ELECTRIC LINEAR MOTION ACTUATOR AND ELECTRIC DISC BRAKE DEVICE

摘要

An electric linear motion actuator is provided comprising a housing (1), an outer ring member (5), a rotary shaft (10) driven by an electric motor (11), a carrier (14) supported on the rotary shaft (10) and planetary rollers (21) mounted between the rotary shaft (10) and the outer ring member (5). The outer ring member (5) has a helical rib (6) formed on the radially inner surface of the outer ring member (5) and in engagement with circumferential grooves (24) formed on a radially outer surface of each of the planetary rollers (21). When the rotary shaft (10) rotates, the planetary rollers (21) are configured to rotate due to a frictional contact between the rotary shaft (10) of the planetary rollers (21), thereby moving the outer ring member (5) in an axial direction. The electric linear motion actuator further comprises a friction coupling means which is configured to frictionally fixedly couple the carrier (14) to the rotary shaft (10) while an axial load applied to the outer ring member (5) in a push-in direction is small, and to uncouple the carrier (14) from the rotary shaft (10) under the axial load when the axial load is large.