Gear, reduction gear combination and electric power steering apparatus

• US 6,988,582 B2
• Filed: 01/10/2003
• Issued: 01/24/2006
• Est. Priority Date: 01/11/2002
• Status: Expired due to Fees

• Current Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Original Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Inventors: Murakami, Hiroaki, Machida, Tomomasa, Maekawa, Tomohiro, Joshita, Kaname, Tsutsui, Teruo, Kitami, Etsurou
• Primary Examiner(s): Lerner, Avraham
• Application Number:
  US10/340,538
• Publication Number:
  US 20040084865A1
• Time in Patent Office: 1,110 Days
• Field of Search: 180/443, 180/444, 180/446, 744/61, 744/09, 744/11, 744/40
• US Class Current: 180/444
• 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, at least one of the inner surface of the tooth body and the outer surface of the core body being non-circular and having at least one projection and one depression; and

a coupler of elastic material in the space between and engaging the at least one of the non-circular inner surface of the annular tooth body and the outer surface of the core body to couple the core body with the annular tooth body by engagement with the at least one projection and depression.

2. The gear according to claim 1, wherein the portions of the coupler that engage the non-circular portion of the at least one of the tooth body inner surface and core body outer surface form a limiting mechanism for limiting relative rotation between the annular tooth body and the coupler and relative rotation 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. The gear according to claim 1 wherein both the inner surface of the tooth body and the outer surface of the core body are non-circular and have at least one projection and depression engaged by the coupler of elastic material.

8. The gear according to claim 7 wherein the inner surface of the tooth body and the outer surface of the core body have a cruciform cross-section.

9. 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, at least one of the inner surface of the tooth body and the outer surface of the core body being non-circular and having at least one projection and one depression; and

a coupler of elastic material in the space between and engaging the at least one of the non-circular inner surface of the annular tooth body and the outer surface of the core body to couple the core body with the annular tooth body.

10. The reduction gear combination according to claim 9, wherein the portions of the coupler that engage the non-circular portion of the at least one of the tooth body inner surface and core body outer surface form a limiting mechanism for limiting relative rotation between the annular tooth body and the coupler and relative rotation between the core body and the coupler.

11. The reduction gear combination according to claim 10, 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. The reduction gear combination according to claim 9, wherein the annular tooth body is made of synthetic resin and the core body is made of metal.

14. The reduction gear combination according to claim 13, 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.

15. The reduction gear combination according to claim 9 wherein both the inner surface of the tooth body and the outer surface of the core body are non-circular and have at least one projection and depression engaged by the coupler of elastic material.

16. The reduction gear combination according to claim 15 wherein the inner surface of the tooth body and the outer surface of the core body have a cruciform cross-section.

17. 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, at least one of the inner surface of the tooth body and the outer surface of the core body being non-circular and having at least one projection and one depression; and

a coupler of elastic material in the space between and engaging the at least one of the non-circular inner surface of the annular tooth body and the outer surface of the core body to couple the core body with the annular tooth body by engagement with the at least one projection and depression.

18. The electric power steering apparatus according to claim 17, wherein the portions of the coupler that engage the non-circular portion of the at least one of the tooth body inner surface and core body outer surface form a limiting mechanism for limiting relative rotation between the annular tooth body and the coupler and relative rotation between the core body and the coupler.

19. The electric power steering apparatus according to claim 18, wherein the annular tooth body is made of synthetic resin and the core body is made of metal.

20. The electric power steering apparatus according to claim 19, 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.

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

22. The electric power steering apparatus according to claim 21, 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.

23. The electric power steering apparatus according to claim 17 wherein both the inner surface of the tooth body and the outer surface of the core body are non-circular and have at least one projection and depression engaged by the coupler of elastic material.

24. The electric power steering apparatus according to claim 23 wherein the inner surface of the tooth body and the outer surface of the core body have a cruciform cross-section.