JPH0611408A - Leak inspection device - Google Patents

Abstract

PURPOSE:To inspect leak even though a component as object has a minute capacity by giving an air pressure directly to a work capsule and a master capsule, and furnishing a control valve and a capacity changing means in the air supply path to each of the capsules. CONSTITUTION:An air pressure P is given to a work capsule 6A and master capsule 6B, and with this air pressure P a diaphragm DF is contacted with the wall of a chamber C1. After the air pressure P is stabilized, two-way control valves 4A, 4B are closed. In this condition, the sensitivity of a differential pressure sensor 7 is raised electrically, and it is checked whether a differential pressure is generated. If yes, it is known that a minute leak exists. If a work 8 has as large a leak as admitting air intrusion momentarily, there is no differential pressure generation, when the A-B of a three-way solenoid valve 13 is changed over into continuity for giving the air pressure to the chamber C1 in order to inspect whether any larger leak exists. Eventual differential pressure is sensed from the capacity difference on the work capsule 6A and master capsule 6B, and a judging device 10 judges that it is a large leak.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leakage inspection device used for inspecting a sealed container having a small volume for leakage.

[0002]

2. Description of the Related Art Conventionally, FIG. 2 shows an example of an apparatus for inspecting for leaks in electronic parts such as a crystal oscillator, a reed relay or a relay housed in a container, and a sealed container such as a wrist watch. A leak detection device of volume difference detection type is used. The leak inspection apparatus shown in FIG. 2 includes an air pressure source 1 that generates a constant air pressure, a three-way solenoid valve 2 that shuts off the air pressure generated by the air pressure source 1, and a three-way solenoid valve 2 of this type.
3C connected to the output side B of the branch and branching the air pressure of the air pressure source 1 into two passages 3A, 3B, and this branch pipe 3C
The two-way solenoid valves 4A and 4B that are inserted into the two passages 3A and 3B that are branched by, and that intermittently operate the air pressure that is branched into the passages 3A and 3B, and the output side of the two-way solenoid valves 4A and 4B. Tanks TN1, which are provided and have the same internal volume as each other
TN2, two-way solenoid valves provided on the output side of the tanks TN1 and TN2, work capsules 6A and master capsules 6B connected to the respective output sides of the two-way solenoid valves 5A and 5B, and these work capsules 6A And a pressure difference between the master capsule 6B and the master capsule 6B.

In this structure, the three-way solenoid valve 2 is connected to AB
The two-way solenoid valves 4A and 4A are controlled so that they communicate with each other.
B is opened and the air pressure of the air pressure source 1 is set to the tanks TN1 and TN2.
Give to. In this case, the two-way solenoid valves 5A and 5B are closed. Therefore, the pressure output from the air pressure source 1 is stored in the tanks TN1 and TN2. Tanks TN1 and TN2
When the air pressure is stabilized, the two-way solenoid valves 4A and 4B are closed, and the two-way solenoid valves 5A and 5B are opened instead. By controlling the two-way solenoid valves 5A and 5B to be in the open state, the air pressure stored in the tanks TN1 and TN2 is given to the work capsule 6A and the master capsule 6B.

Although not particularly shown, the work capsule 6A and the master capsule 6B are provided with lids which can be opened and closed. A master container 9 having the same volume as the work 8 is previously inserted into the master capsule 6B, and the work 8 is replaced by opening and closing the lid of the work capsule 6A. By inserting the work 8 into the work capsule 6A, the volume inside the void (the total volume including the capsule and the pipe) on the side of the work capsule 6A and the side of the master capsule 6B become equal.

Work capsule 6A and master capsule 6B
When a certain amount of air pressure is released from the tanks TN1 and TN2, no differential pressure is generated between the work capsule 6A and the master capsule 6B unless the work 8 is significantly leaked. Also, it can be seen that there is no small leak if the differential pressure does not gradually occur thereafter. Therefore, in this case, the determination device 1
0 determines that the work 8 is a good product.

On the other hand, when a constant pressure is applied to the work capsule 6A and the master capsule 6B from the tanks TN1 and TN2, if the differential pressure is detected by the differential pressure detector 7, the determination device 10 determines that the work 8 is to be operated. Judge that there is a big leak. In other words, it can be understood that there is a relatively large leakage when the differential pressure occurs immediately after the air pressure is applied to the work capsule 6A and the master capsule 6B. Further, when a certain time elapses after the supply of the air pressure and the solenoid valves 5A and 5B are closed, and the differential pressure value gradually increases in this state, the determination device 10 determines that there is a small leak.

When the inspection is completed, the two-way solenoid valves 4A and 4B
Then, the three-way solenoid valve 2 is switched to a state in which BC is in communication, the air passages 3A and 3B are opened to the atmosphere, and the pressure difference between the work capsule 6A and the master capsule 6B is returned to atmospheric pressure.
The lid of the work capsule 6A is opened, the work 8 is replaced, and the work 8 is inspected again through the same process as described above.

