Plunger fuel pump structure based on the working principle

Fuel injection pump is the diesel fuel supply system, the most important piece, its performance and quality of diesel great influence, known as the "heart" of the diesel engine.

one. Function, requirement, type

Function: Increase diesel pressure, according to the working order of the engine, load size, timing and quantitative delivery of high pressure diesel fuel injector, and each cylinder equal pressure.

Claim:

(1) pump oil pressure to ensure the injection pressure and atomization quality requirements.

(2) The amount of fuel supply should be consistent with the exact number of diesel engine work required.

(3) Ensure that the diesel engine work order, accurate supply of oil within the prescribed time.

(4) adjustable fuel supply and fuel supply time, and ensure uniform fuel supply to each cylinder.

(5) The law of fuel supply should ensure that diesel combustion completely.

(6) start and end of fuel supply, agile, off the oil simply to avoid dripping.

Type: Automotive diesel injection pump according to their working principle can be divided into plunger-type injection pump, injection pump - injector and rotor dispensing pump three categories.

two. Piston pump pump oil principle

Piston pump pump mechanism consists of two sets of precision couplings:

Plunger and plunger sleeve is a pair of precision couplings that can not be interchanged after paired grinding, requiring high precision and smoothness and good wear resistance. The radial clearance is 0.002 ~ 0.003mm

Piston head cylindrical surface cut with a chute, and through the radial hole, the axial hole connected with the top, the purpose is to change the circulation of fuel supply; plunger sleeve system has into and back to the oil hole, both with the pump Low-pressure oil chamber connected to the body, the plunger set into the pump body, the positioning screw positioning.

Plunger head chute location, change the amount of fuel supply is also different. Outlet valve and the valve seat is also a pair of precision couplings, can not be swapped after grinding, with the gap of 0.01.

Outlet valve is a one-way valve, under the action of spring pressure, the upper conical surface of the valve is tightly matched with the valve seat. Its function is to cut off the high pressure oil pipe from the upper cavity of the plunger to prevent the oil in the high pressure pipe Inverted into the injection pump.

The lower part of the oil valve is cross-section, both to guide, but also through the diesel. Under the conical surface of the valve, there is a small cylindrical surface, called the vacuum ring, whose function is to quickly reduce the pressure of oil in the high-pressure tubing when the fuel supply ends, so as to avoid dripping oil at the orifice. When the ring falls into the valve seat, the upper volume increases rapidly, the pressure decreases rapidly, and the injection is stopped rapidly.

Pump oil principle

Work, the camshaft in the fuel injection pump camshaft and the role of the plunger spring, forcing the plunger up and down, reciprocating motion, thus completing the pump oil task, pump oil process can be divided into the following three stages.

Into the oil process

When the convex portion of the cam is rotated, the plunger moves downward due to the spring force. The upper space of the plunger (called the pump oil chamber) generates a vacuum. When the upper end of the plunger moves the plunger sleeve After the oil hole is opened, the diesel fuel filled in the upper body oil passage of the oil pump enters the oil pump chamber through the oil hole, and the plunger moves to the bottom dead center and ends in the oil inlet.

Oil supply process

When the camshaft turns to the convex portion of the cam, the plunger body is compressed and the plunger moves upward to compress the fuel. A part of the fuel flows back to the upper oil chamber of the injection pump through the oil hole. When the plunger top cover the upper edge of the sleeve into the oil hole, due to the small clearance between the plunger and sleeve (0.0015-0.0025mm) so that the top of the plunger pump chamber becomes a sealed oil chamber, the plunger Continue to rise, the pump oil chamber pressure rapidly increased, pump oil pressure> spring force of the valve + high pressure tubing remaining pressure, open the valve, high pressure diesel oil into the high pressure tubing through the injector Into the combustion chamber.

Return to the process

Plunger upward oil supply, when up to the plunger on the chute (stopping edge) and the sleeve connected to the oil return hole, the low pressure oil pump chamber and the plunger head of the hole and the radial hole And chute communication, a sudden drop in oil pressure, the oil valve in the spring force quickly closed, stop the fuel supply. After the plunger has to go up, when the convex part of the cam turn, under the action of the spring, the plunger down again. At this point they started the next cycle.

Conclusion: From the above discussion, the following conclusions can be drawn

① plunger reciprocating total travel L is constant, determined by the cam's lift.

(2) The amount of fuel supplied by the plunger per cycle depends on the fuel supply stroke, and the fuel supply stroke is variable regardless of the camshaft control.

③ fuel supply start time does not change with the change of fuel stroke.

④ Turn the plunger can change the fuel supply end time, thus changing the fuel supply.

The function of the Fuel System:

The function of the fuel system is to supply the car engine parts with a certain amount of clean and atomized gasoline, which can be mixed with a certain amount of air to form a combustible mixture according to the need of engine running condition. At the same time, the fuel system also needs to store a significant amount of petrol to ensure that the car has a considerable distance to continue driving mileage.

The main auto parts and functions of fuel system:

The fuel system also includes electronically controlled petrol injection systems, fuel supply systems (petrol tanks, petrol filters, petrol pumps, oil and gas separators, tubing and fuel gauges, and other ancillary devices).

Fuel System

Fuel System,Automotive Fuel System,Car Fuel System,Fuel Management System

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