US-12623486-B2 - Mecanum wheel

US12623486B2US 12623486 B2US12623486 B2US 12623486B2US-12623486-B2

Abstract

A wheel of the present disclosure includes a barrel holder, barrel support shafts, barrels, and bearings. The barrel holder is rotationally driven. The barrel support shafts arranged on the circumference of the barrel holder at an angle to a rotation axis of the barrel holder. The barrels are barrel-shaped rotating bodies. The barrels are rotatably supported on the corresponding barrel support shafts, and outer surfaces of the barrels contact a surface on which the wheel travels as the barrel holder rotates. The bearing supports the retainer. A groove is formed at least in a region of the outer circumferential surface of the barrel support shaft extending in the axial direction and including a radially inner projected area of the retainer.

Inventors

Kazuyoshi Suzuki
Takuya SHINKAI
Kenya TOMIYASU
See Wah MA
Ikuto GONJA

Assignees

NABTESCO CORPORATION

Dates

Publication Date: 20260512
Application Date: 20230316
Priority Date: 20220420

Claims (9)

1 . A mecanum wheel, comprising: a rotatable holder; a plurality of barrel support shafts arranged on a circumference of the rotatable holder at an angle to a rotation axis of the rotatable holder; barrels rotatably supported on each of the plurality of barrel support shafts, each of the barrels being a barrel-shaped rotating body, outer surfaces of the barrels sequentially contacting a surface on which the wheel travels as the rotatable holder rotates; and bearings disposed between the barrel support shafts and the barrels, each of the bearings rotatably supporting the corresponding barrel and having a retainer, wherein the bearing is disposed at an axially outer end of the barrel and encloses the barrel support shaft, wherein a first groove is provided at least in a region of an outer circumferential surface of the barrel support shafts, the region extends in an axial direction and includes a radially inner projected area of the retainer.
2 . The mecanum wheel of claim 1 , wherein the bearing includes: a first race abutting a first member in the axial direction, the first member being disposed on an opposite side of the rotatable holder in the axial direction with the bearing therebetween; a second race abutting a second member in the axial direction, the second member being disposed closer to the rotatable holder than the bearing in the axial direction; and a plurality of rolling elements disposed between the first race and the second race, the plurality of rolling elements rollably contacting the first race and the second race; wherein the retainer is disposed between the first race and the second race and supports the plurality of rolling elements, wherein the first groove is provided in the outer circumferential surface of the barrel support shafts, the first groove extends in the axial direction and crosses over an end portion of an inner end surface of the first race and an end portion of an inner end surface of the second race, and wherein the inner end surface of the first race and the inner end surface of the second race oppose each other.
3 . The mecanum wheel of claim 2 , wherein the first groove is provided in the outer circumferential surface of the barrel support shafts such that the first groove does not cross over an end portion of an outer end surface of the first race and an end portion of an outer end surface of the second race, and wherein the outer end surface of the first race and the outer end surface of the second race face away from the rolling elements in the axial direction.
4 . The mecanum wheel of claim 1 , wherein a recess dented inwardly in the axial direction is provided in an axial end portion of the barrel, wherein the bearing is housed in a bearing housing portion defined by the recess and the outer circumferential surface of the barrel support shaft, and wherein a second groove is provided at least in a region of an inner circumferential surface of the recess, the region extends in the axial direction and includes a radially outer projected area of the retainer.
5 . A mecanum wheel, comprising: a rotatable holder; a plurality of barrel support shafts arranged on a circumference of the rotatable holder at an angle to a rotation axis of the rotatable holder; barrels rotatably supported on each of the plurality of barrel support shafts, each of the barrels being a barrel-shaped rotating body, outer surfaces of the barrels contacting a surface on which the wheel travels as the rotatable holder rotates; and bearings disposed between the barrel support shafts and the barrels, each of the bearings rotatably supporting the corresponding barrel and having a retainer, wherein the bearing is disposed at an axially outer end of the barrel and encloses the barrel support shafts, wherein a recess dented inwardly in the axial direction is provided in an axial end portion of the barrel, wherein the bearing is housed in a bearing housing portion defined by the recess and the outer circumferential surface of the barrel support shafts, and wherein a second groove is provided at least in a region of an inner circumferential surface of the recess, the region extends in the axial direction and includes a radially outer projected area of the retainer.
6 . The mecanum wheel of claim 1 , wherein the bearing includes: a first race abutting a first member in the axial direction, the first member being disposed on an opposite side of the rotatable holder in the axial direction with the bearing therebetween; a second race abutting a second member in the axial direction, the second member being disposed closer to the rotatable holder than the bearing in the axial direction; a plurality of rolling elements disposed between the first race and the second race, the plurality of rolling elements rollably contacting the first race and the second race; wherein the retainer is disposed between the first race and the second race and supports the plurality of rolling elements, wherein a spacer block is disposed between an outer end surface of the second race, which faces away from the rolling elements in the axial direction and the rotatable holder, the spacer block being attached on the outer circumferential surface of the barrel support shafts, and wherein an elastic member is disposed between the spacer block and the second race, the elastic member contacts the spacer block, the outer end surface of the second race, and the outer circumferential surface of the barrel support shafts.
7 . A drive unit comprising: a mecanum wheel; and a drive device rotationally driving the mecanum wheel, wherein the mecanum wheel includes: a rotatable holder; a plurality of barrel support shafts arranged on a circumference of the rotatable holder at an angle to a rotation axis of the rotatable holder; barrels rotatably supported on each of the plurality of barrel support shafts, each of the barrels being a barrel-shaped rotating body, outer surfaces of the barrels contacting a surface on which the wheel travels as the rotatable holder rotates; and bearings disposed between the barrel support shafts and the barrels, each of the bearings rotatably supporting the corresponding barrel and having a retainer, wherein the bearing is disposed proximate an axially outer end of the barrel and encloses the barrel support shafts, and wherein a first groove is provided at least in a region of an outer circumferential surface of the barrel support shafts, the region extends in an axial direction and includes a radially inner projected area of the retainer.
8 . A transfer device, comprising: a mecanum wheel; a drive device rotationally driving the mecanum wheel; and a vehicle body supporting the mecanum wheel and the drive device, wherein the mecanum wheel includes: a rotatable holder; a plurality of barrel support shafts arranged on a circumference of the rotatable holder at an angle to a rotation axis of the rotatable holder; barrels rotatably supported on each of the plurality of barrel support shafts, each of the barrels being a barrel-shaped rotating body, outer surfaces of the barrels sequentially contacting a surface on which the wheel travels as the rotatable holder rotates; and bearings disposed between the barrel support shafts and the barrels, each of the bearings rotatably supporting the corresponding barrel and having a retainer, wherein the bearing is disposed at an axially outer end of the barrel and encloses the barrel support shafts, and wherein a first groove is provided at least in a region of an outer circumferential surface of the barrel support shafts, the region extends in an axial direction and includes a radially inner projected area of the retainer.
9 . The mecanum wheel of claim 5 , wherein the bearing includes: a first race abutting a first member in the axial direction, the first member being disposed on an opposite side of the rotatable holder in the axial direction with the bearing therebetween; a second race abutting a second member in the axial direction, the second member being disposed closer to the rotatable holder than the bearing in the axial direction; a plurality of rolling elements disposed between the first race and the second race, the plurality of rolling elements rollably contacting the first race and the second race; wherein the retainer is disposed between the first race and the second race and supports the plurality of rolling elements, wherein a spacer block is disposed between an outer end surface of the second race, which faces away from the rolling elements in the axial direction, and the rotatable holder, the spacer block being attached on the outer circumferential surface of the barrel support shafts, and wherein an elastic member is disposed between the spacer block and the second race, the elastic member contacts the spacer block, the outer end surface of the second race, and the outer circumferential surface of the barrel support shaft.