JP2010266283A - Device and method for leakage test - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify a differential pressure detecting passage in a device for a leakage test which includes a temperature-sensitive member for temperature compensation. <P>SOLUTION: A chamber 13 to be inspected is formed between the inside of the internal space 11 of an inspection object 10 and the outside of the temperature-sensitive member 60 composed of a material of favorable heat conduction. After pressurized gas is introduced into each of the chamber 13 to be inspected and a temperature-sensitive chamber 61 in the temperature-sensitive member 60, first and second passages 31 and 32 are intercepted, and then a second downstream-side opening/closing means V<SB>36</SB>is closed, differential pressure D<SB>1</SB>between the chamber 13 to be inspected and a portion 36 of the second passage where pressure is checked up are detected by a differential pressure sensor 33. Besides, a first downstream-side opening/closing means V<SB>35</SB>is closed and differential pressure D<SB>2</SB>between the temperature-sensitive chamber 61 and a portion 35 of the first passage where the pressure is checked up are detected by the differential pressure sensor 33. The differential pressure data D<SB>1</SB>are compensated on the basis of the differential pressure data D<SB>2</SB>, and leakage determination is performed on the basis of the differential pressure data D<SB>1</SB>after the compensation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an apparatus and method for performing a leak test by introducing pressurized gas into an internal space to be inspected.

  In general, in a differential pressure type leak test, after a pressurized gas such as compressed air is introduced into an internal space to be inspected and a reference space, the internal space and the reference space are cut off from each other to form a closed system. When there is a leak from the inspection object, this is detected as a differential pressure. Thereby, the quality of the inspection object can be determined (see Patent Document 1).

  When pressurized gas is introduced into the internal space to be inspected, the temperature rises by adiabatic compression, and then heat is dissipated over time, and the temperature drops. Also, if the inspection object is heated or cooled and there is a temperature difference between the surrounding equipment and atmosphere, or if the pressurized gas is at a different temperature from the inspection object, the internal temperature of the inspection object will change over time. To do. Such a temperature change also causes a pressure change.

  Therefore, in the leak test method described in Patent Document 2, not only the pressure change in the internal space to be inspected but also the temperature change is measured, and correction (temperature compensation) is performed to remove the pressure change due to the temperature change. . Thereby, it is possible to improve the accuracy of the leak determination and consequently the quality determination of the inspection target.

  Specifically, for example, a heat-sensitive member having good heat conductivity is prepared. A temperature sensitive greenhouse is formed inside the temperature sensitive member. A test chamber is formed between the inner surface of the internal space to be inspected and the outer surface of the temperature sensitive member by arranging the temperature sensitive member in the internal space of the inspection target. A first differential pressure detection path including a differential pressure sensor is connected to the test chamber. A second differential pressure detection path including another differential pressure sensor is connected to the temperature sensitive greenhouse. Through these differential pressure detection paths, pressurized gas is introduced into the test room and the sensitive room. Then, the differential pressure in the test chamber with respect to the reference pressure is measured by the differential pressure sensor in the first differential pressure detection path, and the differential pressure in the temperature sensitive room with respect to the second reference pressure is measured by the differential pressure sensor in the second differential pressure detection path. taking measurement. The pressure change in the sensation greenhouse is mainly due to the temperature change in the test room. Therefore, by correcting the time-dependent data of the measured differential pressure in the test room based on the time-dependent data of the measured differential pressure in the sensitive room, it is possible to eliminate the part due to the temperature change from the pressure change in the test room. . Leakage is determined based on the corrected data. The internal pressure of the temperature-sensing greenhouse, which is a temperature-sensitive member, is highly sensitive to minute temperature changes. Therefore, the sensitivity of temperature measurement can be increased. In addition, since the temperature of the test chamber can be measured on average, reliability can be ensured even if there is a temperature distribution in the test chamber.

JP 2004-062011 A JP 2007-064737 A

  In the system of the above-mentioned patent document 2, two differential pressure detection paths for a test object and a temperature sensitive member are required, and two differential pressure sensors are required.

