Description Title of Invention: FLUID PRESSURE CYLINDER
Technical Field
The present invention relates to a fluid pressure cylinder in which a piston is displaced along an axial direction under the supply of a pressure fluid. Background Art
Heretofore, as a means for transporting workpieces, for example, a fluid pressure cylinder has been used having a piston that is displaced under the supply of a pressure fluid. For example, as disclosed in Japanese Laid-Open Patent Publication No. 2014-129853 (Patent Document 1), in the fluid pressure cylinder, a head cover and a rod cover are disposed on both ends of the cylinder tube, a piston is disposed dis-placeably in the interior of the cylinder tube, and a piston rod connected to the piston is supported displaceably through the rod cover. Further, on outer circumferential surfaces of the head cover and the rod cover, ports are formed respectively for supplying and discharging the pressure fluid, and the ports project diametrally outward with respect to the outer circumferential surface of the cylinder tube.
Further, with the fluid pressure cylinder according to Japanese Laid-Open Patent Publication No. 2000-337312 (Patent Document 2), a head cover and a rod cover are connected respectively by screw-engagement with respect to both ends of a cylinder tube. Summary of Invention
Although recently it has been desired to reduce the size of such fluid pressure cylinders, with the fluid pressure cylinder according to the aforementioned Patent Document 1, since the respective ports project diametrally outward with respect to the cylinder tube, the diametral dimension of the fluid pressure cylinder is increased in size.
Further, with the fluid pressure cylinder according to Patent Document 2, since it is necessary for female threaded portions to be disposed on both ends of the cylinder tube, and for male threaded portions to be provided for a predetermined length re-spectively on the outer circumferential surfaces of the head cover and the rod cover, the lengthwise dimension of the fluid pressure cylinder is made greater in size by the lengths of the female threaded portions and the male threaded portions.
A general object of the present invention is to provide a fluid pressure cylinder in which cover members can easily be attached/detached, while the size of the fluid pressure cylinder in the axial direction and the diametral direction can be kept small in size.

The present invention is characterized by a fluid pressure cylinder comprising a cylindrical cylinder tube including a cylinder chamber in interior thereof that is circular in cross section, cover members formed with circular shapes in cross section corre-sponding to the cylinder chamber and which are mounted in ends of the cylinder tube, and a piston disposed displaceably along the cylinder chamber, wherein:
a pair of ports through which a pressure fluid is supplied and discharged are provided on a more diametrally inward side than an outer circumferential surface of the cylinder tube; and
latching members configured to latch the cover members in an axial direction are disposed in the ends of the cylinder tube, the latching members being engaged with respect to the cylinder tube and constituted from rings with resilient forces in a diametral direction, and the cover members are attachable and detachable with respect to the cylinder tube by attachment and detachment of the rings with respect to the cylinder tube.
According to the present invention, in the fluid pressure cylinder, the pair of ports through which the pressure fluid is supplied and discharged are provided on a more di-ametrally inward side than the outer circumferential side of the cylinder tube, and the latching members that latch the cover members in the axial direction are disposed in the ends of the cylinder tube, the latching members being engaged with respect to the cylinder tube and constituted from rings with a resilient force in the diametral direction, wherein the cover members are attachable and detachable with respect to the cylinder tube by attachment and detachment of the ring with respect to the cylinder tube.
