JP4682045B2 - In-wheel motor for electric vehicles - Google Patents

Description

  The present invention relates to an in-wheel motor used as a power device for a vehicle such as a prime mover.

In recent years, a direct drive method for directly driving wheels with a motor without providing a reduction gear has been developed as a vehicle driving method. In the direct drive system, an outer rotor type in-wheel motor in which an annular stator is attached to an axle via a bracket and a rotor is directly fixed to the wheel side is used. The rotor has a configuration in which permanent magnets are arranged in the circumferential direction, and the stator has a coil in which windings are concentratedly wound around teeth. When the stator coil is energized to rotate the rotor, the wheel fixed integrally with the rotor rotates. Since the wheel is rotatably attached to the axle by a bearing, the wheel is directly driven to rotate by an in-wheel motor (see, for example, Patent Document 1).
JP 2002-281722 A

However, in this type of in-wheel motor, the stator is fixed to the axle while the rotor is fixed to the wheel. Therefore, it is necessary to design in consideration of the assembly tolerance between the stator and the rotor. Furthermore, when the axle is slightly deformed by a load from the road surface applied to the wheel, the rotor must not interfere with the stator. For this reason, the gap between the rotor and the stator cannot be reduced, and the conventional in-wheel motor has a structural limitation on the driving torque.
The present invention has been made in view of such circumstances, and has as its main object to reduce the gap between the rotor and the stator so as to obtain a good driving torque.

The invention according to claim 1 of the present invention for solving the above-mentioned problems is an in-wheel motor for an electric vehicle having a rotor having a rotor core fixed to a rotor holder and a stator, wherein the stator is fixed to a suspension, and the rotor holder Is an in-wheel motor for an electric vehicle characterized in that a power transmission portion is provided inside the stator via a bearing and transmits the rotation of the rotor to the wheel via a buffer member.
In this in-wheel motor for an electric vehicle, the stator is separated from the axle by fixing the stator to the suspension. Further, since the rotor is supported on the inner periphery of the stator via the bearing, the rotor is also separated from the axle. The driving torque of the rotor is transmitted to the wheel via the power transmission unit, and the buffer member absorbs the deviation between the wheel axis and the rotor axis.

According to a second aspect of the present invention, in the in-wheel motor for an electric vehicle according to the first aspect, the power transmission portion is formed on a boss projecting a part of the rotor holder, an outer periphery of the boss, and the wheel. And an elastic member inserted between the formed holes.
In this in-wheel motor for an electric vehicle, when an external force is applied to the wheel, the elastic member absorbs the deviation between the wheel shaft center and the rotor shaft center. Since the elastic member is arranged so as to surround the outer periphery of the boss, the external force acting on the wheel can be absorbed with a simple configuration.

The invention according to claim 3 is the in-wheel motor for an electric vehicle according to claim 1 or 2, wherein each of the rotor core and the stator has a salient pole structure and is wound around the salient pole of the stator. A current is supplied to the wound winding based on the position information of the rotor.
This in-wheel motor for an electric vehicle employs a switched reluctance motor, so that a permanent magnet is not required and the structure is simplified. Further, since the gap between the stator and the core can be reduced, a large driving torque can be generated.

  According to the present invention, since the stator and the rotor are not supported by the axle, it is not necessary to consider the assembly tolerance to the axle as in the prior art, and the gap between the stator and the rotor can be reduced. Further, since the eccentricity between the wheel and the rotor can be absorbed by the power transmission unit, the gap between the stator and the rotor can be reduced. From these things, it becomes possible to generate a high driving torque stably.

The best mode for carrying out the invention will be described in detail with reference to the drawings.
1 and 2 show a vehicle drive unit including an in-wheel motor for an electric vehicle (hereinafter referred to as an in-wheel motor). The in-wheel motor 1 includes a stator 2 and a rotor 3, and is fixed to a housing portion 6 that is recessed in a front end portion 5 </ b> A of a swing arm 5 that is a rear suspension of an electric type prime mover. Here, the swing arm 5 swings so that the distal end portion 5A draws an arc starting from a pivot shaft passing through a through hole 7 provided in the base end portion 5B. An axle 8 is fixed to the distal end portion 5A so as to be orthogonal to the swinging direction. A wheel 9 is attached to the axle 8 after passing the in-wheel motor 1 in a non-contact manner. A hole 11 through which the axle 8 is passed is formed in the wheel 10 of the wheel 9, and the axle 8 is fixed to the inner ring of the bearing 12 press-fitted therein by a nut 13.

