About Euro 3 engine. . .

"Electronic control" means that the fuel injection system is controlled by computer, and ECU (commonly known as computer) accurately controls the fuel injection quantity and injection time of each nozzle, which can achieve the best balance between fuel economy and power of diesel engine, while the traditional diesel engine is mechanically controlled, and the control accuracy cannot be guaranteed.

"High pressure" means that the pressure of the fuel injection system is 1. 1 times higher than that of the traditional diesel engine, and the highest pressure can reach 145MPa (while the injection pressure of the traditional diesel engine is 60-70 MPa), so that the atomization is good and the combustion is sufficient, thus improving the power and finally achieving the purpose of fuel saving.

"* * * * rail" is used to supply oil to all injectors at the same time through a common oil supply pipe. The fuel injection quantity is accurately calculated by ECU, and fuel with the same quality and pressure is provided to all injectors at the same time, which makes the engine run more smoothly and optimizes the comprehensive performance of diesel engine. However, the traditional diesel engine injects fuel into each cylinder, and the fuel injection quantity and pressure are inconsistent, which leads to uneven operation, unstable combustion, loud noise and high fuel consumption.

Principle of high voltage rail 1. Common rail fuel injection system entered the practical stage in the middle and late 1990s. This kind of electronic control system can be divided into accumulator electronic control fuel injection system, hydraulic booster electronic control fuel injection system and high pressure rail electronic control fuel injection system. High-pressure rail system can realize the functions that traditional fuel injection system can't. Its advantages are as follows: a. The fuel injection pressure in the common rail system is flexible and adjustable, and the required optimal injection pressure can be determined according to different working conditions, thus optimizing the comprehensive performance of the diesel engine. B. The fuel injection timing can be controlled independently and flexibly. At a high injection pressure (120MPa~200MPa), nitrogen oxides and PM can be controlled in a small value at the same time to meet the emission requirements. C flexibly control the change of fuel injection rate, realize ideal fuel injection law, easily realize pre-injection and multiple injection, which can not only reduce nitrogen oxides of diesel engine, but also ensure excellent power and economy. D. The solenoid valve controls fuel injection with high control accuracy, and there will be no bubbles and zero residual pressure in the high-pressure oil circuit. Therefore, within the working range of diesel engine, the change of circulating fuel injection quantity is small, which can improve the uneven fuel supply of each cylinder, thus reducing the vibration of diesel engine and reducing emissions. Because of the above advantages, diesel engine research institutions at home and abroad have invested a lot of energy in its research. The mature systems are: CR system of German Robert Bosch Company, ECD-U2 system of Japanese Denso Company, unijet system of Italian Fiat Group, LDCR system of British Delphi Diesel System Company, etc. Two. Introduction diagram of main components of high-pressure rail fuel injection system 1 shows the basic composition of high-pressure rail electronically controlled fuel injection system. It is mainly composed of electronic control unit, high-pressure oil pump, * * * rail pipe, electronic fuel injector and various sensors. The low-pressure fuel pump inputs the fuel into the high-pressure oil pump, which pressurizes the fuel to the high-pressure oil rail. The pressure in the high-pressure fuel rail is adjusted by the electronic control unit according to the rail pressure measured by the rail pressure sensor and the need. The fuel in the high-pressure fuel rail passes through the high-pressure fuel pipe. According to the running state of the machine, the electronic control unit determines the appropriate fuel injection timing from the preset map, and the fuel injection duration is injected into the cylinder by an electro-hydraulic controlled electronic injector. 1, the design criterion of high-pressure oil pump high-pressure oil pump oil supply is to ensure the demand of the sum of injection quantity and control oil quantity of diesel engine under any circumstances and the demand of oil quantity change when starting and accelerating. Because the injection pressure in the rail system has nothing to do with the fuel injection process, and the injection timing is not guaranteed by the cam of the high-pressure oil pump, the cam of the high-pressure oil pump can be designed according to the design principle of the lowest peak torque, the lowest contact stress and the most wear resistance. Bosch Company adopts a three-cylinder radial piston pump driven by a diesel engine, which produces a pressure as high as 135Mpa. The high-pressure oil pump adopts multiple oil-pressing cams in each oil-pressing unit, so that its peak torque is reduced to 1/9 of that of the traditional high-pressure oil pump, the load is relatively uniform, and the running noise is reduced. In this system, the pressure in the high-pressure rail cavity is controlled by discharging the fuel in the rail cavity. In order to reduce the power loss, in the case of small fuel injection, one oil pressing unit in the three-cylinder radial piston pump will be closed to reduce the oil supply.