Work-in-progress crankshaft, crankshaft, compressor, refrigeration cycle device, and crankshaft manufacturing method

Abstract

One embodiment of a work-in-progress crankshaft according to the present disclosure comprises: a long shaft part, a coupling shaft part, and a short shaft part that extend in an axial direction about a central axis; a first eccentric shaft part that is located between the long shaft part and the coupling shaft part in the axial direction, is eccentric to the central axis, and extends in the axial direction; and a second eccentric shaft part that is located between the coupling shaft part and the short shaft part in the axial direction, is eccentric to the central axis, and extends in the axial direction. The long shaft part is of larger dimension in the axial direction than the short shaft part. The first eccentric shaft part and the second eccentric shaft part are eccentric on mutually opposite sides to the central axis in between. An outer circumferential surface of the first eccentric shaft part is a cut surface formed by cutting. Residual stress remaining on an outer circumferential surface of the second eccentric shaft part is greater than residual stress remaining on the outer circumferential surface of the first eccentric shaft part.

Description

Work-in-progress of a crankshaft, crankshaft, compressor, refrigeration cycle device, and method for manufacturing a crankshaft

[0001] The present disclosure relates to a work-in-progress of a crankshaft, a crankshaft, a compressor, a refrigeration cycle device, and a method for manufacturing a crankshaft.

[0002] Generally, turning and grinding are performed on the outer peripheral surfaces of respective parts of a crankshaft (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2014-195856

[0004] In such a crankshaft, due to the influence of residual stress on the outer peripheral surfaces of respective parts, there has been a problem that the crankshaft is deformed after grinding, and the amount of core deviation at both ends increases.

[0005] The present disclosure has been made to solve the above-described problems, and one of the objects is to provide a work-in-progress of a crankshaft, a crankshaft, and a method for manufacturing a crankshaft capable of suppressing the amount of core deviation at both ends, as well as a compressor and a refrigeration cycle device including such a crankshaft.

[0006] One aspect of the work-in-progress of a crankshaft according to the present disclosure includes a long shaft portion, a connecting shaft portion, and a short shaft portion that extend in the axial direction about a central axis, a first eccentric shaft portion that is located between the long shaft portion and the connecting shaft portion in the axial direction and is eccentric with respect to the central axis and extends in the axial direction, and a second eccentric shaft portion that is located between the connecting shaft portion and the short shaft portion in the axial direction and is eccentric with respect to the central axis and extends in the axial direction. The long shaft portion has a larger dimension in the axial direction than the short shaft portion. The first eccentric shaft portion and the second eccentric shaft portion are eccentric on opposite sides with respect to the central axis. The outer peripheral surface of the first eccentric shaft portion is a cutting surface formed by cutting. The residual stress remaining on the outer peripheral surface of the second eccentric shaft portion is larger than the residual stress remaining on the outer peripheral surface of the first eccentric shaft portion.

[0007] One embodiment of the crankshaft according to the present disclosure comprises a long shaft portion, a connecting shaft portion, and a short shaft portion extending axially with respect to a central axis; a first eccentric shaft portion located between the long shaft portion and the connecting shaft portion in the axial direction and extending axially eccentrically with respect to the central axis; and a second eccentric shaft portion located between the connecting shaft portion and the short shaft portion in the axial direction and extending axially eccentrically with respect to the central axis, wherein the long shaft portion has a larger axial dimension than the short shaft portion, the first eccentric shaft portion and the second eccentric shaft portion are eccentric to opposite sides of the central axis, and the residual stress remaining on the outer circumferential surface of the second eccentric shaft portion is greater than the residual stress remaining on the outer circumferential surface of the first eccentric shaft portion.

[0008] One embodiment of the compressor according to the present disclosure comprises the above-described crankshaft, a rotating electric machine that rotates the crankshaft about the central axis, a compression mechanism having a first piston mounted on the first eccentric shaft portion, a second piston mounted on the second eccentric shaft portion, a first bearing member that rotatably supports the long shaft portion, and a second bearing member that rotatably supports the short shaft portion, and a compressor casing that houses the rotating electric machine, the crankshaft, and the compression mechanism.

[0009] One embodiment of the refrigeration cycle device according to the present disclosure is a refrigeration cycle device equipped with the above-described compressor, comprising: a circulation path section through which a refrigerant circulates; the compressor for compressing the refrigerant; a heat sink arranged in the path of the circulation path section for extracting heat from the compressed refrigerant; a pressure reducer for reducing the pressure of the refrigerant flowing out of the heat sink; and an evaporator for evaporating the refrigerant flowing out of the pressure reducer.

[0010] One embodiment of a method for manufacturing a crankshaft according to the present disclosure comprises a preliminary step of preparing a work-in-progress crankshaft having a first eccentric shaft portion and a second eccentric shaft portion that are eccentric with respect to a central axis, and a grinding step of grinding the outer circumferential surface of the first eccentric shaft portion and the outer circumferential surface of the second eccentric shaft portion, wherein the work-in-progress has a long shaft portion, a connecting shaft portion and a short shaft portion extending axially with respect to a central axis, the first eccentric shaft portion located between the long shaft portion and the connecting shaft portion in the axial direction, and in the axial direction The workpiece comprises a first eccentric shaft portion located between the connecting shaft portion and the short shaft portion, wherein the long shaft portion has a larger axial dimension than the short shaft portion, the first eccentric shaft portion and the second eccentric shaft portion are eccentric to opposite sides of the central axis, the outer circumferential surface of the first eccentric shaft portion is a machined surface formed by machining, and the residual stress remaining on the outer circumferential surface of the second eccentric shaft portion is greater than the residual stress remaining on the outer circumferential surface of the first eccentric shaft portion.

[0011] According to this disclosure, it is possible to provide a work-in-progress crankshaft, a crankshaft, a method for manufacturing a crankshaft, and a compressor and a refrigeration cycle device equipped with such a crankshaft, which can suppress the amount of misalignment at both ends.

[0012] This is a schematic diagram of a refrigeration cycle device in an embodiment. This is a cross-sectional view of a compressor in an embodiment. This is a side view of a crankshaft in an embodiment. This is a flowchart of the manufacturing process of a crankshaft in an embodiment. This is a schematic diagram showing the second turning process in an embodiment. This is a schematic diagram showing the third turning process in an embodiment. This is a schematic diagram showing the residual stress application process in an embodiment. This is a schematic diagram showing the second grinding process in an embodiment. This is a diagram explaining the principle of crankshaft deformation. This is a schematic diagram showing the third grinding process in an embodiment. This is a schematic diagram showing the deformation state of a crankshaft in an embodiment. This is a schematic diagram showing the deformation state of a crankshaft in a comparative form. This is a flowchart of the residual stress application process in a modified example. This is a schematic diagram showing the residual stress application process in a modified example. This is a side view of a crankshaft in a modified example.

[0013] Embodiments of this disclosure will be described below with reference to the drawings. However, the scope of this disclosure is not limited to the embodiments described below and can be modified at will within the scope of the technical concept of this disclosure. Furthermore, in the following drawings, the scale and number of components in each structure may differ from those in the actual structure in order to make the configurations easier to understand.

[0014] (Refrigeration Cycle Device) Figure 1 is a schematic diagram showing the general configuration of the refrigeration cycle device 200 in this embodiment. The refrigeration cycle device 200 is a device that utilizes a refrigeration cycle in which a refrigerant R circulates. In this embodiment, the refrigeration cycle device 200 is, for example, an air conditioner. In addition, the refrigeration cycle device 200 can be used for various other purposes, such as hot water supply systems and refrigeration systems.

[0015] The refrigeration cycle device 200 includes an outdoor heat exchanger 202, an indoor heat exchanger 204, a pressure reducer 203, a four-way valve 205, and a circulation path section 201. The refrigerant R circulates through the circulation path section 201. The outdoor heat exchanger 202, the indoor heat exchanger 204, the pressure reducer 203, and the four-way valve 205 are arranged in the path of the circulation path section 201.

