JP7398735B2 - wheel drive device - Google Patents

Description

The present invention relates to an in-wheel motor type wheel drive device, and in particular, to reduce the centrifugal force applied to the rotor of an electric motor rotated by an external force and the regenerative power generated in the rotor by separating the speed reduction mechanism with an electromagnetic clutch mechanism. Concerning new improvements.

Typically, an in-wheel motor type wheel drive device is used in electric vehicles and the like. In this type of wheel drive device, the wheels are rotated using a motor called an in-wheel motor as a drive source. In this case, a system using a planetary gear mechanism is known as a power transmission mechanism for transmitting the driving force of the motor to the wheels (see, for example, Patent Document 1).

US Patent No. 9511853

Conventionally, when driving a vehicle such as an automobile using the driving force of a motor, it is preferable to ensure a large reduction ratio of the planetary gear mechanism in order to reduce the torque required of the motor. However, when the reduction ratio of the planetary gear mechanism is increased, the following problems occur when used as a wheel drive device for an aircraft, for example.

When the above-mentioned in-wheel motor type wheel drive device is used in an aircraft, the wheels of the aircraft are rotated by the wheel drive device when the aircraft moves on a taxiway at an airport, so-called taxiing. In this case, in order to move an aircraft that is heavier than a car, it is necessary to ensure a large reduction ratio of the planetary gear mechanism. However, in an aircraft wheel drive device, even when the in-wheel motor is not driven, the wheels may rotate at high speed due to external force during landing and takeoff other than taxiing. That is, when an aircraft is landing or taking off, the wheels of the aircraft rotate at a much higher speed than when taxiing. Furthermore, the power transmission path in the wheel drive device is reversed from that during taxiing, which involves driving the motor. Therefore, the rotation of the wheels is increased in speed by the built-in planetary gear mechanism and transmitted to the motor, and a large centrifugal force is applied to the rotor of the motor. Furthermore, since a large amount of regenerative power (back electromotive force) is generated in the motor, it is necessary to increase the size of peripheral equipment that incorporates large resistors in order to absorb this.

The present invention has been made to solve the above problems, and its purpose is to reduce the centrifugal force applied to the rotor of the motor and the regenerated power generated when the wheels rotate at high speed due to external factors. The objective is to provide a wheel drive device that can.
Furthermore, since the wheels of the in-wheel motor type wheel drive device according to the present invention are directly attached to the axle, the vertical load of the legs applied during landing etc. is directly applied from the wheels to the axle. Since the structure is such that it does not enter, only rotation needs to be considered as an external force.

An in-wheel motor type wheel drive device according to the present invention includes an electric motor having a stator and a rotor, a drive shaft that rotates together with the rotor, and a planetary gear mechanism that rotates together with the drive shaft and serves as a speed reduction mechanism. a sun gear forming a part of the gear, a first gear part and a second gear part, the first gear part meshing with the sun gear, a plurality of planetary gears, and a first gear part of the plurality of planetary gears; A clutch disc includes a first internal gear that meshes with each other and has a first tooth-shaped portion on a side surface, and a second tooth-shaped portion that can freely move toward and away from the first tooth-shaped portion of the first internal gear. an electromagnetic clutch mechanism capable of switching between a state in which the first internal gear is fixed and a state in which the first internal gear is rotated; an outer case having a rotation stopper for the clutch disk; A wheel drive device comprising a second internal gear that meshes with a second gear portion, and an output shaft that rotates integrally with the second internal gear, wherein the planetary gear mechanism is a 3K type of mysterious planetary gear.

The wheel drive device according to the present invention is a wheel drive device for an aircraft.

Since the wheel drive device according to the present invention is configured as described above, the following effects can be obtained. That is, when the wheels rotate at high speed due to external force, the centrifugal force applied to the rotor of the motor and the regenerated power generated can be reduced by lowering the rotational speed of the rotor using the electromagnetic clutch mechanism.
Therefore, damage to the rotor due to strong centrifugal force and introduction of a large device for discarding strong regenerated power can be eliminated.

1 is a longitudinal sectional view showing the overall configuration of a wheel drive device according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view showing the main part of FIG. 1. FIG. FIG. 2 is an enlarged sectional view showing the main part of FIG. 1. FIG. FIG. 2 is a longitudinal sectional view showing a state in which a wheel is applied to the wheel drive device of the present invention.

Hereinafter, preferred embodiments of the in-wheel motor type wheel drive device according to the present invention will be described. In addition, in this specification, an "in-wheel motor type wheel drive device" is simply called a "wheel drive device."
FIG. 1 is a longitudinal sectional view showing the overall configuration of a wheel drive device according to an embodiment of the present invention.
The illustrated wheel drive device 1 is a wheel drive device for an aircraft, and is mainly composed of an electric motor 2, a planetary gear mechanism 3, and an electromagnetic clutch mechanism 4. Note that FIG. 1 shows a cross-sectional structure of the wheel drive device 1 viewed along the longitudinal direction of the aircraft, that is, along the axial direction of the central axis K of the wheel drive device 1, with the upper side in the figure being vertically upward, and the lower side in the figure being Corresponds to the vertically downward direction. Further, the axis K in FIG. 1 indicates the central axis of the wheel drive device 1.

The electric motor 2 includes a resolver 20 used to control rotation. The resolver 20 is a sensor that detects the rotation speed and rotation angle of the electric motor 2.

The electric motor 2 has a stator 21 and a rotor 22, and a drive shaft 24 is connected to the rotor 22 using a key 23. The electric motor 2 is arranged between the outer case 10 and the inner case 13 in the radial direction of the wheel drive device 1. The stator 21 is fixed to an outer case 10, and the outer case 10 and the inner case 13, together with a first rear cover 14, a second rear cover 15, and a front cover 16, constitute a housing of the wheel drive device 1.

A flange portion 11 is formed at one end of the outer case 10, and a partition portion 12 is formed at an intermediate portion of the outer case 10. Further, the other end portion 10a of the outer case 10, which is opposite to the flange portion 11, extends long from the partition portion 12 toward the planetary gear mechanism 3 side. A fixing hole 11a is provided in the flange portion 11, and a plurality of fixing holes 11a are provided at predetermined intervals in the circumferential direction of the flange portion 11. The partition portion 12 is arranged between the electromagnetic clutch mechanism 4 and the electric motor 2 in the direction of the central axis K of the wheel drive device 1 . The outer case 10 is configured to be fixed to a wheel support part (not shown) of an aircraft by bolting using a fixing hole 11a of the flange part 11.

The drive shaft 24 is disposed inside the inner case 13, rotates together with the rotor 22, and has a cylindrical shape centered on the central axis K. The drive shaft 24 is rotatably supported by two bearings 50 and 52, and a sun gear 30 is provided at one end thereof, and the sun gear 30 is integrally formed with the drive shaft 24. That is, the drive shaft 24 and the sun gear 30 are integrally configured.

The planetary gear mechanism 3 is mainly composed of a sun gear 30, a plurality of planetary gears 31, a first internal gear 32, and a second internal gear 33. Each of the planetary gears 31 is held by a pair of carriers 36 and 37, and each is formed into a ring shape around a central axis K. It is rotatably supported by a bearing 54.

Among the pair of carriers 36 and 37, one carrier 36 is rotatably supported by a bearing 52, and the other carrier 37 is rotatably supported by a bearing 53.

The first internal gear 32 is rotatably supported by a pair of bearings 54 spaced apart from each other, and the outer ring of each bearing 54 is fixed to the inner peripheral surface of the outer case 10. The second internal gear 33 is rotatably supported by a bearing 51, and the outer ring of the bearing 51 is fixed to the inner peripheral surface of the outer case 10.

Further, each planetary gear 31 is configured with a two-stage gear having a first gear part 34 and a second gear part 35 integrally, and the first gear part 34 has both the sun gear 30 and the first internal gear 32. are meshed with each other. The second gear portion 35 meshes with the second internal gear 33. The first internal gear 32 and the second internal gear 33 have different numbers of teeth, and each planetary gear 31 meshes with these two internal gears 32 and 33.

An output shaft 38 is mechanically connected to the second internal gear 33, and this output shaft 38 rotates together with the second internal gear 33. By fitting a key (not shown) into a keyway, the output shaft 38 rotates integrally with the second internal gear 33. (not shown) is connected and fixed to a wheel 5 for mounting. Thereby, the second internal gear 33, the output shaft 38, and the wheel 5 are configured to rotate together with each other.

The electromagnetic clutch mechanism 4 constitutes a switching mechanism capable of switching between a state in which the first internal gear 32 is fixed and a state in which the first internal gear 32 is rotated. The clutch disc 40, a spring 41, a yoke 42, and a magnet wire 43 are also included. This clutch disc 40 is provided so as to be movable in a direction parallel to the central axis K so as to be able to move toward or away from the first internal gear 32, that is, to be able to move toward or away from the first internal gear 32. A rotation stopper 40b is provided at the outer case 10, and the rotation stopper 40b serves as a mechanism for locking the clutch disc 40 against the outer case 10 so that it does not rotate even under excessive torque. That is, the rotation stopper 10b of the outer case 10 is engaged with the rotation stopper portion 40b of the clutch disc 40 to prevent rotation.

