Electric compressor

Abstract

An electric compressor is provided with: a housing having a cylindrical stator in the inner peripheral portion thereof; a rotating shaft disposed inside the housing and having a rotor facing the stator; the compressor impeller is fixed on one side of the axial direction of the rotating shaft; and a cooling water flow path provided on the outside of the housing in the radial direction of the stator, the cooling water flow path having: a plurality of first cooling water flow paths provided along the circumferential direction of the housing and provided at intervals in the axial direction; and a second cooling water flow path provided along a bending direction bent at a predetermined angle with respect to the circumferential direction of the housing, the second cooling water flow path connecting the ends of the plurality of first cooling water flow paths to each other.

Description

Technical Field

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

[0002] For example, fuel cells require high-pressure air and are therefore suitable for two-stage compression electric compressors. A two-stage compression electric compressor is constructed such that a rotating shaft is rotatably supported by a housing, a low-pressure impeller is arranged on one axial side of the rotating shaft, and a high-pressure impeller is arranged on the other axial side. The electric compressor rotates the rotor by passing current through the stator coils constituting the stator, utilizing the magnetic attraction and repulsion generated thereby, thereby rotating the rotating shaft integral with the rotor. Therefore, in particular, the stator (stator coil) becomes hot and needs to be cooled. Typically, the electric compressor cools the stator by flowing cooling water inside the housing, and supplies a portion of the compressed air to the stator to cool the stator. As an example of such an electric compressor, there is the electric compressor described in Patent Document 1.

[0003] Previous technical literature Patent Literature Patent Document 1: Japanese Patent No. 5565229 Summary of the Invention

[0004] Technical issues to be solved by the invention The conventional electric compressor described in Patent Document 1 cools the stator by forming a spiral flow path in the housing and allowing cooling water to flow through the spiral flow path. In this case, the spiral flow path is in a spiral shape relative to the center of the housing, so it is impossible to set a cooling water flow path on the inlet and outlet sides of the cooling water. The stator has a stator core and a stator coil. The stator coil is wound around the stator core, and a portion of the stator coil is exposed to one side and the other side of the axial direction as the coil end. Therefore, it is difficult for conventional electric compressors to fully cool the coil end of the stator coil with the cooling water flowing through the spiral flow path.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an electric compressor that improves cooling performance.

[0006] Means for solving technical problems In order to achieve the above-mentioned purpose, the electric compressor of the present invention comprises: a housing having a cylindrical stator on the inner circumference; a rotating shaft arranged inside the housing and having a rotor opposite to the stator; a compressor impeller fixed to one side of the axial direction of the rotating shaft; and a cooling water flow path arranged on the radially outer side of the stator in the housing, the cooling water flow path comprising: a plurality of first cooling water flow paths arranged along the circumference of the housing and arranged at intervals in the axial direction; and a second cooling water flow path arranged along a bending direction bent at a predetermined angle relative to the circumference of the housing, and connecting the ends of the plurality of first cooling water flow paths to each other.

[0007] Effects of the Invention According to the electric compressor of the present invention, it is possible to improve cooling performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a longitudinal sectional view showing the internal structure of the electric compressor according to the first embodiment.

[0009] Figure 2 It is a perspective view schematically showing a cooling water channel.

[0010] Figure 3 It is a perspective view showing a core for forming a cooling water channel.

[0011] Figure 4 It is a schematic diagram showing the shape of the cooling water channel.

[0012] Figure 5 It is a cross-sectional view showing a cooling water passage in the electric compressor according to the second embodiment.

[0013] Figure 6 It is a cross-sectional view showing a cooling water passage in the electric compressor according to the third embodiment.

[0014] Figure 7 It is a cross-sectional view showing a modified example of the cooling water passage in the electric compressor.

[0015] Figure 8 It is a perspective view schematically showing a cooling water passage in the electric compressor according to the third embodiment.

[0016] Figure 9 It is a cross-sectional view showing a cooling water channel. DETAILED DESCRIPTION

[0017] The following describes in detail preferred embodiments of the present invention with reference to the accompanying drawings. The present invention is not limited to these embodiments and, when multiple embodiments exist, also includes configurations formed by combining the various embodiments. Furthermore, the constituent elements in the embodiments include those readily apparent to those skilled in the art, substantially identical elements, and so-called equivalent elements.

[0018] [First embodiment] <Structure of an electric compressor> Figure 1 It is a longitudinal sectional view showing the internal structure of the electric compressor according to the first embodiment.

[0019] like Figure 1 As shown, the electric compressor 10 is a two-stage compression type electric compressor and includes a housing 11 , a rotating shaft 12 , a low-pressure impeller 13 , and a high-pressure impeller 14 .

[0020] The housing 11 includes a motor housing 21, a low-pressure side bearing housing 22, and a high-pressure side bearing housing 23. The motor housing 21 is cylindrical. The low-pressure side bearing housing 22 is disk-shaped and is disposed on one side of the motor housing 21 in the axial direction ( Figure 1 The low-pressure side bearing housing 22 is detachably fastened to one end of the motor housing 21 in the axial direction by a plurality of bolts (not shown). The high-pressure side bearing housing 23 is in the shape of a circular plate and is arranged on the other side of the motor housing 21 in the axial direction ( Figure 1 The high-pressure side bearing housing 23 is detachably fastened to the other axial end of the motor housing 21 by a plurality of bolts (not shown).

[0021] The motor housing 21 has one axial opening closed by the low-pressure bearing housing 22, and the other axial opening closed by the high-pressure bearing housing 23. Therefore, the housing 11 has a hollow shape due to the low-pressure bearing housing 22 and the high-pressure bearing housing 23 being fastened to the motor housing 21.

[0022] The motor housing 21 has a stator 31 fixed to its inner periphery. The stator 31 is cylindrical in shape. It includes a stator core 32 and a stator coil 33. The stator core 32 is cylindrical in shape, and its outer periphery is fixed to the inner periphery of the motor housing 21. The stator coil 33 is wound around the stator core 32, with a portion of the stator coil 33 being housed within the stator core 32. The low-voltage coil end 33a is exposed on one axial side of the stator core 32, while the high-voltage coil end 33b is exposed on the other axial side of the stator core 32.

[0023] The rotating shaft 12 is disposed within the housing 11. The rotating shaft 12 is arranged along an axis O concentric with the housing 11 and is rotatably supported by the housing 11 about the axis O. A rotor 34 is fixed to the outer periphery of the rotating shaft 12 at an axially intermediate position. The rotor 34 includes a rotor core (permanent magnet) 35. The rotor core 35 is cylindrical and fixed to the outer periphery of the rotating shaft 12.

[0024] The inner and outer circumferences of the stator 31 and rotor 34 face each other in the radial direction. A gap is provided between the inner and outer circumferences of the stator 31 and the rotor 34. Therefore, when current flows through the stator coils 33 of the stator 31, the resulting magnetic attraction and repulsion forces cause the rotor 34 to rotate, thereby generating a rotational force on the rotating shaft 12.

[0025] The rotating shaft 12 is rotatably supported by the housing 11 via a low-pressure air bearing 38 and a high-pressure air bearing 39. The rotating shaft 12 has a low-pressure shaft portion 12a on the side axially closer to the rotor 34, and a high-pressure shaft portion 12b on the other side axially closer to the rotor 34. The low-pressure bearing sleeve 36 is mounted on the low-pressure shaft portion 12a for integral rotation, and the high-pressure bearing sleeve 37 is mounted on the high-pressure shaft portion 12b for integral rotation. The low-pressure bearing sleeve 36 functions as the low-pressure shaft portion, and the high-pressure bearing sleeve 37 functions as the high-pressure shaft portion. Alternatively, the low-pressure bearing sleeve 36 and the high-pressure bearing sleeve 37 may be omitted, or the rotating shaft 12 may be directly supported by the low-pressure air bearing 38 and the high-pressure air bearing 39.

[0026] The low-pressure air bearing 38 is integrally provided with the low-pressure bearing housing 22. The low-pressure air bearing 38 is cylindrical and extends from the inner surface of the low-pressure bearing housing 22 toward the rotor 34. The low-pressure air bearing 38 is located outside the low-pressure bearing sleeve 36 mounted on the rotating shaft 12. If the low-pressure air bearing 38 directly supports the rotating shaft 12, the low-pressure air bearing 38 is located outside the rotating shaft 12. A low-pressure clearance is maintained between the inner circumferential surface of the low-pressure air bearing 38 and the outer circumferential surface of the low-pressure bearing sleeve 36.

[0027] The high-pressure air bearing 39 is integrally mounted on the high-pressure bearing housing 23. The high-pressure air bearing 39 is cylindrical and extends from the inner surface of the high-pressure bearing housing 23 toward the rotor 34. The high-pressure air bearing 39 is positioned outside the high-pressure bearing sleeve 37 mounted on the rotating shaft 12. If the high-pressure air bearing 39 directly supports the rotating shaft 12, the high-pressure air bearing 39 is positioned outside the rotating shaft 12. A high-pressure clearance is maintained between the inner circumferential surface of the high-pressure air bearing 39 and the outer circumferential surface of the high-pressure bearing sleeve 37.

[0028] Regarding the housing 11, a low-pressure compressor 41 is disposed on the low-pressure side bearing housing 22 side, and a high-pressure compressor 42 is disposed on the high-pressure side bearing housing 23 side. The low-pressure compressor 41 includes a low-pressure side housing 43 and a low-pressure impeller 13. The high-pressure compressor 42 includes a high-pressure side housing 44 and a high-pressure impeller 14.

