Abstract: An arrangement for determining the concentration of a component in a gas mixture includes a first volume in which the concentration of the component is maintained constant with respect to the influence of the coupling to the concentration in the gas mixture. The coupling acts via a diffusion resistance. The above-mentioned influence of the coupling is compensated via a controllable flow of ions of the component through a solid electrolyte between the first volume and the gas mixture. The solid electrolyte serves as the pump device. The intensity of the pump current defines a measure for the wanted concentration in the gas mixture. The above-mentioned flow is controlled as a function of the deviation of the output voltage of a Nernst cell from a desired value. The Nernst cell is between a first volume and a reference gas volume.

Abstract: A cylinder-by-cylinder air-fuel ratio-estimating system for an internal combustion engine includes an air-fuel ratio sensor arranged in the exhaust system of the engine, at a confluent portion of the exhaust system. The air-fuel ratio of a mixture supplied to each of the cylinders is estimated based the output from the air-fuel ratio sensor, by using an observer for observing the internal operative state of the exhaust system based on a model representative of the behavior of the exhaust system. The air-fuel ratio at the confluent portion is estimated by using a delay parameter representative of the response delay of the air-fuel ratio sensor, and the air-fuel ratio of the mixture supplied to each of the cylinders is estimated by using the estimated air-fuel ratio at the confluent portion. The estimated air-fuel ratio of the mixture supplied to each of the cylinders is subsequently used for estimating a value of the air-fuel ratio at the confluent portion of the exhaust system.

Abstract: An air-fuel ratio control system for an internal combustion includes an air-fuel ratio sensor arranged in the exhaust system, and an ECU which controls an amount of fuel to be supplied to the engine in a feedback manner based on an output from the air-fuel ratio sensor by using an adaptive controller of a recurrence formula type, such that the air-fuel ratio of an air-fuel mixture supplied to the engine becomes equal to a desired air-fuel ratio. Deterioration of a response characteristic of the air-fuel ratio sensor is detected based on at least one adaptive parameter used in the feedback control of the amount of fuel to be supplied to the engine.

Abstract: A fuel metering control system for an internal combustion engine including a feedback loop having an adaptive controller and an adaptation mechanism that estimates controller parameters .theta.. The adaptive controller corrects the quantity of fuel injection to bring a controlled variable obtained at least based on an output of said air/fuel ratio sensor, to a desired value. The adaptation mechanism is input with the controlled variable once per prescribed crank angle such as a TDC of a certain cylinder and estimates the controller parameters. Since, however, the input is limited to a specific cylinder's air/fuel ratio, the air/fuel ratio is averaged for all cylinders and used in the calculation. Similar averaging is made for the other parameters input to the mechanism or output from the controller.

Abstract: A method for the calibration of a lambda probe in an internal combustion engine in which the lambda probe is arranged in front of and/or behind a catalytic converter in order to control a fuel-air mixture of the internal combustion engine. The lambda probe gives off signal values during a measurement period as a function of the exhaust gas produced from the fuel-air mixture. In order to compensate for the lack of sharpness resulting from a manufacturing process of the lambda probe and an aging of the probe, a method is proposed for the calibration of the lambda probe in which the catalytic converter is supplied with an overly rich fuel-air mixture. During this time the corresponding signal measurement values of the lambda probe are measured independently of other control signals. Upon a further processing of the probe signal, a correction value is formed therefrom, which correction value is fed to the probe signal in the controlled operating state of the internal combustion engine.

Abstract: A fuel metering control system for an internal combustion engine, having a feedback loop. In the system, the quantity of fuel injection (Tim) to be supplied to the engine (plant) is determined outside of the feedback loop. A first feedback correction coefficient (KSTR) is calculated using an adaptive law, while a second feedback correction coefficient (KLAF), whose control response is inferior to that of the first feedback correction coefficient, is calculated using a PID control law. The feedback correction coefficients are calculated such that the plant output (air/fuel ratio) is brought to a desired value (desired air/fuel ratio). The coefficients are calculated at least in parallel and either of them is selected to be multiplied by the quantity of fuel injection (Ti).

