Iveco Fiat S.p.a.

Dereco Dieselmotoren Forschungsund Entwicklungs-Ag

Christian Mathis

Gernot Amann

A high-pressure, continuous-delivery piston pump, controlled as a function of engine speed and load, supplies fuel to an accumulator supplying injectors. On the intake side of the pump, there is provided a throttle for metering the amount of fuel supplied by the pump. Via operating signals, the throttle is regulated by an electronic control device in such a manner as to supply the pump and pressurize only the amount of fuel strictly required for operating the injectors and the engine, thus eliminating any energy losses caused by fuel feedback to the tank, and drastically reducing fuel consumption.

Fuel injection system for an internal combustion engine

Upstream of the electrically operated fuel injectors for each engine cylinder there is connected a common pressure reservoir subject via a valve to the action of a continuously delivering fuel pump as a function of the engine speed and load. The common pressure reservoir is continuously connected by means of an annular chamber and a throttle to a channel in each fuel injector. Each fuel injector has a solenoid or magnetic valve operable for each fuel injection process and during the operation thereof connects said channel with a fuel return pipe and consequently relieves or releases the nozzle needle closing the fuel injection opening, thus releasing the discharge of fuel from a pressure chamber located directly upstream of the fuel injection opening. The channel is continuously connected via a throttle bore bridging a check valve to a control chamber controlling the nozzle needle movement. The pressure chamber is connected to a second pressure chamber associated with the related fuel injector and located in the vicinity thereof and is connected by the second pressure chamber to the common pressure reservoir. The fuel injection course can be influenced by the size of the throttle bore and the subdivision of the fuel storage volume into two pressure chambers. It is in particular possible to delay the ascent in the fuel injection rate during the fuel injection starting phase and consequently to reduce combustion noise and the emission of pollutants.

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Arbon, Switzerland

Christian Mathis