DESCRIPTION
Title of Invention:
COMPRESSOR AND REFRIGERATING CYCLE APPARATUS Technical Field
[0001] The present invention relates to a compressor and a refrigerating cycle
apparatus.
Background Art
[0002] A rotary compressor described in Patent Literature 1 includes a crank shaft
made of steel for mechanical structure. The surface of a portion of this crank shaft that
slides with each bearing is provided with a manganese phosphate film and a
molybdenum disulfide film.
Citation List
Patent Literature
[0003] Patent Literature 1: JP 2009-275645 A
Summary of Invention
Technical Problem
[0004] A highly efficient compressor is demanded for energy saving and resource
saving.
[0005] If a crank shaft diameter is reduced, a sliding loss is reduced, so that efficiency
of a compressor can be increased. However, in a generally widespread compressor, a
crank shaft made of a cast material such as FCD (Ferrum Casting Ductile) 550 or FCD
700 and having only a manganese phosphate film coated thereon is used. The cast
material such as the FCD 550 or the FCD 700 has a Young's modulus of approximately
164 gigapascals. That is, the cast material does not have a high rigidity. Accordingly,

if the diameter of the crank shaft made of the cast material is reduced, a deflection
amount of the crank shaft increases due to a gas load in a compression chamber. If the
deflection amount of the crank shaft increases, the crank shaft becomes easy to seize in
a bearing, so that reliability of the compressor is impaired.
[0006] If the material of the crank shaft is changed to the one having a high rigidity,
the increase in the deflection amount of the crank shaft can be reduced. A forged
material such as S45C has a Young's modulus of approximately 205 gigapascals or
higher. That is, the forged material has the high rigidity. However, seizure resistance
of the crank shaft made of the forged material and having only the manganese
phosphate film coated thereon is inferior to seizure resistance of the crank shaft made of
the cast material and having only the manganese phosphate film coated thereon by
approximately 10 %. Accordingly, if the material of the crank shaft is changed from
the cast material to the forged material, the crank shaft becomes easy to seize in the
bearing, even if the deflection amount of the crank shaft does not increase. Reliability
of the compressor is thereby impaired.
[0007] Even if a crank shaft made of steel for mechanical structure and having a
manganese phosphate film and a molybdenum disulfide film coated thereon is used as
in the rotary compressor described in Patent Literature 1, seizure resistance of the crank
shaft is not sufficiently improved.
[0008] An object of the present invention is to sufficiently improve seizure resistance
of a crank shaft in a compressor.
Solution to Problem
[0009] A compressor according to one aspect of the present invention may include:
a crank shaft with a portion thereof covered with a solid lubricant film including molybdenum disulfide and resin;

a motor to rotate the crank shaft; and
a compressing mechanism including a bearing rotatably fitted on the portion of the crank shaft covered with the solid lubricant film, the compressing mechanism being driven by rotation of the crank shaft. Advantageous Effects of Invention
[0010] In the present invention, the film including the resin as well as the molybdenum disulfide is employed for the crank shaft of the compressor. Therefore, seizure resistance of the crank shaft is sufficiently improved. Brief Description of Drawings
[0011] Fig. 1 is a circuit diagram of a refrigerating cycle apparatus according to Embodiment 1.
Fig. 2 is a circuit diagram of the refrigerating cycle apparatus according to Embodiment 1.
Fig. 3 is a longitudinal sectional view of a compressor according to Embodiment 1.
Fig. 4 is a sectional view taken along the line A-A of Fig. 3.
Fig. 5 is a sectional view illustrating a structure of a film on a solid lubricant application portion of a crank shaft in the compressor according to Embodiment 1.
Fig. 6 is a graph illustrating a relationship between a ratio of a film thickness to a crank shaft diameter and a percentage of a seizure load with respect to a conventional product, in the compressor according to Embodiment 1.
Fig. 7 is a graph illustrating a relationship between a ratio of a film thickness variation to a clearance between the film and a bearing and a ratio of an oil film thickness with respect to the conventional product, in the compressor according to Embodiment 1.

Description of Embodiments
[0012] Hereinafter, an embodiment of the present invention will be described, using the drawings. The same or equivalent portions are denoted by the same reference numerals throughout the respective drawings. Explanations of the same or equivalent portions will be suitably omitted or simplified in the description of the embodiment. Concerning configurations of devices, instruments, components, and so on, their materials, shapes, sizes, and so on can be appropriately changed within the scope of the present invention. [0013] Embodiment 1.
This embodiment will be described, using Figs. 1 to 7. [0014] * * * Description of Configuration * * *
A configuration of a refrigerating cycle apparatus 10 according to this embodiment will be described with reference to Figs. 1 and 2.
[0015] Fig. 1 illustrates a refrigerant circuit 11 in a cooling operation. Fig. 2 illustrates a refrigerant circuit 11 in a heating operation.
[0016] Though the refrigerating cycle apparatus 10 is an air conditioner in this embodiment, the refrigerating cycle apparatus 10 may be an appliance other than the air conditioner, such as a refrigerator or a heat pump cycle apparatus. [0017] The refrigerating cycle apparatus 10 includes the refrigerant circuit 11 in which a refrigerant circulates. The refrigerating cycle apparatus 10 further includes a compressor 12, a four-way valve 13, a first heat exchanger 14 that is an outdoor heat exchanger, an expansion mechanism 15 that is an expansion valve, and a second heat exchanger 16 that is an indoor heat exchanger. The compressor 12, the four-way valve 13, the first heat exchanger 14, the expansion mechanism 15, and the second heat exchanger 16 are connected to the refrigerant circuit 11.

