[0001]The present invention relates to a shock absorber.
Priority is claimed on Japanese Patent Application No. 2019-118696, filed June 26, 2019, the content of which is incorporated herein by reference. [Background Art] 10 [0002]
In some shock absorbers, two valves are opened in the same stroke (see, for example, Patent Literature 1). [Citation List] [Patent Literature] 15 [0003]
[Patent Literature 1]
Japanese Examined Patent Application, Second Publication No. H2-41666 [Summary of Invention] [Technical Problem] 20 [0004]
With the two valves which are opened in the same stroke, it is possible to open one valve without opening the other valve in a region in which a piston speed is low and to open both valves in a region in which the piston speed is higher than that in the region in which the piston speed is low. In such a structure, abnormal noise may be generated 25 especially at the time of high frequency input.
2

[0005]
An object of the present invention is to provide a shock absorber capable of suppressing the generation of abnormal noise. [Solution to Problem] 5 [0006]
An aspect of the present invention includes: a cylinder which is filled with a working fluid; a piston which is slidably provided in the cylinder and divides an inside of the cylinder into two chambers; a piston rod which is connected to the piston and extends outside the cylinder; a first passage and a second passage through which the working
10 fluid flows due to movement of the piston; a first damping force generating mechanism which is provided in the first passage and generates a damping force; and a second damping force generating mechanism which is provided in the second passage and generates a damping force. The second damping force generating mechanism includes a sub valve provided on one side of the second passage, and a volume variable
15 mechanism that changes a volume of a volume chamber provided in parallel with the second passage. [0007]
Another aspect of the present invention includes: a cylinder which is filled with a working fluid; a piston which is slidably provided in the cylinder and divides an inside
20 of the cylinder into two chambers; a piston rod which is connected to the piston and extends outside the cylinder; a first passage and a second passage through which the working fluid flows due to movement of the piston; a first damping force generating mechanism which is provided in the first passage and generates a damping force; and a second damping force generating mechanism which is provided in the second passage
25 and generates a damping force. The second damping force generating mechanism
3

includes one side sub valve provided on one side of a valve seat member passage portion provided in a valve seat member of the second passage, and a bottomed tubular cap member provided between the piston and the valve seat member in the second passage. The valve seat member is provided in the cap member, and the one side sub valve is 5 provided in a cap chamber between a bottom portion of the cap member and the valve seat member. In the second passage, an orifice is disposed on an upstream side or a downstream side from the one side sub valve in flow by which the one side sub valve is opened. In a region in which a piston speed is low, the one side sub valve is opened in a state in which a valve of the first damping force generating mechanism is closed. In a
10 speed region in which the piston speed is higher than that in the region in which the piston speed is low, the valve of the first damping force generating mechanism and the one side sub valve are both opened. A communication passage communicating with one chamber is formed at the bottom portion of the cap member. In the cap chamber, between the one side sub valve and the bottom portion of the cap member, a movable
15 moving member is provided. A volume variable mechanism is further provided
between the moving member and the one side sub valve, wherein the volume variable mechanism is formed with an intermediate chamber whose volume is changed by movement of the moving member. [0008]
20 Still another aspect of the present invention includes: a cylinder which is filled
with a working fluid; a piston which is slidably provided in the cylinder and divides an inside of the cylinder into two chambers; a piston rod which is connected to the piston and extends outside the cylinder; a first passage and a second passage through which the working fluid flows from the chamber on an upstream side to the chamber on a
25 downstream side in the cylinder due to movement of the piston; a first damping force
4

generating mechanism which is provided in the first passage formed in the piston and generates a damping force; and a second damping force generating mechanism which is provided in an annular valve seat member disposed in one of the two chambers, is provided in the second passage which is parallel to the first passage, and generates a 5 damping force. The second damping force generating mechanism includes a first sub valve provided on one side of a valve seat member passage portion provided in the valve seat member of the second passage and a second sub valve provided on the other side thereof, and a bottomed tubular cap member provided between the piston and the valve seat member in the second passage. The valve seat member is provided in the cap
10 member, the first sub valve is provided in the one chamber, and the second sub valve is provided in a cap chamber between a bottom portion of the cap member and the valve seat member. In the second passage, an orifice is disposed on an upstream side or a downstream side from the first sub valve in flow by which the first sub valve is opened. In a region in which a piston speed is low, a valve of the second damping force
15 generating mechanism is opened in a state in which a valve of the first damping force generating mechanism is closed. In a speed region in which the piston speed is higher than that in the region in which the piston speed is low, the valve of the first damping force generating mechanism and the valve of the second damping force generating mechanism are both opened. A communication passage communicating with the one
20 chamber is formed at the bottom portion of the cap member. In the cap chamber, between the second sub valve and the bottom portion of the cap member, a flexible member that closes the communication passage is provided. An intermediate chamber of which communication with the communication passage is blocked by the flexible member is formed between the flexible member and the second sub valve.
25 [0009]
5

Still another aspect of the present invention includes: a cylinder which is filled with a working fluid; a piston which is slidably provided in the cylinder and divides an inside of the cylinder into two chambers; a piston rod which is connected to the piston and extends outside the cylinder; a first passage and a second passage through which the 5 working fluid flows from the chamber on an upstream side to the chamber on a
downstream side in the cylinder due to movement of the piston; a first damping force generating mechanism which is provided in the first passage formed in the piston and generates a damping force; and a second damping force generating mechanism which is provided in an annular valve seat member disposed in one of the two chambers, is
10 provided in the second passage which is parallel to the first passage, and generates a damping force. The second damping force generating mechanism includes a first sub valve provided on one side of a valve seat member passage portion provided in the valve seat member of the second passage, and a bottomed tubular cap member provided between the piston and the valve seat member in the second passage. The valve seat
15 member is provided in the cap member, and the first sub valve is provided in the one chamber. In the second passage, an orifice is disposed on an upstream side or a downstream side from the first sub valve in flow by which the first sub valve is opened. In a region in which a piston speed is low, a valve of the second damping force generating mechanism is opened in a state in which a valve of the first damping force
20 generating mechanism is closed. In a speed region in which the piston speed is higher than that in the region in which the piston speed is low, the valve of the first damping force generating mechanism and the valve of the second damping force generating mechanism are both opened. A communication passage communicating with the one chamber is formed at the bottom portion of the cap member. A flexible member that
25 closes the communication passage is provided in a cap chamber between the bottom
6

portion of the cap member and the valve seat member. An intermediate chamber of which communication with the communication passage is blocked by the flexible member is formed between the flexible member and the valve seat member. [Advantageous Effects of Invention] 5 [0010]
According to the above-mentioned shock absorber, it is possible to suppress the
generation of abnormal noise.
[Brief Description of Drawings]
[0011]
10 Fig. 1 is a cross-sectional view showing a shock absorber according to a first
embodiment of the present invention.
Fig. 2 is a partial cross-sectional view showing a main part of the shock absorber according to the first embodiment of the present invention.
Fig. 3 is a partial cross-sectional view showing the periphery of a cap member 15 and a valve seat member of the shock absorber according to the first embodiment of the present invention.
Fig. 4A is a perspective view showing the valve seat member of the shock
absorber according to the first embodiment of the present invention from one side in an
axial direction.
20 Fig. 4B is a perspective view showing the valve seat member of the shock
absorber according to the first embodiment of the present invention from the other side in the axial direction.
Fig. 5 is a characteristic diagram showing damping force characteristics of the
shock absorber according to the first embodiment of the present invention.
25 Fig. 6 is a characteristic diagram showing analysis results of rod acceleration
7

and a damping force of the shock absorber according to the first embodiment of the present invention.
Fig. 7 is a partial cross-sectional view showing the periphery of a cap member and a valve seat member of a shock absorber according to a second embodiment of the 5 present invention.
Fig. 8 is a partial cross-sectional view showing the periphery of a cap member and a valve seat member of a shock absorber according to a third embodiment of the present invention.
Fig. 9 is a partial cross-sectional view showing a main part of a shock absorber 10 according to a fourth embodiment of the present invention.
Fig. 10 is a partial cross-sectional view showing the periphery of a cap member and a valve seat member of the shock absorber according to the fourth embodiment of the present invention.
Fig. 11 is a partial cross-sectional view showing a main part of a shock absorber 15 according to a fifth embodiment of the present invention.
Fig. 12 is a partial cross-sectional view showing the periphery of a cap member and a valve seat member of the shock absorber according to the fifth embodiment of the present invention.
Fig. 13 is a hydraulic circuit diagram showing the shock absorber according to 20 the fifth embodiment of the present invention.
Fig. 14 is a partial cross-sectional view showing the periphery of a cap member and a valve seat member of a shock absorber according to a sixth embodiment of the present invention.
Fig. 15 is a characteristic diagram showing a damping force and the like of the 25 shock absorber according to the sixth embodiment of the present invention.
8

Fig. 16 is a characteristic diagram showing a damping force and the like of a shock absorber according to a comparative example.
Fig. 17 is a partial cross-sectional view showing the periphery of a cap member and a valve seat member of a shock absorber according to a seventh embodiment of the 5 present invention.
Fig. 18 is a partial cross-sectional view showing the periphery of a cap member and a valve seat member of a shock absorber according to an eighth embodiment of the present invention.
Fig. 19 is a partial cross-sectional view showing the periphery of a cap member 10 and a valve seat member of a shock absorber according to a ninth embodiment of the present invention.
Fig. 20 is a partial cross-sectional view showing the periphery of a cap member
and a valve seat member of a shock absorber according to a tenth embodiment of the
present invention.
15 Fig. 21 is a hydraulic circuit diagram showing a shock absorber according to an
eleventh embodiment of the present invention.
Fig. 22 is a hydraulic circuit diagram showing a shock absorber according to a twelfth embodiment of the present invention.
Fig. 23 is a partial cross-sectional view showing a main part of a shock absorber 20 according to a thirteenth embodiment of the present invention. [Description of Embodiments] [0012] [First embodiment]
A first embodiment will be described with reference to Figs. 1 to 6. In the 25 following, for convenience of explanation, the upper side in Figs. 1 to 3, 7 to 11, and 23
9

and the left side in Figs. 12, 14, 17 to 20 will be referred to as "upper," and the lower side
in Figs. 1 to 3, 7 to 11, and 23 and the right side in Figs. 12, 14 and 17 to 20 will be
referred to as "lower."
[0013]
5 As shown in Fig. 1, a shock absorber 1 of the first embodiment is a so-called
mono-tube type hydraulic shock absorber and includes a cylinder 2 which is filled with an oil liquid (not shown) as a working fluid. The cylinder 2 has a bottomed cylindrical shape. The cylinder 2 is an integrally formed product including a cylindrical body portion 11 and a bottom portion 12 which is formed on the lower side of the body portion
10 11 and closes the lower portion of the body portion 11. [0014]
The shock absorber 1 has a division body 15 and a piston 18, both of which are slidably provided inside the cylinder 2. The division body 15 is provided between the piston 18 and the bottom portion 12 of the cylinder 2. The piston 18 defines two
15 chambers, that is, an upper chamber 19 and a lower chamber 20, in the cylinder 2, and the division body 15 defines the lower chamber 20 and a gas chamber 16 in the cylinder 2. In other words, the piston 18 is slidably provided in the cylinder 2 and divides the inside of the cylinder 2 into the upper chamber 19 on one side and the lower chamber 20 on the other side. The upper chamber 19 and the lower chamber 20 in the cylinder 2 are
20 filled with an oil liquid as a working fluid, and the gas chamber 16 in the cylinder 2 is filled with a gas. [0015]
The shock absorber 1 includes a piston rod 21 of which one end side portion in an axial direction is disposed inside the cylinder 2 to be connected and fixed to the piston
25 18 and the other end side portion extends outside the cylinder 2. The piston rod 21
10

passes through the upper chamber 19 and does not pass through the lower chamber 20. Therefore, the upper chamber 19 is a rod side chamber through which the piston rod 21 passes, and the lower chamber 20 is a bottom side chamber on the bottom portion 12 side of the cylinder 2. 5 [0016]
The piston 18 and the piston rod 21 move integrally. In an extension stroke of the shock absorber 1 in which the amount of protrusion of the piston rod 21 from the cylinder 2 is increased, the piston 18 moves toward the upper chamber 19. In a contraction stroke of the shock absorber 1 in which the amount of protrusion of the
10 piston rod 21 from the cylinder 2 is decreased, the piston 18 moves toward the lower chamber 20. [0017]
A rod guide 22 is fitted and fixed to an upper end opening side of the cylinder 2, and a seal member 23 is fitted to the upper side which is the outer side of the cylinder 2
15 with respect to the rod guide 22. The upper end portion of the cylinder 2 is swaged inward in a radial direction to form a locking portion 26, and the seal member 23 is interposed between the locking portion 26 and the rod guide 22. A friction member 24 is provided between the rod guide 22 and the seal member 23. [0018]
20 The rod guide 22, the friction member 24, and the seal member 23 all have
annular shapes, and the piston rod 21 is slidably inserted inside each of the rod guide 22, the friction member 24, and the seal member 23 and extends from the inside of the cylinder 2 to the outside thereof. In the piston rod 21, the one end side portion in the axial direction is fixed to the piston 18 inside the cylinder 2, and the other end side
25 portion protrudes outside the cylinder 2 via the rod guide 22, the friction member 24, and
ii

the seal member 23. [0019]
The rod guide 22 supports the piston rod 21 to be movable in the axial direction while restricting movement thereof in a radial direction and guides the movement of the 5 piston rod 21. The seal member 23 is in close contact with the cylinder 2 at the outer peripheral portion thereof and is in sliding contact with the outer peripheral portion of the piston rod 21 moving in the axial direction at the inner peripheral portion thereof. As a result, the seal member 23 prevents the oil liquid in the cylinder 2 from leaking to the outside. The friction member 24 applies a frictional force to the piston rod 21.
10 [0020]
The piston rod 21 has a main shaft portion 27 and an attachment shaft portion 28 having a diameter smaller than that of the main shaft portion 27. In the piston rod 21, the main shaft portion 27 is slidably fitted to the rod guide 22, the friction member 24, and the seal member 23, and the attachment shaft portion 28 is disposed in the cylinder 2
15 and is connected to the piston 18 and the like. The end portion of the main shaft portion 27 on the attachment shaft portion 28 side is a shaft step portion 29 extending in a direction orthogonal to an axis. [0021]
In the outer peripheral portion of the attachment shaft portion 28, at an
20 intermediate position thereof in the axial direction, a passage cutout portion 30 extending in the axial direction is formed, and at a tip end position on a side opposite to the main shaft portion 27 in the axial direction, a male screw 31 is formed. The passage cutout portion 30 is formed by, for example, being cut out of the outer peripheral portion of the attachment shaft portion 28 to have a flat shape in a surface parallel to the central axis of
25 the attachment shaft portion 28. The passage cutout portion 30 can be formed in a
12

so-called two-sided width shape at two positions of the attachment shaft portion 28 which are located at intervals of 180 degrees in a circumferential direction. [0022]
The piston rod 21 is provided with a stopper member 32, a pair of supports 33, a 5 coil spring 34, and a buffer 35, which are all annular, at a portion between the piston 18 of the main shaft portion 27 and the rod guide 22. The piston rod 21 is inserted through an inner peripheral side of the stopper member 32, and the stopper member 32 is swaged and fixed to the main shaft portion 27. One support 33, the coil spring 34, the other support 33, and the buffer 35 are disposed in that order from a side of the stopper
10 member 32. [0023]
The piston rod 21 is inserted inside the pair of supports 33 and the coil spring 34, and the pair of supports 33 and the coil spring 34 are disposed between the stopper member 32 and the rod guide 22. The piston rod 21 is inserted inside the buffer 35, and
15 the buffer 35 is disposed between the other support 33 and the rod guide 22. In the stopper member 32, the pair of supports 33, the coil spring 34, and the buffer 35, when the piston rod 21 protrudes a predetermined length from the cylinder 2, the buffer 35 comes into contact with the rod guide 22, and the buffer 35 and the coil spring 34 are elastically deformed.
20 [0024]
In the shock absorber 1, for example, a protruding portion of the piston rod 21 from the cylinder 2 is disposed at the upper portion and is supported by a vehicle body, and the bottom portion 12 of the cylinder 2 is disposed at the lower portion and is connected to a wheel side. In contrast to this, the cylinder 2 side may be supported by
25 the vehicle body and the piston rod 21 may be connected to the wheel side.
13

[0025]
As shown in Fig. 2, the piston 18 is constituted by a piston main body 36 which
is made of a metal and is connected to the piston rod 21 and an annular sliding member
37 which is made of a resin, is integrally mounted on the outer peripheral surface of the 5 piston main body 36, and slides in the cylinder 2.
[0026]
The piston main body 36 is provided with a plurality of (only one is shown in
Fig. 2 due to the cross section) passage holes 38 through which the upper chamber 19 and
the lower chamber 20 can communicate with each other and a plurality of (only one is 10 shown in Fig. 2 due to the cross section) passage holes 39 through which the upper
chamber 19 and the lower chamber 20 can communicate with each other.
[0027]
The plurality of passage holes 38 are formed at equal pitches with one passage
hole 39 interposed therebetween in a circumferential direction of the piston main body 36, 15 and the number of the passage holes 38 is half of the total number of the passage holes 38
and 39. The plurality of passage holes 38 have a crank shape with two bending points.
In the passage holes 38, one side in the axial direction of the piston 18 (an upper side in
Fig. 2) is open on the outer side of the piston 18 in the radial direction, and the other side
in the axial direction of the piston 18 (a lower side in Fig. 2) is open on the inner side of 20 the piston 18 in the radial direction with respect to the one side. An annular groove 55
which allows the plurality of passage holes 38 to communicate with the lower chamber
20 side in the axial direction is formed in the piston main body 36.
[0028]
On the lower chamber 20 side of the annular groove 55, a first damping force 25 generating mechanism 41 that opens and closes a passage in the annular groove 55 and
14

the plurality of passage holes 38 to generate a damping force is provided. Due to the first damping force generating mechanism 41 disposed on the lower chamber 20 side, the passage in the plurality of passage holes 38 and the annular groove 55 becomes a passage on an extension side through which the oil liquid flows from the upper chamber 19 which 5 becomes an upstream side toward the lower chamber 20 which becomes a downstream side at the time of the movement of the piston 18 toward the upper chamber 19, that is, in the extension stroke. The first damping force generating mechanism 41 provided for the passage in the plurality of passage holes 38 and the annular groove 55 is a damping force generating mechanism on an extension side which suppresses the flow of the oil
10 liquid from the passage in the plurality of passage holes 38 and the annular groove 55 on an extension side toward the lower chamber 20 to generate a damping force. [0029]
The passage holes 39 of which the number is the other half of the total number of the passage holes 38 and 39 are formed at equal pitches with one passage hole 38
15 interposed therebetween in the circumferential direction of the piston main body 36. The plurality of passage holes 39 have a crank shape with two bending points. In the plurality of passage holes 39, the other side in the axial direction of the piston 18 (a lower side in Fig. 2) is open on the outer side of the piston 18 in the radial direction, and one side in the axial direction of the piston 18 (an upper side in Fig. 2) is open on the inner
20 side of the piston 18 in the radial direction with respect to the other side. An annular groove 56 which allows the plurality of passage holes 39 to communicate with the upper chamber 19 side in the axial direction is formed in the piston main body 36. [0030]
On the upper chamber 19 side of the annular groove 56, a first damping force
25 generating mechanism 42 that opens and closes a passage in the plurality of passage
15

holes 39 and the annular groove 56 to generate a damping force is provided. Due to the first damping force generating mechanism 42 disposed on the upper chamber 19 side, the passage in the plurality of passage holes 39 and the annular groove 56 becomes a passage on a contraction side through which the oil liquid flows from the lower chamber 20 5 which becomes an upstream side toward the upper chamber 19 which becomes a
downstream side at the time of the movement of the piston 18 toward the lower chamber 20, that is, in the contraction stroke. The first damping force generating mechanism 42 provided for the passage in the plurality of passage holes 39 and the annular groove 56 is a damping force generating mechanism on a contraction side which suppresses the flow
10 of the oil liquid from the passage in the plurality of passage holes 39 and the annular groove 56 on a contraction side toward the upper chamber 19 to generate a damping force. [0031]
The piston main body 36 has substantially a disk shape. In the center of the
15 piston main body 36 in the radial direction, an insertion hole 44 into which the
attachment shaft portion 28 of the piston rod 21 is inserted is formed to penetrate the piston main body 36 in the axial direction. The insertion hole 44 has a small-diameter hole portion 45 on one side in the axial direction to which the attachment shaft portion 28 of the piston rod 21 is fitted and a large-diameter hole portion 46 on the other side in the
20 axial direction which has a diameter larger than that of the small-diameter hole portion 45. The small-diameter hole portion 45 is provided on the upper chamber 19 side in the axial direction, and the large-diameter hole portion 46 is provided on the lower chamber 20 side in the axial direction. [0032]
25 In the end portion of the piston main body 36 on the lower chamber 20 side in
16

the axial direction, an annular inner seat portion 47 is formed on the inner side of the piston main body 36 in the radial direction with respect to an opening of the annular groove 55 on the lower chamber 20 side. Further, in the end portion of the piston main body 36 on the lower chamber 20 side in the axial direction, an annular valve seat portion 5 48 constituting a part of the first damping force generating mechanism 41 is formed on the outer side of the piston main body 36 in the radial direction with respect to the opening of the annular groove 55 on the lower chamber 20 side. [0033]
In the end portion of the piston main body 36 on the upper chamber 19 side in 10 the axial direction, an annular inner seat portion 49 is formed on the inner side of the piston main body 36 in the radial direction with respect to an opening of the annular groove 56 on the upper chamber 19 side. Further, in the end portion of the piston main body 36 on the upper chamber 19 side in the axial direction, an annular valve seat portion
50 constituting a part of the first damping force generating mechanism 42 is formed on
15 the outer side of the piston main body 36 in the radial direction with respect to the
opening of the annular groove 56 on the upper chamber 19 side. [0034]
In the insertion hole 44 of the piston main body 36, the large-diameter hole portion 46 is provided on the inner seat portion 47 side in the axial direction with respect 20 to the small-diameter hole portion 45. The passage in the large-diameter hole portion 46 of the piston main body 36 constantly communicates with a piston rod passage portion
51 in the passage cutout portion 30 of the piston rod 21 with the positions thereof in the
axial direction overlapping.
[0035]
25 The outer side of the piston main body 36 in the radial direction with respect to
17

the valve seat portion 48 has a stepped shape having an axial height lower than that of the valve seat portion 48. An opening of the passage hole 39 on the lower chamber 20 side on a contraction side is disposed in this stepped portion. Further, similarly, the outer side of the piston main body 36 in the radial direction with respect to the valve seat 5 portion 50 has a stepped shape having an axial height lower than that of the valve seat portion 50. An opening of the passage hole 38 on the upper chamber 19 side on an extension side is disposed in this stepped portion. [0036]
The first damping force generating mechanism 42 on a contraction side includes
10 the valve seat portion 50 of the piston 18 and has, in order from the piston 18 side in the axial direction, a plurality of (specifically two) disks 62 having the same inner diameter and the same outer diameter, one disk 63, a plurality of (specifically four) disks 64 having the same inner diameter and the same outer diameter, a plurality of (specifically two) disks 65 having the same inner diameter and the same outer diameter, a plurality of
15 (specifically four) disks 66 having the same inner diameter and having outer diameters which decrease as the distance from the piston 18 increases in the axial direction, one disk 67, one disk 68, and one annular member 69. The disks 62 to 68 and the annular member 69 are made of a metal and each have a perforated circular flat plate shape having a constant thickness into which the attachment shaft portion 28 of the piston rod
20 21 can be fitted. The disks 62 to 68 are plain disks (flat disks without protrusions). [0037]
The disk 62 has an outer diameter larger than the outer diameter of the inner seat portion 49 of the piston 18 and smaller than the inner diameter of the valve seat portion 50 of the piston 18 and is constantly in contact with the inner seat portion 49. The disk
25 63 has an outer diameter larger than the outer diameter of the disk 62 and smaller than
18

the inner diameter of the valve seat portion 50. The plurality of disks 64 have an outer
diameter equal to the outer diameter of the valve seat portion 50 of the piston 18 and can
be seated on the valve seat portion 50.
[0038]
5 The plurality of disks 65 have an outer diameter smaller than the outer diameter
of the disk 64. The largest outer diameter disk of the plurality of disks 66 has an outer diameter smaller than the outer diameter of the disk 65. The disk 67 has an outer diameter smaller than the outer diameter of the smallest outer diameter disk of the disks 66 and equal to the outer diameter of the inner seat portion 49 of the piston 18. The
10 disk 68 has an outer diameter larger than the outer diameter of the smallest outer
diameter disk of the disks 66 and smaller than the outer diameter of the largest outer diameter disk of the disks 66. The annular member 69 has an outer diameter smaller than the outer diameter of the disk 68 and larger than the outer diameter of the shaft step portion 29 of the piston rod 21. The annular member 69 is thicker and more rigid than
15 the disks 62 to 68 and is in contact with the shaft step portion 29. [0039]
The plurality of disks 64, the plurality of disks 65, and the plurality of disks 66 constitute a main valve 71 on a contraction side which can be detached and seated with respect to the valve seat portion 50. When the main valve 71 is separated from the
20 valve seat portion 50, the main valve 71 allows the passage in the plurality of passage holes 39 and the annular groove 56 to communicate with the upper chamber 19 and suppresses the flow of oil liquid with the valve seat portion 50 to generate a damping force. The annular member 69, together with the disk 68, restricts the deformation of the main valve 71 in an opening direction beyond a specified value by coming into
25 contact with the main valve 71.
19

[0040]
The passage in the plurality of passage holes 39 and the annular groove 56 and the passage between the main valve 71 and the valve seat portion 50 which appears when the valve is opened constitute a first passage 72 on a contraction side through which the 5 oil liquid flows from the lower chamber 20 which becomes an upstream side in the
cylinder 2 to the upper chamber 19 which becomes a downstream side in the cylinder 2 by the movement of the piston 18 toward the lower chamber 20 side. The first damping force generating mechanism 42 on a contraction side which generates a damping force includes the main valve 71 and the valve seat portion 50 and is therefore provided in the
10 first passage 72. The first passage 72 is formed in the piston 18 including the valve seat portion 50, and the oil liquid passes through the first passage 72 when the piston rod 21 and the piston 18 move to the contraction side. [0041]
Here, in the first damping force generating mechanism 42 on a contraction side,
15 in each of the valve seat portion 50 and the main valve 71 in contact therewith, a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to communicate with each other even when the valve seat portion 50 and the main valve 71 are in contact with each other is not formed. That is, the first damping force generating mechanism 42 on a contraction side does not allow the upper chamber 19 and the lower chamber 20 to
20 communicate with each other if the valve seat portion 50 and the main valve 71 are in contact with each other over the entire circumference. In other words, a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to constantly communicate with each other is not formed in the first passage 72, and thus the first passage 72 is not a passage that allows the upper chamber 19 and the lower chamber 20 to constantly
25 communicate with each other.
20

[0042]
The first damping force generating mechanism 41 on an extension side includes the valve seat portion 48 of the piston 18 and has, in order from the piston 18 side in the axial direction, one disk 82, one disk 83, one disk 84, a plurality of (specifically four) 5 disks 85 having the same inner diameter and the same outer diameter, one disk 86, a
plurality of (specifically two) disks 87 having the same inner diameter and the same outer diameter, a plurality of (specifically two) disks 88 having the same inner diameter and having outer diameters which decrease as the distance from the piston 18 increases in the axial direction, and one disk 89. The disks 82 to 89 are made of a metal, and all of them
10 are plain disks that each have a perforated circular flat plate shape having a constant thickness into which the attachment shaft portion 28 of the piston rod 21 can be fitted. [0043]
The disk 82 has an outer diameter larger than the outer diameter of the inner seat portion 47 of the piston 18 and smaller than the inner diameter of the valve seat portion
15 48 of the piston 18 and is constantly in contact with the inner seat portion 47. As shown in Fig. 3, in the disk 82, a cutout portion 90 that allows the passage in the annular groove 55 and the plurality of passage holes 38 to constantly communicate with the passage in the large-diameter hole portion 46 of the piston 18 and the piston rod passage portion 51 in the passage cutout portion 30 of the piston rod 21 is formed from an intermediate
20 position outside the inner seat portion 47 in the radial direction to the inner peripheral edge portion in the radial direction. The cutout portion 90 is formed during press forming of the disk 82. The cutout portion 90 faces the large-diameter hole portion 46 of the piston 18 to be adjacent thereto. The disk 83 has the same outer diameter as the disk 82, and the cutout portion as in the disk 82 is not formed in the disk 83. The disk
25 84 has an outer diameter larger than the outer diameter of the disk 83 and smaller than
21

the inner diameter of the valve seat portion 48. [0044]
The plurality of disks 85 have an outer diameter equal to the outer diameter of the valve seat portion 48 of the piston 18 and can be seated on the valve seat portion 48. 5 The disk 86 has an outer diameter smaller than the outer diameter of the disk 85. The plurality of disks 87 have an outer diameter smaller than the outer diameter of the disk 86. The larger outer diameter disk of the plurality of disks 88 has an outer diameter smaller than the outer diameter of the disk 87. The disk 89 has an outer diameter smaller than the outer diameter of the smaller outer diameter disk of the plurality of disks 88 and
10 equal to the outer diameter of the inner seat portion 47 of the piston 18. As shown in Fig. 2, the disk 89 can be a common part having the same shape as the disk 67. The plurality of disks 88 are thicker and more rigid than the disks 85 to 87. [0045]
The plurality of disks 85, the one disk 86, the plurality of disks 87, and the
15 plurality of disks 88 constitute a main valve 91 on an extension side which can be
detached and seated with respect to the valve seat portion 48. When the main valve 91 is separated from the valve seat portion 48, the main valve 91 allows the passage in the annular groove 55 and the plurality of passage holes 38 to communicate with the lower chamber 20 and suppresses the flow of oil liquid with the valve seat portion 48 to
20 generate a damping force. [0046]
The passage in the plurality of passage holes 38 and the annular groove 55 and the passage between the main valve 91 and the valve seat portion 48 which appears when the valve is opened constitute a first passage 92 on an extension side through which the
25 oil liquid flows from the upper chamber 19 which becomes an upstream side in the
22

cylinder 2 to the lower chamber 20 which becomes a downstream side in the cylinder 2 by the movement of the piston 18 toward the upper chamber 19 side. The first damping force generating mechanism 41 on an extension side which generates a damping force includes the main valve 91 and the valve seat portion 48 and is therefore provided in the 5 first passage 92. The first passage 92 is formed in the piston 18 including the valve seat portion 48, and the oil liquid passes through the first passage 92 when the piston rod 21 and the piston 18 move to the extension side. [0047]
In the first damping force generating mechanism 41 on an extension side, in
10 each of the valve seat portion 48 and the main valve 91 in contact therewith, a fixed
orifice that allows the upper chamber 19 and the lower chamber 20 to communicate with each other even when the valve seat portion 48 and the main valve 91 are in contact with each other is not formed. That is, the first damping force generating mechanism 41 on an extension side does not allow the upper chamber 19 and the lower chamber 20 to
15 communicate with each other if the valve seat portion 48 and the main valve 91 are in contact with each other over the entire circumference. In other words, a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to constantly communicate with each other is not formed in the first passage 92, and thus the first passage 92 is not a passage that allows the upper chamber 19 and the lower chamber 20 to constantly
20 communicate with each other. [0048]
As shown in Fig. 3, on a side of the first damping force generating mechanism 41 on an extension side opposite to the piston 18, in order from the first damping force generating mechanism 41 side, one cap member 101, one flexible disk 100 (a flexible
25 member or a moving member), a plurality of (specifically two) disks 102, one sub valve
23

