Importance

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Abstract

A fault detection method for detecting short circuit faults in an injector arrangement at engine start-up. The injector arrangement comprises one or more piezoelectric fuel injectors, which are connected in a drive circuit. In one aspect of the invention, the potential at a bias point in the drive circuit is determined and compared with a predicted voltage. A short circuit fault signal is generated if the potential at the bias point is not within a predetermined tolerance voltage of the predicted voltage. In another aspect of the invention, a first charge pulse is applied to the injectors to charge the injectors. A discharge current path is provided during a delay period following the first charge pulse by closing a discharge switch. A faulty injector will discharge through the discharge current path during the delay period. A second charge pulse is applied to the injectors following the delay period. Current flow is sensed during the second charge pulse, and a short circuit warning signal is generated if the current flow during the second charge pulse exceeds a predetermined threshold current.

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First Claim