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JP-7854679-B2 - Leak inspection method and leak inspection apparatus

JP7854679B2JP 7854679 B2JP7854679 B2JP 7854679B2JP-7854679-B2

Inventors

  • 安倍 悠朔
  • 松田 佑
  • 高橋 咲貴子
  • 松江 朋彦

Assignees

  • 学校法人早稲田大学
  • タカハタプレシジョン株式会社

Dates

Publication Date
20260507
Application Date
20230626

Claims (4)

  1. A leak inspection device for inspecting air leaks in an object under inspection, which has an internal space that is reduced to a predetermined vacuum and airtightly sealed, in a bright environment, An excitation light source is provided that projects excitation light from outside the internal space onto a pressure-sensitive paint, which is applied to a white plate and placed within the internal space, and whose luminescence intensity changes with changes in the oxygen concentration within the internal space. A light receiving means for receiving light emitted from the pressure-sensitive paint, A measuring means for measuring decay time from the time waveform of the emission intensity of the received light, The system includes a notification means that determines that there is an air leak and notifies the system if the time it takes for the luminescence intensity represented by equation (1) to decrease to 37% of the maximum value during the decay time is less than a predetermined threshold, A leak detection device characterized by the following: I(t)=I 0 ×exp(-t/τ) (1) Here, I(t) is the emission intensity at time t, I0 is the emission intensity when the excitation light disappears, and τ is the emission lifetime.
  2. The excitation light is pulsed and the excitation wavelength of the pressure-sensitive paint includes a wavelength range of 400 nm to 700 nm. The leak inspection device according to feature 1.
  3. The pressure-sensitive paint contains a ruthenium complex. The leak inspection device according to claim 1 or 2.
  4. A leak inspection method for inspecting air leaks in an object under inspection, which has an internal space that is reduced to a predetermined vacuum and airtightly sealed, in a bright environment, A light projection step involves projecting excitation light from outside the internal space onto a pressure-sensitive paint, which is applied to a white plate and placed within the internal space, and whose luminescence intensity changes with changes in the oxygen concentration within the internal space. A light receiving step that receives light emitted from the pressure-sensitive paint, A measurement step of measuring the decay time from the time waveform of the emission intensity of the received light, The notification step includes determining that there is an air leak and notifying the relevant party if the time it takes for the luminescence intensity represented by equation (1) to decrease to 37% of the maximum value during the decay time is less than a predetermined threshold, A leak testing method characterized by the following: I(t)=I 0 ×exp(-t/τ) (1) Here, I(t) is the emission intensity at time t, I0 is the emission intensity when the excitation light disappears, and τ is the emission lifetime.

Description

This invention relates to a leak detection method and a leak detection apparatus. An optical oxygen concentration measurement method is known (Patent Document 1), which involves using a combination of an emissive layer that emits light upon excitation light and an absorbing dye layer whose optical absorption spectrum changes depending on the degree of binding with oxygen molecules, which varies according to the oxygen concentration. The method measures the oxygen concentration by detecting the light intensity of the output light, which changes based on the partial absorption of incident light (either light used to emit light from the emissive layer) or light emitted from the emissive layer as it passes through the absorbing dye layer. A fluid measurement method is also known that simultaneously performs a pressure field measurement step, in which the pressure distribution on the surface of an object in contact with a fluid is optically measured using a pressure-sensitive paint, and a velocity field measurement step, in which visible particles are scattered in the fluid and the spatial behavior of the fluid is optically measured, thereby obtaining information on the pressure field and velocity field for the same event as information correlated in the time direction (Patent Document 2). Japanese Patent Publication No. 2004-28650Japanese Patent Publication No. 2013-79878 This is a block diagram showing the functional configuration of the leak inspection device according to this embodiment.This is a schematic diagram illustrating an example of a leak inspection device according to this embodiment.This flowchart schematically illustrates the leak testing procedure according to this embodiment.This diagram conceptually illustrates the attenuation of luminescence intensity.This figure shows an example of measurement results for luminescence lifetime under vacuum and atmospheric pressure.This figure shows an example of measurement results for the luminescence lifetime of an excitation light source under atmospheric pressure, with varying luminescence intensity.This figure shows an example of measurement results for the luminescence lifetime of an excitation light source under vacuum conditions, with varying luminescence intensity.This is a schematic cross-sectional view showing the configuration of a water meter as an example of an object under inspection. The present invention will now be described in more detail with reference to the drawings, with examples of embodiments and specific examples provided below, but the present invention is not limited to these embodiments and specific examples. Furthermore, it should be noted that the following diagrams used in the explanation are schematic, and the proportions of the dimensions may differ from those of reality. For ease of understanding, diagrams of components other than those necessary for the explanation have been omitted as appropriate. The leak inspection method according to this embodiment is a leak inspection method for inspecting air leaks in an object to be inspected which has an internal space that is depressurized to a predetermined degree of vacuum and airtightly sealed, and includes a light projection step of projecting excitation light from outside the internal space onto a pressure-sensitive paint P whose luminescence intensity changes with changes in the oxygen concentration inside the internal space; a measurement step of measuring the decay time of the luminescence intensity; and a determination step of determining that there is an air leak if the decay time is less than a predetermined threshold. The leak inspection apparatus 1 for implementing the leak inspection method according to this embodiment includes a light-emitting unit 10 that projects excitation light from outside the internal space onto a pressure-sensitive paint P whose light emission intensity changes with changes in the oxygen concentration inside the internal space, a light-receiving unit 20 as a light-receiving means for receiving the light emitted from the pressure-sensitive paint P, a measurement unit 30 as a measuring means for measuring the decay time of the light emission intensity of the received light, and a notification unit 40 as a notification means for notifying the user if the decay time is below a predetermined threshold. First, a leak inspection device 1 for implementing the leak inspection method according to this embodiment and a water meter 100 as an example of an object to be inspected will be described with reference to the drawings. Figure 1 is a block diagram showing the functional configuration of the leak inspection device 1 according to this embodiment, Figure 2 is a schematic diagram showing an example of the leak inspection device 1 according to this embodiment, and Figure 8 is a schematic cross-sectional view showing the configuration of a water meter 100 as an example of an object to be inspected. (Water meter) As an example of an object to be inspect