JPH07113592B2 - Leakage inspection method and device for sealed container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention fills a glass bottle or a plastic bottle with food, beverage, etc., and uses a metal or plastic screw lid or caulking lid, or winding or heat sealing. The present invention relates to a leak inspection method for a sealed container and an apparatus therefor.

[Prior Art] If the hermetically sealed state is impaired due to a defect in the lid or bottle mouth of the hermetically sealed container, or poor fitting or adhesion between the two, the contents may be altered or spoiled. For this reason, products with poor hermeticity must be reliably removed by inspection as defective products.

Conventionally, as a leakage inspection method for such a sealed container, there is a method of electromagnetically or optically non-contact measuring the change amount of the lid top surface due to the pressure change in the container (subject) due to poor sealing or Similarly, a method is known in which the natural frequency of the top surface of the lid changes, and is measured by the frequency of the sound generated by the impact.

However, these conventional methods are premised on that the pressure inside the container is different from the pressure in the external environment, and like the aseptic filling that has been recently researched, the contents are filled at room temperature and the pressure difference between the inside and the outside of the container is reduced. If it does not occur, even if the sealing property is poor, the pressure in the container does not change, so that such a container could not be used as the subject.

In this way, as a leak inspection method when the internal pressure of the subject does not differ from the external pressure, conventionally, it is used for leak inspection of unfilled empty cans and plastic containers, gas appliances, piping parts or automobile parts. There is a way.

According to this method, the outside of the subject is pressurized or depressurized, and after holding for a certain period of time, the pressure fluctuation caused by the poor sealing is measured to determine the leakage. However, even if it is said that the sealing is defective, in general, there is an extremely small gap, and the amount of pressure fluctuation due to the sealing failure is extremely small with respect to the external pressing force (pressure reducing force). In some cases, the amount of pressure fluctuation was smaller than the variation in), and the sealing failure could not be detected.

Therefore, conventionally, as shown in FIG. 5, a master 506 serving as a reference is generally prepared, and a differential pressure between the master 506 and the subject 507 is measured to detect a sealing failure.

That is, the branch pipe 501 is connected to the pressure supply pump 500,
The master 506 and the subject 507 are attached to the ends of the respective branch paths 501a and 501b via the on-off valves 502 and 503 and the airtight connectors 504 and 505.
And a differential pressure gauge 508 between each branch 501a and 501b.
Are connected. As the master 506, a reference container having the same volume as the subject 507, another subject, or the like is used.

The inspection method is as follows.First, the master 506 and the subject 507 are connected to the branch passages 501a and 501b with the on-off valves 502 and 503 closed, and then the on-off valves 502 and 503 are opened to apply compressed air to both the master 506 and the subject 507. Is supplied, and the on-off valves 502 and 503 are closed when the respective pressures reach equilibrium. Then, after holding for a certain period of time, the measurement value of the differential pressure gauge 508 is read. At this time, if the test object 507 is a normal product with no leakage, no differential pressure is generated, but if leaked, the pressure on the test object 507 side is reduced by that amount, and thus a differential pressure is generated and it is determined that the product is defective. It

It should be noted that instead of supplying pressure to the master 506 and the subject 507, a method of similarly vacuum-suctioning these to obtain a differential pressure has also been performed.

[Problems to be Solved] In order to obtain high reliability in the above-described conventional leak inspection method (FIG. 5), after supplying compressed air, the master 506
And the pressure inside the object 507 must be balanced. For that purpose, it was necessary to take a sufficiently long time to supply the compressed air. In particular, when the inspection device as shown in FIG. 5 is used, compressed air is supplied to the master 506 and the subject 507 via separate on-off valves 502 and 503, so that the air resistances of both are not necessarily the same. Master 50 again
The volumes of 6 and subject 507 are also not the same due to product variations. As a result, it takes a long time to reach equilibrium, which violates the demand for rapid inspection.

In addition, in order to automate the inspection and make it continuous, the inspection device shown in FIG. 5 may be used by incorporating it into a rotating mechanism in a bottle filling production line or the like. That is, slide valves are provided at the portions indicated by broken lines AA and BB in the figure, and airtight connectors 504 and 505 are incorporated into the rotating mechanism so that containers that are continuously fed can be mounted one after another. On the other hand, by installing components such as the pressure supply source 500 and the differential pressure gauge 508 outside the rotation mechanism, the master 506 and the subject 507 are sequentially supplied to the pressure supply source 500 via the slide valve.
It is configured to be connected to a differential pressure gauge 508 or the like so that leakage inspection can be performed.

