Electric compressor

Abstract

[Problem] To reduce the size and weight of a main bearing for supporting a drive shaft that drives a compression mechanism. [Solution] An electric compressor (10) comprises a drive shaft (61) that drives a compression mechanism (70), a motor (60) that drives the drive shaft (61), a motor housing (20) that defines a motor chamber (21) into which a refrigerant sucked from an external refrigeration cycle is introduced, a compression mechanism housing (30) having a discharge chamber (32) from which the compressed refrigerant is discharged, and a pressure equalization means (120). The drive shaft (61) has a first end surface (61c) disposed in the motor housing (20), a second end surface (61d) disposed in the compression mechanism housing (30), and a portion (61a) supported by a rolling bearing (111) between the motor (60) and the compression mechanism (70). The pressure equalization means (120) equalizes the pressure acting on the first end surface (61c) and the second end surface (61d).

Description

Electric compressor

[0001] The present invention relates to an improved technique for an electric compressor including a compression mechanism that compresses a refrigerant and a motor that drives the compression mechanism.

[0002] Among electric compressors, there is a rolling piston type rotary compressor equipped with a compression mechanism having multiple compressors. Such compression mechanisms include a parallel compression mechanism (e.g., a twin compression mechanism) in which multiple compressors are arranged in parallel to perform compression, and a multi-stage compression mechanism in which multiple compressors are arranged in series to perform compression. For example, the technology disclosed in Patent Document 1 is known as an electric compressor equipped with a parallel compression mechanism.

[0003] According to the electric compressor with a horizontal parallel compression mechanism known from Patent Document 1, refrigerant drawn into a housing is compressed by two compression mechanisms, and the discharged refrigerant is combined and discharged in a discharge silencer chamber. This electric compressor has a motor chamber that can accommodate a motor and draw refrigerant from the outside, a compression mechanism chamber that accommodates the compression mechanisms, and a discharge chamber from which refrigerant compressed by the compression mechanisms is discharged. The motor can drive the compression mechanisms via a motor shaft (drive shaft). The drive shaft is rotatably supported by main bearings made of plain bearings at a portion between the motor and the compression mechanisms and at an end on the discharge chamber side.

[0004] However, in a sliding bearing, the drive shaft is rotatably supported via lubricating oil introduced between the drive shaft and the sliding bearing, and so there is a limit to how much power loss can be reduced due to the viscosity of the lubricating oil.On the other hand, as disclosed in Patent Document 2, for example, rolling bearings are known as a structure for supporting a drive shaft.

[0005] The electric compressor with a parallel compression mechanism known from Patent Document 2 has a vertical configuration in which the drive shaft is oriented vertically, as shown in FIG. 11 of Patent Document 2. The drive shaft is rotatably supported by rolling bearings at the section between the motor and the compression mechanism and at its lowest end. Therefore, it is conceivable to replace the plain bearing of Patent Document 1 with the rolling bearing of Patent Document 2. If the main bearing located between the motor and the compression mechanism is configured with a rolling bearing, the rotation of the drive shaft can be supported by the rolling bearing, thereby reducing power loss. Furthermore, if the rolling bearing is configured with a ball bearing, the axial movement of the drive shaft can be restricted by the rolling bearing.

[0006] JP 2021-156203 A JP 2007-291996 A

[0007] However, in the electric compressor with a parallel compression mechanism known from Patent Document 1, one end face (first end face) of the drive shaft communicates with the motor chamber, and the other end face (second end face) communicates with the discharge chamber. The motor chamber is a low-pressure region that can draw in refrigerant from the outside, and the discharge chamber is a high-pressure region that discharges compressed refrigerant. Low pressure acts on the first end face, and high pressure acts on the second end face. A pressure difference occurs between the pressure acting on the first end face and the pressure acting on the first end face. As a result, an axial force (axial load) acts on the drive shaft from the second end face to the first end face.

[0008] In particular, when R744 (carbon dioxide) is used as the refrigerant, the refrigerant pressure is very high, which causes a large axial force to act on the rolling bearings. This requires large-sized rolling bearings to withstand both radial and axial loads, which is disadvantageous in terms of reducing the size and weight of the electric compressor.

[0009] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a technology that can reduce the size and weight of a main bearing for supporting a drive shaft that drives a compression mechanism.

[0010] In the following description, reference numerals in the accompanying drawings are placed in parentheses to facilitate understanding of the present invention, but the present invention is not limited to the illustrated forms.

[0011] According to the present disclosure, there is provided an electric compressor (10; 200; 300) comprising: a compression mechanism (70); a drive shaft (61) that drives the compression mechanism (70); a motor (60) that drives the drive shaft (61); a motor housing (20) that houses the motor (60) and defines a motor chamber (21) into which a refrigerant drawn from an external refrigeration cycle is introduced; and a compression mechanism housing (30) that houses the compression mechanism (70) and has a discharge chamber (32) from which the refrigerant compressed by the compression mechanism (70) is discharged, The drive shaft (61) has a first end face (61c) of both axial end faces (61c, 61d) disposed within the motor housing (20), a second end face (61d) of both axial end faces (61c, 61d) disposed within the compression mechanism housing (30), and a portion (61a) between the motor (60) and the compression mechanism (70) is rotatably supported by a rolling bearing (111) capable of bearing a radial load and an axial load, and the electric compressor (10; 200; 300) further includes pressure equalizing means (120) for equalizing pressure acting on both end faces (61c, 61d) of the drive shaft (61).

[0012] Preferably, the pressure equalizing means (120) is configured by a through hole (121) that passes through the drive shaft (61) in the axial direction so as to allow communication between the both end faces (61c, 61d) of the drive shaft (61).

[0013] More preferably, the through hole (121) has a first opening (122) that opens to the first end face (61c) of the both end faces (61c, 61d) of the drive shaft (61) and a second opening (123) that opens to the second end face (61d), and at least one of the first opening (122) and the second opening (123) is isolated from the motor chamber (21) or the discharge chamber (32).

