ELECTRIC LINEAR ACTUATOR AND ELECTRIC DISC BRAKE DEVICE

摘要

PROBLEM TO BE SOLVED: To reduce costs by reducing kinds of planetary rollers.SOLUTION: Circumferential grooves 23 which are engaged with spiral protrusions 6 formed at an inside diameter face of an outer ring member 5 are formed at outside diameter faces of a plurality of planetary rollers 21 which are supported by a carrier rotatable with a rotating shaft arranged on an axial core of the outer ring member 5 as a center. The outer ring member 5 is linearly moved to an axial direction by making the planetary rollers 21 rotate and revolve by friction contact with the rotating shaft. Axial force to a press-in direction which is applied to the planetary rollers 21 is received by a thrust bearing 24. Small-diameter parts 21b are arranged at one-end faces of the planetary rollers 21, and the axial force having equal magnitudes is applied to the thrust bearing 24 by differentiating axial lengths of the small-diameter parts 21b. Small-diameter parts 21c whose axial lengths are not shorter than zero are arranged at other end faces of the planetary rollers 21. An axial length which is obtained by adding the axial length of the small-diameter part 21c at the other end face and the axial length of the small-diameter part 21b at one end face is made equal with those of a plurality of the planetary rollers 21, and the axial lengths of the plurality of planetary rollers 21 are made to be the same.SELECTED DRAWING: Figure 5