JPH02242131A - Method and apparatus for leakage - Google Patents

Abstract

PURPOSE:To enable the implementing of a leak inspection varied in leak criterion continuously with one equipment by providing with a diameter varying orifice on a piping for detecting gas connecting an inspection chamber and a gas detector to keep a gas flow rate constant regardless of an amount of leakage. CONSTITUTION:A product 1 which has chambers 1a and 1b different in leak criterion is set on an inspection chamber 2. Connecting hoses 7a' and 7b' are connected and valves 8, 5a and 5b are opened and the chambers are evacuated with a vacuum pump 10 and an exhausting device 3. Then, all valves are closed. Subsequently, a valve 6a is opened to inject a helium gas into the chamber 1a with a gas injector 4. When any leak exists, the leaked gas is introduced to a detector 12 through a valve 13 and a piping 11 for detecting gas and after an inspection ends, the valves 6a and 13 are closed while those 5a and 8 are opened to restore vacuum. Likewise, the chamber 1b is inspected. Here, an opening of an orifice 25 is changed to be larger or smaller depending on whether the criterion is strict or gentle to keep a flow rate almost constant.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a leak testing method and apparatus for testing leaks in hollow airtight products.

``Prior art and its problems'' Conventionally, there has been a leakage inspection method and method for inspecting leakage of hollow airtight products such as automobile radiators, evaporators, oil coolers, or refrigerator compressors using helium gas, halogen gas, etc. Various proposals have been made regarding the device.

The outline of the leakage method using helium gas, etc. is as follows: The airtight product to be tested for leakage is set in the inspection chamber, the air inside the airtight product is suctioned and evacuated, and the inside of the inspection chamber is vacuumed by suction with a vacuum pump. A leak test is performed by injecting a leak test gas into the air inside the airtight product and guiding the gas leaking into the test chamber to a gas detection device. The gas detection device detects gas introduced into an analysis tube by ionizing it with a filament and analyzing it.

However, in the leak detection method and apparatus using helium gas, etc., the leak detection criteria are different;
For example, no leak testing method or device has been proposed that can first perform a small leak test and then perform a leak test for a large amount of leak with relaxed leakage criteria using the same device.

The reason for this is that if leak tests are performed consecutively using the same leak test device with different leak judgment criteria, a large amount of gas will be probed into the analysis tube when testing a large leak amount, and the gas will be removed before the next test. There is a risk that the remaining gas may remain in the analysis tube and raise the pack gland for gas detection, causing the remaining gas to be detected in the next test and causing a false diagnosis. Therefore, an appropriate leak test must be performed. This is because it is not possible.

For this reason, it is divided into two chambers, such as in a water-cooled oil cooler, and one chamber is required to perform micro-leak inspection with strict leakage criteria, while the other chamber has looser leakage criteria. When a leak test for a large leakage amount is required, a small leak test is performed using a leak test device that uses helium gas, etc., and a leak test for a large leakage amount is performed using a so-called water tank in which air bubbles are placed 1 m in a water tank. ing. If a water tank is used, a drying process is required to dry the inner space of the airtight product, which increases the number of man-hours and reduces productivity.

In addition, preparing a leak detection device that uses helium gas or the like for each different leakage determination standard not only requires a large amount of equipment costs, but also requires more than twice the man-hours to set and remove airtight products from the leak detection device. 6. ``Problems to be Solved by the Invention'' The present invention has been made to solve the above-mentioned problems. It is an object of the present invention to provide a leak testing method and device that can perform leak testing with different standards continuously using the same device by keeping the gas flow rate guided to the gas detection device constant.

``Means for Solving the Problems'' A method that is a specific means to achieve the above purpose is to set an airtight product, which is the subject of a leak test, in an inspection room, suck and exhaust the air inside the airtight product, and then place it inside the inspection room. In the leak detection method, the gas for leak detection is injected into the air inside the airtight product after being suctioned by a vacuum pump to create a vacuum, and the gas leaking into the inspection chamber is guided to a gas detection device to perform a leak test. The flow rate of the gas leaked into the chamber is adjusted in the path leading to the gas detection device, so that a substantially constant flow rate of gas is guided to the gas detection device, and leak tests with different leakage criteria are successively performed. The device is characterized in that it can be carried out by
An inspection room where airtight products to be tested for leakage are set;
an exhaust device that suctions and exhausts the air inside the airtight product set in the inspection chamber, a gas injection device that injects a gas for leakage testing into the air inside the airtight product, and a vacuum pump that vacuums the inside of the inspection chamber by suctioning the airtight product. , a leakage detection device comprising a gas detection device that guides and detects gas leaking into a vacuum inspection chamber through gas detection piping, the gas detection piping connecting the inspection chamber and the gas detection device; The invention is characterized in that a variable diameter orifice whose diameter can be changed according to different leakage determination criteria is installed.

