| 摘要 |
PROBLEM TO BE SOLVED: To generate large output by a small booster by holding a valve mechanism in a non-operating condition, and operating the valve mechanism by operating an actuator through a slide member to dispense with a bellows provided in a constant pressure chamber, and to secure the effective area to which the negative pressure is applied. SOLUTION: When a brake pedal is stepped in the condition in which the atmosphere is introduced into a pressure chamber 59 of an actuator 41, a piston 53 is moved to the left through an input shaft 34, and communication of a constant pressure chamber with a variable pressure chamber is shut off by closing a vacuum valve 35, and an atmospheric valve 38 is opened to introduce the atmospheric pressure in the variable pressure chamber. The pressure difference is generated before and behind two power pistons to achieve the boosting effect. When the actuator 41 is operated and the negative pressure is introduced into a pressure chamber 59, a slide member 21 is retracted to the rear side by the pressure difference generated before and behind the piston 53 and a seal member 58, the vacuum valve 35 is closed and the atmospheric valve 38 is opened to similarly demonstrate the boosting effect. |
