Abstract: An oxygen concentration detection apparatus includes a detection unit having a pair of oxygen-ion conductive solid electrolyte walls forming first and second gas retaining chambers on which first and second sets of electrodes, which are designed to operate alternatively, are provided. First and second current supply circuits are provided for alternatively supplying first and second pump currents respectively on the first and second sets of electrodes. Between the current supply circuits and the sets of electrodes respectively, a first variable resistor and a second variable resistor are provided so that adjustment operations are enabled separately for obtaining an accurate overall output signal characteristic of the oxygen concentration detection apparatus.

Abstract: A method of engine air/fuel ratio control whereby a compensation value is computed for compensating an error of a basic fuel injection time interval. The computation is periodically performed as an operating sequence including steps of computing a current first compensation value, utilizing a preceding first compensation value (obtained and memorized during a previous execution of the sequence, under the same engine operating conditions as those of the current first computation value), obtaining a second compensation value based on the deviation between a detected air/fuel ratio and a target air/fuel ratio, and compensating the basic value by the first and second compensation values to obtain an output value, used to control fuel supply to the engine. In addition, while engine acceleration or deceleration is occurring, the basic value is corrected by a transition compensation value, computed in accordance with the degree of acceleration or deceleration.

Abstract: A system of abnormality detection for an oxygen concentration sensor employed to sense the oxygen concentration in engine exhaust gas for obtaining data to control the air/fuel ratio of a fuel mixture supplied to the engine. In which, the oxygen concentration sensor includes a sensor cell element, an oxygen pump element each formed of a pair of electrodes which sandwich a solid electrolytic member, and a heater element for heating the solid electrolytic member. The system functions to detect an abnormality of the heater element on the basis of the value of a voltage developed between the electrodes of the sensor cell element and an air/fuel ratio compensation value that is derived by sensing the exhaust gas oxygen concentration.

Abstract: A system of abnormality detection for an oxygen concentration sensor employed to sense the oxygen concentration in engine exhaust gas, and to obtain data to control the air/fuel ratio of a fuel mixture supplied to the engine. The oxygen concentration sensor including a sensor cell element and an oxygen pump element. The system serves to detect an abnormality such as an open-circuit or a short-circuit in electrode connecting leads of the sensor cell element on the basis of a value of voltage developed between the electrodes of the sensor cell element and of a value of current which flows between the electrodes of the oxygen pump element.

Abstract: An air/fuel ratio control system for an internal combustion engine includes an oxygen concentration sensor for sensing the oxygen concentration in the exhaust gas of the engine, and a correction value setting device which determines a correction value corresponding to an output signal of the oxygen concentration sensor obtained when the fuel cut operation of the engine has continued for more than a predetermined time period. The output signal of the oxygen concentration sensor is corrected by the correction value during the engine operation other than the fuel cut operation.

Abstract: A method for controlling an oxygen concentration detection apparatus mounted on an engine, including an oxygen concentration sensing element and a heater element for heating the oxygen concentration sensing unit, includes an operation for detecting an engine temperature of a time immediately before the start of the supply of a drive current to the heater element, and an operation for controlling the magnitude of the drive current for a time period which is determined correspondingly to the engine temperature, to be lower than a level of the drive current to be supplied to the heater element after the elapse of the time period determined according to the engine temperature.

Abstract: A method for controlling an oxygen concentration sensor mounted on an engine, including oxygen ion conductive solid electrolyte members operative as an oxygen pump element and a sensor cell element respectively, a source of pump current to be supplied to the oxygen pump element, and a heater element for heating the oxygen pump element and the sensor cell element. The method includes an operation for detecting an engine temperature of a time immediately before the start of the supply of a drive current of the heater element, and a control operation for starting the supply of the pump current after an elapse of a time period determined in response to the engine temperature from the start of the supply of the drive current of the heater element.

Abstract: An oxygen sensor comprising an oxygen sensing unit sensitive to oxygen in an oxygen-containing gas and operative to produce an electric signal variable with the concentration of oxygen in the oxygen-containing gas when contacted by a stream of the gas, and a partitioned housing structure which has at least one first port open to the outside of the housing structure and which comprises partition means defining in the housing structure first and second chambers which are located across the partition means, the partition means being formed with at least one second port providing communication between the first and second chambers, the first chamber being open to the first port and the second chamber having enclosed the oxygen sensing unit therein.

Abstract: An oxygen sensor comprising an oxygen sensing unit sensitive to oxygen in an oxygen-containing gas and operative to produce an electric signal variable with the concentration of oxygen in the oxygen-containing gas when contacted by a stream of the gas, and a dual-shell housing structure comprising an outer shell and an inner shell enclosed within the outer shell and spaced apart inwardly from the outer shell to form a first chamber therebetween, the inner shell having defined therein a second chamber having the oxygen sensing unit fixedly held in position therewithin, the outer shell being formed with at least one port open to the first chamber and the inner shell being formed with at least one port open to the first and second chambers, the port in one of the outer and inner shells being out of alignment with the port in the other shell in a direction substantially perpendicular to the longitudinal measurement of the sensing unit and passing through a predetermined point of the sensing unit.

Abstract: An idling rpm feedback control method comprises controlling the quantity of supplementary air being supplied to an internal combustion engine equipped with at least one equipment which creates a load acting on the engine and includes at least one electrical device, in a feedback manner responsive to the difference between actual engine rpm and desired idling rpm during idling of the engine. The method also comprising varying the quantity of fuel being supplied to the engine in response to detected values of the total quantity of intake air inclusive of supplementary air at each predetermined rotational angle of the engine, so as to maintain the air-fuel ratio of a mixture being supplied to the engine at a desired value.

Abstract: A system adapted to control a control valve for controlling the quantity of supplementary air being supplied to an internal combustion engine, in a feedback manner responsive to a difference between actual engine rpm and desired engine rpm at engine idle. The above control valve is opened in synchronism with a signal indicative of a predetermined rotational position of the engine. The system is also adapted to detect a total quantity of suction air including the supplementary air being supplied to the engine, in synchronism with the above predetermined rotational position signal, to supply a quantity of fuel corresponding to the detected total suction air quantity.