According to the requirements of the engine, the fuel injection pump should accurately supply oil to the cylinders according to the specified time, and the oil supply advance angle of each cylinder (the fuel pump starts to supply oil to the crankshaft corresponding to the top dead center) should be consistent. In addition to the original fuel supply advance angle, the vehicle diesel engine also requires the fuel supply advance angle to change with the speed (the oil supply advance angle automatic adjustment device). In order to ensure the working performance of the diesel engine, it is also required that the fuel injection pump has a certain supply of oil to continue. The fuel supply advance angle is specified at the factory. If the oil supply is too early (the advance angle is too large), the diesel fuel is injected under the condition that the air temperature and pressure in the cylinder are low, the mixture gas is not formed well, the diesel engine is rough, the diesel engine produces a knocking sound, and the machine is easily damaged. It is difficult to start, and it is easy to reverse when starting, the fuel consumption rate increases, and the power decreases. If the oil supply is too late (the advance angle is too small), the diesel combustion process will continue until the top dead center, the combustion will be incomplete, the exhaust smoke, the machine temperature is too high, the start is difficult, the fuel consumption rate rises, the power decline. For example, the fuel supply advance angle of the 190A diesel engine is reduced from 39° to 30°, and the S195 model is reduced from 18° to 13°, and the power is reduced by 1.5 kW and 1.8 kW, respectively. Therefore, in the fuel system technical diagnosis, the detection and adjustment of the fuel supply advance angle is correct, which plays an important role in restoring the diesel engine's dynamic performance and economic performance.
The main reasons affecting the fuel supply advance angle: First, the wear parts of the transmission parts, such as the oil pump cam, roller, block, the end of the plunger wear and the wear of the plunger pair; second, improper adjustment of the gasket, no timely extraction of the gasket, or No suitable gaskets can be used for adjustment; third, some robots have poor technology and will not adjust or dare to adjust.