Consequently, since the amount at which fittings or the like project outward in the diametral direction when such fittings are connected to the ports that are arranged on a diametrally inward side of the cylinder tube can be suppressed compared to a con-ventional fluid pressure cylinder, the fluid pressure cylinder can be reduced in size in the diametral direction. Further, by constituting the cover members to be fixed on ends of the cylinder tube by the latching members, in comparison with a conventional fluid pressure cylinder in which the cover members are fixed by screw-engagement with respect to the cylinder tube, since there is no need for screw members or the like for effecting such screw-engagement, the fluid pressure cylinder can be reduced in size in the axial direction due to the absence of such screw members. Furthermore, since the cover members are fixed with respect to the cylinder tube by the latching members, and the fixed state thereof can be released easily by removing the rings that serve as the latching members, in comparison with a conventional fluid pressure cylinder in which the cover members are screw-engaged with respect to the cylinder tube, the at-tachment and detachment operations of the cover members with respect to the cylinder

tube can more easily be performed.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings, in which preferred embodiments of the present invention are shown by way of illustrative example. Brief Description of Drawings
[fig.l]FIG. 1 is an overall cross-sectional view of a fluid pressure cylinder according to a first embodiment of the present invention;
[fig.2]FIG. 2A is an enlarged cross-sectional view showing the vicinity of a head cover in the fluid pressure cylinder of FIG. 1; FIG. 2B is a front view in which the head cover is observed from an axial direction;
[fig.3]FIG. 3A is an enlarged cross-sectional view showing the vicinity of a rod cover in the fluid pressure cylinder of FIG. 1; FIG. 3B is a front view in which the rod cover is observed from an axial direction;
[fig.4]FIG. 4 is an overall cross-sectional view of a fluid pressure cylinder according to a second embodiment of the present invention;
[fig.5]FIG. 5A is an enlarged cross-sectional view showing the vicinity of a head cover in the fluid pressure cylinder of FIG. 4; FIG. 5B is a front view in which the head cover is observed from an axial direction;
[fig.6]FIG. 6A is an enlarged cross-sectional view showing the vicinity of a rod cover in the fluid pressure cylinder of FIG. 4; FIG. 6B is a front view in which the rod cover is observed from an axial direction;
[fig.7]FIG. 7 is an exploded perspective view of the fluid pressure cylinder of FIG. 4; [fig.8]FIG. 8 is an overall cross-sectional view of a fluid pressure cylinder according to a third embodiment of the present invention;
[fig.9]FIG. 9 is an exterior perspective view of the fluid pressure cylinder shown in FIG. 8;
[fig. 10]FIG. 10 is an exploded perspective view of the fluid pressure cylinder shown in FIG. 9;
[fig. 11]FIG. 11 is a cross-sectional view taken along line XI-XI of FIG. 8; [fig.l2]FIG. 12 is an overall cross-sectional view of a fluid pressure cylinder according to a fourth embodiment of the present invention;
[fig.l3]FIG. 13 is a cross-sectional view taken along line XIII-XIII of FIG. 12; [fig. 14] FIG. 14 is an exterior perspective view showing a condition in which an at-tachment is installed thereon for attaching the fluid pressure cylinder of FIG. 1 to another member; [fig.l5]FIG. 15 is a partially exploded perspective view showing a condition in which

the attachment is removed from the fluid pressure cylinder of FIG. 14;
[fig. 16]FIG. 16 is a front view in which the fluid pressure cylinder of FIG. 14 is seen
from the attachment side;
[fig.l7]FIG. 17 is an exterior perspective view showing a condition prior to assembly,
of a case in which the fluid pressure cylinder of FIG. 14 is fixed to another member
arranged below the fluid pressure cylinder;
[fig.l8]FIG. 18 is a cross-sectional view of a condition in which the fluid pressure
cylinder of FIG. 17 is fixed;
[fig.l9]FIG. 19 is an exterior perspective view showing a condition prior to assembly,
of a case in which the fluid pressure cylinder of FIG. 14 is fixed to another member
arranged on a side of the fluid pressure cylinder; and
[fig.20]FIG. 20 is a cross-sectional view of a condition in which the fluid pressure
cylinder of FIG. 19 is fixed.
Description of Embodiments
As shown in FIG. 1, a fluid pressure cylinder 10 includes a cylindrical cylinder tube 12, a head cover (cover member) 14 mounted in one end of the cylinder tube 12, a rod cover (cover member) 16 mounted in another end of the cylinder tube 12, a piston 18 that is disposed displaceably in the interior of the cylinder tube 12, and a piston rod 20 that is connected to the piston 18.
The cylinder tube 12, for example, is formed from a metal material such as stainless steel or the like, and is made up from a tubular body that extends with a constant cross-sectional area in the axial direction (the directions of arrows A and B), and in the interior thereof, a cylinder chamber 22 is formed in which the piston 18 and the piston rod 20 are accommodated. Further, cylindrical bodies 24a, 24b, which are larger in diameter than the cylinder tube 12, are connected respectively to both ends of the cylinder tube 12.
