FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
ROTARY COMPRESSOR AND METHOD OF MANUFACTURING ROLLING PISTON
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION
AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
Technical Field
[0001]
The present disclosure relates to a rotary compressor including a rolling piston,
5 and to a method of manufacturing a rolling piston.
Background Art
[0002]
In this type of related-art compressor, for example, as disclosed in Fig. 6 of
Patent Literature 1, a compression mechanism portion to compress refrigerant
10 includes a rotational shaft to eccentrically rotate a rotor, a cylinder provided on the
outer circumference of the rotor and forming a cylinder vane chamber between the
rotor and the cylinder, and a front panel and a rear panel located on both sides in the
axial direction of the rotational shaft. The rotor slides relative to the front panel and
the rear panel through lubricating oil. On a portion of the front panel and the rear
15 panel corresponding to the cylinder vane chamber, anti-seizure grooves, a ringshaped groove, and sealing grooves are formed. The anti-seizure grooves are
formed on the radially inward side of the ring-shaped groove, while the sealing
grooves are formed on the radially outward side of the ring-shaped groove. The
ring-shaped groove is formed on the front panel and the rear panel, so that a sliding
20 surface on the outer circumferential side relative to the ring-shaped groove is
lubricated with emulsion fluid of gasified refrigerant and lubricating oil, and a sliding
surface on the inner circumferential side relative to the ring-shaped groove is
lubricated with viscous fluid of lubricating oil mixed with refrigerant almost completely
dissolved in the lubricating oil.
25 Citation List
Patent Literature
[0003]
Patent Literature 1: Japanese Unexamined Patent Application Publication No.
S56-135780
30 Summary of Invention
3
Technical Problem
[0004]
In the above-mentioned compressor, depending on the relative positions of the
rotor and the front panel, and the relative positions of the rotor and the rear panel
5 (that is, the rotation angle of the rotor relative to the front panel and the rear panel),
the ring-shaped groove and the sealing grooves can be exposed to the cylinder vane
chamber. The sealing grooves are formed in such a manner as to extend radially
inward to be directed toward the rotor along the rotation direction of the rotor. In
view of this, the lubricating oil present in the sealing grooves is drawn by rotation of
10 the rotor, moving radially inward toward the rotor. In the compressor having this
configuration, when a carbon dioxide refrigerant is used, instead of a
chlorofluorocarbon-based refrigerant, the pressure in the cylinder vane chamber
increases to a relatively high level, and consequently the refrigerant enters the
sealing grooves, the ring-shaped groove, and the anti-seizure grooves. This leads to
15 a problem that the thickness of an oil film between the rotor and the front panel and
the thickness of an oil film between the rotor and the rear panel are decreased, which
results in degradation in lubrication performance between the rotor and the front
panel, and lubrication performance between the rotor and the rear panel.
[0005]
20 The present disclosure has been made to solve the above problems, and it is
an object of the present disclosure to provide a rotary compressor that can reduce
entry of refrigerant from a cylinder chamber into a second groove portion regardless
of the rotation angle of a rolling piston, and a method of manufacturing a rolling
piston.
25 Solution to Problem
[0006]
A rotary compressor according to one embodiment of the present disclosure is
a rotary compressor having a rotary electric machine and a compression mechanism
portion accommodated in a hermetically-sealed container, the compression
30 mechanism portion being driven by the rotary electric machine and being configured
4
to compress refrigerant, wherein the compression mechanism portion includes a
rolling piston rotatably fitted onto an eccentric shaft portion of a rotational shaft
rotated by the rotary electric machine, a cylinder including a cylinder chamber
configured to accommodate the rolling piston therein and divided by a vane into a
5 compression chamber and a low-pressure chamber, and frames relative to which the
rolling piston slides, the frames being located on both sides in the axial direction of
the rolling piston and the cylinder, and being configured to close opening port portions
of the cylinder chamber on its opposite end faces, the rolling piston includes, on a
sliding surface having a ring shape and sliding relative to the frames, a first groove
10 portion extending radially outward from an inner circumferential end of the sliding
surface and directed toward a direction opposite to a rotation direction of the eccentric
shaft portion, a second groove portion connecting to a radially outward end of the first
groove portion, and extending radially outward to be directed toward a rotation
direction of the eccentric shaft portion, and a wall portion flush with the sliding surface
15 on a radially outward side of the second groove portion, and wherein the compression
mechanism portion includes a lubricating oil supply mechanism configured to supply
lubricating oil to the first groove portion.
A method of manufacturing a rolling piston according to another embodiment of
the present disclosure is a method of manufacturing a rolling piston in which a first
20 groove portion and a second groove portion are formed on a sliding surface of a
rolling piston that constitutes a compression mechanism portion of a rotary
compressor, the sliding surface having a ring shape, the first groove portion extending
radially outward from an inner circumferential end of the sliding surface and being
directed toward one of circumferential directions, the second groove portion
25 connecting to a radially outward end of the first groove portion, and extending radially
outward to be directed toward an other of the circumferential directions opposite to
the one of the circumferential directions, wherein the rolling piston is manufactured
by: moving an electrode close to a rolling piston material, the electrode including a
first protrusion and a second protrusion corresponding respectively to the first groove
30 portion and the second groove portion; generating electrical discharge spark between
5
the electrode and the rolling piston material; forming the first groove portion on the
sliding surface of the rolling piston material facing the first protrusion; and forming the
second groove portion on the sliding surface of the rolling piston material facing the
second protrusion.
5 Advantageous Effects of Invention
[0007]
The rotary compressor according to one embodiment of the present disclosure,
and the method of manufacturing a rolling piston according to another embodiment of
the present disclosure allow lubricating oil to be present in the first groove portion and
10 the second groove portion, and thus can form an oil film adequately between the
sliding surface of the rolling piston and the frames.
Brief Description of Drawings
[0008]
[Fig. 1] Fig. 1 is a sectional view of a compressor in Embodiment 1.
15 [Fig. 2] Fig. 2 is a cross-sectional view illustrating a compression mechanism
portion of Embodiment 1.
