Patent US6330460B1 successfully refreshed from Google Patents.
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EP0442687A2
Expired / Lapsed
EP
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Method of and apparatus for detecting misfire
Assignee: ZF International UK Ltd
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Filing: 1991-02-12
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Granted: —
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Expires: 2011-02-12
Abstract
Abstract In order to detect misfire in an internal combustion engine, engine speed is determined by measuring (13) the time of passage of a crankshaft disc (10) from a first position (0, 1, 2) to a second position (1, 2, 0) during every revolution. A detection circuit (14) takes the reciprocal of the measured times of passage to form a series of engine speeds and forms the difference between consecutive engine speeds. These differences are compared (16) with a threshold to signal a misfire when the threshold is exceeded.
Inventors
- 👤 Michael Holmes
- 👤 Benjamin James Bradshaw
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 20:11
CPC Classifications
G; G01; G01M; G01M15/00; G01M15/04; G01M15/11
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
76 words
An apparatus for detecting misfire in an internal combustion engine, comprising measuring means for making measurements representing engine speeds, means for determining variations as the differences between measurements, and a comparator for comparing the variations with a threshold level and for signalling a misfire when the threshold level is exceeded, characterised in that the measuring means (10, 11) is arranged to make the measurements between the same points of cylinder and piston cycles of the engine.
Claim 2
Dependent Claim
68 words
An apparatus as claimed in Claim 1, characterised in that the measuring means (10, 11) is arranged to detect first and second points in each of the cylinder and piston cycles and the determining means (13, 14) is arranged to form the time intervals between the detection of the first and second points and to form the difference between the reciprocals of the time intervals as the variations.
Claim 3
Dependent Claim
29 words
An apparatus as claimed in Claim 2, characterised in that the comparator (16) is arranged to compare the variations with a fixed threshold level representing a fixed speed variation.
Claim 4
Independent Claim
76 words
An apparatus as claimed in any one of the preceding claims for use with an internal combustion engine having a plurality of pistons and cylinders, characterised in that the measuring means (10, 11) is arranged to make a series of measurements between the same points of the cycles of a first of the pistons and cylinders and the determining means (13, 14) is arranged to determine the variations between consecutive measurements of the series of measurements.
Claim 5
Dependent Claim
49 words
An apparatus as claimed in Claim 4, characterised in that the measuring means (10, 11) is arranged to make respective series of measurements corresponding to respective pistons and cylinders and the determining means (13, 14) is arranged to determine the variations between consecutive measurements of each of the series.
Claim 6
Dependent Claim
44 words
An apparatus as claimed in Claim 5, characterised in that the measuring means (10, 11) comprises a transducer arranged to detect when an engine output shaft is at a respective first position and a respective second position for each of the cylinders and pistons.
Claim 7
Dependent Claim
120 words
An apparatus as claimed in Claim 1 for use with an internal combustion engine having a plurality of pistons and cylinders, characterised in that the measuring means (10, 11) is arranged to make the measurements between a respective first point and a respective second point of each cycle of each piston and cylinder and in that the determining means (13, 14) is arranged to determine the variations by comparing each xth, (x+1)th, (x+a)th, and (x+a+1)th measurements, where a is the number of combustion events per period of a systematic measurement fluctuation or a multiple thereof, the xth and (x+a)th measurements are of opposite sign in the comparison, and the (x+1)th and (x+a+1)th measurements are of opposite sign in the comparison.
Claim 8
Dependent Claim
30 words
An apparatus as claimed in Claim 7, characterised in that a is equal to the number of combustion events per revolution of an engine output shaft or a multiple thereof.
Claim 9
Dependent Claim
31 words
An apparatus as claimed in Claim 7 or 8, characterised in that the determining means (13, 14) is arranged to form each variation as: T(x)-T(x+1)-T(x+a)+T(x+a+1) where T(i) is the ith measurement.
Claim 10
Dependent Claim
98 words
An apparatus as claimed in Claim 1 for use with an n cylinder internal combustion engine, where n is greater than 1, characterised in that the measuring means (10,11) is arranged to make the measurements between a respective first point and a respective second point of each cycle of each piston and cylinder and in that the determining means (13, 14) is arranged to determine the variations as the difference between sums (T(x)+T(x+n-1)) and (T(y)+T(z)), where T(x) is the xth measurement, T(x+n-1) is the (x+n-1)th measurement, and T(y) and T(z) are measurements between the xth and (x+n-1)th measurements.
Claim 11
Dependent Claim
23 words
An apparatus as claimed in Claim 10, characterised in that the measurements T(y) and T(z) are midway between the xth and (x+n-1)th measurements.
Claim 12
Dependent Claim
32 words
An apparatus as claimed in Claim 11 for a four-stroke cycle engine having an even number of cylinders, characterised in that the measurements T(y) and T(z) are the (x+(n/2)-1)th and (x+(n/2))th measurements.
Claim 13
Dependent Claim
39 words
An apparatus as claimed in Claim 11 for a four-stroke cycle engine having an odd number of cylinders, characterised in that the measurement T(y) is the (x+((n-1)/2))th measurement and the measurement T(z) is the (x+((n-1)/2)-1)th, (x+((n-1)/2))th, or (x+((n-1)/2)+1)th measurement.
