JP2011183985A - Brake device of in-wheel motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake device of an in-wheel motor which reduces the size and weight of an in-wheel type driving mechanism, and reduces load exerted on a bearing of a wheel shaft. <P>SOLUTION: The wheel shaft 14 is supported by the interior of an inner housing 12 constituting the brake device 21 through the bearing 13. A hub 15 is engagedly fixed to the wheel shaft 14, and a driving wheel 16 is connected to the hub 15. An inner stator 18 is disposed on the outer peripheral surface of the inner housing 12. A permanent magnet 20 is attached to the outer peripheral surface of the hub 15 through an outer housing 19. A brake drum 12a is integrally formed in an opening of the inner housing 12 on the side opposite the hug 15. A brake mechanism 46 is mounted on an inner end of the wheel shaft 14. The rotation of the wheel shaft 14 is braked by pressing first and second brake shoes 25 and 26 of the brake mechanism 46 against an inner peripheral surface 12b of the brake drum 12a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a brake device for an in-wheel motor that can be reduced in size and weight to increase an empty space around the in-wheel motor.

  As a brake device of an in-wheel motor, what was indicated by patent documents 1 is proposed conventionally. In this brake device, as shown in FIG. 11, an in-wheel motor 62 is housed in a case 61 mounted on a vehicle body frame, and a drive shaft is connected to a motor shaft 63 of the in-wheel motor 62 via a speed reduction mechanism 64. 65 is connected. A hub 66 is connected to the drive shaft 65, and a wheel 67 is connected to the hub 66 by bolts. A brake device 69 is mounted on the hub 66 via a disk rotor 68.

JP 2006-1373 A

  However, since the brake device 69 is accommodated inside the wheel 67 in the conventional brake device, the bearing center O70 related to the axial direction of the bearing 70 of the motor shaft 63 of the in-wheel motor 62 and the axial direction of the wheel 67 are related. The separation distance L from the wheel center O67 is large, and there are the following problems. That is, since the bearing center O70 and the wheel center O67 are largely offset, the case 61 and the in-wheel motor 62 protrude greatly from the wheel 67, and the in-wheel drive mechanism cannot be reduced in size and weight.

  When the speed reduction mechanism 64 is omitted and the motor shaft 63 and the drive shaft 65 are integrated, that is, when the motor shaft 63 of the motor 62 is a wheel shaft, the separation distance L is not the speed reduction mechanism 64. It will be shorter. However, since a considerable separation distance L still exists, a large load acts on the bearing 70 of the motor shaft (wheel shaft) 63 due to the principle of the lever, and a large, high-rigidity bearing must be used.

  An object of the present invention is to provide a brake device for an in-wheel motor that can reduce the size and weight of the in-wheel drive mechanism and can reduce the load acting on the bearing of the wheel shaft.

  In order to solve the above-mentioned problems, an invention according to claim 1 is an in-wheel motor type vehicle in which an electric motor is accommodated inside a drive wheel, and a cylindrical shape that constitutes the electric motor in a suspension device of the vehicle. An inner housing, a wheel shaft is supported through a bearing in a central hole of the inner housing, a driving wheel is connected to an outer end of the wheel shaft through a hub, and an opening of the inner housing on the vehicle side The gist of the present invention is that a brake drum is provided, a brake mechanism is connected to the inner end of the wheel shaft, and the brake mechanism is housed inside the brake drum.

  According to a second aspect of the present invention, in the first aspect, the brake mechanism includes a brake base coupled to an inner end portion of the wheel shaft and a first erected at two locations on the outer peripheral side of the brake base. And a second support pin, first and second brake shoes pivotably joined to both support pins, a flat surface portion formed on the first support pin, and a tip part of the second brake shoe Between the first cam lever interposed between the flat portion formed on the first support lever, the flat portion formed on the second support pin, and the flat portion formed on the tip of the first brake shoe. A second cam lever, a biasing means that biases the first and second brake shoes in a non-braking direction that always approaches, and a pivot that rotates the first and second cam levers in the braking direction. Consists of operating mechanism The gist.

