Apparatus for controlling operating state of an internal combustion engine

An apparatus for controlling an operating state of an internal combustion engine, comprising:

• demand amount detecting means for detecting a demand amount, including detecting at least the manipulation amount of an accelerator, as an amount of demand for the operation of said internal combustion engine;
• operating condition varying means for varying variable of operating condition, which include at least fuel supply amount and throttle valve opening degree;
• operating state detecting means for detecting variables of operating state which include at least intake air quantity, rotational speed and output torque;
• target value setting means for determining respective target values for operating state variables which include at least target output torque and target intake air quantity, using said demand amount detected by said demand amount detecting means;
• control means for controlling said operating condition varying means by determining feedback amounts of said operating condition variables in order to cause variables of the detected operating state of said internal combustion engine to approach said determined target value;
• wherein said target value setting means determines said target intake air quantity as an intake air quantity with which said fuel supply amount becomes minimum on the basis of a correlation between intake air quantity and fuel supply amount when output torque is made constant;
• and
• wherein said control means is an integral-added optimal regulator which determines said feedback amount on the basis of an optimal feedback gain predetermined in accordance with a dynamic model of a system relating to the operation of said internal combustion engine, said integral-added optimal regulator of said control means having:
• (a) state evaluating means for estimating state variables of an appropriate order indicative of a dynamic internal state of the system based on operating state and operating condition of said internal combustion engine using parameters determined on the basis of the dynamic model of the system relating to the operation of said internal combustion engine;
• (b) accumulating means for accmulating respective differences between the target values of the operating state variables determined by said target value setting means and said detected operating state variables, for at least output torque and intake air quantity;
• and
• (c) feedback amount determining means for determining respective controlled variables of operating condition including at least fuel supply amount and throttle opening degree which are controlled by said operating condition varying means using said optimal feedback gain determined on the basis of the dynamic model of said system, said estimated state variables, and said accumulated value.