Internal combustion engine misfire detection
First Claim
1. In an internal combustion engine having a plurality of cylinders each cylinder having a piston mechanically linked to a crankshaft and reciprocally driven in the cylinder to rotate the crankshaft by cylinder combustion events in which an air-fuel mixture provided to the engine cylinders is ignited by timed application of an ignition drive signal to cylinder spark plugs, a method for diagnosing improper combustion conditions in the engine cylinders, comprising the steps of:
- generating fuel injection control commands;
outputting the fuel injection control commands to control delivery of fuel to the engine;
generating ignition control commands;
outputting the ignition control commands to drive spark plugs of the engine cylinders;
generating reference signals at predetermined angular positions of the crankshaft;
determining reference periods as timed durations between each adjacent reference signal;
diagnosing an improper combustion condition in a selected engine cylinder, by (a) identifying a first and second determined reference period corresponding to the selected engine cylinder, (b) calculating an ideal reference period for the identified first and second determined reference periods, (c) estimating noise and disturbance content in the identified first and second reference periods, (d) processing the identified first and second reference periods by removing the ideal reference period and the estimated noise and disturbance content from said first and second reference periods, (e) forming a misfire component as a difference between the processed first and second reference periods, (f) comparing the magnitude of the misfire component to a predetermined threshold component, and (g) diagnosing an improper cylinder combustion condition in the selected engine cylinder when the magnitude of the misfire component exceeds the predetermined threshold component.
14 Assignments
0 Petitions
Accused Products
Abstract
Internal combustion engine control and diagnostics provides for delivery of a fuel quantity and intake air to engine cylinders and for an ignition signal to ignite the air and fuel, wherein misfire conditions in the cylinder are diagnosed over all operating conditions through a reference period model of the components of measured reference periods not attributed to a misfire condition and through removal of such components from measured reference periods yielding a resultant reference period component sensitive only to misfire conditions. The magnitude, position, and stability of the resultant component indicates misfire severity, location, and persistence.
18 Citations
10 Claims
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1. In an internal combustion engine having a plurality of cylinders each cylinder having a piston mechanically linked to a crankshaft and reciprocally driven in the cylinder to rotate the crankshaft by cylinder combustion events in which an air-fuel mixture provided to the engine cylinders is ignited by timed application of an ignition drive signal to cylinder spark plugs, a method for diagnosing improper combustion conditions in the engine cylinders, comprising the steps of:
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generating fuel injection control commands; outputting the fuel injection control commands to control delivery of fuel to the engine; generating ignition control commands; outputting the ignition control commands to drive spark plugs of the engine cylinders; generating reference signals at predetermined angular positions of the crankshaft; determining reference periods as timed durations between each adjacent reference signal;
diagnosing an improper combustion condition in a selected engine cylinder, by (a) identifying a first and second determined reference period corresponding to the selected engine cylinder, (b) calculating an ideal reference period for the identified first and second determined reference periods, (c) estimating noise and disturbance content in the identified first and second reference periods, (d) processing the identified first and second reference periods by removing the ideal reference period and the estimated noise and disturbance content from said first and second reference periods, (e) forming a misfire component as a difference between the processed first and second reference periods, (f) comparing the magnitude of the misfire component to a predetermined threshold component, and (g) diagnosing an improper cylinder combustion condition in the selected engine cylinder when the magnitude of the misfire component exceeds the predetermined threshold component. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 10)
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9. In an engine control system for issuing fuel injector control commands for controlling delivery of fuel to an engine having n cylinders and an output shaft, and for issuing ignition control commands to spark plugs for timing ignition, in a cylinder combustion event, of a mixture of engine intake air and the delivered fuel in engine cylinders, a method for diagnosing engine cylinder misfire conditions, comprising the steps of:
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generating reference periods indicating output shaft rotation rate following each cylinder combustion event; processing each individual reference period of a predetermined first and second reference period generated following combustion events in corresponding first and second engine cylinders, by; (a) determining a reference period mean over a predetermined plurality of the generated reference periods including the individual reference period; (b) removing transient content from the reference period by subtracting the mean from the individual reference period; (c) removing periodic, time-varying noise and disturbance content from the individual reference period; determining a difference between the processed first and second reference periods; comparing the difference to a predetermined difference threshold value; and diagnosing a misfire condition in the first engine cylinder when the difference exceeds the predetermined difference threshold value.
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Specification