[0029] The low-pressure side casing 43 is fastened to the outer surface of the low-pressure side bearing housing 22 by multiple bolts. The low-pressure impeller 13 is disposed within the low-pressure side casing 43. The low-pressure impeller 13 is fixed to one axial end of the rotating shaft 12 by bolts 45 for integral rotation. The low-pressure compressor 41 is provided with an intake port 46, a diffuser portion 47, a scroll-shaped scroll portion 48, and a discharge port (not shown) via the low-pressure side casing 43 and the low-pressure impeller 13.

[0030] The high-pressure side casing 44 is fastened to the outer surface of the high-pressure side bearing housing 23 by a plurality of bolts. The high-pressure impeller 14 is disposed within the high-pressure side casing 44. The high-pressure impeller 14 is fixed to the other axial end of the rotating shaft 12 by bolts 49 for integral rotation. The high-pressure compressor 42 is provided with an intake port 50, a diffuser portion 51, a scroll-shaped scroll portion 52, and a discharge port (not shown) via the high-pressure side casing 44 and the high-pressure impeller 14.

[0031] Furthermore, the low-pressure compressor 41 and the high-pressure compressor 42 are connected to each other at a discharge port (not shown) and a suction port 50 via a connecting flow path 53 .

[0032] In the low-pressure compressor 41, when the low-pressure impeller 13 rotates, external air is drawn in through the intake port 46. The centrifugal force of the low-pressure impeller 13 accelerates and pressurizes the air. The accelerated and pressurized air is decelerated by the diffuser 47, flows through the vortex 48, and is discharged from the outlet. The low-pressure air compressed by the low-pressure compressor 41 is delivered to the high-pressure compressor 42 via the connecting flow path 53. In the high-pressure compressor 42, when the high-pressure impeller 14 rotates, external air is drawn in through the intake port 50. The centrifugal force of the high-pressure impeller 14 accelerates and pressurizes the air. The accelerated and pressurized air is decelerated by the diffuser 51, flows through the vortex 52, and is discharged from the outlet.

[0033] <Air flow path> like Figure 1As shown, the electric compressor 10 has an air flow path 60. The air flow path 60 has a first air flow path 61 and a second air flow path 62. The first air flow path 61 supplies compressed air from the housing 11 to the low-pressure side air bearing 38. The first air flow path 61 is arranged in the low-pressure side bearing housing 22 along the radial direction. In the first air flow path 61, an air inlet 63 is provided at one end on the radially outer side. The air inlet 63 is connected to an exhaust flow path 64 branching from the connecting flow path 53. In the first air flow path 61, a part of the low-pressure air (compressed air) discharged from the low-pressure compressor 41 is extracted by the exhaust flow path 64 and supplied to the air inlet 63. In addition, the air inlet 63 can be connected to an exhaust flow path that extracts high-pressure air (compressed air) discharged from the high-pressure compressor 42. The low-pressure side bearing housing 22 is provided with a low-pressure side space portion 65 on the outer periphery of the axis O. The other radially inner end of the first air flow path 61 communicates with the low-pressure side space 65 .

[0034] A thrust disc 66, constituting a thrust bearing, is fixed to the rotating shaft 12. The thrust disc 66 is fixed between the low-pressure side bearing sleeve 36 of the rotating shaft 12 and the low-pressure impeller 13. The thrust disc 66 rotates integrally with the rotating shaft 12. The thrust disc 66 is disposed in the low-pressure side space 65. The low-pressure side space 65 communicates with the low-pressure side gap between the inner circumferential surface of the low-pressure side air bearing 38 and the outer circumferential surface of the low-pressure side bearing sleeve 36.

[0035] Compressed air flowing through the first air flow path 61 is supplied to the low-pressure side space 65, cooling the bearing surfaces (one axial surface and the other axial surface of the low-pressure side space 65) that support the thrust disk 66. The compressed air in the low-pressure side space 65 is then supplied to the low-pressure side air bearing 38. Specifically, the compressed air is supplied to the low-pressure side gap between the inner circumference of the low-pressure side air bearing 38 and the outer circumference of the low-pressure side bearing sleeve 36, thereby floating the rotating shaft 12 and supporting it at a predetermined radial position. The compressed air supplied to the low-pressure side air bearing 38 is then discharged to the outside through an outlet (not shown) provided in the housing 11.