As shown in FIGS. 1, 2A, and 3A, the cylindrical bodies 24a, 24b, for example, are formed from a metal material such as stainless steel or the like with circular shapes in cross section, and have a predetermined width along the axial direction. In addition, in the cylindrical bodies 24a, 24b, inner circumferential surfaces of ends thereof are joined respectively by welding in a state of abutment against the outer circumferential surface of the cylinder tube 12. More specifically, portions of the cylindrical bodies 24a, 24b are disposed in an overlapping manner in the axial direction (the directions of arrows A and B) with respect to both ends of the cylinder tube 12, and the opposite ends of the cylinder tube 12 are formed in stepwise shapes by the cylindrical bodies 24a, 24b, which are expanded in diameter, being disposed on the outer side in the diametral directions with respect to the cylinder tube 12.

Further, annular engagement grooves 26, which are recessed diametrally outward, are formed on the inner circumferential surface of the cylindrical bodies 24a, 24b, and later-described latching rings 50 are engaged respectively therein.
Furthermore, holes 28, which penetrate diametrally between the engagement grooves 26 and the connection sites to which the cylinder tube 12 is connected, are formed in the cylindrical bodies 24a, 24b. Rotation preventing screws (pin members) 30 are screw-engaged from an outer circumferential side in the holes 28, and are engaged re-spectively in screw holes 32 formed in outer circumferential surfaces of the head cover 14 and the rod cover 16. Owing thereto, rotational displacement of the cylindrical bodies 24a, 24b, respectively, with respect to the head cover 14 and the rod cover 16 is restricted.
Stated otherwise, the rotation preventing screws 30 function as rotation preventing means for restricting rotational displacement of the cylindrical bodies 24a, 24b with respect to the head cover 14 and the rod cover 16.
As shown in FIGS. 1 through 2B, the head cover 14, for example, is formed with a circular shape in cross section from a metal material such as stainless steel or the like, and is inserted into the interior of the cylinder tube 12 and the cylindrical body 24a.
The outer circumferential surface of the head cover 14 is formed in a stepwise shape, such that the other end side thereof (in the direction of the arrow B) expands slightly in diameter, and by abutment of the one end of the cylinder tube 12 against the stepped portion 34, positioning of the cylinder tube 12 in the axial direction (the direction of the arrow B) with respect to the head cover 14 is carried out, together with the other end side (in the direction of the arrow B), which is formed with a large diameter, being covered by the cylindrical body 24a.
In a state in which the cylinder tube 12 is positioned with respect to the head cover 14, an end of the cylindrical body 24a and another end of the head cover 14 are sub¬stantially coplanar (see FIG. 2A).
Further, a recess 36, which is circular shaped in cross section and is recessed di-ametrally inward, is formed at a small diameter location on the outer circumferential surface of the head cover 14. In the recess 36, a first fluid port 38 is formed through which a pressure fluid is supplied and discharged. The first fluid port 38 extends di-ametrally inward perpendicular to the axial direction of the head cover 14, and com-municates with a first communication hole 40 that is formed in the center of the head cover 14. The recess 36 is exposed to the outer circumferential side through a port hole 42a, which is formed in the cylinder tube 12 that covers the outer circumferential side of the head cover 14. In addition, a fitting 44 (the two-dot-dashed line shape) is connected through the port hole 42a to the first fluid port 38, to and from which the pressure fluid is supplied and discharged through piping.

] The first communication hole 40 opens in facing relation to the side of the cylinder tube 12 (in the direction of the arrow A) in the center in one end of the head cover 14. Together therewith, an end of the first communication hole 40 on the side of the cylinder chamber 22 (in the direction of the arrow A) expands in diameter, and a first damper 46 is mounted in the interior thereof. The first damper 46, for example, is formed in a ring shape from an elastic material, and is disposed such that the end thereof projects toward the side of the cylinder tube 12 (in the direction of the arrow A) slightly with respect to the end of the head cover 14.
] On the other hand, an annular recess 48a, the diametral outer side of which is
recessed in the axial direction (in the direction of the arrow A), is formed on the other end of the head cover 14. An outer circumferential side of the annular recess 48a is covered by the cylindrical body 24a, together with the latching ring 50 being held in the annular recess 48a. Further, multiple (for example, four) first attachment holes 52, which extend in the axial direction (the direction of the arrow A) at a location more on the inner circumferential side than the annular recess 48a, are formed in the other end of the head cover 14. The fluid pressure cylinder 10 can be fixed in place by screw-engagement of attachment bolts (not shown), which are inserted through another apparatus or the like, with respect to the first attachment holes 52. Moreover, the first attachment holes 52, for example, as shown in FIG. 2B, are disposed at equal intervals of separation mutually on a diameter that passes through the center of the head cover 14.
