Plunger unit of Fuel Injection Pump : Construction and working

The plunger unit of fuel injection pump (FIP) is an important mechanical parts of the Fuel injection pump. Which pump the incoming fuel with high pressure to the injectors through high pressure pipe line. Every fuel injection pump have plungers equal quantity of the engine cylinder. Now we are going to learn about plunger unit of fuel injection pump.

Construction of plunger unit of fuel injection pump:-

The plunger unit of fuel injection pump have a pusher assembly which pushed the plunger unit when cam of the FIP cam shaft is comes under the pusher assembly.

The plunger unit of fuel injection pump have a adjusting nut and locking nut for adjust the caliper adjusting. It have upper and lower returned plates. The lower retainer plate is known as horse nail also. Both plates are retain the returning spring of the plunger unit of fuel injection pump.

The plunger unit of fuel injection pump have a sleeve which covered by the quadron sleeve which gives the rotational movements to the plunger.

The plunger have vertical and helical grooves which helps to control or supply of the fuel to the injectors.

Working of plunger unit of fuel injection pump:-

The FIP cam shaft starts received drive along with engine starting and start rotates. When the cam of the FIP cam shaft comes below the pusher assembly, then the pusher assembly moves upward and due to this the plunger unit is also moves upward and press the fuel of the fuel barrel which comes from fuel gallery.

But the driver do not press the accelerator pedal right now so the vehicle is still start in idling condition. In idling condition the helical groove of the plunger unit of fuel injection pump is aligned with spill hole of the fuel barrel in some amount. That's why there is some fuel is pressed by the plunger unit and goes to the injector but some amount of fuel drain into the fuel gallery.

When driver push the accelerator pedal then the movement of the accelerator pedal is goes to the rack shaft and rack shaft move forward. The serration of the rack shaft are always remains meshed with the serration of the quadron sleeve so the quadron sleeve is also rotate.

Because of rotation of the quadron sleeve the plunger unit of fuel injection pump is also rotate and the helical groove and spill hole both are dis-aligned and the full fuel is pressed and supply by the plunger to the injectors and the injectors spray the maximum fuel into the combustion chamber. In resulting the vehicle running in maximum speed.