Gear, reduction gear combination and electric power steering apparatus

• US 20040084865A1
• Filed: 01/10/2003
• Published: 05/06/2004
• Est. Priority Date: 01/11/2002
• Status: Active Grant

• Current Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Original Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Inventors: Murakami, Hiroaki, Maekawa, Tomohiro, Joshita, Kaname, Tsutsui, Teruo, Kitami, Etsurou, Machida, Tomomasa
• Granted Patent: US 6,988,582 B2
• Time in Patent Office: Days
• US Class Current: 280/93.513
• CPC Class Codes: B62D 5/0409 Electric motor acting on the steering column
• CPC Class Codes: F16D 1/06 for attachment of a member on a shaft or on a shaft-end attachment of marine propellers on shafts B63H23/34
• CPC Class Codes: F16D 2001/062 characterised by adaptors where hub bores being larger than the shaft
• CPC Class Codes: F16D 3/76 shaped as an elastic ring centered on the axis, surrounding a portion of one coupling part and surrounded by a sleeve of the other coupling part
• CPC Class Codes: F16F 15/126 consisting of at least one annular element surrounding the axis of rotation
• CPC Class Codes: F16H 1/16 comprising worm and worm-wheel
• CPC Class Codes: F16H 55/14 Construction providing resilience or vibration-damping F16H55/06 takes precedence
• CPC Class Codes: Y10T 74/19898 Backlash take-up

Abstract

A worm 1 is composed of an annular tooth body 11 having a tooth 10 on the outer surface thereof, a core body 12 inserted inside the annular tooth body 11; and an elastic coupler 13, which can be transformed in the radial direction, for coupling the core body 12 with the annular tooth body 11. The worm 1 is engaged with the worm wheel with the elastic coupler 13 being transformed in the radial direction in such a manner that a negative amount of backlash is generated at the engagement portion. This can be also employed for the worm wheel. With a reduction gear combination having this structure, the backlash amount at the engagement portion can be adjusted to a proper amount without selecting elements such as the worm and the worm wheel to be assembled.

Claims

1. A gear comprising:

an annular tooth body having a tooth on an outer surface thereof,

a core body inserted inside the annular tooth body; and

a coupler made of elastic material, which couples the core body with the annular tooth body.

2. The gear according to claim 1, further comprising a limiting mechanism for limiting relative turn between the annular tooth body and the coupler and relative turn between the core body and the coupler.

3. The gear according to claim 2, wherein the annular tooth body is made of synthetic resin and the core body is made of metal.

4. The gear according to claim 3, wherein the coupler is coupled with the core body via a coupling ring made of synthetic resin having larger rigidity than the elastic material of the coupler.

5. The gear according to claim 1, wherein the annular tooth body is made of synthetic resin and the core body is made of metal.

6. The gear according to claim 5, wherein the coupler is coupled with the core body via a coupling ring made of synthetic resin having larger rigidity than the elastic material of the coupler.

7. A reduction gear combination comprising a pinion and a gear wheel engaged with the pinion,

wherein at least one of the pinion and the gear wheel has:

an annular tooth body having a tooth on an outer surface thereof;

a core body inserted inside the annular tooth body; and

a coupler made of elastic material, which couples the core body with the annular tooth body.

8. The reduction gear combination according to claim 7, further comprising a limiting mechanism for limiting relative turn between the annular tooth body and the coupler and relative turn between the core body and the coupler.

9. The reduction gear combination according to claim 8, wherein the annular tooth body is made of synthetic resin and the core body is made of metal.

10. The reduction gear combination according to claim 9, wherein the coupler is coupled with the core body via a coupling ring made of synthetic resin having larger rigidity than the elastic material of the coupler.

11. The reduction gear combination according to claim 7, wherein the annular tooth body is made of synthetic resin and the core body is made of metal.

12. The reduction gear combination according to claim 11, wherein the coupler is coupled with the core body via a coupling ring made of synthetic resin having larger rigidity than the elastic material of the coupler.

13. An electric power steering apparatus comprising:

a reduction gear combination including a pinion and a gear wheel engaged with the pinion;

a steering assist motor connected with the pinion; and

a transmitting unit for transmitting rotation of the gear wheel associated with rotation of the motor to a steering mechanism,

wherein at least one of the pinion and the gear wheel has;

an annular tooth body having a tooth on an outer surface thereof,

a core body inserted inside the annular tooth body; and

a coupler made of elastic material, which couples the core body with the annular tooth body.

14. The electric power steering apparatus according to claim 13, further comprising a limiting mechanism for limiting relative turn between the annular tooth body and the coupler and relative turn between the core body and the coupler.

15. The electric power steering apparatus according to claim 14, wherein the annular tooth body is made of synthetic resin and the core body is made of metal.

16. The electric power steering apparatus according to claim 15, wherein the coupler is coupled with the core body via a coupling ring made of synthetic resin having larger rigidity than the elastic material of the coupler.

17. The electric power steering apparatus according to claim 13, wherein the annular tooth body is made of synthetic resin and the core body is made of metal.

18. The electric power steering apparatus according to claim 17, wherein the coupler is coupled with the core body via a coupling ring made of synthetic resin having larger rigidity than the elastic material of the coupler.