The present invention relates to a compressor and a refrigerating cycle apparatus. Background Art
[0002] Conventionally, a technique provides circular arc-shaped crownings at both axial end sections of a bush member of a journal bearing for a compressor (for example, see Patent Literature 1). This technique forms circular arc sections having 3mm or more and 5mm or less in width and more than 500 mm in radius, as crownings, at the both end sections of the annular bush member which is made of a polyimide resin material and has 3.5 mm in thickness. Citation List Patent Literature
[0003] Patent Literature 1: JP 2001-289169 A Summary of Invention Technical Problem
[0004] In general, a hermetic type compressor includes a hermetic container, a compression mechanism that compresses a refrigerant, and an electric motor that drives the compression mechanism. The compression mechanism and the electric motor are both housed in the hermetic container and are connected to each other by a crankshaft. The crankshaft includes an eccentric shaft section, a main shaft section, and an auxiliary shaft section. The compression mechanism includes a cylinder, a rolling piston fitted to the eccentric shaft section, a main bearing that is a bearing supporting the main shaft section, an auxiliary bearing that is a bearing supporting the auxiliary shaft section.

The eccentric shaft section and the rolling piston are housed in a cylinder chamber that is an internal space of the cylinder. A working chamber is formed between an outer circumferential surface of the rolling piston and an inner circumferential surface of the cylinder. When the crankshaft is rotated by a rotor of the electric motor, the eccentric shaft section is eccentrically rotated, and the rolling piston is also eccentrically rotated in the cylinder chamber. The eccentric rotation of the rolling piston varies the volume of the working chamber, and the refrigerant suctioned into the working chamber is compressed.
[0005] A refrigerating machine oil is reserved in a bottom section of the hermetic container. The refrigerating machine oil is suctioned up through an oil supply path formed in the crankshaft to fill gaps between the crankshaft and the bearings. As a result, an oil film is formed between the crankshaft and the bearings. The bearings support the crankshaft by the fluid lubrication of the oil film without being in contact with the crankshaft.
[0006] In order to reduce the size of hermetic type compressor and increase the capacity of the hermetic type compressor, it is necessary to increase the output of the electric motor while maintaining the diameter of the crankshaft. To increase the output of the electric motor, it is effective to increase the width of a core of the electric motor. However, increasing the width of the core of the electric motor involves an increase in weight of the rotor and a rise in a position of the center of gravity of the rotor, which leads to an increase in whirl of the rotor. The whirl of the rotor causes a deflection of the crankshaft.
[0007] In the configuration described in Patent Literature 1, the electric motor is provided below the compression mechanism. Meanwhile, there is another hermetic type compressor in which an electric motor is provided above a compression

mechanism. In such a hermetic type compressor, the crankshaft is deflected with a fulcrum at an upper end section of the main shaft section, as the rotor whirls. If the width of the core of the electric motor increases while maintaining the diameter of the crankshaft, since the rigidity of the crankshaft does not vary, the deflection of the crankshaft with the fulcrum at the upper end section of the main shaft section increases with increasing the whirl of the rotor. As a result, the fluid lubrication of the oil film could be inhibited, and the upper end section of the main bearing could come into contact with the main shaft section, which might result in an occurrence of scuff in the upper end section of the main bearing or the main shaft section. [0008] An object of the present invention is to prevent an upper end section of a bearing on an electric motor side from coming into contact with a crankshaft even if a deflection of the crankshaft increases in a compressor. Solution to Problem [0009] A compressor according to one aspect of the present invention includes:
a container, wherein a refrigerating machine oil is reserved in a bottom section of the container;
an electric motor housed in the container; and
a compression mechanism disposed inside the container and below the electric motor, the compression mechanism being driven by a rotational force of the electric motor which is transmitted through the crankshaft, the compression mechanism including a bearing on the electric motor side, the crankshaft being fitted to the bearing, the refrigerating machine oil being supplied from the bottom section of the container to the bearing through the crankshaft, thereby forming an oil film on an inner circumferential surface of the bearing,
wherein an inner circumferential surface of an upper end section of the

bearing is curved, so that an inner diameter of the upper end section of the bearing
gradually increases upward.
Advantageous Effects of Invention
[0010] In the present invention, an inner circumferential surface of an upper end
section of a bearing on an electric motor side is curved, so that an inner diameter of the
upper end section of the bearing gradually increases upward. Therefore, according to
the present invention, even if a deflection of a crankshaft increases, the upper end
section of the bearing is less likely to come into contact with the crankshaft.
Brief Description of Drawings
[0011] Fig. 1 is a circuit diagram of a refrigerating cycle apparatus according to a
first embodiment.
Fig. 2 is a circuit diagram of the refrigerating cycle apparatus according to the first embodiment.
Fig. 3 is a vertical cross-sectional view of a compressor according to the first embodiment.
Fig. 4 is a sectional view of a compression mechanism of the compressor according to the first embodiment, taken along a line A-A.
Fig. 5 is a vertical cross-sectional view of a part of the compression mechanism and crankshaft of the compressor according to the first embodiment.
Fig. 6 is a graph showing a relationship between an axial position of the crankshaft of the compressor and an oil film load capacity according to the first embodiment.
Description of Embodiments
[0012] Hereinafter, embodiments of the present invention will be described, using the drawings. The same or equivalent portions are denoted by the same reference