Abstract: An engine air/fuel ratio control system maintains average engine air/fuel ratio at a desired lean air/fuel ratio during cold engine operation in order to more rapidly warm the catalytic converter. Fuel delivered to the engine is modulated with a truncated triangular wave which is truncated to minimize lean air/fuel excursions. An error signal is generated from the exhaust gas oxygen sensor output, and a proportional plus integral control responsive to the error signal generates a feedback correction value to maintain the desired air/fuel ratio. Gain of the controller is increased when the error signal indicates engine air/fuel operation leaner than a preselected air/fuel ratio to further minimize excursions in a fuel enleanment direction.

Abstract: An air/fuel ratio feedback control system with the adaptive controller. The adaptive controller has a system parameter estimator which identifies system parameters such that the error between the desired value and the controlled variable outputted from the plant decreases to zero. In the system, a basic fuel injection amount is determined at a feedforward system. The adaptive controller is placed outside of the basic fuel injection amount determining system and receives the desired value (air/fuel ratio) and the controlled value (detected air/fuel ratio) using the system parameters etc. The calculated feedback coefficient is multiplied to the basic fuel injection amount to determine a final injection amount to be supplied to the plant (engine). Variables necessary for the system parameter calculation are limited their change of range so as to make the controller to be realized on a low performance computer with a small word length.

Abstract: A system for controlling fuel metering for a multi-cylinder internal combustion engine, having a feedback loop which has an adaptive controller and an adaptation mechanism coupled to the adaptive controller for estimating controller parameters .theta.. The adaptive controller calculates a feedback correction coefficient using internal variables that include the controller parameters .theta., to correct a basic quantity of fuel injection obtained by retrieving mapped data by engine speed and engine load, to bring a detected air/fuel ratio to a desired air/fuel ratio. In the system, the internal variables of the adaptive controller are determined in response to detected engine operating conditions, when the engine operation has shifted from an open-loop control region to the feedback control region.

Abstract: A feedback control system for an internal combustion engine, particularly as utilized in an outboard motor. An oxygen sensor outputs a signal indicative of the fuel-air ratio for controlling the charge-forming system of the engine to maintain the desired fuel-air ratio. A series of filters, each tuned for a different frequency and a different engine speed, are interposed between the sensor and the control for reducing the effect of noise.

Abstract: A fuel metering control system for an internal combustion engine, having a feedback loop. In the system, the quantity of fuel injection (Tim) to be supplied to the engine (plant) is determined outside of the feedback loop. A feedback correction coefficient (KSTR) is calculated using an adaptive controller and a feedback control is carried out by multiplying the quantity of fuel injection by the coefficient in the feedback control region. In view of the situation, once leaving the feedback control region due to, for example, fuel cutoff, but soon returning to the feedback control region shortly, internal variables of the adaptive controller necessary for coefficient calculation are held so as to make it unnecessary to determine the variables and to keep the control continuity and to enhance the controllability. On the other hand, if it takes a longer time to return the region, the variables are set to initial values.

Abstract: The operation of a catalyst can be monitored using a two part test. An engine management system is arranged to perturb the oxygen concentration of the exhaust gas of an internal combustion engine such that an oxygen concentration of the gas entering the catalyst varies between oxygen rich and oxygen deficient. A first test involves counting the number of transitions of the gas leaving the catalyst between two predetermined oxygen concentrations in response to a predetermined number of transitions of the gas entering the catalyst. A second test is performed if the first test indicates the catalyst to be faulty. The second test involves forming an integral of the oxygen concentration of the gas leaving the catalyst and correcting the integral for gas flow through the catalyst.

Abstract: A method and apparatus are disclosed for measuring atmospheric pressure in conjunction with an air-fuel ratio sensor of the type comprising a concentration cell with atmospheric air and exhaust electrodes on opposite sides of a solid-state electrolyte having oxygen ion conductivity. During an atmospheric pressure measuring cycle, oxygen ions are pumped from the atmospheric air electrode to the exhaust electrode, in a quantity which is either predetermined at a fixed value, or is sufficient to bring the cell to an equilibrium state. Atmospheric pressure is then calculated from measured emf of the cell, using an experimentally derived functional relationship. In a second embodiment, ions are pumped until a predetermined change of the concentration cell emf is achieved, and atmospheric pressure is determined based on the amount of time required to achieve such change. The atmospheric pressure measuring mode is operated on a time shared basis with the air-fuel ration detection mode.

