JP2598197B2 - Airtightness inspection method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airtightness inspection method and apparatus for immersing a sealed container in a liquid and inspecting the airtightness of the sealed container.

[0002]

2. Description of the Related Art Conventionally, in the industry, when manufacturing a sealed container, the inside of the sealed container is pressurized and submerged in a water tank.
Bubbles leaking from a defective part (hereinafter referred to as leak bubbles)
The airtightness of the sealed container is inspected by detecting the presence or absence of airtightness.

By the way, when the sealed container is submerged,
When immersed in water, air bubbles adhere to the outer wall surface of the sealed container, and the air bubbles stay in the concave portion of the sealed container, so-called air pools are generated. Then, bubbles attached to the outer wall surface are released, or bubbles in the air reservoir are released from the concave portion of the sealed container, so that bubbles are generated in the water tank (hereinafter referred to as residual bubbles).

[0004] Since it is difficult to discriminate between the residual air bubbles and the leak air bubbles leaking from the inside of the sealed container, it is not possible to judge whether the airtightness of the sealed container is good or not based only on the amount of the detected air bubbles.

[0005] Therefore, a swinging operation such as inversion of the sealed container is added to eliminate air bubbles remaining in the concave portion of the sealed container, or a vibration generator arranged in the water tank is energized to urge the outside of the sealed container to the outside. A method of promoting the elimination of the residual air bubbles adhered to the wall surface is used, and the inspection accuracy is improved by delaying the start of the inspection until the residual air bubbles are eliminated.

On the other hand, the technical idea of an airtightness inspection method is disclosed in Japanese Patent Application Laid-Open No. 57-54832, "Airtightness Inspection Method".
No. 127140, “Airtightness inspection device”.

The "airtightness inspection method" and the "airtightness inspection apparatus" calculate the total amount of change in the number of bubbles detected at each sampling time, and introduce the total amount information of the change amount into a determination circuit to provide airtightness. Is determined.

[0008]

However, in the above-described conventional airtightness inspection method and apparatus, it is difficult to determine the presence / absence of leaked air bubbles when the amount of leaked air bubbles is small compared to the residual air bubbles. There is.

Further, there is a problem that the inspection time cannot be shortened because the residual air bubbles cannot be removed promptly.

The present invention has been made in order to solve such a conventional problem. By extracting only leaked bubble data from detected bubble data, the number of leaked bubbles is smaller than that of residual bubbles. Airtightness inspection method that can reliably detect the airtightness and can start the airtightness inspection even when the residual air bubbles are not completely removed, thereby shortening the inspection time. And an apparatus.

[0011]

In order to achieve the above object, a first aspect of the present invention is to provide an airtight test for detecting the airtightness of a sealed container by detecting bubbles generated from the sealed container immersed in a liquid. A method for detecting the air bubbles by an air bubble detection sensor and counting the number of air bubbles at each preset sampling time; and setting a predetermined number of air bubbles from the counted number of air bubbles at each sampling time. A second step of extracting the number of patterns corresponding to the plurality of types of occurrence period patterns, and a third step of comparing the extracted number of patterns with a preset threshold value.
And a fourth step of determining whether the airtightness of the sealed container is good or bad based on the comparison result.

Further, a second invention is an airtightness inspection device for inspecting the airtightness of the sealed container by detecting air bubbles generated from the sealed container immersed in the liquid, wherein the air bubbles are detected. A bubble detection sensor, a counting circuit that counts the detected bubbles at each preset sampling time, and a plurality of preset occurrence cycle patterns from the information of the number of bubbles counted at each sampling time. A number-of-patterns extraction circuit for extracting the number of each pattern to be performed, a comparison circuit for comparing the number of each of the extracted patterns, and a preset threshold value, based on the comparison result, And an airtightness determination circuit for determining whether the airtightness is acceptable or not.

[0013]

In the airtightness inspection method and apparatus according to the present invention, air bubbles generated from the sealed container immersed in the liquid are detected by the air bubble detection sensor, and the detected air bubbles are counted by the counting circuit at every preset sampling time. Count. Then
From the number-of-bubbles information counted for each sampling time, the number of each pattern that matches a plurality of types of generation cycle patterns set in advance is extracted, and the number of extracted patterns and a predetermined threshold value are extracted. And whether the airtightness of the sealed container is good or not is determined based on the comparison result.