numerals throughout the drawings. Description on the same or equivalent portions will be suitably omitted or simplified in the descriptions of the embodiments. Concerning the configurations of apparatuses, 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] First Embodiment
The configurations of an apparatus and a device according to this embodiment, an operation of the device according to this embodiment, the detailed configuration of constituent elements of the device according to this embodiment, and effects of this embodiment will be sequentially described. [0014] * * * Description of Configurations * * *
The configuration of a refrigerating cycle apparatus 10 that is the apparatus according to this embodiment will be described with reference to Figs. 1 and 2. [0015] Fig. 1 illustrates a refrigerant circuit 11 during a cooling operation. Fig. 2 illustrates the refrigerant circuit 11 during a heating operation.
[0016] In this embodiment, the refrigerating cycle apparatus 10 is an air conditioner. The refrigerating cycle apparatus 10 may be, however, an apparatus 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 a direction in which the refrigerant flows between during the cooling operation and during the heating operation. The first heat exchanger 14 operates as a condenser during the cooling operation, and radiates heat of the refrigerant compressed by the compressor 12. That is, the first heat exchanger 14 exchanges heat using the refrigerant compressed by the compressor 12. The first heat exchanger 14 operates as an evaporator during the heating operation, and exchanges heat between outdoor air and the refrigerant expanded by the expansion mechanism 15, thereby heating the refrigerant. The expansion mechanism 15 expands the refrigerant the heat of which has been radiated by the condenser. The second heat exchanger 16 operates as a condenser during the heating operation, and radiates heat of the refrigerant compressed by the compressor 12. That is, the second heat exchanger 16 exchanges heat using the refrigerant compressed by the compressor 12. The second heat exchanger 16 operates as an evaporator during the cooling operation, and exchanges heat between indoor air and the refrigerant expanded by the expansion mechanism 15, thereby heating the refrigerant.
[0019] The refrigerating cycle apparatus 10 further includes a controlling device 17. [0020] Specifically, the controlling device 17 is a microcomputer. In Figs. 1 and 2, only connection between the controlling device 17 and the compressor 12 is illustrated; however, the controlling device 17 is connected not only to the compressor 12 but also to each component connected to the refrigerant circuit 11. The controlling device 17 monitors and controls a state of each component.
[0021] As the refrigerant that circulates in the refrigerant circuit 11, an arbitrary refrigerant such as an R32 refrigerant, an R290 (propane) refrigerant, an R407C refrigerant, an R410A refrigerant, an R744 (C02) refrigerant, or an R1234yf refrigerant

may be used.
[0022] The configuration of the compressor 12 that is the device according to this
embodiment will be described with reference to Fig. 3.
[0023] Fig. 3 illustrates a vertical cross section of the compressor 12. Note that in
Fig. 3, hatching indicating a cross section is omitted.
[0024] In this embodiment, the compressor 12 is a hermetic type compressor.
Specifically, the compressor 12 is a single-cylinder rotary compressor. The
compressor 12 may be, however, a rotary compressor with two or more cylinders, a
scroll compressor, or a reciprocating compressor.
[0025] The compressor 12 includes a container 20, a compression mechanism 30, an
electric motor 40, and a crankshaft 50.
[0026] Specifically, the container 20 is a hermetic container. A refrigerating
machine oil 25 is reserved in a bottom section of the container 20. A suction pipe 21
for suctioning the refrigerant and a discharge pipe 22 for discharging the refrigerant are
attached to the container 20.
[0027] The electric motor 40 is housed in the container 20. Specifically, the electric
motor 40 is disposed at an upper section inside the container 20. In this embodiment,
the electric motor 40 is a concentrated winding motor. The electric motor 40 may be,
however, a distributed winding motor.
[0028] The compression mechanism 30 is housed in the container 20. Specifically,
the compression mechanism 30 is disposed at a lower section inside the container 20.
That is, the compression mechanism 30 is disposed inside the container 20 and below
the electric motor 40.
[0029] The electric motor 40 and the compression mechanism 30 are coupled to each
other by the crankshaft 50. The crankshaft 50 forms an oil supply path of the

