Abstract: A gas sensor control apparatus (1) includes a gas sensor (8) having an oxygen pump cell (14); a sensor drive circuit (52) which energizes the gas sensor; terminal voltage output means (54) which detects and outputs a terminal voltage of the oxygen pump cell; anomaly detection means (58) which compares the terminal voltage and a first threshold value, and when the terminal voltage exceeds the first threshold value, outputs a short circuit anomaly signal informing of a short circuit; a controller (55) which compares the terminal voltage and a second threshold value less than the first threshold value, and when the terminal voltage exceeds the second threshold value, generates a cell voltage anomaly signal informing of an application of an overvoltage to the oxygen pump cell; and command means (9) which, when receiving the short circuit anomaly signal or cell voltage anomaly signal, outputs a de-energization command.

Abstract: A gas sensor system including a gas sensor; a current control unit; a constant control unit; and a temperature acquisition unit. The gas sensor includes a measurement chamber, a pump cell and an electromotive force cell. The current control unit performs feedback control on current flowing through the pump cell in response to the voltage of the electromotive force cell and in accordance with a control constant which characterizes the feedback control. Further, the constant control unit changes the control constant of the feedback control in accordance with a value (for example, a resistance value of the electromotive force cell) corresponding to the temperature of the gas sensor.

Abstract: A gas sensor control apparatus 5 is connected to a gas sensor (8) including cells (14, 24) each having a pair of electrodes provided on a solid electrolyte body (13, 23), and includes a sensor drive circuit (52). The gas sensor control apparatus (5) includes an instruction unit for outputting an instruction for setting the sensor drive circuit (52) to a deenergization state so as to stop the supply of electricity to the cells (14, 24) and an instruction for setting the sensor drive circuit (52) to an energization state so as to supply electricity to the cells (14, 24); a setting unit (55) for setting the sensor drive circuit (52) to the deenergization state or the energization state; and a wiring anomaly detection unit (58) for detecting a wiring anomaly of the sensor drive circuit (52) or the gas sensor (8).

Abstract: A sensor control apparatus (100) includes a signal output section (60) which outputs an instruction signal for selecting a drive or protection mode, and a drive circuit (70) which controls the supply of electric current to the sensor. The drive circuit (70) includes detection means (77) for detecting an anomaly of the electrical connection state of the sensor, protection means (81), operable when the anomaly is detected, for forcedly switching to the protection mode, and report means (80) for outputting a report signal after the drive circuit has entered the protection mode. When the report is input, the signal output section outputs an instruction signal for switching the energization mode to the protection mode, and then outputs an instruction signal for switching to the drive mode. When the report signal is again input a predetermined number of times, the signal output section determines that an anomaly has occurred.

Abstract: A control device for a gas sensor is configured to: receive a mode command to specify one of a plurality of sensor energization modes including at least a gas concentration detection mode, a protection mode and a pre-energization mode; switch a sensor element of the gas sensor into the one of the plurality of sensor energization modes according to the mode command; judge satisfaction of a certain condition where the mode command is to specify the gas concentration detection mode and the sensor element is in any of the plurality of sensor energization modes other than the pre-energization mode at the time of receipt of the mode command; and prohibit the sensor element from switching over to the gas concentration detection mode when the certain condition is satisfied.

Abstract: A gas concentration detection apparatus and system including a gas sensor. Voltage Vd generated across detection resistor Rd through which pump current Ip flows is differentially amplified by OP1, and offset voltage Vofs is superposed thereon to obtain a detection voltage Vout. The amplification factor applied to the differential amplification of the voltage Vd is changed by turning switch SW3 on and off. When switch SW2 is turned on, the input terminal potentials of the operational amplifier OP1 are equalized, so that voltage Vofs is output as the detection voltage Vout. The detection voltage Vout contains an error attributable to the electronic components which form the circuit. The detection voltage Vout containing the error when SW2 is turned on is acquired as a correction voltage for each amplification factor, and is used for correction at the time of detection of the concentration so as to cancel the error.

Abstract: A gas sensor control apparatus (1) includes a gas sensor (8) having an oxygen pump cell (14); a sensor drive circuit (52) which energizes the gas sensor; terminal voltage output means (54) which detects and outputs a terminal voltage of the oxygen pump cell; anomaly detection means (58) which compares the terminal voltage and a first threshold value, and when the terminal voltage exceeds the first threshold value, outputs a short circuit anomaly signal informing of a short circuit; a controller (55) which compares the terminal voltage and a second threshold value less than the first threshold value, and when the terminal voltage exceeds the second threshold value, generates a cell voltage anomaly signal informing of an application of an overvoltage to the oxygen pump cell; and command means (9) which, when receiving the short circuit anomaly signal or cell voltage anomaly signal, outputs a de-energization command.

