In-wheel motor cooling structure

Abstract

To provide a cooling structure of an in-wheel motor capable of improving the cooling performance.SOLUTION: A disclosed cooling structure of an in-wheel motor is a cooling structure of an in-wheel motor placed in a wheel of a vehicle. The cooling structure includes: a rotary electric machine that rotates a hub where the wheel is fixed; and a knuckle provided in contact with a stator of the rotary electric machine for rotatably supporting the hub. One or more cooling fins extending in the axial direction of the wheel are provided on the knuckle.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a cooling structure for an in-wheel motor. [Background technology]

[0002] Patent Document 1 discloses a technology for a cooling device for an in-wheel motor, in which motor heat dissipation fins are arranged on the outer periphery of a housing to which a stator is fixed, below the in-wheel motor, and an air-cooling fan is provided outside the in-wheel motor to air-cool the motor heat dissipation fins. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-148272 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technique disclosed in Patent Document 1 leaves room for improvement in terms of cooling performance.

[0005] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a cooling structure for an in-wheel motor that can improve cooling performance. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the cooling structure for an in-wheel motor of the present invention is a cooling structure for an in-wheel motor provided within the wheel of a vehicle, comprising a rotating electric machine that rotates a hub to which the wheel is fixed, and a knuckle that rotatably supports the hub and is provided in contact with a stator of the rotating electric machine, and is characterized in that the knuckle is provided with one or more cooling fins extending in the axial direction of the wheel.

[0007] This allows cooling fins to be provided on the knuckle, to which heat is transferred from the stator of the rotating electrical machine, taking into consideration the direction of air flow within the wheel, thereby improving cooling performance.

[0008] In the above, the cooling fins may be disposed on a circumferential side surface of a leg portion of the knuckle on a vehicle rear side.

[0009] This allows the cooling fins to be placed in areas where the wind speed is high, improving the cooling performance.

[0010] In the above, the cooling fins may be disposed only on the vehicle rear side of the knuckle.

[0011] This makes it possible to reduce the number of cooling fins, thereby reducing costs, while efficiently improving cooling performance. Effect of the Invention

[0012] The cooling device for an in-wheel motor according to the present invention has cooling fins on the knuckle to which heat is transferred from the stator of the rotating electric machine, taking into consideration the direction of air flow within the wheel, thereby achieving the effect of improving cooling performance. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic configuration of an in-wheel motor according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing the flow of wind around a wheel equipped with an in-wheel motor while the vehicle is running. [Diagram 3] FIG. 3 is a diagram of an in-wheel motor in which cooling fins are arranged on legs located on the vehicle rear side of the knuckle, as viewed from the inside in the axial direction. [Figure 4] FIG. 4 is a perspective view of a knuckle having cooling fins disposed on a leg portion located on the rear side of the vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a cooling structure for an in-wheel motor according to the present invention will be described. However, the present invention is not limited to the embodiment.

[0015] FIG. 1 is a cross-sectional view showing a schematic configuration of an in-wheel motor 1 according to an embodiment. The in-wheel motor 1 according to the embodiment has a stator 11 and a rotor 12, and is provided inside a wheel of a vehicle. The stator 11 has a stator core 111, a stator coil 112, and a stator spindle 113. Stator coils 112 are arranged at equal intervals around the stator 11, which is substantially ring-shaped. The stator coil 112 can generate a rotating magnetic field at a predetermined speed by receiving power supply from a battery. The stator spindle 113 is fixed by a bolt 14 to a knuckle 13 fixed to a suspension arm. The knuckle 13 rotatably supports a hub 16 via a hub bearing 15 in which a plurality of balls are arranged between an outer race (outer ring) 151 and an inner race (inner ring) 152.

[0016] A rotor 12 having a rim portion 121 and a disk portion 122 is rotatably arranged on the outside of the stator 11 at a predetermined interval from the stator 11. In the in-wheel motor 1 according to the embodiment, the rotor 12 has the rim portion 121 and the disk portion 122 as components constituting the wheel of the wheel. The rim portion 121 is located on the radial outside of the stator 11. The disk portion 122 is located on the outside in the axial direction of the stator 11. In this embodiment, the "axial direction" refers to the direction in which the axis AX of the axle 18, which will be described later, extends, unless otherwise specified. A magnet 123 such as a permanent magnet is arranged on the inner periphery side of the rim portion 121 so as to face the stator core 111 of the stator 11, and the rotor 12 rotates relative to the stator 11 as the rotating magnetic field moves. The rotor 12 is fixed to the hub 16 by the hub bolts 17, so that the wheel can be rotated at a predetermined speed by the rotation of the rotor 12.

[0017] The axle 18 corresponds to the rotation shaft of the wheel on which the in-wheel motor 1 is mounted, is rotatable around the axis line AX, and has its end on the outer side of the vehicle fixed to the hub 16 by a locking ring 19.

[0018] The mechanical pump 20 is, for example, an oil pump that pumps a coolant (oil) as a refrigerant, and an inner race 201, which is a fixed part constituting the pump 20, is attached to the outer race 151 of the hub bearing 15, and an outer race 202, which is a rotating part constituting the pump 20, is attached to the hub 16. Then, the outer race 202 rotates in conjunction with the rotation of the hub 16, and the pump 20 is driven by the rotation difference between the inner race 201 and the outer race 202. Note that an electric pump may be used instead of the mechanical pump 20. In this case, the electric pump may be provided on the outer race 151 of the hub bearing 15.

[0019] A first cooling flow passage 114 and a second cooling flow passage 115, which are flow passages through which a coolant flows and extend in the circumferential direction of the stator 11, are provided side by side in the axial direction inside the stator core 111. The first cooling flow passage 114 and the second cooling flow passage 115 are partially in communication with each other inside the stator core 111.

[0020] An outward flow path 131 and a return flow path 132, which are a plurality of flow paths for circulating the coolant between the first cooling flow path 114 and the second cooling flow path 115 in the stator core 111 and the pump 20, are provided in the inside of the knuckle 13 and the inside of the stator 11 (stator core 111 and stator spindle 113) so as to communicate with each other. The connection portions between the knuckle 13 and the stator 11 (stator spindle 113) in the outward flow path 131 and the return flow path 132 are located at positions where no bolts 14 fastening the knuckle 13 and the stator spindle 113 are present in the circumferential direction of the stator 11. In addition, gaskets (not shown) are inserted in the connection portions between the knuckle 13 and the stator 11 (stator spindle 113) in the outward flow path 131 and the return flow path 132 to ensure sealing at the connection portions.

[0021] An inflow end of the outflow passage 131 communicates with a discharge port of the pump 20, and an outflow end of the outflow passage 131 communicates with a first cooling passage 114 in the stator core 111. Moreover, an inflow end of the return passage 132 communicates with a second cooling passage 115 in the stator core 111, and an outflow end of the return passage 132 communicates with an inlet of the pump 20.

[0022] Note that, taking into consideration strength and the like, the knuckle 13 may be enlarged as necessary and provided with internal passages for flowing the coolant, such as the forward passage 131 and the return passage 132. As a method for providing the forward passage 131 and the return passage 132 in the knuckle 13, for example, grooves corresponding to the forward passage 131 and the return passage 132 may be dug in the wall surface of the knuckle 13 by drilling or the like, and then the grooves may be covered with a lid member, or a core may be provided in the portions corresponding to the forward passage 131 and the return passage 132 when the knuckle 13 is produced by casting.

[0023] In the in-wheel motor 1 according to the embodiment, when the pump 20 is driven in response to the rotation of the hub 16, the coolant discharged from the pump 20 flows through the forward flow path 131, the first cooling flow path 114, the second cooling flow path 115, and the return flow path 132 in that order, as shown in FIG. 1, and then circulates back to the pump 20.

[0024] In the in-wheel motor 1 according to the embodiment, the coolant is circulated by the pump 20, and the coolant flowing through the first cooling flow passage 114 and the second cooling flow passage 115 removes heat from the stator core 111, thereby cooling the stator core 111 and the stator 11. In addition, the coolant that has received heat from the stator core 111 flows out from the second cooling flow passage 115 to the return flow passage 132, flows through the return flow passage 132, the pump 20, and the outward flow passage 131 in this order, and during the time until it flows back into the first cooling flow passage 114, the heat of the coolant is transmitted to the knuckle 13 in the outward flow passage 131 and the return flow passage 132, and is dissipated to the air flowing around the knuckle 13.

