Toothed belt and belt reduction gear including the same

Patent metadata

Field	Value
Publication number	US-9670985-B2
Application number	US-201514617790-A
Country	US
Kind code	B2
Filing date	Feb 9, 2015
Priority date	Aug 9, 2012
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

A toothed belt includes: a back portion; and a plurality of helical teeth provided on an inner periphery of the back portion and disposed at a fixed pitch in a belt longitudinal direction. An angle θ between a tooth trace direction of the helical teeth and a belt lateral direction is in a range of 7 degrees to 10 degrees, both inclusive. A ratio A of a thickness tb of the back portion to a tooth height hb of the helical teeth, which is given by A=100×tb/hb, is in a range of 120% to 240%, both inclusive.

First claim

What is claimed is:

1. A toothed belt for a power steering system, comprising:
a back portion comprised of an elastic material; and
a plurality of helical teeth provided on an inner periphery of the back portion and disposed at a fixed pitch in a belt longitudinal direction, wherein
an angle θ between a tooth trace direction of the helical teeth and a belt lateral direction is in a range of 7 degrees to 10 degrees, both inclusive, and
a ratio A of a thickness tb of the back portion to a tooth height hb of the helical teeth, which is given by A=100×tb/hb, is in a range of 120% to 240%, both inclusive.

2. The toothed belt of claim 1 , wherein the ratio A is in a range of 175% to 240%, both inclusive.

3. The toothed belt of claim 1 , wherein a total thickness of the belt is 3.88 mm or less.

4. The toothed belt of claim 1 , further comprising:
a cord embedded in the back portion so as to extend in the belt longitudinal direction.

5. The toothed belt of claim 4 , wherein the helical tooth has tooth rubber provided on the inner periphery of the back portion and tooth cloth covering an inner peripheral surface of the tooth rubber.

6. The toothed belt of claim 5 , wherein
each of the back portion and the tooth rubber mainly contains HNBR, CR, EPDM, or a mixture of two or more selected from HNBR, CR, and EPDM,
the cord is comprised of glass fiber, and
the tooth cloth is comprised of nylon.

7. The toothed belt of claim 1 , wherein the pitch P of the helical teeth is in a range of 2 mm to 3 mm, both inclusive.

8. The toothed belt of claim 1 , wherein a belt width W is in a range of 20 mm to 40 mm, both inclusive.

9. A belt reduction gear, comprising:
a drive pulley having a plurality of first helical teeth;
a driven pulley having a plurality of second helical teeth; and
a toothed belt for power steering, which includes a back portion comprised of an elastic material, and a plurality of third helical teeth provided on an inner periphery of the back portion so as to mesh with the first helical teeth and the second helical teeth and disposed at a fixed pitch in a belt longitudinal direction, and which is wound around the drive pulley and the driven pulley, wherein
an angle θ between a tooth trace direction of the third helical teeth and a belt lateral direction of the toothed belt is in a range of 7 degrees to 10 degrees, both inclusive, and
a ratio A of a thickness tb of the back portion to a tooth height hb of the third helical teeth, which is given by A=100×tb/hb, is in a range of 120% to 240%, both inclusive.

10. The belt reduction gear of claim 9 , wherein
the ratio A is in a range of 175% to 240%, both inclusive.

11. The belt reduction gear of claim 9 , wherein
a compression ratio B of a tooth height hb of the third helical teeth with respect to a groove depth hp of the drive pulley and a groove depth hp of the driven pulley, which is given by B=100×(hb−hp)/hb, is B≦1.4%, and
a ratio C of backlash BL between the toothed belt and the drive pulley and the driven pulley to the tooth pitch P of the third helical teeth, which is given by C=100×BL/P, is 1.7%≦C≦2.5%.

12. The belt reduction gear of claim 9 , further comprising:
a cord embedded in the back portion so as to extend in the belt longitudinal direction.

Assignees

• Bando Chemical Ind

Inventors

• Sekiguchi Yuji
• Nakashima Eijiro

Classifications

• B62D5/04

  electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear · CPC title

• F16G1/10 Primary

  with textile reinforcement · CPC title

• B62D3/02

  mechanical · CPC title

• B62D5/0424

  the axes of motor and final driven element of steering gear, e.g. rack, being parallel · CPC title

• F16H55/14

  Construction providing resilience or vibration-damping (F16H55/06 takes precedence) · CPC title