Drive device

Abstract

This drive device comprises: a motor (12) having a rotor (30) that rotates about a rotation center axis extending in a prescribed axial direction, and a stator (40) that is disposed inside the rotor in a radial direction orthogonal to the axial direction; and a brake sliding part (50) having an annular shape in a circumferential direction extending circumferentially around the rotation center axis, the brake sliding part being pressed by a friction member. The rotor includes: a cylindrical carrier part (31); a magnet part (32) provided to the inner peripheral surface of the carrier part; an intermediate attachment part (60) having an annular form in a circumferential direction, the intermediate attachment part being provided to an axial-directional end part of the carrier part, and having the brake sliding part attached thereto; and fins (80-85) provided to at least one of the outer surfaces of the carrier part and the intermediate attachment part, the fins protruding from the at least one outer surface.

Description

Drive unit CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2023-147146, filed on September 11, 2023, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a drive device.

[0003] Conventionally, drive devices equipped with a motor have been known. The motor is housed in a casing. The casing has heat dissipation fins on its outer periphery. This prevents the temperature of the motor from rising. An example of such a technology is disclosed in Patent Document 1.

[0004] JP 2011-79484 A

[0005] A known motor is an outer rotor type motor that has a rotor and a stator disposed radially inside the rotor. The rotor has a cylindrical carrier and a magnet disposed on the inner circumferential surface of the carrier.

[0006] In some cases, the rotor is fitted with a brake sliding part of a braking device that brakes the rotor. In this case, there is a concern that heat generated in the brake sliding part will be transferred to the magnet part, reducing the magnetic flux density of the magnet part.

[0007] For example, in a configuration in which fins are provided on the casing that houses the motor, there is a concern that the heat generated in the brake sliding part will be transferred to the magnet part due to the heat not being effectively dissipated from the brake sliding part as a heat source.

[0008] The present disclosure has been made in consideration of the above circumstances, and its main object is to provide a drive device that can suppress heat transfer from a brake sliding portion to a magnet portion of a rotor.

[0009] The present disclosure provides a drive device including: a motor having a rotor that rotates around a central axis of rotation extending in a predetermined axial direction, and a stator that is arranged inside the rotor in a radial direction perpendicular to the axial direction; and a brake sliding portion that is annular in a circumferential direction extending circumferentially around the central axis of rotation and against which a friction member is pressed, wherein the rotor has: a cylindrical carrier portion; a magnet portion provided on an inner peripheral surface of the carrier portion; an intermediate mounting portion that is annular in the circumferential direction and is provided at an end of the carrier portion in the axial direction, to which the brake sliding portion is attached; and a fin that is provided on an outer surface of at least one of the carrier portion and the intermediate mounting portion and protrudes from the outer surface.

[0010] The brake sliding part is attached to an intermediate mounting part of the rotor. The intermediate mounting part is annular in the circumferential direction and is provided at the axial end of the carrier part of the rotor. A magnet part is provided on the inner circumferential surface of the carrier part. In this case, there is a concern that heat generated in the brake sliding part will be transferred to the magnet part via the intermediate mounting part and the carrier part.

[0011] Therefore, in the present disclosure, the rotor has fins. The fins are provided on the outer surface of at least one of the carrier portion and the intermediate mounting portion. The carrier portion and the intermediate mounting portion are arranged between the brake sliding portion and the magnet portion, and form a heat transfer path for transferring heat from the brake sliding portion, which is a heat source. In a configuration in which fins protruding from the outer surfaces of the carrier portion and the intermediate mounting portion, which form the heat transfer path, are provided, the surface area of ​​the heat transfer path is increased. This promotes heat dissipation in the heat transfer path. Therefore, heat transfer from the brake sliding portion to the magnet portion can be suppressed.

[0012] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a longitudinal cross-sectional view of a wheel unit according to a first embodiment, Fig. 2 is a perspective view of a carrier portion and fins, Fig. 3 is a circumferentially expanded view of an expanded diameter portion according to a second embodiment, Fig. 4 is a circumferentially expanded view of an expanded diameter portion according to a modification of the second embodiment, Fig. 6 is a circumferentially expanded view of an expanded diameter portion according to a third embodiment, Fig. 7 is a longitudinal cross-sectional view of a wheel unit according to a fourth embodiment, Fig. 8 is a longitudinal cross-sectional view of a wheel unit according to a modification of the fourth embodiment, and Fig. 9 is a circumferentially expanded view of a cross section of an expanded diameter portion and a wheel according to a fifth embodiment.

[0013] Several embodiments will be described with reference to the drawings. In several embodiments, functionally and / or structurally corresponding and / or associated parts may be designated by the same reference numerals or reference numerals that differ in the hundredth or more digit. For corresponding and / or associated parts, reference may be made to the descriptions of other embodiments.

[0014] First Embodiment Hereinafter, a first embodiment in which a drive device according to the present disclosure is embodied as a wheel unit will be described. The wheel unit is used as a drive wheel in a vehicle such as a four-wheeled vehicle or a two-wheeled vehicle, and includes a wheel to which a tire is attached and a motor (in-wheel motor) housed in a space inside the wheel. The wheel unit of this embodiment is applied to an electrically powered vehicle such as an electric vehicle or a hybrid vehicle.

[0015] The wheel unit 10 will be described below with reference to Fig. 1. Fig. 1 is a vertical cross-sectional view of the wheel unit 10.

[0016] 1, the wheel unit 10 includes a cylindrical wheel 11 and a motor 12 that rotates the wheel 11. In the following description, the direction in which the rotational center axis LC of the motor 12 (wheel 11) extends is referred to as the axial direction, the direction extending radially from the center of the rotational center axis LC is referred to as the radial direction, and the direction extending circumferentially around the rotational axis is referred to as the circumferential direction.

