Electric compressor device

Abstract

In the present invention, an electric compressor device includes: a motor including a rotating shaft, a compressor impeller provided on the rotating shaft, a rotor provided on the rotating shaft on the back surface side of the compressor impeller, and a stator coil positioned around the rotor; a journal bearing rotatably supporting the rotating shaft between the rotor and the compressor impeller; and a bearing housing that accommodates the journal bearing and includes a radially extending wall part extending in the radial direction of the rotating shaft between the stator coil and the compressor impeller. A cooling air flow passage for guiding cooling air for the coil introduced from the outside of the bearing housing to the stator coil is formed inside the radially extending wall part. All portions of the cooling air flow passage are positioned radially outward of the journal bearing.

Description

Electric Compressor Device

[0001] This application claims priority to Japanese Patent Application No. 2024-012721, filed with the Japan Patent Office on January 31, 2024, the contents of which are incorporated herein by reference.

[0002] Conventionally, electric compressors that use compressed air to cool a stator coil are known. For example, Patent Document 1 discloses an electric compressor that includes a low-pressure bearing housing, and a compressed air flow path that functions as cooling air is formed inside the low-pressure bearing housing. The compressed air flows sequentially through a one-side annular flow path, a radial flow path, an annular flow path, and an axial flow path before reaching the stator coil.

[0003] International Publication No. 2023 / 162160

[0004] However, the cooling air flows radially inward to a position close to the axis of the electric compressor, and then flows to an axial flow path located radially outward. Therefore, by the time it reaches the stator coil, the cooling air has already exchanged heat with various components of the electric compressor. As a more specific example, the cooling air exchanges heat with the thrust bearing in the low-pressure side bearing housing or the journal bearing near the thrust bearing, and the temperature of the cooling air is relatively high. This can make it difficult to effectively cool the stator coil.

[0005] An object of the present disclosure is to provide an electric compressor device that can effectively cool a stator coil.

[0006] An electric compressor device according to at least one embodiment of the present disclosure comprises: a rotating shaft; a compressor impeller provided on the rotating shaft; a motor including a rotor provided on the rotating shaft on the back side of the compressor impeller and a stator coil arranged around the rotor; a journal bearing that rotatably supports the rotating shaft between the rotor and the compressor impeller; and a bearing housing that accommodates the journal bearing, the bearing housing including a radially extending wall portion that extends radially of the rotating shaft between the stator coil and the compressor impeller, wherein a cooling air flow path is formed inside the radially extending wall portion to guide coil cooling air introduced from outside the bearing housing to the stator coil, and the entire cooling air flow path is located radially outward of the journal bearing.

[0007] According to the present disclosure, it is possible to provide an electric compressor device that can effectively cool a stator coil.

[0008] Fig. 2 is a schematic diagram of an electric compressor device according to one embodiment; Fig. 3 is a schematic diagram of a low-pressure side bearing housing according to one embodiment; Fig. 4 is a partial enlarged view of Fig. 2; Fig. 5 is a schematic perspective view of an anti-swirl plate according to one embodiment; Fig. 6 is a schematic diagram of an injection port and an anti-swirl plate according to one embodiment; Fig. 7 is a schematic diagram of an anti-swirl plate according to another embodiment;

[0009] Several embodiments of the present disclosure will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure and are merely illustrative examples. For example, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express relative displacements with a tolerance or angle or distance to the extent that the same function is achieved. For example, expressions expressing the equality of things, such as "same," "equal," and "homogeneous," not only express strict equality, but also express tolerance or differences to the extent that the same function is achieved. For example, expressions expressing shapes such as a square or cylindrical shape not only express shapes such as a square or cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is achieved. On the other hand, the expressions "comprise," "include," or "have" one component are not exclusive expressions that exclude the existence of other components. Note that similar components may be assigned the same reference numerals and descriptions thereof may be omitted.

[0010] 1 is a schematic diagram of an electric compressor device 10 according to an embodiment of the present disclosure. The electric compressor device 10 of this example is a two-stage compression compressor for supplying compressed air to a fuel cell mounted on a vehicle. The electric compressor device 10 includes a rotating shaft 12, a low-pressure compressor impeller 13 provided on one side of the rotating shaft 12, and a high-pressure compressor impeller 14 provided on the other side of the rotating shaft 12.

[0011] In the following description, the direction in which the axis of the rotating shaft 12 extends will be referred to as the "axial direction," and the circumferential direction and radial direction based on the axis will sometimes be simply referred to as the "circumferential direction" and the "radial direction," respectively. The outer radial direction is the side away from the axis, and the inner radial direction is the side approaching the axis.

[0012] The electric compressor device 10 further includes a motor 3. The motor 3 includes a rotor 4 provided on the rotary shaft 12 between a low-pressure compressor impeller 13 and a high-pressure compressor impeller 14, a stator 2 extending in the circumferential direction so as to surround the rotor 4, and a stator coil 5 supported by the stator 2.

[0013] The rotor 4 is located on the rear side (i.e., the other axial side) of the low-pressure compressor impeller 13. The stator 2 is supported by the inner circumferential surface of the motor housing 21. A plurality of stator coils 5 are arranged circumferentially, each positioned around the rotor 4. The stator coil 5 has a pair of coil ends 6 protruding axially from the stator 2. Each of the pair of coil ends 6 may be covered with a resin member (not shown). During the manufacturing process of the motor 3, a filling process is performed in which the stator coil 5 placed inside a mold is filled with liquid resin, and then a cooling process is performed to cool the mold. As a result, the pair of coil ends 6 are covered with the resin member. Hereinafter, when the term "coil end 6" is simply used, it refers to the coil end 6 on one side.

[0014] In some embodiments of the present disclosure, a motor cooling water passage 17 extending in the circumferential direction is formed inside the motor housing 21. The axial range of the motor cooling water passage 17 is included in the axial range of the stator 2. In other words, the motor cooling water passage 17 is disposed in an axial position between a pair of coil ends 6. The cooling water flowing through the motor cooling water passage 17 exchanges heat with the stator coil 5, thereby cooling the stator coil 5. In particular, the radially outer portions of the stator coil 5 are cooled by the cooling water.

[0015] The electric compressor device 10 further includes a low-pressure side journal bearing 15 and a high-pressure side journal bearing 16 that rotatably support the rotating shaft 12. The low-pressure side journal bearing 15 is located between the rotor 4 and the low-pressure compressor impeller 13, and the high-pressure side journal bearing 16 is located between the rotor 4 and the high-pressure compressor impeller 14. The low-pressure side journal bearing 15 is housed in a low-pressure side bearing housing 22 that is located on one axial side of the motor housing 21, and the high-pressure side journal bearing 16 is housed in a high-pressure side bearing housing 23 that is located on the other axial side of the motor housing 21. In this example, both the low-pressure side journal bearing 15 and the high-pressure side journal bearing 16 are air bearings.

[0016] In some embodiments, the cooling water flow passage 11 extending in the circumferential direction is formed only inside the high-pressure side bearing housing 23 out of the high-pressure side bearing housing 23 or the low-pressure side bearing housing 22 .

[0017] The electric compressor device 10 further includes a thrust bearing 8 that rotatably supports the rotating shaft 12. The thrust bearing 8 is disposed between the low-pressure side journal bearing 15 and the low-pressure compressor impeller 13 and is housed in a low-pressure side bearing housing 22. A disk 8a of the low-pressure side journal bearing 15 faces the low-pressure side bearing housing 22 (more specifically, a main body 76 described below) in the axial direction. In this example, the thrust bearing 8 is an air bearing. The disk 8a extends radially outward from a cylindrical portion of the low-pressure side journal bearing 15. The rotating shaft 12 is inserted into the cylindrical portion.

[0018] The low-pressure compressor impeller 13 is housed in a low-pressure side housing 43, and both are components of a low-pressure compressor 41. The low-pressure side housing 43 defines an intake port 46, a diffuser 47, a scroll portion 48, and a low-pressure discharge port (not shown).

[0019] The high-pressure compressor impeller 14 is housed in a high-pressure side housing 44, and both are components of the high-pressure compressor 42. The high-pressure side housing 44 defines an inlet 50, a diffuser 51, a scroll section 53, and a high-pressure discharge port (not shown). The low-pressure discharge port of the low-pressure compressor 41 and the inlet 50 of the high-pressure compressor 42 are connected by an intermediate pipe 54.