[0018] The compressor 12 compresses the refrigerant. The four-way valve 13 switches the flowing direction of the refrigerant between the cooling operation and the heating operation. In the cooling operation, the first heat exchanger 14 operates as a condenser to dissipate heat of the refrigerant compressed by the compressor 12. That is, the first heat exchanger 14 performs heat exchange, using the refrigerant compressed by the compressor 12. In the heating operation, the first heat exchanger 14 operates as an evaporator to heat the refrigerant by exchanging heat between outdoor air and the refrigerant expanded by the expansion mechanism 15. The expansion mechanism 15 expands the refrigerant which has been dissipated at the condenser. In the heating operation, the second heat exchanger 16 operates as a condenser to dissipate heat of the refrigerant compressed by the compressor 12. That is, the second heat exchanger 16 performs heat exchange, using the refrigerant compressed by the compressor 12. In the cooling operation, the second heat exchanger 16 operates as an evaporator to heat the refrigerant by exchanging heat between indoor air and the refrigerant expanded by the expansion mechanism 15.
[0019] The refrigerating cycle apparatus 10 further includes a control device 17. [0020] Specifically, the control device 17 is a microcomputer. Although Figs. 1 and 2 illustrate only a connection between the control device 17 and the compressor 12, the control device 17 may be connected not only to the compressor 12 but also to each element connected to the refrigerant circuit 11, other than the compressor 12. The control device 17 monitors and controls the state of each element connected to the control device 17.
[0021] As the refrigerant circulating in the refrigerant circuit 11, an HFC (HydroFluoroCarbon)-based refrigerant such as R32, R125, R134a, R407C, or R410A is used. Alternatively, an HFO (HydroFluoroOlefin)-based refrigerant such as Rl 123,

R1132 (E), R1132 (Z), R1132a, R1141, R1234yf, R1234ze (E), or R1234ze (Z) is used.
Alternatively, a natural refrigerant such as R290 (propane), R600a (isobutane), R744
(carbon dioxide), or R717 (ammonia) is used. Alternatively, other refrigerants are
used. Alternatively, a mixture of two or more types of these refrigerants is used.
[0022] A configuration of the compressor 12 according to this embodiment will be
described with reference to Fig. 3.
[0023] Fig. 3 illustrates a longitudinal section of the compressor 12.
[0024] In this embodiment, the compressor 12 is a hermetic type compressor.
Specifically, the compressor 12 is a single-cylinder rotary compressor, but the
compressor 12 may be a multi-cylinder rotary compressor, a scroll compressor, or a
reciprocating compressor.
[0025] The compressor 12 includes a hermetic container 20, a compressing
mechanism 30, a motor 40, and a crank shaft 50.
[0026] Refrigerating machine oil 25 is reserved at the bottom portion of the hermetic
container 20. An intake pipe 21 to suck the refrigerant and a discharge pipe 22 to
discharge the refrigerant are attached to the hermetic container 20.
[0027] The motor 40 is accommodated in the hermetic container 20. Specifically,
the motor 40 is placed at an upper portion of the inside of the hermetic container 20.
Though the motor 40 is a concentrated-winding motor in this embodiment, the motor 40
may be a distributed-winding motor.
[0028] The compressing mechanism 30 is accommodated inside the hermetic
container 20. Specifically, the compressing mechanism 30 is placed at a lower portion
of the inside of the hermetic container 20. That is, the compressing mechanism 30 is
placed below the motor 40 inside the hermetic container 20.
[0029] The motor 40 and the compressing mechanism 30 are coupled by the crank

shaft 50. The crank shaft 50 forms an oil supply path for the refrigerating machine oil 25 and the rotation shaft of the motor 40.
[0030] Along with the rotation of the crank shaft 50, the refrigerating machine oil 25 is pumped up by an oil pump provided at the lower portion of the crank shaft 50. Then, the refrigerating machine oil 25 is supplied to each slide portion of the compressing mechanism 30 and lubricates each slide portion of the compressing mechanism 30. As the refrigerating machine oil 25, POE (polyol ester), PVE (polyvinyl ether), or AB (alkyl benzene) or the like, each being synthetic oil, is used.
[0031] The motor 40 rotates the crank shaft 50. The compressing mechanism 30 is driven by the rotation of the crank shaft 50 and compresses the refrigerant. That is, the compressing mechanism 30 is driven by a rotation force of the motor 40 that is transmitted via the crank shaft 50 and compresses the refrigerant. Specifically, this refrigerant is a low-pressure gas refrigerant sucked into the intake pipe 21. A high-temperature and high-pressure gas refrigerant compressed by the compressing mechanism 30 is discharged into the hermetic container 20 from the compressing mechanism 30.
[0032] The crank shaft 50 includes an eccentric shaft portion 51, a main shaft portion 52, and a sub-shaft portion 53. These portions are provided in the order of the main shaft portion 52, the eccentric shaft portion 51, and the sub-shaft portion 53 in the axial direction. That is, the main shaft portion 52 is provided on one axial end side of the eccentric shaft portion 51, and the sub-shaft portion 53 is provided on the other axial end side of the eccentric shaft portion 51. Each of the eccentric shaft portion 51, the main shaft portion 52, and the sub-shaft portion 53 has a columnar shape. The main shaft portion 52 and the sub-shaft portion 53 are provided so that the center axes of the main shaft portion 52 and the sub-shaft portion 53 match with each other, or are

coaxially provided. The eccentric shaft portion 51 is provided so that the central axis
of the eccentric shaft portion 51 deviates from the central axes of the main shaft portion
52 and the sub-shaft portion 53. When each of the main shaft portion 52 and the
sub-shaft portion 53 rotates around the central axis, the eccentric shaft portion 51
eccentrically rotates.
[0033] A solid lubricant is applied to a portion of the crank shaft 50 so as to form a
film. A structure of the film on the portion of the crank shaft 50 with the solid
lubricant applied thereto, or a solid lubricant application portion 37 will be described
later.
[0034] Hereinafter, details of the motor 40 will be described.
[0035] Though the motor 40 in this embodiment is a brushless DC (Direct Current)
motor, the motor 40 may be a motor other than the brushless DC motor, such as an
induction motor.
[0036] The motor 40 includes a stator 41 and a rotor 42.
[0037] The stator 41 has a cylindrical shape and is fixed in contact with the inner
circumferential surface of the hermetic container 20. The rotor 42 has a columnar
shape and is placed inside of stator 41 having a space of 0.3 to 1.0 mm apart from the
stator 41.
[0038] The stator 41 includes a stator core 43 and a winding 44. The stator core 43
is fabricated by punching out each of a plurality of electromagnetic steel plates, which
contains iron as a major component and has a thickness of 0.1 to 1.5 mm, into a certain
shape, laminating the punched-out electromagnetic steel plates axially, and fixing the
laminated electromagnetic steel plates by caulking. The stator core 43 has an outer
diameter that is larger than the inner diameter of an intermediate portion of the hermetic
container 20 and is fixed inside the hermetic container 20 by shrinkage fit. The

