Worm reduction gear and steering mechanism

Patent metadata

Field	Value
Publication number	US-9902421-B2
Application number	US-201615133790-A
Country	US
Kind code	B2
Filing date	Apr 20, 2016
Priority date	Apr 30, 2015
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

In a worm reduction gear, a second bearing that supports a second end of a worm shaft and a guide member are housed in a holding hole in a housing. A bias member biases the second end of the worm shaft toward the worm wheel (in a second direction). The guide member is elastically fitted in the holding hole in the housing to guide movement of the second end via the second bearing. A slit is fanned in the guide member. Stress is relieved which is exerted on the guide member when the guide member is elastically fitted in the holding hole.

First claim

What is claimed is:

1. A worm reduction gear comprising:
a housing with a holding hole formed therein;
a worm shaft including a first end coupled to an electric motor and a second end positioned on the opposite side of the worm shaft from the first end in an axial direction, the worm shaft being housed in the housing;
a worm wheel that meshes with the worm shaft;
a first bearing held by the housing to support the first end so that the first end is rotatable;
a second bearing that supports the second end so that the second end is rotatable;
a bias member that directly or indirectly biases the second end toward the worm wheel; and
a guide member having a slit and elastically fitted in the holding hole in the housing to directly or indirectly guide movement of the second end.

2. The worm reduction gear according to claim 1 , wherein the guide member includes a C-shaped fitting portion that has a pair of circumferential ends between which the slit is formed, and that is elastically fitted in the holding hole.

3. The worm reduction gear according to claim 1 , wherein the guide member is formed of resin.

4. The worm reduction gear according to claim 1 , wherein a protruding portion provided on one of the guide member and the housing or a member held by the housing engages with a recessed portion formed in other of the guide member and the housing or the member held by the housing to regulate rotation of the guide member in a circumferential direction of the holding hole.

5. The worm reduction gear according to claim 1 , wherein the guide member includes a stopper portion that regulates a distance that the second end moves away from the worm wheel.

6. The worm reduction gear according to claim 1 , further comprising a positioning portion provided on the housing or a member held by the housing to position the guide member in the axial direction of the worm shaft.

7. The worm reduction gear according to claim 1 , further comprising a receiving-seat forming member that forms a receiving seat disposed on an outer side of at least one of the second end and the second bearing in the axial direction and that is provided integrally with the outer ring of the second bearing, wherein
the bias member is disposed adjacent to at least one of the second end and the second bearing in the axial direction and between the housing and the receiving seat and is configured to bias the second end toward the worm wheel via the receiving-seat forming member and the second bearing.

8. A steering apparatus that transmits power of an electric motor to a steering shaft via the worm reduction gear according to claim 1 .

Assignees

• Jtekt Corp

Inventors

• Kawamura Naofumi

Classifications

• F16H57/039

  Gearboxes for accommodating worm gears · CPC title

• B62D5/0409 Primary

  Electric motor acting on the steering column · CPC title

• F16H57/021

  Shaft support structures, e.g. partition walls, bearing eyes, casing walls or covers with bearings · CPC title

• F16H2057/0213

  Support of worm gear shafts · CPC title

• F16H2057/127

  using springs · CPC title