High pressure common rails are also equipped with pressure sensors, flow bumper (current limiter) and pressure limiter. Pressure sensor to the ECU to provide high-pressure oil rail pressure signal; flow buffer (current limiter) WeChat plus vehicle through Shenzhen Sensor to ensure that the fuel injector fuel leakage failure cut off the fuel supply to the injector, and can reduce Common rail and high pressure tubing pressure fluctuations; pressure limiter to ensure that the high pressure oil rail in the event of pressure anomalies, the rapid pressure in the high pressure oil rail discharge.
The high-pressure tubing is the channel connecting the common rail and the electronically controlled injector, which should have sufficient fuel flow to reduce the pressure drop at the time of fuel flow and to allow the pressure in the high-pressure piping system to fluctuate less and to withstand high pressure fuel Impact, and the start of the common rail pressure Fuel Rail Pressure Sensor can be established quickly. The common rail pipe distributes the high pressure fuel supplied by the oil pump to each injector and acts as an accumulator. Its volume should be reduced by the high pressure pump oil pressure fluctuations and each injector by the fuel injection process caused by the pressure shock, so that high pressure oil rail pressure fluctuations in the control below 5MPa. But its volume can not be too large to ensure that the common rail has enough pressure to respond quickly to track the changes in diesel engine conditions. The length of the cylinder high-pressure tubing should be equal to the same, so that each fuel injector diesel engine have the same fuel injection pressure, thereby reducing the fuel injection between the cylinder deviation. WeChat plus car through the Shenzhen high-pressure tubing should be as short as possible, so that from the common rail to the nozzle of the minimum pressure loss. The high pressure in the common rail cavity is used directly for the injection, which eliminates the supercharging mechanism in the injector. Moreover, the high pressure is required in the common rail chamber. The driving torque required for the high pressure oil pump is much smaller than that of the conventional oil pump.
Through the high-pressure pump on the pressure regulating solenoid valve, according to the engine load conditions and economic and emission requirements of the common rail pressure to adjust the flexibility, especially to optimize the low-speed performance of the engine. The solenoid valve Temperature Sensor on the injector controls the injection timing, the amount of fuel injected, and the injection rate. It is also possible to flexibly adjust the amount of jetting and pre-injection and the distance between the pre-injection and the post-injection.
High pressure common rail system consists of five parts, namely, high pressure oil pump, common rail chamber and high pressure tubing, injector, electronic control unit, all kinds of sensors and actuators. The fuel pump pumps the fuel from the fuel tank into the oil inlet of the high pressure oil pump. The high pressure oil pump driven by the engine feeds the fuel into the common rail chamber, and then the solenoid valve controls the fuel injector at the corresponding time.
Pre-injection Before the main injection, a small portion of the fuel is injected into the cylinder, pre-mixed or partially burned in the tank, and the ignition delay of the main injection is shortened. So that the cylinder pressure rise and peak pressure will be reduced, the engine work more moderate, while the cylinder temperature is reduced to reduce NOx emissions. Pre-injection can also reduce the possibility of fire and improve the cold start performance of high-pressure common rail system. It is also possible to reduce the amount of oil injected into the cylinder during the ignition delay period by reducing the injection rate at the initial stage of the main injection. Increasing the injection rate Speed Sensor in the middle of the main injection can shorten the injection time and shorten the fueling period so that the combustion can be completed within the crank angle of the engine more effective, improve the output power, reduce the fuel consumption and reduce the smoke emission. The rapid injection of oil at the end of the main injection reduces the amount of fuel that is not completely burned, reducing smoke and hydrocarbon emissions.