JP2001033343A - Method and device for leak test - Google Patents

Abstract

PROBLEM TO BE SOLVED: To replace a body to be inspected in a vacuum chamber with another body to be inspected while deciding a leak without being affected by tracer gas from other bodies to be inspected. SOLUTION: This leak testing method has a storage stage for putting a body X to be inspected which is filled with tracer gas in the vacuum chamber 10, an evacuation stage for evacuating the vacuum chamber 10 by a vacuum pump 20, a communication stage for cutting off the communication between a partition chamber 30 formed between the vacuum chamber 10 and vacuum pump 20 and the vacuum pump 20 when the inside of the vacuum chamber 20 reaches a previously set specific degree of vacuum and links the partition chamber 30 with a gas detector 40 to make the tracer gas leaking from the body X to be inspected with the gas detector 40, a cutoff stage for disconnecting the vacuum chamber 10 from the partition chamber 30, and an exchange stage for linking the inside of the vacuum chamber 10 to the atmosphere and replacing the body X to be inspected with another body to be inspected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak test method for introducing a tracer gas (such as He gas) into a subject and determining whether or not the tracer gas leaks or whether or not the leak exceeds a permissible limit. More particularly, the present invention relates to a leak test method and a leak test device that can be replaced with another subject while determining the leak of tracer gas.

[0002]

2. Description of the Related Art Conventionally, drums, air conditioner outdoor units,
In order to detect minute holes and cracks in the welded parts and wall surfaces of various objects such as compressors, aluminum wheels, automobile fuel tanks, etc., these various objects are filled with tracer gas and leaked from these objects. There is known a tracer gas inspection method for detecting emitted tracer gas.

In this type of tracer gas inspection method, for example, as shown in FIG. 2, a vacuum pump 61 is connected to an airtightly sealed vacuum chamber 60 through an electromagnetic valve V1 and a pipe P1 so as to be able to conduct electricity. A gas detector (detector) 62 is connected so as to be able to conduct through the pipe P2 to constitute a leak test apparatus, and a specimen X (hereinafter, this specimen is referred to as a work) previously filled with a tracer gas is introduced into the chamber 60. Deploy.

After that, the air remaining in the vacuum chamber 60 is evacuated by opening the electromagnetic valve V1 and the inside of the vacuum chamber 60 is evacuated. He gas leaked into the chamber 60 leaks into the chamber 60, and the leaked He gas flows into the detector 62 through the electromagnetic valve V2 and the pipe P2, and the He gas is detected by the detector 62. According to this method, the presence / absence of a leak in the entire work X can be detected, and the leak amount of the entire work X can be determined. The inside of the vacuum chamber 60 is connected to the atmosphere through an electromagnetic valve V3 and a pipe P3 so as to be conductive.
After the test, the electromagnetic valve V3 is opened and the vacuum chamber 6 is opened.
The vacuum state in 0 is released.

[0005]

However, in the tracer gas inspection method as described above, the vacuum chamber 60 for accommodating the work X and the gas detector (detector) 6 are provided.
2 is connected to the work X until the inspection is completed.
Cannot be taken out of the vacuum chamber 60, it takes a long time until the inspection is completed, and the inspection efficiency is poor. Therefore, the present invention has been made to solve the above-described problem, and determines the leakage of tracer gas from a subject housed in a vacuum chamber while determining the presence of another subject housed in the vacuum chamber. It is intended to be exchangeable with a subject.

[0006]

In order to solve the above-mentioned problems, a leak test method according to the present invention comprises: a housing step of housing an object filled with tracer gas in a vacuum chamber; A pressure reducing step of reducing the pressure inside the chamber to a level lower than that of the subject, and, when the inside of the vacuum chamber reaches a predetermined pressure, establishes communication between a vacuum chamber and a compartment formed between the vacuum chamber and the vacuum pump. A communication step of shutting off and communicating between the compartment and the gas detector to communicate the tracer gas leaked from the subject to the gas detector, and a shutoff step of shutting off between the vacuum chamber and the compartment. ,
An exchange step of exchanging the object for another object.

Accordingly, the tracer gas filled in the subject leaks into the vacuum chamber based on the differential pressure between the subject and the vacuum chamber which has been reduced in pressure in the depressurizing step, and the leaked tracer Gas will flow into the compartment. Next, when the pressure inside the vacuum chamber reaches a predetermined pressure in the communication step, the communication between the compartment and the vacuum pump is cut off. As a result, the tracer gas that has flowed into the compartment does not flow into the compartment on another path. Further, when the communication between the compartment and the gas detector is established by the communication step, the tracer gas flowing into the compartment flows into the gas detector, so that the gas detector detects the tracer gas. Start.