winding 44 is wound around the stator core 43. Specifically, the winding 44 is wound around the stator core 43 via an insulating member by concentrated winding. One ends of lead wires not illustrated are connected to the winding 44. The winding 44 includes a core wire and at least one-layer film covering the core wire. In this embodiment, the core wire is made of copper. The film is made of AI (amide-imide)/EI (ester-imide). The insulating member is made of PET (polyethylene terephthalate).
[0039] A method of fixing the electromagnetic steel plates of the stator core 43 to each other is not limited to the caulking. A different method such as welding may be used. A method of fixing the stator core 43 inside the hermetic container 20 is not limited to the shrinkage fit, and press fitting may be used. The core wire of the winding 44 may be made of aluminum. The insulating member may be made of PBT (polybutylene terephthalate), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PTFE (polytetrafluoroethylene), LCP (liquid-crystal polymer), PPS (polyphenylene sulfide), or phenol resin.
[0040] The rotor 42 includes a rotor core 45 and permanent magnets not illustrated. As with the stator core 43, the rotor core 45 is fabricated by punching out each of a plurality of electromagnetic steel plates, which contains iron as a major component and has a thickness of 0.1 to 1.5 mm, into a certain shape, laminating the punched-out electromagnetic steel plates axially, and fixing the laminated electromagnetic steel plates by caulking. Each permanent magnet is inserted in a corresponding one of a plurality of insertion holes formed in the rotor core 45. Each permanent magnet forms a magnetic pole. As each permanent magnet, a ferrite magnet or a rare-earth magnet is used.

[0041] A method of fixing the electromagnetic steel plates of the rotor core 45 to each other is not limited to the caulking, and a different method such as welding may be used.
[0042] A shaft hole, into which the main shaft portion 52 of the crank shaft 50 is shrink fitted, or press fitted, is formed at the center of the rotor core 45 in a plan view. That is, the rotor core 45 has an inner diameter that is smaller than the outer diameter of the main shaft portion 52. Although not illustrated, a plurality of through holes are formed axially around the shaft hole of the rotor core 45. Each through hole forms one of the passages for the gas refrigerant which is to be emitted from a discharge muffler 35 that will be described later to the space in the hermetic container 20. Each through hole also serves as one of the passages for letting the refrigerating machine oil 25 introduced to the upper portion of the hermetic container 20 fall to the lower portion of the hermetic container 20.
[0043] Although not illustrated, if the motor 40 is formed as an induction motor, each of conductors made of aluminum, copper, or the like fills or is inserted in a corresponding one of slots formed in the rotor core 45. Then, a squirrel cage winding, wherein each of the two ends of the conductors is short-circuited with one of end rings, is formed.
[0044] A terminal 24 connected to an external power supply such as an inverter device is attached to the top portion of the hermetic container 20. Specifically, the terminal 24 is a glass terminal. In this embodiment, the terminal 24 is fixed to the hermetic container 20 by welding. The other ends of the lead wires described above are connected to the terminal 24 so as to electrically connect the terminal 24 and the winding 44 of the motor 40. [0045] The discharge pipe 22 whose both axial ends are open, is attached to the top

portion of the hermetic container 20. The gas refrigerant which has been discharged
from the compressing mechanism 30 is discharged from the space in the hermetic
container 20 to the external refrigerant circuit 11 through the discharge pipe 22.
[0046] The compressing mechanism 30 will be described in detail hereinbelow, with
reference to not only Fig. 3 but also Fig. 4.
[0047] Fig. 4 illustrates a section taken along the line A-A of Fig. 3, or taken when the
compressing mechanism 30 is cut by a perpendicular plane to the axial direction of the
crank shaft 50. In Fig. 4, hatching that expresses a section is omitted.
[0048] The compressing mechanism 30 includes a cylinder 31, a roller 32, a main
bearing 33, a sub-bearing 34, and the discharge muffler 35.
[0049] The inner circumference of the cylinder 31 has a circular shape in a plan view.
A cylinder chamber 61 being a space that has a circular shape in a plan view is formed
in the cylinder 31. The outer circumferential surface of the cylinder 31 is provided
with an inlet port for sucking the gas refrigerant from the refrigerant circuit 11. The
refrigerant that has been sucked from the inlet port is compressed in the cylinder
chamber 61. Both axial ends of the cylinder 31 are open.
[0050] The roller 32 has a ring-like shape. Accordingly, each of the inner and outer
circumferences of the roller 32 has a circular shape in a plan view. The roller 32
eccentrically rotates in the cylinder chamber 61. The roller 32 is slidably fitted on the
eccentric shaft portion 51 of the crank shaft 50 that servers as the rotation shaft of the
roller 32.
[0051] The cylinder 31 is provided with a vane groove 62 communicating with the
cylinder chamber 61 and extending radially. A back-pressure chamber 63, which is a
space that has a circular shape in a plan view and communicates with the vane groove
62, is formed at the outer side of the vane groove 62. A vane 64 for partitioning the

