Abstract: A device provided in an exhaust system of an internal combustion engine in order to detect exhaust gas temperature. The device includes an oxygen sensor which has a sense element outboard of a heater element. The oxygen sensor is further designed to incorporate a temperature sensing element on the outboard of the sense element. The temperature sensing element optimizes the detection of the exhaust gas temperature, thereby providing efficient operation of the engine.

Abstract: A method is described for estimating the temperature of the exhaust gases upstream from a pre-catalyser disposed along an exhaust pipe of an internal-combustion engine, which is provided with a system for controlling the composition of the exhaust gases, comprising an oxygen sensor, which is disposed along the exhaust pipe, upstream from the pre-catalyser, a heater, which is associated with the oxygen sensor, and a control unit, which, inter alia, serves the purpose of piloting the heater. The method comprises the steps of: determining an operative quantity, which is correlated to an electrical power supplied to the heater, in order to keep the operative temperature of the oxygen sensor close to a target temperature; and determining the temperature of the exhaust gases upstream from the pre-catalyser, according to the said operative quantity.

Abstract: An air-fuel ratio sensor is equipped with a sensing element including a solid electrolytic substrate. When the sending element is warmed up and activated by a heater, a microcomputer controls electric power supplied to the heater based on a control base value being set according to a duty ratio=100%. A power profile P1 is determined beforehand to set a target heater power. Through the warm-up heater power control, an actual heater power supplied to the heater is equalized to the target heater power determined according to the power profile P1.

Abstract: A system and method for controlling a variable displacement engine include starting the engine with at least one bank of cylinders deactivated to increase load on at least one other bank of activated cylinders and reduce time required for an engine and/or vehicle component to reach a desired operating temperature. In one embodiment, ignition timing or spark is retarded and air/fuel ratio is biased lean for the activated cylinder bank during and shortly after starting to further reduce the time required for catalyst light off and closed loop operation. During activation of a deactivated bank of cylinders, air/fuel ratio of one or more activated cylinders is biased rich with air/fuel ratio of the deactivated cylinders biased lean. In addition, spark is retarded during activation of the deactivated cylinders to reduce the time necessary for components associated with the deactivated cylinders to reach desired operating temperatures.

Abstract: An A/F signal proportional to an oxygen concentration in the exhaust gas from an internal combustion engine is output upon application of a voltage based on an instruction from a microcomputer. At the time an element resistance is detected, a bias instruction signal Vr from the microcomputer is converted by a D/A converter 21 to an analog signal Vb. An output voltage Vc obtained by removing high frequency components from the analog signal Vb through an LPF 22 is input to a bias control circuit 40. During this time period in which the element resistance is detected, an accurate A/F signal is not output. Therefore, the A/F signal that has theretofore prevailed is held by a Sample/Hold circuit 70 to thereby prevent the use of an erroneous A/F signal. Namely, at the time of detecting the element resistance, the detected value of the oxygen concentration is prevented from becoming abnormal. As a result, an accurate A/F control can be executed using the detected element resistance.

Abstract: The heater control apparatus comprises an exhaust gas sensor 6 for detecting an oxygen concentration in exhaust gases of an internal combustion engine, a heater 5 for heating this exhaust gas sensor 6 to a predetermined temperature, a power source including a battery 2 for supplying electric power to this heater 5 and a charging generator 4 for charging this battery 2, a switching element 19 inserted into a circuit for supplying electric power to the heater 5 from the power source, control means 12 for performing current-carrying control of the switching element 19 so as to maintain a temperature of the exhaust gas sensor 6 at a predetermined value, and an overvoltage detection element 28 for outputting an abnormal detection signal when a voltage of the power source exceeds a predetermined value, and it is constructed so that the switching element 19 is broken to stop the passage of current to the heater 5 by the abnormal detection signal of the overvoltage detection element 28 when a voltage of the charging