[Fig. 3] Fig. 3 is a sectional view illustrating an oil supply passage formed in a
rotational shaft of Embodiment 1.
[Fig. 4] Fig. 4 is an explanatory view illustrating a rolling piston and the
20 rotational shaft of Embodiment 1.
[Fig. 5] Fig. 5 is an explanatory view illustrating the rolling piston and the
rotational shaft of Embodiment 1.
[Fig. 6] Fig. 6 is an explanatory view illustrating the method of forming first
groove portions and second groove portions of Embodiment 1.
25 [Fig. 7] Fig. 7 is an explanatory view illustrating the method of forming the first
groove portions and the second groove portions of Embodiment 1.
[Fig. 8] Fig. 8 is an explanatory view illustrating a compressor as a comparative
example of Embodiment 1.
[Fig. 9] Fig. 9 is an explanatory view illustrating the compressor of Embodiment
30 1.
6
[Fig. 10] Fig. 10 is an explanatory view showing the pressure of refrigerating
machine oil in the first groove portions and the second groove portions of
Embodiment 1.
Description of Embodiments
5 [0009]
Embodiment 1
A compressor 1 is described below. Fig. 1 is a vertical cross-sectional view
illustrating the structure of the compressor 1. Fig. 2 is a cross-sectional view of a
compression mechanism portion 2 corresponding to the A-A section in Fig. 1.
10 As illustrated in Fig. 1, the compressor 1 is a hermetically-sealed single rotary
compressor. The compressor 1 includes the compression mechanism portion 2 to
compress refrigerant (a carbon dioxide refrigerant in Embodiment 1), a rotary electric
machine 3 to drive the compression mechanism portion 2, a hermetically-sealed
container 4 to accommodate therein the compression mechanism portion 2, the rotary
15 electric machine 3, and other devices, and a power supply terminal 5 to supply power
to the rotary electric machine 3. The rotary electric machine 3 is located above the
compression mechanism portion 2.
The hermetically-sealed container 4 includes a substantially-cylindrical body
portion 4a, a substantially-hemispherical upper lid portion 4b, and a lower lid portion
20 4c. The upper lid portion 4b and the lower lid portion 4c are welded respectively to
the top and the bottom of the body portion 4a.
[0010]
The rotary electric machine 3 includes a stator 3a fixed to the inner
circumferential surface of the body portion 4a of the hermetically-sealed container 4,
25 and a rotor 3b located on the inner side of the stator 3a with a predetermined gap
between the stator 3a and the rotor 3b. The stator 3a is fixed to the body portion 4a
by spot welding, shrink fit, or other fixing method. The power supply terminal 5 is
attached to the central portion of the upper lid portion 4b, and connects to a lead wire
6. Power is supplied to the rotary electric machine 3 from the power supply terminal
30 5 through the lead wire 6.
7
The compression mechanism portion 2 includes a rotational shaft 10, a cylinder
11, an upper bearing 12 serving as a frame, a lower bearing 13 serving as a frame, a
rolling piston 14, and a vane 15. The upper bearing 12 is fixed to the body portion
4a by spot welding. The upper portion of the rotational shaft 10 is inserted into and
5 fixed to the central portion of the rotary electric machine 3. More specifically, the
upper portion of the rotational shaft 10 is inserted into and fixed to the central portion
of the rotor 3b. The rotational shaft 10 includes, at its lower portion, an eccentric
shaft portion 10a that is eccentric with reference to the axial center of the rotational
shaft 10.
10 [0011]
The cylinder 11 forms a cylinder chamber 11a in its inner circumferential
portion. The cylinder chamber 11a is concentric with the axial center of the
rotational shaft 10. The upper bearing 12 and the lower bearing 13 support the
rotational shaft 10 rotatably. The upper bearing 12 closes one of the end faces on
15 opposite end portions of the cylinder 11 (facing toward the rotary electric machine 3).
The lower bearing 13 closes the other end face on opposite end portions of the
cylinder 11 (facing toward the lower lid portion 4c). The cylinder 11, the upper
bearing 12, and the lower bearing 13 are formed separately as individual
components, and then assembled together.
20 The rolling piston 14 is formed in a substantially cylindrical shape. In the axial
direction of the rotational shaft 10, opposite end faces of the rolling piston 14 formed
in a substantially cylindrical shape are closed by the upper bearing 12 and the lower
bearing 13. As illustrated in Fig. 2, the cylinder chamber 11a is formed and
hermetically sealed in the internal space of the cylinder 11. In the cylinder chamber
25 11a, the eccentric shaft portion 10a of the rotational shaft 10 illustrated in Fig. 2, and
the rolling piston 14 fitted onto the eccentric shaft portion 10a are accommodated.
An oil film is formed between the eccentric shaft portion 10a and the rolling piston 14
to ensure sliding and sealing performance.
[0012]
8
As illustrated in Fig. 2, the cylinder 11 has therein a vane sliding groove 11b
extending in the radial direction. The vane sliding groove 11b is formed extending in
the radial direction of the cylinder 11 from the cylinder chamber 11a, and penetrates
opposite sides of the cylinder 11 in its axial direction. A hole 11c is formed on the
5 radially outward side of the vane sliding groove 11b. The hole 11c also penetrates
opposite sides of the cylinder 11 in its radial direction. The vane sliding groove 11b
and the hole 11c connect to each other. In the hole 11c, a spring 16 is located to
serve as an urging unit. An urging force of the spring 16 causes the vane 15 to be
urged toward the radially inward side of the cylinder 11. The tip end of the vane 15
10 is pressed against the outer circumferential surface of the rolling piston 14. The
cylinder 11 has therein a suction passage 11d and a discharge port 11e on opposite
sides of the vane 15 in the circumferential direction of the cylinder 11. The suction
passage 11d connects to the cylinder chamber 11a. The discharge port 11e also
connects to the cylinder chamber 11a.
