How to repair denso common rail injector-4
Diesel High Pressure Common Rail System?

Fuel pump dispensing volume adjustment and the reasons for the uneven distribution



Adjust the oil on the test bench of the fuel pump, and the oil distribution is uneven after installation; main reason is the use of debugging state and the different conditions, the existence of debugging supply imbalance, mechanical wear and tear, the Oil valve spring failure; fuel pump installed after adjustment method.

Diesel fuel injection pump is an important component of the supply system, usually in the pilot stage of adjustment after the supply capacity use, sometimes even such a power shortage, smoky exhaust, speed instability of the unusual circumstances. Debugging was mainly due to the fuel pump and the actual supply of oil into the cylinder and the cylinder or inconsistent supply of heterogeneity caused by the direct impact of the diesel engine power, economy and reliability.

Fuel pump dispensing volume adjustment and the reasons for the uneven distribution

First, the reasons for the uneven supply fuel pump

1. Debug state and the different conditions of use

Fuel pump is in the test bench at room temperature for debugging, and the installed capacity is the use of compression in the cylinder end, the cylinder temperature of 500 to 700, 3 to 5 MPa pressure under the conditions of use, the difference is greater. Locomotive operation, the fuel pump and injector temperature reached 90, causing diesel will decrease the viscosity, thus plunger and the needle-and the leakage increased to fuel more than debugging.

According to the determination of the actual injection pump the fuel is injected into the cylinder test bench commissioning of only about 80%, although the pump debugging staff will consider this factor, but it is impossible to accurately grasp. In addition, since the piston and the cylinder valve train wear or confined in varying degrees, the cylinder compression pressure and the temperature will be a difference. Even if the test bench debugging good fuel pump installation, use, the cylinder volume of oil will produce uneven.

2. Debugging existing supply uneven

Debugging in the fuel pump test bench, in the request the cylinder rated speed of the unevenness of oil should be <3%. Actual debugging process, as a test bench for the injector and high pressure tubing length, shape, diameter, and so can not be fully consistent with the original machine, coupled with the difference in debugging technology, fuel pump installed, the actual oil injected into the cylinder often uneven volume of> 3%.

3. Mechanical failure caused by uneven supply

After long-term use of motorcycles, or fuel pump drive coupling gap too large, drive gear wear, backlash increases will also affect the uniformity of cylinder oil. In addition, high-pressure pipeline joints due to frequent vibration or tightened enough leakage, and the tightening of the joint Ambassador metal loss and blocked the pipeline, the same will be caused tanks of oil uneven.

In addition, the fuel pump and the governor in the spring, one of the strong deformation larger, higher operating frequency was the plunger spring. Therefore, its higher frequency broken. Light, Fuel Injector reduction in the volume of the cylinder fuel injection uneven, the cylinder fuel injection interval ultra-poor, injector start time delay to heavy oil supply interruption can not even supply.

Second, the fuel pump installed after further adjustment

1. Fuel pump to the basis for the adjustment

 According to the cylinder and the exhaust temperature, pressure or breathing color to determine their actual work with the diesel engine combustion of the fuel supply tank to determine the volume too much or too little, too early or too late supply, and then to readjust . Through appropriate adjustments in the oil tank and dispensing time for the fuel pump to the cylinder diesel engine to remove the cylinder real difference.

2. Further adjustment of the injection pump technique

(1) fuel pump installed, according to the required standards for good oil supply, exhaust manifold unloaded at the same time, to observe the work of the cylinder.

(2) start diesel engine, idling 2 ~ 3 mins, hand-to-mouth and the cylinder exhaust injector near the cylinder head, if a cylinder temperature is too high, may be initially determined that the cylinder of excessive supply.

(3) When the temperature of more than 50, increasing throttle, the engine operates at the rated speed, the exhaust ports at the same time see the smoke color, to listen to the voice of the cylinder. If a cylinder smoky, the excessive supply, construction machinery installed to spend more of the 135 series engine as an example, the fuel pump can be regulated to stop oil tooth-pulling direction, loosened regulation on the locking screw gear , a small crowbar take control of the oil sleeve inserted in the holes with hammer tapping to the right moment, can reduce the supply of, otherwise increase.

When a cylinder with sharp percussion sound, and start difficulties, the supply began prematurely; if a cylinder temperature high, and even flame out, it may be late starting time is supply. Such as the 135 series engine, the cylinder oil starting time adjustment, is the location of the plunger pumps decision. When the late starting time of supply, should regularly adjusting nut and screw some rotation, the starting time of early oil, some of this screw tightening.

(4) Check supply advance angle

General Oil Spill Act can be used to check supply advance angle, will be a high-pressure pump tubing joints loosened, will be connected to the injector end of the connector removed the tubing to the horizontal position, and then fasting the pump high-pressure tubing joints, throttle rafah the greatest location, open decompression shake cars until the high-pressure pipeline exports out a few drops of diesel.

Wiped off the milk tubing exit diesel, then slowly rotating flywheel. At the same time attention to the observation of the high-pressure pipeline export of oil, in its start moving moment on the immediate cessation of rotating flywheel. At this point, the body of water or line should be engraved on the flywheel at the only point in the first 16 ~ 20 between. If the two are in alignment before the oil spill, the oil advance angle too premature supply; only if more than oil spills, the supply advance angle is low, supply is too late.

It should be noted that, for multi-cylinder diesel engine, to install a special glass tube and indicators, measuring cylinder compression on the first point and only started when oil on the fan belt pulley arc between the two marks to determine supply advance angle is correct. At the same time, every single pump dispensing checks whether the same batch, if different, adjustable Tappet plunger and the clearance between the oil pump and the body or between the gasket thickness, the intermittent supply reach consensus.

After more than the early transfer, check-cylinder exhaust temperature is consistent, if it can not resume the normal work of the engine, the cylinder pressure measurement should be whether or not within the scope of the permit and, if necessary, replace the valve piston ring or grinding, inspection Injector the spray conditions and opening pressure is normal.e the risk of misalignment or breaking the dowel pins.