Brake pressure regulator is one of the basic components of the vehicle brake system. Brake pressure regulator connected between the master cylinder and the wheel cylinder, to control the brake pressure in the wheel cylinder directly or indirectly through a solenoid valve. Typically, the solenoid valve directly controls the brake pressure in the wheel cylinder braking pressure regulator called circulation type regulator, the brake pressure is indirectly controlled brake pressure regulator called a variable volume regulator.
1. Categories brake pressure regulator
more
type brake pressure regulator, the structure and working principle differences are large. It can be classified according to the power source, the overall structure and voltage mode.
1, according to the power source classification
According to different power sources brake pressure, the brake pressure regulator is divided into two kinds of pneumatic and hydraulic. Hydraulic mainly for cars and light trucks; pneumatic mainly used for large passenger cars and trucks.
2. The overall structural classification
Depending on the overall structure, the brake pressure regulator is divided into two kinds of separate and integral. Separate self-contained brake pressure regulator, connected through a brake line to the brake master cylinder (or brake booster). Separate brakeA pressure regulator disposed on an automobile flexibility, relatively low cost, but relatively more brake line connection. Integral brake pressure regulator and the master brake cylinder (or brake booster) formed integrally. Integral brake pressure regulator compact structure, small pipe joints, but the cost, mostly used in ABS as standard equipment on the car.
3, according to the classification pressure regulating means
Depending on the voltage mode, the brake pressure regulator and into a flow-type two varactor.
The flow-through pressure regulator, also known as recursive or loop type, which is characterized by one or two solenoid valves in series between the brake master cylinder (or brake booster) and the wheel cylinder, a solenoid valve the ABS ECU commands to adjust the pressure of the brake wheel cylinder through the control flow of the brake fluid. Currently, Bosch, Davis ABS series have adopted this form. So that when the wheel cylinder pressure of the brake fluid is returned to the brake master cylinder (or accumulator); the brake fluid in the wheel cylinder holding pressure is neither inflow nor outflow; when the brake booster a master cylinder (or the accumulator) of the brake fluid flows into the wheel cylinder.
variable displacement characteristics of the brake pressure regulator is in the original set of parallel hydraulic braking circuit means has a piston-like part. When ABS work, the apparatus first wheel cylinder and the master cylinder isolation, and then by turning off solenoid valve or a motor, control movement of the piston in the pressure regulating cylinder, the cylinder chamber so that the regulator to the brake wheel cylinder volume changes. Volume increases, the brake pressure reduction; volume decreases, the brake pressure is increased; constant volume, the pressure remains constant.
4. The solenoid valve structural classification
Depending on the structure of the solenoid valve, the brake pressure regulator is divided into two two-way solenoid valve and three-way solenoid valve two.
2. The working principle of the brake pressure regulator
circulating the brake pressure regulator, this form of the brake pressure regulator is a solenoid valve connected in series between the brake master cylinder and the wheel cylinder, direct control of the brake pressure in the wheel cylinders. Such pressure regulation system is characterized by a brake pressure oil passage and the oil passage communicating the control pressure ABS. The system works as follows:
(1) regular brake
Conventional braking, ABS system does not work. No current through the solenoid, the solenoid valve is a “boost” position, with the brake master cylinder and the wheel cylinder through, by the brake master cylinder to the brake fluid directly into the wheel cylinder, the wheel cylinder pressure with the master cylinder pressure increase or decrease. At this point scavenge pump and need not work. When the
(2) the holding pressure process
When the locking wheel speed sensor emits a danger signal, the ECU into a small holding current (about 1/2 of the maximum current) through the electromagnetic coil, the solenoid valve (3) the process under reduced pressure
If the “hold pressure” command is issued, there wheel lock signal, namely the ECU into a maximum solenoid current, the solenoid valve in the “pressure” position in which the solenoid valve the wheel cylinder and the oil return passage or reservoir is turned, the wheel cylinder by brake fluid reservoir chamber flows into the solenoid valve, the wheel cylinder pressure drop.
(4) pressurization
When the wheel acceleration after pressure drops too quickly, the ECU will interrupt the current leading to the solenoid valve communicates the master cylinder and the wheel cylinder again, the high pressure brake fluid into the master cylinder again the wheel cylinder, the brake pressure is increased.
in the “packing” position. At this time, a master cylinder, wheel cylinders, and the oil return hole sealed from each other, the brake pressure in the wheel cylinder is maintained constant.