[0008]

In the conventional device,
When the volume of the work 8 is small, there is a drawback that the presence or absence of the leak cannot be detected. In other words, the internal volume (internal volume of voids) of the work capsule, the piping leading to the work capsule, the solenoid valve, etc. is finite and cannot be set to a minute value. Therefore, when the inner volume of the work 8 becomes small, the inner volume of the void and the work 8
This is because the ratio of the internal pressure to the internal volume increases and the differential pressure generation sensitivity decreases. Therefore, in order to increase the differential pressure generation sensitivity by the conventional technique, the void volume must be made as small as possible. For this reason, the solenoid valves 5A and 5B are closed and the tanks TN1 and TN2 are separated to reduce the volume of the void, but there is a limit to this. As a result, the volume of the work 8 that can be inspected by the conventional technique is up to about 1 cc, and there is an inconvenience that the leak inspection cannot be performed on the work having a volume less than this.

As a recent trend, miniaturization is active in every field. In particular, in the field of electronic components, various components such as reed relays and crystal oscillators have been miniaturized, and there is a demand for a technique capable of inspecting a component having a minute volume for leakage.

[0010]

According to the present invention, air pressure is directly applied to a work capsule and a master capsule from an air pressure source, and a two-way air pressure control type control valve and a variable volume are provided in an air pressure supply path leading to the work capsule and the master capsule. And means are provided. After the air pressure of a predetermined pressure is applied to the work capsule and the master capsule, the two-way control valve is closed to disconnect the air pressure source from the work capsule and the master capsule. In this state, it is determined whether or not the differential pressure is gradually generated, and the presence or absence of minute leakage of the work 8 is determined. If there is no minute leak, the variable volume means is variably controlled to change the volume inside the void on the work capsule side and the volume on the master capsule side by equal amounts.

If there is a large leak due to the change in the internal volume, the internal volume of the work is instantaneously added to the internal volume of the work capsule when the air pressure is applied. Therefore, a difference occurs in the internal volume between the work capsule side and the master capsule side, and a pressure difference is generated due to this volume difference. If there is no leak in the work, no differential pressure is generated even if the variable volume means is variably controlled.

Therefore, according to the present invention, it is possible to inspect the presence or absence of leakage even for a component having a very small volume.

[0013]

FIG. 1 shows an embodiment of the present invention. In the figure, 1 is an air pressure source, 2 is a 3-way solenoid valve, 4A and 4B are 2-way control valves,
6A is a work capsule, 6B is a master capsule, and 7 is a differential pressure detector, which is the same as the conventional technique. In this invention, the variable volume means 12A and 12B are provided in communication with the work capsule 6A and the master capsule 6B. In this example, the case where the variable volume means 12A and 12B are constituted by the diaphragm DF is shown. One chamber C ₂ partitioned by the diaphragm DF is connected to the work capsule 6A and the master capsule 6B, and the other chamber C ₁ is connected to the air pressure source 14 through the three-way solenoid valve 13.

Although the air pressure source 14 generates a positive pressure higher than the pressure of the air pressure source 1, the three-way solenoid valve 13 is B-
Connect between C. Therefore, at the start of the inspection, the pressure of the air pressure source 14 is not applied to the diaphragm DF, and the one chamber C ₁ partitioned by the diaphragm DF is open to the atmosphere. In this state, air pressure P is applied from the air pressure source 1 to the work capsule 6A and the master capsule 6B. Therefore, at this time, the diaphragm DF is pressed against the wall of the chamber C ₁ by the air pressure P. The two-way control valves 4A and 4B are closed after the time required for the air pressure P to stabilize. In this state, the detection sensitivity of the differential pressure detector 7 is electrically increased to check whether or not a differential pressure is generated. When a differential pressure occurs, it can be seen that there is a minute leak. When there is a large leak such that the air instantly enters the work 8, the air supplied from the air pressure source 1 instantly enters the work 8, so that no differential pressure is generated.

If no differential pressure is generated, it is inspected whether there is a large leak. Therefore, in the present invention, the three-way solenoid valve 13 inserted on the side of the air pressure source 14 is switched to the state of communicating between A and B, and the chamber C ₁ partitioned by the diaphragm DF is switched.
The pressure of the air pressure source 14 is applied to. Since the pressure of the air pressure source 14 is larger than the test pressure P, the diaphragm D
F is pressed against the wall of chamber C ₂ . Due to the movement of the diaphragm DF, the apparent inner volumes of the work capsule 6A and the master capsule 6B are reduced by the amount of the inner volumes of the chambers C ₁ and C ₂ . Due to this volume change, if there is a difference in volume between the work capsule 6A side and the master capsule 6B side, a differential pressure is generated, and the differential pressure is detected by the differential pressure detector 7 and a large leak is made by the determination device 10. It is determined that there is.

