How does a plunger pump work?

1) The plunger pump integrates a low-pressure gear type oil delivery pump, three high-pressure pump oil components with oil pump plungers, and an oil quantity control valve,

2) The working principle of the fuel transfer pump is to pump fuel from the fuel tank, pass through a filter with oil-water separation, pass through the inlet pipe, and then enter the high-pressure pump. The fuel transfer pump allows the fuel to pass through the relief valve's saving hole, and then enter the lubrication and cooling circuit of the high-pressure pump. The camshaft causes the plunger of three pumps to move up and down according to the shape of the cam.

3) The oil supply pressure exceeds the opening pressure of the relief valve, and the fuel pump can allow the fuel to enter the plunger chamber through the high-pressure pump inlet valve. The plunger of the high-pressure pump is moving downward (suction stroke), and when the plunger passes the bottom dead center, the inlet valve closes. So, the fuel inside the plunger chamber cannot possibly leak, it will be compressed with an oil pressure higher than the supply pressure.

4) The addition of oil pressure causes the outlet valve to open, and when it reaches the common rail pressure, the compressed fuel enters the high-pressure circulation (oil circuit). The plunger continues to supply fuel until it reaches the top dead center (fuel supply stroke). After the top dead center, the pressure decreases, causing the outlet valve to close. The fuel pressure still in the plunger chamber also decreases, and the plunger (pump oil plug) moves downward again. As long as the pressure inside the plunger chamber drops below the supply pressure of the oil pump, it is sufficient, the inlet valve opens again, and the pumping process begins again.