JP2010271231A - Leak inspection method and leak inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leak inspection method and a leak inspection device that can, when inspecting for leaks using pressure methods, precisely and reliably subtract the temperature-caused portion of change in the pressure of a fluid inside an object being tested. <P>SOLUTION: This leakage inspecting device is provided with: a pump 12 and electromagnetic valve 13 that control the pressure of a fluid in a space 2A; a pressure sensor 14 that measures the pressure of the fluid in the space 2A and outputs pressure data; and a computation unit 15 that makes the determination of whether or not there is a leak. The computation unit 15 determines whether or not there is a leak of fluid from the component 2 on the basis of the results of exponential analysis performed using two types of pressure data. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a leakage inspection method and a leakage inspection apparatus for inspecting leakage of fluid from an inspection target such as a pipe or a tank.

  When transporting fluids such as fuel gas or petroleum using pipes or storing them in various pressure tanks, it is very important to check for the presence or degree of fluid leakage. . This is because leakage of these fluids leads to loss of the fluid itself, danger of ignition, environmental pollution, and the like.

  Among these methods for inspecting leakage, the most basic method is a pressure type leakage inspection method. In this method, the fluid in the pipe or tank is pressurized to a predetermined pressure, and the pressure change of the fluid in the pipe or tank is measured while the pipe or tank is closed, thereby inspecting the presence or degree of fluid leakage. To do.

  However, the pressure of these fluids also changes due to changes in ambient temperature. Therefore, in this inspection method, in order to improve the inspection accuracy and make the inspection reliable, when measuring the pressure change of the fluid in the pipe or tank, the pressure fluctuation is caused by the leakage of the fluid. It is necessary to determine whether the change is due to a change in the temperature of the fluid or a change due to a change in the temperature of the fluid.

Therefore, many measures related to temperature compensation in leakage inspection have been proposed. They are roughly classified into the following four categories.
(1) Method for reducing temperature change of inspection object (for example, Patent Document 1)
(2) A method of preparing a master that changes the same temperature as the inspection target and detecting a differential pressure between the inspection target and the master (for example, Patent Document 2)
(3) Method of estimating presence / absence of temperature change from pressure change before and after leak test (4) Method of temperature compensation using output signal of temperature sensor (for example, Patent Document 3)

JP 2008-26016 A JP 2004-6201 A JP 2001-27576 A

  However, any of the above-described methods has application limits and weak points, and it has been difficult to reliably remove the temperature-induced fluctuation in the fluid pressure change with high accuracy.

  The present invention has been made in view of such a problem, and its purpose is to reliably remove a temperature-induced fluctuation in a pressure change of a fluid in a test object in a pressure type leak test. It is an object of the present invention to provide a possible leakage inspection method and leakage inspection apparatus.

The first leakage inspection method of the present invention includes the following two steps.
(A1) The first characteristic value is obtained based on the first pressure data obtained by measuring the pressure of the fluid in the inspection target for a predetermined period after setting the pressure of the fluid in the inspection target to the first pressure. As a result of the first step (A2) for determining the presence or absence of leakage of fluid from the inspected object using the first characteristic value, it has been found that there is no suspicion that fluid is leaking from the inspected object In this case, the leakage inspection is finished, and if it is found that there is a suspicion that the fluid is leaking from the inspection target, the pressure of the fluid in the inspection target is set to a second pressure different from the first pressure. The second characteristic value derived based on the second pressure data obtained by measuring the pressure of the fluid in the inspection target for a predetermined period, and the result of the exponential analysis derived based on the first pressure data Alternatively, the third characteristic value derived using this result The second step determines the presence or absence of leakage of fluid from the object to be inspected by

  The first leakage inspection apparatus of the present invention derives a first characteristic value based on the first pressure data, and uses the first characteristic value to determine the presence or absence of fluid leakage from the inspection target. It has a part. The first pressure data is obtained by setting the pressure of the fluid in the inspection target to the first pressure and then measuring the pressure of the fluid in the inspection target for a predetermined period. If the result of the determination indicates that there is no suspicion that fluid is leaking from the object to be inspected, the leak inspection device ends the leakage inspection, and it is found that there is suspicion that fluid is leaking from the object to be inspected. In such a case, the following determination is further performed. Specifically, the leakage inspection apparatus is derived using the second characteristic value derived based on the second pressure data and the result of the exponential analysis derived based on the first pressure data or using this result. The third characteristic value is used to determine the presence or absence of fluid leakage from the object to be inspected. The second pressure data is obtained by measuring the pressure of the fluid in the inspection target for a predetermined period after setting the pressure of the fluid in the inspection target to a second pressure different from the first pressure. .

  In the first leakage inspection method and the first leakage inspection apparatus of the present invention, first, leakage determination using one type of pressure data is performed. As a result, only when there is a suspicion of leakage, the second type of pressure is detected. Leakage determination using data is performed. Exponential analysis is performed in the second leak determination. As a result, it is possible to distinguish between the pressure fluctuation caused by the temperature change and the pressure fluctuation caused by the leakage, so that the information on the temperature change can be removed from the pressure data and only the information on the leakage can be extracted. .

The second leakage inspection method of the present invention includes the following two steps.
(B1) The first pressure data is obtained by measuring the pressure of the fluid in the inspection target for a predetermined period after the pressure of the fluid in the inspection target is set to the first pressure, and then the inspection target After the pressure of the fluid in the chamber is changed to a second pressure different from the first pressure, the second pressure data is obtained by measuring for a predetermined period (B2). The result of exponential analysis derived based on the first pressure data obtained by measuring the pressure of the fluid in the object to be inspected for a predetermined period after the pressure is set to 1 or the fourth derived using this result. The fifth characteristic value derived based on the characteristic value and the second pressure data obtained by measuring the pressure of the fluid in the object to be inspected for a predetermined period after making the second pressure different from the first pressure. Leakage of fluid from the inspected object using The second step determines the presence or absence

  The second leakage inspection apparatus of the present invention acquires the first pressure data by measuring the pressure of the fluid in the inspection target for a predetermined period after setting the pressure of the fluid in the inspection target to the first pressure. And a data acquisition unit for acquiring the second pressure data by measuring the fluid pressure in the object to be inspected to a second pressure different from the first pressure and then measuring for a predetermined period of time. It is. The leak inspection apparatus further includes a result of exponential analysis derived based on the first pressure data or a fourth characteristic value derived using the result and a fifth characteristic derived based on the second pressure data. A determination unit that determines whether or not there is a leakage of fluid from the inspection target using the value is provided. The first pressure data is obtained by setting the pressure of the fluid in the inspection target to the first pressure and then measuring the pressure of the fluid in the inspection target for a predetermined period. The second pressure data is obtained by measuring the fluid pressure in the object to be inspected for a predetermined period after setting the second pressure different from the first pressure.

  In the second leak test method and the second leak test apparatus of the present invention, an exponential analysis using the first pressure data among the two types of pressure data is performed. This makes it possible to distinguish between pressure fluctuations due to temperature changes and pressure fluctuations due to leaks, so that information about temperature changes can be removed from pressure data and only information about leaks can be extracted. it can.

  According to the first and second leakage inspection methods and the first and second leakage inspection devices of the present invention, it is possible to remove information about temperature changes and extract only information about leakage from pressure data. I did it. Thereby, the presence or absence of leakage can be reliably determined. That is, according to the present invention, in the pressure-type leak test, the temperature-induced variation in the pressure change of the fluid in the test object can be reliably removed with high accuracy.

