JP2003240667A - Leakage test method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leakage test method and a leakage inspection device improving increase in costs and problems in a vacuum form by changing to an atmospheric form and preventing drop in throughput of the device. <P>SOLUTION: This leakage test device 10 has structure in which a plurality of chambers 11 circulate required processes for the leakage test. The test device has upper and lower conveying passages 12 such as a conveyer and elevating machines 13 installed at both ends of the conveying passages 12 to form a closed conveying passage of the chambers. Instruments executing required processes of the leakage test of test target 20 housed in the chambers along the conveying passages are installed to inspect leakage during moving of the chambers. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leakage inspection method and apparatus for inspecting airtight leakage of various test works which are inspection objects by using a leakage inspection medium (tracer gas) such as helium gas.

[0002]

2. Description of the Related Art Generally, there are two types of leak inspections, one is to inspect by a pressure change caused by leakage and the other is to inspect by the amount of leaked tracer gas. Since the method based on this pressure change is easily affected by temperature and the like, a method using tracer gas is used for inspecting for minute leaks.

In this case, as shown in FIG. 2, the inspection object 2 placed in the vacuum chamber 1 is filled with helium as a tracer gas from the helium filling device 3, and helium leaks into the vacuum chamber 1 which is a vacuum. Is often conducted by a vacuum method in which a gas detector (helium leak detector) 4 is guided by mass spectrometry to perform a leak test. Reference numeral 5 is an exhaust pump of the vacuum chamber 1, and reference numeral 6 is an exhaust pump of the inspection object 2. However, when this vacuum chamber 1 is used, the vacuum pump (exhaust pump) 5 for evacuating the inside of the chamber becomes large according to the chamber volume, and the exhaust time also becomes long. Further, the vacuum chamber 1 also needs to be capable of withstanding a vacuum and having its inner surface not easily contaminated. For this reason, as the inspection object becomes larger, the cost and time will increase significantly. Furthermore, maintenance for maintaining the vacuum system is troublesome.

As an improvement of this problem, an airtightness inspection method in which the inside of the chamber is at atmospheric pressure is disclosed in Japanese Patent No. 320352.
No. 8 publication. In this airtightness inspection method, the inside of the chamber containing the inspection object is set to the atmospheric pressure state, the helium leaked from the inspection object to the atmospheric pressure is diffused and stirred for a certain period of time, and then introduced into the helium leak detector. Atmospheric pressure method. However, this atmospheric pressure method is inferior in detection power to the vacuum method (it is impossible to detect with high accuracy), and therefore the leaked helium accumulates in the chamber as the leak amount to be inspected becomes minute. However, it takes a long time to increase the concentration. Therefore, the throughput of the inspection device (the number of inspections within a fixed time) becomes lower than that of the vacuum system, and there is a problem that the number of devices increases.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. An object of the present invention is to improve the cost and maintenance problems caused by the vacuum system by using an atmospheric pressure system as a leak test. At the same time, it is an object of the present invention to provide a leakage inspection method and device capable of preventing a decrease in throughput of the inspection device due to accumulation of leaked gas.

[0006]

The present invention provides, as a means for solving the above-mentioned problems, a leak inspection method and apparatus according to each of the claims. The leak inspection method according to claim 1, wherein the inspection target is housed in a plurality of chambers circulating in the closed transfer path, and the leakage inspection of the inspection target is performed in a required process while moving in the closed transfer path. This makes it possible to improve the throughput of the inspection apparatus.

According to a second aspect of the leak inspection method, the steps required for the leak inspection are the exhaust of the chamber and the zero point check of helium, the helium filling step, the leak helium accumulation step, the stirring step in the chamber, and the leak test step. Is specified. According to the leak inspection method of the third aspect, the leak helium accumulation time is managed, whereby the leak can be accurately detected. A third aspect of the invention is an apparatus invention of the method of the first, second or third aspect, and the operation and effect thereof are the same as those of the first to third aspects.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A leak inspection method and apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically illustrates the overall configuration of the leak inspection device of the present invention. The leak inspection apparatus 10 of the present invention has a structure in which a plurality of chambers 11 containing the inspection object 20 circulate through each required process of the leak inspection. That is, the inspection apparatus 10 is provided with upper and lower transfer paths 12 made of, for example, a conveyor and elevators 13 provided at both ends of the upper and lower transfer paths 12 to form a closed transfer path for the chamber 11. ing. Fans 14 are provided above and below the closed transfer path to exhaust air around the inspection device and prevent helium from drifting around.

