Speed reducer
A speed reducer relating to one aspect of the present disclosure includes: an internal gear having a casing and a plurality of outer pins, where the casing surrounds a main axis, and the outer pins are rotatably arranged in pin grooves provided on an inner periphery of the casing; an external gear meshing with the internal gear; an eccentric body for oscillating the external gear; a carrier rotatable relative to the casing; and a main bearing having an inner sliding surface and an outer sliding surface, where the inner sliding surface is rotatable integrally with the casing, and the outer sliding surface is rotatable integrally with the carrier. One of the inner and outer sliding surfaces is made of resin, and the other of the inner and outer sliding surfaces is made of a thermally conductive material that is more wear-resistant than the resin.
1. A speed reducer comprising:
a casing configured to surround a main axis;
an internal gear integrally formed with the casing;
an external gear configured to mesh with the internal gear;
an eccentric body configured to oscillate the external gear;
a carrier configured to be rotatable relative to the casing; and
a main bearing configured to be arranged between the casing and the carrier, and to rotatably support the carrier relative to the casing,
wherein the internal gear includes an internal gear body integrated into the casing, and a plurality of internal tooth pins configured to mesh with the external gear,
wherein the plurality of internal tooth pins are configured to rotatably arrange in pin grooves formed on an inner peripheral surface of the internal gear body,
wherein the main bearing is a plain bearing having an inner sliding surface and an outer sliding surface that are in contact with each other, the inner sliding surface is formed on an inner peripheral surface of a metal ring being rotatable integrally with the casing, the outer sliding surface is formed on an outer peripheral surface of the carrier,
wherein one of the inner and outer sliding surfaces is made of resin, and the other of the inner and outer sliding surfaces is made of a thermally conductive material that has a higher wear-resistant than the resin, and
wherein the plurality of internal tooth pins and the metal ring are made of a material that has a higher thermal conductivity and a higher wear-resistant than the resin.
2. The speed reducer of claim 1 , wherein the carrier is made of the resin.
3. The speed reducer of claim 2 , wherein the inner sliding surface is made of the thermally conductive material, and
wherein, in a direction extending along the main axis, the inner sliding surface is positioned to overlap the outer pins.
4. The speed reducer of claim 1 , wherein the inner and outer sliding surfaces have a groove formed therein that is not in communication with an internal space having the external gear housed therein.
5. The speed reducer of claim 1 , wherein the metal ring is arranged to overlap with respect to the plurality of internal tooth pins along a radial direction of the casing.