1 is a schematic configuration diagram of a leakage inspection apparatus according to a first embodiment of the present invention. It is a figure showing an example of the time-dependent change of the pressure in to-be-inspected object. It is a figure showing the procedure of the leakage inspection by the leakage inspection apparatus of FIG. It is a figure showing the other example of the time-dependent change of the pressure in to-be-inspected object. It is a figure showing the other example of the time-dependent change of the pressure in to-be-inspected object. It is a figure showing the other example of the time-dependent change of the pressure in to-be-inspected object. It is a schematic block diagram of the leakage inspection apparatus when it is set as the test subject different from the test subject of FIG. It is a schematic block diagram of the leakage inspection apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic block diagram of the leakage inspection apparatus when it is set as the test object different from the test object of FIG. It is a figure showing the modification of the procedure of the leakage inspection of FIG.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the invention will be described in detail with reference to the drawings. The description will be given in the following order.

1. First Embodiment (Gauge Pressure Leakage Inspection)
・ Structure of leak test equipment ・ Procedure for leak test ・ Principle of leak test ・ Method of index analysis ・ Effect Modified example of the first embodiment (example in which the object to be inspected is piping)
3. Second embodiment (differential pressure type leakage inspection)
4). Modified example of the second embodiment (example in which the object to be inspected is piping)
5). Modification common to each embodiment and its modification (variation of inspection procedure)

<First Embodiment>
[Configuration of Leakage Inspection Device]
FIG. 1 shows a schematic configuration of a leakage inspection apparatus 1 according to the first embodiment of the present invention. The leakage inspection apparatus 1 performs a leakage inspection on an inspection target. The inspection target is, for example, a die-cast part or a container. Here, the “container” means a “vessel” that fills the inside thereof with a fluid, and includes, for example, a pipe and a tank having a volume larger than that of the pipe. In addition to a single-phase substance composed of a gas or a liquid, a “fluid” includes a state in which two or more phases of a gas, a liquid, or a solid are mixed, and a mixture of a plurality of them. It is a concept that includes.

  In the following, a case will be described in which the object to be inspected is a die-cast part 2 used in, for example, an engine gear box case.

  For example, as shown in FIG. 1, the leakage inspection apparatus 1 includes a base 10 and a sealing material 11 provided on the upper surface of the base 10. The base 10 is for fixing the component 2 to be inspected, and is in close contact with the component 2 via a sealing material 11 as shown in FIG. The base 10 has a through hole 10 </ b> A connected to one end of the pipe 18. The through hole 10 </ b> A is formed at a position communicating with the gap 2 </ b> A formed by the base 10 and the part 2 when the part 2 is fixed on the base 10. The sealing material 11 is for ensuring the airtightness of the gap 2A. The gap 2A is filled with gas as a fluid, for example.

  For example, as shown in FIG. 1, the leak inspection apparatus 1 includes a pump 12 connected to one end of a pipe 18 and an electromagnetic valve 13 connected in the middle of the pipe 18. The pump 12 controls the pressure of the fluid in the gap 2A, and supplies the fluid into the gap 2A via the pipe 18 or takes in the fluid filled in the gap 2A into the pump 12. Thus, the fluid in the gap 2A is pressurized or depressurized. The electromagnetic valve 13 is closed when the pressure sensor 14 to be described later measures the pressure to separate the pump 12 and the gap 2A, or is opened when the pump 12 is driven to connect the pump 12 and the gap 2A. Is.

  In addition, the leak test | inspection apparatus 1 may be equipped with mechanisms other than the above-mentioned pump 12 and the electromagnetic valve 13 as a mechanism (pressure control part) which controls the pressure of the space | gap 2A. The leak inspection apparatus 1 may include, for example, a combination of a diaphragm and a moving coil.

  As shown in FIG. 1, for example, the leakage inspection apparatus 1 further includes a pressure sensor 14 (pressure measurement unit), a calculation unit 15 (leakage determination unit), a drive unit 16, and a display unit 17. ing.

  The pressure sensor 14 measures the pressure of the fluid in the gap 2A. For example, the pressure sensor 14 communicates with the gap 2A through the through hole 10A of the base 10 and the pipe 18 connected to the through hole 10A. . The pressure sensor 14 outputs the measured pressure as a pressure signal 14A to the calculation unit 15. The pressure measured by the pressure sensor 14 is not necessarily an absolute pressure, and may be, for example, a gauge pressure (pressure difference between the pressure in the air gap 2A and the external air pressure) or a relative pressure with another fluid. Good. In addition, although the above-mentioned external atmospheric pressure is generally atmospheric pressure, it may be a pressure different from that.

  The drive unit 16 drives the pump 12 and the electromagnetic valve 13 based on a control signal from the calculation unit 15. The display unit 17 displays the determination result based on a signal corresponding to the determination result from the calculation unit 15 and notifies the user. As a means for notifying the user, for example, a speaker that outputs sound may be used instead of or in addition to the display unit 17.

  The calculation unit 15 has a function of controlling the drive unit 16 and a function of inspecting the presence or absence of fluid leakage from the component 2 based on the pressure signal 14 </ b> A output from the pressure sensor 14. Below, the procedure of the leakage inspection performed in the calculating part 15 is demonstrated.

[Leakage inspection procedure]
FIG. 2 shows an example of the change over time of the pressure fluctuation that is performed when the leak inspection is performed. FIG. 3 shows an example of the procedure of leakage inspection executed in the calculation unit 15. First, the calculation unit 15 sets the pressure of the fluid in the gap 2A to a predetermined pressure (first pressure) (step S1). Specifically, the arithmetic unit 15 starts the pressurization (pressure fluctuation) for the fluid in the part 2 at time t _1, where the pressure of the fluid in the gap 2A reaches a predetermined size (time t ₂ ) To stop pressurization (pressure fluctuation).

Next, the arithmetic unit 15, for example, receives pressure data (pressure) output from the pressure sensor 14 after the transient temperature change accompanying the fluctuation of the pressure of the fluid in the gap 2 </ b> A attenuates and converges (time t ₃ ). The acquisition of the signal 14A) is started (step S2). At this time, the calculation unit 15 continuously acquires pressure data for a predetermined section (first section Δt ₁ ) from time t ₃ to time t ₄ . Note that the calculation unit 15 may start to acquire pressure data output from the pressure sensor 14 before the transient temperature change accompanying the fluctuation of the pressure of the fluid in the gap 2A converges. Further, at this stage, the calculation unit 15 may immediately perform an exponential analysis using a series of pressure data (pressure signal 14A), or at the stage where all the pressure data necessary for the leak test has been acquired. An exponential analysis may be performed. In the present embodiment, it is assumed that the exponential analysis is performed at the stage where all the pressure data necessary for the leakage inspection has been acquired. A specific method of index analysis will be described in detail later.

