Patent ID: 9739319
Date: 2017-08-22
CPC Classifications: F16D

Claim:
1. A driving force transmission apparatus disposed between a first shaft and a second shaft that are coaxial with each other, the apparatus being configured to switch between an on state in which a rotational force is transmitted between the first shaft and the second shaft and an off state in which no rotational force is transmitted between the first shaft and the second shaft, the apparatus comprising: an outer peripheral portion disposed on the first shaft; an inner peripheral portion disposed on the second shaft, the inner peripheral portion facing the outer peripheral portion; a space defined between the outer peripheral portion and the inner peripheral portion, the space including at least one relatively large sub-space and at least two relatively small sub-spaces, the relatively small and relatively large sub-spaces being disposed alternately in a circumferential direction of the first and second shafts; at least one pair of rolling elements disposed in the space; an elastic body to elastically urge the rolling elements of the at least one pair away from each other in the circumferential direction; a retainer to retain the rolling elements in the space, the retainer including a pair of retaining members each retaining an associated one of the rolling elements of the at least one pair; a switching member disposed in the space so as to be displaceable in an axial direction of the first and second shafts, the axial direction including a first direction and a second direction opposite to the first direction; and a switching member assist to aid the switching member to rotate with rotation of the second shaft, with the switching member displaced in the second direction, wherein displacement of the switching member in the first direction causes the rolling elements of the at least one pair to move close to each other in the circumferential direction against elastic urging force from the elastic body and move to the relatively large sub-space, so that the rolling elements of the at least one pair each come out of engagement with the outer peripheral portion or the inner peripheral portion and each form a clearance therewith in the space, resulting in the off state of the apparatus, displacement of the switching member in the second direction causes the rolling elements of the at least one pair to move away from each other under the elastic urging force and move to the relatively small sub-spaces, so that a downstream one of the rolling elements of the at least one pair, in a direction of rotation of one of the first shaft and the second shaft relative to the other one of the first shaft and the second shaft, comes into zero clearance engagement with the outer peripheral portion and the inner peripheral portion, with a clearance formed between an upstream one of the rolling elements of the at least one pair in the direction of rotation and the outer peripheral portion or the inner peripheral portion, resulting in the on state of the apparatus, and the switching member includes a restrictor to restrict relative positions of the retaining members in the circumferential direction during the on state.