Closed-loop mixture control for an internal combustion engine of a roadway vehicle with means for compensating for fuel deficiency during vehicle start-up periods

Claim 2

A closed-loop mixture control system for an internal combustion engine of a roadway vehicle, said engine including means for supplying air and fuel in a controlled ratio thereto, said system comprising: means for generating a first signal representing the concentration of an exhaust composition of the emissions from said engine; means for comparing the first signal with a reference value to generate a second signal indicating the deviation of the air-fuel ration in said emissions from said reference value; a vehicle start detector for generating an output only at the instant when the vehicle is being started from a rest, idle condition; means for generating a compensating signal in response to the output from said vehicle start detector; control amplifier means responsive to the second signal for generating a control signal which adjusts said air-fuel supply means in the direction of the deviation of said air-fuel ratio in said emissions from said reference value; a summation circuit providing summation of the control signal and the compensating signal so that the air-fuel supply means is adjusted to supply an enriched mixture to said engine when the vehicle is started from a rest, idle condition; said vehicle start detector including means for generating a step change DC signal in response to the detection of said vehicle being started from a rest, idle condition, and said compensating signal generating means comprising a differentiator for differentiating the leading edge of the step change DC signal for enriching said air-fuel ratio supplied by said air-fuel supply means.

Claim 3

In combination, apparatus for controlling the air-fuel ratio of a mixture supplied to an internal combustion engine of a roadway vehicle; means for deriving a first signal indicative of the concentration of an exhaust composition of the emission from said engine; a feedback loop responsive to the first signal for deriving a control signal that is supplied to the control apparatus so that during normal, running operation of the vehicle there is a tendency to maintain a predetermined air-fuel ratio of the emissions, said feedback loop having a tendency to oscillate so that there is a tendency for the first signal to cause less fuel to be supplied to the engine than is needed as the vehicle goes from an idle to a normal, running condition, the feedback loop including: a proportional-integral controller responsive to the first signal and including operational amplifier means; means for overcoming the tendency for the first signal to cause less fuel to be supplied to the engine as the vehicle goes from an idle to a normal, running condition comprising: a vehicle start detector for generating an output only substantially simultaneously with the vehicle being started in motion from an engine idle condition; and means responsive to the output of the start detector for modifying the feedback loop to cause the control apparatus to suddenly supply an enriched air-fuel mixture to the engine substantially simultaneously with the derivation of the start detector output, the means for modifying including means for deriving a short duration pulse in response to the derivation of the start detector output, and the operational amplifier means including means for linearly combining the pulse with a signal derived in response to the first signal.

Claim 4

In combination, apparatus for controlling the air-fuel ratio of a mixture supplied to an internal combustion engine of a roadway vehicle; means for deriving a first signal indicative of the concentration of an exhaust composition of the emission from said engine; a feedback loop responsive to the first signal for deriving a control signal that is supplied to the control apparatus so that during normal, running operation of the vehicle there is a tendency to maintain a predetermined air-fuel ratio of the emissions, said feedback loop having a tendency to oscillate so that there is a tendency for the first signal to cause less fuel to be supplied to the engine than is needed as the vehicle goes from an idle to a normal, running condition, the feedback loop including: a proportional-integral controller responsive to the first signal and including operational amplifier means; means for overcoming the tendency for the first signal to cause less fuel to be supplied to the engine as the vehicle goes from an idle to a normal, running condition comprising: a vehicle start detector for generating an output only substantially simultaneously with the vehicle being started in motion from an engine idle condition; and means responsive to the output of the start detector for modifying the feedback loop to cause the control apparatus to suddenly supply an enriched air-fuel mixture to the engine substantially simultaneously with the derivation of the start detector output, the means for modifying including means for deriving a short duration pulse in response to the derivation of the start detector output, and the operational amplifier means including means for linearly combining the pulse with a signal derived in response to the first signal.