The function of the delivery valve
1, to prevent injection before drip, improve injection speed: The fuel pump when oil until the oil pressure is higher than the valve spring preload and the residual pressure inside the high-pressure pipeline, the oil valve rises, the sealing cone face off Open seat. We must wait until the decompression valve is completely off the seat of the pilot hole, pumping chamber of the fuel to enter the high-pressure pipeline.
2, to prevent fuel injection after the drop of oil, increase closing speed: When you stop oil supply, the oil pressure valve with the lower edge when an intake duct, high pressure tubing and pump chamber path will be cut off. When the valve is fully seat behind He dropped a distance h, thus the volume of high-pressure pipeline has been increased so that the oil pressure drops rapidly 1MPa ~ 2MPa, fast off the oil altogether prevented due to fluctuations in oil pressure and the "shrinking oil pipe up" and generate spray After the drop of oil.
3, to prevent backflow of fuel, so to maintain a certain residual pressure in the high-pressure tubing.
The oil valve is a one-way valve, the spring pressure, the upper conical valve seat surface and tight fit for its role in stopping when the upper end of the high-pressure tubing and the plunger cavity isolated, to prevent high-pressure pipeline Pour the oil flows into the fuel pump inside. The lower part of the valve was cross sections, both driven, but also by diesel fuel. There under the oil valve cone is a small cylindrical surface, known as the decompression zone, its role is When supply end, the hydraulic high-pressure tubing declined rapidly to avoid the spray holes produced drip phenomenon. When seat belts fall within the above volume so quickly increased pressure decreases rapidly, Minting fast speed. Work, under the action of the cam and the plunger spring in the fuel injection pump camshaft, forcing the plunger for the upper and lower reciprocating motion, thus completing the task of pumping, pumping process can be divided into the oil - oil -Oil return in three stages.