Exhaust gas recirculation valves
In the development of new engine generations, the reduction of fuel consumption and the reduction of pollutant emissions are becoming increasingly important. LRT Automotive therefore offers exhaust gas recirculation (EGR) valves for over 90% of the vehicle models currently on the market. Of course, with the usual LRT quality.
Task
The EGR valve (exhaust gas recirculation valve) is part of the exhaust system. It is installed either directly at the beginning of the exhaust manifold or on the intake manifold in the immediate vicinity of the engine block. At high combustion temperatures, environmentally harmful nitrogen oxides are increasingly produced in the engine. The task of the EGR valve is to meter the amount of recirculated exhaust gas and thus reduce the dangerous nitrogen oxides.
Functionality
The EGR valve returns part of the exhaust gas to the cylinders. Because the exhaust gas is low in oxygen, it no longer takes part in combustion in the cylinder, but displaces the fresh air in the intake manifold. The combustion rate decreases, the oxygen content in the intake air is reduced, and the combustion temperature of the running engine is lowered from around 700 °C to about 400 °C. This drastically reduces the formation of nitrogen oxides.
In addition, many diesel vehicles have an exhaust gas recirculation cooler, which further lowers the temperature of the exhaust gases before they re-enter the valve.
Control
The amount of exhaust gas recirculated through the EGR valves is determined by the engine control system. The valve is controlled by the on-board electronics using sensor data on engine speed and current engine output.
EGR Variants
There are different valves with varying modes of operation. Diesel engines have large cross-sections on the valve due to high recirculation rates, while gasoline engines tend to use smaller ones. In addition, the valves are distinguished between pneumatic and electric motor control. A pneumatic valve is opened by negative pressure, whereas the valve opening controlled by an electric motor is regulated directly by the engine control unit.
Environmental protection
Exhaust gas recirculation is one of the most important methods for reducing pollutant emissions from internal combustion engines. The method helps protect the environment, as it can reduce harmful nitrogen oxides emitted into the environment by cars by up to 50 percent. In addition, the formation of soot particles in diesel engines is reduced by around ten percent.
In order to pass the exhaust emissions test, the proper functioning of the exhaust gas recirculation system is required.