The vacuum brake booster and brake master cylinder are structurally integrated into one unit. The scheme of action and the device of the first is nothing super complicated.
The brake booster has a housing divided into two parts by a diaphragm. The atmospheric part forms on the pedal side. The vacuum chamber is located on the side of the brake master cylinder, which is connected via a non-return valve to the intake manifold. The collector is a source of vacuum. The vacuum brake booster on diesel engines works stably due to the presence of a special electric pump in the design. When the motor stops, disconnection occurs. The vacuum brake booster and the collector can also disconnect in the event of a malfunction (or failure) of the former.
In its initial position, a follow-up valve connects the atmospheric chamber to the second part of the housing. When you press the brake pedal - with the atmosphere.
A pusher is also connected to the brake pedal. It provides tracking valve movement. The diaphragm dividing the housing into two parts is connected to the rod of the brake master cylinder (GTZ) from the side of the vacuum part. The diaphragm is responsible for pumping brake fluid to the working cylinders by means of a piston.
The movement of the diaphragm to its original position is due to the return spring. The vacuum brake booster may include in its design an emergency braking system - an electromagnetic rod drive.
ESP assumes a tipping preventive structure — an active system.
Car braking is carried out with some deceleration and solely due to actions performed by the driver.
The hydraulic brake booster offers a follow-up action. In the direction of increasing air pressure in the part under the diaphragm of the control valve, its piston and diaphragm begin to move down until the air valve takes up space in the seat. The forces affecting the control diaphragm from below and above, in this case are aligned. From below, piston force acts, which depends on the impact on the brake pedal. Above is increased air pressure in the cavity under the baffle of the control valve.
With increased effort on the pedal, pressure is generated in the system, which contributes to the beginning of the movement of the piston of the hydraulic cylinder and the closing of its valve. At the same time, the vacuum valve closes. Air opens at the same time. At the same time, the piston of the control valve rises, air is introduced into the cavity from the atmosphere by means of a filter. Then, air is sent to the chamber cavity through a hose. A vacuum is maintained in the cavity. Under the influence of the difference in pressure, the diaphragm bends forward, and its force is transmitted through the rod to the piston in the hydraulic cylinder. Further, the pressure is set in the wheel cylinders. It is just created by the diaphragm of the camera and the driver’s foot. Thus, the car is braked with the necessary efficiency.
In accordance with a certain force acting on the pedal, pressure is also formed in the vacuum chamber. Accordingly, the same pressure is created in the fluid of the wheel cylinders. It is also formed due to the actions of the driver’s force and transmitted from the camera.
When the pedal is released, the parts of the amplifier and the piston of the GTZ are returned to their original position. The liquid in this case is returned through the opening intake valve to the GTZ. Through the bypass hole in the piston head, fluid is returned from the reservoir, which pushes the washer, bends the edges of the cuff, fills the space, thereby increasing the readiness of the brake cylinder for re-braking.