Emission control apparatus for internal engines with means for generating step function voltage compensating signals

Claim 1

A closed loop mixture control system for an internal combustion engine having a throttle valve and means for supplying a mixture of air and fuel thereto in a variable ratio in response to a control signal representative of the deviation of the air-fuel ratio within the exhaust system of the engine, wherein the system includes means for modifying the amplitude of the control signal to control the air-fuel ratio to a desired value, comprising: means for sensing the rate of movement of said throttle valve and providing a first output signal corresponding thereto; means for detecting the presence of acceleration and deceleration of said engine utilizing said first output signal and providing a second output signal wherever said rate of movement of said throttle valve exceeds a predetermined threshold level; means for generating a signal representing a time integral of said modified control signal; a source for providing a first and a second DC voltage; means for combining said time integral representing signal with said first DC voltage to generate a first voltage signal and for combining said time integral representing signal with said second DC voltage to generate a second voltage signal; and means for applying said first and second voltage signals to said air-fuel supply means in response to the detection of said acceleration or deceleration whereby a rich air-fuel mixture is supplied to said engine under acceleration and a lean air-fuel mixture is supplied to said engine under deceleration.