[0036] The second air flow path 62 branches off from the first air flow path 61 and supplies compressed air to the high-pressure side air bearing 39. The second air flow path 62 includes an axial air flow path 67 and a radial air flow path 68. The axial air flow path 67 branches off from the first air flow path 61 and extends along the axial direction of the rotating shaft 12 in the motor housing 21. The radial air flow path 68 communicates with the axial air flow path 67 and extends along the radial direction of the rotating shaft 12 in the high-pressure side bearing housing 23. Furthermore, the radial air flow path 68 communicates with the high-pressure side gap between the inner circumferential surface of the high-pressure side air bearing 39 and the outer circumferential surface of the high-pressure side bearing sleeve 37.

[0037] The compressed air branching off from the first air flow path 61 flows axially through the axial air flow path 67 of the second air flow path 62 before flowing radially inward through the radial air flow path 68 and being supplied to the high-pressure side air bearing 39. Specifically, the compressed air is supplied to the high-pressure side gap between the inner circumference of the high-pressure side air bearing 39 and the outer circumference of the high-pressure side bearing sleeve 37, thereby floating the rotating shaft 12 and supporting it at a predetermined radial position. The compressed air supplied to the high-pressure side air bearing 39 then flows through the gap between the stator 31 and the rotor 34, cooling the stator core 32 and stator coil 33 of the stator 31. The compressed air that has cooled the stator 31 is discharged to the outside through an outlet (not shown) provided in the housing 11.

[0038] <Cooling water path> Figure 2 It is a perspective view schematically showing a cooling water channel.

[0039] like Figure 1 As shown, the electric compressor 10 includes a cooling water flow path 70. The cooling water flow path 70 is provided radially outside the stator 31 in the housing 11 and radially inside the axial air flow path 67 of the air flow path 60 that constitutes the second air flow path 62. In this embodiment, the cooling water flow path 70 is arranged radially inside the axial air flow path 67 of the air flow path 60 that constitutes the second air flow path 62, but this is not limiting. The cooling water flow path 70 may also be arranged radially outside the axial air flow path 67 of the air flow path 60 that constitutes the second air flow path 62.

[0040] like Figure 1 and Figure 2 As shown, the cooling water flow path 70 includes a plurality of first cooling water flow paths 71 and a plurality of second cooling water flow paths 72 .

[0041] The first cooling water flow path 71 includes a plurality (four in this embodiment) of flow paths 71a, 71b, 71c, and 71d. The plurality of flow paths 71a, 71b, 71c, and 71d are arranged along the circumference of the motor housing 21. The plurality of flow paths 71a, 71b, 71c, and 71d are spaced apart in the axial direction of the motor housing 21. The plurality of flow paths 71a, 71b, 71c, and 71d are arranged within a predetermined angle (e.g., 270° to 300°) in the circumferential direction of the motor housing 21. In this case, the plurality of flow paths 71a, 71b, 71c, and 71d are staggered at a predetermined angle in the circumferential direction of the motor housing 21.

[0042] The second cooling water flow path 72 includes multiple (three in this embodiment) flow paths 72a, 72b, and 72c. The second cooling water flow path 72 connects the ends of the multiple first cooling water flow paths 71. Specifically, the multiple flow paths 72a, 72b, and 72c connect the ends of the multiple flow paths 71a, 71b, 71c, and 71d. The multiple flow paths 72a, 72b, and 72c are arranged along a curved direction that is bent at a predetermined angle relative to the circumferential direction of the motor housing 21. The multiple flow paths 72a, 72b, and 72c are spaced apart in the axial direction of the motor housing 21. The multiple flow paths 72a, 72b, and 72c are arranged within a predetermined angle (e.g., 60° to 90°) in the circumferential direction of the motor housing 21. In this case, the multiple flow paths 72a, 72b, and 72c are staggered at a predetermined angle in the circumferential direction of the motor housing 21. Flow path 72a connects the end of flow path 71a and the end of flow path 71b, flow path 72b connects the end of flow path 71b and the end of flow path 71c, and flow path 72c connects the end of flow path 71c and the end of flow path 71d.

[0043] The first cooling water flow path 71, which is located on one axial side of the motor housing 21, extends substantially throughout the circumference of the motor housing and has a cooling water outlet 73 at its end. Furthermore, the first cooling water flow path 71, which is located on the other axial side of the motor housing 21, extends substantially throughout the circumference of the motor housing 21 and has a cooling water inlet 74 at its end.

[0044] Furthermore, the flow path 71a of the first cooling water flow path 71, which has an outlet portion 73, is arranged opposite the coil end portion 33a of the stator coil 33 constituting the stator 31. Furthermore, the flow path 71d of the first cooling water flow path 71, which has an inlet portion 74, is arranged opposite the coil end portion 33b of the stator coil 33 constituting the stator 31.

[0045] In the first cooling water flow path 71, multiple flow paths 71a, 71b, 71c, and 71d are arranged at predetermined angles in the circumferential direction of the motor housing 21. Similarly, in the second cooling water flow path 72, multiple flow paths 72a, 72b, and 72c are arranged at predetermined angles in the circumferential direction of the motor housing 21. Furthermore, the flow paths 72a, 72b, and 72c connect the ends of adjacent flow paths 71a, 71b, 71c, and 71d. Therefore, the multiple flow paths 72a, 72b, and 72c that constitute the second cooling water flow path 72 are arranged at intervals along a connecting line C that is inclined at a predetermined angle relative to the axis O and passes through the outlet 73 and the inlet 74.

[0046] Cooling water is supplied to the inlet 74 provided in the motor housing 21, flows through the plurality of first cooling water flow paths 71 and the plurality of second cooling water flow paths 72, and is discharged to the outside through the outlet 73. Specifically, the cooling water flows from the inlet 74 through the flow paths 71a, 72a, 71b, 72b, 71c, 72ca, and 71d to the outlet 73. At this point, the stator core 32 and stator coil 33 in the stator 31 are cooled by the cooling water flowing through the interior of the motor housing 21.

[0047] Core Structure Figure 3 It is a perspective view showing a core for forming a cooling water channel.

[0048] The motor housing 21 is manufactured by casting. Figure 3 As shown, the core 100 used to manufacture the motor housing 21 includes ring portions 101a, 101b, 101c, and 101d corresponding to the first cooling water flow paths 71, and curved portions 102a, 102b, and 102c corresponding to the second cooling water flow paths 72, respectively. Furthermore, the ring portion 101a is provided with a cylindrical portion 103 corresponding to the outlet 73, and the ring portion 101d is provided with a cylindrical portion (not shown) corresponding to the inlet 74.

[0049] Furthermore, the core 100 has a plurality of positioning blocks 105a, 105b, 105c, 105d, 106a, 106b, and 106c connected to the ring portions 101a, 101b, 101c, and 101d and the curved portions 102a, 102b, and 102c. Meanwhile, although not shown, the outer mold is divided into three parts: an upper mold and a lower mold corresponding to the ring portions 101a, 101b, 101c, and 101d, and a side mold corresponding to the curved portions 102a, 102b, and 102c. The core 100 is provided with a plurality of positioning blocks 105a, 105b, 105c, 105d, 106a, 106b, 106c relative to the ring portions 101a, 101b, 101c, 101d and the curved portions 102a, 102b, 102c, thereby improving the manufacturability of the core 100 and suppressing the deviation of the core 100 relative to the mold during casting.

[0050] <Second cooling water path> Figure 4 It is a schematic diagram showing the shape of the cooling water channel.

[0051] like Figure 4As shown, in the first cooling water flow path 71, the flow path 71a and the flow path 71b are connected by the flow path 72a of the second cooling water flow path 72. The flow paths 71a and 71b are arranged along the circumferential lines Ra and Rb extending along the circumference of the motor housing 21, and are arranged at a distance L in the axial direction of the motor housing 21. The flow path 72a is arranged along the bending line B bent at a predetermined angle θ relative to the circumferential lines Ra and Rb, and each end is connected to the flow path 71a and the flow path 71b. Taking into account the pressure loss of the cooling water flowing through the first cooling water flow path 71 and the second cooling water flow path 72, the predetermined angle θ is preferably set to be within the range of 10° to 40°, for example. At this time, the connection portion between the flow path 71a and the flow path 72a or the connection portion between the flow path 71b and the flow path 72a is preferably connected by a bending portion.

[0052] Furthermore, the channel cross-sectional area of ​​the flow paths 71a and 71b (71c and 71d) constituting the first cooling water flow path 71 is the same as the channel cross-sectional area of ​​the flow path 72a (72b and 72c) constituting the second cooling water flow path 72. In other words, the width W1 of the flow paths 71a and 71b (71c and 71d) is the same as the width W2 of the flow paths 72a (72b and 72c). Furthermore, the height of the flow paths 71a and 71b (71c and 71d) is the same as the height of the flow paths 72a (72b and 72c).

[0053] Here, the channel cross-sectional area refers to the channel area when the flow paths 71a, 71b (71c, 71d) and the flow paths 72a (72b, 72c) are cut in a direction perpendicular to the longitudinal direction (the direction of cooling water flow). However, near the connection between the flow paths 71a, 71b (71c, 71d) and the flow paths 72a (72b, 72c), the channel cross-sectional area of ​​the flow paths 71a, 71b (71c, 71d) and the channel cross-sectional area of ​​the flow paths 72a (72b, 72c) may differ.

[0054] <Function of Electric Compressor> like Figure 1 and Figure 2 As shown, the electric compressor 10 rotates the rotor 34 by passing current through the stator coils 33 constituting the stator 31, thereby rotating the rotating shaft 12 integral with the rotor 34. A low-pressure impeller 13 and a high-pressure impeller 14 are connected to each end of the rotating shaft 12. Therefore, the stator 31 in particular reaches a high temperature. The electric compressor 10 is an air-cooled and water-cooled type. Specifically, the electric compressor 10 extracts a portion of the compressed air compressed by the low-pressure impeller 13 and supplies it to the air flow path 60. The air is then supplied to the low-pressure side air bearing 38 and the high-pressure side air bearing 39, and then supplied to the stator 31 to cool the stator 31.

[0055] Furthermore, the electric compressor 10 supplies cooling water from the outside to the cooling water flow path 70 to cool the stator core 32 or stator coil 33 of the stator 31. At this time, the first cooling water flow path 71 constituting the cooling water flow path 70 is configured such that the flow paths 71a, 71b, 71c, and 71d are arranged at the axial ends of the motor housing 21. Therefore, the coil ends 33a and 33b of the stator coil 33 can be cooled. In other words, in the stator 31, not only the stator core 32 but also the stator coil 33 are appropriately cooled by the cooling water, thereby reducing the flow rate of compressed air used as cooling air. Therefore, by primarily utilizing the compressed air for the stator 31 and rotor 34, air shortages in the stator 31 and rotor 34 can be suppressed, and the stator 31 and rotor 34 can be appropriately cooled.

[0056] [Second embodiment] Figure 5 2 is a cross-sectional view showing a cooling water channel in an electric compressor according to a second embodiment. Figure 1 and Figure 2 In the description, components having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0057] like Figure 1 and Figure 2 As shown, the cooling water flow path 70 includes a plurality of first cooling water flow paths 71 and a plurality of second cooling water flow paths 72 .

[0058] like Figure 5 As shown, the first cooling water flow path 71 and the second cooling water flow path 72 are provided with a plurality of protrusions 81 on the inner surface. The protrusions 81 are shaped along the circumference of the motor housing 21 and are arranged at intervals in the axial direction of the motor housing 21. Furthermore, the protrusions 81 have a semicircular cross-sectional shape, but may also have a quadrilateral cross-sectional shape or a trapezoidal cross-sectional shape. Furthermore, the protrusions 81 are provided on one of the four inner surfaces that partition the first cooling water flow path 71 and the second cooling water flow path 72, but may also be provided on a plurality of inner surfaces. Furthermore, the protrusions 81 are provided in a shape along the circumference of the motor housing 21, but may also be provided as mere protrusions at intervals in the circumferential direction of the motor housing 21.

[0059] The flow area of ​​the first cooling water flow path 71 and the second cooling water flow path 72 can be changed by adjusting the number of protrusions 81 provided on the inner surface. Therefore, the flow rate or flow velocity of the cooling water flowing through the first cooling water flow path 71 and the second cooling water flow path 72 can be adjusted, thereby improving cooling efficiency.

[0060] [Third embodiment] Figure 61 is a cross-sectional view showing a cooling water channel in an electric compressor according to a third embodiment. Figure 1 and Figure 2 In the following description, components having the same functions as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0061] like Figure 6 As shown, the motor housing 21 is provided with recesses 82 on the outer surface radially outside the plurality of first cooling water flow paths 71 and second cooling water flow paths 72. The recesses 82 are shaped along the circumferential direction of the motor housing 21 and are arranged at intervals in the axial direction of the motor housing 21. The recesses 82 are arranged between the first cooling water flow paths 71 and the second cooling water flow paths 72 on the outer surface of the motor housing 21. Furthermore, the recesses 82 are semicircular in shape, but may also be rectangular or trapezoidal in shape. Furthermore, the recesses 82 are provided in a shape along the circumferential direction of the motor housing 21, but may also be simply protrusions, with a plurality of recesses 82 arranged at intervals in the circumferential direction of the motor housing 21.

[0062] Providing recessed portions 82 on the outer surfaces of the first cooling water flow path 71 and the second cooling water flow path 72 increases the surface area of ​​the motor housing 21. This improves the cooling efficiency of the cooling water flowing through the motor housing 21, the first cooling water flow path 71, and the second cooling water flow path 72.

[0063] Modifications Figure 7 It is a cross-sectional view showing a modified example of the cooling water passage in the electric compressor.

[0064] like Figure 7 As shown, the motor housing 21 has protrusions 83 on its outer surface radially outward of the plurality of first cooling water flow paths 71 and second cooling water flow paths 72. The protrusions 83 are shaped along the circumference of the motor housing 21 and are spaced apart in the axial direction of the motor housing 21. While the protrusions 83 are semicircular, they may also be rectangular or trapezoidal. Furthermore, while the protrusions 83 are shaped along the circumference of the motor housing 21, they may also be simply protrusions, with multiple protrusions spaced apart in the circumference of the motor housing 21.