107 (a second sub valve), one valve seat member 109 provided with one O-ring 108 on the outer peripheral side thereof, one sub valve 110 (a first sub valve), one disk 111, one disk 113, and a plurality of (specifically two) annular members 114 shown in Fig. 2 are provided such that the attachment shaft portion 28 of the piston rod 21 is fitted to the 5 inside of each of them. In the attachment shaft portion 28 of the piston rod 21, at a
portion protruding with respect to the annular member 114, the male screw 31 is formed, and a nut 115 is screwed onto the male screw 31. The nut 115 is in contact with the annular member 114. [0049]
10 The flexible disk 100, the cap member 101, the disks 102, 111, and 113, the sub
valves 107 and 110, the valve seat member 109, and the annular member 114 are all made of a metal. The disks 102, 111, and 113, the sub valve 107 and 110, and the annular member 114 each have a perforated circular flat plate shape having a constant thickness into which the attachment shaft portion 28 of the piston rod 21 can be fitted.
15 The disks 102, 111, and 113 and the sub valves 107 and 110 are plain disks. The flexible disk 100, the cap member 101, and the valve seat member 109 each have an annular shape into which the attachment shaft portion 28 of the piston rod 21 can be fitted. [0050]
20 The cap member 101 is an integrally formed product having a bottomed tubular
shape and is integrally formed by, for example, plastic working or cutting of a metal plate. As shown in Fig. 3, the cap member 101 has a bottom portion 122 having a perforated circular plate shape and a constant thickness, an intermediate tapered portion 123 that extends from the outer peripheral edge portion of the bottom portion 122 while
25 expanding in diameter to one side of the bottom portion 122 in the axial direction, and a
24

cylindrical tubular portion 124 that extends from the end edge portion of the intermediate
tapered portion 123 on a side opposite to the bottom portion 122 in a direction opposite
to the bottom portion 122.
[0051]
5 The bottom portion 122 has a perforated circular plate shape in which the
attachment shaft portion 28 of the piston rod 21 is fitted to the inner peripheral portion thereof. When the attachment shaft portion 28 is fitted to the inner peripheral portion of the bottom portion 122, the cap member 101 is positioned with respect to the piston rod 21 in the radial direction and is disposed coaxially therewith. A plurality of passage
10 holes 126 that penetrate the bottom portion 122 in the axial direction of the bottom portion 122 is formed between the inner peripheral portion and the outer peripheral portion of the bottom portion 122. The plurality of passage holes 126 are disposed at positions equidistant from the center of the bottom portion 122 at equal intervals in a circumferential direction of the bottom portion 122 and are formed on the outer
15 peripheral portion side with respect to the center between the inner peripheral portion and the outer peripheral portion of the bottom portion 122. The cap member 101 is disposed in an orientation in which the bottom portion 122 is located closer to the piston 18 than the tubular portion 124, is in contact with the disk 89, and is fitted to the attachment shaft portion 28 at the inner peripheral portion of the bottom portion 122.
20 [0052]
The cap member 101 is thicker than the disks 85 to 88, has a bottomed tubular shape, and has higher rigidity than the disks 85 to 88. Therefore, the cap member 101 restricts the deformation of the main valve 91 constituted by the plurality of disks 85 to 88 in an opening direction beyond a specified value by coming into contact with the main
25 valve 91.
25

[0053]
The flexible disk 100 has a main body portion 301 and a disk protruding portion 302 (a flexible member side protruding portion) protruding from the main body portion 301. The main body portion 301 has a perforated circular flat plate shape having a 5 constant thickness in a natural state before being assembled to the shock absorber 1, and the inner peripheral surface and the outer peripheral surface of the main body portion 301 are coaxial. The disk protruding portion 302 protrudes from the main body portion 301 toward one side of the main body portion 301 in the axial direction. The disk protruding portion 302 has an annular shape coaxial with the main body portion 301 and
10 is formed on the outer peripheral surface side with respect to the central position between the inner peripheral surface and the outer peripheral surface of the main body portion 301. The attachment shaft portion 28 of the piston rod 21 can be fitted into the main body portion 301. When the attachment shaft portion 28 is fitted to the inner peripheral portion of the main body portion 301, the flexible disk 100 is positioned with respect to
15 the piston rod 21 in the radial direction and is disposed coaxially therewith. [0054]
The flexible disk 100 is formed by the press forming from a single plate material having a constant thickness, and thus the main body portion 301 and the disk protruding portion 302 are integrally formed with each other. The disk protruding portion 302
20 extends from the outer peripheral side of the main body portion 301 while the diameter is reduced in a tapered shape to one side in the axial direction, then folds back at an inner side in the radial direction toward the other side in the axial direction, and extends while the diameter is reduced in a tapered shape to the other side in the axial direction to join the main body portion 301. In other words, the cross-sectional shape of the disk
25 protruding portion 302 at a surface including the central axis of the flexible disk 100 has
26

a tapered V-shape in which the width in the radial direction becomes narrower as the distance from the main body portion 301 in the axial direction increases. The disk protruding portion 302 has an axisymmetric shape. The disk protruding portion 302 has a circular shape in which an apex on a side opposite to the main body portion 301 in the 5 axial direction of the flexible disk 100 is concentric with the inner peripheral portion and the outer peripheral portion of the flexible disk 100, and the height of the disk protruding portion 302 from the main body portion 301 is constant over the entire circumference. [0055]
The flexible disk 100 is housed in the cap member 101, the disk protruding
10 portion 302 is oriented to protrude from the main body portion 301 toward the bottom portion 122 in the axial direction, and the disk protruding portion 302 is in contact with the bottom portion 122. The disk 102 has an outer diameter smaller than the minimum inner diameter of the disk protruding portion 302. The flexible disk 100 is interposed between the disk 102 and the bottom portion 122 on the inner peripheral side of the main
15 body portion 301 and is incorporated in the shock absorber 1. As a result, the main body portion 301 is elastically deformed in a tapered shape to be separated from the bottom portion 122 in the axial direction toward the outer side in the radial direction. [0056]
In a state in which the flexible disk 100 is incorporated in the shock absorber 1,
20 the inner diameter of a tip end surface of the disk protruding portion 302 in contact with the bottom portion 122 is larger than twice the maximum distance from the center of the bottom portion 122 to each of the plurality of passage holes 126. As a result, the flexible disk 100 is disposed such that the annular disk protruding portion 302 surrounds the entire plurality of passage holes 126 on the outer side in the radial direction of the
25 bottom portion 122 and is in contact with the bottom portion 122 over the entire
27

circumference. [0057]
In the flexible disk 100, a portion of the inner peripheral portion of the main body portion 301 which overlaps the disk 102 is an inner peripheral side contact portion 5 303 that is constantly in contact with the disk 102 and the bottom portion 122 of the cap member 101 over the entire circumference. The outer diameter of the inner peripheral side contact portion 303 is smaller than twice the minimum distance from the center of the bottom portion 122 to each of the plurality of passage holes 126. As a result, the flexible disk 100 is disposed such that the inner peripheral side contact portion 303
10 surrounds the entire plurality of passage holes 126 on the inner side in the radial direction of the bottom portion 122 and is in contact with the bottom portion 122 over the entire circumference. [0058]
In a state in which the flexible disk 100 is incorporated in the shock absorber 1,
15 the main body portion 301 constitutes the inner peripheral side contact portion 303, a flexible portion 305 between the inner peripheral side contact portion 303 and the disk protruding portion 302, and an outer peripheral edge portion 306 on the outer side in the radial direction with respect to the disk protruding portion 302. Here, the outer peripheral edge portion 306 has an outer diameter smaller than the minimum inner
20 diameter of the intermediate tapered portion 123 of the cap member 101, and thus the flexible disk 100 does not comes into contact with the intermediate tapered portion 123 and the tubular portion 124. The flexible disk 100 has a tapered shape such that the flexible portion 305 and the outer peripheral edge portion 306 are separated from the bottom portion 122 in the axial direction toward the outer side in the radial direction.
25 The flexible disk 100 can be elastically deformed such that the flexible portion 305
28

approaches the bottom portion 122 or returns to its original state. [0059]
The valve seat member 109 has a perforated circular plate shape in which a through hole 131 extending in the axial direction and penetrating in a thickness direction 5 through which the attachment shaft portion 28 is inserted is formed in the center in the radial direction. The through hole 131 has a small-diameter hole portion 132 on one side in the axial direction to which the attachment shaft portion 28 of the piston rod 21 is fitted and a large-diameter hole portion 133 on the other side in the axial direction which has a diameter larger than that of the small-diameter hole portion 132.
10 [0060]
As shown in Fig. 4A, the valve seat member 109 has an inner seat portion 134 having an annular shape that surrounds the large-diameter hole portion 133 at an end portion on the large-diameter hole portion 133 side in the axial direction and a valve seat portion 135 that extends outward in the radial direction from the inner seat portion 134.
15 Further, as shown in Fig. 4B, the valve seat member 109 has an inner seat portion 138 having an annular shape that surrounds the small-diameter hole portion 132 at an end portion on the small-diameter hole portion 132 side opposite to the large-diameter hole portion 133 in the axial direction and a valve seat portion 139 that extends outward in the radial direction from the inner seat portion 138. In the valve seat member 109, a portion
20 among the inner seat portion 134, the valve seat portion 135, the inner seat portion 138, and the valve seat portion 139 in the axial direction is a main body portion 140 having a perforated circular plate shape. [0061]
As shown in Fig. 4A, the inner seat portion 134 protrudes from the inner
25 peripheral edge portion on the large-diameter hole portion 133 side of the main body
29

portion 140 in the axial direction to one side of the main body portion 140 in the axial direction, and the valve seat portion 135 also protrudes from the main body portion 140 to the same side as the inner seat 134 in the axial direction of the main body 140 at the outer side of the inner seat 134 in the radial direction. In the inner seat portion 134 and 5 the valve seat portion 135, tip end surfaces on the protruding side, that is, tip end surfaces on a side opposite to the main body portion 140, are flat surfaces and extend in a direction orthogonal to an axis of the valve seat member 109 to be disposed in the same plane. [0062]
10 As shown in Fig. 4B, the inner seat portion 138 protrudes from the inner
peripheral edge portion on the small-diameter hole portion 132 side of the main body portion 140 in the axial direction to a side opposite to the inner seat portion 134 of the main body portion 140 in the axial direction, and the valve seat portion 139 also protrudes from the main body portion 140 to the same side as the inner seat 138 in the
15 axial direction of the main body 140 at the outer side of the inner seat 138 in the radial direction. In the inner seat portion 138 and the valve seat portion 139, tip end surfaces on the protruding side, that is, tip end surfaces on a side opposite to the main body portion 140, are flat surfaces and extend in a direction orthogonal to an axis of the valve seat member 109 to be disposed in the same plane. The inner seat portions 134 and 138
20 have the same outer diameter. [0063]
As shown in Fig. 4A, the valve seat portion 135 is a deformed seat having a petal shape, and has a plurality of, specifically four, valve seat constituent portions 201. These valve seat constituent portions 201 have the same shape and are disposed at equal
25 intervals in the circumferential direction of the valve seat member 109.
30

[0064]
The inner seat portion 134 has an annular shape centered on the central axis of the valve seat member 109. Each of the valve seat constituent portions 201 has a pair of extension portions 202 that extend outward in the radial direction from the inner seat 5 portion 134 and a connecting portion 203 that connects end portions of the pair of extension portions 202 on a side opposite to the inner seat portion 134. The pair of extension portions 202 each have a linear shape and are mirror-symmetrical with respect to a surface including the central axis of the valve seat member 109. The pair of extension portions 202 are disposed to be perpendicular to each other when seen in the
10 axial direction of the valve seat member 109. The connecting portion 203 has an arc shape centered on the central axis of the valve seat member 109. [0065]
A passage recess 205 which is surrounded by the valve seat constituent portion 201 and a part of the inner seat portion 134 that connects the pair of extension portions
15 202 to each other and is recessed from the tip end surfaces on the protruding side thereof in the axial direction of the valve seat member 109 is formed. A bottom surface of the passage recess 205 is formed by the main body portion 140. The passage recess 205 is formed inside each of the valve seat constituent portions 201. All the passage recesses 205 are formed at positions equidistant from the central axis of the valve seat member
20 109 and are formed at equal intervals in the circumferential direction of the valve seat member 109. [0066]
At the central position of the passage recess 205 in the circumferential direction of the valve seat member 109, a passage hole 206 that penetrates the main body portion
25 140 in the axial direction to penetrate the valve seat member 109 in the axial direction is
31

formed. The passage hole 206 is a linear hole parallel to the central axis of the valve seat member 109. The passage hole 206 is formed in a bottom surface of each of the passage recesses 205. All the passage holes 206 are formed at positions equidistant from the central axis of the valve seat member 109 and are formed at equal intervals in 5 the circumferential direction of the valve seat member 109. [0067]
The adjacent extension portions 202 of the valve seat constituent portions 201 disposed adjacent to each other in the circumferential direction of the valve seat member 109 are separated from each other in the circumferential direction of the valve seat
10 member 109, are parallel to each other, and are parallel to a line in the radial direction which passes through the central axis of the valve seat member 109. The extension portions 202 on a far side in the circumferential direction of the valve seat constituent portions 201 disposed adjacent to each other in the circumferential direction of the valve seat member 109 are disposed on the same straight line parallel to the line in the radial
15 direction which passes through the central axis of the valve seat member 109. [0068]
As shown in Fig. 4B, the valve seat portion 139 is a deformed seat having a petal shape, and has a plurality of, specifically four, valve seat constituent portions 211. These valve seat constituent portions 211 have the same shape and are disposed at equal
20 intervals in the circumferential direction of the valve seat member 109. The valve seat constituent portions 211 have the same shapes as the valve seat constituent portions 201. [0069]
The inner seat portion 138 has an annular shape centered on the central axis of the valve seat member 109. Each of the valve seat constituent portions 211 has a pair of
25 extension portions 212 that extend outward in the radial direction from the inner seat
32

portion 138 and a connecting portion 213 that connects end portions of the pair of extension portions 212 on a side opposite to the inner seat portion 138. The pair of extension portions 212 each have a linear shape and are mirror-symmetrical with respect to a surface including the central axis of the valve seat member 109. The pair of 5 extension portions 212 are disposed to be perpendicular to each other when seen in the axial direction of the valve seat member 109. The connecting portion 213 has an arc shape centered on the central axis of the valve seat member 109. The outer diameter of outer edge portions disposed on the same circle of all the connecting portions 213 is the same as the outer diameter of outer edge portions disposed on the same circle of all the
10 connecting portions 203, and the inner diameter of inner edge portions disposed on the same circle of all the connecting portions 213 is the same as the inner diameter of inner edge portions disposed on the same circle of all the connecting portions 203. [0070]
A passage recess 215 which is surrounded by the valve seat constituent portion
15 211 and a part of the inner seat portion 138 that connects the pair of extension portions 212 to each other and is recessed from the tip end surfaces on the protruding side thereof in the axial direction of the valve seat member 109 is formed. A bottom surface of the passage recess 215 is formed by the main body portion 140. The passage recess 215 is formed inside each of the valve seat constituent portions 211. All the passage recesses
20 215 are formed at positions equidistant from the central axis of the valve seat member 109 and are formed at equal intervals in the circumferential direction of the valve seat member 109. [0071]
At the central position of the passage recess 215 in the circumferential direction
25 of the valve seat member 109, a passage hole 216 that penetrates the main body portion
33

140 in the axial direction to penetrate the valve seat member 109 in the axial direction is formed. The passage hole 216 is a linear hole parallel to the central axis of the valve seat member 109. The passage hole 216 is formed in a bottom surface of each of the passage recesses 215. All the passage holes 216 are formed at positions equidistant 5 from the central axis of the valve seat member 109 and are formed at equal intervals in the circumferential direction of the valve seat member 109. [0072]
The adjacent extension portions 212 of the valve seat constituent portions 211 disposed adjacent to each other in the circumferential direction of the valve seat member
10 109 are separated from each other in the circumferential direction of the valve seat member 109, are parallel to each other, and are parallel to a line in the radial direction which passes through the central axis of the valve seat member 109. The extension portions 212 on a far side in the circumferential direction of the valve seat constituent portions 211 disposed adjacent to each other in the circumferential direction of the valve
15 seat member 109 are disposed on the same straight line parallel to the line in the radial direction which passes through the central axis of the valve seat member 109. [0073]
Here, a disposition pitch of the plurality of valve seat constituent portions 201 in the circumferential direction of the valve seat members 109 and a disposition pitch of the
20 plurality of valve seat constituent portions 211 in the circumferential direction of the
valve seat members 109 are the same, and the valve seat constituent portions 201 and the valve seat component portion 211 are shifted from each other by half a pitch. In other words, the central position of the valve seat constituent portion 211 is disposed at the central position between the valve seat constituent portion 201 and the valve seat
25 constituent portion 201 which are adjacent to each other in the circumferential direction
34

of the valve seat member 109, and conversely, the central position of the valve seat constituent portion 201 is disposed at the central position between the valve seat constituent portion 211 and the valve seat constituent portion 211 which are adjacent to each other in the circumferential direction of the valve seat member 109. 5 [0074]
All the passage recesses 205 and all the passage recesses 215 are formed at positions equidistant from the central axis of the valve seat member 109, and the passage recesses 205 and the passage recesses 215 are alternately disposed in a staggered shape in the circumferential direction of the valve seat member 109. All the passage holes 206
10 and all the passage holes 216 are formed at positions equidistant from the central axis of the valve seat member 109, and the passage holes 206 and the passage holes 216 are alternately provided at equal intervals on the same circumference. [0075]
As shown in Fig. 4B, the passage hole 206 is disposed between the valve seat
15 constituent portion 211 and the valve seat constituent portion 211 which are adjacent to each other in the circumferential direction of the valve seat member 109, and thus the passage hole 206 is disposed outside a range of the valve seat portion 139. As shown in Fig. 4A, the passage hole 216 is disposed between the valve seat constituent portion 201 and the valve seat constituent portion 201 which are adjacent to each other in the
20 circumferential direction of the valve seat member 109, and thus the passage hole 216 is disposed outside a range of the valve seat portion 135. [0076]
In the valve seat member 109, a passage groove 221 that crosses the inner seat portion 134 in the radial direction is formed on the large-diameter hole portion 133 side
25 in the axial direction over the inner seat portion 134 and the main body portion 140.
35

