US 4,361,124 AGranted

System for controlling air-fuel ratio

AssigneesFuji Jukogyo Kabushiki Kaisha, Nissan Motor Co., Ltd.

InventorHiroyuki Nakamura

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Abstract

An electronic control system for controlling the air-fuel ratio for an internal combustion engine comprising an on-off type electromagnetic valve for correcting the air-fuel ratio of the air-fuel mixture supplied by an air-fuel mixture supply device, a comparing circuit for comparing the output signal of a detector with a reference value, an integration circuit connected to the comparing circuit, a pulse generator, and a comparator for producing pulses for driving the on-off type electromagnetic valve from output signals of the integration circuit and of the pulse generator for controlling the air-fuel ratio to a value substantially equal to the stoichiometric air-fuel ratio. A first converter converts the operation of the throttle valve to an electric quantity output, a second converter converts the prevailing ambient atmospheric pressure to another electric quantity output. Further, there is provided switches actuated by the output signals of the first converter for rendering the integration circuit non-responsive to the output of the detector and responsive to the output of the second converter.

Claims14

Dependent claims

In a system for controlling the air-fuel ratio for an internal combustion engine having an induction passage, air-fuel mixture supply means, a throttle valve in the induction passage, an exhaust passage communicating with the engine, detecting means for detecting the concentration of a constituent of exhaust gases passing through said exhaust passage, an electronic control circuit operatively connected to an output of said detecting means and electromagnetic valve means actuated by an output signal from said electronic control circuit for correcting the air-fuel ratio of the air-fuel mixture supplied by said air-fuel mixture supply means dependent on said detecting means, the improvement comprising

first converting means for converting the a condition in the induction passage to an electric quantity first output signal,
second converting means for converting a presently existing ambient atmospheric pressure at an altitude of the engine to a corresponding electric quantity second output signal,
first means dependent on the first output signal of said first converting means for rendering said electronic control circuit non-responsive to an output from said detecting means,
second means dependent on the first output signal of said first converting means for feeding said second output signal of said second converting means to said electronic control circuit for controlling the air-fuel ratio to a proper value in dependency on the altitude of the engine.

1 more element

Dependencies are inferred from the claim text.