We know that, in addition to particulate matter, nitrogen oxides (NOx) is also one of the factors leading to haze. For the emission control of nitrogen oxides, in fact, car companies have also been a mature technology program - exhaust gas recycling technology. Exhaust Gas Recirculation (EGR), which diverted the right amount of exhaust gas from the exhaust pipe into the intake manifold and the fresh air into the cylinder again to participate in the combustion process benz air suspension for sale, popular point is "to chew again and again Rice ", so that more fully mixed gas combustion, reduce the generation of nitrogen oxides, reducing the engine emissions. EGR is not a new technology, the first appeared in the diesel engine, the current gasoline engine has been in use for many years. Early EGR system to direct high-temperature exhaust gas without direct cooling into the cylinder to participate in combustion, although the engine can reduce emissions, but there is due to high cylinder temperature increases the risk of deflagration. At present, the water-cooled EGR system air shocks becomes the mainstream, and the exhaust gas is cooled by the radiator before entering the intake manifold, which improves the deflagration problem due to the intake air temperature and the cylinder temperature being excessively high. Currently there are a few EGR engine engines, not only a joint venture brands, such as Changan, Chery, BYD and other Chinese brands have many applications of this technology engine, of course, the most common or in the diesel engine. It is worth mentioning that, EGR not only can effectively reduce the engine's nitrogen oxides emissions, but also under certain load conditions to enhance engine air shock absorber fuel efficiency, such as the fourth-generation Prius in the 1.8-liter 2ZR-FXE engine using the EGR System to help the gasoline engine to achieve an unprecedented 40% of the fuel efficiency.