Claim 14
Dependent Claim
159 words
An apparatus as claimed in Claim 1 for an n cylinder internal combustion engine, where n is greater than 1, characterised in that the measuring means (10, 11) is arranged to make the measurements between a respective first point and a respective second point of each cycle of each piston and cylinder and in that the determining means (13, 14) is arranged to determine the variations in accordance with at least two of the following constraints: (i) the measurements are compared in the determining means (13, 14) as pairs with the measurements of each pair being measured over the same range of positions of an output shaft of the engine; (ii) the xth measurement is compared in the determining means (13, 14) with the (x+p)th the measurement, where p is an even integer; (iii) at least three measurements are compared in the determining means (13, 14), the at least three measurements including an xth measurement and an (x+n-1)th measurement.
Claim 15
Independent Claim
54 words
A method of detecting misfire in an internal combustion engine, comprising the steps of making measurements representing engine speeds between the same points of cylinder and piston cycles of the engine, determining variations as the difference between measurements, comparing the variations with a threshold level, and signalling a misfire when the threshold is exceeded.
Claim 16
Dependent Claim
61 words
A method as claimed in Claim 15, characterised in that the measuring step comprises detecting first and second points in each of the cylinder and piston cycles and in that the determining step comprises forming the time intervals between the detection of the first and second points and forming the difference between the reciprocals of the time intervals as the variations.
Claim 17
Dependent Claim
27 words
A method as claimed in Claim 16, characterised in that the comparing step comprises comparing the variations with a fixed threshold level representing a fixed speed variation.
Claim 18
Independent Claim
69 words
A method as claimed in any one of Claims 15 to 17 for an internal combustion engine having a plurality of pistons and cylinders, characterised in that the measuring step comprises making a series of measurements between the same points of the cycles of a first of the pistons and cylinders and in that the determining step comprises determining the variations between consecutive measurements of the series of measurements.
Claim 19
Dependent Claim
43 words
A method as claimed in Claim 18, characterised in that the measuring step comprises making respective series of measurements corresponding to respective pistons and cylinders and in that the determining step comprises determining the variations between consecutive measurements of each of the series.
Claim 20
Dependent Claim
38 words
A method as claimed in Claim 19, characterised in that the measuring step comprises detecting when an engine output shaft is at a respective first position and a respective second position for each of the cylinders and pistons.
Claim 21
Dependent Claim
110 words
A method as claimed in Claim 15 for an internal combustion engine having a plurality of pistons and cylinders, characterised in that the measuring step comprises making the measurements between a respective first point and a respective second point of each cycle of each piston and cylinder and in that the determining step comprises determining the variations by comparing each xth, (x+1)th, (x+a)th, and (x+a+1)th measurements, where a is the number of combustion events per period of a systematic measurement fluctuation or a multiple thereof, the xth and (x+a)th measurements are of opposite sign in the comparison, and the (x+1)th and (x+a+1)th measurements are of opposite sign in the comparison.
Claim 22
Dependent Claim
30 words
A method as claimed in Claim 21, characterised in that a is equal to the number of combustion events per revolution of an engine output shaft or a multiple thereof.
Claim 23
Dependent Claim
26 words
A method as claimed in Claim 21 or 22, characterised in that the determining step determines each variation as: T(x)-T(x+1)-T(x+a)+T(x+a+1) where T(i) is the ith measurement.
Claim 24
Dependent Claim
88 words
A method as claimed in Claim 15 for an n cylinder internal combustion engine, where n is greater than 1, characterised in that the measuring step comprises making the measurements between a respective first point and a respective second point of each cycle of each piston and cylinder and in that the determining step determines the variations as the difference between sums (T(x)+T(x+n-1)) and (T(y)+T(z)), where T(x) is the xth measurement, T(x+n-1) is the (x+n-1)th measurement, and T(y) and T(z) are measurements between the xth and (x+n-1)th measurements.
Claim 25
Dependent Claim
23 words
A method as claimed in Claim 24, characterised in that the measurement T(y) and T(z) are midway between the xth and (x+n-1)th measurements.
Claim 26
Dependent Claim
32 words
A method as claimed in Claim 25 for a four-stroke cycle engine having an even number of cylinders, characterised in that the measurements T(y) and T(z) are the (x+(n/2)-1)th and (x+(n/2))th measurements.
Claim 27
Dependent Claim
39 words
A method as claimed in Claim 25 for a four-stroke cycle engine having an odd number of cylinders, characterised in that the measurement T(y) is the (x+((n-1)/2))th measurement and the measurement T(z) is the (x+((n-1)/2)-1)th, (x+((n-1)/2))th, or (x+((n-1)/2)+1)th measurement.
Claim 28
Dependent Claim
127 words
A method as claimed in Claim 15 for an n cylinder internal combustion engine, where n is greater than 1, characterised in that the measuring step comprises making the measurements between a respective first point and a respective second point of each cycle of each piston and cylinder and in that the determining step comprises determining the variations in accordance with at least two of the following constraints: (i) the measurements are compared as pairs with the measurements of each pair being measured over the same range of positions of an output shaft of the engine; (ii) the xth measurement is compared with the (x+p)th measurement, where p is an even integer; (iii) at least three measurements are compared including an xth measurement and an (x+n-1)th measurement.
References Cited (Backward Citations)
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