[0014] More preferably, the first opening (122) communicates with the motor chamber (21), and the second opening (123) is isolated from the discharge chamber (32).

[0015] More preferably, the electric compressor (10) further includes a side plate (103) provided to close an end surface (94a) of the compression mechanism (70) on the discharge chamber (32) side, the side plate (103) having a cylindrical shaft support boss portion (115) protruding toward the discharge chamber (32), the shaft support boss portion (115) rotatably supporting an end portion (61b) of the drive shaft (61) on the discharge chamber (32) side, an outer peripheral surface (115b) of the shaft support boss portion (115) fitting into a recess (124a) formed inside the compression mechanism housing (30), The gap between the outer peripheral surface (115b) of the shaft support boss portion (115) and the inner peripheral surface of the recess (124a) is sealed by a sealing member (125), thereby isolating the second opening (123) of the drive shaft (61) from the discharge chamber (32).

[0016] In another preferred example, the electric compressor (200) further includes a side plate (103) provided to close an end face (94 a) of the compression mechanism (70) on the discharge chamber (32) side, an end (61 b) of the drive shaft (61) on the discharge chamber (32) side penetrates the side plate (103) and is fitted into a recess (124 a) formed inside the compression mechanism housing (30), and a seal member (225) seals between an outer peripheral surface (61 e) of the end (61 b) and an inner peripheral surface of the recess (124 a), thereby isolating the second opening (123) of the drive shaft (61) from the discharge chamber (32).

[0017] In another preferred example, the electric compressor (300) further includes a side plate (103) provided to close an end face of the compression mechanism (70) on the discharge chamber (32) side, the side plate (103) having a cylindrical boss portion (315) with a bottom that bulges out toward the discharge chamber (32), and an end portion (61 b) of the drive shaft (61) on the discharge chamber (32) side is rotatably supported by a sliding bearing (116) fitted in a recess (315 a) formed in the boss portion (315) or directly in the recess (315 a), thereby isolating the second opening (123) of the drive shaft (61) from the discharge chamber (32).

[0018] In another preferred example, the electric compressor (10; 200; 300) further includes a partition member (40) provided between the motor housing (20) and the compression mechanism housing (30), the partition member (40) having a cylindrical boss portion (113) supporting the rolling bearing (111) on a surface (40a) facing the motor chamber (21), the outer diameter (D1) of the boss portion (113) being set smaller than the inner diameter (D2) of the coil end (63a) of the cylindrical stator (63) of the motor (60), and the boss portion (113) overlapping the coil end (63a) in the axial direction of the drive shaft (61).

[0019] Preferably, the electric compressor (10; 200; 300) is of a horizontally placed type in which the drive shaft (61) is arranged horizontally.

[0020] Preferably, the electric compressor (10; 200; 300) uses R744 as the refrigerant in the refrigeration cycle.

[0021] The present invention can provide a technique that can reduce the size and weight of a main bearing for supporting a drive shaft that drives a compression mechanism.

[0022] Fig. 5 is a cross-sectional view taken along the centerline of an electric compressor according to a first embodiment. Fig. 6 is an enlarged view of the compression mechanism and its surroundings shown in Fig. 1. Fig. 7 is a cross-sectional view of the first compression mechanism shown in Fig. 2, seen from the axial direction of the drive shaft. Fig. 8 is a cross-sectional view of the second compression mechanism shown in Fig. 2, seen from the axial direction of the drive shaft. Fig. 9 is an enlarged view of the drive shaft and its surroundings shown in Fig. 1. Fig. 10 is a cross-sectional view of the drive shaft shown in Fig. 5. Fig. 11 is a cross-sectional view of the isolation section and its surroundings of an electric compressor according to a second embodiment. Fig. 12 is a cross-sectional view of the isolation section and its surroundings of an electric compressor according to a third embodiment.

[0023] An embodiment of the present invention will be described below with reference to the accompanying drawings. Note that the embodiment shown in the accompanying drawings is an example of the present invention, and the present invention is not limited to this embodiment. In the drawings, "Up" indicates the top, and "Dn" indicates the bottom.

[0024] First Embodiment An electric compressor 10 according to a first embodiment will be described with reference to FIGS. 1 to 6. FIG.

[0025] Example 1 Fig. 1 shows the overall configuration of an electric compressor 10 used in a refrigeration cycle using R744 (carbon dioxide) as a refrigerant. In addition to PAG, POE, etc., can be used as the oil for the refrigeration cycle. This electric compressor 10 includes a housing 11, a motor 60, and a compression mechanism 70 driven by the motor 60. This electric compressor 10 has the configuration of a so-called horizontally mounted electric compressor, in which the compression mechanism 70 is disposed, for example, next to the motor 60.

[0026] The housing 11 is configured to be installable horizontally and includes a motor housing 20, a compression mechanism housing 30 arranged beside the motor housing 20, and a partition member 40 (partition block 40) sandwiched between the motor housing 20 and the compression mechanism housing 30. The motor housing 20, the compression mechanism housing 30, and the partition member 40 are made by casting or forging metal materials such as aluminum (including aluminum alloys).

[0027] The motor housing 20 is a cylindrical member with a bottom and a motor chamber 21 that houses the motor 60. One axial end of the motor housing 20 is closed by a bottom wall 22. The other axial end of the motor housing 20 is completely open. The motor housing 20 also has a suction port 23 that draws refrigerant into the motor chamber 21 from an external refrigeration cycle (not shown).

[0028] The compression mechanism housing 30 is a cylindrical member with a bottom that is open on the motor housing 20 side and has a compression mechanism chamber 31 on the open side and a discharge chamber 32 on the closed side. The compression mechanism chamber 31 and the discharge chamber 32 are continuous in the axial direction of the compression mechanism housing 30 and communicate with each other. The compression mechanism chamber 31 houses the compression mechanism 70. The discharge chamber 32 is a space from which the refrigerant compressed by the compression mechanism 70 is discharged.