[0017] The wheel 11 includes a tire 21 and a wheel 22 fixed to the inner periphery of the tire 21. The wheel 22 includes a hub 23 that serves as the center of rotation of the wheel 11, a cylindrical rim 24 that surrounds the hub 23, and spokes 25 that connect the hub 23 and the rim 24. The tire 21 is attached to the outer periphery of the rim 24. The hub 23 and the spokes 25 are provided on one axial end of the rim 24, and a motor 12 is housed in the inner space of the rim 24 (the inner space of the wheel 22). The motor 12 is provided in a fixed state to the hub 23 of the wheel 22.

[0018] The motor 12 is fixed to the inner periphery of the wheel 11. The motor 12 is an outer rotor surface permanent magnet motor, and includes a rotor 30 that rotates about a central rotation axis LC, and a stator 40 that is arranged radially inside the rotor 30. The stator 40 is fixed to the vehicle body 14, and the rotor 30 is fixed to the wheel 11. The rotor 30 and the stator 40 are each cylindrical, and are arranged opposite each other with an air gap that extends in an annular shape between them.

[0019] First, the configuration of the rotor 30 of the motor 12 will be described.

[0020] The rotor 30 has a substantially cylindrical carrier portion 31 and an annular magnet portion 32 fixed to the carrier portion 31. The carrier portion 31 functions as a magnet holding member and is formed of a metal material such as iron or aluminum. The carrier portion 31 has a cylindrical portion 33 and an end plate portion 34 provided on one axial end of the cylindrical portion 33. The other axial end of the cylindrical portion 33 is open. The cylindrical portion 33 has a magnet holding portion 33a and an expanded diameter portion 33b. The magnet portion 32 is fixed to the inner circumferential surface of the magnet holding portion 33a. The tip of the open side of the cylindrical portion 33 is the expanded diameter portion 33b, which has a larger diameter than the magnet holding portion 33a.

[0021] The magnet section 32 has a plurality of magnets fixed to the inner circumferential surface of the cylindrical section 33 of the carrier section 31. In the magnet section 32, the magnets are arranged so that their polarity alternates along the circumferential direction of the rotor 30. As a result, the rotor 30 has a plurality of magnetic poles in the circumferential direction, and each magnetic pole generates magnetic flux. The magnets are polar-anisotropic permanent magnets, and are configured using, for example, sintered neodymium magnets with an intrinsic coercivity of 400 kA / m or more and a residual magnetic flux density Br of 1.0 T or more. Incidentally, the motor 12 may be an interior permanent magnet synchronous machine (IPMSM).

[0022] The wheel unit 10 includes a hub bearing 35. The hub bearing 35 includes an outer ring 35a as a stationary portion, an inner ring 35b as a rotating portion, and a plurality of rolling elements 35c (e.g., balls) disposed between the outer ring 35a and the inner ring 35b. The inner ring 35b is fixed to the inner surface of the end plate portion 34, which is one of the two axially opposite surfaces that faces the cylindrical portion 33. The inner ring 35b, the hub 23, and the end plate portion 34 are fixed to one another with fasteners such as bolts. This allows the rotor 30 to be assembled to the wheel 11, and the rotor 30 and the wheel 22 to rotate integrally. In this embodiment, the wheel 22 corresponds to the "rotating member."

[0023] Next, the configuration of the stator 40 will be described.

[0024] The stator 40 includes a stator winding 41, a stator core 42, and a stator holder 43. The stator core 42 and the stator holder 43 are integrated with the stator core 42 on the radially outer side, and the stator winding 41 is assembled to the radially outer side of the stator core 42.

[0025] The stator winding 41 has a plurality of phase windings, and is formed into a cylindrical shape by arranging the phase windings of each phase in a predetermined order in the circumferential direction. For example, the stator winding 41 can be configured with three phase windings of U, V, and W phases. The stator core 42 is cylindrical and is provided as a back yoke.

[0026] For example, the stator 40 may have a teethless structure that does not have teeth for forming slots. This structure may be any of the following (A) to (C): (A) A structure in which inter-conductor members are provided between each conductor portion in the circumferential direction in the stator 40, and the inter-conductor members are made of a magnetic material that satisfies the relationship Wt×Bs≦Wm×Br, where Wt is the circumferential width of the inter-conductor member per magnetic pole, Bs is the saturation magnetic flux density of the inter-conductor member, Wm is the circumferential width of the magnet per magnetic pole, and Br is the residual magnetic flux density of the magnet that constitutes the magnet portion 32. (B) A structure in which inter-conductor members are provided between each conductor portion in the circumferential direction in the stator 40, and a non-magnetic material is used as the inter-conductor member. (C) A structure in which no inter-conductor members are provided between each conductor portion in the circumferential direction in the stator 40.

[0027] The stator holder 43 has a stator cylindrical portion 44 and an end plate portion 45. The stator cylindrical portion 44 is assembled to the radially inner side of the stator core 42. The end plate portion 45 is provided radially inner of the stator cylindrical portion 44 at one axial end side of the stator cylindrical portion 44. The end plate portion 45 of the stator holder 43 is provided on the same side of both axial sides as the end plate portion 34 of the carrier portion 31. As a result, the carrier portion 31 and the stator holder 43 are configured such that the end plate portions 34, 45 face each other on one of both axial sides and are open on the other side.

