When working, under the action of the cam and plunger spring on the camshaft of the injection pump, the plunger is forced to reciprocate up and down, and then the oil pumping task is completed, and the oil pumping process can be divided into the following three periods.
Oil feed process
When the cam bulge is somewhat turned, under the action of spring force, the plunger moves downward, the upper space of the plunger (called the pump oil chamber) occurs vacuum, when the upper end face of the plunger turns the oil inlet hole on the plunger sleeve, the diesel fuel covered 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 intake is completed.
Oil supply process
When the camshaft turns to the bulge of the cam and some jacks the roller body, the plunger spring is tightened, the plunger moves upward, the fuel is pressurized, and some fuel flows back to the upper body oil cavity of the fuel injection pump through the oil hole. When the top surface of the plunger covers the upper edge of the sleeve traveling oil hole, because the cooperative vacancy between the plunger and the sleeve is very small (0.0015-0.0025mm), the pump oil chamber at the top of the plunger becomes a sealed oil chamber, the plunger continues to rise, the oil pressure activation in the pump oil chamber increases, and the pump oil pressure > When the spring force of the oil outlet valve + the remaining pressure of the high-pressure oil pipe, push the oil outlet valve, and the high-pressure diesel enters the high-pressure oil pipe through the oil outlet valve and is injected into the combustion chamber through the injector.
Oil return process
The plunger supplies oil upward, and when the chute (stop supply side) on the plunger goes up to the oil return hole on the sleeve, the low-pressure oil circuit of the pump chamber communicates with the middle hole and radial hole and chute of the plunger head, the oil pressure drops, and the oil outlet valve is closed under the action of spring force, and the oil supply is supplied successively. After that, the plunger also has to go up, and when the cam bulge is somewhat turned, under the action of the spring, the plunger goes down again. This is where the next cycle begins