However, due to the structure of the slip valve, if too much pressure is applied, leakage occurs at the slip portion. Therefore, in the conventional method of measuring the differential pressure by equilibrating in a large pressure state, the slip valve leaks during the measurement, resulting in an erroneous judgment, that is, the leakage from the slip valve is different even though it is a good product. Appears under pressure, defective product (leakage container)
There was a risk that I would judge.

In order to prevent such erroneous detection, it is necessary to add an on-off valve between the slide valve and the airtight connectors 504, 505 to increase airtightness. It took a long time to supply and equilibrate the air, and it was not possible to speed up the inspection.

Further, since the hermetically sealed container as the subject mainly accommodates foods, beverages, etc., the compressed air to be supplied is required to be sanitary and clean. However, a general compressed air supply pump often has a drain containing water and oil mixed therein, and the drain is sometimes supplied together with the compressed air, which may contaminate the surface of the subject 507. .

On the other hand, if the master 506 and the subject 507 are suctioned by vacuum, the above problem does not occur. However, if the subject 507 is a semi-rigid plastic bottle and there is an extremely large leak in the bottle or bottle, most of the air present in the head space inside the bottle will be sucked out. For this reason, the inside of the bottle is greatly decompressed, and the bottle is crushed by the atmospheric pressure, so that the inspection device may suck the contents and cause a failure.

The method of the present invention has been made to solve the above-mentioned problems, and can perform leak inspection of sealed containers quickly and with high reliability, and also has high reliability even when the inspection is automated and continuous. It is an object of the present invention to provide a method for inspecting leaks in a sealed container capable of maintaining the property.

In addition, the device of the present invention can perform leak inspection of a sealed container quickly and with high reliability, and can also support automation and continuation of inspection while maintaining high reliability. An object of the present invention is to provide a leak inspection method for a hermetically sealed container, which can prevent the subject from being contaminated by the drain from the pump and can prevent the inconvenience of sucking even the contents of the subject by vacuum suction.

[Means for Solving the Problems] In order to achieve the above object, the method for inspecting leakage of a sealed container according to the method of the present invention generates a pressure difference between the inside of the subject by pressurizing or depressurizing the outside of the subject. In the method for inspecting the leakage of the sealed container by detecting the pressure change outside the subject based on the poor sealing, pressurizing or depressurizing the outside of the subject by moving the piston in the cylinder by a certain amount, After holding this state for a certain period of time, the piston is returned to its original position, and when the piston returns to its original position, the pressure outside the subject is measured to determine leakage.

Further, the leak inspection device for a sealed container according to the device of the present invention includes an inspection pocket for hermetically accommodating the whole or a part of the subject, a cylinder communicating with the pocket, and a movement in the cylinder to move the inside of the inspection pocket. Piston for pressurizing or depressurizing, a pressure sensor for measuring the pressure in the inspection pocket, and a pressure sensor located between the inspection pocket and the pressure sensor for connecting or resetting the inspection pocket and the pressure sensor. And a switching valve for opening the sensor to atmospheric pressure.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a front sectional view showing the configuration of the first embodiment of the device of the present invention. In this embodiment, as a test object, a plastic bottle 100 having a volume of 1 to 2 liters is filled with a fruit juice beverage or the like and sealed with an aluminum screw lid 101 having a diameter of 38 mm. Alternatively, a case of inspecting for leakage caused by any defect in the liner 103 provided on the inner surface of the lid will be described. The headspace 104 of the bottle 100 is about 70cc.

In FIG. 1, reference numeral 10 denotes a cup-shaped inspection pocket, which has a rubber O-ring 11 on the inner surface of the opening end, and which is a lid 101 of the subject.
And cover the collar 105 on the neck of the bottle 100.
By elastically pressing the ring 11, the chamber 10a having a small volume can be formed inside.

12 is a piston device, and inside the cylinder 13, the piston
14 is slidable in the axial direction, and absorbs air from the opening 13a as the piston 14 slides. Here, the amount of air absorbed by the piston device 12 is set to be approximately the same as that of the container in the head space 104 existing in the bottle 100 of the subject. With this setting, there is no possibility that the contents in the bottle 100 will leak out due to suction. Further, the piston 14 can be driven by a manual operation, but generally, it is automatically performed by a driving mechanism such as a cam mechanism.