[0065] Providing the protrusions 83 on the outer surfaces of the first cooling water flow path 71 and the second cooling water flow path 72 increases the surface area of ​​the motor housing 21. This improves the cooling efficiency of the cooling water flowing through the motor housing 21, the first cooling water flow path 71, and the second cooling water flow path 72.

[0066] [Fourth embodiment] Figure 81 is a perspective view schematically showing a cooling water passage in an electric compressor according to a fourth embodiment. Figure 9 : is a cross-sectional view showing the cooling water channel. In addition, the basic structure of the fourth embodiment is the same as that of the first embodiment described above. Figure 2 In the description, components having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0067] like Figure 8 and Figure 9 As shown, the second cooling water flow path 72 is composed of a plurality of flow paths 72a, 72b, and 72c spaced apart in the axial direction of the motor housing 21. The plurality of flow paths 72a, 72b, and 72c are spaced apart along a connecting line C that is tilted at a predetermined angle relative to the axis O. The cross-sectional shape of the flow paths 72a, 72b, and 72c is a scalene. In other words, the gaps between the flow paths 72a, 72b, and 72c are in the shape of a scalene and face in one direction. Figure 9 is the channel cross-sectional shape of the end portion of the flow path 72a connected to the end portion of the flow path 71b. Figure 9 As shown, the flow path 72a is in the shape of a parallelogram.

[0068] As previously mentioned, the core 100 (refer to Figure 3 ) For manufacturing cooling water flow paths 70, the outer mold is divided into three parts: an upper mold and a lower mold corresponding to the first cooling water flow paths 71, and a side mold corresponding to the second cooling water flow paths 72. The upper mold, lower mold, and side mold are pulled radially outward relative to the core 100. Therefore, by setting the channel cross-section of the flow paths 72a, 72b, and 72c to an irregular quadrilateral, the side mold can be easily releasable from the core 100.

[0069] [Effects of this embodiment] The electric compressor involved in the first embodiment includes: a housing 11, which has a cylindrical stator 31 on its inner circumference; a rotating shaft 12, which is arranged inside the housing 11 and has a rotor 34 opposite to the stator 31; a low-pressure impeller (compressor impeller) 13, which is fixed to one side of the axial direction of the rotating shaft 12; and a cooling water flow path 70, which is arranged radially outside the stator 31 in the housing 11, and the cooling water flow path 70 includes: a plurality of first cooling water flow paths 71, which are arranged along the circumferential direction of the housing 11 and are arranged at intervals in the axial direction; and a second cooling water flow path 72, which is arranged along a curved direction bent at a predetermined angle relative to the circumferential direction of the housing 11 and connects the ends of the plurality of first cooling water flow paths 71 to each other.

[0070] According to the electric compressor of the first embodiment, the first cooling water flow path 71 can be arranged at each axial end of the housing 11, and the cooling water can flow to each axial end of the housing 11 to cool the housing 11. Therefore, not only the stator core 32 in the stator 31 but also the coil ends 33a and 33b of the stator coil 33 can be cooled, thereby improving the cooling performance.

[0071] The electric compressor according to the second embodiment is the electric compressor according to the first embodiment, but further comprises: a first cooling water flow path 71 (flow path 71d) of the plurality of first cooling water flow paths 71 arranged on one axial side of the housing 11 is arranged over the entire circumference of the housing 11 and has a cooling water inlet 74 at its end; and a first cooling water flow path 71 (flow path 71a) of the plurality of first cooling water flow paths 71 arranged on the other axial side of the housing 11 is arranged over the entire circumference of the housing 11 and has a cooling water outlet 73 at its end. This allows the coil ends 33a and 33b of the stator coil 33 to be appropriately cooled by the cooling water.

[0072] The electric compressor according to the third embodiment is the electric compressor according to the second embodiment, but further comprises a first cooling water flow path 71 (flow path 71d) having an inlet 74 and a first cooling water flow path 71 (flow path 71a) having an outlet 73, disposed so as to face the coil ends 33a and 33b of the stator coil 33 constituting the stator 31. This allows the coil ends 33a and 33b of the stator coil 33 to be appropriately cooled by the cooling water.

[0073] The electric compressor according to the fourth embodiment is the electric compressor according to the second embodiment, but furthermore, the cross-sectional area of ​​the first cooling water flow path 71 is the same as the cross-sectional area of ​​the second cooling water flow path 72. As a result, the flow rate of the cooling water flowing through the first cooling water flow path 71 and the second cooling water flow path 72 remains unchanged, reducing pressure loss and improving cooling performance.

[0074] The electric compressor according to the fifth embodiment is the electric compressor according to any one of the first to fourth embodiments, wherein a plurality of second cooling water flow paths 72 are provided and are spaced apart in a direction inclined at a predetermined angle with respect to the axial direction of the housing 11. This reduces the gaps between the plurality of first cooling water flow paths 71, thereby improving cooling performance.

