1 phenomena
The abnormal sound of the combustion of diesel oil is a kind of similar metal percussion sound when the engine is working.
2 reason analysis
When the diesel engine is working, there is a process in which the combustion chamber of the diesel engine is burning. It can be divided into four stages, namely, the later period of ignition, the period of fast ignition, the period of slow burning and the period of afterburning. The ignition delay of diesel spray, refers to the combustion chamber is not immediately burning, it should be in the air mixing, evaporation, oxidation temperature and flame, into the rapid combustion period, the rapid formation of fire, burning speed, heat and fast, temperature and pressure in the cylinder rose sharply in this period in the crank angle of each turned 1 degrees, the gas pressure rise rate is 0.39 ~ O.59MPa, the piston TDC crank angle of 10 DEG to 15 DEG gas pressure rose to the highest point, and then to the slow burning period and combustion period.
The diesel engine combustion process, the piston compression near TDC, diesel spray for ignition delay into the cylinder after the rapid combustion period, the ignition delay set to save fuel and is funded by the people at the same time the fuel combustion, the combustion speed and the heat released quickly and easily, a sharp rise in cylinder pressure and temperature. If the period of each crank angle turned 1 degrees, the gas pressure rise rate of more than 0.39 ~ 0.59MPa, the gas pressure rise rate, combustion gas pressure wave. The burning parts of indoor combustion gas of high pressure shock waves surrounded by combustion gas, a similar metal percussion sound, the diesel combustion is not normal noise.
From the above, fuel supply advance angle is too large (to the cylinder fuel injection time early), poor quality fuel, fuel supply advance angle is too large (to the cylinder fuel injection time early), poor quality fuel, fuel supply is too large, overload operation, poor atomization, combustion will cause for poor conditions the ignition delay time, resulting in rapid combustion period pressure rise rate and crude.
3 diagnosis and exclusion of the first diagnosis should be based on the fault phenomenon in the diagnosis. If the noise is in line with the failure of the preliminary analysis of the engine has a rough voice, should be further done as follows:
(1) inspection and adjustment of diesel engine fuel supply advance angle: remove Baotou beiben parts of the fuel pump on the first cylinder tubing and the flywheel shell window on the cover, and then move the flywheel to rotate, then observe the fuel injection pump (pump) of a cylinder oil, if the oil amount of oil began to rise, stop leveraging the flywheel at this time, see the observation window fixed marker (pointer or line) indicating scale on flywheel is the fuel supply advance angle (Unified combustion chamber of diesel engine the best advance angle is 25 DEG to 35 DEG, separated combustion chamber of diesel engine optimal fuel injection advance angle is small, usually 15 degrees to 20 degrees).
If the fuel injection advance angle is not in conformity with the technical documentation, it shall be adjusted. The adjustment, some diesel engine (such as the 135 diesel engine with vertical type fuel injection pump) injection time adjustment is in the pump drive coupling, the Baotou beiben accessories coupling clamping bolt loosen, leveraging the flywheel so the fuel supply advance angle scale alignment mark fixed observation window, and then the coupling clamping bolt can be tightened.
If the oil supply from Baotou beiben accessories engine timing gear direct drive advance angle adjustment, the fuel injection pump of fixed screw loose, swinging the fuel pump, fuel pump to advance in accordance with the technical requirements, after adjusting the fixing screw is fastened.
Road test: road test should choose a good road, with low speed to stabilize the speed of the vehicle, the accelerator pedal in the end, so that the vehicle acceleration. At this time, if can hear a slight sound of crude diesel engine, when the vehicle is increased after the sound disappeared for the advance angle of fuel supply is normal; if you hear the engine sound strong and tough work speed increase does not disappear, the fuel injection time too early, should be re adjusted. If the acceleration cannot hear violent sound, and feel powerless, that oil is too late, should be re adjusted.