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 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: A method and apparatus is provided for modulating the flux of oxygen impinging on a calorimetric gas sensor. The method and apparatus are based on modulating the oxygen concentration of a gas mixture presented to the microcalorimeter between a predetermined high level and at a substantially zero value to create a modulated output to reduce the noise of the sensor and to eliminate its zero-offset.

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 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: 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.

Abstract: An engine air/fuel control system (8) and method for controlling an engine (28) coupled to a catalytic converter (50) and for providing a measurement of engine emissions (202-296). Nitrogen oxides concentration, hydrocarbon concentration, and carbon monoxide concentration of exhaust gases downstream of the converter are measured (46, 54, and 52). Each concentration measurement is averaged for the speed load cell in which such measurement occurred (244-256). Each concentration average measurement is converted to a measurement of mass emissions emitted during a test cycle (268-284). Fuel delivered to the engine is corrected by a feedback variable (104-134, 158-178) derived from both an exhaust gas oxygen sensor (44) positioned upstream of the converter and the three sensors positioned downstream of the converter (46, 52, 54). A measurement of emissions in response to the averaged mass measurements of emission concentration downstream of the converter is also provided (278-296).

Abstract: A gas sensor for measuring gas constituents, particularly exhaust gas constituents for an internal combustion engine, comprising a pair of polysilicon plates, each plate supporting a pair of resistors, one serving as a heater and the other as a thermometer, one plate being coated with a catalyst to promote combustion of unburned combustible gas constituents, wherein provision is made for reducing temperature gradients across the plates and for effecting temperature uniformity of the catalyst while maintaining a high degree of structural integrity.

Abstract: A sensor which is selective to carbon monoxide relative to other reducing gases includes a Bi--Sr--Ca--Cu--O system metal oxide element.

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: A method of monitoring, while on board an automotive vehicle, one or more of catalyst performance, engine misfire, and combustion quality, the vehicle having an internal combustion engine equipped with a catalyst for converting noxious emissions of the engine, comprising: (i) exposing at least one pair of EGO sensors to substantially the same emissions either exiting from the engine or from the catalyst, one of the EGO sensors having its electrode highly catalytic, and the other sensor having its electrode low-to-noncatalytic; (ii) comparing the outputs of the sensor electrodes (amplitude, frequency, or phase shift) to determine if there is a sufficient differential to indicate a misfire or poor combustion in the case of the sensors being located downstream of the engine exhaust but upstream of the catalyst, or indicating poor catalyst efficiency in the case of the sensors being placed substantially immediately downstream of the catalyst. The catalyst may be a three-way catalyst (or an oxidation catalyst).

Abstract: Disclosed is a method and apparatus for determining the hydrocarbon conversion efficiency of a catalytic converter used in conjunction with an internal combustion (IC) engine to reduce the pollutants contained in the IC exhaust gas comprising the steps of: (a) determining the hydrocarbon content of the IC exhaust gas prior to its entry into the catalytic converter by sampling the exhaust and passing the sample to a catalytic differential calorimetric sensor; (b) contacting the catalyst in the converter with the IC exhaust; (c) determining the hydrocarbon content of the exhaust leaving the catalytic converter by sampling the exhaust and passing the sample to the catalytic differential calorimetric sensor; and (d) comparing the hydrocarbon contents of the exhaust samples from steps (a) and (c) and thereby determining the hydrocarbon conversion efficiency of the catalyst in the converter.

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.