] Further, the rotation preventing screw 30 that is inserted through the cylindrical body 24a is screw-engaged into the screw hole 32 that is formed in the outer circumferential surface of the head cover 14, whereby a state is brought about in which relative ro¬tational displacement between the head cover 14 and the cylindrical body 24a and the cylinder tube 12 is restricted.
] As shown in FIGS. 1, 3A, and 3B, the rod cover 16, for example, is formed with a circular shape in cross section from a metal material such as stainless steel or the like, and is inserted into the interior of the cylinder tube 12 and the cylindrical body 24b.
] The outer circumferential surface of the rod cover 16, in the same manner as the head cover 14, is formed in a stepwise shape, such that the other end side thereof (in the direction of the arrow A) expands slightly in diameter, and by abutment of the other end of the cylinder tube 12 against the stepped portion 56, positioning of the cylinder tube 12 in the axial direction (the direction of the arrow A) with respect to the rod cover 16 is carried out, together with the other end side (in the direction of the arrow A), which is formed with a large diameter, being covered by the cylindrical body 24b.
] In a state in which the cylinder tube 12 is positioned with respect to the rod cover 16, an end of the cylindrical body 24b and another end of the rod cover 16 are substantially

coplanar (see FIG. 3A).
Further, a recess 58, which is circular shaped in cross section and is recessed di-ametrally inward at a small diameter location, is formed on the outer circumferential surface of the rod cover 16. In the recess 58, a second fluid port 60 is formed through which a pressure fluid is supplied and discharged. The second fluid port 60 extends di-ametrally inward perpendicular to the axial direction of the rod cover 16, and com-municates with a rod hole 62 and a second communication hole 64 that are formed in the center of the rod cover 16.
The recess 58 is exposed to the outer circumferential side through a port hole 42b, which is formed in the cylinder tube 12 that covers the outer circumferential side of the rod cover 16. In addition, a fitting 44 (the two-dot-dashed line shape) is connected through the port hole 42b to the second fluid port 60, to and from which the pressure fluid is supplied and discharged through piping.
The second communication hole 64 opens in facing relation to the side of the cylinder tube 12 (in the direction of the arrow B) in the center in one end of the rod cover 16, while additionally, the rod hole 62 that penetrates in the axial direction (the directions of arrows A and B) is formed in the center of the second communication hole 64. Further, an end of the second communication hole 64 on the side of the cylinder chamber 22 (in the direction of the arrow B) expands in diameter, and a second damper 66 is mounted in the interior thereof. The second damper 66, for example, is formed in a ring shape from an elastic material, and is disposed such that the end thereof projects toward the side of the cylinder tube 12 (in the direction of the arrow B) slightly with respect to the end of the rod cover 16.
A rod packing 68 and a bush 70 are disposed through annular grooves in the rod hole 62, and by sliding respectively along the outer circumferential surface of the piston rod 20, leakage of pressure fluid from between the piston rod 20 and the rod cover 16 is prevented, while in addition, the piston rod 20 is guided along the axial direction (the directions of arrows A and B).
On the other hand, an annular recess 48b, the diametral outer side of which is recessed in the axial direction (in the direction of the arrow B) is formed on the other end of the rod cover 16. An outer circumferential side of the annular recess 48b is covered by the cylindrical body 24b, together with the latching ring 50 being held in the annular recess 48b.
Further, multiple (for example, four) second attachment holes 72, which extend in the axial direction (the direction of the arrow B) at a location more on the inner cir-cumferential side than the annular recess 48b, are formed in the other end of the rod cover 16. The fluid pressure cylinder 10 can be fixed in place by screw-engagement of attachment bolts (not shown), which are inserted through another apparatus or the like,

with respect to the second attachment holes 72. Moreover, the second attachment holes 72, for example, as shown in FIG. 3B, are disposed at equal intervals of separation mutually on a diameter that passes through the center of the rod cover 16.
Furthermore, the rotation preventing screw 30 that is inserted through the cylindrical body 24b is screw-engaged into the screw hole 32 that is formed in the outer circum-ferential surface of the rod cover 16, whereby a state is brought about in which relative rotational displacement between the rod cover 16 and the cylindrical body 24b and the cylinder tube 12 is restricted.
