Abstract:
A method of operating a gas sensor is disclosed, wherein the sensor includes a pumping electrode configuration and a measuring electrode configuration, and wherein the method includes operating the sensor in a first mode in which a first, lower pumping potential sufficient to electrochemically remove an interfering compound from the sensor without electrochemically removing the analyte from the sensor is applied across the pumping electrode configuration and a measuring potential sufficient to electrochemically remove the analyte from the sensor is applied across the measuring electrode configuration; and operating the sensor in a second mode in which a second, higher pumping potential sufficient to electrochemically remove the analyte from the sensor is applied to the pumping electrode configuration.
Abstract:
A method and apparatus is provided for modulating flux of combustibles reacting with oxygen impinging on a calorimetric gas sensor. The method includes the steps of enclosing a sensing element and a reference element of a calorimetric gas sensor with an apparatus having at least one aperture to allow combustibles to enter and impinge on the sensing element and reference element, periodically restricting the aperture of the apparatus to modulate the flux of combustibles entering at a predetermined frequency to produce an AC output signal from the calorimetric gas sensor, and measuring the sensor output at the frequency at which the aperture is restricted.
Abstract:
An air/fuel control system which includes feedback control from an exhaust gas oxygen sensor positioned upstream of a catalytic converter. The exact air/fuel ratio required optimum converter efficiency is determined by generating an emissions signal from both a HC/CO sensor and a NO sensor each positioned downstream of the catalytic converter. The feedback variable is trimmed by a signal derived from the emissions signal to maintain air/fuel operation at a value corresponding to maximum converter efficiency.
Abstract:
A method of operating a selective combustible sensor having a pump cell and a sensor cell includes the steps of immersing the sensor in a gaseous atmosphere having at least two combustible gases and oxygen gas and allowing the gaseous atmosphere to enter a region between the pump cell and the sensor cell, applying a pumping current to the pump cell, sensing an e.m.f. (V.sub.s), across the sensor cell, varying at least either the V.sub.s or temperature to make the sensor insensitive to one of the combustible gases, and detecting the other combustible gases present in the gaseous atmosphere.
Abstract:
This invention teaches a system for interrupting operation of the internal combustion engine of a vehicle so as to prevent an undesirably high level of carbon monoxide in the ambient. Engine operation is interrupted when there are simultaneous signals indicating a carbon monoxide level above a predetermined value and and idling condition of the engine.
Abstract:
A method of operating a calorimetric gas sensor by modulating its operating temperature includes the steps of heating a sensing element and a reference element of a calorimetric gas sensor to a first temperature between a predetermined minimum temperature and a light-off temperature of the sensing element, modulating the heating of the sensing element and reference element between a second temperature above the light-off temperature and the first temperature to produce an alternating current (AC) output, and measuring the AC sensor output of the frequency of modulation.
Abstract:
A method of operating a gas sensor is disclosed, wherein the sensor includes a pumping electrode configuration and a measuring electrode configuration, and wherein the method includes operating the sensor in a first mode in which a first, lower pumping potential sufficient to electrochemically remove an interfering compound from the sensor without electrochemically removing the analyte from the sensor is applied across the pumping electrode configuration and a measuring potential sufficient to electrochemically remove the analyte from the sensor is applied across the measuring electrode configuration; and operating the sensor in a second mode in which a second, higher pumping potential sufficient to electrochemically remove the analyte from the sensor is applied to the pumping electrode configuration.
Abstract:
An improved engine control system using a NOx sensor is disclosed. In one example, the NOx sensor structure and/or signals are modified to improve distance transmission of NOx sensor output signals so that at least some processing electronics can be relocated remote to the sensor and in an engine control unit, or other such control unit utilizing the NOx sensor signals, and controlling the NOx sensor heaters, if applicable.
Abstract:
This invention is directed to an electrically heatable catalyst device comprising an electrically insulating substrate carrying an electrically conductive material selected from metal oxides, carbides, nitrides and silicides, and applied thereon a washcoat carrying a catalyst.