Speed reduction or speed increasing apparatus

Patent metadata

Field	Value
Publication number	US-10281008-B2
Application number	US-201615569128-A
Country	US
Kind code	B2
Filing date	Apr 12, 2016
Priority date	May 25, 2015
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

A speed reduction apparatus supports a third crown gear that undergoes wave motion. The speed reduction apparatus includes: a first crown gear; a second crown gear; a third crown gear having opposing teeth facing the first crown gear and opposing teeth facing the second crown gear, back to back; and cam units and that cause the third crown gear to undergo wave motion. The cam units and have a first cam on the first crown gear side with respect to the third crown gear, and a second cam on the second crown gear side with respect to the third crown gear. The first and second cams sandwich the third crown gear. A first rolling element between the first cam and the third crown gear is capable of rolling motion, and a second rolling element between the second cam and the third crown gear is capable of rolling motion.

First claim

The invention claimed is:

1. A speed reduction or speed increasing apparatus, comprising:
a first crown gear fixed to a housing;
a second crown gear fixed to an output portion and rotatable with respect to the housing;
a third crown gear having opposing teeth facing the first crown gear and opposing teeth facing the second gear, back to back with respect to each other; and
a cam unit configured to incline the third crown gear with respect to the first and second crown gears in such a manner that the third crown gear engages with the first crown gear and the third crown gear engages with the second crown gear, and to cause the third crown gear to undergo wave motion in such a manner that locations of contact move in a circumferential direction,
wherein:
the cam unit includes a first cam placed on the first crown gear side with respect to the third crown gear, and a second cam placed on the second crown gear side with respect to the third crown gear,
the first cam and the second cam sandwich the third crown gear,
a first rolling element is disposed between the first cam and the third crown gear in such a manner as to be capable of rolling motion,
a second rolling element is disposed between the second cam and the third crown gear in such a manner as to be capable of rolling motion,
the first and second cams are fixed to an input shaft so as not to be rotatable,
the first cam is directly rotatably supported by a first bearing disposed between the first crown gear and the first cam, and
the second cam is directly rotatably supported by a second bearing disposed between the second crown gear and the second cam.

2. The speed reduction or speed increasing apparatus according to claim 1 , wherein the first and second cams are fixed to the input shaft which penetrates the first and second cams and the third crown gear.

3. The speed reduction or speed increasing apparatus according to claim 2 , wherein:
the first and second cams include a first inclined surface and a second inclined surface parallel to each other, the first and second inclined surfaces being inclined with respect to an axis of the first and second cams,
a first rolling element rolling groove and a second rolling element rolling groove that are circular as viewed from a direction orthogonal to the first and second inclined surfaces are formed in the first and second inclined surfaces, and
circular third and fourth rolling element rolling grooves facing the first and second rolling element rolling grooves are formed back to back in the third crown gear.

4. The speed reduction or speed increasing apparatus according to claim 3 , wherein:
the opposing teeth of the first, second, and third crown gears alternately include top portions and bottom portions in the circumferential direction,
the top portion is of a convex shape based on a part of a side surface of a cone, and
the bottom portion is of a concave shape based on a part of a side surface of a cone.

5. The speed reduction or speed increasing apparatus according to claim 2 , wherein:
the opposing teeth of the first, second, and third crown gears alternately include top portions and bottom portions in the circumferential direction,
the top portion is of a convex shape based on a part of a side surface of a cone, and
the bottom portion is of a concave shape based on a part of a side surface of a cone.

6. The speed reduction or speed increasing apparatus according to claim 2 , wherein the input shaft is a straight input shaft.

7. The speed reduction or speed increasing apparatus according to claim 1 , wherein:
the first and second cams include a first inclined surface and a second inclined surface parallel to each other, the first and second inclined surfaces being inclined with respect to an axis of the first and second cams,
a first rolling element rolling groove and a second rolling element rolling groove that are circular as viewed from a direction orthogonal to the first and second inclined surfaces are formed in the first and second inclined surfaces, and
circular third and fourth rolling element rolling grooves facing the first and second rolling element rolling grooves are formed back to back in the third crown gear.

8. The speed reduction or speed increasing apparatus according to claim 7 , wherein:
the opposing teeth of the first, second, and third crown gears alternately include top portions and bottom portions in the circumferential direction,
the top portion is of a convex shape based on a part of a side surface of a cone, and
the bottom portion is of a concave shape based on a part of a side surface of a cone.

9. The speed reduction or speed increasing apparatus according to claim 7 , wherein the center of the first rolling element rolling groove of the first cam and the center of the second rolling element rolling groove of the second cam are displaced from the axis of the first and second cams in such a manner that the center of the wave motion of the third crown gear is on the axis.

10. The speed reduction or speed increasing apparatus according to claim 9 , wherein:
the opposing teeth of the first, second, and third crown gears alternately include top portions and bottom portions in the circumferential direction,
the top portion is of a convex shape based on a part of a side surface of a cone, and
the bottom portion is of a concave shape based on a part of a side surface of a cone.

11. The speed reduction or speed increasing apparatus according to claim 1 , wherein:
the opposing teeth of the first, second, and third crown gears alternately include top portions and bottom portions in the circumferential direction,
the top portion is of a convex shape based on a part of a side surface of a cone, and
the bottom portion is of a concave shape based on a part of a side surface of a cone.

12. The speed reduction or speed increasing apparatus according to claim 11 , wherein a position of the apices of the cones agree with a position of the center of the wave motion of the third crown gear.

Assignees

• Thk Co Ltd

Inventors

• Saito Hideo
• Mizutani Yuichi

Classifications

• F16H1/321

  the orbital gear being nutating · CPC title

• F16C19/10 Primary

  for axial load mainly · CPC title

• F16H2200/0043

  the gear ratios comprising four forward speeds · CPC title

• F16H53/02

  Single-track cams for single-revolution cycles; Camshafts with such cams · CPC title

• F16C33/585

  of raceways, e.g. ribs to guide the rollers · CPC title