Next, the vacuum chamber and the compartment are shut off by the shut-off step, and the gas detector determines whether or not the tracer gas is leaking or leaks beyond the allowable limit. During this time, the subject stored in the vacuum chamber can be replaced with another subject by the replacement process.

On the other hand, in the leak test apparatus according to the present invention, a vacuum pump connected to the vacuum chamber through the first pipe to reduce the pressure inside the vacuum chamber lower than that of the subject is provided. A gas chamber disposed between the chamber and a vacuum chamber and a vacuum pump connected via a first pipe, and a gas detector connected to the chamber via a second pipe and detecting a tracer gas flowing into the chamber; A first valve connected to a first pipe between the vacuum chamber and the compartment to communicate the vacuum chamber with the compartment; and a first valve connected to the first pipe between the compartment and the vacuum pump. A second valve for communicating the chamber with the vacuum pump; and a third valve connected to the second pipe between the compartment and the gas detector for communicating the compartment with the gas detector. .

Thus, when the first valve and the second valve are opened after driving the vacuum pump, the inside of the vacuum chamber is in a reduced pressure state compared with the test object. As a result, a pressure difference occurs between the subject and the vacuum chamber, and the tracer gas leaks from the subject into the vacuum chamber. Then, after the inside of the vacuum chamber reaches a predetermined pressure, the second valve is closed and the third valve is opened, so that the inside of the vacuum chamber communicates with the inside of the gas detector. The detector starts detecting the tracer gas.
Thereafter, when the first valve is closed, the inside of the vacuum chamber and the inside of the gas detector are shut off. It can be replaced with a subject.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below in detail with reference to FIG. 1. However, the present invention is not limited to this embodiment, and the scope of the present invention is not changed. It is possible to change and implement as appropriate. FIG. 1 is a block diagram schematically showing a leak test apparatus according to the present invention.

1. Leak test device The leak test device of the present invention is a test object filled with tracer gas (He gas) (hereinafter, this test object is referred to as a work).
A vacuum chamber 10 for airtightly storing X, and a vacuum pump 20 for reducing the pressure inside the vacuum chamber 10 to a level lower than that of a work.
And a compartment 30 disposed between the vacuum chamber 10 and the vacuum pump 20, a gas detector (detector) 40 for detecting a tracer gas flowing into the compartment 30, and pipes P1 to P3 to be described later. And a control device 50 that controls the operation and stop of the vacuum pump 20 and controls the opening and closing of the electromagnetic valves V1 to V4.

Then, the vacuum chamber 10 and the vacuum pump 2
0 is connected to the first pipe P1 via the compartment 30, and the first pipe P1 between the vacuum chamber 10 and the compartment 30.
Is connected to a first electromagnetic valve V1, and a first pipe P1 between the compartment 30 and the vacuum pump 20 is connected to a second electromagnetic valve V2. A second pipe P2 is connected between the compartment 30 and the gas detector (detector) 40, and a third electromagnetic valve V3 is connected to the second pipe P2. Further, a third pipe P3 is connected to the vacuum chamber 10, and a fourth electromagnetic valve V4 is connected to the third pipe P3.

The vacuum chamber 10 comprises a fixed box (not shown) and a movable lid movable vertically with respect to the fixed box. After the work X is placed on the movable lid,
When the movable lid driven by the movable lid drive device moves upward and reaches the lower end of the fixed box, the lower end of the fixed box and the movable lid are hermetically sealed. A pressure gauge for measuring the pressure in the vacuum chamber 10 is provided in the vacuum chamber 10, and the measured value of the pressure gauge is input to the control device 50.

When the first electromagnetic valve V1 and the second electromagnetic valve V2 are opened in the driving state, the vacuum pump 20
Vacuum chamber 10 via first pipe P1 and compartment 30
Then, the air existing in the vacuum chamber 10 is exhausted, and the inside of the vacuum chamber 10 is depressurized until a predetermined pressure lower than the inside of the work X (for example, 1 Torr or less) is reached. When the pressure in the vacuum chamber 10 becomes lower than that in the work X, the tracer gas (He) filled in the work X stored in the vacuum chamber 10 is used.
Gas) leaks into the vacuum chamber 10.

