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 system and method of detecting a leak in an evaporative emissions system for a vehicle includes measuring a physical disturbance of the vehicle with a sensory system and providing a sensory signal (311, 313, 315). Then, comparing the sensory signal (311, 313, 315) to a threshold (405) and generating a diagnosis signal (407, 413) having a "valid test" state, when the sensory signal does not exceed the threshold, and generating the diagnosis signal having an "invalid test" state, when the sensory signal exceeds the threshold. And, executing an evaporative emissions system leak test while the provided diagnosis signal indicates the "valid test" state, and aborting the evaporative emissions system leak test (505) when the diagnosis signal indicates the "invalid test" state.

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 method of detecting low compression pressure by interpreting acceleration of an engine crankshaft (201) is detailed. In a preferred embodiment, the method teaches measurement of intake manifold pressure. Then, a first engine crankshaft acceleration is measured, preferably proximate a maximum rate of compression, for a cylinder (113), and a first variable (307) indicative of the first engine crankshaft acceleration is provided. Then, a second engine crankshaft acceleration is measured, preferably proximate the cylinder's top-dead-center position (105), and a second variable (311) indicative of the second engine crankshaft acceleration is provided. Then, the method combines (313) the intake manifold pressure, the first variable, and the second variable and provides a compression pressure variable as a function of the combined variables. Other embodiments include subsets of the above variables to provide a compression pressure variable as a function of the combined variables.

Abstract: A method for monitoring the performance of a catalytic converter includes the monitoring of output from a first gas sensor (16) positioned upstream from a catalytic converter (12) and a second gas sensor (18) located at a position downstream from the catalytic converter (12). An engine controller (20) receives the output of the first and second gas sensors (16,18) and also receives estimates of the exhaust gas mass flow rate and the catalyst temperature within the catalytic converter (12). The exhaust gas mass flow rate and the catalyst temperature are used to calculate a mass transfer coefficient that is determinative of the conversion efficiency of the catalytic converter (12). A monitoring parameter is determined using the output of the first and second gas sensors (16,18), and the monitoring parameter is normalized to the coefficient.

Abstract: A method for detrending engine positional data includes acquiring positional encoder data over a plurality of consecutive engine revolutions as the engine is decelerating. Then, a trend (207) in the acquired positional encoder data consistent with behavior occurring at less than a frequency of one cycle per engine revolution is identified. Next, corrected positional encoder data (208) is generated dependent on removing the identified trend (207).

Abstract: A misfire detection system and method measures fluctuations of air charge ingested into an engine 303, preferably as fluctuations of the engine's intake air pressure or as fluctuations of the mass air flow. A misfire indication 337 is provided dependent on a behavior of the fluctuations of air charge. Preferably, to eliminate errors associated with engine transient operating conditions, such as acceleration, the fluctuations of air charge are differentiated 325 before a misfire detection mechanism 333 is used to determine misfire behavior.

Abstract: A method and apparatus for adaptive profile correction for rotating position encoders in reciprocating engines measures a raw engine speed derived from a rotating position encoder (107) driven by a reciprocating engine. A first corrected engine speed (1103) is provided dependent on the raw engine speed and a predetermined first encoder profile while the engine is operating bounded within a first speed range (905), and a second corrected engine speed (1103) is provided dependent on the raw engine speed and a predetermined second encoder profile while the engine is operating bounded within a second speed range (913).

Abstract: An acceleration based misfire detection system with improved signal fidelity comprises a measurement device (421, 423, 425, 427) for determining an operating condition of the powertrain (401). The operating condition can include engine speed, engine load, as well as other conditions. A misfire detector (417) provides a misfire indication (419) dependent on an improved fidelity acceleration signal (415).

Abstract: An apparatus, and a corresponding method, for determining misfire in a reciprocating engine operates on a selectable quantity of discrete sampled acceleration signals that are indicative of acceleration behavior of the reciprocating engine. A decimation device selects a quantity of the discrete sampled acceleration signals dependent on an engine family, and optionally engine operating conditions such as speed and load. An accelearation signal is selected from the sampled acceleration signals, preferably the sample having the most negative magnitude. A misfire determination device provides a misfire indication dependent on the selected acceleration signal.

Abstract: A method for detecting a misfire condition by interpreting acceleration of an engine crankshaft (301) is described. The method teaches measurement of a first engine crankshaft acceleration, (405) proximate a first predetermined engine crankshaft angle, and provides a first reading (407) indicative of the first engine crankshaft acceleration, measurement of a second engine crankshaft acceleration, (417) proximate a second predetermined engine crankshaft angle, and provides a second reading (419) indicative of the second engine crankshaft acceleration, then combines (421) the first reading and the second reading and provides an acceleration coefficient (423) indicative of the combined readings. Then, a misfire is indicated (427) when the acceleration coefficient does not exceed a predetermined limit.

Abstract: A system for detecting the presence of a knock condition by interpreting a broadband spectra signal as measured from an internal combustion engine is described. The system includes a spectra measurement device, preferably an accelerometer (101) mounted to an engine for providing a broadband spectra signal (103) to a knock detector (105). Preferably the knock detector (105) is based on a digital signal processor. The signal (103) is provided simultaneously to knock discrimination elements (405, 409, and 413), that provide a knock spectra signal (415) representative of the average energy within a predetermined knock spectra, and noise discrimination elements (417, 421, and 425), that provide a noise spectra signal (427) representative of average energy within a predetermined noise spectra. The knock spectra signal (415) is combined with the noise spectra signal (427) to provide a knock signal (431) when an engine knocking condition is detected.

Abstract: A system, and corresponding method, for detecting the presence of a misfire condition by interpreting spectral activity of a running engine includes a device (309, 313) for measuring a characteristic, preferably an acceleration characteristic indicative of the running engine's performance, A spectral discrimination device (319), preferably a digital filter, receives a composite signal (317) provided by the measuring device (309, 313). The digital filter (319) provides a normal firing signal (321), corresponding to spectral energy attributable to a portion of the composite signal (317) representative of a normal firing condition in the running engine, and a misfire signal (323), corresponding to spectral energy attributable to another portion of the composite signal (317) representative of a misfiring condition in the running engine. A comparison device (325) provides and indication of a misfire condition (327) when a magnitude of the misfire signal (323) exceeds a magnitude of the normal firing signal (321).

Abstract: An arrangement is disclosed wherein a luminosity detector and a pressure transducer are used in an internal combustion engine to determine the burned gas temperature and trapped mass within each combustion chamber of the engine on a cycle-to-cycle basis or over a period of cycles, and to predict NO.sub.x emissions from the engine. Also disclosed is an arrangement wherein the burned gas temperature in each combustion chamber can be determined using only the luminosity detector.

Abstract: An internal combustion engine having a luminosity detector and an arrangement for measuring certain operating and running parameters such as peak heat release rate in the combustion chamber, NO.sub.x emissions and air/fuel ratio is provided. An arrangement is also disclosed wherein the engine's adjustable parameters can be varied in response to the luminosity signal or in response to the measured operating parameters so as to provide better running of the engine and/or reduce cycle to cycle variation.

Abstract: A method and apparatus for controlling spark reignition in an internal combustion engine based on the detected luminosity or pressure in the combustion chamber is provided. Only the luminosity or pressure measurement may be used as a basis for this control. This method and apparatus is also capable of providing same cycle control of spark reignition.

Abstract: An internal combustion engine having a luminosity probe and an arrangement for measuring certain parameters such as IMEP, combustion chamber pressure, heat release and the like by measuring luminosity in the chamber and adjusting the running parameters of the engine to obtain the desired luminosity. Also disclosed is an arrangement for maintaining uniformity from cycle to cycle in a given combustion chamber and uniformity combustion in the combustion chambers of a multi-chamber engine.

Abstract: An internal combustion engine having a luminosity probe and an arrangement for adjusting the running parameters of the engine to obtain the desired luminosity. Also disclosed is an arrangement for maintaining uniformity from cycle to cycle in a given combustion chamber and uniformity combustion in the combustion chambers of a multi-chamber engine.

Abstract: A luminosity and temperature detector for an internal combustion engine and method for measuring luminosity including a light probe and photodiode that receives the light transmitted from the light probe. The photodiode is designed, constructed and biased to operate within the zero temperature coefficient portion of its range for the wavelengths being measured. In addition, the dark current is measured when there is no luminosity due to combustion and this is subtracted from the other readings to obtain temperature compensation. Furthermore, the dark current measurement will indicate the temperature of the photodiode.