[0075] The electric compressor according to the sixth embodiment is the electric compressor according to any one of the first to fifth embodiments, wherein the first cooling water flow path 71 and the second cooling water flow path 72 are provided with protrusions 81 on their inner surfaces. This increases the inner surface area, thereby improving cooling performance.

[0076] The electric compressor according to the seventh embodiment is the electric compressor according to any one of the first to sixth embodiments, wherein the housing 11 is provided with protrusions 83 or recesses 82 on the radially outer outer surface of the plurality of first cooling water flow paths 71 and the second cooling water flow paths 72. This increases the surface area, thereby improving cooling performance.

[0077] The electric compressor according to the eighth embodiment is the electric compressor according to any one of the first to seventh embodiments, wherein a plurality of second cooling water flow paths 72 are arranged at intervals in the axial direction of the housing 11, and the channel cross-section has a square shape with irregular sides. This improves mold releasability during casting of the housing 11.

[0078] In the above embodiment, the electric compressor 10 is described as a two-stage compression type electric compressor, but it may be a one-stage compression type electric compressor. Furthermore, the bearings are air bearings, but they may be other bearings.

[0079] Explanation of symbols 10-Electric compressor, 11-Casing, 12-Rotating shaft, 12a-Low-pressure side shaft, 12b-High-pressure side shaft, 13-Low-pressure impeller, 14-High-pressure impeller, 21-Motor housing, 22-Low-pressure side bearing housing, 23-High-pressure side bearing housing, 31-Stator, 32-Stator core, 33-Stator coil, 33a-Low-pressure side coil end, 33b-High-pressure side coil end, 34-Rotor, 35-Rotor core, 36-Low-pressure side bearing sleeve, 37-High-pressure side bearing sleeve, 38-Low-pressure side air bearing, 39-High-pressure side air bearing, 41-Low-pressure compressor, 42-High-pressure compressor, 43-Low-pressure side housing, 44-High-pressure side housing, 45, 49-bolts, 46, 50-intake port, 47, 51-diffuser portion, 48, 52-vortex portion, 53-connecting flow path, 60-air flow path, 61-first air flow path, 62-second air flow path, 63-air inlet, 64-exhaust flow path, 65-low-pressure side space portion, 66-thrust disk, 67-axial air flow path, 68-radial air flow path, 70-cooling water flow path, 71-first cooling water flow path, 71a, 71b, 71c, 71d-flow path, 72-second cooling water flow path, 72a, 72b, 72c-flow path, 73-outlet portion, 74-inlet portion, 81-convex portion, 82-concave portion, 83-convex portion.

Claims

1. An electric compressor comprising: a housing having a cylindrical stator at its inner periphery; a rotating shaft disposed inside the housing and having a rotor facing the stator; a compressor impeller fixed to one side of the axial direction of the rotating shaft; and A cooling water flow path is provided in the housing on the radially outer side of the stator. The cooling water flow path has: a plurality of first cooling water flow paths arranged along the circumferential direction of the housing and spaced apart in the axial direction; and The second cooling water flow path is provided along a curved direction curved at a predetermined angle with respect to the circumferential direction of the housing, and connects end portions of the plurality of first cooling water flow paths.

2. The electric compressor according to claim 1, wherein The first cooling water flow path among the multiple first cooling water flow paths that is arranged on one side of the axial direction of the shell is arranged over the entire circumferential area of ​​the shell, and a cooling water inlet is provided at the end. The first cooling water flow path among the multiple first cooling water flow paths that is arranged on the other side of the axial direction of the shell is arranged over the entire circumferential area of ​​the shell, and a cooling water outlet is provided at the end.

3. The electric compressor according to claim 2, wherein: The first cooling water flow path provided with the inlet portion and the first cooling water flow path provided with the outlet portion are arranged to face coil ends of a stator coil constituting the stator.

4. The electric compressor according to any one of claims 1 to 3, wherein A channel cross-sectional area of ​​the first cooling water flow path is the same as a channel cross-sectional area of ​​the second cooling water flow path.

5. The electric compressor according to claim 1, wherein A plurality of the second cooling water flow paths are provided, and are arranged at intervals in a direction inclined at a predetermined angle with respect to the axial direction of the housing.

6. The electric compressor according to claim 1, wherein The first cooling water flow path and the second cooling water flow path are provided with convex portions on inner surfaces.

7. The electric compressor according to claim 1, wherein The housing may include a convex portion or a concave portion on an outer surface of the housing on the radially outer sides of the plurality of first cooling water flow paths and the second cooling water flow paths.

8. The electric compressor according to claim 1, wherein A plurality of the second cooling water flow paths are arranged at intervals in the axial direction of the housing, and each channel has a cross-sectional shape of an irregular quadrilateral.

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