Patent attributes
The object is to provide a reclining device for a seat such as an automotive seat including a differential transmission mechanism (Taumel mechanism) which makes it possible to eliminate precision machining of the inner surface of an external gear into which a slide bearing is pressed, in which the freedom of design of the reclining device is not restricted by the standards of a bearing bush, and which can be manufactured at a low cost. The reclining device includes a differential transmission mechanism for adjusting the opening angle of a hinge through which the seating portion and the backrest portion of the seat are coupled together. The differential transmission mechanism includes an internal gear and an external gear having a slightly smaller number of teeth than the internal gear and meshing with the internal gear. An arcuate gap is defined between a shaft hole of the external gear and a small-diameter portion of a cam integral with a shaft of the internal gear. A pair of wedge-shaped pieces and are received in the arcuate gap such that their narrow ends and face in opposite directions to each other. At least the outer surfaces and of the wedge-shaped pieces and, which serve as frictional contact surfaces when the wedge-shaped pieces and are pushed by the cam integral with the shaft of the internal gear and slide in the arcuate gap, are each made of a low-friction sliding material.