Abstract: A system and method for controlling temperature of an exhaust gas oxygen sensor in a system having a variable displacement engine include monitoring temperature of the sensor, comparing the sensor temperature to a corresponding desired temperature, and controlling the system to maintain the sensor temperature at or above the desired operating temperature. In one embodiment, the sensor is a heated exhaust gas oxygen (HEGO) sensor and the method includes controlling an integrated sensor heater to maintain the sensor temperature above the desired operating temperature. Depending upon the particular application, the system may also be controlled by controlling the engine to reactivate at least one deactivated cylinder to increase the temperature of the sensor alone or in combination with controlling an integrated or auxiliary sensor heater for systems using HEGO sensor(s).

Abstract: A method and apparatus for controlling universal exhaust gas oxygen (UEGO) sensors comprises an application specific integrated circuit (ASIC) that includes a sensor control utilizing proportional-integral-derivative control loop, sensor drivers for generating pumping currents that reflect the changes of voltages representative of oxygen levels in the reference and test chambers of the UEGO sensor, a communication circuit for communicating with an engine control module, and output buffers for conditioning replications of the pumping current for delivery to an output circuit. In addition to the ASIC, a sensor interface conditions the sensor signals and an output circuit transforms the pumping circuit replications to compatible inputs for the engine control module. Preferably, all of the circuits are formed on a portion of a circuit board in the engine control module. A trim compensation circuit compensates for sensor deviation from an ideal performance standard.

Abstract: An A/F signal proportional to an oxygen concentration in the exhaust gas from an internal combustion engine is output upon application of a voltage based on an instruction from a microcomputer. At the time an element resistance is detected, a bias instruction signal Vr from the microcomputer is converted by a D/A converter 21 to an analog signal Vb. An output voltage Vc obtained by removing high frequency components from the analog signal Vb through an LPF 22 is input to a bias control circuit 40. During this time period in which the element resistance is detected, an accurate A/F signal is not output. Therefore, the A/F signal that has theretofore prevailed is held by a Sample/Hold circuit 70 to thereby prevent the use of an erroneous A/F signal. Namely, at the time of detecting the element resistance, the detected value of the oxygen concentration is prevented from becoming abnormal. As a result, an accurate A/F control can be executed using the detected element resistance.

Abstract: A heater control system is provided for controlling the temperature of a heater used to heat a solid electrolyte-made sensing element of a gas concentration sensor up to a given temperature at which the sensing element is activated to provide a desired gas concentration output for controlling a preselected variable used in a given feedback control system. The heater control system controls an electric power supplied to the heater to bring the temperature of the sensing element into agreement with a target temperature value and determines the target temperature value as a function of the preselected variable used in the feedback control system so that only desired quantity of power may be supplied to the heater, thereby minimizing a consumption of the power.

Abstract: A system for controlling a temperature of an air-fuel ratio sensor heater of an direct injection spark ignition engine which is operated at an ultra-lean burn combustion or at a pre-mixture charged combustion. In the system, the temperature of the air-fuel ratio sensor is estimated and the supply of current to the heater is determined in terms of a duty ratio in PWM based on the estimated temperature of the air-fuel ratio sensor and is increased when the engine is determined to be operated at the ultra-lean burn combustion. The duty ratio is increased by an augmentative on-time which is determined based on a parameter such as a desired torque, an engine speed and load, or a vehicle speed. The supply of current is also increased when the operation of the EGR is in progress.

Abstract: An oxygen concentration detector includes an air-fuel ratio sensor, a heater that heats the air-fuel ratio sensor, a heater controller that supplies electric power to the heater such that the air-fuel ratio sensor reaches an activation temperature, and an element temperature detector that detects a temperature of an element of the air-fuel ratio sensor. The heater controller detects a rate of decrease in the temperature of the element of the air-fuel ratio sensor based on the temperature detected by the element temperature detector, and determines that the sensor element is wetted when the detected rate of decrease is greater than a reference value. The element temperature detector can detect the sensor element temperature based on an impedance of the element. The heater controller can prevent the supply of electric power to the heater if it is determined that the sensor element is wetted. The air-fuel ratio sensor can be provided in an exhaust passage of an engine.