15 [0013]
The body portion 4a of the hermetically-sealed container 4 is provided with a
through hole. A refrigerant suction pipe 17 is connected to this through hole. The
refrigerant suction pipe 17 connects to the suction passage 11d. The upper lid
portion 4b of the hermetically-sealed container 4 is provided with a through hole. A
20 refrigerant discharge pipe 18 is connected to this through hole. The refrigerant
discharge pipe 18 connects to the discharge port 11e via the internal space of the
hermetically-sealed container 4.
A low-pressure chamber 19 is formed by the space that is closed by the upper
lid portion 4b, the lower lid portion 4c, the cylinder 11, the rolling piston 14, and the
25 vane 15, and that connects to the suction passage 11d. A compression chamber 20
is formed by the space that is closed by the upper lid portion 4b, the lower lid portion
4c, the cylinder 11, the rolling piston 14, and the vane 15, and that connects to the
discharge port 11e. That is, the cylinder 11 includes the cylinder chamber 11a
divided by the vane 15 into the compression chamber 20 and the low-pressure
30 chamber 19.
9
[0014]
As illustrated in Fig. 3, a columnar hollow hole is provided in the rotational shaft
10 at its axial center. The hollow hole serves as an oil supply passage 30 to feed
refrigerating machine oil 29 accumulating at the bottom of the hermetically-sealed
5 container 4. The refrigerating machine oil 29 is equivalent to lubricating oil. The oil
supply passage 30 includes an opening port portion 31 on an end face of the
rotational shaft 10 facing toward the lower lid portion 4c. The end portion of the
rotational shaft 10 facing toward the lower lid portion 4c is immersed in the
refrigerating machine oil 29 (see Fig. 1) accumulating at the bottom of the
10 hermetically-sealed container 4. The oil supply passage 30 allows the refrigerating
machine oil 29 accumulating as described above (see Fig. 1) to be sucked from the
opening port portion 31 of the rotational shaft 10 due to a centrifugal pump effect
generated when the rotational shaft 10 rotates, and due to a differential pressure
effect generated between the high-pressure space and the low-pressure space. The
15 high-pressure space is formed by filling the hermetically-sealed container 4 with highpressure refrigerant gas. The low-pressure space is formed by sucking low-pressure
refrigerant gas into the compression mechanism portion 2.
[0015]
The rotational shaft 10 has an oil supply hole 32a that is open from the oil
20 supply passage 30 toward the outer circumferential surface of the rotational shaft 10
at a position corresponding to the vicinity of the upper end face of the eccentric shaft
portion 10a. The rotational shaft 10 has a groove portion 32b that is recessed from
the outer circumferential surface of the rotational shaft 10 over its entire periphery in
the circumferential direction at a position corresponding to the oil supply hole 32a.
25 The oil supply hole 32a and the groove portion 32b connect to each other. The oil
supply hole 32a and the groove portion 32b allow the refrigerating machine oil 29
having been sucked into the oil supply passage 30 to be supplied between the
eccentric shaft portion 10a and the upper bearing 12, and between the rolling piston
14 and the upper bearing 12. With this supply, an oil film is formed between the
30 eccentric shaft portion 10a and the upper bearing 12, and between the rolling piston
10
14 and the upper bearing 12 to ensure sliding and sealing performance. The
rotational shaft 10 including the oil supply passage 30, the oil supply hole 32a, and
the groove portion 32b constitutes a lubricating oil supply mechanism 33.
Note that the groove portion 32b may be omitted. In a case where the groove
5 portion 32b is omitted, the oil supply hole 32a is open to the outer circumferential
surface of the rotational shaft 10. As described above, in a case where the groove
portion 32b is omitted, the rotational shaft 10 including the oil supply passage 30 and
the oil supply hole 32a constitutes the lubricating oil supply mechanism 33.
[0016]
10 Similarly to the above, the rotational shaft 10 has an oil supply hole 34a that is
open from the oil supply passage 30 toward the outer circumferential surface of the
rotational shaft 10 at a position corresponding to the vicinity of the lower end face of
the eccentric shaft portion 10a. The rotational shaft 10 has a groove portion 34b that
is recessed from the outer circumferential surface of the rotational shaft 10 over its
15 entire periphery in the circumferential direction at a position corresponding to the oil
supply hole 34a. The oil supply hole 34a and the groove portion 34b connect to
each other. The oil supply hole 34a and the groove portion 34b allow the
refrigerating machine oil 29 having been sucked into the oil supply passage 30 to be
supplied between the eccentric shaft portion 10a and the lower bearing 13, and
20 between the rolling piston 14 and the lower bearing 13. With this supply, an oil film
(the refrigerating machine oil 29) is formed between the eccentric shaft portion 10a
and the lower bearing 13, and between the rolling piston 14 and the lower bearing 13
to ensure sliding and sealing performance. The rotational shaft 10 including the oil
supply passage 30, the oil supply hole 34a, and the groove portion 34b constitutes a
25 lubricating oil supply mechanism 35.
Note that the groove portion 34b may be omitted. In a case where the groove
portion 34b is omitted, the oil supply hole 34a is open to the outer circumferential
surface of the rotational shaft 10. As described above, in a case where the groove
portion 34b is omitted, the rotational shaft 10 including the oil supply passage 30 and
30 the oil supply hole 34a constitutes the lubricating oil supply mechanism 35.
11
[0017]
Next, the shape of the rolling piston 14 is described.
Fig. 4 corresponds to the B-B cross-section in Fig. 1, and illustrates the
relationship between the rotational shaft 10 and the rolling piston 14 when viewed
5 from the top side of the rolling piston 14.
As illustrated in Fig. 4, the rolling piston 14 includes, on its top side (the face
facing toward the upper lid portion 4b), a sliding surface 41 formed in a ring shape.
The sliding surface 41 slides relative to the upper bearing 12.
