Electric compressor

Abstract

To surely and appropriately lubricate a lubrication target portion of an electric compressor.SOLUTION: An electric compressor (1) includes: a housing (2) having a suction port (109) and a discharge port (263) for a working medium; a driving shaft (105); a motor (102) for rotating the driving shaft; and a scroll compression mechanism (204) having a rocking scroll (220) attached to one end of the driving shaft and driven by the driving shaft, and a fixed scroll (210). An oil pump (140) attached to the other end of the driving shaft and driven by the driving shaft supplies oil sucked from an oil reserving space (108) in a lower part of a motor chamber (101) to a lubrication target portion through an oil supply passage (144) inside the driving shaft (105). Oil contained in the working medium compressed by the scroll compression mechanism (204) is separated by an oil separator (261), and is returned to the oil reserving space (108) through an oil return passage (280).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electric compressor. [Background technology]

[0002] Patent Document 1 describes a conventional horizontal scroll compressor. In this compressor, an oil pump provided at the end of the rotating shaft opposite to the scroll compression mechanism draws oil from an oil reservoir in the shell and supplies it to the bearing sliding parts, etc. The oil that lubricates the bearing sliding parts, etc. is returned to the oil reservoir. In the compressor of Patent Document 1, an oil flow path and an oil reservoir are provided at the bottom of the shell, while a refrigerant gas flow path is provided at the upper end of the shell. In other words, the oil is prevented from being sucked into the compression chamber of the scroll compression mechanism together with the refrigerant gas by substantially separating the liquid oil flow path and the refrigerant gas flow path. Patent Document 1 describes that almost no oil flows into the compression chamber.

[0003] However, if almost no oil flows into the compression chamber as described above, there is a concern that the sliding and rolling parts of the fixed scroll and orbiting scroll may be damaged due to insufficient lubrication.

[0004] Furthermore, if almost no oil flows into the compression chamber as described above, it is not possible to ensure airtightness of the compression chamber by oil, which raises concerns that the compression efficiency of the compressor will decrease.

[0005] To solve these concerns, it is possible to adopt a configuration that allows a sufficient amount of oil to be supplied to the compression chamber, for example, a configuration that supplies the compression chamber with the amount of oil necessary for lubrication together with the refrigerant gas. For example, it is possible to provide a refrigerant gas intake port for the compression chamber in the lower region of the shell as well. When a sufficient amount of oil is supplied to the compression chamber, the oil is discharged from the compression chamber together with the compressed refrigerant gas and flows out into the refrigeration cycle outside the compressor. The oil that flows out into the refrigeration cycle circulates through the refrigeration cycle and then flows back into the compressor from the suction port of the compressor.

[0006] During low load operation of the refrigeration cycle, the oil that has flowed out of the compressor is less likely to return to the compressor, and the oil in the oil sump of the shell decreases, which may cause poor lubrication in the compressor. In refrigeration cycles used in bus air conditioners and refrigerated vehicles, the compressor is often located under the vehicle near the engine, and the heat exchanger is often located above the vehicle, such as on the roof, so the total length of the piping in the refrigeration cycle is long. In this case, it becomes even more difficult for the oil that has flowed out of the compressor to return to the compressor, making the above problem more likely to occur.

[0007] Incidentally, even if a sufficient amount of oil were supplied to the compression chamber in the device of Patent Document 1, the same problems as those described above would still exist.

[0008] The horizontal scroll compressor disclosed in Patent Document 2 has an oil separator in the shell (housing) of the compressor, and minimizes the amount of oil contained in the working medium flowing out from the compressor to the refrigeration cycle. In the compressor of Patent Document 2, the oil separated from the working medium by the oil separator is returned to the space near the orbiting scroll in the motor chamber through a through hole formed inside the wall of the fixed scroll. This returned oil is used to lubricate the scroll compression mechanism, the motor unit, and the sliding parts around it. According to the configuration of Patent Document 2, there is no problem that the oil that flows out from the compressor to the refrigeration cycle piping does not return sufficiently. Here, the "working medium" refers to the medium that circulates in the refrigeration cycle including the compressor, and includes refrigerant and oil.

