Planetary traction drive transmission

• US 6,406,399 B1
• Filed: 07/28/2000
• Issued: 06/18/2002
• Est. Priority Date: 07/28/2000
• Status: Expired due to Term

• Current Assignee: The Timken Company
• Original Assignee: The Timken Company
• Inventors: Ai, Xiaolan
• Primary Examiner(s): Marmor, Charles A.
• Assistant Examiner(s): Pang, Roger
• Application Number:
  US09/627,675
• Time in Patent Office: 690 Days
• Field of Search: 475/183, 475/197, 475/331, 475/334, 475/335, 475/336, 475/348, 475/184, 475/190, 475/193, 475/342
• US Class Current: 475/183
• CPC Class Codes: F16H 13/06 with members having orbital motion
• CPC Class Codes: F16H 2001/2881 comprising two axially spaced central gears, i.e. ring or sun gear, engaged by at least one common orbital gear wherein one of the central gears is forming the output

Abstract

A planetary traction drive transmission has a sun roller provided with two inner raceways which are presented outwardly and taper downwardly away from each other. It also has two outer rings located within a housing, with the rings surrounding the sun roller and having tapered raceways presented inwardly toward the tapered raceways of the sun roller. In addition the transmission has planet rollers which are organized in two rows, there being a separate row within each ring. The rollers have tapered side faces along which they contact the raceways of the sun roller and the rings. They are also organized in pairs, with a roller of each row forming a pair. The rollers of a pair contact each other at beveled end faces on the rollers, and thus each roller of the pair serves to back and axially position the other roller of the pair. At all lines of contact between the rollers and the raceways and between the rollers themselves pure rolling contact, characterized by the absence of spinning, exists. In one embodiment the raceways of the sun roller are locked together and relative rotation occurs between the outer rings. In another embodiment the outer rings are locked together and relative rotation occurs between the raceways of the sun roller. Each embodiment provides high speed and torque ratios in a very compact package.

Claims

1. A traction drive transmission which is organized about a center axis, said transmission comprising:

a sun roller;

first and second inner raceways mounted on the sun roller and being tapered such that their large diameter ends are presented toward each other;

first and second outer raceways tapered such that their large diameter ends are presented toward each other, the first outer raceway being located around the first inner raceway and the second outer raceway being located around the second inner raceway, one of the first raceways being rotatable relative to its corresponding second raceway and the other of the first raceways being generally locked with respect to its corresponding second raceway;

first planet rollers arranged in a row between the first raceways and having tapered side faces which contact the first inner and outer raceways and second planet rollers arranged in a row between the second raceways and having tapered side faces that contact the second inner and outer raceways, the first and second planet rollers being arranged in pairs, with the first planet roller of any pair backing and serving to axially position the second backing roller of the pair and vice versa; and

a carrier connected to the first and second planet rollers.

2. A traction drive transmission according to claim 1 wherein pure rolling contact characterized by the absence of spinning exists between:

a. the first inner raceway and the first rollers

b. the first outer raceway and the first rollers

c. the second inner raceway and the second rollers

d. the second outer raceway and the second rollers

e. the first and second rollers of each pair.

3. A traction drive transmission according to claim 1 wherein

a. the first inner raceway lies in a conical envelope having its apex at a first point along the center axis;

b. the first outer raceway lies in a conical envelope having its apex at the first point on the center axis;

c. the second inner raceway lies in a conical envelope having its apex at a second point along the center axis; and

d. the second outer raceway lies in a conical envelope having its apex at the second point along the center axis.

4. A traction drive transmission according to claim 3 wherein

a. the side faces of the first rollers lie in conical envelopes having their apices at the first point along the center axis;

b. the side faces of the second rollers lie in conical envelopes having their apices at the second point along the center axis;

c. the first rollers revolve about first axes that intersect the center axis at the first point;

d. the second rollers revolve about second axes that intersect the center axis at the second point;

e. the first and second axes for the first and second rollers for any pair of first and second rollers intersect at a third point.

5. A traction drive transmission according to claim 4 wherein

a. the envelopes of the first and second inner races intersect at a fourth point;

b. the first and second rollers of each pair have end faces where they contact each other, and

c. the end faces of each pair of first and second rollers contact each other along a straight line connecting the third and fourth points.

6. A traction drive transmission according to claim 4 wherein:

a. the envelopes of the first and second outer raceways intersect at a fourth point;

b. the first and second rollers of each pair have end faces where they contact each other, and

c. the end faces of each pair of first and second rollers contact each other along a straight line connecting the third and fourth points.

7. A traction drive according to claim 1 wherein the second outer raceway rotates relative to the first outer raceway.

8. A traction drive transmission according to claim 7 and further comprising an outer ring which carries the second outer raceway, and an end disk connected to the outer ring and rotatable with it.

9. A traction drive transmission according to claim 1 wherein the second inner raceway rotates relative to the first inner raceway.

10. A traction drive transmission according to claim 1 and further comprising a housing;

first and second outer rings located in the housing with the first outer raceway being on the first outer ring and the second outer raceway being on the second ring.

11. A traction drive according to claim 10 wherein the housing and at least one of the outer rings have opposed ramps;

and further comprising rolling elements located between the ramps of the housing and said one outer ring, the ramps being oriented such that the rolling elements move up them and urge said one outer ring axially toward the other outer ring when relative rotation occurs between said one ring and the housing.

