The recirculation valve is designed to reduce harmful emissions that are generated as a result of engine operation at high speeds. Structurally, the valve is a metal body in which a diaphragm moves, which opens the bypass opening when the gas mixture in the combustion chamber reaches a certain temperature.
The exhaust gas recirculation valve is the main component of the recirculation system, designed to reduce the amount of harmful emissions into the atmosphere. The valve is installed in the channel connecting the intake and exhaust manifolds of the internal combustion engine. Recirculation valves are used in both gasoline and diesel engines of modern cars.
How the valve works
The release of toxic substances is carried out as a result of a chemical reaction of oxygen and nitrogen, which occurs when a certain temperature in the combustion chamber is reached. The recirculation valve supplies part of the exhaust gases to the intake manifold, impairing the combustion of the fuel, as a result of which the temperature of the gas in the combustion chamber decreases.
Moving the diaphragm
The exhaust gas recirculation valve is a pneumatic mechanical control valve. The working body of the valve is a diaphragm placed in a metal body. At rest, the diaphragm, under the action of a spring, closes the flow area of the valve connecting the intake and exhaust manifolds. The gas supply channel from the exhaust manifold is located in the lower part of the valve, and the upper part is connected by means of a tube to the intake manifold of the engine.
When the peak temperature is reached in the combustion chamber, a vacuum is created in the exhaust manifold, as a result of which the spring is pressed upward, opening the flow area of the valve.
The movement of the diaphragm depends on the position of the throttle valve, which changes depending on the operating mode of the engine. At idle speed of the engine, the temperature in the combustion chamber does not reach peak values, and the open position of the damper does not create a vacuum in the upper cavity of the valve. The valve comes into action as the RPM rises when the throttle valve moves to the closed position, creating a vacuum in the exhaust manifold.
Further development of recirculation valves
The engines of modern cars use recirculation valves with a thermal valve. The presence of a thermal valve prevents the diaphragm from moving when the engine is started, when it is not yet sufficiently warmed up. In engines of previous generations, the recirculation valve was included in the operation when the engine was started, artificially increasing the warm-up time.
Electronically controlled recirculation valves are also used in modern automotive engine designs. The movement of the diaphragm in them is carried out by a signal from the electronic engine control unit, which takes into account the position of the throttle valve and the temperature in the combustion chamber.