Abstract: A fuel metering control system for an internal combustion engine, having a feedback loop. In the system, the quantity of fuel injection (Tim) to be supplied to the engine (plant) is determined outside of the feedback loop. A first feedback correction coefficient (KSTR) is calculated using an adaptive law, while a second feedback correction coefficient (KLAF(KSTRL)), whose control response is inferior to the first feedback correction coefficient is calculated using a PID control law. The feedback correction coefficients are calculated such that the plant output (air/fuel ratio) is brought to a desired value (desired air/fuel ratio). The engine is equipped with a variable valve timing mechanism which switches the valve timing between characteristics for low engine speed and those for high engine speed. If the characteristic for high engine speed is selected, the second feedback correction coefficient is used for fuel injection quantity correction.

Abstract: An air-fuel ratio control system for an internal combustion engine equipped with a three-way catalytic converter has first and second oxygen sensors disposed respectively upstream and downstream of the catalytic converter. An air-fuel ratio feedback correction coefficient is set in accordance with the output of the first oxygen sensor under a proportional plus integral control. The system has a control unit with a function to set a retard time in which the timing of a proportional control of air-fuel ratio control is compulsorily retarded, in accordance with the output of the second oxygen sensor. The retard time is limited within a range not longer than a maximum value set as a predetermined rate of an output cycle of the first oxygen sensor.

Abstract: A robust engine fueling control is provided for assuring neutral attainment in a vehicular automated mechanical transmission system (10) having a manually controlled master clutch (16). Upon sensing a requirement for a shift into transmission neutral, the disengaging jaw clutch members (134A/142A) are constantly urged into a disengaged position, fuel is caused to decrease to idle (302), and then fuel is blipped by increasingly larger amounts (304, 306, 308) until neutral is sensed.

Abstract: An air-fuel ratio control system for an internal combustion engine utilizes a pre-stored standard relation between an air-fuel ratio sensor signal and a standard air-fuel ratio indicative value for deriving the standard air-fuel ratio indicative value based on the sensor signal. The system further utilizes a pre-stored modified relationship between the standard air-fuel ratio indicative value and a for-control air-fuel ratio indicative value for deriving a for-control air-fuel ratio indicative value based on the derived standard air-fuel ratio indicative value. In the modified relationship, the for-control air-fuel ratio indicative value varies with respect to a corresponding variation of the standard air-fuel ratio indicative value within a given range across the standard air-fuel ratio indicative value representing a stoichiometric air-fuel ratio.

Abstract: An air/fuel control system (8) generates a fuel command (100) for fuel delivery to the engine (28) based upon at least an amount of air inducted into the engine. This fuel command is trimmed by a feedback variable derived (240-282) from an exhaust gas oxygen sensor (44) when feedback control is initiated. Feedback control is commenced when the peak-to-peak output of the sensor is less than a threshold value (122-128) while pumping current applied to a sensor electrode is modulated (122-128). Modulation is then removed but the pumping current is maintained to shift the sensor output to a preselected lean air/fuel ratio (128). Lean air/fuel feedback control continues until the converter is warmed (130-140).

Abstract: An air/fuel ratio estimator for estimating an air/fuel ratio of a mixture supplied to each cylinder of a multicylinder internal combustion engine through an output of an air/fuel ratio sensor installed at a confluence point of an exhaust system of the engine. The estimator includes first device for assuming the output of the air/fuel ratio sensor as an average value made up of a sum of products of past firing histories of each cylinder weighted by a predetermined value, and establishing a model using the air/fuel ratio as a state variable, a second device for obtaining a state equation with respect to the state variable. An observer is provided to estimate the unmeasured state variable indicative of the air/fuel ratio and the air/fuel ratio at each cylinder is estimated from an output of the observer. In the configuration upper and lower limit is established for the state variable such that it is replaced with its initial value if it exceeds either limit.

Abstract: The invention is directed to a circuit for conditioning the output signal of a measuring sensor for further processing in a control apparatus which has a fixed ground potential which does not necessarily correspond to the ground potential of the measuring sensor. A conditioning circuit is provided which can be integrated on a chip and has the following characteristics. The conditioning circuit compensates for the fluctuating ground offset between exhaust gas probe and control apparatus ground when utilizing an exhaust gas probe burdened with a potential. The circuit arrangement includes an external circuit which can be changed to influence the input signal to the conditioning circuit. With this changeable external circuit, the output signal of the circuit arrangement can be so modified that the control apparatus outputs an output voltage with offset and an output voltage without offset.

