Smart washer for pre-load monitoring

Patent metadata

Field	Value
Publication number	US-9964135-B2
Application number	US-201514971670-A
Country	US
Kind code	B2
Filing date	Dec 16, 2015
Priority date	Dec 16, 2015
Publication date	May 8, 2018
Grant date	May 8, 2018

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.

First claim

What is claimed:

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.

2. A method according to claim 1 wherein the placing step comprises applying torque to said fastener with a wrench having a processor and a sensor interface in communication with the pre-load monitor and a memory for receiving and storing electrical power data generated by the pre-load monitor.

3. A method according to claim 1 further comprising the step of monitoring the fastener pre-load.

4. A method according to claim 3 further comprising the monitoring step including the sub-steps of:
stimulating a portion of the pre-load monitor lying adjacent to the flexible piezoelectric material;
detecting a deformation of the flexible piezoelectric material in response to the stimulating step; and
measuring an amount of the deformation;
wherein the stimulating step occurs by way of a voltage source provided by a power supply internal to or external of the pre-load monitor.

5. A method according to claim 4 wherein the amount of deformation is determined by way of a load cell.

6. A method according to claim 3 wherein the monitoring step includes the sub-step of using a wrench adapted to apply torque to said fastener, said wrench having a processor and a sensor interface in communication with the pre-load monitor and a memory for receiving and storing electrical power data generated by the pre-load monitor.

7. A method according to claim 1 further comprising the step of powering the broadcasting step with a portion of the electrical power generated.

8. A method according to claim 1 further comprising the step of storing within the pre-load monitor a portion of the electrical power generated.

9. A method according to claim 1 further comprising the step of adjusting the fastener pre-load to account for a temperature gradient between an assembly environment and an operating environment of the fixture.

10. A system of monitoring fastener pre-load, the system comprising:
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.

11. A system according to claim 10 wherein the pre-load monitor is in the form of a circular washer.

12. A system according to claim 11 further comprising a gasket material arranged about the washer.

13. A system according to claim 10 further comprising a wrench adapted to apply torque to a fastener, said wrench including a processor and a sensor interface in communication with the pre-load monitor and a memory for receiving and storing electrical power data generated by the pre-load monitor.

14. A system according to claim 13 further comprising the wrench including communication hardware.

15. A system according to claim 14 further comprising the communication hardware arranged to retrieve data from a remote database and write data to the remote database.

16. A system according to claim 14 further comprising a protective device in communication with the wrench.

17. A system according to claim 16 wherein the protective device is selected from the group consisting of an operator headset, an operator earpiece, operator eyewear, and an operator glove.

18. A system according to claim 10 further comprising the pre-load monitor including:
a stimulation layer lying adjacent to the flexible piezoelectric material and in communication with a power supply; and
a detection layer lying adjacent to the flexible piezoelectric material and arranged to detect a deformation of the flexible piezoelectric material.

19. A system according to claim 18 further comprising the detection layer including a load cell.

20. A system according to claim 10 further comprising the washer including an energy storage layer in communication with the flexible piezoelectric material, the energy storage layer including a least one of a battery and a capacitor.

Assignees

• Cameron Int Corp

Inventors

• Jaffrey Andrew
• McNaney Andy

Classifications

• F16B31/028 Primary

  with a load-indicating washer or washer assembly · CPC title