Abstract: A fuel injector comprising a valve needle which is slidable within a bore, a surface associated with the valve needle defining, in part, a control chamber which communicates, through a restriction, with a supply passage. The fuel injector also includes an injection control valve controlling communication between the control chamber and a low pressure reservoir, and a drain valve controlling communication between the supply passage and the low pressure reservoir. The injection control valve and the drain valve include respective armatures moveable under the influence of a common electromagnetic actuator.

Abstract: A method of incorporating noise considerations during circuit optimization includes the steps of: specifying a circuit schematic to be optimized; specifying at least one noise criterion as a noise measurement, including the signal to be checked for noise, the sub-interval of time of interest, and the maximum allowable noise deviation; providing each noise criterion as either a semi-infinite constraint or a semi-infinite objective function; specifying at least one variable of the optimization; converting the semi-infinite noise constraints and the semi-infinite noise objective functions into time-integral equality constraints; optionally, if required, providing additional optimization criteria other than noise as, for each such criterion, either objective functions or constraints; creating a merit function to be minimized to solve the optimization problem; simulating the circuit in the time-domain; computing the values of the objective functions and constraints; efficiently computing the gradients of the merit

Abstract: An injector arrangement is disclosed which comprises a valve needle urged into engagement with a seating under the action of the pressure of fuel within a control chamber. A needle control valve controls communication between a source of fuel at high pressure and the control chamber, and also between the control chamber and a low pressure drain. The needle control valve includes a valve member including an end which is engageable with a surface extending in a plane normal to the axis of the valve member to close a port communicating with the low pressure drain.

Abstract: A method of efficient computation of gradients of a merit function of a system includes the steps of: specifying at least one parameter for which the gradients with respect to the at least one parameter are desired; specifying the merit function of interest in terms of observable measurements of the system; either solving or simulating the system to determine values of the measurements; expressing the gradients of the merit function as the gradient of a weighted sum of measurements; forming an appropriately configured adjoint system; and either solving or simulating the adjoint system to simultaneously determine the gradients of the merit function with respect to the at least one parameter by employing a single adjoint analysis.