[0020] The operation of the electric compressor device 10 is outlined as follows. The rotating magnetic field generated by energizing the stator coil 5 acts on the permanent magnets provided on the rotor 4, causing the motor 3 to rotate the rotating shaft 12. The low-pressure compressor impeller 13 and the high-pressure compressor impeller 14 rotate together with the rotating shaft 12. As the low-pressure compressor impeller 13 rotates, external air passes through the suction port 46. The air passing through the suction port 46 is accelerated by the centrifugal force of the low-pressure compressor impeller 13. The accelerated air is decelerated and pressurized by the diffuser 47 before flowing through the scroll section 48. The compressed air in the scroll section 48 is discharged from the low-pressure discharge port and flows through the intermediate pipe 54. The intermediate pipe 54 directs the compressed air to the suction port 50. The air passing through the suction port 50 is accelerated by the centrifugal force of the high-pressure compressor impeller 14. The accelerated air is decelerated and pressurized by the diffuser 51 before flowing through the scroll section 53. The compressed air in the scroll section 53 is discharged from a high-pressure discharge port and sent to the fuel cell.

[0021] <Overview of Cooling System> Figure 2 is a schematic diagram of the low-pressure side bearing housing 22 according to one embodiment of the present disclosure. The low-pressure side bearing housing 22 includes a radially extending wall portion 25 extending radially between the stator coil 5 and the low-pressure compressor impeller 13. A flow path is formed inside the radially extending wall portion 25, which guides compressed air bled from the intermediate piping 54 as cooling air to an object to be cooled (this flow path is omitted in Figure 1). In this example, the object to be cooled includes the thrust bearing 8 and the stator coil 5. More specifically, a bearing cooling flow path 90 through which bearing cooling air flows and a cooling air flow path 70 through which coil cooling air flows are formed inside the radially extending wall portion 25. The configuration of the bearing cooling flow path 90 will be described later.

[0022] The coil cooling air flowing through the cooling air flow path 70 is supplied to the coil ends 6 of the stator coil 5 (details will be described later). In the present embodiment, the entire cooling air flow path 70 is located radially outward from the outermost surface 15a of the low-pressure side journal bearing 15. In some embodiments of the present disclosure, the entire cooling air flow path 70 is located radially outward from a cylindrical outer peripheral surface 29 of a cylindrical wall portion 27 (described later) of the low-pressure side bearing housing 22. In some embodiments, the entire cooling air flow path 70 is located radially outward from a swirl prevention plate 33 (described later) and is also located radially outward from the radial center of the disk 8a of the thrust bearing 8.

[0023] According to the above configuration, it is possible to suppress heat exchange between the coil cooling air flowing through the cooling air flow path 70 and components such as the low-pressure side journal bearing 15 and the thrust bearing 8 located therearound. Since it is possible to suppress a temperature rise in the coil cooling air before it reaches the stator coil 5, it is possible to effectively cool the coil ends 6 of the stator coil 5.

[0024] 2 , the bearing cooling flow path 90 includes a bearing upstream flow path 91 and a bearing downstream flow path 93. The bearing upstream flow path 91 is configured to guide low-pressure compressed air bled from the intermediate piping 54 to the thrust bearing 8 as bearing cooling air. The low-pressure compressed air is guided by the bearing upstream flow path 91 and flows into the bearing accommodating space 19 for the thrust bearing 8 formed inside the low-pressure side bearing housing 22. The bearing downstream flow path 93 is configured to guide the bearing cooling air that has completed heat exchange with the thrust bearing 8 in the bearing accommodating space 19 to the outside. Both the bearing upstream flow path 91 and the bearing downstream flow path 93 extend radially.

[0025] <Cooling air flow path 70> As shown in FIG. 3 , the cooling air flow path 70 has an inlet flow path 71 extending radially and axially, a circumferentially extending flow path 75 connected to a downstream end 72 of the inlet flow path 71, and a plurality of injection ports 78 arranged closer to the stator coil 5 than the circumferentially extending flow path 75 (i.e., on the other axial side).

[0026] In this example, the upstream end 69 of the inlet flow passage 71 is connected to the bearing upstream flow passage 91, and the bearing cooling air extracted from the bearing upstream flow passage 91 is guided as coil cooling air toward the stator coil 5. Note that, although the inlet flow passage 71 extends along the radial and axial directions in the example of Figure 3, the present disclosure is not limited thereto, and the inlet flow passage 71 may extend only along the axial or radial direction.

[0027] The circumferentially extending flow passage 75 extends circumferentially to surround the rotating shaft 12. In one example in the present disclosure, a radially outer end of the circumferentially extending flow passage 75 is connected to the downstream end 72 of the inlet flow passage 71. A portion of the radial range of the circumferentially extending flow passage 75 overlaps with the radial range of the disk 8 a of the thrust bearing 8. However, it is preferable that the circumferentially extending flow passage 75 be located radially outward, and in this example, the entire circumferentially extending flow passage 75 is located outside the radial center of the disk 8 a. The multiple injection ports 78 are arranged at intervals in the circumferential direction. Each injection port 78 is configured to inject the coil cooling air in the circumferentially extending flow passage 75 toward the coil ends 6 of the stator coil 5.

[0028] According to the above configuration, coil cooling air is injected from each of the multiple injection ports 78 arranged in the circumferential direction, thereby uniformly cooling the air around the stator coil 5. This allows the electric compressor device 10 to effectively cool the coil ends 6.

[0029] Furthermore, the inlet flow path 71 of the cooling air flow path 70 guides bearing cooling air bled from the bearing upstream flow path 91 of the bearing cooling flow path 90 to the stator coil 5 as coil cooling air, so that compressed air bled from the intermediate piping 54 can be used as coil cooling air. Furthermore, the bearing cooling air before exchanging heat with the thrust bearing 8 flows through the inlet flow path 71 as coil cooling air, so the temperature of the coil cooling air before it reaches the stator coil 5 can be lowered. This allows the stator coil 5 to be cooled effectively.

[0030] Returning to Fig. 2 , the multiple injection ports 78 will be described. In some embodiments, the multiple injection ports 78 include multiple inner injection ports 79 that are arranged radially inward of the center (two-dot chain line M) of the radial range of the stator coil 5. More specifically, the inner injection ports 79 include first inner injection ports 79a that are arranged at equal intervals in the circumferential direction, and second inner injection ports 79b that are arranged at equal intervals in the circumferential direction and radially inward of the first inner injection ports 79a.

[0031] The pitch angle of the multiple first inner jet ports 79a is greater than or equal to 15 degrees and less than or equal to 20 degrees. In other words, the circumferential distance between the centers of two circumferentially adjacent first inner jet ports 79a is greater than or equal to 15 degrees and less than or equal to 20 degrees, based on the axis of the rotating shaft 12. In this example, the pitch angle is 20 degrees, and there are 18 first inner jet ports 79a. Similarly, the pitch angle of the multiple second inner jet ports 79b is also greater than or equal to 15 degrees and less than or equal to 20 degrees. As an example, the pitch angle is also 20 degrees, and there are 18 second inner jet ports 79b. In some embodiments, the centers of the multiple first inner jet ports 79a and the centers of the multiple second inner jet ports 79b are located at the same circumferential position as each other (see FIG. 5 ).

[0032] According to the inventor's findings, the temperature of the stator coil 5 is more likely to rise radially inward than radially outward. This is because the further radially inward in the internal space of the motor housing 21, the more difficult it is for the stator coil 5 to dissipate heat. In this regard, with a configuration in which multiple inner injection ports 79 are provided, the coil cooling air injected from the multiple inner injection ports 79 can effectively cool the coil ends 6 located inside the center of the radial range of the stator coil 5 (two-dot chain line M).

[0033] 3, the detailed relationship between the low-pressure side bearing housing 22 and the cooling air flow path 70 will be described. The radially extending wall portion 25 of the low-pressure side bearing housing 22 includes a main body portion 76 having the inlet flow path 71 formed therein. The above-mentioned bearing cooling flow path 90 is also formed inside the main body portion 76.

[0034] The radially extending wall portion 25 further includes an extension portion 73 that is configured separately from the main body portion 76. The extension portion 73 is a plate that extends in the radial direction and is attached to the main body portion 76 by a plurality of fastening members (not shown). A plurality of injection ports 78 are formed in the extension portion 73. Each injection port 78 is a circular hole that penetrates the extension portion 73 in the axial direction.

