The ignition knock of diesel generator is formed because the ignition lag period is too long and the pressure rise rate is too large, resulting in rough operation of the diesel generator. It is characterized by a sharp, crisp, sustained, metal-like thumping sound during sharp acceleration. It is more obvious when idling or light load work, accompanied by vibration of the body. At high load and high speed, the sound is relatively weak, and the operation is relatively stable.
1. Use the diesel generator road test method to make a preliminary diagnosis. Run smoothly at high speed and low speed, and then accelerate the accelerator to the end. If the diesel generator makes a strong and sharp knocking sound, and does not disappear for a long time, when the accelerator pedal is slightly lifted, the sound will immediately weaken or disappear, and the sound will resume when the accelerator is heavy. produced, it can be regarded as a fire knocking sound. The fuel injection time can be delayed a little, and then the road test can be carried out. If the sound disappears, it means that the fuel injection time is too early.
2. If the fuel injection time is delayed and the sound does not change, it means that the fuel supply timing is correct, and the diesel can be replaced before the road test. If the sound disappears, it means that the diesel quality is poor.
3. Use the half-cut test, that is, loosen the high-pressure oil pipe joint of the fuel injection pump, so that part of the oil is sprayed outside, so as to reduce the oil supply to the cylinder. If the sound and exhaust smoke disappear, it means that the fuel supply to the cylinder is too large.
4. If the half-cut fuel test is used, the sound will only weaken but not disappear, and the sound will disappear after the oil is completely cut off, which means that it is the fire knocking sound caused by the premature fuel supply time of the cylinder or the poor atomization quality of the fuel injection pump. Pay attention to check the spraying of the fuel injection pump.
5. The fire knocking sound caused by the excessive fuel supply of individual cylinders can also be predicted by touching the exhaust manifold of the corresponding cylinder by hand after cold start; Touch the lower part of the fuel injector and the cylinder head near it. If you feel that the temperature of the cylinder being touched is hotter than other cylinders, it means that the fuel supply of the cylinder is too large. You can also hold the high-pressure oil pipe by hand. If you feel that the pulsation is large, the oil supply of the cylinder is too large.
6. If the fuel supply of individual cylinders is too large or the fuel supply time is too early, the fuel injection nozzle should be removed to debug the fuel supply volume and fuel supply interval angle of the cylinder on the test bench, and the fuel supply volume and fuel supply of other cylinders should be checked. Check the spacing angle.
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