The main difference between conventional diesel generators and electronically controlled diesel generators is the fuel supply system. The former uses a mechanical fuel injection system, while the latter uses an electronically controlled fuel injection system. The fuel supply system of ordinary diesel generator is generally composed of fuel supply device, air supply device, mixture forming device and exhaust gas discharge device. The electronic control diesel generator fuel supply system is developed on the basis of the common diesel generator fuel supply system with electronic control system. The function of the fuel supply system of the ordinary diesel generator is to spray the diesel oil into the cylinder according to certain rules according to different working conditions of the diesel generator, and the clean air of the suction cylinder is rapidly mixed and burned, and the exhaust gas generated after combustion is discharged into the atmosphere.
The diesel oil supply device includes fuel tank, diesel frygar filter, oil-water separator, low pressure oil pipe, oil transfer pump, fuel injection pump (including governor), fuel injector, high pressure oil pipe and return pipe. The tank contains filtered diesel oil that has been deposited. The diesel oil is sucked from the tank to the oil pump and pumped out. After the impurities are filtered out by the diesel freigard filter, it enters the fuel injection pump. The high pressure diesel oil output from the injection pump is injected into the combustion chamber through the high pressure tubing and injector. The excess diesel is returned to the oil pump through the return pipe because the fuel supply is much larger than the fuel injection pump. The section from the tank to the fuel injection pump is called the low pressure oil line. The low pressure oil line is only used to supply filtered fuel to the fuel injection pump. From the fuel injection pump to the injector this section of the oil pressure is established by the fuel injection pump, generally more than 10MPa, so called this section of oil for high pressure oil road. High pressure diesel is sprayed into the combustion chamber in a mist through the injector and mixed with air to form a combustible mixture.
1. The fuel tank
Oil tank is used to store diesel oil container, oil tank is generally made of steel plate stamping after welding. In order to prevent the formation of foam after the severe impact of the diesel oil tank, the internal surface of the tank in addition to rust treatment, some also separated by a partition into more space. The refueling port is located at the top of the tank, and the filter screen is generally installed below the refueling port. In order to avoid the vacuum inside the tank, the upper part of the tank cover is generally equipped with air holes. The bottom of the tank is usually equipped with a drain port.
2. Diesel Freighter filter
Diesel freighter filter has coarse, fine points. Diesel crude filter is generally installed before the oil pump, used to remove diesel oil particles of large impurities, filter elements are paper type, metal gap type, plate type and mesh type. Diesel fine filter is generally installed after the oil pump, used to remove the small impurities in diesel oil, filter elements are felt, metal mesh type paper type.
As shown in Figure 2-3, the diesel oil from the oil pump enters the gap between the Frigga filter shell and the paper filter through the oil inlet, and then flows out through the oil outlet through the center rod after filtering through the filter element. A pressure limiting valve is set on the cover of the Freigard filter. When the oil pressure exceeds the standard, the pressure limiting valve is opened and the excess diesel oil directly returns to the diesel oil tank through the pressure limiting valve from the oil inlet.
3. The fuel injection pump
Injection pump, also known as high pressure pump, its structure and principle is more complex, will be studied carefully and carefully in the future article.
4. The fuel injector
The fuel injector is a device that injects high pressure fuel oil into the combustion chamber of a diesel generator. According to the requirements of different diesel generators, atomized diesel oil from high pressure oil pump is sprayed into a specific position of the combustion chamber with a certain injection pressure, spray fineness, spray law, range and spray cone Angle, and mixed combustion with air. The injector is composed of a nozzle and a nozzle holder. The nozzle is embedded in the nozzle holder and installed on the cylinder head. The structure of injector can be divided into two types: open and closed. The high pressure cavity of the open injector is directly connected with the combustion chamber through the injection hole, while the closed injector is separated by a needle valve. The diesel generators of modern diesel cars basically use closed fuel injectors. Closed fuel injectors are divided into hole injectors and needle injectors, which are used in different combustion chambers.
5. oil and water separator
The function of the oil-water separator is to separate the water mixed in the oil. It is made of the principle of light oil and heavy water. If the buoy reaches or exceeds the red line, it shall release the discharge plug and release the water.
6. The oil transfer pump
Oil pump is an indispensable part of diesel generator. Its job is to transfer fuel from the tank to the fuel injection pump. In order to ensure the diesel oil in the low pressure oil circulation, and to the fuel injection pump supply enough quantity and a certain pressure of the fuel, the oil delivery should be load Z large fuel injection volume 3 ~ 4 times, to ensure the normal operation of the machine. Can be divided into two types of in-line and distribution, in this case, the in-line oil pump is explained by the import check valve, piston, piston spring, plunger tater, push rod, export check valve, hand oil pump, pump body and so on. The oil pump is installed on the side of the fuel injection pump. It is driven by the eccentric CAM set in the camshaft of the fuel injection pump. The piston is reciprocated by the plunger tappet and the push rod, and the pressure fuel is sent to the fuel injection pump. These pumps sometimes require the removal of air from the fuel on the low pressure side of the fuel system (from the fuel pump to the fuel pump), so a manual fuel pump is prepared to deliver the fuel to the fuel pump. The oil pump can be divided into horizontal and upper and lower type according to the different path of fuel, and can be divided into single action type and complex action type according to the function.
(1) single acting oil transmission pump
The camshaft drives the piston upward through the push rod, the inlet check valve closes, and the fuel in the inner chamber presses the outlet check valve open. Most of the fuel spills into the outer chamber, and some of it is transferred from the outlet to the fuel injection pump. The CAM continues to rotate until it reaches the state as shown in FIG. 2-8B. The piston is pressed down by the spring, and the fuel in the outer chamber is squeezed from the outlet to the fuel injection pump. Then the pressure of the chamber drops, the export check valve closes, the import check valve opens, and the fuel is sucked into the fuel chamber. Through the repeated operation of the oil pump, the fuel is conveyed to the fuel injection pump through the fuel freighter filter. When the fuel delivered is surplus and the fuel pressure of the outer chamber exceeds the rated pressure (output pressure), the piston is pressed to the upper part by the fuel pressure of the outer chamber, as shown in FIG. 2·, and separated from the push rod, and the fuel supply is temporarily interrupted. Therefore, the flow pressure is determined by the spring force of the piston spring. Thus, the oil pump is to prevent the oil pressure exceeds the rated value of the device. And drive the CAM oil pump, generally have a single CAM and reduce the transmission of oil pressure fluctuation of the double CAM two forms.
(2) complex action oil pump
The complex oil pump is used in large diesel generators because of its large amount of oil. Two inlet check valves and two outlet check valves are designed in the complex operating fuel pump. The reciprocating piston is used for fuel suction and output.
Jiangsu Meao Power Technology Co., Ltd. focuses on the development and manufacture of diesel generator sets, and has accumulated rich experience in manufacturing and service in this field. As a professional generator manufacturer, MEAOPOWER attaches great importance to product development, innovation and service quality, and maintains close strategic cooperation with famous domestic and international enterprises such as Cummins, Perkins, Doosan, Yuchai, Weichai, Shangchai, Wuxi Wandi, Lillesomer, Stanford, Marathon and so on.
