Absolute compression test
First Claim
1. A method of measuring the absolute compression of each cylinder in an internal combustion engine having known ideal performance parameters, comprising the steps of:
- sensing the absolute angular speed of the crankshaft of an engine during at least one noncombustive engine cycle;
relating particular subcyclic absolute speed variations to particular cylinders;
calculating the work of expansion and the work of compression for each cylinder;
identifying as a faulted cylinder each cylinder for which the compression work and the expansion work are each less than the work of compression and expansion, respectively, which would be performed by an ideal cylinder;
firstly correcting, if more than one faulted cylinder is identified, for the apparent effects of the diminished work of each faulted cylinder on the calculated work of each of the other faulted cylinders;
secondly correcting for the apparent effects of the diminished work of each faulted cylinder on the calculated work of each of the nonfaulted cylinders; and
computing the absolute compression pressure for each cylinder during said cycle based on said corrected work calculations.
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Accused Products
Abstract
A method and apparatus for determining the absolute compression pressure of each cylinder in an internal combustion engine is disclosed. The technique involves analyzing the changes in engine kinetic energy in order to calculate both the work of compression and expansion of each cylinder in a multi-cylinder engine typically during a decelerating engine cycle. Speed data is obtained and the work associated with the compression and expansion process for each cylinder is calculated and compared to the compression and expansion data of a good engine which is stored in computer memory. If a compression fault is present, it can be detected because that cylinder will display a decrease in both the work of compression and expansion. Once a faulted cylinder has been identified, the magnitude of the fault can be calculated and normalized and the compression pressure of each cylinder calculated and displayed.
27 Citations
17 Claims
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1. A method of measuring the absolute compression of each cylinder in an internal combustion engine having known ideal performance parameters, comprising the steps of:
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sensing the absolute angular speed of the crankshaft of an engine during at least one noncombustive engine cycle; relating particular subcyclic absolute speed variations to particular cylinders; calculating the work of expansion and the work of compression for each cylinder; identifying as a faulted cylinder each cylinder for which the compression work and the expansion work are each less than the work of compression and expansion, respectively, which would be performed by an ideal cylinder; firstly correcting, if more than one faulted cylinder is identified, for the apparent effects of the diminished work of each faulted cylinder on the calculated work of each of the other faulted cylinders; secondly correcting for the apparent effects of the diminished work of each faulted cylinder on the calculated work of each of the nonfaulted cylinders; and computing the absolute compression pressure for each cylinder during said cycle based on said corrected work calculations. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. Apparatus for measuring the absolute compression of each cylinder in an internal combustion engine having known ideal performance parameters, comprising:
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first sensing means adapted to be disposed for a response to the magnitude of an engine parameter, the magnitude of which fluctuates in conjunction with the cylinder-related absolute angular velocity including subcylic excursions in engine angular velocity as a consequence of the compression and expansion strokes of the individual pistons, said sensing means providing a corresponding engine angular velocity signal; second sensing means adapted to be disposed for a response to the stroke of a particular engine cylinder piston through a reference piston position as manifested by the cyclic displacement of an engine component member having a cyclic function directly related to the piston stroke of said particular cylinder piston for providing a series of sensed, periodic cylinder identification (CID) signal pulses representative of said stroke through said reference piston position to mark engine cycles; data acquisition means, responsive to said engine angular velocity signal and to said CID signal pulses, for registering said angular velocity signal with respect to said CID signal pulses to provide a registered angular velocity signal for each engine cycle; and signal processing means, responsive to said registered angular velocity signal from said data acquisition means over at least one engine cycle, for providing signal manifestations indicative of the work of compression and the work of expansion for each cylinder, said signal processing means comparing the magnitudes of said work signal manifestations to stored signals having magnitudes indicative of the work of an ideal cylinder and for providing cylinder fault signals identifying those cylinders as faulted cylinders for which said comparison indicates that the work of compression and expansion are each less than ideal, said signal processing means counting said fault signals to determine the number of faulted cylinders detected and, if more than one faulted cylinder is detected, providing for each faulted cylinder work signal manifestations corrected for the apparent effects of the diminished work of each faulted cylinder, said signal processing means providing for each nonfaulted cylinder work signal manifestations corrected for the apparent effects of the diminished work of each faulted cylinder, said signal processing means providing pressure signals having magnitudes indicative of the absolute compression pressure for each cylinder. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification