| 主权项 |
1. An extensible rotation transmission shaft comprising:
an inner shaft having an inner-side concave groove recessed radially inwards and extended axially provided at at least one circumferential location of an outer periphery surface thereof; an outer shaft having a hollow cylinder shape into which the inner shaft can be inserted and having an outer-side concave groove recessed radially outwards and extended axially provided at at least one circumferential location of an inner periphery surface thereof, at which the outer-side concave groove corresponds to the inner-side concave groove; a plurality of balls arranged in series axially between the inner-side concave groove and the outer-side concave groove; an inside guide plate sandwiched between a rolling surface of each ball and an outer surface of the inner-side concave groove; an outside guide plate sandwiched between the rolling surface of each ball and an inner surface of the outer-side concave groove, the inner shaft and the outer shaft being combined so that a rotational force can be transmitted therebetween and axial relative displacement can be made, wherein the rolling surface of each ball and a radially outside surface of the inside guide plate are in contact with each other only at two circumferentially set-apart inside contact parts, and portions of a radially inside surface of the inside guide plate, which correspond to the respective inside contact parts, are supported by the outer surface of the inner-side concave groove, wherein the rolling surface of each ball and a radially inside surface of the outside guide plate are in contact with each other only at two circumferentially set-apart outside contact parts, and portions of a radially outside surface of the outside guide plate, which correspond to the respective outside contact parts, are supported by the inner surface of the outer-side concave groove, and wherein at a state after the extensible rotation transmission shaft is assembled, at least the inner surface of the outer-side concave groove is elastically deformed more radially outwards than a state before the assembling, thereby preloading the respective balls. |
