In the Vacuum Brake Booster System, the controller needs to drive and control the vacuum pump according to the relative pressure value in the vacuum tank. The relative pressure value is calculated from the vacuum pressure value and the atmospheric pressure value. The vacuum booster is mainly composed of a vacuum servo air chamber and a control valve.
Vacuum Brake Booster System
The vacuum servo air chamber is composed of the front and rear shells, and the servo air chamber diaphragm is sandwiched between the two to divide the servo air chamber into the front and rear chambers. The front chamber is connected to the engine intake manifold (ie, the vacuum source) through a vacuum check valve. The outside air is filtered through the filter ring and the felt filter ring and enters the servo chamber rear chamber. A control valve is installed in the hub of the rear cavity diaphragm seat. The control valve is composed of an air valve and a vacuum valve. After the structure diagram is partially enlarged, the air valve and the control valve push rod are fixed together. The control valve push rod is connected to the brake pedal mechanism through an adjustment fork. There are channels A and B on the diaphragm of the servo air chamber. Channel A is used to connect the front chamber of the servo air chamber and the control valve and channel B is used to connect the back chamber of the servo air chamber and the control valve. The thrust generated during the operation of the vacuum servo air chamber, like the pedal force, directly acts on the brake master cylinder pushrod.
When the Vacuum Brake Booster Kits are not working, the air valve and the control valve push rod leave the rubber reaction disk under the action of the control valve push rod spring to the right end limit position, and the vacuum valve leaves the valve seat on the diaphragm seat, that is, the vacuum The valve is open. The vacuum valve is pressed against the air valve by the valve spring, that is, the air valve is in a closed state. At this time, the front and back chambers of the servo air chamber communicate with each other and are isolated from the atmosphere. When the engine is operating, a certain degree of vacuum can be generated in the front and rear chambers.
When braking, the brake pedal is depressed, and the control force from the pedal mechanism pushes the control valve plunger and the control valve plunger forward. After eliminating the gap between the plunger and the rubber reaction disk, the brake master continues to push The cylinder push rod, the brake fluid in the master cylinder flows into the brake wheel cylinder at a certain pressure and this force is given by the brake pedal mechanism. At the same time, under the action of the valve spring, the vacuum valve also moves forward until it presses against the valve seat of the diaphragm seat so that the channels A and B are isolated, that is, the front and rear chambers of the servo air chamber. Insulation, the air valve leaves the vacuum valve and opens, and the air is filled into the back chamber of the servo air chamber through the filter ring, felt filter ring, the opening of the air valve and the channel B. With the filling of air, a pressure difference occurs on the two sides of the diaphragm of the servo air chamber to generate thrust. This thrust pushes the brake master cylinder push rod forward through the diaphragm seat and the rubber reaction disk. This force is caused by the pressure difference. give. At this time, the acting force on the brake master cylinder pushrod is the sum of the pedal force and the thrust force of the servo-air chamber reaction disk, so that the pressure output by the brake master cylinder is doubled.
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