Abstract: A system for monitoring the operability of a probe heating device is introduced which comprises a probe heater, an arrangement which supplies the probe heater with the necessary electrical energy and the corresponding supply leads. The essence of the invention is that the heating current for a probe heater causes a measuring voltage on a measuring resistor connected in series with the probe heater. The measuring voltage is compared to a further voltage which is emitted by a reference element. The reference element is at a similar temperature as the measuring resistor or receives a measuring signal which corresponds to the temperature of the measuring resistor and emits a voltage which has a similar temperature response as the measuring voltage. By means of this comparison of both voltages, it is possible to conclude as to the current flowing through the heater and therefore as to the operability of the probe heating device without switching too high a resistor in series with the probe heater.

Abstract: A closed loop fuel control system for an internal combustion engine in which the temperature of the exhaust gases passing by the oxygen sensor are regulated. The system utilizes a heated oxygen sensor in a slipstream of the exhaust gas and the temperature of the exhaust gas is controlled prior to its passing by the heated oxygen sensor for maximum efficiency of the catalytic converter.

Abstract: A heated exhaust gas oxygen sensor assembly for an internal combustion engine that changes the heater status in order to detect a malfunction of the heater. The assembly includes an oxygen sensor, heater, impedance sensor, and controller. The oxygen sensor has a sensing element and a pair of output leads. The sensing element detects the relative oxygen concentration in the exhaust gas and responsively provides an oxygen level signal on the output leads. The heater physically warms the oxygen sensor. The impedance sensor is interconnected to the output leads of the oxygen sensor and measures the impedance between them. The controller first activates and then deactivates the heater. The controller also receives the impedance signals representing the impedance of the oxygen sensor when the heater is both on and off.

Abstract: A heated exhaust gas oxygen sensor assembly that automatically detects whether the heater in the assembly is malfunctioning. The assembly includes an oxygen sensor, heater, impedance sensor, and controller. The oxygen sensor detects the relative oxygen concentration in the exhaust gas of an internal combustion engine and issues signal along a pair of output leads. The heater physically warms the oxygen sensor. The impedance sensor is interconnected to the output leads of the oxygen sensor and provides an impedance measurement to the controller. The controller compares the impedance to a predetermined threshold value to judge the effect of the heater in physically warming the sensor. If the impedance is above a predetermined threshold, the controller determines that the heater is not operating properly and issues an alarm signal.

Abstract: The invention relates to a method and an arrangement for checking the operability of an electric heater in motor vehicles and especially the heater of an oxygen probe which is mounted in the exhaust gas channel of an internal combustion engine. It is necessary to determine the temperature-dependent electrical resistance and the temperature of the oxygen probe heater for a precise evaluation of the operational state of the oxygen probe heater. The basic principle of the invention is based upon the consideration that the measurement of the electrical resistance of the oxygen probe heater is then carried out when the oxygen probe heater has cooled down to the ambient temperature. Whether this cool down has taken place can be determined in various ways in accordance with the invention, for example, from the cool down of the engine block or by a comparison of the engine block temperature to the intake-air temperature.

Abstract: A device for determining activation of an air-fuel ratio sensor which comprises an air-fuel ratio sensor comprising an air-fuel ratio sensor comprising an oxygen concentration cell element and an oxygen pump element arranged in an exhaust system of an engine provided with electrodes and an interposing diffusion chamber wherein exhaust gas is diffused and introduced, and a heater for heating the oxygen concentration cell element and the oxygen pump element; a pump current controlling means for controlling pump current which flows in the pump element so that the electromotive force of the concentration cell element becomes a predetermined reference voltage; a pump current detecting means; a pump current cutting means; a pump voltage detecting means; a heater power supplying means; a memorizing means for memorizing a previous pump voltage allowable range for the pump current or a target air-fuel ratio of the engine; and a timer means operated at every predetermined time interval for starting the heater supplying

Abstract: A device for determining activation of an air-fuel ratio sensor comprising an air-fuel ratio sensor arranged in an exhaust system of an engine and having a heater for heating an oxygen concentration cell element and an oxygen pump element, a current flowing means for flowing a predetermined current from a first electrode of the concentration cell to a reference electrode, a pump current controlling means for controlling current flowing in the pump element so that a sensor voltage between the reference electrode and the first electrode becomes a reference voltage, a pump current detecting means, a current flow cutting means, a sensor voltage detecting means, a heater power supplying means, and a timer means operated at every predetermined time interval for starting the heater supplying power means to the heater during a pump-current-cut state and for operating the current flow cutting means during the predetermined time interval.

Abstract: The invention is directed to a method for the temperature open-loop control and closed-loop control of exhaust gas probes for mixture control systems having several heatable exhaust gas probes. For this purpose, the temperature of one exhaust gas probe is closed-loop controlled in a control loop and the heaters of other exhaust gas probes are open-loop controlled. The closed-loop controlled exhaust gas probe controls the open-loop controlled exhaust gas probes insofar as the actuating variable of the temperature control loop is used as the output value for the temperature open-loop control of the other exhaust gas probes.

Abstract: An apparatus for controlling a heater for an oxygen sensor includes a heater controller for detecting a heater resistance value of a heater and for controlling the heater so that a detected resistance value of the heater is equal to a target resistance value. A specific operating condition detecting unit detects a specific operating condition of the internal combustion engine where the air-fuel ratio is other than a stoichiometric air-fuel ratio. A target resistance value changing unit changes the target resistance value when the air-fuel ratio in the specific operating condition indicated by the sensor output signal is s outside a normal range of air-fuel ratio which should be detected in the specific operating condition.