[0028] A refrigerant passage 46 is formed in the stator cylindrical portion 44, through which a refrigerant such as cooling water flows. The refrigerant passage 46 extends axially in a flat shape and is provided in an annular shape along the stator cylindrical portion 44, allowing the refrigerant to flow circumferentially between an inlet and an outlet (not shown). Although not shown, a circulation path for circulating the refrigerant is connected to the inlet and outlet of the refrigerant passage 46. The circulation path is provided with, for example, an electric pump and a heat dissipation device such as a radiator, and the refrigerant circulates through the circulation path and the refrigerant passage 46 of the motor 12 as the pump is driven.

[0029] The holder end plate portion 45 extends radially inward from the stator cylindrical portion 44 to the hub bearing 35, and serves as a partition plate portion that axially divides the inner space of the stator cylindrical portion 44. For example, the holder end plate portion 45 has a plurality of holes into which the outer ring 35a of the hub bearing 35 is assembled.

[0030] The stator 40 includes a stator base 47 that supports the stator holder 43. The stator base 47 is provided on the inner circumferential side of the stator cylindrical portion 44. The stator base 47 is fixed to the vehicle body 14. As a result, the motor 12 is mounted on the vehicle so that the rotational center axis LC of the rotor 30 extends in the horizontal direction.

[0031] Next, the brake device and its peripheral configuration will be described.

[0032] The wheel unit 10 includes a brake disc 50 and an intermediate mounting portion 60 that constitute a brake device. The brake device is a disc-type friction braking device. The brake disc 50 has an annular shape in the circumferential direction about the central axis of rotation LC. The brake disc 50 is, for example, a solid disc made of a single circular plate, or a ventilated disc with an internal cavity for ventilation. The brake disc 50 includes a disc mounting portion 51 and a sliding portion 52. The disc mounting portion 51 is the portion of the brake disc 50 that is mounted to the intermediate mounting portion 60. The sliding portion 52 is the portion of the brake disc 50 against which a brake pad is pressed, and is provided radially outside the intermediate mounting portion 60. In this embodiment, the brake disc 50 corresponds to the "brake sliding portion."

[0033] The brake device has a brake caliper. For example, in Fig. 1, the brake caliper is attached to the outer periphery of the brake disc 50. Although a detailed explanation using the drawings is omitted, the brake caliper has a pair of brake pads as friction members, a piston that presses the brake pads against the brake disc 50, and a caliper body that supports the brake pads and the piston. The brake caliper is operated by hydraulic pressure, an electric signal, or the like, and brings the brake pads into contact with the brake disc 50 to generate braking force.

[0034] The intermediate mounting portion 60 is a member for mounting the brake disc 50 to the cylindrical portion 33 of the rotor 30. The intermediate mounting portion 60 has an annular shape in the circumferential direction about the central axis of rotation LC. The intermediate mounting portion 60 is fixed to the expanded diameter portion 33b of the carrier portion 31 with fasteners such as bolts (not shown). A radially inner portion of the intermediate mounting portion 60 is attached to the stator base portion 47 via the bearing 36.

[0035] The bearing 36 is a rolling bearing, such as a radial ball bearing, having an outer ring 36a, an inner ring 36b, and a plurality of rolling elements 36c disposed therebetween. A radially inner portion of the intermediate mounting part 60 is fixed to the outer ring 36a. A stator base part 47 is fixed to the inner ring 36b. The rotor 30 is rotatably supported relative to the stator holder 43 and the stator base part 47 by the hub bearing 35 and the bearing 36. Note that the bearing 36 may be a roller bearing having rollers (e.g., a needle roller bearing or a tapered roller bearing) instead of the balls 36c as rolling elements.

[0036] The intermediate mounting portion 60 has a plurality of female threaded holes 61 formed at predetermined intervals in the circumferential direction. The female threaded holes 61 extend in the axial direction. The disc mounting portion 51 of the brake disc 50 has a bolt insertion hole 53 formed therethrough in the axial direction. A bolt 70 is inserted into the bolt insertion hole 53 and the female threaded hole 61, and the male thread formed in the shank of the bolt 70 is screwed into the female thread formed in the female threaded hole 61. In this way, the brake disc 50 is mounted to the intermediate mounting portion 60 with the disc mounting portion 51 and the intermediate mounting portion 60 abutting against each other. The motor 12 and the brake disc 50 correspond to a "drive device."

[0037] Here, in a configuration in which the brake disc 50 is attached to the rotor 30 via the intermediate mounting portion 60, there is a concern that heat generated in the brake disc 50 will be transferred to the magnet portion 32 via the brake disc 50, the intermediate mounting portion 60, and the carrier portion 31. In this case, there is a concern that the temperature of the magnet portion 32 will rise, resulting in a decrease in the magnetic flux density of the magnet portion 32.

[0038] Therefore, the wheel unit 10 according to this embodiment has a characteristic configuration for dissipating heat generated by the brake disc 50. The characteristic configuration will be described below.

[0039] The wheel unit 10 includes a plurality of fins 80. Each fin 80 is provided on the expanded diameter portion 33b of the carrier portion 31. Each fin 80 is fixed to the expanded diameter portion 33b with a fastener such as a bolt (not shown). Note that each fin 80 may be fixed by being sandwiched between the expanded diameter portion 33b and the wheel 22.

[0040] FIG. 2 shows a perspective view of the carrier portion 31 and each fin 80. Each fin 80 extends radially outward from the outer peripheral surface of the expanded diameter portion 33b. Each fin 80 protrudes a predetermined length from the outer peripheral surface of the expanded diameter portion 33b. Each fin 80 is arranged around the entire outer peripheral surface of the expanded diameter portion 33b. Note that each fin 80 is located radially inward of the rim 24. This prevents interference between each fin 80 and the wheel 11. In FIG. 2, the shape of the end plate portion 34 is simplified and shown as flat.