Next, the computing unit 15 sets the pressure of the fluid in the gap 2A to a pressure (second pressure) different from the current pressure (first pressure) (step S3). Specifically, the arithmetic unit 15, the vacuum to the fluid in the gap 2A (pressure fluctuations) begins at time t _4, where the pressure of the fluid in the gap 2A reaches a predetermined size (time t ₅₎ To stop decompression (pressure fluctuation). At this time, it is preferable that the pressure of the fluid in the space 2 </ b> A is an external atmospheric pressure (for example, atmospheric pressure) or almost an external atmospheric pressure. Further, when the pressure of the fluid in the gap 2A is reduced, the pressure regulating valve 19 provided in the pipe 18 is opened to allow the gap 2A to communicate with the outside, and then the pressure of the fluid in the gap 2A is set to a desired value. The pressure adjustment valve 19 may be closed when the pressure is reached.

Next, the operation part 15, for example, after a transient temperature changes due to variations in the pressure of the fluid in the gap 2A is attenuated converged (time t _6), it begins to acquire a second time pressure data (step S4). At this time, the calculation unit 15 continuously acquires pressure data for a predetermined section (second section Δt ₂ ) from time t ₆ to time t ₇ . Note that the calculation unit 15 may start to acquire pressure data output from the pressure sensor 14 before the transient temperature change accompanying the fluctuation of the pressure of the fluid in the gap 2A converges. Further, at this stage, the calculation unit 15 may immediately perform an exponential analysis using a series of pressure data (pressure signal 14A), or at the stage where all the pressure data necessary for the leak test has been acquired. An exponential analysis may be performed. In the present embodiment, it is assumed that the exponential analysis is performed at the stage where all the pressure data necessary for the leakage inspection has been acquired.

Next, the calculating part 15 determines the presence or absence of leakage. Specifically, the calculation unit 15 first performs exponential analysis using two types of pressure data (pressure data of the first section Δt ₁ and pressure data of the second section Δt ₂ ) (step S5). Subsequently, the calculation unit 15 determines the presence or absence of fluid leakage from the component 2 based on the analysis result (step S6). For example, the calculation unit 15 first approximates the change over time of the pressure data in the first section Δt ₁ with an exponential function, and approximates the change over time in the pressure data of the second section Δt ₂ with an exponential function. Subsequently, the calculation unit 15 has a predetermined correlation between the attenuation coefficient of the exponential function obtained from the pressure data in the first section Δt ₁ and the attenuation coefficient of the exponential function obtained from the pressure data in the second section Δt _2. It is determined whether or not. As for the degree of correlation, both attenuation coefficients do not have to be completely applied to a predetermined correlation equation described later, and may have a certain range (error). As a result, when these are not in the predetermined correlation, the calculation unit 15 determines that there is a suspicion that fluid is leaking from the component 2, and displays that fact on the display unit 17 (step S7). On the contrary, when these are in a predetermined correlation, the calculation unit 15 determines that there is no suspicion that fluid is leaking from the component 2, and displays that fact on the display unit 17 (step S8). . In step S6, when the calculation unit 15 determines that there is a suspicion of leakage, the calculation unit 15 obtains the pressure data output from the pressure sensor 14 again, and uses the series of pressure data to perform exponential analysis. The correlation of the attenuation coefficient may be determined again.

In the above leakage determination, the pressure in the first section Δt ₁ is larger than the pressure in the second section Δt _2. For example, as shown in FIG. 4, the first section Δt ₁ and the second section The order of Δt ₂ with time may be reversed so that the pressure in the first exponential analysis section is smaller than the pressure in the next exponential analysis section. Further, in the above-described leakage determination, the pressurization process is performed on the fluid in the gap 2A when the pressure in the first section Δt ₁ is obtained. For example, as shown in FIG. 5, the depressurization process is performed. Also good. Further, for example, as shown in FIG. 6, in the process shown in FIG. 5, the order of the first interval Δt ₁ and the second interval Δt ₂ is reversed, and the pressure in the first exponent analysis interval is changed to the next exponent. You may make it become larger than the pressure of an analysis area.

[Principle of leak inspection]
Next, the principle of the above-described leakage inspection will be described. In leak testing, it can often be assumed that the temperature of the test object is exponentially decaying. For example, in the inspection of die cast work and inspection after pipe construction work, the object to be inspected is heated or cooled in the previous process such as cleaning and fusion of the connection part. In many cases, the temperature is different from the external temperature (for example, room temperature). In this case, the temperature of the object to be inspected gradually equilibrates to the external temperature while the leakage inspection is performed, so that the temperature change is almost exponential. In such a case, a simple algorithm for distinguishing between temperature change and leakage can be considered by estimating the attenuation coefficient (time constant) at two different pressures.

Now, it is assumed that the average temperature T (t) of the fluid in the air gap 2A has the relationship expressed by Equation ₁ in the first section Δt ₁ . In Equation 1, T ₂ is the temperature of the atmosphere around the object to be inspected, and is usually the outside air temperature or room temperature. ΔT is T ₂ −T (0). T (0) is the temperature at time t = 0. β is an attenuation coefficient. In the present embodiment, for example, the time t ₃ in FIG. 2 is used as a reference, and the time t in the mathematical expression represents an elapsed time when measured with the time t ₃ as the origin.

(When there is no fluid leakage)
If there is no fluid leakage, the pressure in the gap 2A is given by In Equation 2, M ⁽¹⁾ is the mass of the fluid in the gap 2A at the time of closing (first interval Δt ₁ ). V ₀ is the volume of the gap 2A. R is a gas constant. m is the molecular weight of the gas in the gap 2A. Note that the superscript (1) in Equation 2 means an estimated value in the first interval Δt ₁ .

However, since the relational expressions shown in Equations 3 and 4 hold, the right side of Equation 2 is as shown in Equation 5. In Equation 5, P ₁ is the pressure at the end of the first section Δt ₁ .

By performing exponential analysis using Equation 5, it is possible to estimate the values of the attenuation coefficient β (or the time constant that is the inverse thereof), the attenuation amplitude A ^(1), and the bias offset B ⁽¹⁾ .

Next, in the second section Δt ₂ , if there is no fluid leakage, the pressure of the fluid in the gap 2A should be expressed by the following equation (6). In Equation 6, M ⁽²⁾ is the mass of the fluid in the gap 2A at the time of closing (second interval Δt ₂ ). Δt is a time interval between the first interval Δt ₁ and the second interval Δt _2, and corresponds to t ₆ -t ₃ in FIG. When the left side of Equation 6 is replaced with P ′ (t), the equation shown in Equation 7 is obtained. Note that the superscript (2) in Expression 7 means an estimated value in the second interval Δt ₂ .

Here, the values of the attenuation coefficient β ⁽²⁾ , the attenuation amplitude A ^(2), and the bias offset B ⁽²⁾ in the second section Δt ₂ should satisfy the following equations 8, 9, and 10. In Equations 8, 9, and 10, estimation errors due to the influence of noise and the like are not considered.

When the three estimated values in the first section Δt _{1 and} the three estimated values in the second section Δt ₂ satisfy the above-mentioned formulas 8, 9, and 10, the pressure drop in the first section Δt ₁ Can be determined not to be due to leakage but to an exponential decrease in temperature.

(When there is no temperature change and only leakage exists)
Next, the case where there is no temperature change and only leakage is considered. At this time, the pressure change in the first section Δt ₁ is expressed by Equation 11. Further, the pressure is exponentially attenuated and satisfies Equations 12 and 13. In Equation 12, k is a time constant. P ₂ is the pressure at the end of the second section Δt ₂ . ΔP is a pressure difference between the pressure P ₁ at the end of the first section Δt ₁ and the pressure P ₂ at the end of the second section Δt ₂ .

