Cooling structure for electric motor

Abstract

To further ensure the cooling performance of a rotor. The cooling structure of the electric motor includes a rotor having a rotor core and a plurality of permanent magnets embedded in the rotor core. Furthermore, the cooling structure of the electric motor includes a plurality of oil paths formed in a manner that they are spaced apart in the circumferential direction of the rotor core and respectively penetrate in the axial direction of the rotor core, and a tubular guide portion provided on one end side or both end sides in the axial direction of the rotor core and guiding cooling oil supplied from the radially inner side to the plurality of oil paths.

Description

Technical Field

[0001] This invention relates to a cooling structure for an electric motor. Background Technology

[0002] A conventional cooling structure for an electric motor has been proposed, comprising: a stator wound with coils; a rotor fixed to a shaft and having multiple stacked steel plates and multiple magnets assembled on the stacked steel plates; multiple cooling flow paths formed axially through the stacked steel plates near the magnets; a supply hole supplying cooling liquid from the oil holes at the center of the shaft to the outer circumferential surface of the shaft; and multiple receiving portions, each spaced apart circumferentially on one side of the rotor along its axial direction (for example, see Patent Document 1). In this structure, the multiple receiving portions are connected to corresponding cooling flow paths, their outer diameter sides are covered, and their inner diameter sides are open to receive cooling medium dissipated from the supply hole. In this electric motor cooling structure, the cooling liquid from the oil holes of the shaft is dissipated from the supply hole due to centrifugal force caused by the rotation of the rotor and is received by the receiving portions and supplied to the cooling flow paths.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-68622 Summary of the Invention

[0004] In the cooling structure of the electric motor described above, if the position of the liquid receiving part is not properly related to the position of the supply hole of the shaft, the cooling liquid may not be fully received by the liquid receiving part, thus failing to achieve sufficient cooling performance of the rotor.

[0005] The main purpose of the cooling structure of the electric motor of the present invention is to further ensure the cooling performance of the rotor.

[0006] To achieve the above-mentioned main objectives, the cooling structure of the electric motor of the present invention adopts the following scheme.

[0007] The cooling structure of the electric motor of the present invention includes a rotor having a rotor core and a plurality of permanent magnets embedded in the rotor core. The main feature of the cooling structure of the electric motor is that it includes:

[0008] Multiple oil passages are formed in a manner that are spaced apart circumferentially in the rotor core and respectively extend through the rotor core axially; and

[0009] A cylindrical guide section is disposed on one or both ends of the rotor core along the axial direction and guides cooling oil supplied from the radially inner side to the plurality of oil passages.

[0010] In the cooling structure of the electric motor of the present invention, multiple oil passages and guide sections are provided. The multiple oil passages are formed such that they are spaced apart circumferentially in the rotor core and each extends through the rotor core axially. The guide sections are provided at one or both ends axially in the rotor core, are cylindrical, and guide cooling oil supplied radially inward to the multiple oil passages. Because the guide sections are cylindrical, cooling oil from the radially inward side can be received more fully and supplied to the multiple oil passages formed in the rotor core. As a result, the rotor can be cooled more fully. That is, the cooling performance of the rotor can be further ensured.

[0011] In the cooling structure of the electric motor of the present invention, the guide portion may include a first wall portion that is cylindrical and extends along the axial direction and a second wall portion that extends radially inward from the end of the first wall portion away from the rotor core. It may also include a wall portion that is cylindrical and whose inner diameter decreases along the axial direction as it moves away from the rotor core.

[0012] In the cooling structure of the electric motor of the present invention, a plurality of guide portions with different inner diameters may be provided.

[0013] In the cooling structure of the electric motor of the present invention, the plurality of oil passages may include holes in which the permanent magnets are disposed. This allows for further cooling of the permanent magnets. Attached Figure Description

[0014] Figure 1 This is a front view of the motor unit according to an embodiment of the present invention.

[0015] Figure 2 It is along Figure 1 A sectional view cut along line AA.

[0016] Figure 3 From Figure 1 The main view of the motor unit has been removed, eliminating the guide section.

[0017] Figure 4 This is a cross-sectional view of a modified motor unit.

[0018] Figure 5 This is a cross-sectional view of a modified motor unit.

[0019] Figure 6 This is a cross-sectional view of a modified motor unit. Detailed Implementation

[0020] The embodiments (implementations) for carrying out the present invention will be described with reference to the accompanying drawings. Figure 1 This is a front view of the motor unit 10 according to an embodiment of the present invention. Figure 2 yes Figure 1 AA sectional view. Figure 3 From Figure 1 The front view of the motor unit 10 without the guide section 30 is shown.

[0021] The electric motor unit 10 of this embodiment is mounted in electric vehicles, hybrid electric vehicles, fuel cell vehicles, etc. The electric motor unit 10 includes: an electric motor 12 configured as a synchronous generator motor; and a guide section 30 for guiding cooling oil for cooling the electric motor 12. The electric motor 12 includes a rotor 20 fixed to a rotor shaft 14 and a stator (not shown) centrally housing the rotor 20.

[0022] The rotor 20 includes a rotor core 22 and multiple permanent magnets 27 and 28. The rotor core 22 is formed by stacking multiple electromagnetic steel plates into a cylindrical shape, resulting in an overall cylindrical structure. The inner circumference of the rotor core 22 is fixed to a rotor shaft 14 inserted into its inner side. The rotor core 22 has multiple through holes 23, 24, and 26. End plates can be arranged on both sides of the rotor core 22 along its axial direction. In this case, the end plates are formed with the same shape as the rotor core 22, matching the positions of the multiple through holes 23, 24, and 26.

[0023] Multiple through holes 23 are formed radially from the central portion to the outer periphery of the rotor core 22, extending axially through the rotor core 22 at predetermined intervals (45° intervals in the embodiment). Each pair of through holes 23 has a first portion 23a and a second portion 23b. The two first portions 23a extend approximately linearly along the circumference of the rotor core 22. The two second portions 23b extend approximately linearly from the ends of the two first portions 23a that are furthest from each other to the outer periphery of the rotor core 22.

[0024] Multiple through holes 24 are formed on the outer periphery of the rotor core 22 in such a way that they penetrate the rotor core 22 axially, and are spaced apart at a predetermined interval (45° interval in the embodiment) in pairs. The pairs of through holes 24 extend in a generally straight line along the circumference of the rotor core 22 between the two pairs of first parts 23a and the two pairs of second parts 23b.

[0025] Multiple through holes 26 are formed on the inner periphery of the rotor core 22 at intervals (45° intervals in the embodiment) in the circumferential direction of the rotor core 22, respectively, in a manner that penetrates the rotor core 22 axially.

[0026] Multiple permanent magnets 27 and 28 are each formed into a generally cuboid shape. Two permanent magnets 27 are inserted into / fixed in multiple through holes 23. One permanent magnet 28 is inserted into / fixed in multiple through holes 24.

[0027] The guide portion 30 is made of resin, for example, and includes a first wall portion 31 and a second wall portion 32. The first wall portion 31 is cylindrical with an inner diameter that is the same as or slightly larger than the outermost diameter (the distance from the axis of the rotor core 22 to the farthest point on the wall surface of the outer diameter side of the through holes 26) of the plurality of through holes 26 of the rotor core 22, and extends axially along the rotor core 22. The end of the first wall portion 31 on the rotor core 22 side is fixed to the rotor 20 by welding, riveting, or the like (e.g., an end plate). The second wall portion 32 extends radially inward from the end of the first wall portion 31 on the side away from the rotor core 22. The guide portion 30 temporarily stores or guides cooling oil supplied from the oil passage 80 provided in the housing of the motor unit 10 or the like to the plurality of through holes 26.

[0028] In this embodiment, cooling oil from oil passage 80 is sprayed axially along rotor core 22 and impacts rotor shaft 14 or rotor 20. Due to their rotation, it moves radially outward, is received by guide portion 30, and guided to multiple through holes 26, where it flows (see reference). Figure 2 (The thick arrow indicates this). Thus, the rotor 20 is cooled. Although the relative positions of the oil passage 80 and the plurality of through holes 26 change successively as the rotor 20 rotates, the guide portion 30, having a cylindrical first wall portion 31, can adequately receive cooling oil from the oil passage 80 and guide it to the plurality of through holes 26. Furthermore, the guide portion 30, having a second wall portion 32 extending radially inward from the end of the first wall portion 31 away from the rotor core 22, can suppress the movement of cooling oil received by the first wall portion 31 towards the outside of the guide portion 30 (the side away from the rotor core 22). As a result, cooling oil from the oil passage 80 can be adequately supplied through the plurality of through holes 26, further adequately cooling the rotor 20. That is, the cooling performance of the rotor 20 can be further ensured.

[0029] In the motor unit 10 (cooling structure of motor 12) of the embodiment described above, a guide portion 30 is provided, which has a cylindrical first wall portion 31 and a second wall portion 32 extending radially inward from the end of the first wall portion 31 away from the rotor core 22. This allows the guide portion 30 to receive sufficient cooling oil from the oil passage 80 and to supply it adequately through the multiple through holes 26, thereby more fully cooling the rotor 20.

[0030] In the above embodiment, the motor unit 10 is provided with cooling oil supplied from the oil passage 80 provided in the housing to the guide section 30, but it is not limited to this. For example, such as Figure 4As shown in the modified example of the motor unit 10B, cooling oil flowing through the oil passage provided in the rotor shaft 14 and the multiple oil passages 80B formed in a manner that are spaced apart in the circumferential direction of the rotor shaft 14 and respectively connected to the inside and outside of the rotor shaft 14 can also be supplied to the guide section 30.

[0031] In the above embodiment, the motor unit 10 is provided with a guide portion 30 for guiding cooling oil to a plurality of through holes 26, but it is not limited to this. For example, instead of this, it may be provided with a guide portion for guiding cooling oil to a plurality of through holes 23 (the gap between the through holes 23 and the permanent magnets 27). In this way, the plurality of permanent magnets 27 can be further cooled. Furthermore, it may also be provided with a guide portion for guiding cooling oil to a plurality of through holes 24 (the gap between the through holes 24 and the permanent magnets 28). In this way, the plurality of permanent magnets 28 can be further cooled.

[0032] In the above embodiments, for Figures 1-3 The motor unit 10 has been described, but is not limited thereto. For example, as Figure 5 As shown in the modified example of the motor unit 10C, in addition to the same hardware structure as the motor unit 10, it may also include a guide section 40. Furthermore, as... Figure 6 As shown in the modified example of the motor unit 10D, in addition to having the same hardware structure as the motor unit 10, it may also include a guide section 50. The following will describe each section in turn.

[0033] right Figure 5 The modified electric motor unit 10C will be described below. The guide section 40 is disposed on the same side as the guide section 30 relative to the rotor core 22. Like the guide section 30, the guide section 40 is made of resin, for example, and has a first wall section 41 and a second wall section 42. The first wall section 41 is cylindrical with an inner diameter that is the same as or slightly larger than the outermost diameter (distance from the axis of the rotor core 22 to the farthest point on the wall surface of the outer diameter side of the through holes 24) of the rotor core 22, and extends axially along the rotor core 22. The end of the first wall section 41 on the rotor core 22 side is fixed to the rotor 20 (e.g., an end plate) by welding, riveting, or the like. The second wall section 42 extends radially inward from the end of the first wall section 41 on the side away from the rotor core 22. The guide section 40 temporarily stores or guides cooling oil from the oil passage 80C provided in the housing of the electric motor unit 10 to the multiple through holes 24. In this modified example, in addition to the cooling oil from oil passage 80 being received by guide 30 and guided to and flowing through multiple through holes 26, the cooling oil from oil passage 80C is received by guide 40 and guided to and flows through multiple through holes 24 (see reference). Figure 6 (Thick arrow). Thus, compared to the above embodiment, it is possible to further cool the multiple permanent magnets 28.

[0034] In the modified motor unit 10C, a guide portion 30 for guiding cooling oil to a plurality of through holes 26 and a guide portion 40 for guiding cooling oil to a plurality of through holes 24 are provided. However, this is not a limitation, as long as at least two of the guide portions for guiding cooling oil to a plurality of through holes 26, guide portions for guiding cooling oil to a plurality of through holes 23, and guide portions for guiding cooling oil to a plurality of through holes 24 are provided on the same side relative to the rotor core 22.

[0035] right Figure 6 The modified motor unit 10D will be described below. The guide portion 50 is positioned opposite to the guide portion 30 relative to the rotor core 22. Like the guide portion 30, the guide portion 50 is made of resin, for example, and includes a first wall portion 51 and a second wall portion 52. The first wall portion 51 is cylindrical with an inner diameter that is the same as or slightly larger than the outermost diameter (distance from the axis of the rotor core 22 to the farthest point on the outer diameter side of the wall of the first portion 23a) of each of the plurality of through holes 23 of the rotor core 22, and extends axially along the rotor core 22. The rotor core 22 side end of the first wall portion 51 is fixed to the rotor 20 (e.g., an end plate) by welding, riveting, or the like. The second wall portion 52 extends radially inward from the end of the first wall portion 51 on the side furthest from the rotor core 22. The guide section 50 temporarily stores or guides cooling oil from the oil passage 80D provided in the housing of the motor unit 10 to the plurality of through holes 23 (part 23a). In this modified example, in addition to the cooling oil from the oil passage 80 being received by the guide section 30 and guided to the plurality of through holes 26 and flowing through the plurality of through holes 26, the cooling oil from the oil passage 80D is received by the guide section 50 and guided to the plurality of through holes 23 and flows through the plurality of through holes 23 (see reference). Figure 5 (The thick arrow). Thus, compared to the above embodiment, it is possible to further cool the multiple permanent magnets 27.