[0041] The enlarged diameter portion 33b is disposed between the brake disc 50 and the magnet portion 32, and serves as a heat transfer path for transferring heat from the brake disc 50, which is a heat source. In a configuration in which fins 80 protruding from the outer peripheral surface of the enlarged diameter portion 33b, which serves as the heat transfer path, are provided, the surface area of ​​the heat transfer path increases. This promotes heat dissipation in the heat transfer path. Therefore, heat transfer from the brake disc 50 to the magnet portion 32 can be suppressed.

[0042] Here, the expanded diameter portion 33b is provided on the brake disc 50 side of the magnet holding portion 33a in the axial direction, and is connected to the intermediate mounting portion 60. In other words, the expanded diameter portion 33b is provided on the brake disc 50 side of the magnet holding portion 33a in the heat transfer path from the brake disc 50 to the magnet portion 32. In this case, in a configuration in which the fins 80 are provided on the expanded diameter portion 33b, heat dissipation is promoted on the brake disc 50 side of the heat transfer path relative to the magnet holding portion 33a. Therefore, it is possible to reliably prevent heat generated in the brake disc 50 from being transferred to the magnet portion 32 fixed to the inner circumferential surface of the magnet holding portion 33a. The expanded diameter portion 33b corresponds to the "connection portion."

[0043] Furthermore, in a configuration in which the fins 80 are provided on the enlarged diameter portion 33b, the fins 80 are spaced further away from the brake disc 50, which is a heat source, than in a configuration in which the fins are provided on the intermediate mounting portion 60, unlike the present embodiment. This prevents the fins 80 from being heated by radiant heat from the brake disc 50. Therefore, a configuration that is suitable for utilizing the fins 80 as a heat dissipation portion can be realized.

[0044] The enlarged diameter portion 33b is located inward of the outer peripheral surface of the intermediate mounting portion 60. The protruding length of each fin 80 from the enlarged diameter portion 33b is shorter in the radial direction than the distance between the outer end of the intermediate mounting portion 60 and the outer end of the enlarged diameter portion 33b. In other words, the outer end of each fin 80 in the radial direction is located inward of the outer peripheral surface of the intermediate mounting portion 60. In this case, the intermediate mounting portion 60 is interposed between each fin 80 and the brake disc 50 in the axial direction. This further prevents each fin 80 from being heated by heat radiation from the brake disc 50.

[0045] The shape of each fin 80 will be described in detail using Figure 3. Figure 3 is a circumferentially expanded view of the expanded diameter portion 33b. In Figure 3, the vehicle front side is the side in the circumferential direction where the rotor 30 rotates in a specific direction, which is a direction in which the vehicle moves forward. In other words, the vehicle moves forward when the rotor 30 rotates in the specific direction. The outer side in the vehicle width direction is the magnet holding portion 33a side relative to the expanded diameter portion 33b in the axial direction. The inner side in the vehicle width direction is the intermediate mounting portion 60 side relative to the expanded diameter portion 33b in the axial direction. The magnet holding portion 33a and magnet portion 32 of the rotor 30 are arranged on the outer side in the vehicle width direction. The brake disc 50, the intermediate mounting portion 60, and the like are arranged on the inner side in the vehicle width direction. Note that, for convenience, Figure 3 shows the expanded diameter portion 33b and each fin 80, but does not illustrate other components.

[0046] Each fin 80 extends along the axial direction. The fins 80 are arranged at predetermined intervals in the circumferential direction. The axial dimension of each fin 81 is determined so that it fits within the axial width of the expanded diameter portion 33b.

[0047] Each fin 80 extends axially and has a flattened shape in the circumferential direction. The multiple fins 80 are arranged at predetermined intervals in the circumferential direction. In this case, when multiple fins 80 are arranged, an increase in the surface area of ​​the surface of each fin 80 facing the brake disc 50 is suppressed. This makes it possible to arrange multiple fins 80 so that the surface is less likely to be exposed to heat radiation from the brake disc 50. Therefore, it is possible to accurately increase the surface area of ​​the heat transfer path from the brake disc 50 to the magnet portion 32 while accurately suppressing heating of each fin 80 by radiant heat from the brake disc 50. As a result, it is possible to accurately promote heat dissipation from the heat transfer path by each fin 80.

[0048] Second Embodiment A second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, the shape of each fin is changed.

[0049] Figure 4 shows the expanded diameter portion 33b in a circumferentially expanded view. In Figure 4, the same components as those shown in Figure 3 are denoted by the same reference numerals for convenience. The "vehicle front side," "outer side in the vehicle width direction," and "inner side in the vehicle width direction" are explained in the same way as in Figure 3.

[0050] The wheel unit 10 includes a plurality of fins 81. As in the first embodiment, each fin 81 extends radially outward from the outer peripheral surface of the expanded diameter portion 33b and protrudes a predetermined length from the outer peripheral surface of the expanded diameter portion 33b. The fins 81 are arranged at predetermined intervals in the circumferential direction around the entire outer peripheral surface of the expanded diameter portion 33b. Differences between the fins 81 in the first embodiment and the fins 81 in the second embodiment will be described below.

[0051] Each fin 81 extends in a diagonal direction that is shifted circumferentially as it moves from one end to the other in the axial direction. Each fin 81 is provided on the outer peripheral surface of the expanded diameter portion 33b so as to fit within the axial width of the expanded diameter portion 33b. In this case, the diagonal dimension of each fin 81 can be made longer than the axial dimension of the fin 80 in the first embodiment. This makes it possible to realize a configuration that is suitable for increasing the surface area of ​​each fin 81, which serves as a heat dissipation portion.

