JP2014166031A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor capable of improving productivity of a housing by suppressing high frequency sound caused by expanding/contracting vibration of a stator and high frequency sound caused by film surface vibration of the housing.SOLUTION: A housing 20 of a motor 10 comprises an inner cylinder 21 holding a stator 13, and an outer cylinder 22 provided at the outer peripheral side of the inner cylinder 21 and forming a cooling water channel 30 between the inner cylinder 21 and itself. Within the cooling water channel 30, a plurality of inner ribs 41-43 radially connecting the inner cylinder 21 and the outer cylinder 22 and extending circumferentially are provided side by side in an axial direction. The cooling water channel 30 is divided into a plurality of channels 31-34 by the plurality of inner ribs 41-43, and at positions radially overlapped with the plurality of channels 31-34 on an outer peripheral surface of the outer cylinder 22, outer ribs 45 protruding outside in a radial direction and extending circumferentially are provided, respectively.

Description

  The present invention relates to an electric motor, and more particularly to an electric motor housing.

  A conventional electric motor has an inner cylinder that holds a stator, and an outer cylinder that forms a cooling water passage for flowing cooling water between the inner cylinder, and the inner cylinder and the outer cylinder are arranged in the cooling water passage. What connects with the several support | pillar which was made is known (for example, refer patent document 1).

JP 2010-041835 A

  However, the electric motor described in Patent Document 1 is arranged so that a plurality of support columns are interspersed, and the circumferential rigidity of the housing is low, so that high-frequency sound is generated due to the expansion and contraction vibration of the stator. Moreover, although the rigidity of the housing is improved by providing ribs on the outer side in the radial direction of the support column, the effect on the circumferential rigidity of the housing is small, and the high-frequency sound cannot be suppressed.

  In addition, the support is arranged in the part where the thin wall area of the housing is increased to reduce the area where the membrane vibration occurs, and the high frequency sound caused by the membrane vibration is suppressed. However, it has become difficult to discharge core sand during casting, and the productivity of the housing was not good.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to suppress the high-frequency sound caused by the expansion / contraction vibration of the stator and the high-frequency sound caused by the film surface vibration of the housing, thereby producing the housing. An object of the present invention is to provide an electric motor capable of improving the performance.

In order to achieve the above object, the invention according to claim 1
A shaft (for example, a shaft 11 in an embodiment described later);
A rotor (for example, a rotor 12 in an embodiment described later) provided on the shaft;
A stator (for example, a stator 13 in an embodiment described later) provided on the outer peripheral side of the rotor;
In an electric motor (for example, an electric motor 10 in an embodiment described later) including a housing that holds the stator (for example, a housing 20 in an embodiment described later),
The housing is
An inner cylinder holding the stator (for example, an inner cylinder 21 in an embodiment described later);
An outer cylinder (for example, in an embodiment described later) that is provided on the outer peripheral side of the inner cylinder and forms a cooling water channel (for example, a cooling water channel 30 in an embodiment described later) between which the cooling water flows between the inner cylinder. An outer cylinder 22),
A plurality of inner ribs (for example, first to third inner ribs 41 to 43 in an embodiment described later) are connected to the inner and outer cylinders in the cooling water flow path in the radial direction and extend in the circumferential direction. Provided side by side,
The cooling water flow path is divided into a plurality of flow paths (for example, first to fourth flow paths 31 to 34 in embodiments described later) by the plurality of inner ribs,
Outer ribs (for example, outer ribs 45 in the embodiments described later) that protrude outward in the radial direction and extend in the circumferential direction are respectively provided at positions on the outer peripheral surface of the outer cylinder that overlap the plurality of flow paths in the radial direction. And

In addition to the structure of Claim 1, the invention according to Claim 2
The outer rib (for example, the outer rib 45 in the embodiment described later) overlaps the axial center of the plurality of flow paths (for example, first to fourth flow paths 31 to 34 in the embodiment described later) in the radial direction. It is characterized by being provided at each position.