  According to a third aspect of the present invention, in the second aspect, the rotation operation mechanism includes a shielding cover attached to an opening end portion of the brake drum, and an operation rod supported by the shielding cover so as to reciprocate. A conical cam member connected to the inner end of the actuating rod so as to correspond to the tip ends of the first and second cam levers, and a wire for pulling the actuating rod. When moved from the braking position to the braking position, the first and second cam levers are rotated in the braking direction so that the first and second brake shoes are pressed against the inner peripheral surface of the brake drum. It is a summary.

  According to a fourth aspect of the present invention, in the first aspect, the brake mechanism shields a cylindrical flexible brake drum that is elastically deformable at an inner end portion of the wheel shaft and an opening of the brake drum. A support pin attached to the shielding cover, first and second brake shoes pivotably joined to the support pin, and tip portions of the first and second brake shoes attached to the shielding cover A cam member interposed therebetween, an urging means for urging the first and second brake shoes in a non-braking direction approaching each other, and rotating the cam member in the braking direction to The gist of the invention is that it is constituted by a rotation operation mechanism that moves in the braking direction.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the bearing center in the axial direction of the bearing of the wheel shaft matches the driving wheel center in the axial direction of the rotational axis of the driving wheel. It is set as the gist.

(Function)
According to the present invention, a brake drum is provided at the end of the cylindrical inner housing constituting the electric motor on the vehicle side, and the brake mechanism connected to the wheel shaft is accommodated inside the brake drum. For this reason, the bearing of the wheel shaft can be accommodated in the central part inside the driving wheel, and the separation distance between the bearing center in the axial direction of the bearing and the driving wheel center in the axial direction of the rotation axis of the driving wheel is reduced. can do. Therefore, the electric motor and the brake device are prevented from protruding from the drive wheel, and the in-wheel drive mechanism is reduced in size and weight. Further, the load acting on the wheel shaft bearing is reduced.

  According to the present invention, the in-wheel drive mechanism can be reduced in size and weight, the load acting on the wheel shaft bearing can be reduced, and the bearing can be reduced in size and weight.

The center part sectional view showing the 1st embodiment which materialized the brake device of the in-wheel motor of this invention. The perspective view of the non-braking state of a brake device. The central part expanded sectional view of the non-braking state of a brake device. The central part expanded sectional view of the braking state of a brake device. The front view of the non-braking state of a brake device. The front view of the braking state of a plate apparatus. Sectional drawing of the center part which shows 2nd Embodiment which actualized the brake device of the in-wheel motor of this invention. The front view of the non-braking state of a brake device. The front view of the braking state of a brake device. Sectional drawing of the brake device which shows another embodiment of this invention. Sectional drawing of the center part which shows the brake device of the conventional in-wheel motor.

(First embodiment)
A first embodiment of a brake device for an in-wheel motor embodying the present invention will be described below with reference to FIGS.

  As shown in FIG. 1, a cylindrical inner housing 12 constituting an in-wheel motor 11 is connected to an upper arm and a lower arm of a double wishbone suspension of a suspension device (not shown) of a vehicle. A wheel shaft 14 is rotatably supported in the center hole of the inner housing 12 via a pair of inner and outer radial ball bearings 13. A hub 15 is fitted and fixed near the tip of the wheel shaft 14, and a driving wheel 16 is connected to the hub 15 by a plurality of hub stand bolts 17. An inner stator 18 composed of teeth 18 a and coils 18 b is fitted and fixed to the outer peripheral surface of the inner housing 12. A housing forming portion 15 a having an L-shaped cross section that forms a part of the outer housing of the in-wheel motor 11 is integrally formed on the outer peripheral edge portion of the hub 15. A cylindrical outer housing 19 is fitted and fixed to the outer peripheral surface of the housing forming portion 15 a so as to cover the inner stator 18. A plurality of permanent magnets 20 are joined and fixed to the inner peripheral surface of the outer housing 19 so as to face the teeth 18a of the inner stator 18 at a predetermined interval. Each permanent magnet 20 is arranged such that the N pole and S pole on the surface facing the inner stator 18 are alternately changed in the circumferential direction of the outer housing 19.

A brake device 21 is mounted between the inner housing 12 and the inner end of the wheel shaft 14. The brake device 21 will be described below.
As shown in FIG. 1, a cylindrical brake drum 12a is integrally formed at the opening end of the inner housing 12 opposite to the hub 15. The brake drum 12a is formed to have a larger diameter than the diameter of the cylindrical portion that supports the inner stator 18.

