Torque transmission joint and electric power steering apparatus

Patent metadata

Field	Value
Publication number	US-9718493-B2
Application number	US-201314355566-A
Country	US
Kind code	B2
Filing date	Jul 29, 2013
Priority date	Nov 1, 2012
Publication date	Aug 1, 2017
Grant date	Aug 1, 2017

Abstract

A shock-absorbing member comprises held sections located at a plurality of locations in a circumferential direction and comprising paired held sections and non-paired held sections, and is constructed to have a non-circular cylindrical shape in cross-section. Portions where outer-diameter side end sections of held sections that are adjacent to each other in the circumferential direction are made continuous by way of outer-diameter side cover sections, and portions where inner-diameter side end sections of held sections that are adjacent to each other in the circumferential direction are made continuous directly or by way of inner-diameter side cover sections, in an alternating sequence in the circumferential direction. Drive-side arm sections are placed between the non-paired held sections, driven-side arm sections are placed between the paired held sections, and the outer circumferential surfaces of the drive-side arm sections are covered by the outer-diameter side cover sections.

First claim

What is claimed is:

1. A torque transmission joint comprising:
a drive-side transmission member supported by an end section of a drive shaft concentrically with the drive shaft;
a driven-side transmission member supported by an end section of a driven shaft concentrically with the driven shaft and, arranged in series with the drive-side transmission member in an axial direction of the torque transmission joint; and
a shock-absorbing member made of an elastic material and provided between the drive-side transmission member and the driven-side transmission member;
the torque transmission joint transmitting torque between the end sections of the drive shaft and the driven shaft;
wherein
the drive-side transmission member comprises:
a drive-side base section supported by the end section of the drive shaft, and having a surface facing the driven-side transmission member; and
a plurality of drive-side arm sections provided on the surface of the drive-side base section intermittently in a circumferential direction of the torque transmission joint so as to protrude out in the axial direction, and each of the drive-side arm sections having paired side surfaces in the circumferential direction;
the driven-side transmission member comprises:
a driven-side base section supported by the end section of the driven shaft, and having a surface facing the drive-side transmission member; and
a plurality of driven-side arm sections provided on the surface of the driven-side base section intermittently in the circumferential direction so as to protrude out in the axial direction, and each of the driven-side arm sections having paired side surfaces in the circumferential direction;
the shock-absorbing member comprises combined held sections located at plural locations of the shock-absorbing member in the circumferential direction, the combined held sections comprising adjacent paired flat plate shaped held sections, inner-diameter side end sections of each of the paired flat plate shaped held sections being connected to each other directly or by an inner-diameter side cover section; and outer-diameter cover sections connecting outer-diameter side end sections of adjacent non-paired flat plate shaped held sections between the adjacent combined held sections, such that the held sections are connected on the inner-diameter side and the outer-diameter side alternately in the circumferential direction, and the shock-absorbing member being constructed so as to have a non-circular tube shape in a cross section thereof;
the drive-side arm sections and the driven-side arm sections are arranged in an alternating sequence in the circumferential direction, and the held sections are respectively arranged between the side surfaces of the drive-side arm sections and the driven-side arm sections that are adjacent to each other in the circumferential direction;
arm sections of one of the pluralities of arm sections being placed between the paired held sections, respectively, and arm sections of another of the pluralities of arm sections being places between the non-paired held sections, respectively, and outer circumferential surfaces of either of the drive-side arm sections or the driven-side arm sections are covered by the outer-diameter side cover sections which are exposed to an outside of the torque transmission joint; and
the shock-absorbing member is formed from two or more shock-absorbing pieces, including at least two types of shock-absorbing pieces with different elasticities, and the shock-absorbing pieces have held pieces that form the held sections; and cover pieces that form the outer-diameter side cover sections, with the shock-absorbing pieces layered in the axial direction.

2. The torque transmission joint according to claim 1 , wherein side surfaces in the circumferential direction of the held pieces of one of the shock-absorbing pieces which is more elastically deformable than the other shock-absorbing pieces protrude further in the circumferential direction than side surfaces in the circumferential direction of the held pieces of the other shock-absorbing pieces.

3. The torque transmission joint according to claim 1 , wherein the shock-absorbing pieces of the shock-absorbing member are joined together by engagement between an engaging section and an engaged section that are provided on the shock-absorbing pieces.

4. The torque transmission joint according to claim 1 , wherein a damper member for absorbing part of a thrust force that acts between the drive shaft and the driven shaft and transmitting another part of the thrust force that acts between the drive shaft and the driven shaft is provided on an inside of the shock-absorbing member.

5. The torque transmission joint according to claim 4 , wherein the damper member is integrally formed with at least one of the shock-absorbing pieces of the shock-absorbing member.

6. The torque transmission joint according to claim 1 , wherein the combined held sections are provided at four locations of the shock-absorbing member that are uniformly spaced in the circumferential direction, and the non-circular tube shape in the cross section of the shock-absorbing member is a cross cylindrical shape.

7. An electric power steering apparatus comprising:
a housing that is supported by a fixed portion of a vehicle body;
a rotating steering shaft that rotates as a steering wheel of the vehicle is rotated and applies a steering angle to steered wheels;
a worm wheel that is supported by part of the rotating steering shaft so as to be concentric with the rotating steering shaft, and rotates together with the rotating steering shaft;
a worm that comprises a worm shaft both end sections in an axial direction of the worm shaft being supported inside the housing by bearings so as to be able to rotate freely, and a middle section in the axial direction around which worm teeth that engage with the worm wheel are provided; and
an electric motor;
wherein the torque transmission joint according to claim 1 is provided between an output shaft of the electric motor and the worm shaft such that the torque transmission joint can transmit a torque between the output shaft acting as the drive shaft and the worm shaft acting as the driven shaft.

8. The torque transmission joint according to claim 1 , wherein the paired held sections each have a mirror symmetry about an imaginary plane that passes through a center axis of the torque transmission joint, and are inclined in a direction toward the imaginary plane with respect to a radial direction of the shock-absorbing member going toward an outside in the radial direction of the shock-absorbing member, and the side surfaces of the paired side surfaces of the drive-side arm sections, which are positioned on a front side in a direction of rotation of the drive shaft are inclined in a direction toward the front side in the direction of rotation with respect to the imaginary plane going toward the outside in the radial direction.

Assignees

• Nsk Ltd

Inventors

• Moriyama Seiichi
• Shibazaki Hiroshi
• Segawa Toru
• Yamamoto Takeshi
• Kojima Kazuhiko

Classifications

• F16D3/68 Primary

  the elements being made of rubber or similar material · CPC title

• B62D5/0454

  Worm gears · CPC title

• F16H1/16

  comprising worm and worm-wheel · CPC title

• B62D5/0409

  Electric motor acting on the steering column · CPC title

• F16D3/52

  comprising a continuous strip, spring, or the like engaging the coupling parts at a number of places · CPC title