[0035] An end face 77 of the main body portion 76 on the stator coil 5 side includes a concave surface 74 that is recessed toward the low-pressure compressor impeller 13 side (i.e., one axial side). The concave surface 74 extends in the circumferential direction to surround the rotating shaft 12, and the radially outer end of the concave surface 74 is connected to the downstream end 72 of the inlet flow passage 71. An end face 73a of the extension portion 73 on the low-pressure compressor impeller 13 side cooperates with the concave surface 74 to define a circumferentially extending flow passage 75.

[0036] According to the above configuration, the extension portion 73 is configured separately from the main body portion 76, which improves the design freedom for arranging the multiple injection ports 78. As a result, the multiple injection ports 78 are arranged in positions suitable for cooling the coil ends 6 of the stator coil 5.

[0037] 3 , the low-pressure side bearing housing 22 further includes a cylindrical wall portion 27 extending from a radially inner end portion 76 a of the main body portion 76 toward the rotor 4 side (i.e., the other axial side). The cylindrical wall portion 27 has a cylindrical inner circumferential surface 28 that surrounds the low-pressure side journal bearing 15, and a cylindrical outer circumferential surface 29 opposite the cylindrical inner circumferential surface 28. The cylindrical wall portion 27 and the main body portion 76 are integrally formed from the same material.

[0038] 3 and 4, the low-pressure side bearing housing 22 further includes a plurality of anti-swirl plates 33 arranged on the cylindrical outer peripheral surface 29. Each of the anti-swirl plates 33 has a thickness in the circumferential direction. Each of the anti-swirl plates 33 also includes an axially extending portion 31 that extends along the axial direction.

[0039] According to the inventor's findings, a swirling flow of internal air is generated inside the motor housing 21 in the rotational direction of the rotating shaft 12 (arrow A in FIGS. 2 and 4 ). As a more specific example, a high-pressure-side cooling air passage (not shown) is formed inside the high-pressure-side bearing housing 23 (see FIG. 1 ), through which compressed air bled from the intermediate piping 54 flows as cooling air. The cooling air flowing from the high-pressure-side cooling air passage into the motor housing 21 is given a swirling component by the rotation of the rotating shaft 12 and the rotor 4 as it flows toward one side in the axial direction. As a result, the internal air flows inside the motor housing 21 with a swirling component.

[0040] If the coil cooling air injected from the injection port 78 flows circumferentially due to the swirling flow of the internal air, the coil cooling air will not hit the coil ends 6, making it difficult to cool the stator coil 5. In this regard, with the above-described configuration, the internal air hits the swirl prevention plate 33, reducing the swirling component of the internal air. This prevents the coil cooling air that merges with the internal air from swirling in the circumferential direction. This allows the stator coil 5 to be cooled effectively.

[0041] 5 is a schematic diagram showing the jet nozzles 78 and the anti-swirl plates 33 according to one embodiment of the present disclosure. The arrow B in the figure indicates the direction of rotation of the rotary shaft 12 (similarly to FIG. 6 ). Each of the multiple anti-swirl plates 33 is located radially inward of the multiple jet nozzles 78, and more specifically, is located radially inward of the multiple second inner jet nozzles 79 b.

[0042] The multiple swirl prevention plates 33 and the multiple injection ports 78 are arranged alternately in the circumferential direction. More specifically, any given swirl prevention plate 33 is located between two adjacent first inner injection ports 79a in the circumferential direction, and is also located between two adjacent second inner injection ports 79b in the circumferential direction. The number of swirl prevention plates 33 is the same as the number of first inner injection ports 79a and the number of second inner injection ports 79b.

[0043] According to the above configuration, one of the swirl prevention plates 33 is disposed for each of the multiple injection ports 78 on the upstream side in the rotation direction of the rotating shaft 12 (opposite the arrow B). The swirl prevention plate 33 more reliably removes the swirling component of the swirling internal air before it hits the coil cooling air from the injection ports 78. This more reliably prevents the coil cooling air injected from the injection ports 78 from swirling in the circumferential direction.

[0044] 6 is a schematic diagram of a swirl prevention plate 33A (33) according to another embodiment. The swirl prevention plate 33A further includes an inclined extension 32 connected to the rotor 4-side end 31a of the axial extension 31 (the rotor 4 side is synonymous with the other axial side). The inclined extension 32 extends linearly toward the rotor 4 side, toward the upstream side in the rotation direction of the rotating shaft 12 (the side opposite to the arrow B). Internal air (arrow A) flowing toward one side in the axial direction along the rotation direction of the rotating shaft 12 is guided by the inclined extension 32 and the axial extension 31 in order and impinges on the extension 73 (see FIG. 3).

[0045] According to the above configuration, it is possible to suppress pressure loss when the internal air flowing along the rotation direction of the rotary shaft 12 hits the radially extending wall portion 25. This makes it possible to efficiently remove the swirling component of the internal air.

[0046] <Modification> The electric compressor device 10 illustrated in FIG. 1 may be a turbocharger instead of a two-stage compressor. In this case, a turbine impeller is provided on the other side of the rotary shaft 12 instead of the high-pressure compressor impeller 14, and the intermediate piping 54 is not provided. The compressed air delivered by the low-pressure compressor impeller 13 is delivered to the combustion chamber of the engine. Even in this case, if the entire cooling air flow path 70 is positioned radially outward of the outermost peripheral surface 15a of the low-pressure journal bearing 15, the temperature rise of the coil cooling air before it reaches the stator coil 5 can be suppressed. Therefore, the coil ends 6 of the stator coil 5 can be effectively cooled.

[0047] 2 may extract compressed air directly from the intermediate pipe 54 instead of extracting bearing cooling air from the bearing upstream flow path 91. Even in this case, the extracted compressed air is guided to the stator coil 5 as coil cooling air by the cooling air flow path 70. Furthermore, the bearing upstream flow path 91 and the bearing upstream flow path 92 do not have to be provided.

[0048] 2 and 3 may be integrally formed from the same material. In this case, the low-pressure side bearing housing 22 may be manufactured by additive manufacturing.

[0049] <Summary> The contents described in the above-described embodiments can be understood, for example, as follows.

[0050] 1) An electric compressor device (10) according to at least one embodiment of the present disclosure comprises: a rotating shaft (12); a compressor impeller (low-pressure compressor impeller 13) provided on the rotating shaft; a motor (3) including a rotor (4) provided on the rotating shaft on the back side of the compressor impeller and a stator coil (5) arranged around the rotor; a journal bearing (low-pressure side journal bearing 15) that rotatably supports the rotating shaft between the rotor and the compressor impeller; and a bearing housing (low-pressure side bearing housing 22) that accommodates the journal bearing and includes a radially extending wall portion (25) that extends in the radial direction of the rotating shaft between the stator coil and the compressor impeller, wherein a cooling air flow path (70) is formed inside the radially extending wall portion to guide coil cooling air introduced from outside the bearing housing to the stator coil, The entire cooling air flow path is located radially outward of the journal bearing.

[0051] The configuration of 1) above can prevent the coil cooling air flowing through the cooling air passage from exchanging heat with the journal bearing and the components around it. This can prevent the coil cooling air from increasing in temperature before reaching the stator coil, thereby realizing an electric compressor device that can effectively cool the stator coil.

[0052] 2) In some embodiments, in the electric compressor device described in 1) above, the cooling air flow path has: an inlet flow path (71) extending along at least one of the radial direction and the axial direction of the rotating shaft; a circumferentially extending flow path (75) connected to a downstream end (72) of the inlet flow path and extending so as to surround the rotating shaft; and a plurality of injection ports (78) arranged at intervals in the circumferential direction of the rotating shaft on the stator coil side of the circumferentially extending flow path, and each configured to inject the coil cooling air in the circumferentially extending flow path toward the stator coil.

[0053] According to the configuration of 2), the coil cooling air is injected from each of the multiple injection ports arranged in the circumferential direction, so the air around the stator coil is cooled uniformly, thereby enabling the electric compressor device to effectively cool the stator coil.

[0054] 3) In some embodiments, in the electric compressor device described in 2), the plurality of injection ports include a plurality of inner injection ports (78) arranged inward from the center of the radial range of the stator coil.

[0055] According to the inventor's knowledge, the temperature of the stator coil is more likely to rise on the inside than on the outside in the radial direction. In this regard, with the configuration of 3) above, the coil cooling air injected from the multiple inside injection ports can effectively cool the stator coil located inside the center of the radial range.

[0056] 4) In some embodiments, in the electric compressor device described in 2) or 3) above, the radially extending wall portion has a main body portion (76) in which the inlet flow path is formed, and an extension portion (73) that extends in the radial direction on the stator coil side with respect to the circumferentially extending flow path and in which the plurality of injection ports are formed, and an end face (77) of the main body portion on the stator coil side is recessed toward the compressor impeller side and includes a concave surface (74) to which the downstream end of the inlet flow path is connected, and the extension portion is configured separately from the main body portion and is attached to the main body portion so as to cooperate with the concave surface to define the circumferentially extending flow path.

[0057] According to the configuration of 4) above, the extension portion is configured separately from the main body portion, which increases the degree of freedom in designing the arrangement of the multiple injection ports, and the multiple injection ports can be arranged in positions suitable for cooling the stator coil.

[0058] 5) In some embodiments, the electric compressor device is described in any one of 1) to 4) above, wherein the bearing housing further includes: a cylindrical wall portion (27) extending from the radially inner end portion (76a) of the radially extending wall portion toward the rotor in the axial direction of the rotating shaft, the cylindrical wall portion (27) having a cylindrical inner peripheral surface (28) surrounding the journal bearing; and a swirl prevention plate (33) having an axially extending portion (31) extending along the axial direction on the cylindrical outer peripheral surface (29) of the cylindrical wall portion.

[0059] According to the inventor's findings, a swirling flow of internal air occurs inside a motor in the direction of rotation of the rotating shaft. If the coil cooling air injected from the injection port flows in a circumferential direction due to the swirling flow, it becomes difficult to cool the stator coil. In this regard, with the configuration of 5) above, the swirl prevention plate reduces the swirling of the internal air, thereby preventing the coil cooling air that merges with the internal air from swirling in the circumferential direction. This allows the stator coil to be cooled effectively.

[0060] 6) In some embodiments, in the electric compressor device described in 5) above, the anti-swirl plate further has an inclined extension portion (32) connected to the rotor-side end (31a) of the axial extension portion, and extending so as to move toward the upstream side in the rotation direction of the rotating shaft as it moves toward the rotor side.

[0061] According to the configuration of 6) above, pressure loss when the internal air flowing along the rotation direction of the rotary shaft hits the inclined extension portion can be suppressed, thereby efficiently removing the swirling component of the internal air.

[0062] 7) In some embodiments, the electric compressor device described in any one of 1) to 6) above further includes a thrust bearing (8) that rotatably supports the rotating shaft between the journal bearing and the compressor impeller and is housed in the bearing housing, wherein a bearing upstream flow path (91) is further formed inside the bearing housing for guiding bearing cooling air introduced from outside the bearing housing toward the thrust bearing, and the cooling air flow path is configured to guide the bearing cooling air bled from the bearing upstream flow path to the stator coil as coil cooling air.

[0063] According to the configuration of 7) above, the bearing cooling air before heat exchange with the thrust bearing is used as the coil cooling air, which allows the temperature of the coil cooling air before it reaches the stator coil to be lowered, thereby enabling the stator coil to be cooled effectively.

[0064] 8) In some embodiments, the electric compressor device is described in any one of 1) to 7) above, wherein the compressor impeller is a low-pressure compressor impeller (13) provided on one side of the rotating shaft, and the electric compressor device further includes: a high-pressure compressor impeller (14) provided on the other side of the rotating shaft; and an intermediate pipe (54) for guiding compressed air delivered by the low-pressure compressor impeller to the high-pressure compressor impeller, and the cooling air flow path is configured to guide the compressed air bled from the intermediate pipe to the stator coil as cooling air for the coil.

[0065] According to the above configuration 8), the compressed air extracted from the intermediate pipe can be used as cooling air for the coil.

[0066] DESCRIPTION OF SYMBOLS 2: Stator 3: Motor 4: Rotor 5: Stator coil 6: Coil end 8: Thrust bearing 8a: Disk 10: Electric compressor device 11: Cooling water flow path 12: Rotating shaft 13: Low-pressure compressor impeller 14: High-pressure compressor impeller 15: Low-pressure side journal bearing 15a: Outermost surface 16: High-pressure side journal bearing 17: Motor cooling water flow path 19: Bearing accommodating space 21: Motor housing 22: Low-pressure side bearing housing 23: High-pressure side bearing housing 25: Radially extending wall portion 27: Cylindrical wall portion 28: Cylindrical inner peripheral surface 29: Cylindrical outer peripheral surface 31: Axial extending portion 31a: End portion 32: Inclined extending portion 33, 33A: Swirl prevention plate 41 : Low-pressure compressor 42 : High-pressure compressor 43 : Low-pressure side housing 44 : High-pressure side housing 46 : Intake port 47 : Diffuser 48 : Scroll section 50 : Intake port 51 : Diffuser 53 : Scroll section 54 : Intermediate piping 69 : Upstream end 70 : Cooling air flow path 71 : Inlet flow path 72 : Downstream end 73 : Extension section 73a : End face 74 : Concave surface 75 : Circumferentially extending flow path 76 : Main body section 76a : Inner end portion 77 : End face 78 : Injection port 79 : Inner injection port 79a : First inner injection port 79b : Second inner injection port 90 : Bearing cooling flow path 91 : Bearing upstream flow path 93 : Bearing downstream flow path A, B : Arrow M : Two-dot chain line

Claims

1. An electric compressor device comprising: a rotating shaft; a compressor impeller provided on the rotating shaft; a motor including a rotor provided on the rotating shaft behind the compressor impeller and a stator coil arranged around the rotor; a journal bearing that rotatably supports the rotating shaft between the rotor and the compressor impeller; and a bearing housing that accommodates the journal bearing, the bearing housing including a radially extending wall portion that extends in the radial direction of the rotating shaft between the stator coil and the compressor impeller, wherein a cooling air flow path is formed inside the radially extending wall portion to guide coil cooling air introduced from outside the bearing housing to the stator coil, and all portions of the cooling air flow path are located radially outward of the journal bearing.

2. The electric compressor device according to claim 1, wherein the cooling air flow path comprises: an inlet flow path extending along at least one of the radial direction and the axial direction of the rotating shaft; a circumferentially extending flow path connected to the downstream end of the inlet flow path and extending so as to surround the rotating shaft; and a plurality of injection ports arranged at intervals in the circumferential direction of the rotating shaft on the stator coil side of the circumferentially extending flow path, and each injection port configured to inject the coil cooling air in the circumferentially extending flow path towards the stator coil.

3. The electric compressor device according to claim 2, wherein the plurality of injection ports include a plurality of inner injection ports arranged inside the center of the radial range of the stator coil.

4. An electric compressor device according to claim 2 or 3, wherein the radially extending wall portion has: a main body portion in which the inlet flow path is formed; and an extension portion which extends in the radial direction on the stator coil side with respect to the circumferentially extending flow path and in which the plurality of injection ports are formed; an end face of the main body portion on the stator coil side is recessed toward the compressor impeller side and includes a concave surface to which the downstream end of the inlet flow path is connected; and the extension portion is configured separately from the main body portion and is attached to the main body portion so as to define the circumferentially extending flow path in cooperation with the concave surface.

5. An electric compressor device according to any one of claims 1 to 3, wherein the bearing housing further includes: a cylindrical wall portion extending from the radially inner end of the radially extending wall portion toward the rotor in the axial direction of the rotating shaft, the cylindrical wall portion having a cylindrical inner circumferential surface surrounding the journal bearing; and a swirl prevention plate having an axially extending portion extending along the axial direction on the cylindrical outer circumferential surface of the cylindrical wall portion.

6. An electric compressor device as described in claim 5, wherein the anti-swirl plate further has an inclined extending portion connected to the rotor-side end of the axial extending portion, the inclined extending portion extending so as to move toward the upstream side in the rotation direction of the rotating shaft as it moves toward the rotor side.

7. An electric compressor device according to any one of claims 1 to 3, further comprising a thrust bearing that rotatably supports the rotating shaft between the journal bearing and the compressor impeller and is housed in the bearing housing, wherein an upstream bearing flow path is further formed inside the bearing housing for guiding bearing cooling air introduced from outside the bearing housing toward the thrust bearing, and the cooling air flow path is configured to guide the bearing cooling air bled from the upstream bearing flow path to the stator coil as coil cooling air.

8. An electric compressor device according to any one of claims 1 to 3, wherein the compressor impeller is a low-pressure compressor impeller provided on one side of the rotating shaft, and the electric compressor device further comprises: a high-pressure compressor impeller provided on the other side of the rotating shaft; and an intermediate pipe for guiding compressed air delivered by the low-pressure compressor impeller to the high-pressure compressor impeller, and the cooling air flow path is configured to guide the compressed air extracted from the intermediate pipe to the stator coil as cooling air for the coil.

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