Abstract: A control system (10) controls fuel injected into an internal combustion engine (14) having a fuel vapor recovery system (74) coupled to the air/fuel intake. To achieve stoichiometric combustion, delivery of liquid fuel is trimmed by a feedback variable (32) responsive to an exhaust gas oxygen sensor (26) and a learned value (40) representing quantity of recovered fuel vapor. Learning (40) is inhibited when an indication is provided of air/fuel operation rich of stoichiometry which is caused by factors other than vapor recovery.

Abstract: The invention is directed to a method of shifting the lambda value to that value at which a control in time average is effected with a two-point lambda control for an internal combustion engine.

Abstract: An air/fuel ratio feedback control system for an internal combustion engine sets an air/fuel ratio feedback correction coefficient on the basis of an air/fuel ratio for an air/fuel mixture introduced into a combustion chamber of the engine, to cause the air/fuel ratio to approach a set point thereof. The correction coefficient consists of a rich control proportional component P.sub.R, a lean control proportional component P.sub.L and an integral component I. When the air/fuel ratio set by the feedback control system deviates from an initial set point (the stoichiometric value) due to deterioration of an oxygen sensor for detecting the air/fuel ratio, the feedback control system compensates for the deviation to cause the air/fuel ratio to approach the initial set point, by varying a ratio of the rich control proportional component P.sub.R to the lean control proportional component P.sub.

Abstract: A control system (10) controls the induction of fuel injected into an internal combustion engine (14) to achieve stoichiometric combustion. The control system includes a feedback controller (32) which generates a feedback variable by integrating the output of an exhaust gas oxygen sensor (26). Integration is inhibited in response to an indication of a rich air/fuel offset.

Abstract: A method for controlling the air-fuel ratio in an internal combustion engine equipped to operate from a gaseous alternative fuel. The output signal of the engine's exhaust gas oxygen sensor is used to measure the variable engine transport delay. The variable is used to approximate a reciprocal of the delay. The reciprocal is used as a representation of the variable engine mass air-flow. A limit cycle operating in a transport-delay-oscillator mode is modified by extending the duration of the enrichment phase in proportion to the mass air-flow. The resulting exhaust gas concentrations are biased rich and thus shifted within an optimum operating window of the engine's gasoline catalytic converter. A significant reduction of unwanted exhaust emissions is observed.

Abstract: The arrangement according to the invention permits the optimal control of the air/fuel ratio of an air/fuel mixture supplied to an internal combustion engine while considering the gas storage capability of a catalyzer. The degree of conversion of the catalyzer is dependent upon the oxygen content of the exhaust gas which is available. Since this degree of conversion is partially influenced by the oxygen given off by the catalyzer, a targeted enrichment or leaning of the air/fuel ratio can optimize the degree of conversion of the catalyzer.

Abstract: A fuel blending ratio detecting method is provided which includes a feedback computing compensation coefficient K.sub.FB on the basis of an air/fuel ratio responsive output V.sub.o of an O.sub.2 sensor, computing a feedback learned value K.sub.LRN on the basis of the feedback compensation coefficient K.sub.FB at intervals of a predetermined period, and multiplying the current blending ratio compensation coefficient K.sub.B by this feedback learned value K.sub.LRN to compute the next blending ratio compensation coefficient K.sub.B. Thus, the quantity of fuel supplied to the internal combustion engine can be always controlled accurately on the basis of the computed blending ratio compensation coefficient.

Abstract: A fuel blending ratio detecting method is provided wherein a feedback compensation coefficient K.sub.FB is computed on the basis of an air/fuel ratio responsive output V.sub.o of an O.sub.2 sensor, and a current blending ratio compensation coefficient K.sub.B is multiplied by a peak mean value K.sub.PEAK of the current and preceding peak values of the computed feedback compensation coefficient K.sub.FB to compute the next blending ratio compensation coefficient K.sub.B. Thus, the quantity of fuel supplied to the internal combustion engine can be always controlled accurately on the basis of the computed blending ratio compensation coefficient.

Abstract: Disclosed is an air-fuel ratio control apparatus in an internal combustion engine using different kinds of fuels, such as gasoline and an alcohol, interchangeably or together in a mixed state, wherein at the stationary driving, the integration constant for setting the air-fuel ratio feedback correction coefficient at the air-fuel feedback control is set according to the concentration of the basic fuel such as the alcohol, and at the transient driving, the integration constant is set at a value larger than the value set at the stationary driving. If this structure is adopted, the deflection of the air-fuel ratio at the stationary driving is kept constant irrespectively of the fuel concentration and high exhaust gas-purging performances can be maintained, and at the transient driving, a good response characteristic can be maintained to control excessive thickening or thinning of the air-fuel ratio, and good transient driving performances and high exhaust gas-purging performances can be maintained.

Abstract: The rich or lean status of an air/fuel control system is determined according to the difference between the time period that the normalized air/fuel ratio is greater than an upper limit and the time period that the normalized air/fuel ratio is less than a lower limit in equal number of successive rich and lean cycles when in closed-loop fuel operation. The degree of rich or lean of the system is proportional to the time period difference. An adaptive learning control correction factor is incremented or decremented by an adaptive amount proportional to the time period difference.

Abstract: A control system controls an operating parameter of an internal combustion engine. The control system includes an electrically operated actuator for acting on the operating parameter to be controlled and a control unit for adjusting the actuator so as to cause the operating parameter to assume a pregiven value. The control unit has an integral component for carrying out an integration and a proportional component for carrying out a proportional amplification operation. The rate of change of the operating parameter is controlled to a pregiven value when pregiven conditions are present by intervening in the integral operation and/or the proportional amplification operation carried out by the control unit.