Abstract: A method of controlling and diagnosing the heater of a sensor sensitive to the composition of the exhaust gas of an engine; the sensor having at least an electrolytic cell sensitive to oxygen ions, and supplying information relative to the ratio of the mixture supplied to the engine; the method including the steps of: calculating an internal resistance value of the cell on the basis of detected values of the voltage at the terminals of the cell before and after supplying a reference current to the cell; correcting the calculated internal resistance value as a function of the detected ratio of the mixture supplied to the engine; converting the corrected internal resistance value into a current temperature value of the sensor; feedback controlling the temperature of the sensor by regulating the current supplied to the heater by processing the deviation between the current temperature value and an objective temperature; and diagnosing the efficiency of the heater as of the corrected internal resistance value of

Abstract: The apparatus includes a sensor capable of delivering a voltage representative of the ratio between a reference oxygen pressure and the oxygen pressure in a volume of the sensor and provided with electrodes (12, 14) via which it is possible to pass a pumping current that controls said oxygen pressure in the volume, and monitoring and control means including a digital controller (26) receiving said representative voltage on an input and suitable for delivering the pumping current. The monitoring and control means deliver the pumping current in the form of a current that varies continuously and progressively, without interruptions, governed by the digital controller in such a manner as to servo-control the input voltage to a determined value.

Abstract: According to the state of the art, either two separate sensor elements are generally used to determine the exhaust gas temperature and the air/fuel ratio, lambda, or the temperature and lambda readings are not taken simultaneously, at least at temperatures of less than 250.degree. C. In addition, sufficiently precise simultaneous measurement is only possible during stationary operation. The process according to the invention and the corresponding sensor arrangement now make it possible to obtain a precise temperature and lambda reading at a minimal degree of metrological complexity, especially under non-stationary conditions, in that a heated sensor, which exhibits a temperature-sensitive and oxygen-sensitive element on a carrier element, is used to measure the exhaust gas temperature, even at low temperatures with the heating system switched off, while a lambda reading is obtained simultaneously, with the latter being possible only at higher temperature ranges.

Abstract: An air-fuel ratio sensor of a limit current type is used for an air-fuel ratio feedback control. When the air-fuel ratio sensor is in a semi-activated state, the air-fuel ratio sensor is driven into an electromotive force generating mode by a current externally applied thereto thereby to shift an electromotive force changing point so that an air-fuel ratio at which the electromotive force changes stepwisely is shifted from the stoichiometric ratio point to a lean zone. When the air-fuel ratio sensor is in a completely activated state, the air-fuel ratio sensor is applied with a voltage to produce a limit current varying with an air-fuel ratio so that a feedback control is performed based on the advanced control theory by using a linear current output characteristics.

Abstract: The invention is directed to a method for monitoring the operation of a gas probe, such as a .lambda.-probe for an internal combustion engine. The .lambda.-probe has a probe ceramic (Nernst cell) and a probe heater. The internal resistance (x) of the probe ceramic is measured and a desired value (y) is determined in dependence upon the temperature of the gas to be detected and the heating power of the probe heater. The internal resistance (x) is then compared to the desired value (y) and, when the measured value of the internal resistance (x) exceeds the desired value (y), then a fault signal is generated and/or the fault signal is outputted and/or the fault signal is stored.

Abstract: An oxygen concentration detecting apparatus precisely and easily performs diagnosis of a limit current type oxygen sensor. The limit current type oxygen sensor has an oxygen concentration detecting element for outputting limit current proportional to the oxygen concentration and a heater for heating the detecting element. A CPU of a microcomputer controls energization of the heater to activate the oxygen sensor. The CPU calculates element resistance based on the voltage applied to the oxygen sensor and the current detected in the sensor. In a sensor diagnosis routine, the CPU determines whether preconditions for the diagnosis have been met. If all the preconditions have been met, the CPU executes the diagnosis. That is, the CPU determines whether the element resistance is within a predetermined range. If it is below the range, the CPU determines that the sensor has high element temperature abnormality.

Abstract: An on-board gas composition sensor is disclosed for monitoring oxygen content levels in the exhaust gas (24) of an internal combustion engine (4). The gas composition sensor includes a sensor body (20) mounted inan exhaust stream from an engine (4), with a fiber-optic cable (18) running from the sensor body (20) to a silicon chip (13) containing a sensor assembly(10). The sensor assembly (10) includes a light source (12), mounted on the chip (13), for generating excitation light. Also, a fiber-optic coupler (16), formed in the chip, operatively engages a second fiber-optic cable (15), mounted in a groove on the chip. The second cable (15) connects to a fluorescence detector (34) and an excitation detector (36). The two detectors produce output signals (35, 37) that are used by the electronic engine control (8) to adjust engine operation.

Abstract: A control device for a heater for an air fuel ratio sensor attached close to a sensor element of an air fuel ratio sensor located in an intake passage of an intake passage.The control device comprises an ambient temperature related parameter detecting means for detecting a parameter related an ambient temperature of the air fuel ratio sensor, an intake air amount related parameter detecting means for detecting a parameter related amount of fresh intake air introduced into intake passage, and supply power controlling means for controlling supply power based on a parameter detected by an ambient temperature related parameter detecting means and a parameter detected by an intake air amount related parameter detecting means.

Abstract: A system for estimating the temperature of an oxygen sensor installed in an exhaust system of an engine comprises a section for sensing a load of the engine; a section for sensing a rotation speed of the engine; and a section which, based on both the engine load and the engine rotation speed, calculates a basic estimated temperature of the oxygen sensor which would appear under a normal condition. A section is employed which senses a speed of the vehicle. A section is employed which, based on the vehicle speed, determines a first correction factor for correcting the basic estimated temperature. A section is employed which senses the temperature of outside air. A section is employed which, based on the outside air temperature, determines a second correction factor for correcting the basic estimated temperature.

Abstract: A method for estimating a temperature of a tip of an exhaust gas oxygen (EGO) sensor used with a heater in an electronic engine control for an engine having an exhaust system wherein the exhaust system includes a variable length exhaust pipe having a short path and a long path for transporting exhaust gas from the engine to the HEGO sensor and an exhaust valve positioned in the exhaust pipe for regulating the flow of exhaust gas between the short path and the long path utilizes control logic to determine whether the exhaust gas is flowing through the short path or the long path, determine a temperature of the unheated HEGO sensor based on the path of flow of the exhaust gas, and determine whether the heater is on. If the heater is not on, an amount of heat applied to the sensor is set to zero. If the heater is on, an increase in the temperature of the HEGO sensor is determined based on an amount of heat applied to the sensor.

Abstract: A sensing element of an oxygen sensor is controlled to keep a target impedance for maintaining activation temperature of the oxygen sensor. As the sensing element deteriorates, its internal impedance increases and power supply to a heater for heating the sensing element increases. The oxygen sensor temperature rises excessively above an activation temperature. To restrict excessive temperature rise, the target impedance is altered when the supply power to the heater exceeds a predetermined reference. The target impedance may be increased with increase in the power supply to the heater. Alternatively, the heater supply power is limited to a predetermined maximum for restricting excessive temperature rise.

