Fuel metering control system for internal combustion engine

A computer program controlled system for controlling fuel metering for a multi-cylinder internal combustion engine, comprising:

• an air/fuel ratio sensor located in an exhaust system of the engine for detecting an air/fuel ratio in exhaust gas of the engine;
• engine operating condition detecting means for detecting engine operating conditions including at least engine speed and engine load;
• basic fuel injection quantity determining means coupled to said engine operating condition detecting means, for determining a basic quantity of fuel injection for a cylinder of the engine based on at least the detected engine operating conditions;
• a feedback loop means coupled to said basic fuel injection quantity determining means, and having an adaptive controller and an adaptation mechanism coupled to said adaptive controller for estimating controller parameters, said adaptive controller calculating a feedback correction coefficient using internal variables that include at least said controller parameters, to correct the basic quantity of fuel injection to bring a controlled variable obtained based at least on the detected air/fuel ratio to a desired value;
• feedback control region discriminating means for discriminating whether engine operation is in a feedback control region based on the detected engine operating conditions;
• output fuel injection quantity determining means for determining an output quantity of fuel injection, said output fuel injection quantity determining means correcting the basic quantity of fuel injection using said feedback correction coefficient when the engine operation is discriminated to be in the feedback control region;
• and
• fuel injection means coupled to said output fuel injection quantity determining means, for injecting fuel into the cylinder of the engine based on the output quantity of fuel injection;
• wherein:
• said feedback loop means determines the internal variables of the adaptive controller in response to the detected engine operating conditions, when the engine operation has shifted from an open-loop control region to the feedback control region.

A method for controlling fuel metering for a multi-cylinder internal combustion engine, comprising the steps of:

• detecting an air/fuel ratio in exhaust gas of the engine;
• detecting engine operating conditions including at least engine speed and engine load;
• determining a basic quantity of fuel injection for a cylinder of the engine based on at least the detected engine operating conditions;
• feedback controlling with an adaptive controller and an adaptation mechanism coupled to said adaptive controller for estimating controller parameters, said adaptive controller calculating a feedback correction coefficient using internal variables that include at least said controller parameters, to correct the basic quantity of fuel injection to bring a controlled variable obtained based at least on the detected air/fuel ratio to a desired value;
• discriminating whether engine operation is in a feedback control region based on the detected engine operating conditions;
• determining an output quantity of fuel injection, while correcting the basic quantity of fuel injection using said feedback correction coefficient when the engine operation is discriminated to be in the feedback control region;
• and
• injecting fuel into the cylinder of the engine based on the output quantity of fuel injection;
• and
• determining the internal variables of the adaptive controller in response to the detected engine operating conditions, when the engine operation has shifted from an open-loop control region to the feedback control region.

A computer program embodied on a computer-readable medium for controlling fuel metering for a multi-cylinder internal combustion engine, said computer program comprising the steps of:

• detecting an air/fuel ratio in exhaust gas of the engine;
• detecting engine operating conditions including at least engine speed and engine load;
• determining a basic quantity of fuel injection for a cylinder of the engine based on at least the detected engine operating conditions;
• feedback controlling with an adaptive controller and an adaption mechanism coupled to said adaptive controller for estimating controller parameters, said adaptive controller calculating a feedback correction coefficient using internal variables that include at least said controller parameters, to correct the basic quantity of fuel injection to bring a controlled variable obtained based at least on the detected air/fuel ratio to a desired value;
• discriminating whether engine operation is in a feedback control region based on the detected engine operating conditions;
• determining an output quantity of fuel injection, while correcting the basic quantity of fuel injection using said feedback correction coefficient when the engine operation is discriminated to be in the feedback control region;
• and
• injecting fuel into the cylinder of the engine based on the output quantity of fuel injection;
• and
• determining the internal variables of the adaptive controller in response to the detected engine operating conditions, when the engine operation has shifted from an open-loop control region to the feedback control region.

A system for controlling fuel metering for a multicylinder internal combustion engine, comprising:

• an air/fuel ratio sensor located in an exhaust system of the engine for detecting an air/fuel ratio in exhaust gas of the engine;
• engine operating condition detecting means for detecting engine operating conditions including at least engine speed and engine load;
• control means, coupled to said air/fuel ratio sensor and said engine operating condition detecting means, for controlling an amount of fuel to be injected, said control means including
• a) basic fuel injection quantity determining means for determining a basic quantity of fuel injection for a cylinder of the engine based on at least the detected engine operating conditions,
• b) a feedback loop means coupled to said basic fuel injection quantity determining means, and having an adaptive controller and an adaptation mechanism coupled to said adaptive controller for estimating controller parameters, said adaptive controller calculating a feedback correction coefficient using internal variables that include at least said controller parameters, to correct the basic quantity of fuel injection to bring a controlled variable obtained based at least on the detected air/fuel ratio to a desired value,
• c) feedback control region discriminating means for discriminating whether engine operation is in a feedback control region based on the detected engine operating conditions,
• d) output fuel injection quantity determining means for determining an output quantity of fuel injection, said output fuel injection quantity determining means correcting the basic quantity of fuel injection using said feedback correction coefficient when the engine operation is discriminated to be in the feedback control region;
• and
• fuel injection means coupled to said control means, for injecting fuel into the cylinder of the engine based on the output quantity of fuel injection;
• and
• said feedback loop means determines the internal variables of the adaptive controller in response to the detected engine operating conditions, when the engine operation has shifted from an open-loop control region to the feedback control region.