High Quality VE1 Delivery Valve 131110-8820 A69 Diesel Engine Spare Parts

Cut off the fuel and prevent dripping
Action scenario: When the plunger of the injection pump moves downward (stops fuel supply), the outlet valve closes quickly, cutting off the passage between the high-pressure oil pipe and the oil pump.

Principle:
There is a sealing cone at the bottom of the outlet valve. When the plunger stops pumping oil and the oil pressure drops, the outlet valve quickly seats under the action of the spring force, and the sealing cone fits the valve seat to prevent the fuel in the high-pressure oil pipe from flowing back into the oil pump.

Significance:
Avoid dripping of the injector due to the drop in oil pipe pressure after the oil is stopped, prevent poor fuel atomization, incomplete combustion or contamination of the combustion chamber.
Maintain a certain static pressure (residual pressure) in the high-pressure oil pipe to prepare for the next injection, ensure that the pressure is quickly established in the initial stage of injection, and the injection is more crisp.

Control the start and end of the fuel injection process
1. Injection start stage
When the plunger of the injection pump compresses the fuel upward, the oil pressure increases, and after overcoming the outlet valve spring force and the residual pressure in the high-pressure oil pipe, the outlet valve is lifted up.
When the outlet valve is lifted, its pressure relief ring (the cylindrical surface above the sealing cone) gradually leaves the valve seat, and the high-pressure fuel enters the high-pressure oil pipe through the outlet valve channel and starts to supply fuel to the injector.

2. End of injection stage
When the plunger reaches the end of the fuel supply, the oil pressure in the plunger chamber drops, and the outlet valve falls back under the action of the spring force.
First, the pressure relief ring cuts into the valve seat hole to block the fuel passage. At this time, the high-pressure oil pipe is isolated from the oil pump;
Then, the outlet valve continues to seat, the sealing cone fits, and the oil is cut off.
The key role of the pressure relief ring:
When the pressure relief ring cuts into the valve seat, it will give up a part of the volume (called the pressure relief volume), so that the volume in the high-pressure oil pipe increases instantly, and the oil pressure drops rapidly (by about 10-20MPa), ensuring that the injector stops spraying immediately to avoid secondary injection (after the injection is completed, the oil pipe pressure fluctuates and then sprays again) or intermittent injection (unstable dripping).

Maintain stable pressure in the high-pressure oil pipe
Residual pressure control:
The preload of the oil outlet valve spring and the design of the pressure relief ring jointly determine the residual pressure in the high-pressure oil pipe.
If the residual pressure is too high: it may cause abnormal opening pressure of the injector, or even oil leakage at the non-injection time;
If the residual pressure is too low: the pressure builds slowly during the next injection, and injection delay and poor atomization may occur.
Adapt to different working conditions:
Under different engine loads (such as idling and full load), the oil outlet valve maintains a stable residual pressure to ensure that the injector can achieve stable and accurate fuel injection volume and injection timing under various working conditions.

Filtering and buffering effect (partial structure)
Built-in filter (partial oil outlet valve):
Some oil outlet valves are equipped with a filter or filter element at the oil inlet end to filter impurities in the fuel (such as metal debris, colloidal particles) to prevent clogging of the injector or wear of precision parts (such as plunger pair, needle valve pair).
Buffering fuel shock: During the opening and closing process of the oil outlet valve, the damping effect of the spring and the pressure relief ring can buffer the pressure fluctuation of the fuel, reduce the pressure shock (water hammer effect) in the high-pressure oil pipe, and protect the sealing of the oil pipe and the injector.