According to the method which is the specific means described above, the gas flow rate is adjusted in the path leading to the gas detection device, and a substantially constant gas flow rate can be guided to the gas detection device regardless of the amount of gas leakage. It is possible to carry out consecutive leak tests with different leak judgment criteria.

Furthermore, according to the device as the specific means, a variable diameter orifice is interposed in the gas detection piping connecting the inspection room and the gas detection device, so that the diameter can be changed according to different leakage determination criteria. Accordingly, the gas flow rate guided to the gas detection device can be kept almost constant.

"Example" An example of the leak testing method and apparatus of the present invention will be described.

FIG. 1 is a basic circuit diagram of a leak testing device that implements the method of the present invention.

The airtight product 1, which is an object to be tested for leakage, has a first chamber 1a in which a micro-leakage test with strict leakage criteria is carried out, and a second chamber 1b in which a leakage test with gentle leakage criteria is carried out. An example of the airtight product 1 having the first chamber 1a and the second chamber lb is a water-cooled oil cooler for automobiles, where the first chamber 1a corresponds to an oil tank and the second chamber lb corresponds to a water-cooled tank.

The airtight product 1 is set in the inspection chamber 2. The examination room 2
The first chamber 1a and the second chamber 1 of the set airtight product 1 are
Exhaust system piping 3a, 3b connected to an exhaust device 3 for exhausting air from the inner space of b, and injection system piping 4a, 4b connected to a gas injection device 4 for injecting helium gas for inspection are connected. , each of the pipes 3a, 3b and 4a, 4
Exhaust valves 5a, 5b and gas injection valve 6a in b.

6b, and is connected to the examination room 2 through common piping 7a, 7b. The common pipes 7a, 7b and the first chamber 1 of the airtight product 1
a and the second chamber 1b are connected by connecting hoses 7a'' and 7b'' for exhausting and injecting helium gas.

Further, a vacuum pump 10 is connected to the examination room 2 through a vacuum suction pipe 9 having a vacuum suction valve 8 interposed therebetween, and a gas detection device 12 is connected through a gas detection pipe 11. The gas detection pipe 11 includes a gas detection valve 13.
and a variable diameter orifice 14 are interposed in series. The gas detection device 12 uses a mass spectrometer 15 to detect helium gas guided through the gas detection piping 11 . In the mass spectrometer 15, the helium gas is detected by an analysis tube that ionizes and analyzes the helium gas taken in by a filament.

FIG. 2.3 is a sectional view and a front view showing details of the variable diameter orifice 14.

The main body of the variable diameter orifice 14 has a helium gas introduction pipe 22 formed on its lower surface and a helium gas delivery pipe 23 formed on its side surface as a sealed chamber 21, and is inserted into the gas detection pipe 11.

The inner end of the helium gas introduction pipe 22 has a large diameter orifice 2.
4, with a small diameter orifice 25 on the top surface, and a gasket 2.
6 to bring them into close contact. The small-diameter orifice 25 is supported by a pin 31 on an arm 30 that is firmly fitted to a rotating shaft 27 extending across the sealed chamber 21 with a key 28 and a set screw 29, and is rotated diagonally above the large-diameter orifice 24 by rotation of the rotating shaft 27. It is possible to evacuate to. A lever 32 is tightly fitted on the rotating shaft 27 outside the sealed chamber 21, and a piston rod 34 of a cylinder 33 is connected to the lever 32 by a pin 35.

The cylinder 33 includes a stay 3 fixed to the outside of the sealed chamber 21.
Supported by 6.

Hereinafter, the operation of the device of the present invention will be described. For the first chamber 1a of the airtight product 1, a micro leak test with strict leakage criteria is carried out, and a second test is performed for the first chamber 1a of the airtight product 1.
The chamber 1b will be explained based on a mode in which a leak test with mild leakage criteria is performed.

First, the airtight product 1 is placed in the inspection chamber 2, and the connection hose 7a connected to the first chamber 1a of the airtight product 1 is connected to the exhaust system piping 3.
a and the gas injection system piping 4a are connected to the common piping 7a, and a connecting hose 7b' connected to the second chamber 1b is connected to the common piping 7b that connects the exhaust system piping 3b and the gas injection system piping 4b. do. Subsequently, the vacuum suction valve 8 is opened, and the inside of the examination chamber 2 is vacuumed by the vacuum pump 10 via the vacuum suction piping 9 to create a vacuum state, and then the vacuum suction valve 8 is closed. Also, at the same time as the start of vacuum suction, the exhaust valve 5
Open a and 5b to open the first chamber 1a and second chamber 1b of the airtight product 1.
The chamber is evacuated by the exhaust device 3 to create a vacuum state so that the concentration of the helium gas to be injected does not change. When the exhaust is finished, the exhaust valves 5a and 5b are closed, the gas injection valve 6a is opened, and helium gas is injected by the gas injection device 4 into the first chamber 1a where a micro leakage test is performed.

At this time, if there is a leak in the first chamber 1a, helium gas leaks into the inspection chamber 2 which is in a vacuum state. The helium gas leaked into the inspection chamber 2 is detected by opening the gas detection valve 13 and passing it through the gas detection pipe 11 to the mass spectrometer 1 of the gas detection wave M12.
In this case, the cylinder 33 disposed outside the sealed chamber 21 of the variable diameter orifice 14 is driven, the piston rod 34 is extended, and the lever 34 rotates the rotating shaft 27 counterclockwise. The small-diameter orifice 25 in close contact with the orifice 24 is retracted obliquely upward. Therefore, helium gas is introduced into the sealed chamber 21 from the large-diameter orifice 24 at the inner end of the gas introduction pipe 22 without restricting its flow, and is sent from the gas delivery pipe 23 to the mass spectrometer 15 of the gas detection device 12. A slight leak in the first chamber 1a is detected by measuring the gas flow rate at a predetermined amount or more.

After the minute leakage test for the first chamber 1a is completed, the gas injection valve 6a and the gas detection valve 13 are closed.

Subsequently, the second chamber 1b of the airtight product 1 is subjected to a leakage test with mild leakage criteria. Similarly to the above, the inside of the examination chamber 2 is vacuumed to a vacuum state, and the exhaust valve 5a is opened to exhaust the helium gas injected into the first chamber la. This means that if there is a leak below the leakage criteria in the first chamber la, the first
Helium gas remaining in chamber la leaks out and enters second chamber l.
This is to avoid affecting the leakage test in step (b).

Furthermore, the exhaust valve 5b is opened to exhaust the air from the second chamber lb as well. In this way, the first chamber 1a and the second chamber 1b are evacuated to a vacuum state, so that the concentration of the newly injected helium gas does not change. 1st chamber 1a and 2nd chamber lb
After the exhaust from the chamber is completed, the exhaust valves 5a and 5b are closed, and the gas injection valve 6b is opened to inject helium gas into the second chamber lb. At this time, if there is a leak in the second chamber lb, helium gas leaks into the inspection chamber 2 which is in a vacuum state.

This helium gas is guided to the mass spectrometer 15 of the gas detection device 12 by opening the gas detection valve 13 and passing through the gas detection piping 11. In this case, if there is a leak in the second chamber 1b, the minute leakage test is performed. Since a larger amount of gas than would otherwise leak out, the piston rod 34 of the cylinder 33 placed outside the sealed chamber 21 of the variable diameter orifice 14 is contracted, and the rotating shaft 27 is rotated clockwise using the lever 34 to cause a large amount of gas to leak out. A small diameter orifice 25 is brought into close contact with the diameter orifice 24. Therefore, the flow rate of the helium gas is reduced by the small diameter orifice 25 at the inner end of the gas introduction pipe 22 to the same level as during the minute leakage test described above, and is further introduced into the sealed chamber 21 to moderate the flow rate and send out the gas. The gas is sent from the pipe 23 to the mass spectrometer 15 of the gas detection device 12, and when the gas flow rate is measured to be a predetermined amount or more, the second chamber lb
Detect leakage.

As mentioned above, micro leak inspection with strict leak judgment criteria,
The diameter of the variable diameter orifice 14 is changed in the case of a leak test with a gentle leak judgment standard, and the flow rate of helium gas guided to the mass spectrometer 15 of the leak test bag W and 12 is kept almost constant in accordance with the minute leak judgment standard. By doing so, it is possible to prevent the background from increasing or fluctuating in the mass spectrometer 15 for gas detection, and to successively perform leakage tests with different leakage criteria using the same device.

In addition, the leakage test device is systemized, and the valves installed in each pipe, etc., drive the cylinder 33 that operates the variable diameter orifice 14, and set and take out the airtight product 1, which is the object to be tested, into the inspection chamber 2. It is also possible to automatically and continuously perform leakage tests using different leakage criteria by controlling the above using a series of programs.

