CN107492969B

CN107492969B - Electric motor

Info

Publication number: CN107492969B
Application number: CN201610407524.1A
Authority: CN
Inventors: 邓实; 朱涛; A·博龙卡
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2016-06-12
Filing date: 2016-06-12
Publication date: 2021-01-26
Anticipated expiration: 2036-06-12
Also published as: CN107492969A

Abstract

The present invention relates to a motor including a housing defining an internal space of the motor, the housing having an airflow incident side on which a cooling airflow is incident and an airflow exit side from which the cooling airflow exits; characterized in that the motor further comprises at least one baffle assembly arranged at the air flow exit side of the housing for guiding a cooling air flow to flow close to the housing surface at the air flow exit side. According to the present invention, the heat dissipation effect of the motor can be significantly improved.

Description

Electric motor

Technical Field

The present invention relates to electric motors, and more particularly to cooling of electric motors.

Background

As the power of the electric motor used in electric vehicles such as electric motorcycles, electric bicycles, and electric automobiles increases, it becomes more and more important to efficiently cool the electric motor. For motors mounted in close proximity to the wheels of an electric vehicle, passive airflow cooling is typically employed for such motors, since the airflow around the motor may flow relative to the motor during vehicle operation. For this reason, annular heat-radiating fins extending from a motor housing, which is a heat transfer surface of the motor, are generally provided on the motor housing, and have a good improvement effect on forced convection cooling performed when an air flow passes over the motor housing during running of the vehicle, and natural convection cooling performed when the air flow is stationary with respect to the motor housing during stopping of the vehicle.

However, during forced convection cooling performed when the air flow flows relative to the motor case, the motor case acts as a barrier to the flow of the air flow, so that the air flow generates a boundary layer near the surface of the motor case. When the reynolds number is too high, for example above 5, the boundary layer air flow may generate vortices and thus separate with respect to the motor housing surface. The separation of the boundary layer air flow from the motor case surface may result in a reduction in heat transfer efficiency at localized locations of the motor case surface, thereby adversely affecting the cooling of the entire motor.

Accordingly, there is a need for improvements to existing electric motors for electric vehicles.

Disclosure of Invention

The object of the present invention is to overcome at least one of the above-mentioned drawbacks of the prior art and to provide an improved electric motor for electric vehicles, which is capable of avoiding or causing separation of boundary layer air flow relative to the motor housing surface at a position further away from the motor housing, so as to achieve sufficient heat exchange of cooling air flow with the motor housing, thereby improving cooling efficiency.

To this end, according to an aspect of the present invention, there is provided an electric motor including:

a housing defining an interior space of the motor, the housing having an airflow incident side on which a cooling airflow is incident and an airflow exit side from which the cooling airflow exits;

characterized in that the motor further comprises at least one baffle assembly arranged at the air flow exit side of the housing for guiding a cooling air flow to flow close to the housing surface at the air flow exit side.

According to the invention, through at least one flow guide plate component arranged on the air flow leaving side of the shell, cooling air flows are blown to the shell from the air flow incidence side of the motor shell to pass through the area, possibly separated from the surface of the shell, of the highest point and the lowest point on the shell, and then the cooling air flows are guided by the flow guide plate to continuously flow close to the surface of the shell part on the air flow leaving side, so that the shell part on the air flow leaving side can be subjected to heat exchange with the cooling air fully, the heat dissipation efficiency of the shell part on the air flow leaving side is improved, and the heat dissipation effect of the whole motor is improved remarkably.

Drawings

Fig. 1 is a perspective view of a motor according to a preferred embodiment of the present invention;

FIG. 2 is a schematic view of a baffle assembly according to a preferred embodiment of the present invention; and

fig. 3 is a side view of a motor according to a preferred embodiment of the present invention, schematically showing the flow path of the air flow.

Detailed Description

Preferred embodiments of the present invention are described in detail below with reference to examples. It will be understood by those skilled in the art that these exemplary embodiments are not meant to limit the invention in any way.

Fig. 1 is a perspective view of a motor according to a preferred embodiment of the present invention. As shown in fig. 1, a motor 1 according to a preferred embodiment of the present invention includes a housing 3 defining a motor internal space, a stator (not visible in the drawing) fixedly disposed in the motor internal space, a rotor rotatably disposed at the center of the stator and including a rotor core and a rotating shaft 5, and end caps 7 (only one end cap is visible in the drawing) at both ends of the housing 3. For an electric motor used in an electric vehicle such as an electric motorcycle, an electric bicycle, and an electric automobile, a plurality of annular heat radiating fins 9 extending along the circumferential direction of the housing are generally provided on the outer surface of the housing 3 as a heat transfer surface of the electric motor, and such annular heat radiating fins 9 not only increase the heat radiating area of the electric motor but also contribute to guiding an air flow to flow over from the outer surface of the housing 3 by means of air flow channels 11 defined between adjacent annular heat radiating fins 9.

The relative movement between the airflow and the motor mounted on the vehicle when the vehicle is running causes the airflow to be incident on the motor from one side of the motor housing (i.e., the side of the motor housing facing in the direction of travel or the windward side) and to exit the motor from the other side of the motor (i.e., the side of the motor housing facing away from the direction of travel or the leeward side), and therefore, an airflow incident side 3a and an airflow exit side 3b opposite to the airflow incident side 3a are present on the motor housing 3. According to the invention, at least one baffle arrangement 13 is arranged on the air flow leaving side 3b of the housing 3 for guiding the cooling air flow close to the housing surface of the air flow leaving side 3 b. Fig. 2 is a schematic view of a baffle according to a preferred embodiment of the invention. As shown in fig. 1 and 2, the baffle assembly 13 comprises an elongated baffle 15 extending in the longitudinal direction of the housing 3 and a bracket 17 for mounting the baffle 15 to the housing 3. The surface 15a of the baffle 15 opposite the housing 3 of the motor is streamlined, preferably curved, to define an airflow directing channel 19 between the housing 3 of the motor and the baffle 15 when the baffle assembly 13 is mounted to the housing 3. The bracket 17 is connected at one end to the housing 3 or the annular fin 9, for example by means of a known connection such as welding or screwing, and the other end of the bracket 17 is adjustably connected to the air deflector 15, for example by means of a pin 21. In this way, in use, a user can adjust the shape of the airflow directing passage 19, and thus the orientation of the airflow relative to the housing 3, by manually actuating the baffle 15 to change the orientation of the baffle 15 relative to the housing 3.

Although it is possible to provide the baffle assembly 13 only in the upper half or the lower half of the airflow exit side 3b of the casing 3, it is preferable to provide the baffle assembly 13 symmetrically in the upper half and the lower half of the airflow exit side 3b of the casing 3. Further, in the preferred embodiment in the drawing, two baffle assemblies 13 are provided on each of the upper and lower halves of the airflow exit side 3b of the casing 3 along the circumferential direction of the casing, but one or more than two baffle assemblies 13 may be provided on each of the upper and lower halves of the airflow exit side 3b of the casing 3 as needed depending on the size of the casing 3 of the motor and the baffle 15.