cylinder chamber 61 into a suction chamber that is a low-pressure working chamber and a compression chamber that is a high-pressure working chamber is placed in the vane groove 62. The vane 64 has a plate-like shape with a tip thereof rounded. The vane 64 reciprocates while sliding in the vane groove 62. The vane 64 is constantly pressed against the roller 32 by a vane spring provided in the back-pressure chamber 63. Because of high pressure inside the hermetic container 20, force due to the difference between the pressure in the hermetic container 20 and the pressure in the cylinder chamber 61 acts on the vane rear surface that is a surface of the vane 64 at the side of the back-pressure chamber 63, when the compressor 12 starts operation,. Therefore, the vane spring is mainly used for pressing the vane 64 against the roller 32 at the start-up of the compressor 12, which is when there is no difference between the pressure in the hermetic container 20 and the pressure in the cylinder chamber 61. [0052] The main bearing 33 has an inverted T-shape in a side view. The main bearing 33 is slidably fitted on the main shaft portion 52 which is a portion above the eccentric shaft portion 51, of the crank shaft 50. A through hole 54 that serves as an oil supply path is provided inside the crank shaft 50 in the axial direction. An oil film is formed between the main bearing 33 and the main shaft portion 52 by supply of the refrigerating machine oil 25 sucked up through this through hole 54. The main bearing 33 closes the upper side of the cylinder chamber 61 of the cylinder 31 and the upper side of the vane groove 62 of the cylinder 31. That is, the main bearing 33 closes the upper sides of two working chambers in the cylinder 31.
[0053] The sub-bearing 34 has a T-shape in a side view. The sub-bearing 34 is slidably fitted on the sub-shaft portion 53 which isa portion below the eccentric shaft portion 51, of the crank shaft 50. An oil film is formed between the sub-bearing 34 and the sub-shaft portion 53 by supply of the refrigerating machine oil 25 sucked up

through the through hole 54 of the crank shaft 50. The sub-bearing 34 closes the lower side of the cylinder chamber 61 of the cylinder 31 and the lower side of the vane groove 62 of the cylinder 31. That is, the sub-bearing 34 closes the lower sides of the two working chambers in the cylinder 31.
[0054] Each of the main bearing 33 and the sub-bearing 34 is fixed to the cylinder 31 by a fastener 36 such as a bolt and supports the crank shaft 50 that is the rotation shaft of the roller 32. The main bearing 33 supports the main shaft portion 52 without contacting the main shaft portion 52, using fluid lubrication of the oil film between the main bearing 33 and the main shaft portion 52. Similarly to the main bearing 33, the sub-bearing 34 supports the sub-shaft portion 53 without contacting the sub-shaft portion 53, using fluid lubrication of the oil film between the sub-bearing 34 and the sub-shaft portion 53.
[0055] Although not illustrated, a discharge port for discharging the refrigerant compressed in the cylinder chamber 61 to the refrigerant circuit 11 is provided in the main bearing 33. The discharge port is in a position that communicates with the compression chamber when the cylinder chamber 61 is partitioned into the suction chamber and the compression chamber by the vane 64. A discharge valve to openably/closably block the discharge port is attached to the main bearing 33. The discharge valve closes until the gas refrigerant in the compression chamber reaches a desired pressure and opens when the gas refrigerant in the compression chamber reaches the desired pressure. So that, discharge timing of the gas refrigerant from the cylinder 3lis controlled.
[0056] The discharge muffler 35 is attached to the outer side of the main bearing 33. The high-temperature and high-pressure gas refrigerant discharged when the discharge valve opens temporarily enters the discharge muffler 35 and is then emitted from the

discharge muffler 35 to the space in the hermetic container 20. [0057] The discharge port and the discharge valve may be provided for the sub-bearing 34, or each of the main bearing 33 and the sub-bearing 34. The discharge muffler 35 is attached to the outer side of the bearing where the discharge port and the discharge valve are provided.
[0058] An intake muffler 23 is provided beside the hermetic container 20. The intake muffler 23 sucks the low-pressure gas refrigerant from the refrigerant circuit 11. The intake muffler 23 suppresses direct entry of the liquid refrigerant into the cylinder chamber 61 of the cylinder 31 when the liquid refrigerant returns. The intake muffler 23 is connected to the intake port provided in the outer circumferential surface of the cylinder 31 through the intake pipe 21. The intake port is in a position that communicates with the suction chamber when the cylinder chamber 61 is partitioned into the suction chamber and the compression chamber by the vane 64. The main body of the intake muffler 23 is fixed to the side surface of the hermetic container 20 by welding or the like.
[0059] Though the eccentric shaft portion 51, the main shaft portion 52, and the sub-shaft portion 53 of the crank shaft 50 may be made of a cast material, the eccentric shaft portion 51, the main shaft portion 52, and the sub-shaft portion 53 of the crank shaft 50 in this embodiment are made of a forged material such as the S45C. On contrast therewith, the main bearing 33 and the sub-bearing 34 are made of one of a cast material and a sintered material. Specifically, the main bearing 33 and the sub-bearing 34 are made of sintered steel, gray cast iron, or carbon steel. The cylinder 31 is also made of sintered steel, gray cast iron, or carbon steel. The roller 32 is made of a cast material, and specifically, the roller 32 is made of alloy steel containing molybdenum, nickel, and chrome, or an iron-based cast material. The vane 64 is made of high-speed

