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A system for controlling fuel flow in an internal combustion engine receives a command specifying a desired fuel flow rate from an electronic control module. The system generates a feedforward estimate of actuator current required to produce the desired flow rate. This estimate is combined with a fu

A system for controlling fuel flow in an internal combustion engine receives a command specifying a desired fuel flow rate from an electronic control module. The system generates a feedforward estimate of actuator current required to produce the desired flow rate. This estimate is combined with a fueling current offset value generated using a proportional-integral feedback controller. A differential pressure between the fuel rail and cylinder gas is converted, by surface interpolation based on a lookup table, to an estimate of actual fuel flow rate. The difference between this actual fuel flow rate and the desired flow rate is provided to the feedback controller as an error signal. The feedback controller preferably uses different gain values depending on an operating mode of the engine (speed control and torque control modes).

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[ We claim:] [1.] A fuel control system for an internal combustion engine for delivering fuel to a fuel rail for distribution to a plurality of fuel injectors, comprising:computing means for receiving a plurality of operating condition signals indicative of an operating state of the internal combust

[ We claim:] [1.] A fuel control system for an internal combustion engine for delivering fuel to a fuel rail for distribution to a plurality of fuel injectors, comprising:computing means for receiving a plurality of operating condition signals indicative of an operating state of the internal combustion engine and for generating a desired fuel quantity signal representing a desired quantity of fuel to be delivered to one of the fuel injectors based on said operating condition signals;first conversion means connected with said computing means for converting said desired fuel quantity signal into an estimated actuator current signal;adjusting means connected with said first conversion means and an output of a proportional integral controller means for combining an offset current signal received from said proportional integral controller means with said estimated actuator current signal to produce an actuator current control signal;actuator means connected with said adjusting means for receiving said actuator current control signal and for controlling the amount of fuel delivered to the fuel rail based on said actuator current control signal;pressure sensing means connected with the fuel rail for sensing a fuel pressure in the fuel rail and for generating a fuel rail pressure signal corresponding to said fuel pressure;second conversion means connected with said pressure sensing means for receiving said fuel rail pressure signal and for converting said fuel rail pressure signal into an estimated fuel quantity signal representing an estimated actual fuel delivery rate to one of the injectors; andcomparison means connected with said second conversion means, said computing means and said proportional integral controller means for generating a fuel quantity error signal corresponding to a difference between said estimated fuel quantity signal and said desired fuel quantity signal and for providing said fuel quantity error signal to said proportional integral controller means;wherein said proportional integral controller means generates an offset current signal based on said fuel quantity error signal.