Worm gear for a worm gear mechanism of a motor vehicle steering system made from fibre reinforced plastic with a targeted orientation of the fibres

Patent metadata

Field	Value
Publication number	US-11225283-B2
Application number	US-201816646702-A
Country	US
Kind code	B2
Filing date	Sep 27, 2018
Priority date	Oct 2, 2017
Publication date	Jan 18, 2022
Grant date	Jan 18, 2022

Abstract

A worm gear for a worm gear mechanism of a motor vehicle steering system includes a carrier body and a multiplicity of teeth with tooth surfaces. The teeth point radially outward and the carrier body is formed from a plastic including reinforcement fibers and has a multiplicity of ribs with rib surfaces which point radially outward from a central encircling ring-shaped web of the worm gear. The teeth are applied to the ribs of the carrier body by injection molding, and the reinforcement fibers are oriented, wherein the multiplicity of reinforcement fibers, in terms of their orientation, follow the adjacent rib surfaces of the carrier body and/or the adjacent tooth surfaces of the teeth.

First claim

What is claimed is:

1. A worm gear for a worm gear mechanism of a motor vehicle steering system, comprising:
a carrier body formed from a plastic comprising reinforcement fibers, the carrier body comprising:
a central encircling ring-shaped web;
a multiplicity of ribs with rib surfaces that point radially outward from the ring-shaped web; and
a multiplicity of teeth that point radially outwardly, the teeth each having tooth surfaces;

wherein the teeth are applied to the ribs of the carrier body by injection molding; and
wherein the reinforcement fibers are non-cross-linked and wherein at least 50% of the reinforcement fibers are oriented to follow the adjacent rib surfaces of the carrier body and/or adjacent tooth surfaces of the teeth.

2. The worm gear of claim 1 wherein the carrier body has reinforcement ribs that extend radially from the encircling ring-shaped web in the direction of an axis of rotation of the worm gear.

3. The worm gear of claim 2 wherein the carrier body is arranged on a hub of the worm gear and on a ring-shaped edge region adjoining the hub in a radial direction, wherein the reinforcement ribs project from a lateral surface of the ring-shaped edge region.

4. A worm gear for a worm gear mechanism of a motor vehicle steering system, comprising:
a central encircling ring-shaped web; and
a multiplicity of teeth that point radially outward from the encircling ring-shaped web, the teeth each including tooth surfaces;
wherein the worm gear is a single piece, plastic construction that comprises reinforcement fibers that are non-cross-linked and that are oriented unidirectionally to follow adjacent tooth surfaces.

5. The worm gear of claim 4 wherein the reinforcement fibers are oriented, in a cross section of the worm gear, along a tooth profile of the teeth.

6. The worm gear of claim 4 wherein the reinforcement fibers in a region of the teeth below the tooth surfaces a depth of between 0 mm and 1 mm, are oriented, in a cross section of the worm gear, along a tooth profile of the teeth.

7. The worm gear of claim 4 wherein the reinforcement fibers are oriented parallel to the tooth surfaces in a longitudinal direction.

8. The worm gear of claim 4 wherein the reinforcement fibers are composed of synthetic resin.

9. The worm gear of claim 8 wherein the reinforcement fibers include one or more of polyamide, polyacetal, saturated polyester, polyether, or ether ketone.

10. The worm gear of claim 4 where the reinforcement fibers comprise at least one type of fibers composed of metal fibers, carbon fibers, or glass fibers.

11. A worm gear mechanism for a motor vehicle steering system comprising the worm gear of claim 4 and a worm which engages with the worm gear.

12. A method for producing a single-component worm gear for a worm gear mechanism of a motor vehicle steering system, comprising a multiplicity of teeth which project radially outward, wherein the teeth have in each case one rib, which ribs extend radially outward from a central encircling ring-shaped web of the worm gear, the method comprising:
providing a mold for the injection molding of the worm gear; and
injecting a synthetic resin with reinforcement fibers into the mold by means of a nozzle and a runner, such that more than 75% of the reinforcement fibers are oriented to follow an adjacent tooth surface.

13. The method of claim 12 wherein a single gate point is provided which is arranged in the region of a hub, such that the teeth are filled radially.

14. The method of claim 12 comprising forming the ribs and the teeth separately, wherein both the ribs and the teeth contain the reinforcement fibers.

15. The method of claim 12 wherein the synthetic resin is injected in a way that prevents cross-linking of the reinforcement fibers.

16. The method of claim 12 comprising forming the teeth in a way that prevents the reinforcement fibers from projecting from a surface of the teeth.

17. The worm gear of claim 1 wherein the reinforcement fibers are present in the ribs.

18. The worm gear of claim 1 wherein more than 75% of the reinforcement fibers are oriented to follow the adjacent tooth surfaces of the teeth.

19. The worm gear of claim 1 wherein more than 85% of the reinforcement fibers are oriented to follow the adjacent tooth surfaces of the teeth.

20. The worm gear of claim 1 wherein the reinforcement fibers of the teeth follow the adjacent tooth surfaces of the teeth without projecting out of the teeth and into the ribs, wherein the reinforcement fibers of the ribs follow the adjacent rib surfaces without projecting out of the ribs and into the teeth.

Assignees

• Thyssenkrupp Presta Ag
• Thyssenkrupp Ag

Inventors

• Ernstson Gernot
• Peter Manuel

Classifications

• 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

• F16H57/0006

  Vibration-damping or noise reducing means specially adapted for gearings (devices for varying tension of belts, ropes or chains with damping means F16H7/0829; toothed members with construction providing vibration damping F16H55/14; reducing vibrations or noise of the gearbox casing F16H57/028; suppression of vibrations or noise of gear selectors F16H59/0208; control of hydrostatic fluid gearing preventing or reducing vibrations or noise F16H61/4183) · CPC title

• B62D5/0454 Primary

  Worm gears · CPC title

• F16H1/16

  comprising worm and worm-wheel · CPC title