refrigerating machine oil 25 and a rotation shaft of the electric motor 40. [0030] Along with rotation of the crankshaft 50, the refrigerating machine oil 25 is pumped up by an oil pump provided at the lower section of the crankshaft 50, and is supplied to each sliding section of the compression mechanism 30 to lubricate each sliding section of the compression mechanism 30. As the refrigerating machine oil 25, polyol ester (POE), polyvinyl ether (PVE), alkyl benzene (AB), or the like, each of which is synthetic oil, is used.
[0031] The compression mechanism 30 compresses the refrigerant by being driven by a rotational force of the electric motor 40 transmitted through the crankshaft 50. Specifically, the refrigerant is a low-pressure gas refrigerant suctioned into the suction pipe 21. The high temperature, high pressure gas refrigerant which is compressed by the compression mechanism 30 is discharged from the compression mechanism 30 into the container 20.
[0032] The crankshaft 50 includes an eccentric shaft section 51, a main shaft section 52, and an auxiliary shaft section 53. These components are provided in the order of the main shaft section 52, the eccentric shaft section 51, and the auxiliary shaft section 53 in the axial direction. That is, the main shaft section 52 is provided on one axial end side of the eccentric shaft section 51, and the auxiliary shaft section 53 is provided on the other axial end side of the eccentric shaft section 51. Each of the eccentric shaft section 51, the main shaft section 52, and the auxiliary shaft section 53 has a cylindrical shape. The main shaft section 52 and the auxiliary shaft section 53 are disposed so that central axes thereof coincide with each other, that is, are disposed coaxially. The eccentric shaft section 51 is disposed so that a central axis of the eccentric shaft section 51 is offset from the central axes of the main shaft section 52 and the auxiliary shaft section 53. When the main shaft section 52 and the auxiliary shaft section 53 are

rotated about the central axes thereof, the eccentric shaft section 51 is eccentrically
rotated.
[0033] Hereinafter, details of the electric motor 40 will be described.
[0034] In this embodiment, the electric motor 40 is a brushless direct current (DC)
motor. The electric motor 40 may be, however, an electric motor other than the
brushless DC motor such as an induction electric motor.
[0035] The electric motor 40 includes a stator 41 and a rotor 42.
[0036] The stator 41 has a cylindrical shape and is fixed so as to be in contact with an
inner circumferential surface of the container 20. The rotor 42 has a cylindrical shape
and is disposed on an inner side of the stator 41 with a gap having 0.3 mm or more and
1.0 mm or less in width.
[0037] The stator 41 includes a stator iron core 43 and windings 44. The stator iron
core 43 is manufactured by punching a plurality of magnetic steel sheets, each of which
contains iron as a major component and has 0.1 mm or more and 1.5 mm or less in
thickness, into a predetermined shape, laminating the punched sheets in the axial
direction, and fixing the sheets by caulking, welding, or the like. An outer diameter of
the stator iron core 43 is larger than an inner diameter of an intermediate section of the
container 20. The stator iron core 43 is fixed by being shrinkage-fitted to the inside of
the container 20. The windings 44 are wound on the stator iron core 43. Specifically,
the windings 44 are wound around the stator iron core 43 via an insulating member by
concentrated winding. Each winding 44 is constituted from a core wire and
at-least-one-layer film covering the core wire. In this embodiment, the material of the
core wire is copper. The material of the film is amide-imide (AI)/ester-imide (EI).
The material of the insulating member is polyethylene terephthalate (PET). The
material of the core wire may be aluminum. The material of the insulating member

may be polybutylene terephthalate (PBT), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), liquid-crystal polymer (LCP), polyphenylene sulfide (PPS), or phenol resin. First ends of lead wires not illustrated are connected to the windings 44.
[0038] The rotor 42 includes a rotor iron core 45 and permanent magnets not illustrated. Similarly to the stator iron core 43, the rotor iron core 45 is manufactured by punching a plurality of magnetic steel sheets, each of which contains iron as a major component and has 0.1 mm or more and 1.5 mm or less in thickness, into a predetermined shape, laminating the punched sheets in the axial direction, and fixing the sheets by caulking, welding, or the like. The permanent magnets are inserted in a plurality of insertion holes formed in the rotor iron core 45. Each permanent magnet forms a magnetic pole. As each permanent magnet, a ferrite magnet or a rare-earth magnet is used.
[0039] A shaft hole, into which the main shaft section 52 of the crankshaft 50 is fitted by shrinkage fit or pressed, is formed in the center of the rotor iron core 45 in plan view. Though not illustrated, a plurality of through holes penetrating in the axial direction are formed around the shaft hole of the rotor iron core 45. Each through hole serves as one of paths for a gas refrigerant emitted from a discharge muffler 35 which will be described later to the space in the container 20.
[0040] Though not illustrated, if the electric motor 40 is formed as the induction electric motor, conductors made of aluminum, copper, or the like fill or are inserted in a plurality of slots formed in the rotor iron core 45. Then, a squirrel-cage winding, wherein both ends of the conductors are short-circuited by end rings, is formed. [0041] A terminal 24 connected to an external power supply such as an inverter