The passage groove 221 is formed to be recessed from the tip end surface of the inner seat portion 134 on a side opposite to the main body portion 140 in the axial direction of the valve seat member 109 and to be further recessed than the end surface of the main body portion 140 on the inner seat portion 134 side. The passage groove 221 is 5 provided along a line in the radial direction which passes through the center of the valve seat member 109 on the line in the radial direction and extends inward in the radial direction of the valve seat member 109 from the passage hole 216 that is open between the valve seat constituent portion 201 and the valve seat constituent portion 201 to be connected to the large-diameter hole portion 133. The passage groove 221 is provided
10 for each of the passage holes 216. A plurality of, specifically four, passage grooves 221 are provided at equal intervals in the circumferential direction of the valve seat member 109 with the positions aligned in the radial direction of the valve seat member 109. The inner seat portion 134 is formed intermittently in the circumferential direction by the formation of the passage groove 221.
15 [0077]
As shown in Fig. 3, the passage hole 216 and the passage recess 215 to which the passage hole 216 is open form a first passage portion 151 provided in the valve seat member 109. In the valve seat member 109, a plurality of, specifically four, first passage portions 151 are provided at equal intervals in the circumferential direction of
20 the valve seat member 109 with the positions aligned in the radial direction of the valve seat member 109. In other words, the valve seat member 109 is provided with the plurality of first passage portions 151 at equal intervals on the same circumference. [0078]
The passage groove 221 forms a radial passage 222 extending in the radial
25 direction toward the first passage portion 151. In the valve seat member 109, a plurality
36

of, specifically four, radial passages 222 are provided at equal intervals in the
circumferential direction of the valve seat member 109 with the positions aligned in the
radial direction of the valve seat member 109.
[0079]
5 As shown in Fig. 4B, in the valve seat member 109, a passage groove 225 is
formed on the small-diameter hole portion 132 side of the main body portion 140 in the axial direction. The passage groove 225 is formed to be recessed from the end surface of the main body portion 140 on the inner seat portion 138 in the axial direction of the valve seat member 109. The passage groove 225 is provided along a line in the radial
10 direction which passes through the center of the valve seat member 109 on the line in the radial direction and extends outward in the radial direction of the valve seat member 109 from the passage hole 206 that is open between the valve seat constituent portion 211 and the valve seat constituent portion 211 to be connected to the outer peripheral surface of the main body portion 140. The passage hole 206 is open to a bottom surface of the
15 passage groove 225. The passage groove 225 is provided for each of the passage holes 206. A plurality of, specifically four, passage grooves 225 are provided at equal intervals in the circumferential direction of the valve seat member 109 with the positions aligned in the radial direction of the valve seat member 109. [0080]
20 As shown in Fig. 2, the passage hole 206 and the passage recess 205 to which
the passage hole 206 is open form a second passage portion 152 provided in the valve seat member 109. In the valve seat member 109, a plurality of, specifically four, second passage portions 152 are provided at equal intervals in the circumferential direction of the valve seat member 109 with the positions aligned in the radial direction of the valve
25 seat member 109. In other words, the valve seat member 109 is provided with the
37

plurality of second passage portions 152 at equal intervals on the same circumference. [0081]
The plurality of first passage portions 151 and the plurality of second passage portions 152 are provided in the valve seat member 109 to form a valve seat member 5 passage portion 150 through which the oil liquid flows. In other words, the valve seat member passage portion 150 has the first passage portions 151 and the second passage portions 152, and the plurality of first passage portions 151 and the plurality of second passage portions 152 are alternately provided at equal intervals on the same circumference.
10 [0082]
As shown in Fig. 3, in the valve seat member 109, at an intermediate position of the outer peripheral portion in the axial direction, an annular seal groove 145 which is recessed inward in the radial direction is formed. The O-ring 108 is disposed in the seal groove 145. In the valve seat member 109, in a state in which the inner seat portion 138
15 and the valve seat portion 139 face a side opposite to the bottom portion 122, the outer peripheral portion is fitted to the tubular portion 124 of the cap member 101, and the valve seat portion 109 is provided in the cap member 101. In this state, the O-ring 108 seals the gap between the tubular portion 124 of the cap member 101 and the valve seat member 109.
20 [0083]
The cap member 101, the O-ring 108, and the valve seat member 109 constitute a cap chamber 146 inside the cap member 101. The cap chamber 146 is provided between the bottom portion 122 of the cap member 101 and the valve seat member 109. The flexible disk 100, the plurality of disks 102, and the sub valve 107 are provided in
25 the cap chamber 146.
38

[0084]
The flexible disk 100 is provided between the sub valve 107 in the cap chamber 146 and the bottom portion 122 of the cap member 101. In the flexible disk 100, the disk protruding portion 302 is constantly in contact with the bottom portion 122 of the 5 cap member 101 over the entire circumference to surround the entire plurality of passage holes 126 on the outer side in the radial direction of the bottom portion 122. Further, in the flexible disk 100, the inner peripheral side contact portion 303 is constantly in contact with the bottom portion 122 of the cap member 101 over the entire circumference to surround the entire plurality of passage holes 126 on the inner side in the radial direction
10 of the bottom portion 122. [0085]
Therefore, due to the flexible disk 100, the cap chamber 146 is divided into an intermediate chamber 147 on the sub valve 107 side with respect to the flexible disk 100 and a communication chamber 149 (a volume chamber) on the plurality of passage holes
15 126 side with respect to the flexible disk 100. The communication chamber 149
constantly communicates with a communication passage 148 in the plurality of passage holes 126. The flexible disk 100 blocks the communication of the intermediate chamber 147 with the communication passage 148. In other words, in the cap chamber 146, between the sub valve 107 and the bottom portion 122 of the cap member 101, the
20 flexible disk 100 that closes the communication passage 148 is provided. In other words, the intermediate chamber 147 of which the communication with the communication passage 148 is blocked by the flexible disk 100 is formed between the flexible disk 100 and the sub valve 107. [0086]
25 As the flexible disk 100 bends, the volume of the intermediate chamber 147
39

changes. That is, the bending of the flexible disk 100 causes the intermediate chamber 147 to have a function as an accumulator. When the communication chamber 149 absorbs the increase of the volume of the intermediate chamber 147, the volume of the communication chamber 149 decreases to discharge the oil liquid. When the 5 communication chamber 149 absorbs the decrease of the volume of the intermediate chamber 147, the volume of the communication chamber 149 increases to cause the oil liquid to flow in. This prevents the deformation of the flexible disk 100 from being hindered by the oil liquid in the communication chamber 149. [0087]
10 As shown in Fig. 2, the annular valve seat member 109 and the bottomed tubular
cap member 101 are disposed in the lower chamber 20 which is one of the upper chamber 19 and the lower chamber 20. At this time, in the valve seat member 109, the valve seat portion 135 is disposed on the cap chamber 146 side, and the valve seat portion 139 is disposed on the lower chamber 20 side. The valve seat member 109
15 divides the intermediate chamber 147 of the cap chamber 146 and the lower chamber 20 from each other and is provided to face both the intermediate chamber 147 and the lower chamber 20. The plurality of passage grooves 225 are provided facing the lower chamber 20, and the plurality of second passage portions 152 constantly communicate with the lower chamber 20 via the passages in the plurality of passage grooves 225.
20 The communication passage 148 formed in the bottom portion 122 of the cap member 101 constantly communicates with the lower chamber 20 which is one of the upper chamber 19 and the lower chamber 20. [0088]
The radial passage 222 in the passage groove 221 that is open to the first passage
25 portion 151 of the valve seat member 109 constantly communicates with the intermediate
40

chamber 147, and the inside of the intermediate chamber 147, the passage in the large-diameter hole portion 133 of the valve seat member 109, and the piston rod passage portion 51 in the passage cutout portion 30 of the piston rod 21 constantly communicate with each other. Therefore, the intermediate chamber 147 constantly communicates 5 with the upper chamber 19 via the radial passage 222 in the passage groove 221 of the valve seat member 109, the passage in the large-diameter hole portion 133 of the valve seat member 109, the piston rod passage portion 51 in the passage cutout portion 30 of the piston rod 21, the passage in the large-diameter hole portion 46 of the piston 18, the passage in the cutout portion 90 of the disk 82, and the passage in the annular groove 55
10 and the plurality of passage holes 38 of the piston 18. [0089]
As shown in Fig. 3, the disk 102 has an outer diameter equal to the outer diameter of the inner seat portion 47. As shown in Fig. 2, the sub valve 107 has a disk shape, has an outer diameter equal to the outer diameter of the valve seat portion 135 of
15 the valve seat member 109, is constantly in contact with the inner seat portion 134, and can be detached and seated with respect to the valve seat portion 135. The sub valve 107 closes all the second passage portions 152 by being seated on the entire valve seat portion 135. Further, the sub valve 107 closes the second passage portions 152 inside the valve seat constituent portions 201 by being seated on the entire valve seat
20 constituent portions 201 of the valve seat portion 135 shown in Fig. 4A. [0090]
As shown in Fig. 2, the sub valve 107 that can be detached and seated with respect to the valve seat portion 135 is provided in the cap chamber 146, and when the sub valve 107 is separated from the valve seat portion 135 in the cap chamber 146, the
25 sub valve 107 allows the plurality of second passage portions 152 and the intermediate
41

chamber 147 of the cap chamber 146 to communicate with each other and thus allows the lower chamber 20 to communicate with the upper chamber 19. At this time, the sub valve 107 suppresses the flow of the oil liquid with the valve seat portion 135 to generate a damping force. The sub valve 107 is an inflow valve that is opened when the oil 5 liquid flows into the intermediate chamber 147 from the lower chamber 20 via the
plurality of second passage portions 152 and is a check valve that restricts the outflow of the oil liquid from the intermediate chamber 147 to the lower chamber 20 via the second passage portions 152. Here, as shown in Fig. 4A, the passage hole 216 constituting the first passage portion 151 is open outside the range of the valve seat portion 135 in the
10 valve seat member 109 and thus constantly communicates with the intermediate chamber 147 regardless of the sub valve 107 seated on the valve seat portion 135 as shown in Fig. 2. [0091]
The passage in the plurality of passage grooves 225, the plurality of second
15 passage portions 152, the passage between the sub valve 107 and the valve seat portion 135 which appears when the valve is opened, the intermediate chamber 147, the radial passage 222 in the passage groove 221 of the valve seat member 109, the passage in the large-diameter hole portion 133 of the valve seat member 109, the piston rod passage portion 51 in the passage cutout portion 30 of the piston rod 21, the passage in the
20 large-diameter hole portion 46 of the piston 18, the passage in the cutout portion 90 of the disk 82, and the passage in the annular groove 55 and the plurality of passage holes 38 of the piston 18 constitute a second passage 172 through which the oil liquid flows from the lower chamber 20 which becomes an upstream side in the cylinder 2 to the upper chamber 19 which becomes a downstream side in the cylinder 2 by the movement
25 of the piston 18 toward the lower chamber 20. The second passage 172 becomes a
42

passage on a contraction side through which the oil liquid flows from the lower chamber
20 which becomes an upstream side toward the upper chamber 19 which becomes a
downstream side at the time of the movement of the piston 18 toward the lower chamber
20, that is, in the contraction stroke.
5 [0092]
The second passage 172 includes the piston rod passage portion 51 in the passage cutout portion 30 formed by cutting out the piston rod 21, in other words, a part of the second passage 172 is formed by being cut out of the piston rod 21. In addition to the formation of the piston rod passage portion 51 by cutting out the piston rod 21, the 10 piston rod passage portion 51 may be formed by penetrating the inside of the piston rod
21 in a hole shape such that one end is open in the passage in the large-diameter hole
portion 133 of the valve seat member 109 and the other end is open in the passage in the
large-diameter hole portion 46 of the piston 18. Therefore, the second passage 172 has
the piston rod passage portion 51 formed by cutting out or penetrating the piston rod 21.
15 [0093]
The sub valve 107, the valve seat portion 135, the plurality of disks 102, the flexible disk 100, and the cap member 101 constitute a second damping force generating mechanism 173 on a contraction side which is provided in the second passage 172 on a contraction side, opens and closes the second passage 172, and suppresses the flow of the
20 oil liquid from the second passage 172 to the upper chamber 19 to generate a damping force. In other words, in the second damping force generating mechanism 173, the valve seat portion 135 is provided in the valve seat member 109. The sub valve 107 constituting the second damping force generating mechanism 173 on a contraction side is a sub valve on a contraction side.
25 [0094]
43

In the second passage 172, when the second damping force generating mechanism 173 is in an opened state, the passage in the cutout portion 90 of the disk 82 becomes the narrowest among portions in which a flow path cross-sectional area is fixed, the flow path cross-sectional area of the passage in the cutout portion 90 is narrower than 5 that of each of the upstream side and downstream side thereof, and the passage in the cutout portion 90 becomes an orifice 175 in the second passage 172. The orifice 175 is disposed on a downstream side from the sub valve 107 in the flow of the oil liquid when the sub valve 107 is opened and the oil liquid flows through the second passage 172. The orifice 175 is formed by being cut out of the disk 82 in the first damping force
10 generating mechanism 41, which is in contact with the piston 18. [0095]
In the second damping force generating mechanism 173 on a contraction side, in each of the valve seat portion 135 and the sub valve 107 in contact therewith, a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to communicate with
15 each other even when the valve seat portion 135 and the sub valve 107 are in contact with each other is not formed. That is, the second damping force generating mechanism 173 on a contraction side does not allow the upper chamber 19 and the lower chamber 20 to communicate with each other if the valve seat portion 135 and the sub valve 107 are in contact with each other over the entire circumference. In other words, a fixed orifice
20 that allows the upper chamber 19 and the lower chamber 20 to constantly communicate with each other is not formed in the second passage 172, and thus the second passage 172 is not a passage that allows the upper chamber 19 and the lower chamber 20 to constantly communicate with each other. [0096]
25 The second passage 172 on a contraction side through which the upper chamber
44

19 and the lower chamber 20 can communicate with each other is parallel to the first passage 72 which is also a passage on a contraction side through which the upper chamber 19 and the lower chamber 20 can communicate with each other, the first damping force generating mechanism 42 is provided in the first passage 72, and the 5 second damping force generating mechanism 173 is provided in the second passage 172. Therefore, the first damping force generating mechanism 42 on a contraction side and the second damping force generating mechanism 173 on a contraction side are disposed in parallel. [0097]
10 As shown in Fig. 3, the sub valve 110 has a disk shape, has an outer diameter
equal to the outer diameter of the valve seat portion 139 of the valve seat member 109, is constantly in contact with the inner seat portion 138, and can be detached and seated with respect to the valve seat portion 139. The sub valve 110 closes all the first passage portions 151 by being seated on the entire valve seat portion 139. Further, the sub valve
15 110 closes the first passage portions 151 inside the valve seat constituent portions 211 by being seated on the entire valve seat constituent portions 211 of the valve seat portion 139 shown in Fig. 4B. As shown in Fig. 3, the sub valve 110 can be a common part having the same shape as the sub valve 107. The outer diameter of the disk 111 is smaller than the outer diameter of the sub valve 110 and is equal to the outer diameter of
20 the inner seat portion 138. [0098]
The sub valve 110 is provided in the lower chamber 20 and allows the intermediate chamber 147 and the lower chamber 20 to communicate with each other by being separated from the valve seat portion 139. At this time, the sub valve 110
25 suppresses the flow of the oil liquid with the valve seat portion 139 to generate a
45

damping force. The sub valve 110 is a discharge valve that is opened when the oil liquid is discharged from the inside of the intermediate chamber 147 to the lower chamber 20 via the plurality of first passage portions 151 of the valve seat member 109 and is a check valve that restricts the inflow of the oil liquid from the lower chamber 20 5 to the inside of the intermediate chamber 147 via the first passage portions 151. Here, as shown in Fig. 4B, the passage hole 206 constituting the second passage portion 152 is open outside the range of the valve seat portion 139 in the valve seat member 109 and thus constantly communicates with the lower chamber 20 regardless of the sub valve 110 seated on the valve seat portion 139 as shown in Fig. 2.
10 [0099]
The passage in the plurality of passage holes 38 and the annular groove 55 of the piston 18, the passage in the cutout portion 90 of the disk 82, the piston rod passage portion 51 in the passage cutout portion 30 of the piston rod 21, the passage in the large-diameter hole portion 46 of the piston 18, the passage in the large-diameter hole
15 portion 133 of the valve seat member 109, the radial passage 222 in the passage groove 221 of the valve seat member 109, the intermediate chamber 147, the plurality of first passage portions 151 of the valve seat member 109, and the passage between the sub valve 110 and the valve seat portion 139 which appears when the valve is opened constitute a second passage 182 through which the oil liquid flows from the upper
20 chamber 19 which becomes an upstream side in the cylinder 2 to the lower chamber 20 which becomes a downstream side in the cylinder 2 by the movement of the piston 18 toward the upper chamber 19. [0100]
The second passage 182 becomes a passage on an extension side through which
25 the oil liquid flows from the upper chamber 19 which becomes an upstream side toward
46