[0036] In the modified motor unit 10D, a guide portion 50 for guiding cooling oil to a plurality of through holes 23 (the gap between the through holes 23 and the permanent magnets 27) is provided on the side opposite to the guide portion 30 relative to the rotor core 22, but this is not a limitation. For example, a guide portion for guiding cooling oil to a plurality of through holes 24 (the gap between the through holes 24 and the permanent magnets 28) may be provided on the side opposite to the guide portion 30 relative to the rotor core 22. In this way, the plurality of permanent magnets 28 can be further cooled.

[0037] In the above embodiment, the guide portion 30 of the motor unit 10 has a cylindrical first wall portion 31 and a second wall portion 32 extending radially inward from the end of the first wall portion 31 away from the rotor core 22, but is not limited thereto. For example, the guide portion may have a cylindrical wall portion with an inner diameter that decreases in size as it moves away from the rotor core 22 along the axial direction of the rotor core 22. Even in this case, it is possible to suppress to some extent the movement of cooling oil received by the guide portion toward the side away from the rotor core 22. The guide portions 40 and 50 of the motor units 10C and 10D can also be replaced in the same way.

[0038] The correspondence between the main elements of the implementation method and the main elements of the invention described in the solution to the problem section is explained. In the implementation method, rotor core 22 corresponds to "rotor core", multiple permanent magnets 27 and 28 correspond to "multiple permanent magnets", rotor 20 corresponds to "rotor", and motor 12 corresponds to "motor". At least a portion of multiple through holes 26, multiple through holes 23, and multiple through holes 24 corresponds to "multiple oil passages", and at least a portion of guide parts 30, 40, and 50 corresponds to "guide parts".

[0039] Furthermore, the correspondence between the main elements of the implementation method and the main elements of the invention described in the "Solution to Solve the Problem" column is merely an example of how the implementation method is used to carry out the invention described in the "Solution to Solve the Problem" column, and therefore does not limit the elements of the invention described in the "Solution to Solve the Problem" column. That is, the interpretation of the invention described in the "Means to Solve the Problem" column should be based on the description in that column; the implementation method is simply a specific example of the invention described in the "Means to Solve the Problem" column.

[0040] The present invention has been described above using embodiments, but the present invention is not limited to such embodiments and can of course be implemented in various ways without departing from the spirit of the present invention.

[0041] This invention can be used in industries such as electric motor manufacturing.

[0042] Symbol Explanation

[0043] 10, 10B, 10D, 10C - Motor unit; 12 - Motor; 14 - Rotor shaft; 20 - Rotor; 22 - Rotor core; 23, 24, 26 - Through hole; 23a - Part 1; 23b - Part 2; 27, 28 - Permanent magnet; 30, 40, 50 - Guide part; 31, 41, 51 - First wall part; 32, 42, 52 - Second wall part; 80, 80B, 80C, 80D - Oil passage.

Claims

1. A cooling structure for an electric motor, comprising a rotor having a rotor core and a plurality of permanent magnets embedded in the rotor core, characterized in that the cooling structure for the electric motor comprises: Multiple oil passages are formed in a manner that are spaced apart circumferentially in the rotor core and respectively extend through the rotor core axially; and A cylindrical guide section is disposed on one or both ends of the rotor core along the axial direction and guides cooling oil supplied from the radially inner side to the plurality of oil passages.

2. The cooling structure for the electric motor according to claim 1, characterized in that, The guide portion includes a first wall portion that is cylindrical and extends along the axial direction and a second wall portion that extends radially inward from the end of the first wall portion away from the rotor core, or it includes a wall portion that is cylindrical and whose inner diameter decreases along the axial direction as it moves away from the rotor core.

3. The cooling structure for the electric motor according to claim 1 or 2, characterized in that, have: Multiple guide sections with different inner diameters.

4. The cooling structure for the electric motor according to claim 1 or 2, characterized in that, The plurality of oil passages include holes in which the permanent magnets are disposed.

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