apparatus is attached to the top section of the container 20. Specifically, the terminal
24 is a glass terminal. In this embodiment, the terminal 24 is fixed to the container 20
by welding. Second ends of the lead wires mentioned above are connected to the
terminal 24. Thereby, the terminal 24 and the windings 44 of the electric motor 40 are
electrically connected.
[0042] The discharge pipe 22 whose both axial ends are open is attached to the top
section of the container 20. The gas refrigerant discharged from the compression
mechanism 30 passes from the space in the container 20 through the discharge pipe 22,
and is discharged to the refrigerant circuit 11 of an outside.
[0043] Hereinafter, details of the compression mechanism 30 will be described with
reference to not only Fig. 4 but also Fig. 3.
[0044] Fig. 4 illustrates a cross section of the compression mechanism 30 taken along
a line A-A in Fig. 1, that is, a plane perpendicular to an axial direction of the crankshaft
50. Note that in Fig. 4, hatching indicating a cross section is omitted.
[0045] The compression mechanism 30 includes a cylinder 31, a rolling piston 32, a
main bearing 33, an auxiliary bearing 34, and the discharge muffler 35.
[0046] An inner circumference of the cylinder 31 has a circular shape in plan view.
Inside the cylinder 31, a cylinder chamber 61 that is a space circular in plan view is
formed. On an outer circumferential surface of the cylinder 31, a suction port for
suctioning the gas refrigerant from the refrigerant circuit 11 is provided. The
refrigerant suctioned from the suction port is compressed in the cylinder chamber 61.
Both axial ends of the cylinder 31 are open.
[0047] The rolling piston 32 has a ring shape. Accordingly, each of an inner
circumference and an outer circumference of the rolling piston 32 has a circular shape in
plan view. The rolling piston 32 eccentrically rotates in the cylinder chamber 61.

The rolling piston 32 is slidably fitted to the eccentric shaft section 51 of the crankshaft 50 that serves as a rotation shaft of the rolling piston 32.
[0048] The cylinder 31 is provided with a vane groove 62 communicating with the cylinder chamber 61 and extending in the radial direction. At the outside of the vane groove 62, a back pressure chamber 63 which is a space circular in plan view and communicates with the vane groove 62 is formed. In the vane groove 62, a vane 64 for partitioning the cylinder chamber 61 into a suction chamber which is a low-pressure working chamber and a compression chamber which is a high-pressure working chamber is provided. The vane 64 is shaped like a plate whose tip is rounded. The vane 64 reciprocates while sliding in the vane groove 62. The vane 64 is constantly pressed against the rolling piston 32 by a vane spring provided in the back pressure chamber 63. Since the pressure inside the container 20 is high, a force generated due to a difference between the pressure inside the container 20 and the pressure inside the cylinder chamber 61 acts on the vane back surface being the surface of the vane 64 on the side of the back pressure chamber 63 when the operation of the compressor 12 starts. Therefore, the vane spring is used for the purpose of pressing the vane 64 against the rolling piston 32 mainly at startup of the compressor 12 when there is no difference between the pressure inside the container 20 and the pressure inside the cylinder chamber 61.
[0049] The main bearing 33 has an inverse T shape in side view. The main bearing 33 is slidably fitted to the main shaft section 52, which is a portion upper than the eccentric shaft section 51, of the crankshaft 50. Inside the crankshaft 50, a through hole 54 serving as the oil supply path is provided along the axial direction. The refrigerating machine oil 25 which is suctioned up through the through hole 54 is supplied between the main bearing 33 and the main shaft section 52, thereby forming an

oil film. The main bearing 33 closes the upper sides of the cylinder chamber 61 and the vane groove 62 of the cylinder 31. That is, the main bearing 33 closes the upper sides of the two working chambers in the cylinder 31.
[0050] The auxiliary bearing 34 has a T shape in side view. The auxiliary bearing 34 is slidably fitted to the auxiliary shaft section 53, which is a portion lower than the eccentric shaft section 51, of the crankshaft 50. The refrigerating machine oil 25 which is suctioned up through the through hole 54 of the crankshaft 50 is supplied between the auxiliary bearing 34 and the auxiliary shaft section 53, thereby forming an oil film. The auxiliary bearing 34 closes the lower sides of the cylinder chamber 61 and the vane groove 62 of the cylinder 31. That is, the auxiliary bearing 34 closes the lower sides of the two working chambers in the cylinder 31.
[0051] The main bearing 33 and the auxiliary bearing 34 are fixed to the cylinder 31 by fasteners 36 such as bolts, respectively and support the crankshaft 50 that serves as the rotation shaft of the rolling piston 32. The main bearing 33 supports the main shaft section 52 by the fluid lubrication of the oil film between the main bearing 33 and the main shaft section 52, without being in contact with the main shaft section 52. Similarly to the main bearing 33, the auxiliary bearing 34 supports the auxiliary shaft section 53 by the fluid lubrication of the oil film between the auxiliary bearing 34 and the auxiliary shaft section 53, without being in contact with the auxiliary shaft section 53.
[0052] Though not illustrated, the main bearing 33 is provided with a discharge port for discharging the refrigerant which is compressed in the cylinder chamber 61 to the refrigerant circuit 11. The discharge port is located at a position where the discharge port communicates with the compression chamber when the cylinder chamber 61 is partitioned into the compression chamber and the suction chamber by the vane 64. A

