JP3132710B2 - Leak inspection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak inspection device used to inspect a sealed container for leaks.

[0002]

2. Description of the Related Art On December 11, 1991, the present applicant proposed a leak inspection apparatus "Japanese Patent Application No. 3-326267" which is suitable for inspecting a sealed container having a small volume for leakage. The leak inspection apparatus proposed above is provided with a volume changing means which communicates with the work capsule and the master capsule and changes the inner volumes of the work capsule and the master capsule by an equal amount, and the contents of the work capsule and the master capsule are changed by the volume changing means. When the product is changed, it is characterized in that it is configured to determine whether or not there is a leak in the work stored in the work capsule based on whether or not a differential pressure is generated between the work capsule and the master capsule. Is what you do.

[0003] FIG. 1 in the figure
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, 7
Indicates a differential pressure detector. Variable volume means 12A, 12B communicated with work capsule 6A and master capsule 6B
Is provided. In this example, the variable volume means 12A, 12A
A case where B is constituted by a diaphragm DF is shown. One chamber C ₂ partitioned by the diaphragm DF is communicated with the work capsule 6A and the master capsule 6B,
The other chamber C ₁ is connected to an air pressure source 14 through a three-way solenoid valve 13.

The pneumatic pressure source 14 generates a positive pressure higher than the pressure of the pneumatic pressure source 1.
C is communicated. Inspection At the beginning therefore, the pressure of the air pressure source 14 is not applied to the diaphragm DF, the chamber C ₁ of one partitioned by a diaphragm DF is open to the atmosphere. In this state, the air pressure P is applied from the air pressure source 1 to the work capsule 6A and the master capsule 6B. Therefore, the diaphragm DF by the time the air pressure P is pressed against the wall of the chamber C _1. After the time required for the air pressure P to stabilize, the two-way control valves 4A and 4B are closed. In this state, the detection sensitivity of the differential pressure detector 7 is electrically increased to check for the occurrence of a differential pressure. When a differential pressure is generated, it is understood that there is a small leak. If there is a large leak such that air instantaneously enters the work 8, the differential pressure does not occur because the air supplied from the air pressure source 1 instantaneously enters the work 8.

If no differential pressure is generated, it is checked whether there is a large leak. For this reason, the three-way solenoid valve 13 inserted on the side of the air pressure source 14 is switched to a state in which communication is performed between AB and the air pressure source 1 is inserted into the chamber C ₁ partitioned by the diaphragm DF.
Apply a pressure of 4. Since the pressure of the air pressure source 14 is taken larger than the test pressure P, the diaphragm DF is pressed against the wall of the chamber C _2. By the movement of the diaphragm DF,
Internal volume of the apparent work capsules 6A and master capsule 6B is smaller by an amount obtained by adding the internal volume of the chamber C ₁ and C _2. Due to this volume change, the work capsule 6
When there is a difference in volume between the A side and the master capsule 6B side, a differential pressure is generated, and the differential pressure is detected by the differential pressure detector 7, the determination device 10 determines that there is a large leak, and the display device 11 determines The result of the determination is displayed.

The work capsule 6A side and the master capsule 6
The volume including the piping is matched with the side B, and a master container 9 having the same capacity as the work 8 is inserted into the master capsule 6B. The volumes of 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 pressure difference occurs between them.

However, when the work 8 has a large leak, the inner volume of the work 8 is added to the inner volume of the work capsule 6A, so that there is a difference in the inner volume between the work capsule 6A and the master capsule 6B. appear. As a result, when a volume change is given by the volume variable means 12A and 12B, a pressure difference proportional to the volume difference is generated.

[0008]

In the leak inspection apparatus proposed above, both of the volume variable amounts of the volume variable means match, and the internal volumes of both the work capsule 6A side and the master capsule 6B side include the piping. If they match each other, it is possible to determine the presence or absence of leakage even for a minute object having an inner volume of the work 8 of, for example, 0.01 cc and an outer volume of about 0.05 cc.

[0009] However, even if the volume variable amounts of the volume variable means 12A and 12B can be matched, the work capsule 6 does not.
It is difficult to match the internal volumes of both side A and master capsule 6B. In other words, even if there is a slight difference in the length of the pipes connected to the capsules 6A and 6B, or irregular deformation, etc., a volume difference occurs. Due to this volume difference, a differential pressure is generated even if the work 8 is a good product. There is an inconvenience. In order to completely match the internal volumes of the work side and the master side, a great deal of labor is required, and a troublesome adjustment operation is forced. Moreover, such labor is troublesome because it must be performed each time the type of capsule is changed.

An object of the present invention is to provide a leakage inspection apparatus capable of accurately determining whether or not a work has leaked even if there is a volume difference between the work capsule side and the master capsule side. .

[0011]

According to the present invention, even if there is a volume difference between the work capsule side and the master capsule side, a differential pressure value caused by the volume difference is measured in advance to obtain a zero point fluctuation value. The zero point fluctuation value is stored and subtracted from the differential pressure value generated at the time of inspecting the work.

Therefore, according to the configuration of the present invention, even if there is a volume difference between the work capsule side and the master capsule side, a differential pressure value generated by the volume difference is measured and stored in advance, and the stored value is stored. Since the differential pressure value is subtracted from the differential pressure value generated at the time of work inspection and is electrically corrected, the internal volumes of the work capsule side and the master capsule side do not always have to be matched with high accuracy.

