(1) the size of high pressure oil pipe should be consistent
Diesel fuel pump in the oil supply process, because the diesel elastic compressibility and high pressure pipe, high-pressure diesel will form the pressure fluctuation in the tube, the pressure fluctuation of the transfer will take some time, to ensure the cylinder oil supply interval angle consistent, uniform, high pressure pipe length and diameter was measured and selected we can not arbitrarily change. Therefore, when the multi cylinder injection pump is adjusted, the inner diameter and length of the high pressure oil pipe must be equal, and the following 3 points should be paid attention to.
(1) the diesel oil should be cleaned and the 48h will have to be precipitated before the oil tank is added. When refueling, a filter is set up and only the upper diesel is used.
The new high pressure oil pipe should be cleaned with diesel oil, remove rust oil and dirt, and heat the tubing when necessary.
The test of continuous work, every 3 months should be 1 times the amount of oil test of high pressure fuel pipe, a fuel injector on the test bench, with the same standard as a quantity of tubing, with a single cylinder or multi cylinder piston pump plunger pump in the pump, in order to high-pressure tubing for the amount of oil test.
(2) use the standard injector
The performance of injector will seriously affect the injection volume and fuel supply uniformity. Even if the fuel injection quantity and fuel supply uniformity of the injection pump are verified, the actual fuel consumption is far beyond the prescribed tolerance range (the allowable error of fuel injection volume is within the range of ± l%).
There are 3 factors that lead to the change in the amount of fuel injection.
(1) the wear of the spray hole. When the injector works, the aperture will increase gradually and the fuel volume will increase gradually due to the high pressure, high-speed flow of diesel oil and the wear of mechanical impurities in fuel.
The wear of the guide face of the injector needle valve body. As the mechanical impurities in diesel enter the gap of the needle valve body, it plays an abrasive role, so that the needle valve will be scratched on the guiding surface in high-speed reciprocating motion, forming fine axial scratches.
The opening pressure of the nozzle is decreased. Due to the change of pre tightening force of the pressure regulating spring in the injector, the sealing cone surface of the needle valve is worn, and the sealing performance of the guiding part of the needle valve and the needle valve body is worse, which will cause the opening pressure of the nozzle to decrease, resulting in the increase of the oil supply and the uneven oil supply. Therefore, when the injection pump is debugged, the opening pressure of the debug injector on the test rig should be consistent or almost close to the opening pressure of the standard injector. When the fuel supply error is more than 4%, the fuel injector with excessive fuel supply should be selected to correct the opening pressure, and the adjustment of opening pressure is allowed to correct when the oil output is not large.
(3) strict control of the temperature of test diesel oil
Because the viscosity and specific gravity of diesel oil vary with temperature, and the amount of fuel is calculated by volume. Therefore, the temperature change of diesel engine has great influence on the adjustment of fuel supply. For example, when the temperature decreases, the viscosity of diesel increases, the mobility decreases, the leakage of plunger decreases, and the amount of oil supply increases, especially the worn plunger. In order to adjust the supply of oil accurately, the temperature of the test room should be kept at about 20 degrees C. The oil temperature of the fuel injection pump should be checked in the range of 40~45 degrees centigrade. This requirement can be adjusted by the oil temperature automatic control device installed by the injection pump test rig.
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