Inverter integrated electric compressor

Abstract

This invention provides an inverter-integrated electric compressor that can suppress or prevent electro-corrosion of the bearing supporting the rotating shaft of the rotor on which the electric motor is fixed. In the inverter-integrated electric compressor (10), a first partition (212) of a conductive housing (20) separates the inverter (60) from the electric motor (40), and a second partition (232) of the housing (20) separates the electric motor (40) from the compression mechanism (50). The stator (41) of the electric motor (40) is fixed to the housing (20), and the conductive rotating shaft (30) of the rotor (42) on which the electric motor (40) is fixed is supported to rotate by a first metal bearing (25) held in the first partition (212) and a second metal bearing (26) held in the second partition (232). Furthermore, an insulating layer (35) is provided between the rotating shaft (30) and the rotor (42).

Description

Technical Field

[0001] This invention relates to an inverter-integrated electric compressor. Background Technology

[0002] As an example of an electric compressor, an inverter-integrated electric compressor is known in the past. In this type of electric compressor, a metal shaft (drive shaft), an electric motor that rotates the shaft, a compression mechanism driven by the rotation of the shaft, and an inverter that drives the electric motor are, in most cases, integrated into a metal housing. Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-2282 Summary of the Invention The technical problem that the invention aims to solve

[0004] When an electric motor is driven by an inverter, a shaft voltage is generated between the shaft and the housing that holds the metal bearing supporting the shaft due to the electrostatic capacitance within the electric motor. If this shaft voltage exceeds, for example, the insulation breakdown voltage of the insulating film generated by the lubricant, discharge will occur between the shaft and the bearing, as well as inside the bearing, resulting in potential electrolytic corrosion of the bearing.

[0005] Therefore, the object of the present invention is to provide an inverter-integrated electric compressor that can suppress or prevent electro-corrosion of a metal bearing that supports the rotor of an electric motor as a rotatable component. Technical solutions adopted to solve technical problems

[0006] According to one aspect of the present invention, an inverter-integrated electric compressor is provided. The provided inverter-integrated electric compressor includes: a conductive shaft; an electric motor that rotates the shaft; a compression mechanism driven by the rotation of the shaft to compress a fluid; an inverter that drives the electric motor; and a conductive housing that houses the shaft, the electric motor, the compression mechanism, and the inverter. The housing has a first partition portion and a second partition portion, the first partition portion separating the inverter from the electric motor, and the second partition portion separating the electric motor from the compression mechanism. The electric motor includes a stator fixed to the housing and a rotor fixed to the shaft. The shaft is supported for rotation by a first metal bearing held in the first partition portion and a second metal bearing held in the second partition portion. Furthermore, an insulating layer is provided between the shaft and the rotor. Invention Effects

[0007] According to one aspect of the present invention, an inverter-integrated electric compressor can be provided, which can suppress or prevent electro-corrosion of the bearing that supports the rotor of the electric motor as a rotatable shaft. Attached Figure Description

[0008] Figure 1 This is a cross-sectional view showing an inverter-integrated electric compressor according to an embodiment. Figure 2 This is a diagram showing the shaft and the rotor of the electric motor. Figure 3 This is a diagram that conceptually illustrates an example of the principle of shaft voltage generation achieved by the electrostatic capacitance inside an electric motor. Detailed Implementation

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0010] Figure 1 This is a cross-sectional view illustrating the schematic structure of an inverter-integrated electric compressor (hereinafter simply referred to as "electric compressor") according to an embodiment of the present invention. The electric compressor 10 of this embodiment is, for example, installed in the refrigerant circuit of an automotive air conditioning system and configured to compress, pressurize, and discharge gaseous refrigerant (i.e., fluid) flowing in the refrigerant circuit. Here, the gaseous refrigerant flowing in the refrigerant circuit may contain a lubricant.

[0011] In addition, the following will Figure 1 The left side serves as the front side of the electric compressor 10. Figure 1 The right side serves as the rear side of the electric compressor 10. Figure 1 The upper side serves as the upper side of the electric compressor 10. Figure 1 The lower side of the electric compressor 10 will be described below. Furthermore, terms such as "first" and "second" are simply used to distinguish similar components rather than to limit the components that use these terms.