The invention according to claim 3 includes, in addition to the configuration according to claim 1 or 2,
In the housing (for example, the housing 20 in an embodiment described later), an inflow port (for example, a flow in the embodiment described later) into which the cooling water flows into the cooling water channel (for example, the cooling water channel 30 in the embodiment described later). An inlet 25), an outlet (for example, an outlet 26 in an embodiment described later) for allowing cooling water to flow out from the cooling water flow path, and an air outlet (for example, an air outlet in an embodiment described later) for extracting air from the cooling water. 27)
The cooling water flow path has a communication path (for example, a communication path 35 in an embodiment described later) that communicates the plurality of flow paths (for example, first to fourth flow paths 31 to 34 in the embodiment described later) in the axial direction. ) Are provided,
The inflow port, the outflow port, and the air vent port are respectively arranged at positions that overlap the plurality of communication paths in the circumferential direction.

  According to the first aspect of the present invention, the housing includes an inner cylinder that holds the stator, and an outer cylinder that is provided on the outer peripheral side of the inner cylinder and that forms a cooling water flow path for flowing cooling water between the inner cylinder and the inner cylinder. In the cooling water flow path, the inner cylinder and the outer cylinder are connected in the radial direction and a plurality of inner ribs extending in the circumferential direction are provided side by side in the axial direction, so that the circumferential rigidity of the housing can be improved. The high frequency sound resulting from the expansion and contraction vibration of the stator can be suppressed. In addition, the cooling water flow path is divided into a plurality of flow paths by a plurality of inner ribs, and outer ribs that protrude in the radial direction and extend in the circumferential direction are positioned at positions that overlap the plurality of flow paths on the outer peripheral surface of the outer cylinder in the radial direction. Since it is provided, it is possible to reduce the area where the film surface vibrates, and to suppress high-frequency sound caused by the film surface vibration. In addition, since a plurality of inner ribs are provided along the circumferential direction in the cooling water flow path, the structure of the cooling water flow path can be simplified, thereby facilitating the discharge of core sand during casting, and the housing The productivity can be improved.

  According to the second aspect of the present invention, since the outer ribs are provided at positions that overlap the axial centers of the plurality of flow paths in the radial direction, the area of membrane vibration can be efficiently reduced.

  According to the invention of claim 3, since the cooling water inlet, the cooling water outlet, and the cooling water air vent are respectively arranged at positions overlapping with the plurality of communication paths in the circumferential direction, The flow of cooling water can be improved. Thereby, since the pressure loss of a cooling water pump can be reduced, a low-cost cooling water pump can be employ | adopted and the manufacturing cost of an electric motor can be reduced.

It is sectional drawing explaining one Embodiment of the electric motor which concerns on this invention. It is the sectional view on the AA line of the housing shown in FIG. It is a BB sectional view of the housing shown in FIG. It is a perspective view explaining the cooling water flow path shown in FIG. FIG. 2 is a development view of the housing shown in FIG. 1.

  Hereinafter, an embodiment of an electric motor according to the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, the electric motor 10 of the present embodiment includes a shaft 11, a rotor 12 provided on the shaft 11, a stator 13 provided on the outer peripheral side of the rotor 12, and a housing 20 that holds the stator 13. Prepare. The stator 13 includes a stator core 13a and coils 13b provided on both sides in the axial direction of the stator core 13a.

  The housing 20 has a cylindrical shape, the stator 13 is press-fitted into the inner peripheral surface, is provided on the outer peripheral side of the inner cylinder 21 that holds the stator 13, and allows cooling water to flow between the inner cylinder 21. The outer cylinder 22 that forms the cooling water flow path 30, the inner cylinder 21, and one axial end portion (the left end portion in FIG. 1) of the outer cylinder 22 are connected in the radial direction to close the cooling water flow path 30. And a second end portion 24 that connects the other axial end portions (the right end portion in FIG. 1) of the inner cylinder 21 and the outer cylinder 22 in the radial direction and closes the cooling water passage 30.

  The cooling water channel 30 is formed in an annular shape, and the axial width thereof is set to be substantially the same as the axial width of the stator core 13 a of the stator 13.

  As shown in FIGS. 1 to 5, first to third inner ribs 41 to 43 extending in the circumferential direction by connecting the inner cylinder 21 and the outer cylinder 22 in the radial direction in the cooling water flow path 30 of the housing 20. Are provided side by side in the axial direction. For this reason, the cooling water passage 30 is divided into first to fourth passages 31 to 34 by first to third inner ribs 41 to 43.