Fig. 3 is a side view of a motor according to a preferred embodiment of the present invention, schematically showing the flow path of the air flow. The course of the air flow in the upper half of the housing 3 relative to the housing 3 of the electric motor is schematically shown in fig. 3 by arrow lines, wherein the dashed arrow line a represents the course of the air flow relative to the housing 3 of the electric motor without the guide plate assembly 13 according to the invention being installed and the solid arrow line B represents the course of the air flow relative to the housing 3 of the electric motor after the guide plate assembly 13 according to the invention being installed. As shown in fig. 3, without the baffle assembly 13 according to the present invention installed, the air flow is blown from the air flow incident side 3a of the motor housing onto the housing 3 when the vehicle is running to cause the air flow to move relative to the motor, and immediately after passing through the vicinity of the highest point and the lowest point on the housing 3, the air flow is separated from the housing portion of the air flow leaving side 3b, so that the housing portion of the air flow leaving side 3b cannot sufficiently exchange heat with the cooling air flow, resulting in deterioration of the heat radiation effect of the housing portion of the air flow leaving side 3 b. In contrast to the foregoing, in the case where the baffle assembly 13 according to the present invention is installed, when the vehicle is driven to cause the airflow to move relative to the motor, the airflow is blown onto the housing 3 from the airflow incident side 3a of the motor housing, and after passing near the highest point and the lowest point on the housing 3, the airflow continues to flow close to the surface of the housing portion of the airflow exit side 3b under the guidance of the baffle 15, so that the housing portion of the airflow exit side 3b can sufficiently exchange heat with the cooling airflow, the heat radiation efficiency of the housing portion of the airflow exit side 3b is improved, and the heat radiation effect of the entire motor is remarkably improved.

The present invention has been described in detail with reference to the specific embodiments. It is to be understood that both the foregoing description and the embodiments shown in the drawings are to be considered exemplary and not restrictive of the invention. Furthermore, although the preferred embodiment above is described in connection with an electric motor mounted to an electric vehicle, it will be understood that the principles of the present invention are applicable to all electric motors whose housing employs forced convection cooling, such as where the motor itself is not moving, but a fan is employed to deliver forced cooling airflow to the motor. In addition, the present invention is also applicable to a case where the outer surface of the motor case is not provided with the annular heat radiation fins. It will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit of the invention, and these changes and modifications do not depart from the scope of the invention.

Claims

1. An electric motor for an electric vehicle, the electric motor (1) comprising:

a housing (3) that defines an internal space of the electric motor (1), relative movement between an air flow and the electric motor (1) when the electric vehicle is running being such that the housing (3) has an air flow incident side (3a) on which a cooling air flow is incident and an air flow exit side (3b) from which the cooling air flow exits and which is opposite to the air flow incident side (3 a);

characterized in that the electric motor (1) further comprises at least one baffle assembly (13) arranged at the air flow exit side (3b) of the housing (3) for guiding a cooling air flow to flow close to the housing surface of the air flow exit side (3 b).

2. The electric motor according to claim 1, characterized in that at least one baffle assembly (13) is symmetrically arranged in the upper and lower halves of the air flow exit side (3b) of the housing (3).

3. The electric motor according to claim 2, characterized in that two baffle assemblies (13) are provided symmetrically along the circumferential direction of the housing, respectively, in the upper half and the lower half of the airflow exit side (3b) of the housing (3).

4. An electric motor according to claim 1, characterized in that the baffle assembly (13) comprises an elongated baffle (15) extending in the longitudinal direction of the housing (3) and a bracket (17) for mounting the baffle (15) to the housing (3).

5. An electric motor according to claim 4, characterized in that the surface (15a) of the deflector (15) opposite the housing (3) is streamlined so as to define an air flow guiding channel (19) between the housing (3) and the deflector (15).

6. An electric motor according to claim 4, characterized in that the bracket (17) is connected to the housing (3) at one end and the bracket (17) is connected to the deflector (15) at the other end.

7. An electric motor according to claim 6, characterized in that the air deflector (15) and the bracket (17) are adjustably interconnected.

8. The electric motor according to claim 1, characterized in that the electric motor (1) further comprises a plurality of annular heat-radiating fins (9) provided on an outer surface of the housing (3) and extending along a circumferential direction of the housing (3), with air flow channels (11) defined between adjacent annular heat-radiating fins (9).

9. The motor according to claim 1, further comprising a stator fixedly disposed in the inner space, a rotor rotatably disposed in the center of the stator and including a rotor core and a rotating shaft (5), and end caps (7) at both ends of the housing (3).

10. The electric motor of claim 1, wherein the electric vehicle is an electric motorcycle, an electric bicycle, or an electric automobile.