[0029] One axial end of the compression mechanism housing 30 is closed by a bottom wall 34. This bottom wall 34 is, for example, formed integrally with the compression mechanism housing 30. The other axial end of the compression mechanism housing 30 is completely open. In this manner, the open end face of the compression mechanism housing 30 is closed by a partition member 40.

[0030] The partition member 40 is a disk-shaped member that separates the motor chamber 21 and the compression mechanism chamber 31, and is sandwiched between the open end face of the motor housing 20 and the open end face of the compression mechanism housing 30.

[0031] The gap between the end face of the motor housing 20 and the partition member 40, and the gap between the end face of the compression mechanism housing 30 and the partition member 40, are sealed by sealing members (not shown), such as gaskets or O-rings. The partition member 40 is restricted in both relative rotation and axial movement with respect to the motor housing 20 and the compression mechanism housing 30. For example, the partition member 40 is fixed integrally with the motor housing 20 and the compression mechanism housing 30 by fastening members 51, such as bolts.

[0032] Next, a description will be given of the motor 60. As shown in Fig. 1, the motor 60 includes an output shaft 61, a rotor 62 fixed to the output shaft 61, and a cylindrical stator 63 surrounding the rotor 62.

[0033] The output shaft 61 has its center of rotation on the axial center line CL1 of the motor housing 20, extends from the motor chamber 21 toward the compression mechanism chamber 31, and penetrates the partition member 40. The compression mechanism 70 is drivingly connected to the output shaft 61. In other words, the output shaft 61 of the motor 60 can be arranged sideways (for example, horizontally) and also serves as the drive shaft 61 that drives the compression mechanism 70. Hereinafter, the output shaft 61 of the motor 60 may be referred to as the "drive shaft 61."

[0034] The axial center line CL1 of the motor housing 20 may be referred to as the "center line CL1 of the output shaft 61 (drive shaft 61)." The output shaft 61 of the motor 60 may be configured as a separate member from the drive shaft of the compression mechanism 70. In that case, the output shaft 61 of the motor 60 is connected to the drive shaft of the compression mechanism 70 by a connecting member such as a coupling.

[0035] The rotor 62 is rotatable about a center line CL1 of the output shaft 61. The stator 63 is disposed radially outward of the rotor 62 and is fixed to an inner peripheral surface 20a of the motor housing 20.

[0036] As shown in FIG. 2 , the partition member 40 has a shaft insertion hole 41 through which the drive shaft 61 can be inserted. The shaft insertion hole 41 is coaxial with the center line CL1 of the drive shaft 61. The partition member 40 also has a shaft seal 42. The shaft seal 42 is a member that seals between the shaft insertion hole 41 and the outer peripheral surface of the drive shaft 61, and is configured, for example, by a lip seal. The shaft seal 42 can prevent refrigerant present in the compression mechanism chamber 31 and the discharge chamber 32 from leaking into the motor chamber 21 through the shaft insertion hole 41. The shaft seal 42 is located on the compression mechanism chamber 31 side of the partition member 40.

[0037] Next, the compression mechanism 70 will be described. As shown in FIG. 2 , the compression mechanism 70 is configured as a parallel compression mechanism (e.g., a twin compression mechanism) in which, for example, a first compression mechanism 80 and a second compression mechanism 90 are arranged in parallel to perform compression. The first compression mechanism 80 and the second compression mechanism 90 have substantially the same configuration. Both the first and second compression mechanisms 80, 90 are configured as so-called rolling piston rotary compressors that perform compression using rotating bodies 82, 92 (pistons 82, 92) and cylinders 84, 94 that rotate. The first compression mechanism 80 is located on the partition member 40 side of the compression mechanism chamber 31. The second compression mechanism 90 is located on the opposite side of the partition member 40 from the first compression mechanism 80 in the compression mechanism chamber 31.

[0038] 2 and 3 , the first compression mechanism 80 includes a first eccentric shaft 81 that is integral with or provided integrally with the drive shaft 61, a cylindrical first piston 82 (first rotor 82) that is fitted onto the first eccentric shaft 81, and a flat first cylinder 84 that has a first cylinder chamber 83 that allows rotational movement of the first piston 82. A center line CL2 of the first eccentric shaft 81 is offset from a center line CL1 of the drive shaft 61. Relative rotation of the first cylinder 84 with respect to the compression mechanism housing 30 is restricted.

[0039] The first cylinder chamber 83 is a circular hole concentric with the center line CL1 of the drive shaft 61 and penetrates the first cylinder 84 in the axial direction. The first cylinder 84 further has a first suction passage 86 and a first discharge passage 87 that communicate with the first cylinder chamber 83. The first suction passage 86 is made up of a first axial passage 86a that penetrates the first cylinder 84 in the axial direction and a first radial passage 86b that communicates from the first axial passage 86a to the first cylinder chamber 83. The first discharge passage 87 opens to the surface of the first cylinder 84 that faces the partition member 40. As shown in FIGS. 2 and 3 , the first suction passage 86 and the first discharge passage 87 are located above the drive shaft 61, which is oriented horizontally.

[0040] The outer diameter of the first piston 82 is smaller than the inner diameter of the first cylinder chamber 83. A vertical plate-shaped first vane 88 is in contact with the outer peripheral surface of the first piston 82 and is movable back and forth. The tip of the first vane 88 is pressed against the outer peripheral surface of the first piston 82 by a first spring 89. The first vane 88 divides the first cylinder chamber 83 into a first suction chamber 83a and a first compression chamber 83b. The first suction chamber 83a communicates with a first suction passage 86. The first compression chamber 83b communicates with a first discharge passage 87. The first piston 82 revolves within the first cylinder chamber 83. Refrigerant introduced from the first suction passage 86 to the first suction chamber 83a is compressed by the orbital motion of the first piston 82 and is discharged from the first compression chamber 83b through the first discharge passage 87.

