Patent ID: 7624721
Filing Date: 2009-12-01
Classification: F02D

Abstract:
1. A drive circuit for an injector arrangement comprising a first fuel injector in parallel with a second fuel injector, the drive circuit comprising: i) a selector switch arrangement operable to select the first fuel injector and/or the second fuel injector into the drive circuit and to deselect the first fuel injector and/or the second fuel injector from the drive circuit; ii) a first diagnostic tool operable, when the second fuel injector is selected and the first fuel injector is deselected: a) to sense a current through the first fuel injector; and b) to provide a first signal on detection of a stack terminal short circuit fault associated with the first fuel injector when the sensed current is at variance from a first threshold current; iii) a first charge storage device for operative connection with a selected one of the first and second fuel injectors during a charging phase so as to cause a charge current to flow therethrough; iv) a second charge storage device for operative connection with the selected one of the first and second fuel injectors during a discharge phase so as to permit a discharge current to flow therethrough; and v) a charge switch arrangement for operably controlling the connection of the selected one of the first and second fuel injectors to the first charge storage device or the second charge storage device, wherein, when the charge switch arrangement is actuated and either the first fuel injector or the second fuel injector is selected, the first diagnostic tool is operable, both to sense an open circuit current through the selected one of the first and second fuel injectors, and to provide a second signal on detection of an open circuit fault when the open circuit current is substantially the same as the first threshold current.