Bending meshing type gear device

1. A bending meshing gear device comprising:

a wave generator;

an external gear which is bent and deformed by the wave generator; and

an internal gear which meshes with the external gear,

wherein the internal gear is formed of a resin,

wherein the external gear is formed of a metal a having a thermal conductivity higher than that of the resin and wear resistance higher than that of the resin,

wherein a tooth thickness of the internal gear is larger than a tooth thickness of the external gear in a meshing range of the external gear and the internal gear, and

wherein the tooth thickness is a dimension of a tooth in a direction orthogonal to a tooth length direction and a tooth trace direction.

2. The bending meshing gear device according to claim 1 ,

wherein in the meshing range, a minimum value of the tooth thickness of the internal gear is larger than a minimum value of the tooth thickness of the external gear.

3. The bending meshing gear device according to claim 1 ,

wherein at a center position of the meshing range in the tooth length direction, the tooth thickness of the internal gear is larger than the tooth thickness of the external gear.

4. The bending meshing gear device according to claim 1 ,

wherein in the meshing range, a minimum value of the tooth thickness of the internal gear is equal to or more than a maximum value of the tooth thickness of the external gear.

5. The bending meshing gear device according to claim 1 , further comprising:

a wave generator bearing which is disposed between the wave generator and the external gear,

wherein an inner peripheral surface of the external gear constitutes an outer ring-side rolling surface on which a rolling element of the wave generator bearing rolls.

6. The bending meshing gear device according to claim 5 ,

wherein an outer peripheral surface of the wave generator constitutes an inner ring-side rolling surface on which the rolling element of the wave generator bearing rolls.

7. A bending meshing gear device comprising:

a wave generator;

an external gear which is bent and deformed by the wave generator;

an internal gear which meshes with the external gear; and

an abutment member provided in contact with the external gear,

wherein the internal gear is formed of a resin,

wherein the external gear is formed of a high thermal conductivity material having a thermal conductivity higher than that of the resin and wear resistance higher than that of the resin,

wherein a tooth thickness of the internal gear is larger than a tooth thickness of the external gear in a meshing range between the external gear and the internal gear, and

wherein the tooth thickness is a dimension of the internal gear or the external gear in a direction orthogonal to a tooth length direction and a tooth trace direction,

wherein the abutment member is formed of a high thermal conductivity material having a thermal conductivity higher than that of the resin, and

wherein a portion of the abutment member is exposed to an external space of the bending meshing gear device.

8. The bending meshing gear device according to claim 7 ,

wherein the abutment member is a bearing housing in which a bearing supporting the wave generator is disposed.

9. The bending meshing gear device according to claim 1 , further comprising:

a bolt for connecting the internal gear and another member,

wherein the bolt is formed of a high thermal conductivity material having a thermal conductivity higher than that of the resin.

10. The bending meshing gear device according to claim 1 , further comprising:

a wave generator bearing disposed between the wave generator and the external gear,

wherein the wave generator and the wave generator bearing are formed of a high thermal conductivity material having a thermal conductivity higher than that of the resin.