The latching rings 50, for example, are formed substantially with C-shapes in cross section from a metal material, and are mounted respectively in the engagement grooves 26 that are formed in the cylindrical bodies 24a, 24b. The latching rings 50 are formed in shapes corresponding to the engagement grooves 26 and have elastic forces so as to expand diametrally outward. Together therewith, jig holes 74 are formed respectively at locations that are expanded diametrally inward on open ends thereof.
Additionally, by a non-illustrated jig being inserted into the pair of jig holes 74, and by the expanded parts with the jig holes 74 being displaced in directions to approach one another mutually, the latching rings 50 can be deformed elastically and diametrally inwardly in opposition to the elastic force of the latching rings 50.
In a state in which the head cover 14 and the rod cover 16 are inserted through the interiors of the cylindrical bodies 24a, 24b and the cylinder tube 12, and the one end and the other end of the cylinder tube 12 are placed in abutment with the stepped portions 34, 56 and positioned in the axial direction, the latching rings 50 are engaged respectively in the engagement grooves 26 of the cylindrical bodies 24a, 24b. As a result, the latching rings 50 abut against the wall surfaces of the annular recesses 48a, 48b of the head cover 14 and the rod cover 16, and disengagement of the head cover 14 and the rod cover 16 from the open-ended sides of the cylindrical bodies 24a, 24b is re¬stricted.
Stated otherwise, the latching rings 50 function as latching members for fixing the head cover 14 and the rod cover 16 with respect to the cylinder tube 12.
As shown in FIGS. 1 and 2A, the piston 18 is formed with a circular shape in cross section, and is accommodated in the cylinder chamber 22 displaceably along the axial direction (in the directions of arrows A and B), together with a piston packing 76, a magnet 78, and a wear ring 80 being disposed respectively through annular grooves on the outer circumferential surface of the piston 18. Further, one end of the piston rod 20, which is inserted through a central portion of the piston 18, is connected integrally with the piston 18 by caulking.
In addition, by the piston packing 76 being placed in abutment with the inner circum-ferential surface of the cylinder tube 12, leakage of pressure fluid from between the

piston 18 and the cylinder tube 12 is prevented, and by abutment of the wear ring 80 against the inner circumferential surface of the cylinder tube 12, the piston 18 is guided along the axial direction. Further, magnetism of the magnet 78 is detected by a position detecting sensor, which is provided on an outer side of the cylinder tube 12, whereby the position of the piston 18 in the interior of the cylinder tube 12 can be detected.
The piston rod 20 is made up from a shaft having a predetermined length in the axial direction (the directions of arrows A and B). One end of the piston rod 20 is connected to the center of the piston 18, whereas the other end thereof projects to the exterior of the fluid pressure cylinder 10 through the rod hole 62 of the rod cover 16.
The fluid pressure cylinder 10 according to the first embodiment of the present invention is constructed basically as described above. Next, a case in which the head cover 14 is assembled with respect to the cylinder tube 12 will be described while referring to FIGS. 1 and 2A.
Since assembly of the rod cover 16 with respect to the cylinder tube 12 is roughly the same as the case of the head cover 14, detailed description of the case of the rod cover 16 will be omitted.
First, the head cover 14 is inserted into the interior of the opened cylinder tube 12 from one end side (in the direction of the arrow B), and by abutment of the stepped portion 34 thereof against the one end of the cylinder tube 12, a positioned state is brought about in which further movement of the head cover 14 toward the other end side of the cylinder tube 12 (in the direction of the arrow A) is restricted. In the po-sitioned state, a condition is provided in which the annular recess 48a of the head cover 14 is covered by the cylindrical body 24a.
Next, by a non-illustrated jig, which is inserted into the pair of jig holes 74, in a state in which the latching ring 50 is elastically deformed diametrally inward, the head cover 14 is inserted into the annular recess 48a, and in a state in which a portion thereof is inserted into the engagement groove 26, the deformed state of the jig is released. Con-sequently, the latching ring 50 is expanded in diameter by the elasticity thereof and engages with the engagement groove 26, whereby a condition is brought about in which movement of the head cover 14 in a direction (the direction of the arrow B) away from the cylinder tube 12 is restricted by the latching ring 50 that is engaged with the cylindrical body 24a.
