Patent ID: 7966871
Filing Date: 2011-06-28
Classification: F02D,F02M

Abstract:
1. A method of identifying an individual short circuited fuel injector within an injector bank of an engine comprising a plurality of fuel injectors each having a piezoelectric actuator and an associated injector select switch forming part of an injector drive circuit, the method comprising the steps of: (i.) charging all of the piezoelectric actuators of the plurality of fuel injectors within the injector bank during a charge phase by applying a top rail voltage to a high voltage rail of said drive circuit; (ii.) at the end of the charge phase waiting for a delay period; (iii.) subsequently closing an injector select switch of a fuel injector to select said fuel injector during the charge phase such that the stack voltage of each piezoelectric actuator increases to a voltage approaching the top rail voltage; (iv.) determining a stack voltage present across the piezoelectric actuator of the selected fuel injector and storing the stack voltage in a data store, wherein the stack voltage is indicative of an amount of charge present on the selected injector at the end of the delay period; (v.) repeating steps (i) to (iv) for each fuel injector in the injector bank in turn; identifying an individual short circuited fuel injector as being the injector which has discharged beyond a predetermined voltage drop limit during the delay period; and generating a short circuit fault signal for the identified fuel injector.