Speed reducer for vehicle

Patent metadata

Field	Value
Publication number	US-10415683-B2
Application number	US-201615365615-A
Country	US
Kind code	B2
Filing date	Nov 30, 2016
Priority date	Dec 21, 2015
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

The present invention relates to a speed reducer for a vehicle. The speed reducer of an electric power steering system includes a worm and a worm wheel, wherein the worm wheel includes: a boss having an empty space into which a steering shaft is inserted; a gear part integrally formed with the outer circumferential surface of the boss and having crests and roots formed on the outer circumferential surface thereof so as to be engaged with the worm; and a heat conduction member provided on the side of the boss and the gear part to support the roots and the boss to conduct, to the boss, frictional heat generated from the gear part. Accordingly, the speed reducer releases frictional heat from the worm wheel to the boss to prevent wear and noise caused by expansion of the worm wheel.

First claim

What is claimed is:

1. A speed reducer for a vehicle, the speed reducer comprising a worm and a worm wheel,
wherein the worm wheel comprises:
a boss having an empty space into which a steering shaft is inserted;
a gear part integrally formed with an outer circumferential surface of the boss and having crests and roots formed on an outer circumferential surface of the gear part thereof so as to be engaged with the worm; and
a heat conduction member provided on one side of the boss and the gear part to support the roots and the boss to conduct, to the boss, frictional heat generated from the gear part,
wherein the heat conduction member includes a plurality of gear support parts protruding from an outer peripheral portion of the heat conduction member at a tilt angle with respect to an axial axis of the steering shaft wherein each crest of the gear part has opposite concave sides at which the crest is connected with the roots on opposite sides thereof, and each gear support part has a width that decreases and then increases again.

2. The speed reducer of claim 1 , wherein the heat conduction member comprises a connecting part formed in a plate shape having an empty space therein and supporting ends of the roots at an outer end thereof, and a boss support part protruding from an inner end of the connecting part in an axial direction of the steering shaft and supported on the boss.

3. The speed reducer of claim 2 , wherein a plurality of coupling recesses are formed in an outer peripheral portion of the connecting part to correspond to the roots, the coupling recesses being circumferentially spaced apart from each other.

4. The speed reducer of claim 2 , wherein the heat conduction member has a the plurality of gear support parts protruding protrude from an outer end of the connecting part in the axial direction of the steering shaft, the plurality of gear support parts being provided in the crests and circumferentially spaced apart from each other.

5. The speed reducer of claim 1 , wherein the plurality of gear support parts have a constant width.

6. The speed reducer of claim 1 , wherein each gear support part has ribs protruding outwardly from opposite circumferential ends thereof in a radial direction of the worm wheel such that the heat conduction member effectively radiates heat generated from portions engaged with the worm shaft of and the worm wheel.

7. The speed reducer of claim 1 , wherein each gear support part has ribs protruding outwardly and inwardly from opposite circumferential ends thereof in a radial direction of the worm wheel such that the heat conduction member effectively radiates heat generated from portions engaged with the worm shaft of and the worm wheel.

8. The speed reducer of claim 2 , wherein a groove is concavely formed in a side surface of the boss on which the heat conduction member is supported, and an end of the boss support part is inserted into, and supported by, the groove.

9. The speed reducer of claim 2 , wherein the boss support part has a bent portion formed at one end thereof to support a side surface of the boss.

10. The speed reducer of claim 2 , wherein the boss support part is supported by a positioning section concavely formed in an insertion hole into which the steering shaft is inserted.

11. The speed reducer of claim 1 , wherein the heat conduction member is formed in a plate shape having an empty space therein,
an outer end of the heat conduction member supports ends of the roots at the outer end thereof, and
an inner end of the heat conduction member makes contact with an outer circumferential surface of the steering shaft at the inner end thereof.

12. The speed reducer of claim 11 , wherein the heat conduction member has a plurality of gear support parts protruding from the outer end thereof in the axial direction of the steering shaft, the plurality of gear support parts being are provided in the crests and circumferentially spaced apart from each other.

13. The speed reducer of claim 1 , wherein the boss has a plurality of stoppers formed on the outer circumferential surface thereof and circumferentially spaced apart from each other to prevent the gear part from spinning with no traction.

14. The speed reducer of claim 1 , wherein each crest of the gear part has opposite concave sides at which the crest is connected with the roots on opposite sides thereof, and each gear support part has a width that varies.

15. The speed reducer of claim 1 , wherein each gear support part has ribs protruding outwardly or inwardly from opposite circumferential ends thereof in a radial direction of the worm wheel such that the heat conduction member effectively radiates heat generated from portions engaged with the worm and the worm wheel.

Assignees

• Mando Corp

Inventors

• Park Jooyeol

Classifications

• F16H55/24

  Special devices for taking up backlash · CPC title

• F16H55/22 Primary

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

• F16H57/0498

  Worm gearings · CPC title

• B62D5/0409

  Electric motor acting on the steering column · CPC title

• F16H55/06 Primary

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