In order to solve the above problems, the device of the present invention is a leak test device for determining a leak from an inspection object having an internal space.
(A) a temperature-sensitive member made of a good heat-conductive material that has a temperature-sensitive greenhouse inside and is arranged so that an outer surface forms a test chamber between the inner space and the inner space;
(B) A differential pressure having a first passage that leads to the test chamber and introduces pressurized gas into the test chamber, and a second passage that leads to the temperature sensitive greenhouse and introduces pressurized gas into the temperature sensitive greenhouse. A detection path;
(C) a differential pressure sensor provided between the first passage and the second passage for detecting a differential pressure in the passages;
(D) upstream opening / closing means for blocking the first and second passages after allowing the introduction of the pressurized gas through the first and second passages upstream from the differential pressure sensor;
(E) a first downstream opening / closing means that is provided in a first passage downstream of the differential pressure sensor and that opens before the blocking and operates from opening to closing or from closing to opening after the blocking;
(F) Provided in the second passage on the downstream side of the differential pressure sensor, opened before the interruption, and closed after the interruption when the first downstream opening / closing means is open, and the first downstream opening / closing means is closed. A second downstream opening / closing means that opens when
And after the shut-off, the second downstream opening / closing means opens the differential pressure data obtained by the differential pressure sensor when the first downstream opening / closing means is open (the second downstream opening / closing means is closed). Correction is performed based on differential pressure data obtained by the differential pressure sensor when the first downstream side opening / closing means is closed), and the leakage determination is performed based on the corrected differential pressure data.

  A pressurized gas is introduced into the test chamber and the temperature sensitive room by allowing the upstream opening / closing means. Next, the first passage and the second passage are blocked from each other by the upstream opening / closing means. As a result, the examination room and the first passage are made into one closed space. The sensitive room and the second passage are made into another closed space. The temperature of the test room changes due to a temperature difference from the surrounding environment, heat dissipation after adiabatic compression, and the like. The temperature change in the test room is transmitted to the temperature sensitive greenhouse through the temperature sensitive member and appears as a pressure change in the temperature sensitive room. After the interruption by the upstream opening / closing means, the first downstream opening / closing means is opened and the second downstream opening / closing means is closed for a certain period. Thereby, the 2nd channel | path upstream from a 2nd downstream opening-and-closing means is interrupted | blocked from a sensitive room, and it does not receive to the influence of the pressure change of a sensitive room. A differential pressure sensor detects a differential pressure between the internal pressure of the second passage upstream of the second downstream opening / closing means and the internal pressure of the test chamber. This differential pressure data includes information on pressure changes in the test chamber, that is, information on leakage from the test chamber and temperature changes in the test chamber, and does not include information on pressure changes in the temperature-sensitive room. Further, for a certain period, the second downstream side opening / closing means is opened, and the first downstream side opening / closing means is closed. As a result, the first passage upstream of the first downstream opening / closing means is blocked from the test chamber and is not affected by the pressure change in the test chamber. A differential pressure sensor detects a differential pressure between the internal pressure of the first passage upstream of the first downstream opening / closing means and the internal pressure of the temperature-sensitive room. This differential pressure data includes information on the temperature change of the temperature-sensitive greenhouse, and hence the temperature change of the test room, and does not include information on leakage from the test room. Therefore, the differential pressure data when the first downstream opening / closing means is open (the second downstream opening / closing means is closed) and the difference data when the second downstream opening / closing means are open (the first downstream opening / closing means are closed) are used. By correcting based on the pressure data, it is possible to obtain differential pressure data resulting only from leakage in the test chamber. Based on the corrected differential pressure data, it is possible to determine the leakage of the test chamber. As described above, the leak test apparatus acquires the internal pressure information of the test room and the internal pressure information of the sensitive room by shifting the time. Therefore, only one differential pressure sensor is required, the differential pressure detection path can be simplified, and the cost can be reduced.

The method of the present invention is a leak test method for determining a leak from an inspection object having an internal space.
A highly heat-conductive temperature-sensitive member having a temperature-sensitive greenhouse inside is arranged so as to form a test chamber between the inner space and the inner space,
In a state where the first passage connected to the test chamber and the second passage connected to the temperature-sensitive room are in communication with each other, pressurized gas is introduced into the test room and the temperature-sensitive room through the first and second paths, respectively. And then shutting off the first passage and the second passage,
Next, the first pressure difference is detected by closing a portion of the second passage closer to the temperature sensitive room than the test pressure portion and detecting a differential pressure between the test chamber and the test pressure portion of the second passage by a differential pressure sensor. A pressure detecting step and a portion closer to the test chamber than the test pressure portion of the first passage is closed, and a differential pressure between the temperature sensing chamber and the test pressure portion of the first passage is detected by the differential pressure sensor. Performing a second differential pressure detecting step,
The differential pressure data in the first differential pressure detection step is corrected based on the differential pressure data in the second differential pressure detection step, and the leakage determination is performed based on the corrected differential pressure data.

