Smart washer for pre-load monitoring
First Claim
1. A method of measuring fastener pre-load, the method comprising the steps of:
- placing a clamping force on a pre-load monitor located between a washer face of a fastener and a bearing surface of a fixture arranged to receive a portion of a shank of the fastener;
measuring the fastener pre-load using electrical power generated by the pre-load monitor in response to the clamping force;
broadcasting electrical power data generated by the pre-load monitor; and
calculating the fastener pre-load based upon the broadcast electrical power data;
wherein the pre-load monitor comprises;
an uppermost metallic layer proximate to said washer face of said fastener for receiving said clamping force from said fastener, and said pre-load monitor comprising a lowermost metallic layer proximate to said bearing surface of said fixture; and
, located between the uppermost and lowermost metallic layers,a flexible piezoelectric material arranged to generate an electrical signal to the clamping force produced by the fastener and a radio frequency identifier RFID tag arranged to broadcast the electrical signal.
1 Assignment
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Accused Products
Abstract
A pre-load monitor is arranged for use between a washer face of a fastener and a bearing surface of a fixture arranged to receive a portion of a shank of the fastener. The pre-load monitor, which can be in the form of a washer, includes a piezoelectric generator which generates the electrical power to measure, monitor and report the pre-load. The resulting electrical power produced is proportional to the pre-load and can be stored to provide the energy required to function electrical, electronic and communication circuits included in the washer. Alternatively, the pre-load monitor can be a half- or split ring (or a C-ring) constructed similarly to that of the washer, or the ring can be a two-piece gasket construction that includes an array of the washers.
16 Citations
20 Claims
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1. A method of measuring fastener pre-load, the method comprising the steps of:
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placing a clamping force on a pre-load monitor located between a washer face of a fastener and a bearing surface of a fixture arranged to receive a portion of a shank of the fastener; measuring the fastener pre-load using electrical power generated by the pre-load monitor in response to the clamping force; broadcasting electrical power data generated by the pre-load monitor; and calculating the fastener pre-load based upon the broadcast electrical power data; wherein the pre-load monitor comprises; an uppermost metallic layer proximate to said washer face of said fastener for receiving said clamping force from said fastener, and said pre-load monitor comprising a lowermost metallic layer proximate to said bearing surface of said fixture; and
, located between the uppermost and lowermost metallic layers,a flexible piezoelectric material arranged to generate an electrical signal to the clamping force produced by the fastener and a radio frequency identifier RFID tag arranged to broadcast the electrical signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system of monitoring fastener pre-load, the system comprising:
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a pre-load monitor arranged for use between a washer face of a fastener and a bearing surface of a fixture arranged to receive a portion of a shank of the fastener; the pre-load monitor having; uppermost metallic layer proximate to said washer face of said fastener for receiving said clamping force from said fastener, and said pre-load monitor comprising a lowermost metallic layer proximate to said bearing surface of said fixture; and
, located between the uppermost and lowermost metallic layers,a flexible piezoelectric material arranged to generate electric power in response to a clamping force produced by the fastener; and a radio frequency identifier RFID tag arranged to broadcast an amount of the electric power generated. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification