Weichai Oil Pump 4110000556003 AZ1500070021A Made in China

The oil suction and pressure of the fuel injection pump is accomplished by the reciprocating motion of the plunger within the plunger sleeve. When the plunger is in the lower position, the plunger sleeve of the plunger

When the cam presses against the rollers of the roller body, the plunger rises. From the moment the plunger starts to move upward until the upper end face of the plunger blocks the oil hole, this period of time is when the fuel is squeezed out from the oil chamber and flows into the oil passage. During this period, due to the movement of the plunger, the fuel is pushed out from the oil chamber and flows into the oil passage. Therefore, this stroke is called the pre-stroke. When the plunger blocks the oil hole, the oil pressure pressurization process begins. As the plunger moves upward, the oil pressure in the oil chamber rapidly increases. When the pressure exceeds the spring force of the oil outlet valve and the upper oil pressure, it pushes the oil outlet valve open, and the fuel is pushed into the oil pipe and sent to the fuel injector.

The moment when the oil inlet hole on the plunger sleeve is completely blocked by the upper surface of the plunger is called the theoretical start point of oil supply. As the plunger continues to move upwards, the oil supply continues. The pressurized oil process lasts until the helical inclined edge on the plunger allows the oil inlet hole of the plunger sleeve to be clear, at which point the oil inlet hole is opened. Then, the high-pressure oil flows back from the oil chamber through the longitudinal groove on the plunger and the oil inlet hole on the plunger sleeve into the oil passage inside the pump body. At this time, the oil pressure in the oil chamber of the plunger sleeve rapidly decreases. The oil outlet valve, under the action of the spring and the oil pressure in the high-pressure oil pipe, falls back to the valve seat, and the injector immediately stops injecting oil. Although the plunger continues to move upwards at this time, the oil supply has ended.