[0052] In a configuration in which each fin 81 is provided on the carrier portion 31, each fin 81 rotates integrally with the rotor 30. Therefore, in this embodiment, the rotation of each fin 81 in conjunction with the rotation of the rotor 30 is utilized to generate an axial air flow. A configuration for generating an axial air flow will be described below.

[0053] Each fin 81 extends on the outer peripheral surface of the expanded diameter portion 33b so as to be shifted in a specific direction as it moves outward in the vehicle width direction. For example, regarding one of the fins 81a, a circumferential position P1 at the outer end of the fin 81a in the vehicle width direction is shifted in a specific direction compared to a circumferential position P2 at the inner end of the fin 81a in the vehicle width direction.

[0054] When the rotor 30 rotates in the specific direction, the air pushed by each fin 81 flows inward in the vehicle width direction. In this case, the air pushed by each fin 81 hits the brake disc 50. This allows the brake disc 50 to be cooled while the rotor 30 is rotating in the specific direction. As a result, the effect of suppressing heat transfer from the brake disc 50 to the magnet portion 32 can be improved.

[0055] <Modification of the Second Embodiment> As shown in Fig. 5, a plurality of fins 82 may be arranged. In Fig. 5, the same components as those shown in Fig. 3 are denoted by the same reference numerals for convenience. The "vehicle front side," "outer side in the vehicle width direction," and "inner side in the vehicle width direction" are the same as those in Fig. 3.

[0056] Specifically, each fin 82 may extend on the outer peripheral surface of the expanded diameter portion 33 b so that the fins 82 are shifted in the opposite direction to the specific direction as they move outward in the vehicle width direction. For example, with respect to one fin 82 a of each fin 82, a circumferential position P3 at the outer end of the fin 82 a in the vehicle width direction is shifted in the opposite direction to the specific direction compared to a circumferential position P4 at the inner end of the fin 82 a in the vehicle width direction.

[0057] When the rotor 30 rotates in a specific direction, air pushed by each fin 82 flows outward in the vehicle width direction. In this case, the air pushed by each fin 82 flows toward the carrier portion 31, which is a heat transfer path for heat generated in the brake disc 50. This makes it possible to generate an air flow that cools the carrier portion 31 while the rotor 30 is rotating in the specific direction. As a result, it is possible to enhance the effect of suppressing heat transfer from the brake disc 50 to the magnet portion 32.

[0058] Third Embodiment A third embodiment will now be described with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, the shape of each fin is changed.

[0059] Figure 6 shows the expanded diameter portion 33b in a circumferentially expanded view. In Figure 6, the same components as those shown in Figure 3 are denoted by the same reference numerals for convenience. The "vehicle front side," "outer side in the vehicle width direction," and "inner side in the vehicle width direction" are explained in the same way as in Figure 3.

[0060] The wheel unit 10 includes fins 83. As in the first embodiment, the fins 83 extend radially outward from the outer peripheral surface of the expanded diameter portion 33b and protrude a predetermined length from the outer peripheral surface of the expanded diameter portion 33b. Differences between the fins 83 in the first embodiment and the second embodiment will be described below.

[0061] The fins 83 extend in the circumferential direction. In the present embodiment, the fins 83 are arranged in a plurality of pieces in the circumferential direction, separated at predetermined intervals of a length L. Each fin 83 is arranged in the circumferential direction around the entire outer circumferential surface of the expanded diameter portion 33 b.

[0062] The fins 83 can be arranged so as to overlap in the axial direction. For example, as shown in Figure 6, three fins 83 can be arranged so as to overlap within the axial width of the expanded diameter portion 33b. This allows the surface area of ​​the heat transfer path from the brake disc 50 to the magnet portion 32 to be increased appropriately.

[0063] It is not necessary to provide multiple fins 83. For example, the fins 83 may be arranged continuously around the entire outer circumferential surface of the expanded diameter portion 33b without any circumferential breaks. Furthermore, the fins 83 do not need to be arranged overlapping in the axial direction.

[0064] Each fin 83 extends in the circumferential direction and has a flattened shape in the axial direction. This increases the surface area of ​​the heat transfer path while suppressing an increase in the surface area of ​​the circumferentially facing surface of each fin 83. This reduces air resistance that occurs when the rotor 30 rotates and promotes heat dissipation in the heat transfer path.

[0065] Fourth Embodiment A fourth embodiment will now be described with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, the shape of each fin is changed.

[0066] Fig. 7 shows a vertical cross-sectional view of the wheel unit 10. In Fig. 7, the same components as those shown in Fig. 1 are denoted by the same reference numerals for convenience.

[0067] The wheel unit 10 includes fins 84. As in the first embodiment, the fins 84 extend radially outward from the outer peripheral surface of the expanded diameter portion 33b in the radial direction and protrude a predetermined length from the outer peripheral surface of the expanded diameter portion 33b. The fins 84 extend along the axial direction and are arranged in plurality at predetermined intervals in the circumferential direction. Each fin 84 is arranged at a predetermined interval in the circumferential direction around the entire outer peripheral surface of the expanded diameter portion 33b. Below, differences between each fin 84 and the first embodiment will be described.

[0068] The expanded diameter portion 33b has a facing portion 33c and a protruding portion 33d. The facing portion 33c is a portion of the expanded diameter portion 33b that does not protrude axially from the rim 24 of the wheel 11 and is disposed facing the inner circumferential surface of the rim 24. The protruding portion 33d extends axially from the facing portion 33c toward the intermediate attachment portion 60. The protruding portion 33d is a portion of the expanded diameter portion 33b that protrudes axially from the rim 24. The rim 24 is not present radially outward of the protruding portion 33d.

[0069] Each fin 84 is provided on the facing portion 33 c and the protruding portion 33 d, spanning the facing portion 33 c and the protruding portion 33 d in the axial direction. The length of each fin 84 that protrudes from the outer circumferential surface of the expanded diameter portion 33 b decreases as it approaches the wheel 11 in the axial direction. In other words, in the vertical cross-sectional view of the wheel unit 10, each fin 84 has a tapered shape that tapers axially toward the wheel 11.

[0070] Each fin 84 has a first portion 84a provided on the facing portion 33c and a second portion 84b provided on the protruding portion 33d. The radially outer end of the first portion 84a is located inside the inner circumferential surface of the wheel 11 (specifically, the rim 24). This prevents the fins 84 from interfering with the rim 24. The second portion 84b also extends radially outward beyond the outer end of the first portion 84a. This allows the surface area of ​​each fin 84 to be larger than when the entire protruding length of each fin 84 is limited to the inner circumferential surface of the rim 24 or less. Therefore, according to this embodiment, the heat dissipation effect of each fin 84 can be enhanced while preventing the fins 84 from interfering with the wheel 11.

[0071] <Modification of Fourth Embodiment> When each fin 84 extends in an oblique direction as described in the second embodiment, it may be tapered axially toward the wheel 11. Even in this case, the radially outer end of the first portion 84a of each fin 84 can be positioned more inward than the rim 24, and the second portion 84b can extend radially outward beyond the outer end of the first portion 84a.

[0072] The fins 84 do not necessarily have to be tapered axially toward the wheel 11. For example, the first portions 84a of the fins 84 may have the same protruding length from the outer peripheral surface of the enlarged diameter portion 33b. Also, the second portions 84b of the fins 84 may have the same protruding length from the outer peripheral surface of the enlarged diameter portion 33b.

[0073] As described in the third embodiment, the fins 84 may extend in the circumferential direction and be arranged so as to overlap in the axial direction. In this case, of the fins 84 arranged so as to overlap in the axial direction, the fin 84 provided on the facing portion 33 c may be defined as the first portion 84 a, and the radial outer end of the first portion 84 a may be located more inward than the rim 24. Alternatively, of the fins 84 arranged so as to overlap in the axial direction, the fin 84 provided on the protruding portion 33 d may be defined as the second portion 84 b, and the second portion 84 b may extend more outward in the radial direction than the outer end of the first portion 84 a.

[0074] 7 shows an example in which the second portion 84b of each fin 84 is located radially outward from the outer peripheral surface of the intermediate mounting portion 60. Alternatively, each fin 84 may be located radially inward from the outer peripheral surface of the intermediate mounting portion 60. In this case, the second portion 84b of each fin 84 may extend radially outward from the outer end of the first portion 84a and may be located radially inward from the outer peripheral surface of the intermediate mounting portion 60. This makes it possible to both suppress the effects of heat radiation from the brake disc 50 and increase the surface area of ​​each fin 84.

[0075] 8 , the outer ends 84 c of the second portions 84 b of each fin 84 may be aligned radially with the outer peripheral surface of the intermediate mounting portion 60. In other words, the outer ends of each fin 84 in the radial direction may be aligned with the outer peripheral surface of the intermediate mounting portion 60. This makes it possible to maximize the surface area of ​​each fin 84 while suppressing the effects of heat radiation from the brake disc 50.

[0076] Fifth Embodiment A fifth embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, the shape of the fins is changed.

[0077] Figure 9 shows a circumferentially expanded cross section of the expanded diameter portion 33b and the wheel 22. Figure 9 is a line cross section taken along an imaginary line drawn in the radial direction passing through the expanded diameter portion 33b and the rim 24 in Figure 1, and shows the expanded diameter portion 33b and the rim 24 expanded in the circumferential direction. Note that in Figure 9, the same components as those shown in Figure 1 are denoted by the same reference numerals for convenience.

[0078] The wheel unit 10 includes corrugated fins 85. The fins 85 are provided between the inner peripheral surface of the wheel 22 and the outer peripheral surface of the enlarged diameter portion 33b.

[0079] The fin 85 has a first folded portion 85a and a second folded portion 85b. The first folded portion 85a is a portion of the fin 85 that folds back from the expanded diameter portion 33b side toward the wheel 22 side. The apex of the first folded portion 85a abuts against the expanded diameter portion 33b. The second folded portion 85b is a portion of the fin 85 that folds back from the wheel 22 side toward the expanded diameter portion 33b. The apex of the second folded portion 85b abuts against the wheel 22. The fin 85 extends from the first folded portion 85a to the second folded portion 85b, and protrudes a predetermined length from the outer peripheral surface of the expanded diameter portion 33b.

[0080] The first folded portions 85a and the second folded portions 85b are alternately provided in the circumferential direction, so that the fins 85 are provided around the entire circumference of the expanded diameter portion 33b in the circumferential direction.

[0081] The enlarged diameter portion 33b is provided with positioning pins 90 for positioning the fins 85. For example, the positioning pins 90 are integrally formed with the enlarged diameter portion 33b. A plurality of the positioning pins 90 are provided in the circumferential direction at the same intervals as the first folded portions 85a. A positioning hole 91 is formed in each of the first folded portions 85a. In each of the first folded portions 85a, the positioning pin 90 is fitted into the positioning hole 91, thereby fixing the fins 85 to the enlarged diameter portion 33b. Note that a plurality of the positioning pins 90 and the positioning holes 91 may be provided at predetermined intervals in the axial direction.

[0082] According to this embodiment, the expanded diameter portion 33b is provided with corrugated fins 85. In this case, the fins 85 extend from each first folded portion 85a to the adjacent second folded portions 85b in the circumferential direction. Therefore, compared to a configuration in which multiple thin plate-like fins are provided on the expanded diameter portion 33b, a configuration suitable for increasing the surface area of ​​the heat transfer path can be realized. As a result, heat transfer from the brake disc 50 to the magnet portion 32 can be effectively suppressed.

[0083] The second folded portion 85b abuts against the wheel 22. This allows heat to be transferred from the expanded diameter portion 33b to the wheel 22 via the fins 85. This increases the number of heat dissipation paths for the heat transferred from the expanded diameter portion 33b, thereby realizing a configuration suitable for utilizing the fins 85 as a heat dissipation portion.

[0084] <Modification of Fifth Embodiment> The fin 85 may be held in a state sandwiched between the enlarged diameter portion 33b and the wheel 22. In this case, the positioning pins 90 may not be provided in the enlarged diameter portion 33b, and the positioning holes 91 may not be provided in the first folded portion 85a.

[0085] Each first folded portion 85a may be fixed to the enlarged diameter portion 33b by welding, instead of using a fitting structure of the positioning pin 90 and the positioning hole 91. In this case, the enlarged diameter portion 33b may not be provided with the positioning pin 90, and the first folded portion 85a may not be provided with the positioning hole 91.

[0086] Other Embodiments The above-described embodiments may be modified as follows.

[0087] The heat dissipation fins do not necessarily have to be provided on the enlarged diameter portion 33b. For example, the fins may be provided on at least one of the outer circumferential surface of the magnet holding portion 33a and the outer circumferential surface of the intermediate mounting portion 60. In this case, the shape of the fins may be as described in the first to third and fifth embodiments. Furthermore, for example, the fins may be provided on the end surface of the intermediate mounting portion 60 on the brake disc 50 side in the axial direction. In other words, the fins may be provided on the outer surface of at least one of the magnet holding portion 33a, the enlarged diameter portion 33b, and the intermediate mounting portion 60.

[0088] In the first to fifth embodiments, the fins 80 to 83 do not necessarily have to be arranged around the entire outer circumferential surface of the expanded diameter portion 33b, but may be arranged on only a portion of the outer circumferential surface of the expanded diameter portion 33b.

[0089] The brake device may be a drum-type friction braking device instead of a disc-type friction braking device. In this case, the brake device has brake shoes as friction members and a brake drum against which the brake shoes are pressed. The brake drum is attached to the intermediate mounting portion 60. The brake shoes move radially outward and are pressed against the brake drum, generating a braking force on the rotor 30. At this time, there is a concern that heat generated in the brake drum may be transferred to the magnet portion 32 via the intermediate mounting portion 60 and the carrier portion 31. In this embodiment, the brake drum corresponds to the "brake sliding portion."

[0090] The intermediate attachment portion 60 does not necessarily have to be fixed as a separate member to one axial end of the rotor 30 , but may be formed integrally with the rotor 30 .

[0091] The motor 12 may be used for purposes other than a vehicle traction motor, and may be a motor used in a wide range of moving objects, including aircraft and ships. For example, when the motor 12 is used in an aircraft, the motor 12 serves as a power source for the aircraft's flight, and a propeller serving as a rotating member rotates as the motor 12 is driven. When the motor 12 is used in a ship, the motor 12 serves as a power source for the ship's navigation, and a screw serving as a rotating member rotates as the motor 12 is driven.

[0092] The disclosure in this specification is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and modifications thereto by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and / or elements shown in the embodiments. The disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and / or elements from the embodiments. The disclosure encompasses the substitution or combination of parts and / or elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. Some disclosed technical scopes are defined by the claims, and should be interpreted as including all modifications within the meaning and scope equivalent to the claims.