[0041] 2 and 4 , similar to the first compression mechanism 80, the second compression mechanism 90 includes a second eccentric shaft 91 that is integral with or provided integrally with the drive shaft 61, a cylindrical second piston 92 (second rotor 92) that is fitted onto the second eccentric shaft 91, and a flat-plate-shaped second cylinder 94 that has a second cylinder chamber 93 that allows rotational movement of the second piston 92. Relative rotation of the second cylinder 94 with respect to the compression mechanism housing 30 is restricted.

[0042] The center line CL3 of the second eccentric shaft 91 is offset from the center line CL1 of the drive shaft 61. The center line CL2 of the first eccentric shaft 81 and the center line CL3 of the second eccentric shaft 91 are located symmetrically with respect to the center line CL1 of the drive shaft 61.

[0043] The second cylinder chamber 93 is a circular hole concentric with the center line CL1 of the drive shaft 61 and penetrates the second cylinder 94 in the axial direction. The second cylinder 94 further has a second suction passage 96 and a second discharge passage 97 that communicate with the second cylinder chamber 93. The second suction passage 96 is made up of a second axial passage 96a that penetrates the second cylinder 94 in the axial direction and a second radial passage 96b that communicates from the second axial passage 96a to the second cylinder 94. The second discharge passage 97 opens to the surface of the second cylinder 94 that faces the discharge chamber 32. As shown in FIGS. 2 and 4, the second suction passage 96 and the second discharge passage 97 are located above the drive shaft 61, which is oriented horizontally.

[0044] The outer diameter of the second piston 92 is smaller than the inner diameter of the second cylinder chamber 93. A vertical plate-shaped second vane 98 is movably attached to the outer peripheral surface of the second piston 92. The tip of the second vane 98 is pressed against the outer peripheral surface of the second piston 92 by a second spring 99. The second vane 98 divides the second cylinder chamber 93 into a second suction chamber 93a and a second compression chamber 93b. The second suction chamber 93a communicates with a second suction passage 96. The second compression chamber 93b communicates with a second discharge passage 97. The second piston 92 revolves within the second cylinder chamber 93. Refrigerant introduced from the second suction passage 96 into the second suction chamber 93a (second cylinder chamber 93) is compressed by the orbital motion of the second piston 92 and discharged from the second compression chamber 93b through the second discharge passage 97.

[0045] 2, the first cylinder chamber 83 is closed on the partition member 40 side by a flat first closing plate 101. This first closing plate 101 is sandwiched between the partition member 40 and the first cylinder 84. Furthermore, the first closing plate 101 has a first through hole 101a communicating with the first suction passage 86 and a second through hole 101b communicating with the first discharge passage 87. The first through hole 101a and the second through hole 101b penetrate the first closing plate 101 in the plate thickness direction.

[0046] The first axial passage 86a of the first suction passage 86 passes through a first through-hole 101a of a first closing plate 101 and communicates with the suction passage 43 of the partition member 40. This suction passage 43 penetrates the partition member 40 in the axial direction of the motor housing 20. Therefore, the first cylinder chamber 83 communicates with the suction port 23 (see FIG. 1) of the motor housing 20 via the first suction passage 86, the first through-hole 101a of the first closing plate 101, the suction passage 43 of the partition member 40, and the motor chamber 21.

[0047] The partition member 40 has a communication groove 44 (discharge recess 44) that communicates between the second through-hole 101b of the first closure plate 101 and the compression mechanism chamber 31. This communication groove 44 is formed on the surface of the partition member 40 facing the first closure plate 101. A discharge valve 45 that opens and closes the opening of the second through-hole 101b is provided in the communication groove 44. This discharge valve 45 is a check valve, such as a reed valve, that allows refrigerant to flow only from the first discharge passage 87 to the communication groove 44. The first cylinder chamber 83 communicates with the discharge chamber 32 via the first discharge passage 87, the second through-hole 101b, the communication groove 44, and the compression mechanism chamber 31.

[0048] The space between the first cylinder chamber 83 and the second cylinder chamber 93 is closed by a flat second closing plate 102. This second closing plate 102 is sandwiched between the first cylinder 84 and the second cylinder 94. The second closing plate 102 has a through hole 102a that connects the first axial passage 86a of the first cylinder 84 and the first axial passage 96a of the second cylinder 94. This through hole 102a penetrates the second closing plate 102 in the thickness direction. The second cylinder chamber 93 is in communication with the suction port 23 of the motor housing 20 (see FIG. 1 ) via the second suction passage 96 of the second cylinder 94, the through hole 102a of the second closing plate 102, the first suction passage 86 of the first cylinder 84, the first through hole 101a of the first closing plate 101, the suction passage 43 of the partition member 40, and the motor chamber 21.

[0049] The surface of the second cylinder chamber 93 facing the discharge chamber 32 of the compression mechanism housing 30 (the bottom wall 34 side) is closed by a flat third closure plate 103. More specifically, the third closure plate 103 is a side plate provided to close the end face 94a of the second cylinder 94 on the axial side opposite the first cylinder 84, i.e., the end face 94a of the compression mechanism 70 facing the discharge chamber 32. The third closure plate 103 may be referred to as the "side plate 103" as appropriate.

[0050] As is clear from the above description, the discharge chamber 32 is a space within the compression mechanism housing 30 that is surrounded by the bottom wall 34 and the third closure plate 103 (side plate 103).

