Emission control system for an internal combustion engine
First Claim
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1. A system for controlling the air/fuel mixture input to an internal combustion engine which comprises:
- a sensor mounted to the engine for sensing the level of an exhaust gas and producing an analog signal indicative of that level;
means for producing a reference level signal indicative of the desired level of said exhaust gas;
a comparator connected to receive the analog exhaust gas signal and the reference level signal and being operable to produce a first logic level output if the analog exhaust gas signal exceeds the reference level signal and produce a second logic level output if the analog exhaust gas signal is less than the reference level signal;
a clock for producing clock pulses;
a flip-flop connected to the comparator and the clock and being operable to store the state of the comparator output each time a clock pulse is received and to produce a corresponding direction signal at an output;
a stepper motor mounted to the engine for controlling the air/fuel mixture; and
a stepper motor control connected to the clock and the flip-flop and being operable to advance the stepper motor one step for each received clock pulse in the direction indicated by the state of the flip-flop.
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Abstract
A system for controlling the air/fuel ratio input to a small engine measures the oxygen level in the engine'"'"'s exhaust and compares it with a reference level. A stepper motor controls the air/fuel ratio and it is advanced one step each time a clock pulse is produced in a direction determined by the level of exhaust oxygen. A fault detector circuit stops the engine if the sensed oxygen level is outside a preset range for more than a preset time interval.
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Citations
8 Claims
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1. A system for controlling the air/fuel mixture input to an internal combustion engine which comprises:
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a sensor mounted to the engine for sensing the level of an exhaust gas and producing an analog signal indicative of that level; means for producing a reference level signal indicative of the desired level of said exhaust gas; a comparator connected to receive the analog exhaust gas signal and the reference level signal and being operable to produce a first logic level output if the analog exhaust gas signal exceeds the reference level signal and produce a second logic level output if the analog exhaust gas signal is less than the reference level signal; a clock for producing clock pulses; a flip-flop connected to the comparator and the clock and being operable to store the state of the comparator output each time a clock pulse is received and to produce a corresponding direction signal at an output; a stepper motor mounted to the engine for controlling the air/fuel mixture; and a stepper motor control connected to the clock and the flip-flop and being operable to advance the stepper motor one step for each received clock pulse in the direction indicated by the state of the flip-flop. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification