Looseness detection sensor and how to identify loose bolts

Patent metadata

Field	Value
Publication number	US-12031856-B2
Application number	US-201917774426-A
Country	US
Kind code	B2
Filing date	Nov 15, 2019
Priority date	Nov 15, 2019
Publication date	Jul 9, 2024
Grant date	Jul 9, 2024

Abstract

A sensor for detecting looseness of a plurality of bolts and nuts fixing parts includes: a non-conductive film attached to a surface of the part, which is one of the parts, including holes H from which the bolts are inserted; and a conductive film attached to the non-conductive film, configured to receive supply of a high-frequency signal, and having a same planar shape as that of the non-conductive film, wherein the planar shape is a shape in which a resonance frequency of the high-frequency signal confined in the non-conductive film is different according to a position of a loosened bolt, and the planar shape of the conductive film is a shape in which a distance between a bolt and an end portion of the conductive film is different for each of the plurality of bolts.

First claim

The invention claimed is:

1. A looseness detection sensor for detecting looseness of a plurality of bolts and nuts fixing two or more parts to each other, comprising:
a non-conductive film attached to a surface of one of the parts including holes from which the bolts are inserted; and
a conductive film attached to the non-conductive film, configured to receive supply of a high-frequency signal, and having a same planar shape as that of the non-conductive film,
wherein the planar shape is a shape in which a resonance frequency of the high-frequency signal confined in the non-conductive film is different according to a position of a loosened bolt.

2. The looseness detection sensor according to claim 1 , wherein the planar shape is a shape in which a distance between a bolt and an end portion of the conductive film is different for each of the plurality of bolts.

3. The looseness detection sensor according to claim 1 , wherein the planar shape is a shape in which a distance between a bolt and a supply point to which the high-frequency signal is supplied is different for each of the plurality of bolts.

4. A method for specifying a loosened bolt, performed by a looseness detection apparatus for detecting looseness of a plurality of bolts and nuts fixing two or more parts to each other, comprising:
a high-frequency sweep step of sweeping a high-frequency signal at a frequency in a predetermined range and supplying the signal to a conductive film attached to a non-conductive film attached to a surface of one of the parts including holes from which the bolts are inserted;
a resonance frequency detecting step of detecting a resonance frequency of the part to which the conductive film is attached;
a resonance frequency recording step of recording a resonance frequency detected in the resonance frequency detecting step;
a determining step of comparing the resonance frequency detected in the resonance frequency detecting step and a previous resonance frequency, and determining whether or not the bolts are loosened based on whether or not there is a new resonance frequency or an amount of change in a resonance frequency; and
a specifying step of, in a case in which it is determined in the determining step that there is a loosened bolt, specifying the loosened bolt based on whether or not there is a new resonance frequency or an amount of change in a resonance frequency.

Assignees

• Nippon Telegraph & Telephone

Inventors

• Matsunaga Eri
• Minotani Tadashi
• Nakamura Masahito
• Tsuda Masayuki

Classifications

• G01N22/00

  Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more (G01N3/00 - G01N17/00, G01N24/00 take precedence) · CPC title

• G01H13/00 Primary

  Measuring resonant frequency · CPC title