On the other hand, in the second section Δt ₂ , the pressure difference does not change and is constant because the internal / external pressure difference is zero. That is, an exponential change in pressure due to leakage can occur only in the first interval Δt ₁ . That is, when there is no temperature change and leakage exists, the three estimated values in the first interval Δt _{1 and} the three estimated values in the second interval Δt ₂ are the above-described Equations 8, 9, and Does not satisfy 10. In other words, it is difficult to estimate the three estimated values in the second section Δt ₂ .

(When both temperature change and leakage exist)
Next, consider the case where both an exponential change in ambient temperature and an exponential decay in pressure due to leakage exist simultaneously. At this time, in the first section Δt ₁ , both exponential functions are overlapped to have the function form shown in Equation 14.

On the other hand, in the second section Δt ₂ , since there is no pressure change due to leakage, the pressure change shown in Formula 15 should be shown. Therefore, the three estimated values in the first interval Δt _{1 and} the three estimated values in the second interval Δt ₂ do not satisfy the above-described Equations 8, 9, and 10.

  From the above, an exponential analysis is performed in two sections as shown in FIG. 2, and the presence or absence of leakage is determined using whether or not those results satisfy the above-mentioned formulas 8, 9, and 10 as an index. It is possible.

  The above theory is valid not only in the case of the pressure fluctuation shown in FIG. 2, but also in the cases of FIGS.

[Method of exponential analysis]
Next, an index analysis method will be described. In the present embodiment, for example, Fourier transform is used as an exponential analysis technique. Hereinafter, a method of exponential analysis using Fourier transform will be described.

It is assumed that the pressure p (t) during the exponential analysis interval is expressed by Equation 16.

This function is sampled at a period of T seconds, the data series shown in Equation 17 is measured, and the DFT is calculated. If there is no influence of noise, the DFT is as shown in Equation 18.

Here, when Ω is defined as shown in Equation 19, Ω satisfies Equation 20 and Equation 21. As a result, the parameters of the exponential function in the exponential analysis section can be estimated by Equations 21, 22, and 23. For example, an estimated value (maximum likelihood estimated value or least square estimated value) of the quantity represented by the estimation formulas shown in Equations 21, 22, and 23 is obtained, and exponential function parameters (β, A, B) can be determined. These estimation formulas are different from the conventionally known estimation formulas of the Fourier transform method. In the estimation equations shown in Equations 21, 22, and 23, the influence of the finite time property in the actual calculation is taken into account, so that an accurate estimated value can be obtained.

  For example, a nonlinear optimization method can be used as an exponential analysis method. In particular, the nonlinear optimization method is suitable for parameter estimation when the pressure signal is composed of two or more exponential functions. As the nonlinear optimization method, as described in literatures such as AAIstratov and OFVyvenko: Exponential analysis in physical phenomena, RSI, 70 (2), 1233/1257, 1999, for example, Simplex method, Examples include various methods based on the Newton-Raphson method, quasi-Newton methods, methods based on the Gauss-Newton method, and Marquardt methods.

By the way, the pressure signal includes two or more exponential functions in, for example, the following three cases.
(1) When there is both temperature change and leakage (2) When pressure data is acquired before the transient change in temperature converges (3) The characteristics of the heat transfer system to be inspected change during the inspection if you did this

  First, in the case of the above (1), the exponential parameters of both temperature change and leakage can be estimated by using the nonlinear optimization method. As a result, the temperature change parameters in the section where only the temperature change occurs (for example, when the atmospheric pressure is set) and the section where both the temperature change and the leak exist (when the first pressure is set) match, Since the result is that the parameters of the two do not match (not in correlation), it is possible to remove the information about the temperature change and extract only the information about the leakage. In the case of (1) above, when the Fourier transform method is used, the estimation of the exponent parameter itself is not performed accurately. However, the index parameter does not match (not correlated) in the section where only the temperature change and the section where both the temperature change and leakage occur. Therefore, even when the Fourier transform method is used, it is possible to remove information about temperature changes and extract only information about leakage.

  Next, in the case of the above (2) (Claim 13), even if there is only one original exponential function, an exponential function accompanying a transient temperature change is included. Therefore, in this case, it may be advantageous to use a nonlinear optimization method. In the case of the above (3), it seems more advantageous to separate the exponential functions using the nonlinear optimization method and estimate each of them.

[effect]
In the present embodiment, the pump 12 and the electromagnetic valve 13 that control the pressure of the fluid in the gap 2A, the pressure sensor 14 that measures the pressure of the fluid in the gap 2A, and outputs pressure data, and the calculation that performs the leak determination A portion 15 is provided. Then, the calculation unit 15 performs an exponential analysis using two types of pressure data (pressure data of the first section Δt ₁ and pressure data of the second section Δt ₂ ). As a result, the pressure fluctuation caused by the temperature change and the pressure fluctuation caused by the leakage can be distinguished from the correlation of the attenuation coefficient, so information on the temperature change is removed from the two types of pressure data, Only information about leaks can be extracted. As a result, the presence or absence of leakage can be reliably determined. As described above, in the present embodiment, in the pressure-type leak test, the temperature-induced variation in the pressure change of the fluid in the test target can be reliably removed with high accuracy.

<Modification of the first embodiment>
In the first embodiment, the case where the object to be inspected is the die-cast part 2 as shown in FIG. 1 has been described. For example, even if the pipe 3 is as shown in FIG. Good. This piping 3 has a role as a path | route at the time of transporting fluids, such as fuel gas and petroleum, for example, and has a fluid in the inside. At this time, the pipe 3 has a pair of valves 3A and 3B at predetermined positions. These valves 3A and 3B close a predetermined piping region when performing a leakage inspection.

Also in this modified example, as in the above-described embodiment, it is possible to perform an exponential analysis using two types of pressure data (pressure data in the first section Δt ₁ and pressure data in the second section Δt ₂ ). . Therefore, in the pressure-type leak test, the temperature-induced variation in the pressure change of the fluid in the test object can be reliably removed with high accuracy.

<Second Embodiment>
FIG. 8 shows a schematic configuration of the leakage inspection apparatus 4 according to the second embodiment of the present invention. This leakage inspection apparatus 4 performs a differential pressure type leakage inspection, and is different from the leakage inspection apparatus 1 that performs a gauge pressure type leakage inspection in terms of the inspection method. Further, along with the difference in the inspection method, the leakage inspection apparatus 4 has a configuration different from that of the leakage inspection apparatus 1. Therefore, in the following, description of points common to the leakage inspection apparatus 1 will be omitted as appropriate, and differences from the leakage inspection apparatus 1 will be mainly described.

  For example, as shown in FIG. 8, the leakage inspection apparatus 4 of the present embodiment includes a base 10, a sealing material 11, a pump 12, an electromagnetic valve 13, and a pipe 18, as in the above embodiment. The leakage inspection apparatus 4 also includes a differential pressure sensor 41, a reference container 42, an electromagnetic valve 43, and a pipe 44, for example, as shown in FIG. The differential pressure sensor 41 is inserted in the middle of the pipe 18. One end of the pipe 18 is connected to the through hole 10 </ b> A of the base 10, and the other end of the pipe 18 is connected to the pump 12. The electromagnetic valve 13 is inserted between the pump 12 and the differential pressure sensor 41 in the pipe 18, and communicates with the air gap 42 </ b> A in the reference container 42 between the electromagnetic valve 13 and the differential pressure sensor 41 in the pipe 18. The through-hole 42B which connects is connected. Further, one end of the pipe 44 is connected between the pump 12 and the electromagnetic valve 13 in the pipe 18, and the other end of the pipe 44 is connected between the differential pressure sensor 41 of the pipe 18 and the through hole 10 </ b> A. ing.

  The differential pressure sensor 41 measures a differential pressure between the pressure on the gap 2 </ b> A side of the pipe 18 and the pressure on the gap 42 </ b> A side of the pipe 43. Since the differential pressure sensor 41 measures differential pressure, it has a higher resolution than the pressure sensor 14 of the above embodiment. Therefore, the differential pressure sensor 41 can reliably detect slight fluctuations in the pressure in the component 2 and the pressure in the reference container 42. The reference container 42 is, for example, a container with no leakage, and has a gap 42A having a volume similar to the volume in the object to be inspected. Some structures may be provided in the gap 42A as necessary. The reference container 42 is placed in the same environment as the part 2, and the ambient temperature of the reference container 42 is substantially the same as the ambient temperature of the part 2. Therefore, the influence of the external temperature can be removed by measuring the pressure difference between the pressure in the reference container 42 and the pressure in the component 2. The electromagnetic valves 13 and 43 are provided for the purpose of closing when measuring the differential pressure between the pressure inside the reference container 42 and the pressure inside the component 2 and opening when driving the pump 12. In the present embodiment, the pump 12 supplies the fluid to the inside of the component 2 and the reference container 42 via the pipes 18 and 44, or pumps the fluid filled in the interior of the component 2 and the reference container 42. 12 is used to pressurize or depressurize the fluid inside the component 2 and the reference container 42.

  The leakage inspection apparatus 4 according to the present embodiment further includes, for example, a calculation unit 45, a drive unit 46, and a display unit 47.

  The drive unit 46 drives the pump 12 and the electromagnetic valves 13 and 43 based on a control signal from the calculation unit 45. The display unit 47 displays the determination result based on a signal corresponding to the determination result from the calculation unit 45 and notifies the user. As a means for notifying the user, for example, a speaker that outputs sound may be used instead of or in addition to the display unit 47.

  The calculation unit 45 has a function of controlling the drive unit 46 and a function of inspecting the presence or absence of fluid leakage from the component 2 based on the pressure signal 41 </ b> A output from the differential pressure sensor 41. Below, the procedure of the leakage inspection performed in the calculating part 45 is demonstrated.

[Leakage inspection procedure]
First, the calculation unit 45 drives the pump 12 and the electromagnetic valves 13 and 43 to set the fluid pressure in the component 2 and the reference container 42 to a predetermined pressure (first pressure) (step S1). Specifically, the arithmetic unit 45, the time t _1, to start pressurization to the fluid component 2 and the reference container 42 (pressure fluctuation), the pressure of the fluid in the parts 2 and the reference container 42 is of a predetermined magnitude When this is reached (time t ₂ ), pressurization (pressure fluctuation) is stopped. Hereinafter, for convenience, “the fluid in the component 2 and the reference container 42” will be referred to as “the fluid in the component 2, etc.”.

Next, the calculation unit 45, for example, after the transient temperature change accompanying the fluctuation of the pressure of the fluid in the gap 2A attenuates and converges (time t ₃ ), the pressure data output from the differential pressure sensor 41 (time t ₃ ). The acquisition of the pressure signal 41A) is started (step S2). At this time, the calculation unit 45 continuously acquires pressure data for a predetermined section (first section Δt ₁ ) from time t ₃ to time t ₄ . Note that the calculation unit 15 may start to acquire pressure data output from the pressure sensor 14 before the transient temperature change accompanying the fluctuation of the pressure of the fluid in the gap 2A converges. Further, at this stage, the calculation unit 45 may immediately perform an exponential analysis using a series of pressure data (pressure signal 41A), or at the stage where all the pressure data necessary for the leak test has been acquired. An exponential analysis may be performed. In the present embodiment, it is assumed that the exponential analysis is performed at the stage where all the pressure data necessary for the leakage inspection has been acquired. A specific method of exponential analysis is the same as that in the above embodiment.

Next, the calculating part 45 makes the pressure of the fluid in the components 2 etc. a pressure (second pressure) different from the current pressure (first pressure) (step S3). Specifically, the calculation unit 15 first starts the pressure reduction (pressure fluctuation) with respect to the fluid in the component 2 and the like at time t ₄ by driving the pump 12 and the electromagnetic valves 13 and 43. Subsequently, the calculation unit 15 stops the pressure reduction (pressure fluctuation) when the pressure of the fluid in the component 2 or the like reaches a predetermined magnitude (time t ₅ ). At this time, it is preferable that the pressure of the fluid in the component 2 etc. is external pressure (for example, atmospheric pressure) or almost external pressure. Further, when the pressure of the fluid in the component 2 or the like is reduced, the pressure regulating valve 48 provided in the pipe 43 is opened to allow the gap in the component 2 or the like to communicate with the outside, and then in the component 2 or the like. The pressure regulating valve 48 may be closed when the fluid pressure reaches a desired pressure.

Next, the calculation unit 45 acquires the second pressure data (pressure signal 41A) after the transient temperature change accompanying the fluctuation of the pressure of the fluid in the gap 2A is attenuated and converged (time t ₆ ). Start (step S4). At this time, the calculation unit 45 continuously acquires pressure data for a predetermined interval (second interval Δt ₂ ) from time t ₆ to time t ₇ . Note that the calculation unit 15 may start to acquire pressure data output from the pressure sensor 14 before the transient temperature change accompanying the fluctuation of the pressure of the fluid in the gap 2A converges. Further, at this stage, the calculation unit 45 may immediately perform an exponential analysis using a series of pressure data (pressure signal 41A), or at the stage where all the pressure data necessary for the leak test has been acquired. An exponential analysis may be performed. In the present embodiment, it is assumed that the exponential analysis is performed at the stage where all the pressure data necessary for the leakage inspection has been acquired.

Next, the calculation unit 45 determines whether there is a leak. Specifically, the calculation unit 45 first performs exponential analysis using two types of pressure data (pressure data of the first section Δt ₁ and pressure data of the second section Δt ₂ ) (step S5). Subsequently, the calculation unit 45 determines whether or not there is leakage of fluid from the component 2 based on the analysis result (step S6). For example, the computing unit 45 first approximates the change over time of the pressure data in the first interval Δt ₁ with an exponential function and approximates the change over time in the pressure data of the second interval Δt ₂ with an exponential function. Subsequently, the calculating unit 45 has a predetermined correlation between the attenuation coefficient of the exponential function obtained from the pressure data in the first section Δt ₁ and the attenuation coefficient of the exponential function obtained from the pressure data in the second section Δt _2. It is determined whether or not. As for the degree of correlation, both attenuation coefficients do not have to be completely applied to a predetermined correlation equation described later, and may have a certain range (error). As a result, when these are not in the predetermined correlation, the calculation unit 45 determines that there is a suspicion that fluid is leaking from the component 2, and displays that fact on the display unit 47 (step S7). On the contrary, if these are in a predetermined correlation, the calculation unit 45 determines that there is no suspicion that fluid is leaking from the component 2, and displays that fact on the display unit 47 (step S8). . In step S6, when the calculation unit 45 determines that there is a suspicion of leakage, the calculation unit 45 obtains the pressure data output from the differential pressure sensor 41 again, and uses the series of pressure data to obtain an exponent. Analysis may be performed to re-determine the correlation of the attenuation coefficient.

In the leak determination described above, the pressure in the first section Δt ₁ is larger than the pressure in the second section Δt _2. For example, the order of the first section Δt ₁ and the second section Δt ₂ with time is changed. Conversely, the pressure in the first exponential analysis section may be made smaller than the pressure in the next exponential analysis section. Further, in the above-described leakage determination, the pressurizing process is performed on the fluid in the component 2 or the like when the pressure in the first section Δt ₁ is obtained, but, for example, a depressurizing process may be performed. Further, for example, when the pressure in the first section Δt ₁ is obtained, the decompression process is performed, and the order of the first section Δt ₁ and the second section Δt ₂ with respect to time is reversed. You may make it become larger than the pressure of an index analysis area.

[effect]
In the present embodiment, the differential pressure sensor 41 that measures the pressure difference between the pump 12 and the electromagnetic valves 13 and 43 that control the pressure of the fluid in the gaps 2A and 42A, and the gap 2A and the gap 42A, and outputs pressure data. And a calculation unit 45 that performs leakage determination. Then, an exponential analysis using two types of pressure data (pressure data of the first section Δt ₁ and pressure data of the second section Δt ₂ ) is performed in the calculation unit 45. As a result, the pressure fluctuation caused by the temperature change and the pressure fluctuation caused by the leakage can be distinguished from the correlation of the attenuation coefficient, so information on the temperature change is removed from the two types of pressure data, Only information about leaks can be extracted. As a result, the presence or absence of leakage can be reliably determined. As described above, also in the present embodiment, in the pressure-type leak test, the temperature-induced fluctuation in the pressure change of the fluid in the test target can be reliably removed with high accuracy.

<Modification of Second Embodiment>
In the second embodiment, the case where the object to be inspected is the die-cast part 2 as shown in FIG. 8 is described. For example, even if the pipe 3 is as shown in FIG. Good.

  In this modification, in the leakage inspection apparatus 4, for example, as shown in FIG. 9, the pipe 3 is connected instead of the component 2, and the reference container 51 is connected instead of the reference container 42.

  The reference container 51 is, for example, a container that does not leak, and has a gap 51 </ b> A having a volume similar to the volume in the inspection target. Any structure may be provided in the gap 51A as necessary. The reference container 51 is placed in the same environment as the pipe 3, and the ambient temperature of the reference container 51 is substantially the same as the ambient temperature of the pipe 3. Therefore, the influence of the external temperature can be removed by measuring the differential pressure between the pressure in the reference container 51 and the pressure in the pipe 3.

Also in this modified example, as in the second embodiment, an exponential analysis using two types of pressure data (pressure data of the first section Δt ₁ and pressure data of the second section Δt ₂ ) can be performed. Is possible. Therefore, in the pressure-type leak test, the temperature-induced variation in the pressure change of the fluid in the test object can be reliably removed with high accuracy.

<Modifications common to the above embodiments and their modifications>
[First Modification]
In each of the above-described embodiments and modifications thereof, exponential analysis is performed on two types of pressure data. However, exponential analysis is performed only on the first pressure data of the two types of pressure data. May be. For example, instead of Step 5 and Step 6 described in the above embodiment, the following steps are performed.

That is, the calculation unit 15 first performs an exponential analysis using the first pressure data (pressure data in the first section Δt ₁ ), and then uses this analysis result to characterize the pressure data in the second section Δt _2. A value (fourth characteristic value) is derived. Specifically, the calculation unit 15 derives the pressure fluctuation range in the pressure data in the second section Δt ₂ predicted from the result of the exponential analysis in the pressure data in the first section Δt ₁ . Subsequently, the calculation unit 15 uses the pressure fluctuation range obtained by the prediction and the characteristic value derived from the pressure data of the second section Δt ₂ (the pressure fluctuation range obtained by the measurement) to create a gap. The presence or absence of leakage of fluid in 2A (gap 3C) is determined. For example, the calculation unit 15 compares the pressure fluctuation range obtained by the prediction with the pressure fluctuation range obtained by the measurement, and determines whether or not these are in a predetermined correlation. As for the degree of correlation, the two values do not need to completely coincide with each other, and may have a certain range (error). As a result, when they do not have a predetermined correlation, the calculation unit 15 determines that there is a suspicion that fluid is leaking from the component 2 (pipe 3), and displays that fact on the display unit 17. On the contrary, when these are in a predetermined correlation, the calculation unit 15 determines that there is no suspicion that fluid is leaking from the component 2 (pipe 3), and displays that fact on the display unit 17. . Also in this modification, when the calculation unit 15 determines that there is a suspicion of leakage, the pressure data output from the pressure sensor 14 is acquired again and the series of pressure data is used. An exponential analysis may be performed to determine again the correlation between the pressure fluctuation range obtained by prediction and the pressure fluctuation range obtained by measurement.

Thus, in the present modification, two (and pressure data in the first section Delta] t _1, the pressure data in the second interval Delta] t ₂₎ the pressure data of the first (pressure data in the first section Delta] t ₁₎ the pressure data in the Exponential analysis using is performed. Even in this case, it is possible to distinguish between the pressure fluctuation caused by the temperature change and the pressure fluctuation caused by the leakage, so the information about the temperature change is removed from the pressure data, and the leakage Only information can be extracted. As a result, the presence or absence of leakage can be reliably determined. As described above, in this variation, in the pressure-type leak test, the temperature-induced fluctuation in the pressure change of the fluid in the test target can be reliably removed with high accuracy.

[Second Modification]
In each of the above-described embodiments and modifications thereof, the pressure data is always acquired twice. However, the acquisition of the second pressure data may be omitted as necessary. For example, first, leakage determination using one type of pressure data may be performed, and as a result, leakage determination using the second type of pressure data may be performed only when there is a suspicion of leakage. The specific procedure will be described below.

  In the following, the case where the pressure is changed as shown in FIG. 2 will be described as an example. However, this modification can be applied to other pressure changes as shown in FIGS. It is. Hereinafter, a case where the inspection target is the component 2 will be described. However, the present modification can also be applied to a case where the inspection target is the pipe 3 as illustrated in FIG. In the following, a gauge pressure type leak test will be described, but this modification can also be applied to a differential pressure type leak test.

FIG. 10 shows an example of the procedure of leakage inspection executed in the arithmetic unit 15. First, the calculation unit 15 sets the pressure of the fluid in the gap 2A to a predetermined pressure (first pressure) (step S11). Specifically, the arithmetic unit 15 starts the pressurization for the fluid in the gap 2A (pressure fluctuations) at time t _1, where the pressure of the fluid in the gap 2A reaches a predetermined size (time t ₂ ) To stop pressurization (pressure fluctuation).

Next, the arithmetic unit 15, for example, receives pressure data (pressure) output from the pressure sensor 14 after the transient temperature change accompanying the fluctuation of the pressure of the fluid in the gap 2 </ b> A attenuates and converges (time t ₃ ). The acquisition of the signal 14A) is started (step S12). At this time, the calculation unit 15 continuously acquires pressure data for a predetermined section (first section Δt ₁ ) from time t ₃ to time t ₄ . Note that the calculation unit 15 may start to acquire pressure data output from the pressure sensor 14 before the transient temperature change accompanying the fluctuation of the pressure of the fluid in the gap 2A converges.

Next, the calculating part 15 determines the presence or absence of leakage. Specifically, the computing unit 15 first derives a characteristic value (first characteristic value) based on the pressure data in the first section Δt ₁ (step S13). Here, the first characteristic value, the pressure fluctuation range in the first interval Delta] t ₁ of the pressure data (pressure drop width in this case), or is the result of exponential analysis in the first section Delta] t ₁ of the pressure data. The index analysis method is the same as that described in the first embodiment. Subsequently, the computing unit 15 determines whether or not there is leakage of fluid from the component 2 based on the first characteristic value (step S14).

For example, the calculation unit 15 compares the pressure fluctuation range in the pressure data of the first section Δt ₁ with master data (pressure fluctuation range) prepared in advance, and determines whether these are in a predetermined correlation. Determine whether. As for the degree of correlation, the two values do not need to completely coincide with each other, and may have a certain range (error). As a result, when these are in a predetermined correlation, the calculation unit 15 determines that there is no suspicion that fluid is leaking from the component 2, and displays that fact on the display unit 17 (step S15). On the contrary, when these are not in the predetermined correlation, the calculation unit 15 determines that there is a suspicion that fluid is leaking from the component 2, and then proceeds to step. Specifically, the calculation unit 15 sets the pressure of the fluid in the gap 2A to a pressure (second pressure) different from the current pressure (first pressure) (step S16). Specifically, the arithmetic unit 15, the vacuum to the fluid in the gap 2A (pressure fluctuations) begins at time t _4, where the pressure of the fluid in the gap 2A reaches a predetermined size (time t ₅₎ To stop decompression (pressure fluctuation). At this time, it is preferable that the pressure of the fluid in the gap 2A is an external atmospheric pressure (for example, atmospheric pressure). Further, when the pressure of the fluid in the gap 2A is reduced, the pressure regulating valve 19 provided in the pipe 18 is opened to allow the gap 2A to communicate with the outside, and then the pressure of the fluid in the gap 2A is set to a desired value. The pressure adjustment valve 19 may be closed when the pressure is reached.

Next, the operation part 15 after the transient temperature changes due to variations in the pressure of the fluid in the gap 2A is attenuated converged (time t _6), begins to acquire a second time pressure data (step S17) . At this time, the calculation unit 15 continuously acquires pressure data for a predetermined section (second section Δt ₂ ) from time t ₆ to time t ₇ . Note that the calculation unit 15 may start to acquire pressure data output from the pressure sensor 14 before the transient temperature change accompanying the fluctuation of the pressure of the fluid in the gap 2A converges.

Next, the calculating part 15 determines the presence or absence of leakage. Specifically, the computing unit 15 first derives a characteristic value (second characteristic value) based on the pressure data in the second section Δt ₂ (step S18). Here, the second characteristic value, the pressure fluctuation range in the second section Delta] t ₂ of the pressure data (pressure drop width in this case), or is the result of exponential analysis in the second section Delta] t ₂ of the pressure data. Further, the calculation unit 15 performs an exponential analysis using the pressure data in the first section Δt ₁ or derives a characteristic value (third characteristic value) using the result of the exponential analysis. Here, the third characteristic value is a pressure fluctuation width (here, a pressure drop width) in the pressure data in the second section Δt ₂ predicted from the result of the exponential analysis in the pressure data in the first section Δt ₁ . The method of exponential analysis is the same as that described in the first embodiment. Note that the calculation unit 15 may perform the calculation using the pressure data of the first section Δt ₁ at a stage before this stage (for example, the stage of step S13).

Subsequently, when the second characteristic value is the pressure fluctuation range in the pressure data of the second section Δt ₂ , the calculation unit 15 calculates the pressure fluctuation range (third characteristic value) obtained by the prediction. ) And the pressure fluctuation range (second characteristic value) obtained by the measurement, it is determined whether or not they are in a predetermined correlation (step S19). On the other hand, when the second characteristic value is the result of exponential analysis in the pressure data in the second section Δt ₂ , the computing section 15 calculates the exponential function obtained from the pressure data in the first section Δt _1. Is determined to be in a predetermined correlation with the attenuation coefficient of the exponential function obtained from the pressure data of the second section Δt ₂ (step S19).

  As for the degree of correlation, the two values do not need to completely coincide with each other, and may have a certain range (error). As a result, when these are not in the predetermined correlation, the calculation unit 15 determines that there is a suspicion that fluid is leaking from the component 2, and displays that fact on the display unit 17 (step S20). On the contrary, when these are in a predetermined correlation, the calculation unit 15 determines that there is no suspicion that fluid is leaking from the component 2, and displays that fact on the display unit 17 (step S21). . Also in this modification, when the calculation unit 15 determines that there is a suspicion of leakage, the pressure data output from the pressure sensor 14 may be acquired again and the correlation may be determined again. .

In this modification, first, leakage determination using one type of pressure data (pressure data of the first section Δt ₁ ) is performed. As a result, only when there is a suspicion of leakage, the second type of pressure data (first Leakage determination using the pressure data of the two sections Δt ₂ is performed. In the second leak determination, an exponential analysis is performed. As a result, it is possible to distinguish between the pressure fluctuation caused by the temperature change and the pressure fluctuation caused by the leakage, so that the information on the temperature change can be removed from the pressure data and only the information on the leakage can be extracted. . Thereby, the presence or absence of leakage can be reliably determined. That is, also in this modification, in the pressure-type leak test, the temperature-induced variation in the pressure change of the fluid in the test object can be reliably removed with high accuracy.

  In each of the above modifications, the correlation is determined using the pressure fluctuation range for a certain period. However, the correlation can also be determined using a value equivalent to the pressure fluctuation range for a certain period. .

For example, when the time to reach a predetermined pressure fluctuation range is used, the correlation is determined as follows. When calculating the time until the predetermined pressure fluctuation range is reached in the pressure data of the second section Δt ₂ as the second characteristic value, the calculation unit 15 calculates the pressure of the first section Δt ₁ as the third characteristic value. A time required to reach a predetermined pressure fluctuation range in the pressure data of the second section Δt ₂ predicted from the result of the exponential analysis in the data is derived. Then, the calculation unit 15 compares the time (third characteristic value) obtained by the prediction with the time (second characteristic value) obtained by the measurement, and determines whether or not these are in a predetermined correlation. Is determined (step S19).

For example, when the differential coefficient of the pressure change within a certain period is used, the correlation is determined as follows. When the calculation unit 15 derives the differential coefficient of the pressure change within a certain period in the pressure data of the second section Δt ₂ as the second characteristic value, the pressure data of the first section Δt ₁ is used as the third characteristic value. The differential coefficient of the pressure change within a certain period in the pressure data in the second section Δt ₂ predicted from the result of the exponential analysis in FIG. And the calculating part 15 compares the differential coefficient (3rd characteristic value) obtained by prediction, and the differential coefficient (2nd characteristic value) obtained by measurement, and these have a predetermined correlation. It is determined whether or not (step S19).

