CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of PCT international application Ser. No. PCT/JP2019/026425 filed on Jul. 3, 2019 which designates the United States, incorporated herein by reference, and which is based upon and claims the benefit of priority from Japanese Patent Application No. 2018-127332 filed on Jul. 4, 2018, the entire contents of which are incorporated herein by reference.

FIELD

The present disclosure relates to a rolling bearing unit to support a vehicle wheel.

BACKGROUND

Conventional vehicle wheels are supported by a suspension through a rolling bearing unit. A structure in which the rolling bearing unit has a contactless power supply system is known (see Patent Literature 1).

The rolling bearing unit of Patent Literature 1 includes a power receiving coil provided on the inner side of a rotary-side inner ring in a vehicle width direction, and a covering member covering the inner side of the power receiving coil in the vehicle width direction. A power supply coil is disposed on the inner side of the covering member in the vehicle width direction.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Patent Application Laid-open Publication No. 2018-1769

Technical Problem

The rolling bearing unit of Patent Literature 1 has a power receiving coil disposed on the inner side, in the vehicle width direction, of the inner ring and has a power supply coil disposed on the inner side, in the vehicle width direction, of the covering member (cap) covering the power receiving coil. This structure increases the width of the rolling bearing unit along the vehicle width direction and thus increases the overall size of the rolling bearing unit.

For the foregoing reasons, there is a need for a rolling bearing unit the structure of which is advantageous in reducing the size of the unit.

SUMMARY

A rolling bearing unit according to a first aspect of the present invention, includes: an inner ring member having a recess on a first side in an axial direction along a rotation axis, the recess being recessed toward a second side in the axial direction; an outer ring member disposed on an outer periphery side of the inner ring member; a rolling body disposed between the inner ring member and the outer ring member and rotatably supporting the inner ring member with respect to the outer ring member; a transmitter capable of transmitting at least one of electric power or a signal, at least a part of the transmitter being accommodated inside the recess of the inner ring member; and a covering member that is supported by the first side of the outer ring member in the axial direction, covers the first side of the inner ring member in the axial direction, and fixes the transmitter.

According to the first aspect of the present invention, at least a part of the transmitter is accommodated inside the recess of the inner ring member along the axial direction, and thus the first side of the inner ring member in the axial direction is kept from projecting in the axial direction. This can reduce the entire length of the rolling bearing unit in the axial direction, thereby preventing an increase in the overall size of the unit.

In a rolling bearing unit according to a second aspect of the present invention, the covering member has a through-hole, the transmitter has a projection on the first side in the axial direction, the projection projects toward the first side and is fittable into the through-hole of the covering member, and the transmitter is fixed to the covering member with the projection fitted in the through-hole.

According to the second aspect of the present invention, the transmitter is connected with the covering member with the projection fitted in the through-hole, which enables effective holding of the transmitter. Since the inner ring member, which is a rotary member, is disposed on the outer periphery side of the transmitter, which is a stationary member, it is difficult to hold the transmitter. To address this, the transmitter is connected with the covering member, which is a stationary member. This structure enables effective holding of the transmitter.

In a rolling bearing unit according to a third aspect of the present invention, a center axis of the transmitter is along the rotation axis of the inner ring member with the projection fitted in the through-hole.

According to the third aspect of the present invention, the center axis of the transmitter is along the rotation axis of the inner ring member. This alignment can reduce interference of the inner peripheral surface of the recess with the outer peripheral surface of the transmitter during rotation of the inner ring member.

Furthermore, this alignment can reduce the distance between the inner peripheral surface of the recess of the inner ring member and the outer peripheral surface of the transmitter in the radial direction, which allows the inner ring member to have a larger thickness, thereby increasing the rigidity thereof. The center axis of the transmitter can be aligned with the rotation axis of the inner ring member by carrying out a simple task such as fitting the projection of the transmitter in the through-hole of the covering member.

In a rolling bearing unit according to a fourth aspect of the present invention, a sealing member annularly continuous around the rotation axis is interposed between a portion on an outer periphery side of the projection of the transmitter on the first side in the axial direction and a portion on an outer periphery side of the through-hole of the covering member.

According to the fourth aspect of the present invention, the sealing member provides waterproof even when water enters through the gap between the projection and the through-hole.

More specifically, with the projection fitted in the through-hole, a gap can be produced between the projection and the through-hole, and water can enter through the gap. The sealing member in an annular shape is therefore interposed between the outer periphery side of the projection and the outer periphery side of the through-hole, thereby, if water enters through the gap, stopping the water from further spreading to the outer peripheral side from the sealing member.

Advantageous Effects of Invention

According to an aspect of the present invention, a size-reduced rolling bearing unit is obtained.