Abstract: A closed loop fuel control system for controlling air/fuel ratio in response to exhaust gas oxygen signals includes a selective hysteresis function to prevent high frequency switching after a noise spike. This improves fuel control system noise protection without introducing permanent time delays.

Abstract: Apparatus, and a corresponding method for its operation, for controlling the air/fuel ratio in a large engine having one or more banks of cylinders with separate intake and exhaust manifolds. Oxygen sensors in the manifolds are sampled periodically to provide the apparatus with an indication of the level of oxygen, and therefore an indication of the level of various pollutants, in exhaust gases discharged from the engine. The apparatus, preferably in microprocessor form, computes a fuel control correction based on the difference between the sensed oxygen level and a desired oxygen level in each exhaust manifold. The correction is applied in the form of a change to the pulse width of a binary control signal applied to a solenoid valve. In the illustrative embodiment, the solenoid valve is coupled to a fuel pressure regulator and functions to vent an air chamber in the regulator when the solenoid is actuated.

Abstract: An air-fuel ratio control system for an internal combustion engine calculates an amount of fuel to be supplied to the engine in response to the rotational speed of the engine and a parameter indicative of load on the engine, and an amount of fuel injected into an intake passage and adhering to the inner surface of the intake passage, based upon a direct supply ratio and a carry-off ratio. A feedback correction value is set to such a value that an air-fuel ratio in exhaust gases from the engine becomes equal to a desired value, and the amount of fuel calculated as above is corrected by the direct supply ratio, the carry-off ratio, and the feedback correction value set as above. A control speed at which the feedback correction value is corrected is set based upon at least one of the direct supply ratio and the carry-off ratio.

Abstract: An air fuel ratio detecting arrangement using a diffusion suppressing type air fuel ratio sensor applicable to an air fuel ratio control unit for an internal combustion engine incorporating an atmospheric air pressure correction circuit in a signal processing and outputting device for correcting an output voltage signal processed therein based on a change in atmospheric air pressure which is detected when a predetermined operating condition of an internal combustion engine is satisfied. A secular change correction circuit included in the signal processing and outputting device detects a change in electromotive force of a concentration cell portion of the air fuel ratio sensor when a predetermined rich air fuel ratio is reached and corrects a reference voltage for the air fuel ratio sensor based on the detected change in electromotive force of the concentration cell portion in addition to an air calibration circuit.

Abstract: The temperature compensated air/fuel ratio controller is used in conjunction with an internal combustion engine. The method includes electronically sensing the oxygen content and the temperature of the exhaust gas generated by the engine. It was discovered that the oxygen content signal varies in a curvilinear manner with respect to the temperature. The oxygen content signal is therefore compensated in both the linear and non-linear signal regions. The compensated oxygen content signal is then used to control the air/fuel ratio of the engine. In a working embodiment, the temperature compensated air/fuel ratio controller utilizes a zirconium oxide oxygen sensor. One type of circuitry designed to compensate the oxygen content signal in both the linear and non-linear signal regions includes, in one embodiment, electronic circuitry that segments the curvilinear function into linear segments and generates a plurality of linear compensatory signals which are added to the oxygen content signal.

Abstract: The invention is directed to a connecting circuit for a potential-free lambda probe having a ground line and a signal line and having an offset voltage source which is connected to the ground line. This offset voltage source raises the potential of the ground line to a pregiven value relative to ground. A ground short is directly detectable in the connecting circuit of the invention in that the potential measured at the signal line drops below the offset voltage. In this way, it is no longer required as in conventional circuits to check for a ground short by enriching the mixture of an engine and to monitor the exhaust gas with the lambda probe.

Abstract: An exhaust gas oxygen sensor is used to control the air/fuel ratio of an internal combustion engine in combination with an electronic engine control. The exhaust gas oxygen sensor is positioned in the exhaust stream flow from the engine. The electronic engine control utilizes different air/fuel ratio feedback strategies depending upon whether the signal output from the exhaust gas oxygen sensor is saturated indicating a rich air/fuel ratio, saturated indicating a lean air/fuel ratio or operating in a linear region.

