Method and apparatus for detecting misfires and idenfifying causes
First Claim
1. A method of checking the performance of an internal combustion engine, the engine including a cylinder having a piston an associated exhaust valve and an intake valve, the engine further including a crankshaft and camshaft means, the camshaft means including an exhaust cam and an intake cam, the method including the steps of:
- a. replacing one of the spark plug, fuel injector or glow plug from the cylinder with a pressure transducer;
b. rotating the crankshaft of the engine fast enough to build pressure within the cylinder and through at least one compression stroke where the piston is momentarily at top dead center (hereinafter TDC 0°
);
c. measuring the pressure changes in the cylinder while the crankshaft is being rotated fast enough to build pressure in the cylinder;
d. generating a cylinder pressure waveform from the measured pressure changes in the cylinder; and
e. from the cylinder pressure waveform analyzing the magnitude and timing of at least one of the pressure changes in the cylinder.
3 Assignments
0 Petitions
Accused Products
Abstract
A method of identifying misfires in an engine including: running the engine; measuring the pressure pulses from the exhaust; generating a waveform from the measured pulses; dividing the waveform into segments; associating each waveform segment with the cylinder which generated the pulse; and examining each segment for features which indicate a misfire. Also disclosed is methodology for checking the performance of an engine including cam timing and identifying the probable cause(s) of misfires. This includes generating a cylinder pressure waveform from the measured pressure changes in a cylinder and analyzing the magnitude and timing of at least one of the pressure changes in such cylinder. Further disclosed is methodology for analyzing the pressure changes in the engine'"'"'s intake manifold and in the crankcase. Finally, additional diagnostic procedures are disclosed for: checking the ignition timing of an engine; and using the apparatus and methods with additional instrumentation including gas analyzers.
34 Citations
35 Claims
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1. A method of checking the performance of an internal combustion engine, the engine including a cylinder having a piston an associated exhaust valve and an intake valve, the engine further including a crankshaft and camshaft means, the camshaft means including an exhaust cam and an intake cam, the method including the steps of:
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a. replacing one of the spark plug, fuel injector or glow plug from the cylinder with a pressure transducer; b. rotating the crankshaft of the engine fast enough to build pressure within the cylinder and through at least one compression stroke where the piston is momentarily at top dead center (hereinafter TDC 0°
);c. measuring the pressure changes in the cylinder while the crankshaft is being rotated fast enough to build pressure in the cylinder; d. generating a cylinder pressure waveform from the measured pressure changes in the cylinder; and e. from the cylinder pressure waveform analyzing the magnitude and timing of at least one of the pressure changes in the cylinder. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method of creating a vacuum in a diesel engine which does not have intake manifold vacuum at idle, to permit the generation of one or more cylinder pressure waveforms, which waveforms mimic those from a engine which has intake manifold pressure at idle, the method including the step of placing at least a partial restriction over the induction inlet of the intake manifold of the diesel engine to create intake manifold vacuum at idle.
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26. A method of checking the performance of an internal combustion engine by analyzing the pressure changes in the engine'"'"'s intake manifold, the engine including an intake manifold and a crankshaft, the method including the steps of:
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a. connecting a pressure transducer to the intake manifold; b. rotating the crankshaft of the engine fast enough to create a pressure differential in the intake manifold; c. measuring the pressure changes in the manifold while the crankshaft is being rotated fast enough to create a pressure differential in the intake manifold; d. generating an intake pressure waveform from the measured pressure changes in the intake manifold; and e. analyzing at least a portion of the intake pressure waveform for one or more features indicative of a problem with the engine. - View Dependent Claims (27, 28, 29, 30)
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31. A method of checking the performance of an internal combustion engine, the engine including a cylinder having a piston an associated exhaust valve and an intake valve, the engine further including an intake manifold, a crankcase, a crankshaft and camshaft means, method including the steps of:
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a. rotating the crankshaft of the engine fast enough to build pressure within the cylinder and the intake manifold; b. measuring the pressure changes in the cylinder while the crankshaft is being rotated fast enough to build pressure in the cylinder; c. generating a cylinder pressure waveform from the measured pressure changes in the cylinder; d. measuring the pressure changes in the crankcase while the crankshaft is being rotated; e. generating a crankcase pressure waveform form the measured pressure changes in the crankcase; and f. comparing the crankcase pressure waveform with the cylinder pressure waveform. - View Dependent Claims (32, 33)
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34. A method of checking the ignition timing of an internal combustion engine, the method including the steps of:
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a. replacing one of the spark plug, fuel injector or glow plug from the cylinder with a pressure transducer; b. rotating the crankshaft of the engine fast enough to build pressure within the cylinder and through at least two successive compression strokes where the piston is at a first top dead center and the cylinder pressure peaks (hereinafter TDC 0°
) and a second top dead center 720°
of crankshaft rotation later and the cylinder pressure peaks a second time (hereinafter TDC 720°
);c. measuring the time between the first compression peak and the second compression peak; d. dividing the measured time by 720 to obtain the degrees of crankshaft rotation per unit of time; e. obtaining a trigger signal; f. marking the trigger signal; g. measuring the time between the trigger signal and one of the compression peaks; and h. determining the ignition timing from the time between trigger signal and compression peak and the degrees of crankshaft rotation per unit of time.
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35. A method of diagnosing an internal combustion engine, the method including the steps of:
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a. conducting a first test to identifying at least one misfiring cylinder; and b. conducting a second test to determine the probable cause of the misfire, the second test selected from the group including analyzing PID data, analyzing Calculated PID data, analyzing the engine'"'"'s tailpipe emissions with a gas analyzer, and analyzing the engine'"'"'s ignition with an ignition analyzer.
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Specification