In the embodiment described above, a micro-leakage test with strict leakage criteria was first performed, and then a leakage test with looser leakage criteria was performed, but this order may be reversed.

However, the vacuum suction in the inspection chamber 2 and the first vacuum suction of the airtight product 1 before proceeding to the micro leakage inspection. It is necessary to carefully evacuate the second chambers 1a and 1b so that residual helium does not affect the micro-leakage test.

"Other Embodiments" FIG. 4 shows a modified embodiment of the variable diameter orifice 14.

A valve seat 43 corresponding to a fi-head conical needle valve 42 is provided on the inner end edge 41 of the helium gas introduction pipe 22 formed in the sealed chamber 21, and by moving the needle valve 42 closer to or away from each other, helium gas can be introduced. The aim is to vary the flow rate through which the The needle 44 of the needle valve 42 is made to protrude outside the sealed chamber 21, and the needle 44 of the needle valve 42 is
By operating 4 with a microcomputer-controlled servo motor (not shown), the flow rate of helium gas can be adjusted continuously and steplessly.

In FIG. 5, a plurality of branch pipes 53 each having an orifice 51 of a different diameter and a switching valve 2 interposed in the gas detection pipe 11 are provided in parallel. Open the switching valve 52 of one of the branch pipes 53 and open the other switching valve 5.
By closing 2, the flow rate of helium gas can be adjusted in stages.

Based on each of the embodiments described above, it is also possible to perform leak tests using different leakage criteria on airtight products having a plurality of chambers of second grade or higher, or on a plurality of airtight products at the same time.

In addition to helium gas, argon, freon, etc. can be used as the gas for leakage testing.

[Effects of the Invention] As clarified in the explanation of the above-mentioned specific means and operation, the leakage detection method of the present invention adjusts the gas flow rate in the path leading to the gas detection device, and detects the leakage regardless of the amount of gas leakage. Since a nearly constant gas flow rate can be guided to the gas detection device, there is no need for a large amount of gas to flow in and cause background rise or fluctuation for gas detection.
Leak tests using different leak judgment criteria can be carried out continuously in the equipment, which not only makes it possible to significantly reduce equipment costs, but also improves work efficiency.

Furthermore, as clarified in the explanation of the specific means and operation, the leakage testing device of the present invention includes a variable diameter orifice interposed in the gas detection piping that connects the testing chamber and the gas detection device. By changing the diameter according to different leakage determination criteria, the gas flow rate led to the gas detection device can be made substantially constant, and the method of the present invention can be effectively implemented.

Figure 1

[Brief explanation of drawings]

The attached drawings show embodiments of the present invention, in which Fig. 1 is a basic circuit diagram of a leak test device, Fig. 2 is a sectional view of a variable diameter orifice, Fig. 3 is a front view thereof, and Fig. 4 is a diagram of a variable diameter orifice. Modified Embodiment FIG. 5 is a part of a circuit diagram showing another modified embodiment. 11. , airtight products, 210. Laboratory, 311. Exhaust system, 3a, 3b, exhaust system piping, 4.1. Gas injection device, 4a, 4b, gas injection system piping, 10,
,,Vacuum pump, 11 ,,Gas detection piping, 12
, Gas detection device, 14, Variable diameter orifice, 21, Sealed chamber. Figure Figure

Claims (2)

[Claims] (1) Set the airtight product that is the subject of the leak test in the test chamber, suck and exhaust the air inside the airtight product, and create a vacuum by suctioning the test chamber with a vacuum pump. In a leak detection method in which a leak test is performed by injecting the gas into the air and guiding the gas leaking into the inspection chamber to a gas detection device, the flow rate of the gas is adjusted in the path leading the gas leaking into the inspection chamber to the gas detection device. A leak testing method characterized in that a substantially constant flow rate of gas is guided to the gas detection device so that leak tests with different leak determination criteria can be carried out successively. (2) An inspection chamber where the airtight product to be tested for leaks is set, an exhaust device that suctions and exhausts the air inside the airtight product set in the inspection chamber, and a gas for leak testing is injected into the air inside the airtight product. In a leak detection device, which is composed of a gas injection device, a vacuum pump that vacuums the inspection chamber by suction, and a gas detection device that guides and detects gas leaking into the vacuum inspection chamber through gas detection piping. . A leak testing device, characterized in that the gas detection pipe connecting the inspection chamber and the gas detection device is provided with a variable diameter orifice whose diameter can be changed according to different leakage determination criteria.