Through the analysis of the structure and composition of the diesel fuel injection pump, this paper finds out the location of the fuel injection pump that is prone to failure, and puts forward the correct disposal method to provide users with correct and reliable basis for use.
[Keywords] diesel engine; fuel injection pump
Fuel injection pumps (also known as high-pressure diesel pumps) are one of the most sophisticated components in the fuel supply system for diesel internal combustion engines. Often referred to as the "heart" component of the engine, the structural process is extremely precise. In use, the precision components that make up the fuel injection pump will directly affect the power, economy and service life of the internal combustion engine when the technical conditions change.
According to the experience of use, the common problems in the use of fuel injection pumps are: parts wear, oil supply error, oil supply error, oil supply disorder, uneven oil supply, zero fuel supply and so on.
Long-spectrum multi-diesel users, knowledge of the use, structure, correct use, and easy problems of the fuel injection pump, the impact on the power, economy, and service life of the internal combustion engine and how to restore the function of the fuel injection pump are well known. There is not much mastery. In order to give full play to the performance of the engine, reduce fuel consumption and extend its service life; this article is for the user's reference.
First, the structure and function of the fuel injection pump
In order to facilitate the understanding and mastery of the analysis and disposal methods of the Yishangshan in the use of the fuel injection pump, the structure and function of the fuel injection pump should be familiar with first.
Commonly used fuel injection pumps have the following categories:
(1) In-line fuel injection pump: There are split fuel injection pumps and synthetic fuel injection pumps.
(2) Dispensing type fuel injection pump: There is a rotor type distribution pump and a plunger type distribution pump.
The fuel injection pumps widely used in high-speed diesel engines are all plunger pumps. For example, the 413F series air-cooled diesel engine and the 6V150 Li 12V150 water-cooled diesel engine are all straight plunger synthetic fuel injection pumps. Its structure is similar. They are composed of the main components such as the plunger servant, the Shanyou valve, the oil quantity control mechanism and the drive mechanism. The basic structure is shown below:
1. Oil outlet valve joint 2. Oil outlet valve spring 3. Oil outlet valve coupling 4. Fuel injection pump body
5. Low pressure chamber 6. Worm 7. Oil quantity control sleeve 8. Plunger spring
9. Tappet body parts 10. Camshaft 11. Spring seat 12. Plunger coupler
11. Adjust the ring gear 14. Enter the oil hole
The fuel injection pump is mainly used to increase the pressure of the quantitative fuel according to the order of the cylinders of the engine, and timely press into the injector. Then, the fuel is evenly, finely and uniformly injected into the combustion chamber by the injector, and mixed with the compressed air to form a good combustible mixture, and the combustion work.
Second, problems, causes, effects on the performance of internal combustion engines and disposal methods
(1) Parts wear
The wearing parts of the fuel injection pump mainly include wear of the plunger coupler, wear of the oil outlet valve, wear of the drive member, spring breakage and oil pipe breakage.
1, the plunger part wear
The plunger coupler has high precision (with a clearance of 0.002 to 0.004 mm), finish and surface hardness. However, as the use time increases, the relative moving surface acts on mechanical wear and abrasive wear. The fit clearance will change. The general rule is that the gap increases due to wear. The oil leakage is increased, the oil supply is reduced, and the oil supply pressure is lowered: the injection timing of the injector is delayed, and the fuel injection time of the injector is reduced. As the oil supply pressure is lowered, the spray quality of the injector will be deteriorated, which will easily cause the engine to start difficult, the power is insufficient, and the fuel consumption rate increases; especially when the engine is running at a low speed, the oil leakage is more obvious, and the actual oil supply amount The decline is more and the difference is very human, resulting in unstable engine running at low speed and easy to extinguish.
In use, the fuel of the specified grade should be ensured, the oil supply to the fuel injection pump should be cleaned, the opening pressure of the injector needle should not be too large, and the oil supply amount should be changed smoothly to slow the wear of the plunger even I:. If the engine power is reduced due to the wear of the plunger coupler, the plunger coupler should be replaced in time.
2, the oil valve even wear
After the oil valve coupler is used frequently, due to the unclean fuel, high-speed impact during work, high-pressure fuel scouring and acid corrosion, many irregular dents will be formed on the oil delivery valve coupler. The tapered mountain is now annularly recessed, and the wear of the guiding surface hinders the centering of the tapered surface. As a result, the oil valve coupler wears and is not closed. When the oil valve coupler wears unevenly and the seal is not strict, the fuel return in the high pressure oil pipe is too much, and when the residual pressure is excessively reduced, the time of the next oil supply is postponed, and the actual oil supply amount is reduced. As a result, the combustion of each cylinder of the engine is not regular, the work is not stable and the power is reduced. In use, the tightness of the oil valve coupler should always be checked. If it is not closed, it should be cleaned, ground or replaced in time.
3, the drive parts wear
The wear of the drive member mainly refers to the change of the size of the upper and lower end faces of the cam and the tappet caused by the lubrication condition and the constant high-speed impact. Wear of the drive member will cause the fuel injection pump to start to be delayed, before the oil supply end time. When the fuel pump drive parts wear out inconsistently, not only the engine oil supply is too late, but also the engine cylinders work unevenly. Will cause the engine to work unstable, smoke, sound, and speed will be abnormal. Especially when using the later fuel injection pump, the above phenomenon is more obvious when the driving parts are seriously worn. The fuel pump should be adjusted, corrected or replaced at this time.
4, the spring is broken
The fuel pump plunger return spring and the mountain oil valve co-located spring may break due to materials, processing technology, installation process, long-term high-speed compression, tensile fatigue during operation, and sudden change in speed at low temperature. When the return spring is broken, the lighter returning the component to the position is weak or not timely, which will affect the engine oil supply pressure, fuel supply and fuel supply timeliness, thus affecting the engine's power and economy. The heavy one will cause the engine to "fly" (scarred), causing engine damage. When the engine "speeding" fault occurs, do not cut off the power contact (step clutch or gear). The brake should be turned off with the brake "蹩" or the fuel supply should be cut off in time to automatically turn off the flame. To preserve the engine.
5, tubing fracture
The cracking of the pump oil pipe (high pressure oil pipe) occurs mostly near the oil pipe joint, and the force is strong and weak. The only reasons are: improper installation, distortion of the pump tubing, additional stress; excessive engine load for a long time, unstable operation, vibration plus brush, will also produce greater stress; over time, fatigue fracture. In addition, the quality of the pump tubing is poor, the wall thickness is uneven, the strength is not enough, or the injection pressure is too high (when the injector needle is pulled down), the deformation and breakage are likely to occur during the work. In use, if the tubing is found to be broken, measures such as dressing compression, broken cylinder operation (multi-cylinder engine), welding repair, and replacement of new tubes may be taken.
Shanghai Diesel Pump Manufacturer