No matter what kind of oil pump, the key is a "pump" word. The quantity, pressure and time of the pump oil should be very precise and adjusted automatically according to the load. Oil pump is a component with fine processing and complicated manufacturing technology. The oil pump of general automobile diesel engine at home and abroad is produced by a few specialized factories in the world.

The key part of the fuel injection pump is the plunger. If we use the common syringe in the hospital as the analogy, the movable plunger is called plunger and the syringe is called plunger sleeve. Suppose a spring is installed in the syringe to support one end of the plunger and the other end of the plunger contacts the camshaft. When the camshaft rotates around, the plunger will move up and down once in the plunger sleeve, which is the base of the plunger of the fuel injection pump. This exercise mode.

Plunger and plunger sleeve are very precise accessories. There is an inclined groove on the plunger body, and there is a small hole on the plunger sleeve called the suction port. This suction port is full of diesel oil. When the plunger inclined groove is opposite to the suction port, diesel oil enters the plunger sleeve. When the plunger is crowned by the camshaft to a certain height, the plunger inclined groove is staggered with the suction port, and the suction port is closed, so that diesel oil can neither be inhaled nor pressed out, and when the plunger continues to rise, When the pressure of diesel oil reaches a certain level, the one-way valve will be opened and rushed out into the injector, and then from the injector into the cylinder combustion chamber. A certain amount of diesel oil is discharged from the plunger each time, only part of it is injected into the cylinder, and the rest is discharged by the return hole, and the amount of oil discharged is adjusted by increasing or decreasing the amount of oil discharged.

When the plunger rises to the "top point" and moves down, the plunger inclined groove meets the suction port, and the diesel oil is sucked into the plunger sleeve, repeating the above action again. Each group of plunger system of in-line fuel injection pump corresponds to one cylinder, and there are four groups of plunger systems in four cylinders. Therefore, the plunger system of in-line fuel injection pump is relatively large and is mostly used in medium-sized and above-medium-sized vehicles. For example, diesel engines on buses and trucks generally use in-line fuel injection pumps.