Electric compressor device

Abstract

This electric compressor device is provided with a motor housing that accommodates a motor. A cooling flow path through which a cooling liquid flows in the circumferential direction is formed inside the motor housing at a position closer to the outer side in the radial direction than a stator of the motor, and the axial length of the cooling flow path is greater than the radial length of the cooling flow path by at least two times when viewed in the circumferential direction. At least one reinforcing rib is provided to the motor housing, the reinforcing rib protruding radially outward from a radially inner wall surface of the motor housing defining the cooling flow path and extending in a circumferential direction.

Description

Technical Field

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

[0002] Conventionally, electric compressor devices are known that include a motor housing having a coolant flow path formed therein. The coolant flowing through the flow path cools the stator and other components of the motor that constitutes the electric compressor device. For example, the motor housing disclosed in Patent Document 1 has a coolant channel formed therein that extends circumferentially.

[0003] Previous technical literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-209845 Summary of the Invention

[0006] Technical issues to be solved by the invention

[0007] However, the flow path cross section of the coolant passage of the motor housing is substantially square, so the flow rate of the coolant tends to be low. Therefore, the electric compressor device may not be able to fully exert its cooling performance.

[0008] An object of the present invention is to provide an electric compressor device with improved cooling performance.

[0009] Means for solving technical problems

[0010] An electric compressor device according to at least one embodiment of the present invention includes:

[0011] a rotating shaft; a compressor impeller disposed on the rotating shaft;

[0012] a motor for driving the rotating shaft; and

[0013] a motor housing accommodating the motor,

[0014] The motor comprises:

[0015] a rotor fixed to the rotating shaft; and

[0016] a stator disposed around the rotor and supported by the motor housing;

[0017] A cooling flow path for cooling liquid to flow in a circumferential direction is formed inside the motor housing at a position radially outward of the stator.

[0018] When viewed along the circumferential direction, the axial length of the cooling flow path is more than twice the radial length of the cooling flow path.

[0019] The electric compressor device is provided with at least one reinforcing rib that protrudes from a radially inner wall surface of a wall surface of the motor housing defining the cooling flow path toward the radially outer side and extends along the circumferential direction.

[0020] Effects of the Invention

[0021] According to the present invention, it is possible to provide an electric compressor device having improved cooling performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic cross-sectional view of an electric compressor device according to one embodiment.

[0023] Figure 2 yes Figure 1 A partial enlarged view of .

[0024] Figure 3 This is a schematic graph showing the relationship between the coolant flow rate and the heat transfer coefficient determined by simulation.

[0025] Figure 4A 1 is a schematic cross-sectional view of a first reinforcing rib 71 constituting the reinforcing rib 70 (first example).

[0026] Figure 4B It is a schematic cross-sectional view of the first reinforcing rib 71 constituting the reinforcing rib 70 (second example).

[0027] Figure 5 This is a schematic diagram of a motor housing according to one embodiment when viewed in the axial direction.

[0028] Figure 6A It is a schematic cross-sectional view showing a motor case according to the first embodiment.

[0029] Figure 6B It is a schematic cross-sectional view showing a motor case according to a second embodiment.

[0030] Figure 6C It is a schematic cross-sectional view showing a motor case according to a third embodiment.

[0031] Figure 6D It is a schematic cross-sectional view showing a motor case according to a fourth embodiment. DETAILED DESCRIPTION

[0032] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention and are merely illustrative examples.

[0033] For example, expressions such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" indicating relative or absolute configurations not only indicate such configurations in a strict sense, but also indicate a state of relative displacement at an angle or distance with a tolerance or a degree to which the same function can be achieved.

[0034] For example, expressions such as “same,” “equal,” and “homogeneous” that indicate that things are in the same state not only indicate a state that is strictly the same, but also indicate a state that has tolerances or differences to the extent that the same function can be achieved.

[0035] For example, expressions indicating shapes such as a quadrilateral and a cylinder not only indicate shapes such as a quadrilateral and a cylinder in a strict geometric sense, but also indicate shapes including concave and convex portions, chamfered portions, and the like as long as the same effect can be obtained.

[0036] On the other hand, the expression “having”, “including” or “having” a constituent element is not an exclusive expression that excludes the existence of other constituent elements.

[0037] In addition, the same symbols are attached to the same structures, and the description thereof may be omitted.

[0038] <Overall Structure of Electric Compressor Device 1>

[0039] Figure 1 1 is a schematic cross-sectional view of an electric compressor device 1 according to an embodiment of the present invention. The electric compressor device 1 of this example is a two-stage compression electric compressor having a rotating shaft 2. The two-stage compression electric compressor is configured to deliver compressed air to a fuel cell mounted on a vehicle, for example.

[0040] In the following description, the direction in which the axis of the rotating shaft 2 extends is sometimes referred to as the "axial direction," and the circumferential and radial directions relative to the axis are sometimes referred to simply as the "circumferential direction" and the "radial direction." The radially outer side is the direction away from the axis of the rotating shaft 2, and the radially inner side is the direction closer to the axis.

[0041] The electric compressor device 1 includes a housing 20 that accommodates a rotating shaft 2. The housing 20 includes a low-pressure side housing 23 that accommodates the low-pressure stage impeller 13 provided at one end of the rotating shaft 2, a high-pressure side housing 24 that accommodates the high-pressure stage impeller 14 provided at the other end of the rotating shaft 2, and a motor housing 25 that accommodates the motor 5 for driving the rotating shaft 2. In this embodiment, the low-pressure side housing 23 and the high-pressure side housing 24 are arranged so as to sandwich the motor housing 25 in the axial direction.