discharge valve for closing the discharge port in an openable and closable manner 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. With this configuration, a timing at which the gas refrigerant is discharged from the cylinder 31 is controlled. [0053] The discharge muffler 35 is attached to the outer side of the main bearing 33. A high-temperature and high-pressure gas refrigerant which is discharged when the discharge valve opens once enters the discharge muffler 35 and is then emitted into the space in the container 20 from the discharge muffler 35. Note that the discharge port and the discharge valve may be provided in the auxiliary bearing 34 or may be provided in both of the main bearing 33 and the auxiliary bearing 34. The discharge muffler 35 is attached to the outer side of the bearing provided with the discharge port and the discharge valve.
[0054] A suction muffler 23 is provided beside the container 20. The suction muffler 23 suctions the low-pressure gas refrigerant from the refrigerant circuit 11. When a liquid refrigerant returns, the suction muffler 23 prevents the liquid refrigerant from directly entering the cylinder chamber 61 of the cylinder 31. The suction muffler 23 is connected to the suction port provided in the outer circumferential surface of the cylinder 31, via the suction pipe 21. The suction port is located at a position where the suction port communicates with the suction chamber when the cylinder chamber 61 is partitioned into the compression chamber and the suction chamber by the vane 64. The body of the suction muffler 23 is fixed to a side surface of the container 20 by welding or the like.
[0055] In this embodiment, the material of the cylinder 31, the main bearing 33, and the auxiliary bearing 34 is sintered steel. However, the material of the cylinder 31, the

main bearing 33, and the auxiliary bearing 34 may be gray cast iron or carbon steel. The material of the rolling piston 32 is alloy steel containing chromium and so on. The material of the vane 64 is high-speed tool steel.
[0056] Though not illustrated, when the compressor 12 is configured as a swing-type rotary compressor, the vane 64 is unitarily provided with the rolling piston 32. When the crankshaft 50 is driven, the vane 64 reciprocates along a groove of a support body rotatably attached to the rolling piston 32. The vane 64 moves forward and backward radially while swinging, along with the rotation of the rolling piston 32, thereby partitioning the interior of the cylinder chamber 61 into the compression chamber and the suction chamber. The support body is composed of two columnar members each having a semicircular transverse cross section. The support body is rotatably fitted in a circular holding hole formed in an intermediate section between the suction port and the discharge port of the cylinder 31. [0057] *** Description of Operation ***
The operation of the compressor 12 that is the device 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.
[0058] Power is supplied from the terminal 24 to the stator 41 of the electric motor 40 via the lead wires. This causes current to flow through the windings 44 of the stator 41, and magnetic flux is generated from the windings 44. The rotor 42 of the electric motor 40 rotates by the action of the magnetic flux generated from the windings 44 and magnetic flux generated from the permanent magnets of the rotor 42. The rotation of the rotor 42 causes the crankshaft 50 fixed to the rotor 42 to rotate. In association with the rotation of the crankshaft 50, the rolling piston 32 of the compression mechanism 30

eccentrically rotates in the cylinder chamber 61 of the cylinder 31 of the compression mechanism 30. The cylinder chamber 61 which is the space between the cylinder 31 and the rolling piston 32 is divided into the suction chamber and the compression chamber by the vane 64. In association with the rotation of the crankshaft 50, the volumes of the suction chamber and the compression chamber change. In the suction chamber, a gradual increase in the volume causes the low-pressure gas refrigerant to be suctioned from the suction muffler 23. In the compression chamber, a gradual decrease in the volume causes the gas refrigerant inside to be 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 container 20. The discharged gas refrigerant further passes through the electric motor 40 and is discharged outside the container 20 through the discharge pipe 22 at the top section of the container 20. The refrigerant discharged outside the container 20 passes through the refrigerant circuit 11 and returns to the suction muffler 23 again. [0059] *** Detailed Description of Configuration ***
A detailed configuration of the main bearing 33 which is a constituent element of the device according to this embodiment will be described with reference to Fig. 5. [0060] Fig. 5 illustrates a part of a vertical cross section of the compression mechanism 30 and the crankshaft 50. Note that in Fig. 5, hatching indicating a cross section is omitted.
[0061] As described above, the compression mechanism 30 includes the main bearing 33 on the electric motor 40 side and the auxiliary bearing 34 on an opposite side to the electric motor 40 side. The crankshaft 50 is fitted to the main bearing 33 and the auxiliary bearing 34. Specifically, the main shaft section 52 is slidably fitted to the main bearing 33, and the auxiliary shaft section 53 is slidably fitted to the auxiliary

