Variable pressure fuel injection system with dual flow rate injector

摘要

A variable pressure fuel injection system and multi-flow rate injector is provided which produces multiple fuel injection flow rates from a common source of pressurized fuel to enable reductions in emissions, combustion noise and particulates while improving fuel consumption. The present invention includes inner and outer needle valve elements biased into respective closed positions against respective valve seats for controlling the flow through corresponding sets of injection orifices. The movement of each valve is controlled by an injection control valve controlling the drain flow of control fuel from respective control volumes positioned at outer ends of the valve elements. Valve element bias spring preloads along with control flow orifices and needle valve element surface areas are selected to cause, for example, single valve operation at low fuel supply pressure and dual valve operation at high supply pressure.