the lower chamber 20 which becomes a downstream side at the time of the movement of the piston 18 toward the upper chamber 19, that is, in the extension stroke. The second passage 182 includes the piston rod passage portion 51 in the passage cutout portion 30 formed by cutting out the piston rod 21, in other words, a part of the second passage 182 5 is formed by being cut out of the piston rod 21. [0101]
The cap member 101, the sub valve 110, the valve seat portion 139, the disks 111 and 113, and the annular member 114 constitute a second damping force generating mechanism 183 on an extension side which is provided in the second passage 182 on an
10 extension side, opens and closes the second passage 182, and suppresses the flow of the oil liquid from the second passage 182 to the lower chamber 20 to generate a damping force. In other words, in the second damping force generating mechanism 183, the valve seat portion 139 is provided in the valve seat member 109. The sub valve 110 constituting the second damping force generating mechanism 183 on an extension side is
15 a sub valve on an extension side. [0102]
As shown in Fig. 3, the communication chamber 149 that communicates with the lower chamber 20 is disposed in parallel with the second passage 172 shown in Fig. 2 and the second passage 182 shown in Figs. 2 and 3. The second damping force
20 generating mechanisms 173 and 183 each have a volume variable mechanism 185 that can change the volume of the communication chamber 149. The volume variable mechanism 185 is constituted by the flexible disk 100, the bottom portion 122 of the cap member 101, the communication chamber 149, and the communication passage 148. The flexible disk 100 changes to reduce the volume of the communication chamber 149
25 by deforming and moving toward the bottom portion 122 and changes to increase the
47

volume of the communication chamber 149 by deforming and moving away from the
bottom portion 122.
[0103]
In the second passage 182, when the second damping force generating 5 mechanism 183 is in an opened state, as shown in Fig. 2, the passage in the cutout portion 90 of the disk 82 becomes the narrowest among portions in which a flow path cross-sectional area is fixed, the flow path cross-sectional area of the passage in the cutout portion 90 is narrower than that of each of the upstream side and downstream side thereof, and the passage in the cutout portion 90 becomes an orifice 175 also in the
10 second passage 182. The orifice 175 is common to the second passages 172 and 182. The orifice 175 is disposed on an upstream side from the sub valve 110 in the flow of the oil liquid when the sub valve 110 is opened and the oil liquid flows through the second passage 182. The orifice 175 may be disposed on a downstream side from the sub valve 110 in the flow of the oil liquid when the sub valve 110 is opened and the oil liquid flows
15 through the second passage 182. The sub valve 110 and the above sub valve 107 are independently opened and closed. [0104]
In the second damping force generating mechanism 183 on an extension side, in each of the valve seat portion 139 and the sub valve 110 in contact therewith, a fixed
20 orifice that allows the upper chamber 19 and the lower chamber 20 to communicate with each other even when the valve seat portion 139 and the sub valve 110 are in contact with each other is not formed. That is, the second damping force generating mechanism 183 on an extension side does not allow the upper chamber 19 and the lower chamber 20 to communicate with each other if the valve seat portion 139 and the sub valve 110 are in
25 contact with each other over the entire circumference. In other words, a fixed orifice
48

that allows the upper chamber 19 and the lower chamber 20 to constantly communicate with each other is not formed in the second passage 182, and thus the second passage 182 is not a passage that allows the upper chamber 19 and the lower chamber 20 to constantly communicate with each other. The annular member 114, together with the disk 113, 5 restricts the deformation of the sub valve 110 in the opening direction beyond a specified value by coming into contact with the sub valve 110. [0105]
In the shock absorber 1, as a flow for passing the oil liquid in the axial direction at least in the piston 18, the upper chamber 19 and the lower chamber 20 can
10 communicate with each other via only the first damping force generating mechanisms 41 and 42 and the second damping force generating mechanisms 173 and 183. Therefore, in the shock absorber 1, on the passage of the oil liquid that passes through at least the inside of the piston 18 in the axial direction, a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to constantly communicate with each other is not provided.
15 Since the shock absorber 1 is a mono-tube type, the shock absorber 1 is not provided with a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to constantly communicate with each other as a whole. [0106]
The second passage 182 on an extension side through which the upper chamber
20 19 and the lower chamber 20 can communicate with each other is parallel to the first passage 92 which is also a passage on an extension side through which the upper chamber 19 and the lower chamber 20 can communicate with each other, except for the passage in the annular groove 55 and the plurality of passage holes 38 on the upper chamber 19 side. In the parallel portion, the first damping force generating mechanism
25 41 is provided in the first passage 92, and the second damping force generating
49

mechanism 183 is provided in the second passage 182. Therefore, the first damping
force generating mechanism 41 on an extension side and the second damping force
generating mechanism 183 on an extension side are disposed in parallel.
[0107]
5 The second damping force generating mechanisms 173 and 183 include the
valve seat member 109, the sub valve 110 provided on one side of the valve seat member passage portion 150 which is a portion of the second passages 172 and 182 provided in the valve seat member 109 and the sub valve 107 provided on the other side of the valve seat member passage portion 150, and the bottomed tubular cap member 101 provided
10 between the piston 18 and the valve seat member 109 in the second passages 172 and 182. The valve seat member 109 is provided in the cap member 101, the sub valve 110 is provided on the lower chamber 20 side of the valve seat member 109, and the sub valve 107 is provided in the cap chamber 146 formed between the bottom portion 122 of the cap member 101 and the valve seat member 109. The valve seat member 109 is
15 provided with the radial passage 222 that communicates with the piston rod passage
portion 51 and extends in the radial direction toward the first passage portion 151 on an
extension side.
[0108]
In a case in which the piston 18 or the like is assembled to the piston rod 21, the
20 annular member 69, the disk 68, the disk 67, the plurality of disks 66, the plurality of
disks 65, the plurality of disks 64, the disk 63, the plurality of disks 62, and the piston 18 are superposed on the shaft step portion 29 in order while the attachment shaft portion 28 of the piston rod 21 is inserted. At this time, the piston 18 is oriented such that the small-diameter hole portion 45 is located on the shaft step portion 29 side.
25 [0109]
50

In addition, the disk 82, the disks 83, the disk 84, the plurality of disks 85, the disk 86, the plurality of disks 87, the plurality of disks 88, the disk 89, and the cap member 101 are superposed on the piston 18 in order while the attachment shaft portion 28 is inserted. At this time, the cap member 101 is oriented such that the bottom 5 portion 122 is located on the piston 18 side and is in contact with the disk 89. [0110]
Further, the flexible disk 100, the plurality of disks 102, the sub valve 107, and the valve seat member 109 on which the O-ring 108 is mounted are superposed on the bottom portion 122 of the cap member 101 in order while the attachment shaft portion 28
10 is inserted. At this time, as shown in Fig. 3, in the flexible disk 100, the disk protruding portion 302 is oriented to protrude from the main body portion 301 toward the bottom portion 122, the disk protruding portion 302 is in contact with the bottom portion 122, and the inner peripheral side contact portion 303 is in contact with the disk 102. Further, at this time, in the valve seat member 109, as shown Fig. 2, the inner seat portion 134 and
15 the valve seat portion 135 are oriented to be located on the sub valve 107, and the outer peripheral portion and the O-ring 108 are fitted to the tubular portion 124 of the cap member 101. [0111]
Further, the sub valve 110, the disk 111, the disk 113, and the plurality of
20 annular members 114 are superposed on the valve seat member 109 in order while the attachment shaft portion 28 is inserted. In this state, the nut 115 is screwed to the male screw 31 of the piston rod 21 protruding with respect to the annular member 114, and the nut 115 and the shaft step portion 29 clamp at least the inner peripheral side of the above-described constituent elements in the axial direction.
25 [0112]
51

In this state, the inner peripheral side of the main valve 71 is clamped between the inner seat portion 49 of the piston 18 and the disk 67 via the disks 62 and 63, and the main valve 71 is in contact with the valve seat portion 50 of the piston 18 over the entire circumference. Further, in this state, the inner peripheral side of the main valve 91 is 5 clamped between the inner seat portion 47 of the piston 18 and the disk 89 via the disks 82 to 84, and the main valve 91 is in contact with the valve seat portion 48 of the piston 18 over the entire circumference. [0113]
Further, in this state, as shown in Fig. 3, in the flexible disk 100, the disk
10 protruding portion 302 is in contact with the bottom portion 122 while the flexible disk 100 is elastically deformed, and the inner peripheral side contact portion 303 is clamped between the bottom portion 122 of the cap member 101 and the disk 102. Further, in this state, as shown in Fig. 2, the inner peripheral side of the sub valve 107 is clamped between the inner seat portion 134 of the valve seat member 109 and the disk 102, and
15 the sub valve 107 is in contact with the valve seat portion 135 of the valve seat member 109 over the entire circumference. Further, in this state, the inner peripheral side of the sub valve 110 is clamped between the inner seat portion 138 of the valve seat member 109 and the disk 111, and the sub valve 110 is in contact with the valve seat portion 139 of the valve seat member 109 over the entire circumference.
20 [0114]
As shown in Fig. 3, in the flexible disk 100, when the disk protruding portion 302 is in contact with the bottom portion 122 and the inner peripheral side contact portion 303 is clamped between the bottom portion 122 of the cap member 101 and the disk 102, the disk protruding portion 302 is in contact with the bottom portion 122 of the
25 cap member 101 over the entire circumference in a state in which a preload
52

corresponding to the height of the disk protruding portion 302 is applied. Although the sub valve 107 bends in a direction toward the flexible disk 100 when the valve is opened, a sufficient gap is provided between the sub valve 107 and the flexible disk 100. Therefore, even when the sub valve 107 is lifted to the maximum, the sub valve 107 does 5 not come into contact with the flexible disk 100. [0115]
As shown in Fig. 2, between the first damping force generating mechanism 41 on an extension side and the second damping force generating mechanism 183 on an extension side, the main valve 91 of the first damping force generating mechanism 41 has
10 a rigidity and a valve opening pressure higher than those of the sub valve 110 of the
second damping force generating mechanism 183. Therefore, in the extension stroke, in an extremely low speed region in which a piston speed is lower than a predetermined value, the valve of the second damping force generating mechanism 183 is opened in a state in which the valve of the first damping force generating mechanism 41 is closed.
15 Further, in a normal speed region in which the piston speed is this predetermined value or more, the valve of the first damping force generating mechanism 41 and the valve of the second damping force generating mechanism 183 are both opened. The sub valve 110 is an extremely low speed valve which is opened to generate a damping force in a region in which the piston speed is extremely low.
20 [0116]
That is, in the extension stroke, the piston 18 moves to the upper chamber 19 side, and thus the pressure in the upper chamber 19 increases and the pressure in the lower chamber 20 decreases. Then, although neither each of the first damping force generating mechanisms 41 and 42 nor each of the second damping force generating
25 mechanisms 173 and 183 has a fixed orifice that allows the upper chamber 19 and the
53

lower chamber 20 to constantly communicate with each other, the oil liquid in the upper chamber 19 flows into the intermediate chamber 147 via the passage in the plurality of passage holes 38 and the annular groove 55 of the piston 18, the orifice 175, the passage in the large-diameter hole portion 46 of the piston 18, the piston rod passage portion 51 5 in the passage cutout portion 30 of the piston rod 21, the passage in the large-diameter hole portion 133 of the valve seat member 109, and the radial passage 222 in the passage groove 221 of the valve seat member 109. As a result, the pressure in the intermediate chamber 147 is increased. Therefore, in the volume variable mechanism 185 shown in Fig. 3, the flexible portion 305 of the flexible disk 100 bends toward the bottom portion
10 122 to increase the capacity of the intermediate chamber 147, and thus the pressure
increase in the intermediate chamber 147 is suppressed. At this time, since the flexible disk 100 bends and moves toward the bottom portion 122, the volume variable mechanism 185 reduces the volume of the communication chamber 149. [0117]
15 Here, in the extension stroke of the shock absorber 1 at the time of low
frequency input (at the time of large amplitude excitation), the amount of the oil liquid flowing from the upper chamber 19 into the intermediate chamber 147 becomes large as described above. Therefore, the flexible disk 100 is greatly deformed, the flexible portion 305 comes into contact with the bottom portion 122 of the cap member 101, and
20 the contact area thereof becomes large. When the contact area of the flexible disk 100 with the bottom portion 122 is increased in this way, the amount of bending of the flexible disk 100 is limited, and thus the flexible disk 100 does not bend when a certain amount or more of a differential pressure is applied. Since the flexible disk 100 is completely bent in this way, the capacity of the intermediate chamber 147 is not
25 increased. This state is the same as a state in which the flexible disk 100 and the
54

communication passage 148 are not present, and the pressure in the intermediate chamber
147 is increased to the state in which the valve of the second damping force generating
mechanism 183 is opened.
[0118]
5 At this time, since neither each of the first damping force generating
mechanisms 41 and 42 nor each of the second damping force generating mechanisms 173 and 183 has a fixed orifice that allows the upper chamber 19 and the lower chamber 20 to constantly communicate with each other, as shown by a solid line in Fig. 5, in the extension stroke in which the piston speed is less than a first predetermined value vl at
10 which the valve of the second damping force generating mechanism 183 is opened, the damping force rises steeply. Further, in a region in which the piston speed is higher than the first predetermined value vl and in an extremely low speed region in which the piston speed is higher than the first predetermined value and lower than a second predetermined value v2 (vl or more and less than v2), the valve of the second damping
15 force generating mechanism 183 is opened in a state in which the valve of the first damping force generating mechanism 41 is closed. [0119]
That is, the sub valve 110 is separated from the valve seat portion 139, and the upper chamber 19 and the lower chamber 20 communicate with each other through the
20 second passage 182 on an extension side. Therefore, the oil liquid in the upper chamber 19 flows to the lower chamber 20 via the passage in the plurality of passage holes 38 and the annular groove 55 of the piston 18, the orifice 175, the passage in the large-diameter hole portion 46 of the piston 18, the piston rod passage portion 51 in the passage cutout portion 30 of the piston rod 21, the passage in the large-diameter hole portion 133 of the
25 valve seat member 109, the intermediate chamber 147, the radial passage 222 in the
55

passage groove 221 of the valve seat member 109, the first passage portion 151 in the valve seat member 109, and the passage between the sub valve 110 and the valve seat portion 139. As a result, even in the extremely low speed region in which the piston speed is lower than the second predetermined value, the damping force of the valve 5 characteristics (the characteristics in which the damping force is substantially proportional to the piston speed) can be obtained. [0120]
Further, in the extension stroke, in the normal speed region in which the piston speed is the second predetermined value v2 or more, the valve of the first damping force
10 generating mechanism 41 is opened while a state in which the valve of the second
damping force generating mechanism 183 is opened remains. That is, the sub valve 110 is separated from the valve seat portion 139, and the oil liquid flows from the upper chamber 19 to the lower chamber 20 through the second passage 182 on an extension side, but at this time, the flow of the oil liquid is throttled by the orifice 175 provided on
15 the downstream side from the main valve 91 in the second passage 182, and thus the pressure applied to the main valve 91 increases and a differential pressure increases, the main valve 91 is separated from the valve seat portion 48, and the oil liquid flows from the upper chamber 19 to the lower chamber 20 through the first passage 92 on an extension side. Therefore, the oil liquid in the upper chamber 19 flows to the lower
20 chamber 20 via the passage in the plurality of passage holes 38 and the annular groove 55 and the passage between the main valve 91 and the valve seat portion 48. [0121]
As a result, even in the above normal speed region in which the piston speed is the second predetermined value v2 or more, the damping force of the valve
25 characteristics (the characteristics in which the damping force is substantially
56