Abstract: A sensor control apparatus (100) includes a signal output section (60) which outputs an instruction signal for selecting a drive or protection mode, and a drive circuit (70) which controls the supply of electric current to the sensor. The drive circuit (70) includes detection means (77) for detecting an anomaly of the electrical connection state of the sensor, protection means (81), operable when the anomaly is detected, for forcedly switching to the protection mode, and report means (80) for outputting a report signal after the drive circuit has entered the protection mode. When the report is input, the signal output section outputs an instruction signal for switching the energization mode to the protection mode, and then outputs an instruction signal for switching to the drive mode. When the report signal is again input a predetermined number of times, the signal output section determines that an anomaly has occurred.

Abstract: To provide a malfunction diagnosing method and apparatus capable of reliably determining a malfunction even where the malfunction occurs in a common wire connecting a gas sensor and a control circuit for driving it. In a gas concentration measurement unit 1 having a sensor control circuit 50 which is connected to a sensor element 10 including an oxygen pump cell 14 and an oxygen concentration detection cell 24 and controls and drives this sensor element 10, a variation state of a terminal voltage at one connecting point (specifically, a Vs+ terminal) other than connecting points between electrodes facing a measurement chamber of each cell 14 and 24 and a common wire 24 is detected by a malfunction detection circuit 53 and an arithmetic processor 54. Based on this variation state of the terminal voltage, diagnosis of malfunction in the common wire 42 is executed. When the common wire 42 is broken, the terminal voltage at the Vs+ terminal varies with oscillations.

Abstract: A gas sensor apparatus 3 in an air-fuel ratio detection system 1 includes a gas sensor element 4 which outputs a detection signal corresponding to air-fuel ratio, and a gas sensor control circuit 2 which includes a detection section 20 for outputting a first output signal VIP1, a second output signal VIP2, and a third output signal VIP3 in accordance with the detection signal. This detection section 20 outputs the first output signal VIP1 which changes in accordance with the air-fuel ratio at least within a wide first air-fuel ratio zone, the second output signal VIP2 which changes in accordance with the air-fuel ratio within a narrow zone in the vicinity of the stoichiometric ratio, and the third output signal VIP3 which changes in accordance with the air-fuel ratio within a narrow zone in the lean region.

Abstract: A gas detection apparatus including a gas sensor element and a gas-sensor control circuit. The gas sensor element includes at least one sensor cell including a solid electrolyte member and a pair of electrodes, and external connection terminals electrically connected to the electrodes. The gas-sensor control circuit includes control terminals electrically connected to respective external connection terminals of the gas sensor element, an inspection current supply circuit for supplying an inspection current to an inspected terminal, which is a control terminal to be inspected for presence or absence of a short circuit to a predetermined potential, an inspection potential measurement circuit for measuring the potential of the inspected terminal, and an uninspected terminal impedance increasing circuit for increasing the impedance of the gas-sensor control circuit as viewed from an uninspected terminal, which is a control terminal other than the inspected terminal.

Abstract: A gas sensor diagnostic method includes the steps of counting the reversal number of times that a target air-fuel ratio for an air-fuel mixture to be supplied to an internal combustion engine reverses from a rich side to a lean side or from the lean side to the rich side through a specific air-fuel ratio defined as a boundary of the rich and lean sides; obtaining a detection signal of a gas sensor at constant time intervals during a diagnosis period between a timing when the count for the reversal number is started and a timing when the reversal number reaches a predetermined number; calculating a moderated signal by applying a moderation calculation using a predetermined moderation coefficient to the obtained detection signal; calculating a deviation between the obtained detection signal and the calculated moderated signal; and determining whether the gas sensor is in an abnormal state or not on the basis of the deviation.

Abstract: A gas sensor control apparatus 5 is connected to a gas sensor (8) including cells (14, 24) each having a pair of electrodes provided on a solid electrolyte body (13, 23), and includes a sensor drive circuit (52). The gas sensor control apparatus (5) includes an instruction unit for outputting an instruction for setting the sensor drive circuit (52) to a deenergization state so as to stop the supply of electricity to the cells (14, 24) and an instruction for setting the sensor drive circuit (52) to an energization state so as to supply electricity to the cells (14, 24); a setting unit (55) for setting the sensor drive circuit (52) to the deenergization state or the energization state; and a wiring anomaly detection unit (58) for detecting a wiring anomaly of the sensor drive circuit (52) or the gas sensor (8).