Abstract: An amplifier having a high input dynamic range as well as high CMRR and PSRR values and input impedance while using a single supply voltage, includes an input stage with two transistors which are biased by a constant current, preferably of less than 1 microampere, while the collectors of the transistors are kept at fixed reference voltages. The input signal applied between the emitters of the transistors is transferred to the terminals of a first resistor which is supplied with current from a circuit which mirrors the current into a second resistor, from the terminals of which the output signal is taken.The preferred application is for forming interfaces for lambda probes fitted to catalytic converters for motor vehicles.

Abstract: An air/fuel mixture control system for an internal combustion engine uses a closed-loop controller which varies the air/fuel mixture in response to the oxygen level in the engine's exhaust emissions to achieve stoichiometry. The oxygen sensor produces a binary signal indicating either a rich or a lean mixture. The controller responds changes in binary sensor signal by delivering fuel at a fixed rate until either (1) the sensor responds by indication an oxygen level change or (2) a predicted transport delay interval expires. In the event the predicted interval expires before the sensor responds, the fixed rate is adjusted in an effort to obtain the desired level change within the allotted interval. In the event the level change is delayed beyond a limit, the predicted transport delay interval is enlarged.

Abstract: An air/fuel control system for use with an internal combustion engine which is adapted to burn fuels having different combustion characteristics. The control system compensates for errors in the fuel-type signal produced by a sensor. A closed-loop air/fuel mixture controller responds to sensed exhaust oxygen levels to maintain combustion near stoichiometry. When the errors from the fuel type sensor predominate, at high engine speed and load, a fuel-type variable, initially obtained from the sensor, is adaptively modified. The error compensation scheme thus adapts to changing fuels, fuel sensor errors, and differing engine operating characteristics to provide better fuel control and improved performance.

Abstract: A system for detecting deterioration of at least one HC sensor arranged in the exhaust passage of an internal combustion engine. There is calculated a difference between an actual value of output from the HC sensor and a predetermined reference value set in accordance with at least one parameter indicative of operating conditions of the engine, while the engine is in a predetermined operating condition. The difference is compared with a predetermined value. It is judged that there is deterioration in the HC sensor when the difference exceeds the predetermined value. In another aspect of the invention, the actual value of output from the HC sensor is corrected by a value of output from the HC sensor detected and stored when the fuel supply to the engine is cut off. Then, there is calculated a difference between the corrected actual value and the predetermined reference value.

Abstract: A system for controlling an air/fuel ratio for an internal combustion engine, using an oxygen concentration sensor having a first chamber for introducing therein exhaust gas of the engine and a second chamber for introducing therein reference ambient air to detect oxygen content in the exhaust gas. In order to eliminate exhaust gas pulsation which could affect on detection accuracy, it is firstly determined if engine operation is in a transient state or in a normal state. Then the detected oxygen concentration value in the preceding cycle is added to the product obtained by multiplying the deviation between the values in the preceding and current cycles by a coefficient .alpha.. The coefficient is made different in the transient state and in the normal state. In the normal engine operation state, the coefficient .alpha. is determined from engine speed and load.

Abstract: A system for controlling an air/fuel ratio of an internal combustion engine supplied with a blended fuel of gasoline and alcohol and equipped with a blowby gas ventilator. An oxygen sensor is provided and an amount of fuel supply is corrected in response to the detected air/fuel ratio within a range having a lower limit set in the lean direction and an upper limit set in the rich direction. At engine starting, injected alcohol may not vaporize but leak into the crankcase and will then vaporize to pass into the air intake passage along with the blowby gas when the engine temperature rises, causing the air/fuel ratio to be become rich beyond the correction lower limit. For that reason, in this system, engine coolant temperature and alcohol content in the fuel are detected. And if the temperature is within a range defined from the alcohol boiling point when the alcohol content is above a reference value, the lower limit of the range is shifted in the leaner direction.

Abstract: In a method for lambda value detection, the voltages of the loaded and the unloaded lambda sensor are detected and the internal resistance of the sensor is calculated from these values with the aid of the known value of the load resistance. The value of the internal resistance and the respective value of the voltage of the sensor in the unloaded state serve as input variables for a characteristic field, in which lambda values dependent on values of the internal resistance and of the voltage of the sensor in the unloaded state are stored. The method of the invention affords the advantage that lambda values can be measured very accurately even in the strongly temperature-dependent rich branch of a sensor, for example, of a sensor of the Nernst type. The values thus detected can be indicated by a measuring device or they can be used for exhaust gas control, for example in warming-up or at full load.