Abstract: A knocking determination device detects a vibration generated in an internal combustion engine during a predetermined period in each combustion cycle of the internal combustion engine. The knocking determination device performs a knocking determination of a presence or absence of a knock based on a vibration waveform in a predetermined frequency band component of the vibration detected.

Abstract: A computer implemented method and apparatus for a marine vessel data system, the method comprising: receiving data from at least one sensor configured to measure vibration and operationally arranged to the marine vessel to provide time-domain reference sensor data; maintaining the time-domain reference sensor data within a data storage system; generating a Fast Fourier Transform (FFT) on the time-domain reference sensor data to provide a plurality of reference spectra files in frequency-domain, wherein each reference spectra file comprises spectra data defined by amplitude information and frequency information, and each spectra file is associated with condition information determined based on collection of the time-domain reference sensor data; normalizing each reference spectra file by converting the frequency information to order information using the condition information to provide normalized reference spectra files; and training a convolutional autoencoder type of neural network using the normalized refe

Abstract: The present invention provides a device and method for detecting a misfire in an engine, the device being provided with: a rotation speed sensor (43) as a supercharger rotation speed measurement unit for measuring a rotation speed (Nt) of a supercharger (23); a misfire index calculation unit (51) that calculates a misfire index (Yt) from a degree of change in the rotation speed (Nt) of the supercharger (23), the rotation speed being measured by the rotation speed sensor (43); and a misfire determination unit (52) that determines a misfire in an engine (10) when the misfire index (Yt) calculated by the misfire index calculation unit (51) exceeds a pre-set determination value (D).

Abstract: A multi-cylinder spark-ignition internal combustion engine includes a monitored cylinder and a plurality of non-monitored cylinders, a pressure sensor disposed to monitor in-cylinder pressure in the monitored cylinder and a rotational position sensor. The controller is in communication with the pressure sensor, the rotational position sensor and the spark controller. The controller monitors, via the pressure sensor, in-cylinder pressure for the monitored cylinder during a combustion event, and determines a first spark timing based upon a desired spark timing and the in-cylinder pressure. A spark controller controls spark timing for the monitored cylinder based upon the final spark timing.

Abstract: When a rotational fluctuation ?NEeng of an engine is equal to or larger than a first threshold NEref1, a rotational fluctuation ?NEmg1 of a motor MG1 that is calculated at a timing preceding the rotational fluctuation ?NEeng of the engine by 180 degrees in terms of a rotational angle of a crankshaft is compared with a second threshold NEref2. When the rotational fluctuation ?NEmg1 is equal to or larger than the second threshold NEref2, it is determined that the rotational fluctuation ?NEeng of the engine has reached a value equal to or larger than a threshold NEref due to a disturbance such as running on a bad road or the like, and a misfire counter is maintained. When the rotational fluctuation ?NEmg1 is smaller than the second threshold NEref2, it is determined that a misfire may be occurring in at least one of cylinders of the engine, and the misfire counter is incremented.

Abstract: A control system is provided for use with a dual-fuel engine. The control system may have a detonation sensor configured to generate a detonation signal indicative of detonation within at least one associated cylinder of the dual-fuel engine, and a governor sensor configured to generate a demand signal associated with a demand for liquid fuel supply into the dual-fuel engine based on an output of the engine. The control system may also have a detection sensor configured to generate a detection signal indicative of a gaseous fuel presence outside the dual-fuel engine, and a controller in communication with the detonation sensor, the governor sensor, and the detection sensor. The controller may be configured to determine undesired flow of gaseous fuel based on any one or more of the detonation, demand, or detection signals.

Abstract: An engine cylinder misfire detection system is provided that detects changes in exhaust manifold pressure (EMP) fluctuations, compares the EMP fluctuations with diagnostic thresholds determined with other engine characteristic information obtained from engine sensor data, and determines whether a cylinder misfire has occurred. A method of monitoring and detecting EMP fluctuations in combination with one or more sensed engine characteristics is disclosed to determine an engine cylinder misfire in a cycle of an internal combustion engine having at least one cylinder. The actuation approaches of the present invention include one or more processes for a cylinder of an engine associated with a determination of various load variables including fresh air flow, engine type, engine data inputs, and analytical determinants.

