Electric compressor

Abstract

In this electric compressor, a stator coil comprises a first coil end located between a stator core and a first compressor impeller. A resin molded section is configured so as to cover at least part of the first coil end. A motor housing comprises a bearing mount for supporting a first journal bearing, a cylindrical part in the interior of which a cooling channel through which a cooling medium flows is formed, and an annular wall provided so as to partition the first compressor impeller and the first coil end. The resin molded section comprises an end wall part located between the first coil end and the annular wall, and an inner peripheral wall part located between the first coil end and the bearing mount. The end wall part comprises a surface in contact with the annular wall, and a surface in contact with the first coil end. There is a gap provided between the inner peripheral wall part and the bearing mount.

Description

Electric compressor

[0001] The present disclosure relates to an electric compressor.

[0002] Patent Document 1 discloses an electric compressor in which compressor impellers are provided on one end and the other end of a rotating shaft of a motor. In this electric compressor, a cooling passage through which a coolant flows is formed in the motor housing, and the motor housing and the coil end of the motor are connected by a heat-conductive material (resin mold). The cold energy of the coolant is transferred to the coil end of the motor via the motor housing and the resin mold, thereby cooling the coil end.

[0003] Japanese Patent Application Laid-Open No. 2015-209845

[0004] In the electric compressor of Patent Document 1, the journal bearing provided on one end of the rotating shaft (on the low-pressure compressor side in the example shown in Patent Document 1) is supported by a bearing pedestal of the motor housing, and the bearing pedestal is in contact with the resin mold. Therefore, heat from the coil end on the one end of the rotating shaft is easily transferred to the journal bearing via the resin mold and the bearing pedestal, which can easily cause the journal bearing to become too hot.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure has an object to provide an electric compressor that can cool the coil ends of a motor while suppressing an increase in the temperature of journal bearings.

[0006] In order to achieve the above object, an electric compressor according to at least one embodiment of the present disclosure is an electric compressor comprising: a rotating shaft; a first compressor impeller provided on one end side of the rotating shaft; a motor including a rotor provided on the rotating shaft behind the first compressor impeller and a stator arranged around the rotor; and a first journal bearing rotatably supporting the rotating shaft between the rotor and the first compressor impeller, wherein the stator includes a stator core, a stator coil, a resin mold, and a motor housing, and the stator coil includes a first coil end located between the stator core and the first compressor impeller, and the resin mold is configured to cover at least a part of the first coil end, and the motor housing includes: a bearing base portion supporting the first journal bearing; and a cylindrical portion surrounding the stator core, the first coil end, and the resin mold, the cylindrical portion having a cooling flow path formed therein through which a cooling medium flows. an annular wall portion connecting the end of the cylindrical portion on the first compressor impeller side to the bearing base portion and separating the first compressor impeller from the first coil end; the resin mold including: an end wall portion located between the first coil end and the annular wall portion; and an inner circumferential wall portion located between the first coil end and the bearing base portion; the end wall portion including a surface in contact with the annular wall portion and a surface in contact with the first coil end; and a gap provided between the inner circumferential wall portion and the bearing base portion.

[0007] According to at least one embodiment of the present disclosure, there is provided an electric compressor that can cool the coil ends of a motor while suppressing an increase in temperature of a journal bearing.

[0008] 7 is a schematic cross-sectional view including the rotation axis CA of an electric compressor 2 according to an embodiment of the present disclosure. FIG. 7 is a schematic cross-sectional view enlarging the vicinity of the journal bearing 22 in the electric compressor 2 shown in FIG. 1. FIG. 7 is a schematic cross-sectional view showing a modified example of the electric compressor 2 shown in FIG. 2. FIG. 7 is a schematic cross-sectional view showing an example of an A-A cross section (a cross section perpendicular to the axial direction) of the electric compressor 2 shown in FIG. 3. FIG. 7 is a schematic cross-sectional view showing another ... modified example of the electric compressor 2 shown in FIG. 2. FIG. 7 is a schematic cross-sectional view showing yet another modified example of the electric compressor 2 shown in FIG. 2. FIG. 7 is a schematic cross-sectional view partially showing a cross section perpendicular to the radial direction at the position of the bypass hole 72 in the electric compressor 2 shown in FIG.