More specifically, since movement of the head cover 14 toward the side of the rod cover 16 (in the direction of the arrow A) is restricted by abutment of the stepped portion 34 with respect to the cylinder tube 12, and since movement thereof in a direction away from the rod cover 16 (in the direction of the arrow B) is restricted by the latching ring 50, a fixed state is established in which displacement of the head cover 14 in the axial direction (the directions of arrows A and B) with respect to the

end of the cylinder tube 12 is restricted.
Lastly, the screw hole 32 of the head cover 14 and the hole 28 of the cylindrical body 24a are placed in matching relation, and by insertion and screw-rotation of the rotation preventing screw 30 from the outer circumferential side, rotation of the head cover 14 with respect to the cylindrical body 24a and the cylinder tube 12 is restricted. Stated otherwise, by the rotation preventing screw 30, the head cover 14 is positioned in the circumferential direction with respect to the cylindrical body 24a. Consequently, the port hole 42a that opens on the outer circumferential surface of the cylinder tube 12 is positioned in facing relation to the first fluid port 38.
As a result, assembly of the head cover 14 with respect to one end of the cylinder tube 12 is completed.
On the other hand, in the case that the head cover 14 is to be removed from the cylinder tube 12, first, the rotation preventing screw 30 is rotated, and the rotation preventing screw 30 is taken out from the head cover 14 and the cylindrical body 24a. Together therewith, using the non-illustrated jig, the latching ring 50 is elastically deformed diametrally inward, and is taken out from the engagement groove 26. Owing thereto, the head cover 14 is released from its fixed state with respect to the cylinder tube 12, whereby the head cover 14 can be moved and taken out in a direction (the direction of the arrow B) to separate away from the cylinder tube 12.
Next, operations of the fluid pressure cylinder 10, which is assembled as described above, will be explained. The condition shown in FIG. 1, in which the piston 18 is moved to the side of the head cover 14 (in the direction of the arrow B), will be described as an initial condition.
First, a pressure fluid is supplied to the first fluid port 38 from a non-illustrated pressure fluid supply source. In this case, the second fluid port 60 is placed beforehand in a state of being open to atmosphere under a switching action of a non-illustrated switching valve. Accordingly, the pressure fluid is supplied to the first communication hole 40 from the first fluid port 38, and by the pressure fluid that is supplied into the cylinder chamber 22 from the first communication hole 40, the piston 18 is pressed toward the side of the rod cover 16 (in the direction of the arrow A). In addition, under the displacement action of the piston 18, the piston rod 20 is displaced together with the piston 18, and a displacement end position is reached by the piston 18 coming into abutment against the second damper 66.
Next, in the case that the piston 18 is to be displaced in an opposite direction (in the direction of the arrow B), the pressure fluid is supplied to the second fluid port 60, together with the first fluid port 38 being opened to atmosphere under a switching action of a non-illustrated switching valve. In addition, the pressure fluid is supplied into the cylinder chamber 22 from the second fluid port 60 through the second commu-

nication hole 64, whereupon the piston 18 is pressed by the pressure fluid that is supplied into the cylinder chamber 22 toward the side of the head cover 14 (in the direction of the arrow B).
Consequently, under the displacement action of the piston 18, the piston rod 20 is displaced together with the piston 18, and the initial position is restored (see FIG. 1) by the piston 18 coming into abutment against the first damper 46 of the head cover 14.
In the foregoing manner, according to the first embodiment, in the fluid pressure cylinder 10, the recesses 36, 58, which are recessed diametrally inward with respect to the outer circumferential surfaces of the head cover 14 and the rod cover 16, are provided, and the first and second fluid ports 38, 60 open inside the recesses 36, 58. Therefore, the amount by which the fittings 44 and pipings, etc., that are connected to the first and second fluid ports 38, 60 project can be suppressed. As a result, compared to the conventional fluid pressure cylinder in which the ports project out diametrally with respect to the cylinder tube 12, the fluid pressure cylinder 10 can be reduced in size in the diametral direction, and the space on the outer circumferential side of the fluid pressure cylinder 10 can be utilized effectively.
