Patent ID: 7971802
Filing Date: 2011-07-05
Classification: F02M

Abstract:
1. A fuel injector for use in delivering fuel to an internal combustion engine, the fuel injector comprising: a nozzle having a nozzle needle which is moveable with respect to a first needle seat to control fuel delivery through a nozzle outlet; a nozzle control valve for controlling fuel flow into a control chamber through a first passage to pressurise the control chamber, and for controlling fuel flow out of said control chamber through said first passage to depressurise the control chamber; a second needle seat with which the nozzle needle engages when the nozzle needle lifts from the first needle seat to its maximum extent; whereby movement of the nozzle needle is controlled by fuel pressure within the control chamber, such that pressurising the control chamber causes the nozzle needle to be urged against the first needle seat to close the nozzle outlet, and depressurising the control chamber causes the nozzle needle to lift from the first needle seat to open the nozzle outlet; wherein the nozzle needle defines, at least in part, a restricted passage through which fuel can flow into the control chamber as the control chamber depressurises, the fuel flow into the control chamber through said restricted passage serving to reduce the rate at which the control chamber depressurises, thereby reducing the rate at which the nozzle needle lifts from the first needle seat to open the nozzle outlet; and wherein engagement of the nozzle needle with the second needle seat closes the restricted passage to substantially prevent fuel flow into the control chamber through the restricted passage, thereby reducing parasitic losses of fuel during fuel delivery.