  As shown in FIG. 1, a disc-shaped metal brake base 22 is connected to an inner end (right end in the figure) of the wheel shaft 14 on the vehicle side so as to be synchronously rotatable with the shaft 14 by a bolt. . As shown in FIG. 2, semi-cylindrical first and second support pins 23 and 24 are vertically installed on the side surface near the outer periphery of the brake base 22 by welding in parallel with each other at an interval of 180 degrees. ing. A semi-cylindrical engagement recess 25a formed at the base end of the first brake shoe 25 is rotatably engaged with the semi-columnar portion 23a of the first support pin 23. A flat surface portion 25 b formed at the distal end portion of the first brake shoe 25 is disposed opposite to the flat surface portion 24 b formed on the second support pin 24. A semi-cylindrical engaging recess 26a formed at the base end portion of the second brake shoe 26 is rotatably engaged with the semi-cylindrical portion 24a of the second support pin 24, and the second brake shoe A flat surface portion 26 b formed at the tip end portion 26 is disposed opposite to the flat surface portion 23 b formed on the first support pin 23.

  A brake lining 27 is bonded to the arc-shaped outer peripheral surfaces of the first and second brake shoes 25 and 26. As shown in FIG. 5, a predetermined gap is always formed between the brake lining 27 and the inner peripheral surface 12b of the brake drum 12a. As shown in FIG. 6, the rotation of the wheel shaft 14 is braked when the brake linings 27 of the first and second brake shoes 25 and 26 are pressed against the inner peripheral surface 12b of the brake drum 12a. It has become so.

  Between the flat part 23b of the first support pin 23 and the flat part 26b at the tip of the second brake shoe 26, an angle is formed by the first flat plate part 28a and the second flat plate part 28b. A cam plate 28c formed at the base end portion of the second flat plate portion 28b of the first cam lever 28 is interposed. Similarly, the first flat plate portion 29a and the second flat plate portion 29b are formed in an angle between the flat portion 24b of the second support pin 24 and the flat portion 25b of the first brake shoe 25. A cam plate 29c formed at the base end portion of the second flat plate portion 29b of the second cam lever 29 is interposed.

  As shown in the partially enlarged view of FIG. 2, a screw hole 23c is formed in the tip surface of the first support pin 23, and the first flat plate portion 28a of the first cam lever 28 is formed so as to correspond to the screw hole 23c. A through-hole 28d is formed through the base end portion. Then, the male screw portion 30a of the support pin 30 including the male screw portion 30a, the shaft portion 30b, and the flange portion 30c is screwed into the screw hole 23c, and the shaft portion 30b is advanced into the through hole 28d, so that the flange portion The first cam lever 28 is rotatably connected to the first support pin 23 by bringing 30c into contact with the upper surface of the first flat plate portion 28a. Since the support pin 30 of the second cam lever 29 is also configured in the same manner as the support pin 30 on the first cam lever 28 side, description thereof is omitted.

  Both ends of first and second tension springs 31 and 32 as urging means are connected to the first and second brake shoes 25 and 26 by locking pins, and the first and second tension springs 31 and 32 are connected. Therefore, the first and second brake shoes 25 and 26 are always urged in the non-braking direction approaching each other. Further, the first and second tension springs 31 and 32 allow the engagement recesses 25a and 26a of the first and second brake shoes 25 and 26 to become semi-cylindrical portions 23a and 23a of the first and second support pins 23 and 24, respectively. The flat portions 25b and 26b of the first and second brake shoes 25 and 26 are pressed against the cam plates 28c and 29c of the first and second cam levers 28 and 29, respectively.

  As shown in FIG. 1, the opening end face of the brake drum 12a of the inner housing 12 has a shielding cover for covering the first and second brake shoes 25 and 26, the first and second cam levers 28 and 29, and the like. 41 is attached with a bolt. A through hole 41a is formed through the center of the shielding cover 41, and a guide tube 42 is connected to the shielding cover 41 by welding so as to communicate with the through hole 41a. An operating rod 43 is pierced and supported in the guide cylinder 42 so as to reciprocate in the same direction as the axis of the wheel shaft 14, and a conical cam member 44 is connected to the inner end of the operating rod 43. ing. The distal end portion of the cam member 44 is in contact with the distal end portions of the first and second cam levers 28 and 29. A wire 45 linked to a brake pedal (not shown) provided at the driver's seat of the vehicle is connected to the outer end portion of the operating rod 43.