[0025] In this way, in the in-wheel motor 1 of the embodiment, by driving the pump 20 in conjunction with the rotation of the hub 16, the coolant is circulated between the first cooling passage 114 and the second cooling passage 115 and the pump 20 via the forward flow path 131 and the return flow path 132, thereby lowering the temperature of the coolant while it flows through the forward flow path 131 and the return flow path 132, and the stator core 111 and ultimately the stator 11 can be cooled by the coolant.

[0026] In the in-wheel motor 1 according to the embodiment, the stator 11 (stator spindle 113) and the knuckle 13 are in contact with each other, so that heat from the stator 11 is transmitted to the knuckle 13. The heat transmitted to the knuckle 13 in this manner is then dissipated to the air flowing around the knuckle 13.

[0027] As shown in FIG. 2, while the vehicle is traveling, wind flows inside the wheel of the wheel 100 on which the in-wheel motor 1 is mounted from the inside to the outside in the axial direction, and the wind speed increases toward the rear of the vehicle.

[0028] Therefore, in the cooling structure of the in-wheel motor 1 according to the embodiment, one or more cooling fins 30 extending in the axial direction are provided on the leg 130 of the knuckle 13 so as to follow the wind flow in consideration of the wind flow direction in the wheel, as shown in Fig. 3 and Fig. 4. Specifically, in the cooling structure of the in-wheel motor 1 according to the embodiment, a plurality of (eight) cooling fins 30 are arranged on the circumferential side surface of the leg 130 located on the vehicle rear side of the knuckle 13 so as to extend in the axial direction, taking into consideration a portion 40 in the wheel where the wind speed is high while the vehicle is traveling. As a result, in the cooling structure of the in-wheel motor 1 according to the embodiment, heat from the knuckle 13 can be efficiently dissipated from the cooling fins 30, and the cooling performance of the knuckle 13 and therefore the cooling performance of the stator 11 can be improved compared to a case where the cooling fins 30 are not provided on the knuckle 13.

[0029] The location of the cooling fins 30 on the knuckle 13 is not limited to the vehicle rear side of the knuckle 13, and may be other locations on the knuckle 13, as long as the cooling fins 30 are provided on the knuckle 13 so as to extend in the axial direction along the flow of air, taking into consideration the direction of air flow in the wheel while the vehicle is running. For example, the cooling fins 30 may be arranged to extend in the axial direction on the circumferential side of the leg 130 located on the vehicle front side of the knuckle 13. On the other hand, by arranging the cooling fins 30 only on the vehicle rear side of the knuckle 13, the number of cooling fins 30 can be reduced to reduce costs, while efficiently improving cooling performance. [Explanation of symbols]

[0030] 1 In-wheel motor 11 Stator 12 Rotor 13 Knuckle 14 Volts 15 Hub bearing 16 Hub 17 Hub bolt 18 Axles 19 Locking ring 20 Pump 111 Stator core 112 Stator coil 113 Status Spindle 114 First cooling channel 115 Second cooling channel 121 Rim section 122 Disk section 123 Magnet 130 Legs 131 Outward Flow Path 132 Return flow path 151 Outer Race 152 Inner Race 201 Inner Race 202 Outer Race

Claims

1. A cooling structure for an in-wheel motor provided inside a wheel of a vehicle, comprising: a rotating electric machine that rotates a hub to which the wheel is fixed; a knuckle that rotatably supports the hub and is provided in contact with a stator of the rotating electric machine; Equipped with One or more cooling fins extending in the axial direction of the wheel are provided on the knuckle, a cooling fin disposed on a circumferential side surface of a leg portion of the knuckle on a vehicle rear side,

2. A cooling structure for an in-wheel motor provided within a wheel of a vehicle, comprising: a rotating electric machine that rotates a hub to which the wheel is fixed; a knuckle that rotatably supports the hub and is provided in contact with a stator of the rotating electric machine; Equipped with One or more cooling fins extending in the axial direction of the wheel are provided on the knuckle, 13. A cooling structure for an in-wheel motor, comprising: a cooling fin disposed only on a vehicle rear side of the knuckle.

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