Electric power steering apparatus and method of manufacturing gear used therefor

• US 6,644,431 B2
• Filed: 10/25/2001
• Issued: 11/11/2003
• Est. Priority Date: 11/16/2000
• Status: Expired due to Fees

• Current Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Original Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Inventors: Shiina, Akihiko, Matsubara, Hideo, Minami, Mitsuharu, Kuze, Masashi
• Primary Examiner(s): Morris, Lesley D.
• Assistant Examiner(s): Lum, L.
• Application Number:
  US09/983,631
• Publication Number:
  US 20020056588A1
• Time in Patent Office: 747 Days
• Field of Search: 180/443, 180/444, 744/43, 743/88.PS, 74D/IG.10, 744/39, 744/46, 744/25
• US Class Current: 180/444
• CPC Class Codes: B62D 5/0409 Electric motor acting on the steering column
• CPC Class Codes: F16H 2055/065 Moulded gears, e.g. inserts therefor
• CPC Class Codes: F16H 55/06 Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties coatings for lubrication F16H57/041; producing gear wheels from plastics or substances in a plastic state B29D15/00; heat treatment C21D9/32; electrolytic surface treatment C25D; heating by electromagnetic field H05B6/00
• CPC Class Codes: F16H 55/22 for transmissions with crossing shafts, especially worms, worm-gears
• CPC Class Codes: Y10T 29/49472 Punching or stamping
• CPC Class Codes: Y10T 29/49474 Die-press shaping
• CPC Class Codes: Y10T 29/49986 Subsequent to metal working
• CPC Class Codes: Y10T 74/19828 Worm

Abstract

The support body engaged with the interior side of the tooth body provided at the worm wheel of the electric power steering apparatus comprises: a corrugates cylinder part-press-formed to have a plurality of concavities on the exterior side thereof and convexities to the interior formed by the concavities which are arranged in a peripheral direction; and a plate part an exterior edge of which is united with an end of the corrugated cylinder part, wherein the tooth body is engaged with the exterior side of the corrugated cylinder part. With the method of manufacturing the gear, synthetic resin of the tooth body can be deposited uniformly on the support body made of metal engaged with the interior of the tooth body, costs can be reduced, and the support body can be engaged with the tooth body without generating voids and weld marks.

Claims

1. An electric power steering apparatus for assisting steering by transmitting rotation of a steering assist motor to a steering mechanism via a driving gear and a driven gear having a ring-shaped tooth body made of synthetic resin meshing with said driving gear and a support body made of metal engaged with an interior side of said tooth body, the support body comprising:

a corrugated cylinder part press-formed to have a plurality of concavities on an exterior side thereof and convexities to an interior side formed by said concavities which are arranged in a peripheral direction; and

a plate part an edge of which is united with an end of said corrugated cylinder part.

2. The electric power steering apparatus according to claim 1, wherein the corrugated cylinder part is bent at a first ring groove part which is provided at the edge of the plate part.

3. The electric power steering apparatus according to claim 2,

the support body further comprising a mounting cylinder part which is bent at an interior edge of the plate part to be concentric with the corrugated cylinder part,

wherein the mounting cylinder part is bent at a second ring groove part which is provided at an interior edge of the plate part.

4. The electric power steering apparatus according to claim 3, the support body further comprising a ring concavity part which is provided at one end of the corrugated cylinder part.