Oil pump suction and pressure, the plunger in the plunger set in the reciprocating movement to complete. When the plunger is located in the lower position, the two oil hole in the plunger sleeve is opened, communicated with the oil plunger cavity and the pump body, the fuel oil filling chamber. When the cam is pushed onto the roller of the roller body, the plunger is raised. From the beginning of the plunger movement up to the oil hole is blocked by the upper end of the plunger. During this period of time, due to the movement of the plunger, the fuel is squeezed out from the oil chamber and flows into the oil channel. So this process is called pre stroke. Oil pump when the plunger will block the oil hole, then began to press the oil process. Plunger up, oil chamber oil pressure increased sharply. When the pressure exceeds the spring force and the upper oil pressure of the oil valve, the oil valve is opened on the top, and the fuel oil pressure of the oil pipe is sent to the fuel injector.
The time that the oil inlet on the plunger sleeve is completely blocked by the plunger on the end face of the plunger is known as the theoretical fuel supply starting point. The plunger to continue upward movement, oil has continued, oil pressure process continues until the plunger on the spiral bevel move the plunger sleeve oil return hole, when the oil hole is opened, high pressure oil from the oil chamber through the plunger on the longitudinal slot and the plunger sleeve oil return hole on the back of the oil pump body. At this point, the oil pressure of the oil pump plunger oil chamber is rapidly reduced, and the oil pressure of the oil valve in the spring and the high pressure oil pipe falls back to the valve seat. At this time, although the plunger continues upward, but the supply has been terminated. The plunger sleeve oil return hole is the hypotenuse open end times supply theory. In the plunger upward movement of the entire process, just the middle of a stroke is the process of pressure, which is known as the plunger of the effective stroke.