Therefore, by extracting the number of patterns corresponding to a plurality of types of generation cycle patterns set in advance, only leak bubble information is extracted from detected bubble information in which information of residual bubbles and leak bubbles is mixed. It becomes possible.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the method and apparatus for checking airtightness according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an airtightness inspection apparatus 1 embodying the present invention.
FIG. 2 is a perspective view showing a configuration of a No. 0.

The airtightness inspection apparatus 10 includes an inspection liquid tank 12 for submerging a vehicle fuel tank W as a sealed container, an umbrella-shaped foam collecting hood 14, and an arithmetic circuit 16.

A fuel tank W is provided inside the test liquid tank 12.
A holding housing 20 to which holding fittings 18a and 18b for holding the holding member are engaged, a rotating shaft 21 to be attached to the holding fitting 18a, and a rotating mechanism 22 for driving the rotating shaft 21 to rotate.

The rotating mechanism 22 includes a motor 24 fixed to the outside of the test liquid tank 12, a pulley 28 mounted on a rotating shaft 26 of the motor 24, and a pulley 30 disposed in the test liquid tank 12. , And a belt 32 is stretched between the pulley 28 and the pulley 30. In addition, the pulley 30 is
4 and the other end of the rotating shaft 34 is engaged with the rotating shaft 21, so that when the motor 24 is energized,
The rotation shaft 26 and the pulley 2
8, belt 32, pulley 30, rotating shaft 34, rotating shaft 21
The holding bracket 18a is driven to rotate via
The fuel tank W is rotated.

The umbrella-shaped foam collecting hood 14 has a hood section 36 for collecting bubbles generated from the fuel tank W, and a hood section 3.
6, a test tube 38 disposed at the top of the hood 6, and piston rods 40a and 40b are engaged with the hood portion 36,
The foam collecting hood 14 is moved up and down under the extension action of the elevating cylinders 42a and 42b. An optical bubble detection sensor 44 is attached to the inspection tube 38, and the output of the optical bubble detection sensor 44 is introduced to the arithmetic circuit 16.

FIG. 2 is a block diagram showing the configuration of the arithmetic circuit 16.

The arithmetic circuit 16 includes a sensor amplifier circuit 46 for amplifying the output of the bubble detection sensor 44, a counter circuit 48 for counting the number of amplified bubbles generated at each preset sampling time, and a counter circuit 48. A pattern extraction circuit 50 for extracting the number of patterns corresponding to a plurality of types of generation cycle patterns set in advance from the number-of-bubbles information for each sampling time counted in the step (a), and a frequency-converted pattern data and a predetermined threshold. And a control circuit 54 for determining whether the airtightness of the fuel tank W is acceptable or not based on the comparison result.
And

Further, the arithmetic circuit 16 includes a storage circuit 56 for storing the respective arithmetic results and the like, and a display 58 for displaying the results of the pass / fail judgment.

The airtightness inspection apparatus 1 configured as described above
The operation of performing the airtightness inspection of the vehicle fuel tank W at 0 will be described with reference to FIGS.

1.5 kg / gauge pressure in the fuel tank W
The fuel tank W is submerged in the test liquid tank 12 with compressed air of cm ² (step S31).
a, 18b (step S32). Next, the motor 24 is energized to rotate the holding member 18a via the rotating shaft 26, the pulley 28, the belt 32, the pulley 30, the rotating shaft 34, and the rotating shaft 21.
By rotating the fuel tank W held at 8a by 180 degrees,
Remaining air bubbles remaining on the bottom side of the concave fuel tank W are eliminated (step S33), and the lifting cylinders 42a and 42b are urged to move the piston rods 40a and 40b.
The foaming hood 14 is lowered to a predetermined position above the fuel tank W under the action of the extension (step S34), and the detection of air bubbles is started. A calculation is performed based on the detected number-of-bubbles information to determine whether the fuel tank W is airtight (step S35). Details of the inspection method will be described later.

Next, as in step S33, the motor 24 is energized to further rotate the fuel tank W by 180 degrees so that the upper side of the fuel tank W is set to the water surface side (step S3).
6) As in step S35, air bubbles are detected to determine whether airtightness is acceptable (step S37).