Further, a structure is provided in which the head cover 14 and the rod cover 16 are capable of being fixed by the latching rings 50, which can be engaged with respect to the cylindrical bodies 24a, 24b provided on both ends of the cylinder tube 12. Therefore, compared to the conventional fluid pressure cylinder in which the head cover and the rod cover are affixed by being screw-engaged with respect to both ends of the cylinder tube, since there is no need to provide threaded portions, respectively, for the purpose of mutual screw-engagement between the cylinder tube 12 and the head cover 14 and the rod cover 16, the longitudinal dimension of the fluid pressure cylinder 10 in the axial direction can be reduced in size significantly.
Furthermore, compared to the conventional fluid pressure cylinder in which the head cover and the rod cover are connected by being screw-engaged with respect to both ends of the cylinder tube, the operation to attach and detach the head cover 14 and the rod cover 16 with respect to the cylinder tube 12 can be performed easily, simply by installation and removal of the latching rings 50.
Next, a fluid pressure cylinder 100 according to a second embodiment is shown in FIGS. 4 through 7. Constituent elements, which are the same as those of the above-described fluid pressure cylinder 10 according to the first embodiment, are denoted by the same reference characters, and detailed description of such features is omitted.
The fluid pressure cylinder 100 according to the second embodiment differs from the fluid pressure cylinder 10 according to the first embodiment, in that a head cover 102 and a rod cover 104 are formed from plate members.
As shown in FIGS. 4 through 6B, the fluid pressure cylinder 100 comprises a plate-

shaped head cover 102 that closes one end of a cylinder tube 106, and the cylindrical shaped rod cover 104 that closes the other end of the cylinder tube 106.
The head cover 102 is disposed in the interior of one end of the cylinder tube 106, and a port hole 42a opens on an outer circumferential surface of another end side (in the direction of the arrow A), which is separated a predetermined distance from the one end thereof. In the interior of the cylinder tube 106, a first port member 108 that faces toward the port hole 42a is fixed by welding or the like. The first port member 108 includes in the interior a first fluid port 110 with threads engraved thereon, and a fitting 44 (the two-dot-dashed line shape) is connected to the first port member 108. More specifically, the first port member 108 is disposed so as to project diametrally inward with respect to the cylinder tube 106.
Meanwhile, on the other end of the cylinder tube 106, in which the rod cover 104 is disposed in the interior thereof, a cylindrical body 24b is welded on the outer circum-ferential surface thereof, together with a port hole 142 opening at a position on the one end side (in the direction of the arrow B) of the cylinder tube 106 with respect to an end of the cylindrical body 24b.
The head cover 102, for example, is formed with a circular disk shape of a constant thickness from a metal material such as stainless steel or the like, which is inserted into the one end of the cylinder tube 106, and is fixed thereto by welding or the like. Further, on the head cover 102, multiple (for example, four) first boss members 112 are provided at positions on predetermined diameters with respect to the center of the head cover 102.
The first boss members 112 are formed in cylindrical shapes with screw holes 114 being formed in the interior thereof, and are inserted into holes 116 that are formed in the head cover 102. Ends of the first boss members 112 are fixed by welding or the like in a coplanar state with the end surface of the head cover 102. More specifically, the first boss members 112 are disposed so as to project toward the side of the cylinder tube 106 (in the direction of the arrow A) with respect to the head cover 102.
Further, first dampers 118 made from an elastic material such as rubber or the like are disposed respectively on the other ends of the first boss members 112, and are arranged in facing relation to the cylinder chamber 22.
In addition, the screw holes 114 of the first boss members 112 function as attachment holes, which are used when the fluid pressure cylinder 100 is fixed to another apparatus or the like.
The rod cover 104 includes a main body portion 120, which is formed, for example, from a metal material such as stainless steel or the like and has a U-shape in cross section, and a cylindrical shaped holder portion 122 provided in the center of the main body portion 120. The main body portion 120 has a rod hole 126 formed in the center

of a base part 124 that is formed in a disk shape and through which the piston rod 20 is inserted. An end of the holder portion 122 is joined by welding or the like so as to be coaxial with the rod hole 126. More specifically, the holder portion 122 is formed sub-stantially in parallel with a circumferential wall portion 128 that extends in an axial direction from the outer edge of the base part 124 in the main body portion 120.
Further, multiple (for example, four) second boss members 130 are provided at positions on predetermined diameters centrally about the rod hole 126 on the base part 124 of the main body portion 120.