Here, the relationship between the clutch disc 40 and the first internal gear 32 will be explained using FIG. 1.
First, a first tooth-shaped portion 32a is formed on the side surface of the first internal gear 32, and the first tooth-shaped portion 32a extends in a predetermined direction in the circumferential direction of the first internal gear 32, as shown in FIG. It is formed in a concave and convex shape with intervals. Meanwhile, a second tooth-shaped portion 40a is formed on the side surface of the clutch disc 40. The second tooth-shaped portion 40a is formed to face the first tooth-shaped portion 32a of the first internal gear 32 in a direction parallel to the central axis K. The second tooth-shaped portion 40a is a tooth-shaped portion that can freely move toward and away from the first tooth-shaped portion 32a of the first internal gear 32, and is uneven at predetermined intervals in the circumferential direction of the clutch disc 40. It is formed in the shape of The clutch disc 40 is urged in a direction away from the first internal gear 32 by a spring 41, as shown in a cross section below the central axis K in FIG. The electromagnetic clutch mechanism 4 for moving the first internal gear 32 is an electromagnetic drive unit, and includes a yoke 42 formed in a ring shape with a groove, and a magnet wrapped in the groove of the yoke. It is constituted by a wire 43. As is well known, the electromagnetic clutch mechanism 4 operates by being turned on and off of electricity by a wheel control device (not shown). Specifically, when the electromagnetic clutch mechanism 4 is energized, it operates to pull the clutch disk 40 toward the left in FIG. 1 by magnetic attraction force against the biasing force of the spring 41, and when it is not energized, the magnetic attraction force It operates to release.

More specifically, when the clutch disc 40 is pulled by energizing the electromagnetic clutch mechanism 4, the clutch disc 40 moves in a direction approaching the first internal gear 32, and this movement causes the clutch disc 40 to have a second tooth shape. The shaped portion 40a meshes with the first tooth-shaped portion 32a of the first internal gear 32. As a result, the first internal gear 32 is fixed, resulting in a state in which the power of the reduction gear is transmitted. On the other hand, when the electromagnetic clutch mechanism 4 is de-energized, the clutch disc 40 moves in a direction away from the first internal gear 32 due to the biasing force of the spring 41, and this movement causes the second tooth of the clutch disc 40 to move away from the first internal gear 32. As the mold-shaped portion 40a separates from the first tooth-shaped portion 32a of the first internal gear 32, rotation of the first internal gear 32 is allowed, resulting in a state in which power from the reducer is not transmitted.

Next, the operation of the wheel drive device according to the embodiment of the present invention during taxiing will be described. First, when a drive current is supplied to the electric motor 2 by a control section (not shown), the rotor 22 rotates due to the rotating magnetic field generated by the stator 21 having the stator winding 8a, and the drive shaft 24 and the rotor 22 are integrally connected to each other. Sun gear 30 rotates. At this time, if the second tooth-shaped portion 40a of the clutch disc 40 is brought into mesh with the first tooth-shaped portion 32a of the first internal gear 32 by energizing the electromagnetic clutch mechanism 4 by the control section, the first Rotation of the internal gear 32 is fixed by a clutch disc 40. Therefore, the first internal gear 32 substantially functions as a fixed internal gear and is in a state of transmitting the power of the reduction gear.

On the other hand, since the second internal gear 33 is rotatably supported by the bearing 51, it functions as a movable internal gear. In this way, the first internal gear 32 functions as a fixed internal gear, and the second internal gear 33 functions as a movable internal gear, so that the planetary gear mechanism 3 as a reduction mechanism is configured as a so-called mysterious planetary gear (3K type) functions as a mechanism. That is, when the sun gear 30 rotates as described above, each planetary gear 31 revolves around the sun gear 30 while rotating. Further, the second internal gear 33 rotates together with the output shaft 38 according to the reduction ratio of the planetary gear mechanism 3. Therefore, if the reduction ratio of the planetary gear mechanism 3 is 1/n (where n is a number larger than 1), the rotation of the drive shaft 24 accompanying the drive of the electric motor 2 is reduced to 1/n. and is transmitted to the output shaft 38.
The number of teeth Z and the reduction ratio 1/n of each gear are shown below as an example of the 3K type mysterious planetary gear which is the reduction gear structure of the wheel drive device of the present invention. However, the number of teeth and reduction ratio of the present invention are not limited to these.
Sun gear Z=56, first planetary gear Z=16, second planetary gear Z=15,
When the first internal gear Z=88 and the second internal gear Z=87,
The reduction ratio is 1/n=1/50.
Further, six planetary gears are arranged so as to be supported by a carrier. However, the number of planetary gears of the present invention is not limited.