bearing 34. The refrigerating machine oil 25 is supplied from the bottom section of the container 20 to the inner circumferential surface of each of the main bearing 33 and the auxiliary bearing 34 through the crankshaft 50, thereby forming the oil film. The main bearing 33 and the auxiliary bearing 34 support the crankshaft 50 by the fluid lubrication of the oil film without being in contact with the crankshaft 50. [0062] The main bearing 33 includes a flat plate-shaped fixed section 71 and a cylindrical-shaped bearing section 72. The fixed section 71 is fixed to the upper side of the cylinder 31 by the above-described fastener 36. The bearing section 72 rises from the fixed section 71 toward an opposite direction to the cylinder 31, that is, in a direction of the rotor 42. Openings are formed at the both axial ends of the bearing section 72. The main shaft section 52 is inserted into a space connecting these openings to each other so as to penetrate from one opening to the other opening. [0063] Similarly to the main bearing 33, the auxiliary bearing 34 includes a flat plate-shaped fixed section 73 and a cylindrical-shaped bearing section 74. The fixed section 73 is fixed to the lower side of the cylinder 31 by the above-described fastener 36. The bearing section 74 rises from the fixed section 73 toward an opposite direction to the cylinder 31, that is, in a direction of the bottom section of the container 20. Openings are formed at the both axial ends of the bearing section 74. The auxiliary shaft section 53 is inserted into a space connecting these openings to each other so as to penetrate from one opening to the other opening.
[0064] In this embodiment, the electric motor 40 is provided above the compression mechanism 30. Therefore, the deflection of the crankshaft 50 with the fulcrum at the upper end section of the main shaft section 52 increases with increasing the whirl of the rotor 42. If this deflection inhibits the fluid lubrication of the oil film formed between the main bearing 33 and the main shaft section 52, the upper end section 81 of the main

bearing 33 could come into contact with the main shaft section 52, which might result in an occurrence of scuff in the upper end section 81 of the main bearing 33 or the main shaft section 52. Therefore, such a configuration is needed that even if the whirl of the rotor 42 increases, at least either the main bearing 33 or the main shaft section 52 properly maintains the fluid lubrication of the oil film.
[0065] When the rigidity of the main shaft section 52 is increased by increasing the diameter of the main shaft section 52, it is possible to reduce the deflection of the crankshaft 50 which is caused by the whirling of the rotor 42. However, in order to reduce the size of the compressor 12 and to increase the capacity of the compressor 12, it is preferable to increase the width of the core of the electric motor, while maintaining the diameter of the main shaft section 52. Therefore, this embodiment aims to maintain the fluid lubrication of the oil film by devising the configuration of the main bearing 33. That is, in this embodiment, although the main bearing 33 that is provided at a position closer to the electric motor 40 than the auxiliary bearing 34 is largely affected by the deflection of the crankshaft 50 caused by the whirl of the rotor 42, the main bearing 33 is configured to properly maintain the fluid lubrication of the oil film against the deflection. Specifically, an inner circumferential surface 82 of the upper end section 81 of the main bearing 33 is curved, so that the inner diameter of the upper end section 81 of the main bearing 33 gradually increases upward. With this configuration, such an advantageous effect is also achieved that burr is prevented from occurring at the upper end section 81 of the main bearing 33.
[0066] In this embodiment, since an inner circumferential surface 84 of a lower end section 83 of the main bearing 33 is inclined, the inner diameter of the lower end section 83 of the main bearing 33 gradually increases downward. That is, an inner circumferential section of the lower end section 83 of the main bearing 33 are

chamfered. With this configuration, such an advantageous effect is achieved that bun-is prevented from occurring at the lower end section 83 of the main bearing 33. [0067] It is preferable that a vertical distance Dl of a curved section 85 which is a portion where the inner circumferential surface 82 of the upper end section 81 of the main bearing 33 is curved is 0.1 mm or more and 2.0 mm or less. Since a gap 55 between the curved section 85 and the crankshaft 50 is wide when the deflection of the crankshaft 50 is small such as in a case where the compressor 12 operates at a low rotational speed, extension of the vertical distance of the curved section 85 to 3 mm or more widens an area where the oil film does not act effectively. As a result, a substantial bearing length is decreased, and scuff could occur in the upper end section 81 of the main bearing 33 or the main shaft section 52. For the same reason, it is preferable that a vertical distance D2 of an inclined section 86 which is a portion where the inner circumferential surface 84 of the lower end section 83 of the main bearing 33 is inclined is 0.1 mm or more and 2.0 mm or less.
[0068] In this embodiment, the vertical distance Dl of the curved section 85 is equal to the vertical distance D2 of the inclined section 86. A shape of the inner circumferential surface 82 of the curved section 85 in the vertical cross section of the upper end section 81 of the main bearing 33 is a circular arc having a radius equal in length to the vertical distance D2 of the inclined section 86. By adopting such a circular arc shape, as shown in Fig. 6, it is possible to secure a more oil film load capacity than that in a case where the same chamfer as the inclined section 86 is adopted. Therefore, it is possible to maintain the fluid lubrication of the oil film when the crankshaft 50 is deflected largely. Also, as described above, the vertical distance Dl of the curved section 85 which employs the circular arc shape is 0.1 mm or more and 2.0 mm or less. Thereby, it is possible to ensure a substantial bearing length.