[0016] The outdoor heat exchanger 202 is located outdoors. The indoor heat exchanger 204 is located indoors. The outdoor heat exchanger 202 and the indoor heat exchanger 204 are heat exchange units that exchange heat with air. The refrigeration cycle device 200 can adjust the temperature of the indoor air by exchanging heat between the refrigerant R flowing through the circulation path 201 and the indoor air in the room where the indoor heat exchanger 204 is located.

[0017] Examples of refrigerants R flowing through the circulation path 201 include fluorine-based refrigerants or hydrocarbon-based refrigerants with low global warming potential (GWP). Examples of refrigerants R include a single refrigerant from among R1234yf, R1234ze, R32, and R290, a mixture of two or more of these, or a mixture of one of these with another refrigerant. Examples of refrigerants R include a mixture containing R1132(E) or a mixture containing R1123. Examples of refrigerants R include a mixture of R516A, R410A, R445A, R444A, R454C, R444B, R454A, R455A, R457A, R459B, R452B, R454B, R447B, R447A, R446A, and R459A.

[0018] In particular, the refrigerant R is preferably a single refrigerant from among R1234yf, R1234ze, R32, and R290, or a mixture of two or more of these, or a mixture of one of these with another refrigerant, or a mixture containing R1132(E), or a mixture containing R1123.

[0019] The four-way valve 205 is installed in the portion of the circulation path 201 that is connected to the discharge side of the compressor 1. The four-way valve 205 can reverse the direction of the refrigerant R flowing through the circulation path 201 by switching a portion of the circulation path 201.

[0020] If the path connected by the four-way valve 205 is the path shown by the solid line on the four-way valve 205 in Figure 1, the refrigerant R flows through the circulation path section 201 in the direction shown by the solid arrow in Figure 1. In this case, the discharge pipe 4 of the compressor 1 is connected to the indoor heat exchanger 204, and the intake muffler 3 of the compressor 1 is connected to the outdoor heat exchanger 202.

[0021] On the other hand, if the path connected by the four-way valve 205 is the path shown by the dashed line on the four-way valve 205 in Figure 1, the refrigerant R flows through the circulation path section 201 in the direction shown by the dashed arrow in Figure 1. In this case, the discharge pipe 4 of the compressor 1 is connected to the outdoor heat exchanger 202, and the intake muffler 3 of the compressor 1 is connected to the indoor heat exchanger 204.

[0022] The refrigeration cycle device 200 is capable of performing both cooling operation, which cools the indoor air using the indoor heat exchanger 204, and heating operation, which heats the indoor air using the indoor heat exchanger 204.

[0023] When the refrigeration cycle unit 200 performs cooling operation, the refrigerant R flowing through the circulation path 201 flows in the direction indicated by the dashed arrow in Figure 1. In other words, when the refrigeration cycle unit 200 performs cooling operation, the refrigerant R flowing through the circulation path 201 circulates by passing through the compressor 1, the outdoor heat exchanger 202, the pressure reducer 203, and the indoor heat exchanger 204 in that order before returning to the compressor 1. In cooling operation, the outdoor heat exchanger 202 functions as a heat radiator, and the indoor heat exchanger 204 functions as an evaporator.

[0024] On the other hand, when the refrigeration cycle unit 200 performs heating operation, the refrigerant R flowing through the circulation path 201 flows in the direction shown by the solid line in Figure 1. In other words, when the refrigeration cycle unit 200 performs heating operation, the refrigerant R flowing through the circulation path 201 circulates by passing through the compressor 1, the indoor heat exchanger 204, the pressure reducer 203, and the outdoor heat exchanger 202 in that order, and returning to the compressor 1. In heating operation, the outdoor heat exchanger 202 functions as an evaporator, and the indoor heat exchanger 204 functions as a heat radiator.

[0025] (Compressor) Next, the compressor 1 of this embodiment will be described in more detail. Figure 2 is a cross-sectional view of the compressor 1 of this embodiment. The compressor 1 according to this embodiment is a rolling piston type compressor.

[0026] The compressor 1 comprises a compressor casing 10, a first suction pipe 2A, a second suction pipe 2B, an suction muffler 3, a compression mechanism 20, a rotating electric motor 30, a crankshaft 40, and a discharge pipe 4.

[0027] The compressor casing 10 constitutes the outer casing of the compressor 1. The compressor casing 10 houses the compression mechanism 20, the rotating electric machine 30, and the crankshaft 40, etc. Inside the compressor casing 10, refrigeration oil 6, which is a lubricating oil, is stored. The refrigeration oil 6 is stored at the bottom of the compressor casing 10. As the refrigeration oil 6, for example, mineral oil-based, alkylbenzene-based, polyalkylene glycol-based, polyvinyl ether-based, and polyol ester-based lubricating oils can be used.

[0028] The compressor casing 10 is connected to the discharge piping 4, the first suction pipe 2A, and the second suction pipe 2B. The stator 32 of the rotating electric machine 30 and the compression mechanism 20 are attached to the inner circumferential surface of the compressor casing 10. The compression mechanism 20 is located below the stator 32.

[0029] The discharge pipe 4 is provided to discharge the high-temperature, high-pressure refrigerant inside the compressor casing 10 to the outside of the compressor casing 10. The discharge pipe 4 is connected to the ceiling portion of the compressor casing 10. The first suction pipe 2A and the second suction pipe 2B are provided to supply refrigerant to the inside of the compressor casing 10. The first suction pipe 2A and the second suction pipe 2B are connected to the outer circumferential surface of the compressor casing 10. One end of the first suction pipe 2A opens into the internal space of the first cylinder 21A of the compression mechanism 20 (described later), and the other end opens into the internal space of the intake muffler 3. One end of the second suction pipe 2B opens into the internal space of the second cylinder 21B of the compression mechanism 20 (described later), and the other end opens into the internal space of the intake muffler 3.

[0030] The intake muffler 3 functions as a muffler that reduces refrigerant noise and other sounds generated when refrigerant flows into the compressor 1. The intake muffler 3 also functions as an accumulator capable of storing liquid refrigerant. The refrigerant flowing into the intake muffler 3 is supplied to the compression mechanism 20 via the first intake pipe 2A and the second intake pipe 2B.

[0031] The compression mechanism 20 is connected to the first suction pipe 2A and the second suction pipe 2B inside the compressor casing 10. The compression mechanism 20 is also connected to the crankshaft 40. The compression mechanism 20 compresses the refrigerant supplied from the first suction pipe 2A and the second suction pipe 2B using the power of the rotating electric machine 30 transmitted by the crankshaft 40. The refrigerant compressed by the compression mechanism 20 is released inside the compressor casing 10.

[0032] The compression mechanism 20 includes a first cylinder 21A, a second cylinder 21B, a first bearing member 24A, a second bearing member 24B, a partition plate 25, a first muffler 23A, and a second muffler 23B.

[0033] The first cylinder 21A compresses the refrigerant supplied from the first suction pipe 2A. The second cylinder 21B is located below the first cylinder 21A. The second cylinder 21B compresses the refrigerant supplied from the second suction pipe 2B.

[0034] The first cylinder 21A is provided with a first piston 22A that rotates slidably within the first cylinder 21A. The first piston 22A is connected to the first eccentric shaft portion 51 of the crankshaft 40. The first eccentric shaft portion 51 is eccentric with respect to the central axis O of the crankshaft 40. Therefore, the first piston 22A rotates eccentrically with respect to the central axis O within the first cylinder 21A.

[0035] The second cylinder 21B is provided with a second piston 22B that rotates slidably within the second cylinder 21B. The second piston 22B is connected to the second eccentric shaft portion 52 of the crankshaft 40. The second eccentric shaft portion 52 is eccentric with respect to the central axis O of the crankshaft 40. Therefore, the first piston 22A rotates eccentrically with respect to the central axis O within the first cylinder 21A.

[0036] The phase difference between the first axis J1, located at the center of the first eccentric shaft portion 51 of the crankshaft 40, and the second axis J2, located at the center of the second eccentric shaft portion 52, is 180° with respect to the central axis O. Therefore, the first piston 22A and the second piston 22B rotate with a phase difference of 180° at all times.

