ESP pressure regulator assembly of Citroen car

The ESP pressure regulator assembly of Citroen car

brake wheel cylinder is controlled by the solenoid valve in the pressure regulator, as shown in Figure 2. The pressure regulator is composed of 4 oil inlet solenoid valves, 4 oil outlet solenoid valves and 2 conversion solenoid valves that control 4 brake wheel cylinders to realize the basic control process of ABS. The two ESP main solenoid valves are closed. When the ESP main solenoid valve is opened, the two conversion solenoid valves are closed, and the ESP system enters the adjustment state. Here, taking the wheel braking process on the left 6 fixed wheel braking circuit as an example, the basic parts of the pressure regulator circuit are explained, including switching solenoid valve, inlet solenoid valve, discharge solenoid valve, brake wheel cylinder, re injection pump, buffer and low-pressure accumulator. Its function

realizes three working states as follows

1 pressurization process. According to the braking needs of the driver, the booster establishes the pre pressure, and the switching solenoid valve is opened to allow the brake oil to enter the brake wheel cylinder. At this time, the left front wheel entry solenoid valve is opened, the left front wheel discharge solenoid valve is closed, the ESP main solenoid valve remains closed, the ESP has not been controlled and adjusted, the brake performs conventional braking, the brake pressure is instantly established in the left front wheel brake cylinder and the re injection pump, and the re injection pump starts to work to further increase the brake pressure

2 pressure maintaining process. When the brake pressure rises to the fast locking state, the left front wheel entry solenoid valve is closed, and the left front wheel discharge solenoid valve is closed. At this time, the ESP main solenoid valve remains closed, and it does not enter the working state. The brake valve cannot relieve pressure, and then the injection pump stops working, and the brake pressure is in the process of maintaining

3 pressure relief process. When the braking pressure rises again to the critical state close to locking, the system enters the pressure relief process. At this time, the switching solenoid valve is closed, the ESP main solenoid valve is opened, the left front wheel entry solenoid valve is closed, and the left front wheel discharge solenoid valve is opened or closed depending on the pressure. The re injection pump and brake valve participate in the work, the ESP enters the brake fluid pressure adjustment state, and the brake fluid returns to the fluid reservoir or enters the energy accumulator through the brake valve

esp can adjust the pressure up to 150 times per second. When individual solenoid valves fail to varying degrees, the ESP system will be turned off, and the solenoid valve circuit will be detected with "circuit open", "short circuit to positive", "short circuit to negative" and other fault information

9 re injection pump

the function of the re injection pump is to establish the instantaneous braking pressure when the ESP system starts to work. As can be seen in Figure 2, with Professor Guo's team finding the extensive use of modern computer and communication technology, when the piston of the re injection pump moves upward, the oil pressure in the upper chamber of the piston increases, the one-way valve opens, the lower return valve closes, and the pressure oil pressurizes the brake wheel cylinder. At the same time, the piston cavity produces true narrowing, This sucks the brake fluid in the reservoir. When the piston moves, the pressure in the piston chamber 1 rises, and the upper chamber of the piston produces true narrowing, the return valve opens, and the brake oil in the piston chamber 1 enters the upper chamber of the piston, which quickly compensates the upper chamber. When the pressure is instantly established, the wheel will be quickly braked. The advantages of the re injection pump are mainly reflected in the large amount of oil pumped and the rapid establishment of pressure

10 ESP system warning lamp

there are four kinds of warning lamps designed in Citroen ESP system, namely brake warning lamp, ABS warning lamp, Sr/ESP warning lamp and liquid level indicator lamp. When the ESP system is in different working states, the alarm light, such as rope and other plastic tests, will have different alarm indicators. Therefore, during driving, the working state of the whole ESP system can be judged according to the alarm conditions of different alarm lights. In addition, when the liquid level in the reservoir is too low or the liquid level sensor fails, the alarm light will also alarm. In this case, there will be no fault information in the ESP system, but it will prompt that the filtering area of the oil filter should be more than 2 times the output flow of the hydraulic pump, and the brake fluid needs to be maintained