Abstract: A fuel injection system is disclosed for an internal combustion engine that has multiple combustion chambers and a camshaft which cyclically imparts pressurization energy to and recovers pressurization energy from fuel being supplied to the engine. The fuel injection system includes a plurality of unit injectors, a camshaft linkage which simultaneously reciprocates pressurizing plungers of a set of at least two unit injectors and an interconnecting line which allows selective fluid interconnection between fuel pressurization chambers formed within the unit injectors. The interconnection line allows fluid linkage of the volume of fuel which is simultaneously pressurized and depressurized within the interconnected fuel pressurization chambers of a first set of unit injectors.

Abstract: A strategy for quantifying and compensating for between-engine variations in engine static timing, fuel pump phasing and overall system bandwidth includes a control circuit operable to manage a fuel control system including a high pressure, cyclically operable fuel pump and at least one fuel injector operable to supply fuel to an internal combustion engine from a fuel collection unit. In one embodiment, the strategy of the present invention is operable to determine peak values of the fuel pressure within fuel collection unit and corresponding engine position values for a number of different engine speeds and solve a corresponding model-based system of equations to determine a combined engine static timing and fuel pump phasing error as well as a first overall system bandwidth value.

Abstract: Manufacturing/design imperfections and component failures in the fuel system/engine can lead to non-uniform torque production among the cylinders. Non-uniform cylinder torques can be observed as small engine speed fluctuations about the average engine speed at any given operating point. Severe imbalance conditions can be heard, felt, and seen by human operators. The present invention uses the fluctuations in engine speed to detect an unbalanced engine and attempts to correct the unbalance by applying trims to the fueling commands for each individual cylinder. The present invention is based on the calculation of a 6-point Fourier Transform (FFT) of engine speed data over one complete engine cycle. This FFT is calculated continuously to provide imbalance detection. An unbalanced engine results in non-zero magnitudes of the FFT components that correspond to the 0.5, 1.0, and 1.5 engine orders.

Abstract: A closed-loop control system having two feedback paths 106, 108. A first feedback path contains an expected system output value generated by a system model 102. The second feedback path provides insensitivity to noise by heavily filtering the error between the model output 104 and the actual measured system output 74. Because of the delay associated with the filtering operation, the dual feedback paths result in an initial fast (but approximated) system response, followed by a delayed correction to that response.