  As shown in FIGS. 2 to 5, the cooling water flow path 30 is provided with a plurality of communication paths 35 in the circumferential direction that allow the first to fourth flow paths 31 to 34 to communicate in the axial direction. For this reason, the first to third inner ribs 41 to 43 are divided into a plurality in the circumferential direction by the plurality of communication paths 35.

  In addition, as shown in FIG. 2, the housing 20 includes an inlet 25 that allows cooling water to flow into the cooling water passage 30, an outlet 26 that causes the cooling water to flow out from the cooling water passage 30, and air that extracts air from the cooling water. A vent 27 is formed, and the inlet 25, the outlet 26, and the air vent 27 are respectively arranged at positions overlapping with the plurality of communication passages 35 of the cooling water flow path 30 in the circumferential direction.

  In addition, outer ribs 45 that protrude radially outward and extend in the circumferential direction are provided on the outer peripheral surface of the outer cylinder 22 of the housing 20 at positions that overlap the first to fourth flow paths 31 to 34 in the radial direction. . More specifically, the outer rib 45 is provided at a position that overlaps the axial center of each of the first to fourth flow paths 31 to 34 in the radial direction.

  FIG. 4 is a perspective view showing the shape of the cooling water flow path 30 extracted, and this corresponds to the shape of the core when the housing 20 of the electric motor 10 is cast. And in the electric motor 10 of this embodiment, as shown in FIG.4 and FIG.5, since the 1st-3rd inner side ribs 41-43 are provided in the cooling water flow path 30 along the circumferential direction, the cooling water flow path 30 The structure is simplified. For this reason, since core sand can be easily discharged during casting, the productivity of the housing 20 is improved. In addition, since the structure of the cooling water flow path 30 is simplified and the cooling water easily passes through the cooling water flow path 30, pressure loss is reduced, and a low-cost cooling water pump can be employed. The manufacturing cost is reduced. Therefore, the cooling water flow path 30 of the present embodiment has a shape that takes into consideration the casting of the housing 20, the flow of the cooling water, and the manufacturing cost.

  As described above, according to the electric motor 10 of the present embodiment, the first to third inner ribs extending in the circumferential direction by connecting the inner cylinder 21 and the outer cylinder 22 in the radial direction in the cooling water flow path 30 of the housing 20. Since 41-43 are provided along with an axial direction, the circumferential direction rigidity of the housing 20 can be improved and the high frequency sound resulting from the expansion-contraction vibration of the stator 13 can be suppressed. Further, the cooling water flow path 30 is divided into first to fourth flow paths 31 to 34 by first to third inner ribs 41 to 43, and the first to fourth flow paths 31 to 34 on the outer peripheral surface of the outer cylinder 22 and Since outer ribs 45 that protrude radially outward and extend in the circumferential direction are provided at positions that overlap in the radial direction, the area where the membrane vibration occurs can be reduced, and high-frequency sound caused by the membrane vibration can be suppressed. it can.

  Moreover, according to the electric motor 10 of this embodiment, since the 1st-3rd inner side ribs 41-43 are provided in the cooling water flow path 30 along the circumferential direction, the structure of the cooling water flow path 30 can be simplified. it can. Thereby, discharge of core sand at the time of casting becomes easy, and the productivity of the housing 20 can be improved. Moreover, since the structure of the cooling water flow path 30 is simplified and the cooling water easily passes through the cooling water flow path 30, pressure loss can be reduced. Thereby, since a low-cost cooling water pump can be employ | adopted, the manufacturing cost of the electric motor 10 can be reduced.

  Moreover, according to the electric motor 10 of this embodiment, since the outer rib 45 is provided in the position which overlaps with the axial direction center and radial direction of the 1st-4th flow paths 31-34, respectively, the area which carries out a film surface vibration is efficiently obtained. Can be reduced.

  Further, according to the electric motor 10 of the present embodiment, the cooling water inlet 25, the cooling water outlet 26, and the cooling water air outlet 27 are respectively arranged at positions overlapping with the plurality of communication paths 35 in the circumferential direction. Therefore, the flow of the cooling water in the cooling water channel 30 can be improved. Thereby, since the pressure loss of a cooling water pump can be reduced, a low-cost cooling water pump can be employ | adopted and the manufacturing cost of the electric motor 10 can be reduced.