  In this embodiment, the brake base 22, the first and second support pins 23, 24, the first and second brake shoes 25, 26, the first and second cam levers 28, 29, the first and second tension springs. A brake mechanism 46 is constituted by 31, 32, the operating rod 43, the cam member 44, and the like. Further, the operation rod 43, the cam member 44, the wire 45, and the like constitute a rotation operation mechanism 47 for the first and second cam levers 28 and 29.

Next, the operation of the brake device 21 of the in-wheel motor 11 configured as described above will be described.
In FIG. 1, when an alternating current is supplied from a power source such as a battery (not shown) to the coil 18b of the inner stator 18 of the in-wheel motor 11, the motor 11 is driven, and the outer housing 19 and the permanent magnet 20 are moved to the wheel shaft. 14 is rotated around the vehicle and the vehicle is driven. When the vehicle is stopped while the vehicle is running, the supply of current to the coil 18b of the in-wheel motor 11 is stopped, and when a brake pedal (not shown) of the driver's seat is depressed by the driver, the wire 45 is In FIG. 1 and FIG. 3, the cam member 44 is pulled in the right direction and the cam member 44 is moved in the same direction via the operating rod 43. For this reason, the inclined surface 44a of the cam member 44 is pushed between the tip portions of the first and second cam levers 28, 29, and the first and second cam levers 28, 29 are moved toward the support pin 30 in FIG. Rotated in the direction. By rotation of the first and second cam levers 28 and 29, the cam plates 28c and 29c are rotated between the flat surface portion 23b (26b) and the flat surface portion 24b (25b), and the first and second brake shoes 25 are rotated. 26 are rotated about the first and second support pins 23 and 24 in the direction of arrow Q in FIG. 5, and the brake linings of the first and second brake shoes 25 and 26 are formed on the inner peripheral surface 12b of the brake drum 12a. 27 is pressed. As a result, the rotation of the wheel shaft 14, the brake base 22, the first and second brake shoes 25, 26, etc. is braked, and the drive wheels 16 are braked.

According to the brake device for an in-wheel motor of the above embodiment, the following effects can be obtained.
(1) In the first embodiment, the brake drum 12a is integrally formed at the end of the inner housing 12 on the vehicle body frame side, and the brake base 22 is connected to the inner end of the wheel shaft 14, A brake mechanism 46 for braking the rotation of the wheel shaft 14 is provided on the brake base 22 in cooperation with the brake drum 12a. For this reason, as shown in FIG. 1, the center O16 in the axial direction of the drive wheel 16 and the bearing center O13 in the central axial direction of the wheel shaft 14 of the pair of bearings 13 of the in-wheel motor 11 can be matched. Therefore, the load acting on the bearing 13 can be reduced when the drive wheel 16 is rotated and the vehicle travels. Further, the in-wheel motor 11 can be accommodated in the drive wheel 16 and the amount of the brake device 21 protruding from the drive wheel 16 can be suppressed, so that the in-wheel drive mechanism can be reduced in size and weight. .

  (2) In the first embodiment, since the inner opening of the inner housing 12 is used as the brake drum 12a, a dedicated heavy brake drum 12a is not required, and the brake device 21 can be reduced in size and weight. From this point, the in-wheel drive mechanism can be reduced in size and weight.

  (3) In the first embodiment, the cam plate 28c of the first cam lever 28 is interposed between the flat portion 23b of the first support pin 23 and the flat portion 26b of the second brake shoe 26, and the second support pin The cam plate 29 c of the second cam lever 29 is interposed between the 24 flat portions 24 b and the flat portion 25 b of the first brake shoe 25. Further, the brake lining 27 is pressed against the inner peripheral surface 12b of the brake drum 12a by the lever principle by rotating the first and second cam levers 28 and 29. For this reason, the pressing force of the brake lining 27 against the inner peripheral surface 12b can be ensured, and the wheel shaft 14 can be braked appropriately.