[0051] The third closure plate 103 has a through-hole 103a communicating with the discharge chamber 32. The through-hole 103a penetrates the third closure plate 103 in the plate thickness direction. A discharge valve 104 is provided in the discharge chamber 32 to open and close the opening of the through-hole 103a. The discharge valve 104 is a check valve, such as a reed valve, that allows refrigerant gas to flow only from the second discharge passage 97 to the discharge chamber 32. The second cylinder chamber 93 communicates with the discharge chamber 32 via the second discharge passage 97 and the through-hole 103a. The discharge chamber 32 communicates with the oil separation chamber 35. Refrigerant in the second compression mechanism 90 can flow into the oil separation chamber 35 through the second discharge passage 97, the communication hole 143a, and the discharge chamber 32.

[0052] Furthermore, the compression mechanism housing 30 has an oil separation chamber 35 that separates oil from the refrigerant compressed by the compression mechanism 70, and a discharge port 36 that discharges the gaseous refrigerant from which the oil has been separated by this oil separation chamber 35 to the outside.

[0053] The first cylinder 84, the second cylinder 94, the first closing plate 101, the second closing plate 102, and the third closing plate 103 are fixed to the partition member 40 by fastening members such as bolts (not shown).

[0054] Next, the drive shaft 61 and the support structure that supports the drive shaft 61 will be described in detail.

[0055] As shown in Figure 5, the drive shaft 61 is rotatably supported by a first bearing 111 (main bearing 111) provided in the partition member 40 and a second bearing 112 (sub-bearing 112) provided in the bottom wall 22 of the motor housing 20.

[0056] The first bearing 111 is a rolling bearing capable of receiving radial and axial loads, such as a ball bearing or roller bearing, and supports a portion 61a (see also FIG. 1 ) of the drive shaft 61 between the motor 60 and the compression mechanism 70. The inner ring of the first bearing 111 is fixed to the drive shaft 61 by an interference fit such as press fitting.

[0057] The partition member 40 has a cylindrical first boss portion 113 (first shaft support portion 113) for mounting and supporting the first bearing 111. That is, the partition member 40 has the first boss portion 113 on its surface 40a facing the motor chamber 21. This first boss portion 113 protrudes from the partition member 40 toward the motor chamber 21. As a result, the first bearing 111 is located in the motor chamber 21.

[0058] 2, the outer diameter D1 of the first boss portion 113 is set to be smaller than the inner diameter D2 of the coil end 63a of the stator 63. Therefore, the first boss portion 113 can be positioned so as to overlap the coil end 63a in the axial direction of the drive shaft 61. The overlapping portion can shorten the overall length of the electric compressor 10 (the length in the direction along the center line CL1).

[0059] The first bearing 111 and the first boss portion 113 are located closer to the motor chamber 21 than the shaft seal 42 provided in the partition member 40. The first bearing 111 is not affected by the high-pressure refrigerant in the compression mechanism chamber 31.

[0060] As shown in Figure 5, the second bearing 112 is a rolling bearing such as a ball bearing or a roller bearing. It has a cylindrical second boss 114 (second shaft support 114) with a bottom for mounting and supporting the second bearing 112. This second boss 114 protrudes from the bottom wall 22 of the motor housing 20 toward the motor chamber 21. As a result, the second bearing 112 is located in the motor chamber 21.

[0061] Furthermore, an end 61b of the drive shaft 61 on the discharge chamber 32 side is rotatably supported by a cylindrical third boss portion 115 (third shaft support portion 115) provided on the third closure plate 103. This third boss portion 115 protrudes from the third closure plate 103 toward the discharge chamber 32. More specifically, the third boss portion 115 is rotatably supported by a sliding bearing 116 (third bearing 116) fitted in an internal third recess 115a, or directly by the third recess 115a.

[0062] The first and second bearings 111 and 112, the first boss portion 113, the second boss portion 114, the third boss portion 115, and the sliding bearing 116 are located on the center line CL1 of the drive shaft 61.

[0063] As shown in Figures 5 and 6, a first axial end surface 61c of the drive shaft 61 is disposed within the motor housing 20. A second axial end surface 61d of the drive shaft 61 is disposed within the compression mechanism housing 30 of Figure 2. The second bearing 112 is mounted in a second recess 114a of the second boss portion 114. The second recess 114a is in communication with the motor chamber 21 through an internal gap of the second bearing 112. The pressure in the motor chamber 21 is transmitted to the inside of the second recess 114a through the internal gap of the second bearing 112. Therefore, the pressure in the second recess 114a is the same as (or approximately the same as) the pressure in the motor chamber 21.

[0064] The electric compressor 10 has a pressure equalizing means 120 that equalizes the pressure acting on both end faces 61 c, 61 d of the drive shaft 61. For example, the pressure equalizing means 120 is configured by a through hole 121 that passes through the drive shaft 61 in the axial direction to allow communication between both end faces 61 c, 61 d of the drive shaft 61. The through hole 121 is located on the center line CL1 of the drive shaft 61 and has a first opening 122 that opens to the first end face 61 c of both end faces 61 c, 61 d of the drive shaft 61 and a second opening 123 that opens to the second end face 61 d.

[0065] At least one of the first opening 122 and the second opening 123 is isolated from the motor chamber 21 or the discharge chamber 32. In the first embodiment, the first opening 122 communicates only with the motor chamber 21 (the second recess 114a of the second boss portion 114). The second opening 123 is isolated from the discharge chamber 32. Here, "isolation" means that the flow of a medium (e.g., a refrigerant) between multiple spaces is sealed or restricted by a sealing member or a minute gap, and does not mean that the spaces are completely separated.

