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: An ignition timing control system for an internal combustion engine comprises first signal generating means for generating a first signal at a crank angle position of the engine corresponding to each one of a plurality of cylinder groups; second signal generating means for generating a second signal at a crank angle position corresponding to a top-dead-center position of each cylinder, and distributing means for distributing ignition command signals to ignition devices provided for respective cylinder groups, in response to the first and second signals. Further, cylinder-discriminating means is provided for generating a third signal at a crank angle position corresponding to a particular one of the cylinders in response to the first and second signals.

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, 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: 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: 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 concentration detection system includes an oxygen sensor unit sensitive to oxygen in ambient oxygen-containing gases, an activating current supply operative to supply an activating current to the oxygen sensor unit. The oxygen sensor unit is responsive to the activating current and operative to produce a sensor signal voltage variable with the concentration of oxygen in the oxygen-containing gases. A reference signal generator produces a predetermined reference signal, the activating current supply means is responsive to the reference signal for producing the activating current. A current limiting circuit limits the oxygen concentration below a predetermined value which is variable with one of the activating current and the sensor signal voltage.

Abstract: An oxygen concentration sensing device for sensing an oxygen concentration in a gaseous body includes a pair of solid electrolyte members having oxygen ion permeability which are arranged to face each other forming a predetermined gap portion between them. Each of the solid electrolyte members is provided with a pair of electrodes and one of the solid electrolyte members is operative as an oxygen pump element when a drive current is supplied across the electrodes thereof and the other one of the solid electrolyte members is operative as a sensor cell element for producing a sensor output signal.

Abstract: A correction method for a geomagnetic field sensor (11) of a bearing indication system (10) mounted on a vehicle including a signal processor (13) for processing an output signal (Vx, Vy) of the sensor. The signal processor includes a storing function (15), comprising steps of storing the output signal of the sensor as data (6) of the bearing of the vehicle, while the vehicle is traveling, and computing a bearing correction vector (Xoff, Yoff) for correcting the output signal of the sensor on the basis of the stored bearing data. When the vehicle is judged to be subjected to a strong magnetic field, the bearing data stored may be all cleared. The bearing correction vector may be updated each time when a predetermined period of time is elapsed or the vehicle has traveled a predetermined distance.

Abstract: The present invention is directed to a phase locked driving circuit for a piezoelectric pump in a fluidic gas angular rate sensor in which the driving circuit comprises a voltage controlled oscillator for providing an oscillating drive signal to the piezoelectric pump. A phase difference detector is coupled to the output of the oscillator for detecting the phase of the current of the output signal and the phase of the voltage of the output signal and for providing an output indicative of the phase difference therebetween. An error amplifier is coupled to the phase difference detector for comparing the phase difference to a predetermined phase difference and for producing a voltage indicative thereof. The voltage of the error detecting circuit is applied to the control input of the voltage controlled oscillator for controlling the output thereof.

Abstract: A digital display for an electronic timepiece having visual indication display segments peripherally disposed around a numerical display digit to selectively indicate a predetermined time zone corresponding to the time displayed by the numerical display digits is provided. The display is characterized by a bezel surrounding the plurality of visual indication display segments, the bezel having a plurality of first distinct indicia disposed therearound. Each of the first indicia are disposed proximate to the position of a visual indication display segment to identify the predetermined time zone selectively indicated by the visual identification display segment. A plurality of second indicia are disposed on the bezel, each second indicia being positioned between a specific visual indication display segment and a further first indicia representative of the time zone adjacent to the time zone represented by the specific visual indication display segment.

Abstract: A battery monitoring circuit wherein the voltage discharge characteristic of a battery is utilized to facilitate detection of the impending failure of a battery is provided. The electronic timepiece includes a display device for displaying time in response to timekeeping signals applied thereto and is further adapted to indicate a voltage level representative of impending failure of a battery in response to an indication signal applied thereto. The battery is adapted to deliver at least two characteristic voltage levels, the first voltage level corresponding to a first plateau of discharge, and the second voltage level corresponding to a last plateau of discharge being sustained essentially at the second voltage level for a predetermined interval of time.