Tapered involute sector gear and variable ratio rack recirculating-ball style steering gearbox

Patent metadata

Field	Value
Publication number	US-9346490-B2
Application number	US-201314055163-A
Country	US
Kind code	B2
Filing date	Oct 16, 2013
Priority date	Oct 16, 2013
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

A recirculating-ball style gearbox for a vehicle steering system is provided. The gearbox has a rack with rack-teeth that are capable of providing variable ratio steering, where the rack-teeth are in mesh with the involute-teeth of a tapered sector gear. The involute-teeth of the sector gear have arrays of helical meshing lines extending across the meshing surfaces of the teeth, wherein the array of helical meshing lines have leads that decrease in length moving radially outward across the meshing surfaces.

First claim

What is claimed is:

1. A recirculating-ball style steering gearbox comprising:
a rack having rack-teeth capable of providing variable ratio steering; and
a tapered sector gear having involute-teeth in mesh with the rack-teeth, each involute-tooth having an array of helical meshing lines extending across a meshing surface, wherein the array of helical meshing lines has lead dimensions that decrease in length moving radially outward across the meshing surface.

2. The recirculating-ball style steering gearbox of claim 1 , wherein a mesh load between the tapered sector gear and rack is modifiable by adjusting a position of the sector gear longitudinally.

3. The recirculating-ball style steering gearbox of claim 1 , wherein the lengths of the leads decrease in steps.

4. The recirculating-ball style steering gearbox of claim 3 , wherein the lengths of the leads decrease by 100 mm to 300 mm at each step.

5. The recirculating-ball style steering gearbox of the claim 1 , wherein the tapered sector gear has 3 involute-teeth.

6. The recirculating-ball style steering gearbox of claim 1 , wherein linear movement of the rack is rotatably linked to a steering wheel of a vehicle via a worm gear and ball-nut.

7. The recirculating-ball style steering gearbox of claim 1 , wherein the tapered sector gear is pivotally linked to steerable road wheels of an automobile.

8. A sector gear for a recirculating-ball style steering system comprising:
at least one tapered involute-tooth having a meshing surface capable of contacting variable ratio rack teeth along an array of helices, the helices having lead dimensions that decrease in length moving radially outward across the meshing surface.

9. The sector gear of claim 8 , wherein a mesh load between the sector gear and a variable ratio rack is modifiable by adjusting a position of the sector gear longitudinally.

10. The sector gear of claim 8 , wherein the lengths of the leads decrease in steps.

11. The sector gear of claim 10 , wherein the lengths of the leads decrease by 100 mm to 300 mm at each step.

12. The sector gear of claim 8 , wherein the sector gear has 3 involute-teeth.

13. A gearbox comprising:
a rack having a least one rack-tooth with a concave meshing surface on a first side and a convex meshing surface on a second side; and
a tapered sector gear having at least one involute-tooth with a first tooth thickness at a first pitch circle adjacent a first side of the tooth larger than a second tooth thickness at a second pitch circle adjacent a second side of the tooth, wherein the at least one involute-tooth has an array of helical meshing lines extending across a sector tooth meshing surface, the array of helical meshing lines having lead dimensions that decrease in length moving radially outward across the sector tooth meshing surface.

14. The gearbox of claim 13 , wherein a mesh load between the tapered sector gear and rack is modifiable by adjusting a position of the sector gear longitudinally.

15. The gearbox of claim 13 , wherein the lengths of the leads decrease in steps.

16. The gearbox of claim 15 , wherein the lengths of the leads decrease by 100 mm to 300 mm at each step.

17. The gearbox of claim 13 , wherein the tapered sector gear has 3 involute-teeth.

Assignees

• Ford Global Tech Llc

Inventors

• Washnock Joseph
• Barry Jr Jackson E
• Killins Dale

Classifications

• B62D3/08

  using intermediate balls or the like · CPC title

• B62D5/24 Primary

  for worm type · CPC title

• F16H55/26

  Racks · CPC title

• Y10T74/1967

  Rack and pinion · CPC title

• Y10T74/19949

  Teeth · CPC title