Oil pump suction and pressure oil, the plunger in the plunger sleeve reciprocation to complete. When the plunger is in the lower position, the two oil holes in the plunger sleeve are opened. The inner cavity of the plunger sleeve is communicated with the oil passage in the pump body, and the fuel is rapidly filled in the oil chamber.

The plunger rises as the cam hits the roller of the roller body. Move upward from the beginning of the plunger until the oil hole is blocked by the upper end of the plunger. During this time, due to the movement of the plunger, the fuel is squeezed out of the oil chamber and into the oil gallery. So this lift is called pre-stroke. When the plunger block the oil hole, it began to pressure process. Plunger up, oil chamber pressure rose sharply. When the pressure exceeds the spring force of the oil valve and the upper oil pressure, the oil valve is opened and the oil is pushed into the oil pipe by the oil pressure.

The time when the oil inlet hole on the plunger sleeve is completely blocked by the upper end surface of the plunger is referred to as the starting point of the theoretical oil supply.

Continue to move up the plunger, the fuel has been continued, the pressure process continues until the helical bevel on the plunger to open the plunger sleeve back to the oil hole so far, when the hole is opened, high pressure oil from the oil chamber by The longitudinal groove on the plunger and the oil return hole in the plunger sleeve return to the oil passage in the pump body. At this point the plunger sleeve oil chamber pressure rapidly reduced, the oil valve in the spring and high pressure tubing back to the valve seat, the injector immediately stop injection. At this point although the plunger is still up, but the oil supply has been terminated.

The plunger oil return hole is opened by the hypotenuse of the plunger is called the theoretical end of the oil supply.

From the above oil and pressure process can be seen in the plunger up the entire process, only the middle of a stroke is the process of pressure, this stroke is called the effective stroke of the plunger.

2, fuel adjustment

In order to meet the requirements of the diesel engine load, the injection pump fuel supply must be able to be in the range of the maximum fuel supply (full load) to zero fuel supply (parking) adjustment.

Fuel supply regulation is through the gear rod, rotating sleeve so that all the fuel injection pump plunger rotation to achieve.

When the plunger rotation, the fuel supply start time unchanged, and the end of the oil supply, due to the hypotenuse of the plunger sleeve back to the hole position change changed. With the different angles of rotation of the plunger, the effective stroke of the plunger is also different, so the amount of fuel supply also changes.

The greater the angle the plunger does not rotate the oil supply 1, the greater the distance between the upper end of the plunger and the hypotenuse of opening the oil return hole of the plunger sleeve, the greater the oil supply. If the plunger rotation angle is greater Small, the oil cut started earlier, the fuel supply is also smaller. When the diesel engine must be off when the oil, to this end, the longitudinal groove on the plunger can be turned directly to the plunger sleeve on the back hole. At this point, throughout the plunger stroke, the fuel in the plunger sleeve has been through the longitudinal groove, back to the oil hole back to the oil hole, there is no pressure process, so the fuel supply is equal to zero.

Therefore, when the plunger rotation, the use of change the end of the moment to adjust the amount of fuel supply, this method is called the oil end of the adjustment method.

Change the position of the bevel on the plunger, you can get other adjustment methods. The figure below shows the beveled shape of the plunger for the three fuel-conditioning methods.