The function of the oil outlet valve for Marine diesel engine parts

The oil outlet valve of the DK28 diesel engine parts is a one-way valve. Under the action of the spring pressure, the upper conical surface of the valve fits tightly with the valve seat. Its function is to isolate the high-pressure oil pipe from the upper end cavity of the plunger when the supply is stopped, preventing the oil in the high-pressure oil pipe from flowing back into the fuel injection pump. The structure is simple and reliable. It does not change the working structure parameters, and the operation is not affected. It can be disassembled and reassembled repeatedly. The processing and manufacturing are simple and convenient for on-site assembly.

The function of the oil outlet valve

(1) To prevent oil dripping before injection and increase the injection speed: When the fuel injection pump supplies fuel, once the fuel pressure is higher than the pre-tightening force of the fuel outlet valve spring and the residual pressure in the high-pressure fuel pipe, the fuel outlet valve rises and its sealing conical surface leaves the valve seat. The fuel in the pump oil chamber can only enter the high-pressure oil pipe when the pressure-reducing band on the oil outlet valve is completely removed from the guide hole of the valve seat.

(2) To prevent oil dripping after injection and increase the closing speed: When the oil supply is stopped, as soon as the lower edge of the pressure-reducing zone of the oil outlet valve enters the conduit, the passage between the high-pressure oil pipe and the pump chamber is cut off. When the oil outlet valve is fully repositioned and drops by a distance of h, the volume of the high-pressure oil pipe increases, causing the oil pressure to drop rapidly by 1MPa to 2MPa. The oil cut-off is quick and decisive, preventing post-spray oil dripping caused by oil pressure fluctuations and "oil expansion due to pipe contraction".

(3) Prevent fuel backflow and maintain a certain residual pressure in the high-pressure oil pipe.