Patent ID: 9657811
Date: 2017-05-23
CPC Classifications: B62D,F16H

Claim:
1. A worm speed reducer, comprising: a worm shaft having a first end coupled to an electric motor such that the worm shaft is driven by the electric motor, and a second end opposite to the first end in an axial direction of the worm shaft; a worm wheel with pairs of tooth flanks, each pair defining a tooth groove; a housing that houses the worm shaft and the worm wheel and that supports the second end of the worm shaft such that the second end is able to pivot around the first end of the worm shaft; and a bias member that is supported by the housing and that elastically biases the second end of the worm shaft in a preloading direction in which a center distance between the worm shaft and the worm wheel decreases, wherein: a center axis of the worm shaft is parallel to but offset in an offset direction from a plane that is orthogonal to a center axis of the worm wheel and that passes through a central position of the worm wheel in a tooth width direction, and (i) in a left-handed coordinate system for a case where the worm shaft is configured with a right-hand thread or (ii) in a right-handed coordinate system for a case where the worm shaft is configured with a left-hand thread, when a direction toward the first end of the worm shaft corresponds to a thumb direction and the preloading direction corresponds to an index finger direction, the offset direction corresponds to a middle finger direction.