JP3087532B2 - Airtightness inspection method for hollow containers - 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 for a hollow container such as a fuel tank, and more particularly to a method for performing a high-precision airtightness inspection with a simple structure.

[0002]

2. Description of the Related Art A submerged leak check method has been well known as a method for inspecting the airtightness of a hollow container such as a fuel tank. As shown in FIG. 6, this submerged leak check method includes, for example, a fuel tank 2 in a water tank 1.
And the air from the air supply source is supplied into the fuel tank 2 via the pressure regulator A, for example, 0.3 kg /
The inside of the fuel tank 2 is pressurized at a pressure of cm ² for 30 seconds. Then, the operator visually checks the presence or absence of air bubbles B leaking from the fuel tank 2 and checks whether there is any leakage.

[0003]

However, in such a conventional submerged leak check method, an operator needs to visually check the presence or absence of air bubbles B leaking from the fuel tank 2. It is necessary to keep an eye on the fuel tank 2 for a certain period of time, and it is difficult to distinguish leaking bubbles B from bubbles adhering around the fuel tank 2. There is a problem.

As an inspection method for solving such a problem,
Conventionally, there is one disclosed in JP-A-4-89542. In this inspection method, after placing the hollow container in the inspection chamber, the hollow container and the inspection chamber are evacuated at a predetermined vacuum so that the degree of vacuum is higher in the inspection chamber than in the hollow container. Is supplied to the test chamber, and the amount of gas leakage from the hollow container to the inspection chamber is measured by gas measuring means.

In this method, although an accurate airtightness inspection can be performed, there is a problem that the equipment cost is high and is not practical because the equipment is large-scale. Therefore,
In view of the above-mentioned conventional problems, the present invention provides a method for inspecting the airtightness of a hollow container, which can perform an accurate airtightness inspection with no need for visual inspection by an operator with simple and low-cost equipment. The purpose is to provide.

[0006]

Therefore, according to the first aspect of the present invention, a hollow container to be inspected is disposed in water in a water tank, and a gas having a property different from air is specified in the hollow container. Sealing with pressure, detecting gas leaking from the hollow container above the hollow container in the water tank, and determining whether the gas detection amount is within an allowable range or exceeds the allowable range, Gas for detecting gas leaking from the hollow container
The detection unit of the detection device has a pre-programmed pattern
Scan above the hollow container and scan above the hollow container
Calculate the coordinates of the X and Y positions of the detector, and make sure that the gas
At the X and Y positions of the detector above the hollow container at the point
Converting the target into data and outputting the data .

[0007]

[0008]

According to the first aspect of the present invention, the airtightness of the hollow container is provided.
To inspect the hollow container to be inspected in the water in the tank
And place a gas with a property different from air in the hollow container.
Enclose with pressure. And above the hollow container in the water tank
Detects gas leaking from a hollow container, and the amount of detected gas is allowable
Determine if the value is within the range or exceeds the allowable range
I do. Therefore, there is no oversight of leakage defects, it is possible to improve the inspection accuracy itself since it is possible to quantitatively grasp the degree of leakage defect by leakage of the gas, constant
Improve reliability of test results even if you do not watch
You . Further, even if there are bubbles adhering to the hollow container, it is possible to detect only the gas leaking from the hollow container, so that it is possible to make a more accurate determination.

Further, the gas leaking from the hollow container is detected.
The detection part of the gas detector
Scan over the hollow container and scan over the hollow container
Calculate the coordinates of the X and Y positions of the detecting part
X, Y of the detection part above the hollow container at the time of exceeding the allowable range
By converting the coordinates of the position into data and outputting it, it is possible to approximately specify which part of the hollow container has a leak,
It is possible to feed back to the previous process.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a configuration of an example of an inspection apparatus that executes a method for inspecting the airtightness of a hollow container according to the present invention. In this figure, the inspection device includes a water tank 1 and helium (hereinafter, referred to as helium).
A He gas supply device 3 for supplying a He mixed gas from a gas tank C via a filler hose D into a fuel tank 2 as a hollow container, and a He gas supply device 3 provided across the upper opening of the water tank 1. A He gas absorber 4 provided on the table 11 so as to be capable of scanning, and the He gas absorber 4
, A control personal computer 6 connected to the He gas absorber 4, the table 11, and the He leak detector 5, and a printer 7 connected to the control personal computer 6. .

The He leak detector 5 constitutes a gas detector, and the He gas absorber 4 constitutes a detector of the gas detector. The outline of the airtightness inspection method is as follows. A fuel tank 2 to be inspected is placed in water in a water tank 1 and a He mixed gas is supplied at, for example, 0.15 kg / c.
The fuel is supplied into the fuel tank 2 at a pressure of m ² and sealed. Next, the He gas absorber 4 is scanned above the fuel tank 2 to detect the He gas E leaking from the fuel tank 2, thereby performing a leak check of the fuel tank 2. Leak NG is determined when the amount of leaked He gas exceeds an allowable amount preset in the He leak detector 5, and in that case, the fuel tank 2 is inspected again.