[0012] The electric compressor 10 includes: a housing 20; a shaft 30; an electric motor 40 that rotates the shaft 30; a compression mechanism 50 that is driven by the rotation of the shaft 30 to compress a gaseous refrigerant (fluid); and an inverter 60 that supplies power to the electric motor 40 to drive it. The shaft 30, the electric motor 40, the compression mechanism 50, and the inverter 60 are housed in the housing 20. Although not particularly limited, in this embodiment a scroll compressor mechanism is used as the compression mechanism 50, which includes: a fixed scroll 51 fixed to the housing 20; and a movable scroll 52 that revolves around the fixed scroll 51.

[0013] The outer casing 20 is, for example, made of metal and is conductive. In this embodiment, the outer casing 20 includes a front outer casing 21, a cover member 22, a middle outer casing 23, and a rear outer casing 24 as outer casing components. Furthermore, these outer casing components are fastened with fasteners or the like (omitted in the figure) to form the outer casing 20 of the electric compressor 10. However, it is not limited to this, and the outer casing 20 can be formed by any combination of outer casing components.

[0014] The front housing 21 has a cylindrical first peripheral wall portion 211 extending front to back. The front end face of the first peripheral wall portion 211 is the front end face of the front housing 21, and the rear end face of the first peripheral wall portion 211 is the rear end face of the front housing 21. The interior of the first peripheral wall portion 211 is divided by a first partition portion 212 into an inverter housing space for accommodating the front side of the inverter 60 and a motor housing space for accommodating the rear side of the electric motor 40. In other words, the first partition portion 212 of the front housing 21 (i.e., housing 20) separates the electric motor 40 and the inverter 60 within the housing 20.

[0015] A first bearing retaining portion 213 is formed in the first partition wall portion 212. The first bearing retaining portion 213 is located approximately at the radial center of the first partition wall portion 212. The first bearing retaining portion 213 is cylindrical and protrudes rearward from the rear surface of the first partition wall portion 212, i.e., into the motor housing space. A first bearing 25 made of metal is held in the first bearing retaining portion 213. In this embodiment, the first bearing 25 is a rolling bearing, including an inner ring, an outer ring, and a plurality of rolling elements disposed between the inner ring and the outer ring. The sliding portion of the first bearing 25 can be lubricated by a pre-applied lubricant and / or a lubricant contained in the gaseous refrigerant.

[0016] A cover member 22 is joined to the front end face of the front housing 21. This seals off the inverter housing space, forming an inverter housing chamber. The front end face of the intermediate housing 23 is joined to the rear end face of the front housing 21. Furthermore, sealing members can be provided between the front housing 21 and the cover member 22, and between the front housing 21 and the intermediate housing 23, as needed.

[0017] The intermediate housing 23 has a cylindrical second circumferential wall portion 231 extending front to back. The front end face of the second circumferential wall portion 231 is the front end face of the intermediate housing 23, and the rear end face of the second circumferential wall portion 231 is the rear end face of the intermediate housing 23. The interior of the second circumferential wall portion 231 is divided by a second partition portion 232 into a front connecting space connected to the motor receiving space of the front housing 21 and a rear compression mechanism receiving space for receiving the compression mechanism 50. In other words, the second partition portion 232 of the intermediate housing 23 (i.e., housing 20) separates the electric motor 40 and the compression mechanism 50 within the housing 20.

[0018] The second partition wall portion 232 has a hollow, cylindrical protrusion 233 with a bottom. The bottom of the hollow protrusion 233 faces forward and protrudes forward relative to the other parts of the second partition wall portion 232, i.e., towards the motor housing space. The hollow protrusion 233 is disposed at approximately the radial center of the second partition wall portion 232, opposite to the first bearing retaining portion 213 disposed on the first partition wall portion 212 of the front housing 21. A shaft insertion hole 234 for the shaft 30 to be inserted is formed on the flat portion (bottom of the cylindrical portion) on the front side of the hollow protrusion 233. Furthermore, a second bearing retaining portion 235 is formed inside the hollow protrusion 233. That is, the second bearing retaining portion 235 is disposed closer to the compression mechanism 50 than the shaft insertion hole 234. A metal second bearing 26 is held in the second bearing retaining portion 235. In this embodiment, the second bearing 26 is a rolling bearing, just like the first bearing 25. The sliding portion of the second bearing 26, like the sliding portion of the first bearing 25, can be lubricated by a pre-applied lubricant and / or the lubricant contained in the gaseous refrigerant.

[0019] The rear end face of the rear outer shell 24 is joined to the rear end face of the intermediate outer shell 23. The rear outer shell 24 is formed into a bottomed cylindrical shape, having a cylindrical third peripheral wall portion 241 extending front and rear and a bottom wall portion 242 that seals the opening on the rear side of the third peripheral wall portion 241. The front end face that serves as the opening end face of the third peripheral wall portion 241 is the front end face of the rear outer shell 24.

[0020] In this embodiment, a recess 236 is formed on the rear end face of the intermediate outer shell 23, i.e., the rear end face of the second peripheral wall portion 231. This recess can accommodate the outer edge of the first substrate 511 (described later) of the fixed scroll 51 constituting the compression mechanism 50 (vortex compression mechanism). Furthermore, the outer edge of the first substrate 511 of the fixed scroll 51 is held between the intermediate outer shell 23 and the rear outer shell 24 while being accommodated in the recess 236. Thus, the fixed scroll 51 is fixed to the outer shell 20, the rear opening of the intermediate outer shell 23 (second peripheral wall portion 231) is blocked by the first substrate 511 of the fixed scroll 51, and the opening end face (front opening) of the rear outer shell 24 (third peripheral wall portion 241) is blocked by the first substrate 511 of the fixed scroll 51.

[0021] The rotating shaft 30 is, for example, made of metal and is conductive. The rotating shaft 30 is inserted into a shaft insertion hole 234 formed in the hollow protrusion 233 of the second partition 232. In other words, the rotating shaft 30 passes through the shaft insertion hole 234 and extends in the front-rear direction within the housing 20. Furthermore, the rotating shaft 30 is supported by a first bearing 25 and a second bearing 26 to be rotatable relative to the housing 20. The first bearing 25 is held in the first partition 212 (first bearing holding portion 213), and the second bearing 26 is held in the second partition 232 (second bearing holding portion 235).

[0022] In this embodiment, the communication between the space on the electric motor 40 side (the motor housing space) and the space on the compression mechanism 50 side (the compression mechanism housing space) within the housing 20, separated by the shaft insertion hole 234, is severed; therefore, a shaft sealing member 27 is provided. The shaft sealing member 27 is held in a seal holding portion 237 formed inside the hollow protrusion 233 of the second partition wall portion 232. The seal holding portion 237 is disposed between the shaft insertion hole 234 and the second bearing holding portion 235. The shaft sealing member 27 is formed in an annular shape, and its outer peripheral portion is fixed to the seal holding portion 237, for example, by pressing, while its inner peripheral portion contacts (slidingly contacts) the outer peripheral surface of the rotating shaft 30.

[0023] In other words, the shaft sealing member 27 is disposed inside the hollow protrusion 233 of the second partition 232, closer to the electric motor 40 than the second bearing 26, and further adjacent to the shaft insertion hole 234. Furthermore, the shaft sealing member 27 seals the space between the electric motor 40 side and the compression mechanism 50 side of the rotating shaft 30 in the axial direction, thereby effectively severing (substantially severing) the communication between the space on the electric motor 40 side (the motor housing space) and the space on the compression mechanism 50 side (the compression mechanism housing space) within the housing 20 via the shaft insertion hole 234.

[0024] The electric motor 40 is, for example, a three-phase AC motor. The electric motor 40 includes a stator 41 and a rotor 42. Both the stator 41 and the rotor 42 are conductive.

[0025] The stator 41 is fixed to the inner peripheral surface of the first peripheral wall portion 211 of the front housing 21 (i.e., the housing 20). The stator 41 includes a stator core and stator windings. Alternating current is supplied to the stator windings from an inverter 60. The inverter 60 is configured to convert direct current from a vehicle battery (not shown) or the like into alternating current and supply it to the stator windings of the stator 41.

