Method and apparatus for producing fault signals responsive to malfunctions in individual engine cylinders
First Claim
1. An apparatus for detecting malfunctions in individual cylinders of an internal combustion engine having a rotating member driven by a plurality of cylinders, comprising:
- sensor means for measuring the time between successive angular positions as said member rotates through at least one engine cycle and producing a plurality of period signals responsive respectively to said measured time intervals, wherein each engine cylinder has an equal number of said angular positions associated therewith and said member makes at least one rotation per engine cycle;
deviation means for receiving said period signals and producing a deviation signal for each engine cylinder, said deviation signal being responsive to a difference between said period signals of a respective cylinder;
average means for receiving said deviation signals and producing an average signal responsive to an average of said deviation signals; and
comparator means for receiving said deviation and average signals, comparing each deviation signal to said average signal, and producing respective fault signals in response to individual deviation signals differing from said average signal by more than a first threshold.
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Abstract
Dynamic engine diagnostic devices are useful for detecting engine faults such as a misfiring cylinder during normal engine operation. Identification of the particular cylinder having the fault enables repairs to be made more efficiently. In the subject application, an apparatus is provided for detecting malfunctions in individual cylinders of an internal combustion engine having a rotating member driven by a plurality of cylinders. The apparatus includes a sensor for measuring the time between successive angular positions as the member rotates through at least one engine cycle and producing a plurality of period signals responsive respectively to the measured time intervals. Each engine cylinder has an equal number of the angular positions associated therewith, and the member makes one rotation per engine cycle. A deviation circuit receives the period signals and produces a deviation signal for each engine cylinder. Each deviation signal is responsive to a difference between period signals of a respective cylinder. An averaging circuit receives the deviation signals and produces an average signal responsive to an average of the deviation signals. A comparator receives the deviation and average signals, compares each deviation signal to the average signal, and produces respective fault signals in response to individual deviation signals differing from the average signal by more than a first threshold.
80 Citations
18 Claims
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1. An apparatus for detecting malfunctions in individual cylinders of an internal combustion engine having a rotating member driven by a plurality of cylinders, comprising:
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sensor means for measuring the time between successive angular positions as said member rotates through at least one engine cycle and producing a plurality of period signals responsive respectively to said measured time intervals, wherein each engine cylinder has an equal number of said angular positions associated therewith and said member makes at least one rotation per engine cycle; deviation means for receiving said period signals and producing a deviation signal for each engine cylinder, said deviation signal being responsive to a difference between said period signals of a respective cylinder; average means for receiving said deviation signals and producing an average signal responsive to an average of said deviation signals; and comparator means for receiving said deviation and average signals, comparing each deviation signal to said average signal, and producing respective fault signals in response to individual deviation signals differing from said average signal by more than a first threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for detecting malfunctions in individual cylinders of an internal combustion engine having a rotating member driven by a plurality of said cylinders, comprising:
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sensor means for measuring the time between successive angular positions as said member rotates through at least one engine cycle and producing a plurality of period signals responsive respectively to said measured time intervals, wherein each engine cylinder has an equal number of said angular positions associated therewith and said member makes at least one rotation per engine cycle; deviation means for receiving said period signals and producing a deviation signal for each engine cylinder, said deviation signal being responsive to a difference between said period signals of a respective cylinder; average means for receiving said deviation signals and producing an average signal responsive to an average of said deviation signals; and comparator means for receiving said deviation and average signals, determining if said average signal is less than, equal to, or greater than zero, producing respective fault signals in response to said deviation signals being less than a third preselected threshold if said average signal is less than zero, and producing respective fault signals in response to individual deviation signals being less than said average signal by more than a first threshold if said average signal is greater than or equal to zero.
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10. A method for detecting malfunctions in individual cylinders of an internal combustion engine having rotating member driven by a plurality of cylinders, comprising the steps of:
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sensing the time between successive angular positions as said member rotates through at least one engine cycle and producing a plurality of period signals responsive respectively to said measured time intervals, wherein each engine cylinder has an equal number of said angular positions associated therewith and said member makes at least one rotation per engine cycle; producing a deviation signal for each engine cylinder, said deviation signal being responsive to a difference between said period signals of a respective cylinder; producing an average signal responsive to an average of said deviation signals; and comparing each deviation signal to said average signal and producing respective fault signals in response to individual deviation signals differing from said average signal by more than a first threshold. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. An apparatus for detecting malfunctions in individual cylinders of an internal combustion engine having a rotating member driven by a plurality of cylinders, comprising:
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sensor means for measuring the time between successive angular positions as said member rotates through at least one engine cycle and for producing a plurality of period signals responsive respectively to said measured time intervals, wherein each engine cylinder has an equal number of said angular position associated therewith and the member makes at least one rotation per engine cycle; deviation means for receiving said period signals and producing a deviation signal for each engine cylinder in response to the maximum decrease between period signals for a respective engine cylinder; average means for receiving said deviation signals and producing an average signal responsive to an average of said deviation signals; and comparator means for receiving said average and deviation signals, comparing each deviation signal to said average signal, and producing respective fault signals in response to individual deviation signals differing from said average signal by more than a first threshold.
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Specification