Delphi Technologies Holding S.arl

Delphi Technologies, Inc.

Delphi Technologies IP Limited

Louisa J Perryman

Martin A P Sykes

Daniel Jeremy Hopley

Steven J Martin

Nigel P Baker

Nigel Baker

Steven Martin

Martin Sykes

A fault detection method is provided for detecting faults in an injector arrangement. The injector arrangement includes one or more piezoelectric fuel injectors connected in an injector drive circuit, and the injector drive circuit is arranged to control operation of the one or more piezoelectric fuel injectors. The fault detection method includes determining a sample voltage at a sample point in the injector drive circuit at a first sample time. The sample voltage is the voltage on an injector or is related to the voltage on an injector. The method further includes calculating a range of predicted voltages expected at the sample point at a second sample time following the first sample time, and determining the sample voltage at the sample point at the second sample time. The presence of a fault is detected if the sample voltage determined at the sample point at the second sample time is not within the range of predicted voltages.

Detection of faults in an injector arrangement

A method and apparatus for detecting faults in an injector arrangement is described. The injector arrangement comprises a plurality of piezoelectric injectors that are located in parallel branches of an injector bank circuit of an injector drive circuit. Each branch of the injector bank circuit comprises a high side isolation switch. The high side isolation switches are each operable to enable an associated piezoelectric injector in the injector bank circuit when closed, and disable the associated piezoelectric injector in the injector bank circuit when open. The fault detection method comprises the steps of operating the high side isolation switches so as to enable one of the piezoelectric injectors and disable the other piezoelectric injector(s), and performing diagnostics to detect the presence or absence of faults on the enabled piezoelectric injector.

A method of identifying an individual short circuit fuel injector, within an injector bank of an engine comprising a plurality of fuel injectors. Each fuel injector has a piezoelectric actuator and an associated injector select switch forming part of an injector drive circuit. The method comprises: (i) charging all of the piezoelectric actuators of the plurality of fuel injectors within the injector bank during a charge phase; (ii) at the end of the charge phase waiting for a delay period; and (iii) subsequently closing an injector select switch of a fuel injector to select said fuel injector. The method further comprises: (iv) determining a stack voltage present on terminals of the piezoelectric actuator of the selected fuel injector and storing the stack voltage in a data store. The stack voltage is indicative of an amount of charge present on the selected injector at the end of the delay period. The method further comprises (v) repeating steps (i) to (iv) for each fuel injector in the injector bank in turn; and (vi) identifying the individual short circuit fuel injector as being the injector which has discharged beyond a predetermined voltage drop limit during the delay period. The method also comprises generating a short circuit fault signal for the identified fuel injector.

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.

A method of detecting faults in an injector arrangement in an engine. The injector arrangement comprises at least one fuel injector having a piezoelectric actuator, and the method comprises: charging the piezoelectric actuator during a charge phase (t); attempting to recharge the piezoelectric actuator during a test phase (t) which commences after a time interval (&#x394;t) following the end of the charge phase (t); sensing a current (I) that flows through the piezoelectric actuator during the test phase (t); and generating a short circuit fault signal if the sensed current (I) reaches a first predetermined threshold current (I) which is indicative of a short circuit in the piezoelectric actuator.

The invention relates to a drive circuit for an injector arrangement having a fuel injector, and a method of detecting faults in the drive circuit. The drive circuit includes a diagnostic tool that senses a measured voltage between the injector and a known voltage level. The measured voltage is biased with respect to the known voltage to a predicted voltage unless the drive circuit has a fault. A fault signal is provided on sensing of a measured voltage that differs from the predicted voltage. The drive circuit may additionally, or alternatively, include a diagnostic tool. The diagnostic tool senses a detected current to provide a fault signal upon detection of the fault when the detected current is at variance from a threshold current.

Drive circuit for an injector arrangement and a diagnostic method

The invention relates to a drive circuit for an injector arrangement comprising a first fuel injector in parallel with a capacitive component. The drive circuit comprises: a selector means and diagnostic means. The selector means is operable to select the first fuel injector and/or the capacitive component into the drive circuit and to deselect the first fuel injector and/or the capacitive component from the drive circuit. When the capacitive component is selected and the first fuel injector is deselected, the diagnostic means is operable to sense a current through the first fuel injector. When the sensed current is at variance from a first threshold current the diagnostic means is operable to provide a first signal on detection of a stack terminal short circuit fault associated with the first fuel injector. The capacitive component may be a second fuel injector.

The invention relates to a drive circuit for an injector arrangement comprising a first fuel injector in parallel with a capacitive component. The drive circuit comprises: a selector means (SQ, SQ) and diagnostic means. The selector means (SQ, SQ) is operable to select the first fuel injector and/or the capacitive component into the drive circuit and to deselect the first fuel injector and/or the capacitive component from the drive circuit. When the capacitive component is selected and the first fuel injector is deselected, the diagnostic means is operable to sense a current (I) through the first fuel injector. When the sensed current (I) is at variance from a first threshold current (I) the diagnostic means is operable to provide a first signal on detection of a stack terminal short circuit fault associated with the first fuel injector. The capacitive component may be a second fuel injector.

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Rainham, United Kingdom

Louisa J Perryman