[0026] The rotor 42 is configured with a predetermined gap from the radially inner side of the stator 41. A permanent magnet is installed in the rotor 42. The rotor 42 is integrally formed into a cylindrical shape, and is fixed to the rotating shaft 30 with a through hole extending through the rotor 42 in the front-to-back direction. That is, the rotor 42 is fixed to the outer circumferential surface of the rotating shaft 30 and rotates integrally with the rotating shaft 30.

[0027] Figure 2 This is a diagram showing the shaft 30 and the rotor 42 of the electric motor 40. (See diagram below.) Figure 2 As shown, in this embodiment, an insulating layer 35 is provided between the rotating shaft 30 and the rotor 42. While not particularly limited, the insulating layer 35 can be formed of an electrically insulating resin such as fluoropolymer or epoxy resin. Furthermore, the insulating layer 35 can have a desired thickness.

[0028] In this embodiment, the rotor 42 is pressed into the through hole 42a (hollow portion) of the rotor 42 by the shaft 30 and fixed to the outer peripheral surface of the shaft 30. The insulating layer 35 is formed to cover the portion of the outer peripheral surface of the shaft 30 corresponding to the rotor 42. Furthermore, of the two openings of the through hole 42a (hollow portion) of the rotor 42, namely the opening on the inverter 60 side (front opening) and the opening on the compression mechanism 50 side (rear opening), the peripheral edge 42b of the opening on the compression mechanism 50 side is chamfered to a greater extent than the peripheral edge 42c of the opening on the inverter 60 side (including the case where only the peripheral edge 42b on the compression mechanism 50 side is chamfered).

[0029] The electric motor 40 generates a magnetic field in the stator 41 by power supplied from the inverter 60. The rotational force acts on the permanent magnet of the rotor 42, causing the rotor 42 to rotate, thereby causing the shaft 30 to rotate. In other words, the electric motor 40 is configured to be driven by the inverter 60 to rotate the shaft 30.

[0030] As described above, the compression mechanism 50 is a scroll compression mechanism, which includes a fixed scroll 51 and a movable scroll 52 that revolves around the fixed scroll 51.

[0031] The fixed scroll 51 has a circular plate-shaped first base plate 511 and a first scroll wall 512 erected on one side of the first base plate 511. The first scroll wall 512 extends from the inner end (winding start portion) on the radially inward side of the first base plate 511 in a scroll shape (involute curve state) to the outer end (winding end portion) on the radially outward side of the one side of the first base plate 511 (the side where the first scroll wall 512 is erected) facing forward, so that the outer edge of the first base plate 511 is received in the recess 236 and is fixed by being clamped by the intermediate outer shell 23 and the rear outer shell 24.

[0032] The movable scroll 52 has a circular plate-shaped second base plate 521, a second scroll wall 522 erected on one side of the second base plate 521, and a cylindrical portion 523 protruding from the other side of the second base plate 521. The second scroll wall 522 extends from the inner end (winding start portion) radially inward along a scroll shape (involute curve shape) to the outer end (winding end portion) radially outward on the said one side of the second base plate 521. The movable scroll 52 is disposed between the second partition portion 232 of the intermediate housing 23 and the fixed scroll 51 with the said one side of the second base plate 521 (the side where the second scroll wall 522 is erected) facing rearward. In other words, the movable scroll 52 is disposed opposite to the fixed scroll 51 in such a way that the second scroll wall 522 engages with the first scroll wall 512 of the fixed scroll 51. In addition, the said other side of the second base plate 521 is also referred to as the back side of the second base plate 521 or the back side of the movable scroll 52.

[0033] The movable scroll 52 is driven by a driving force transmitted via the shaft 30 and the crank mechanism 70. The crank mechanism 70 is a mechanism that converts the rotation of the shaft 30 into the revolution-rotational motion of the movable scroll 52. The driven movable scroll 52 is configured to perform revolution-rotational motion relative to the fixed scroll 51 while its rotation is prevented by the rotation-stopping mechanism 80.

[0034] While not specifically limited, the crank mechanism 70 may, for example, have a structure including an eccentric pin and an eccentric bushing. The eccentric pin is eccentrically disposed at the rear end of the shaft 30 relative to the shaft 30, and the eccentric bushing is rotatably mounted to the eccentric pin and rotatably inserted into the cylindrical portion 523 via a bearing. Furthermore, the rotation-stopping mechanism 80 may, for example, have a structure including a ring and a pin. The ring is pressed into a circular hole formed on the other side (back side) of the second base plate 521 of the movable scroll 52, and the pin is fixed to the second partition wall portion 232 of the intermediate housing 23, passes through the thrust plate 90, and extends to the inside of the ring.