The rolling piston 14 includes a first groove portion 42 extending radially
10 outward from the inner circumferential end of the sliding surface 41 and directed
toward the direction opposite to a rotation direction S1 of the eccentric shaft portion
10a, a second groove portion 43 connecting to the radially outward end of the first
groove portion 42, and extending radially outward to be directed toward the rotation
direction S1 of the eccentric shaft portion 10a, and a wall portion 44 flush with the
15 sliding surface 41 on the radially outward side of the second groove portion 43. That
is, the rolling piston 14 includes the first groove portion 42 extending radially outward
from the inner circumferential end of the sliding surface 41 and directed toward the
direction opposite to a rotation direction S2 of the rolling piston 14, the second groove
portion 43 connecting to the radially outward end of the first groove portion 42, and
20 extending radially outward to be directed toward the rotation direction S2 of the rolling
piston 14, and the wall portion 44 flush with the sliding surface 41 on the radially
outward side of the second groove portion 43. The rotation direction S2 is
equivalent to one of the circumferential directions, while the direction opposite to the
rotation direction S2 is equivalent to the other of the circumferential directions. On
25 the sliding surface 41, the first groove portion 42 is formed to have a radial width h1
less than a radial width h2 of the second groove portion 43.
[0018]
On the sliding surface 41, plural combinations of the first groove portion 42, the
second groove portion 43, and the wall portion 44 are provided at predetermined
30 intervals along the circumferential direction of the rolling piston 14. More specifically,
12
on the sliding surface 41, 12 combinations of the first groove portion 42, the second
groove portion 43, and the wall portion 44 are provided at equal intervals along the
circumferential direction of the rolling piston 14. The number of combinations of the
first groove portion 42, the second groove portion 43, and the wall portion 44 may not
5 be necessarily 12. Other than one combination or 12 combinations, any number of
combinations of the first groove portion 42, the second groove portion 43, and the
wall portion 44 may be provided. Furthermore, the first groove portions 42, the
second groove portions 43, and the wall portions 44 may be provided along the
circumferential direction of the rolling piston 14 at any different intervals, instead of at
10 equal intervals.
[0019]
The rolling piston 14 includes, on the sliding surface 41, the first groove
portions 42, the second groove portions 43, and the wall portions 44. In other words,
V-shaped grooves, each of which is made up of the first groove portion 42 and the
15 second groove portion 43, are formed on the sliding surface 41, in which each of the
V-shaped grooves has one end portion closer to the eccentric shaft portion 10a and
open to the inner circumferential surface of the rolling piston 14, and has another end
portion farther from the eccentric shaft portion 10a and formed leading to the position
inward relative to the outer circumferential surface of the rolling piston 14. On the
20 sliding surface 41, 12 V-shaped grooves are formed at equal intervals along the
circumferential direction. These V-shaped grooves formed on the sliding surface 41
are also referred to as herringbone groove in general.
[0020]
Fig. 5 corresponds to the C-C cross-section in Fig. 1, and illustrates the
25 relationship between the rotational shaft 10 and the rolling piston 14 when viewed
from the bottom side of the rolling piston 14.
The rolling piston 14 includes, on its bottom side (the face facing toward the
lower lid portion 4c), a sliding surface 51 formed in a ring shape. The sliding surface
51 slides relative to the lower bearing 13. The rolling piston 14 includes a first
30 groove portion 52 extending radially outward from the inner circumferential end of the
13
sliding surface 51 and directed toward the direction opposite to the rotation direction
S1 of the eccentric shaft portion 10a, a second groove portion 53 connecting to the
radially outward end of the first groove portion 52, and extending radially outward to
be directed toward the rotation direction S1 of the eccentric shaft portion 10a, and a
5 wall portion 54 flush with the sliding surface 51 on the radially outward side of the
second groove portion 53. That is, the rolling piston 14 includes the first groove
portion 52 extending radially outward from the inner circumferential end of the sliding
surface 51 and directed toward the direction opposite to the rotation direction S2 of
the rolling piston 14, the second groove portion 53 connecting to the radially outward
10 end of the first groove portion 52, and extending radially outward to be directed
toward the rotation direction S2 of the rolling piston 14, and the wall portion 54 flush
with the sliding surface 51 on the radially outward side of the second groove portion
53. On the sliding surface 51, the first groove portion 52 is formed to have a radial
width h3 less than a radial width h4 of the second groove portion 53.
15 [0021]
On the sliding surface 51, plural combinations of the first groove portion 52, the
second groove portion 53, and the wall portion 54 are provided at predetermined
intervals along the circumferential direction of the rolling piston 14. More specifically,
on the sliding surface 51, 12 combinations of the first groove portion 52, the second
20 groove portion 53, and the wall portion 54 are provided at equal intervals along the
circumferential direction of the rolling piston 14. The number of combinations of the
first groove portion 52, the second groove portion 53, and the wall portion 54 may not
be necessarily 12. Other than one combination or 12 combinations, any number of
combinations of the first groove portion 52, the second groove portion 53, and the
25 wall portion 54 may be provided. Furthermore, the first groove portions 52, the
second groove portions 53, and the wall portions 54 may be provided along the
circumferential direction of the rolling piston 14 at any different intervals, instead of at
equal intervals.
[0022]
14
The rolling piston 14 includes, on the sliding surface 51, the first groove
portions 52, the second groove portions 53, and the wall portions 54. In other words,
V-shaped grooves, each of which is made up of the first groove portion 52 and the
second groove portion 53, are formed on the sliding surface 51, in which each of the
5 V-shaped grooves has one end portion closer to the eccentric shaft portion 10a and
open to the inner circumferential surface of the rolling piston 14, and has another end
portion farther from the eccentric shaft portion 10a and formed leading to the position
inward relative to the outer circumferential surface of the rolling piston 14. On the
sliding surface 51, 12 V-shaped grooves are formed at equal intervals along the
10 circumferential direction. These V-shaped grooves formed on the sliding surface 51
are also referred to as herringbone groove in general.
[0023]
Next, descriptions are made on the method of forming the first groove portions
42 and the second groove portions 43 on the rolling piston 14 using electrical
15 discharge machining.