Accordingly, even when the crankshaft 50 is not deflected, it is possible to maintain the
fluid lubrication of the oil film.
[0069] In order to easily maintain the fluid lubrication of the oil film, it is preferable
that a gap 56 between the inclined section 86 and the crankshaft 50 is made as narrow as
possible. On the other hand, it is necessary to widen the gap 55 between the curved
section 85 and the crankshaft 50 to such an extent that metal contact can be avoided
when the crankshaft 50 is deflected largely. Therefore, it is preferable that the
maximum width Wl of the gap 55 between the curved section 85 and the crankshaft 50
is larger than the maximum width W2 of the gap 56 between the inclined section 86 and
the crankshaft 50.
[0070] *** Description of Advantageous Effects of the Embodiment ***
In this embodiment, the inner circumferential surface 82 of the upper end section 81 of the main bearing 33 is curved, so that the inner diameter of the upper end section 81 of the main bearing 33 gradually increases upward. Therefore, according to this embodiment, even if the deflection of the crankshaft 50 with the fulcrum at the upper end section of the main shaft section 52 increases, the upper end section 81 of the main bearing 33 is less likely to come into contact with the main shaft section 52. Therefore, it is possible to prevent the occurrence of the scuff in the upper end section 81 of the main bearing 33 or the main shaft section 52.
[0071] To manufacture a compact and high output air conditioner, the compressor 12 needs a small compression mechanism 30 having a large excluded volume. Also, as to a refrigerant to be used under low-pressure conditions among refrigerants that are proposed to be used for the purpose of protecting the global environment, if an amount of such a refrigerant which circulate in the refrigerant circuit 11 is not increased, the same potential as a conventional refrigerant cannot be achieved. Therefore, in order to

use such a refrigerant, the compression mechanism 30 having the large excluded volume is required.
[0072] As a method of increasing the excluded volume, there is a method of increasing the number of cylinders of the compression mechanism 30. However, when the number of cylinders is increased, the compressor 12 is extended in the axial direction, that is, in the height direction, which makes it difficult to reduce the size of the compression mechanism 30. Also, an increase in the number of cylinders complicates the structure of the compression mechanism 30, the number of parts increases, the design load for ensuring the reliability increases, and the cost increases. [0073] In order to maintain or reduce the size of the compressor 12 and to increase the excluded volume, it is optimum to increase the eccentricity amount of the eccentric shaft section 51 of the crankshaft 50 while maintaining the inner diameter of the cylinder chamber 61 of the compression mechanism 30 and the diameter of the crankshaft 50. In order to enhance the output of the electric motor 40 in accordance with the excluded volume, it is effective to increase the width of the core of the electric motor.
[0074] However, if the width of the core of the electric motor is increased while maintaining the diameter of the crankshaft 50, the whirl of the rotor 42 increases due to an increase in the weight of the rotor 42 and a rise in a position of the center of gravity of the rotor 42. Since the rigidity of the crankshaft 50 does not vary, the deflection of the crankshaft 50 with the fulcrum at the upper end section of the main shaft section 52 increases with increasing the whirl of the rotor 42. If this deflection inhibits the fluid lubrication of the oil film, the upper end section 81 of the main bearing 33 could come into contact with the main shaft section 52, which might result in an occurrence of scuff in the upper end section 81 of the main bearing 33 or the main shaft section 52.