[0009] However, the temperature of the working medium discharged from the scroll compression mechanism during operation is high. Therefore, the temperature of the oil returning via the above-mentioned route is also high. If high-temperature, low-viscosity oil is supplied to the bearing sliding parts, etc., there is a risk of poor lubrication. In addition, if high-temperature oil is supplied to the scroll compression mechanism, a sufficient amount of working medium cannot be supplied to the scroll compression mechanism, and the compression efficiency may decrease. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 2-27186 [Patent Document 2] JP 2014-145353 A Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is to provide an electric compressor that can reliably and appropriately lubricate parts to be lubricated. [Means for solving the problem]

[0012] According to one embodiment of the present invention, there is provided an electric compressor comprising: a housing having a suction port and a discharge port for a working medium; a drive shaft rotatably supported in a motor chamber in the housing; a motor accommodated in the motor chamber in the housing and rotating the drive shaft; a scroll compression mechanism including a fixed scroll fixed to the housing; and a swing scroll attached to one end of the drive shaft and driven by the drive shaft; an oil pump attached to the other end of the drive shaft and driven by the drive shaft, for supplying oil sucked from an oil storage space provided at a lower part of the motor chamber to parts to be lubricated of the scroll compression mechanism via an oil supply passage provided inside the drive shaft; and an oil separator provided in the housing and separating oil contained in the working medium compressed by the scroll compression mechanism from the working medium, and an oil return passage provided in the housing for returning the oil separated by the oil separator to the oil storage space of the motor chamber. Effect of the Invention

[0013] According to the above embodiment, the parts to be lubricated can be reliably and appropriately lubricated. [Brief description of the drawings]

[0014] [Figure 1]1 is an axial cross-sectional view that shows a schematic configuration of an electric compressor according to an embodiment of the present invention. [Diagram 2] 2 is a front view of a wall (partition wall) of the motor chamber on the scroll compression mechanism side as viewed from the motor side (corresponding to the view taken along the line II-II in FIG. 1). FIG. [Diagram 3] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] The electric compressor 1 includes a housing 2. In the illustrated embodiment, the housing 2 is mainly formed of a central motor block 100, a compression and discharge block 200 on the left side of the motor block 100, an electric block 300 on the right side of the motor block 100, and a cover block 400 that closes the right open end of the electric block 300. Each of the blocks 100, 200, 300, 400 is, for example, a die-cast product of an aluminum alloy.

[0017] Adjacent blocks are butted together via a seal member (not shown) as necessary, and are firmly fastened together by screws (not shown). Note that appropriate seal members are provided as necessary not only between adjacent blocks, but also between adjacent members that require sealing, and it goes without saying that the surface pressure required for sealing is ensured between the contacting surfaces of the members by means of, for example, fastening with screws. Please note that such seals are not necessarily shown, and that many fastening means are not shown.

[0018] A motor chamber (motor housing space) 101 is formed inside the motor block 100 to house a motor 102. The motor 102 has a stator 103 and a rotor 104. The rotor 104 has a plurality of permanent magnets (details not shown) embedded therein, and is fixed to a drive shaft (rotating shaft) 105.

[0019] The drive shaft 105 is supported by the housing 2 (the motor block 100 in the illustrated example) so as to be rotatable about a horizontally extending axis of rotation via bearings (rolling bearings) 106 and 107. The stator 103 is supplied with power by an inverter drive circuit 302 provided inside an electric block 300, which causes the rotor 104 to rotate.

[0020] The lower part of the motor chamber 101 serves as an oil storage space 108 in which lubricating oil is stored.

[0021] An upper portion of the housing 2 (an upper portion of the motor block 100 in the illustrated example) is provided with a suction port 109 for taking in the working medium compressed by the electric compressor 1 into the housing 2. The suction port 109 is located at the upper portion of the motor chamber 101 and opens into a space on the electric block 300 side relative to the motor 102.

[0022] The working medium drawn into the compressor contains a very small amount of oil mist in addition to the refrigerant.

[0023] Within the compression and discharge block 200, a scroll chamber (scroll accommodating space) 202, a discharge chamber 240, and an oil separation chamber 260 are provided.

[0024] A scroll compression mechanism 204 is provided in the scroll chamber 202. The scroll compression mechanism 204 has a fixed scroll 210 fixed to the housing 2 (the compression discharge block 200 in the illustrated example) and a swing scroll 220 disposed on one end of the drive shaft 105 and driven by the motor 102.

[0025] The fixed scroll 210 has an end plate 211, a cylindrical outer peripheral wall 212 extending from the outer peripheral edge of the end plate 211 toward the oscillating scroll 220, and a spiral wall 213 extending from the end plate 211 toward the oscillating scroll 220 radially inside the outer peripheral wall 212.

[0026] The orbiting scroll 220 has an end plate 221 and a spiral wall 222 standing from the end plate 221 toward the fixed scroll 210 .

[0027] One end of an eccentric pin 110 is press-fitted into a position offset from the center of rotation of the drive shaft 105. A balance weight 111 is attached to the eccentric pin 110. The balance weight 111 has a cylindrical journal portion 112 and a weight portion 113. The other end of the eccentric pin 110 is fitted into a hole provided in the journal portion 112. Therefore, as the drive shaft 105 rotates, the balance weight 111 performs an eccentric rotational motion around the center of rotation of the drive shaft 105, thereby reducing vibrations generated by the swinging motion of the swing scroll 220.

[0028] The outer peripheral surface of the journal portion 112 is fitted into an inner race of a bearing (rolling bearing) 124. The outer race of the bearing 124 is fitted into a cylindrical bearing receiver 224 that rises from an end plate 221 of the orbiting scroll 220 toward the drive shaft 105.

[0029] The end plate 221 of the orbiting scroll 220 is provided with a plurality of (e.g., eight) cylindrical recesses surrounding the periphery of the bearing support 224, and a cylindrical ring 225 made of a bearing material is press-fitted into each recess. A plurality of (e.g., eight) pins 226 are press-fitted into the wall (partition wall) 118 of the motor block 100 adjacent to the scroll compression mechanism 204. Each ring 225 houses one pin 226. The outer diameter of the pin 226 is smaller than the inner diameter of the ring 225.

[0030] Due to the presence of the bearing 124 and the cooperative action of the ring 225 and the anti-rotation pin 226, the orbiting scroll 220 can only revolve (oscillate), but cannot rotate. This type of so-called "pin and ring" type rotation prevention mechanism is well known as a rotation prevention mechanism in a scroll compression mechanism, so detailed illustration and description will be omitted. Note that the rotation prevention mechanism may be a rotation prevention mechanism using an Oldham ring instead of the above pin and ring type rotation prevention mechanism.

[0031] A wall of the housing 2 (in the illustrated example, the wall of the motor block 100, i.e., the partition wall 118) that separates the motor chamber 101 and the scroll chamber 202 has a plurality of (e.g., six) through holes 130 (hereinafter referred to as "working medium supply holes 130") formed therein.

[0032] A plurality of (e.g., six) working medium supply holes 130 are provided at equal intervals in the circumferential direction at positions slightly inside the cylindrical outer peripheral wall 212 of the fixed scroll 210. The working medium supply holes 130 are provided so that the working medium is introduced into the outermost peripheral portion of the compression chamber 206 formed between the spiral wall 213 of the fixed scroll 210 and the spiral wall 222 of the orbiting scroll 220.

[0033] The working medium supply hole 130 is provided at a position higher than the oil level L (see L in FIG. 2) in the motor chamber 101 during normal operation of the electric compressor 1 so that oil in the oil storage space 108 at the bottom of the motor chamber 101 (particularly high-temperature oil in the oil storage space 108 near the scroll compression mechanism 204) does not directly flow into the scroll compression mechanism 204. In other words, the working medium supply hole 130 is not provided at a position lower than the oil level L.

[0034] The working medium introduced into the motor chamber 101 through the suction port 109 passes through the gap between the outer wall of the motor block 100 and the stator 103, the gap within the stator 103, the gap between the stator 103 and the rotor 104, etc., and flows inside the motor chamber 101 toward the compression and discharge block 200, and then flows into the scroll compression mechanism 204 through the working medium supply hole 130.

[0035] In other words, the motor chamber 101 is provided in a low-pressure region where the working medium, which is sucked through the suction port 109 and has a relatively low pressure and low temperature, flows, and is provided in the space upstream of the scroll compression mechanism 204 .

[0036] During normal operation of the electric compressor 1, oil in the oil storage space 108 at the bottom of the motor chamber 101 is stirred up as the rotor 104 rotates, and becomes mist and floats inside the motor chamber 101. This oil mist is carried by the flow of the working medium and flows into the scroll compression mechanism 204, where it seals and lubricates the contact portions between the fixed scroll 210 and the orbiting scroll 220 that move relative to each other.

[0037] During normal operation of the electric compressor 1, the working medium introduced into the outermost peripheral portion of the compression chamber 206 is compressed while moving toward the center of the scroll as the orbiting scroll 220 orbits. This compressed working medium flows into the discharge chamber 240 through one or more discharge holes 214 (one in the illustrated example) provided in the approximate center of the end plate 211 of the fixed scroll 210. A check valve 215 made of an elastic metal plate is attached to the end plate 211. The check valve 215 opens the discharge hole 214 only when the pressure in the compression chamber 206 at a position corresponding to the discharge hole 214 is high, and closes the discharge hole 214 when the pressure is low.

[0038] The working medium that flows into the discharge chamber 240 flows out into the oil separation chamber 260 through a through hole 241 formed in a wall of the housing 2 (in the illustrated example, the wall of the compression discharge block 200) that separates the discharge chamber 240 and the oil separation chamber 260.

[0039] The oil separation chamber 260 is provided with an oil separation structure (oil separator) 261. In the illustrated embodiment, the oil separation structure 261 has a cylindrical member 262. The working medium that has flowed into the oil separation chamber 260 from the through-hole 241 flows at a high flow rate in a swirling manner around the cylindrical member 262, and at this time, the mist-like oil contained in the working medium is centrifuged.

[0040] The working medium from which the oil has been separated flows through the inside of the cylindrical member 262 to a discharge port 263 opening at the top of the oil separation structure 261, and from there is discharged into a piping system (including a heat exchanger, etc. that constitutes a refrigeration cycle) connected to the electric compressor 1.

[0041] The position where the oil separation structure 261 is provided is not limited to the position shown in FIG. 1, but can be provided at any position in the flow path of the working medium from the discharge hole 214 of the fixed scroll 210 to the discharge port 263 of the housing 2 (compression discharge block 200).

[0042] In other words, the oil separation structure 261 can be provided at any position downstream of the scroll compression mechanism 204 in the high pressure region where a working medium with a relatively high pressure and high temperature flows.

[0043] The oil separated from the working medium flows down along the inner wall surface of the oil separation chamber 260 and falls into an oil storage space 264 provided in the lower part of the oil separation chamber 260 .

[0044] The oil storage space 264 of the oil separation chamber 260 communicates with the oil storage space 108 of the motor chamber 101 via an oil return passage 280 .

[0045] In the illustrated embodiment, the oil return passage 280 is made up of the following elements: (First element) A horizontal hole 281 drilled in the wall of the compression / discharge block 200, which extends horizontally from the oil storage space 264 toward the end plate 211 of the fixed scroll 210. (Second element) An oblique hole 282 extending obliquely in the end plate 211 of the fixed scroll 210 (Third element) A horizontal hole 283 extending horizontally is drilled in the outer peripheral wall 212 of the fixed scroll 210. (Fourth element) A vertical groove 284 extending vertically is formed on the end surface of the wall of the motor block 100 on the fixed scroll 210 side. (Fifth element) A horizontal hole 285 extending horizontally and terminating in an oil return hole 286 opening into the oil storage space 108 is drilled in the wall of the motor block 100 on the side of the fixed scroll 210.

[0046] The oil return passage 280 is provided with a pressure reducing mechanism using an orifice member (not shown) for narrowing the hole diameter (oil flow passage area).

[0047] For example, the orifice member can be provided in the horizontal hole 283, and by using an orifice member having a precisely machined inner diameter, the pressure of the oil flowing from the oil separation chamber 260 in the high pressure region through the oil return passage 280 into the motor chamber 101 in the low pressure region can be precisely restricted by the pressure reducing mechanism.

[0048] A filter 287 for removing foreign matter contained in the oil is provided on the upstream side of the orifice member, for example, at the entrance of the horizontal hole 281.

[0049] The oil is prevented from leaking out of the oil return passage 280 between the oil storage space 264 of the oil separation chamber 260 and the oil storage space 108 of the motor chamber 101. Specifically, for example, appropriate sealing is provided using a sealing member such as a sheet gasket or an O-ring as necessary. Such a sealing member may be provided, for example, between the end plate 211 of the fixed scroll 210 and the wall of the compression / discharge block 200, and between the tip of the outer circumferential wall 212 of the fixed scroll 210 and the wall of the motor block 100.

[0050] The path of the oil return passage 280 that connects the oil storage space 264 of the oil separation chamber 260 and the oil storage space 108 of the motor chamber 101 is not limited to the one shown in the figure. For example, the oil return passage 280 does not have to penetrate the inside of the wall body (end plate 211, outer peripheral wall 212) of the fixed scroll 210, and may penetrate the wall body of the compression discharge block 200 below the fixed scroll 210, for example.

[0051] Next, lubrication of the parts around the drive shaft 105 will be described.

[0052] An oil pump 140 driven by the drive shaft 105 is attached to the end of the drive shaft 105 opposite the scroll compression mechanism 204. The oil pump 140 may be, for example, a trochoid oil pump, but is not limited to this. The oil pump 140 is shown in a simplified form in FIG.

[0053] An oil suction hole 142 is provided in the oil storage space 108 of the motor chamber 101. This oil suction hole 142 is provided at a height position that is always lower than the oil level L in the oil storage space 108 during normal operation of the electric compressor 1.

[0054] Oil is sucked into the oil pump 140 from the oil suction hole 142 through an oil suction passage 143. The oil suction passage 143 is, for example, a metal tube connected to a suction port of the oil pump 140. Alternatively, at least a portion of the oil suction passage 143 may be formed by a hole drilled in the wall of the motor block 100.

[0055] A discharge port of oil pump 140 communicates with an oil passage (oil supply passage) 144 drilled in drive shaft 105. Oil passage 144 supplies oil to portions requiring lubrication between members that roll or slide as drive shaft 105 rotates.

[0056] A first branch passage 145 branches off from the oil passage (main oil passage) 144, and oil is supplied from this first branch passage 145 to a space 146 facing one end of the bearing 107. The oil flows through the bearing 107 to lubricate the bearing 107, and then drops from the other end of the bearing 107 into the oil storage space 108.

[0057] Between the bearing 106 and the bearing 124, a cavity 150 for allowing the rotational movement of the weight portion 113 of the balance weight 111 is formed in the wall of the motor block 100 on the scroll compression mechanism 204 side.

[0058] A second branch passage 147 branches off from the oil passage 144, and oil is supplied from this second branch passage 147 to the space between the bearing 106 and the weight portion 113 of the balance weight 111 (a part of the above-mentioned cavity 150). Some of this oil flows into the bearing 106 to lubricate the bearing 106, and then drops into the oil storage space 108 from the end of the bearing 106 opposite the balance weight 111. The remainder of the oil supplied from the second branch passage 147 flows to the bottom of the cavity 150.