Abstract: According to a method and an apparatus of the present invention for diagnosing a fault of an engine, a cranking rotation state is created by rotating a crank shaft while explosions in each cylinder are stopped; a variation of angular velocity of the crank shaft is detected for each cylinder in the cranking rotation state; a cylinder the compression pressure of which is insufficient is detected based on the variation; and if a cylinder indicated as a misfiring cylinder by a fault code is the same as the cylinder detected as being insufficient in compression pressure in the cranking rotation state, the cylinder is specified.

Abstract: Methods and arrangements for controlling hybrid powertrains are described. In one aspect, an engine is alternatingly operated at different effective displacements. One displacement delivers less than a requested powertrain output and the other delivers more. A motor/generator system is used to add and subtract torque to/from the powertrain to cause the net delivery of the requested powertrain output. In some embodiments, energy added and subtracted from the powertrain is primarily drawn from and stored in a capacitor (e.g., a supercapacitor or an ultracapacitor) when alternating between effective displacements. In another aspect a hybrid powertrain arrangement includes an engine a motor/generator and an energy storage system that includes both a battery and a capacitor. The capacitor stores and delivers electrical energy to the motor/generator unit during operation of the engine in a variable displacement or skip fire mode.

Abstract: A method of detecting misfire in an internal combustion engine comprises: sensing a temporal signature of a lateral displacement of the engine, performing a spectral analysis of the temporal signature of the lateral displacement to extract a magnitude of a predetermined frequency, and determining that misfiring in at least one of the plurality of cylinders has occurred based on the magnitude of the predetermined frequency. The predetermined frequency is associated with one of a plurality of orders of the engine. The one of the plurality of orders is representative of engine displacement due to in-cylinder pressures. Other methods of detecting misfire and a vehicle are also presented.

Abstract: A process for validating the fault detection of a device under test includes carrying out a series of basic tests of the device under test. Each basic test leads to a positive or negative result indicating normal or abnormal functioning of the device under test. The process also includes, after each realization of a basic test, updating an event counter (CRT) and updating a result counter (FCRT). Validation is performed depending on test result once the event counter has reached a first maximal value (CTRmax) or once the realization counter has reached a second maximal value (FCTRmax). The process can be performed by a diagnostic device. The process and device can monitor the electric or functional performance of more or less complex systems installed in an automobile.

Abstract: According to a method and an apparatus of the present invention for diagnosing a fault of an engine, a cranking rotation state is created by rotating a crank shaft while explosions in each cylinder are stopped; a variation of angular velocity of the crank shaft is detected for each cylinder in the cranking rotation state; a cylinder the compression pressure of which is insufficient is detected based on the variation; and if a cylinder indicated as a misfiring cylinder by a fault code is the same as the cylinder detected as being insufficient in compression pressure in the cranking rotation state, the cylinder is specified.

Abstract: A method of analyzing an engine for misfire activity includes receiving an electrical signal associated with a plurality of cycles of the engine, identifying energy spikes in the electrical signal associated with cylinder firings in the engine, generating engine speed estimates based on spacing between the energy spikes, and analyzing anomalies in the engine speed estimates to identify misfire activity in the engine. Also described is a method of analyzing an engine for misfire activity including receiving an electrical signal associated with the engine, detecting AC ripple in the electrical signal, generating engine speed estimates in response to the detected AC ripple, and analyzing anomalies in the engine speed estimates to identify misfire activity in the engine.

Abstract: A method for detecting abnormal combustion in the combustion chamber of at least one cylinder of a spark-ignition supercharged internal-combustion engine includes: measuring a quantity linked with the combustion of the fuel mixture in the chamber, producing a signal whose amplitude depends on the amplitude of the measured quantity, comparing the amplitude of the signal produced with the amplitude of a threshold signal corresponding to the amplitude of a signal during combustion with engine knock, determining the presence of a rumble type abnormal combustion in the combustion chamber when the amplitude of the signal produced exceeds the amplitude of the threshold signal by a significant value.