tool steel.
[0060] Although not illustrated, if the compressor 12 is formed as a swing-type rotary compressor, the vane 64 is formed integrally with the roller 32. When the crank shaft 50 is driven, the vane 64 projects and retracts along the groove in a support body rotatably attached to the roller 32. Along with the rotation of the roller 32, the vane 64 moves forward and backward radially while swinging, to partition the interior of the cylinder chamber 61 into a compression chamber and a suction chamber. The support body is formed of two columnar members each having a semicircular cross section. The support body is rotatably fitted in a circular holding hole formed at an intermediate portion between the inlet port and discharge port for the cylinder 31. [0061] *** Description of Operation ***
The operation of the compressor 12 according to this embodiment will be described with reference to Figs. 3 and 4. The operation of the compressor 12 corresponds to a refrigerant compression method according to this embodiment. [0062] Power is supplied from the terminal 24 to the stator 41 of the motor 40 via the lead wires. Current thereby flows through the winding 44 of the stator 41, and magnetic flux is generated from the winding 44. The rotor 42 of the motor 40 rotates by the action of the magnetic flux generated from the winding 44 and the magnetic flux generated from the permanent magnets of the rotor 42. Specifically, the rotor 42 rotates by an attractive and repulsive action between a rotating magnetic field that is generated due to passage of the current through the winding 44 of the stator 41 and the magnetic field of the permanent magnets of the rotor 42. The rotation of the rotor 42 causes the crank shaft 50, which is fixed to the rotor 42, to rotate. Along with the rotation of the crank shaft 50, the roller 32 of the compressing mechanism 30 eccentrically rotates in the cylinder chamber 61 in the cylinder 31 of the compressing

mechanism 30. The cylinder chamber 61 that is the space between the cylinder 31 and the roller 32 is divided into the suction chamber and the compression chamber by the vane 64. Along with the rotation of the crank shaft 50, the volumes of the suction chamber and the compression chamber change. In the suction chamber, as the volume gradually enlarges, the low-pressure gas refrigerant is sucked from the intake muffler 23. In the compression chamber, as the volume is gradually reduced, the gas refrigerant inside is compressed. The compressed gas refrigerant, the pressure and temperature of which have become high, is discharged from the discharge muffler 35 to the space in the hermetic container 20. The discharged gas refrigerant further passes through the motor 40 and is discharged from the discharge pipe 22 at the top portion of the hermetic container 20 to the outside of the hermetic container 20. The refrigerant discharged to the outside of the hermetic container 20 passes through the refrigerant circuit 11 to return again to the intake muffler 23. [0063] *** Detailed Description of Configuration ***
Details of the solid lubricant application portion 37 of the crank shaft 50 will be described with reference to Figs. 3 and 5.
[0064] Fig. 5 illustrates a portion of a section of three layers that are a solid lubricant film 70, a manganese phosphate film 80, and a base material 55 of the crank shaft 50. [0065] The solid lubricant film 70 includes molybdenum disulfide 71 and resin 72. Specifically, the resin 72 is PAI (polyamide-imide). In this embodiment, the solid lubricant film 70 further includes graphite 73.
[0066] Preferably, the resin 72 is the PAI, but may be PTFE, PPS, PES (polyethersulfone), PI (polyimide), or PEEK (polyetheretherketone). [0067] A portion of the crank shaft 50 is covered with the solid lubricant film 70 having the configuration as mentioned above. Then, the main bearing 33 and the

sub-bearing 34 of the compressing mechanism 30 are slidably fitted on the portion of the crank shaft 50 covered with the solid lubricant film 70. That is, in this embodiment, a portion of the main shaft portion 52 where the main bearing 33 is fitted and a portion of the sub-shaft portion 53 where the sub-bearing 34 is fitted are covered with the solid lubricant film 70 having the configuration as mentioned above. By including the resin 72 as well as the molybdenum disulfide 71 in the solid lubricant film 70, seizure resistance of the crank shaft 50 can be sufficiently enhanced. Accordingly, seizure of the main shaft portion 52 in the main bearing 33 becomes difficult. Seizure of the sub-shaft portion 53 in the sub-bearing 34 also becomes difficult. [0068] As described above, in this embodiment, the main bearing 33 and the sub-bearing 34 are made of one of the cast material and the sintered material while the main shaft portion 52 and the sub-shaft portion 53 are made of the forged material. However, the main shaft portion 52 and the sub-shaft portion 53 and the main bearing 33 and the sub-bearing 34 may be made of similar composition metals. As a specific example, the main shaft portion 52 and the sub-shaft portion 53 and the main bearing 33 and the sub-bearing 34 may be all made of an iron-based material. Generally, sliding of similar composition metals causes reduction of seizure resistance due to "co-alloy". In this embodiment, however, reduction of seizure resistance of each of the main shaft portion 52 and the sub-shaft portion 53 due to the "co-alloy" can be suppressed by the solid lubricant film 70.
[0069] In this embodiment, a portion of the eccentric shaft portion 51 where the roller 32 is fitted is also covered with the solid lubricant film 70 having the configuration as mentioned above. Accordingly, seizure of the eccentric shaft portion 51 in the roller 32 becomes difficult. [0070] As described above, in this embodiment, the roller 32 is made of the cast

material while the eccentric shaft portion 51 is made of the forged material. However, the eccentric shaft portion 51 and the roller 32 may be made of similar composition metals. As a specific example, the eccentric shaft portion 51 and the roller 32 may be both made of an iron-based material. In this embodiment, reduction of seizure resistance of the eccentric shaft portion 51 due to the "co-alloy" can also be suppressed by the solid lubricant film 70.
[0071] In this embodiment, a portion of the main shaft portion 52 that is shrink-fitted or press fitted into the rotor core 45 is not covered with the solid lubricant film 70. Accordingly, it becomes easy to shrink-fit or press-fit the main shaft portion 52 into the shaft hole of the rotor core 45.
[0072] Though the graphite 73 is not essential, the seizure resistance of the crank shaft 50 can be further enhanced by including the graphite 73 in the solid lubricant film 70. [0073] In the portion of the crank shaft 50 covered with the solid lubricant film 70, the solid lubricant film 70 is overlaid on the manganese phosphate film 80. A surface 81 of the manganese phosphate film 80 in contact with the solid lubricant film 70 is an uneven surface. That is, a lot of concave portions 82 and convex portions 83 are formed on the surface 81 of the manganese phosphate film 80. Since the surface 81 of the manganese phosphate film 80 is not even, the solid lubricant film 70 readily adheres closely to the surface 81 of the manganese phosphate 80, thereby making it difficult for the solid lubricant film 70 to peel off. Accordingly, the seizure resistance of the crank shaft 50 is further improved.
[0074] If a roughness of the surface 81 of the manganese phosphate film 80 in contact with the solid lubricant film 70 is 1.5 z or more, an effect that the solid lubricant film 70 readily adheres closely to the manganese phosphate film 80 can be obtained. Preferably, the roughness of the surface 81 of the manganese phosphate film 80 is 2.0 z

