Cycloidal speed reducer, in-wheel motor drive device, and vehicle motor drive device

A cycloidal speed reducer comprising:

• a casing;
• an input shaft having one end arranged in said casing;
• a disk-shaped eccentric member eccentric with respect to an axis of said input shaft and coupled to the one end of the input shaft;
• a revolution member supported by said eccentric member, to make a revolution motion around said axis together with a rotation of said input shaft;
• a rolling bearing arranged between an inner circumference of said revolution member and an outer circumference of said eccentric member, and a bearing internal gap of said roller bearing being larger than zero;
• an outer circumference engagement member supported by said casing and engaging with an outer circumference part of said revolution member to cause the revolution member to make a rotation motion;
• and
• an output shaft engaging with said revolution member to extract the rotation motion, wherein
• said rolling bearing has a rolling body, an inner ring member mounted on the outer circumference of said eccentric member, and a lubricant oil hole penetrating from an inner diameter surface of the inner ring member to an outer circumference track surface thereof to supply a lubricant oil to the outer circumference track surface of the inner ring member being in rolling contact with said rolling body, and
• said lubricant oil hole is arranged in a non-load range in which a bearing load is not applied from said output shaft and said outer circumference engagement member to said revolution member, in the outer circumference track surface of said rolling bearing, wherein
• the inner ring member of the rolling bearing has:
• i) a non-load range which does not receive the bearing load and is larger than 180 degrees, and
• ii) a load range which receives the bearing load and is smaller than 180 degrees, and further wherein
• the input shaft has an axis oil path along its axis, the eccentric member has a lubricant oil path from the axis oil path toward the radial outer side of the eccentric member, and
• an annular groove is provided between the eccentric member and the inner ring member, the annular groove circumferentially extending and connecting the lubricant oil path and the lubricant oil hole.