12. A planetary traction drive transmission which is organized about a center axis, said transmission comprising:

a sun roller having first and second inner raceways which are tapered and arranged such that their large diameter ends are presented toward each other;

a first outer ring having a first outer raceway presented toward the first inner raceway; and

a second outer ring having a second outer raceway presented toward the second inner raceway;

the first and second rings being detached such that relative rotation can occur between the rings, the first and second outer raceways being tapered and oriented such that their large diameter ends are presented toward each other;

first planet rollers located in a row between the sun roller and the first outer ring, with each having a tapered side face and an end face, the side faces of the first roller contacting the first inner and outer raceways;

second planet rollers located in a row between the sun roller and the second outer ring, with each having a tapered side face and an end face, the side faces of the second rollers contacting the second inner and second outer raceways, each second roller being located opposite one of said first rollers, so that the first and second rollers are arranged in pairs, the end face on the second roller of any pair bearing against the end face of the first roller of that pair; and

a carrier coupled to the first and second rollers.

13. A traction drive transmission according to claim 12 wherein the inner raceways of the sun roller are fixed in position with respect to each other.

14. A traction drive transmission according to claim 12 wherein pure rolling contact characterized by the absence of spinning exists between:

a. the first inner raceway and the first rollers;

b. the first outer raceway and the first rollers;

c. the second inner raceway and the second rollers;

d. the second outer raceway and the second rollers;

e. the end faces of the first and second rollers of each pair.

15. A traction drive transmission according to claim 12 wherein

a. the first inner raceway lies in a conical envelope having its apex at a first point along the center axis;

b. the first outer raceway lies in a conical envelope having its apex at the first point on the center axis;

c. the second inner raceway lies in a conical envelope having its apex at a second point along the center axis; and

d. the second outer raceway lies in a conical envelope having its apex at the second point along the center axis.

16. A traction drive transmission according to claim 15 wherein

a. the side faces of the first rollers lie in envelopes having their apices at the first point along the center axis;

b. the side faces of the second rollers lie in envelopes having their apices at the second point along the center axis;

c. the first rollers revolve about first axes that intersect the center axis at the first point;

d. the second rollers revolve about second axes that intersect the center axis at the second point;

e. the first and second axes for the first and second rollers for any pair of first and second rollers intersect at a third point.

17. A traction drive transmission according to claim 16 wherein

a. the envelopes of the first and second inner races intersect at a fourth point;

and

b. the end faces of each pair of first and second rollers contact each other along a straight line connecting the third and fourth points.

18. A planetary traction drive transmission that is organized about a center axis, said transmission comprising:

a first sun roller having its axis along the center axis and further having a first inner raceway that is tapered and presented outwardly away from the center axis;

a second sun roller having its axis along the center axis, but being detached from the first sun roller such that one of the sun rollers can rotate relative to the other sun roller, the second sun roller having a second inner raceway that is tapered and presented away from the center axis, the large diameter end of the second inner raceway being presented toward the large diameter end of the first inner raceway;

a first outer ring located around the first sun roller and having a first outer raceway that is tapered and presented inwardly toward the first inner raceway;

a second outer ring located around the second sun roller and having a second outer raceway that is tapered and presented inwardly toward the second inner raceway, the large diameter end of the second outer raceway being presented toward the large diameter end of the first outer raceway;

first planet rollers located in a row between the first sun roller and the first outer ring, with each having a tapered side face and an end face, the side faces of the first rollers contacting the first inner and outer raceways;

second planet rollers located in a row between the second sun roller and the second outer ring, with each having a tapered side face and an end face, the side faces of the second rollers contacting the second inner and second outer raceways, each second roller being located opposite a first roller so that the first and second rollers are arranged in pairs, the end face on the second roller of any pair bearing against the end face of the first roller of that pair; and

a carrier coupled to the first and second rollers.

19. A traction drive transmission according to claim 18 wherein the first and second outer rings are locked such that they do not rotate relative to each other.

20. A traction drive transmission according to claim 18 wherein pure rolling contact characterized by the absence of spinning exists between:

a. the first inner raceway and the first rollers;

b. the first outer raceway and the first rollers;

c. the second inner raceway and the second rollers;

d. the second outer raceway and the second rollers; and

e. the first and second rollers of each pair.

21. A traction drive transmission according to claim 18 wherein

a. the first inner raceway lies in a conical envelope having its apex at a first point along the center axis;

b. the first outer raceway lies in a conical envelope having its apex at the first point on the center axis;

c. the second inner raceway lies in a conical envelope having its apex at a second point along the center axis; and

d. the second outer raceway lies in a conical envelope having its apex at the second point along the center axis.

22. A traction drive transmission according to claim 21 wherein

a. the side faces of the first rollers lie in conical envelopes having their apices at the first point along the center axis;

b. the side faces of the second rollers lie in conical envelopes having their apices at the second point along the center axis;

c. the first rollers revolve about first axes that intersect the center axis at the first point;

d. the second rollers revolve about second axis that intersect the center axis at the second point; and

e. the first and second axes for the first and second rollers of for any pair of first and second rollers intersect at a third point.

23. A traction drive transmission according to claim 22 wherein

a. the envelopes of the first and second outer raceways intersect at a fourth point;

and

b. the end faces of each pair of first and second roller contact each other along a straight line connecting the third and fourth points.