  (4) In the first embodiment, the first and second brake shoes 25 and 26 are rotated outward about the first and second support pins 23 and 24. For this reason, the first and second brake shoes 25 and 26 are urged outward by the rotation of the wheel shaft 14 against the urging force of the first and second tension springs 31 and 32 by centrifugal force. . Therefore, the pressing operation of the first and second brake shoes 25 and 26 against the brake drum 12 a can be appropriately performed with a small operating force of the brake wire 45.

(Second Embodiment)
Next, a second embodiment of the brake device for an in-wheel motor embodying the present invention will be described with reference to FIGS. In addition, since 2nd Embodiment is the structure which changed the brake mechanism 46 of the brake device 21 of the in-wheel motor 11 of 1st Embodiment, description is abbreviate | omitted about the same structure.

  As shown in FIG. 7, a flexible brake drum 48 that is elastically deformable via an attachment ring 40 is integrally formed at the inner end portion of the wheel shaft 14. The flexible brake drum 48 includes a disc-like portion 48a connected to the mounting ring 40 by a bolt, a cylindrical portion 48b formed integrally with the outer peripheral edge of the disc-like portion 48a, and The disk-shaped part 48a is constituted by a bent part 48c formed in the circumferential direction. A brake shoe 49 is bonded to the inner peripheral surface 12 b of the brake drum 12 a of the inner housing 12. The cylindrical portion 48 b of the flexible brake drum 48 is always in a non-contact state between the brake lining 27 of the first and second brake shoes 25 and 26 and the brake shoe 49. The first and second brake shoes 25 and 26 are attached to the shielding cover 41.

  In the second embodiment, as shown in FIG. 8, instead of the first support pin 23, a cylindrical support pin 51 is erected on the shielding cover 41 by welding or the like. Engaging recesses 25a and 26a of the first and second brake shoes 25 and 26 are joined so as to be rotatable. In addition to the second support pin 24, a long square plate-like cam member 52 is mounted on the shielding cover 41 opposite to the support pin 51 so as to be rotatable at a predetermined position. The cam member 52 is interposed between the opposed flat portions 25b, 26b of the first and second brake shoes 25, 26. An operating lever 53 is connected to the cam member 52, and the operating lever 53 is rotated by a brake wire 45. The wire 45 is introduced into the brake drum 12a through a hole (not shown) formed in the shielding cover 41.

  In the second embodiment, when the brake wire 45 is pulled, the operation lever 53 is rotated counterclockwise in FIG. By this operation, the cam member 52 is tilted between the flat portions 25b and 26b of the first and second brake shoes 25 and 26 as shown in FIG. 9, and the first and second brake shoes 25 and 26 are moved. The first and second tension springs 31 and 32 are rotated against the urging force of the first and second tension springs 31 and 32 in the braking direction separated from each other about the support pin 51. As a result, the brake lining 27 is pressed against the inner peripheral surface of the flexible brake drum 48, the cylindrical portion 48b of the flexible brake drum 48 is elastically deformed, and the outer peripheral surface thereof is the brake on the inner periphery of the brake drum 12a. Pressed against Shu 49. Accordingly, the rotation of the wheel shaft 14 is braked.

According to the brake device for an in-wheel motor of the second embodiment, the following effects can be obtained.
(1) In the second embodiment, the flexible brake drum 48 is sandwiched between the brake shoe 49 on the brake drum 12a side and the brake lining 27 on the first and second brake shoes 25, 26 side. did. For this reason, the sliding friction between braking components can be improved and the braking function of the wheel shaft 14 can be improved.

  (2) In the second embodiment, since the main components of the brake mechanism 46 are mounted on the shielding cover 41 fixed to the brake drum 12a, the rotational load on the wheel shaft 14 can be reduced.

(3) In the second embodiment, since the cam member 52 is provided at only one place, the number of parts can be reduced, manufacturing and assembling operations can be easily performed, and the cost can be reduced.
In addition, you may change this embodiment as follows.

  As shown in FIG. 10, the brake lining 27 is bonded to the inner side surface 12c orthogonal to the inner peripheral surface 12b of the brake drum 12a. A flexible brake disk 56 that is elastically deformable is disposed so as to face the brake lining 27 with a predetermined gap. On the other hand, a brake shoe 58 is mounted on the inner side surface of the shielding cover 41 via a spring 57 so as to be able to reciprocate only in the axial direction of the wheel shaft 14. A cam mechanism 60 including a cam member 59 that presses the brake shoe 58 against the flexible brake disk 56 against the biasing force of the spring 57 is provided between the brake shoe 58 and the shielding cover 41.

