| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a pneumatic booster capable of achieving a long stroke without causing increase of pedal stepping force. <P>SOLUTION: In starting boosting action, a vacuum valve 11A is closed, and a negative pressure passage 71 is disconnected from a valve element back surface side space 70A to be set in a negative pressure state. As an input rod 7 advances to open an atmospheric air valve 10, atmospheric air is introduced to a pressure changing chamber 4 to thrust a power piston 5, while atmospheric air is introduced to the poppet valve element back surface side space 70A, so that a valve element separating and seating part 57 of a poppet valve element 12A receives pressure on the side of the negative pressure passage in a negative pressure state in such a direction as to close a valve seat 73 for negative pressure. Spring force, or ineffective input, necessary for maintaining a vacuum valve 11A closed when the atmospheric air valve 10 is opened can be reduced. Therefore, pedal stepping force need not be increased even when a pedal ratio is lowered as required following achievement of the long stroke. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
