Emission control system for internal combustion engines utilizing balance differential amplifier stage
First Claim
1. An emission control system for an internal combustion engine having an air-fuel mixing and proportioning device for delivery of proportioned air-fuel mixture to the cylinder of said engine in accordance with a low level noise and long term drift compensated error correction signal, comprising:
- an exhaust composition sensor for sensing the concentration of an exhaust composition of the emissions from said engine to generate a first signal representative of the sensed concentration;
means for generating said compensated error correction signal; and
means for controlling the air-fuel mixing and proportioning device in response to said compensated error correction signal;
said compensated error correction signal generating means comprising;
(a) means for generating a second signal substantially representative of a mean value of said first signal;
(b) means for generating a third signal representative of the difference in amplitude between said first and second signals;
(c) means for combining said third signal with a predetermined DC voltage having a level higher than noise so that said third signal fluctuates above and below said DC voltage; and
(d) means for modifying the amplitude of said combined signal in accordance with a predetermined control characteristic to generate said compensated error correction signal.
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Abstract
A closed-loop emission control system for an internal combustion engine having an exhaust composition sensor includes an averaging circuit for generating a signal representative of the average value of the sensed exhaust composition, and a balanced differential amplifier receptive of the average and instantaneous values of the sensed composition to generate an output indicating the difference therebetween. A DC bias is applied to the differential amplifier to fluctuate the difference signal above and below the DC bias level.
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Citations
7 Claims
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1. An emission control system for an internal combustion engine having an air-fuel mixing and proportioning device for delivery of proportioned air-fuel mixture to the cylinder of said engine in accordance with a low level noise and long term drift compensated error correction signal, comprising:
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an exhaust composition sensor for sensing the concentration of an exhaust composition of the emissions from said engine to generate a first signal representative of the sensed concentration; means for generating said compensated error correction signal; and means for controlling the air-fuel mixing and proportioning device in response to said compensated error correction signal; said compensated error correction signal generating means comprising; (a) means for generating a second signal substantially representative of a mean value of said first signal; (b) means for generating a third signal representative of the difference in amplitude between said first and second signals; (c) means for combining said third signal with a predetermined DC voltage having a level higher than noise so that said third signal fluctuates above and below said DC voltage; and (d) means for modifying the amplitude of said combined signal in accordance with a predetermined control characteristic to generate said compensated error correction signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification