US Patent 11878747 Speed reducer, drive unit and steering assisting device

A speed reducer includes an input rotating body, a base block, a speed reducing mechanism unit and a tubular case. The input rotating body is rotatable when acted upon by power from a drive device. The base block supports the input rotating body rotatably. The speed reducing mechanism unit reduces a speed of rotation of the input rotating body. The tubular case externally covers the speed reducing mechanism unit and the base block. The tubular case is assembled onto the base block such that they are rotatable relative to each other. The speed-reduced rotation from the speed reducing mechanism unit is output from one of the tubular case and the base block. The base block has a fixture flange integrally formed therewith. The flange extends from a radially inner region within the tubular case radially outward beyond an outer peripheral surface of the tubular case.