What Is An EGR Valve And What Does It Do?

release time:2020-04-26 13:40Views:Times
Installation position of EGR valve
The EGR valve is installed on the intake pipe. Exhaust gas recirculation (EGR valve) is to introduce exhaust gas into the intake pipe to reduce the oxygen content in the intake air, thereby reducing the combustion temperature and reducing the emission of nitrogen oxides. However, exhaust gas recirculation will affect the power of the engine, so it can only be carried out under moderate working conditions to ensure that the engine can reduce pollution and ensure its use.

The role of EGR valve
Exhaust gas recirculation (EGR) systems can be divided into open-loop control EGR systems and closed-loop control EGR systems according to whether feedback monitoring elements are provided. Compared with the open-loop control EGR system, the closed-loop control EGR system only adds an EGR valve position sensor to the EGR valve as a feedback signal to monitor the opening degree of the EGR valve to keep the EGR rate at the optimal value. The EGR valve position sensor detects the up and down movement position of the EGR valve stem, and the engine ECU determines the size of the valve opening to reduce exhaust emissions.

EGR valve's structure
The valve needle of the EGR valve is connected to the sliding contact arm of the potentiometer. The EGR valve of the duty cycle control changes with the change of the duty cycle, and the controlled vacuum suction is also different, causing the EGR valve The size of the valve opening is also different, and the displacement of the valve stem rise is also different.

Working principle of EGR valve
The stem of the EGR valve rises and pushes the position of the sliding contact arm connected to it to change, so that the sliding contact slides on the sliding resistance, generating different voltage signals. This signal will be transmitted to the engine control ECU, engine control ECU In this way, the position of the EGR valve is monitored to ensure that the valve responds correctly to the commands of the ECU, thereby adjusting and correcting the opening time and duty cycle of opening the EGR valve, and accurately controlling the amount of recirculation to reduce emissions and improve performance. Some models such as Honda, Buick and Toyota are equipped with EGR valve position sensors.


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