  As shown in FIGS. 1 to 3A, 3B, the stator 2 of the in-wheel motor 1 has an annular stator body 22 having a hole 21 formed in the center. The size of the hole 21 is sufficiently larger than the outer diameter of the axle 8. A plurality of through holes 23 penetrating in the axle direction are formed in the stator body 22 at equal intervals in the circumferential direction, and the stator 2 is positioned and fixed to the swing arm 5 through bolts 24 in the through holes 23. Furthermore, a plurality of salient pole portions 25 are provided on the outer periphery of the stator body 22 at substantially equal intervals in the circumferential direction. Each salient pole portion 25 is provided with an insulator (not shown) and then wound with a winding 26 to form a coil. In addition, it is preferable to mold the coil which consists of the coil | winding 26 with resin.

The rotor 3 has a configuration in which a rotor core 36 is fixed to the inner periphery of the rotor holder 31 by press-fitting. In the rotor holder 31, an annular end portion 33 is integrally extended from the base end of the outer cylinder 32 in the diameter reducing direction, and the peripheral edge of the opening 34 at the center of the end portion 33 extends concentrically with the outer cylinder 32. Is formed. The outer cylinder 32, the end part 33, and the inner cylinder 35 are substantially U-shaped in a cross-sectional view. A rotor core 36 is press-fitted on the inner peripheral side of the outer cylinder 32 so as to abut against the end portion 33.
The rotor core 36 has a plurality of salient pole portions 38 projecting from the annular core body 37 at substantially equal intervals in the rotation direction toward the rotation center. The inner peripheral surface of the salient pole portion 38 has an arc shape, and a minute gap 39 is formed between the salient pole portion 38 and the outer peripheral surface of the salient pole portion 25 of the stator 2. Thus, in this embodiment, the wheel motor 1 is configured as a switched reluctance motor that does not have a permanent magnet.

  The inner surface side of the end portion 33 is recessed so as to receive the stator 2. Two bearings 42 are press-fitted at predetermined intervals in the length direction of the inner cylinder 35 on the outer peripheral surface of the inner cylinder 35 of the rotor holder 31. The outer peripheral surfaces of these bearings 42 are press-fitted into the inner peripheral surface of the hole 21 of the stator 2, and the rotor holder 31 is rotatably supported with respect to the stator 2 via the bearings 42.

  Here, a plurality of holes 41 are formed in the end portion 33 in accordance with the arrangement of the through holes 23 on the stator 2 side. The diameter of the hole 41 is large enough to insert and remove the bolt 24. Further, a plurality of power transmission units 50 are provided on the outer surface of the end portion 33 (surface facing the wheel 9) at substantially equal intervals in the circumferential direction. Each power transmission unit 50 includes a boss 51 that is integrally extended in the axial direction from the end portion 33 of the rotor holder 31, and a buffer member 52 that covers the outer periphery of the boss 51. The buffer member 52 has an outer diameter that can be press-fitted into a power transmission hole 55 formed in the wheel 10. The buffer member 52 can be made of an elastic member or a self-lubricating resin (lubricating resin). Examples of the lubricating resin include a fluorine-based resin.

Next, the operation of this embodiment will be described.
Electricity is supplied from a motor control device (not shown) so that a rotating magnetic field is generated in the winding 26 wound around the stator 2 of the in-wheel motor 1. The rotor core 36 rotates with respect to the stator 2 due to the difference between the magnetic flux generated by the current flowing in the winding 26 and the inductance of the rotor core 36. When the rotor core 36 rotates, the rotor holder 31 fixed to the outer periphery of the rotor core 36 rotates together. The inner cylinder 35 of the rotor holder 31 is rotatably supported by the stator 2 via a bearing 42. Since the stator 2 is fixed to the swing arm 5 with bolts 24, the rotor holder is fixed to the swing arm 5 and the axle 8. 31 rotates around the axle 8 to generate a predetermined driving torque.

The driving torque of the rotor holder 31 is transmitted to the wheel 10 of the wheel 9 via the power transmission unit 50. Since the wheel 10 is rotatably supported on the axle 8 by the bearing 12, the wheel 9 rotates around the axle 8. The rotor 3 is continuously rotated by switching the coil 26 to be excited according to the rotational angle position of the rotor core 36.
Here, when the wheel 9 rotates and the prime mover travels, the wheel 9 receives a load from the road surface. This load mainly acts as an upward force and acts on the wheel 10 to displace the wheel 10 and the axle 8. At this time, the buffer member 52 of the power transmission unit 50 is deformed so as to absorb the deviation between the axis of the wheel 10 and the axis of the in-wheel motor 1. On the other hand, since the power transmission unit 50 continues to transmit the rotation of the rotor holder 31 to the wheel 10, the in-wheel motor 1 can continuously rotate the rotor 3.