The above is the operation of the wheel drive device 1 when taxiing an aircraft. On the other hand, when the aircraft lands or takes off, the tires mounted on the wheels 5 rotate at a much higher speed than when taxiing due to external forces. At this time, if the electromagnetic clutch mechanism 4 is energized by the control section, the rotation of the output shaft 38 is increased by a reciprocal of the reduction ratio of the planetary gear mechanism 3, that is, n times. The signal is transmitted to the drive shaft 24. Therefore, the rotor 22 of the electric motor 2 rotates at a high speed n times the rotation speed of the output shaft 38. Therefore, when the wheels rotate at high speed due to external forces such as during landing of an aircraft, a large centrifugal force is applied to the rotor 22 of the electric motor 2. Further, since the rotor 22 rotates at a very high speed, a large amount of regenerative power is generated in the electric motor 2.

Therefore, when the aircraft lands or takes off, the control section de-energizes the electromagnetic clutch mechanism 4, so that the first tooth-shaped portion of the first internal gear 32 is turned off as shown in FIG. 32a, the second tooth-shaped portion 40a of the clutch disk 40 is separated from the second tooth-shaped portion 40a of the clutch disk 40, and even if the output shaft 38 rotates at high speed during landing or takeoff of an aircraft, the rotation of the output shaft 38 is increased by n times and is driven. It is no longer transmitted to the shaft 24. The reason is as follows. First, when the output shaft 38 rotates during landing or takeoff of the aircraft, the second internal gear 33 rotates together with the output shaft 38. At this time, when the electromagnetic clutch mechanism 4 is in a non-energized state, the first internal gear 32 functions as a movable internal gear similarly to the second internal gear 33. Therefore, when the second internal gear 33 rotates, each planetary gear 31 revolves without rotating, and the first internal gear 32 rotates together with the second internal gear 33. Moreover, when each planetary gear 31 revolves, the sun gear 30 rotates accordingly. As a result, the second internal gear 33, the first internal gear 32, the planetary gear 31, and the sun gear 30 rotate integrally with each other. Therefore, the output shaft 38 and the drive shaft 24 rotate at the same rotation speed. Therefore, the rotation of the output shaft 38 is not increased by n times and transmitted to the drive shaft 24, and the centrifugal force applied to the rotor 22 of the electric motor 2 and the centrifugal force generated in the electric motor 2 during landing of an aircraft, etc. It is possible to reduce both the regenerated power and the regenerated power.

In the embodiment described above, the wheel drive device 1 is used for an aircraft, but the present invention is not limited thereto, and can be widely applied as a wheel drive device for a moving body other than an aircraft.

1 wheel drive device, 2 electric motor, 3 planetary gear mechanism, 4 electromagnetic clutch mechanism,
10 outer case, 10b rotation stopper, 21 stator, 22 rotor,
24 drive shaft, 30 sun gear, 31 planetary gear, 32 first internal gear,
32a first tooth-shaped part, 33 second internal gear, 34 first gear part, 35 second gear part, 38 output shaft, 40 clutch disc, 40a second tooth-shaped part,
40b Detent portion.

Claims (1)

An in-wheel motor type wheel drive device used for aircraft taxiing,
an electric motor (2) having a stator (21) and a rotor (22);
a drive shaft (24) that rotates integrally with the rotor (22);
a sun gear (30) that rotates together with the drive shaft (24) and forms part of a planetary gear mechanism (3) as a speed reduction mechanism;
a plurality of planetary gears (31) each having a first gear part (34) and a second gear part (35), the first gear part (34) meshing with the sun gear (30);
a first internal gear (32) that meshes with the first gear part (34) of the plurality of planetary gears (31) and has a first tooth-shaped part (32a) on a side surface;
a clutch disc (40) having a second tooth-shaped portion (40a) that can freely approach and separate from the first tooth-shaped portion (32a) of the first internal gear (32); an electromagnetic clutch mechanism (4) that can be switched between a state in which the gear (32) is fixed and a state in which rotation of the first internal gear (32) is allowed;
an outer case (10) having a rotation prevention portion (10b) for the rotation prevention portion (40b) of the clutch disc (40);
a second internal gear (33) meshing with the second gear portion (35) of the plurality of planetary gears (31);
an output shaft (38) that rotates integrally with the second internal gear (33);
An in-wheel motor type wheel drive device, characterized in that the planetary gear mechanism (3) is a 3K type of mysterious planetary gear.

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