or more, and more preferably, the roughness of the surface 81 of the manganese phosphate film 80 is 3.0 z or more, in order to obtain a higher effect. Parameter value such as 1.5 z, 2.0 z, or 2.0 z is a value quantified the roughness of the surface 81 of the manganese phosphate film 80 using ten-point average height. [0075] The manganese phosphate film 80 is formed by applying manganese phosphate surface treatment to the base material 55 of the crank shaft 50. If buffing is applied after the manganese phosphate surface treatment as in the prior art, the surface 81 of the manganese phosphate film 80 is smoothed. So that, the concave portions 82 and the convex portions 83 of the manganese phosphate film 80 are removed. Therefore, in this embodiment, the buffing is omitted. As a result, the roughness of the surface 81 of the manganese phosphate film 80 as described above is obtained. Then, the seizure resistance of the crank shaft 50 is improved by approximately 70 % with respect to a case where the buffing is applied after the manganese phosphate surface treatment.
[0076] The solid lubricant film 70 is formed by applying defric coating to the manganese phosphate film 80 after the manganese phosphate surface treatment. When the solid lubricant is applied by dipping, the molybdenum disulfide 71 may penetrate into the manganese phosphate film 80. Therefore, in this embodiment, the solid lubricant is applied to the surface 81 of the manganese phosphate film 80 by spraying when the defric coating is performed. As a result, the molybdenum disulfide 71 is not penetrating into the manganese phosphate film 80, so that the solid lubricant film 70 having the structure illustrated in Fig. 5 can be obtained. Then, the seizure resistance of the crank shaft 50 is sufficiently improved.
[0077] Fig. 6 illustrates a relationship between a ratio of a film thickness to a crank shaft diameter and a percentage of a seizure load with respect to a conventional product.

[0078] The "crank shaft diameter" refers to the diameter of a portion of the crank shaft 50 where the bearing is fitted. In this embodiment, the diameter of the portion of the main shaft portion 52 where the main bearing 33 is fitted corresponds to the "crank shaft diameter". The diameter of the portion of the sub-shaft portion 53 where the sub-bearing 34 is fitted also corresponds to the "crank shaft diameter". [0079] The "film thickness" refers to a minimum thickness of the solid lubricant film 70. In this embodiment, in the portion of the main shaft portion 52 where the main bearing 33 is fitted, the distance from the vertex of the convex portion 83 that is the highest in the manganese phosphate film 80 to a sliding surface 74 of the solid lubricant film 70 opposed to the main bearing 33 corresponds to the "film thickness". In the portion of the sub-shaft portion 53 where the sub-bearing 34 is fitted, the distance from the vertex of the convex portion 83 that is the highest in the manganese phosphate film 80 to the sliding surface 74 of the solid lubricant film 70 opposed to the sub-bearing 34 also corresponds to the "film thickness".
[0080] The "ratio of the film thickness to the crank shaft diameter" refers to a value obtained by dividing the film thickness by the crank shaft diameter. [0081] The "percentage of the seizure load with respect to the conventional product" refers to a percentage of the seizure resistance of the crank shaft 50 according to this embodiment to seizure resistance of the conventional product having only the manganese phosphate film coated thereon. It is assumed that a total thickness of the solid lubricant film 70 and the manganese phosphate film 80 is the same as the thickness of the film of the conventional product.
[0082] As illustrated in Fig. 6, when the ratio of the film thickness to the crank shaft diameter exceeds 0.8 x 103, the percentage of the seizure load with respect to the conventional product falls below 100%. This is because, when the ratio of the film

•5
thickness to the crank shaft diameter exceeds 0.8 x 10" , the solid lubricant film 70 readily peels off. Accordingly, preferably, the ratio of the film thickness to the crank shaft diameter is 0.8 x 10"3 or less.
[0083] Although not illustrated, according to an endurance test result, a sufficient film thickness after the compressor 12 has been operated for a long period of time of 10 years cannot be obtained when the ratio of the film thickness to the crank shaft diameter falls below 0.3 x 10"3. This is because, the longer the operation period of the compressor 12 is, the more an abrasion loss of the solid lubricant film 70 increases. Accordingly, preferably, the ratio of the film thickness to the crank shaft diameter is 0.3 x 10"3 or more.
[0084] As mentioned above, in order to prevent reduction of the seizure resistance due to peeling-off and abrasion of the solid lubricant film 70, preferably, the ratio of the minimum thickness of the solid lubricant film 70 to the diameter of the main shaft portion 52 is not less than 0.0003 and not more than 0.0008, in the portion of the main shaft portion 52 where the main bearing 33 is fitted. Preferably, the ratio of the minimum thickness of the solid lubricant film 70 to the diameter of the sub-shaft portion 53 is not less than 0.0003 and not more than 0.0008, also in the portion of the sub-shaft portion 53 where the sub-bearing 34 is fitted.
[0085] Fig. 7 illustrates a relationship between a ratio of a film thickness variation to a clearance between the film and the bearing and a ratio of an oil film thickness with respect to the conventional product.
[0086] The "clearance between the film and the bearing" means a distance between the solid lubricant film 70 and the bearing. In this embodiment, the maximum value of the distance between the solid lubricant film 70 and the main bearing 33 corresponds to the "clearance between the film and the bearing". The maximum value of the distance