Abstract: This invention provides a heater controller applied to an air-fuel ratio sensor to prevent the sensor being cooled after a return from a fuel-cut state.The temperature of a detecting element 111 of an air-fuel ratio sensor 11 is maintained at a fixed temperature by beating the heater 112, and an electric power supplied to the heater is controlled by controlling a switching element 122 of a driving circuit 12 to a proper duty ratio. The sensor is cooled during the fuel-cut state because intake air is directly exhausted to an exhaust pipe, and the temperature of the sensor does not return to the proper temperature after a return from the fuel-cut state because the ambient temperature does not immediately return to the temperature before the fuel-cut state. Therefore a heater controller prevents the sensor being cooled by increasing an electric power after the return from the fuel-cut state in accordance with an integrated intake air-flow rate during the fuel-cut state.

Abstract: An apparatus controls power supplied to a heater of an air-fuel-ratio sensor in consideration of the radiant heat from a catalytic converter. A map showing a relationship between power supplied to the heater and engine operating conditions is prepared on the assumption that radiant heat from the converter never affects the temperature of the sensor. Another map showing the same relationship is prepared on the assumption that radiant heat from the converter, which is new, affects the temperature of the sensor. A difference .DELTA.Qij=Q2ij-Q1ij is calculated under the same engine operating conditions, where Q1ij is power supplied to the heater with radiant heat from the converter affecting the temperature of the sensor and Q2ij is power supplied to the heater with radiant heat from the converter not affecting the temperature of the sensor. At the same time, a deterioration index DR of the converter is calculated. The deterioration index DR is used to determine a coefficient .alpha..

Abstract: An apparatus, for controlling a heater for heating an air-fuel ratio sensor, which is capable of preventing an excessive temperature rise of the heater after the air-fuel ratio sensor has been activated. After engine start-up, power is continuously supplied to the heater 112 until its temperature reaches about 1100.degree. C. A basic power is determined so that the heater temperature is maintained at 1100.degree. C. after reaching 1100.degree. C., and so that the temperature of a sensing element 111 is maintained at 710.degree. C. after the air-fuel ratio sensor has been activated. The basic power is corrected in increasing direction using an auxiliary power calculated as a function of coolant temperature. After the air-fuel ratio sensor has been activated, if the increased power exceeds the 1100.degree. C. basic power, the power is limited below the 1100.degree. C. base power, to prevent the heater being damaged due to an excessive temperature rise of the heater.

Abstract: A process and a device for controlling a heating element, in particular a glow plug of a self-igniting internal combustion engine, in which the current is allowed to flow through the heating element when a door contact is actuated and another condition is met.

Abstract: A heater control apparatus for an air-fuel ratio sensor that is capable of supplying optimum power, regardless of the coolant temperature of an internal combustion engine at the engine start-up, is provided. When the internal combustion engine is started, a switching element 122 is continuously held at ON state, to continuously supply power to a heater 112 of the air-fuel ratio sensor 11. The duty cycle of the switching element is controlled so that the heater temperature is maintained at 1100.degree. C., after the heater resistance, which is calculated from the voltage applied to the heater and the current flowing through the heater, has reached a predetermined value, and so that a sensing element 111 is maintained at a temperature of 710.degree. C., after the air-fuel ratio sensor was activated.

Abstract: A system for detecting the ambient temperature of an exhaust system of an internal combustion engine, where an oxygen sensor (O.sub.2 sensor) is installed for detecting oxygen content in exhaust gases generated by the engine. The oxygen sensor has a detection element and a heater for heating the detection element when supplied with current. The exhaust system is further provided with a catalytic converter which similarly has a heater for heating the catalyst for promoting the activation thereof. The electric resistance of the sensor heater is detected and based on the detected resistance, the ambient temperature of the exhaust system is detected or estimated in accordance with characteristics preestablished with respect to the electric resistance of the heater. With the arrangement, it becomes possible to detect the ambient temperature of the exhaust system without using a temperature sensor. The detected ambient temperature is used for controlling the current supply to the heater of the catalytic converter.

