The medium pressure plunger pump is an important device in hydraulic systems. It relies on the reciprocating motion of the plunger in the cylinder body to change the volume of the sealed working chamber to achieve oil suction and pressure. Piston pumps have the advantages of high rated pressure, compact structure, high efficiency, and convenient flow regulation.

The total stroke L of the reciprocating motion of the plunger in the medium pressure plunger pump remains constant and is determined by the lift of the cam. The fuel supply amount per cycle of the plunger depends on the fuel supply stroke, which is variable and not controlled by the camshaft. The start time of fuel supply does not change with the variation of fuel supply stroke. Rotating the plunger can change the end time of fuel supply, thereby altering the fuel supply amount. When the plunger pump is working, the cam on the camshaft of the fuel injection pump and the plunger spring force the plunger to reciprocate up and down, thereby completing the pumping task. The pumping process can be divided into the following two stages.

1. Oil inlet process: When the convex part of the cam rotates past, under the action of spring force, the plunger moves downward, and the upper space of the plunger (called the pump oil chamber) generates a vacuum degree. When the upper end face of the plunger opens the oil inlet hole on the plunger sleeve, diesel filled in the oil passage of the upper body of the oil pump enters the pump oil chamber through the oil hole. The plunger moves to the bottom dead center, and the oil inlet is completed

2. Return oil process: The plunger supplies oil upwards. When the inclined groove (stop supply edge) on the plunger is connected to the return oil hole on the sleeve, the low-pressure oil circuit of the pump chamber communicates with the middle hole, radial hole, and inclined groove of the plunger head. The oil pressure suddenly drops, and the outlet valve quickly closes under the action of the spring force, stopping the oil supply. Afterwards, the plunger will continue to move upwards. When the protruding part of the cam rotates past, under the action of the spring, the plunger will move downwards again. At this point, the next cycle begins.

A plunger pump is introduced based on the principle of a plunger. There are two one-way valves on a plunger pump, and the directions are opposite. When the plunger moves in one direction, negative pressure appears in the cylinder. At this time, one one-way valve opens and the liquid is sucked into the cylinder. When the plunger moves in the other direction, the liquid is compressed and the other one-way valve is opened, and the liquid sucked into the cylinder is discharged. This working mode forms continuous fuel supply after continuous movement.

The service life of a medium pressure plunger pump is related to regular maintenance, the quantity and quality of hydraulic oil, and the cleanliness of the oil. Avoiding particles in the oil from causing wear and tear on the friction pair of the plunger pump is also an effective way to extend the service life of the plunger pump. When replacing parts during maintenance, it is advisable to use original factory produced parts as much as possible. These parts may be more expensive than other counterfeit parts, but they have better quality and stability. If you purchase cheap counterfeit parts, it may seem to save costs in the short term, but it may also bring hidden dangers and pose greater harm to the use of plunger pumps.