The differential pressure data in the first differential pressure detection process is internal pressure information of the test chamber. The differential pressure data in the second differential pressure detection process is the internal pressure information of the temperature sensitive room. In the method of the present invention, the internal pressure information of the test room and the internal pressure information of the sensitive room are acquired by shifting in time. Therefore, only one differential pressure sensor is required, the differential pressure detection path can be simplified, and the cost can be reduced.
The first differential pressure detection step may be performed first, and then the second differential pressure detection step may be performed, or the second differential pressure detection step may be performed first, and then the first differential pressure detection step may be performed.

  According to the present invention, only one differential pressure sensor is required, the differential pressure detection path can be simplified, and the cost can be reduced.

1 is a circuit diagram showing a schematic configuration of a leak test apparatus according to a first embodiment of the present invention. It is a time chart which shows an example of the leak test procedure by the said leak test apparatus.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of a circuit configuration of the leak test apparatus 1. The inspection target 10 of the leak test apparatus 1 is, for example, a cylinder block of an automobile engine. The inspection object 10 has an internal space 11.

  As shown in FIG. 1, the leak test apparatus 1 includes a compressed air source 2 as a pressurized gas supply source, a differential pressure detection path 3, and an installation table 4. The compressed air source 2 can supply an air pressure of the order of several hundred kPa. The inspection object 10 is installed on the installation table 4 with the opening of the internal space 11 facing downward. The opening of the internal space 11 is blocked by the installation table 4. Although not shown, the installation table 4 is provided with a sealing member such as an O-ring that hermetically seals between the periphery of the opening of the inspection object 10 and the installation table 4.

The differential pressure detection path 3 of the leak test apparatus 1 is configured as follows.
A common path 30 of the differential pressure detection path 3 extends from the compressed air source 2. The common path 30, a common on-off valve _{V 30} and the regulator _{R 30} are sequentially provided from the upstream side. The secondary pressure of the common path 30 is adjusted by the regulator R ₃₀ . An exhaust passage 34 extends from the common passage 30 downstream from the common on-off valve V ₃₀ . An exhaust opening / closing valve V ₃₄ is provided in the exhaust passage 34. The downstream end of the exhaust path 34 is open to the atmosphere.

A first passage 31 and a second passage 32 are branched from the downstream end of the common passage 30. The first passage 31, a first upstream side switching valve V ₃₁ first downstream-side valve V ₃₅ are sequentially provided from the upstream side. The first upstream side switching valve V ₃₁ constitutes the upstream side switching means in the claims. The first downstream-side valve V ₃₅ constitutes the first downstream opening and closing means of the appended claims. A portion of the first passage 31 between the on-off valve V ₃₁ and the on-off valve V ₃₅ constitutes a first detected pressure portion 35.

The second passage 32, a second upstream side switching valve V ₃₂ second downstream-side valve V ₃₆ are sequentially provided from the upstream side. The second upstream side opening / closing valve V ₃₂ constitutes upstream side opening / closing means in the claims. The second downstream-side valve V ₃₆ constitute the second downstream opening and closing means of the appended claims. A portion of the second passage 32 between the on-off valve V ₃₂ and the on-off valve V ₃₆ constitutes a second detected pressure portion 36.

  A differential pressure sensor 33 is provided between the first passage 31 and the second passage 32. The differential pressure sensor 33 includes a first chamber 33a and a second chamber 33b. The first chamber 33a is connected to the test pressure portion 35 of the first passage 31 via the first sensor connection path 31a. The second chamber 33b is connected to the test pressure portion 36 of the second passage 32 via the second sensor connection passage 32a.

  Furthermore, a first master tank 37 is connected to the first pressure-sensitive portion 35 of the first passage 31. In this embodiment, the connection position of the first master tank 37 is the first detected pressure portion 35 on the downstream side of the differential pressure sensor 33, but the first detected pressure portion 35 on the upstream side of the differential pressure sensor 33. May be. The first master tank 37 may be omitted.