Work capsule 6A side and master capsule 6
By matching the volume including the piping with the B side and inserting a master container 9 of the same capacity as the work 8 which does not leak into the master capsule 6B, the work capsule 8 can be leaked if it does not leak. The volumes on the 6A side and the master capsule 6B side are equal. Therefore, in this case, the volume changing means 1
Even if the volume is changed between 2A and 12B, no differential pressure is generated between them.

However, when the work 8 is leaked, the inner volume of the work 8 is added to the inner volume of the work capsule 6A, so that a difference in inner volume occurs between the work capsule 6A side and the master capsule 6B side. To do. As a result, when the volume changing means 12A and 12B change the volume, a differential pressure proportional to the volume difference is generated. This will be described using mathematical expressions. As a condition of the work 8 used here, there is a relatively large leak, and air enters the work 8 in a short time. The inner volume of the work 8 is ΔV, the inner volume of the work capsule 6A and the master capsule 6B (not including the inner volume ΔV of the work 8 and the master container 9) is V, and the volume varying means 12A, 12B.
Is ΔV ₁ , the air pressure (test pressure) given from the air pressure source 1 is P, the pressure change on the work capsule side when the volume of the volume changing means 12A, 12B changes ΔV ₁ , ΔP ₁ , the master capsule side If the pressure change is ΔP ₂ , the work side P (V + ΔV + ΔV ₁ ) = (P + ΔP ₁ ) (V + ΔV−ΔV ₁ ) (1) Master side P (V + ΔV ₁ ) = (P + ΔP ₂ ) (V−ΔV ₁ ) …… (2) From formula (1), ΔP ₁ = 2P × ΔV ₁ / (V + ΔV−ΔV ₁ ) …… (3) From formula (2), ΔP ₂ = 2P × ΔV ₁ / (V−ΔV ₁ ) …… (4) ΔP ₂ −ΔP ₁ = 2P × ΔV ₁ × ΔV / (V−ΔV ₁ ) (V + ΔV−ΔV ₁ ) ... (5) From the formula (5), the sensitivity of the volume difference is the test pressure P and the volume change. It is proportional to ΔV ₁ and almost inversely proportional to the square of the internal volume V of the capsules 6A and 6B.

By the way, the internal volume V of the capsules 6A, 6B: 2 cc, the volume change amount ΔV ₁ : 0.3 of the volume varying means 12A, 12B.
cc Test pressure (absolute pressure) P: 1.5
kg / cm ² Work 8 internal volume ΔV: 0.0
When it is set to 1cc, ΔP ₂ −ΔP ₁ can be calculated from equation (5) as follows: ΔP ₂ −ΔP ₁ = 2P × 1.5 × 10 ⁴ × 0.3 × 0.01 / (2−0.3) (2 + 0.01−0.3) = 31 (mm H ₂ O), and this pressure difference can be sufficiently measured by an ordinary differential pressure detector.

[0019]

As described above, according to the present invention, it is possible to detect whether or not there is a leak, especially a large leak, even if the work 8 has a small internal volume of, for example, about 0.01 cc. Therefore, it is possible to obtain a great effect that it is possible to inspect a sealed container having a small volume such as an electronic component or a wristwatch for leakage. Further, in this invention, the control valves 4A and 4B are
Since an air-operated valve is used, it does not generate heat unlike an electromagnetic valve during operation, so there is no risk of temperature changes in the air circuit. Therefore, the inspection can be stably performed, and the inspection with high reliability can be performed.

In the above embodiment, the volume changing means 12
Although the example in which the diaphragm DF is used as A and 12B has been described, an element such as a cylinder or a bellows may be used as another element. Also, the volume changing means 1
Although 2A and 12B were changed in the direction of decreasing the volume of the void when inspecting for the presence of a large leak, the presence of a large leak can be inspected even if the volume of the void is increased.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining an embodiment of the present invention.

FIG. 2 is a block diagram for explaining a conventional technique.

[Explanation of symbols]

 1 Air Pressure Source 2 3 Way Solenoid Valve 4A, 4B 2 Way Control Valve 6A Work Capsule 6B Master Capsule 7 Differential Pressure Detector 8 Work 9 Master Container 12A, 12B Variable Volume Means 13 3 Way Solenoid Valve 14 Air Pressure Source

Claims (1)

[Claims] 1. A. An air pressure source for generating a constant pressure air pressure, and B. A work capsule and a master capsule to which the air pressure generated by the air pressure source is respectively applied; A pair of control valves that are inserted into the passages leading to the work capsule and the master capsule to open and close the passages; A differential pressure detector for measuring the pressure difference between the work capsule and the master capsule, E. A leak inspecting device comprising: volume varying means for varying the pressures applied to the work capsule and the master capsule by a fixed amount.