[0037] As the first piston 22A and the second piston 22B rotate eccentrically, refrigerant is drawn into the compressor 1. Specifically, as the first piston 22A and the second piston 22B rotate eccentrically, low-pressure refrigerant from outside the compressor 1 flows into the intake muffler 3. Of the low-pressure refrigerant that has flowed into the intake muffler 3, the low-pressure gaseous refrigerant flows into the compression mechanism 20 via the first intake pipe 2A and the second intake pipe 2B. A portion of the gaseous refrigerant that has flowed into the compression mechanism 20 is compressed by the first piston 22A and the second piston 22B to become high-temperature, high-pressure gaseous refrigerant. This high-temperature, high-pressure gaseous refrigerant is released into the space inside the compressor casing 10. This high-temperature, high-pressure gaseous refrigerant released into the space inside the compressor casing 10 moves to the upper part of the space inside the compressor casing 10 through gaps such as the rotating electric machine 30, and is discharged from the discharge pipe 4.

[0038] The first bearing member 24A is provided on the upper side of the first cylinder 21A. The first bearing member 24A rotatably supports the crankshaft 40. In this embodiment, the first bearing member 24A is a so-called sliding bearing. The first bearing member 24A closes the upper opening of the first cylinder 21A. The first bearing member 24A is provided with a valve (not shown) that releases the refrigerant compressed by the first cylinder 21A and the first piston 22A. When this valve opens, the space formed by the first cylinder 21A and the first piston 22A communicates with the space inside the first muffler 23A, which will be described later.

[0039] The second bearing member 24B is provided below the second cylinder 21B. The second bearing member 24B rotatably supports the crankshaft 40. In this embodiment, the second bearing member 24B is a so-called sliding bearing. The second bearing member 24B closes the opening on the lower side of the second cylinder 21B. The second bearing member 24B is provided with a valve (not shown) that releases the refrigerant compressed by the second cylinder 21B and the second piston 22B. When this valve opens, the space formed by the second cylinder 21B and the second piston 22B communicates with the space inside the second muffler 23B, which will be described later.

[0040] The partition plate 25 is provided between the first cylinder 21A and the second cylinder 21B. The partition plate 25 closes the lower opening of the first cylinder 21A. The partition plate 25 also closes the upper opening of the second cylinder 21B. In other words, the partition plate 25 separates the space formed by the first cylinder 21A and the first piston 22A from the space formed by the second cylinder 21B and the second piston 22B.

[0041] The first muffler 23A is fixed to the upper surface of the first bearing member 24A. Between the first muffler 23A and the first bearing member 24A, a space (the space inside the first cylinder 21A) is formed through which the refrigerant compressed by the first cylinder 21A and the first piston 22A is discharged. The first muffler 23A is provided with a refrigerant discharge section (not shown). As a result, the refrigerant compressed by the first cylinder 21A and the first piston 22A is discharged into the space inside the first muffler 23A, and then released from the refrigerant discharge section into the interior of the compressor casing 10.

[0042] The second muffler 23B is fixed to the lower surface of the second bearing member 24B. Between the second muffler 23B and the second bearing member 24B, a space (the space inside the second muffler 23B) is formed through which the refrigerant compressed by the second cylinder 21B and the second piston 22B is discharged. The space inside the second muffler 23B is connected to the space inside the first muffler 23A via a refrigerant flow path (not shown). After the refrigerant compressed by the second cylinder 21B and the second piston 22B is discharged into the space inside the second muffler 23B, it flows into the space inside the first muffler 23A via the refrigerant flow path. The refrigerant that has flowed into the first muffler 23A is then released into the interior of the compressor casing 10 from the refrigerant discharge section of the first muffler 23A.

[0043] The rotating electric machine 30 has a rotor 31 and a stator 32. The rotor has permanent magnets. The rotor 31 is connected to the crankshaft 40. The stator 32 has an iron core and multiple phase windings mounted on the iron core. By supplying alternating current to each phase winding, a rotating magnetic field is formed in the stator 32. This rotating magnetic field acts on the permanent magnets of the rotor 31, causing the rotor 31 to rotate.

[0044] (Crankshaft) The crankshaft 40 is connected to the rotating electric machine 30. The crankshaft 40 rotates about the central axis O together with the rotor 31. The crankshaft 40 transmits the power of the rotating electric machine 30 to the compression mechanism 20.

[0045] The crankshaft 40 includes a shaft body 50, a first eccentric shaft portion 51 and a second eccentric shaft portion 52 that project radially outward from the outer peripheral surface of the shaft body 50. The first eccentric shaft portion 51 and the second eccentric shaft portion 52 project radially outward from the outer peripheral surface of the shaft body 50.

[0046] The shaft body 50 is cylindrical and extends in the vertical direction about the central axis O. The shaft body 50 is provided with an oil supply recess 42, a first oil supply port 43, and a second oil supply port 44. The oil supply recess 42 extends in the vertical direction of the shaft body 50. The oil supply recess 42 has a suction port 41 that opens to the lower end surface of the shaft body 50. A centrifugal pump portion 45 is provided inside the oil supply recess 42. The centrifugal pump portion 45 has a conventionally known structure. Although illustration of the detailed structure of the centrifugal pump portion 45 is omitted, the centrifugal pump portion 45 is formed, for example, by twisting a plate-like member in a spiral shape. The centrifugal pump portion 45 sucks up the refrigerant oil 6 stored at the bottom of the compressor housing 10 by the centrifugal force generated by the rotation of the crankshaft 40.

[0047] The first oil supply port 43 and the second oil supply port 44 are through holes that extend radially outward from the oil supply recess 42. The first oil supply port 43 and the second oil supply port 44 are arranged in the vertical direction. The first oil supply port 43 is located above the second oil supply port 44. The opening of the first oil supply port 43 faces the inner peripheral surface of the first bearing member 24A. The first oil supply port 43 supplies the refrigerant oil 6 sucked up by the centrifugal pump portion 45 to the sliding portion between the first bearing member 24A and the crankshaft 40. The opening of the second oil supply port 44 faces the inner peripheral surface of the second bearing member 24B. The second oil supply port 44 supplies the refrigerant oil 6 sucked up by the centrifugal pump portion 45 to the sliding portion between the second bearing member 24B and the crankshaft 40.

[0048] The shaft body 50 has a long shaft portion 55, a connecting shaft portion 53, and a short shaft portion 54. The long shaft portion 55, the connecting shaft portion 53, and the short shaft portion 54 are arranged in this order from the upper side to the lower side. The long shaft portion 55, the connecting shaft portion 53, and the short shaft portion 54 are each columnar and extend in the axial direction around a central axis.

[0049] The long shaft portion 55 extends upward from the first eccentric shaft portion 51. A rotor 31 is fixed to an upper region of the outer peripheral surface of the long shaft portion 55. Also, a lower region of the outer peripheral surface of the long shaft portion 55 is rotatably supported by the first bearing member 24A. The long shaft portion 55 has a larger axial dimension than the short shaft portion 54 and the connecting shaft portion 53.

[0050] The short shaft portion 54 extends downward from the second eccentric shaft portion 52. The outer peripheral surface of the short shaft portion 54 is rotatably supported by the second bearing member 24B. The short shaft portion 54 has a larger axial dimension than the connecting shaft portion 53.

[0051] The connecting shaft portion 53 is located between the first eccentric shaft portion 51 and the second eccentric shaft portion. The outer peripheral surface of the connecting shaft portion 53 is surrounded by the partition plate 25 from the radially outer side.

[0052] FIG. 3 is a side view of the crankshaft 40. The diameters of the long shaft portion 55, the connecting shaft portion 53, and the short shaft portion 54 are substantially equal. As shown in FIG. 3, slight height steps may be provided on the long shaft portion 55 and the short shaft portion 54, respectively.

[0053] The outer peripheral surface of the connecting shaft portion 53 is a cut surface formed by cutting. In this specification, the "cut surface" means a surface formed by cutting and having cutting marks as traces of the cutting edge of a tool remaining on the surface. Also, in this specification, the "outer peripheral surface" means a surface facing the radially outer side.

[0054] Also, the outer peripheral surfaces of the long shaft portion 55 and the short shaft portion 54 are grinding surfaces formed by grinding. The long shaft portion 55 and the short shaft portion 54 have their surface roughness adjusted by performing grinding after cutting. Thereby, the sliding resistance between the long shaft portion 55 and the first bearing member 24A and the sliding resistance between the short shaft portion 54 and the second bearing member 24B are reduced.

[0055] The first eccentric shaft portion 51 is located in the axial direction between the long shaft portion 55 and the connecting shaft portion 53. The first eccentric shaft portion 51 is cylindrical in shape with a first axis J1 that extends parallel to the central axis O as its center. That is, the first eccentric shaft portion 51 extends axially, eccentric to the central axis O. The diameter of the first eccentric shaft portion 51 is larger than the diameters of the long shaft portion 55, the connecting shaft portion 53, and the short shaft portion 54.

[0056] The second eccentric shaft portion 52 is located in the axial direction between the short shaft portion 54 and the connecting shaft portion 53. The second eccentric shaft portion 52 is cylindrical in shape with a second axis J2 that extends parallel to the central axis O as its center. That is, the second eccentric shaft portion 52 extends axially, eccentric to the central axis O. The diameter of the second eccentric shaft portion 52 is larger than the diameters of the long shaft portion 55, the connecting shaft portion 53, and the short shaft portion 54.

[0057] In this embodiment, the phase of the first axis J1 with respect to the central axis O and the phase of the second axis J2 with respect to the central axis O are offset by 180° from each other. That is, the first eccentric shaft portion 51 and the second eccentric shaft portion 52 are eccentric to opposite sides of the central axis O. According to this embodiment, the center of gravity of the crankshaft 40 can be positioned on the central axis O, and the crankshaft 40 can be rotated in a balanced manner around the central axis O. This makes it possible to suppress vibrations of the compressor 1 during operation.

[0058] In this embodiment, the distance d1 between the first axis J1 and the central axis O is equal to the distance d2 between the second axis J2 and the central axis O. However, the distance d1 between the first axis J1 and the central axis O and the distance d2 between the second axis J2 and the central axis O may be different from each other.

[0059] In this embodiment, the diameter D1 of the first eccentric shaft portion 51 and the diameter D2 of the second eccentric shaft portion 52 are equal to each other. However, the diameter D1 of the first eccentric shaft portion 51 and the diameter D2 of the second eccentric shaft portion 52 may be different to each other.

[0060] In this embodiment, the width dimension W1 of the first eccentric shaft portion 51 and the width dimension W2 of the second eccentric shaft portion 52 are equal to each other. However, the width dimension W1 of the first eccentric shaft portion 51 and the width dimension W2 of the second eccentric shaft portion 52 may be different to each other. In this specification, the width dimension of the eccentric shaft portion refers to the axial dimension of the eccentric shaft portion.

[0061] As in this embodiment, when the distances d1 and d2, the diameters D1 and D2, and the width dimensions W1 and W2 are all equal, it becomes easier to position the center of gravity of the crankshaft 40 on the central axis O, making it possible to rotate the crankshaft 40 in a balanced manner.

[0062] The outer circumferential surfaces of the first eccentric shaft portion 51 and the second eccentric shaft portion 52 are ground surfaces formed by grinding. The sides facing both axial directions are machined surfaces formed by cutting. In this embodiment, the first eccentric shaft portion 51 and the second eccentric shaft portion 52 are formed by cutting both the outer circumferential and side surfaces, and then grinding only the outer circumferential surface. Furthermore, the outer circumferential surface of the second eccentric shaft portion 52 is burnished after cutting but before grinding. The manufacturing method of the crankshaft 40 will be described in more detail later.

[0063] (Manufacturing Method for Crankshafts) Figure 4 is a flowchart showing the manufacturing process of a crankshaft 40. As shown in Figure 4, the manufacturing method for a crankshaft 40 includes a molding process S10, a cutting process S20, a residual stress application process (burnishing process) S30, and a grinding process S40.

[0064] In the manufacturing process of the crankshaft 40, the molding process S10, the cutting process S20, and the residual stress application process S30 constitute a preliminary process SA. That is, the manufacturing method of the crankshaft 40 includes a preliminary process SA and a grinding process S40. Furthermore, the preliminary process SA includes the molding process S10, the cutting process S20, and the residual stress application process S30.

[0065] The preliminary process SA and the grinding process S40 are carried out in different factories, for example. In the following explanation, the intermediate product of the crankshaft 40 manufactured through the preliminary process SA is referred to as work-in-progress (crankshaft work-in-progress) 40A. The factory that performs the preliminary process SA manufactures the work-in-progress 40A of the crankshaft 40. The factory that performs the grinding process S40 receives the work-in-progress 40A manufactured in the preliminary process SA and performs the grinding process S40 to manufacture the finished crankshaft 40.

[0066] The molding process S10 is a process in which the rough outer shape of the crankshaft 40 is formed using a mold. In the molding process S10, the crankshaft 40 is formed to dimensions that leave room for subsequent processes such as cutting and grinding. The molding process S10 is, for example, a forging process or a casting process.

[0067] The cutting process S20 is a process in which the crankshaft 40 formed in the molding process S10 is cut using tools such as turning inserts and drills. The cutting process S20 comprises a first turning process S21, a drilling process S22, a second turning process S23, and a third turning process S24.

[0068] The first turning step S21 is a process of machining the outer circumferential surfaces of the long shaft portion 55, the connecting shaft portion 53, and the short shaft portion 54 by turning. In the first turning step S21, the crankshaft 40 is rotated with the central axis O as the center of rotation to form the long shaft portion 55, the connecting shaft portion 53, the short shaft portion 54, and the lubrication recess 42. After going through the first turning step S21, the outer circumferential surfaces of the long shaft portion 55, the connecting shaft portion 53, and the short shaft portion 54 become machined surfaces.

[0069] The drilling process S22 is a process in which the oil supply recess 42, the first oil supply port 43, and the second oil supply port 44 shown in Figure 2 are formed on the crankshaft 40. In the drilling process S22, first, a hole is drilled into the end face of the short shaft portion 54 using a drill to form the oil supply recess 42. Next, holes are drilled into the outer circumferential surfaces of the long shaft portion 55 and the short shaft portion 54 using a drill to form the first oil supply port 43 and the second oil supply port 44.

[0070] Figure 5 is a schematic diagram showing the second turning process S23. The second turning process S23 is a process in which the side surface and outer circumferential surface of the first eccentric shaft portion 51 are machined by turning.

[0071] In the second turning step S23, first, the crankshaft 40 is chucked using the first eccentric collet 9A. The first eccentric collet 9A supports the long shaft portion 55 with the first axis J1 of the first eccentric shaft portion 51 as the center of rotation. Next, the crankshaft 40 is rotated with the first axis J1 as the center of rotation, and the turning chip 8 processes the side surface and outer circumferential surface of the first eccentric shaft portion 51. After going through the second turning step S23, the side surface and outer circumferential surface of the first eccentric shaft portion 51 become machined surfaces.

[0072] Figure 6 is a schematic diagram showing the third turning process S24. The third turning process S24 is a process in which the side surface and outer circumferential surface of the second eccentric shaft portion 52 are machined by turning.

[0073] In the third turning step S24, first, the crankshaft 40 is chucked using the second eccentric collet 9B. The second eccentric collet 9B supports the long shaft portion 55 with the second axis J2 of the second eccentric shaft portion 52 as the center of rotation. Next, the crankshaft 40 is rotated with the second axis J2 as the center of rotation, and the turning chip 8 processes the side surface and outer circumferential surface of the second eccentric shaft portion 52. After going through the second turning step S23, the side surface and outer circumferential surface of the second eccentric shaft portion 52 become machined surfaces.

[0074] Figure 7 is a schematic diagram showing the residual stress application process S30 of this embodiment. The residual stress application process S30 is a process of applying residual stress to the outer circumferential surface of the second eccentric shaft portion 52. The residual stress application process S30 in this embodiment is a burnishing process. By going through the residual stress application process S30, the work-in-progress 40A is manufactured.