[0059] The oil passage (main passage) 144 is bent midway and then opens at the end surface of the drive shaft 105. In other words, the oil passage 144 has an oil discharge port 148 that opens at the end surface of the drive shaft 105.

[0060] The weight portion 113 of the balance weight 111 is provided with a through hole 114. This through hole 114 extends from a first surface facing the end face having the oil discharge port 148 of the drive shaft 105 to a second surface on the opposite side. The oil discharge port 148 is provided so as to face the opening of the through hole 114 (see also FIG. 3) in the first surface of the weight portion 113. The through hole 114 opens in the second surface so as to face the side of the bearing 124. Therefore, the oil discharged from the oil discharge port 148 is efficiently supplied to the bearing 124. The oil that lubricates the bearing 124 falls to the bottom of the cavity 150.

[0061] As the orbiting scroll 220 oscillates, the end face of the end plate 211 of the orbiting scroll 220 slides against the thrust plate 160 made of a highly wear-resistant material that is sandwiched between the opposing surfaces of the motor block 100 and the compression / discharge block 200. The oil that falls to the bottom of the cavity 150 wets the end face of the end plate 211 of the orbiting scroll 220, and also contributes to lubrication of the sliding surface between the end face and the thrust plate 160.

[0062] In addition, a part of the oil that has wetted the end face of the end plate 211 of the orbiting scroll 220 may enter between the fixed scroll 210 and the orbiting scroll 220 and contribute to lubrication between them. However, in this embodiment, lubrication between the fixed scroll 210 and the orbiting scroll 220 is mainly performed by mist-like oil contained in the working medium supplied from the working medium supply hole 130.

[0063] The oil that has accumulated at the bottom of the cavity 150 passes through an oil passage 151 that extends downward (diagonally downward in the illustrated example) from the bottom of the cavity 150 and falls into the oil storage space 108.

[0064] Since the working medium is adiabatically compressed in the compression chamber 206 of the scroll compression mechanism 204, the working medium is at a high temperature immediately after leaving the scroll compression mechanism 204, and therefore the oil separated from the working medium and accumulated in the oil separation chamber 260 is also at a high temperature. Therefore, the oil flowing from the oil separation chamber 260 through the oil return passage 280 into the oil storage space 108 of the motor chamber 101 is also at a relatively high temperature.

[0065] In this embodiment, the distance between the oil return hole 286 of the oil return passage 280 and the oil suction hole 142 is sufficiently large so that the relatively hot oil that flows from the oil separation chamber 260 through the oil return passage 280 into the oil storage space 108 of the motor chamber 101 is not immediately sucked into the oil pump 140 through the oil suction hole 142.

[0066] Specifically, the oil return hole 286 and the oil suction hole 142 are provided near both ends of the motor chamber 101. In other words, the oil return hole 286 and the oil suction hole 142 are located on opposite sides of the motor 102 in the axial direction of the drive shaft 105.

[0067] In this way, the temperature is made uniform by the diffusion of the oil in the oil storage space 108, and the oil whose temperature has been reduced by the heat dissipation from the oil in the oil storage space 108 to the outside through the wall of the motor block 100 is sucked into the oil pump 140. This makes it possible to prevent high-temperature, low-viscosity oil that is not suitable for lubrication from being supplied to the parts to be lubricated, such as bearings. This makes it possible to prevent problems such as wear and damage from occurring in the parts to be lubricated.

[0068] As described above, the working medium supply hole 130 is provided at a position higher than the oil level L (see L in FIG. 2) in the motor chamber 101, so that the high-temperature oil that flows out from the oil return hole 286 into the motor chamber 101 does not immediately flow into the scroll compression mechanism 204. If high-temperature, low-viscosity oil is supplied to the scroll compression mechanism 204, there is a risk that the scroll compression mechanism 204 may be damaged due to poor lubrication. Furthermore, if high-temperature oil is supplied to the scroll compression mechanism 204, there is a risk that the working medium sucked into the scroll compression mechanism 204 may be heated, resulting in a decrease in compression efficiency. According to this embodiment, it is possible to prevent such problems from occurring.

