US-12620862-B2 - Cooling structure of in-wheel motor

Abstract

A cooling structure of an in-wheel motor includes a rotary electric machine and a knuckle. The rotary electric machine is configured to rotate a hub to which a wheel is fixed. The knuckle rotatably supports the hub and is provided in contact with a stator of the rotary electric machine. Here, the knuckle is provided with one or more cooling fins extending in the axial direction of the tire-wheel assembly.

Inventors

• Hideaki Miyazono

Assignees

• TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date

20260505

Application Date

20230222

Priority Date

20220406

Claims (10)

1. 1 . A cooling structure of an in-wheel motor, the cooling structure being provided in a wheel of a tire-wheel assembly, the cooling structure comprising: a rotary electric machine configured to rotate a hub to which the wheel is fixed; and a knuckle that supports the hub so as to be rotatable and that is provided in contact with a stator of the rotary electric machine, wherein the knuckle is provided with one or more cooling fins extending in an axial direction of the tire-wheel assembly, wherein the one or more cooling fins is disposed on a side surface in a circumferential direction of a leg portion on a vehicle rear side of the knuckle.
2. 2 . A cooling structure of an in-wheel motor, the cooling structure being provided in a wheel of a tire-wheel assembly, the cooling structure comprising: a rotary electric machine configured to rotate a hub to which the wheel is fixed; and a knuckle that supports the hub so as to be rotatable and that is provided in contact with a stator of the rotary electric machine, wherein the knuckle is provided with one or more cooling fins extending in an axial direction of the tire-wheel assembly, wherein the one or more cooling fins is disposed only on a vehicle rear side of the knuckle.
3. 3 . The cooling structure according to claim 1 , wherein an inside of the knuckle and an inside of the stator are provided with a forward flow path and a return flow path for circulating a cooling liquid, and the forward flow path and the return flow path are connected to a pump that is driven as the hub rotates.
4. 4 . The cooling structure according to claim 2 , wherein an inside of the knuckle and an inside of the stator are provided with a forward flow path and a return flow path for circulating a cooling liquid, and the forward flow path and the return flow path are connected to a pump that is driven as the hub rotates.
5. 5 . The cooling structure according to claim 1 , wherein the side surface in the circumferential direction of the leg portion includes a first side surface and a second side surface that is opposite from the first side surface and in the circumferential direction of the leg portion, and the one or more cooling fins extend from each of the first side surface and the second side surface of the leg portion.
6. 6 . The cooling structure according to claim 2 , wherein the one or more cooling fins is disposed on a side surface in a circumferential direction of a leg portion of the knuckle.
7. 7 . The cooling structure according to claim 1 , wherein the vehicle rear side of the knuckle is located rearward of a rotary shaft of the wheel on which the in-wheel motor is mounted.
8. 8 . The cooling structure according to claim 2 , wherein the vehicle rear side of the knuckle is located rearward of a rotary shaft of the wheel on which the in-wheel motor is mounted.
9. 9 . The cooling structure according to claim 1 , wherein the leg portion of the knuckle further includes an exterior facing surface and an interior facing surface, and the side surface in the circumferential direction of the leg portion extends from the exterior facing surface to the interior facing surface.
10. 10 . The cooling structure according to claim 6 , wherein the leg portion of the knuckle further includes an exterior facing surface and an interior facing surface, and the side surface in the circumferential direction of the leg portion extends from an edge of the exterior facing surface to an edge of the interior facing surface.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Japanese Patent Application No. 2022-063625 filed on Apr. 6, 2022, incorporated herein by reference in its entirety. BACKGROUND 1. Technical Field The present disclosure relates to a cooling structure of an in-wheel motor. 2. Description of Related Art Japanese Unexamined Patent Application Publication No. 2010-148272 (JP 2010-148272 A) discloses a technology that is a cooling device of an in-wheel motor, in which a motor heat dissipation fin is disposed at a position that is an outer peripheral portion of a housing to which a stator is fixed and that is a lower portion of the in-wheel motor, and in which a cooling fan is provided outside the in-wheel motor to cool the motor heat dissipation fin. SUMMARY However, in the technology disclosed in JP 2010-148272 A, there is room for improvement in the cooling performance. The present disclosure has been made in view of the above problems, and an object thereof is to provide a cooling structure of an in-wheel motor capable of improving the cooling performance. A cooling structure of an in-wheel motor according to a first aspect of the present disclosure is a cooling structure of an in-wheel motor provided in a wheel of a tire-wheel assembly. The cooling structure of the in-wheel motor includes: a rotary electric machine configured to rotate a hub to which the wheel is fixed; and a knuckle that supports the hub so as to be rotatable and that is provided in contact with a stator of the rotary electric machine. Here, the knuckle is provided with one or more cooling fins extending in an axial direction of the tire-wheel assembly. According to such a configuration, the cooling fin is provided in the knuckle to which heat is transferred from the stator of the rotary electric machine in consideration of a flow direction of wind in the wheel. Therefore, the cooling performance of the in-wheel motor can be improved. In the cooling structure according to the first aspect, the cooling fin may be disposed on a side surface in a circumferential direction of a leg portion on a vehicle rear side of the knuckle. According to such a configuration, it is possible to improve the cooling performance by disposing the cooling fin in a portion having a high wind speed. In the cooling structure according to the first aspect, the cooling fin may be disposed only on a vehicle rear side of the knuckle. According to such a configuration, it is possible to efficiently improve the cooling performance while achieving cost reduction by reducing the number of cooling fins. A cooling device of an in-wheel motor according to the present disclosure has an effect of the improving cooling performance by providing a cooling fin in a knuckle to which heat is transferred from a stator of a rotary electric machine, in consideration of a flow direction of wind in a wheel. BRIEF DESCRIPTION OF THE DRAWINGS Features, advantages, and technical and industrial significance of exemplary embodiments of the present disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: FIG. 1 is a cross-sectional view illustrating a schematic configuration of an in-wheel motor according to an embodiment; FIG. 2 is a view showing a flow of wind around a tire-wheel assembly on which an in-wheel motor is mounted during vehicle running; FIG. 3 is a view of an in-wheel motor in which cooling fins are arranged on a leg portion located on a vehicle rear side of a knuckle as viewed from the inside in an axial direction; FIG. 4 is a perspective view of a knuckle in which a cooling fin is disposed on a leg portion located on a vehicle rear side. DETAILED DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a cooling structure of an in-wheel motor according to the present disclosure will be described. This embodiment is not intended to limit the present disclosure. FIG. 1 is a cross-sectional view illustrating a schematic configuration of an in-wheel motor 1 according to an embodiment. The in-wheel motor 1 according to the embodiment includes a stator 11 and a rotor 12. The in-wheel motor 1 is provided in a wheel of a tire-wheel assembly. The stator 11 includes a stator core 111, a stator coil 112, and a stator spindle 113. Further, the stator coils 112 are arranged at equal intervals around the stator 11 having a substantially ring shape. The stator coil 112 can generate a rotating magnetic field at a predetermined speed by receiving electric power from a battery. The stator spindle 113 is fixed to a knuckle 13 fixed to the suspension arm by a bolt 14. The knuckle 13 rotatably supports the hub 16 via a hub bearing 15 in which a plurality of balls are disposed between the outer race (outer ring) 151 and the inner race (inner ring) 152. A rotor 12 having a rim portion 121 and a disk portion 122 is disposed outside the stator 11. The rotor 12 is rotatably disposed at a predetermined in