[0075] In the residual stress application step S30, the crankshaft 40 is rotated with the second axis J2 as the center of rotation, while the burnishing tool 7 is pressed against the outer circumferential surface of the second eccentric shaft portion 52. As a result, compressive stress is applied to the outer circumferential surface of the second eccentric shaft portion 52, and the outer circumferential surface of the second eccentric shaft portion 52 becomes a burnishing surface with increased hardness.

[0076] In this embodiment, the residual stress application step S30 is performed immediately after the third turning step S24. Therefore, the second eccentric collet 9B used in the third turning step S24 can be used as is without being replaced. According to this embodiment, the residual stress application step S30 can be simplified.

[0077] In the residual stress application process S30, burnishing is not performed on the first eccentric shaft portion 51, and therefore no residual stress is applied to it. As a result, the outer circumferential surface of the first eccentric shaft portion 51 of the work-in-progress 40A remains a machined surface. Furthermore, only the residual stress applied in the second turning process S23 remains on the outer circumferential surface of the first eccentric shaft portion 51. In contrast, the outer circumferential surface of the second eccentric shaft portion 52 retains the residual stress applied in the residual stress application process S30 in addition to the residual stress applied in the third turning process S24. As a result, in the work-in-progress 40A, the residual stress remaining on the outer circumferential surface of the second eccentric shaft portion 52 is greater than the residual stress remaining on the outer circumferential surface of the first eccentric shaft portion.

[0078] The residual stress on the outer surfaces of the first eccentric shaft portion 51 and the second eccentric shaft portion 52 can be measured using a portable X-ray residual stress measuring device (model: μ-X360S) manufactured by PulseTech Industries Co., Ltd., under the following conditions: ferrite (35 deg) and single incidence method (X-ray measurement). The hardness of the outer surfaces of the first eccentric shaft portion 51 and the second eccentric shaft portion 52 can be measured by the Vickers hardness test specified in JIS Z 2244:2009.

[0079] As shown in Figure 4, the grinding process S40 comprises a first grinding process S41, a second grinding process S42, and a third grinding process S43. The grinding process S40 is a process in which grinding is performed on the work-in-progress 40A.

[0080] The first grinding step S41 is a process of grinding the outer surfaces of the long shaft portion 55 and the short shaft portion 54. In the first grinding step S41, a cylindrical grinding method or a centerless grinding method is employed. After going through the first grinding step S41, the outer surfaces of the long shaft portion 55 and the short shaft portion 54 become ground surfaces.

[0081] Figure 8 is a schematic diagram showing the second grinding step S42. Note that Figure 8 exaggerates the deformation of the crankshaft 40 that occurs during the second grinding step S42. In the second grinding step S42, first, the long shaft portion 55 is supported with the central axis O as the center of rotation. Next, the crankshaft 40 is rotated with the central axis O as the center of rotation. As a result, the first eccentric shaft portion 51 rotates eccentrically with respect to the central axis O. Furthermore, the grinding wheel 61 is pressed against the outer circumferential surface of the first eccentric shaft portion 51 and moved radially in synchronization with the eccentric rotation of the first eccentric shaft portion 51, thereby grinding the outer circumferential surface of the first eccentric shaft portion 51. After going through the second grinding step S42, the outer circumferential surface of the first eccentric shaft portion 51 becomes a ground surface.

[0082] Before the second grinding process S42, the outer circumferential surface of the first eccentric shaft portion 51 retains compressive residual stress caused by the second turning process S23. In the second grinding process S42, grinding the outer circumferential surface of the first eccentric shaft portion 51 disrupts the balance of residual stress, causing deformation in the crankshaft 40. After the second grinding process S42, the crankshaft 40 bends from the first eccentric shaft portion 51 in the direction from the first axis J1 toward the central axis O.

[0083] The bending angle of the crankshaft 40, starting from the first eccentric shaft portion 51, is defined as the first deformation angle θ1. The length from the axial center of the first eccentric shaft portion 51 to the end face 54f of the short shaft portion 54 is defined as the first dimension h1. After the second grinding process S42, the center of the end face 54f of the short shaft portion 54 is displaced by a first misalignment amount A1 in the direction from the first axis J1 toward the central axis O relative to the central axis O. That is, in the crankshaft 40 after the second grinding process S42, the short shaft portion 54 is misaligned with respect to the long shaft portion 55 by a first misalignment amount A1. The first misalignment amount A1 is expressed as the product of the sine of the first deformation angle θ1 and the first dimension h1 (A1 = h1 × sinθ1).

[0084] Figure 9 illustrates the principle of deformation of the crankshaft 40. A V-shaped microcrack 67 is formed on the surface of the ground surface after grinding. If compressive residual stress remains on such a ground surface, compressive forces 68 act from both sides toward the V-shaped microcrack 67. As a result, the outer circumferential surface of the first eccentric shaft portion 51 deforms slightly in the direction 66 that closes the V-shaped microcrack. This deformation occurs around the entire circumference of the outer circumferential surface of the first eccentric shaft portion 51. As shown in Figure 8, the long shaft portion 55 and the connecting shaft portion 53 connected to the first eccentric shaft portion 51 extend axially around the central axis O, which is positioned offset from the first eccentric shaft portion 51. Therefore, the long shaft portion 55 and the connecting shaft portion 53 are affected by the minute deformation and bend toward the direction toward the central axis O from the first axis J1.

[0085] Figure 10 is a schematic diagram showing the third grinding step S43. Figure 9 illustrates the deformation of the crankshaft 40 caused by the third grinding step S43. The third grinding step S43 is performed continuously without removing the clamp from the second grinding step S42. That is, in the third grinding step S43, the crankshaft 40 is rotated with the central axis O as the center of rotation, causing the second eccentric shaft portion 52 to rotate eccentrically with respect to the central axis O. Next, the grinding wheel 61 is pressed against the outer circumferential surface of the second eccentric shaft portion 52 and moved radially in synchronization with the eccentric rotation of the second eccentric shaft portion 52, thereby grinding the outer circumferential surface of the second eccentric shaft portion 52. After going through the third grinding step S43, the outer circumferential surface of the second eccentric shaft portion 52 becomes a ground surface.

[0086] Before the third grinding step S43, the outer circumferential surface of the second eccentric shaft portion 52 retains compressive residual stress caused by the third turning step S24 and the residual stress application step S30. Similar to the second grinding step S42, the third grinding step S43 causes deformation of the crankshaft 40 due to the disruption of the residual stress balance by grinding the outer circumferential surface of the second eccentric shaft portion 52. After the third grinding step S43, the crankshaft 40 bends from the second eccentric shaft portion 52 in the direction from the first axis J1 toward the central axis O. In other words, in the third grinding step S43, the crankshaft 40 bends in the opposite direction to that in the second grinding step S42. The principle by which deformation occurs in the crankshaft 40 in the third grinding step S43 is the same as the principle by which deformation occurs in the crankshaft 40 in the second grinding step S42.

[0087] The bending angle of the crankshaft 40 starting from the second eccentric shaft portion 52 is defined as the second deformation angle θ2. The length from the axial center of the second eccentric shaft portion 52 to the end face 54f of the short shaft portion 54 is defined as the second dimension h2. After the third grinding process S43, the center of the end face 54f of the short shaft portion 54 is displaced by a second misalignment amount A2 in the direction from the second axis J2 toward the central axis O relative to the central axis O. That is, in the crankshaft 40 after the third grinding process S43, the short shaft portion 54 is misaligned with respect to the connecting shaft portion 53 by a second misalignment amount A2. The second misalignment amount A2 is expressed as the product of the sine of the second deformation angle θ2 and the second dimension h2 (A2 = h2 × sinθ2).

[0088] Figure 11 is a schematic diagram showing the deformation state of the crankshaft 40 in this embodiment. On the other hand, Figure 12 is a schematic diagram showing the deformation state of the crankshaft 40P in a comparative form. Note that the amount of deformation of the crankshafts 40 and 40P is exaggerated in Figures 11 and 12.

