Brake booster for a vehicle

An improved brake booster for a vehicle including a housing having a front cell and a rear cell closely combined with each other, a power piston and a diaphragm for separating an inside of the housing into a uniform pressure chamber and a variable pressure chamber, a valve having a first end to which the power piston and the diaphragm are closely combined along a circumference thereof and having a second end connected to atmospheric air with penetrating the rear cell, a control plunger for controlling an inflow of atmospheric air to the variable pressure chamber, the control plunger being installed to move forwardly and backwardly in a cylinder hall formed inside the valve along a valve axis, an input axle having a first end combined with the control plunger and a second end combined with a brake pedal, and an output axle contacting to the first end of the valve with an intermediary of a reaction disk positioned on a center of the first end of the valve so that a shifting force caused by displacement of the power piston and the diaphragm is capable of being transferred thereto, wherein the improvement comprises:

• A vacuum tube for forming an inside of the uniform pressure chamber into a vacuum, a first end thereof being connected to an intake manifold and a second end thereof penetrating through and extended into the uniform pressure chamber;
• a venturi tube in which a venturi portion is formed, the venturi tube being diverged from the vacuum tube inside the uniform pressure chamber;
• a first air suction tube for sucking away an inside air of the uniform pressure chamber, the first air suction tube being connected to the venturi portion;
• and
• a second air suction tube for sucking in atmospheric air, the second air suction tube having a first end penetrating through the uniform pressure chamber and connected to the venturi portion, and a second end exposed to atmospheric air.