  Similarly, a second master tank 38 is connected to the second detected pressure portion 36 of the second passage 32. In the present embodiment, the connection position of the second master tank 38 is the second detected pressure portion 36 on the downstream side of the differential pressure sensor 33, but is the second detected pressure portion 36 on the upstream side of the differential pressure sensor 33. May be. The second master tank 38 may be omitted.

  The leak test apparatus 1 further includes a temperature sensitive member 60. The temperature sensitive member 60 is made of a material having good heat conductivity such as aluminum. A plurality of fins 62 are provided on the outer surface of the temperature sensing member 60. A temperature sensitive greenhouse 61 is formed inside the temperature sensitive member 60. A plurality of fins 63 are provided on the inner surface of the sensitive room 61.

  The temperature sensitive member 60 is smaller than the internal space 11 of the inspection object 10 and can be accommodated in the internal space 11. When the temperature sensitive member 60 is accommodated in the internal space 11 of the inspection object 10, the test chamber 13 is formed between the inner surface of the internal space 11 of the inspection object 10 and the outer surface of the temperature sensitive member 60. The downward opening of the test chamber 13 is closed by the installation table 4, and the test chamber 13 is sealed.

A downstream end of the first passage 31 is connected to the test chamber 13.
The downstream end of the second passage 32 is connected to the temperature sensing chamber 61 of the temperature sensing member 60.

Although illustration is omitted, the leak test apparatus 1 further includes a control means for performing a leak test method described later. The control means includes a drive circuit for the on-off valves V ₃₀ , V ₃₁ , V ₃₂ , V ₃₄ , an input / output unit including a signal conversion circuit, a ROM storing a control program, a RAM storing measurement data of the differential pressure sensor 33, It has CPU etc. which perform control operation including the leak determination (good / bad determination) of inspection object 10.

A leak test method using the leak test apparatus 1 having the above configuration will be described with reference to the time chart of FIG.
(1) Preparatory work In the preparatory work prior to the main inspection for the target 10 to be inspected for leakage, the correlation between the pressure change and the temperature change in the test chamber 13 is obtained.
(1-1) Installation Step An inspection object having the same configuration as the object 10 to be inspected in the subsequent main inspection is prepared. The inspection object 10 that has been found to have no leakage may be used, or the inspection object 10 whose leakage is unknown may be used. A pseudo work having substantially the same configuration as that of the inspection object 10 may be created and used.
Hereinafter, the inspection object 10 used in the preparatory work will be appropriately distinguished from the inspection object 10 in the main inspection by adding “X” to the reference numeral.

  As shown in FIG. 1, the inspection object 10 </ b> X is installed on the installation table 4. The temperature sensing member 60 is accommodated in the interior 11 of the inspection object 10X, and the sealed chamber 13 is formed. The first passage 31 is connected to the test chamber 13, and the second passage 32 is connected to the temperature sensitive greenhouse 61.

(1-2) closing the pressure introduction process exhaust on-off valve _{V 34,} opening the on-off valve _{V 30, V 31, V 32} , V 35, V 36. Then, several hundred kPa of compressed air (pressurized gas) is introduced from the compressed air source 2 into the differential pressure detection path 3. The compressed air is introduced into the test chamber 13 through the first passage 31 and is introduced into the temperature sensitive room 61 through the second passage 32. Thereby, as shown in FIG. 2, the internal pressure of the test chamber 13 and the temperature-sensitive room 61 becomes high. Furthermore, compressed air is also introduced into the master tanks 37 and 38.

(1-3) blocking step then closes the common opening and closing valve _{V 30.} Subsequently, the first and second upstream side on-off valves V ₃₁ and V ₃₂ are closed. Thereby, the 1st channel | path 31 and the 2nd channel | path 32 are interrupted | blocked mutually, and become each independent closed space. The internal pressure of the test chamber 13 changes over time due to air leakage, a temperature difference from the surrounding environment, heat dissipation after adiabatic compression, and the like. The pressure of the first passage 31 and the first test pressure portion 35 is equal to that of the test chamber 13 and exhibits the same behavior as the internal pressure of the test chamber 13. The temperature change in the test chamber 13 reaches the temperature-sensitive greenhouse 61 through the wall of the temperature-sensitive member 60 having good heat conductivity. As a result, the internal pressure of the sensitive greenhouse 61 changes with time. The pressure of the second passage 32 and the second pressure-inspected portion 36 is equal to that of the temperature-sensitive greenhouse 61 and exhibits the same behavior as the internal pressure of the temperature-sensitive greenhouse 61.