[0042] The low-pressure side casing 23 is formed with an intake port 236, a diffuser 237, a vortex portion 238, and an exhaust port (not shown). Similarly, the high-pressure side casing 24 is formed with an intake port 246, a diffuser 247, a vortex portion 248, and an exhaust port (not shown). The exhaust port of the low-pressure side casing 23 is connected to the intake port 246 of the high-pressure side casing 24 via a connecting pipe (not shown). The low-pressure side casing 23 and the low-pressure stage impeller 13 function as the low-pressure stage compressor 3, while the high-pressure side casing 24 and the high-pressure stage impeller 14 function as the high-pressure stage compressor 4. The low-pressure stage impeller 13 and the high-pressure stage impeller 14 are each an example of a compressor impeller.

[0043] The motor 5 includes a rotor 51 fixed to the rotating shaft 2 between the high-pressure stage impeller 14 and the low-pressure stage impeller 13, and a stator 52 disposed around the rotor 51. The rotor 51 includes a rotor core supported by the rotating shaft 2 and a plurality of permanent magnets supported by the rotor core. Furthermore, the stator 52 includes a stator core 53 extending in the circumferential direction and a stator coil 54 disposed on the stator core 53. The stator core 53 is supported by the motor housing 25.

[0044] The operation of the electric compressor device 1 is summarized as follows. Current flowing through the stator coil 54 creates a rotating magnetic field, causing the rotor 51 to rotate along with the rotating shaft 2. This also causes the low-pressure stage impeller 13 and the high-pressure stage impeller 14 to rotate. In the low-pressure stage compressor 3, air is drawn in through the intake port 236 (arrow A1). The drawn-in air is accelerated by the centrifugal force of the low-pressure stage impeller 13. The accelerated air passes through the diffuser 237, where it is decelerated and pressurized. It then flows through the vortex 238 and is discharged from the outlet (arrow A2). The low-pressure air compressed by the low-pressure stage compressor 3 is delivered to the intake port 246 via a connecting pipe (arrow A3). In the high-pressure stage compressor 4, the low-pressure air that has passed through the intake port 246 is accelerated by the centrifugal force of the high-pressure stage impeller 14. The accelerated air passes through the diffuser 247, where it is decelerated and pressurized. It then flows through the vortex 248 and is discharged from the outlet (arrow A4).

[0045] While the electric compressor device 1 is operating as described above, current flows through the stator coil 54, causing the temperature of the stator 52 to rise. Furthermore, the temperature of the stator 52 also rises due to eddy currents generated in at least one of the stator core 53 or the stator coil 54. Therefore, in the motor housing 25 of this embodiment, a cooling flow path 40 is formed radially outward of the stator 52 to allow a coolant (not shown) to flow circumferentially.

[0046] <Overview of Cooling Flow Path 40>

[0047] refer to Figure 1 、 Figure 2 , illustrating a cooling flow path 40 according to one embodiment of the present invention. Figure 2yes Figure 1 A partially enlarged view. The cooling flow path 40 of this example includes a first cooling flow path 41, a second cooling flow path 42, and a first return cooling flow path 46. The first cooling flow path 41 and the second cooling flow path 42 are arranged to extend along the circumferential direction and are arranged in the axial direction. The first return cooling flow path 46 is connected to the first cooling flow path 41 and the second cooling flow path 42. The coolant flows into the first cooling flow path 41 (arrow B1) after passing through the inlet 251 formed in the motor housing 25. Then, the coolant flows through the first cooling flow path 41, the first return cooling flow path 46, and the second cooling flow path 42 in sequence and is discharged from the outlet 252 formed in the motor housing 25 (arrow B2).

[0048] The cross-sectional shape of the cooling channel 40 will be described. Regarding the cooling channel 40 of this example, when viewed along the circumferential direction, the axial length of the cooling channel 40 is at least twice, and more specifically, at least four times, greater than the radial length of the cooling channel 40. Here, when the ratio of the axial length to the radial length is defined as the aspect ratio, an axial length that is N times greater than the radial length is synonymous with an aspect ratio of 1 / N or less. That is, the aspect ratio of the cooling channel 40 of this example is 0.5 or less, more specifically, 0.25 or less.

[0049] The aspect ratio is 0.25 or less as long as it is established in at least the flow path extending in the circumferential direction in the cooling flow path 40. Figure 1 、 Figure 2 In the example of , the aspect ratio of the first cooling channel 41 and the second cooling channel 42 may be 0.25 or less. Figure 2 In the figure, the axial and radial lengths of the first cooling channel 41 correspond to dimensions La and Ld, respectively. Furthermore, the axial and radial lengths of the second cooling channel 42 correspond to dimensions Ma and Md, respectively. When the aspect ratio of the cooling channel 40 is 0.25 or less, dimension La is at least four times dimension Ld, and dimension Ma is at least four times dimension Md.

[0050] Furthermore, in this example, the cross-sectional shape of the first return cooling flow path 46 is also the same. More specifically, when viewed along the axial direction, the circumferential length of the first return cooling flow path 46 is at least twice, and more specifically, at least four times, greater than the radial length of the first return cooling flow path 46 (not shown).

