Worm reduction gear and steering system

Patent metadata

Field	Value
Publication number	US-9878735-B2
Application number	US-201615149950-A
Country	US
Kind code	B2
Filing date	May 9, 2016
Priority date	May 21, 2015
Publication date	Jan 30, 2018
Grant date	Jan 30, 2018

Abstract

A worm reduction gear satisfies following relational Formula (1) and Formula (2):

3≧ D 2/ D 1≧1.7  (1)

0.1°≦α−β≦0.5°  (2)

where D 1 is an outside diameter of a worm, D 2 is an outside diameter of a hob for cutting a worm wheel to form tooth spaces, and α is a pressure angle of the worm wheel and β is a pressure angle of the worm at an intermeshing pitch circle of the worm and the worm wheel.

First claim

What is claimed is:

1. A worm reduction gear comprising:
a worm; and
a worm wheel including tooth spaces that mesh with the worm, wherein following relational Formula (1) and Formula (2) are satisfied:
3≧ D 2/ D 1≧1.7  (1)

0.1°≦α−β≦0.5°  (2)

where D 1 is an outside diameter of the worm, D 2 is an outside diameter of a hob for cutting the worm wheel to form the tooth spaces, and α is a first acute angle formed by a reference line extending along a radial direction of the worm wheel with a worm wheel tooth flank and β is a second acute angle formed by the reference line with the worm tooth flank at an intermeshing pitch circle of the worm and the worm wheel.

2. A steering system comprising:
an electric motor for auxiliary steering; and
the worm reduction gear as claimed in claim 1 that reduces rotation of the electric motor.

Assignees

• Jtekt Corp

Inventors

• Kikuchi Arata

Classifications

• B23F5/22

  the tool being a hob for making spur gears · CPC title

• F16H55/08

  Profiling · CPC title

• B23F5/24

  the tool being a hob for making bevel gears · CPC title

• B62D3/10

  with worm engaging in sector or roller gear · CPC title

• B62D5/0454 Primary

  Worm gears · CPC title