According to this embodiment, the stator 2 is fixed directly to the swing arm 5 so as to be separated from the axle 8, and the rotor 3 is rotatably supported by the stator 2, so that the stator is fixed to the axle as in the prior art. Therefore, it is not necessary to design in consideration of the tolerance between the stator and the rotor and the tolerance when the rotor is attached to the axle via the bearing, and the gap between the rotor core and the stator can be reduced. In particular, since the rotor holder 31 is directly supported by the stator 2 via the bearing 42 and the rotor core 36 is press-fitted into the rotor holder 31, the gap 39 between the stator 2 and the rotor core 36 is adjusted in advance based on the inner diameter reference of the stator 2 before being assembled to the prime mover. It becomes possible to do. Therefore, the gap 39 can be made small and the workability of the adjustment process of the gap 39 is improved.
Further, since the driving torque is directly transmitted to the wheel 10 by the power transmission unit 50, the wheel 9 can be efficiently driven to rotate. When an external force is applied to the wheel 9 from the road surface or the like, the buffer member 52 of the power transmission unit 50 absorbs the displacement due to the external force, so that the external force is hardly applied to the in-wheel motor 1. For this reason, it is not necessary to set the gap 39 in advance in view of the external force, and an increase in driving torque due to the reduction of the gap 39 is expected.

  Since the in-wheel motor 1 is configured as a switched reluctance motor, a permanent magnet is not required. Therefore, the structure can be simplified and can be manufactured at low cost. Further, stable performance can be exhibited even when rotated at high speed or rotated at high temperature. In order to obtain a sufficient driving torque with a switched reluctance motor having such advantages, it is necessary to reduce the gap between the rotor core and the stator. According to this embodiment, the gap 39 can be reduced. Therefore, the advantages of the switched reluctance motor can be fully exhibited.

Note that the present invention can be widely applied without being limited to the above-described embodiment.
For example, the in-wheel motor 1 may be an outer rotor type DC brushless motor. Even in this case, since the gap can be reduced, a high driving torque can be obtained.
The power transmission unit 50 may have a configuration in which the rotor holder 31 and the wheel 10 are connected by a closely wound coil spring. In this case, the coil spring serves as a buffer member. The coil spring has a function of transmitting a driving torque on the in-wheel motor 1 side to the wheel 10 and absorbing a fluctuation of the wheel 10 due to an external force. Further, a buffer member that is slidable with respect to either the rotor holder 31 or the wheel 10 may be provided, and the sliding amount may be reset when the rotor holder 31 rotates once.
Further, the electric vehicle is not limited to a prime mover. The in-wheel motor 1 may be provided on at least one wheel of a vehicle having two or more wheels such as a four-wheel vehicle. Even with such a vehicle, the same effect as described above can be obtained.

It is a disassembled perspective view of the vehicle drive part containing the in-wheel motor which concerns on this Embodiment. It is a cross-sectional view of FIG. (A) It is sectional drawing orthogonal to an axial direction, (b) It is an enlarged view of IIIb.

Explanation of symbols

1 In-wheel motor (in-wheel motor for electric vehicles)
2 Stator 3 Rotor 5 Swing arm (suspension)
10 Wheel 25 Salient pole (saliency)
26 Winding 31 Rotor holder 38 Salient pole (saliency)
42 Bearing 50 Power transmission part 51 Boss 52 Buffer member (elastic member)

Claims (3)

In an in-wheel motor for an electric vehicle having a rotor having a rotor core fixed to a rotor holder and a stator,
The electric motor is characterized in that the stator is fixed to a suspension, the rotor holder is held inside the stator via a bearing, and a power transmission unit is provided for transmitting rotation of the rotor to a wheel via a buffer member. In-wheel motor for vehicles.   The said power transmission part consists of the boss | hub which protruded a part of said rotor holder, and the elastic member inserted between the outer periphery of the said boss | hub, and the hole formed in the said wheel. The in-wheel motor for electric vehicles as described. The rotor core and the stator each have a salient pole structure, and are configured to supply a current to a winding wound around the salient pole of the stator based on rotor position information. An in-wheel motor for an electric vehicle described in 1.

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