[0051] like Figure 2As shown, the motor housing 25 includes at least one reinforcing rib 70 extending circumferentially in the cooling flow path 40. More specifically, the motor housing 25 includes a wall surface 60 that defines the cooling flow path 40, and the wall surface 60 has a radially inner wall surface 62 and a radially outer wall surface 64. Moreover, the reinforcing rib 70 protrudes radially outward from the radially inner wall surface 62. The reinforcing rib 70 is a convex surface integrally formed with the radially inner wall surface 62. By providing the reinforcing rib 70 on the radially inner wall surface 62 rather than on the radially outer wall surface 64, the stator core 53, which is prone to temperature rise, can be effectively cooled. In addition, the reinforcing rib 70 can also be provided on the radially outer wall surface 64.

[0052] While not an essential structural element of the present invention, the present embodiment includes a plurality of reinforcing ribs 70 arranged at intervals in the axial direction. More specifically, the reinforcing ribs 70 include a plurality of first reinforcing ribs 71 arranged at intervals in the axial direction in the first cooling flow path 41, and a plurality of second reinforcing ribs 72 arranged at intervals in the axial direction in the second cooling flow path 42. Each first reinforcing rib 71 and each second reinforcing rib 72 extends circumferentially.

[0053] The number of reinforcing ribs 70 provided in the cooling flow path 40 extending in the circumferential direction may be two or more, or three or more. In the illustrated example, the number of first reinforcing ribs 71 provided in the first cooling flow path 41 is three, and the number of second reinforcing ribs 72 provided in the second cooling flow path 42 is also three. The details will be described later, but the first return cooling flow path 46 may or may not include reinforcing ribs 70 (see FIG. 1 ). Figure 6A 、 Figure 6B ).

[0054] According to the above structure, the aspect ratio of the cooling flow path 40 is less than 1, so the flow rate of the coolant in the cooling flow path 40 is increased, and by providing at least one reinforcing rib 70, the cross-sectional area of ​​the flow path is appropriately narrowed, so the flow rate of the coolant is further increased. As a result, the heat transfer coefficient between the cooling flow path 40 and the coolant is increased. In addition, by providing the reinforcing rib 70, the heat transfer area is also increased. Therefore, an electric compressor device 1 with improved cooling performance is realized. In addition, by adopting a structure in which multiple reinforcing ribs 70 are arranged at intervals in the axial direction, the heat transfer area is further increased, and the cooling performance of the electric compressor device 1 is further improved.

[0055] Furthermore, in the present embodiment, since the aspect ratio is 1 or less, the flow velocity of the coolant increases, and thus the flow rate of the coolant can also be reduced. Figure 3 This is a schematic diagram showing the relationship between the coolant flow rate and the heat transfer coefficient determined by analysis. Figure 3In the graph, the solid line represents the cooling flow path 40 according to the embodiment, which has an aspect ratio of 0.25, and the dashed line represents the cooling flow path according to the comparative example (not shown), which has an aspect ratio of 1. As described above, the heat transfer coefficient of the cooling flow path 40 is higher than that of the cooling flow path according to the comparative example. As a result, the cooling flow path 40 according to the embodiment can achieve the required heat transfer coefficient (E shown in the graph) for the electric compressor device 1, while the cooling flow path 40 according to the comparative example can achieve a smaller coolant flow rate. Therefore, in the electric compressor device 1, the coolant flow rate flowing through the cooling flow path 40 can also be reduced.

[0056] In another example, the cooling channel 40 may not include the second cooling channel 42 and the first return cooling channel 46, but may consist solely of the first cooling channel 41. Furthermore, only one first reinforcing rib 71 may be provided in the first cooling channel 41. These embodiments also achieve the aforementioned technical advantages.

[0057] <Reinforcing Ribs 70 According to Several Embodiments>

[0058] Figure 4A 、 Figure 4B The first reinforcing rib 71 constituting the reinforcing rib 70 is shown. Figure 4A This is a schematic cross-sectional view of the first reinforcing rib 71A (71). Figure 4B This is a schematic cross-sectional view of the first reinforcing rib 71B (71). At least one of the structures related to the first reinforcing ribs 71A and 71B described below can also be applied to the second reinforcing rib 72 (see Figure 2 ).

[0059] like Figure 4A 、 Figure 4B As shown, the maximum radial length (dimension h) of the first reinforcing ribs 71A, 71B (71) is 4 / 5 or less, and more preferably 2 / 3 or less, of the maximum radial length (dimension H) of the first cooling channel 41. Any value can be adopted as the minimum value of dimension h, but for example, dimension h can be 1 / 5 or more, more specifically 2 / 5 or more, of dimension H.

[0060] According to the above structure, a reduction in the flow rate of the coolant due to an excessive narrowness between the radially outer wall surface 64 of the motor housing 25 and the first reinforcing ribs 71A, 71B can be avoided, and an increase in the flow rate of the coolant locally generated in the first cooling flow path 41 and the resulting increase in pressure loss can be avoided.

[0061] Furthermore, the aforementioned relationship between dimension h and dimension H may also apply between the second reinforcing rib 72 and the second cooling flow path 42. More specifically, the relationship between the radial lengths of the first reinforcing rib 71 and the first cooling flow path 41, and the relationship between the radial lengths of the second reinforcing rib 72 and the second cooling flow path 42 may be identical. As a more detailed example, when viewed in the circumferential direction, the first reinforcing rib 71 and the second reinforcing rib 72 may have the same shape, and when viewed in the circumferential direction, the first cooling flow path 41 and the second cooling flow path 42 may have the same shape.