proportional to the piston speed) can be obtained. The rate of the increase of the damping force on an extension side with respect to the increase of the piston speed in the normal speed region is lower than the rate of the increase of the damping force on an extension side with respect to the increase of the piston speed in the extremely low speed 5 region. In other words, the inclination of the rate of the increase of the damping force on an extension side with respect to the increase in the piston speed in the normal speed region can be made lower than that in the extremely low speed region. [0122]
Here, in the extension stroke, in the normal speed region in which the piston
10 speed is the second predetermined value v2 or more, the differential pressure between the upper chamber 19 and the lower chamber 20 is higher than that in the low speed region in which the piston speed is the first predetermined value vl or more and less than the second predetermined value v2, but, since the first passage 92 is not throttled by the orifice, it is possible to allow the oil liquid to flow via the first passage 92 at a large flow
15 rate by the main valve 91 being opened. By this and by throttling the second passage 182 with the orifice 175, it is possible to prevent the sub valve 110 from being deformed. [0123]
Further, at this time, pressures in opposite directions from the lower chamber 20 and the intermediate chamber 147 are applied to the sub valve 107 in a closed state.
20 Even if the differential pressure between the upper chamber 19 and the lower chamber 20 becomes large, since the orifice 175 is formed on the upstream side from the sub valve 107 in the second passage 182, the pressure increase in the intermediate chamber 147 becomes gentle with respect to the pressure increase in the upper chamber 19, which prevents the pressure difference between the intermediate chamber 147 and the lower
25 chamber 20 from becoming large. Therefore, it is possible to prevent the pressure
57

difference between the intermediate chamber 147 and the lower chamber 20 received by the sub valve 107 in a closed state from becoming large, and it is possible to prevent the large back pressure from the intermediate chamber 147 side toward the lower chamber 20 side from being applied to the sub valve 107. 5 [0124]
The shock absorber 1 is provided with, as a flow path through which the oil liquid flows from the upper chamber 19 to the lower chamber 20 in the extension stroke, the first passage 92 and the second passage 182 in parallel and is provided with the main valve 91 and the sub valve 110 in parallel. Further, the orifice 175 is connected in series
10 with the sub valve 110. [0125]
As described above, in the extension stroke, in the normal speed region in which the piston speed is the second predetermined value v2 or more, it is possible to allow the oil liquid to flow via the first passage 92 at a large flow rate by the main valve 91 being
15 opened. As a result, the flow rate of the oil liquid flowing through the passage between the sub valve 110 and the valve seat portion 139 is reduced. Therefore, for example, the rate of the increase of the damping force with respect to the increase in the piston speed in the normal speed region (v2 or more) for the piston speed can be reduced. In other words, the inclination of the rate of the increase of the damping force on an extension
20 side with respect to the increase in the piston speed in the normal speed region (v2 or
more) can be made lower than that in the extremely low speed region (less than v2). As
a result, the degree of freedom in design can be expanded.
[0126]
In the extension stroke at the time of high frequency input (at the time of small
25 amplitude excitation) in which a higher frequency is input to the shock absorber 1 than
58

that at the time of low frequency input described above, the amount of the oil liquid flowing from the upper chamber 19 into the intermediate chamber 147 is small. Therefore, the deformation of the flexible disk 100 is small, and the volume variable mechanism 185 can absorb the volume of the oil liquid flowing into the intermediate 5 chamber 147 by the amount of bending of the flexible disk 100. Therefore, the increase in the pressure in the intermediate chamber 147 becomes small. Therefore, at the time of rising of an extremely low speed damping force, it is possible to make the state of the shock absorber a state in which, as it were, there is no flexible disk 100 and the intermediate chamber 147 constantly communicates with the lower chamber 20 through
10 the communication passage 148 of the cap member 101, that is, a state in which the
structure of the shock absorber is the same as a structure having no second damping force
generating mechanism 183.
[0127]
Therefore, in comparison with the damping force characteristics at the time of
15 low frequency input shown by the solid line in Fig. 5, the rise of the extremely low speed damping force becomes gentle as shown by a two-dot chain line in Fig. 5. Further, in the extremely low speed region (less than v2), when the flexible disk 100 is bent, the valve of the second damping force generating mechanism 183 is opened while increasing the volume of the oil liquid flowing into the intermediate chamber 147, and thus the
20 extremely low speed damping force with respect to the same piston speed is lower than that at the time of low frequency input in which the flexible disk 100 is completely bent and the volume of the oil liquid flowing into the intermediate chamber 147 is not changed. In other words, when the frequency of the piston 18 exceeds a predetermined frequency, the volume variable mechanism 185 including the flexible disk 100 limits the
25 flow rate of the oil liquid to the sub valve 110 of the second damping force generating
59

mechanism 183. When the rigidity (the plate thickness or the like) of the flexible disk 100 is variously formed, it is possible to adjust the change in damping force (the inclination of the damping force with respect to the piston speed) until the valve of the second damping force generating mechanism 183 is opened. 5 [0128]
As shown in Fig. 2, between the first damping force generating mechanism 42 on a contraction side and the second damping force generating mechanism 173 on a contraction side, the main valve 71 of the first damping force generating mechanism 42 has a rigidity and a valve opening pressure higher than those of the sub valve 107 of the
10 second damping force generating mechanism 173. Therefore, in the contraction stroke, in the extremely low speed region in which the piston speed is lower than a predetermined value, the valve of the second damping force generating mechanism 173 is opened in a state in which the valve of the first damping force generating mechanism 42 is closed, and in a normal speed region in which the piston speed is higher than the
15 predetermined value, the valve of the first damping force generating mechanism 42 and the valve of the second damping force generating mechanism 173 are both opened. The sub valve 107 is an extremely low speed valve which is opened to generate a damping force in a region in which the piston speed is extremely low. [0129]
20 That is, in the contraction stroke, the piston 18 moves to the lower chamber 20
side, and thus the pressure in the lower chamber 20 increases and the pressure in the upper chamber 19 decreases. Then, since neither each of the first damping force generating mechanisms 41 and 42 nor each of the second damping force generating mechanisms 173 and 183 has a fixed orifice that allows the lower chamber 20 and the
25 upper chamber 19 to constantly communicate with each other, the oil liquid does not
60

flow until the valve of the second damping force generating mechanism 173 is opened. Therefore, the damping force rises steeply. In a region in which the piston speed is higher than a third predetermined value at which the valve of the second damping force generating mechanism 173 is opened and in an extremely low speed region in which the 5 piston speed is higher than the third predetermined value and lower than a fourth
predetermined value, the valve of the second damping force generating mechanism 173 is opened in a state in which the valve of the first damping force generating mechanism 42 is closed. [0130]
10 That is, the sub valve 107 is separated from the valve seat portion 135, and the
lower chamber 20 and the upper chamber 19 communicate with each other through the second passage 172 on a contraction side. Therefore, the oil liquid in the lower chamber 20 flows to the upper chamber 19 via the passage in the passage groove 225 of the valve seat member 109, the second passage portion 152, the passage between the sub
15 valve 107 and the valve seat portion 135, the intermediate chamber 147, the radial
passage 222 in the passage groove 221 of the valve seat member 109, the passage in the large-diameter hole portion 133 of the valve seat member 109, the piston rod passage portion 51 in the passage cutout portion 30 of the piston rod 21, the passage in the large-diameter hole portion 46 of the piston 18, the orifice 175, and the passage in the
20 annular groove 55 and the plurality of passage holes 38 of the piston 18. As a result,
even in the extremely low speed region in which the piston speed is lower than the fourth predetermined value, the damping force of the valve characteristics (the characteristics in which the damping force is substantially proportional to the piston speed) can be obtained.
25 [0131]
61

Further, in the contraction stroke, in the normal speed region in which the piston speed is the fourth predetermined value or more, the valve of the first damping force generating mechanism 42 is opened while a state in which the valve of the second damping force generating mechanism 173 is opened remains. That is, the sub valve 107 5 is separated from the valve seat portion 135, and the oil liquid flows from the lower chamber 20 to the upper chamber 19 through the second passage 172 on a contraction side, but at this time, in the second passage 172, the flow rate of the oil liquid is throttled by the orifice 175, and thus a differential pressure generated at the main valve 71 provided in the first passage 72 increases, the main valve 71 is separated from the valve
10 seat portion 50, and the oil liquid flows from the lower chamber 20 to the upper chamber 19 through the first passage 72 on a contraction side. Therefore, the oil liquid in the lower chamber 20 flows to the upper chamber 19 via the passage in the plurality of passage holes 39 and the annular groove 56 and the passage between the main valve 71 and the valve seat portion 50.
15 [0132]
As a result, even in the above normal speed region in which the piston speed is the fourth predetermined value or more, the damping force of the valve characteristics (the characteristics in which the damping force is substantially proportional to the piston speed) can be obtained. The rate of the increase of the damping force on a contraction
20 side with respect to the increase of the piston speed in the normal speed region is lower than the rate of the increase of the damping force on a contraction side with respect to the increase of the piston speed in the extremely low speed region. In other words, the inclination of the rate of the increase of the damping force on a contraction side with respect to the increase in the piston speed in the normal speed region can be made lower
25 than that in the extremely low speed region.
62

[0133]
In the contraction stroke, in the normal speed region in which the piston speed is the fourth predetermined value or more, the differential pressure between the upper chamber 19 and the lower chamber 20 is higher than that in the low speed region, but, 5 since the first passage 72 is not throttled by the orifice, it is possible to allow the oil liquid to flow via the first passage 72 at a large flow rate by the main valve 71 being opened. Therefore, the damping force in the normal speed region for the piston speed can be reduced, and the degree of freedom in design can be expanded. [0134]
10 Further, at this time (in a case in which the piston speed is high), the differential
pressure between the lower chamber 20 and the upper chamber 19 becomes large, but the second passage 172 is throttled with the orifice 175, and thus the pressure in the intermediate chamber 147 communicating with the upper chamber 19 via the orifice 175 becomes the pressure between the lower chamber 20 and the upper chamber 19.
15 Therefore, it is possible to prevent the differential pressure between the intermediate chamber 147 and the lower chamber 20 from becoming too large. By this and by opening the main valve 71 to allow the oil liquid to flow at a large flow rate through the first passage 72, it is possible to prevent the sub valve 107 from being deformed. [0135]
20 Further, at this time, pressures in opposite directions from the lower chamber 20
and the intermediate chamber 147 are applied to the sub valve 110 in a closed state. The differential pressure between the lower chamber 20 and the upper chamber 19 is large, but the lower chamber 20 and the intermediate chamber 147 communicate with each other by the sub valve 107 being opened, and the orifice 175 is provided between
25 the intermediate chamber 147 which becomes a downstream side of the sub valve 110
63

and the upper chamber 19. Therefore, it is possible to prevent the pressure in the intermediate chamber 147 from dropping too much, and it is also possible to increase the pressure in the intermediate chamber 147 in accordance with the increase in the pressure in the lower chamber 20. Therefore, the differential pressure generated on surfaces of 5 the sub valve 110 on the upstream side and downstream side is small, and it is possible to prevent a large back pressure from the lower chamber 20 side toward the intermediate chamber 147 side from being applied to the sub valve 110. [0136]
The above shock absorber 1 is provided with, as a flow path through which the
10 oil liquid flows from the lower chamber 20 to the upper chamber 19 in the contraction stroke, the first passage 72 and the second passage 172 in parallel and is provided with the main valve 71 and the sub valve 107 in parallel. Further, the orifice 175 is connected in series with the sub valve 107 in the second passage 172. [0137]
15 In the contraction stroke, when the pressure in the lower chamber 20 increases,
the pressure in the communication passage 148 and the communication chamber 149 also increases. However, it is set that the valve of the second damping force generating mechanism 173 is opened before the flexible disk 100 is deformed by the pressure in the communication passage 148 and the communication chamber 149. Therefore, in the
20 contraction stroke, the flexible disk 100 does not allow the communication chamber 149 to communicate with the intermediate chamber 147. [0138]
As described above, in the extension stroke of the shock absorber 1, in the normal speed region in which the piston speed is the second predetermined value v2 or
25 more, the differential pressure between the upper chamber 19 and the lower chamber 20
64

becomes large, but, since the pressure increase in the intermediate chamber 147 can be suppressed with the orifice 175 formed on the upstream side from the sub valve 107, the deformation of the sub valve 107 due to the back pressure can be suppressed. Further, in the contraction stroke, in the normal speed region in which the piston speed is the 5 fourth predetermined value or more, the differential pressure between the lower chamber 20 and the upper chamber 19 becomes larger than that in the low speed region, but by allowing the oil liquid to flow at a large flow rate in the first passage 72 and by throttling the downstream side from the sub valve 107 in the second passage 172 with the orifice 175, it is possible to suppress the deformation of the sub valve 107. Therefore, the
10 durability of the sub valve 107 can be improved. [0139]
Further, in the extension stroke of the shock absorber 1, in the normal speed region in which the piston speed is the second predetermined value v2 or more, the differential pressure between the upper chamber 19 and the lower chamber 20 becomes
15 larger than that in the low speed region, but by allowing the oil liquid to flow at a large flow rate in the first passage 92 and by throttling the second passage 182 with the orifice 175, it is possible to suppress the deformation of the sub valve 110. Further, in the contraction stroke, in the normal speed region in which the piston speed is the fourth predetermined value or more, the differential pressure between the lower chamber 20 and
20 the upper chamber 19 becomes large, but the lower chamber 20 and the intermediate chamber 147 communicate with each other by the sub valve 107 being opened, and the flow of the oil liquid from the intermediate chamber 147 to the upper chamber 19 is throttled with the orifice 175 provided between the intermediate chamber 147 and the upper chamber 19. Therefore, the differential pressure between the lower chamber 20
25 and the intermediate chamber 147 is small, and deformation of the sub valve 110 due to
65

the back pressure can be suppressed. Therefore, the durability of the sub valve 110 can
be improved.
[0140]
Since the shock absorber 1 has the second damping force generating 5 mechanisms 173 and 183 which are independent in the contraction stroke and the extension stroke, the degree of freedom in setting the damping force characteristics is increased. [0141]
Patent Literature 1 described above describes a shock absorber having two
10 valves which are opened in the same stroke. By employing a structure in which two valves which are opened in the same stroke are provided in this way, it is possible to open one valve without opening the other valve in a region in which the piston speed is low and to open both valves in a region in which the piston speed is higher than that in the region in which the piston speed is low. In a shock absorber having such a structure,
15 if it is set that the damping force is generated at the time of low frequency input in the extremely low speed region in order to improve the responsiveness at the time of fine steering input, the flat feeling in ride quality on a smooth road, or the like, abnormal noise may be generated at the time of high frequency input. [0142]
20 The shock absorber 1 of the first embodiment has the first passage 92 and the
second passage 182 through which the oil liquid flows by the movement of the piston 18, the first damping force generating mechanism 41 which is provided in the first passage 92 and generates a damping force, and the second damping force generating mechanism 183 which is provided in the second passage 182 and generates a damping force. The
25 second damping force generating mechanism 183 includes the sub valve 110 provided on
66

one side of the second passage 182 and the volume variable mechanism 185 that changes
the volume of the communication chamber 149 provided in parallel with the second
passage 182. As a result, the volume variable mechanism 185 makes it possible to
change the volume of the communication chamber 149 provided in parallel with the 5 second passage 182. Therefore, it is possible to change the flow rate of the oil liquid
flowing through the second passage 182. Therefore, it is possible to suppress the
generation of abnormal noise.
[0143]
Further, the volume variable mechanism 185 has the communication chamber 10 149 and the flexible disk 100 that moves to change the volume of the communication
chamber 149. Therefore, the volume variable mechanism 185 can be configured in a
simple manner.
[0144]
When the frequency of the piston 18 exceeds the predetermined frequency, the 15 flow rate of the oil liquid to the sub valve 110 is limited by the volume variable
mechanism 185. Therefore, it is possible to suppress the generation of abnormal noise
especially at the time of high frequency input.
[0145]
Further, the first passage 92 and the second passage 182 are connected in 20 parallel. Therefore, it is possible to reduce the flow rate of the oil liquid flowing
through the second passage 182. Therefore, it is possible to suppress the deformation of
the sub valve 110.
[0146]
In the shock absorber 1 of the first embodiment, the sub valve 110 and the sub 25 valve 107 of the second damping force generating mechanisms 173 and 183 of the
67

second passages 172 and 182 which are parallel to the first passages 72 and 92 of the piston 18 provided with the first damping force generating mechanisms 41 and 42 are provided in the valve seat member 109 disposed in the lower chamber 20. At the same time, the bottomed tubular cap member 101 is provided between the piston 18 and the 5 valve seat member 109 in the second passages 172 and 182, and the valve seat member 109 is disposed inside the cap member 101. At this time, the sub valve 110 is provided on the lower chamber 20 side, and the sub valve 107 is provided in the cap chamber 146 formed between the bottom portion 122 of the cap member 101 and the valve seat member 109. Then, the communication passage 148 communicating with the lower
10 chamber 20 is formed in the bottom portion 122 of the cap member 101, and the flexible disk 100 that closes the communication passage 148 is provided between the second sub valve 107 in the cap chamber 146 and the bottom portion 122 of the cap member 101. As a result, the intermediate chamber 147 of which the communication with the communication passage 148 is blocked by the flexible disk 100 can be formed between
15 the flexible disk 100 and the second sub valve 107. The intermediate chamber 147 constitutes the second passages 172 and 182, and the capacity thereof becomes variable when the flexible disk 100 bends. [0147]
With this configuration, in the extension stroke of the shock absorber 1 at the
20 time of low frequency input, the amount of the oil liquid flowing from the upper chamber 19 into the intermediate chamber 147 is large. Therefore, the flexible disk 100 is completely bent, and then the capacity of the intermediate chamber 147 is not increased. Therefore, as shown by the solid line in Fig. 5, it is possible to steeply raise the damping force in the extension stroke when the piston speed is less than a first predetermined
25 value vl. On the other hand, in the extension stroke of the shock absorber 1 at the time
68

