There are several types of EGR valves.

The EGR control solenoid valve is an electromechanical vacuum switch valve, which is located in the control box on the right side of the firewall. Its function is to control the vacuum applied to the EGR valve. The solenoid valve is controlled by the controller. When the solenoid is energized, the valve opens and the passage between the air inlet and the air outlet is communicated.

1.2 EGR valve lift sensor

The sensor uses a potentiometer pushed by a plunger to transmit the actual lifting height signal of the ECR valve to the engine controller. The engine controller stores the optimal lifting height of BGR valve under various working conditions. If the actual lifting height value is different from the optimal value stored in the engine controller, the engine controller cuts off the power supply of the EGR control solenoid valve and reduces the vacuum applied to the EGR valve.

1.3 exhaust gas recirculation valve

The valve is located on the right side of the intake manifold, near the throttle body. Its function is to make a certain amount of exhaust gas flow into the intake manifold for recirculation. One side of the EGR valve diaphragm is connected with the pivot rod, and the other side is connected with the spring (the spring keeps the valve normally closed). When the vacuum pressure on the diaphragm is greater than the spring force, the pivot rod is pulled away from the original position, and the channel is opened, so that the exhaust gas enters the recirculation system. The amount of recirculated exhaust gas is directly related to the throttle opening value, and its control principle is shown in Figure 2. The solenoid valve receives the control signals from the controller and relay, and opens the vacuum loop, so the vacuum pressure △Px attracts the diaphragm on the EGR valve to open the valve, introducing the exhaust gas into the cylinder, and reducing the emission of nitrogen oxides.