Stress wave sensor
First Claim
1. A stress wave sensor in communication with an electronic assembly, said sensor comprising:
- a transducing element generating a primary resonant frequency;
a charge converter in communication with said transducing element; and
a high pass filter in communication with said charge converter for attenuating received signals that fall below, a selected frequency;
wherein said sensor having a resonant gain of approximately 30 db at its primary resonant frequency to allow for selective amplification of stress waves;
wherein said sensor having a resonant output of a specific amplitude, said resonant output decaying to half amplitude by a predetermined number of cycles.
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Accused Products
Abstract
A sensor is disclosed specifically for detecting stress waves for use in a stress wave analysis system. The stress waves-are preferably detected in a narrow frequency range of 35-40KHz. At this range, stress waves from friction and impact sources typically propagate through machine structures at detectable amplitudes. In order to maximize the signal to noise ratio of stress waves, relative to background noise and vibration, the sensor of the present invention is designed and calibrated with a frequency response and damping features that are specifically tailored for stress wave analysis. The sensor preferably satisfies the following three criteria: (a) has a resonant gain of approximately 30 db, at its primary resonant frequency, to assure adequate selective amplification of stress waves; (b) provide a total energy content of the Resonant Energy Integral within a specified tolerance band and which can be measurable using standard test equipment and fixtures to produce calibration data that is traceable to recognized standards; and (c) have its resonant peak amplitude output decay to half amplitude by five cycles, and be down to no more than twenty percent of the initial response in the number of cycles that occur during the time period that corresponds to the corner frequency of a low pass filter.
32 Citations
22 Claims
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1. A stress wave sensor in communication with an electronic assembly, said sensor comprising:
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a transducing element generating a primary resonant frequency;
a charge converter in communication with said transducing element; and
a high pass filter in communication with said charge converter for attenuating received signals that fall below, a selected frequency;
wherein said sensor having a resonant gain of approximately 30 db at its primary resonant frequency to allow for selective amplification of stress waves;
wherein said sensor having a resonant output of a specific amplitude, said resonant output decaying to half amplitude by a predetermined number of cycles. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 14, 15, 16)
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11. A stress wave sensor in communication with an electronic assembly used for stress wave analysis, said electronic assembly including a band pass filter, said sensor comprising:
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a transducing element generating a primary resonant frequency approximately between 35 KHz to 40 KHz;
a charge converter in communication with said transducing element; and
a high pass filter in communication with said charge converter for attenuating received signals that fall below a frequency of approximately 20 KHz;
wherein said sensor having a resonant gain of approximately 30 db at its primary resonant frequency to allow for selective amplification of stress waves;
wherein said sensor having a resonant output of a specific amplitude, said resonant output decaying to half amplitude by a predetermined number of cycles. - View Dependent Claims (12, 13, 17)
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18. A stress wave sensor in communication with an electronic assembly, said sensor comprising:
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a transducing element generating a primary resonant frequency;
a charge converter in communication with said transducing element; and
a high pass filter in communication with said charge converter for attenuating received signals that fall below a selected frequency;
wherein said sensor having a resonant gain of approximately 30 db at its primary resonant frequency and a resonant output of a specific amplitude, said resonant output decaying to approximately half amplitude by a predetermined number of cycles.
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19. A stress wave senor in communication with an electronic assembly, said senor comprising;
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a transducing element generating a primary resonant frequency;
a charge converter in communication with said transducing element; and
a high pass or band pass filter in communication with said charge converter for attenuating received signals that fall below a selected frequency prior to any amplification of the received signals to prevent saturation of any signal conditioning amplification outside of the sensor;
wherein the received signals includes a low frequency component and a high frequency component;
wherein said high pass or band pass filter attenuates said low frequency component so that the high frequency component represents a significant percentage of the filtered signal prior to any subsequent amplification outside of the sensor.- View Dependent Claims (20, 21, 22)
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Specification