Abstract: A spectral method, and corresponding system, for knock detection includes acquiring (603) spectral energy associated with vibration caused by a knocking condition from a running engine. Preferably, a sampled data system (105) acquires the spectral energy by converting an output from an accelerometer (101) into data samples (103) in a digital form. Then from the acquired spectral energy, a knock variable is derived from magnitudes of spectral components, representing a characteristic of a combustion chamber located within the running engine. In a preferred embodiment the knock variable is derived from magnitudes of spectral components related by ratios corresponding to Bessel function coefficients. The preferred embodiment includes a Digital Signal Processor (109) applying a Fast Fourier Transform method (503) to estimate a spectral content used to determine the knock variable. Then, a knock indication is provided (509) when the knock variable exceeds a magnitude of a predetermined threshold (507).

Abstract: A sensor housing (10) for directing the flow of a gas over two sensitive regions (53, 54) of sensing device (52) includes an inner shroud (12) surrounding the sensing device (52). The inner shroud (12) is inserted into an outer shroud (14), such that a plurality of gas channels (44) are formed between the inner shroud (12) and the outer shroud (14). In operation, a gas enters through inlet orifices (28) in the outer shroud (14) and travels through the gas channels (44) to the proximal end (26) of the inner shroud (12). The flow direction of the gas is then reversed and the gas passes through an inner chamber (50) and over sensitive regions (53), (54) located on the surface of the sensing device (52). Vacuum pressure created at an outlet hole (46) located at a distal end (35) of the outer shroud (14) draws the gas out of the inner chamber (50) and return the gas to the exterior of the sensor housing (10).

Abstract: A system and method measures hydrocarbon conversion efficiency of a catalytic converter (501). Total-combustible sensors (511, 521) are positioned to measure exhaust gas on both sides of the catalytic converter (501). Signals from these sensors (511, 521) have a magnitude comprised of a first portion, dependent on a concentration of the hydrocarbon gas in the gas stream, and a second portion, dependent on a concentration of the other combustible gasses in the gas stream, where a magnitude relationship between the first portion and the second portion is variable when the gas stream transitions into a region on the rich side of stoichiometry. The signals from these sensors (511, 521) are filtered so that a magnitude relationship between a first and second portion of the filtered signals is constant when the gas stream (506) transitions into the region on the rich-side of stoichiometry. Hydrocarbon conversion efficiency (529) is computed dependent on the filtered signals (515, 525).

Abstract: A system and method estimates tailpipe emissions by sensing (703) a catalyzed gas stream (506) and providing a total-combustible gas signal (511) dependent thereon. The total-combustible gas signal (511) has a magnitude comprised of a first portion, dependent on a concentration of the hydrocarbon gas in the catalyzed gas stream (506), and a second portion, dependent on a concentration of the other combustible gasses in the catalyzed gas stream (506). A magnitude relationship between the first portion and the second portion is variable when the catalyzed gas stream (506) transitions into a region on the rich side of stoichiometry. The variability the magnitude relationship of the first and second portions is filtered out so that the magnitude relationship is substantially constant when the catalyzed gas stream (506) transitions into the region on the rich side of stoichiometry.

Abstract: A modified noble metal catalyst based calorimetric sensor for sensing non-methane hydrocarbons in an automotive exhaust gas stream includes a first sensing element (105) with an output that provides a signal (111) indicative of a concentration of indicative of non-methane hydrocarbons, hydrogen (H.sub.2), and carbon monoxide (CO). A compensating sensing element (107) has an output that provides a compensating signal (113) indicative of a concentration of hydrogen (H.sub.2) and carbon monoxide (CO). A circuit for combining the signal and the compensating signal provides a combined signal indicative of a measure of non-methane hydrocarbons in the automotive exhaust gas stream.

Abstract: A system, and a corresponding method, for measuring a chemical concentration of a gas exhausted from exhaust ports (409, 413) of a multi-cylinder internal combustion engine (401) includes a gas sensing device. This device (419) is preferably a UEGO (Universal Exhaust Gas Oxygen) sensor. The gas exhausted is present in a substantially stable chemical concentration (706, 718) at a collection point (420) during intervals (738, 742) of engine angular rotation corresponding to the exhaust cycles. The UEGO sensor (419) measures the gas exhausted from the exhaust ports (409, 413) and provides a sensory output signal (743) that, during the intervals (738, 742) of engine angular rotation corresponding to each of the exhaust cycles, approaches (737, 741) a substantially stable value representative of the chemical concentration of the gas (706, 718) exhausted during the associated exhaust cycle.

Abstract: An apparatus, and corresponding method, for directly measuring air-fuel ratio of a combustion process, in an internal combustion engine is described. The apparatus includes a first electromagnetic wave sensor (105) that provides a first signal (107), representative of light intensity emitted at a first wavelength, and a second electromagnetic wave sensor (115) that provides a second signal (117), representative of light intensity emitted at a second wavelength. A ratio circuit (111, 121, 125) combines an integral of the first signal (107), and an integral of the second signal (117), and provides an air-fuel ratio signal, (127) indicative of the air-fuel ratio during the combustion process.