US5487008A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and system for detecting the misfire of a reciprocating internal combustion engine in frequency domain
Assignee: University of Michigan (System)
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Filing: 1993-02-26
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Granted: 1996-01-23
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Expires: 2013-02-26
Abstract
Abstract Engine misfire is detected in a reciprocating internal combustion engine having an engine cycle frequency in the frequency domain from crankshaft angular velocity. Crankshaft angular position is sensed to develop an electrical signal which is a function of the crankshaft angular velocity. The electrical signal contains data which is sampled. The sampled data is transformed to an equivalent frequency domain spectrum including frequency components of the engine cycle frequency and harmonics thereof. A statistical decision algorithm is applied to the magnitudes of the frequency components to distinguish between a true misfire and normal cyclic variability which characterizes the combustion process. In one embodiment, the misfired cylinder is identified based on the phase of the frequency component at the engine cycle frequency. In another embodiment, the identity of the misfired cylinder is determined by shifting the sampled data prior to transforming the data.
Inventors
- 👤 William B. Ribbens
- 👤 Jaehong Park
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:51
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1497; F02D41/1498; F02D41/22; G; G01; G01M; G01M15/00; G01M15/04; G01M15/11; F02B; F02B75/00; F02B75/02; F02B2075/022; F02B2075/025; F02B3/00; F02B3/06; F02D41/1401; F02D2041/1413; F02D2041/1432; F02D41/24; F02D41/26; F02D41/28; F02D2041/286; F02D2041/288; F02D2200/00; F02D2200/02; F02D2200/10; F02D2200/1015; F02D2400/00; F02D2400/04; F02D41/0097
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
162 words
A method for detecting a misfire of a reciprocating internal combustion engine including a plurality of reciprocating components having an engine cycle frequency, N cylinders and a crankshaft, the method comprising the steps of: generating an electrical signal as a function of crankshaft angular velocity, the electrical signal containing data; sampling the data synchronously with crankshaft angular position at a sampling rate to obtain sampled data; transforming the sampled data to an equivalent frequency domain spectrum, including frequency components having complex amplitudes at the engine cycle frequency and harmonics thereof; and applying an algorithm to the magnitudes of the frequency components, which algorithm distinguishes between a true misfire and normal cycle variability which characterizes the combustion process in each cylinder of the engine to thereby obtain a misfire signal and wherein the method further comprises the step of shifting the sampled data for (N-1) of the cylinders prior to the step of transforming to identify the cylinder in which the misfire occurred.
Claim 2
Independent Claim
162 words
A method for detecting a misfire of a reciprocating internal combustion engine including a plurality of reciprocating components having an engine cycle frequency, N cylinders and a crankshaft, the method comprising the steps of: generating an electrical signal as a function of crankshaft angular velocity, the electrical signal containing data; sampling the data synchronously with crankshaft angular position at a sampling rate to obtain sampled data; transforming the sampled data to an equivalent frequency domain spectrum, including frequency components having complex amplitudes at the engine cycle frequency and harmonics thereof; and applying an algorithm to the magnitudes of the frequency components, which algorithm distinguishes between a true misfire and normal cycle variability which characterizes the combustion process in each cylinder of the engine to thereby obtain a misfire signal and wherein the method further comprises the step of shifting the sampled data for (N-1) of the cylinders prior to the step of transforming to identify the cylinder in which the misfire occurred.
Claim 3
Dependent Claim
39 words
The method as claimed in claim 1 wherein the frequency components of the engine cycle frequency have a phase and wherein the method includes the step of identifying the cylinder in which the misfire occurred based on the phase.
Claim 4
Dependent Claim
25 words
The method of claim 1 wherein the frequency components have phases and wherein the algorithm is also applied to the phases of the frequency components.
Claim 5
Dependent Claim
21 words
The method of claim 1 wherein the step of transforming includes the step of applying a DFT to the sampled data.
Claim 6
Dependent Claim
21 words
The method of claim 1 wherein the step of transforming includes the step of applying an FFT to the sampled data.
Claim 7
Independent Claim
164 words
A system for detecting a misfire of a reciprocating internal combustion engine including a plurality of reciprocating components having an engine cycle frequency, N cylinders and a crankshaft, the system comprising: means for generating an electrical signal as a function of crankshaft angular velocity, the electrical signal containing data; means for sampling the data synchronously with crankshaft angular position at a sampling rate to obtain sampled data; means for transforming the sampled data to an equivalent frequency domain spectrum, including frequency components having complex amplitudes at the engine cycle frequency; and means for applying an algorithm to the magnitudes of the frequency components, which algorithm distinguishes between a true misfire and normal cyclic variability which characterizes the combustion process in each cylinder of the engine to thereby obtain a misfire signal and wherein the system further comprises means for shifting the sampled data for (N-1) of the cylinders prior to transformation of the sampled data to identify the cylinder in which the misfire occurred.
Claim 8
Independent Claim
164 words
A system for detecting a misfire of a reciprocating internal combustion engine including a plurality of reciprocating components having an engine cycle frequency, N cylinders and a crankshaft, the system comprising: means for generating an electrical signal as a function of crankshaft angular velocity, the electrical signal containing data; means for sampling the data synchronously with crankshaft angular position at a sampling rate to obtain sampled data; means for transforming the sampled data to an equivalent frequency domain spectrum, including frequency components having complex amplitudes at the engine cycle frequency; and means for applying an algorithm to the magnitudes of the frequency components, which algorithm distinguishes between a true misfire and normal cyclic variability which characterizes the combustion process in each cylinder of the engine to thereby obtain a misfire signal and wherein the system further comprises means for shifting the sampled data for (N-1) of the cylinders prior to transformation of the sampled data to identify the cylinder in which the misfire occurred.
Claim 9
Dependent Claim
39 words
The system as claimed in claim 6 wherein the frequency components of the engine cycle frequency have a phase and wherein the system further includes means for identifying the cylinder in which the misfire occurred based on the phase.
Claim 10
Dependent Claim
27 words
The system as claimed in claim 6 wherein the frequency components have phases and wherein the algorithm is also applied to the phases of the frequency components.
Claim 11
Dependent Claim
23 words
The system as claimed in claim 6 wherein the step of transforming includes the step of applying a DFT to the sampled data.
Claim 12
Dependent Claim
23 words
The system as claimed in claim 6 wherein the step of transforming includes the step of applying an FFT to the sampled data.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-01-22 | 1999-07-24 | 2000-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-01-22 | 2003-07-24 | 2004-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-01-22 | 2007-07-24 | 2008-01-23 | $7700.00 | Window Closed / Lapsed |