[0062] Figure 4A 、 Figure 4B The plurality of first reinforcing ribs 71A, 71B (71) shown have radially outer ends, namely, tops 175A, 175B (175). The top 175 is a flat surface in the first reinforcing rib 71 that faces radially outward and is a flat surface that extends orthogonally to the radial direction. The axial length of the tops 175A, 175B corresponds to the dimension Wt. The dimension of the intervals (the shortest distance in the axial direction) between two adjacent axially arranged first reinforcing ribs 71A, 71B (71) corresponds to Ws. In this example, the dimension Ws is greater than the dimension Wt. In other words, the plurality of first reinforcing ribs 71 are arranged in the axial direction at intervals that are longer than the axial length of the top 175. In addition, the dimension Wt can be shorter than the dimension h or longer than the dimension h.

[0063] This structure avoids excessive increases in the coolant flow rate and the resulting increase in pressure loss caused by an excessively short interval between two adjacent first reinforcing ribs 71. Furthermore, the aforementioned relationship between dimensions Ws and Wt also applies to the second reinforcing ribs 72. Specifically, the plurality of second reinforcing ribs 72 can be arranged axially at intervals greater than the axial length of the tops of the second reinforcing ribs 72.

[0064] like Figure 4A 、 Figure 4B As shown, the wall surface 60 of the motor housing 25 has a pair of axially oriented side surfaces 65. In both figures, the shortest distance between any of the plurality of first reinforcing ribs 71A and 71B (71) closest to the side surface 65 and the side surface 65 is represented by dimension Wf. Dimension Wf is longer than dimension Wt described above. In other words, the shortest distance between the first reinforcing rib 71 closest to the side surface 65 and the side surface 65 is longer than the axial length of the top portion 175.

[0065] This configuration avoids an excessive increase in the coolant flow rate and the resulting increase in pressure loss caused by an excessively short minimum distance between the first rib 71 and the side surface 65. Furthermore, the aforementioned relationship between dimensions Wf and Wt also applies to the second rib 72. Specifically, the shortest distance between the side surface (not shown) of the wall surface 60 defining the second cooling channel 42 and the second rib 72 closest to that side surface can be longer than the axial length of the top of the second rib 72.

[0066] like Figure 4A 、 Figure 4B As shown, when viewed along the circumferential direction, the plurality of first reinforcing ribs 71A (71) are each trapezoidal in shape, and the plurality of first reinforcing ribs 71B (71) are each rectangular in shape. In this example, the first reinforcing ribs 71A and 71B are connected to the radially inner wall surface 62 of the wall surface 60 via the curved surface 69. According to the above structure, for example, the manufacturing of the motor housing 25 by casting can be simplified. In addition, the structure of the first reinforcing rib 71 described above can also be applied to the second reinforcing rib 72. That is, when viewed along the circumferential direction, the second reinforcing rib 72 can be trapezoidal or rectangular in shape.

[0067] <Detailed Example of Motor Case 25 and Cooling Flow Path 40>

[0068] Figure 5 This is a schematic diagram of a motor housing 25 according to one embodiment of the present invention, viewed axially. As shown, the motor housing 25 includes a first main body end 81, which is one circumferential end, and a second main body end 82, which is the other circumferential end. The first main body end 81 and the second main body end 82 are circumferentially opposed to each other with a gap M therebetween. The motor housing 25 of this embodiment has a generally cylindrical shape extending in the axial direction and, when viewed axially, is generally C-shaped.

[0069] Figure 6A and Figure 6B The motor housing 25A (25) according to the first embodiment and the motor housing 25B (25) according to the second embodiment are shown respectively. In both figures, the motor housing 25 is shown in its expanded form, with the longitudinal direction of the paper corresponding to the circumferential direction (described later). Figure 6C 、 Figure 6D Also, in order to make the drawings clearer, the hatching of the reinforcing rib 70 and the hatching of the motor housing 25 are different in the two figures (described later). Figure 6C 、 Figure 6D The cooling flow path 40A ( 40 ) of the motor housing 25A, 25B ( 25 ) includes a first cooling flow path 41 and a second cooling flow path 42 extending in the circumferential direction, and a first return cooling flow path 46 communicating with the first cooling flow path 41 and the second cooling flow path 42 .

[0070] In order to realize the above-mentioned cooling flow path 40A, the motor housing 25A, 25B (25) includes a first partition wall 91. The first partition wall 91 extends along the circumferential direction in a manner to divide the cooling flow path 40A into the first cooling flow path 41, the second cooling flow path 42 and the first return cooling flow path 46. In more detail, the first partition wall 91 has a first connection end 911 connected to the first main body end 81, a first flow path forming end 912 circumferentially opposite to the second main body end 82 across the first return cooling flow path 46, and a first extension portion 913 extending circumferentially between the first connection end 911 and the first flow path forming end 912. The first extension portion 913 extends parallel to the first reinforcing rib 71 and the second reinforcing rib 72. In addition, Figure 6A 、 Figure 6B In the example, the circumferential range in which the first cooling channel 41 and the circumferential range in which the second cooling channel 42 are arranged are both the same as the circumferential range in which the first partition wall 91 is arranged. Furthermore, the first return cooling channel 46 is arranged at a position offset from the first partition wall 91 in the circumferential direction.

