| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently ensure a section area of a second space part and attain improving of operation responsiveness, by providing a control valve making the second space part, formed in a main unit part in accordance with axial directional movement of an input member relating to a power piston, selectively communicate with a first space part or the atmosphere. SOLUTION: A brake pedal 81 is operated, when an input rod 18 is advanced leftward, a valve plunger 23 of a control valve mechanism 17 is advanced, first, a seal part 22a of a control valve 22 is energized by a spring 21, to be integrally moved with the valve plunger 23, the real part 22a is brought into contact with an annular protruded part 141c of a power piston. In this way, communication of a first/second space part 14a, 14b that is, communication of a pressure transforming chamber with a negative pressure source is interrupted. Next, be further movement of the valve plunger 23, the second space part 144b communicates with the atmosphere, as a result, in accordance with a large pressure difference generated between a low pressure chamber 4a and the transforming chamber, the power piston outputs brake force. |