[0066] More specifically, the compression mechanism housing 30 has a cylindrical fourth boss 124 with a bottom that protrudes from the bottom wall 34 toward the discharge chamber 32. A fourth recess 124a in the fourth boss 124 is located on the center line CL1 of the drive shaft 61 and opens to the discharge chamber 32. The outer peripheral surface 115b of the third boss 115 on the third closure plate 103 is fitted into the fourth recess 124a of the fourth boss 124. A seal member 125 seals the gap between the outer peripheral surface 115b of the third boss 115 and the inner peripheral surface of the fourth boss 124 (the inner peripheral surface of the fourth recess 124a). As a result, the second opening 123 of the drive shaft 61 is isolated from the discharge chamber 32. The seal member 125 is, for example, an O-ring or a lip seal. In this manner, the third boss portion 115 , the fourth boss portion 124 , and the seal member 125 combine to form an isolation portion 126 for isolating the second opening 123 of the drive shaft 61 from the discharge chamber 32 .

[0067] The description of the electric compressor 10 of the first embodiment can be summarized as follows.

[0068] As shown in FIG. 1 , the electric compressor 10 includes a compression mechanism 70, a drive shaft 61 that drives the compression mechanism 70, a motor 60 that drives the drive shaft 61, a motor housing 20 that houses the motor 60 and defines a motor chamber 21 into which refrigerant drawn from an external refrigeration cycle is introduced, and a compression mechanism housing 30 that houses the compression mechanism 70 and has a discharge chamber 32 from which refrigerant compressed by the compression mechanism 70 is discharged.

[0069] As shown in Figure 5, the drive shaft 61 has two axial end faces 61c, 61d, of which the first end face 61c is arranged within the motor housing 20, and the second end face 61d of the two axial end faces 61c, 61d is arranged within the compression mechanism housing 30, and the portion 61a between the motor 60 and the compression mechanism 70 is rotatably supported by a rolling bearing 111 (first bearing 111) that can withstand radial loads and axial loads.

[0070] The electric compressor 10 further includes a pressure equalizing means 120 for equalizing the pressure acting on both end surfaces 61 c and 61 d of the drive shaft 61 .

[0071] In this way, the electric compressor 10 has the pressure equalizing means 120 that equalizes the pressure acting on both end surfaces 61c, 61d of the drive shaft 61, thereby suppressing the axial force acting on the drive shaft 61 and enabling the main bearing made up of the rolling bearing 111 to be made smaller and lighter. As a result, the electric compressor 10 can be made smaller and lighter. In other words, the rolling bearing 111 (first bearing 111) for supporting the drive shaft 61 that drives the compression mechanism 70 can be made smaller and lighter.

[0072] As shown in FIG. 5 , the pressure equalizing means 120 is configured by a through-hole 121 that passes through the drive shaft 61 in the axial direction, allowing communication between both end faces 61c, 61d of the drive shaft 61. The pressure equalizing means 120 is configured such that both end faces 61c, 61d of the drive shaft 61 that drives the compression mechanism 70 are communicated with each other by the through-hole 121, thereby balancing the pressures acting on both end faces 61c, 61d. This reduces the axial force acting on the drive shaft 61, allowing for a reduction in the size and weight of the main bearing, which is the rolling bearing 111 (first bearing 111). As a result, the electric compressor 10 can be made smaller and lighter.

[0073] 5, the through hole 121 has a first opening 122 that opens to the first end face 61c and a second opening 123 that opens to the second end face 61d of both end faces 61c, 61d of the drive shaft 61. At least one of the first opening 122 and the second opening 123 is isolated from the motor chamber 21 or the discharge chamber 32.

[0074] For example, when the first opening 122 is isolated from the motor chamber 21, the pressure acting between the end faces 61c, 61d is balanced at a high pressure. When the second opening 123 is isolated from the discharge chamber 32, the pressure acting between the end faces 61c, 61d is balanced at a low pressure. When the first opening 122 is isolated from the motor chamber 21 and the second opening 123 is isolated from the discharge chamber 32, the pressure acting between the end faces 61c, 61d is balanced at a preset reference pressure. In this way, the pressure acting between the end faces 61c, 61d of the drive shaft 61 can be balanced as desired.

[0075] 5 , the first opening 122 is preferably connected to the motor chamber 21, and the second opening 123 is isolated from the discharge chamber 32. As a result, the pressure of the motor chamber 21, which is a low-pressure region, is introduced into the first opening 122 and then led to the second opening 123 via the through-hole 121. Although the second end surface 61 d of the drive shaft 61 is disposed within the compression mechanism housing 30, the second opening 123 is isolated from the discharge chamber 32, which is a high-pressure region, so that the pressure acting on the second end surface 61 b ​​can be maintained at a pressure equivalent to the pressure of the motor chamber 21.

[0076] As shown in FIGS. 2 and 5 , the electric compressor 10 has a side plate 103 (third closure plate 103) that closes the end surface 94a of the compression mechanism 70 on the discharge chamber 32 side. The side plate 103 has a cylindrical shaft support boss 115 (third boss 115) that protrudes toward the discharge chamber 32. The shaft support boss 115 rotatably supports the end 61b of the drive shaft 61 on the discharge chamber 32 side. The outer peripheral surface 115b of the shaft support boss 115 is fitted into a recess 124a (fourth recess 124a of the fourth boss 124) formed in the interior 32 (discharge chamber 32) of the compressor housing 30. A seal member 125 seals the gap between the outer peripheral surface 115b of the shaft support boss 115 and the inner peripheral surface of the recess 124a, isolating the second opening 123 of the drive shaft 61 from the discharge chamber 32. Therefore, the second opening 123 of the drive shaft 61 can be easily and reliably isolated from the discharge chamber 32 by the seal member 125 .

[0077] 2, the partition member 40 has a cylindrical boss portion 113 (first boss portion 113) on its surface 40a facing the motor chamber 21, the boss portion 113 supporting the rolling bearing 111 (first bearing 111). The outer diameter D1 of the boss portion 113 is set smaller than the inner diameter D2 of the coil end 63a of the cylindrical stator 63 of the motor 60. The boss portion 113 overlaps the coil end 63a in the axial direction of the drive shaft 61. This allows the overall length of the electric compressor 10 to be shortened.

[0078] 1, the electric compressor 10 has a horizontally-mounted configuration in which the drive shaft 61 is disposed horizontally. Therefore, the rolling bearing 111 (first bearing 111) located in a portion 61a of the drive shaft 61 between the motor 60 and the compression mechanism 70 does not need to support the entire weight of the drive shaft 61. This allows the main bearing formed by the rolling bearing 111 to be made smaller and lighter.

[0079] The electric compressor 10 uses R744 (carbon dioxide) as the refrigerant in its refrigeration cycle. When R744 is used as the refrigerant, the refrigerant pressure is very high, resulting in a very large axial force acting on the rolling bearing 111 (first bearing 111). In response to this, the compressor is provided with pressure equalizing means 120 that equalizes the pressure acting on both end faces 61c, 61d of the drive shaft 61, thereby suppressing the axial force acting on the drive shaft 61 and enabling the main bearing, consisting of the rolling bearing 111, to be made smaller and lighter. As a result, the electric compressor 10 can be made smaller and lighter.

[0080] Second Embodiment An electric compressor 200 according to a second embodiment will be described with reference to Fig. 7. Fig. 7 corresponds to Fig. 5 described above.

[0081] An electric compressor 200 according to the second embodiment is characterized in that the isolating section 126 shown in Figures 1 to 6 is replaced with an isolating section 226 shown in Figure 7. The other basic configuration is common to the electric compressor 10 according to the first embodiment. The same reference numerals are used for the parts common to the electric compressor 10 according to the first embodiment, and detailed description thereof will be omitted.

[0082] The isolation portion 226 in the second embodiment is composed of the end portion 61b of the drive shaft 61 facing the discharge chamber 32, a cylindrical fourth boss portion 124 with a bottom into which the end portion 61b can be fitted, and a seal member 225 that seals between the inner circumferential surface of a fourth recess 124a of the fourth boss portion 124 and the outer circumferential surface 61e of the end portion 61b of the drive shaft 61. The fourth recess 124a inside the fourth boss portion 124 is sealed by the seal member 225. As a result, the second opening 123 of the drive shaft 61 is isolated from the discharge chamber 32. The seal member 225 is composed of, for example, an O-ring or a lip seal.

[0083] The electric compressor 200 of the second embodiment can be summarized as follows. The electric compressor 200 has a side plate 103 that closes an end surface 94a (see FIG. 2 ) of the compression mechanism 70 that faces the discharge chamber 32. The end 61b of the drive shaft 61 that faces the discharge chamber 32 penetrates the side plate 103 (third closure plate 103) and fits into a recess 124a (fourth recess 124a of the fourth boss 124) formed inside the compressor housing 30. A seal member 225 seals the gap between the outer circumferential surface 61e of the end 61b of the drive shaft 61 that faces the discharge chamber 32 and the inner circumferential surface of the recess 124a, thereby isolating the second opening 123 of the drive shaft 61 from the discharge chamber 32. Therefore, the seal member 225 can easily and reliably isolate the second opening 123 of the drive shaft 61 from the discharge chamber 32.

[0084] The electric compressor 200 according to the second embodiment can achieve the same effects as the electric compressor 10 according to the first embodiment, in addition to the effects of the second embodiment.

[0085] Third Embodiment An electric compressor 300 according to a third embodiment will be described with reference to Fig. 8. Fig. 8 corresponds to Fig. 5 described above.

[0086] An electric compressor 300 according to the third embodiment is characterized in that the isolating section 126 shown in Figures 1 to 6 is replaced with an isolating section 326 shown in Figure 8. The other basic configuration is the same as that of the electric compressor 10 according to the first embodiment. The same reference numerals are used for the parts common to the electric compressor 10 according to the first embodiment, and detailed description thereof will be omitted.

[0087] The side plate 103 (third closure plate 103) of the third embodiment has a cylindrical boss portion 315 (third boss portion 315) with a bottom that bulges out toward the discharge chamber 32. That is, the end of the third boss portion 315 on the discharge chamber 32 side is closed by a bottom plate 315c. As a result, a recess 315a (third recess 315a) formed in the boss portion 315 is isolated from the discharge chamber 32. The isolation portion 326 of the third embodiment is formed by the cylindrical boss portion 315 with a bottom.

[0088] An end 61b of the drive shaft 61 on the discharge chamber 32 side is rotatably supported by a sliding bearing 116 (third bearing 116) fitted in the recess 315a or directly in the recess 315a. The cylindrical boss 315 with a bottom separates the second opening 123 of the drive shaft 61 from the discharge chamber 32.

[0089] The electric compressor 300 of the third embodiment can be summarized as follows. The side plate 103 (third closure plate 103) has a cylindrical boss 315 (third boss 315) with a bottom that bulges out toward the discharge chamber 32. The end 61b of the drive shaft 61 facing the discharge chamber 32 is rotatably supported by a sliding bearing 116 (third bearing 116) fitted in a recess 315a (third recess 315a) formed in the boss 315, or directly in the recess 315a, thereby isolating the second opening 123 of the drive shaft 61 from the discharge chamber 32. Therefore, the second opening 123 of the drive shaft 61 can be reliably isolated from the discharge chamber 32 without the need for a seal member.

[0090] The electric compressor 300 according to the third embodiment can achieve the same effects as the electric compressor 10 according to the first embodiment, in addition to the effects of the third embodiment.

[0091] As long as the functions and effects of the present invention are achieved, the present invention is not limited to the respective embodiments. For example, the compression mechanism 70 is not limited to the parallel compression mechanism configuration described above, and may be a single-stage compression mechanism that compresses using only a single compression mechanism, or may be a multi-stage compression mechanism that compresses using a first compression mechanism 80 and a second compression mechanism 90 arranged in series. Furthermore, a stepped portion with a slightly larger diameter may be formed at the engagement portion of the drive shaft 61 with the first bearing 111, so that the axial load of the drive shaft 61 is transmitted to the first bearing 111 via this stepped portion. The electric compressors 10, 200, and 300 of the respective embodiments may be combined with any two or more of the embodiments.

[0092] The electric compressors 10, 200, and 300 of the present invention are suitable for use in a refrigeration cycle.

[0093] DESCRIPTION OF SYMBOLS 10 Electric compressor 20 Motor housing 21 Motor chamber 30 Compression mechanism housing 31 Compression mechanism chamber 32 Discharge chamber 40 Partition member 40a Surface facing the motor chamber 41 Shaft insertion hole 60 Motor 61 Drive shaft (output shaft) 61a Portion between the motor and the compression mechanism 61b End of the drive shaft on the discharge chamber side 61c First end face 61d Second end face 61e Outer peripheral surface of the end 63 Stator 63a Coil end 70 Compression mechanism 103 Side plate (third closure plate) 111 First bearing 112 Second bearing 113 First boss portion (first shaft support portion) 114 Second boss portion (second shaft support portion) 114a Second recess 115 Third boss portion (third shaft support portion) 115a Third recess 115b Outer peripheral surface 116 Sliding bearing 120 Pressure equalizing means 121 Through hole 122 First opening 123 Second opening 124 Fourth boss portion 124a Fourth recessed portion 125 Seal member 126 Separating portion 200 Electric compressor 225 Seal member 226 Separating portion 300 Electric compressor 315 Boss portion (third boss portion) 315a Recessed portion (third recessed portion) 326 Separating portion D1 Outer diameter of first boss portion D2 Inner diameter of stator coil end

Claims

1. An electric compressor (10; 200; 300) comprising: a compression mechanism (70); a drive shaft (61) that drives the compression mechanism (70); a motor (60) that drives the drive shaft (61); a motor housing (20) that houses the motor (60) and defines a motor chamber (21) into which refrigerant drawn from an external refrigeration cycle is introduced; and a compression mechanism housing (30) that houses the compression mechanism (70) and has a discharge chamber (32) from which the refrigerant compressed by the compression mechanism (70) is discharged, the drive shaft (61) has a first end face (61c) of both axial end faces (61c, 61d) disposed within the motor housing (20), a second end face (61d) of both axial end faces (61c, 61d) disposed within the compression mechanism housing (30), and a portion (61a) between the motor (60) and the compression mechanism (70) is rotatably supported by a rolling bearing (111) capable of bearing a radial load and an axial load, and the electric compressor (10; 200; 300) further includes pressure equalizing means (120) for equalizing pressure acting on the both end faces (61c, 61d) of the drive shaft (61).

2. An electric compressor as described in claim 1, wherein the pressure equalizing means (120) is constituted by a through hole (121) that passes through the drive shaft (61) in the axial direction, allowing communication between the both end faces (61c, 61d) of the drive shaft (61).

3. The electric compressor according to claim 2, wherein the through hole (121) has a first opening (122) that opens to the first end face (61c) of the both end faces (61c, 61d) of the drive shaft (61) and a second opening (123) that opens to the second end face (61d), and at least one of the first opening (122) and the second opening (123) is isolated from the motor chamber (21) or the discharge chamber (32).

4. The electric compressor according to claim 3, wherein the first opening (122) communicates with the motor chamber (21), and the second opening (123) is isolated from the discharge chamber (32).

5. The compressor further includes a side plate (103) provided to close an end face (94a) of the compression mechanism (70) on the discharge chamber (32) side, the side plate (103) having a cylindrical shaft support boss portion (115) protruding toward the discharge chamber (32), the shaft support boss portion (115) rotatably supporting an end portion (61b) of the drive shaft (61) on the discharge chamber (32) side, and an outer peripheral surface (115b) of the shaft support boss portion (115) fitting into a recess (124a) formed inside the compression mechanism housing (30), 5. The electric compressor according to claim 4, wherein a seal member seals a gap between the outer peripheral surface of the shaft support boss portion and an inner peripheral surface of the recess, thereby isolating the second opening of the drive shaft from the discharge chamber.

6. The electric compressor according to claim 4, further comprising a side plate (103) provided to close an end face (94a) of the compression mechanism (70) on the discharge chamber (32) side, an end (61b) of the drive shaft (61) on the discharge chamber (32) side passes through the side plate (103) and fits into a recess (124a) formed inside the compression mechanism housing (30), and a seal member (225) seals between an outer peripheral surface (61e) of the end (61b) and an inner peripheral surface of the recess (124a), thereby isolating the second opening (123) of the drive shaft (61) from the discharge chamber (32).

7. The electric compressor according to claim 4, further comprising a side plate (103) provided so as to close an end face of the compression mechanism (70) on the discharge chamber (32) side, the side plate (103) having a cylindrical boss portion (315) with a bottom that bulges out towards the discharge chamber (32), and an end portion (61b) of the drive shaft (61) on the discharge chamber (32) side is rotatably supported by a sliding bearing (116) fitted in a recess (315a) formed in the boss portion (315) or directly in the recess (315a), thereby isolating the second opening (123) of the drive shaft (61) from the discharge chamber (32).

8. The electric compressor according to claim 1, further comprising a partition member (40) provided between the motor housing (20) and the compression mechanism housing (30), the partition member (40) having a cylindrical boss portion (113) supporting the rolling bearing (111) on a surface (40a) facing the motor chamber (21), the outer diameter (D1) of the boss portion (113) being set smaller than the inner diameter (D2) of the coil end (63a) of the cylindrical stator (63) of the motor (60), and the boss portion (113) overlapping the coil end (63a) in the axial direction of the drive shaft (61).

9. The electric compressor according to claim 1, wherein the drive shaft (61) is arranged horizontally.

10. The electric compressor according to claim 1, wherein R744 is used as the refrigerant in the refrigeration cycle.

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