Fig. 6 is an explanatory view corresponding to the rolling piston 14 (a rolling
piston material 105) in D-D cross-section in Fig. 4, and illustrating the relationship
between an electrode 104 used for electrical discharge machining and the rolling
piston material 105. Fig. 7 is an explanatory view corresponding to the rolling piston
20 14 (the rolling piston material 105) in D-D cross-section in Fig. 4, and illustrating the
rolling piston material 105 with the first groove portions 42 and the second groove
portions 43 formed thereon by electrical discharge machining.
As illustrated in Fig. 6, the electrode 104 includes first protrusions 102 and
second protrusions 103 corresponding respectively to the first groove portions 42 and
25 the second groove portions 43, and the electrode 104 is moved close to the sliding
surface 41 of the rolling piston material 105 (the rolling piston 14 not yet having the
first groove portions 42 or the second groove portions 43). When a voltage is
applied from the electrode 104 to the rolling piston material 105 to generate electrical
discharge spark, then on the sliding surface 41 of the rolling piston material 105, the
30 first groove portions 42 are formed at positions facing the first protrusions 102, while
15
the second groove portions 43 are formed at positions facing the second protrusions
103. Consequently, production of the rolling piston 14 including the first groove
portions 42 and the second groove portions 43 is completed.
[0024]
5 In the manner as described above, electrical discharge machining is used to
form the first groove portions 42 and the second groove portions 43 on the rolling
piston material 105. Thus, even when the first groove portions 42 and the second
groove portions 43 include a sharp-edge shaped portion, the first groove portions 42
and the second groove portions 43 can still be formed into a precise shape.
10 In addition, the first groove portions 52 and the second groove portions 53 are
also formed on the rolling piston 14 using electrical discharge machining in the same
manner as described above. Thus, descriptions of the formation method are
omitted.
[0025]
15 Note that other than electrical discharge machining, coining dies may be used
to form the first groove portions 42 and the second groove portions 43 on the rolling
piston material 105. That is, coining dies provided with protruding portions
corresponding to the first groove portions 42 and the second groove portions 43 are
used to form the first groove portions 42 and the second groove portions 43 on the
20 sliding surface 41 by pressing the protruding portions described above against the
sliding surface 41 of the rolling piston material 105 to form recesses on the sliding
surface 41. The first groove portions 52 and the second groove portions 53 are also
formed on the rolling piston 14 using the coining dies in the same manner as
described above. Thus, descriptions of the formation method are omitted.
25 [0026]
Next, operation of the compressor 1 having the configuration as described
above, and the function of the compressor 1 are described. As illustrated in Figs. 1
and 2, when the rotary electric machine 3 is energized from the power supply terminal
5, a magnetic field is generated in the stator 3a, so that the rotor 3b rotates with the
30 rotational shaft 10. As the rotational shaft 10 rotates, the eccentric shaft portion 10a
16
rotates. When the eccentric shaft portion 10a rotates, the rolling piston 14 rotates
and slides inside the cylinder 11. That is, the rolling piston 14 rotates eccentrically
along the inner circumferential surface of the cylinder 11. Due to this rotation, gas
refrigerant is sucked into the low-pressure chamber 19 in the cylinder 11 through the
5 refrigerant suction pipe 17 and the suction passage 11d, and the gas refrigerant is
compressed in the compression chamber 20 in the cylinder 11. The high-pressure
gas refrigerant compressed in the compression chamber is discharged to the space in
the hermetically-sealed container 4 and then discharged from the refrigerant
discharge pipe 18 to the outside of the hermetically-sealed container 4.
10 [0027]
Motion of the eccentric shaft portion 10a and the rolling piston 14 is described
with reference to Fig. 2. The rotational shaft 10 (not illustrated in Fig. 2) rotates in
the counterclockwise direction, causing the eccentric shaft portion 10a to rotate
counterclockwise in the cylinder 11 (in the rotation direction S1). Then, the rolling
15 piston 14 fitted onto the outer circumference of the eccentric shaft portion 10a rotates
counterclockwise in the cylinder 11 (in the rotation direction S2), while being in
contact with the inner circumferential surface of the cylinder 11 through an oil film
made of the refrigerating machine oil 29. Note that the rolling piston 14 may
sometimes stop rotating depending on the operating state of the compressor 1. The
20 rotational shaft 10 rotates at a speed faster than that of the rolling piston 14.
[0028]
As illustrated in Fig. 3, the refrigerating machine oil 29 accumulating at the
bottom of the hermetically-sealed container 4 is sucked from the opening port portion
31 of the oil supply passage 30 of the rotational shaft 10 due to a centrifugal pump
25 effect generated when the rotational shaft 10 rotates, and due to a differential
pressure effect generated between the high-pressure space and the low-pressure
space. The high-pressure space is formed by filling the hermetically-sealed
container 4 with high-pressure refrigerant gas. The low-pressure space is formed by
suctioning low-pressure refrigerant gas into the compression mechanism portion 2.
30 The refrigerating machine oil 29 having been sucked from the opening port portion 31
17
is supplied between the eccentric shaft portion 10a and the upper bearing 12, and
between the rolling piston 14 and the upper bearing 12 through the oil supply hole
32a and the groove portion 32b. In addition, the refrigerating machine oil 29 having
been sucked from the opening port portion 31 is supplied between the eccentric shaft
5 portion 10a and the lower bearing 13, and between the rolling piston 14 and the lower
bearing 13 through the oil supply hole 34a and the groove portion 34b.
[0029]
Next, the refrigerating machine oil 29 present between the rolling piston 14 and
the upper bearing 12 is described with reference to Figs. 3 and 4.
10 As described above, the eccentric shaft portion 10a rotates counterclockwise
(in the rotation direction S1), and the rolling piston 14 rotates counterclockwise (in the
rotation direction S1) as illustrated in Fig. 4. In this state, the refrigerating machine
oil 29 is supplied between the upper bearing 12 and the sliding surface 41 of the
rolling piston 14 through the opening port portion 31, the oil supply passage 30, the oil
15 supply hole 32a, and the groove portion 34b of the rotational shaft 10 illustrated in
Fig. 3, and is further supplied to the first groove portions 42 and the second groove
portions 43 illustrated in Fig. 4.