[0069] In this embodiment, before the working medium discharged from the scroll compression mechanism 204 flows out of the housing 2 through the discharge port 263, the oil in the working medium is separated by the oil separation structure 261, and the separated oil is returned to the oil storage space 108 of the motor chamber 101. Therefore, the amount of oil that flows out into the refrigeration cycle connected to the electric compressor 1 is extremely small, and a sufficient amount of oil is always present in the oil storage space 108. Therefore, there is no shortage of oil to lubricate the components in the electric compressor 1. [Explanation of symbols]

[0070] 1 Electric compressor 2. Housing 101 Motor Room 102 Motor 105 Drive shaft 106, 107 Drive shaft bearings 108 Oil storage space 109 Suction port 111,124,225 Parts attached to the oscillating scroll 130 Working medium supply hole 140 Oil pump 142 Oil suction hole 144 Oil supply passage 204 Scroll Compression Mechanism 210 Fixed Scroll 214 Discharge hole 220 Swinging Scroll 263 Discharge port 261 Oil separator (oil separation structure) 280 Oil return passage 286 Oil return hole

Claims

1. a housing (2) having a working medium intake port (109) and a discharge port (263); A drive shaft (105) rotatably supported in a motor chamber (101) in the housing (2); a motor (102) accommodated in the motor chamber (101) in the housing (2) and rotating the drive shaft (105); a scroll compression mechanism (204) including a fixed scroll (210) fixed to the housing (2) and an orbiting scroll (220) attached to one end of the drive shaft (105) and driven by the drive shaft (105); an oil pump (140) attached to the other end of the drive shaft (105), driven by the drive shaft (105), and configured to supply oil drawn from an oil storage space (108) provided in a lower portion of the motor chamber (101) to portions to be lubricated (106, 107, 111, 124, 220, 225) of the scroll compression mechanism (204) via an oil supply passage (144) provided inside the drive shaft (105); an oil separator (261) provided in the housing (2) and configured to separate oil from the working medium compressed by the scroll compression mechanism (204); An oil return passage (280) for returning the oil separated by the oil separator (261) to the oil storage space (108) of the motor chamber (101) is provided in the housing (2).

2. 2. The electric compressor according to claim 1, wherein the lubrication target portions (106, 107, 111, 124, 220, 225) to which oil is supplied via the oil supply passage (144) inside the drive shaft (105) do not include a sliding surface between the fixed scroll (210) and the orbiting scroll (220), and the sliding surface is lubricated by oil contained in the working medium sucked into the scroll compression mechanism (204).

3. 2. The electric compressor according to claim 1, wherein the oil separated in the oil separator is returned to the oil storage space in the motor chamber through the oil return passage without passing through the parts to be lubricated.

4. The oil return passage (280) terminates at an oil return hole (286) that opens into the motor chamber (101); The oil pump (140) draws oil from an oil suction hole (142) that opens in the oil storage space (108) in the motor chamber (101), 2. The electric compressor according to claim 1, wherein the oil return hole (286) and the oil suction hole (142) are provided on opposite sides of the motor (102).

5. The housing (2) has a partition wall (118) that separates the motor chamber (101) from a space in which the scroll compression mechanism (204) is disposed, the partition wall (118) is provided with one or more working medium supply holes (130) for passing the working medium that has flowed from the suction port (109) into the motor chamber (101) toward a space in which the scroll compression mechanism (204) is disposed; The oil return passage (280) terminates at an oil return hole (286) provided in the partition wall (118) that opens into the motor chamber (101); The electric compressor according to claim 1 , wherein the working medium supply hole (130) is located above the oil return hole (286).

6. 6. The electric compressor according to claim 5, wherein the working medium supply hole (130) is provided at a position higher than a liquid level of oil in the oil storage space (108) of the motor chamber (101) during normal operation of the electric compressor (1).

7. 2. The electric compressor according to claim 1, wherein at least a portion of the oil return passage (280) penetrates a wall that constitutes the fixed scroll (210).

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