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: When a rotation fluctuation amount of an engine exceeds a predetermined threshold, it is determined that there is a possibility that a misfire has occurred. Then, when a rotation fluctuation pattern of the engine coincides with a first rotation fluctuation pattern, it is determined that a misfire has occurred; whereas, when the rotation fluctuation pattern does not coincide with the first rotation fluctuation pattern, it is determined whether the rotation fluctuation pattern coincides with a specific rotation fluctuation pattern in consideration of a lock-up state of a lock-up clutch or whether an engine rotational speed is lower than a threshold. When the determination is affirmative, occurrence of a misfire is determined on the basis of whether the rotation fluctuation pattern of the engine coincides with a second misfire determination pattern that is defined to be smaller in variation of a rotation fluctuation amount than the first rotation fluctuation pattern.

Abstract: A damper post-stage rotation speed in a post-stage of a damper calculated from motor rotation speeds and an engine rotation speed are used to calculate a resonance influence component, and the resonance influence component is subtracted from the engine rotation speed to calculate a determination rotation speed. Then, the determination rotation speed is used to determine a misfire of an engine. This allows determination of the misfire of the engine with higher accuracy even if resonance caused by torsion of the damper occurs.

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 and method for misfire detection in a multi-cylinder internal combustion engine system includes an engine-speed activated artificial neural network (ANN)-based detection function. An input vector includes a plurality of engine speed derivatives attributable to a respective cylinder, and also includes engine speed and load values. The input vector values are updated each combustion cycle. A conventional misfire detection block is used when the engine speed is at or below an engine speed threshold. An ANN-based misfire detection block is used when the engine speed exceeds the threshold. The ANN-based block is configured to emulate a plurality of distinct ANNs each of which is conditioned by a respective set of weights and biases to correspond to and detect when a respective cylinder has misfired. The ANN-based block includes an output signal for each ANN indicating whether the respective cylinder has misfired.

Abstract: An internal-combustion-engine misfire determination system includes: detection sections that detects the rotational speeds of the output shaft and the downstream shaft; a rigidity estimation section that performs a rigidity estimation process in which frequency components caused by a resonance due to torsion of the torsion element are extracted from the rotational speeds, and the rigidity of the torsion element is estimated based on a value obtained by comparing amplitudes of both of the extracted frequency components and on the detected output shaft rotational speed; a resonance influence component calculation section that calculates a resonance influence component caused by an influence of the resonance on the output shaft rotational speed; and a misfire determination section that determines the occurrence of the misfire in the internal combustion engine based on a rotational speed for determination that is obtained by subtracting the calculated resonance influence component from the output shaft rotational

Abstract: A misfire determination device for a multi-cylinder internal combustion engine, of which an output shaft is connected, through a torsion element, to a downstream shaft downstream of the torsion element, includes: an first portion for detecting an output shaft rotational speed that is the rotational speed of the output shaft; a second portion for detecting a downstream shaft rotational speed that is the rotational speed of the downstream shaft; a third portion that calculates a component caused by an influence of resonance due to torsion of the torsion element on the output shaft rotational speed, based on the acquired output shaft rotational speed and the acquired downstream shaft rotational speed; and a fourth portion for determining the occurrence of the misfire in the internal combustion engine based on a rotational speed that is obtained by subtracting the calculated component from the detected output shaft rotational speed.

Abstract: A method and system for detecting engine misfires in a multi-cylinder internal combustion engine. The system includes a processor and a crankshaft sensor which produces an output signal to the processor representative of the angular position of the crankshaft. The processor is programmed to determine a first velocity difference between a first set of angularly spaced angular ranges of the crankshaft as well as a second velocity difference between a second set of angularly spaced angular ranges of the crankshaft. The first and second angular ranges are different from each other. The processor compares the absolute value of the greater of the first and second velocity differences with a threshold value and generates an engine misfire signal whenever that threshold is exceeded.

Abstract: A misfire detecting apparatus for an internal combustion engine wherein a rotational speed parameter according to a rotational speed of the engine is detected. A reference value of the rotational speed parameter is then calculated. Next, a difference between the reference value and a rotational speed parameter detected at every predetermined crank angle as a relative speed parameter is calculated. Further, an integrated value of the relative speed parameter is calculated, and a misfire determination is performed based on the calculated integrated value.

Abstract: An engine speed variation after one power stroke from a misfire has an opposite sign (plus or minus) relative to an engine speed variation at a misfire. A computer determines whether the misfire exists in the subject cylinder based on the engine speed variation between the subject cylinder and the subject cylinder after one power stroke. In order to detect any kinds of misfire, the computer computes a difference value between a current engine speed variation and an engine speed variation before 360° CA or after 360° CA, a difference value between a current engine speed variation and an engine speed variation before 720° CA or after 720° CA, and a difference value between a current engine speed variation and an engine speed variation before 720/(cylinder number)° CA or after 720/(cylinder number)° CA. These three difference values are respectively compared with a misfire determination value to perform a misfire detection.

Abstract: A computer implemented system for engine misfire detection employs a crankshaft-originated speed signal that includes normal variability due to target wheel tooth error and the like. A Discrete Fourier Transform (DFT) is performed on the speed signal to convert it into a frequency-domain raw misfire detection metric. The system is configured to normalize the raw misfire detection metric using a non-misfire metric that is obtained by and corresponds to non-misfire operation of an internal combustion engine. A resulting normalized misfire detection metric has such normal variations removed leaving variations attributable to misfire. The system detects a misfire when the normalized misfire detection metric exceeds a predetermined threshold and is bounded by a predetermined phase angle region. The system detects both continuous misfire as well as intermittent misfire. The system also detects single cylinder misfire and multiple cylinder misfire.

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: A system for discrimination of spurious crankshaft encoder signals. A position encoder connected to an engine crankshaft sends a pulsed signal indicative of crankshaft rotational performance to an engine controller. The controller is programmed to trigger an interrupt service routine (ISR) on every falling or rising edge of each pulse. The ISR calculates and stores the period of each pulse and the period of the previous pulse and calculates the rotational speed and instantaneous acceleration or deceleration of the engine at all times. The controller is further programmed with realistic engine acceleration and deceleration limits and recognizes a next signal only within a time window corresponding to those limits and the engine speed. Signals arriving outside the calculated time window are considered spurious and are rejected. The system improves engine performance by preventing loss of synchronization between spark and fuel injection and piston and valve timing.

Abstract: A computer implemented system for engine misfire detection employs a crankshaft-originated speed signal that includes normal variability due to target wheel tooth error and the like. A Discrete Fourier Transform (DFT) is performed on the speed signal to convert it into a frequency-domain raw misfire detection metric. The system is configured to normalize the raw misfire detection metric using a non-misfire metric that is obtained by and corresponds to non-misfire operation of an internal combustion engine. A resulting normalized misfire detection metric has such normal variations removed leaving variations attributable to misfire. The system detects a misfire when the normalized misfire detection metric exceeds a predetermined threshold and is bounded by a predetermined phase angle region. The system detects both continuous misfire as well as intermittent misfire. The system also detects single cylinder misfire and multiple cylinder misfire.