In the compartment 30, after the inside of the vacuum chamber 10 reaches a predetermined pressure, the first electromagnetic valve V1 is closed to shut off the inside of the vacuum chamber 10 and the inside of the compartment 30. Therefore, even if the work X stored in the vacuum chamber 10 is replaced with another object, the detector 40 is provided so that the detector 40 can detect the tracer gas (He gas). Further, by closing the second electromagnetic valve V2, the first solenoid valve connected to the vacuum pump 20 is closed.
It is provided so that the tracer gas (He gas) flowing into the compartment 30 does not flow out to another path connected via the fourth pipe V4 communicating with the pipe V1.

When the third electromagnetic valve V3 is opened, the detector 40 detects the amount of tracer gas (He gas) flowing into the compartment 30 through the second pipe P2,
This is converted into an electric signal, and the detected signal is
0 is output to the determination unit. This makes it possible to measure whether or not the tracer gas is leaking from the work X, or whether or not the leak is more than an allowable limit.

The control device 50 includes an arithmetic processing unit, a storage unit, an input / output unit, and the like, and performs arithmetic processing based on a program stored in the storage unit. Thus, for example, when a drive signal is sent to a movable lid driving device (not shown) that moves the movable lid of the vacuum chamber 10, the servo motor of the movable lid driving device is driven to move the movable lid by a predetermined amount. And stop at a predetermined position. When a drive signal is sent to the vacuum pump 20, the vacuum pump 20 is driven, and when a stop signal is sent, the drive of the vacuum pump 20 is stopped. When the pressure in the vacuum chamber 10 reaches a predetermined pressure, the control device 50 sends a close signal to the second electromagnetic valve V2 to close the second electromagnetic valve V2,
An open signal is sent to the electromagnetic valve V3, and the third electromagnetic valve V
3 is opened.

The control device 50 controls each of the electromagnetic valves V1,
Send an open signal or a close signal to V2, V3, V4
Each of the electromagnetic valves V1, V2, V3, V4 is set to an open state or a closed state. Further, when a detection start signal is transmitted to the detector 40, the detector 40 starts detection of a tracer gas (He gas). On the other hand, when the detector 40 detects the tracer gas (He gas), the control device 50 receives this detection signal, and the determination unit of the control device 50 determines the work X
It is determined whether or not the tracer gas is leaking from, or whether the leak is more than the allowable limit.

2. Leak Test Method Next, a description will be given of a work leak test method using the leak test apparatus configured as described above. (1) Preparation of a subject (work) First, a tracer gas (He gas) is filled from an opening (not shown) provided in the work, and a sealing stopper is fitted into the opening to form a tracer gas (He). Gas) in the work. In this case, the filling pressure of the tracer gas (He gas) is approximately the same as the atmospheric pressure.

Thereafter, after the work is placed on the movable lid of the vacuum chamber 10 and the start switch provided in the controller 50 is turned on, the controller 50 sends a drive signal to a movable lid moving device (not shown). I do. Then, the movable lid moving device is driven to move the movable lid to the lower end of the fixed box and stop it. Thereby, the inside of the vacuum chamber 10 becomes airtight. When the start switch is turned on, the control device 5
0 sends a drive signal to the vacuum pump 20 to send
0 is driven. At this time, each electromagnetic valve V1, V2,
V3 and V4 are closed.

(2) Leak test Next, the control device 50 sends an open signal to the first electromagnetic valve V1 and the second electromagnetic valve V2, and the first electromagnetic valve V1
And the second electromagnetic valve V2 is opened. As a result, the air in the vacuum chamber 10 is exhausted, and the inside of the vacuum chamber 10 is reduced in pressure more than the work X. As a result, a differential pressure is generated between the inside of the vacuum chamber 10 and the inside of the work X, and the tracer gas (He gas) filled in the work X is generated.
Leaks into the vacuum chamber 10, and the leaked tracer gas (He gas) flows into the compartment 30.

Next, when the pressure inside the vacuum chamber 10 reaches a predetermined pressure, the pressure gauge provided in the vacuum chamber 10 sends a detection signal to the control device 50. As a result, the control device 50 sends a close signal to the second solenoid valve V2 to close the second solenoid valve V2, and sends an open signal to the third solenoid valve V3 to send the open signal to the third solenoid valve V3. Open. Accordingly, the tracer gas (He gas) flowing into the compartment 30 flows into the detector 40, and the detector 40 starts detecting the tracer gas (He gas).

Next, the controller 50 controls the first solenoid valve V
1 to close the first solenoid valve V1. As a result, the communication between the compartment 30 and the vacuum chamber 10 is interrupted, and the detector 40 that has started detecting the tracer gas (He gas) continues to detect the tracer gas (He gas), thereby detecting the He gas. The detection amount is converted into an electric signal, and the detection signal is output to the determination unit of the control device 50. This makes it possible to determine whether or not the tracer gas is leaking from the work X or whether or not the leak is more than the allowable limit. Further, since the communication between the vacuum chamber 10 and the compartment 30 is interrupted, it is possible to arrange another subject to be examined in the vacuum chamber 10.

