The composition of exhaust gases from internal combustion engine is sensed, particularly the oxygen component thereof, and a sensed signal is derived, which is applied to a threshold detector, which triggers whenever the sensed signal passes a certain threshold value. The trigger signal controls and integrating controller to commence integrating, the integrating controller providing an output signal which is applied to set the air-fuel ratio such that the air number lambda is constantly controlled to be about 1. If integration by the integrating controller persists for a period of time in excess of a predetermined lapsed time, as determined by a pulse source controlled by speed of the engine, the integrating rate of the integrating controller is changed to provide for more rapid response when large changes have to be compensated.

Method and apparatus to reduce noxious components in the exhaust emissions of internal combustion engines

There is provided an air-fuel ratio control system for internal combustion engines wherein the direction of deviation of the actual air-fuel ratio from a preset air-fuel ratio is determined by an oxygen concentration detector for detecting the concentration of oxygen contained in the exhaust gases from an internal combustion engine and an air-fuel ratio discriminating circuit, whereby air is injected from an air injection valve when the air-fuel ratio is low i.e. the mixture is rich and fuel is injected from a fuel injection valve when the air-fuel ratio is high i.e. the mixture is lean, thereby controlling the air-fuel ratio to a predetermined value.

Air-fuel ratio control system for internal combustion engines

There is provided an air-fuel mixture ratio correcting system for a carburetor in which the air-fuel ratio of a mixture fed to an engine is detected whereby to control the amount of auxiliary fuel and/or the amount of auxiliary air to always control the air-fuel ratio of the mixtures at the correct value.

Air-fuel mixture ratio correcting system for carburetor

In an air-to-fuel ratio adjusting system for an internal combustion engine which comprises an additional air supply passage communicating with the carburetor of an internal combustion engine at the position downstream of its throttle valve, a control valve disposed in the additional air supply passage to vary the passage area thereof, and a percolation sensor for detecting percolation phenomenon of the fuel during idling operation of the engine is provided. When the occurrence of a percolation phenomenon is determined in accordance with the output signal of the percolation sensor, the control valve is controlled in response to the output signal of an air-to-fuel ratio sensor, whereas the control valve is held in a predetermined valve position when there is no occurrence of percolation phenomenon during idling operation of the engine.

Air-to-fuel ratio adjusting system for an internal combustion engine

The exhaust gas composition is sensed by a sensor which provides an electrical output signal which is appliied to an integral controller which controls the mixing device (fuel injection system or carburetor) which mixes air and fuel to provide the air-fuel mixture for the engine, in proper proportion for minimum noxious exhaust emission. In accordance with the invention, the integral controller integrates at a rate which is controlled by the speed of the engine. A speed-dependent pulse signal is derived, applied to a monostable multivibrator (MMV) which samples the signal applied to the integral controller, so that the integral controller will integrate only when it receives the sample signal, and hold the then obtained integrated signal until the next sampled signal is applied thereto.

Exhaust gas composition control system for internal combustion engines, and control method

Air and fuel are applied to the inlet manifold of an internal combustion engine over a first path, the amount of air being controlled in accordance with a command input, for example to control operation of the engine. The oxygen content in the exhaust gases is measured and additional air is applied to the inlet manifold of the engine over a second path, the amount of additional air being supplied over the second path being controlled in accordance with (a) the amount of air admitted through the first path and, additionally, (b) in accordance with the measured oxygen content of the exhaust gases.

P Schmidt

Papers

Method and apparatus to remove polluting components from the exhaust gases of internal combustion engines