of high frequency input at which the abnormal noise is apt to be generated, the amount of the oil liquid flowing from the upper chamber 19 into the intermediate chamber 147 is small. Therefore, it is possible to absorb the volume of the oil liquid flowing into the intermediate chamber 147 by the bending of the flexible disk 100. As a result, the 5 intermediate chamber 147 can be brought into a state similar to the state in which the intermediate chamber 147 constantly communicates with the lower chamber 20 through the communication passage 148 of the cap member 101. Accordingly, in comparison with the damping force characteristics at the time of low frequency input shown by the solid line in Fig. 5, the rise of the extremely low speed damping force becomes gentle as
10 shown by a two-dot chain line in Fig. 5. The change in damping force generated when the valve of the second damping force generating mechanism 183 is opened becomes smooth, and in the extremely low speed region (less than v2), the extremely low speed damping force with respect to the same piston speed becomes lower than that at the time of low frequency input. In other words, the second damping force generating
15 mechanism 183 can have a frequency-dependent function. [0148]
In this way, the shock absorber 1 generates the damping force sufficiently even at the extremely low speed with respect to the low frequency input in which the damping force is required even at the extremely low speed in order to improve the responsiveness
20 at the time of the fine steering input, the flat feeling in ride quality on a smooth road, or the like. Meanwhile, the shock absorber 1 weakens the damping force at the extremely low speed and makes the change of the damping force generated when the valve of the second damping force generating mechanism 183 is opened become smooth with respect to the high frequency input in which the abnormal noise is apt to be generated to suppress
25 the abnormal noise. Therefore, it is possible to achieve both the desired damping
69

performance at extremely low speed and the suppression of the abnormal noise. [0149]
Here, in order to verify the effect of suppressing the abnormal noise of the shock absorber 1 of the first embodiment, rod acceleration correlating with the generation of the 5 abnormal noise was analyzed. That is, one end of a spring mechanism having a
predetermined characteristic is fixed in position, the piston rod 21 of the shock absorber 1 is connected to the other end thereof, the cylinder 2 is connected to a vibration source, and the cylinder 2 is vibrated by the vibration source with a predetermined sinusoidal wave. In this case, the rod acceleration which is the acceleration of the piston rod 21
10 and the damping force of the shock absorber 1 were analyzed. Further, for comparison, the same analysis was performed with respect to a shock absorber of a comparative example having a configuration in which the bottom portion 122 of the cap member 101 does not have the communication passage 148 and the flexible disk 100 is not provided in the cap chamber 146 in comparison with the shock absorber 1. The analysis result is
15 shown in Fig. 6. [0150]
Fig. 6 shows the characteristics at the time of reversing the stroke from the contraction stroke to the extension stroke in which the abnormal noise is especially apt to be generated and the damping force shown by the two-dot chain line in Fig. 6 changes
20 from minus to plus. As is clear from Fig. 6, in the rod acceleration of the shock
absorber 1 of the first embodiment shown by the solid line in Fig. 6, a peak value on a plus side is close to 0 as shown by an arrow Yl and a peak value on a minus side is close to 0 as shown by an arrow Y2 as compared with rod acceleration of the comparative example shown by the broken line in Fig. 6. As a result, it can be seen that the effect of
25 suppressing the abnormal noise that correlates with the rod acceleration can be obtained.
70

[0151]
In the shock absorber 1 of the first embodiment, the disk protruding portion 302 that is constantly in contact with the bottom portion 122 of the cap member 101 is integrally formed with the flexible disk 100, and thus it is possible to suppress the 5 increase of the number of parts and the increase of the assembling man-hours. Further, since the flexible disk 100 can be manufactured by the press forming, the cost of parts can be reduced. [0152]
Further, the orifice 175 is disposed on the upstream side from the sub valve 110
10 of the second passage 182 in flow during the extension stroke in which the sub valve 110 is opened. As a result, during the contraction stroke, the sub valve 107 is opened with respect to the lower chamber 20, the oil liquid flows into the intermediate chamber 147, and the orifice 175 throttles the flow of the oil liquid flowing to the upper chamber 19. Therefore, the differential pressure between the intermediate chamber 147 and the lower
15 chamber 20 becomes small, the sub valve 110 in a closed state which receives the back pressure from the lower chamber 20 receives the same pressure as that of the lower chamber 20 from the intermediate chamber 147, and the received back pressure (the differential pressure) is suppressed. Therefore, the durability of the sub valve 110 can be improved.
20 [0153]
Further, the valve seat member passage portion 150 has the first passage portions 151 on an extension side and the second passage portions 152 on a contraction side, and the plurality of first passage portions 151 on an extension side and the plurality of second passage portions 152 on a contraction side are alternately provided at equal
25 intervals on the same circumference. Therefore, the valve seat portion 139 on an
71

extension side can be formed by the plurality of valve seat constituent portions 211 formed by surrounding the first passage portions 151, and the valve seat portion 135 on a contraction side can be formed by the plurality of valve seat constituent portion 201 formed by surrounding the second passage portions 152. Therefore, it is possible to 5 suppress sudden valve opening and hydraulic fluctuation at the time of valve opening of the second damping force generating mechanism 183 on an extension side including the sub valve 110 and the valve seat portion 139 and to smoothly change the damping force characteristics. [0154]
10 That is, as shown by the solid line in Fig. 5, in the extension stroke when the
piston speed is less than the first predetermined value vl, it is possible to smoothly change the damping force characteristics when the piston speed transitions to the extremely low speed region (vl or more and less than v2) higher than the first predetermined value vl at which the valve of the second damping force generating
15 mechanism 183 is opened after the damping force steeply rises. Here, the broken line shown in Fig. 5 is the damping force characteristics in a case in which the sub valve 110 is detached and seated with respect to one annular valve seat portion, but in comparison with this, the damping force characteristics of the shock absorber 1 of the first embodiment change smoothly.
20 [0155]
Similarly, in the second damping force generating mechanism 173 on a contraction side which includes the valve seat portion 135 having the same shape as that of the valve seat portion 139 and the sub valve 107, it is also possible to smoothly change the damping force characteristics at the time of valve opening.
25 [0156]
72

Moreover, since the plurality of first passage portions 151 on an extension side and the plurality of second passage portions 152 on a contraction side are alternately provided on the same circumference, it is possible to increase both the diameters of the sub valves 107 and 110, to lower the valve rigidity in both the extension and contraction 5 strokes, to suppress the hydraulic fluctuation, and to smoothly change the damping force characteristics. [0157]
Here, if the continuation of the damping force in the extremely low speed region is not smooth, in other words, if the damping coefficient becomes discontinuous, a
10 non-linear feeling will be given to the fine steering operation such as slowly turning the steering in the same lane. In addition, a steep change in damping force may make the ride quality stiff and uncomfortable. On the other hand, the shock absorber 1 of the first embodiment can suppress deterioration in steering stability and ride quality while increasing the damping force in the extremely low speed region. Further, since the
15 hydraulic fluctuation can be suppressed, the generation of the abnormal noise can also be suppressed. [0158]
Further, since the present embodiment has a structure in which the piston rod 21 is inserted into the piston 18, the cap member 101, and the valve seat member 109, it is
20 possible to compactly dispose the piston 18, the cap member 101, and the valve seat member 109. [0159]
Since a part of each of the second passages 172 and 182 is formed by being cut out or penetrated of the piston rod 21, the second passages 172 and 182 can be easily
25 formed.
73

[0160]
Since the radial passage 222 that communicates with the piston rod passage portion 51 and extends in the radial direction toward the first passage portion 151 on an extension side is formed in the valve seat member 109, it is possible to allow the piston 5 rod passage portion 51 and the first passage portion 151 on an extension side communicate with each other with a simple structure. [0161]
Since the orifice 175 is formed by being cut out of a disk 82 in the first damping force generating mechanism 41 on an extension side, which is in contact with the piston
10 18, the orifice 175 can be easily formed. [0162]
Since the differential pressure between the intermediate chamber 147 and the lower chamber 20 does not increase in both the expansion stroke and the contraction stroke, it is possible to use a thin pressed part as the cap member 101. Therefore, it is
15 advantageous in terms of manufacturability and weight reduction. [0163]
In the above first embodiment, the second damping force generating mechanisms 173 and 183 are provided on the lower chamber 20 side which is one of the upper chamber 19 and the lower chamber 20, but they can also be provided on the upper
20 chamber 19 side. In this case, for example, the cap member 101, the flexible disk 100, the plurality of disks 102, the sub valve 107, the valve seat member 109 on which the O-ring 108 is mounted, the sub valve 110, the disk 111, and the disk 113 are disposed between the annular member 69 and the disk 68 in that arrangement order with reversed in the axial direction. Therefore, the disk 113 of these is in contact with the annular
25 member 69, and the cap member 101 is in contact with the disk 68. Further, the disk 89
74

is in contact with the annular member 114. [0164]
Further, in this case, the plurality of disks 62 and the disk 82 having the cutout portion 90 are exchanged with each other such that the passage in the cutout portion 90 5 communicates with the passage in the annular groove 56 on a contraction side. In addition, the large-diameter hole portion 46 of the piston 18 is formed on the inner seat portion 49 side to be adjacent to and to face the cutout portion 90, and the passage cutout portion 30 is formed such that the piston rod passage portion 51 allows the passage of the cutout portion 90 of the disk 82, the passage in the large-diameter hole portion 46 of the
10 piston 18, and the passage in the large-diameter hole portion 133 of the valve seat member 109 to communicate with each other. [0165]
With this configuration, the second damping force generating mechanism 173 becomes the second damping force generation mechanism on an extension side, and the
15 second damping force generation mechanism 183 becomes the second damping force generation mechanism on a contraction side. Then, the first passage portion 151 becomes a passage portion on a contraction side, and the radial passage 222 of the valve seat member 109 communicates with the piston rod passage portion 51 and extends in the radial direction toward the first passage portion 151 on a contraction side. As a result, it
20 is possible to achieve both the desired damping performance at extremely low speed and the suppression of the abnormal noise in the contraction stroke. [0166] [Second embodiment]
Next, a second embodiment will be described mainly based on Fig. 7, focusing
25 on portions different from the first embodiment. The portions common to the first
75

embodiment are represented by the same terms and the same reference signs. [0167]
In a shock absorber 1A of the second embodiment, as shown in Fig. 7, instead of the flexible disk 100 having the disk protruding portion 302 of the first embodiment, a 5 flexible disk 100A (a flexible member or a moving member) and a step adjustment shim 321 are provided. [0168]
The flexible disk 100A is a plain disk (a flat disk without protrusions) which has a perforated circular flat plate shape having a constant thickness in a natural state before
10 being assembled to the shock absorber 1A, and into which the attachment shaft portion 28 of the piston rod 21 can be fitted. The flexible disk 100A has an inner peripheral surface and an outer peripheral surface coaxially disposed and has an axisymmetric shape When the attachment shaft portion 28 is fitted to the inner peripheral portion of the flexible disk 100A, the flexible disk 100A is positioned with respect to the piston rod 21
15 in the radial direction and is disposed coaxially therewith. The disk protruding portion 302 of the first embodiment is not formed in the flexible disk 100A. The flexible disk 100A is also formed by the press forming from a single plate material having a constant thickness. [0169]
20 The step adjustment shim 321 has a perforated circular flat plate shape having a
constant thickness and has an inner peripheral surface and an outer peripheral surface both of which are cylindrical surfaces and are coaxially disposed. The step adjustment shim 321 has an axisymmetric shape. The step adjustment shim 321 is also formed by the press forming from a single plate material having a constant thickness. The step
25 adjustment shim 321 is formed separately from the flexible disk 100A.
76

[0170]
The step adjustment shim 321 has an inner diameter larger than the outer diameter of the disk 102 and is larger than twice the maximum distance from the center of the bottom portion 122 to each of the plurality of passage holes 126. Further, the step 5 adjustment shim 321 has an outer diameter equal to the minimum inner diameter of the intermediate tapered portion 123 of the cap member 101. [0171]
The step adjustment shim 321 is placed on the bottom portion 122 of the cap member 101, and at that time, the step adjustment shim 321 is positioned with respect to
10 the cap member 101 in the radial direction by the intermediate tapered portion 123 and is disposed coaxially with the cap member 101. The step adjustment shim 321 is disposed to surround the entire plurality of passage holes 126 on the outer side in the radial direction of the bottom portion 122 and is in contact with the bottom portion 122 over the entire circumference. When the step adjustment shim 321 is placed on the bottom
15 portion 122, the surface opposite to the bottom portion 122 becomes a flat surface extending in a direction orthogonal to the axis of the cap member 101. [0172]
The flexible disk 100A and the step adjustment shim 321 are housed in the cap member 101, and at that time, the step adjustment shim 321 is disposed between the
20 flexible disk 100A and the bottom portion 122 of the cap member 101. The flexible
disk 100A is incorporated in the shock absorber 1, is interposed between the disk 102 and the bottom portion 122 on the inner peripheral side thereof, and is in contact with the step adjustment shim 321 on the outer peripheral side thereof over the entire circumference. As a result, the flexible disk 100A is elastically deformed in a tapered shape to be
25 separated from the bottom portion 122 in the axial direction toward the outer side in the
77

radial direction. [0173]
In the flexible disk 100A, a portion of the inner peripheral portion thereof which overlaps the disk 102 is an inner peripheral side contact portion 303A that is constantly in 5 contact with the bottom portion 122 of the cap member 101 and the disk 102 over the entire circumference. The outer diameter of the inner peripheral side contact portion 303 A is smaller than twice the minimum distance from the center of the bottom portion 122 to each of the plurality of passage holes 126. As a result, in the flexible disk 100A, the inner peripheral side contact portion 303A is disposed to surround the entire plurality
10 of passage holes 126 on the inner side in the radial direction of the bottom portion 122 and is in contact with the bottom portion 122 over the entire circumference. [0174]
The flexible disk lOOAhas the inner peripheral side contact portion 303A, an outer peripheral edge portion 306A, and a flexible portion 305A between them. The
15 outer peripheral edge portion 306A of the flexible disk 100A has an outer diameter larger than the inner diameter of the step adjustment shim 321 and smaller than the minimum inner diameter of the intermediate tapered portion 123 of the cap member 101. The flexible disk 100A is in contact with the step adjustment shim 321 at the outer peripheral edge portion 306A over the entire circumference and is elastically deformed in a tapered
20 shape such that the flexible portion 305A and the outer peripheral edge portion 306A are separated from the bottom portion 122 in the axial direction toward the outer side in the radial direction. The flexible disk 100A is deformed such that the flexible portion 305A approaches the bottom portion 122 or returns to its original state. [0175]
25 The flexible disk 100A, the step adjustment shim 321, the plurality of disks 102,
78

and the sub valve 107 are provided in the cap chamber 146. The flexible disk 100A is provided between the sub valve 107 in the cap chamber 146 and the bottom portion 122 of the cap member 101. The flexible disk 100A is constantly in contact with the step adjustment shim 321 provided to surround the entire plurality of passage holes 126 on the 5 outer side in the radial direction of the bottom portion 122 over the entire circumference. Further, in the flexible disk 100A, the inner peripheral side contact portion 303A is constantly in contact with the bottom portion 122 of the cap member 101 over the entire circumference to surround the entire plurality of passage holes 126 on the inner side in the radial direction of the bottom portion 122.
10 [0176]
Due to the flexible disk 100A and the step adjustment shim 321, the cap chamber 146 is divided into the intermediate chamber 147 on the sub valve 107 side and the communication chamber 149 communicating with the communication passage 148 in the plurality of passage holes 126. The flexible disk 100A blocks the communication of
15 the intermediate chamber 147 with the communication passage 148. In other words, in the cap chamber 146, between the sub valve 107 and the bottom portion 122 of the cap member 101, the flexible disk 100A that closes the communication passage 148 is provided. In other words, the intermediate chamber 147 of which the communication with the communication passage 148 is blocked by the flexible disk lOOAis formed
20 between the flexible disk 100A and the sub valve 107. As the flexible portion 305A of the flexible disk 100A bends, the volume of the intermediate chamber 147 changes. [0177]
The second embodiment has a volume variable mechanism 185 A which is partially different from the volume variable mechanism 185. The volume variable
25 mechanism 185 A of the second embodiment is constituted by the flexible disk 100A, the
79

