In-wheel motor drive device

Patent metadata

Field	Value
Publication number	US-9914349-B2
Application number	US-201415109266-A
Country	US
Kind code	B2
Filing date	Dec 19, 2014
Priority date	Jan 8, 2014
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

Provided is an in-wheel motor drive device, including a casing configured to hold a motor part, a speed reduction part, and a wheel bearing part, the motor part including; a stator, which is fixed to the casing; a rotation shaft of a motor, which is rotatably supported on the casing through intermediation of rolling bearings; and a rotor, which is mounted to the rotation shaft of the motor. The rolling bearing has a radial internal clearance of from 8 μm to 25 μm before being mounted into the motor part. The rotation shaft of the motor is rotatably supported on the casing through intermediation of a plurality of rolling bearings. The rotation shaft of the motor and the rolling bearings configured to support the rotation shaft of the motor are fitted to each other by transition fit or interference fit.

First claim

The invention claimed is:

1. An in-wheel motor drive device comprising:
a motor part;
a speed reduction part;
a wheel bearing part; and
a casing configured to hold the motor part, the speed reduction part and the wheel bearing part, wherein
the motor part comprises:
a stator, which is fixed to the casing;
a rotation shaft of a motor, which is rotatably supported on the casing through intermediation of rolling bearings; and
a rotor, which is mounted to the rotation shaft of the motor, the speed reduction part comprises:
an input shaft of a speed reducer, which is rotationally driven by the rotation shaft of the motor; and
an output shaft of the speed reducer, which is configured to transmit rotation of the input shaft of the speed reducer, which is reduced in speed, to the wheel bearing part,

each of the rolling bearings has a radial internal clearance of from 8 μm to 25 μm before being mounted, and
each of the rolling bearings has an axial constant pressure preload applied thereto.

2. The in-wheel motor drive device according to claim 1 , wherein the axial constant pressure preload is applied by an elastic member, which is elastically deformable in an axial direction thereof.

3. The in-wheel motor drive device according to claim 1 , wherein each of the rolling bearings comprises ceramic balls as rolling elements.

4. The in-wheel motor drive device according to claim 1 , wherein each of the rolling bearings comprises a resin cage.

5. The in-wheel motor drive device according to claim 1 , further comprising a lubrication mechanism configured to supply lubricating oil to the motor part.

6. The in-wheel motor drive device according to claim 1 , wherein the speed reduction part further comprises:
a revolving member, which is rotatably held at an eccentric portion of the input shaft of the speed reducer, and is configured to perform revolving motion about a rotation axis center of the input shaft of the speed reducer along with the rotation of the input shaft of the speed reducer;
an outer periphery engagement member, which is engaged with an outer peripheral portion of the revolving member to cause rotational motion of the revolving member; and
a motion conversion mechanism, which is configured to convert the rotational motion of the revolving member into rotary motion about the rotation axis center of the input shaft of the speed reducer to transmit the rotary motion to the output shaft of the speed reducer.

7. An in-wheel motor drive device comprising:
a motor part;
a speed reduction part;
a wheel bearing part; and
a casing, wherein
the motor part comprises:
a stator, which is fixed to the casing;
a rotation shaft of a motor, which is rotatably supported on the casing through intermediation of a plurality of rolling bearings; and
a rotor, which is mounted to the rotation shaft of the motor,

the rotation shaft of the motor in the motor part is configured to rotationally drive an input shaft of a speed reducer in the speed reduction part,
the speed reduction part is configured to reduce a speed of rotation of the input shaft of the speed reducer to transmit the rotation to an output shaft of the speed reducer,
the wheel bearing part is connected to the output shaft of the speed reducer,
the rotation shaft of the motor and the plurality of rolling bearings configured to support the rotation shaft of the motor are fitted to each other by transition fit or interference fit,
the plurality of rolling bearings and the casing are fitted to each other by clearance fit, and
each of the plurality of rolling bearings has an axial constant pressure preload applied thereto.

8. The in-wheel motor drive device according to claim 7 ,
wherein the rotation shaft of the motor is supported on both sides thereof through intermediation of a pair of rolling bearings, and
wherein any one of the pair of rolling bearings is fixed by bringing a side surface of a holding member, which is fixed to the casing, into abutment against an end surface of an outer ring of the any one of the pair of rolling bearings.

9. The in-wheel motor drive device according to claim 8 , wherein the any one of the pair of rolling bearings, which is fixed by the holding member, corresponds to a bearing configured to support an end of the rotation shaft of the motor on a speed reduction part side.

10. The in-wheel motor drive device according to claim 8 , wherein the holding member comprises a hollow disc.

11. The in-wheel motor drive device according to claim 8 , wherein the holding member comprises:
a base portion, which is a hollow disc; and
a plurality of abutment portions, which project in a radially inward direction from the base portion.

Assignees

• Ntn Toyo Bearing Co Ltd

Inventors

• Kuroda Masaru
• Suzuki Kenichi
• Uchiyama Naoyuki

Classifications

• F16H57/0476

  Electric machines and gearing, i.e. joint lubrication or cooling or heating thereof · CPC title

• H02K5/1732

  radially supporting the rotary shaft at both ends of the rotor (H02K5/1737 takes precedence) · CPC title

• F16C25/083

  with resilient means acting axially on a race ring to preload the bearing · CPC title

• F16C43/04

  Assembling rolling-contact bearings · CPC title

• B60K2007/0092

  the motor axle being coaxial to the wheel axle · CPC title