[0035] The compression mechanism 50 (vortex compression mechanism) is configured to draw in and compress gaseous refrigerant by causing the movable scroll 52 to revolve relative to the fixed scroll 51. Furthermore, an annular thrust plate 90 is disposed between the second base plate 521 of the movable scroll 52 and the second partition wall 232 of the intermediate housing 23, and the rear surface of the second partition wall 232 receives thrust from the movable scroll 52 via the thrust plate 90.

[0036] In addition, such as Figure 1 As shown, the electric compressor 10 of the embodiment includes: an intake chamber H1 for which gaseous refrigerant (fluid) flows in from the outside; a compression chamber H2 for compressing the gaseous refrigerant; a discharge chamber H3 for discharging the gaseous refrigerant compressed in the compression chamber H2; a gas-liquid separation chamber H4 for separating lubricating oil from the gaseous refrigerant compressed in the compression chamber H2; and a back pressure chamber H5 disposed on the back side of the second base plate 521 of the movable scroll 52.

[0037] The intake chamber H1 is formed by the motor housing space of the front outer shell 21 and the connection space of the intermediate outer shell 23. In other words, the intake chamber H1 is divided by the first peripheral wall portion 211 of the front outer shell 21, the first partition wall portion 212 of the front outer shell 21, the second peripheral wall portion 231 of the intermediate outer shell 23, and the second partition wall portion 232 of the intermediate outer shell 23. An intake port P1 is formed in the first peripheral wall portion 211 of the front outer shell 21 that divides the intake chamber H1, and gaseous refrigerant from the outside flows into the intake chamber H1 through the intake port P1. An electric motor 40 and a first bearing 25 are arranged in the intake chamber H1. In addition, a refrigerant passage L1 is formed in the intermediate outer shell 23 for guiding the gaseous refrigerant in the intake chamber H1 to the space H6 near the outer end of the compression mechanism 50 (scroll compressor mechanism).

[0038] Compression chamber H2 is formed between fixed scroll 51 and movable scroll 52. In compression mechanism 50 (scroll compression mechanism), when movable scroll 52 revolves relative to fixed scroll 51, second scroll wall 522 contacts first scroll wall 512, forming a crescent-shaped sealed space radially outward from first base plate 511, first scroll wall 512, second base plate 521, and second scroll wall 522. This crescent-shaped sealed space gradually decreases in volume while moving radially inward. This crescent-shaped sealed space is compression chamber H2.

[0039] The discharge chamber H3 is formed by dividing the third peripheral wall portion 241 of the rear outer casing 24, the bottom wall portion 242 of the rear outer casing 24, and the first base plate 511 of the fixed scroll 51. That is, the interior of the third peripheral wall portion 241 of the rear outer casing 24 becomes the discharge chamber H3. A discharge port L2 is formed at the radial center of the first base plate 511 of the fixed scroll 51, communicating with the discharge chamber H3 through the compression chamber H2, which moves inward and has a smaller volume. A check valve (reed valve) 95 is provided in the discharge port L2. The check valve 95 is configured to allow gaseous refrigerant to flow from the compression chamber H2 to the discharge chamber H3, but to prevent gaseous refrigerant from flowing from the discharge chamber H3 to the compression chamber H2.

[0040] The gas-liquid separation chamber H4 is located further rearward than the discharge chamber H3. Specifically, the gas-liquid separation chamber H4 is formed in the bottom wall portion 242 of the rear outer casing 24 as a cylindrical space extending downward from the upper part of the rear outer casing 24. The discharge chamber H3 and the gas-liquid separation chamber H4 are connected via a connecting hole L3. An oil separator 100 for separating lubricating oil contained in the gaseous refrigerant is disposed in the gas-liquid separation chamber H4. An outlet P2 communicating with the gas-liquid separation chamber H4 is provided on the upper part of the rear outer casing 24.

