JP2023090380A - Leak test method - Google Patents

Abstract

To provide a leak test method capable of improving the detection accuracy of leak in an internal space in a workpiece.SOLUTION: Provided is a leak test method of a workpiece W including a first inspection object portion A where the existence of leak is inspected and a second inspection object portion B which may communicate with the first inspection object portion A. The leak test method includes the steps of: making inner air pressure PA of the blocked first inspection object portion A higher than outer air pressure P0 of the workpiece W; making inner air pressure PB of the blocked second inspection object portion B lower than the outer air pressure P0 of the workpiece W; and detecting a change in the inner air pressure of the first inspection object portion A and the second inspection object portion B.SELECTED DRAWING: Figure 3

Description

The present invention relates to a leak test method.

Patent Literature 1 discloses a leak test method for inspecting the presence or absence of leaks in a plurality of internal spaces existing within a work.
The leak test method according to Patent Document 1 encloses pressurized gases having different air pressures in a plurality of internal spaces serving as parts to be inspected, detects changes in the air pressure of the enclosed pressurized gases, and detects the presence or absence of leaks. to inspect.

JP 2005-308491 A

In the leak test method according to Patent Literature 1, when a leak exists in a site to be inspected, the greater the difference between the internal pressure of the site to be inspected and the air pressure of the leak destination, that is, the greater the inspection pressure, the more the seal is enclosed in the site to be inspected. The fluctuation of the atmospheric pressure of the compressed gas increases. Since the greater the change in air pressure, the easier it is to detect, the greater the inspection pressure, the higher the leak detection accuracy.

When the parts to be inspected communicate with each other, that is, when there is a leak between the parts to be inspected, the inspection pressure of the leak corresponds to the difference in air pressure of the compressed gas sealed in each part to be inspected.
Therefore, when the pressure difference of the compressed gas sealed in each inspected part is small, there is a problem that the detection accuracy of the leak between the inspected parts is lowered.

In addition, there may be a leak between the parts to be inspected, and a leak communicating with the outside of the workpiece may exist in the part to be inspected having a lower internal pressure. In this case, the compressed gas is supplied from the inspected portion with the higher internal pressure to the inspected portion with the lower internal pressure, and there is also the problem that the detection accuracy of the leak communicating with the outside of the workpiece decreases. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a leak test method capable of improving the detection accuracy of leaks in the internal space of a work.

A leak test method according to an aspect of the present invention comprises:
A work leak test method comprising a first inspected portion to be inspected for the presence or absence of a leak, and a second inspected portion that may communicate with the first non-inspected portion, the method comprising:
making the internal pressure of the closed first inspection site higher than the external pressure of the workpiece;
making the internal pressure of the closed second site to be inspected lower than the external pressure of the workpiece;
detecting changes in the internal pressure of the first and second inspection sites;
It is a leak test method.

With such a configuration, the internal leak inspection pressure is expressed as the sum of the inspection pressure of the first inspected portion against the outside of the work and the inspection pressure of the second inspected portion against the outside of the work. It is possible to set a high leak inspection pressure, and as a result, it is possible to improve the detection accuracy of the internal leak.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a leak test method capable of improving detection accuracy of leaks in the internal space of a work.

FIG. 3 is a schematic cross-sectional view showing the structure of a workpiece to be inspected; 1 is a schematic cross-sectional view showing the configuration of a leak test device according to a first embodiment; FIG. FIG. 4 is a schematic cross-sectional view showing the leak test device during leak test; 4 is a flow chart showing the operation of the leak test device according to the first embodiment;

(Leak test method and problem according to conventional technology)
A conventional leak test method will be described below with reference to the drawings. Then, the problems that occur in the leak test method according to the prior art will be described in detail.

FIG. 1 is a schematic cross-sectional view showing the structure of a workpiece to be inspected.
The workpiece W has a first inspected portion A and a second inspected portion B that may communicate with the first inspected portion.