The second boss members 130 are formed in cylindrical shapes with the screw holes 114 being formed in the interior thereof, and are inserted into holes 132 that are formed in the rod cover 104. Ends of the second boss members 130 are fixed by welding or the like in a coplanar state with the end surface of the rod cover 104. More specifically, the second boss members 130 are disposed so as to project toward the side of the cylinder tube 106 (in the direction of the arrow B) with respect to the rod cover 104.
Further, second dampers 134 made from an elastic material such as rubber or the like are disposed respectively on the other ends of the second boss members 130, and are arranged in facing relation to the cylinder chamber 22.
In addition, the screw holes 114 of the second boss members 130 function as at-tachment holes, which are used when the fluid pressure cylinder 100 is fixed to another apparatus or the like.
Further, the circumferential wall portion 128 on the main body portion 120 is ac-commodated so as to be capable of sliding along the inner circumferential surface of the cylindrical body 24b, and by abutting against a seal ring 136 that is provided on the inner circumferential surface of the cylindrical body 24b, leakage of pressure fluid passing between the cylinder tube 106 and the rod cover 104 is prevented.
A second port member 138 is disposed so as to penetrate in a diametral direction on the circumferential wall portion 128. The second port member 138 does not project di-ametrally outward with respect to the circumferential wall portion 128, and is fixed in¬tegrally by welding or the like in a state of projecting diametrally inward.
The second port member 138 includes in the interior thereof a second fluid port 140 on which screw threads are engraved, and in a state in which the rod cover 104 is disposed in the interior of the cylinder tube 106, the second port member 138 is arranged in facing relation to the port hole 142 of the cylindrical body 24b, and a fitting 44 is connected thereto through the port hole 142. Moreover, the fitting 44 is connected to the second port member 138 through the port hole 142, whereby relative rotational displacement between the rod cover 104 and the cylindrical body 24b is re-stricted.
On the other hand, in the interior of the holder portion 122, a rod packing 68 and a

bush /U are disposed along the axial direction.
In addition, the rod cover 104 is inserted into the interior of the cylindrical body 24b, and in a state of being positioned axially by abutment of the end of the circumferential wall portion 128 against the other end of the cylinder tube 106, and by the latching ring 50 being engaged in the engagement groove 26 of the cylindrical body 24b, the latching ring 50 abuts against the base part 124 of the rod cover 104, and disen-gagement of the rod cover 104 from the open end side of the cylindrical body 24b is restricted.
Because the operations of the fluid pressure cylinder 100 according to the second embodiment are the same as the operations of the fluid pressure cylinder 10 according to the first embodiment, detailed descriptions of such operations are omitted.
As has been described above, with the fluid pressure cylinder 100 according to the second embodiment, by the head cover 102 and the rod cover 104, which are disposed on both ends of the cylinder tube 106, being formed from plate members, compared to the conventional fluid pressure cylinder in which the head cover and the rod cover are affixed by being screw-engaged with respect to both ends of the cylinder tube, there is no need to provide threaded portions, respectively, for the purpose of mutual screw-engagement between the cylinder tube 106 and the head cover 102 and the rod cover 104. Therefore, the longitudinal dimension of the fluid pressure cylinder 100 in the axial direction can be reduced in size.
Further, by the first and second port members 108, 138 through which the pressure fluid is supplied and discharged being disposed on the inner circumferential side of the cylinder tube 106, compared to the conventional fluid pressure cylinder in which the ports project diametrally outward with respect to the cylinder tube, the diametral dimension of the fluid pressure cylinder 100 can be made smaller in size.
Furthermore, compared to the conventional fluid pressure cylinder in which the rod cover is connected by being screw-engaged with respect to the cylinder tube, the operation to attach and detach the rod cover 104 with respect to the cylinder tube 106 can be performed easily, simply by installation and removal of the latching ring 50. Moreover, with the aforementioned fluid pressure cylinder 100, although a con-figuration is provided in which only the rod cover 104 is attachable and detachable with respect to the cylinder tube 106, by providing a latching ring 50 also on the side of the head cover 102, a configuration may be provided in which the head cover 102 also is attachable and detachable with respect to the cylinder tube 106.
Further still, since the head cover 102 and the rod cover 104 are formed from plate members having a predetermined thickness, compared to the fluid pressure cylinder 10 according to the first embodiment, a significant reduction in weight can also be achieved.