BRAKE BOOSTER OF VEHICLE

PURPOSE: A brake booster of a vehicle is provided to prevent the loss of the braking power and to avoid an accident by applying normal vacuum pressure to a master bag even when an engine rpm is reduced remarkably or an engine stops suddenly. CONSTITUTION: In a brake booster of a vehicle, a master bag(1) is connected with a vacuum source(3) via a vacuum pipe(2). A vacuum tank(4) is installed in the middle of the vacuum pipe. An inlet pipe(4a) and an outlet pipe(4b) are formed on each end of the vacuum tank. The inlet and outlet pipes are connected to the vacuum pipe. A check valve(5) is installed in the inlet pipe. An opening/shutoff valve is installed in the outlet valve. The vacuum pressure applied to the vacuum tank remains in the vacuum tank by the check valve. If an engine stops suddenly or an engine rpm falls less than a predetermined level, the vacuum pressure in the vacuum tank is applied to the master bag by the opening of the opening/shutoff valve. Thus, the master back performs smooth boosting work. Therefore, the rapid loss of braking power or an accident is avoided.