[0089] The comparative crankshaft 40P shown in Figure 12 differs from the crankshaft 40 of this embodiment in that it does not undergo the residual stress application process S30 during manufacturing. In the comparative crankshaft 40P, the outer circumferential surfaces of both the first eccentric shaft portion 51 and the second eccentric shaft portion 52 are machined surfaces. Furthermore, in the comparative crankshaft 40P, residual stress remains on the outer circumferential surface of the first eccentric shaft portion 51 due to the second turning process S23, and residual stress remains on the outer circumferential surface of the second eccentric shaft portion 52 due to the third turning process S24. Therefore, in the comparative crankshaft 40P, the residual stress remaining on the outer circumferential surface of the first eccentric shaft portion 51 and the residual stress remaining on the outer circumferential surface of the second eccentric shaft portion 52 are approximately equal to each other. Consequently, the first deformation angle θ1 and the second deformation angle θ2 in the comparative crankshaft 40P are approximately equal to each other. Therefore, in the comparative crankshaft 40P, the long shaft portion 55 and the short shaft portion 54 extend approximately parallel to each other.

[0090] As shown in this comparative form, when the first deformation angle θ1 and the second deformation angle θ2 are equal to each other (θ1 = θ2), the amount of misalignment (A1 - A2) of the minor axis portion 54 relative to the major axis portion 55 is expressed by the following formula: A1 - A2 = (h1 - h2)sinθ1 (comparative form) The sine of the first deformation angle and the difference between the first dimension h1 and the second dimension h2 are always positive constants. Therefore, in the crankshaft 40P of the comparative form, it is difficult to bring the amount of misalignment (A1 - A2) close to 0.

[0091] In the crankshaft 40 of this embodiment shown in Figure 11, the second eccentric shaft portion 52 is subjected to residual stress caused by the second turning process S23, as well as residual stress caused by the residual stress application process S30. Therefore, the residual stress on the outer surface of the second eccentric shaft portion 52 is greater than the residual stress on the outer surface of the first eccentric shaft portion 51. As a result, in the crankshaft 40 of this embodiment, the second deformation angle θ2 is greater than the first deformation angle θ1.

[0092] In this embodiment, the amount of misalignment (A1-A2) of the minor axis portion 54 relative to the major axis portion 55 is expressed by the following formula: A1-A2 = {h1 × sinθ1} - {h2 × sinθ2} (Embodiment) In this embodiment, the first dimension h1 is always greater than the second dimension h2. Also, the sine of the first deformation angle θ1 is smaller than the sine of the second deformation angle θ2. Therefore, by appropriately setting the first deformation angle θ1 and the second deformation angle θ2, the first and second terms on the right side of the above formula can be made equal, and the amount of misalignment (A1-A2) can be brought closer to 0. In other words, according to this embodiment, deformation starting from the first eccentric shaft portion 51 can be canceled by deformation by the second eccentric shaft portion 52, and the amount of misalignment (A1-A2) of the minor axis portion 54 relative to the major axis portion 55 can be reduced.

[0093] According to this embodiment, by reducing the amount of misalignment between the short shaft portion 54 and the long shaft portion 55, the coaxiality of both ends of the crankshaft 40 can be increased. As a result, the crankshaft 40 can be stably supported by the first bearing member 24A and the second bearing member 24B, making it possible to reduce vibrations of the compressor 1 while increasing the driving efficiency of the compressor 1.

[0094] The residual stress remaining on the outer circumferential surfaces of the first eccentric shaft portion 51 and the second eccentric shaft portion 52 gradually decreases as the depth from the outer circumferential surface increases. In this embodiment, residual stress remains on the outer circumferential surfaces of the first eccentric shaft portion 51 and the second eccentric shaft portion 52 even after grinding in the grinding process S40. Furthermore, even after grinding in the grinding process S40, the residual stress remaining on the outer circumferential surface of the second eccentric shaft portion 52 is greater than the residual stress remaining on the outer circumferential surface of the first eccentric shaft portion 51 due to the effect of the residual stress imparting process S30.

[0095] (Summary of Embodiments) The work-in-progress 40A of the crankshaft 40 of this embodiment comprises a long shaft portion 55, a connecting shaft portion 53, a short shaft portion 54, a first eccentric shaft portion 51, and a second eccentric shaft portion 52. The long shaft portion 55, the connecting shaft portion 53, and the short shaft portion 54 extend axially with respect to the central axis O. The first eccentric shaft portion 51 is located between the long shaft portion 55 and the connecting shaft portion 53 in the axial direction. The first eccentric shaft portion 51 extends axially, eccentric with respect to the central axis O. The second eccentric shaft portion 52 is located between the connecting shaft portion 53 and the short shaft portion 54 in the axial direction. The second eccentric shaft portion 52 extends axially, eccentric with respect to the central axis O. The long shaft portion 55 has a larger axial dimension than the short shaft portion 54. The first eccentric shaft portion 51 and the second eccentric shaft portion 52 are eccentric to opposite sides of the central axis O. The outer circumferential surface of the first eccentric shaft portion 51 is a machined surface formed by machining. The residual stress remaining on the outer circumferential surface of the second eccentric shaft portion 52 is greater than the residual stress remaining on the outer circumferential surface of the first eccentric shaft portion 51.

[0096] The outer circumferential surfaces of the first eccentric shaft portion 51 and the second eccentric shaft portion 52 of the work-in-progress 40A retain residual compressive stress applied during machining such as cutting. Therefore, when finishing processes such as grinding are performed on the outer circumferential surfaces of the first eccentric shaft portion 51 and the second eccentric shaft portion 52 of the work-in-progress 40A, the crankshaft 40 deforms in the opposite direction of eccentricity, starting from the first eccentric shaft portion 51 and the second eccentric shaft portion 52. According to the above configuration, the first eccentric shaft portion 51 and the second eccentric shaft portion 52 are eccentric to opposite sides of the central axis O. Therefore, when finishing processes are performed, the bending direction starting from the first eccentric shaft portion 51 and the bending direction starting from the second eccentric shaft portion 52 can be made opposite, and the amount of misalignment at both ends can be reduced. Furthermore, according to the above configuration, the outer circumferential surface of the second eccentric shaft portion 52 has a greater residual stress than the outer circumferential surface of the first eccentric shaft portion 51. Therefore, the second deformation angle θ2 originating from the second eccentric shaft portion 52 can be made larger than the first deformation angle θ1 originating from the first eccentric shaft portion 51. This further reduces the amount of misalignment at both ends. By reducing the amount of misalignment at both ends, vibration of the compressor 1 can be reduced and driving efficiency can be increased. Furthermore, with this configuration, the process for correcting the amount of misalignment in the manufacturing process of the crankshaft 40 becomes unnecessary, which can improve productivity and reduce equipment investment costs.

[0097] In the work-in-progress 40A described above, the hardness of the outer surface of the second eccentric shaft portion 52 is higher than that of the outer surface of the first eccentric shaft portion 51. With this configuration, the hardness of the second eccentric shaft portion 52 is increased during the manufacturing of the work-in-progress 40A by burnishing or shot peening. Consequently, the residual stress remaining on the outer surface of the second eccentric shaft portion 52 becomes significantly greater than the residual stress remaining on the outer surface of the first eccentric shaft portion 51. As a result, the amount of misalignment at both ends can be reduced even when performing finishing processes such as grinding.

[0098] The finished crankshaft 40 of this embodiment comprises a long shaft portion 55, a connecting shaft portion 53, a short shaft portion 54, a first eccentric shaft portion 51, and a second eccentric shaft portion 52. The long shaft portion 55, the connecting shaft portion 53, and the short shaft portion 54 extend axially with respect to the central axis O. The first eccentric shaft portion 51 is located between the long shaft portion 55 and the connecting shaft portion 53 in the axial direction. The first eccentric shaft portion 51 extends axially, eccentric with respect to the central axis O. The second eccentric shaft portion 52 is located between the connecting shaft portion 53 and the short shaft portion 54 in the axial direction. The second eccentric shaft portion 52 extends axially, eccentric with respect to the central axis O. The long shaft portion 55 has a larger axial dimension than the short shaft portion 54. The first eccentric shaft portion 51 and the second eccentric shaft portion 52 are eccentric to opposite sides of the central axis O. The residual stress remaining on the outer surface of the second eccentric shaft portion 52 is greater than the residual stress remaining on the outer surface of the first eccentric shaft portion 51. With this configuration, the outer surface of the second eccentric shaft portion 52 is subjected to a greater residual stress than the outer surface of the first eccentric shaft portion 51. Therefore, when finishing processes such as grinding are performed in the manufacturing process of the finished crankshaft 40, the amount of misalignment at both ends is reduced.