(1-4) 1st differential pressure detection process The 2nd downstream on-off valve _V36 is closed through an equilibration process. That is, the portion of the second passage 32 closer to the temperature sensitive room 61 than the detected pressure portion 36 is closed. As a result, the second detected pressure portion 36 is blocked from the sensitive room 61. Therefore, as shown by a two-dot chain line in the chart of “Internal pressure of the temperature-sensitive greenhouse 61” in FIG. 2, the internal pressure of the second test pressure portion 36 is influenced by the pressure change of the temperature-sensitive greenhouse 61 and the temperature change of the test chamber 13. No longer receive. Thereafter, the internal pressure of the second test pressure portion ₃₆ maintains the magnitude P ₃₆ at the time point t ₁ when the on-off valve V ₃₆ is closed. The second master tank 38 can stabilize the internal pressure P ₃₆ of the second detected pressure portion 36. The first downstream opening / closing valve _V35 is kept open.

Subsequently, the detected differential pressure of the differential pressure sensor 33 is recorded for a certain period. Hereinafter, this period is referred to as a first differential pressure detection period, and differential pressure data detected during the first differential pressure detection period is referred to as first differential pressure data. The first differential pressure data indicates a difference between the pressure in the test chamber 13 and the pressure P ₃₆ (a constant value) in the second test pressure portion 36.

(1-5) Second Differential Pressure Detection Step After finishing the first differential pressure detection period, the second downstream on-off valve V ₃₆ is opened. As a result, the second test pressure portion 36 communicates with the temperature sensitive greenhouse 61. Therefore, the internal pressure of the second test pressure portion 36 becomes equal to the internal pressure of the temperature-sensitive greenhouse 61 and thereafter varies according to the temperature change of the temperature-sensitive room 61.

Subsequently, the first downstream opening / closing valve _V35 is closed. That is, the portion closer to the test chamber 13 than the test pressure portion 35 of the first passage 31 is closed. As a result, the first test pressure portion 35 is blocked from the test chamber 13. Therefore, as shown by a two-dot chain line in the chart of “internal pressure of the test chamber 13” in FIG. 2, the internal pressure of the first test pressure portion 35 is not affected by the pressure change of the test chamber 13, and as a result It is not affected by air leakage from the examination room 13 or temperature changes in the examination room 13. Thereafter, the internal pressure of the first detected pressure portion ₃₅ maintains the magnitude P ₃₅ at the time point t ₂ when the on-off valve V ₃₅ is closed. The first master tank 37 can stabilize the internal pressure P ₃₅ of the first test pressure portion 35.

Then, the detected differential pressure of the differential pressure sensor 33 is recorded for a certain period. Hereinafter, this period is referred to as a second differential pressure detection period, and differential pressure data detected during the second differential pressure detection period is referred to as second differential pressure data. The second differential pressure data indicates a difference between the pressure P ₃₅ (constant value) of the first test pressure portion 35 and the pressure of the temperature sensitive greenhouse 61.

(1-6) Correlation acquisition process Thereafter, various conditions such as the pressure introduced from the compressed air source 2, the initial temperature of the inspection target 10X, the initial temperature of the temperature-sensitive member 60, the environmental temperature, etc. are changed, and the above (1-1 ) To (1-6) are repeated to collect first differential pressure data and second differential pressure data. Note that it is preferable to use the same inspection object 10X regardless of the above-described change in conditions.

Then, the first differential pressure data and the second differential pressure data for each sampling condition are compared to find a correlation between them.
For example, the change gradient (or differential value) of the first and second differential pressure data is calculated for each collection condition. Then, the change slope calculation value for each sampling condition is plotted on a graph with the change slope of the first differential pressure data as the vertical axis y and the change slope of the second differential pressure data as the vertical axis x. Perform linear interpolation with. As a result, it is possible to obtain a linear expression (1) representing the correlation between the first differential pressure data and the second differential pressure data.
y = a · x + b (1)
In the formula (1), a and b are constants.

  Alternatively, as described in Patent Document 1, an approximation formula using an exponential function may be established and nonlinear fitting may be performed to determine the coefficient of the approximation formula. Instead of the change gradient of the first and second differential pressure data, the first differential pressure data at a certain point in time during the first differential pressure detection period and the second difference at a certain point in time during the second differential pressure detection period. The pressure data may be picked up for each collection condition. The pickup data is plotted on a graph (see FIG. 5 of the above-mentioned Patent Document 2) in which the first differential pressure data is the vertical axis y and the second differential pressure data is the vertical axis x. Interpolation may be performed. In this case, a correlation equation equivalent to the above equation (1) is obtained.

The above correlation equation (1) can be regarded as indicating the relationship between the temperature change and the differential pressure change in the test chamber 13. Of the first term and the second term on the right side of the correlation equation (1), only the first term includes the second differential pressure data relating to the internal pressure of the temperature-sensitive room 61, and the constant b of the second term is The amount is irrelevant to the differential pressure change in the temperature sensitive room 61, that is, the temperature change in the test chamber 13. In other words, the constant b corresponds to the amount of change in the differential pressure in the test chamber 13 excluding the amount dependent on the temperature change, and in short, represents the differential pressure change component due to leakage from the test chamber 13. . Therefore, the correlation between the temperature change of the test chamber 13 and the differential pressure change component due to it alone can be expressed by the following equation (2).
y = a · x (2)
After the correlation acquisition step, the inspection object 10X is removed from the leak test apparatus 1.

(2) Main inspection Thereafter, the main inspection is performed on the object 10 to be actually inspected. Prior to the main inspection, the inspection object 10 is washed with warm washing water of about 40 ° C., for example. Thereby, the test object 10 is heated to about 40 ° C., for example. Then, substantially the same steps as the preparatory work for acquiring the correlation are sequentially executed.

(2-1) Installation Step That is, the inspection object 10 is installed on the installation table 4. The temperature sensing member 60 is accommodated in the interior 11 of the inspection object 10 to form a sealed test chamber 13. The first passage 31 is connected to the test chamber 13, and the second passage 32 is connected to the temperature sensitive greenhouse 61.
The heated heat of the test object 10 is transmitted to the temperature sensing member 60, and the temperature of the temperature sensing member 60 rises. The temperature of the inspection object 10 decreases due to heat dissipation due to a temperature difference from the surrounding environment.

(2-2) closing the pressure introduction process exhaust on-off valve _{V 34,} opening the on-off valve _{V 30, V 31, V 32} , V 35, V 36. Then, several hundred kPa of compressed air (pressurized gas) is introduced from the compressed air source 2 into the differential pressure detection path 3. The compressed air is introduced into the test chamber 13 through the first passage 31 and is introduced into the temperature sensitive room 61 through the second passage 32. Furthermore, compressed air is also introduced into the master tanks 37 and 38.

(2-3) blocking step then closes the common opening and closing valve _{V 30.} Subsequently, the first and second upstream side on-off valves V ₃₁ and V ₃₂ are closed. Thereby, the 1st channel | path 31 and the 2nd channel | path 32 are interrupted | blocked mutually, and become each independent closed space. The internal pressure of the test chamber 13 changes over time due to air leakage, a temperature difference from the surrounding environment, heat dissipation after adiabatic compression, and the like. The temperature change in the test chamber 13 reaches the temperature-sensitive greenhouse 61 through the wall of the temperature-sensitive member 60 having good heat conductivity. As a result, the internal pressure of the sensitive greenhouse 61 changes with time.

(2-4) First differential pressure detection step The second downstream side on-off valve _V36 is closed through the equilibration step. As a result, the second detected pressure portion 36 is blocked from the sensitive room 61. Accordingly, the internal pressure of the second test pressure portion 36 is not affected by the pressure change of the temperature sensing chamber 61 and thus the temperature change of the test chamber 13, and maintains the magnitude P ₃₆ at the time t ₁ when the on-off valve V ₃₆ is closed. To do. The second master tank 38 can stabilize the internal pressure P ₃₆ of the second detected pressure portion 36. The first downstream opening / closing valve _V35 is kept open. Subsequently, the differential pressure sensor 33 calculates the difference between the first differential pressure data D ₁ in the first differential pressure detection period, that is, the pressure in the test chamber 13 and the pressure P ₃₆ (constant value) in the second test pressure portion 36. Collect.

