Abstract:
An O2 sensor has a sensor element, which includes a solid electrolyte layer and a pair of electrodes. The solid electrolyte layer is held between the electrodes, which includes an atmosphere side electrode and an exhaust side electrode. A constant current circuit is installed in an electric path, which connects between the atmosphere side electrode and a ground, to induce a flow of a predetermined constant electric current between the electrodes through the solid electrolyte layer. When the sensor element generates an electromotive force, the constant current circuit conducts an electric current, which is generated while using the electromotive force of the sensor element as an electric power source, to induce the flow of the predetermined constant electric current between the electrodes in an electromotive force range, which is equal to or larger than an electromotive force of the sensor element generated at a stoichiometric air-to-fuel ratio.
Abstract:
An O2 sensor includes a sensor element using a solid electrolyte layer and a pair of electrodes placed at a position to interpose the solid electrolyte layer, detects an exhaust gas from an internal combustion engine as an object of a detection, and outputs an electromotive force signal depending on an air-fuel ratio of the exhaust gas. The sensor element is connected with a constant current circuit supplying a constant current that is prescribed. A microcomputer calculates an element resistance, determines whether the air-fuel ratio is at least rich, lean, or stoichiometric, on the basis of a comparison between an electromotive force output of the electrogenic cell and a prescribed threshold. Further, the microcomputer controls the constant current supplied by the constant current circuit on the basis of the element resistance.
Abstract:
An O2 sensor has a sensor element, which includes a solid electrolyte layer and a pair of electrodes. The solid electrolyte layer is held between the electrodes, which includes an atmosphere side electrode and an exhaust side electrode. A constant current circuit is installed in an electric path, which connects between the atmosphere side electrode and a ground, to induce a flow of a predetermined constant electric current between the electrodes through the solid electrolyte layer. A voltage circuit is installed in an electric path, which connects between the exhaust side electrode and a ground, to increase an electric potential of the exhaust side electrode by a predetermined amount relative to an electric potential at an output side of the constant current circuit, from which the electric current flows out of the constant current circuit.
Abstract:
An O2 sensor has a sensor element, which includes a solid electrolyte layer and a pair of electrodes. The solid electrolyte layer is held between the electrodes. The electrodes include an atmosphere side electrode, which becomes a positive side at a time of outputting an electromotive force from the sensor element, and an exhaust side electrode, which becomes a negative side at the time of outputting the electromotive force from the sensor element. A resistor is provided in an electric path that connects between the atmosphere side electrode and a ground. When the sensor element generates the electromotive force, the resistor conducts an electric current, which is generated while using the electromotive force as an electric power source, to induce a change in an output characteristic of the O2 sensor.
Abstract:
An O2 sensor has a sensor element, which includes a solid electrolyte layer and a pair of electrodes, while the solid electrolyte layer is interposed between the electrodes. The O2 sensor outputs an electromotive force signal in response to an air-to-fuel ratio of exhaust gas of an engine, which serves as a sensing subject. A constant current circuit, which induces a flow of a predetermined constant electric current between the pair of electrodes of a sensor element, and a current sensing arrangement, which senses a current value of an actual electric current that is conducted through the sensor element, are provided. A microcomputer determines whether an abnormality of the constant current circuit is present based on the current value of the electric current, which is sensed with the current sensing arrangement, in a case where the constant current is induced by the constant current circuit.
Abstract:
A catalytic conversion characteristic of a catalyst, which indicates a relationship between an air-to-fuel ratio and a catalytic conversion efficiency of the catalyst, includes a second air-to-fuel ratio point, which is a point of starting an outflow of NOx from the catalyst and is located on a rich side of a first air-to-fuel ratio point that forms an equilibrium point for a rich component and oxygen. A constant current circuit, which induces a flow of an electric current from an exhaust side electrode to an atmosphere side electrode through a solid electrolyte layer in a sensor element, is connected to the sensor element. A microcomputer controls a current value of the electric current, which is induced by the constant current circuit, based on a difference between the first air-to-fuel ratio point and the second air-to-fuel ratio point at the catalyst.
Abstract:
A deterioration diagnosis device, which performs a deterioration diagnosis of a catalyst, includes an exhaust-gas sensor provided downstream of the catalyst in a flow direction of exhaust gas such that an output value of the exhaust-gas sensor is used at least in the deterioration diagnosis. The deterioration diagnosis device further includes the constant current supply portion which applies a voltage to a sensor element of the exhaust-gas sensor to change an output characteristic of the exhaust-gas sensor, a response-time detection portion which detects a response time required for the output value of the exhaust-gas sensor to change from a rich threshold to a lean threshold, a response-time correction portion which controls the constant current supply portion to change the output characteristic of the exhaust-gas sensor so as to shorten the response time when the response time is longer than a predetermined reference time.
Abstract:
An O2 sensor includes a sensor element using a solid electrolyte layer and a pair of electrodes placed at a position to interpose the solid electrolyte layer, detects an exhaust gas from an internal combustion engine as an object of a detection, and outputs an electromotive force signal depending on an air-fuel ratio of the exhaust gas. The sensor element is connected with a constant current circuit supplying a constant current that is prescribed. A microcomputer conducts an abnormality diagnosis of an output response of the sensor element on the basis of a state of variation in an electromotive force output. Further, when the microcomputer conducts the abnormality diagnosis, the microcomputer restricts a supply of the constant current by the constant current circuit before conducting the abnormality diagnosis.
Abstract:
An emission control system for an engine includes a catalyst and an exhaust-gas sensor provided downstream of the catalyst in a flow direction of exhaust gas. The exhaust-gas sensor includes a sensor element that includes a pair of electrodes and a solid electrolyte body located between the electrodes. The emission control system further includes a constant current supply portion that changes an output characteristic of the exhaust-gas sensor by applying a constant current between the electrodes, a catalytic-state determination portion which determines a rich/lean state of the catalyst, a rich direction control portion which performs and terminates a rich direction control depending on the rich/lean state of the catalyst, a lean direction control portion which performs a lean direction control after the rich direction control, and a characteristic control portion which performs a lean responsiveness control at least during the lean direction control.
Abstract:
A particulate matter sensor includes a sensor element that includes a measurement member and a heater. An anomaly determiner performs determination that there is a break fault in a signal path of the measurement signal in response to both (1) A first determiner, which determines whether a first measurement value of the measurement signal is higher than or equal to a predetermined normal determination threshold while the measurement voltage is applied between the measurement electrodes and the temperature of the measurement member is controlled at a first determination temperature, making a negative determination (2) A second determiner performing negative determination while the measurement voltage is applied between the measurement electrodes and the temperature of the measurement member is controlled within a predetermined temperature range that is higher than the first determination temperature and lower than a second determination temperature, making a negative determination