Abstract: A heater control system for an air-fuel ratio sensor is shown to prevent the sensor from being cooled during an extended idling operation after high-load running. An oxygen concentration detecting element of an air-fuel ratio sensor is heated by a heater installed in the sensor, and its temperature is controlled to about 650.degree. C. When a radiator cooling fan functions during idling or low-speed running after high-load running, a controller detects the functioning of the fan and increases an electric power supplied to the heater. A heater resistance detector detects a resistance of the heater. A storage device stores the detected heater resistance when it is determined that a temperature of the heater is stable based on an engine operating condition. Electric power supplied to the heater is increased in accordance with the difference between the detected resistance of the heater and the stored resistance.

Abstract: This invention provides a heater controller applied to an air-fuel ratio sensor to prevent a temperature of the sensor excessively rising or the heater installed in the sensor breaking down, when a failed sensor is replaced with a new sensor without clearing a memory which stores a resistance of the heater of the failed sensor. A resistance of the heater for heating the sensor is calculated, and is stored as a stored resistance in a back up memory. When a failed sensor is replaced with a new sensor having a lower resistance than that of the heater installed in the failed sensor without clearing the memory, an electric power supplied to the heater is increased in accordance with a current resistance of the new heater and the stored resistance of the failed heater. However, the increased electric power is limited within a interval determined by an engine operating condition.

Abstract: An apparatus to determine whether or not an air-fuel ratio sensor is fully activated is provided. In the apparatus according to the present invention, first, the point of the start of the fluctuation of the output voltage of the air-fuel ratio sensor is detected, and thereafter the fully activated state of the air-fuel ratio sensor is determined by detecting the point when the accumulated value of the difference between the present heater resistance and the standard heater resistance after the above point of the start of the fluctuation of the output voltage of the air-fuel ratio sensor, exceeds a predetermined threshold.

Abstract: A method and device for monitoring a heating device of a sensor mounted in the exhaust system of an internal combustion engine. In assessing the working order of the heating device, use is made of the fact that a sensor heated by a heating element heats up more strongly than an unheated sensor, and that it is possible to establish, with the aid of the signals output by the sensor, whether the sensor has exceeded its minimum operating temperature. The temperature of the sensor is simulated as a function of internal combustion engine operating characteristics. The working order of the heating device can be assessed with the aid of the simulated temperature and the information as to whether the minimum operating temperature is exceeded.

Abstract: The invention relates to a combination of a heated lambda sensor with a stepped or binary sensor characteristic and another heated lambda sensor to determine the lambda value in a gas mixture, e.g. in the exhaust gas preferably of internal combustion engines, the output signal from one lambda sensor being used to calibrate the other one, and the two lambda sensors are arranged closely beside each other, the other lambda sensor having a wide-baud sensor characteristic.

Abstract: This invention teaches a series parallel heated oxygen sensor control wherein a parallel portion is used to apply heat to the oxygen sensor during warm-up and a series portion is used to apply heat to the oxygen sensor afterwards so that about one quarter of the amount of power is applied after warm-up.

Abstract: A system for operating a heating element (114) of a ceramic sensor (112) which is arranged in the exhaust channel (104) of an internal combustion engine (100) and which can be heated by the heating element (114). If the internal combustion engine (100) is in an operating state in which it can be assumed that liquid is present in the exhaust channel (114) of the internal combustion engine (100), the heating element (114) is not activated or is triggered such that the ceramic sensor (112) is operated below a critical temperature (TSeK). Above the critical temperature (TSeK) there is a risk that the ceramic sensor (112) will be damaged due to contact with liquid.

Abstract: A method of inferring the temperature of a heated exhaust gas oxygen sensor is used in the control of the operation of an electronic engine control for an internal combustion engine.

Abstract: A method for pulse width modulating a resistance element of an oxygen sensor. The method quickly heats the resistance element of the oxygen sensor soon after start of the engine with a relatively high duty cycle yielding wide pulse widths. During a mid oxygen sensor temperature range, the method decreasing the duty cycle and thereby the pulse width modulation. And, upon the oxygen sensor reaching peak operating temperature range, the method decreases the pulse width modulated voltage signal supplied to the oxygen sensor to relatively short duty cycled pulses.