(2-5) Second Differential Pressure Detection Step Next, the second downstream opening / closing valve _V36 is opened. As a result, the second test pressure portion 36 communicates with the temperature sensitive greenhouse 61. Therefore, the internal pressure of the second test pressure portion 36 becomes equal to the internal pressure of the temperature-sensitive greenhouse 61 and varies according to the temperature change of the temperature-sensitive room 61.

Subsequently, the first downstream opening / closing valve _V35 is closed. As a result, the first test pressure portion 35 is blocked from the test chamber 13. Accordingly, the internal pressure of the first test pressure portion 35 is not affected by the pressure change in the test chamber 13, and consequently is not affected by the air leakage from the test chamber 13 or the temperature change of the test chamber 13. Thereafter, the internal pressure of the first detected pressure portion ₃₅ maintains the magnitude P ₃₅ at the time point t ₂ when the on-off valve V ₃₅ is closed. The first master tank 37 can stabilize the internal pressure P ₃₅ of the first test pressure portion 35. Then, the differential pressure sensor 33 collects the second differential pressure data D ₂ in the second differential pressure detection period, that is, the difference between the pressure P ₃₅ (constant value) of the first detected pressure portion 35 and the pressure of the temperature sensing chamber 61. To do.

(2-6) Correction process is then corrected based on the first differential pressure data _{D 1} to the second differential pressure data _{D 2} and the correlation equation (2). Specifically, to calculate the slope [Delta] D ₁ of the first differential pressure data _{D 1,} and calculates the slope [Delta] D ₂ of the second differential pressure data _{D 2.} Then, the calculated gradient ΔD ₂ of the second differential pressure data D ₂ is substituted into the variable x on the right side of the equation (2), and the differential pressure change amount a · ΔD ₂ due to the temperature change of the test chamber 13 is obtained. This differential pressure change amount a · ΔD ₂ is subtracted from the calculated gradient ΔD _{1 of} the first differential pressure data D ₁ indicating the actual internal pressure change in the test chamber 13. That is, the following formula is calculated.
ΔD _LEAK = ΔD ₁ −a · ΔD ₂ (3)
As a result, it is possible to obtain a differential pressure change amount ΔD _LEAK resulting from only air leakage among the differential pressure changes in the test chamber 13.

(2-7) Leakage determination step Based on the above-described differential pressure change amount ΔD _LEAK (corrected first differential pressure data), the leakage determination of the inspection object 10 and the pass / fail determination are performed. That is, if the differential pressure change amount ΔD _LEAK is less than or equal to the allowable limit, the inspection object 10 is determined as a non-defective product. If the differential pressure change amount ΔD _LEAK exceeds the allowable limit, the inspection object 10 is determined to be defective.

According to this determination method, since the differential pressure change due to the temperature change is removed, the accuracy of the determination can be improved.
Since the temperature change of the test chamber 13 is measured in terms of pressure, it can be reliably detected even if the temperature change is minute. For example, if the initial pressure is 500 kPa and the initial temperature is 25 ° C., and this temperature is changed by + 0.1 ° C., the pressure change amount is 167.8 Pa according to Boyle's law. Therefore, a large pressure change can be obtained with respect to a minute temperature change. Thereby, temperature measurement can be performed with extremely high sensitivity.
The volume of the chamber 13 to be inspected 10 can be made smaller than the volume of the internal space 11 by the volume of the temperature sensitive member 60. Therefore, the degree of pressure change in the test chamber 14 with respect to the leakage flow rate from the test chamber 13 can be increased, and the leak sensitivity can be increased.
In the first differential pressure detection step, the second test pressure portion 36 serves as a reference tank that provides the reference pressure of the differential pressure sensor 33. In the second differential pressure detection step, the first test pressure portion 35 serves as a reference tank that provides the reference pressure of the differential pressure sensor 33. The leak test apparatus 1 acquires the internal pressure information of the test chamber 13 and the internal pressure information of the sensation greenhouse 51 in a time-shifted manner, and only one differential pressure sensor 33 is required. It can be simplified and the product cost can be reduced.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the embodiment, after the first differential pressure detection step is executed, the second differential pressure detection step is executed. However, after the second differential pressure detection step is executed, the first differential pressure detection step is executed. You may decide.
The temperature-sensitive member 60 only needs to be arranged so as to form the test chamber 13 between the inner surface 11 of the inspection object 10 and is not limited to being housed in the inner space 11 of the inspection object 10, It may be arranged so as to be directed to the outer surface of the inspection object 10 and close the opening of the internal space 11 to the outer surface.