[0041] The back pressure chamber H5 is formed by dividing the second partition wall portion 232 of the intermediate outer shell 23 and the second base plate 521 of the movable scroll 52. In other words, in this embodiment, the back pressure chamber H5 is mainly formed by the internal space of the hollow protrusion 233 of the second partition wall portion 232. The back pressure chamber H5 is equipped with a second bearing 26, a shaft sealing member 27, and a crank mechanism 70, etc. The back pressure chamber H5 is connected to the discharge chamber H3 and the gas-liquid separation chamber H4 via a communication path L4 formed in the intermediate outer shell 23 and the rear outer shell 24, and a throttling orifice (throttling section) OL is arranged in the middle of the communication path L4. In addition, although not shown in the figure, the back pressure chamber H5 is connected to the suction chamber H1 via the throttling orifice and a back pressure control valve provided in the middle of the pressure relief passage.

[0042] Here, the operation of the electric compressor 10 will be briefly explained.

[0043] When the electric motor 40 rotates the shaft 30 via power supplied from the inverter 60, the rotation of the shaft 30 is transmitted to the compression mechanism 50 (more specifically, the movable scroll 52) via the crank mechanism 70, which revolves relative to the fixed scroll 51. Thus, gaseous refrigerant (low pressure) flows into the suction chamber H1 through the suction port P1, passes through the electric motor 40 and the refrigerant passage L1, reaches the space H6, and is drawn into the compression chamber H2 formed between the fixed scroll 51 and the movable scroll 52, where it is compressed. The compressed gaseous refrigerant (high pressure) in the compression chamber H2 is discharged into the discharge chamber H3 through the discharge port L2 (and check valve 95), and then flows into the gas-liquid separation chamber H4 through the connecting port L3. The gaseous refrigerant flowing into the gas-liquid separation chamber H4 is separated from the lubricating oil contained therein by the oil separator 100. Then, the gaseous refrigerant (high pressure) after the lubricating oil has been separated by the oil separator 100 is discharged from the discharge port P2. The lubricating oil separated from the gaseous refrigerant by the oil separator 100 is stored at the bottom of the gas-liquid separation chamber H4. Additionally, a portion of the lubricating oil contained in the gaseous refrigerant discharged into the discharge chamber H3 is also stored at the bottom of the discharge chamber H3.

[0044] Back pressure chamber H5 is connected to discharge chamber H3 and gas-liquid separation chamber H4 via connecting path L4. Furthermore, back pressure chamber H5 is also connected to suction chamber H1 via shaft insertion hole 234 and the aforementioned pressure relief passage. Discharge chamber H3 and gas-liquid separation chamber H4 are high-pressure chambers, while suction chamber H1 is low-pressure chamber. Therefore, lubricating oil stored at the bottom of discharge chamber H3 and / or the bottom of gas-liquid separation chamber H4, along with the gaseous refrigerant in discharge chamber H3 and / or gas-liquid separation chamber H4, is supplied to back pressure chamber H5 via connecting path L4, where it is depressurized by passing through throttling orifice OL. Furthermore, the lubricating oil and / or gaseous refrigerant in back pressure chamber H5 are restricted from flowing into suction chamber H1 by shaft seal member 27, throttling orifice provided in the pressure relief passage, and back pressure control valve. Therefore, the pressure in the back pressure chamber H5 is maintained at an intermediate pressure Pm between the pressure Ps in the suction chamber H1 and the pressure Pd in ​​the discharge chamber H3 (which is equal to the pressure in the gas-liquid separation chamber H4). This intermediate pressure Pm presses the movable scroll 52 toward the fixed scroll 51. In other words, the back pressure chamber H5 applies pressure to the movable scroll 52 in the direction of pressing toward the fixed scroll 51.

[0045] As explained above, in the electric compressor 10 of this embodiment, the conductive shaft 30 of the rotor 42 of the electric motor 40 is supported by a first metal bearing 25 and a second metal bearing 26 to enable rotation. The first bearing 25 is held in the first partition 212 of the front outer casing 21 constituting the conductive outer casing 20, and the second bearing 26 is held in the second partition 232 of the middle outer casing 23 constituting the outer casing 20. The first partition 212 separates the inverter 60 and the electric motor 40 within the outer casing 20, and the second partition 232 separates the electric motor 40 and the compression mechanism 50 within the outer casing 20. The first bearing 25 and the second bearing 26 are rolling bearings.

