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Causes of poor combustion of diesel generator sets

Jun 6, 2022 | Business Fraud Case | 0 comments

Diesel generator set in use in the use of poor combustion, diesel generator smoke pipe emits a “sudden, sudden” sound, idle when the exhaust smoke emits white smoke, to reach the rated speed of 1500 rpm when the diesel generator exhaust or – straight white smoke, there is no decrease.

One: the cause of the failure

  1. The gas is channeled into the oil circuit of the diesel supply mechanism, which reduces the oil volume of the oil supply system, resulting in a small amount of oil in the high-pressure oil circuit.
  2. The diesel generator nozzle is damaged, the diesel atomization is not good, and the injector nozzle is dripping oil. The reason why the injector will drip oil, according to past experience, there are 2 possible reasons, one is that the diesel generator in the working step, the high-pressure diesel sprayed from the injection device will often entrain some mechanical impurities into the injector, and adhere to the sealing cone of the needle valve body, so that its sealing is not strict; Second, due to the ablation of high-pressure and high-temperature gases in the combustion chamber, the frequent erosion of mechanical impurities in the combustion of work, the sealing ring belt of the needle valve and the needle valve body will occur pocks and pits, resulting in the deterioration of the sealing performance between the needle valve and the needle valve body and the dripping oil, resulting in poor combustion.
  3. Damage to diesel high pressure oil pump. Cylindrical pressure reduction ring belt and oil outlet valve seat with serious wear situation, and the pressure reduction belt and the upper end of the valve seat grinded into a conical shape, so that the coordination gap is excessive, so that when the injection pump pump oil operation, the pressure reduction belt will not be fully exposed to the valve seat to cause the oil pressure of the high-pressure tubing to decrease, in the second injection of oil in order to increase the oil pressure in the tubing to the injection pressure, to occupy more fuel supply time, so that the injection time is lagging behind, the amount of fuel injection is reduced accordingly, so that the high-pressure oil pump stops supplying when the high-pressure oil pipe residue diesel is too much, the remaining oil pressure is too high, So that the injection nozzle injection oil is not crisp, the status quo after the occurrence of drip.
  4. Low cylinder pressure accidents. The cause of the low cylinder pressure: the gap between the piston rings is not staggered; Piston ring broken, cylinder pull cylinder; Sudden break of valve springs or sudden bite of valves; Cylinder gas line failure, etc. If the pressure is insufficient, a large amount of white diesel vapor or oil mist will inevitably be discharged from the exhaust pipe, resulting in the output of the diesel generator being weak.

5. The oil supply angle is too small in advance. When installing the diesel generator, the timing gear mark and the high-pressure oil pump gear mark are not aligned, resulting in the high-pressure pump oil supply time being too late.

Second: inspection and treatment measures

  1. First of all, start from the oil supply mechanism to find out whether the gas is channeled into the oil circuit of the oil supply device, so that the fuel supply of the injector is reduced, when all the oil circuits from the oil tank outlet pipe to the high-pressure pump are viewed once, no loose or ruptured and leaked gas is found. In order to ensure that there is no air leakage in the pipeline, a new backup hand oil pump is used, and the scheme of “hitting the hanging bottle” is used to directly supply oil to the fuel pump without going through the original diesel low-pressure pipeline, and the damage to the diesel generator still exists after starting, which proves that the low-pressure oil supply pipeline is good.
  2. Using the cylinder breaking method, the high-pressure oil pipe in front of the injection pump is released in turn, and the combustion status of each cylinder of the diesel generator is inspected, and the reaction of each cylinder is found to be less obvious. Remove the injector nozzle, adjust the injector on the test bench, found that each cylinder injection pump is poorly atomized, and the current situation of oil dripping is serious, so replace the fuel injection pump and correct the injection pressure of the injector to meet the requirements of the injector working standard, and at the same time use a cylinder gauge to measure the pressure of each cylinder. By checking that the pressure of each cylinder is within the normal range, there is no case where the cylinder pressure is too low. After installing the new injector after calibration, and then restarting the diesel generator, it was found that the operation of the diesel generator improved slightly, but it still could not meet the work requirements. Because the connection between the timing gear and the high-pressure pump gear was not disassembled, and the diesel generator was a sudden failure, the cause of the late ignition time could be dismissed.
  3. In the combustion program of the diesel generator, the exhaust pipe does not spray water, the anti-rust water tank does not bubble and return water, and the coolant is not lacking, so the cylinder gasket is not eroded.
  4. After the accident clearance of the above few steps, it is suspected that the high-pressure pump is faulty. After removing the high-pressure pump, the external commissioned the pump, and found that the wear between the distribution pump and the sleeve was large, causing the oil pressure to decrease and the oil pump supply was reduced. Therefore, the replacement of the distribution rotor assembly, the calibration on the test bench found that the injection indicators are qualified, after the installation of the diesel generator again, the diesel generator is still unable to increase the speed of white smoke. Open the timing gear chamber cover, check to confirm that the oil supply timing does not change, once again remove the high-pressure pump to the test bench test, found that the high-pressure pump all the indicators are qualified.
  5. Replace the high-pressure pump of another normally used Isuzu diesel generator of the same type to this machine, start the diesel generator, the smoke pipe is no longer white smoke, the refueling speed rises rapidly, and the operation is powerful. Therefore, after confirming that the original high-pressure pump has been adjusted, there is still damage. The high-pressure pump was disassembled and carefully cleaned, and it was found that the oil supply port before the rotor of the distribution pump was blocked by gelatinous impurities, which hindered the normal oil supply of the distribution pump. In the early stage of the school pump test bench when the pump was calibrated, because the oil transfer pump used for the regulation test was not exactly the same as the actual use, especially the passing ability and oil leakage degree of the valve installer and the tubing were not the same, resulting in the high-pressure pump being qualified on the test bench, and the high-pressure pump operation in the actual work was unqualified. After re-calibration, the high-pressure pump is installed on the diesel generator and the damage is completely lifted.

For the damage of the diesel generator running weakly, the exhaust smoke and white smoke, through the analysis of the working mechanism, combined with the repair experience, list all the possible causes one by one, according to the way from the outside to the inside, from easy to difficult, from disassembly diagnosis to disassembly diagnosis to dismantle the fault, and finally found the fundamental cause, that is, the gelatinous precipitation impurities in the diesel fuel caused by damage. Summarizing the steps of the accident removal, it can be seen that the cause of the damage to the diesel generator is often not a single, but the result of multiple aspects of comprehensive functions, such as the wear and replacement of the fuel injection nozzle assembly found in the troubleshooting process, and the replacement of the rotor distribution rotor wear and tear of the rotor distribution pump. Refining and summarizing the causes of diesel generator accidents, analyzing the damage disposal methods can provide strong reference value for the staff related to diesel generator repair, and promote the exchange and sharing of peer experience.


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