Abstract: A gas sensor system including a gas sensor; a current control unit; a constant control unit; and a temperature acquisition unit. The gas sensor includes a measurement chamber, a pump cell and an electromotive force cell. The current control unit performs feedback control on current flowing through the pump cell in response to the voltage of the electromotive force cell and in accordance with a control constant which characterizes the feedback control. Further, the constant control unit changes the control constant of the feedback control in accordance with a value (for example, a resistance value of the electromotive force cell) corresponding to the temperature of the gas sensor.

Abstract: In an activation state of a sensor device, when voltage on the connection points between the sensor device and the sensor control circuit becomes a preset abnormal value, electric cut off is made between the sensor control circuit and the connection point. Then, the delivery of power to the heater is ceased to lower the temperature of the cells to a below of an activation temperature, thereby increasing the internal resistance of the cell. Thereafter, the sensor control circuit supplies to the sensor device a current in a degree not to damage the sensor device, to detect voltages on the connection points at that time. By comparing between the voltages on the respective connection points detected, a content and location of abnormality occurred is identified for the sensor device.

Abstract: A gas concentration detection apparatus and system including a gas sensor. Voltage Vd generated across detection resistor Rd through which pump current Ip flows is differentially amplified by OP1, and offset voltage Vofs is superposed thereon to obtain a detection voltage Vout. The amplification factor applied to the differential amplification of the voltage Vd is changed by turning switch SW3 on and off. When switch SW2 is turned on, the input terminal potentials of the operational amplifier OP1 are equalized, so that voltage Vofs is output as the detection voltage Vout. The detection voltage Vout contains an error attributable to the electronic components which form the circuit. The detection voltage Vout containing the error when SW2 is turned on is acquired as a correction voltage for each amplification factor, and is used for correction at the time of detection of the concentration so as to cancel the error.

Abstract: An interface device for a gas sensor includes a detection resistor having first and second ends to generate voltages by a current output of the gas sensor, a differential amplifier having first and second input terminals to receive the voltages of the first and second resistor ends and an output terminal to output a voltage according to a difference between the voltages of the first and second resistor ends, a first switching element to transmit the voltage of the first resistor end to the first input terminal of the differential amplifier in a transmission state and interrupt transmission of the voltage of the first resistor end to the first input terminal of the differential amplifier in an interruption state and a second switching element turned on to establish continuity between the first and second input terminals of the differential amplifier when the first switching element is in the interruption state.

Abstract: A gas sensor diagnostic method (or apparatus) is arranged to periodically obtain sensor output values of a gas sensor such as an oxygen sensor for an internal combustion engine, and to determine local extreme values from the sensor output values obtained during a period of interruption of fuel supply to the engine. Moreover, the local extreme values are compared with a first predetermined threshold level. When the number of the local extreme values reaches a predetermined first number, a diagnosis is performed to determine whether the gas sensor is in an improper condition or not, in accordance with results of the comparison of the local extreme values with the first threshold level.

Abstract: A gas sensor diagnostic method includes: a fuel supply detecting step of detecting an interruption of a fuel supply to the internal combustion engine, and a restart of the fuel supply after the interruption of the fuel supply; a response time period accumulating step of determining a response time period by accumulating a first time period that the sensor output value reaches from a first threshold value to a second threshold value after the detection of the interruption of the fuel supply, and a second time period that the sensor output value reaches from a third threshold value to a fourth threshold value after the detection of the restart of the fuel supply after the interruption of the fuel supply; and an abnormal state diagnosing section of determining an abnormal state of the gas sensor when the response time period is greater than a predetermined time period.

Abstract: A gas sensor diagnostic method includes the steps of counting the reversal number of times that a target air-fuel ratio for an air-fuel mixture to be supplied to an internal combustion engine reverses from a rich side to a lean side or from the lean side to the rich side through a specific air-fuel ratio defined as a boundary of the rich and lean sides; obtaining a detection signal of gas sensor at constant time intervals during a diagnosis period between a timing when the count for the reversal number is started and a timing when the reversal number reaches a predetermined number; calculating a first moderated signal by applying a first moderation calculation to the detection signal, and a second moderated signal by applying a second moderation calculation to the detection signal; calculating a deviation between the first and second moderated signals; and determining whether the gas sensor is in the abnormal state on the basis of the deviation obtained during the diagnosis period.