Joint for torque transmission and worm reduction gear

Patent metadata

Field	Value
Publication number	US-10738834-B2
Application number	US-201615561237-A
Country	US
Kind code	B2
Filing date	Apr 27, 2016
Priority date	Apr 28, 2015
Publication date	Aug 11, 2020
Grant date	Aug 11, 2020

Abstract

Circumferential rigidity of both axial end portions of each coupling-side convex portion is lower than circumferential rigidity of an axially intermediate portion of each coupling-side convex portion. The drive-side concave-convex portion is engaged with a half portion on the other axial side of the coupling-side concave-convex portion. The driven-side concave-convex portion is engaged with a half portion on one axial side of the coupling-side concave-convex portion.

First claim

The invention claimed is:

1. A torque-transmission joint is configured to transmit torque between one axial end portion of a drive shaft and the other axial end portion of a driven shaft arranged in series with each other in an axial direction, the torque-transmission joint comprising:
a coupling provided on one circumferential surface of inner and outer circumferential surfaces with a coupling-side concave-convex portion having coupling-side convex portions arranged at a plurality of circumferential places and protruding in a radial direction;
a drive-side transmission part provided at the one axial end portion of the drive shaft and is provided on one circumferential surface, which faces the coupling-side concave-convex portion, of inner and outer circumferential surfaces with a drive-side concave-convex portion having drive-side convex portions arranged at a plurality of circumferential places and protruding in a radial direction; and
a driven-side transmission part provided at the other axial end portion of the driven shaft and is provided on one circumferential surface, which faces the coupling-side concave-convex portion, of inner and outer circumferential surfaces with a driven-side concave-convex portion having driven-side convex portions arranged at a plurality of circumferential places and protruding in a radial direction;
wherein circumferential rigidity of both axial end portions of each coupling-side convex portion is lower than circumferential rigidity of an axially intermediate portion of each coupling-side convex portion,
wherein the drive-side concave-convex portion is engaged with a half portion on the other axial side of the coupling-side concave-convex portion, and the driven-side concave-convex portion is engaged with a half portion on one axial side of the coupling-side concave-convex portion, and
wherein both axial end portions of each coupling-side convex portion is provided with a thickness-reduced portion opening into both axial end surfaces of each coupling-side convex portion and an outer peripheral surface of the coupling.

2. The torque-transmission joint according to claim 1 ,
wherein both axial end surfaces of each coupling-side convex portion are formed with concave portions axially recessed.

3. The torque-transmission joint according to claim 1 ,
wherein at the state where the central axes of the drive shaft and the driven shaft are matched, the drive-side concave-convex portion is engaged with the half portion on the other axial side of the coupling-side concave-convex portion with a drive-side gap of which a circumferential width size increases towards the other axial side being interposed between the circumferential side surface of each drive-side convex portion and the circumferential side surface of each coupling-side convex portion, and
wherein at the state where the central axes of the drive shaft and the driven shaft are matched, the driven-side concave-convex portion is engaged with the half portion on one axial side of the coupling-side concave-convex portion with a driven-side gap of which a circumferential width size increases towards one axial side being interposed between the circumferential side surface of each driven-side convex portion and the circumferential side surface of each coupling-side convex portion.

4. The torque-transmission joint according to claim 3 ,
wherein the circumferential side surface of each coupling-side convex portion has a crowning shape inclined in a direction in which a circumferential width size of each coupling-side convex portion is greatest at an axially intermediate portion and decreases toward both axial end portions.

5. The torque-transmission joint according to claim 1 ,
wherein one circumferential surface of both the inner and outer circumferential surfaces of the coupling is formed with a coupling-side protrusion protruding in the radial direction, and
wherein the coupling-side protrusion is positioned between the drive-side transmission part and the driven-side transmission part in the axial direction.

6. The torque-transmission joint according to claim 1 ,
wherein the thickness-reduced portion comprises:
a triangular portion of which a width size decreases axially inwards from both axial end surfaces of each coupling-side convex portion; and
a rectangular portion connected to a tip end portion of the triangular portion and further extending axially inwards.

7. A worm reduction gear comprising:
a housing;
a worm wheel rotatably supported to the housing;
a worm rotatably supported to the housing at a state where worm teeth provided on an axially intermediate portion thereof are meshed with the worm wheel; and
an electric motor provided to rotatively drive the worm;
wherein the worm and an output shaft of the electric motor are connected by a torque-transmission joint so that torque can be transmitted therebetween, and
wherein the torque-transmission joint is the torque-transmission joint according to claim 1 .

Assignees

• Nsk Ltd

Inventors

• Oosawa Ryou
• Nishimura Nobuyuki

Classifications

• B62D5/0409 Primary

  Electric motor acting on the steering column · CPC title

• F16D3/54

  Couplings comprising a chain or strip surrounding two wheels arranged side by side and provided with teeth or the equivalent · CPC title

• H02K7/1166

  comprising worm and worm-wheel (structural association with bearings specially adapted for worm gear drives H02K7/081) · CPC title

• F16D3/74

  the intermediate member or members being made of rubber or other {rubber-like} flexible material · CPC title

• H02K7/003

  Couplings; Details of shafts (means for mounting rotors on shafts H02K1/28) · CPC title