[0075] In this embodiment, the curved section 85 having the circular arc shape is provided only at the upper end, near the rotor 42, of the main bearing 33. The radius of the circular arc is equal to the length of the chamfer of the lower end, far from the rotor 42, of the main bearing 33 and preferably 0.1 mm or more and 2.0 mm or less. Thus, when the crankshaft 50 is deflected largely, it is possible to ensure the larger oil film load capacity than the chamfer. • Also, even when the crankshaft 50 is not deflected, it is possible to ensure a substantial bearing length. Therefore, according to this embodiment, it is possible to prevent scuff of the upper end section 81 of the main bearing 33 or the main shaft section 52.
[0076] In this embodiment, the bearings are provided only on one side of the rotor 42. Therefore, the deflection amount of the crankshaft 50 is large on the closer side, to the rotor 42, of the bearing. The deflection amount of the crankshaft 50 is small on the farther side, from the rotor 42, of the bearing. Therefore, the circular arc shape is adopted only at the end, on the closer side to the rotor 42, of the main bearing 33 which is provided at a position closer to the electric motor 40 than the auxiliary bearing 34 is. The end on the farther side from the rotor 42 is chamfered. Thereby, the suitable main bearing 33 is achieved.
[0077] As described above, in this embodiment, even if the deflection of the crankshaft 50 with the fulcrum at the upper end section of the main shaft section 52 increases, it is possible to ensure the oil film load capacity and the substantial bearing length. Therefore, the lubrication properties at both of a tip section and substantial length section of the main bearing 33 do not decrease, and it is possible to prevent scuff. Thus, a highly reliable compressor 12 having a high performance can be obtained. [0078] *** Alternative Configuration ***
In this embodiment, the inclined section 86 is provided at the lower end

section 83 of the main bearing 33. The inclined section 86 may be omitted. That is, the inner circumferential section of the lower end section 83 of the main bearing 33 may not be chamfered.
[0079] The embodiment of the invention has been described above. This embodiment may be implemented partially. Specifically, any one of or an arbitrary combination of some of what are described as constituent elements of the apparatus or device in the descriptions of the embodiments may be adopted. Note that the present invention is not limited to this embodiment, and various modifications may be made as necessary.
Reference Signs List
[0080] 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: controlling device; 20: container; 21: suction pipe; 22: discharge pipe; 23: suction muffler; 24: terminal; 25: refrigerating machine oil; 30: compression mechanism; 31: cylinder; 32: rolling piston; 33: main bearing; 34: auxiliary bearing; 35: discharge muffler; 36: fastener; 40: electric motor; 41: stator; 42: rotor; 43: stator iron core; 44: winding; 45: rotor iron core; 50: crankshaft; 51: eccentric shaft section; 52: main shaft section; 53: auxiliary shaft section; 54: through hole; 55: gap; 56: gap; 61: cylinder chamber; 62: vane groove; 63: backpressure chamber; 64: vane; 71: fixed section; 72: bearing section; 73: fixed section; 74: bearing section; 81: upper end section; 82: inner circumferential surface; 83: lower end section; 84: inner circumferential surface; 85: curved section; 86: inclined section

Claims [Claim 1] A compressor comprising:
a container, wherein a refrigerating machine oil is reserved in a bottom section of the container;
an electric motor housed in the container;
a crankshaft forming an oil supply path of the refrigerating machine oil and a rotation shaft of the electric motor; and
a compression mechanism disposed inside the container and below the electric motor, the compression mechanism being driven by a rotational force of the electric motor which is transmitted through the crankshaft, the compression mechanism including a bearing on the electric motor side, the crankshaft being fitted to the bearing, the refrigerating machine oil being supplied from the bottom section of the container to the bearing through the crankshaft, thereby forming an oil film on an inner circumferential surface of the bearing,
wherein an inner circumferential surface of an upper end section of the bearing is curved, so that an inner diameter of the upper end section of the bearing gradually increases upward.
[Claim 2] The compressor according to claim 1, wherein an inner circumferential surface of a lower end section of the bearing is inclined, so that an inner diameter of the lower end section of the bearing gradually increases downward.
[Claim 3] The compressor according to claim 2, wherein a vertical distance of a curved section which is a portion where the inner circumferential surface of the upper end section of the bearing is curved is equal to that of an inclined section which is a portion where the inner circumferential surface of the lower end section of the bearing is inclined, and a shape of the inner circumferential surface of the curved section in a

vertical cross section of the upper end section of the bearing is a circular arc having a radius equal in length to the vertical distance of the inclined section. [Claim 4] The compressor according to claim 2, wherein a maximum width of a gap between a curved section which is a portion where the inner circumferential surface of the upper end section of the bearing is curved and the crankshaft is larger than a maximum width of a gap between an inclined section which is a portion where the inner circumferential surface of the lower end section of the bearing is inclined and the crankshaft.
[Claim 5] The compressor according to claim 1 or 2, wherein a vertical distance of a curved section which is a portion where the inner circumferential surface of the upper end section of the bearing is curved is 0.1 mm or more and 2.0 mm or less. [Claim 6] The compressor according to any one of claims 1 to 5, wherein the compression mechanism includes a main bearing which is the bearing, on the electric motor side, and an auxiliary bearing on an opposite side to the electric motor side, the crankshaft being fitted to the auxiliary bearing, the refrigerating machine oil being supplied from the bottom section of the container to the auxiliary bearing through the crankshaft, thereby forming an oil film on an inner circumferential surface of the auxiliary bearing.
[Claim 7] A refrigerating cycle apparatus comprising the compressor according to any one of claims 1 to 6.