DESCRIPTION OF SYMBOLS 1 Leak test apparatus 10 Inspection object 10X Correlation acquisition inspection object 11 Internal space 13 Test chamber 2 Compressed air source (pressurized gas supply source)
3 Differential pressure detection path 30 Common path 31 First path 31a First sensor connection path 32 Second path 32a Second sensor connection path 33 Differential pressure sensor 33a First chamber 33b Second chamber 34 Exhaust path 35 Test of the first path Pressure portion 36 Pressure detection portion 37 in second passage First master tank 38 Second master tank 60 Temperature sensing member 61 Temperature sensing chamber 62, 63 Fin D ₁ First differential pressure data (differential pressure data in the first detection step)
D ₂ second differential pressure data (differential pressure data in the second detection step)
R ₃₀ regulator V ₃₀ common on-off valve V ₃₁ first upstream side on-off valve (upstream side on-off means)
V ₃₂ 2nd upstream side opening / closing valve (upstream side opening / closing means)
V ₃₄ exhaust on-off valve V ₃₅ first downstream on-off valve (first downstream on-off means)
V ₃₆ second downstream side switching valve (second downstream opening and closing means)

Claims (2)

In a leak test apparatus for judging leakage from an inspection object having an internal space,
(A) a temperature-sensitive member made of a good heat-conductive material that has a temperature-sensitive greenhouse inside and is arranged so that an outer surface forms a test chamber between the inner space and the inner space;
(B) A differential pressure having a first passage that leads to the test chamber and introduces pressurized gas into the test chamber, and a second passage that leads to the temperature sensitive greenhouse and introduces pressurized gas into the temperature sensitive greenhouse. A detection path;
(C) a differential pressure sensor provided between the first passage and the second passage for detecting a differential pressure in the passages;
(D) upstream opening / closing means for blocking the first and second passages after allowing the introduction of the pressurized gas through the first and second passages upstream from the differential pressure sensor;
(E) a first downstream opening / closing means that is provided in a first passage downstream of the differential pressure sensor and that opens before the blocking and operates from opening to closing or from closing to opening after the blocking;
(F) Provided in the second passage on the downstream side of the differential pressure sensor, opened before the interruption, and closed after the interruption when the first downstream opening / closing means is open, and the first downstream opening / closing means is closed. A second downstream opening / closing means that opens when
Differential pressure data obtained by the differential pressure sensor when the first downstream opening / closing means is open after the shut-off, and differential pressure data obtained by the differential pressure sensor when the second downstream opening / closing means is open. A leak test apparatus, wherein the leak determination is performed based on the differential pressure data after correction. In a leak test method for determining a leak from an inspection object having an internal space,
A highly heat-conductive temperature-sensitive member having a temperature-sensitive greenhouse inside is arranged so as to form a test chamber between the inner space and the inner space,
In a state where the first passage connected to the test chamber and the second passage connected to the temperature-sensitive room are in communication with each other, pressurized gas is introduced into the test room and the temperature-sensitive room through the first and second paths, respectively. And then shutting off the first passage and the second passage,
Next, the first pressure difference is detected by closing a portion of the second passage closer to the temperature sensitive room than the test pressure portion and detecting a differential pressure between the test chamber and the test pressure portion of the second passage by a differential pressure sensor. A pressure detecting step and a portion closer to the test chamber than the test pressure portion of the first passage is closed, and a differential pressure between the temperature sensing chamber and the test pressure portion of the first passage is detected by the differential pressure sensor. Performing a second differential pressure detecting step,
A leak test characterized in that the differential pressure data in the first differential pressure detection step is corrected based on the differential pressure data in the second differential pressure detection step, and the leakage determination is performed based on the corrected differential pressure data. Method.

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