[0071] exist Figure 6A and Figure 6B In the example shown, the inlet 251 is formed in the first cooling channel 41, and the outlet 252 is formed in the second cooling channel 42. The coolant passing through the inlet 251 flows through the first cooling channel 41, then flows through the first return cooling channel 46 and the second cooling channel 42 in sequence, and is discharged from the outlet 252.

[0072] According to the above configuration, the provision of the first folded cooling flow path 46 increases the axial length of the cooling flow path 40 (in other words, the axial length of the motor housing 25), further improving the cooling performance of the electric compressor device 1. Furthermore, the provision of the first folded cooling flow path 46 allows the coolant to circumferentially reciprocate, thereby increasing the flow length of the cooling flow path 40 and improving the cooling performance of the electric compressor device 1.

[0073] like Figure 6A As shown, the reinforcing ribs 70A (70) involved in the first embodiment are all arranged to deviate from the first return cooling flow path 46 in the circumferential direction. More specifically, the first reinforcing rib 71 and the second reinforcing rib 72 are arranged within a circumferential range deviating from the first return cooling flow path 46. In the example shown in the figure, one end 711 of the first reinforcing rib 71 and one end 721 of the second reinforcing rib 72 can be arranged at the same circumferential position as the first flow path forming end 912. According to the above structure, the shape of the motor housing 25A can be simplified, and the manufacturing of the motor housing 25A can be simplified.

[0074] like Figure 6BAs shown, the reinforcing rib 70B (70) according to the second embodiment further includes a first curved reinforcing rib 77 disposed in the first return cooling flow path 46. The first curved reinforcing rib 77 is connected to one end 711 of the first reinforcing rib 71 and one end 721 of the second reinforcing rib 72, and is curved in an arc shape so as to protrude toward the second main body end 82. In this example, a plurality of first curved reinforcing ribs 77 are disposed, and each first curved reinforcing rib 77 is connected to one end 711 of each first reinforcing rib 71 and one end 721 of each second reinforcing rib 72.

[0075] According to the above structure, the heat transfer area in the first return cooling flow path 46 can be increased, and the cooling performance of the electric compressor device 1 can be further improved. In addition, in the first return cooling flow path 46, the coolant can flow along the first curved reinforcement rib 77, and the pressure loss of the coolant in the first return cooling flow path 46 can be reduced.

[0076] <Detailed Example of Motor Case 25 and Cooling Flow Path 40 According to Another Embodiment>

[0077] Figure 6C 、 Figure 6D The motor housing 25C (25) according to the third embodiment and the motor housing 25D (25) according to the fourth embodiment are shown. The cooling channel 40B (40) of the motor housings 25C and 25D (25) includes, in addition to the first cooling channel 41, the second cooling channel 42, and the first return cooling channel 46, a third cooling channel 43 and a second return cooling channel 48. The third cooling channel 43 is aligned with the first cooling channel 41 and the second cooling channel 42 in the axial direction and extends in the circumferential direction. The second return cooling channel 48 is connected to the second cooling channel 42 and the third cooling channel 43. The illustrated stiffeners 70C and 70D (70) include, in addition to the first stiffener 71 and the second stiffener 72, a third stiffener 73 extending in the circumferential direction in the third cooling channel 43. In this example, three third ribs 73 are arranged at intervals in the axial direction in the third cooling flow path 43 .

[0078] Figure 6C 、 Figure 6DThe motor housing 25C, 25D (25) shown further includes a second partition wall 92. The second partition wall 92 extends circumferentially to divide the cooling flow paths 40C, 40D (40) into the second cooling flow path 42 and the third cooling flow path 43. More specifically, the second partition wall 92 includes a second connection end 921 connected to the second main body end 82, a second flow path forming end 922 circumferentially opposed to the first main body end 81 across the second return cooling flow path 48, and a second extension portion 923 extending circumferentially between the second connection end 921 and the second flow path forming end 922. The second extension portion 923 extends parallel to the second reinforcing rib 72 and the third reinforcing rib 73.

[0079] exist Figure 6C 、 Figure 6D In the example shown in FIG. 1 , the second return cooling channel 48 is arranged at a position offset in the circumferential direction relative to the second and third reinforcing ribs 72 and 73. Furthermore, the circumferential lengths of the first and third reinforcing ribs 71 and 73 are the same, and the circumferential length of the second reinforcing rib 72 is shorter than the circumferential lengths of the first and third reinforcing ribs 71 and 73. Furthermore, in the examples shown in both figures, the circumferential lengths of the first and third cooling channels 41 and 43 are the same, and the circumferential length of the second cooling channel 42 is shorter than the circumferential lengths of the first and third cooling channels 41 and 43. Furthermore, the circumferential length and axial length of the second return cooling channel 48 are the same as the circumferential length and axial length of the first cooling channel 41, respectively.

[0080] exist Figure 6C and Figure 6D In the motor housing 25C, 25D (25) shown, an inlet 251 is formed in the first cooling flow path 41, and an outlet 252 is formed in the third cooling flow path 43. The coolant passing through the inlet 251 flows through the first cooling flow path 41, the first return cooling flow path 46, the second cooling flow path 42, the second return cooling flow path 48, and the third cooling flow path 43 in sequence and is discharged from the outlet 252.