The parts to be inspected A and B are internal spaces existing in the workpiece W. As shown in FIG. The parts to be inspected A and B have openings, but parts other than the openings must be isolated from the outside of the work W. FIG. In addition, the inspected parts A and B must not communicate with each other. In other words, the parts to be inspected A and B are required to be airtight in areas other than the openings.

According to FIG. 1, the site A to be inspected has two openings, and the site B to be inspected has one opening, but the number of openings is not limited to this. , the number of openings may be any number as long as it is one or more.

As described above, the parts to be inspected A and B are required to be airtight, but leaks may occur in parts other than the openings due to factors such as poor processing and aged deterioration.
A conventional leak test method is a method for inspecting the presence or absence of leaks in inspected parts A and B. FIG.

In the leak test method according to the prior art, first, the openings of the inspected parts A and B are sealed with seal rubber or the like so that the inspected parts A and B are sealed, and the inspected parts A and B are sealed. , contain air pressurized to different atmospheric pressures.
Hereinafter, the internal pressure of the inspection site A will be referred to as P ^A , and the internal pressure of the inspection site B will be referred to as P ^B . Also, the atmospheric pressure outside the workpiece W, that is, the external atmospheric pressure is denoted as ^P0 .

Next, after leaving the inspected parts A and B filled with air for a predetermined time, the internal pressures of the inspected parts A and B are measured.
If there is a leak in the site to be inspected, the sealed air leaks out when the site is left to stand for a predetermined time, so the internal pressure of the site to be inspected fluctuates.
Therefore, when the change in the internal air pressure before and after the test sites A and B are left still for a predetermined time exceeds a predetermined amount, it can be determined that there is a leak in the test site.
The leak test method according to the prior art determines whether or not there is a leak in the inspected portion by such a configuration.

Here, the detection accuracy of the leak test method according to the prior art depends on the inspection pressure, that is, the difference between the internal pressure of the test site and the pressure of the leak destination. Specifically, when there is a leak, the higher the test pressure, the higher the leakage speed of the sealed air. In other words, the leak detection accuracy improves as the inspection pressure increases.

Assuming that the inspection pressure of the portion A to be inspected against the outside of the work W is ^QA , and the inspection pressure of the portion B to be inspected against the outside of the work W is ^QB , the following equations (1) and (2) are established. However, it is assumed that ^QA takes a larger value than ^QB .
P ^A =P ⁰ +Q ^A Expression (1)
P ^B =P ⁰ +Q ^B Expression (2)

However, the inspection pressures ^QA and ^QB are values determined in advance based on the required leak detection accuracy for the parts A and B to be inspected, respectively. As described above, the higher the inspection pressures ^QA and ^QB, the higher the leak detection accuracy, but the cost required for the leak test also increases accordingly.

Here, there may be an internal leak in the inspection sites A and B, that is, a leak that communicates the inspection sites A and B with each other. The internal leak inspection pressure ^QC can be expressed as the following equation (3) from equations (1) and (2).
^QC = ^QA - ^QB Expression (3)

The internal leak test pressure ^QC is expressed as the difference between the test pressure ^QA and the test pressure ^QB as shown in equation (3). Therefore, it was difficult to set the inspection pressure high, and there was a problem that the inspection accuracy could not be improved.

Further, when there is an internal leak between the inspected parts A and B, and there is a leak to the outside of the work W at the inspected part B having a low internal pressure, the leakage from the inspected part A having a high internal pressure to the inspected part B On the other hand, there is also a problem that air is supplied, and the detection accuracy of leakage from the inspected portion B to the outside of the work W is lowered.

As a result of intensive studies, the inventors of the present application made the internal pressure of the first inspection site higher than the external pressure of the work, set the internal pressure of the second inspection site lower than the external pressure of the work, and The inventors have found that these problems can be solved by detecting variations in the internal pressure of the second site to be inspected.

(First embodiment)
<Configuration of leak test device>
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A leak test method according to the first embodiment is performed by a leak test apparatus. First, the configuration of the leak test device will be described.

It should be noted that the object to be inspected in this embodiment is assumed to be the work W described in (Leak Test Method and Problems Related to Conventional Art), that is, the work W shown in FIG.
Further, the codes P ^A , P ^B , P ⁰ , Q ^A , Q ^B , and Q ^C used in (Leak test method and problem according to conventional technology) are still used with the same definitions, but the formula (2 ) and (3) do not hold in this embodiment.

FIG. 2 is a schematic cross-sectional view showing the configuration of the leak test device according to the first embodiment.
The leak test apparatus 1 according to the first embodiment includes a chamber 11, an inspection table 12, a chamber seal 13, seal rubbers 14a-14c, actuators 15a-15c, leak sensors 16a and 16b, regulators 17a and 17b, and an air supply source 18. Prepare.

Hereinafter, the seal rubbers 14a to 14c, the actuators 15a to 15c, the leak sensors 16a and 16b, and the regulators 17a and 17b are simply referred to as the seal rubber 14, the actuator 15, the leak sensor 16, and the regulator 17, respectively, unless otherwise distinguished. do.

The chamber 11 is a box-shaped case that covers the workpiece W, and has a seal rubber 14 and an actuator 15 inside. A leak sensor 16 and a regulator 17 are connected to the outside of the chamber 11 , and air is supplied from an air supply source 18 to the inside via the leak sensor 16 a and the regulator 17 .

The chamber 11 constitutes a space capable of accommodating the workpiece W together with the inspection table 12 and the chamber seal 13 . The space is hermetically sealed, and the atmospheric pressure can be changed by air supplied from the air supply source 18 . The atmospheric pressure of the space corresponds to the atmospheric pressure outside the workpiece W, that is, the external atmospheric pressure ^P0 .

The inspection table 12 is a table for supporting the bottom surface of the workpiece W and the chamber 11 .
Also, the chamber seal 13 is a seal for filling the gap between the chamber 11 and the examination table 12 to ensure hermeticity, and is, for example, a rubber ring.
The inspection table 12 and the chamber seal 13 together with the chamber 11 constitute a space capable of accommodating the workpiece W described above.

The seal rubber 14 is a rubber component attached inside the chamber 11 and attached to the actuator 15 . The seal rubber 14 is pressed against the openings of the inspected parts A and B of the workpiece W by the actuator 15 . The inspected parts A and B are sealed by pressing the seal rubber 14 against the openings.

The seal rubber 14a is pressed against one of the openings of the site A to be inspected, and can enclose the air supplied from the air supply source 18 inside the site A to be inspected. The internal pressure ^PA of the inspected portion A is adjusted by the air enclosed from the seal rubber 14a.

The actuator 15 is a device having a power source such as a motor inside, and presses the seal rubber 14 against the openings of the parts A and B to be inspected.

Although three each of the seal rubbers 14 and the actuators 15 are described in this embodiment, the seal rubbers 14 and the actuators 15 correspond to the total number of openings of the parts A and B to be inspected.

Leak sensors 16a and 16b are devices for detecting changes in air pressure, and are connected to seal rubbers 14a and 14b via chamber 11 and actuator 15, respectively.
The leak sensors 16a and 16b detect changes in the internal pressures P ^A and P ^B of the inspection sites A and B, respectively, and determine that there is a leak when the amount of change in the pressure exceeds a predetermined value. .

However, the leak sensor 16 may only measure the internal pressures P ^A and P ^B. In such a case, the leak sensor 16 transmits the internal pressure P ^A and P ^B measurements to another device such as, for example, a control computer. Then, the device to which the measured value is transmitted determines whether or not there is a leak.

