The total stroke L of the reciprocating movement of the plunger of the plunger pump is constant and is determined by the lift of the cam. The amount of oil supplied by the plunger per cycle depends on the oil supply stroke, which is not controlled by the camshaft and is variable. The start time of fuel supply does not change with the change of fuel supply stroke. Rotating the plunger can change the end time of the fuel supply, thereby changing the fuel supply. When the plunger pump works, under the action of the cam on the camshaft of the fuel injection pump and the plunger spring, the plunger is forced to reciprocate up and down to complete the oil pumping task. The oil pumping process can be divided into the following two stages.
Oil intake process
When the convex part of the cam turns over, under the action of spring force, the plunger moves downwards, and the upper space of the plunger (called the pump oil chamber) generates a vacuum degree. When the upper end of the plunger puts the plunger sleeve on After the oil hole is opened, the diesel oil filled in the upper body oil passage of the oil pump enters the pump oil chamber through the oil hole, the plunger moves to the bottom dead center, and the oil intake ends
Oil return process
The plunger supplies oil upwards. When the chute (stop supply side) on the plunger communicates with the oil return hole on the sleeve, the low pressure oil passage of the pump oil chamber is connected to the middle hole and radial hole of the plunger head When communicating with the chute, the oil pressure drops suddenly, and the oil outlet valve closes quickly under the action of the spring force to stop the oil supply. After that, the plunger will move up again. When the convex part of the cam is turned, the plunger will move down again under the action of the spring. At this point the next cycle begins. The plunger pump is introduced based on the principle of a plunger. A plunger pump has two check valves with opposite directions. When the plunger moves in one direction, negative pressure appears in the cylinder. At this time, a check valve opens and the liquid is sucked in. In the cylinder, when the plunger moves in another direction, another one-way valve is opened after the liquid is compressed, and the liquid sucked into the cylinder is discharged. After continuous movement in this working mode, continuous oil supply is formed.
