Electric fuel pump (page 2 of 2)

The injector has the task of atomizing the fuel needed to form the fuel mixture. It is made from stainless steel in order to be resistant to any impurities which may be present in the fuel; it is centrally located on the injector holder turret above the butterfly valve.

It is made up of an outer casing (1) which contains a winding (2) with a ferromagnetic core (3) and a spring (4) which have the task of keeping the shutter (5) in the closed position in the housing in the casing (6). The assembly is completed by components such as the electrical contacts (7), the fuel inlet duct (8) and filter (9) and the fuel outlet duct (10) and filter (11).

The impulses, coming from the electronic control unit, reach the injector by means of electrical contacts (7), creating a magnetic field through the winding (2) at the core (3), raising the shutter (5) from its housing, overcoming the loading of the opposing spring (4) and causing the injector to open.

The lift of the shutter is 0.06 mm (distance x); taking the physical characteristics of the fuel as constant, the quantity injected only depends on the injector opening time (injection time) which is established by the electronic control unit according to the engine usage conditions.

The jet of fuel, coming out of the injector at a pressure of around 1 bar, is instantly atomized forming a cone of between 30° and 90° and is injected upstream of the accelerator butterfly. The operation of the injector is the synchronous type, i.e. one injection for each ignition.

There is an opening (12) in the accelerator butterfly which has the task of ensuring the optimum distribution of the mixture in the inlet manifold whilst the engine is warming up.