Along this closed transfer path, equipment is provided for carrying out the required steps of the leak test. That is, a vacuum pump 15 for exhausting the inspection object 20, a first detector (helium leak detector) 16 for detecting helium in the atmosphere, a helium encapsulator 17 for enclosing helium in the inspection object 20, an inspection object Second detector (helium leak detector) 1 for detecting the leak of helium from 20
8 and a collector 19 for collecting helium.

The operation of the inspection apparatus 10 configured as described above will be described. First, in the loading step, the inspection target 20 is loaded into the chamber 11 at a predetermined position of the closed transfer path, and the lid 11a of the chamber 11 is closed. Next, in the exhaust / zero point check process, the inspection target 20 is connected to the vacuum pump 15, the inside of the inspection target 20 is evacuated, and then the inspection target 20 is sealed. At the same time, the chamber 11 is connected to the first detector 16, and the gas in the chamber 11 is guided to the first detector 16 to obtain an output I by helium in the atmosphere.

In the internal pressure check and helium filling process, after connecting the pressure gauge P and the helium filling device 17 to the inspection object 20 that has been exhausted and sealed in the previous process, the vacuum degree check and the filling of helium with a positive pressure are performed. Stopper tightly. This vacuum degree check is performed in order to find a large leak of the inspection object 20 before the helium is filled. It is desirable to use a dense helium concentration in order to obtain high detection power (high-precision detection). The filling pressure is 20
However, the higher the value, the greater the amount of leakage per unit time and the higher the detection power.

Next, the chamber 11 containing the inspection object 20 is moved to the transfer path from the upper stage to the lower stage by the elevator 13, and the accumulation process is performed. In the accumulation step, helium leaking from the inspection object 20 is accumulated in the chamber 11.
The necessary number of steps is provided to secure detection power by taking a long accumulation time. Inspection device 1 due to some failure
When 0 stops, the accumulation time increases. In this case, since the amount of accumulation increases, the leak is detected in a large amount, so that the leak is not overlooked, but even the negligible one is detected. In order to prevent this, a storage time management recorder 21 is attached to each chamber 11 to have a recording function for management. That is, the sealing time is recorded when the helium is sealed, and the accumulation time is confirmed in the leak test process which is a subsequent process. If it is longer than the planned storage time, retest or loosen the standard.

In the stirring step, the helium leaked from the inspection object 20 is stirred by a stirring device (not shown) in the chamber 11 so as to have a uniform concentration. This stirring device can be realized by a fan or the like. For example, an electric fan may be installed in each chamber 11 to supply electric power in a stirring process, or a shaft of a fan installed in each chamber 11 may be extended outside the chamber 11 and mechanically driven from the outside. Stirring is carried out.

In the next leak test process, the inspection object 2
The gas containing helium leaked from 0 to the chamber 11 is guided to the second detector (helium leak detector) 18 to obtain an output II according to the helium concentration in the chamber 11. Output I obtained from this output II by zero check
To obtain a measured value corresponding to the leak amount of helium. Here, the output I is subtracted in order to remove the influence of the fluctuation of the helium concentration in the atmosphere. That is, the helium used for the leak test floats around the inspection device 10, and the helium concentration in the atmosphere may change. If the amount of leakage to be inspected is not very small, output II may be used as the measured value.

In taking the difference between the output I and the output II,
First and second detectors (helium leak detector) 16
It is necessary to match the sensitivities of 18 and 18. Therefore, an appropriate control interval should be determined and calibration should be performed using helium gas with a known concentration or master leak with a known leak amount. Further, when introducing the gas in the chamber 11 to the detectors 16 and 18, it is possible to speed up the measurement by setting a negative pressure in the pipe on the detector side.

In this leak test process, if the helium-containing gas is not continuously introduced from the chamber 11 from the beginning, but it is introduced for a short time and checked for a large leak, and then continuously introduced, a large helium leak occurs. Contamination of the second detector 18 can be prevented. In the above description, helium is used as the leakage inspection gas (tracer gas), but the leakage inspection gas is not limited to this. Further, the detector is not limited to one using mass spectrometry such as a helium leak detector. That is, using carbon dioxide, methane, etc. as tracer gas,
It is also possible to use a combination of another gas and a detection method such as detecting absorption of laser light.

In the next helium recovery step, the inspection object 2
0 and the recovery device 19 are connected to recover the helium sealed in the inspection object 20. When using a high concentration of helium, it is desirable to recover the helium because it is not economical to release the used helium in-situ and causes fluctuation of the helium concentration at the atmospheric level. Even if 100% helium is used, the concentration will drop by collecting and reusing it. Therefore, set a replacement period or check the concentration and replace it with a new one.