step adjustment shim 321, the bottom portion 122 of the cap member 101, the communication chamber 149, and the communication passage 148. Also in the second embodiment, the flexible disk 100A changes to reduce the volume of the communication chamber 149 provided in parallel with the second passage 182 by deforming and moving 5 toward the bottom portion 122 and changes to increase the volume of the communication chamber 149 by deforming and moving away from the bottom portion 122. [0178]
In a case in which the piston 18 or the like is assembled to the piston rod 21, the annular member 69, the disk 68, the disk 67, the plurality of disks 66, the plurality of
10 disks 65, the plurality of disks 64, the disk 63, the plurality of disks 62, the piston 18, the disk 82, the disks 83, the disk 84, the plurality of disks 85, the disk 86, the plurality of disks 87, the plurality of disks 88, the disk 89, and the cap member 101 are superposed on the shaft step portion 29 in order while the attachment shaft portion 28 of the piston rod 21 is inserted as in the first embodiment.
15 [0179]
Further, the step adjustment shim 321, the flexible disk 100A, the plurality of disks 102 are superposed on the bottom portion 122 of the cap member 101 in order while the attachment shaft portion 28 is inserted. [0180]
20 Further, the sub valve 107, the valve seat member 109 on which the O-ring 108
is mounted, the sub valve 110, the disk 111, the disk 113, and the plurality of annular members 114 are superposed on the plurality of disks 102 in order while the attachment shaft portion 28 is inserted as in the first embodiment. In this state, the nut 115 is screwed to the male screw 31 of the piston rod 21 protruding with respect to the annular
25 member 114, and the nut 115 and the shaft step portion 29 clamp at least the inner
80

peripheral side of the above-described constituent elements except for the step
adjustment shim 321 in the axial direction.
[0181]
In this state, the flexible disk 100A is in contact with the step adjustment shim 5 321 at the outer peripheral edge portion 306A while being elastically deformed and presses the step adjustment shim 321 against the bottom portion 122 of the cap member
101. Further, in this state, in the flexible disk 100A, the inner peripheral side contact
portion 303 A is clamped between the bottom portion 122 of the cap member 101 and the
disk 102.
10 [0182]
In the flexible disk 100, when the outer peripheral edge portion 306A is in contact with the step adjustment shim 321 and the inner peripheral side contact portion 303 A is clamped between the bottom portion 122 of the cap member 101 and the disk
102, the outer peripheral edge portion 306A is in contact with the step adjustment shim
15 321 over the entire circumference in a state in which a preload corresponding to the
height of the step adjustment shim 321 is applied, and the step adjustment shim 321 is brought into contact with the bottom portion 122 over the entire circumference. As in the first embodiment, even when the sub valve 107 is lifted to the maximum, the sub valve 107 does not come into contact with the flexible disk 100A.
20 [0183]
The shock absorber 1A of the second embodiment includes the sub valve 110 provided on one side of the second passage 182 and the volume variable mechanism 185 A that changes the volume of the communication chamber 149 provided in parallel with the second passage 182. As a result, the volume variable mechanism 185 A makes
25 it possible to change the volume of the communication chamber 149 provided in parallel
81

with the second passage 182. Therefore, as in the first embodiment, it is possible to
change the flow rate of the oil liquid flowing through the second passage 182.
Therefore, it is possible to suppress the generation of abnormal noise.
[0184]
5 In the shock absorber 1A of the second embodiment, the intermediate chamber
147 of which the communication with the communication passage 148 is blocked by the flexible disk 100A and the step adjustment shim 321 is formed between the flexible disk 100A and the second sub valve 107, and the capacity of the intermediate chamber 147 is made variable by the bending of the flexible disk 100A. As a result, as in the first
10 embodiment, it is possible to achieve both the desired damping performance at extremely low speed and the suppression of the abnormal noise. [0185]
Further, the shock absorber 1A of the second embodiment uses the step adjustment shim 321 which is separate from the flexible disk 100A and the cap member
15 101. Therefore, it is possible to easily adjust the preload of the flexible disk 100A by selecting the step adjustment shim 321 from among a plurality of ones having different thicknesses for use. [0186]
In the above second embodiment, the second damping force generating
20 mechanisms 173 and 183 are provided on the lower chamber 20 side which is one of the upper chamber 19 and the lower chamber 20, but they can also be provided on the upper chamber 19 side. In this case, for example, the cap member 101, the step adjustment shim 321, the flexible disk 100A, the plurality of disks 102, the sub valve 107, the valve seat member 109 on which the O-ring 108 is mounted, the sub valve 110, the disk 111,
25 and the disk 113 are disposed between the annular member 69 (see Fig. 2) and the disk
82

68 (see Fig. 2) in that arrangement order with reversed in the axial direction. Besides this, as described in the first embodiment, the same changes as those in the case where the second damping force generating mechanisms 173 and 183 are provided in the upper chamber 19 are made. 5 [0187]
[Third embodiment]
Next, a third embodiment will be described mainly based on Fig. 8, focusing on portions different from the second embodiment. The portions common to the first embodiment are represented by the same terms and the same reference signs.
10 [0188]
In a shock absorber IB of the third embodiment, as shown in Fig. 8, the step adjustment shim 321 of the second embodiment is not provided. In the shock absorber IB of the third embodiment, a cap member 101B which is partially different from the cap member 101 of the first and second embodiments is provided instead of the cap member
15 101 of the first and second embodiments. [0189]
A bottom portion 122B of the cap member 101B is different from the bottom portion 122 of the first embodiment. The bottom portion 122B has a bottom portion main body 331 having a perforated circular plate shape and a constant thickness similar
20 to the bottom portion 122 of the first embodiment and an annular cap protruding portion 32IB (a cap member side protruding portion) that protrudes on the same side as the intermediate tapered portion 123 in the axial direction inside the intermediate tapered portion 123 in the radial direction from the outer peripheral edge portion of the bottom portion main body 331. The outer peripheral side of the cap protruding portion 321B is
25 connected to the intermediate tapered portion 123. The cap member 101B is also an
83

integrally formed product including the bottom portion 122B constituted by the bottom portion main body 331 and the cap protruding portion 32IB, the intermediate tapered portion 123, and the tubular portion 124 and is integrally formed by, for example, plastic working or cutting of a metal plate. 5 [0190]
The bottom portion 122B has a shape in which the step adjustment shim 321 which is a separate body in the second embodiment is integrally formed as the cap protruding portion 32IB on the bottom portion main body 331 similar to the bottom portion 122 of the second embodiment. The inner peripheral surface of the cap
10 protruding portion 32IB is a cylindrical surface, and a side of the cap protruding portion 321B opposite to the bottom portion main body 331 in the axial direction is a flat surface extending in a direction orthogonal to the axis of the cap member 101B. The plurality of passage holes 126 similar to those of the first and second embodiments which penetrate the bottom portion main body 331 in the axial direction of the bottom portion
15 main body 331 are formed inside the cap protruding portion 32IB of the bottom portion main body 331 in the radial direction in the bottom portion 122B. [0191]
In the flexible disk 100A, the inner peripheral side contact portion 303A on the inner peripheral side thereof is interposed between the disk 102 and the bottom portion
20 main body 331 in a state in which the flexible disk 100A is incorporated in the shock absorber IB, and the outer peripheral edge portion 306A on the outer peripheral side thereof is in contact with the cap protruding portion 32IB of the cap member 10IB over the entire circumference. As a result, the flexible disk 100A is elastically deformed in a tapered shape such that the flexible portion 305A and the outer peripheral edge portion
25 306A are separated from the bottom portion main body 331 in the axial direction toward
84

the outer side in the radial direction.
[0192]
The flexible disk lOOAis in contact with the cap protruding portion 321B over
the entire circumference to divide the cap chamber 146 into the intermediate chamber 5 147 and the communication chamber 149. As the flexible portion 305A of the flexible
disk 100A bends, the volume of the intermediate chamber 147 changes.
[0193]
The third embodiment has a volume variable mechanism 185B which is partially
different from the volume variable mechanism 185A. The volume variable mechanism 10 185B is constituted by the flexible disk 100A, the bottom portion 122B of the cap
member 101B, the communication chamber 149, and the communication passage 148.
Also in the volume variable mechanism 185B, the flexible disk 100A changes to reduce
the volume of the communication chamber 149 provided in parallel with the second
passage 182 by deforming and moving toward the bottom portion main body 331 of the 15 bottom portion 122B and changes to increase the volume of the communication chamber
149 by deforming and moving away from the bottom portion main body 331 of the
bottom portion 122.
[0194]
In a case in which the piston 18 or the like is assembled to the piston rod 21, the 20 annular member 69, the disk 68, the disk 67, the plurality of disks 66, the plurality of
disks 65, the plurality of disks 64, the disk 63, the plurality of disks 62, the piston 18, the
disk 82, the disks 83, the disk 84, the plurality of disks 85, the disk 86, the plurality of
disks 87, the plurality of disks 88, and the disk 89 are superposed on the shaft step
portion 29 in order while the attachment shaft portion 28 of the piston rod 21 is inserted 25 as in the first and second embodiments.

WE CLAIMS

A shock absorber comprising:
a cylinder which is filled with a working fluid;
5 a piston which is slidably provided in the cylinder and divides an inside of the
cylinder into two chambers;
a piston rod which is connected to the piston and extends outside the cylinder;
a first passage and a second passage through which the working fluid flows due
to movement of the piston;
10 a first damping force generating mechanism which is provided in the first
passage and generates a damping force; and
a second damping force generating mechanism which is provided in the second passage and generates a damping force,
wherein the second damping force generating mechanism includes
15 a sub valve provided on one side of the second passage, and
a volume variable mechanism that changes a volume of a volume chamber provided in parallel with the second passage. [Claim 2]
The shock absorber according to claim 1, wherein the volume variable 20 mechanism includes the volume chamber and a moving member that moves to change the volume of the volume chamber. [Claim 3]
The shock absorber according to claim 1 or 2, wherein, when a frequency thereof exceeds a predetermined frequency, a flow rate to the sub valve is limited by the 25 volume variable mechanism.
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[Claim 4]
The shock absorber according to any one of claims 1 to 3, wherein the first
passage and the second passage are connected in series.
[Claim 5]
5 The shock absorber according to any one of claims 1 to 3, wherein the first
passage and the second passage are connected in parallel. [Claim 6]
A shock absorber comprising:
a cylinder which is filled with a working fluid;
10 a piston which is slidably provided in the cylinder and divides an inside of the
cylinder into two chambers;
a piston rod which is connected to the piston and extends outside the cylinder;
a first passage and a second passage through which the working fluid flows due
to movement of the piston;
15 a first damping force generating mechanism which is provided in the first
passage and generates a damping force; and
a second damping force generating mechanism which is provided in the second passage and generates a damping force,
wherein the second damping force generating mechanism includes
20 one side sub valve provided on one side of a valve seat member passage portion
provided in a valve seat member of the second passage, and
a bottomed tubular cap member provided between the piston and the valve seat member in the second passage,
wherein the valve seat member is provided in the cap member, and the one side 25 sub valve is provided in a cap chamber between a bottom portion of the cap member and
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the valve seat member,
wherein, in the second passage, an orifice is disposed on an upstream side or a
downstream side from the one side sub valve in flow by which the one side sub valve is
opened,
5 wherein, in a region in which a piston speed is low, the one side sub valve is
opened in a state in which a valve of the first damping force generating mechanism is closed,
wherein, in a speed region in which the piston speed is higher than that in the region in which the piston speed is low, the valve of the first damping force generating 10 mechanism and the one side sub valve are both opened,
wherein a communication passage communicating with one chamber is formed at the bottom portion of the cap member,
wherein, in the cap chamber, between the one side sub valve and the bottom
portion of the cap member, a movable moving member is provided, and
15 wherein the shock absorber further comprises a volume variable mechanism in
which an intermediate chamber whose volume is changed by movement of the moving member is formed between the moving member and the one side sub valve. [Claim 7]
The shock absorber according to claim 6, further comprising:
20 the other side sub valve provided on the other side of the valve seat member
passage portion and provided in the one chamber; and
a volume variable mechanism in which a volume chamber whose volume is changed by movement of the moving member is formed between the moving member and the other side sub valve via the one chamber. 25 [Claim 8]
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The shock absorber according to claim 7, wherein an O-ring is provided at least
one of between the moving member and the bottom portion of the cap member and
between the moving member and the one side sub valve.
[Claim 9]
5 The shock absorber according to claim 7, wherein the moving member is
supported by two conical disk springs, and the conical disk springs are disposed such that their concave sides face each other in a natural state. [Claim 10]
A shock absorber comprising:
10 a cylinder which is filled with a working fluid;
a piston which is slidably provided in the cylinder and divides an inside of the cylinder into two chambers;
a piston rod which is connected to the piston and extends outside the cylinder;
a first passage and a second passage through which the working fluid flows from 15 the chamber on an upstream side to the chamber on a downstream side in the cylinder due to movement of the piston;
a first damping force generating mechanism which is provided in the first passage formed in the piston and generates a damping force; and
a second damping force generating mechanism which is provided in an annular 20 valve seat member disposed in one of the two chambers, is provided in the second passage which is parallel to the first passage, and generates a damping force,
wherein the second damping force generating mechanism includes
a first sub valve provided on one side of a valve seat member passage portion provided in the valve seat member of the second passage and a second sub valve 25 provided on the other side thereof, and
191

a bottomed tubular cap member provided between the piston and the valve seat member in the second passage,
wherein the valve seat member is provided in the cap member, the first sub valve is provided in the one chamber, and the second sub valve is provided in a cap 5 chamber between a bottom portion of the cap member and the valve seat member,
wherein, in the second passage, an orifice is disposed on an upstream side or a downstream side from the first sub valve in flow by which the first sub valve is opened,
wherein, in a region in which a piston speed is low, a valve of the second damping force generating mechanism is opened in a state in which a valve of the first 10 damping force generating mechanism is closed,
wherein, in a speed region in which the piston speed is higher than that in the
region in which the piston speed is low, the valve of the first damping force generating
mechanism and the valve of the second damping force generating mechanism are both
opened,
15 wherein a communication passage communicating with the one chamber is
formed at the bottom portion of the cap member,
wherein, in the cap chamber, between the second sub valve and the bottom
portion of the cap member, a flexible member that closes the communication passage is
provided, and
20 wherein an intermediate chamber of which communication with the
communication passage is blocked by the flexible member is formed between the flexible member and the second sub valve. [Claim 11]
The shock absorber according to claim 10, wherein a flexible member side 25 protruding portion which is constantly in contact with the bottom portion of the cap
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member is integrally formed with the flexible member. [Claim 12]
The shock absorber according to claim 10 or 11, wherein a cap member side protruding portion which is constantly in contact with the flexible member is integrally 5 formed with the bottom portion of the cap member. [Claim 13]
The shock absorber according to any one of claims 10 to 12, wherein the valve seat member passage portion has a passage portion on an extension side and a passage portion on a contraction side, and a plurality of the passage portions on an extension side 10 and a plurality of the passage portions on a contraction side are alternately provided on the same circumference. [Claim 14]
A shock absorber comprising:
a cylinder which is filled with a working fluid;
15 a piston which is slidably provided in the cylinder and divides an inside of the
cylinder into two chambers;
a piston rod which is connected to the piston and extends outside the cylinder;
a first passage and a second passage through which the working fluid flows from the chamber on an upstream side to the chamber on a downstream side in the cylinder 20 due to movement of the piston;
a first damping force generating mechanism which is provided in the first passage formed in the piston and generates a damping force; and
a second damping force generating mechanism which is provided in an annular valve seat member disposed in one of the two chambers, is provided in the second 25 passage which is parallel to the first passage, and generates a damping force,
193

wherein the second damping force generating mechanism includes
a first sub valve provided on one side of a valve seat member passage portion provided in the valve seat member of the second passage, and
a bottomed tubular cap member provided between the piston and the valve seat 5 member in the second passage,
wherein the valve seat member is provided in the cap member, and the first sub valve is provided in the one chamber,
wherein, in the second passage, an orifice is disposed on an upstream side or a
downstream side from the first sub valve in flow by which the first sub valve is opened,
10 wherein, in a region in which a piston speed is low, a valve of the second
damping force generating mechanism is opened in a state in which a valve of the first damping force generating mechanism is closed,
wherein, in a speed region in which the piston speed is higher than that in the region in which the piston speed is low, the valve of the first damping force generating 15 mechanism and the valve of the second damping force generating mechanism are both opened,
wherein a communication passage communicating with the one chamber is formed at the bottom portion of the cap member,
wherein a flexible member that closes the communication passage is provided in 20 a cap chamber between the bottom portion of the cap member and the valve seat member, and
wherein an intermediate chamber of which communication with the communication passage is blocked by the flexible member is formed between the flexible
member and the valve seat member.