The device and principle of operation of the vacuum brake booster
Content
The vacuum booster is one of the integral elements of the vehicle's braking system. Its main purpose is to increase the force transmitted from the pedal to the master brake cylinder. Due to this, driving becomes easier and more comfortable, and braking is effective. In the article, we will analyze how the amplifier works, find out what elements it consists of, and also find out if it is possible to do without it.
Vacuum booster functions
The main functions of the vacuum cleaner (common designation of the device) are:
- an increase in the effort with which the driver presses the brake pedal;
- ensuring more efficient operation of the braking system during emergency braking.
The vacuum amplifier creates additional force due to the resulting vacuum. And it is this reinforcement in the event of emergency braking of a car moving at high speed that allows the entire braking system to work with high efficiency.
Vacuum brake booster device
Structurally, the vacuum amplifier is a sealed round-shaped case. It is installed in front of the brake pedal in the engine compartment. The main brake cylinder is located on its body. There is another type of device - a hydraulic vacuum brake booster, which is included in the hydraulic part of the drive.
The vacuum brake booster consists of the following elements:
- the body;
- aperture (for two cameras);
- monitoring valve;
- brake pedal pusher;
- the piston rod of the hydraulic cylinder of the brakes;
- return spring.
The body of the device is divided by a diaphragm into two chambers: vacuum and atmospheric. The first is located on the side of the brake master cylinder, the second on the side of the brake pedal. Through the check valve of the amplifier, the vacuum chamber is connected to a source of vacuum (vacuum), which is used as an intake manifold on cars with a gasoline engine before supplying fuel to the cylinders.
In a diesel engine, an electric vacuum pump serves as a source of vacuum. Here, the vacuum in the intake manifold is negligible, so the pump is a must. The check valve of the vacuum brake booster disconnects it from the vacuum source when the engine is stopped, as well as in the case in which the electric vacuum pump has failed.
The diaphragm is connected to the piston rod of the master brake cylinder from the side of the vacuum chamber. Its movement ensures the movement of the piston and the injection of brake fluid to the wheel cylinders.
The atmospheric chamber in the initial position is connected to the vacuum chamber, and when the brake pedal is depressed - to the atmosphere. Communication with the atmosphere is provided by a follower valve, the movement of which occurs with the help of a pusher.
In order to increase the braking efficiency in an emergency situation, an emergency braking system in the form of an additional electromagnetic rod drive can be included in the design of the vacuum cleaner.
The principle of operation of the vacuum brake booster
The vacuum brake booster works due to the different pressures in the chambers. In this case, in the initial position, the pressure in both chambers will be the same and equal to the pressure created by the vacuum source.
When the brake pedal is depressed, the pusher transmits force to the follower valve, which closes the channel connecting both chambers. Further movement of the valve facilitates the connection of the atmospheric chamber through the connecting channel to the atmosphere. As a result, the vacuum in the chamber is reduced. The pressure difference in the chambers moves the piston rod of the brake master cylinder. When the braking ends, the chambers reconnect and the pressure in them is equalized. The diaphragm, under the action of the return spring, takes its original position. The vacuum cleaner works in proportion to the force of pressing the brake pedal, i.e. the harder the driver presses the brake pedal, the more efficiently the device will work.
Vacuum Booster Sensors
The efficient operation of the vacuum booster with the highest efficiency is ensured by the pneumatic emergency braking system. The latter includes a sensor that measures the speed of movement of the amplifier rod. It is located directly in the amplifier.
Also in the vacuum cleaner there is a sensor that determines the degree of vacuum. It is designed to signal a lack of vacuum in the amplifier.
Conclusion
The vacuum brake booster is an indispensable element of the braking system. You can, of course, do without it, but you don't need to. First, you have to spend more effort when braking, you may even have to press the brake pedal with both feet. And secondly, driving without an amplifier is unsafe. In the event of emergency braking, the braking distance may simply not be enough.
Questions and answers:
What is a vacuum brake booster valve for? This device removes air from the brake booster. It prevents air from entering the brake line, which can cause brake failure.
How does the vacuum brake booster valve work? The operating principle of the vacuum brake booster check valve is very simple. It releases air in one direction and prevents air from flowing back.
What happens if the vacuum brake booster does not work? With the same effort on the pedal, the car began to slow down noticeably worse. When the pedal is pressed, a hiss is heard, the engine speed increases. the pedal can be stiff.
How to check the vacuum brake booster valve? To diagnose the non-return valve, it is enough to remove it from the vacuum brake booster and blow into the pipe with which it is inserted into the booster. In a working valve, flow will only flow in one direction.
