Air-fuel ratio control system
First Claim
1. An air-fuel ratio control system comprising:
- first means disposed upstream of a three-way catalyst for purifying the exhaust gas in an exhaust system of an internal combustion engine, said first means detecting an oxygen concentration and producing a first signal indicative of the detected oxygen concentration;
second means disposed downstream of said three-way catalyst, said second means detecting an oxygen concentration and producing a second signal indicative of the detected oxygen concentration;
comparator means for comparing said first signal with a reference level associated with a predetermined air-fuel ratio in order to produce a comparison-resultant lean signal and rich signal;
delay means for delaying at least one of the output signals of said comparator means;
adjusting means for adjusting the delay time of the signal delayed by said delay means, in accordance with said second signal of said second means; and
control means for controlling the air-fuel ratio of mixture supplied to said internal combustion engine, in accordance with the delayed signal produced from said delay means.
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Abstract
An air-fuel ratio control system comprises a comparator circuit for comparing a predetermined reference level with an output signal of a first oxygen sensor disposed upstream of a three-way catalyst for purifying the exhaust gas in the exhaust system of an internal combustion engine, the comparator circuit producing a signal indicative of whether the output signal of the first oxygen sensor is higher (lean) or lower (rich) than a predetermined air-fuel ratio, a delay circuit for delaying at least one of the output signals of the comparator circuit, and a delay time adjusting circuit for adjusting the delay time of the signal delayed by the delay circuit, in accordance with the value of the output signal of a second oxygen sensor disposed downstream of the three-way catalyst.
112 Citations
2 Claims
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1. An air-fuel ratio control system comprising:
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first means disposed upstream of a three-way catalyst for purifying the exhaust gas in an exhaust system of an internal combustion engine, said first means detecting an oxygen concentration and producing a first signal indicative of the detected oxygen concentration; second means disposed downstream of said three-way catalyst, said second means detecting an oxygen concentration and producing a second signal indicative of the detected oxygen concentration; comparator means for comparing said first signal with a reference level associated with a predetermined air-fuel ratio in order to produce a comparison-resultant lean signal and rich signal; delay means for delaying at least one of the output signals of said comparator means; adjusting means for adjusting the delay time of the signal delayed by said delay means, in accordance with said second signal of said second means; and control means for controlling the air-fuel ratio of mixture supplied to said internal combustion engine, in accordance with the delayed signal produced from said delay means. - View Dependent Claims (2)
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Specification