Abstract: An oxygen concentration sensor having an oxygen ion conductive solid electrolyte member forming a gas diffusion restricted region into which a measuring gas is introduced, includes a pump current source for supplying a pump current across a pair of electrodes sandwiching the solid electrolyte through a current detection element and a heater for heating the solid electrolyte. By an arrangement in which the current detection element is connected to one of the pair of electrodes facing the gas diffusion restricted region, error of measurement due to leakage of a drive current of the heater is prevented.

Abstract: Abnormalities are detected in 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 and an oxygen pump element. The method functions to detect an abnormality of the oxygen concentration sensor on the basis of the value of sensor voltage which is developed by the sensor cell element and at least one of a set of parameters consisting of an engine operating condition, the value of pump current which flows between the electrodes of the oxygen pump element, and an air/fuel ratio compensation value which is derived from a sensed oxygen concentration level.

Abstract: An oxygen concentration detection device having a pair of oxygen pump units includes an oxygen-ion conductive solid electrolyte member a surface of which faces a gas retaining chamber. A measuring gas is introduced through a gas restricted region into the gas retaining chamber. The solid electrolyte member is provided with two pairs of electrodes respectively supplied with a pair of pump currents generated by a current supply circuit. The magnitude of the pump current flowing between the electrodes of one of two pairs of electrodes is controlled so that the voltage difference across the electrodes of the other one of the two pairs of electrodes is maintained at a level corresponding to a reference level. The oxygen concentration in the gas retaining chamber is detected in terms of a sum value of pump currents flowing through the two pairs of electrodes.

Abstract: A method of air/fuel ratio control for a multicylinder internal combustion engine, utilziing an oxygen concentration sensor which produces an output varying in proportion to oxygen concentration, in which compensation values are computed and stored for use in compensating errors of a basic value which controls the air/fuel ratio. While the engine is operating in a condition condition in which the deviation of a detected air/fuel ratio from a target air/fuel ratio is below a predetermined level, respective compensation values are computed and updated for the individual cylinders of the engine, with these compensation values being computed in accordance with variations in the magnitude of the detected air/fuel ratio.

Abstract: Compensation of an output from an oxygen concentration sensor of an air/fuel ratio control apparatus for an internal combustion engine is executed during engine warm-up, to correct for an erroneous component in the oxygen concentration sensor output data caused by incomplete combustion during warm-up. The degree of compensation applied is determined by the engine operating temperature, as represented by the cooling water temperature. Excessive richness of the air/fuel ratio of the mixture supplied to the engine during warm-up is thereby eliminated.

Abstract: A method for controlling an air/fuel ratio of an internal combustion engine. The fuel supply is performed normally by a feedback control operation for controlling the air/fuel ratio of the mixture toward a target air/fuel ratio in accordance with an oxygen concentration in an exhaust gas of the engine. A fuel cut operation under a predetermined condition includes a step for detecting a transition from the fuel cut operation to resume the fuel supply, and a step for shifting, for a time period after a detection of the transition, the target air/fuel ratio of the feedback control to a lean side with respect to a target air/fuel ratio value to be used after the elapse of the time period.

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: An air/fuel ratio sensor having two units of probe is disclosed each of which comprises two sensing elements, each having a pair of porous electrodes on oppostie sides of an oxygen ion-conductive solid electrolyte; a gas compartment which is formed in contact with one porous electrode for each sensing element and which communicates with the gaseous atmosphere of interest by way of a gas diffusion limiting portion; and an internal reference oxygen source which is formed in contact with one sensing element on the porous electrode side which is opposite the side where said gas compartment is provided. The oxygen source communicates with the outside by way of a leakage resisting portion. The gas compartment in the first unit of probe communicates directly with the gaseous atmosphere of interest by way of a first gas diffusion limiting portion while the gas compartment in the second unit of probe communicates with the gas in the first unit of probe by way of a second gas diffusion limiting portion.

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: A method of controlling the duty ratio of operation of a solenoid control valve in a fluid passage to control the flow rate of fluid in the fluid passage to a desired value. A flow rate value range is divided into a plurality of flow rate value regions between first and second extreme flow rate values which the fluid can assume when the duty ratio assumes corresponding minimum and maximum values. A first predetermined duty ratio value is preset corresponding to each of the divided regions and dependent upon the magnitude of manufacturing variations of the duty ratio-to-flow characteristic of the valve. A second larger predetermined duty ratio value is preset corresponding to each of the divided regions.

Abstract: A method of electronically controlling an operating amount of a control means for controlling operation of an internal combustion engine, such as a fuel injection control means. When the engine is operating in a predetermined low load condition, a desired operating amount of the control means is determined in dependence on the detected value of a first engine operating parameter indicative of loaded conditions of the engine, whereas when the engine is not operating in the predetermined low load condition, the desired operating amount of the control means is determined in dependence on the detected value of a second engine operating parameter indicative of loaded conditions of the engine.

Abstract: A method for operating a closed loop air/fuel ratio control system of an internal combustion engine determining the quantity of fuel to be supplied to the engine in accordance with an output signal of an exhaust gas oxygen sensor placed in an exhaust system of the engine, comprising steps for initiating a supply of an electric current to the exhaust gas oxygen sensor immediately after an ignition switch is turned on and for discriminating the activation state of the oxygen sensor by comparing the level of a combined output voltage of the oxygen sensor with a predetermined reference voltage level, at a time when a predetermined time period has passed after the supply of the electric current to the oxygen sensor, whereby eliminating a mistake of judgment which might occur due to the delay characteristics of a controller unit which determines the operational sequence of closed loop air/fuel ratio control system.

Abstract: An air/fuel ratio feedback control method which is adapted to control the air/fuel ratio of an air/fuel mixture being supplied to an internal combustion engine in response to the output of a means for detecting the concentration of an ingredient in the exhaust gases emitted from the engine. When the engine is operating in a predetermined feedback control region, control of the air/fuel ratio of the air/fuel mixture is carried out by the use of a first coefficient which has a value variable in response to the output of the aforementioned ingredient concentration detecting means, and simultaneously, the value of a second coefficient, which is a mean value of values of the first coefficient, is determined.