The common rail system, which is widely used in diesel engines in the field of construction machinery, has been developed as early as the 1940s, and has been improved and perfected in the 1970s. However, limited by the electronic control technology at that time, the fuel high pressure common rail system has not been widely promoted.
The biggest criticism of the traditional diesel engine is that it is noisy and vibrates greatly in the working process. The noise of diesel engine is mainly caused by the fast burning period in the combustion process. What directly affects the combustion stability in the fast burning period is the standby combustion period before the fast burning period, that is, during the process when the injector starts to inject into the cylinder and when the fuel starts to burn. In the traditional direct injection engine injector, after the high-pressure pump pressure is established and reaches the set pressure value of the injector, the needle valve of the injector is opened directly, and all the fuel is injected into the cylinder, resulting in the high concentration of the mixture in the cylinder, resulting in the rough operation of the engine in the fast burning period, which is often said to be noisy.
The main advantage of diesel common rail technology is that it can completely separate the generation of fuel injection pressure and the injection process. Through the oil pressure in the common rail pipe to ensure that each injector has the same fuel injection pressure, so that the injection pressure is not affected by the engine speed, so as to ensure the stable operation of the engine. The application of diesel common rail technology reduces the vibration and noise of diesel engine to the greatest extent, further reduces fuel consumption, reduces harmful particulate emissions in exhaust gas, and reduces environmental pollution.
By using electronic control device, the EFI system can perform pre injection (standby combustion period) before the main injection (fast burning period). In one millionth of a second before the main injection, a small amount of fuel is injected into the combustion chamber for pre combustion and preheating of the combustion chamber. After pre injection, the cylinder temperature has increased, and it is easier to carry out the main injection of compression ignition. Since the combustion temperature and pressure in the cylinder do not increase suddenly, the noise generated during combustion can be reduced. After the retarding period, the post injection (post combustion period) is carried out to make the combustion exhaust gas carry out the secondary combustion, which increases the cylinder temperature by 200-250 ℃, thus reducing the hydrocarbons in the exhaust gas, protecting the environment and reducing the tail gas pollution.
The modern high pressure common rail injection control system uses various sensors to detect the engine speed, crankshaft position and camshaft position to determine the specific injection time. According to the specific sensor data, after being processed by the engine ECU, it gives the corresponding electrical signals to each cylinder injector to control the fuel injection time and quantity of the fuel injector, so that the engine can determine the specific injection time and quantity according to the specific work The condition is adjusted in real time to meet the work requirements. This paper is written by Zetian sensing Summarize, reprint, please indicate the source.