Inspection object 20 for which helium has been recovered
Is transferred from the lower stage to the upper transfer route 12 by the elevator 13. In the taking-out step, the lid 11 a of the chamber 11 is opened and the inspection target 20 is taken out of the chamber 11.

Then, in a cleaning process, helium remaining in the chamber 11 due to leakage is removed and removed from the installation place of the inspection apparatus 10. In FIG. 1, push air 22 is blown and exhausted by the hood 14 a and the fan 14. It should be noted that this cleaning is performed before the chamber 11 is emptied or the inspection target 20 is removed from the chamber 1.
It may be flushed with air after the lid 11a is closed by putting it in the No. 1 unit. It is desirable to exhaust the periphery of the process in which the positive pressure helium is enclosed in the inspection object 20 by the fan 14. This is to prevent excessive helium from flowing into the atmosphere and drifting around the inspection device 10 due to a defective stopper or the like.

Although not shown in FIG. 1, it is desirable that the chamber 11 be provided with a check valve (not shown) on the side opposite to the suction ports of the detectors 16 and 18. The check valve opens when the pressure in the chamber 11 becomes negative, and allows outside air to enter the chamber 11. As a result, even if the airtightness is poor in the simple chamber 11 that does not require a pressure resistance, it is possible to prevent the chamber 11 that has become negative pressure due to the introduction of gas into the detector from being deformed. Further, since it works to keep the inside of the chamber 11 at the atmospheric pressure, the introduction of gas into the detector is not hindered. The check valve can also be adopted in a configuration in which the chamber 11 is not separated from other components of the inspection device. Also,
The steps described above are not limited to the arrangement shown in FIG. 1 and can be changed as appropriate.

As can be seen from the above description, in the present invention, by separating the chamber from the other components of the inspection device, one inspection device can have a plurality of chambers, and the accumulation time of leaked helium can be increased. Even if the length is increased, it is not necessary to reduce the number of processes in the device for a certain period of time. That is, by sequentially detecting the gas in the plurality of chambers, the throughput of the inspection device is not reduced. In addition, the structure is such that the chamber is circulated using the upper and lower sides of the inspection device, and its area efficiency is good (the device area can be reduced). Further, by attaching a check valve to the chamber, the pressure in the chamber can be maintained at the atmospheric pressure at the time of detection, so that the chamber may be a simple one that does not require a vacuum pressure resistance. For example, a sheet metal product or an acrylic case can also be used. Further, since it is not necessary to evacuate the inside of the chamber, the cost and time can be reduced, and the burden of maintenance of the vacuum system due to dirt on the inner wall of the chamber is also reduced. Further, by making the chamber have a recording function for managing the accumulation time of leakage, it is possible to prevent erroneous determination of leakage.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic overall configuration of a leak inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an overall configuration of a conventional helium leak inspection device using a vacuum method.

[Explanation of symbols]

10 ... (Leakage) inspection device 11 ... Chamber 12 ... Transport path 13 ... Elevator 14 ... fan 15 ... Vacuum pump 16, 18 ... (First and second) detectors 17 ... Helium enclosure 19 ... collector 20 ... Inspection object 21 ... Recorder for storage time management 22 ... Push air

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Atsushi Otani             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Yoshikatsu Yagoi             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Hironori Iwama             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F term (reference) 2G067 BB02 BB03 BB04 BB12 BB25                       CC13 DD17 DD18 EE11

Claims (4)

[Claims] 1. In a leak inspection method for inspecting a leak by enclosing a leak inspection medium such as helium in an inspection object, the inspection object is accommodated at a predetermined position in a plurality of chambers in a circulating closed transfer path. Then, during the movement in the closed transfer path, a leak test is performed on the inspection target housed in the chamber in a required process, and the inspection target is taken out of the chamber after the inspection is completed. A leak inspection method characterized by the above. 2. The required steps include exhausting the inside of the inspection object and a zero-point check of helium, enclosing the helium in the inspection object, accumulating leaked helium in the chamber, and inside the chamber. 2. The method according to claim 1, further comprising a stirring step of 1 and a leak test step of helium.
Leak inspection method described in. 3. The leak inspection method according to claim 2, wherein the storage time of the leaked helium is managed. 4. A leak inspection apparatus for performing the leak inspection method according to claim 1, 2.