What are the EGR valve and PVC valve mentioned in the automobile maintenance book?

EGR valve is a mechatronics product installed on gasoline engine, which is used to control the amount of exhaust gas recirculation fed back to the intake system. It is usually located on the right side of the intake manifold, near the throttle body, and connected to a short metal pipe leading to the exhaust manifold.

PVC valve is the main component of engine crankcase forced ventilation system. Its function is: when idling, the speed is low, the combustion performance is poor, and the crankcase exhaust gas is less. At this time, the system is closed by the vacuum force of the intake manifold; Under other working conditions, the vacuum force drops, the spring in the valve resets, and the system starts to work.

The extended data EGR valve is divided into two types: mechanical type and electronic control type. The mechanical type is shown in the right figure.

EGR valve can reduce the temperature of the combustion chamber, improve the working efficiency of the engine, improve the combustion environment, reduce the burden of the engine, effectively reduce the emission of NO compounds, reduce knock and prolong the service life of various components by introducing the exhaust gas discharged from engine combustion into the intake manifold.

PVC breathing valves are mainly used in atmospheric and low pressure storage tanks (such as HCL/HNO3 storage tanks) containing volatile chemicals that are not allowed to leak. It is fixed on the top of the storage tank as a ventilation device to ensure that the pressure in the tank is in a normal state, prevent the storage tank from being damaged by positive pressure and negative pressure, and also reduce the volatilization loss of liquid in the tank.

Resource EGR valve _ Baidu Encyclopedia