The regulator 17 is a device that adjusts the air supplied from the air supply source 18 to a desired atmospheric pressure. In this embodiment, the air whose pressure is adjusted by the regulator 17a is supplied to the inspection site A, and the air whose pressure is adjusted by the regulator 17b is composed of the chamber 11, the inspection table 12, and the chamber seal 13. supplied to the space. That is, the internal pressure P ^A is regulated by the regulator 17a, and the external pressure ^P0 is regulated by the regulator 17b.

Specifically, the regulator 17 adjusts the internal pressure P ^A to be higher than the external pressure ^P0 , and adjusts the internal pressure ^PB to be lower than the external pressure ^P0 .
More specifically, the regulator 17a adjusts the internal pressure P ^A so as to satisfy the following formula (4), and the regulator 17b adjusts the external pressure ^P0 so as to satisfy the following formula (5).
^PA = ^PB + ^QA + ^QB Expression (4)
^P0 = ^PB + ^QB Expression (5)

When the internal pressure P ^A and the external pressure P ⁰ are adjusted so as to satisfy the equations (4) and (5), the inspection pressure of the inspected portion A against the outside of the workpiece W is certainly ^QA , and the inspected portion B of the workpiece W The inspection pressure to the outside is ^QB .

Here, the inspection pressure ^QC for the internal leak in the inspected parts A and B can be expressed as the following equation (6) from equations (4) and (5).
^QC = ^QA + ^QB Expression (6)

As shown in equation (6), the internal leak test pressure ^QC is expressed as the sum of the test pressures ^QA and ^QB . Therefore, in the leak test apparatus according to the present embodiment, it is possible to set the internal leak test pressure ^QC high, and the internal leak detection accuracy can be improved.

Further, in this embodiment, when there is a leak between the inspected portion B and the outside of the work W, air enters the inspected portion B from the outside of the work W. As shown in FIG. Therefore, even if there is an internal leak between the inspected parts A and B, the fluctuation of the internal pressure ^PB is not suppressed. In other words, the leak test apparatus according to the present embodiment can maintain accuracy in detecting leaks between the inspected portion B and the outside of the workpiece W regardless of whether there is an internal leak between the inspected portions A and B. .

The air supply source 18 is, for example, a high-pressure gas cylinder, and supplies pressurized air to the regulator 17 .
The gas supplied by the air supply source 18 is not limited to air. The gas supplied by the air supply source 18 may be, for example, an inert gas such as nitrogen or argon, or any gas that does not corrode the workpiece W.

<Leak test method>
Next, the operation of the leak test apparatus according to this embodiment, that is, the leak test method according to this embodiment will be described in detail.

FIG. 3 is a schematic cross-sectional view showing the leak test apparatus during execution of the leak test.
As shown in FIG. 3, the workpiece W undergoing the leak test is sealed in a space composed of a chamber 11, an inspection table 12, and a chamber seal 13. As shown in FIG.
Also, the inspected parts A and B are sealed by pressing a sealing rubber 14 against the openings.

FIG. 4 is a flow chart showing the operation of the leak test device according to the first embodiment.
Note that FIG. 3 will be referred to as appropriate in the following description.

First, the internal pressure ^PA of the inspection site A is adjusted higher than the external pressure ^P0 (step ST1).
Specifically, the pressure of the air supplied by the air supply source 18 is adjusted by the regulator 17a, and the leak sensor 16a, the chamber 11, the actuator 15a, and the seal rubber 14a are sealed in the inspection site A, The internal pressure ^PA is made higher than the external pressure ^P0 .
More specifically, the regulator 17a adjusts the air pressure to the value of the internal pressure ^PA represented by the formula (4) and encloses it in the inspection site A, thereby adjusting the value of the internal pressure ^PA . do.

Next, the external air pressure ^P0 is adjusted to be higher than the internal air pressure ^PB of the site to be inspected B (step ST2). In other words, the internal pressure ^PB of the inspection site B is made lower than the external pressure ^P0 .
Specifically, the pressure of the air supplied by the air supply source 18 is adjusted by the regulator 17b, and the air is enclosed in the space composed of the chamber 11, the examination table 12, and the chamber seal 13 via the chamber 11. , the external pressure ^P0 is made higher than the internal pressure ^PB .
More specifically, the regulator 17b adjusts the air pressure to the value of the outside air pressure ^P0 represented by equation (5), and seals the air in the space composed of the chamber 11, the inspection table 12, and the chamber seal 13. By doing so, the value of the outside air pressure ^P0 is adjusted.

The execution order of steps ST1 and ST2 may be reversed. Moreover, step ST1 and step ST2 may be executed in parallel.

Next, after leaving the inspected parts A and B to stand still for a predetermined time (step ST3), the leak sensor 16 detects fluctuations in the internal pressures P ^A and P ^B of the inspected parts A and B (step ST4). . Then, the leak sensor 16 determines whether or not the variation of the internal pressures P ^A and P ^B is equal to or greater than a predetermined value (step ST5).
However, the step of detecting variations in the internal pressures ^PA and ^PB (step ST4) is performed independently for the internal pressures ^PA and ^PB .

If the fluctuations of the internal pressures P ^A and P ^B are equal to or greater than a predetermined value, the leak sensor 16 determines that there is a leak (step ST6), and terminates the series of operations. Also, if the fluctuations of the internal pressures P ^A and P ^B are not equal to or greater than a predetermined value, the leak sensor 16 determines that there is no leak (step ST7), and terminates the series of operations.

As described above, the leak test method according to the present embodiment makes the internal pressure P ^A higher than the external pressure P ⁰ and makes the internal pressure P ^B lower than the external pressure P ⁰ .
With such a configuration, the inspection pressure ^QC for the internal leak is represented as the sum of the inspection pressures ^QA and ^QB , so it is possible to set the inspection pressure ^QC high. can be improved.
In addition, since the internal pressure ^PB is lower than the external pressure ^P0 , if there is a leak between the inspected portion B and the outside of the work W, air enters from the outside of the work W toward the inspected portion B. In this case, even if there is an internal leak between the inspected parts A and B, the fluctuation of the internal pressure ^PB is not suppressed. can be done.

(Other embodiments)
In the first embodiment, air is sealed in the space composed of the chamber 11, the inspection table 12, and the chamber seal 13, and the value of the external pressure ^P0 is increased to increase the internal pressure ^PB to the external pressure P made lower than ⁰ .
However, the internal pressure ^PB may be made lower than the external pressure ^{P0 by reducing the value of the internal pressure PB by} making the inside of the inspection site B negative.
When negative pressure is applied to the inside of the site to be inspected B to make the internal pressure P ^B lower than the external pressure P ⁰ , the internal pressures P ^A and P ^B are expressed by Equation (1) and Equation (7) below.
P ^B =P ⁰ -Q ^B Expression (7)
Note that even when the internal pressures P ^A and P ^B are represented by the formulas (1) and (7), the internal leak inspection pressure Q ^C is represented as the sum of the inspection pressures Q ^A and Q ^B. .
Such a configuration can also improve the leak detection accuracy.

As described above, the present invention has been described with reference to the above embodiments, but the present invention is not limited to the configurations of the above embodiments. It goes without saying that various modifications, modifications, and combinations that can be made are included.

1 leak test device 11 chamber 12 inspection table 13 chamber seals 14, 14a, 14b, 14c seal rubbers 15, 15a, 15b, 15c actuators 16, 16a, 16b leak sensors 17, 17a, 17b regulator 18 air supply source W works A, B Site to be inspected

Claims (1)

A work leak test method comprising a first inspected portion to be inspected for the presence or absence of a leak, and a second inspected portion that may communicate with the first inspected portion, comprising:
making the internal pressure of the closed first inspection site higher than the external pressure of the workpiece;
making the internal pressure of the closed second site to be inspected lower than the external pressure of the workpiece;
detecting changes in the internal pressure of the first and second inspection sites;
leak test method.

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