[0081] According to the above configuration, by providing the second return cooling flow path 48 in addition to the first return cooling flow path 46, the axial length of the cooling flow path 40 (in other words, the axial length of the motor housing 25) can be lengthened, further improving the cooling performance of the electric compressor device 1. Furthermore, by providing the second return cooling flow path 48, the number of times the coolant reciprocates in the circumferential direction increases, thereby increasing the flow path length of the cooling flow path 40 and improving the cooling performance of the electric compressor device 1.

[0082] exist Figure 6CIn the illustrated reinforcing rib 70C (70), the second reinforcing rib 72 and the third reinforcing rib 73 are arranged within a circumferential range that deviates from the second return cooling flow path 48. The other end 722 of the second reinforcing rib 72 and the one end 731 of the third reinforcing rib 73 can be arranged at the same circumferential position as the second flow path forming end 922. According to the above structure, the shape of the motor housing 25C can be simplified, and the manufacturing of the motor housing 25C can be simplified.

[0083] exist Figure 6D The illustrated reinforcing rib 70D (70) further includes a second curved reinforcing rib 78 also disposed in the second return cooling flow path 48. The second curved reinforcing rib 78 is connected to the other end 722 of the second reinforcing rib 72 and the one end 731 of the third reinforcing rib 73, and is curved in an arc shape so as to protrude toward the first main body end 81. In this example, a plurality of second curved reinforcing ribs 78 are disposed, each of which is connected to the other end 722 of each second reinforcing rib 72 and the one end 731 of each third reinforcing rib 73.

[0084] According to the above structure, the heat transfer area in the second return cooling flow path 48 can be increased, and the cooling performance of the electric compressor device 1 can be further improved. In addition, in the second return cooling flow path 48, the coolant can flow along the second curved reinforcement rib 78, and the pressure loss of the coolant in the second return cooling flow path 48 can be reduced.

[0085] Other Modifications

[0086] The electric compressor device 1 is not limited to Figure 1 The electric compressor device 1 may be a single-stage compression electric compressor assembled in a turbocharger device.

[0087] Furthermore, the radial length of the first curved rib 77 may be shorter than at least one of the radial length of the first rib 71 or the radial length of the second rib 72. In this case, the coolant flowing along the first curved rib 77 in the first turned cooling flow path 46 can flow over the first curved rib 77, thereby reducing pressure loss in the first turned cooling flow path 46.

[0088] Furthermore, the first curved reinforcement rib 77 is not limited to extending continuously between one end 711 of the first reinforcement rib 71 and one end 721 of the second reinforcement rib 72. A first through hole extending circumferentially can be formed in the first curved reinforcement rib 77. For example, the first curved reinforcement rib 77 can include a first connecting curved reinforcement rib extending in an arc shape from one end 711 and a second connecting curved reinforcement rib extending in an arc shape from one end 721, and a gap serving as the first through hole is formed between the first connecting curved reinforcement rib and the second connecting curved reinforcement rib. The first connecting curved reinforcement rib and the second connecting curved reinforcement rib have the same curvature radius. In this case, the coolant flowing through the first return cooling flow path 46 can also pass through the gap, which can improve heat transfer in the first return cooling flow path 46 compared to a case where the flow of coolant in the circumferential direction is restricted by the first curved reinforcement rib 77.

[0089] Similarly, the second curved reinforcement rib 78 is not limited to extending continuously between the other end 722 of the second reinforcement rib 72 and the one end 731 of the third reinforcement rib 73. A second through hole extending circumferentially can be formed in the second curved reinforcement rib 78. For example, the second curved reinforcement rib 78 can include a third connecting curved reinforcement rib extending in an arc shape from the other end 722 and a fourth connecting curved reinforcement rib extending in an arc shape from the one end 731, with a gap serving as the second through hole formed between the third connecting curved reinforcement rib and the fourth connecting curved reinforcement rib. The third connecting curved reinforcement rib and the fourth connecting curved reinforcement rib have the same curvature radius. In this case, the coolant flowing through the second return cooling flow path 48 can also pass through the gap, which can improve heat transfer in the second return cooling flow path 48 compared to a case where the flow of coolant in the circumferential direction is restricted by the second curved reinforcement rib 78.

[0090] Summary

[0091] The contents described in the above-mentioned several embodiments can be understood, for example, as follows.

[0092] 1) An electric compressor device 1 according to at least one embodiment of the present invention includes:

[0093] Rotation axis 2;

[0094] a compressor impeller (at least one of the low-pressure stage impeller 13 or the high-pressure stage impeller 14 ), disposed on the rotating shaft;

[0095] a motor 5 for driving the rotating shaft; and

[0096] The motor housing 25 accommodates the motor.

[0097] The motor comprises:

[0098] a rotor 51 fixed to the rotating shaft; and

[0099] The stator 52 is arranged around the rotor and supported by the motor housing.

[0100] A cooling flow path 40 for cooling liquid to flow in the circumferential direction is formed inside the motor housing at a position radially outward of the stator.

[0101] When viewed along the circumferential direction, the axial length of the cooling flow path is more than twice the radial length of the cooling flow path.

[0102] The electric compressor device is provided with at least one rib 70 that protrudes radially outward from a radially inner wall surface 62 of a wall surface 60 of the motor housing defining the cooling flow path and extends in the circumferential direction.

[0103] According to the configuration in 1) above, the aspect ratio of the cooling channel is less than 1, thereby increasing the flow rate of the coolant in the cooling channel. Furthermore, the provision of at least one reinforcing rib moderately narrows the channel cross-sectional area, further increasing the flow rate. This increases the heat transfer coefficient between the cooling channel and the coolant. Furthermore, the provision of the reinforcing rib also increases the heat transfer area. Consequently, an electric compressor device with improved cooling performance can be realized.

[0104] 2) In some embodiments, in the electric compressor device described in 1) above,

[0105] The radial length of the reinforcing rib is less than or equal to 4 / 5 of the maximum radial length of the cooling flow path.

[0106] According to the structure 2) above, a reduction in the coolant flow rate due to excessive narrowing of the cooling channel by the reinforcing ribs can be avoided, and a local increase in the coolant flow rate in the cooling channel and an associated increase in pressure loss can be avoided.

[0107] 3) In some embodiments, in the electric compressor device described in 1) or 2) above,

[0108] A plurality of the at least one reinforcing ribs are arranged at intervals in the axial direction.

[0109] According to the structure of 3) above, the heat transfer area is further increased, and thus the cooling performance of the electric compressor device is further improved.

[0110] 4) In some embodiments, in the electric compressor device described in 3) above,

[0111] The plurality of reinforcing ribs each have a radially outer end, i.e., a top portion 175.

[0112] The plurality of reinforcing ribs are arranged in the axial direction at intervals longer than the axial length of the top portion.

[0113] According to the structure of 4) above, it is possible to avoid an excessive increase in the flow velocity of the coolant and an associated increase in pressure loss due to an excessively short interval between two adjacent ribs.

[0114] 5) In some embodiments, in the electric compressor device described in 4) above,

[0115] When viewed along the circumferential direction, the plurality of reinforcing ribs are respectively in a trapezoidal shape or a rectangular shape.

[0116] According to the structure of 5) above, the manufacture of the motor case can be simplified.

[0117] 6) In some embodiments, in the electric compressor device described in any one of 3) to 5) above,

[0118] The plurality of reinforcing ribs each have a radially outer end, i.e., a top portion 175.

[0119] The wall surface of the motor housing includes a side surface 65 facing the axial direction and defining the cooling flow path.

[0120] A distance between the reinforcing rib closest to the side surface and the side surface is longer than an axial length of the top portion.

[0121] According to the structure of 6) above, it is possible to avoid an excessive increase in the flow velocity of the coolant and an associated increase in pressure loss due to an excessively short distance between the rib and the side surface.

[0122] 7) In some embodiments, in the electric compressor device described in any one of 3) to 6) above,

[0123] The number of the reinforcing ribs arranged in the cooling flow path extending along the circumferential direction is three or more.

[0124] According to the structure of 7) above, the heat transfer area is further increased, and thus the cooling performance of the electric compressor device is further improved.

[0125] 8) In some embodiments, in the electric compressor device described in any one of 1) to 7) above,

[0126] The motor housing comprises:

[0127] The first main body end portion 81 is one end portion in the circumferential direction;

[0128] The second main body end 82 is the other end in the circumferential direction and is opposite to the first main body end with a gap M therebetween; and

[0129] The first partition wall 91 extends along the circumferential direction so as to divide the cooling flow path into the first cooling flow path 41 and the second cooling flow path 42 arranged in the axial direction and the first return cooling flow path 46 communicating with the first cooling flow path and the second cooling flow path.

[0130] The first partition wall has:

[0131] A first connecting end portion 911 connected to the first main body end portion; and

[0132] The first flow path forming end portion 912 faces the second main body end portion in the circumferential direction across the first folded cooling flow path.

[0133] According to the configuration of 8), by providing the first folded cooling flow path in the cooling flow path, the axial length of the cooling flow path can be lengthened, and the cooling performance of the electric compressor device can be further improved.

[0134] 9) In some embodiments, in the electric compressor device described in 8) above,

[0135] The at least one reinforcing rib is arranged to be offset from the first folded cooling flow path in the circumferential direction.

[0136] According to the structure of 9) above, the manufacture of the motor case can be simplified.

[0137] 10) In some embodiments, in the electric compressor device described in 8) above,

[0138] The at least one reinforcing rib has:

[0139] a first reinforcing rib 71 extending along the circumferential direction in the first cooling flow path;

[0140] a second reinforcing rib 72 extending along the circumferential direction in the second cooling flow path; and

[0141] The curved rib (first curved rib 77 ) is curved to protrude toward the second main body end in the first folded cooling flow path and is connected to one end 711 of the first rib and one end 721 of the second rib.

[0142] The structure of step 10) above increases the heat transfer area in the first folded cooling channel, further improving the cooling performance of the electric compressor device. Furthermore, in the first folded cooling channel, the coolant can flow along the curved ribs, reducing the pressure loss of the coolant in the first folded cooling channel.

[0143] 11) In some embodiments, in the electric compressor device described in any one of 8) to 10) above,

[0144] The motor housing further comprises:

[0145] The second partition wall 92 extends along the circumferential direction so as to divide the cooling flow path into the second cooling flow path and the third cooling flow path 43 arranged in the axial direction and the second return cooling flow path 48 communicating with the second cooling flow path and the third cooling flow path.