Abstract: An abnormal combustion detection method for spark-ignition internal-combustion engines, from combustion indicator distribution modelling is disclosed. At least one combustion indicator such as CA10 is determined. The distribution of N values of this indicator, acquired over N cycles preceding the cycle in progress, is modelled by determining coefficients of a theoretical distribution law. Modelling is repeated by removing extreme values from among the N values or for various working points of the engine, to obtain an evolution of the coefficients. At least one parameter characterizing evolution of at least one of these coefficients is determined. The start of an abnormal combustion is detected by comparing the parameter with a predetermined threshold, and the course of the abnormal combustion detected in the combustion chamber is controlled.

Abstract: A method of detecting misfire in an internal combustion engine comprises: sensing a temporal signature of a lateral displacement of the engine, performing a spectral analysis of the temporal signature of the lateral displacement to extract a magnitude of a predetermined frequency, and determining that misfiring in at least one of the plurality of cylinders has occurred based on the magnitude of the predetermined frequency. The predetermined frequency is associated with one of a plurality of orders of the engine. The one of the plurality of orders is representative of engine displacement due to in-cylinder pressures. Other methods of detecting misfire and a vehicle are also presented.

Abstract: An abnormal combustion detection apparatus detects an abnormal combustion of an internal combustion based on a vibration waveform from a vibration sensor attached to the internal combustion engine. A gain circuit of the apparatus amplifies or attenuates the vibration waveform from the vibration sensor, an AD conversion circuit converts a waveform provided by the gain circuit to digital data, and a gain switching unit switches a gain of the gain circuit from a small gain value to a large gain value at a gain switch timing. The gain switching unit separates a large abnormal combustion from a small abnormal combustion in an abnormal combustion determination period for maximizing a dynamic range of an AD conversion circuit and for securely detecting a change of waveform amplitude in case of gain switching in an abnormal combustion detection operation.

Abstract: A control apparatus for an internal combustion engine includes: an abnormal combustion detection unit for detecting an abnormal combustion due to self-ignition occurring; a pre-ignition determination unit for detecting abnormal combustion occurrence timing based on abnormal combustion detection information to determine whether or not the abnormal combustion is the pre-ignition based on comparison between pre-ignition determination timing and the abnormal combustion occurrence timing; a heat-source pre-ignition determination unit for determining whether the pre-ignition is the heat-source pre-ignition or the compression pre-ignition based on comparison between the abnormal combustion occurrence timing set by the pre-ignition determination timing and heat-source pre-ignition determination timing; a first avoidance unit for avoiding the heat-source pre-ignition in a case where the pre-ignition is determined as the heat-source pre-ignition; and a second avoidance unit for avoiding the compression pre-ignition in

Abstract: A method is provided for controlling an internal combustion engine. The method includes, but is not limited to the step of measuring in-cylinder pressure of an expansion phase of a combustion cycle of a cylinder of the internal combustion engine and measuring in-cylinder pressure of a compression phase of the combustion cycle of the cylinder of the internal combustion engine. A difference between a polytrophic expansion phase constant of the cylinder of the internal combustion engine and a polytrophic compression phase constant of the cylinder of the internal combustion engine is then determined using the measured expansion phase pressure and the measured compression phase pressure. A misfiring of the cylinder is later detected using the determined difference.

Abstract: A method for diagnosing combustion within a direct-injection, internal combustion engine including a plurality of combustion chambers and operative lean of stoichiometry includes monitoring pressure readings in the plurality of combustion chambers across engine crank angles, estimating a mass fraction burn percentage for each pressure reading, determining respective crank angles corresponding to a predetermined mass burn percentage for each combustion chamber, comparing said determined crank angles for sequential ones of the plurality of combustion chambers, and indicating an abnormal combustion event if compared crank angles differ by a predetermined angle.

