| 摘要 |
PROBLEM TO BE SOLVED: To increase an output without any increase of a device size as a whole so as to transmit strong operation force to a master cylinder and the like and to reduce an installation space so as to lower a cost. SOLUTION: An inside of a shell 4 of a booster main body 3 is divided into a negative pressure chamber A and a control pressure chamber B by means of a diaphragm 5, and according to a pressing operation of an input shaft 6 by means of a brake pedal 1, the negative pressure chamber A and the control pressure chamber B are connected/disconnected mutually by means of a control valve mechanism 7. A force, which is obtained by boosting a pressing operation force of the input shaft 6 by means of a differential pressure between the negative pressure chamber A and the control pressure chamber B, is transmitted to a master cylinder 11 from the output shaft 8. In the middle of a negative pressure introducing pipe 9 connecting an intake manifold of an engine to the negative pressure chamber A in the shell 4, a check valve 15, which allows suction of air from the inside of the negative pressure chamber A toward the intake manifold 10 side and prevents its reverse flow, and a negative pressure pump 16, which sucks the air inside the negative pressure chamber A so as to discharge it to the outside and generates a vacuum pressure lower than the negative pressure from the intake manifold 10. |