The opening 13a of the cylinder 13 communicates with the opening 10b of the inspection pocket 10 through the conduit 15, and the sliding of the piston 14 can increase or decrease the pressure in the chamber 10a of the inspection pocket 10.

Further, the pipe line 15 is branched in the middle, and the branched pipe line 16 is connected to a pressure sensor 19 via an on-off valve 17 and a slide valve (switching valve) 18. The pressure sensor 19 detects the pressure in the pipe 15, and various known pressure sensors can be applied. Furthermore, a leak determination circuit is provided at the output end of the pressure sensor 19.
20 is provided, and the presence or absence of a pressure change is confirmed based on the measurement result of the pressure sensor 19 to automatically determine the leakage. The slide valve 18 is composed of a pair of connecting members 18a and 18b, the sliding surfaces of which are in pressure contact with each other by the pressing springs 21 and 21, and one connecting member 18a slides in the horizontal direction in the drawing. Further, the connection member 18a is provided with an opening hole 22. For example, after the pressure is detected, the connection member 18a is slid to make the pressure sensor 19 communicate with the opening hole 22, so that the pressure sensor 19 is enlarged. It has a structure that it is opened to the atmospheric pressure and reset. Here, the connecting member 18a and the on-off valve 17
The conduit 16 for connecting to each other is made of a flexible member and moves together when the connecting member 18a slides.

Next, an embodiment of a leak inspection method for a hermetically sealed container using the above inspection device will be described.

First, while pushing the piston 14 in the cylinder 13 to the lower end, the lid 101 portion of the subject is inserted into the inspection pocket 10 with the open / close valve 17 closed, and the bottle 100 is further pressed from below to remove the subject. The O-ring 11 is pressed against the collar 105 to form a sealed chamber 10a in the inspection pocket 10 (step 1).

Then, the piston 14 is pulled up to the upper end of the cylinder 13 by a drive mechanism (not shown) (step 2). As a result, the pressure inside the chamber 10a is reduced. For example, chamber 10
a, pipeline 15 and branched pipeline 16 (however, the range from branch point to on-off valve 17) has a total volume of 25cc, and cylinder 13
Assuming that the volume increase inside is 75 cc, the pressure inside the chamber 10a is reduced to about 57 cmHg in gauge pressure.

Hold this depressurized state for a certain time (Step 3) Bottle 10
If there is a leak due to a defect in the liner 103 or the liner 103, the air in the head space 104 in the bottle 100 leaks to the chamber 10a side during this holding time, and the pressure value in the depressurized state slightly decreases. The holding time is usually about 1 to 5 seconds.

After a certain holding time has elapsed, the piston 14 is returned to the lower end (step 4). By this operation, the depressurized state created by the lifting operation of the piston 14 is canceled. Therefore,
Normally, the inside of the chamber 10a should be at atmospheric pressure, but if there is a leak as described above, the pressure value changed due to the leakage remains, and the pressure value becomes higher than atmospheric pressure.

Then open the open / close valve 17 and slide the slide valve 18 into the chamber.
The pressure in 10a is guided to the pressure sensor 19 and the pressure value is measured (step 5). The measurement result is sent to the leakage determination circuit 20, and if the pressure in the chamber 10a is within a certain range based on the atmospheric pressure, the subject is determined to be normal, and conversely, if it exceeds the certain range, there is a leaky defective product. To determine.

Here, the force applied to the slide valve 18 is only the residual pressure generated by the leakage, which is a few tenths of that of the prior art, and the leakage hardly occurs. Even if there is a minute leak, the error caused by it is
It only reduces the output of 19 somewhat.

The on-off valve 17 used in this embodiment basically does not affect the sensitivity because it does not participate in the suction operation for inspection. In addition, the decrease in sensitivity due to leakage from the slide valve 18 begins to occur because there is an extremely large defect in the bottle or lid and the chamber 10a
This is the case when the residual pressure inside is sufficiently high. In such a case, the defect discrimination level is already exceeded,
Since the object of the present invention can be sufficiently achieved if it is determined as a defective product, the occurrence of an error does not pose a problem.

After the discrimination is completed, the subject is removed from the inspection pocket 10 and carried to the defective product removing device by a carrying device (not shown).
Then, the object determined to be a defective product is removed from the transport line, and conversely, if it is a normal product, it is carried to a post process such as a boxing process.