With the above steps, the airtightness inspection of the fuel tank W is completed.

Next, a description will be given of a method of detecting bubbles in step S35 and a method of determining whether airtightness is acceptable or not in step S37.

The bubble information detected by the bubble detection sensor 44 is amplified by the sensor amplifier circuit 46 and introduced to the counter circuit 48. The control circuit 54 outputs a sampling trigger to the counter circuit 48 at a preset sampling time, for example, every 0.1 second, and outputs the bubble number information output from the counter circuit 48 by the sampling trigger to the preset measurement time. For example, reading is performed for 30 seconds and stored in the storage circuit 56 (see FIG. 5A).
(Step S41).

Next, the control circuit 54 searches the search time T = n ₁
An initial value 1 T _O to the search number n _1, substituting and 0.1sec to the initial value T _O search time T, 0.1s search time T
ec (step S42).

The pattern extraction circuit 50 includes the control circuit 54
The bubble generation pattern is extracted from the bubble number information for each sampling time stored in the storage circuit 56 in step S41 in accordance with the search time T of 0.1 sec set in step S41 and the previously stored search pattern (step S43). .

This pattern extraction method will be described with reference to FIGS.

In the bubble number information for each sampling time counted and stored in the storage circuit 56 (see FIG. 5A), the sampling time is 0.1 sec (first sampling data, see FIG. 5A). ), The sampling time is 0.2 sec (second sampling data, see FIG. 5A), and the sampling time is 0.3 sec (third sampling data, FIG.
(See (a)) to determine whether or not bubbles are detected (see (1) in FIG. 5 (b)). Then, the second sampling data, the third sampling data, and the fourth sampling data are searched. A search is made as to whether or not bubbles have been detected continuously from the sampling data (see FIG. 5 (b) 2).

As described above, while the sampling data to be searched are partially overlapped, the search time T is 0.1 sec, the search time T is 0.1 sec until the last of the measurement time is 30 sec, and three consecutive bubbles are detected. Is extracted, the number of extracted patterns is counted, and stored in the storage circuit 56 (step S44).

Next, "1" is added to the number of searches n ₁ = 1 (n ₁ = 2), and the search time T is substituted for the search time T = n ₁ T _O to set the search time T to 0.2 sec (step S4).
5) As in the case of the pattern extraction in 0.1 sec, a pattern in which three consecutive bubbles are detected is extracted, and the number of extracted patterns is counted and stored.

This pattern extraction is repeated until the search time T becomes 1/2 of the measurement time of 30 seconds, that is, 15 seconds (step S46).

The case where it is determined that there is a pattern in the method of extracting the number of patterns performed as described above will be described in further detail.

FIG. 6A shows a sampling time of 0.1 s.
FIG. 6B is a diagram illustrating the pattern search operation when the search time T is 0.1 sec.

The first sampling data (FIG. 6)
(A)), the second sampling data (FIG. 6)
(A)) and when bubbles are detected consecutively to the third sampling data (see FIG. 6 (a)), that is, when a pattern is extracted (FIG. 6 (b)).
1), the first sampling data (FIG. 6A)
) Is subtracted from “1”.

Similarly, in the pattern search shown in FIG. 6B, "1" is subtracted from the second sampling data (FIG. 6A) since the pattern is extracted.

Hereinafter, when a pattern is similarly extracted, "1" is subtracted from the first sampling data of the three sampling data, and the remaining sampling data is used as new sampling data for the next pattern search. (See FIG. 6 (c)).

In this case, if there is only one missing portion in the fuel tank W, it is known that only one leak bubble is generated at the same time. By subtracting "1", 2
Multiple searches can be prevented.

FIG. 6C shows new sampling data after performing a pattern search for a search time T of 0.1 sec. This new sampling data has a search time T of 0.2 s
FIG. 6D shows that no pattern was extracted in the pattern search from ec to 0.5 sec, and FIG. 6D shows a pattern extracted when the search time T is 0.6 sec.
Further, FIG. 6E shows that there is no pattern to be extracted even if the search time T is added up to 15 seconds.

As a result, the number of extracted patterns is n-2 when the search time T is 0.1 sec.
Is 0.6 sec, and the number of these extracted patterns is converted into a distribution graph represented by a search time T converted into a frequency (step S47).

A comparison operation is performed by the frequency comparison circuit 52 to determine whether or not the maximum number data of the patterns obtained as described above is lower than threshold data indicating a predetermined criterion for pass / fail. S48) If the maximum number of extracted patterns <the threshold value, the control circuit 54 determines that the airtightness of the fuel tank W, which is a sealed container, is passed, and displays the pass on the display 58 (step S49). If the maximum number of extracted patterns is not smaller than the threshold value, rejection is displayed on the display 58 (step S50), and the airtightness inspection ends.

The set threshold value is set based on experimental data obtained from the fuel tank W in which no leak bubbles are generated.

As described above, in the present embodiment, attention is paid to the fact that the generation cycle of the leak air bubbles is regular, and the generation cycle of the residual air bubbles is irregular, so that it is set in advance from the detected air bubble data. By extracting a pattern having the same generation cycle as the generated pattern, only leak bubbles are extracted from bubble data in which residual bubbles and leak bubbles are mixed.

Therefore, even when a large amount of residual air bubbles are generated, it is possible to start the airtightness inspection of the fuel tank W.

In this embodiment, the air bubble detection sensor 4
4 is an optical type, but it is needless to say that a similar effect can be obtained by using a bubble detection sensor of an ultrasonic type or the like.

[0050]

In the airtightness inspection method and apparatus according to the present invention, the number of patterns coincident with a plurality of types of generation cycle patterns set in advance is extracted from the bubble information counted for each sampling time, so that the remaining number is determined. It is possible to extract only leaked bubble information from detected bubble information in which information of bubbles and leaked bubbles are mixed.

Therefore, even when a large amount of residual air bubbles are generated, a highly accurate airtightness inspection can be performed.

Further, since there is no need to wait for the airtightness inspection until the residual air bubbles are eliminated, the airtightness inspection of the sealed container can be started immediately, and the airtightness inspection including submergence, bubble detection and judgment, etc. The cycle time can be shortened, and the inspection efficiency of the entire line can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an airtightness inspection apparatus that implements an airtightness inspection method and apparatus of the present invention.

FIG. 2 is a block diagram showing a configuration of an arithmetic circuit of the embodiment shown in FIG.

FIG. 3 is a flowchart showing an outline of an airtightness inspection method of the embodiment shown in FIG. 1;

FIG. 4 is a flowchart showing an airtightness inspection method of the embodiment shown in FIG.

FIG. 5 is a diagram illustrating a method of searching for a pattern in the airtightness inspection method shown in FIG. 4;

FIG. 6 is a diagram illustrating a method of searching for a pattern in the embodiment shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Airtightness inspection apparatus 12 ... Inspection liquid tank 14 ... Foam collecting hood 16 ... Arithmetic circuit 18a, 18b ... Holding fitting 24 ... Motor 38 ... Inspection tube 44 ... Bubble detection sensor 46 ... Sensor amplifier circuit 48 ... Counter circuit 50 ... Pattern Extraction circuit 52: Frequency comparison circuit 54: Control circuit 56: Storage circuit 58: Display W: Fuel tank

Claims (2)

(57) [Claims] An airtightness inspection method for inspecting airtightness of a sealed container by detecting air bubbles generated from a sealed container immersed in a liquid, wherein the air bubbles are detected by an air bubble detection sensor, A first step of counting for each set sampling time, and a second step of extracting the number of respective patterns that match a plurality of types of generation cycle patterns set in advance from the counted number of bubbles for each sampling time. And a third step of comparing the number of each of the extracted patterns with a preset threshold value; and a step of determining whether the airtightness of the sealed container is good or bad based on the comparison result. 4. An airtightness inspection method, comprising the steps of: 2. An airtightness inspection device for inspecting airtightness of a sealed container by detecting air bubbles generated from a sealed container immersed in a liquid, wherein: an air bubble detection sensor for detecting the air bubbles; A counting circuit that counts the detected bubbles for each preset sampling time; and, based on the counted number of bubbles for each sampling time, the number of respective patterns that match a plurality of types of generation cycle patterns that are set in advance. An extraction circuit for extracting the number of patterns to be extracted; a comparison circuit for comparing the number of each extracted pattern with a preset threshold value; and determining whether the airtightness of the sealed container is good or bad based on the comparison result. An airtightness inspection device, comprising: