Common rail system will produce fuel pressure and fuel injection separated, if the monomer pump diesel injection technology to diesel technology revolution, the common rail can be called a rebellion, because it is a departure from the traditional and the order of the similar to gasoline injection system of diesel fuel system. The common rail system opens up new ways to reduce the emission and noise of diesel engines
Europe can be said to be the paradise of diesel cars, with 39% of diesel cars in Germany. Diesel cars have been around for nearly 70 years, and in the last 10 years the diesel engine has grown tremendously. In 1997, Bosch and Benz jointly developed the Common Rail System. Today in Europe, many brands of cars are equipped with common rail diesel engine, such as Peugeot has HDI common rail diesel engine, and fiat JTD engine, while Delphi developed Multec DCR diesel common rail system.
The common rail system is different from the diesel injection system driven by camshaft, and the common rail diesel injection system separates the injection pressure and the injection process completely. Solenoid valve control injector to replace the traditional mechanical fuel injector, fuel pressure in the fuel rail produced by a radial plunger type high-pressure pump, pressure size has nothing to do with the rotating speed of engine, it can be set freely in a certain range. The fuel pressure in common rail is controlled by an electromagnetic pressure regulating valve, and continuous pressure adjustment is required according to the work of the engine. The electric control unit ACTS on the pulse signal on the solenoid valve to control the fuel injection process. The amount of fuel injection depends on the oil pressure in the fuel rail and the opening time of the solenoid valve and the liquid flow characteristics of the nozzle.
Fuel injection pressure is an important indicator of diesel engine, because it is connected with engine power, fuel consumption, emission, etc. The common rail diesel injection system has increased fuel injection pressure to 1800 bar
In the last two years, cars matching straight diesel engines have developed significantly in Europe, with high efficiency and excellent fuel economy, and reduced engine noise. The direct injection diesel engine USES the pump nozzle system, which is used by 1.9 TDI bao in China, and the maximum injection pressure can reach 1800 bar. Direct injection pump nozzle system well is good, but the fuel pressure can't keep constant, along with more strict emission control, requires higher and constant electronic control diesel injection pressure and more perfect, so many manufacturers take advantage more diesel common rail system as the development direction of diesel engine. The system has high fuel pressure and provides flexible fuel distribution control through ECU flexibly controlling fuel allocation, fuel injection time, injection pressure and injection rate. Through the control of the above features, common rail have already made the responsiveness of diesel engine and driving comfort has reached the level of gasoline engine, at the same time, it has a significant fuel economy and low emission properties.
High fuel pressure is guaranteed in the range of all engine speed. High injection pressure can achieve good combustion characteristics under low speed
Driven by the camshaft control the distribution of axial plunger pump engine, the fuel system pressure has a linear relation with the engine speed, fuel pressure at low engine speed when insufficient, and common rail system can in all of the engine speed range to obtain very high fuel pressure. The flexible electronic control system is capable of low emission and high efficiency under the control of timing and injection pressure. Because of the separation of pressure from the jet process, engine designers gain greater freedom to study the process of burning and spraying oil. Can be adjusted according to the requirement of the engine working condition of injection pressure and injection timing, and make the engine at low speed can be achieved under the condition of complete combustion, so even at very low speed also can obtain high torque. The application of pre-injection technology has made greater progress in reducing emissions and noise.