For example, when the pressure change rate (slope) obtained by dividing the pressure difference between the start and end of the measurement by the time from the start to the end of the measurement is used as follows: To determine the correlation. When the pressure change rate in the pressure data in the second section Δt ₂ is derived as the second characteristic value, the calculation unit 15 uses the result of the exponential analysis in the pressure data in the first section Δt ₁ as the third characteristic value. The predicted pressure change rate in the pressure data in the second section Δt ₂ is derived. Then, the calculation unit 15 compares the pressure change rate (third characteristic value) obtained by the prediction with the pressure change rate (second characteristic value) obtained by the measurement, and these have a predetermined correlation. It is determined whether or not (step S19). Note that the pressure fluctuation range for a certain period, the time until the predetermined pressure fluctuation range is reached, and the differential coefficient of the pressure change within the certain period are values equivalent to the pressure change rate.

  DESCRIPTION OF SYMBOLS 1,4 ... Leak inspection apparatus, 2 ... Parts, 2A, 3C, 42A, 51A ... Air gap, 3, 18, 43 ... Piping, 3A, 3B ... Valve, 10 ... Base, 10A, 42B ... Through-hole, 11 ... Sealing material, 12 ... pump, 13, 43 ... electromagnetic valve, 14 ... pressure sensor, 15, 45 ... calculation unit, 16, 46 ... drive unit, 17, 47 ... display unit, 19, 48 ... pressure adjustment valve, 41 ... Differential pressure sensor, 42, 51 ... reference container.

Claims (15)

The first characteristic value is derived based on the first pressure data obtained by measuring the pressure of the fluid in the inspection target for a predetermined period after setting the pressure of the fluid in the inspection target to the first pressure. The first step of determining the presence or absence of fluid leakage from the object to be inspected using the first characteristic value and the result of the determination revealed that there is no suspicion that fluid is leaking from the object to be inspected. In this case, the leakage inspection is terminated, and when it is found that there is a suspicion that the fluid is leaking from the inspection target, the pressure of the fluid in the inspection target is a second pressure different from the first pressure. After that, the second characteristic value derived based on the second pressure data obtained by measuring the pressure of the fluid in the inspection target for a predetermined period and the first pressure data are derived. The result of the exponential analysis or using this result A leakage inspection method comprising: a second step of determining whether or not there is a leakage of fluid from the inspection target using the derived third characteristic value. The first characteristic value is a pressure change rate in the first pressure data, a value equivalent to a pressure change rate in the first pressure data, or a result of exponential analysis in the first pressure data. Leakage inspection method. The second characteristic value is a pressure change rate in the second pressure data, a value equivalent to a pressure change rate in the second pressure data, or a result of an exponential analysis in the second pressure data. Leakage inspection method. The third characteristic value is a pressure in the second pressure data that is predicted from a result of an exponential analysis in the first pressure data when the second characteristic value is a pressure change rate in the second pressure data. The second pressure data predicted from the result of exponential analysis in the first pressure data when the second characteristic value is a value equivalent to the pressure change rate in the second pressure data. The value equivalent to the pressure change rate in the case where the second characteristic value is a result of exponential analysis in the first pressure data, the result of exponential analysis in the second pressure data. Leakage inspection method. After the pressure of the fluid in the inspection target is set to the first pressure, the first pressure data is obtained by measuring the pressure of the fluid in the inspection target for a predetermined period. A first step of obtaining the second pressure data by measuring the fluid pressure at a second pressure different from the first pressure and then measuring for a predetermined period;
The result of exponential analysis derived based on the first pressure data obtained by measuring the pressure of the fluid in the inspection target for a predetermined period after the pressure of the fluid in the inspection target is set to the first pressure Alternatively, the fourth characteristic value derived using this result and the first characteristic value obtained by measuring the fluid pressure in the object to be inspected for a predetermined period after the second pressure different from the first pressure is obtained. 2. A leakage inspection method including a second step of determining whether or not there is a fluid leakage from the inspection target using a fifth characteristic value derived based on the pressure data. The leakage according to claim 5, wherein the fourth characteristic value is a pressure change rate in the second pressure data, or a value equivalent to the pressure change rate, which is predicted from a result of exponential analysis in the first pressure data. Inspection method. The fifth characteristic value uses, as the fourth characteristic value, a pressure change rate in the second pressure data, which is predicted from an exponential analysis result in the first pressure data, when determining the presence or absence of leakage. In this case, it is the pressure change rate in the second pressure data obtained by measurement, and is predicted from the result of the exponential analysis in the first pressure data as the fourth characteristic value when determining the presence or absence of leakage. The value equivalent to the pressure change rate in the second pressure data obtained by measurement when using a value equivalent to the pressure change rate in the second pressure data. Leakage inspection method. The fifth characteristic value is determined based on the second pressure data obtained by measuring when the result of the exponential analysis derived based on the first pressure data is used when determining the presence or absence of leakage. The leakage inspection method according to claim 5, which is a result of exponential analysis. The leakage inspection method according to any one of claims 1 to 8, wherein one of the first pressure and the second pressure is an external atmospheric pressure. 9. The first pressure data and the second pressure data are differential pressures between a pressure of a fluid in the inspection target and a pressure of a fluid in a reference container prepared as a reference. The leakage inspection method according to any one of the above. The leakage inspection method according to any one of claims 1 to 8, wherein the first pressure data and the second pressure data are pressures of fluid in the inspection target. 9. The first pressure data or the second pressure data is measured after a transient temperature change due to a change in pressure of a fluid in the inspection target is converged. The leakage inspection method according to claim 1. 9. The first pressure data or the second pressure data is measured before a transient temperature change due to a change in pressure of a fluid in the inspection target converges. The leakage inspection method according to any one of the above. The first characteristic value is derived based on the first pressure data obtained by measuring the pressure of the fluid in the inspection target for a predetermined period after setting the pressure of the fluid in the inspection target to the first pressure. A first determination unit that determines whether or not there is leakage of fluid from the inspection target using the first characteristic value; and as a result of the determination, it is found that there is no suspicion that fluid leaks from the inspection target; If it is determined that there is a suspicion that fluid is leaking from the object to be inspected, the pressure of the fluid in the object to be inspected is different from the first pressure. Derived based on the second characteristic value derived on the basis of the second pressure data obtained by measuring the pressure of the fluid in the object to be inspected for a predetermined period after the pressure is applied, and on the first pressure data The result of the index analysis performed or A leakage inspection apparatus comprising: a second determination unit that determines whether or not there is a leakage of fluid from the inspection target using the third characteristic value that is output. After the pressure of the fluid in the inspection target is set to the first pressure, the first pressure data is obtained by measuring the pressure of the fluid in the inspection target for a predetermined period. A data acquisition unit that obtains second pressure data by measuring for a predetermined period after the fluid pressure is changed to a second pressure different from the first pressure;
The result of exponential analysis derived based on the first pressure data obtained by measuring the pressure of the fluid in the inspection target for a predetermined period after the pressure of the fluid in the inspection target is set to the first pressure Alternatively, the fourth characteristic value derived using this result and the first characteristic value obtained by measuring the fluid pressure in the object to be inspected for a predetermined period after the second pressure different from the first pressure is obtained. 2. A leak inspection apparatus comprising: a determination unit that determines whether there is a fluid leak from the inspection target using a fifth characteristic value derived based on the two pressure data.

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