[0146] The second partition wall has:

[0147] A second connecting end portion 921 connected to the second main body end portion; and

[0148] The second flow path forming end portion 922 faces the first main body end portion in the circumferential direction via the second folded cooling flow path.

[0149] According to the configuration of 11), by further providing the second folded cooling flow path in the cooling flow path, the axial length of the cooling flow path can be further lengthened, and the cooling performance of the electric compressor device can be further improved.

[0150] Explanation of symbols

[0151] 1-Electric compressor device, 2-Rotating shaft, 3-Low-pressure stage compressor, 4-High-pressure stage compressor, 5-Motor, 13-Low-pressure stage impeller, 14-High-pressure stage impeller, 20-Casing, 23-Low-pressure side casing, 24-High-pressure side casing, 25-Motor casing, 40-Cooling flow path, 41-First cooling flow path, 42-Second cooling flow path, 43-Third cooling flow path, 46-First folded cooling flow path, 48-Second folded cooling flow path, 51-Rotor, 52-Stator, 53-Stator core, 54-Stator coil, 60-Wall surface, 62-Radially inner wall surface, 64-Radially outer wall surface, 65-Side surface, 69-Curved surface, 70-Reinforcement rib, 71-First reinforcing rib , 72-the second reinforcement rib, 73-the third reinforcement rib, 77-the first curved reinforcement rib, 78-the second curved reinforcement rib, 81-the first main body end, 82-the second main body end, 91-the first partition wall, 92-the second partition wall, 175-top, 236, 246-inlet, 237, 247-diffuser, 238, 248-vortex portion, 251-inlet, 252-outlet, 711, 721, 731-one end, 722-the other end, 911-the first connecting end, 912-the first flow path forming end, 913-the first extension portion, 921-the second connecting end, 922-the second flow path forming end, 923-the second extension portion, M-gap.

Claims

1. An electric compressor device comprising: Rotation axis; a compressor impeller, disposed on the rotating shaft; a motor for driving the rotating shaft; and a motor housing accommodating the motor, The motor comprises: a rotor fixed to the rotating shaft; and a stator disposed around the rotor and supported by the motor housing; A cooling flow path for cooling liquid to flow in a circumferential direction is formed inside the motor housing at a position radially outward of the stator. When viewed along the circumferential direction, the axial length of the cooling flow path is more than twice the radial length of the cooling flow path. The electric compressor device is provided with at least one reinforcing rib that protrudes from a radially inner wall surface of a wall surface of the motor housing defining the cooling flow path toward the radially outer side and extends along the circumferential direction.

2. The electric compressor device according to claim 1, wherein The radial length of the reinforcing rib is less than or equal to 4 / 5 of the maximum radial length of the cooling flow path.

3. The electric compressor device according to claim 1 or 2, wherein: A plurality of the at least one reinforcing ribs are arranged at intervals in the axial direction.

4. The electric compressor device according to claim 3, wherein The plurality of reinforcing ribs each have an outer end in the radial direction, i.e., a top. The plurality of reinforcing ribs are arranged in the axial direction at intervals longer than the axial length of the top portion.

5. The electric compressor device according to claim 4, wherein When viewed along the circumferential direction, the plurality of reinforcing ribs are respectively in a trapezoidal shape or a rectangular shape.

6. The electric compressor device according to claim 3, wherein The plurality of reinforcing ribs each have an outer end in the radial direction, i.e., a top. The wall surface of the motor housing includes a side surface facing the axial direction and defining the cooling flow path. A distance between the reinforcing rib closest to the side surface and the side surface is longer than an axial length of the top portion.

7. The electric compressor device according to claim 3, wherein The number of the reinforcing ribs arranged in the cooling flow path extending along the circumferential direction is three or more.

8. The electric compressor device according to claim 1 or 2, wherein: The motor housing comprises: The first main body end is one end in the circumferential direction; a second main body end portion, which is the other end portion in the circumferential direction and faces the first main body end portion with a gap therebetween; and a first partition wall extending along the circumferential direction so as to divide the cooling flow path into a first cooling flow path and a second cooling flow path arranged in the axial direction, and a first return cooling flow path communicating with the first cooling flow path and the second cooling flow path; The first partition wall has: a first connecting end portion connected to the first main body end portion; and The first flow channel forming end portion faces the second main body end portion in the circumferential direction across the first folded cooling flow channel.

9. The electric compressor device according to claim 8, wherein The at least one reinforcing rib is arranged to be offset from the first folded cooling flow path in the circumferential direction.

10. The electric compressor device according to claim 8, wherein The at least one reinforcing rib has: a first reinforcing rib extending along the circumferential direction in the first cooling flow path; a second reinforcing rib extending along the circumferential direction in the second cooling flow path; and The curved reinforcing rib is curved so as to protrude toward the second main body end in the first folded cooling flow path and is connected to one end of the first reinforcing rib and one end of the second reinforcing rib.

11. The electric compressor device according to claim 8, wherein The motor housing further comprises: a second partition wall extending along the circumferential direction so as to divide the cooling flow path into the second cooling flow path and the third cooling flow path arranged in the axial direction and a second return cooling flow path communicating with the second cooling flow path and the third cooling flow path; The second partition wall has: a second connecting end portion connected to the second main body end portion; and The second flow channel forming end portion faces the first main body end portion in the circumferential direction across the second folded cooling flow channel.

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