Apparatus and method for accurately controlling fuel injection flow rate
First 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; and
comparison 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.
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Accused Products
Abstract
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).
97 Citations
52 Claims
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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:
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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; and comparison 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.
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2. A method of controlling a quantity of fuel injected into a cylinder of an internal combustion engine during each injection event comprising the steps of:
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generating a desired fuel quantity signal indicative of a desired fuel quantity to be delivered to the cylinder of the internal combustion engine; generating an estimated actuator current signal from said desired fuel quantity signal, said estimated actuator current signal being indicative of an estimated actuator current necessary to deliver said desired fuel quantity to a cylinder of the internal combustion engine; generating a fuel rail pressure signal indicative of a measured fuel rail pressure; generating an actual fuel quantity signal from said fuel rail pressure signal, said actual fuel quantity signal being indicative of an actual fuel quantity delivered to a cylinder of the internal combustion engine; generating a fuel quantity difference signal representing a difference between said desired fuel quantity signal and said actual fuel quantity signal; generating an actuator current difference signal from said fuel quantity difference signal, said actuator current difference signal being indicative of a difference between said estimated actuator current and an actual actuator current necessary to achieve delivery of said desired fuel quantity to a cylinder of the internal combustion engine; combining said estimated actuator current signal and said actuator current difference signal to generate an actual actuator current signal indicative of said actual actuator current; and controlling an actuator in accordance with said actual actuator current signal. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A system for controlling a quantity of fuel injected from a fuel rail into a cylinder of an internal combustion engine during each injection event, wherein the fuel pressure in the fuel rail is varied using an actuator to control the desired quantity of fuel to be injected into the cylinder of the internal combustion engine, comprising:
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processing means for generating a desired fuel quantity signal indicative of a desired fuel quantity to be delivered to the cylinder of the internal combustion engine; fuel-to-current conversion means connected with said processing means for receiving said desired fuel quantity signal and generating an estimated actuator current signal from said desired fuel quantity signal, said estimated actuator current signal being indicative of an estimated actuator current necessary to deliver said desired fuel quantity to the cylinder of the internal combustion engine during the injection event; fuel rail pressure measuring means connected with the fuel rail of the internal combustion engine for measuring a sensed fuel rail pressure and for generating a fuel rail pressure signal in response thereto; pressure-to-fuel conversion means connected with said fuel rail pressure measuring means for receiving said fuel rail pressure signal and for generating an actual fuel quantity signal from said fuel rail pressure signal, said actual fuel quantity signal being indicative of an actual fuel quantity delivered to a cylinder of the internal combustion engine; first comparison means connected with said processing means and said pressure-to-fuel conversion means for receiving said desired fuel quantity signal and said actual fuel quantity signal, for calculating a difference between said desired fuel quantity signal and said actual fuel quantity signal, and for generating a fuel quantity difference signal representing said difference; controller means connected with said first comparison means for receiving said fuel quantity difference signal and for generating an actuator current difference signal from said fuel quantity difference signal, said actuator current difference signal being indicative of a difference between said estimated actuator current and an actual actuator current necessary to achieve delivery of said desired fuel quantity to a cylinder of the internal combustion engine; second comparison means connected with said controller means and said fuel-to-current conversion means for receiving said estimated actuator current signal and said actuator current difference signal, and for combining said estimated actuator current signal and said actuator current difference signal to generate an actual actuator current signal indicative of said actual actuator current; and current control means connected with said second comparison means for controlling the supply of current to the actuator in accordance with said actual actuator current signal. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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Specification