[0099] The compressor 1 of this embodiment comprises the crankshaft 40, the rotating electric machine 30, the compression mechanism 20, and the compressor casing 10. The rotating electric machine 30 rotates the crankshaft 40 about the central axis O. The compression mechanism 20 has a first piston 22A, a second piston 22B, a first bearing member 24A, and a second bearing member 24B. The first piston 22A is mounted on the first eccentric shaft portion 51. The second piston 22B is mounted on the second eccentric shaft portion 52. The first bearing member 24A rotatably supports the long shaft portion 55. The second bearing member 24B rotatably supports the short shaft portion 54. The compressor casing 10 houses the rotating electric machine 30, the crankshaft 40, and the compression mechanism 20. In this configuration, the compressor 1 rotatably supports the long shaft portion 55 and the short shaft portion 54, whose misalignment is suppressed, by a first bearing member and a second bearing member. Therefore, vibration of the compressor 1 can be reduced, and the driving efficiency of the compressor 1 can be increased.

[0100] The refrigeration cycle device 200 of this embodiment includes a circulation path section 201, a compressor 1, a heat exchanger (outdoor heat exchanger 202 or indoor heat exchanger 204), a pressure reducer 203, and an evaporator (indoor heat exchanger 204 or outdoor heat exchanger 202). Refrigerant R circulates through the circulation path section 201. The compressor 1 compresses the refrigerant R. The heat exchanger extracts heat from the refrigerant compressed by the compressor 1. The pressure reducer 203 reduces the pressure of the refrigerant flowing out of the heat exchanger. The evaporator evaporates the refrigerant flowing out of the pressure reducer 203. With this configuration, the driving efficiency of the compressor 1 is increased, thus providing a refrigeration cycle device 200 with high driving efficiency.

[0101] In the refrigeration cycle device 200 described above, the refrigerant R is a single refrigerant from among R1234yf, R1234ze, R32, and R290, or a mixture of two or more of these, or a mixture of one of these with another refrigerant, or a mixture containing R1132(E), or a mixture containing R1123. With this configuration, an environmentally friendly refrigeration cycle device 200 can be provided.

[0102] The manufacturing method for the crankshaft 40 of this embodiment comprises a preliminary step SA and a grinding step S40. The preliminary step SA is a step of preparing a work-in-progress 40A having a first eccentric shaft portion 51 and a second eccentric shaft portion 52 that are eccentric with respect to the central axis O. The grinding step S40 is a step of grinding the outer circumferential surface of the first eccentric shaft portion 51 and the outer circumferential surface of the second eccentric shaft portion 52. The work-in-progress 40A comprises a long shaft portion 55, a connecting shaft portion 53, a short shaft portion 54, the first eccentric shaft portion 51, and the second eccentric shaft portion 52. The long shaft portion 55, the connecting shaft portion 53, and the short shaft portion 54 extend axially with respect to the central axis O. The first eccentric shaft portion 51 is located between the long shaft portion 55 and the connecting shaft portion 53 in the axial direction. The second eccentric shaft portion 52 is located in the axial direction between the connecting shaft portion 53 and the short shaft portion 54. The long shaft portion 55 has a larger axial dimension than the short shaft portion 54. The first eccentric shaft portion 51 and the second eccentric shaft portion 52 are eccentric to opposite sides of the central axis O. The outer circumferential surface of the first eccentric shaft portion 51 is a machined surface formed by machining. The residual stress remaining on the outer circumferential surface of the second eccentric shaft portion 52 is greater than the residual stress remaining on the outer circumferential surface of the first eccentric shaft portion 51.

[0103] In this configuration, the first eccentric shaft portion 51 and the second eccentric shaft portion 52 of the work-in-progress 40A are eccentric to opposite sides of the central axis O. Therefore, by performing the grinding process S40 on the work-in-progress 40A, the bending direction starting from the first eccentric shaft portion 51 and the bending direction starting from the second eccentric shaft portion 52 can be made to be in opposite directions, thereby reducing the amount of misalignment at both ends of the crankshaft 40. Furthermore, in this configuration, the outer circumferential surface of the second eccentric shaft portion 52 of the work-in-progress 40A has a greater residual stress than the outer circumferential surface of the first eccentric shaft portion 51. Therefore, the second deformation angle θ2 starting from the second eccentric shaft portion 52 can be made larger than the first deformation angle θ1 starting from the first eccentric shaft portion 51. This further reduces the amount of misalignment at both ends. This configuration eliminates the need for a process to correct misalignment in the manufacturing process of the crankshaft 40, thereby improving productivity and reducing equipment investment costs.

[0104] In the above-described method for manufacturing the crankshaft 40, the preliminary step SA includes a cutting step S20 and a residual stress application step (burnishing step) S30. The cutting step S20 is a step of forming the outer circumferential surfaces of the first eccentric shaft portion 51 and the second eccentric shaft portion 52 by cutting. The residual stress application step S30 is a step of applying compressive residual stress to the outer circumferential surface of the second eccentric shaft portion 52 by burnishing. With this configuration, by performing burnishing, the residual stress remaining on the outer circumferential surface of the second eccentric shaft portion 52 in the work-in-progress 40A can be made greater than the residual stress remaining on the outer circumferential surface of the first eccentric shaft portion 51. Furthermore, the burnishing step does not require a masking step or the like, and can be performed using the same chuck as the cutting step and the same lathe as the cutting step. For this reason, residual stress can be applied to the outer circumferential surface of the second eccentric shaft portion 52 at low cost.

[0105] (Modification 1) Figure 13 is a flowchart of the residual stress application step S130 of a modified version that can be used in the manufacturing method of the crankshaft 40 described above. Figure 14 is a schematic diagram showing the residual stress application step S130 of the modified version. In the description of this modification, the same reference numerals are used for components identical to those in the above-described embodiment, and their descriptions are omitted.

[0106] As shown in Figure 13, the residual stress application step S30 of this modified example includes a masking step S131 and a shot peening step S132.

[0107] As shown in Figure 14, the masking process S131 involves applying a mask M to the surface of the crankshaft 40, excluding the outer circumferential surface of the second eccentric shaft portion 52. The mask M only needs to be applied to at least the outer circumferential surface of the first eccentric shaft portion 51. For example, masking paper can be used as the mask M.

[0108] In the shot peening process S132, shot peening is performed on the outer circumferential surface of the second eccentric shaft portion 52 exposed from the mask M. In the shot peening process S132, countless small spheres 7b of steel and non-ferrous metals are impacted at high speed onto the outer circumferential surface of the second eccentric shaft portion 52. Compressive stress is applied to the outer circumferential surface of the second eccentric shaft portion 52, increasing its hardness.

[0109] After undergoing the residual stress application process S30, the outer circumferential surface of the second eccentric shaft portion 52 becomes a shot-peened surface with increased hardness. On the other hand, since the sphere 7b does not collide with the outer circumferential surface of the first eccentric shaft portion 51, the outer circumferential surface of the first eccentric shaft portion 51 of the work-in-progress 40A remains a machined surface.

[0110] Even when performing the residual stress application step S130 of this modified example, the residual stress remaining on the outer circumferential surface of the second eccentric shaft portion 52 in the work-in-progress 40A can be made greater than the residual stress remaining on the outer circumferential surface of the first eccentric shaft portion. As a result, the second deformation angle θ2 (see Figure 10) in the third grinding step S43 can be made greater than the first deformation angle θ1 (see Figure 9), and the amount of misalignment of the short shaft portion 54 with respect to the long shaft portion 55 can be reduced.