[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 merely illustrative examples and are not intended to limit the scope of the invention. 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," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0010] Fig. 1 is a schematic cross-sectional view including a rotation axis CA of an electric compressor 2 according to one embodiment of the present disclosure. As shown in Fig. 1, the electric compressor 2 is a two-stage compressor including a motor 4, a high-pressure compressor 6 driven by the motor 4, and a low-pressure compressor 8 driven by the motor 4. The electric compressor 2 is configured so that air compressed by the low-pressure compressor 8 is further compressed by the high-pressure compressor 6.

[0011] The motor 4 includes a rotor 10 and a stator 12 disposed around the rotor 10. The high-pressure compressor 6 includes a compressor impeller 14 (first compressor impeller) provided on one end of the rotary shaft 5, and a compressor housing 16 (first compressor housing) that houses the compressor impeller 14. The low-pressure compressor 8 includes a compressor impeller 18 (second compressor impeller) provided on the other end of the rotary shaft 5 (the opposite side to the compressor impeller 14), and a compressor housing 20 (second compressor housing) that houses the compressor impeller 18.

[0012] 1 is the rotation axis of the rotating shaft 5, i.e., the rotation axis of each of the compressor impeller 14, the compressor impeller 18, and the rotor 10. In the following description, unless otherwise specified, the term "axial direction" means the axial direction of the electric compressor 2, i.e., a direction parallel to the rotation axis CA, the term "radial direction" means the radial direction of the electric compressor 2, i.e., a radial direction centered on the rotation axis CA, and the term "circumferential direction" means the circumferential direction of the electric compressor 2, i.e., a circumferential direction centered on the rotation axis CA, unless otherwise specified.

[0013] The rotor 10 is provided on the rotating shaft 5 on the back surface 14b side of the compressor impeller 14 (on the back surface 18b side of the compressor impeller 18), and includes a permanent magnet 11 and a cylindrical holding member 13 that covers the permanent magnet 11 and holds it to the rotor 10.

[0014] The electric compressor 2 includes a journal bearing 22 (first journal bearing) that rotatably supports the rotating shaft 5 between the rotor 10 and the compressor impeller 14, a journal bearing 24 (second journal bearing) that rotatably supports the rotating shaft 5 between the rotor 10 and the compressor impeller 18, and a thrust bearing 26 that is provided between the journal bearing 24 and the compressor impeller 18 and receives a thrust load from the rotating shaft 5. Each of the journal bearings 22 and 24 may be, for example, an air bearing.

[0015] The stator 12 includes a stator core 30 , a stator coil 32 , a resin mold 34 , and a motor housing 36 .

[0016] The stator coil 32 includes a coil end 38 (first coil end) located between the stator core 30 and the compressor impeller 14, and a coil end 40 (second coil end) located between the stator core 30 and the compressor impeller 18. The coil end 38 is provided to protrude in the axial direction from the stator core 30 toward the compressor impeller 14, and the coil end 40 is provided to protrude in the axial direction from the stator core 30 toward the compressor impeller 18.

[0017] The resin mold 34 is made of resin and is configured in an annular shape along the circumferential direction so as to cover at least a portion of the coil end 38 , at least a portion of the stator core 30 , and at least a portion of the coil end 40 .

[0018] The motor housing 36 includes a bearing base portion 44 that supports the journal bearings 22, a cylindrical portion 46 that surrounds the stator core 30, the coil ends 38, the coil ends 40, and the resin mold 34 and forms the outer wall of the motor 4, and an annular wall portion 48 that separates the compressor impeller 14 and the coil ends 38.

[0019] The bearing pedestal 44 is configured in a cylindrical shape along the circumferential direction, accommodates the journal bearing 22 inside, and supports the outer peripheral surface of the journal bearing 22. The bearing pedestal 44 is provided so as to protrude in the axial direction from an inner end 49 of the annular wall 48 in the radial direction toward the opposite side from the compressor impeller 14 (the permanent magnet 11 side of the rotor 10).

[0020] A cooling flow path 47 through which a coolant (cooling medium) such as cooling water flows is formed inside the cylindrical portion 46 at a position radially outward of the stator core 30, the coil ends 38, the coil ends 40, and the resin mold 34. In the cross section illustrated in Fig. 1, multiple cross sections of the cooling flow path 47 are arranged at intervals in the axial direction.

[0021] The annular wall portion 48 is configured in an annular shape along the circumferential direction and, in the cross section shown, extends radially so as to connect an end 50 of the cylindrical portion 46 on the compressor impeller 14 side and the bearing base 44. Cooling air supply holes 51 are formed in the annular wall portion 48 to supply cooling air to the journal bearings 22. In the exemplary embodiment shown, the cooling air supply holes 51 radially penetrate the annular wall portion 48 and are configured to guide cooling air supplied from outside the motor housing 36 to the journal bearings 22.

[0022] In the illustrated exemplary embodiment, the electric compressor 2 includes a bearing housing 52 that is configured as a separate component from the motor housing 36. The bearing housing 52 is provided between the coil end 40 and the compressor impeller 18, and houses the journal bearing 24 and the thrust bearing 26.

[0023] The bearing housing 52 includes a bearing pedestal 53 and an annular wall 54. The bearing pedestal 53 is cylindrical in the circumferential direction, accommodates the journal bearing 24 inside, and supports the outer peripheral surface of the journal bearing 24. The bearing pedestal 53 is provided so as to protrude in the axial direction from an inner end 55 of the annular wall 54 in the radial direction toward the opposite side from the compressor impeller 18 (the permanent magnet 11 side of the rotor 10).

[0024] The annular wall portion 54 is provided to separate the compressor impeller 18 and the coil end 40. The annular wall portion 54 is configured in an annular shape along the circumferential direction and extends along the radial direction in the cross section shown in the figure. An outer end portion 56 of the annular wall portion 54 in the radial direction is held in a sandwiched state between the cylindrical portion 46 of the motor housing 36 and the compressor housing 20 of the low-pressure compressor 8.

[0025] A gap g0 is formed between the coil end 40 and the bearing housing 52, extending radially from a position outside the coil end 40 to a position inside the coil end 40. In the example shown, a gap g01 extending radially is formed between the coil end 40 and the annular wall portion 54, and a gap g02 extending axially and communicating with the gap g01 is formed between the coil end 40 and the bearing base portion 53. The gap g0 (gap g01 and gap g02) may be formed over the entire circumferential direction. In other words, the resin mold 34 and the bearing housing 52 do not need to be in contact with each other.

[0026] Fig. 2 is a schematic cross-sectional view showing an enlarged view of the vicinity of the journal bearing 22 in the electric compressor 2 shown in Fig. 1. As shown in Fig. 2, the resin mold 34 includes an end wall portion 60, an inner peripheral wall portion 62, and an outer peripheral wall portion 63.

[0027] The end wall portion 60 is located between the coil end 38 and the annular wall portion 48, and includes a surface 60a that contacts the annular wall portion 48 and a surface 60b that contacts the coil end 38. The end wall portion 60 is configured in an annular shape along the circumferential direction, and in the cross section shown in the figure, extends along the radial direction so as to connect the end of the inner circumferential wall portion 62 on the compressor impeller 14 side and the end of the outer circumferential wall portion 63 on the compressor impeller 14 side.

[0028] The inner circumferential wall portion 62 is located between the coil end 38 and the bearing pedestal 44, and a radial gap g1 is provided between the inner circumferential wall portion 62 and the bearing pedestal 44. The inner circumferential wall portion 62 is configured in an annular shape along the circumferential direction, and in the cross section shown, extends along the axial direction so as to connect the inner end of the end wall portion 60 in the radial direction to the stator core 30. The gap g1 may be formed around the entire circumferential direction, and in the cross section shown, the gap g1 extends in the axial direction, and the size of the radial gap g1 is constant in the axial direction.

[0029] An inner circumferential surface 62a of the inner circumferential wall portion 62 and an inner end face 30a of the stator core 30 in the radial direction (an end face located between the slits that accommodate the stator coils 32 in the inner circumferential surface of the stator core 30) are flush with each other, and a distance r1 between the inner circumferential surface 62a of the inner circumferential wall portion 62 and the rotation axis CA is equal to a distance r2 between the end face 30a of the stator core 30 and the rotation axis CA. Furthermore, a distance r3 between the outer circumferential surface 44a of the bearing base 44 and the rotation axis CA is equal to a distance r4 between the outer circumferential surface 10a of the rotor 10 (the outer circumferential surface of the holding member 13 in the illustrated example) and the rotation axis CA.

[0030] A radial gap g2 is provided between the inner circumferential wall portion 62 and the rotor 10. The gap g2 may be formed around the entire circumferential direction, or in the cross section shown, the gap g2 extends in the axial direction, and the size of the radial gap g2 is constant in the axial direction. Furthermore, the size of the radial gap g1 and the size of the radial gap g2 may be equal.

[0031] 1 and 2 , the cooling air supplied to the journal bearing 22 through the cooling air supply holes 51 passes through the journal bearing 22 in the axial direction, and then is supplied to the gaps g1 and g2 through the axial gap g3 between the bearing stand 44 and the retaining member 13 of the rotor 10. The cooling air supplied to the gap g2 through the axial gap g3 between the bearing stand 44 and the retaining member 13 of the rotor 10 is supplied to the gap g0 (gaps g01 and g02) and the journal bearing 24 through the radial gap g4 between the stator core 30 and the rotor 10.

[0032] In the electric compressor 2 shown in FIGS. 1 and 2 , the end wall portion 60 (part of the resin mold 34) located between the annular wall portion 48 of the motor housing 36 and the coil ends 38 includes a surface 60a that contacts the annular wall portion 48. This allows the cold heat of the coolant flowing through the cooling flow passage 47 to be transferred from the cylindrical portion 46 of the motor housing 36 to the coil ends 38 via the annular wall portion 48 and the end wall portion 60, thereby cooling the coil ends 38. In addition, a gap g1 is provided between the inner circumferential wall portion 62 (part of the resin mold 34) located between the coil ends 38 and the bearing pedestal 44 and the bearing pedestal 44. This reduces the path of heat transfer from the coil ends 38 to the journal bearing 22, thereby suppressing heat inflow from the coil ends 38 to the bearing pedestal 44 and the journal bearing 22, compared to when the inner circumferential wall portion 62 and the bearing pedestal 44 are in contact with each other. This prevents the journal bearing 22 from becoming too hot.

[0033] Figure 3 is a schematic cross-sectional view showing a modified example of the electric compressor 2 shown in Figure 2. Figure 4 is a schematic cross-sectional view showing an example of an A-A cross section (a cross section perpendicular to the axial direction) of the electric compressor 2 shown in Figure 3. The electric compressor 2 shown in Figures 3 and 4 differs from the electric compressor 2 shown in Figure 2 in that a cavity 64 is formed in the annular wall portion 48, but other configurations are the same as the electric compressor 2 described using Figures 1 and 2.

[0034] 3 and 4 , if the position of the outer end 60 e of the end wall portion 60 in the radial direction is defined as a first position P1, a cavity 64 extending in the circumferential direction is formed in the annular wall portion 48 radially inward of the first position P1. In the embodiment shown in FIG. 4 , the cavity 64 is formed at a position circumferentially offset from the cooling air supply hole 51 and is formed in a substantially C-shape along an arc centered on the rotation axis CA in a cross section perpendicular to the axial direction. As shown in FIG. 4 , the cavity 64 may be formed over an angular range of, for example, 180° or more in the circumferential direction.

[0035] 3 and 4 , a cavity 64 extending in the circumferential direction is formed on the heat transfer path from the coil end 38 to the journal bearing 22, which effectively suppresses heat flow from the coil end 38 to the journal bearing 22 and improves the effect of suppressing an increase in temperature of the journal bearing 22. Furthermore, because the cavity 64 is formed at a position offset in the circumferential direction from the cooling air supply hole 51, the cavity 64 can achieve the effect of suppressing an increase in temperature of the journal bearing 22 without affecting the flow of cooling air from the cooling air supply hole 51 to the journal bearing 22.

[0036] In some embodiments, as shown in Fig. 5, for example, a cavity 64 formed in the annular wall portion 48 may be connected to the cooling air supply holes 51. In the exemplary embodiment shown in Fig. 5, the cavity 64 is formed annularly along the circumferential direction.

[0037] 5 , a cavity 64 extending in the circumferential direction is formed on the heat transfer path from the coil ends 38 to the journal bearings 22, which effectively suppresses heat flow from the coil ends 38 to the journal bearings 22 and improves the effect of suppressing an increase in temperature of the journal bearings 22. Furthermore, by supplying a portion of the cooling air flowing from the cooling air supply holes 51 to the cavity 64 to the journal bearings 22, an increase in temperature around the cavity 64 can be suppressed, and an increase in temperature of the journal bearings 22 can be effectively suppressed.

[0038] Figure 6 is a schematic cross-sectional view showing a modified example of the electric compressor 2 shown in Figure 2. The electric compressor 2 shown in Figure 5 differs from the electric compressor 2 shown in Figure 2 in that a cavity 64 is formed in the annular wall portion 48, but the other configuration is the same as the electric compressor 2 described using Figures 1 and 2. Furthermore, the electric compressor 2 shown in Figure 6 differs from the electric compressor 2 shown in Figure 3 in the position and range of the cavity 64, but the other configuration is the same as the electric compressor 2 shown in Figure 3.

[0039] 6 , the cavity 64 may be formed in the annular wall portion 48 at a position between the cooling air supply hole 51 and the end wall portion 60. In this case, the cavity 64 may be formed in an annular shape along the circumferential direction, or may be formed in a substantially C-shape along an arc centered on the rotation axis CA in a cross section perpendicular to the axial direction.

[0040] 6 , a cavity 64 extending in the circumferential direction is formed on the heat transfer path from the coil ends 38 to the journal bearings 22, which effectively suppresses heat flow from the coil ends 38 to the journal bearings 22 and enhances the effect of suppressing an increase in temperature of the journal bearings 22. Furthermore, because the cavity 64 is formed in a position in the annular wall portion 48 between the cooling air supply holes 51 and the end wall portion 60, the cavity 64 can suppress an increase in temperature of the journal bearings 22 without affecting the flow of cooling air from the cooling air supply holes 51 to the journal bearings 22.

[0041] Figure 7 is a schematic cross-sectional view showing a modified example of the electric compressor 2 shown in Figure 2. Figure 8 is a schematic cross-sectional view partially showing a cross section perpendicular to the radial direction at the position of a bypass hole 72 in the electric compressor 2 shown in Figure 7. The electric compressor 2 shown in Figure 7 differs from the electric compressor 2 shown in Figure 2 in that a cavity 70 is formed between the coil end 38 and the annular wall portion 48, that a bypass hole 72 is formed in the annular wall portion 48, and that a cover member 74 is provided, but the other configurations are the same as the electric compressor 2 described using Figures 1 and 2.

[0042] 7 , a cavity 70 is formed between the coil end 38 and the annular wall 48, extending radially outward from a gap g1 between the inner circumferential wall 62 of the resin mold 34 and the bearing pedestal 44, and a bypass hole 72 is formed in the annular wall 48, connecting the cooling air supply holes 51 with the cavity 70. The cover member 74 is configured to separate the cavity 70 from the end wall 60, and to separate the cavity 70 from the inner circumferential wall 62.

[0043] In the cross section shown in Figure 7, the cover member 74 includes a first partition portion 74a that extends from the coil end 38 to the annular wall portion 48 in a direction intersecting the radial direction and separates the cavity portion 70 from the end wall portion 60, a curved portion 74b that curves along the coil end 38, and a second partition portion 74c that extends in a direction intersecting the axial direction and separates the cavity portion 70 from the inner wall portion 62.

[0044] 8 , the cover member 74 includes a pair of legs 74d1, 74d2 and a partition 74e that protrudes from the legs 74d1, 74d2 toward the coil end 38 in the axial direction. The bypass hole 72 is located between the legs 74d1, 74d2 in the circumferential direction. Each of the legs 74d1, 74d2 is formed in a plate shape and is sandwiched between the end wall portion 60 and the annular wall portion 48, extending in the circumferential direction.

[0045] In the exemplary cross section shown in Figure 8, the partition portion 74e is formed in a curved plate shape, and the axial distance h between the partition portion 74e and the bypass hole 72 (the axial height of the partition portion 74e from the annular wall portion 48) increases as one approaches the center of the partition portion 74e.

[0046] 7 and 8 , cooling air flowing through cooling air supply holes 51 for supplying cooling air to journal bearings 22 is guided through bypass holes 72 and cavity 70 to gap g1 between inner circumferential wall portion 62 and bearing base 44, and cooling air can be supplied through gap g1 to gap g4 between rotor 10 and stator 12 of motor 4, etc. This makes it easier to ensure the flow rate of cooling air flowing through gap g4 between rotor 10 and stator 12 of motor 4, and also makes it possible to obtain the effect described using FIG. 2 etc. (effect of suppressing temperature rise in journal bearings 22).

[0047] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0048] For example, in the above-described embodiment, a two-stage electric compressor including a motor 4, a high-pressure compressor 6 driven by the motor 4, and a low-pressure compressor 8 driven by the motor 4 is exemplified, but the present disclosure is not limited to two-stage electric compressors and may also be a single-stage electric compressor including a motor 4 and a compressor 6 driven by the motor 4.

[0049] The contents described in each of the above embodiments can be understood, for example, as follows.

[0050] [1] An electric compressor (e.g., the above-described electric compressor 2) according to at least one embodiment of the present disclosure is an electric compressor including: a rotating shaft (e.g., the above-described rotating shaft 5); a first compressor impeller (e.g., the above-described compressor impeller 14) provided on one end side of the rotating shaft; a motor (e.g., the above-described motor 4) including a rotor (e.g., the above-described rotor 10) provided on the rotating shaft on the back side of the first compressor impeller and a stator (e.g., the above-described stator 12) arranged around the rotor; and a first journal bearing (e.g., the above-described journal bearing 22) that rotatably supports the rotating shaft between the rotor and the first compressor impeller, wherein the stator includes a stator core (e.g., the above-described stator core 30), a stator coil (e.g., the above-described stator coil 32), a resin mold (e.g., the above-described resin mold 34), and a motor housing (e.g., the above-described motor housing 36), the stator coil includes a first coil end (for example, the above-mentioned coil end 38) located between the stator core and the first compressor impeller, the resin mold is configured to cover at least a portion of the first coil end, the motor housing includes: a bearing pedestal portion (for example, the above-mentioned bearing pedestal portion 44) that supports the first journal bearing, a cylindrical portion (for example, the above-mentioned cylindrical portion 46) that surrounds the stator core, the first coil end, and the resin mold, the cylindrical portion having a cooling flow path (for example, the above-mentioned cooling flow path 47) through which a coolant flows, and an annular wall portion (for example, the above-mentioned annular wall portion 48) that connects the end of the cylindrical portion on the first compressor impeller side to the bearing pedestal and is provided to separate the first compressor impeller and the first coil end, and the resin mold includes: an end wall portion (for example, the above-mentioned end wall portion 60) located between the first coil end and the annular wall portion, an inner circumferential wall portion (e.g., the above-mentioned inner circumferential wall portion 62) located between the first coil end and the bearing pedestal, and the end wall portion includes a surface (e.g., the above-mentioned surface 60a) that contacts the annular wall portion and a surface (e.g., the above-mentioned surface 60b) that contacts the first coil end,A gap (for example, the above-mentioned gap g1) is provided between the inner peripheral wall portion and the bearing pedestal portion.

[0051] According to the electric compressor described in [1] above, the end wall portion (part of the resin mold) located between the annular wall portion of the motor housing and the first coil end includes a surface that contacts the annular wall portion, so that the cold heat of the cooling medium flowing through the cooling passage is transferred from the cylindrical portion of the motor housing through the annular wall portion and the end wall portion to the first coil end, thereby cooling the first coil end. Furthermore, because a gap is provided between the inner circumferential wall portion (part of the resin mold) located between the first coil end and the bearing pedestal and the bearing pedestal, the path of heat transfer from the first coil end to the first journal bearing is reduced compared to when the inner circumferential wall portion and the bearing pedestal are in contact, and heat inflow from the first coil end to the bearing pedestal and the first journal bearing is suppressed. This prevents the journal bearing from becoming too hot.

[0052] [2] In some embodiments, in the electric compressor described in [1] above, if the position of the outer end of the end wall portion in the radial direction of the electric compressor is defined as a first position (e.g., the above-mentioned first position P1), a cavity portion (e.g., the above-mentioned cavity portion 64) extending circumferentially of the electric compressor is formed in the annular wall portion, radially inward of the first position.

[0053] According to the electric compressor described in [2] above, a cavity extending circumferentially is formed on the heat transfer path from the first coil end to the first journal bearing, which effectively suppresses heat flow from the first coil end to the first journal bearing, thereby enhancing the effect of suppressing the journal bearing from becoming too hot.

[0054] [3] In some embodiments, in the electric compressor described in [2] above, the annular wall portion is formed with a cooling air supply hole (e.g., the above-mentioned cooling air supply hole 51) for supplying cooling air to the first journal bearing, and the cavity portion is formed at a position shifted in the circumferential direction from the cooling air supply hole.

[0055] According to the electric compressor described in [3] above, the effect of the cavity described in [2] above (the effect of suppressing the temperature rise of the journal bearing) can be obtained without affecting the flow of cooling air from the cooling air supply hole to the first journal bearing.

[0056] [4] In some embodiments, in the electric compressor described in [2] above, a cooling air supply hole (e.g., the above-mentioned cooling air supply hole 51) for supplying cooling air to the first journal bearing is formed in the annular wall portion, and the cavity portion is connected to the cooling air supply hole.

[0057] According to the electric compressor described in [4] above, by supplying a portion of the cooling air flowing from the cooling air supply hole to the journal bearing to the cavity, it is possible to suppress the temperature rise around the cavity, and it is possible to effectively suppress the temperature rise of the journal bearing.

[0058] [5] In some embodiments, in the electric compressor described in [2] above, the annular wall portion is formed with a cooling air supply hole (e.g., the above-mentioned cooling air supply hole 51) for supplying cooling air to the first journal bearing, and the cavity portion is formed at a position in the annular wall portion between the cooling air supply hole and the end wall portion.

[0059] According to the electric compressor described in [5] above, the effect of the cavity described in [2] above (the effect of suppressing the temperature rise of the journal bearing) can be obtained without affecting the flow of cooling air from the cooling air supply hole to the first journal bearing.

[0060] [6] In some embodiments, in the electric compressor described in any of [1] to [5] above, the annular wall portion is formed with a cooling air supply hole (e.g., the above-mentioned cooling air supply hole 51) for supplying cooling air to the first journal bearing, a cavity portion (e.g., the above-mentioned cavity portion 70) is formed between the first coil end and the annular wall portion and extends from the gap to the outside in the radial direction of the electric compressor, and the annular wall portion is formed with a bypass hole (e.g., the above-mentioned bypass hole 72) that connects the cooling air supply hole and the cavity portion.

[0061] According to the electric compressor described in [6] above, the cooling air flowing through the cooling air supply hole for supplying cooling air to the first journal bearing is guided via the bypass hole and the cavity to the gap between the inner circumferential wall and the bearing base, and cooling air can be supplied via this gap to the gap between the rotor and stator of the motor, etc. This makes it easier to ensure the flow rate of cooling air flowing through the gap between the rotor and stator of the motor, and also achieves the effect of suppressing the temperature rise in the journal bearing described above.

[0062] [7] In some embodiments, the electric compressor according to the above item [6] further includes a cover member (for example, the above-described cover member 74) that separates the cavity portion from the end wall portion.

[0063] According to the electric compressor described in [7] above, the cover member can prevent the resin from flowing into the cavity from the end wall portion side during molding of the molding resin.

[0064] [8] In some embodiments, the electric compressor according to any one of [1] to [7] above further comprises: a second compressor impeller (for example, the above-mentioned compressor impeller 18) provided on the other end side of the rotating shaft; and a second journal bearing (for example, the above-mentioned journal bearing 24) that rotatably supports the rotating shaft between the rotor and the second compressor impeller; the stator includes a bearing housing (for example, the above-mentioned bearing housing 52) that accommodates the second journal bearing and is configured as a separate part from the motor housing; the stator coil includes a second coil end (for example, the above-mentioned coil end 40) located between the stator core and the second compressor impeller; and a gap (for example, the above-mentioned gap g0) is formed between the second coil end and the bearing housing over a range from a position outside the second coil end to a position inside the second coil end in the radial direction of the electric compressor.

[0065] According to the electric compressor described in [8] above, by assembling the bearing housing to the motor housing after molding the molded resin, it is possible to easily manufacture any of the electric compressors described in [1] to [7] above.

[0066] 2 Electric compressor 4 Motor 5 Rotating shaft 6 High-pressure compressor 8 Low-pressure compressor 10 Rotor 10a, 44a Outer circumferential surface 11 Permanent magnet 12 Stator 13 Holding member 14, 18 Compressor impeller 14b, 18b Back surface 16, 20 Compressor housing 22, 24 Journal bearing 26 Thrust bearing 30 Stator core 30a End surface 32 Stator coil 34 Resin mold 36 Motor housing 38, 40 Coil end 44, 53 Bearing base portion 46 Cylindrical portion 47 Cooling flow passage 48, 54 Annular wall portion 49, 55 Inner end portion 50 End portion 51 Cooling air supply hole 52 Bearing housing 56 Outer end portion 60 End wall portion 60a, 60b Surface 60e Outer end 62 Inner peripheral wall portion 62a Inner peripheral surface 63 Outer peripheral wall portion 64, 70 Hollow portion 72 Bypass hole 74 Cover member 74a First partition portion 74b Curved portion 74c Second partition portion 74d1, 74d2 Leg portion 74e Partition portion CA Rotation axis P1 First position g0, g1, g01, g02, g2, g3, g4 Gap h Axial distance r1, r2, r3, r4 Distance

Claims

1. An electric compressor comprising: a rotating shaft; a first compressor impeller provided on one end of the rotating shaft; a motor including a rotor provided on the rotating shaft behind the first compressor impeller and a stator arranged around the rotor; and a first journal bearing rotatably supporting the rotating shaft between the rotor and the first compressor impeller, wherein the stator includes a stator core, a stator coil, a resin mold, and a motor housing, wherein the stator coil includes a first coil end located between the stator core and the first compressor impeller, and the resin mold is configured to cover at least a part of the first coil end, and the motor housing includes: a bearing base portion supporting the first journal bearing; and a cylindrical portion surrounding the stator core, the first coil end, and the resin mold, the cylindrical portion having a cooling flow path formed therein through which a cooling medium flows. an annular wall portion connecting an end of the cylindrical portion on the first compressor impeller side and the bearing base portion, and separating the first compressor impeller and the first coil end; wherein the resin mold includes: an end wall portion located between the first coil end and the annular wall portion; and an inner circumferential wall portion located between the first coil end and the bearing base portion, wherein the end wall portion includes a surface that contacts the annular wall portion and a surface that contacts the first coil end, and a gap is provided between the inner circumferential wall portion and the bearing base portion.

2. The electric compressor according to claim 1, wherein, when the position of the outer end of the end wall portion in the radial direction of the electric compressor is defined as a first position, a hollow portion extending in the circumferential direction of the electric compressor is formed in the annular wall portion, radially inward of the first position.

3. An electric compressor as set forth in claim 2, wherein a cooling air supply hole for supplying cooling air to the first journal bearing is formed in the annular wall portion, and the cavity portion is formed at a position offset in the circumferential direction from the cooling air supply hole.

4. The electric compressor according to claim 2, wherein the annular wall portion is formed with a cooling air supply hole for supplying cooling air to the first journal bearing, and the cavity portion is connected to the cooling air supply hole.

5. An electric compressor as set forth in claim 2, wherein the annular wall portion is formed with a cooling air supply hole for supplying cooling air to the first journal bearing, and the cavity portion is formed in the annular wall portion at a position between the cooling air supply hole and the end wall portion.

6. An electric compressor as described in claim 1, wherein the annular wall portion is formed with a cooling air supply hole for supplying cooling air to the first journal bearing, a cavity portion is formed between the first coil end and the annular wall portion and extends from the gap to the outside in the radial direction of the electric compressor, and the annular wall portion is formed with a bypass hole that connects the cooling air supply hole and the cavity portion.

7. The electric compressor according to claim 6, further comprising a cover member separating the cavity portion from the end wall portion.

8. The electric compressor according to claim 1, further comprising: a second compressor impeller provided on the other end side of the rotating shaft; and a second journal bearing rotatably supporting the rotating shaft between the rotor and the second compressor impeller, wherein the stator includes a bearing housing that houses the second journal bearing and is configured as a separate part from the motor housing, the stator coil includes a second coil end located between the stator core and the second compressor impeller, and a gap is formed between the second coil end and the bearing housing over a range from a position outside the second coil end to a position inside the second coil end in the radial direction of the electric compressor.

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