High Quality VE1 Delivery Valve 096420-0510 Diesel Engine Spare Parts

The oil outlet valve is an important component in the fuel injection system. The following is a detailed introduction to it:
Function

Pressure accumulation: During the plunger oil supply stroke, the oil inlet pressure is progressive, the initial oil supply pressure is increased, and the fuel can enter the high-pressure oil pipe with sufficient pressure to provide power for fuel injection.

Check: When the plunger moves downward, the volume becomes larger, the fuel pressure becomes smaller, and the oil outlet valve is quickly closed under the action of the spring and the upper pressure to prevent the fuel from flowing back into the injection pump, so that a certain residual pressure is maintained in the high-pressure oil pipe, and the injection delay phase of the next cycle is shortened.

Decompression: Using the unloading effect, the residual pressure of the fuel in the high-pressure oil pipe is reduced, the closing speed of the needle valve is increased, and oil dripping after injection is prevented, and secondary injection or repeated injection is avoided, ensuring the accuracy and timeliness of fuel injection.

Working principle
When the injection pump is working, the plunger reciprocates up and down under the action of the cam and the spring. During the oil supply stage of the plunger's upward movement, when the fuel pressure in the plunger cavity is higher than the preload of the oil outlet valve spring and the residual pressure in the high-pressure oil pipe, the oil outlet valve rises, its sealing cone leaves the valve seat, and the fuel enters the high-pressure oil pipe through the oil outlet valve. During the oil return stage of the plunger's downward movement, the oil outlet valve falls back to the valve seat under the action of the spring and the oil pressure in the high-pressure oil pipe, cutting off the passage between the high-pressure oil pipe and the plunger cavity. Among them, the pressure relief ring of the oil outlet valve plays a key role in pressure relief during the seating process. When the pressure relief ring enters the guide hole of the valve seat, the passage between the high-pressure oil pipe and the pump chamber is cut off. As the oil outlet valve continues to seat, the volume of the high-pressure oil pipe increases and the oil pressure drops rapidly.

Type
Isovolumetric oil outlet valve: Structurally, there is a circle of pressure relief belt under the sealing seat surface, and the pressure relief volume is formed by the seat surface sealing belt and the pressure relief belt. Its characteristics are fixed decompression volume, simple structure, good reliability, but at high speed and high load, the decompression may not be enough to produce secondary injection, and at low speed and low load, the decompression may be excessive to produce negative pressure vacuum to form bubbles, causing cavitation.

Isobaric oil outlet valve: A set of one-way valves composed of isobaric valves and springs are installed in the oil outlet valve core. It can automatically adjust the residual pressure after the oil supply is completed under various working conditions and keep it at a certain level higher than the atmospheric pressure, but the structure is relatively complex.

Damping oil outlet valve: Usually a damping valve is installed on the isobaric oil outlet valve, which has a throttling hole. It can slow down the seating speed of the oil outlet valve, delay the pressure drop speed, prevent bubbles from being generated and reduce cavitation, and attenuate the reflected wave to prevent secondary injection, but the residual pressure in the high-pressure oil pipe still changes with the working conditions, and the stability is worse than that of the isobaric oil outlet valve.

Buffering oil outlet valve: The traditional oil outlet valve is designed into two parts, the upper part is the unloading flange, and the lower part is the oil outlet valve cone and the buffer flange. It can slow down the seating speed of the oil outlet valve and ease the pressure fluctuation in the later stage of injection, but the pressure change of the injection system and the needle valve lift are delayed, and the dynamic response is worse than that of the isobaric oil outlet valve.

Orifice plate oil outlet valve: The high-pressure oil pipe can be directly connected to the oil outlet valve housing, reducing the volume of the high-pressure chamber. During the period when the oil supply stops and the oil outlet valve is seated, the high-pressure oil pipe is connected to the plunger chamber through the throttle hole, and the fuel flow is controlled through the throttle hole to prevent the generation of bubbles and the attenuation of the reflected wave after the oil outlet valve is seated.

Common faults
Wear: After long-term use, the sealing surface, pressure relief ring belt and other parts of the oil outlet valve may be worn, resulting in poor sealing, reducing the residual pressure in the high-pressure oil pipe, affecting the effect of fuel injection, and causing delayed injection, oil dripping and other phenomena, thereby affecting the power and economy of the engine.

Stuck: Due to impurities, colloids and other substances in the fuel, or engine overheating and other reasons, the oil outlet valve may be stuck in the open or closed position. If the oil outlet valve is stuck in the open position, fuel will continue to be supplied to the high-pressure oil pipe, causing problems such as excessive fuel injection and incomplete combustion; if it is stuck in the closed position, fuel will not be able to enter the high-pressure oil pipe, and the engine will not be able to start or work normally.

Spring failure: The oil outlet valve spring may weaken in elasticity or break. Weakened spring elasticity will reduce the closing pressure of the oil outlet valve, resulting in poor sealing; a broken spring will prevent the oil outlet valve from working properly, affecting the normal operation of the fuel injection system.