摘要:
A method of stabilizing pump current in a gas sensor through suppression of oscillations of the pump current which result from pulsations of measured gas is provided. The gas sensor includes an oxygen pump element, an oxygen concentration cell element and a measurement gap between the oxygen pump element and the oxygen concentration cell element, and is operative to control the pump current through the oxygen pump element so that an output voltage of the oxygen concentration cell element is constant in order that an oxygen concentration in the measurement gap is maintained constant and detect an oxygen concentration in the measured gas on the basis of the pump current. The method comprising adjusting an activity of electrodes of an oxygen pump element so as to change a responsiveness in control of the pump current and thereby reduce an amplitude of the oscillations of the pump current. There is also provided the above described type gas sensor wherein the activity of the electrodes of the oxygen pump element is adjusted so as to change a responsiveness in control of the pump current and thereby reduce the oscillations of the pump current.
摘要:
Using a gas detection voltage Vs output from a terminal CU, a determination is made at to whether, after startup of an air-fuel ratio detection apparatus (1), a full-range air-fuel ratio sensor (10) has reached a semi-activated state in which a determination can be made as to whether the air-fuel ratio is on the rich or lean side based on a change in a gas detection signal Vic. After determining that the sensor has reached the semi-activated state, the signal Vic is compared with a threshold to determine whether the air-fuel ratio is on the rich or lean side. In the apparatus (1), the potential difference between an outer pump electrode of a pump cell (14) and a reference electrode of an oxygen concentration measurement cell (24) is obtained via a first differential amplification circuit (53) as the gas detection signal Vic, the signal Vic being highly responsive to a change in air-fuel ratio of exhaust gas.
摘要:
A constant current Iconst is applied to an electromotive force cell which is interposed between a gap (measurement chamber) of a fixed atmosphere and an oxygen reference chamber of a constant oxygen content, for measurement of a resistance value of the electromotive force cell, whereby the resistance value can be measured accurately irrespective of an oxygen content in an atmosphere to be measured by an oxygen sensor element or cell unit. The resistance value of the electromotive force cell is measured at a predetermined timing T2 after application of a current is started, so that a measure resistance value is free of a variation of a resistance value due to deterioration of porous electrodes of an electromotive force cell, such a variation being included in the measured resistance value in case the measurement is done by using an AC current, and therefore accurate measurement can be attained. A temperature control methods and a temperature control apparatus for an oxygen sensor, capable of detecting the temperature accurately without suspending measurement of an oxygen content for a long period of time are also provided. Further, a temperature control method and a temperature control apparatus for an oxygen sensor, capable of detecting not only the temperature of the electromotive force cell but the temperature of the pump cell by applying a current or voltage to the electromotive force cell are provided.
摘要:
Using a gas detection voltage Vs output from a terminal CU, a determination is made at to whether, after startup of an air-fuel ratio detection apparatus (1), a full-range air-fuel ratio sensor (10) has reached a semi-activated state in which a determination can be made as to whether the air-fuel ratio is on the rich or lean side based on a change in a gas detection signal Vic. After determining that the sensor has reached the semi-activated state, the signal Vic is compared with a threshold to determine whether the air-fuel ratio is on the rich or lean side. In the apparatus (1), the potential difference between an outer pump electrode of a pump cell (14) and a reference electrode of an oxygen concentration measurement cell (24) is obtained via a first differential amplification circuit (53) as the gas detection signal Vic, the signal Vic being highly responsive to a change in air-fuel ratio of exhaust gas.
摘要:
A method of detecting an activated condition of a wide range air-fuel ratio sensor is provided. With this method, application of a current to a heater is started idiately after an engine is started (S00). Then, a current Icp for pumping is passed through an electromotive force cell (S10). A lapse of a predetermined time Tin is waited for (S18). After a lapse of time Tin, a voltage Vs across both electrodes of the electromotive force cell is detected (S20) and labeled as Vs0 (S22). Then, application of Icp is suspended (S30) and a routine is held on standby until a time of 25 ms elapses (S35). At the point of time when the time of 25 ms has elapsed, the voltage across the electrodes on the opposite sides of the electromotive force cell is detected (S40) and labeled as Vs1 (S45). A resistance value Rs1 is calculated from Vs0, Vs1 and Icp (S50). The resistance value Rs1 is compared with a value Rss which has been prepared previously (S55) and it is judged, when Rs1 is smaller than Rss, that the electromotive force cell has been put into an activated condition. An apparatus for detecting an activated condition of a wide range air-fuel ratio sensor is also provided.
摘要:
A defect detection method for a sensor in which a fixing member provides a seal between a sensor element and tubular metallic members, the method being capable of detecting breakage of a conductor caused by breakage of the element.
摘要:
A defect detection method for a sensor in which a fixing member provides a seal between a sensor element and tubular metallic members, the method being capable of detecting breakage of a conductor caused by breakage of the element.
摘要:
A method of detecting a deteriorated condition of a wide range air-fuel ratio sensor is provided. Firstly, a current is applied to an electromotive force cell to detect a voltage Vs0 across electrodes on opposite side surfaces of the cell. Application of the current is suspended, and a voltage drop Vsd1 across the electrodes is detected after lapse of a time ranging from 10 .mu.s to 1 ms after the application of the current is suspended. Based on the voltage drop Vsd1 is detected a first resistance value Rvs1 equated to the temperature of the electromotive force cell. Further, after lapse of a time ranging from 10 ms to 50 ms after the application of the current to the electromotive force cell is suspended, a voltage drop Vsd2 across the electrodes of the electromotive force cell is detected. Based on the voltage drop Vsd2 is detected a second resistance value Rvs2 equated to an internal resistance of the electromotive force cell including a resistance component resulting from deterioration. By comparison of the resistance values Rvs1 and Rvs2, the deteriorated condition of the wide range air-fuel ratio is detected. An apparatus for carrying out such a method is also provided.
摘要:
An anomaly diagnosing apparatus and method for a gas sensor which includes a heater control section; a measurement section which outputs a detection signal for detecting an internal resistance of the gas sensor through a solid electrolyte via connection terminals and the electrodes within the gas sensor and which measures the internal resistance of the gas sensor based on a response signal input via the connection terminals in response to the output of the detection signal; and a diagnosing section which heats the solid electrolyte by use of the heater control section, obtains, after the start of heating, a first time required to reach a first resistance and a second time required to reach a second resistance different from the first resistance, and determines whether or not the gas sensor is anomalous by comparing a predetermined threshold value and a ratio of the first to second times.
摘要:
An anomaly diagnosing apparatus and method for a gas sensor which includes a heater control section; a measurement section which outputs a detection signal for detecting an internal resistance of the gas sensor through a solid electrolyte via connection terminals and the electrodes within the gas sensor and which measures the internal resistance of the gas sensor based on a response signal input via the connection terminals in response to the output of the detection signal; and a diagnosing section which heats the solid electrolyte by use of the heater control section, obtains, after the start of heating, a first time required to reach a first resistance and a second time required to reach a second resistance different from the first resistance, and determines whether or not the gas sensor is anomalous by comparing a predetermined threshold value and a ratio of the first to second times.