between the solid lubricant film 70 and the sub-bearing 34 also corresponds to the "clearance between the film and the bearing".
[0087] The "film thickness variation" means a difference in height of the sliding surface 74 opposed to the bearing of the solid lubricant film 70. In this embodiment, in the portion where the main bearing 33 of the main shaft portion 52 is fitted, a difference between maximum and minimum values of a distance from the outer circumferential surface of the base material 55 of the main shaft portion 52 to the sliding surface 74 of the solid lubricant film 70 opposed to the main bearing 33 corresponds to the "film thickness variation". In the portion where the sub-bearing 34 of the sub-shaft portion 53 is fitted, a difference between maximum and minimum values of a distance from the outer circumferential surface of the base material 55 of the sub-shaft portion 53 to the sliding surface 74 of the solid lubricant film 70 opposed to the sub-bearing 34 corresponds to the "film thickness variation". [0088] The "ratio of the film thickness variation to the clearance between the film and the bearing" is a value obtained by dividing the film thickness variation by the clearance between the film and the bearing.
[0089] The "ratio of the oil film thickness with respect to the conventional product" is a ratio of the thickness of the oil film between the main bearing 33 and the main shaft portion 52 or the thickness of the oil film between the sub-bearing 34 and the sub-shaft portion 53 in the crank shaft 50 according to this embodiment to the thickness of an oil film in the conventional product having only the manganese phosphate film coated thereon.
[0090] When the ratio of the film thickness variation to the clearance between the film and the bearing exceeds 0.15, the ratio of the oil film thickness with respect to the conventional product falls below 1.0, as illustrated in Fig. 7. This is because, when the

ratio of the film thickness variation to the clearance between the film and the bearing exceeds 0.15, a gap between the solid lubricant film 70 and the bearing is too large to make it difficult for the oil film to be formed. Accordingly, the ratio of the film thickness variation to the clearance between the film and the bearing is preferably 0.15 or less.
[0091] As mentioned above, in the portion of the main shaft portion 52 where the main bearing 33 is fitted, the ratio of the difference in the height of the sliding surface 74 of the solid lubricant film 70 opposed to the main bearing 33 to the clearance between the solid lubricant film 70 and the main bearing 33 is preferably 0.15 or less, in order to ensure a sufficient oil film thickness to prevent reduction of sliding durability. Also in the portion of the sub-shaft portion 53 where the sub-bearing 34 is fitted, the ratio of the difference in the height of the sliding surface 74 of the solid lubricant film 70 opposed to the sub-bearing 34 to the clearance between the solid lubricant film 70 and the sub-bearing 34 is preferably 0.15 or less. [0092] * * * Description of Effects of Embodiment * * *
In this embodiment, the film including not only the molybdenum disulfide 71 but also the resin 72 is employed for the crank shaft 50 of the compressor 12. Therefore, the seizure resistance of the crank shaft 50 is sufficiently improved. Specifically, the seizure resistance of the crank shaft 50 is improved by 10% to 20% with respect to the conventional product. Accordingly, even if a forged material is employed for making the crank shaft 50, it becomes difficult for the crank shaft 50 to seize in each bearing. Thus, the diameter of the crank shaft 50 can be reduced without impairing reliability of the compressor 12, so that a highly-efficient compressor 12 can be obtained. [0093] A large quantity of the liquid refrigerant may enter into the hermetic container

20 of the compressor 12 and the viscosity of the refrigerating machine oil 25 is reduced, so that the thickness of the oil film between the main shaft portion 52 and the main bearing 33 and the thickness of the oil film between the sub-shaft portion 53 and the sub-bearing 34 may be remarkably reduced. In this embodiment, even in that case, the seizure of the crank shaft 50 is avoided and the compressor 12 with high reliability can be obtained. [0094] *** Alternative Configuration ***
The solid lubricant film 70 may further include resin of a type different from that of the resin 72. Specifically, the solid lubricant film 70 may include two or more types of resins that are the PAI, the PTFE, the PPS, the PES, the PI, and the PEEK. [0095] As described above, the compressor 12 may be a multi-cylinder rotary compressor. Herein, a description will be given about a case where the compressor 12 is formed as the multi-cylinder rotary compressor, as a variation example of this embodiment.
[0096] Although not illustrated, in this variation example, the compressing mechanism 30 includes a plurality of the cylinders 31, a plurality of the rollers 32, and one or more partition plates the number of which is smaller than the number of the cylinders 31 by one. If the number of the cylinders 31 is two, the number of the rollers 32 is two, and the number of the one or more partition plates is one. [0097] The crank shaft 50 includes the eccentric shaft portions 51, the number of which is the same as the number of the rollers 32. A corresponding one of the rollers 32 is slidably fitted on each eccentric shaft portion 51. The shaft diameter of a portion between the respective eccentric shaft portions 51 is substantially the same as the diameter of the main shaft portion 52. [0098] The cylinder chamber 61 that is a circular space in a plan view is formed in

each cylinder 31. Each roller 32 eccentrically rotates within a corresponding one of the cylinder chambers 61. That is, a plurality of the cylinder chambers 61 being a space for compressing the refrigerant are formed in the compressing mechanism 30. These plurality of the cylinder chambers 61 are each partitioned by the partition plate in the axial direction of the crank shaft 50. That is, the partition plate blocks the cylinder chamber 61 immediately over the partition plate and the cylinder chamber 61 immediately under the partition plate, from each other.
[0099] Each partition plate may be formed of a one plate through which the crank shaft 50 passes. In that case, however, the partition plate cannot be placed in a desired position unless a portion from an axial end of the crank shaft 50 to the eccentric shaft portions 51 is passed through a through hole of the partition plate. That is, the through hole having a size, through which the eccentric shaft portion 51 close to the axial end of the crank shaft 50 can pass, must be formed in the partition plate. On the other hand, the partition plate in this variation example is formed of a plurality of divided plates disposed around the crank shaft 50. Therefore, when the portion between the respective eccentric shaft portions 51 is surrounded by the plurality of divided plates and the divided plates are fixed to each other by a fixture such as a bolt, the partition plate can be placed in the desired position. That is, the through hole having the size, through which the portion between the respective eccentric shaft portions 51 can pass, should be formed in the partition plate. A notch, corresponding to a portion of the through hole to be formed when all the divided plates are combined, is provided on each divided plate. If the number of the divided plates is two, the partition plate of a doughnut shape with a circular through hole formed therein is formed by combination of semicircular divided plates each with a small semicircular notch provided on its straight portion.

[0100] In this variation example as well, the film including not only the molybdenum disulfide 71 but also the resin 72 is employed for the crank shaft 50 of the compressor 12. Accordingly, as described above, the diameter of the crank shaft 50 can be reduced without impairing reliability of the compressor 12, so that a highly efficient compressor 12 can be obtained. Specifically, reduction of the diameter of the crank shaft 50 means reduction of the diameter of the main shaft portion 52 without changing the diameter of each eccentric shaft portion 51, or an increase in an amount of eccentricity. Even if the diameter of each eccentric shaft portion 51 is increased without changing the diameter of the main shaft portion 52, the amount of eccentricity is increased. In this variation example, each partition plate is divided. Thus, even if the diameter of the eccentric shaft portion 51 is increased, it is not necessary to change the size of the through hole in each partition plate. Accordingly, a situation can be avoided where each partition plate cannot block the cylinder chambers 61 from each other because the through hole of the partition plate is too large. Accordingly, the amount of eccentricity can be increased without impairing the reliability of the compressor 12, so that the highly efficient compressor 12 can be obtained. [0101] Having described the preferred embodiment of the present invention, it should be noted that the embodiment may be practiced partly. The present invention is not limited to this embodiment, but various modifications may be made as needed. Reference Signs List
[0102] 10: refrigerating cycle apparatus; 11: refrigerant circuit; 12: compressor; 13: four-way valve; 14: first heat exchanger; 15: expansion mechanism; 16: second heat exchanger; 17: control device; 20: hermetic container; 21: intake pipe; 22: discharge pipe; 23: intake muffler; 24: terminal; 25: refrigerating machine oil; 30: compressing mechanism; 31: cylinder; 32: roller; 33: main bearing; 34: sub-bearing; 35: discharge

muffler; 36: fastener; 37: solid lubricant application portion; 40: motor; 41: stator; 42: rotor; 43: stator core; 44: winding; 45: rotor core; 50: crank shaft; 51: eccentric shaft portion; 52: main shaft portion; 53: sub-shaft portion; 54: through hole; 55: base material; 61: cylinder chamber; 62: vane groove; 63: back-pressure chamber; 64: vane; 70: solid lubricant film; 71: molybdenum disulfide; 72: resin; 73: graphite; 74: sliding surface; 80: manganese phosphate film; 81: surface; 82: concave portion; 83: convex portion

We Claim:
[Claim 1] A compressor comprising:
a crank shaft with a portion thereof covered with a solid lubricant film including molybdenum disulfide and resin;
a motor to rotate the crank shaft; and
a compressing mechanism including a bearing slidably fitted on the portion of the crank shaft covered with the solid lubricant film, the compressing mechanism being driven by rotation of the crank shaft.
[Claim 2] The compressor according to claim 1, wherein the resin is polyamide-imide. [Claim 3] The compressor according to claim 1 or 2, wherein the solid lubricant film further includes graphite.
[Claim 4] The compressor according to any one of claims 1 to 3, wherein in the portion of the crank shaft covered with the solid lubricant film, the solid lubrication film is overlaid on a manganese phosphate film and a surface of the manganese phosphate film in contact with the solid lubricant film is an uneven surface.
[Claim 5] The compressor according to claim 4, wherein a roughness of the surface of the manganese phosphate film in contact with the solid lubricant film is 1.5 z or more. [Claim 6] The compressor according to claim 4, wherein a roughness of the surface of the manganese phosphate film in contact with the solid lubricant film is 2.0 z or more. [Claim 7] The compressor according to claim 4, wherein a roughness of the surface of the manganese phosphate film in contact with the solid lubricant film is 3.0 z or more. [Claim 8] The compressor according to any one of claims 1 to 7, wherein in a portion of the crank shaft where the bearing is fitted, a ratio of a minimum thickness of the solid lubricant film to a diameter of the crank shaft is not less than 0.0003 and not more than

0.0008.
[Claim 9] The compressor according to any one of claims 1 to 8, wherein in the portion
of the crank shaft where the bearing is fitted, a ratio of a difference in height of a sliding
surface of the solid lubricant film opposed to the bearing to a clearance between the
solid lubricant film and the bearing is 0.15 or less.
[Claim 10] The compressor according to any one of claims 1 to 9,
wherein the crank shaft includes a main shaft portion and a sub-shaft portion that are coaxially provided,
wherein the bearing is slidably fitted on each of the main shaft portion and the sub-shaft portion,
wherein portion of the main shaft portion and the sub-shaft portion where the bearing is fitted is covered with the solid lubricant film, and
wherein the bearing is made of one of a cast material and a sintered material while the main-shaft portion and the sub-shaft portion are made of a forged material. [Claim 11] The compressor according to any one of claims 1 to 10,
wherein the crank shaft includes an eccentric shaft portion to eccentrically rotate,
wherein the compressing mechanism includes a roller slidably fitted on the eccentric shaft portion,
wherein a portion of the eccentric shaft portion where the roller is fitted is covered with the solid lubricant film, and
wherein the roller is made of a cast material while the eccentric shaft portion is made of a forged material. [Claim 12] The compressor according to any one of claims 1 to 10,
wherein a plurality of cylinder chambers being a space for compressing a

refrigerant and partitioned by one or more partition plates in an axial direction of the crank shaft are formed in the compressing mechanism, and
wherein the one or more partition plates are each formed of a plurality of divided plates disposed around the crank shaft.
[Claim 13] A refrigerating cycle apparatus including the compressor according to any one of claims 1 to 12.