  In this embodiment, when the outer peripheral edge of the brake shoe 58 is pressed against the side surface of the flexible brake disc 56 by the cam mechanism 60, the flexible brake disc 56 is pressed against the brake lining 27 to rotate the wheel shaft 14. Is braked.

As the brake mechanism 46 of the brake device 21, various brake mechanisms such as a centrifugal brake device may be employed.
In each of the above embodiments, as shown in FIG. 1, the center O16 of the drive wheel 16 and the bearing center O13 of the bearings 13 and 13 of the in-wheel motor 11 are made to coincide, but the load of the radial ball bearings 13 and 13 The center O16 and the bearing center O13 may be separated to a certain extent so as not to increase.

  O13 ... bearing center, 11 ... in-wheel motor, 12 ... inner housing, 12a ... brake drum, 12b ... inner peripheral surface, 13 ... bearing, 14 ... wheel shaft, 15 ... hub, 16 ... drive wheel, 22 ... brake base, 23 ... 1st support pin, 23b, 24b, 25b, 26b ... Planar part, 24 ... 2nd support pin, 25 ... 1st brake shoe, 26 ... 2nd brake shoe, 28 ... 1st cam lever, 29 ... 1st 2 cam lever, 30, 51 ... support pin, 41 ... shielding cover, 43 ... actuating rod, 44, 52, 59 ... cam member, 45 ... wire, 46 ... brake mechanism, 47 ... rotating operation mechanism, 48 ... flexible brake Drum, 49 ... brake show.

Claims (5)

In an in-wheel motor type vehicle in which an electric motor is accommodated inside a drive wheel,
A cylindrical inner housing constituting the electric motor is mounted on a suspension device of a vehicle, a wheel shaft is supported through a bearing in a central hole of the inner housing, and driven through a hub at an outer end portion of the wheel shaft. The wheel is connected, a brake drum is provided in the opening of the inner housing on the vehicle side, a brake mechanism is connected to the inner end of the wheel shaft, and the brake mechanism is housed inside the brake drum. Wheel motor braking device. 2. The brake mechanism according to claim 1, wherein the brake mechanism includes a brake base connected to an inner end portion of the wheel shaft, first and second support pins erected at two locations on an outer peripheral side of the brake base, and both support pins. Between the first and second brake shoes that are pivotally joined to each other, a flat surface portion formed on the first support pin, and a flat surface portion formed on the tip of the second brake shoe. A first cam lever interposed between the first cam lever, a flat surface portion formed on the second support pin, a second cam lever interposed between a flat surface portion formed on a tip portion of the first brake shoe, And an urging means for urging the first and second brake shoes in a non-braking direction that always approaches, and a rotation operation mechanism for rotating the first and second cam levers in the braking direction. In-wheel featuring Over other brake system. 3. The rotating operation mechanism according to claim 2, wherein the rotation operation mechanism includes a shielding cover attached to an opening end portion of the brake drum, an operating rod supported by the shielding cover so as to be able to reciprocate, and an inner end portion of the operating rod. A conical cam member connected to correspond to the tip portions of the first and second cam levers and a wire pulling the operating rod, and the cam member is moved from the non-braking position to the braking position. And the first and second cam levers are rotated in the braking direction, and the first and second brake shoes are pressed against the inner peripheral surface of the brake drum. Brake equipment. The brake mechanism according to claim 1, wherein the brake mechanism includes a cylindrical flexible brake drum that is elastically deformable at an inner end portion of the wheel shaft, and a support pin attached to a shielding cover that shields an opening of the brake drum. First and second brake shoes pivotally joined to the support pin; a cam member attached to the shielding cover and interposed between the front ends of the first and second brake shoes; A biasing means for biasing the first and second brake shoes in a non-braking direction approaching each other, and a rotating operation mechanism for rotating the cam members in the braking direction and moving both brake shoes in the braking direction. And an in-wheel motor brake device. The bearing center in the axial direction of the bearing of the wheel shaft according to any one of claims 1 to 4, is set to coincide with the driving wheel center in the axial direction of the rotation axis of the driving wheel. Brake device for in-wheel motor.

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