Here, the principle of determining the He gas amount by the He leak detector 5 will be described. He gas and other gases are led to a gas mass analyzer F having the configuration shown in FIG. 2 through a turbo molecular pump built in the He leak detector 5. These gases are first heated and ionized by the tungsten filament G of the gas mass analyzer F. Next, it is accelerated by the ion acceleration voltage and guided to the electromagnetic prism H.

The inside of the electromagnetic prism H is deflected by an electromagnetic force, but the amount of deflection is different for each ion having a different mass. Only He passes through the intermediate screen I and reaches the ion collector J. In the ion collector J, a current proportional to the collected ions is generated, and after amplification by an amplifier, He measurement processing is performed. The He gas absorber 4 is movable in the X and Y directions, and is scanned above the fuel tank 2 at a constant speed. Then, the control personal computer 6 outputs the correlation between the X and Y positions of the He gas absorber 4 and the He gas amount at that time, and roughly identifies which part of the fuel tank 2 has a leak location, and performs a pre-process. It is configured so that feedback can be provided.

The scanning mechanism of the He gas absorber 4 and its method will be described with reference to FIG. He gas absorber 4
An X-axis feed stepping motor 8 provided on the table 11 is configured to be movable in the X-axis direction on a ball screw 9 provided on the table 11. He gas absorber 4
Is guided by a guide rail 10 provided on the table 11 during the movement in the X-axis direction.

On the other hand, the entire table 11 is provided with a Y-axis feed stepping motor 1 provided on a side wall 1A of the water tank 1.
2, the ball screw 1 provided on the side wall 1A of the water tank 1
3 is configured to be movable in the Y-axis direction. Table 11
The whole is guided by guide rails 14 provided on the side wall 1A of the water tank 1 during the movement in the Y-axis direction. The operation of the stepping motor 8 for feeding the X-axis and the stepping motor 12 for feeding the Y-axis is such that the He gas absorber 4 scans the upper portion of the fuel tank 2 at a constant rate according to a pattern programmed in the control personal computer 6 in advance. It is set as follows.

With such a mechanism, the He gas absorber 4 scanning above the fuel tank 2 always detects He gas leaking from the fuel tank 2 and outputs H gas.
The e leak detector 5 determines whether the detected amount of He gas is within an allowable range or exceeds the allowable range. Encoders 15 and 16 are attached to the X-axis feed stepping motor 8 and the Y-axis feed stepping motor 12, respectively. These encoders 15 and 16 scan He fuel tank 2 above. X, Y of gas absorber 4
The position coordinates are calculated by the control personal computer 6.

Accordingly, the coordinates of the position of the He gas absorber 4 above the fuel tank 2 at the time when the He gas exceeds the allowable amount, that is, the coordinates of the X and Y positions of the He gas absorber 4, are converted into data by the control personal computer 6, and 7, and can be output as a map K. Next, the details of the fuel tank airtightness inspection method based on the above configuration will be described with reference to the configuration diagrams of FIGS. 1 to 3, the inspection pattern diagram of FIG. 4, and the flowchart of FIG.

First, an operator fixes the fuel tank 2 to a set jig and closes holes of hoses connected to the fuel tank 2 (S1). Next, connect the He gas inlet of the He gas supply device 3 to the filler hose D of the fuel tank 2, thereby submerging the fuel tank 2 in the water tank _{1 (0~t 1) (S2)} . Next, the test start switch is operated (S3), and 0.
At a pressure of 15 kg / cm ² , a He mixed gas is sealed (t ₁ to t ₂ ) (S 4).

During a certain period of time, the fuel tank 2 is stabilized at a pressure of 0.15 kg / cm ² , and if a large He gas leak occurs, NG is output in this process (t ₂ to t ₃ ). Then, the He gas absorber 4 is operated along the above-described scanning path to detect He gas leaking from the fuel tank 2 (S5), and the He leak detector 5 determines the amount of He gas detection (S6) ( t ₃ ~
t _4). During testing, Huh that He gas detection amount is set in advance
If you do not reach the capacity, output OK in the time t _4. That is, the lamp L for OK determination is turned on and the buzzer sounds (S7). On the other hand, if the detected amount of He gas exceeds the allowable amount, NG is output at that time, that is, the NG determination lamp M is turned on and the buzzer sounds (S1).
1).

