1.Uneven oil supply caused by mechanical failure: After long-term use, due to loose or too large gaps in the drive coupling of the fuel injection pump, the drive gear is worn and the backlash increases, which will also affect the uniformity of the oil supply of each cylinder. Besides, leakage of high-pressure oil pipe joints due to frequent vibration or insufficient tightening, and excessive tightening force may cause the joint metal to fall off and block the oil pipes, which will also cause uneven oil supply in each cylinder. Besides, among fuel injection pumps and governor springs, the plunger springs are the ones with stronger force, greater deformation, and higher working frequency. So its breaking frequency is also higher. The lighter fuel injection volume is reduced, the fuel injection volume of each cylinder is uneven, the fuel injection interval time of each cylinder is out of tolerance, and the fuel injection start time is delayed; the heavy fuel supply is intermittent or even unable to supply.
2.Uneven oil supply during debugging: When the fuel injection pump is debugged on the test bench, the unevenness of the oil supply of each cylinder at the rated speed should be 3%.
3.The difference between the debugging state and the use conditions: the fuel injection pump is debugged on the test bench at room temperature, while the installed use is used when the cylinder is compressed, the temperature in the cylinder reaches 500～700℃, and the pressure is 3～5MPa. , The two are quite different. When the locomotive is operating, the temperature of the fuel injection pump and the fuel injector reaches about 90°C, which will also cause the viscosity of the diesel to decrease. Therefore, the internal leakage of the plunger and the needle valve assembly increases, and the amount of oil return is more than during the debugging. According to the measurement, the actual amount of fuel injected into the cylinder by the fuel injection pump is only about 80% of the test bench debugging volume. Although the fuel pump debugging personnel will consider this factor, it is impossible to accurately grasp it. Besides, due to the difference in the degree of wear or air-tightness of the cylinder liner piston and the valve mechanism, the temperature and pressure of each cylinder after compression will also be different. Even if the fuel injection pump has been debugged on the test bench, the fuel supply of each cylinder will be uneven after installation.
Post time: Mar-05-2021