[0093] - The following describes characteristic configurations extracted from each of the above-described embodiments. [Configuration 1] A drive device including: a motor (12) having a rotor (30) that rotates about a central axis of rotation extending in a predetermined axial direction, and a stator (40) arranged inside the rotor in a radial direction perpendicular to the axial direction, and a brake sliding portion (50) that is annular in a circumferential direction extending circumferentially about the central axis of rotation and against which a friction member is pressed, wherein the rotor has: a cylindrical carrier portion (31), a magnet portion (32) provided on an inner peripheral surface of the carrier portion, an intermediate mounting portion (60) that is annular in the circumferential direction and is provided at an end of the carrier portion in the axial direction, to which the brake sliding portion is attached, and fins (80-85) that are provided on an outer surface of at least one of the carrier portion and the intermediate mounting portion and that protrude from the outer surface. [Configuration 2] The drive device according to Configuration 1, wherein the carrier portion has a magnet holding portion (33a) to which the magnet portion is fixed on an inner peripheral surface thereof, and a connection portion (33b) that is provided on the brake sliding portion side of the magnet holding portion in the axial direction and is connected to the intermediate mounting portion, and the fins extend from the outer peripheral surface in the radial direction to the outside in the radial direction at the connection portion. [Configuration 3] The drive device according to Configuration 2, wherein the fins (80, 84) extend along the axial direction and have a flattened shape in the circumferential direction, and a plurality of fins are arranged at predetermined intervals in the circumferential direction. [Configuration 4] The drive device according to Configuration 2, wherein the fins (81, 82) extend in an oblique direction that shifts in the circumferential direction as they go from one end side to the other end side in the axial direction, and a plurality of fins are arranged at predetermined intervals in the circumferential direction. [Configuration 5] The drive device according to Configuration 4, wherein the motor is an in-wheel motor provided on a wheel of a vehicle, the vehicle moves forward when the rotor rotates in a specific direction, the motor is provided outward in the vehicle width direction from the brake sliding portion, and each of the fins (81) extends along the diagonal direction so as to be shifted in the specific direction as it goes further outward in the vehicle width direction.[Configuration 6] The drive device according to Configuration 4, wherein the motor is an in-wheel motor provided on a wheel of a vehicle, the vehicle moves forward when the rotor rotates in a specific direction, the motor is provided outboard in a vehicle width direction than the brake sliding portion, and each of the fins (82) extends along the oblique direction so as to be shifted in a direction opposite to the specific direction as it goes outboard in the vehicle width direction. [Configuration 7] The drive device according to Configuration 2, wherein the fins (83) extend along the circumferential direction and have a flattened shape in the axial direction. [Configuration 8] The drive device according to any one of configurations 2 to 7, comprising a cylindrical rotating member (22) that is provided to cover an outer peripheral surface of the rotor and rotates as the rotor rotates, wherein the connection portion has: a facing portion (33c) that is arranged to face an inner peripheral surface of the rotating member without protruding from the rotating member in the axial direction; and a protruding portion (33d) that extends from the facing portion toward the intermediate attachment portion in the axial direction and protrudes from the rotating member in the axial direction, wherein the fin (84) has a first portion (84a) that is provided at the facing portion and a second portion (84b) that is provided at the protruding portion, wherein the radially outer end of the first portion is located inside the inner peripheral surface of the rotating member, and the second portion (84b) extends in the radial direction outward beyond the outer end of the first portion. [Configuration 9] The drive device of any one of Configurations 2 to 8, wherein the outer ends of the fins in the radial direction are located inside the outer peripheral surface of the intermediate mounting portion or are located at the outer peripheral surface of the intermediate mounting portion. [Configuration 10] The drive device of Configuration 1, further comprising a cylindrical rotating member (22) that is provided to cover the outer peripheral surface of the rotor and rotates with rotation of the rotor, the fins being corrugated fins (85), and the fins are provided in a sandwiched state between the inner peripheral surface of the rotating member and the outer peripheral surface of the carrier portion.

[0094] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A drive device comprising: a motor (12) having a rotor (30) that rotates around a central axis of rotation extending in a predetermined axial direction, and a stator (40) arranged inside the rotor in a radial direction perpendicular to the axial direction; and a brake sliding part (50) that is annular in a circumferential direction extending circumferentially around the central axis of rotation and against which a friction member is pressed, wherein the rotor has: a cylindrical carrier part (31); a magnet part (32) provided on an inner peripheral surface of the carrier part; an intermediate mounting part (60) that is annular in the circumferential direction, is provided at an end of the carrier part in the axial direction, and to which the brake sliding part is attached; and fins (80-85) provided on the outer surface of at least one of the carrier part and the intermediate mounting part, and protrudes from the outer surface.

2. The drive unit described in claim 1, wherein the carrier portion has a magnet holding portion (33a) to whose inner surface the magnet portion is fixed, and a connection portion (33b) that is provided on the brake sliding portion side of the magnet holding portion in the axial direction and is connected to the intermediate mounting portion, and the fins extend radially outward from the outer peripheral surface in the radial direction at the connection portion.

3. A drive unit as described in claim 2, wherein the fins (80, 84) extend along the axial direction, have a flat shape in the circumferential direction, and are arranged in plurality at predetermined intervals in the circumferential direction.

4. A drive unit as described in claim 2, wherein the fins (81, 82) extend in a diagonal direction that shifts in the circumferential direction as they move from one end to the other end in the axial direction, and a plurality of fins are arranged at predetermined intervals in the circumferential direction.

5. A drive device as described in claim 4, wherein the motor is an in-wheel motor provided on a wheel of a vehicle, the vehicle moves forward when the rotor rotates in a specific direction, the motor is provided outside the brake sliding portion in the vehicle width direction, and each of the fins (81) extends along the diagonal direction so as to be shifted in the specific direction as it moves toward the outside in the vehicle width direction.

6. A drive device as described in claim 4, wherein the motor is an in-wheel motor provided on a wheel of a vehicle, the vehicle moves forward when the rotor rotates in a specific direction, the motor is provided outside the brake sliding portion in the vehicle width direction, and each of the fins (82) extends along the diagonal direction so as to be shifted in the opposite direction to the specific direction as it moves toward the outside in the vehicle width direction.

7. The drive unit according to claim 2, wherein the fins (83) extend along the circumferential direction and are flattened in the axial direction.

8. A drive device as described in claim 2, comprising a cylindrical rotating member (22) that is arranged to cover the outer peripheral surface of the rotor and rotates with the rotation of the rotor, wherein the connection portion has an opposing portion (33c) that is arranged facing the inner peripheral surface of the rotating member without protruding from the rotating member in the axial direction, and a protruding portion (33d) that extends from the opposing portion toward the intermediate mounting portion in the axial direction and protrudes from the rotating member in the axial direction, wherein the fin (84) has a first portion (84a) provided on the opposing portion and a second portion (84b) provided on the protruding portion, wherein the radially outer end of the first portion is located inside the inner peripheral surface of the rotating member, and the second portion (84b) extends outward in the radial direction beyond the outer end of the first portion.

9. A drive unit as described in claim 2, wherein the radially outer end of the fin is located inside the outer circumferential surface of the intermediate mounting portion, or is positioned at the outer circumferential surface of the intermediate mounting portion.

10. A drive unit as described in claim 1, comprising a cylindrical rotating member (22) that is arranged to cover the outer peripheral surface of the rotor and rotates with the rotation of the rotor, the fins being corrugated fins (85), and the fins being sandwiched between the inner peripheral surface of the rotating member and the outer peripheral surface of the carrier portion.

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