A control system for an engine system which has means for optimizing the performance of the converter in the engine system by regulating a set point of a controller. In one embodiment, secondary air flow to the converter is the variable utilized to control the performance of the converter and is regulated in response to the ratio of gas flow in respect to the engine of the system to secondary gas flow to the converter. In another embodiment the air to fuel ratio to the engine is utilized as a variable to control the performance of the converter.
An internal combustion engine is equipped with a lambda regulating device, a catalytic converter disposed in an exhaust pipe of the internal combustion engine, a device for externally heating the catalytic converter to its operating temperature, and a secondary-air pump which injects additional air into the exhaust pipe. A method for controlling the fuel supply for the internal combustion engine includes injecting an additional fuel quantity during operation of a burner and during secondary-air injection, for heating the catalytic converter, as a function of engine air mass flow and an additional secondary-air quantity which is injected into the exhaust system.
Disclosed is a double feedback loop type of secondary air control system for an internal combustion engine, in which a valve provided in a secondary air feed passage for regulating a quantity of the secondary air fed into an exhaust passage of the engine is operated in response to a first error signal indicative of a deviation of the actual secondary air quantity from the desired secondary air quantity and a second error signal indicative of a deviation of the actual air-fuel ratio from the desired air-fuel ratio, thereby effecting a precise control of the air-fuel ratio.
Secondary air fed to the exhaust system of an engine is controlled by controllably venting the secondary air passing through a secondary air supply conduit leading to the exhaust system using a diaphragm unit operated valve. Vacuum applied to the diaphragm unit is controlled by cooperation of the venturi vacuum and the pressure differential between two interior portions of the secondary air supply conduit to supply the exhaust system with an appropriate amount of secondary air to the exhaust gas amount.
A method is disclosed for controlling operation of an engine coupled to an exhaust treatment catalyst. Under predetermined conditions, the method operates an engine with a first group of cylinders combusting a lean air/fuel mixture and a second group of cylinders pumping air only (i.e., without fuel injection). In addition, the engine control method also provides the following features in combination with the above-described split air/lean mode: idle speed control, sensor diagnostics, air/fuel ratio control, adaptive learning, fuel vapor purging, catalyst temperature estimation, default operation, and exhaust gas and emission control device temperature control. In addition, the engine control method also changes to combusting in all cylinders under preselected operating conditions such as fuel vapor purging, manifold vacuum control, and purging of stored oxidants in an emission control device.
A sensor such as an oxygen sensor or a carbon monoxide sensor generates an electrical signal responsive to the oxygen or carbon monoxide concentration in exhaust gases discharged from an exhaust purifying device. Under the control of the electrical signal regulating means the amount of secondary air to the exhaust purifying devices is regulated.