In addition, this invention is not limited to what was illustrated to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.
For example, in the above embodiment, three inner ribs are provided, but the present invention is not limited to this, and it is sufficient that two or more inner ribs are provided.
Moreover, in the said embodiment, although one outer side rib is provided with respect to one flow path, it is not limited to this, A plurality may be provided with respect to one flow path.
Moreover, in the said embodiment, although the outer side rib is provided in the position which overlaps with a flow path in radial direction, it is not limited to this, You may provide in addition to the position which overlaps with an inner side rib in radial direction.

DESCRIPTION OF SYMBOLS 10 Electric motor 11 Shaft 12 Rotor 13 Stator 20 Housing 21 Inner cylinder 22 Outer cylinder 30 Cooling water flow path 31 1st flow path 32 2nd flow path 33 3rd flow path 34 4th flow path 35 Communication path 41 1st inner side rib 42 1st 2 inner rib 43 third inner rib 45 outer rib

  The present invention relates to an electric motor, and more particularly to an electric motor housing.

  A conventional electric motor has an inner cylinder that holds a stator, and an outer cylinder that forms a cooling water passage for flowing cooling water between the inner cylinder, and the inner cylinder and the outer cylinder are arranged in the cooling water passage. What connects with the several support | pillar which was made is known (for example, refer patent document 1).

JP 2010-041835 A

  However, the electric motor described in Patent Document 1 is arranged so that a plurality of support columns are interspersed, and the circumferential rigidity of the housing is low, so that high-frequency sound is generated due to the expansion and contraction vibration of the stator. Moreover, although the rigidity of the housing is improved by providing ribs on the outer side in the radial direction of the support column, the effect on the circumferential rigidity of the housing is small, and the high-frequency sound cannot be suppressed.

  In addition, the support is arranged in the part where the thin wall area of the housing is increased to reduce the area where the membrane vibration occurs, and the high frequency sound caused by the membrane vibration is suppressed. However, it has become difficult to discharge core sand during casting, and the productivity of the housing was not good.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to suppress the high-frequency sound caused by the expansion / contraction vibration of the stator and the high-frequency sound caused by the film surface vibration of the housing, thereby producing the housing. An object of the present invention is to provide an electric motor capable of improving the performance.

In order to achieve the above object, the invention according to claim 1
A shaft (for example, a shaft 11 in an embodiment described later);
A rotor (for example, a rotor 12 in an embodiment described later) provided on the shaft;
A stator (for example, a stator 13 in an embodiment described later) provided on the outer peripheral side of the rotor;
In an electric motor (for example, an electric motor 10 in an embodiment described later) including a housing that holds the stator (for example, a housing 20 in an embodiment described later),
The housing is
An inner cylinder holding the stator (for example, an inner cylinder 21 in an embodiment described later);
An outer cylinder (for example, in an embodiment described later) that is provided on the outer peripheral side of the inner cylinder and forms a cooling water channel (for example, a cooling water channel 30 in an embodiment described later) between which the cooling water flows between the inner cylinder. An outer cylinder 22),
A plurality of inner ribs (for example, first to third inner ribs 41 to 43 in an embodiment described later) are connected to the inner and outer cylinders in the cooling water flow path in the radial direction and extend in the circumferential direction. Provided side by side,
The cooling water flow path is divided into a plurality of flow paths (for example, first to fourth flow paths 31 to 34 in embodiments described later) by the plurality of inner ribs,
Outer ribs (for example, outer ribs 45 in the embodiments described later) that protrude outward in the radial direction and extend in the circumferential direction are respectively provided at positions on the outer peripheral surface of the outer cylinder that overlap the plurality of flow paths in the radial direction. And

In addition to the structure of Claim 1, the invention according to Claim 2
The outer rib (for example, the outer rib 45 in the embodiment described later) overlaps the axial center of the plurality of flow paths (for example, first to fourth flow paths 31 to 34 in the embodiment described later) in the radial direction. It is characterized by being provided at each position .

  According to the first aspect of the present invention, the housing includes an inner cylinder that holds the stator, and an outer cylinder that is provided on the outer peripheral side of the inner cylinder and that forms a cooling water flow path for flowing cooling water between the inner cylinder and the inner cylinder. In the cooling water flow path, the inner cylinder and the outer cylinder are connected in the radial direction and a plurality of inner ribs extending in the circumferential direction are provided side by side in the axial direction, so that the circumferential rigidity of the housing can be improved. The high frequency sound resulting from the expansion and contraction vibration of the stator can be suppressed. In addition, the cooling water flow path is divided into a plurality of flow paths by a plurality of inner ribs, and outer ribs that protrude in the radial direction and extend in the circumferential direction are positioned at positions that overlap the plurality of flow paths on the outer peripheral surface of the outer cylinder in the radial direction. Since it is provided, it is possible to reduce the area where the film surface vibrates, and to suppress high-frequency sound caused by the film surface vibration. In addition, since a plurality of inner ribs are provided along the circumferential direction in the cooling water flow path, the structure of the cooling water flow path can be simplified, thereby facilitating the discharge of core sand during casting, and the housing The productivity can be improved.

According to the second aspect of the present invention, since the outer ribs are provided at positions that overlap the axial centers of the plurality of flow paths in the radial direction, the area of membrane vibration can be efficiently reduced .

It is sectional drawing explaining one Embodiment of the electric motor which concerns on this invention. It is the sectional view on the AA line of the housing shown in FIG. It is a BB sectional view of the housing shown in FIG. It is a perspective view explaining the cooling water flow path shown in FIG. FIG. 2 is a development view of the housing shown in FIG. 1.

  Hereinafter, an embodiment of an electric motor according to the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, the electric motor 10 of the present embodiment includes a shaft 11, a rotor 12 provided on the shaft 11, a stator 13 provided on the outer peripheral side of the rotor 12, and a housing 20 that holds the stator 13. Prepare. The stator 13 includes a stator core 13a and coils 13b provided on both sides in the axial direction of the stator core 13a.

  The housing 20 has a cylindrical shape, the stator 13 is press-fitted into the inner peripheral surface, is provided on the outer peripheral side of the inner cylinder 21 that holds the stator 13, and allows cooling water to flow between the inner cylinder 21. The outer cylinder 22 that forms the cooling water flow path 30, the inner cylinder 21, and one axial end portion (the left end portion in FIG. 1) of the outer cylinder 22 are connected in the radial direction to close the cooling water flow path 30. And a second end portion 24 that connects the other axial end portions (the right end portion in FIG. 1) of the inner cylinder 21 and the outer cylinder 22 in the radial direction and closes the cooling water passage 30.

  The cooling water channel 30 is formed in an annular shape, and the axial width thereof is set to be substantially the same as the axial width of the stator core 13 a of the stator 13.

  As shown in FIGS. 1 to 5, first to third inner ribs 41 to 43 extending in the circumferential direction by connecting the inner cylinder 21 and the outer cylinder 22 in the radial direction in the cooling water flow path 30 of the housing 20. Are provided side by side in the axial direction. For this reason, the cooling water passage 30 is divided into first to fourth passages 31 to 34 by first to third inner ribs 41 to 43.

  As shown in FIGS. 2 to 5, the cooling water flow path 30 is provided with a plurality of communication paths 35 in the circumferential direction that allow the first to fourth flow paths 31 to 34 to communicate in the axial direction. For this reason, the first to third inner ribs 41 to 43 are divided into a plurality in the circumferential direction by the plurality of communication paths 35.

Further, as shown in FIG. 2, the housing 20, inlet port 25 to flow into the cooling water in the cooling water passage 30, and an outlet 2 6 for cooling water flows out from the cooling water passage 30 is formed.

  In addition, outer ribs 45 that protrude radially outward and extend in the circumferential direction are provided on the outer peripheral surface of the outer cylinder 22 of the housing 20 at positions that overlap the first to fourth flow paths 31 to 34 in the radial direction. . More specifically, the outer rib 45 is provided at a position that overlaps the axial center of each of the first to fourth flow paths 31 to 34 in the radial direction.

  FIG. 4 is a perspective view showing the shape of the cooling water flow path 30 extracted, and this corresponds to the shape of the core when the housing 20 of the electric motor 10 is cast. And in the electric motor 10 of this embodiment, as shown in FIG.4 and FIG.5, since the 1st-3rd inner side ribs 41-43 are provided in the cooling water flow path 30 along the circumferential direction, the cooling water flow path 30 The structure is simplified. For this reason, since core sand can be easily discharged during casting, the productivity of the housing 20 is improved. In addition, since the structure of the cooling water flow path 30 is simplified and the cooling water easily passes through the cooling water flow path 30, pressure loss is reduced, and a low-cost cooling water pump can be employed. The manufacturing cost is reduced. Therefore, the cooling water flow path 30 of the present embodiment has a shape that takes into consideration the casting of the housing 20, the flow of the cooling water, and the manufacturing cost.

  As described above, according to the electric motor 10 of the present embodiment, the first to third inner ribs extending in the circumferential direction by connecting the inner cylinder 21 and the outer cylinder 22 in the radial direction in the cooling water flow path 30 of the housing 20. Since 41-43 are provided along with an axial direction, the circumferential direction rigidity of the housing 20 can be improved and the high frequency sound resulting from the expansion-contraction vibration of the stator 13 can be suppressed. Further, the cooling water flow path 30 is divided into first to fourth flow paths 31 to 34 by first to third inner ribs 41 to 43, and the first to fourth flow paths 31 to 34 on the outer peripheral surface of the outer cylinder 22 and Since outer ribs 45 that protrude radially outward and extend in the circumferential direction are provided at positions that overlap in the radial direction, the area where the membrane vibration occurs can be reduced, and high-frequency sound caused by the membrane vibration can be suppressed. it can.

  Moreover, according to the electric motor 10 of this embodiment, since the 1st-3rd inner side ribs 41-43 are provided in the cooling water flow path 30 along the circumferential direction, the structure of the cooling water flow path 30 can be simplified. it can. Thereby, discharge of core sand at the time of casting becomes easy, and the productivity of the housing 20 can be improved. Moreover, since the structure of the cooling water flow path 30 is simplified and the cooling water easily passes through the cooling water flow path 30, pressure loss can be reduced. Thereby, since a low-cost cooling water pump can be employ | adopted, the manufacturing cost of the electric motor 10 can be reduced.

Moreover, according to the electric motor 10 of this embodiment, since the outer rib 45 is provided in the position which overlaps with the axial direction center and radial direction of the 1st-4th flow paths 31-34, respectively, the area which carries out a film surface vibration is efficiently obtained. Can be reduced .

In addition, this invention is not limited to what was illustrated to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.
For example, in the above embodiment, three inner ribs are provided, but the present invention is not limited to this, and it is sufficient that two or more inner ribs are provided.
Moreover, in the said embodiment, although one outer side rib is provided with respect to one flow path, it is not limited to this, A plurality may be provided with respect to one flow path.
Moreover, in the said embodiment, although the outer side rib is provided in the position which overlaps with a flow path in radial direction, it is not limited to this, You may provide in addition to the position which overlaps with an inner side rib in radial direction.

DESCRIPTION OF SYMBOLS 10 Electric motor 11 Shaft 12 Rotor 13 Stator 20 Housing 21 Inner cylinder 22 Outer cylinder 30 Cooling water flow path 31 1st flow path 32 2nd flow path 33 3rd flow path 34 4th flow path 35 Communication path 41 1st inner side rib 42 1st 2 inner rib 43 third inner rib 45 outer rib

Claims (3)

A shaft,
A rotor provided on the shaft;
A stator provided on the outer peripheral side of the rotor;
An electric motor comprising a housing for holding the stator;
The housing is
An inner cylinder holding the stator;
An outer cylinder that is provided on the outer peripheral side of the inner cylinder and forms a cooling water flow path for flowing cooling water between the inner cylinder, and
In the cooling water flow path, a plurality of inner ribs extending in the circumferential direction by connecting the inner cylinder and the outer cylinder in the radial direction are provided side by side in the axial direction,
The cooling water flow path is divided into a plurality of flow paths by the plurality of inner ribs,
An electric motor characterized in that outer ribs that protrude radially outward and extend in the circumferential direction are respectively provided at positions on the outer peripheral surface of the outer cylinder that overlap the plurality of flow paths in the radial direction.   2. The electric motor according to claim 1, wherein the outer rib is provided at a position overlapping with an axial center of each of the plurality of flow paths in a radial direction. The housing is provided with an inlet for allowing cooling water to flow into the cooling water channel, an outlet for allowing cooling water to flow out of the cooling water channel, and an air vent for extracting air from the cooling water,
The cooling water flow path is provided with a plurality of communication paths that communicate the plurality of flow paths in the axial direction.
3. The electric motor according to claim 1, wherein the inflow port, the outflow port, and the air vent port are respectively disposed at positions that overlap with the plurality of communication paths in a circumferential direction.

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