3.Fuel injection pump working principle – – structure
The fuel injection pump is mainly composed of a pumping mechanism, a fuel supply amount adjustment mechanism, a drive mechanism, and a fuel injection pump body. Wherein, the pumping mechanism comprises a plunger coupler, an oil outlet valve coupler, etc.; the oil supply amount adjusting mechanism refers to a rack type oil quantity adjusting mechanism or a fork type oil quantity adjusting mechanism; the driving mechanism comprises a cam shaft, a tappet assembly, etc. The fuel injection pump body is the mounting base of the above three, which requires sufficient strength, rigidity and sealing, and is easy to disassemble, adjust and repair.
4. Fuel injection pump working principle
Suction process: the plunger is driven by the cam of the camshaft. When the convex part of the cam leaves the plunger, the plunger moves down under the action of the plunger spring, the volume of the oil chamber increases, and the pressure decreases; when the plunger is sleeved When the radial oil inlet hole is exposed, the fuel in the low pressure oil chamber flows into the pump chamber along the oil inlet hole.
Pumping process: When the convex part of the cam pushes up the plunger, the volume in the pump chamber decreases, the pressure increases, and the fuel flows back to the low pressure oil chamber along the radial oil hole on the plunger sleeve; When the upward flow to the radial oil hole on the plunger sleeve is completely blocked, the pressure on the pump chamber increases rapidly; when the pressure overcomes the preload force of the fuel valve spring, the oil discharge valve moves up; when the oil discharge valve is on When the pressure relief belt leaves the valve seat, the high pressure diesel fuel is pumped into the high pressure oil pipe and injected into the cylinder through the injector.
Fuel return process: As the plunger continues to move upward, when the chute on the plunger communicates with the radial oil hole on the plunger sleeve, the fuel in the pump chamber passes through the axial oil passage on the plunger, obliquely The oil hole on the oil passage and the plunger sleeve flows back to the low pressure oil chamber, and the pumping stops.