After the output of OK, He gas in the fuel tank 2 is exhausted and collected (t ₄ to t ₅ ) (S ₄ ).
8) Then, the fuel tank 2 is removed from the water tank 1 (S9) and dried (S10). On the other hand, after the output of the NG, the He gas in the fuel tank 2 is exhausted and collected (S12), and as described above, the NG generation site, that is, the upper portion of the fuel tank 2 at the time when the He gas exceeds the allowable amount. , The coordinates of the X and Y positions of the He gas absorber 4 are calculated (S13), and a map of these coordinates is output (S14). Thereafter, statistics of the NG occurrence site are created (S15), and based on this, feedback is applied to the previous process (S16).

When the inspected fuel tank 2 has a leak NG, a re-inspection is performed. In this case, if the fuel tank 2 is NG, the fuel tank 2 is discarded. According to the method for inspecting the airtightness of the fuel tank 2, the fuel tank 2 to be inspected is disposed in the water in the water tank 1, He gas is sealed in the fuel tank 2 at a predetermined pressure, and the fuel in the water tank 1 is filled. A gas leaking from the fuel tank 2 is detected by a He gas absorber 4 disposed above the tank 2, and a He leak detector 3 determines whether the detected amount of He gas is within an allowable range or exceeds the range. Thus, unlike the conventional visual inspection, the degree of the leakage defect can be quantitatively grasped by the amount of He gas leakage, and the inspection accuracy itself can be improved without oversight of the leakage defect. The results are more reliable,
There is no need to keep an eye on it for a certain amount of time.

The air bubbles N adhering to the fuel tank 2
Even if there is (see FIG. 1), only the He gas E leaked from the fuel tank 2 can be detected, so that a more accurate determination can be made. Further, according to such a method,
Compare the conventional method of evacuating the hollow container and the inspection chamber to a predetermined degree of vacuum, supplying a specific gas to the hollow container, and measuring the amount of gas leakage from the hollow container to the inspection chamber by gas measurement means. Therefore, the equipment is simple, and the equipment cost is advantageous and practical.

In particular, according to the above-described embodiment, the He gas absorber 4 scans the upper portion of the fuel tank 2 at a constant rate according to a pattern programmed in the control personal computer 6 in advance, and scans the He gas absorber 2 above the fuel tank 2. X of machine 4,
The coordinates of the Y position are calculated by the control personal computer 6 to obtain He.
The position of the He gas absorber 4 above the fuel tank 2 when the gas exceeds the allowable amount, that is, X, X of the He gas absorber 4
Since the coordinates of the Y position are converted into data by the control personal computer 6 and output as the map K by the printer 7, it is possible to substantially specify which part of the fuel tank W has a leak location, and to feed back to the preceding process. There is an advantage that it becomes possible.

As described above, the present invention has been described with reference to the specific embodiments. However, the present invention is not limited to these embodiments, and is attached to the present invention by a person skilled in the art. Without departing from the scope of the appended claims.
It should be noted that various changes and modifications are possible.

[0025]

As described above, according to the first aspect of the present invention,
In this case, there is no oversight of leakage defects, the inspection accuracy itself can be improved, the degree of leakage defects can be quantitatively grasped by the amount of gas leakage , and the inspection can be performed for a certain period of time.
Even if it is not stretched, the reliability of the inspection result is improved . or,
Even if there are air bubbles adhering to the hollow container, it is possible to detect only the gas leaking from the hollow container, so that it is possible to make a more accurate determination.

Further, when the gas exceeds the allowable range,
Convert the coordinates of the X and Y positions of the detector above the empty container into data
By outputting, it is possible to substantially specify which part of the hollow container has the leaking part, and it is possible to feed back to the previous process.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for executing a method for inspecting the airtightness of a hollow container according to the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a gas mass analyzer of a He leak detector in the same device.

3A and 3B are diagrams showing a scanning mechanism of a He gas absorber in the above device, wherein FIG. 3A is a plan view and FIG.

FIG. 4 is an inspection pattern diagram of an airtightness inspection method.

FIG. 5 is an inspection flowchart of an airtightness inspection method.

FIG. 6 is a cross-sectional view illustrating a conventional airtightness inspection method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 water tank 2 fuel tank 3 He gas supply device 4 He gas absorber 5 He leak detector 6 control personal computer 7 printer

Claims (1)

(57) [Claims] A step of arranging a hollow container to be inspected in water in a water tank and enclosing a gas having a property different from air at a predetermined pressure in the hollow container; A step of detecting gas leaking from the hollow container and determining whether a gas detection amount is within an allowable range or exceeding the allowable range, and a gas detecting device for detecting gas leaking from the hollow container
Of the hollow container with a pre-programmed pattern
The upper part is scanned, and the detecting part scanning above the hollow container is
Calculate the coordinates of X and Y positions and the gas exceeds the allowable range
The coordinates of the X and Y positions of the detection unit above the hollow container at the time
And outputting the airtightness of the hollow container.