[0111] (Modification 2) Figure 15 is a side view of the modified crankshaft 140. The crankshaft 140 of this modification differs from the embodiment described above mainly in the width dimension W2 of the second eccentric shaft portion 152. In the description of this modification, the same reference numerals are used for components identical to those in the embodiment described above, and their descriptions are omitted.

[0112] In this modified example, the width dimension W22 of the second eccentric shaft portion 152 is larger than the width dimension W1 of the first eccentric shaft portion 51. The second deformation angle θ2 (see Figure 10) in the third grinding step S43 increases as the width dimension W22 of the second eccentric shaft portion 152 increases. According to this modified example, by increasing the width dimension W22 of the second eccentric shaft portion 152, the second deformation angle θ2 can be further increased in addition to performing the residual stress application step S30. This makes it easier to reduce the amount of misalignment (A1-A2) of the short shaft portion 54 relative to the long shaft portion 55.

[0113] While embodiments of this disclosure have been described above, this disclosure is not limited to the configurations of the embodiments described above, and the following configurations and methods may also be adopted.

[0114] The specific shape of the crankshaft is not limited to this embodiment. For example, in the crankshaft of this embodiment, the eccentric shaft portion is circular when viewed from the axial direction, but it does not necessarily have to be circular as long as it is eccentric with respect to the central axis. Also, in the crankshaft of this embodiment, the outer circumferential surface of the eccentric shaft portion is located radially outward relative to the outer circumferential surface of the shaft body. However, the eccentric shaft portion may be partially located radially inward relative to the shaft body.

[0115] Furthermore, the above-described embodiment explained the case where the phase difference between the first eccentric shaft portion and the second eccentric shaft portion with respect to the central axis O is 180°. However, if the first eccentric shaft portion and the second eccentric shaft portion are eccentric on opposite sides with respect to the central axis, their phase difference is not limited to this embodiment.

[0116] The refrigeration cycle device relating to this disclosure may be any device that utilizes a refrigeration cycle in which a refrigerant is circulated, and is not limited to air conditioners. The refrigeration cycle device may also be a heat pump water heater or the like.

[0117] The relative positions and dimensions of the parts described in each of the embodiments described above are merely examples, and the relative positions and dimensions of the parts in this disclosure are not particularly limited, as long as they are within the scope of the technical concept of this disclosure. The configurations and methods described herein can be combined as appropriate, as long as they are not inconsistent with each other.

[0118] 1... Compressor, 10... Compressor casing, 20... Compression mechanism, 22A... First piston, 22B... Second piston, 24A... First bearing member, 24B... Second bearing member, 30... Rotating electric machine, 40, 40P, 140... Crankshaft, 40A... Work in progress (work in progress of crankshaft), 51... First eccentric shaft section, 52, 152... Second eccentric shaft section, 53... Connecting shaft section, 54... Short shaft section, 55... Long shaft section, 61... Grinding wheel, 200... Refrigeration cycle device, 201... Circulation path section, 203... Pressure reducer, O... Central axis, M... Mask, R... Refrigerant, S20... Cutting process, S22... Process, S30... Residual stress application process (burnishing process), S40... Grinding process, S131... Masking process, S132... Shot peening process, SA... Preliminary process

Claims

1. A work-in-progress crankshaft comprising: a long shaft portion, a connecting shaft portion, and a short shaft portion extending axially with respect to a central axis; a first eccentric shaft portion located between the long shaft portion and the connecting shaft portion in the axial direction and extending axially eccentrically with respect to the central axis; and a second eccentric shaft portion located between the connecting shaft portion and the short shaft portion in the axial direction and extending axially eccentrically with respect to the central axis, wherein the long shaft portion has a larger axial dimension than the short shaft portion; the first eccentric shaft portion and the second eccentric shaft portion are eccentric to opposite sides of the central axis; the outer circumferential surface of the first eccentric shaft portion is a machined surface formed by machining; and the residual stress remaining on the outer circumferential surface of the second eccentric shaft portion is greater than the residual stress remaining on the outer circumferential surface of the first eccentric shaft portion.

2. The work-in-progress of the crankshaft according to claim 1, wherein the hardness of the outer circumferential surface of the second eccentric shaft portion is higher than the hardness of the outer circumferential surface of the first eccentric shaft portion.

3. A crankshaft comprising: a long shaft portion, a connecting shaft portion, and a short shaft portion extending axially with respect to a central axis; a first eccentric shaft portion located between the long shaft portion and the connecting shaft portion in the axial direction and extending axially eccentrically with respect to the central axis; and a second eccentric shaft portion located between the connecting shaft portion and the short shaft portion in the axial direction and extending axially eccentrically with respect to the central axis, wherein the long shaft portion has a larger axial dimension than the short shaft portion; the first eccentric shaft portion and the second eccentric shaft portion are eccentric to opposite sides of the central axis; and the residual stress remaining on the outer circumferential surface of the second eccentric shaft portion is greater than the residual stress remaining on the outer circumferential surface of the first eccentric shaft portion.

4. A compressor comprising: a crankshaft according to claim 3; a rotating electric machine for rotating the crankshaft about the central axis; a compression mechanism having a first piston mounted on the first eccentric shaft portion, a second piston mounted on the second eccentric shaft portion, a first bearing member for rotatably supporting the long shaft portion, and a second bearing member for rotatably supporting the short shaft portion; and a compressor casing housing the rotating electric machine, the crankshaft, and the compression mechanism.

5. A refrigeration cycle device comprising the compressor described in claim 4, the device comprising: a circulation path section through which a refrigerant circulates; the compressor for compressing the refrigerant; a heat sink disposed in the path of the circulation path section for extracting heat from the compressed refrigerant; a pressure reducer for reducing the pressure of the refrigerant flowing out of the heat sink; and an evaporator for evaporating the refrigerant flowing out of the pressure reducer.

6. The refrigeration cycle apparatus according to claim 5, wherein the refrigerant is a single refrigerant from among R1234yf, R1234ze, R32, and R290, or a mixture of two or more of these, or a mixture of one of these and another refrigerant, or a mixture containing R1132(E), or a mixture containing R1123.

7. A work-in-progress of a crankshaft having a first eccentric shaft portion and a second eccentric shaft portion that are eccentric with respect to the central axis; a grinding step of grinding the outer circumferential surface of the first eccentric shaft portion and the outer circumferential surface of the second eccentric shaft portion, wherein the work-in-progress comprises a long shaft portion, a connecting shaft portion, and a short shaft portion extending axially with respect to the central axis; the first eccentric shaft portion located between the long shaft portion and the connecting shaft portion in the axial direction; and the first eccentric shaft portion located between the connecting shaft portion and the short shaft portion in the axial direction, wherein the long shaft portion has a larger axial dimension than the short shaft portion, the first eccentric shaft portion and the second eccentric shaft portion are eccentric to opposite sides of the central axis, and in the work-in-progress, the outer circumferential surface of the first eccentric shaft portion is a machined surface formed by cutting. A method for manufacturing a crankshaft, wherein the residual stress remaining on the outer circumferential surface of the second eccentric shaft portion in the work-in-progress is greater than the residual stress remaining on the outer circumferential surface of the first eccentric shaft portion.

8. The method for manufacturing a crankshaft according to claim 7, wherein the preliminary step comprises a cutting step of forming the outer circumferential surface of the first eccentric shaft portion and the outer circumferential surface of the second eccentric shaft portion by cutting, and a burnishing step of applying a burnishing process to the outer circumferential surface of the second eccentric shaft portion to impart compressive residual stress.

9. The method for manufacturing a crankshaft according to claim 7, wherein the preliminary step comprises a cutting step of forming the outer circumferential surface of the first eccentric shaft portion and the outer circumferential surface of the second eccentric shaft portion by cutting; a masking step of applying a mask to the outer circumferential surface of the first eccentric shaft portion; and a shot peening step of applying shot peening to the outer circumferential surface of the second eccentric shaft portion to impart compressive residual stress.

Images