Abstract: A supercharged internal combustion engine in a motor vehicle includes a venting device for the crankcase of the internal combustion engine and a compressor for supercharging the internal combustion engine. A discharge opening for discharging the crankcase gas is provided upstream of the compressor and a sensor for determining the charge pressure of the compressor is provided downstream of the compressor. The discharge opening is connected to the crankcase by a first connection for the airflow, in particular a hose connection. In order to cost-effectively monitor the venting of the crankcase of the internal combustion engine, an opening, to which the charge pressure of the compressor is applied, is provided downstream of the compressor. The first connection for the airflow includes a closing device for closing the opening to which the charge pressure is applied, wherein the closing device closes the opening if the first connection is connected to the discharge opening.

Abstract: An engine misfire diagnostic apparatus measures an amount of time required for a crankshaft to pass through a prescribed crank angle range corresponding to a combustion stroke to obtain time measurement values on a per cylinder basis. A first misfire parameter is obtained based on stored time measurement values from a designated cylinder, an opposing cylinder corresponding to one crankshaft rotation prior and the opposing cylinder corresponding to one crankshaft rotation later. A second misfire parameter is obtained based on stored time measurement values from the designated cylinder, a first reference cylinder whose ignition occurs one ignition prior to the designated cylinder's ignition and a second reference cylinder whose ignition occurs later than the designated cylinder's ignition, the differences weighted according to a prescribed ratio. A determination of whether the designated cylinder has misfired is based on the second misfire parameter and a derivative value of the first misfire parameter.

Abstract: In a method for diagnosing an internal combustion engine having first and second fuel injectors, if a misfire is detected, the following steps are performed in sequence: a first fuel quantity of the fuel is introduced only by the first fuel injector; a check is performed to determine whether a misfire results from the introduction of a first fuel quantity in the first step; a second fuel quantity of the fuel is introduced only by the second fuel injector; a check is performed to determine whether a misfire results from the introduction of the second fuel quantity in the third step; and an engine error is diagnosed if a misfire was detected in the second or in the fourth step.

Abstract: A combustion apparatus (water heater) includes a combustion means (burner) combusting fuel, at least two flame detecting means (flame rods) detecting whether there is a flame or not in the combustion means, a determination unit (control device) determining whether or not to be a misfire based on detected results of the flame detecting means, and a control unit (control device) stopping supply of the fuel to the combustion means in response to a determined result of the determination unit.

Abstract: For monitoring a combustion process in an internal combustion engine wherein a fuel-air mixture is ignited with a high-frequency plasma it is provided to determine the impedance of the plasma. A high-frequency signal is applied to the resonator with a capacity that is so low that no arcing-over forms on the electrodes and the high-frequency current and the high-frequency voltage are measured. The impedance of the ignited mixture is determined from the high-frequency current and the high-frequency voltage.

Abstract: An on-board diagnostic system of a vehicle comprises disabling diagnostic operation, such as a misfire monitor, based on road roughness. In one example, the disabling of the diagnostic operation is based on brake actuation and degradation of an anti-lock braking system.

Abstract: A probe and method for sensing pressure variations in the exhaust stream of an engine for detecting cylinder misfires. The probe includes a Venturi tube placed in the exhaust stream. The Venturi tube has a sensing tube with an aperture, and the sensing tube is coupled to a pressure sensor for monitoring the pressure of the exhaust stream within the Venturi tube at the point of the aperture. The pressure sensor then generates a voltage signal based on the pressure, and this voltage signal is viewed on an oscilloscope or processed by a microprocessor to generate a waveform readable by a technician. The waveform will indicate the presence of a misfiring cylinder(s), and more specifically, which cylinder(s) is misfiring.

Abstract: An apparatus and a method for detecting abnormal air-fuel ratio variation among cylinders of a multi-cylinder internal combustion engine are provided. The apparatus includes: a catalyst that is provided in an exhaust passage of the multi-cylinder internal combustion engine; a catalyst temperature detection unit that detects a temperature of the catalyst; a catalyst temperature estimation unit that estimates a temperature of the catalyst based on an engine operating state; and an abnormality detection unit that determines whether abnormal air-fuel ratio variation among the cylinders has occurred based on the detected temperature of the catalyst and the estimated temperature of the catalyst.

Abstract: The internal combustion engine system of the invention calculates a time constant of a high pass filter for eliminating a resonance component of a damper as a distortional element from a rotation speed of an engine, and sets the high pass filter with computation of a transfer function from the time constant. The set high pass filter is applied to a 30-degree rotation time representing a rotational variation of the engine to obtain a filtered 30-degree rotation time with elimination of the resonance component of the damper. The occurrence of an engine misfire is detected, based on a 30-degree rotation time difference and a misfire detection base difference computed from the filtered 30-degree rotation times. This arrangement ensures highly-accurate detection of the occurrence of a misfire in the engine constructed to output power via the damper as the distortional element, irrespective of the rotation speed of the engine.

Abstract: A misfiring cylinder identifying apparatus for a multiple cylinder internal combustion engine is provided with a determining portion that determines whether a plurality of cylinders is misfiring, and an identifying portion that identifies two cylinders among the plurality of cylinders in the order of the revolution speed fluctuation from largest as the misfiring cylinders when it is determined that the plurality of cylinders is misfiring.

Abstract: In a method for detecting combustion misses in cylinders of a combustion engine in part-engine operation in which only some of the cylinders are operated by the injection of fuel, a positional angle of the crankshaft is assigned to an angle segment; each angle segment is assigned to the particular cylinder which predominantly provides the torque for moving the crankshaft through the angle segment; an irregular running datum is determined as a function of a difference of segment pass-through times of immediately successive angle segments; and a combustion miss is detected if the irregular running datum exceeds or undershoots a limit value. In part-engine operation, the irregular running datum is determined only for two successive angle segments that are assigned to a combusting cylinder and to a non-combusting cylinder.

Abstract: A control system includes a jerk determination module and a misfire confirmation module. The jerk determination module determines a jerk of a crankshaft associated with a firing event in an engine. The misfire confirmation module selectively confirms that a misfire detected in the engine is valid based on the jerk.

Abstract: A method is provided for controlling an internal combustion engine. The method includes, but is not limited to the step of measuring in-cylinder pressure of an expansion phase of a combustion cycle of a cylinder of the internal combustion engine and measuring in-cylinder pressure of a compression phase of the combustion cycle of the cylinder of the internal combustion engine. A difference between a polytrophic expansion phase constant of the cylinder of the internal combustion engine and a polytrophic compression phase constant of the cylinder of the internal combustion engine is then determined using the measured expansion phase pressure and the measured compression phase pressure. A misfiring of the cylinder is later detected using the determined difference.

Abstract: In a misfire detection apparatus and method that detects a misfire in an internal combustion engine with cylinders provided in a vehicle, it is determined that a misfire occurs in the engine, if a first condition and a second condition are satisfied; the first condition is a condition that a rotational speed of an output shaft of the engine decreases by an amount equal to or larger than a first change amount during a time period from a compression top dead center in a first cylinder to the compression top dead center in a second cylinder; and the second condition is a condition that the rotational speed of the output shaft increases by an amount equal to or larger than a second change amount during a time period from the compression top dead center in the second cylinder to the compression top dead center in a third cylinder.

Abstract: Structured with a rotational fluctuation measuring section 51 measuring a rotational fluctuation amount DTdi, a misfire judging section 55 judging a misfire by comparing the rotational fluctuation amount with a judging threshold value, a low load judging section 56 judging an internal combustion engine operating under a low load condition, and an ignition angle judging section 57 judging an ignition angle exceeding an ignition delay angle, wherein the misfire judging section 55 has a map M1 with judging threshold values th1 with respect to rotational speeds ne of the engine and a map M2 with judging threshold values th2 with rotational fluctuation amounts larger than the map M1, and judges the misfire based on the maps M1 and M2 when the engine is operating under the low load condition with the ignition angle exceeding the ignition delay angle and, in other cases, based only on the map M1.

Abstract: At a procedure for determining at least one misfiring cylinder (1, 2, 3, 4) of a combustion engine (12) with an even number n of at least four cylinders (1, 2, 3, 4), whereby at least each cylinder (1, 2, 3, 4) is assigned to its own angle segment of a work cycle of the combustion engine (12) and whereby uneven running values (luts) are determined for each cylinder (1, 2, 3, 4), the uneven running values (luts) are evaluated with regard to the fulfillment of a condition (1., 2., 3., 4.), which is set depending on the length of the angle segment or a part or a multiple of it and which corresponds with a default misfiring pattern of the combustion engine (12).

