Planetary gear device

1. A planetary gear device comprising:

a housing cover disposed at one end portion of a housing in an axis direction, the housing being configured to house a sun gear and a planetary gear inside the housing; and

a carrier cover disposed next to the housing cover in the axial direction in the inside, fixed to a carrier rotatably supporting planetary gear and configured to support a shaft of the planetary gear from one end portion side in the axial direction, wherein

one opposing part of a pair of opposing parts opposite to each other in the housing cover and the carrier cover includes a cone-shaped part whose diameter varies in the axial direction, and the other opposing part of the pair of opposing parts includes a sliding part configured to slide on a peripheral surface of the cone-shaped part with a same axis as an axis of the cone-shaped part;

wherein the cone-shaped part includes a cone-shaped recess whose center side is recessed with respect to an outer periphery side; and,

wherein the sliding part includes a cone-shaped protrusion whose center portion protrudes with respect to an outer periphery part.

2. The planetary gear device according to claim 1 ,

wherein the cone-shaped recess is a tapered surface whose center side is recessed; and

wherein the cone-shaped protrusion is a tapered surface whose center side is protruded.

3. The planetary gear device according to claim 1 , wherein the pair of opposing parts is disposed inside relative to an axis of the planetary gear in a radial direction of the sun gear.