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is based on and claims the benefit of priority from Japanese Patent Application Serial No. 2022-069635 (filed on Apr. 20, 2022), the contents of which are hereby incorporated by reference in their entirety. TECHNICAL FIELD The present disclosure relates to a wheel used for a transfer device, a drive unit, and a transfer device. BACKGROUND Mecanum wheels are known as wheels used for a transfer device. This wheel includes a plurality of barrels and a barrel holder. The barrels are barrel-shaped rotating bodies. The barrel holder supports the plurality of barrels rotatably on the circumference of the barrel holder. The barrel holder is rotationally driven by a drive device such as a motor (see, for example, Japanese Translation of PCT International Patent Application 2009-504465). The plurality of barrels are held on the circumference of the barrel holder at an angle to the holder rotation axis of the barrel holder. Such wheels are disposed at around the four corners of the transfer device. Each wheel located at the four corners of the transfer device is independently controlled by the drive device. That is, the transfer device can move freely in various directions by controlling the direction of rotation and torque of each wheel individually. The wheels on the left side and the wheels on the right side of the transfer device are set differently such that their barrels have the opposite inclination held on the circumference of the barrel holder. A pair of support flanges are provided at two axially outer ends of the barrel holder and extend outward in the radial direction of the barrel holder. A plurality of barrel support shafts extend between the pair of support flanges and are fixed thereon. The barrels are rotatably supported by the corresponding barrel support shaft and barrel holder via radial and thrust bearings. The thrust bearing is disposed in a bearing receiving portion between a circular recess formed at the axial end of the barrel and the outer surface of the barrel support shaft. The thrust bearing includes a first race, a second race, and a plurality of rolling elements. The first race contacts a member disposed on the bottom side of the bearing receiving portion in the bearing receiving portion. The second race contacts a member disposed on the support flange side of the barrel holder. The plurality of rolling elements rotatably contact with the first race and the second race. The plurality of rolling elements are rotatably supported by a retainer. The rolling elements and the retainer are disposed between the first and second races. In the above conventional wheel (mecanum wheel), once the barrel holder is rotationally driven by a drive device such as a motor, the outer surfaces of the barrels sequentially contact a traveling surface on which the wheel travels. The transfer device is propelled by receiving reaction force from the traveling surface. At this time, the contact position of each barrel where it contacts the ground surface moves continuously between one end and the other of the barrel in the axial direction as the barrel holder rotates. Thus, when the transfer device travels, a large thrust load is applied alternately to the thrust bearing disposed at axially one end of the barrel and the thrust bearing disposed at the other end of the barrel. When a large thrust load is applied to one thrust bearing, the thrust load on the other thrust bearing is reduced. This may displace the first and second races in a direction away from the plurality of rolling elements. If the separation of the first and second races from the rolling elements becomes large, the retainer may be displaced in the radial direction together with the rolling elements. In this case, there is a possibility that the retainer may interfere with surrounding components such as the barrel support shaft. To address this, for example, the clearance between the thrust bearing and a member (e.g., the member on the barrel holder side) that contacts the first and second races in the axial direction may be strictly controlled. However, this approach increases the manufacturing cost of the components and requires the manufacturer to perform complicated work to control the clearance. SUMMARY The present disclosure provides a wheel in which interference between a bearing retainer and surrounding members can be prevented without requiring strict clearance control between the members. The disclosure also provides a drive unit and transfer device thereof. (1) A wheel according to one aspect of the disclosure includes: a barrel holder rotationally driven; a plurality of barrel support shafts arranged on a circumference of the barrel holder at an angle to a rotation axis of the barrel holder; barrels rotatably supported on the corresponding barrel support shafts, each of the barrels being a barrel-shaped rotating body, outer surfaces of the barrels sequentially contacting a surface