(3) Replacement of Work Stored in Vacuum Chamber Whether the detector 40 has leaked tracer gas or not
Alternatively, while determining whether or not the leakage exceeds the allowable limit, the control device 50 sends an open signal to the fourth electromagnetic valve V4 to open the fourth electromagnetic valve V4. Thereby, the inside of the vacuum chamber 10 communicates with the atmosphere via the pipe P3, and the vacuum state in the vacuum chamber 10 is released. Next, the control device 50 sends a drive signal to a movable lid moving device (not shown). Then, the movable lid moving device is driven to lower the movable lid until the upper end of the work X is located below the lower end of the fixed box, and then stops at the predetermined position. Then, the work X can be taken out from the movable lid and replaced with another work to be inspected.

When the detector 40 completes the detection of the tracer gas, that is, the detector 40 outputs a detection signal to the determination unit of the control device 50 to determine whether or not the tracer gas is leaking from the work X, or whether the tracer gas exceeds the allowable limit. When the determination as to whether or not the leakage has occurred is completed, the control device 50 sends a close signal to the third electromagnetic valve V3 to close the third electromagnetic valve V3. Thus, the detector 40 completes the preparation for detecting the tracer gas from the replaced work.

As described above, in the present invention, the detector 40 detects the detected amount of the tracer gas (He gas) and determines whether or not the tracer gas is leaking, or whether or not the leak is more than an allowable limit. While performing the judgment of
Since the communication between the vacuum chamber 10 and the compartment 30 is interrupted, it is possible to arrange another work to be inspected in the vacuum chamber 10. For this reason, it is possible to shorten the cycle time for inspection.

Note that the control device 50 controls the first electromagnetic valve V1.
If the time for sending the close signal to the first solenoid valve V1 is shortened and the time for closing the first solenoid valve V1 is increased, the work replacement cycle can be shortened.
If the time at which 0 closes the first electromagnetic valve V1 to send the close signal to the first electromagnetic valve V1 is increased, and the time during which the first electromagnetic valve V1 is closed is increased, the work replacement cycle can be delayed.

The detector 40 detects the tracer gas (H
The second solenoid valve V2 is in the closed state while the detection amount of e gas) is detected to determine whether or not the tracer gas is leaking, or whether or not the leak is more than the allowable limit. Therefore, the space between the compartment 30 and the vacuum pump 20 is in a cutoff state. For this reason, even if the vacuum pump 20 is in a driving state, the tracer gas flowing into the compartment 30 is
Since the partial pressure of the tracer gas is high, the detection sensitivity of the tracer gas can be increased.

Further, while the detector 40 detects the detected amount of the tracer gas (He gas) and determines whether or not the tracer gas is leaking, or whether or not the leak is more than an allowable limit. , The second electromagnetic valve V2 is in a closed state. For this reason, as shown in FIG.
If a not-shown electromagnetic valve is connected via a fourth pipe P4 connected to and connected to another vacuum chamber via this electromagnetic valve, a plurality of vacuum chambers connected via the first pipe P1 can be connected. Even if the air in the chamber is sucked, the detection amount of the tracer gas (He gas) in the chamber 30 is in a cutoff state between the chamber 30 and the vacuum pump 20. Detection can be performed without being affected by (He gas).

As a result, while the detection of the tracer gas (He gas) in one vacuum chamber is being performed, the work in another vacuum chamber can be exchanged in parallel. It is possible to detect tracer gas (He gas) in a plurality of vacuum chambers using the vacuum pump 10 described above, and it is possible to construct this kind of leak test system at low cost. The number of vacuum chambers to be connected to one vacuum pump 10 is appropriately selected according to the length of the work replacement time and the length of the leak inspection time so that the number becomes efficient. do it.

In the above-described embodiment, an example has been described in which the compartment 30 is provided separately from the first pipe P1, but the first inner diameter is large enough to accumulate tracer gas.
When the pipe P1 is used, it is not necessary to newly provide the compartment 30, and the inside of the first pipe P1 partitioned between the first solenoid valve V1 and the second solenoid valve V2 can be used as the compartment. . Further, in the above-described embodiment, an example has been described in which the opening and closing of each electromagnetic valve is automatically controlled by the control device. However, each electromagnetic valve may be opened and closed manually. In this case, another valve may be used instead of the electromagnetic valve.

