US4931949A — Method and apparatus for detecting gear defects

Claim 1

Independent Claim 137 words

A method for analyzing a gear system having at least two inter-meshing gears, comprising the steps of: sensing data signals produced by tooth-to-tooth contact in said gear system as said gears revolve, wherein at least some of said data is sensed by shaft encoders and wherein said data signals include signals from at least two top-dead-center pickup means for determining the unique angular orientation of each gear of said gear system; acquiring additional data from said system, including the number of teeth on each gear, the gear system configuration, and the given machine operating state; identifying from the combined data, which includes the additional data and the data signals, the relative angular orientation of the gears in said system and the data generated at said orientation; and analyzing the combined data to compute gear system vibrational characteristics.

Claim 2

Independent Claim 137 words

A method for analyzing a gear system having at least two inter-meshing gears, comprising the steps of: sensing data signals produced by tooth-to-tooth contact in said gear system as said gears revolve, wherein at least some of said data is sensed by shaft encoders and wherein said data signals include signals from at least two top-dead-center pickup means for determining the unique angular orientation of each gear of said gear system; acquiring additional data from said system, including the number of teeth on each gear, the gear system configuration, and the given machine operating state; identifying from the combined data, which includes the additional data and the data signals, the relative angular orientation of the gears in said system and the data generated at said orientation; and analyzing the combined data to compute gear system vibrational characteristics.

Claim 3

Dependent Claim 46 words

The method of claim 1 further comprising the step of: logically combining the signals from said at least two of said top-dead-center pickup means in order to insure that data signals acquisition is initiated at a fixed cycle position of the gears in said gear system.

Claim 4

Independent Claim 132 words

A method for detecting gear defects in a system having at least four gears comprising the steps of: collecting signal data relating to the interaction of a first pair of gears including a first gear and a second gear; collecting signal data from a second pair of gears which includes a third gear which interacts with a fourth gear, said third and said first gear being located on a common shaft; combining the signals collected from said first, second, third and fourth gears together to form a giant hunting tooth pattern; and, detecting the envelope of said giant hunting tooth pattern, wherein the period of the peaks of the envelope which corresponds to the hunting tooth of either pair indicates on which pair of gears a defect is likely to be found.

Claim 5

Independent Claim 132 words

A method for detecting gear defects in a system having at least four gears comprising the steps of: collecting signal data relating to the interaction of a first pair of gears including a first gear and a second gear; collecting signal data from a second pair of gears which includes a third gear which interacts with a fourth gear, said third and said first gear being located on a common shaft; combining the signals collected from said first, second, third and fourth gears together to form a giant hunting tooth pattern; and, detecting the envelope of said giant hunting tooth pattern, wherein the period of the peaks of the envelope which corresponds to the hunting tooth of either pair indicates on which pair of gears a defect is likely to be found.

Claim 6

Independent Claim 86 words

A method of analyzing a vibrational signal generated by the inter-meshing of at least two gears, said analysis comprising the steps of: sensing said vibrational signal at least long enough for each tooth of said gears to mate once before repeating; stacking at least two of said signals so that identical tooth-to-tooth matings are superimposed on each other; and determining which tooth-to-tooth interactions have anomalous patterns, wherein the tooth-to-tooth interactions which have anomalous patterns determined above are likely to include a gear having a defect therein.

Claim 7

Independent Claim 86 words

A method of analyzing a vibrational signal generated by the inter-meshing of at least two gears, said analysis comprising the steps of: sensing said vibrational signal at least long enough for each tooth of said gears to mate once before repeating; stacking at least two of said signals so that identical tooth-to-tooth matings are superimposed on each other; and determining which tooth-to-tooth interactions have anomalous patterns, wherein the tooth-to-tooth interactions which have anomalous patterns determined above are likely to include a gear having a defect therein.

Claim 8

Dependent Claim 30 words

The method of claim 4 further comprises the step of: detecting the envelope of said stacked signals to identify the peak thereof which are likely to indicate teeth containing defects.

Claim 9

Independent Claim 108 words

A system for analyzing a vibrational signal generated by at least two inter-meshing gears, said system comprising: a vibrational signal pickup mountable on an object; an interface connected to said pickup; an analog signal processor means connected to said interface for conditioning and converting said signal to a digital signal; a computer means connected to said analog signal processor means for recording the digital signal over at least one hunting tooth period of said gears and stacking at least two of said signals so that tooth-by-tooth interactions are superimposed on each tooth; and, an output means for reporting the results of the operations performed by said computer means.

Claim 10

Independent Claim 108 words

A system for analyzing a vibrational signal generated by at least two inter-meshing gears, said system comprising: a vibrational signal pickup mountable on an object; an interface connected to said pickup; an analog signal processor means connected to said interface for conditioning and converting said signal to a digital signal; a computer means connected to said analog signal processor means for recording the digital signal over at least one hunting tooth period of said gears and stacking at least two of said signals so that tooth-by-tooth interactions are superimposed on each tooth; and, an output means for reporting the results of the operations performed by said computer means.

Claim 11

Dependent Claim 51 words

The system of claim 6 further comprising of: a shaft encoder connected to said rotating object to produce an output signal each time said object rotates; and a pulse multiplier means to change the number of pulses produced by said shaft encoder to a rate optimally compatible with said computer means.

Claim 12

Dependent Claim 13 words

The system of claim 6 wherein said output means comprises a CRT monitor.

Claim 13

Dependent Claim 26 words

The system of claim 8 wherein said output means includes an alarm to indicate when said signal analyzed by said computer means exceeds a pre-determined threshold.

Claim 14

Independent Claim 75 words

A method of detecting the location of a defect in a gear system of at least two gears, said method comprising the steps of: generating a series of hunting tooth patterns of the tooth-by-tooth interactions of at least two gears; and, comparing the hunting tooth patterns generated over time against each other to locate local gear defects, wherein said hunting tooth patterns are as long as it takes for each tooth-by-tooth interaction to repeat itself.

Claim 15

Independent Claim 75 words

A method of detecting the location of a defect in a gear system of at least two gears, said method comprising the steps of: generating a series of hunting tooth patterns of the tooth-by-tooth interactions of at least two gears; and, comparing the hunting tooth patterns generated over time against each other to locate local gear defects, wherein said hunting tooth patterns are as long as it takes for each tooth-by-tooth interaction to repeat itself.

Claim 16

Independent Claim 88 words

A method for analyzing a vibrational signal generated by at least two inter-meshing gears, comprising the steps of: detecting said vibrational signal; high frequency band pass filtering said vibrational signal; detecting the envelope of said high frequency band pass filtered signal to produce a signal representative of the low frequency components of said vibrational signal; and, stacking at least two of said envelopes so that vibrations of the same tooth are superimposed on each other, wherein the stacking of said envelopes produces an indication of gear tooth anomalies.

Claim 17

Independent Claim 88 words

A method for analyzing a vibrational signal generated by at least two inter-meshing gears, comprising the steps of: detecting said vibrational signal; high frequency band pass filtering said vibrational signal; detecting the envelope of said high frequency band pass filtered signal to produce a signal representative of the low frequency components of said vibrational signal; and, stacking at least two of said envelopes so that vibrations of the same tooth are superimposed on each other, wherein the stacking of said envelopes produces an indication of gear tooth anomalies.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-06-04	1993-12-04	1994-06-05	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-06-04	1997-12-04	1998-06-05	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-06-04	2001-12-04	2002-06-05	$7700.00	Window Closed / Lapsed

Method and apparatus for detecting gear defects

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