| 摘要 |
Provided is an electric booster capable of suppressing an abrupt change in a reaction force generated in response to an operation of a brake pedal, thereby improving operation feeling of the brake pedal. An input rod (34) and an input piston (32) are caused to move forward upon an operation of a brake pedal, and an electric motor (40) is driven in response to the movement of the input piston (32) to propel a primary piston (10) via a ball screw mechanism (41), whereby a desired brake fluid pressure is created in a master cylinder (2). At this time, the input piston (32) receives the fluid pressure in the master cylinder (2), and a part of the reaction force generated during the braking is fed back to the brake pedal. When, after the output of the electric motor (40) has reached the maximum value and the primary piston (10) has stopped moving, the brake pedal is pressed down further, a lock nut (74) abuts a moveable spring bearing (78) to compress a reaction force spring (79), and this imparts a reaction force to compensate for a reduction in increase of the reaction force resulting from the stopping of the primary piston (10). |