The first groove portion 42 extends radially outward from the inner
circumferential end of the sliding surface 41 and is directed toward the direction
20 opposite to the rotation direction S2 of the rolling piston 14. Rotation of the rolling
piston 14 causes the refrigerating machine oil 29 present in the first groove portions
42 to flow radially outward toward the direction opposite to the rotation direction S2 of
the rolling piston 14 due to an inertial force. In contrast, the second groove portion
43 extends radially outward to be directed toward the rotation direction S2 of the
25 rolling piston 14. Rotation of the rolling piston 14 causes the refrigerating machine
oil 29 present in the second groove portions 43 to flow radially inward toward the
direction opposite to the rotation direction S2 of the rolling piston 14 due to an inertial
force.
[0030]
18
Meanwhile, the wall portions 44 flush with the sliding surface 41 are formed on
the radially outward side of the second groove portions 43. This reduces flowing out
of the refrigerating machine oil 29 over the wall portions 44 and its radially outward
leaking from the rolling piston 14 through the clearance between the sliding surface
5 41 and the upper bearing 12. In the manner as described above, a reduction in the
volume of the compression chamber 20, caused by the refrigerating machine oil 29
flowing over the wall portions 44 and leaking radially outward from the rolling piston
14 through the clearance between the sliding surface 41 and the upper bearing 12,
can be suppressed, and accordingly a decrease in work efficiency of the compressor
10 1 can be suppressed.
[0031]
In a related-art compressor (a compressor including a rolling piston not having
the first groove portions 42 or the second groove portions 43), for the purpose of
preventing the occurrence of a phenomenon in which the upper bearing and the
15 rolling piston thermally expand due to continuous operation of the compressor, which
consequently closes the clearance between the upper bearing and the sliding surface
of the rolling piston, so that the refrigerating machine oil 29 cannot be sufficiently
supplied between the upper bearing and the rolling piston, this clearance width is
designed within the narrow allowable dimensional range.
20 However, in the compressor 1 of the present embodiment, even when the
upper bearing 12 and the rolling piston 14 thermally expand due to continuous
operation of the compressor 1, which consequently narrows the clearance between
the upper bearing 12 and the rolling piston 14, a sufficient amount of the refrigerating
machine oil 29 is still easily supplied to the upper bearing 12 and the sliding surface
25 41 of the rolling piston 14 through the first groove portions 42 and the second groove
portions 43, compared to the conventional compressor described above, so that an oil
film can be formed adequately between the upper bearing 12 and the sliding surface
41 of the rolling piston 14. As a result, the clearance width is designed within a
wider allowable dimensional range, which increases the design flexibility, and
30 facilitates management of the clearance tolerances in mass production.
19
[0032]
In the compressor 1 of the present embodiment, even when the upper bearing
12 and the rolling piston 14 thermally expand, the refrigerating machine oil 29 can still
be sufficiently supplied between the upper bearing 12 and the sliding surface 41 of
5 the rolling piston 14 as described above, so that an oil film can be formed adequately
between the upper bearing 12 and the sliding surface 41 of the rolling piston 14.
Thus, the compressor 1 is operated at a variable speed by using inverter control,
instead of being operated at a constant speed, so that even when the amount of
thermal expansion of the upper bearing 12 and the rolling piston 14 increases, the
10 refrigerating machine oil 29 can still be sufficiently supplied between the upper
bearing 12 and the sliding surface 41 of the rolling piston 14. That is, the
compressor 1 can still be adequately operated even at a higher rotation speed than
that of the conventional compressor. Further, the refrigerating machine oil 29 is
sufficiently supplied between the upper bearing 12 and the sliding surface 41 of the
15 rolling piston 14, so that sliding durability of the upper bearing 12 and the sliding
surface 41 of the rolling piston 14 can be improved.
Note that the compressor 1 is not configured to reduce the amount of the
refrigerating machine oil 29, flowing over the wall portions 44 and leaking radially
outward from the rolling piston 14 through the clearance between the sliding surface
20 41 and the upper bearing 12, to zero, but is configured to supply the refrigerating
machine oil 29 to the outer circumferential end of the sliding surface 41, so that a
slight amount of the refrigerating machine oil 29 still leaks outward from the sliding
surface 41 to form an oil film intended to maintain the lubricity and the sealing
performance between the outer circumferential end of the sliding surface 41 and the
25 upper bearing 12.
[0033]
As illustrated in Fig. 8, there is a case where a compressor does not include
the wall portions 44, and instead, the second groove portions 43 are formed leading
to the outer circumferential end of the sliding surface 41 (hereinafter, referred to as
30 compressor of Comparative Example 1). In that case, high-pressure refrigerant
20
present in the compression chamber 20 may leak through the second groove portions
43 that are open to the compression chamber 20, the first groove portions 42, and the
outer circumference of the rotational shaft 10 (the groove portion 32b), to the first
groove portions 42 and the second groove portions 43 that are open to the low5 pressure chamber 19. This may result in a decrease in the work efficiency of the
compressor of Comparative Example 1.
However, as illustrated in Fig. 9, the compressor 1 of the present embodiment
includes the wall portions 44 in the rolling piston 14, so that the radially outward end
portion of the second groove portions 43 is not open to the outer circumferential end
10 of the sliding surface 41. This stops high-pressure refrigerant present in the
compression chamber 20 from flowing into the low-pressure chamber 19 through the
radially outward end portion of the second groove portions 43. This results in
improvement in the work efficiency compared to the compressor of Comparative
Example 1. Particularly, the compressor 1 of the present embodiment uses a carbon
15 dioxide refrigerant whose pressure is increased to a higher level than that of a
chlorofluorocarbon-based refrigerant when the refrigerant is used in the hermeticallysealed container 4. Thus, the compressor 1 can further improve the work efficiency
compared to the compressor of Comparative Example 1.