Further, in the above-described embodiment, the filling pressure of the tracer gas in the subject (work) X is set to about the atmospheric pressure, and the pressure in the chamber and the compartment is reduced by the vacuum pump. If the specimen can withstand high pressure,
A leak test is performed with the tracer gas coming into the chamber by setting the filling pressure of the tracer gas in the subject higher than the atmospheric pressure and generating a differential pressure without reducing the pressure in the chamber with a vacuum pump or the like. You may do so. In this case, each time a leak test is performed, an inert gas other than helium, for example, a neon gas, a xenon gas, or the like may be passed through the compartment to wash the tracer gas.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a leak test apparatus of the present invention.

FIG. 2 is a block diagram schematically showing a conventional leak test apparatus.

[Explanation of symbols]

X: subject (work), 10: vacuum chamber, 20: vacuum pump, 30: compartment, 40: gas detector (detector), 50: control device, P1: first pipe, P2: second pipe, P3 ... 3rd piping, V1 ... 1st electromagnetic valve, V2 ... 2nd electromagnetic valve, V3 ... 3rd electromagnetic valve, V4 ... 4th electromagnetic valve

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazunari Kubota 10-1 Nakazawa-cho, Hamamatsu-shi, Shizuoka F-term in Yamaha Corporation (reference) 2G067 BB31 BB38 CC11

Claims (5)

[Claims] 1. A leak test method for determining whether or not a tracer gas filled in a subject is leaking from the subject or a leak exceeding an allowable limit, wherein the tracer gas is used. A storage step of storing the filled specimen in a vacuum chamber, a decompression step of reducing the pressure in the vacuum chamber to be lower than that of the specimen by a vacuum pump, and a step in which the inside of the vacuum chamber is set to a predetermined pressure. Upon reaching, the communication between the vacuum pump and the compartment formed between the vacuum chamber and the vacuum pump is cut off, and the communication between the compartment and the gas detector is performed so that A communication step of communicating the leaked tracer gas to the gas detector via the compartment; a blocking step of blocking between the vacuum chamber and the compartment; and exchanging the subject for another subject You Leakage test methods is characterized in that so as to include an interchangeable process. 2. A leak test method for determining whether a tracer gas filled in a subject is leaking from the subject or a leak exceeding an allowable limit, wherein the tracer gas is used. A storage step of storing the filled specimen in a chamber, and a communication step of communicating the tracer gas leaked from the specimen stored in the chamber to a gas detector via a compartment; A shutoff step of shutting off the chamber and the compartment; a determination step of detecting the tracer gas in the compartment shut off in the shutoff step to make the determination; exchanging the subject for another subject A leak test method characterized by comprising a replacement step. 3. A leak test apparatus for hermetically storing an object filled with a tracer gas in a vacuum chamber and detecting the tracer gas leaked into the vacuum chamber, A vacuum pump connected through one pipe to reduce the pressure in the vacuum chamber to a level lower than that of the subject; and a vacuum pump disposed between the vacuum chamber and the vacuum pump through the first pipe. And a compartment connected to the vacuum pump; a gas detector connected to the compartment via a second pipe to detect the tracer gas flowing into the compartment; and the vacuum chamber and the compartment A first valve connected to the first pipe between the first chamber and the first chamber to communicate the vacuum chamber with the compartment; and a first chamber connected to the first pipe between the compartment and the vacuum pump. And the vacuum pump And a third valve connected to the second pipe between the compartment and the gas detector for communicating the compartment with the gas detector. Characteristic leak test equipment. 4. When the vacuum pump is driven, the first valve and the second valve are opened to reduce the pressure in the vacuum chamber to a level lower than that of the subject, and then the second valve is closed. While the third valve is opened to start detection of the tracer gas by the gas detector, and then the first valve is closed to detect the tracer gas by the gas detector. 4. The leak test apparatus according to claim 3, wherein the test object stored in the vacuum chamber can be replaced with another test object. 5. A leak test apparatus comprising: a chamber for hermetically containing an analyte filled with tracer gas; and a gas detector for detecting the tracer gas leaked into the chamber. A compartment disposed between the detector and the chamber; and a valve for shutting off the compartment and the chamber, wherein the gas detector connected to the compartment includes the valve Detecting the tracer gas in a state where the compartment is shut off with respect to the chamber, and whether or not the tracer gas filled in the subject is leaking from the subject or a leak exceeding an allowable limit. A leak test device characterized in that it is determined whether or not the leak test is performed.