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U.S. Department of Energy
Office of Scientific and Technical Information

System for controlling air-fuel ratio

Patent ·
OSTI ID:6465147

A system for controlling the air-fuel ratio for a carburetor for an internal combustion engine having an intake passage, an exhaust passage, a throttle valve, a detector such as an oxygen sensor for detecting the concentration of oxygen in the exhaust gases, an air-fuel mixture supply device, an on-off electromagnetic valve for correcting the air-fuel ratio of the air-fuel mixture supplied by the air-fuel mixture supply device and an electric controller. A throttle sensor produces an output dependent on the operation of the throttle valve. The electric controller is so arranged as to decrease variation of controlled air-fuel ratio. The electric controller comprises a comparator for comparing the output signal of the detector with a set value, an integration circuit connected to the comparator, a middle value detecting circuit for detecting a middle value between peak values of the output of the integration circuit, a triangular wave pulse generator, and a comparing circuit for comparing the output of the middle value detecting circuit with the triangular wave pulse for producing square wave pulses for driving the onoff electromagnetic valve for controlling the air-fuel ratio to a value approximately equal to the stoichiometric air-fuel ratio. A correcting device compensates for the delay of the output of the middle value detecting circuit.

Assignee:
Fuji Jukogyo K K (Japan); Nissan Motor Co Ltd (Japan)
Patent Number(s):
US 4356797
OSTI ID:
6465147
Country of Publication:
United States
Language:
English