[0034]
20 As illustrated in Fig. 4, the first groove portion 42 extends radially outward from
the inner circumferential end of the sliding surface 41 to be directed toward the
direction opposite to the rotation direction S2 of the rolling piston 14. Rotation of the
rolling piston 14 causes the refrigerating machine oil 29 present in the first groove
portions 42 to flow radially outward toward the direction opposite to the rotation
25 direction S2 of the rolling piston 14 due to an inertial force. In contrast, the second
groove portion 43 extends radially outward to be directed toward the rotation direction
S2 of the rolling piston 14. Rotation of the rolling piston 14 causes the refrigerating
machine oil 29 present in the second groove portions 43 to flow radially inward toward
the direction opposite to the rotation direction S2 of the rolling piston 14 due to an
30 inertial force. In the manner as described above, the refrigerating machine oil 29 in
21
the first groove portions 42 moves radially outward, while the refrigerating machine oil
29 in the second groove portions 43 moves radially inward, so that as illustrated in
Fig. 10, the pressure of the refrigerating machine oil 29 present in the first groove
portions 42 and the second groove portions 43 is maximized at the position of the
5 connection point between the first groove portion 42 and the second groove portion
43.
With this configuration, the refrigerating machine oil 29 is supplied between the
sliding surface 41 and the upper bearing 12 through the first groove portions 42 and
the second groove portions 43 with a maximum amount of the refrigerating machine
10 oil 29 supplied from the position of the connection point between the first groove
portion 42 and the second groove portion 43. This can improve the sliding
performance between the upper bearing 12 and the sliding surface 41 around the
connection point described above.
[0035]
15 The position, at which the oil pressure of the refrigerating machine oil 29
present in the first groove portions 42 and the second groove portions 43 is
maximized, is set at the connection point between the first groove portion 42 and the
second groove portion 43, not at the position of the radially outward end of the
second groove portions 43. This reduces flowing out of the refrigerating machine oil
20 29 over the wall portions 44 and its radially outward leaking from the rolling piston 14.
In addition, the pressure of the refrigerating machine oil 29 present in the first groove
portions 42 and the second groove portions 43 is maximized at the position of the
connection point between the first groove portion 42 and the second groove portion
43. Thus, even when the clearance between the upper bearing 12 and the rolling
25 piston 14 is enlarged, the refrigerating machine oil 29 present in the second groove
portions 43 still moves radially inward. This reduces flowing out of the amount of the
refrigerating machine oil 29 over the wall portions 44 and its radially outward leaking
from the rolling piston 14 through the clearance between the sliding surface 41 and
the upper bearing 12.
30 [0036]
22
Particularly, in the present embodiment, on the sliding surface 41, the first
groove portion 42 is formed to have the radial width h1 less than the radial width h2 of
the second groove portion 43. Thus, the position, at which the oil pressure of the
refrigerating machine oil 29 present in the first groove portions 42 and the second
5 groove portions 43 is maximized, can be formed radially inward relative to the center
of the radial width of the sliding surface 41. This can further reduces flowing out of
the refrigerating machine oil 29 over the wall portions 44 and its radially outward
leaking from the rolling piston 14.
The second groove portions 43 are not exposed to the compression chamber
10 20 regardless of the relative positions of the rolling piston 14 and the upper bearing
12 (that is, the rotation angle of the rolling piston 14 relative to the upper bearing 12).
Therefore, assuming that the second groove portions 43 are formed to be exposed to
the compression chamber 20, it is conceivable that refrigerant in the compression
chamber 20 may enter the second groove portions 43, and consequently an oil film
15 may not be formed adequately between the rolling piston 14 and the upper bearing
12. However, the compressor 1 of the present embodiment prevents the occurrence
of such a phenomenon.
[0037]
Next, the refrigerating machine oil 29 present between the rolling piston 14 and
20 the lower bearing 13 is described with reference to Fig. 5.
Fig. 5 corresponds to the C-C cross-section in Fig. 1, and illustrates the rolling
piston 14 and the rotational shaft 10 when viewed from the bottom side. Thus, the
eccentric shaft portion 10a rotates counterclockwise in Fig. 4, however, the eccentric
shaft portion 10a rotates clockwise when viewed in Fig. 5. Furthermore, the rolling
25 piston 14 rotates counterclockwise in Fig. 4, however, the rolling piston 14 rotates
clockwise when viewed in Fig. 5.
Note that the first groove portions 52 are formed to extend radially outward
from the inner circumferential end of the sliding surface 51 to be directed toward the
direction opposite to the rotation direction S1 of the eccentric shaft portion 10a, and
30 the second groove portions 53 are formed to extend radially outward to be directed
23
toward the rotation direction S1 of the eccentric shaft portion 10a. That is, the first
groove portions 52 are formed to extend radially outward from the inner
circumferential end of the sliding surface 51 to be directed toward the direction
opposite to the rotation direction S2 of the rolling piston 14. The second groove
5 portions 53 are formed to extend radially outward to be directed toward the rotation
direction S2 of the rolling piston 14.
Therefore, the first groove portions 52, the second groove portions 53, and the
wall portions 54 provided on the sliding surface 51 achieve the same functions as
those of the first groove portions 42, the second groove portions 43, and the wall
10 portions 44 provided on the sliding surface 41 described above. Thus, descriptions
of the same functions are omitted.
[0038]
In Embodiment 1 described above, a carbon dioxide refrigerant is used.
However, the compressor may be configured to use other kinds of refrigerant such as
15 a chlorofluorocarbon-based refrigerant. Even due to this configuration, the same
effects as those in Embodiment 1 can still be obtained.
[0039]
In Embodiment 1 described above, the first groove portions, the second groove
portions, and the wall portions are formed on both the sliding surface 41 and the
20 sliding surface 51 of the rolling piston 14. The first groove portions, the second
groove portions, and the wall portions are not limited to being formed on both the
sliding surface 41 and the sliding surface 51 of the rolling piston 14, but may be
formed on either the sliding surface 41 or the sliding surface 51. Even due to this
configuration, a sliding surface on which the first groove portions, the second groove
25 portions, and the wall portions are formed can still obtain the same effects as those in
Embodiment 1.
[0040]
In Embodiment 1 described above, on the sliding surface 41, the first groove
portions 42 are formed to have the radial width h1 less than the radial width h2 of the
30 second groove portions 43. The radial width h1 of the first groove portions 42 is not
24
limited to being less than the radial width h2 of the second groove portions 43, but
may be equal to or greater than the radial width h2. Even due to this configuration,
an oil film can still be formed adequately between the upper bearing 12 and the
sliding surface 41 of the rolling piston 14.
5 [0041]
In Embodiment 1 described above, on the sliding surface 51, the first groove
portions 52 are formed to have the radial width h3 less than the radial width h4 of the
second groove portions 53. The radial width h3 of the first groove portions 52 is not
limited to being less than the radial width h4 of the second groove portions 53, but
10 may be equal to or greater than the radial width h4. Even due to this configuration,
an oil film can still be formed adequately between the lower bearing 13 and the sliding
surface 51 of the rolling piston 14.
[0042]
In Embodiment 1 described above, in the single rotary type compressor, the
15 first groove portions 42 and 52, the second groove portions 43 and 53, and the wall
portions 44 and 54 are provided respectively on the sliding surfaces 41 and 51 of the
rolling piston 14. The compressor is not limited to this single rotary type compressor.
In a twin rotary type compressor, the first groove portions, the second groove
portions, and the wall portions may be provided on the sliding surfaces of the rolling
20 pistons.
Reference Signs List
[0043]
1: compressor, 2: compression mechanism portion, 3: rotary electric machine,
3a: stator, 3b: rotor, 4: hermetically-sealed container, 4a: body portion, 4b: upper lid
25 portion, 4c: lower lid portion, 5: power-supply terminal, 6: lead wire, 10: rotational
shaft, 10a: eccentric shaft portion, 11: cylinder, 11a: cylinder chamber, 11b: vane
sliding groove, 11c: hole, 11d: suction passage, 11e: discharge port, 12: upper
bearing, 13: lower bearing, 14: rolling piston, 15: vane, 16: spring, 17: refrigerant
suction pipe, 18: refrigerant discharge pipe, 19: low-pressure chamber, 20:
30 compression chamber, 29: refrigerating machine oil, 30: oil supply passage, 31:
25
opening port portion, 32a: oil supply hole, 32b: groove portion, 33: lubricating oil
supply mechanism, 34a: oil supply hole, 34b: groove portion, 35: lubricating oil supply
mechanism, 41: sliding surface, 42: first groove portion, 43: second groove portion,
44: wall portion, 51: sliding surface, 52: first groove portion, 53: second groove
5 portion, 54: wall portion, 102: first protrusion, 103: second protrusion, 104: electrode,
105: rolling piston material, h1, h3: radial width of first groove portion, h2, h4: radial
width of second groove portion, S1: rotation direction of eccentric shaft portion, S2:
rotation direction of rolling piston
26
WE CLAIM:
[Claim 1]
A rotary compressor having a rotary electric machine and a compression
mechanism portion accommodated in a hermetically-sealed container, the
5 compression mechanism portion being driven by the rotary electric machine and
being configured to compress refrigerant, wherein
the compression mechanism portion includes
a rolling piston rotatably fitted onto an eccentric shaft portion of a rotational
shaft rotated by the rotary electric machine,
10 a cylinder including a cylinder chamber configured to accommodate the rolling
piston therein and divided by a vane into a compression chamber and a low-pressure
chamber, and
frames relative to which the rolling piston slides, the frames being located on
both sides in the axial direction of the rolling piston and the cylinder, and being
15 configured to close opening port portions of the cylinder chamber on its opposite end
faces,
the rolling piston includes, on a sliding surface having a ring shape and sliding
relative to the frames,
a first groove portion extending radially outward from an inner circumferential
20 end of the sliding surface and directed toward a direction opposite to a rotation
direction of the eccentric shaft portion,
a second groove portion connecting to a radially outward end of the first groove
portion, and extending radially outward to be directed toward a rotation direction of
the eccentric shaft portion, and
25 a wall portion flush with the sliding surface on a radially outward side of the
second groove portion, and wherein
the compression mechanism portion includes a lubricating oil supply
mechanism configured to supply lubricating oil to the first groove portion.
30
27
[Claim 2]
The rotary compressor of claim 1, wherein the first groove portion is formed to
have a radial width on the sliding surface less than a radial width of the second
groove portion.
5 [Claim 3]
The rotary compressor of claim 1 or 2, wherein on the sliding surface, plural
combinations of the first groove portion, the second groove portion, and the wall
portion are provided at predetermined intervals along a circumferential direction.
[Claim 4]
10 The rotary compressor of any one of claims 1 to 3, wherein
the rolling piston includes the sliding surfaces, number of the sliding surfaces
being two, and
the rolling piston includes, on each of the two sliding surfaces, the first groove
portion, the second groove portion, and the wall portion.
15 [Claim 5]
The rotary compressor of any one of claims 1 to 4, wherein the refrigerant is a
carbon dioxide refrigerant.
[Claim 6]
A method of manufacturing a rolling piston in which a first groove portion and a
20 second groove portion are formed on a sliding surface of a rolling piston that
constitutes a compression mechanism portion of a rotary compressor, the sliding
surface having a ring shape, the first groove portion extending radially outward from
an inner circumferential end of the sliding surface and being directed toward one of
circumferential directions, the second groove portion connecting to a radially outward
25 end of the first groove portion, and extending radially outward to be directed toward
an other of the circumferential directions opposite to the one of the circumferential
directions, wherein
the rolling piston is manufactured by:
28
moving an electrode close to a rolling piston material, the electrode including a
first protrusion and a second protrusion corresponding respectively to the first groove
portion and the second groove portion;
generating electrical discharge spark between the electrode and the rolling
5 piston material;
forming the first groove portion on the sliding surface of the rolling piston
material facing the first protrusion; and
forming the second groove portion on the sliding surface of the rolling piston
material facing the second protrusion.