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 misfire detection method and apparatus includes measurement of combustion induced torque in an internal combustion engine and provision of time-ordered first, second, and third acceleration data samples dependent on the torque. A misfire is indicated when a magnitude of the second acceleration data sample has a magnitude less than a misfire threshold, and less than a magnitude of both the first and third acceleration data samples.

Abstract: A method for monitoring and controlling the performance of a catalytic converter (34) includes monitoring an exhaust gas stream from an engine (16) for the presence of methane. Upon detecting methane in the exhaust gas stream an oxygen storage level of a catalyst within the catalytic converter (34) is determined. The oxygen storage level is compared with a reference standard and the air/fuel ratio of the exhaust gas stream is continuously adjusted to maintain the oxygen storage level within predetermined control limits.

Abstract: A method, and a corresponding system, for determining misfire in a reciprocating engine measures engine crankshaft angular velocity and provides an angular velocity signal as measured from the engine crankshaft (403). A filtered acceleration signal, dependent on the engine crankshaft angular velocity signal and independent of normal combustion information and other high-order effects is provided via filtering (405). When the filtered acceleration signal exceeds a threshold dependent on at least one of the following; engine speed, engine load, or engine temperature (711), a misfire is indicated. Preferably, prior to the misfire determination, the filtered acceleration signal (701) is sampled over a first period of engine crankshaft rotation to provide a first data point (703), over a second period of engine crankshaft rotation to provide a second data point (707), and over a third period of engine crankshaft rotation to provide a third data point (705).

Abstract: A method and system of combustion control for an internal combustion engine (313) proximate an extinction limit includes measurement of acceleration behavior of the internal combustion engine and providing a measure of combustion variability dependent thereon. Preferably, the combustion variability measure is derived by one or more stochastically based methods (607). Operation of the internal combustion engine (313) is controlled dependent on the combustion variability measurement. Fuel, ignition, and exhaust gas recirculation may all be controlled by the derived combustion variability measurement to significantly reduce hydrocarbon (HC) and NO.sub.x emissions.

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 apparatus and method of detecting a leak in an evaporative emissions system measures vapor flow out of the evaporative emissions system while maintaining a zero pressure difference from inside a fuel tank to atmosphere and provides a reference vapor flow variable dependent on the measurement (317). A pressurized vapor and leak flow variable is measured (323) dependent on measured vapor flow out of the evaporative emissions system while maintaining a pressure difference of 10" of water from inside the fuel tank to atmosphere. A leak is indicated (327) if a difference between the reference vapor flow variable and the pressurized vapor and leak flow variable is greater than a predetermined leak flow factor.

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 is provided having a luminosity detector and an arrangement for adjusting the parameters of the engine in response to sensed combustion conditions within the combustion chamber based on particular gain independent parameters of the luminosity signal. The gain independent luminosity parameters can also be used to obtain uniform combustion conditions from cycle to cycle in a given combustion chamber and uniform combustion in the combustion chambers of multi chamber engine.

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: An internal combustion engine is provided having a luminosity detector and an arrangement for measuring certain parameters and running conditions of the engine such as air/fuel ratio in response to sensed combustion conditions within the combustion chamber based on particular gain independent parameters of the luminosity signal and selected engine parameters such as speed. The gain independent luminosity parameters can also be used in an engine control loop to ajust the various parameters of the engine like air/fuel ratio so as to obtain the desired luminosity characteristics and to obtain better running of the engine.

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.