Reducer of electric power steering apparatus

Patent metadata

Field	Value
Publication number	US-2017166239-A1
Application number	US-201615365550-A
Country	US
Kind code	A1
Filing date	Nov 30, 2016
Priority date	Dec 15, 2015
Publication date	Jun 15, 2017
Grant date	—

Abstract

A reducer of an electric power steering apparatus comprises a worm wheel and a worm shaft connected to a motor shaft, the worm wheel and the worm shaft being engaged with each. The worm wheel includes: a ring-shaped hub into which the steering shaft is inserted and having a plurality of outer protrusions formed on the outer peripheral side thereof; a teeth-shaped part, engaged with the worm shaft and formed on the outer peripheral surface thereof, and inner protrusions, formed on the inner peripheral surface thereof, protruding in a radial direction, and formed in the circumferential direction; a ring-shaped insert ring inserted into the inner side of the teeth-shaped part and having support protrusions formed on the outer peripheral side thereof; and a boss integrally injection-molded between the outer peripheral side of the hub and the inner peripheral side of the teeth-shaped part.

First claim

What is claimed is:

1 . A reducer of an electric power steering apparatus, the reducer comprising a worm wheel and a worm shaft connected to a motor shaft, the worm wheel and the worm shaft being engaged with each other to provide an auxiliary steering power to a steering shaft,
wherein the worm wheel comprises: a ring-shaped hub into which the steering shaft is inserted and having a plurality of outer protrusions formed on an outer peripheral side thereof, the plurality of outer protrusions being spaced in a circumferential direction; a teeth-shaped part including gear teeth which are engaged with the worm shaft and are formed on an outer peripheral surface thereof, and inner protrusions which are formed on an inner peripheral surface thereof, protrude in a radial direction, and are formed in the circumferential direction; a ring-shaped insert ring inserted into the inner side of the teeth-shaped part and having support protrusions formed on an outer peripheral side thereof; and a boss which is integrally injection-molded between an outer peripheral side of the hub and an inner peripheral side of the teeth-shaped part.

2 . The reducer of claim 1 , wherein the teeth-shaped part is integrally injection-molded with the insert ring.

3 . The reducer of claim 2 , wherein the insert ring includes a plurality of support protrusions connected in the circumferential direction.

4 . The reducer of claim 3 , wherein the support protrusions have a width decreasing outward in the radial direction.

5 . The reducer of claim 4 , wherein the support protrusions include end protrusions protruding toward both sides in the circumferential direction at the radially outermost portion.

6 . The reducer of claim 5 , wherein a plurality of connection protrusions connected to the end protrusions are formed on both side surfaces of the support protrusions.

7 . The reducer of claim 6 , wherein the support protrusions include outer peripheral surface protrusions on an outer peripheral surface between the end protrusions.

8 . The reducer of claim 1 , wherein the teeth-shaped part and the boss are formed by mixing one polyamide resin among polyamide 6, polyamide 66, polyamide 46, and polyamide 12 and 25 to 50 wt % of glass fiber.

9 . A reducer of an electric power steering apparatus, the reducer comprising a worm wheel and a worm shaft connected to a motor shaft, the worm wheel and the worm shaft being engaged with each other to provide an auxiliary steering power to a steering shaft,
wherein the worm wheel comprises: an insert disc including a small diameter portion having a shaft connection hole formed at a central portion thereof, and a large diameter portion having support protrusions formed on an outer peripheral side thereof, the steering shaft being inserted in the shaft connection hole; and a teeth-shaped part integrally injection-molded on the outer peripheral side of the insert disc, the teeth-shaped part including gear teeth which are engaged with the worm shaft and are formed on an outer peripheral surface thereof, and concave groove parts which are formed on an inner peripheral surface thereof, the support protrusions of the large diameter portion being inserted in the concave groove parts.

10 . The reducer of claim 9 , wherein the insert disc includes a connection part connecting the small diameter portion and the large diameter portion in a radial direction, and the connection part is formed to be stepped with the small diameter portion and the large diameter portion in an axial direction.

11 . The reducer of claim 9 , wherein the teeth-shaped part is integrally injection-molded with the insert disc while surrounding one side surface and the other side surface of the large diameter portion.

12 . The reducer of claim 11 , wherein the insert disc includes a plurality of support protrusions connected in a circumferential direction.

13 . The reducer of claim 12 , wherein the support protrusions have a width decreasing outward in the radial direction.

14 . The reducer of claim 13 , wherein the support protrusions include end protrusions protruding toward both sides in the circumferential direction at the radially outermost portion.

15 . The reducer of claim 14 , wherein a plurality of connection protrusions connected to the end protrusions are formed on both side surfaces of the support protrusions.

16 . The reducer of claim 15 , wherein the support protrusions include outer peripheral surface protrusions on an outer peripheral surface between the end protrusions.

17 . The reducer of claim 9 , wherein the teeth-shaped part is formed by mixing one polyamide resin among polyamide 6, polyamide 66, polyamide 46, and polyamide 12 and 25 to 50 wt % of glass fiber.

Assignees

• Mando Corp

Inventors

• Kim Jong Han
• An Hee Chul

Classifications

• F16H55/06

  Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties · CPC title

• B62D5/04 Primary

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

• B62D3/04

  of worm type · CPC title

• F16H2055/065

  Moulded gears, e.g. inserts therefor · CPC title

• F16H55/22 Primary

  for transmissions with crossing shafts, especially worms, worm-gears · CPC title