The hydraulic system of the disc brake with electro-hydraulic servo control for heavy vehicles designed in this paper can realize the double-brake valve controlled by the electro-hydraulic servo and open the fuel supply at the same time to control the brake of the multi-cylinder brake cylinder. Based on the analysis of the dynamic characteristics of the connecting pipe and the brake cylinder in each part, the simulation model of the hydraulic control system was established and the rationality of the design scheme was verified. And through the bench test to verify the performance of the brake hydraulic system. System composition and working principle Disc brake hydraulic system The disc brake system consists of pedal 2 commander, hydraulic center station, disc brake and brake cylinder. The hydraulic central station is mainly composed of motor 2 oil pump device, brake valve, master brake cylinder, pressure sensor, check valve, accumulator and oil filter. Two brake cylinders of the same structure are used as actuators on both sides of the vehicle, and the brakes are controlled by two-way brake valves. Two-way brake valve is used for the vehicle's service brake. This system selects the pilot-operated remote control dual-brake valve. The valve spool is linked and has 2 input ports, 2 output ports, 1 oil return port and 1 remote control. mouth. The system uses the master cylinder as a signal source to provide the control hydraulic pressure for the remote control port of the two-way brake valve. Each valve inlet of the two-way brake valve is connected with an accumulator to ensure pressure compensation and noise reduction and vibration absorption during braking. In order to make the control pressure and control performance of the oil circuit exactly the same, the two control oil circuits are respectively connected to the B chamber and the C chamber of the two brake cylinders to ensure that the two brake hydraulic pressures are output at the same time and do not interfere with each other. The double-brake valve opens the brake scheme for controlling the multi-cylinder brake cylinder at the same time, which can accelerate the response speed of the brake and meet the requirement of fast response of the brake of the heavy vehicle. Working principle The combined brake system adopts the scheme of intermittent oil supply, that is, the system oil pressure is controlled at 13 to 18 MPa during operation. When the system oil pressure is lower than 13 MPa, the oil pump will start to supply oil to the accumulator, higher than 18 MPa. The oil pump will stop immediately. A pressure sensor is installed in the main control circuit to monitor the accumulator pressure. This working mode improves the service life and work efficiency of the motor. When the vehicle is braked, the operator generates a certain displacement through the pedal 2 commander to drive the piston of the main control cylinder to generate a commanded hydraulic pressure to act on the remote control port of the dual brake valve. The dual brake valve is linked to the valve core. Simultaneously open the pressure chamber to the B chamber or the C chamber or the B chamber and the C chamber. The piston rod of the brake cylinder extends to the brake disc and the vehicle brakes. It can be known that this system is a pressure control system, in which the characteristics of the two-way electro-hydraulic servo pressure valve and the load characteristics of the brake cylinder determine the control method and control performance of the system. Therefore, detailed mathematical model analysis is necessary. Mathematical model of the connecting line Since the brake cylinder of the brake system is located on both sides of the driving wheel of the heavy vehicle, and the two-way brake valve is located in the driving control room, a large number of metal connecting lines are used in the braking system. When the vehicle is braking, the influence of the pipeline on the braking time and braking performance cannot be ignored. In the past, most studies neglected the loss of pressure and flow caused by the connecting pipe. This is equivalent to the fact that the brake valve is directly connected to the brake actuator. This obviously has a length of nearly 10 m from the brake valve to the brake cylinder of the drive wheel. The actual situation of the pipeline varies greatly. Therefore, establishing the mathematical model of the connecting pipeline is of great significance for the study of the performance of the brake system. 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Talking about the Dual-brake Hydraulic Device of the Automobile