Abstract: A SCR doser includes an electrical adapter extending from an inner end electrically connected to the pins of a solenoid to an outer end having electrical terminals. The outer end outwardly protrudes from an aperture provided in a base wall of the housing of the SCR doser.

Abstract: In a selective catalytic reductant dosing system including a reductant injector adapted to inject liquid reductant into an exhaust line, a method of analyzing flow of reductant through the injector includes determining a measure of the temperature of the injector prior to activation of the injector. The method also includes activating the injector and determining a measure of the temperature of the injector subsequent to activation of the injector. The method also includes analyzing the flow of reductant through the injector consequential to the activation by analyzing changes in the measure of temperature of the injector prior to activation and the measure of temperature of the injector subsequent to activation.

Abstract: A method is provided for purging a selective catalytic reduction dosing system having a urea reservoir and a urea delivery module including at least one pump and a dosing injector arranged to spray urea into an engine exhaust pipe and a feedline. The method includes: (1) activating a reverse pump or a pump in a reverse direction; (2) opening the dosing injector; (3) stopping the reverse pump or reverse direction of the pump and closing the dosing injector; (4) activating a forward pump or a forward direction of the pump; (5) stopping the forward pump or forward direction of the pump and opening the dosing injector; and activating the reverse pump or reverse direction of the pump.

Abstract: A SCR doser includes an electrical adapter extending from an inner end electrically connected to the pins of a solenoid to an outer end having electrical terminals. The outer end outwardly protrudes from an aperture provided in a base wall of the housing of the SCR doser.

Abstract: A method is provided for purging a selective catalytic reduction dosing system having a urea reservoir and a urea delivery module including at least one pump and a dosing injector arranged to spray urea into an engine exhaust pipe and a feedline. The method includes: (1) activating a reverse pump or a pump in a reverse direction; (2) opening the dosing injector; (3) stopping the reverse pump or reverse direction of the pump and closing the dosing injector; (4) activating a forward pump or a forward direction of the pump; (5) stopping the forward pump or forward direction of the pump and opening the dosing injector; and activating the reverse pump or reverse direction of the pump.

Abstract: In a selective catalytic reductant dosing system including a reductant injector adapted to inject liquid reductant into an exhaust line, a method of analyzing flow of reductant through the injector includes determining a measure of the temperature of the injector prior to activation of the injector. The method also includes activating the injector and determining a measure of the temperature of the injector subsequent to activation of the injector. The method also includes analyzing the flow of reductant through the injector consequential to the activation by analyzing changes in the measure of temperature of the injector prior to activation and the measure of temperature of the injector subsequent to activation.

Abstract: A fluid injector comprising a coil arranged to drive a pump from a first state to a second state when energized, so as to pump a dosing fluid; a PN junction electrically arranged across the coil to discharge energy stored in the coil when the voltage across the coil is above a threshold. In one particular embodiment, the fluid injector is a selective catalytic reduction dosing fluid injector.

Abstract: A diagnostic circuit arranged to measure an electrical characteristic in a drive circuit of a coil of a fluid injector and compare the measured electrical characteristic with another electrical characteristic to determine whether a PN junction is working to discharge electrical energy in the coil of the fluid injector, in particular a selective catalytic reduction dosing injector.

Abstract: A fluid injector comprising a coil arranged to drive a pump from a first state to a second state when energized, so as to pump a dosing fluid; a PN junction electrically arranged across the coil to discharge energy stored in the coil when the voltage across the coil is above a threshold. In one particular embodiment, the fluid injector is a selective catalytic reduction dosing fluid injector.

Abstract: A diagnostic circuit arranged to measure an electrical characteristic in a drive circuit of a coil of a fluid injector and compare the measured electrical characteristic with another electrical characteristic to determine whether a PN junction is working to discharge electrical energy in the coil of the fluid injector, in particular a selective catalytic reduction dosing injector.

Abstract: 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.

Abstract: A method and apparatus for controlling fuel injection in an engine is described. The apparatus comprises at least one fuel injector which is connected in an injector drive circuit powered by a power source. The method comprises determining an injection event sequence of the at least one fuel injector based on at least one engine operating parameter, determining a magnitude of a load parameter of the power source, comparing the magnitude to a predetermined threshold level for the load parameter, and determining a modified injection event sequence in the event that the magnitude is substantially equal to or greater than the predetermined threshold level.

Abstract: 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 (tC); attempting to recharge the piezoelectric actuator during a test phase (tT) which commences after a time interval (?t) following the end of the charge phase (tC); sensing a current (IS) that flows through the piezoelectric actuator during the test phase (tT); and generating a short circuit fault signal if the sensed current (IS) reaches a first predetermined threshold current (ISC) which is indicative of a short circuit in the piezoelectric actuator.

Abstract: A fuel injector control method comprises determining a required separation time between a termination of an on signal associated with a first injection event and an initiation of an on signal associated with a second injection event. The method comprises calculating an overlap time between the separation time and the time to charge the piezoelectric stack to a first level; dividing the overlap time into first and second time periods as a function of the charge and discharge currents; applying the charge current to the piezoelectric stack for a charge time; and applying the discharge current to the piezoelectric stack for a discharge time so as to discharge the stack to a second level, wherein the discharge time is calculated on the basis of the second time period of the overlap time. Thus, first and second injection events are merged in a pulse mode of operation.

Abstract: 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.

Abstract: 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.

Abstract: A fuel injector control method comprises determining a required separation time between a termination of an on signal associated with a first injection event and an initiation of an on signal associated with a second injection event. The method comprises calculating an overlap time between the separation time and the time to charge the piezoelectric stack to a first level; dividing the overlap time into first and second time periods as a function of the charge and discharge currents; applying the charge current to the piezoelectric stack for a charge time; and applying the discharge current to the piezoelectric stack for a discharge time so as to discharge the stack to a second level, wherein the discharge time is calculated on the basis of the second time period of the overlap time. Thus, first and second injection events are merged in a pulse mode of operation.

Abstract: 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.

Abstract: 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.

Abstract: A method and apparatus for controlling fuel injection in an engine is described. The apparatus comprises at least one fuel injector which is connected in an injector drive circuit powered by a power source. The method comprises determining an injection event sequence of the at least one fuel injector based on at least one engine operating parameter, determining a magnitude of a load parameter of the power source, comparing the magnitude to a predetermined threshold level for the load parameter, and determining a modified injection event sequence in the event that the magnitude is substantially equal to or greater than the predetermined threshold level.