Abstract: An engine air/fuel control system responsive to an electrically heated exhaust gas oxygen sensor. Electrical power is supplied to the sensor by a feedback control system responsive to peak-to-peak measurement in the sensor output. Peak-to-peak measurements are averaged over a predetermined number of sample times and the resulting average value compared to a deadband. When the average measurement is above, within, or below the deadband, electrical power to the heater is, respectively, reduced, held constant, or decreased.

Abstract: A circuit and method are provided for heating a dual heater oxygen sensor. One resistance element is of relatively low resistance such that the oxygen sensor is heated quickly and the other element is of relatively high resistance such that the oxygen sensor is heated and maintained at an optimal operating temperature. The circuit and associated method turn on a low resistance start heater that is in communication with the oxygen sensor given start-up conditions. Once the oxygen sensor has reached an operating temperature range a high resistance operating temperature heater is turned on and the start heater is turned off.

Abstract: A method and system for reducing emissions from an engine during periods of partial or total heated exhaust gas oxygen (HEGO) sensor failure. A switch point is stored in an electronic engine control for use in controlling the fuel delivered to the engine based on the value of the signal generated by the oxygen sensor relative to the switch point. The method includes the step of sensing the current of the heater element of the HEGO sensor. The sensed current is compared to a first predetermined current threshold which indicates a degradation of the HEGO sensor. A degradation of the HEGO sensor introduces a bias signal to the electronic engine control. If the current of the heater element is below the first predetermined current threshold but not below a second predetermined current threshold, the switch point is changed so as to compensate for degradation of the oxygen sensor.

Abstract: An on-board gas composition sensor is disclosed for monitoring oxygen content levels in the exhaust gas of an internal combustion engine. The gas composition sensor includes a light source for generating excitation light, e.g. in the 350-525 nm wavelength range. A sensor body of porous high-temperature fluorescent inorganic oxide ceramic exposed to the exhaust gas emits an optical fluorescence signal responsive to oxygen content in the exhaust gas upon exposure to the excitation light at 400.degree.-650.degree. C. A florescence detector receives the optical fluorescence signal from the sensor means and generates an exhaust gas oxygen content output signal in response. Fiber-optic cable can be employed for transmitting excitation light to the sensor body from a remotely located light emitter. The same or a separate fiber-optic cable can transmit the optical fluorescent signal from the sensor body to the fluorescence detector also at a remote location.

Abstract: An air fuel ratio controlling apparatus for an internal combustion engine, comprises: a catalytic converter, provided in an exhaust system for purifying an exhaust gas of the engine; a first oxygen density sensor, provided upstream from the catalytic converter in the exhaust system, responsive to a first oxygen density of a first exhaust gas of the engine for detecting whether an air fuel ratio of the engine is in a rich condition or a lean condition with respect to a theoretical air fuel ratio of the engine; a second oxygen density sensor, provided downstream from the catalytic converter in the exhaust system, responsive to a second oxygen density of a second exhaust gas passed through the catalytic converter for detecting whether the air fuel ratio of the engine is in a rich or a lean condition with respect to a theoretical air fuel ratio of the engine; and an air fuel ratio control portion for controlling the air fuel ratio in accordance with the detection results of the first and second oxygen sensors, wh

Abstract: A failure detection system for an air-to-fuel ratio control system includes a exhaust gas monitor positioned upstream of a catalytic converter for monitoring an emission content of exhaust gas based on which an air-to-fuel ratio is feedback controlled so as to be maintained at a desired ratio. The system has another exhaust gas monitor positioned downstream of the catalytic converter for monitoring an emission content of exhaust gas passed through the catalytic converter. Functional failures of the exhaust gas monitor of the air-to-fuel ratio control system is judged to be present on the basis of detected emission contents only when a predetermined threshold amount of intake air is detected.

Abstract: The injection of secondary air into the exhaust system of an internal combustion engine equipped with an electrically heated catalyst (EHC) upstream of a catalytic converter using a secondary pump is controlled by use of a dedicated heated oxygen sensor located downstream of the electrically heated catalyst in the exhaust stream from said EHC. The sensor measures the oxygen content in the EHC exhaust stream and sends a signal to a controller which turns on a secondary air pump when the signal from the heated sensor exceeds a pre-selected set point on the controller thereby injecting supplementary air into the exhaust stream from the internal combustion engine to the EHC.

Abstract: An engine temperature is measured an opening of a door is detected so an electrical conduction is made to a heater for heating a sensor element by setting a target element temperature to a relatively high level if such engine temperature (cooling water temperature Thw) is relatively low or, on the other hand, by setting the target element temperature to a relatively low level if the cooling water temperature is relatively high. Then the element temperature is detected and the heater is turned off when the element temperature has reached the target temperature.

Abstract: In an internal combustion engine, an air/fuel ratio senator containing a heater for promoting activation of a sensor element is constituted such that turning-on and heating by the heater is started only after a deviation of an output of the air/fuel ratio sensor becomes more than a predetermined value after starting of the engine. Therefore, forced heating by the heater begins only after moisture in the exhaust adhering to the sensor element is made to fully evaporate by exhaust heat, thereby preventing damage on the sensor element. The damage would be caused by thermal shock due to a difference in the temperature between the inner and the outer surfaces of the sensor element due to forced heating of the moisture.

Abstract: An air-fuel ratio sensor comprises an oxygen concentration cell device, an oxygen pump device, a heater for heating the oxygen concentration cell device and the oxygen pump device, a pump current cut means for stopping the supply of the pump current, first and second timers for controlling the condition of stopping the pump current, and a controller for starting the heating of the heater under the condition of stopping the pump current, to the pump device and for removing the stopping of the pump current for a predetermined time at predetermined intervals from the starting of supplying power to the heater, by means of the first timer, wherein when the pump current shows a predetermined value or higher, the pump current is stopped and the second timer is started, and when the operation of the second timer is finished, the judgment of the activation of the sensor is made, and at the same time, the stopping of the pump current is removed.

Abstract: An oxygen-sensor abnormality detecting device for detecting abnormalities in an Oz sensor for air-fuel ratio detection in an internal combustion engine. In exhaust passage 9, a converter 10 is installed which contains a three-way catalyst for removing three harmful components HC, CO, and NOx of automotive emission. In the catalytic converter 10, a catalyst temperature sensor 11 is installed which detects catalyst temperature of the converter. O.sub.2 sensors 12 and 13 are provided along the exhaust passage on the upstream side and the downstream side of the catalytic converter 10. For the O.sub.2 sensors 12 and 13, the heaters 12a and 13a are provided for promoting the activity of the O.sub.2 sensors 12 and 13. Control circuit 15 checks the catalyst temperature and compares output voltages of the Oz sensors with reference levels under an inactive temperature state of the catalytic converter.

Abstract: An exhaust gas sensor system for use with an internal combustion engine having an exhaust conduit and a catalytic converter. The system includes an exhaust gas oxygen sensor, temperature sensor, and signal conditioner. The exhaust gas oxygen sensor is positioned on the conduit, downstream of the catalytic converter, and provides an oxygen level signal. The temperature sensor is also downstream of the catalytic converter, sensing the temperature of the oxygen sensor. A signal conditioner receives outputs from both the exhaust gas oxygen sensor and the temperature sensor. The oxygen level signal from the oxygen sensor is adjusted, according to the temperature sensed by the temperature sensor, to provide a more accurate oxygen level signal to other components of the engine such as, for example, an air-fuel controller.