After completion of a series of determination operations, the on-off valve 17 is closed again, and one connecting member 18a of the slide valve 18 is slid to cause the pressure sensor 19 to communicate with the open hole 22 and be reset, to prepare for the next measurement. (Step 6).

FIG. 2 is a diagram showing the action in each step described above, that is, the relationship between the movement of the piston and the pressure state of the chamber 10a. The vertical axis of the figure relatively represents the amount of movement of the piston 14 and the pressure in the chamber 10, and the horizontal axis represents the axial tube. The pressure has a positive value in the pressure reducing direction with the atmospheric pressure being O.

In the drawings, the numbers in circles indicate the operation points of the steps described above. Further, the solid line a is the operation of the piston 14 (the suction operation is shown upward), the broken line b is the internal pressure of the chamber 10a in the case where the subject is a normal product without leakage, and the dotted line c is the case where there is slight leakage in the subject. The pressure inside the chamber 10a and the one-dot chain line d indicate the pressure inside the chamber 10a when the subject has a large amount of leakage.

First, the chamber 10a when the subject is a normal product with no leakage
The internal pressure (broken line b) slightly delays the movement of the piston 14, but substantially follows the pressure reduction, and returns to the atmospheric pressure. This delay is due to the line resistance.

Next, the pressure (dotted line c) in the chamber 10a when there is a slight leak in the subject causes a slight decrease in the decompressed state during Step 3, and the amount of decrease is the difference P from the atmospheric pressure in Step 5. Appears as ₁ .

The pressure in the chamber 10a (dashed line d) when the subject has a large amount of leakage is
However, since the air in the head space 104 leaks into the chamber 10a during that time as well, the air pressure in the head space 104 stops at a lower pressure reduction state than in the case of a normal product or a slight leakage. Then, during step 3, air further leaks from the head space 104, and finally the pressure is reduced to P ₂ . When the piston 14 is compressed from this depressurized state (step 4), the air returns to the head space 104 again, so at the time of step 5, the residual pressure in the chamber 10a smaller than P ₂ (absolute value) remains. P ₃ occurs.

As described above, if there is a leak in the subject, step 5
Pressure P ₁ or P ₃ is a chamber at the time of pressure measurement
Since it remains in 10a, leakage can be detected by detecting this residual pressure.

Next, an experimental example performed by the present invention will be described.

The above-mentioned plastic bottle is used as the reference sample.
Using a sealed container consisting of 100 and lid 101, the center of the top surface of lid 101 is cut off, and a 0.2 mm thick stainless steel plate with a 50 micron diameter round hole formed by electron beam processing is attached to that part did.

There are a wide variety of naturally occurring leak paths and shapes, and it is difficult to quantify the relationship between them and the deterioration of the contents due to the invasion of fungi, but the leak location is smaller than the round hole with a diameter of 50 microns. In this case, it is empirically known that the deterioration of the contents due to the invasion of bacteria is negligibly small. Therefore, if the leak can be reliably detected with the above reference sample, practically sufficient reliability can be obtained. it can.

The amount of air leaking from the 50-micron-diameter round hole formed in the above reference sample was measured by water displacement, and it was 0.4 cc / sec when the pressure acting on the round hole was 50 cmHg. The amount of the leaked air is accumulated in the chamber having a volume of 25 cc, and the pressure increases, which is 16 g / cm ² per second.

The pressure sensor is the most sensitive maximum measured value 20 among the end-face diaphragm type commercially available products whose internal volume can be ignored.
Choose 0g / cm ² and pressure resistance of 400g / cm ² , 10% of which is 20g / cm 2.
² was set to the pass / fail judgment level. In this case, step 3
Since the required holding time is 1.25 seconds, leave a margin of 1.5.
Set the hold time in seconds.

The electric signal output of the pressure sensor was set to a maximum value of 10 V and a discrimination level of 1.0 V using a dedicated amplifier. After converting into an electric signal, a discrimination result was obtained using a usual electric signal processing technique.

This determination result showed that there was a leak in the subject.

Next, an embodiment in which a leak inspection device for a sealed container according to the device of the present invention is incorporated in a line for filling the contents of the sealed container to enable continuous leak inspection (second embodiment)
Will be described with reference to FIGS. 3 and 4.

FIG. 3 is an enlarged sectional front view of a single unit of the leak inspection apparatus, and FIG. 4 is a conceptual diagram showing the overall configuration of the apparatus. The same parts as those shown in FIG. 1 are designated by the same reference numerals.

In the drawing, reference numeral 200 denotes a base of the apparatus, and a rotary base 202 is provided around a pillar 201 fixed vertically to the base 200 as an axis, and an inspection head 203 is provided on the outer periphery of the rotary base 202 at regular intervals. The examination tables 204 are attached in pairs.

The inspection head 203 is the piston device 1 described in the previous embodiment.
2 and inspection pocket 10 are integrated. Further, the upper end of the piston rod 14a of the piston device 12 is engaged with the upper cam mechanism 205, and the piston 1 has a shape corresponding to the cam shape.
Move 4 up and down. The inspection table 204 mounts the bottle 100 of the subject, and its lower end is engaged with the lower cam mechanism 206 fixed to the base 200 and is driven up and down. Reference numeral 207 is a pressing spring that biases the inspection table 204 upward.

Further, the turntable 202 includes a chamber 10a in the inspection head 203.
Pipes 15 and 16 communicating with the open / close valve 17, and a connecting member 18a of the slide valve 18 are provided corresponding to each inspection head 203. On the other hand, the support plate 208 fixed to the support shaft 201 has a slide valve
18 connecting members 18b and a pressure sensor 19 are provided.

The inspection device described above operates as follows.

As shown in FIG. 4, the bottles 100 are sent side by side in a line on the conveyor 301 in the direction of the arrow, and the timing screw
A well-known introduction mechanism using 302 and an in-feed wheel 303 carries the product as shown by an arrow i and supplies it to the inspection table 204 in an accurately positioned state. The inspection table 204 is supplied with the bottle 100 of the subject when it is in the lowered position by the lower cam mechanism 206.

Then, the inspection table 204 rises as the rotary table 202 rotates, and as a result, the lid 101 portion of the subject is inserted into the inspection pocket 10 and the collar portion 105 is operated by the pressing spring 207 to cause the O-ring 11 to move. To form a chamber 10a.

At this time, the piston 14 is at the lower end in the cylinder 13. Then, when the subject is mounted, the piston 14 is pulled up by the upper cam mechanism 205 to reduce the pressure in the inspection pocket 10. After that, while the turntable 202 makes about 5/6 rotations in the direction of arrow j, the depressurized state is maintained as it is. Bottle for subject 10
When there is a defect of 2, a defect of the lid 101, a fitting defect, or the like, the air in the head space 104 leaks into the chamber 10a in the holding section.

After passing the holding section, the piston 14 is pushed down to its original position by the upper cam mechanism 205. As a result, the depressurized state previously formed by the lifting operation of the piston 14 disappears, and only the pressure due to the air leaking from the bottle remains as the residual pressure in the chamber 10a.

The open / close valve 17 is provided with an open / close push button 17a, while
The pillar 201 is provided with a protrusion 209. The on-off valve 17 that was closed during the above-mentioned operation is opened and closed by the protrusion 209 and the push button 17a.
Is pressed to open. As a result, the residual pressure in the chamber 10a is
It is guided to the pressure sensor 19 via the slide valve 18 and its value is measured.

The electrical output of the pressure sensor 19 is input to the voltage determination device via a dedicated amplifier (not shown), and if it is equal to or higher than a preset voltage value, it is determined as a defective product. This discrimination signal is sent to the defective product discharging device 304 which divides the bottle discharged from the rotary table 202 into a good product and a defective product.

When the inspection is completed, the inspection table 204 is pushed down again by the lower cam mechanism 206, and the bottle mouth 102 portion is removed from the inspection pocket 10. At this time, since the pressure in the inspection pocket 10 is 0 or a slight positive pressure, it naturally deviates due to the weight of the bottle 100, and no compulsory operation is required.

The bottle 100 removed from the inspection pocket 10 is carried by the outlet star wheel 305 as shown by an arrow k and is transferred onto the conveyor 301. At the same time, if it is a defective product, the defective product removing device 304 uses the defective product conveyor 306. It is pushed up, and the process of one inspection head 203 is completed.

The same process is continuously performed at high speed and successively for a large number of inspection heads 203 arranged on the turntable 202. The discharged non-defective products and defective products are carried out in the directions of arrows l and m, respectively, to complete the entire inspection process.

The number of inspection heads 203 attached to the turntable 202 is
Calculated by taking into account the product of the required number of inspections per minute and the holding time per head required to obtain the required sensitivity, the vertical movement of the piston 14 and the space required for supplying and discharging the bottle 100. It

For example, if you need a throughput of 500 lines per minute, 1
With the allowance of 0%, the number of inspection heads 203 required on the rotary table 202 is calculated as 550.

Since the number of processes per second is 9.16666 and the holding time for one head is 1.5 seconds, the number of heads required for that is 13.75 for the product of the two, and 15.75 for each head for vertical operation of the piston 14. . Since it is necessary to install infeed and outlet star wheels 303 and 305 in this, and the space takes 1/6 rotation of the turntable 202, the total number of inspection heads 203 arranged around the turntable 202 is 15.75 × 6 / 5 = 18.9.

However, since this is the number of heads, it is an integer of 19. However, for the convenience of design and production, 1 for 20 pieces
It may be arranged at a good angle of 18 degrees per head.

The rotary base 202 of the apparatus of this embodiment is rotated by a drive mechanism (not shown) via the belt 210 for one rotation in 2.2 seconds.

The present invention is not limited to the above embodiment.

For example, in the above-described embodiment, the piston is operated in the suction direction, but it may be operated in the opposite direction to pressurize the inspection pocket.

In addition, as the test object, materials other than those used in the examples,
It goes without saying that various sealed containers of various sizes and shapes can be targeted.

Furthermore, when the device of the present invention is used alone, the measuring sensor may be reset by other means without using the measuring sensor resetting structure by the slide valve as shown in FIG.

[Effects of the Invention] According to the leak inspection method for a sealed container and the apparatus therefor of the present invention, the following effects can be obtained.

In the inspection method using the differential pressure between the master and the subject as in the prior art, it took a long time for the pressure between the two to reach an equilibrium state. Since no equilibration time is required, the examination can be speeded up.

There is no risk of leakage at the slide valve when the inspection is automated and continuous. That is, according to the method and apparatus of the present invention, since the pressure acting on the slide valve is only a small amount of air pressure leaked from the subject, it does not become a load enough to cause leakage. Therefore, high reliability can be obtained even when the inspection is automated and continuous.

According to the method and apparatus of the present invention, since the pressure acting on the pressure sensor is only a small amount of air pressure leaked from the subject, the pressure sensor may have a small withstand pressure, and therefore a high-sensitivity pressure sensor is used. Higher sensitivity can be achieved.

Since the apparatus of the present invention does not use the pump for supplying compressed air, it is not necessary to worry about the contamination of the subject due to the drain discharged from the pump.

[Brief description of drawings]

FIG. 1 is a front sectional view showing the constitution of the first embodiment of the device of the present invention, FIG. 2 is a pressure change diagram showing the action of the embodiment of the present invention, and FIGS. 3 and 4 are of the device of the present invention. It is a figure which shows the structure at the time of making the test | inspection which is a 2nd Example continuous.
The figure shows an enlarged cross-sectional front view of the leakage inspection device alone.
FIG. 5 is a conceptual diagram showing the overall configuration of the device, and FIG. 5 is a conceptual diagram showing a conventional example. 10: Inspection pocket, 10a: Chamber 12: Piston device, 13: Cylinder 14: Piston, 15, 16: Pipe line 17: Open / close valve, 18: Sliding valve 19: Pressure sensor, 20: Leakage discrimination circuit 100: Subject Bottle, 101: Cover of subject 104: Head space 201: Support, 202: Rotating table 203: Inspection head, 204: Inspection table

Claims (2)

[Claims] 1. A pressure difference is generated between the inside and the inside of the subject by pressurizing or depressurizing the outside of the subject, and leakage of the sealed container is detected by detecting a pressure change outside the subject due to poor sealing. In the method of inspecting, pressurizing or depressurizing the outside of the subject by moving the piston in a fixed amount in the cylinder, returning this piston to the original position after holding this state for a fixed time,
A leak inspection method for a sealed container, characterized by measuring pressure outside a subject when a piston returns to its original position to determine leak. 2. An inspection pocket for hermetically accommodating all or part of a subject, a cylinder communicating with the pocket, a piston for moving in the cylinder to pressurize or depressurize the inspection pocket, A pressure sensor that measures the pressure in the inspection pocket, and a switch that is located between the inspection pocket and the pressure sensor and connects the inspection pocket and the pressure sensor or opens the pressure sensor to atmospheric pressure for resetting. A leak inspection device for a sealed container, which is equipped with a valve.