Fuel demand engine control system

An electrical system for controlling the air-fuel mixture in an internal combustion engine system having an intake system, at least one cylinder, a throttle valve disposed within said intake system for regulating the flow of air to said cylinder, means for metering a quantity of fuel into said cylinder, and manually operable accelerator means for positively controlling said fuel metering means, said electrical system comprising:

• means responsive to one of said accelerator means and said fuel metering means for generating a first signal indicative of the quantity of fuel to be metered into said cylinder;
• throttle valve positioning means responsive to a control signal for regulating the position of said throttle valve to selectively vary the flow of air into said cylinder;
• means responsive to one of said throttle valve and said throttle valve positioning means for generating a second signal indicative of the actual air flow into said cylinder;
• electronic control unit means responsive to at least said first and second signals for generating a base control signal commanding a predetermined desired air flow as a function of metered fuel and the like for controlling said throttle valve positioning means;
• gas sensing means disposed in said engine for generating a feedback signal indicative of the actual air-fuel mixture existing therein;
• loop-closing means responsive to said feed-back signal for correcting said base control signal such that said throttle valve positioning means is responsive to said corrected control signal for more accurately maintaining a desired air-fuel ratio in said internal combustion engine;
• and
• means responsive to said first signal for anticipating an undesirable condition of excessive enrichment and for generating a transient correction signal indicative thereof even before said gas sensing means detects the actual existence of same for immediately correcting said base control signal and temporarily increasing the air flow into said cylinder for minimizing said undesirable condition.

An electrical system for controlling the air-fuel mixture in an internal combustion engine system having an intake system, at least one cylinder, a throttle valve disposed within said intake system for regulating the flow of air into said cylinder, means for metering a quantity of fuel into said cylinder, and manually operable accelerator means for positively controlling said fuel metering means, said electrical system comprising:

• means responsive to one of said accelerator means in said fuel metering means for generating a first signal indicative of the quantity of fuel to be metered into said cylinder;
• throttle valve positioning means responsive to a control signal for regulating the position of said throttle valve to selectively vary the flow of air into said cylinder;
• means responsive to one of said throttle valve and said throttle valve positioning means for generating a second signal indicative of the actual air flow into said cylinder;
• electronic control unit means responsive to at least said first and second signals for generating a base control signal commanding a predetermined desired air flow as a function of metered fuel and the like for controlling said throttle valve positioning means;
• means for sensing engine roughness which is indicative of the actual existence of an improper air-fuel mixture within said engine and for generating a feed-back signal indicative thereof;
• loop-closing means responsive to said feed-back signal for correcting said basic control signal such that said throttle valve positioning means is responsive to said corrected control signal for more accurately maintaining a desired air-fuel ratio in said internal combustion engine system;
• and
• means responsive to said first signal for anticipating an undesirable condition of excessive enrichment and for generating a transient correction signal indicative thereof even before said engine roughness sensing means detects the actual existence of other than the desired air-fuel mixture within said engine for immediately correcting said base control signal and temporarily increasing the air flow into said cylinder for minimizing said undesirable condition.

A closed loop method of maintaining a desired air-fuel ratio in an internal combustion engine comprising the steps of:

• supplying a quantity of fuel to said engine under operator command;
• measuring a first parameter indicative of the actual air flow into said engine;
• controlling the air flow into said engine as a function of said quantity of fuel supplied to said engine under operator command and said first measured parameter indicative of actual air flow into said engine;
• measuring another engine operating parameter indicative of the actual air-fuel mixture existing in said engine;
• and
• selectively increasing and decreasing said controlled air flow in response to said measured engine operating parameter indicative of the actual air-fuel mixture existing in said engine in a closed loop manner so as to maintain a desired optimal air-fuel ratio under substantially all engine operating conditions.

In a system for controlling the air-fuel mixture in an internal combustion engine having at least one engine cylinder, a closed loop method of maintaining a desired optimal air-fuel ratio under various operating conditions comprising the steps of:

• feeding an operator-commanded quantity of fuel into said cylinder;
• generating a first signal indicative of the quantity of fuel fed into said cylinder;
• generating a second signal indicative of the actual air flow into said cylinder;
• computing a basic control signal indicative of the desired air flow as a function of said first and second signals;
• sensing the oxygen present in the air-fuel mixture actually existing in said engine;
• generating a third signal indicative of the actual air-fuel mixture as a function of the quantity of sensed oxygen present therein;
• adjusting said basic control signal in a closed loop manner to increase and decrease computed air flow to more precisely maintain said desired air-fuel ratio;
• monitoring the rate of change of said quantity of fuel commanded to be fed into said cylinder to anticipate an impending undesirable condition of excessive fuel enrichment;
• and
• generating a transient signal for adjusting said basic control signal even before said oxygen-sensing step is able to detect the actual existence of said undesirable condition to temporarily increase the air flow into said cylinder so as to minimize said undesirable condition of excessive enrichment.

In a system for controlling the air-fuel mixture in an internal combustion engine having at least one engine cylinder, a closed loop method of maintaining a desired optimal air-fuel ratio under various operating conditions comprising the steps of:

• feeding an operator-commanded quantity of fuel into said cylinder;
• generating a first signal indicative of the quantity of fuel fed into said cylinder;
• generating a second signal indicative of the actual air flow into said cylinder;
• computing a basic control signal indicative of desired air flow as a function of said first and second signals;
• monitoring engine roughness as a measure of undesirably high and undesirably low actual air-fuel mixtures existing within said engine;
• generating a third signal from said monitored engine roughness, said third signal being indicative of the magnitude of said undesirably high or low air fuel mixture actually existing within said engine;
• adjusting said basic control signal in a closed loop manner to increase and decrease computed air flow to more precisely maintain said desired air-fuel ratio;
• monitoring the rate of change of said quantity of fuel commanded to be fed into said cylinder to anticipate an impending undesirable condition of excessive fuel enrichment;
• and
• generating a transient signal for adjusting said basic control signal even before said engine roughness monitoring means is able to detect said undesirably high or low air-fuel mixture within said engine to temporarily increase the air flow into said cylinder in order to minimize said undesirable condition of excessive enrichment.