Abstract: A failure diagnosis apparatus for a vehicle is disclosed. The apparatus includes a diagnosis processing section for executing failure diagnosis processing on a device of the vehicle to generate a diagnosis result. The apparatus also includes a data managing section for managing data of the diagnosis result. After an execution condition is met for failure diagnosis, the diagnosis processing section outputs an execution demand to the data managing section for the failure diagnosis processing. In response to the execution demand, the data managing section outputs an execution permission to the diagnosis processing section for the failure diagnosis processing. Also, after the execution condition is met for the failure diagnosis, the diagnosis processing section starts executing the failure diagnosis processing regardless of whether the execution permission has been outputted by the data managing section. A method of failure diagnosis is also disclosed.

Abstract: Method of detecting a misfire in an internal combustion engine provided with at least two cylinders and a crankshaft, includes: a. producing a measurement signal linked to the crankshaft travel time by supplying a succession of instantaneous values each corresponding to the difference between two successive segment times, each of these segment times corresponding to the time interval separating two characteristic instants of the movement of the pistons in two successive cylinders in the firing order, b. comparing the value of the measurement signal with a threshold value, and c. generating a signal representative of a misfire if the value of the measurement signal crosses the threshold value, the measurement signal having, for each cylinder, an average value that is offset relative to a reference average value, a step of reducing, for each cylinder, this offset, is performed by a high-pass filtering operation on the measurement signal.

Abstract: A method to dynamically determine a parametric value for combustion chamber deposits (CCD), e.g. in a controlled auto-ignition engine, including in-situ evaluation of thickness of CCD, based on a sensor which monitors combustion in a homogeneous charge compression ignition engine. It includes a temperature sensor operative to monitor the combustion chamber, and a CCD parameter that is based upon a peak combustion temperature measured at a crank angle. A CCD parameter can also be determined utilizing an in-cylinder pressure monitor, wherein a combustion chamber deposit parameter is based upon crank angle location of a peak in-cylinder pressure parameter.

Abstract: In an internal combustion engine including a flywheel damper, an operation range in which misfire detection is affected by the flywheel damper is set in advance. Whether or not an operation state of the internal combustion engine is within an operation range affected by the flywheel damper is determined. When the operation state is within the operation range affected by the flywheel damper, for example a cylinder specifying process specifying a misfiring cylinder is stopped. By such processing, erroneous detection attributed to irregular rotation fluctuation behavior caused by the flywheel damper can be avoided, and misfire detection performance can be improved.

Abstract: A system for detecting individual cylinder misfire in a multiple cylinder internal combustion (IC) engine having exhaust gas recirculation (EGR). The system includes: a device for predicting EGR flow rate on a cylinder to cylinder basis; a device for sensing actual EGR flow rate on a cylinder to cylinder basis with all cylinders firing; and a device for comparing the predicted EGR flow rate to the actual EGR flow to determine individual cylinder misfire.

Abstract: Method of detecting a misfire in an internal combustion engine provided with at least two cylinders and a crankshaft, includes: a. producing a measurement signal linked to the crankshaft travel time by supplying a succession of instantaneous values each corresponding to the difference between two successive segment times, each of these segment times corresponding to the time interval separating two characteristic instants of the movement of the pistons in two successive cylinders in the firing order, b. comparing the value of the measurement signal with a threshold value, and c. generating a signal representative of a misfire if the value of the measurement signal crosses the threshold value, the measurement signal having, for each cylinder, an average value that is offset relative to a reference average value, a step of reducing, for each cylinder, this offset, is performed by a high-pass filtering operation on the measurement signal.

Abstract: The internal combustion engine system of the invention calculates a time constant of a high pass filter for eliminating a resonance component of a damper as a distortional element from a rotation speed of an engine, and sets the high pass filter with computation of a transfer function from the time constant. The set high pass filter is applied to a 30-degree rotation time representing a rotational variation of the engine to obtain a filtered 30-degree rotation time with elimination of the resonance component of the damper. The occurrence of an engine misfire is detected, based on a 30-degree rotation time difference and a misfire detection base difference computed from the filtered 30-degree rotation times. This arrangement ensures highly-accurate detection of the occurrence of a misfire in the engine constructed to output power via the damper as the distortional element, irrespective of the rotation speed of the engine.

Abstract: A real-time, dynamic method for creating a body of cycle-and-cylinder-specific noise-reduction baseline data useable in conjunction with analyzing the engine-knock behavior of a subject internal combustion engine involving operating the engine in an operating mode wherein engine knock may occur, and while doing so, and during each cycle of each cylinder, gathering cycle-and-cylinder-specific, knock-free, engine-operating, baseline noise data which is intended and dedicated for noise-reduction use solely with respect to analyzing any knock data found to exist in the same operating cycle.

Abstract: An engine misfire system comprises a rough road detection module and a misfire detection module. The rough road detection module selectively generates a rough road indicator based upon a transmission output speed of a vehicle. The misfire detection module selectively diagnoses engine misfire and selectively generates a misfire indicator based on diagnosed engine misfire and the rough road indicator.

Abstract: A rotational fluctuation is given as a variation in rotation speed of a crankshaft at every specific crank angle, that is, at every 120 degrees, corresponding to an ignition timing in each cylinder of a six-cylinder engine. The engine misfire identification technique of the invention calculates a difference between a specific rotational fluctuation at a specific crank angle and a previous rotational fluctuation at a crank angle of 360 degrees before the specific crank angle as a rotational fluctuation difference, and sums up the specific rotational fluctuation at the specific crank angle and the previous rotational fluctuation at the crank angle of 360 degrees before the specific crank angle to give a total rotational fluctuation.

Abstract: The invention relates to the field of methods and devices for evaluating the knocking inside every cylinder of an internal combustion engine by making advantageous use of the ionisation current generated during the combustion of the fuel in each cylinder of said engine. The invention develops over various phases, each of which is repeated continually for each cycle of said combustion engine and is characterised by the fact that ionisation current values are selected during determined lengths of time, and said values are entered in a high-pass filter, the values determined by said filter then being squared and the value Vd calculated, said value being the relation between the value of the sum of the squares of said values obtained by said filter and a known normalisation coefficient, thus generating the spark at the spark plug in each cylinder on the basis of said value Vd.

Abstract: In an internal combustion engine including a flywheel damper, an operation range in which misfire detection is affected by the flywheel damper is set in advance. Whether or not an operation state of the internal combustion engine is within an operation range affected by the flywheel damper is determined. When the operation state is within the operation range affected by the flywheel damper, for example a cylinder specifying process specifying a misfiring cylinder is stopped. By such processing, erroneous detection attributed to irregular rotation fluctuation behavior caused by the flywheel damper can be avoided, and misfire detection performance can be improved.

Abstract: In a method for detecting combustion misses in cylinders of a combustion engine in part-engine operation in which only some of the cylinders are operated by the injection of fuel, a positional angle of the crankshaft is assigned to an angle segment; each angle segment is assigned to the particular cylinder which predominantly provides the torque for moving the crankshaft through the angle segment; an irregular running datum is determined as a function of a difference of segment pass-through times of immediately successive angle segments; and a combustion miss is detected if the irregular running datum exceeds or undershoots a limit value. In part-engine operation, the irregular running datum is determined only for two successive angle segments that are assigned to a combusting cylinder and to a non-combusting cylinder.

Abstract: A method and apparatus is presented for monitoring the cyclic variability of combustion or one or more cylinders of a reciprocating internal combustion engine. Exhaust temperature signals are acquired from one or more exhaust temperature sensors. Cycle-by-cycle values which are related to combustion characteristics are obtained from each exhaust temperature signal. Statistical parameters related to the dispersion of sets of the cycle-by-cycle values are then obtained. The statistical parameters are used to provide an indication of the cyclic variability of the engine.