[0046] Furthermore, in the electric compressor 10 of this embodiment, the electric motor 40 is driven by the inverter 60. Therefore, the switching of the switching elements of the inverter 60... Figure 3A common-mode voltage Vc is applied to the stator windings of the stator 41 of the electric motor 40. This common-mode voltage Vc is, for example, a voltage divider formed by a first capacitance C1 between the stator windings and the shaft 30, and a second capacitance C2 between the shaft 30 and the housing 20 that holds the bearings (first bearing 25, second bearing 26) supporting the shaft 30. The voltage share of the second capacitance C2 (=Vc×C1 / (C1+C2)) is generated as a shaft voltage between the shaft 30 and the housing 20. The first capacitance C1 is primarily the capacitance between the stator windings and the rotor 42, and the second capacitance is primarily the capacitance of the insulating film formed by the lubricant within the first bearing 25 and / or the second bearing 26. Furthermore, as previously stated, if the shaft voltage between the shaft 30 and the housing 20 exceeds the insulation breakdown voltage of the insulating film formed by the lubricant, a discharge will occur inside the first bearing 25 and / or the second bearing 26, resulting in potential electrolytic corrosion in the first bearing 25 and / or the second bearing 26.

[0047] In this embodiment, an insulating layer 35 is provided between the shaft 30 and the rotor 42. That is, the capacitance of the insulating layer 35 is added in series (connected) to the capacitance between the stator windings and the shaft 30. Therefore, the voltage sharing V2 of the second capacitance C2, i.e., the shaft voltage generated between the shaft 30 and the housing 20, is adjusted and further reduced by the capacitance of the insulating layer 35. Therefore, according to this embodiment, the electric compressor 10, by utilizing the insulating layer 35 to reduce the shaft voltage generated between the shaft 30 and the housing 20 compared to the past, can suppress or prevent internal discharge of the first bearing 25 and / or the second bearing 26, thereby suppressing or preventing electro-corrosion of the first bearing 25 and / or the second bearing 26. As a result, stable operation over a long period can be achieved.

[0048] Furthermore, in this embodiment, the rotor 42 is fixed to the outer peripheral surface of the shaft 30 by being pressed into the through hole 42a of the rotor 42, and the insulating layer 35 is formed in such a way that it covers the portion of the outer peripheral surface of the shaft 30 corresponding to the rotor 42. Therefore, it is relatively easy to provide the insulating layer 35 between the shaft 30 and the rotor 42.

[0049] Furthermore, in this embodiment, a scroll compressor is used as the compression mechanism 50. When the compression mechanism 50 is a scroll compressor, the shaft 30 is mostly formed such that the diameter on the compression mechanism 50 side is larger than the diameter on the opposite side (inverter 60 side). Therefore, when the rotor 42 is fixed to the outer peripheral surface of the shaft 30, the shaft 30 is inserted into the compression mechanism 50 side opening of the two openings (the opening on the inverter 60 side and the opening on the compression mechanism 50 side) of the through hole 42a (hollow part) of the rotor 42.

[0050] In this respect, in this embodiment, the periphery 42b of the opening on the compression mechanism 50 side of the two openings of the through hole 42a (hollow portion) of the rotor 42 is chamfered more significantly than the periphery 42c of the opening on the inverter 60 side. Therefore, the chamfered periphery 42b of the opening on the compression mechanism 50 side functions as a guide, facilitating the insertion of the shaft 30 into the through hole 42a (hollow portion) of the rotor 42, and also suppressing or preventing damage to the insulation layer 35 when the shaft 30 and the rotor 42 are integrated.

[0051] Furthermore, in the above embodiment, the insulating layer 35 is formed to cover the portion of the outer peripheral surface of the shaft 30 corresponding to the rotor 42. However, it is not limited to this. The insulating layer 35 may also be provided to cover the inner peripheral surface of the rotor 42. Alternatively, the insulating layer 35 may be formed as an insulating film covering the entire outer peripheral surface of the shaft 30. Alternatively, the entire outer peripheral surface of the shaft 30 may be covered by an insulating film, and the insulating layer 35 may be provided separately from the insulating film on the portion of the outer peripheral surface of the shaft 30 corresponding to the rotor 42. In this way, current can be prevented from flowing from the shaft 30 to the first bearing 25 or the second bearing 26, and discharge caused inside the first bearing 25 and / or the second bearing 26 can be more effectively suppressed or prevented, thereby more effectively suppressing or preventing electro-corrosion of the first bearing 25 and the second bearing 26.

[0052] Furthermore, in the above embodiment, metal rolling bearings are used as the first bearing 25 and the second bearing 26. However, the first bearing 25 and the second bearing 26 do not necessarily have to be rolling bearings. For example, at least one of the first bearing 25 and the second bearing 26 may be formed by a metal sliding bearing. In this case, discharge between the rotating shaft 30 and at least one of the first bearing 25 and the second bearing 26 can be suppressed or prevented, thereby suppressing or preventing electro-corrosion of the first bearing 25 and the second bearing 26.

[0053] Alternatively, the shaft seal member 27 may also be conductive. In this case, the shaft seal member 27 may include, for example, a metallic core and a conductive resin that at least partially covers the surface of the core, through which a rib is formed on the inner periphery that contacts (sliding contact) with the outer peripheral surface of the shaft 30. In this case, the shaft seal member 27 makes the shaft 30 electrically connected to the second partition 232 (i.e., the housing 20), thus preventing the charge generated in the shaft 30 from escaping to the housing 20 via the first bearing 25 and the second bearing 26. Therefore, discharges inside the first bearing 25 and the second bearing 26 can be more effectively suppressed or prevented, and electro-corrosion of the first bearing 25 and the second bearing 26 can be more effectively suppressed or prevented.

[0054] While the embodiments and variations of the present invention have been described above, the present invention is not limited to the above embodiments and variations, and further modifications and changes can be made based on the technical concept of the present invention. (Symbol Explanation)

[0055] 10 Inverter-integrated electric compressor; 20 Housing; 25 First bearing; 26 Second bearing; 27 Shaft sealing component; 30 Rotary shaft; 35 Insulation layer; 40 Electric motor; 41 Stator; 42 Rotor; 42a Through hole; 42b, 42c Peripheral parts; 50 Compression mechanism; 51 Fixed scroll; 52 Movable scroll; 60 Inverter; 212 First partition; 213 First bearing retaining part; 232 Second partition; 233 Hollow protrusion; 234 Shaft insertion through hole; 235 Second bearing retaining part; 237 Seal retaining part; H1 Suction chamber; H2 Compression chamber; H3 Discharge chamber; H5 Back pressure chamber.

Claims

1. An inverter-integrated electric compressor, comprising: A conductive shaft; An electric motor that causes the shaft to rotate; A compression mechanism that is driven by the rotation of the shaft to compress the fluid; An inverter that drives the electric motor; and a conductive housing that houses the shaft, the electric motor, the compression mechanism, and the inverter. Its features are, The housing has a first partition and a second partition, the first partition separating the inverter from the electric motor, and the second partition separating the electric motor from the compression mechanism. The electric motor includes a stator fixed to the housing and a rotor fixed to the shaft. The rotating shaft is supported by a first metal bearing held in the first partition and a second metal bearing held in the second partition, enabling it to rotate. An insulating layer is provided between the rotating shaft and the rotor.

2. The inverter-integrated electric compressor as described in claim 1, characterized in that, The rotor is pressed into the through hole of the rotor via the rotating shaft to be fixed to the outer circumferential surface of the rotating shaft. The insulating layer is formed in such a way that it covers at least the portion of the outer peripheral surface of the shaft corresponding to the rotor.

3. The inverter-integrated electric compressor as described in claim 2, wherein the compression mechanism is a scroll-type compression mechanism comprising a fixed scroll fixed to the housing and a movable scroll revolving relative to the fixed scroll, characterized in that, The rotor has a through hole with an opening on the compression mechanism side and an opening on the inverter side, and the periphery of the opening on the compression mechanism side is chamfered to a greater extent than the periphery of the opening on the inverter side.

4. The inverter-integrated electric compressor as described in any one of claims 1 to 3, characterized in that, A conductive shaft seal member, whose inner circumference contacts the outer circumferential surface of the rotating shaft, is held in the second partition wall portion.

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