Eccentrically oscillating type reduction gear

1. An eccentrically oscillating type reduction gear comprising:

an internal gear;

an external gear which meshes with the internal gear; and

an eccentric body which oscillates the external gear,

wherein the external gear is formed of a resin, and

wherein the internal gear comprises:

an internal gear main body which is formed of a resin, and

an outer pin which is rotatably disposed in a pin groove provided in the internal gear main body and is formed of a material having a thermal conductivity higher than that of a material constituting the internal gear main body.

2. The eccentrically oscillating type reduction gear according to claim 1 , further comprising:

a casing which integrally rotates with the internal gear;

a carrier which rotates relative to the casing; and

a main bearing which is disposed between the casing and the carrier,

wherein an outer ring of the main bearing is formed of a material having a thermal conductivity higher than that of the material constituting the internal gear main body, and

wherein the outer ring of the main bearing and the outer pin abut against each other in an axial direction or abut against each other via a spacer formed of a material having a thermal conductivity higher than that of the resin constituting the internal gear main body.

3. The eccentrically oscillating type reduction gear according to claim 2 ,

wherein a rolling element and an inner ring of the main bearing are formed of a material having a thermal conductivity higher than that of the material constituting the internal gear main body and the carrier is formed of a material having a thermal conductivity higher than that of the material constituting the internal gear main body.

4. The eccentrically oscillating type reduction gear according to claim 1 , wherein the internal gear main body is formed of the resin containing a reinforcing fiber.

5. The eccentrically oscillating type reduction gear according to claim 4 , wherein the internal gear main body is formed of a PEEK (polyetheretherketone) containing the reinforcing fiber.

6. The eccentrically oscillating type reduction gear according to claim 1 , wherein the outer pin is formed of a metal material.

7. The eccentrically oscillating type reduction gear according to claim 6 , wherein the outer pin is formed of an iron-based metal.

8. The eccentrically oscillating type reduction gear according to claim 1 , wherein the outer pin has a multilayer structure in which a core material is wrapped with a surface material.

9. The eccentrically oscillating type reduction gear according to claim 1 , wherein the external gear is formed of the resin containing a reinforcing fiber.

10. The eccentrically oscillating type reduction gear according to claim 9 , wherein the external gear is formed of a PEEK (polyetheretherketone) containing the reinforcing fiber.

11. The eccentrically oscillating type reduction gear according to claim 1 , wherein the external gear is formed of the resin having a heat-resistant temperature higher than that of the internal gear main body.

12. The eccentrically oscillating type reduction gear according to claim 1 , further comprising:

a casing which integrally rotates with the internal gear;

a carrier which rotates relative to the casing; and

a main bearing which is disposed between the casing and the carrier,

wherein the carrier and the main bearing are formed of a material having a thermal conductivity higher than that of the material constituting the internal gear main body, and

wherein the carrier is formed of a light metal.

13. The eccentrically oscillating type reduction gear according to claim 12 , wherein the carrier is formed of an aluminum-based metal.

14. The eccentrically oscillating type reduction gear according to claim 12 , further comprising:

an input shaft on which the eccentric body is provided,

wherein the carrier is formed of a metal material having a specific gravity smaller than that of the input shaft.

15. The eccentrically oscillating type reduction gear according to claim 12 , further comprising:

an inner pin which is inserted into an inner pin hole provided in the external gear and contributes to transmission of power between the carriers,

wherein the inner pin is formed of an iron-based metal.

16. The eccentrically oscillating type reduction gear according to claim 12 ,

wherein the carrier comprises a first carrier disposed on one side of the external gear in an axial direction and a second carrier disposed on the other side of the external gear in the axial direction,

wherein the first carrier and the second carrier are connected to each other via a carrier pin, and

wherein the carrier pin is formed of an iron-based metal.

17. The eccentrically oscillating type reduction gear according to claim 16 , further comprising:

a spacer which is externally fitted to the carrier pin and is configured to keep a gap between the first carrier and the second carrier at a predetermined distance,

wherein the spacer is formed of a resin.

18. The eccentrically oscillating type reduction gear according to claim 16 ,

wherein the first carrier is formed of a light metal, and

wherein the second carrier is formed of a resin.

19. The eccentrically oscillating type reduction gear according to claim 1 , further comprising:

a casing which integrally rotates with the internal gear;

a carrier which rotates relative to the casing; and

a main bearing which is disposed between the casing and the carrier,

wherein the internal gear main body and the external gear are formed of the resin containing a reinforcing fiber,

wherein the outer pin is formed of an iron-based metal,

wherein the main bearing is formed of an iron-based metal, and

wherein the carrier is formed of an aluminum-based metal.

20. The eccentrically oscillating type reduction gear according to claim 19 , wherein the internal gear main body and the external gear are formed of the resin containing a carbon fiber as the reinforcing fiber.