Therefore, even when the types of the work capsule and the master capsule are exchanged, it is only necessary to measure the differential pressure value generated by the volume difference once and to store the measurement result in the storage means. There is no need to perform matching work. Therefore, it is possible to provide an easy-to-use leak inspection device.

[0014]

FIG. 1 shows an embodiment of the present invention. In FIG. 1, parts corresponding to those in FIG. 2 are denoted by the same reference numerals.
In FIG. 1, 1 is an air pressure source, 2 is a three-way solenoid valve, 4A, 4
B is a two-way control valve, 6A is a work capsule, 6B is a master capsule, 7 is a differential pressure detector, 8 is a work, 9 is a master container, 10 is a judging device, 11 is a display for displaying a pass / fail judgment result, 12A. , 12B are volume variable means, 13 is a three-way solenoid valve, and 14 is an air pressure source, as in the description of FIG.

In the present invention, the variable volume means 12A,
12B, a differential pressure value generated based on the internal volume difference between the work capsule 6A and the master capsule 6B is measured in advance as a zero point fluctuation value, and the zero point is stored. Variation storage means is provided. As the zero point fluctuation storage means, for example, a RAM 1 attached to, for example, a microcomputer constituting the determination device 10
It can be provided in a part of OC. That is, the microcomputer is a central processing unit 10A called a CPU.
A ROM 10B storing a program for operating the central processing unit 10A in a predetermined order; a RAM 10C for temporarily storing measurement data and the like;
0D and an output port 10E.

The zero point fluctuation storage means can be provided in a part of the RAM 10C, and is denoted by reference numeral 10F. The differential pressure value generated by the internal volume difference existing between the work capsule 6A and the master capsule 6B is stored in the zero point fluctuation storage means 10F. For this purpose, a good product without leakage is inserted into the work capsule 6A and the master capsule 6A is inserted.
The master container 9 having the same internal volume as the non-defective product is also inserted into the B side, and in this state, air pressure is applied from the air pressure source 1 to the work capsule 6A and the master capsule 6B. With the air pressure stabilized, the control valves 4A and 4B are closed to apply the same pressure to the work capsule 6A and the master capsule 6B. At this time, since the container inserted into the work capsule 6A and the master container 9 are non-defective, no differential pressure detection signal is output from the differential pressure detector 7 due to leakage.

[0017] By controlling the solenoid valve 13 in this state to the state between the A-B is communicated, it is given a higher pressure than the pressure measured in chamber C ₁ of the variable volume means 12A and 12B. Thus the diaphragm DF is pressed against the wall of the chamber C ₂ away from the wall of the chamber C _1. Work capsule 6 by moving diaphragm DF
The inner volume change is given to the A side and the master capsule 6B side.

If the inner volume of the work capsule 6A is smaller than the inner volume of the master capsule 6B due to the change of the inner volume, the pressure of the work capsule 6A becomes higher than the pressure of the master capsule 6B. This differential pressure value is detected by the detection signal of the differential pressure detector 7 and stored in the zero point fluctuation storage means 10F. Thereafter, the work 8 is inserted into the work capsule 6A, and the presence or absence of leakage of the work 8 is inspected. At this time, the zero point fluctuation value is read from the storage means 10F, and the zero point fluctuation value is determined as the differential pressure value generated at the time of inspection. , The influence of the differential pressure value generated based on the inner volume difference between the work capsule side and the master capsule side can be eliminated. When a leak test is performed by setting the inside of the work capsule and the master capsule to a negative pressure, the above-described zero point fluctuation value is added to the measured value and removed. In the case of performing a leak test with a negative pressure, the volume variable means 1 is used.
2A and 12B change in the direction of increasing the volume.

[0019]

As described above, according to the present invention, after air pressure is applied to both the work capsule 6A and the master capsule 6B, the volume is changed while the supply passages for the air pressure are shut off by the control valves 4A and 4B. In a leak inspection apparatus for giving a volume change by means 12A and 12B and inspecting whether or not the work inserted into the work capsule 6A has a leak, the work capsule 6A side is caused by an inner volume difference between the master capsule 6B side. The differential pressure value to be measured is measured in advance as a zero point fluctuation value, stored in the storage means 10F, and the stored value is subtracted from the differential pressure value generated at the time of work inspection.
It is possible to eliminate the influence of the inner volume difference between the work capsule 6A and the master capsule 6B.

Therefore, it is possible to set a state in which a correct inspection can be performed without performing a troublesome adjustment operation for accurately matching the internal volume difference, and thus it is possible to provide a leak inspection apparatus which is easy to use.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air pressure source 2 Three-way solenoid valve 4A, 4B Two-way control valve 6A Work capsule 6B Master capsule 7 Differential pressure detector 8 Work 9 Master container 10 Judgment device 10F Zero point change storage means 11 Display 12A, 12B Volume variable means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-11408 (JP, A) Akio Furuse, “Air Leak Tester”, Sensor Technology, Technical Research Committee Co., Ltd., April 25, 1988, 8, No. 6, p. 247 -250 (58) Field surveyed (Int. Cl. ⁷ , DB name) G01M 3/00-3/40 JICST file (JOIS)

Claims (1)

(57) [Claims] After applying air pressure from a pneumatic pressure source to a work capsule and a master capsule, the air pressure supply path is shut off by a control valve, and a difference in air pressure between the work capsule and the master capsule is measured by a differential pressure gauge. And changing the inner volume communicating with the master capsule in a direction of decreasing (or increasing) by a fixed amount by a volume varying means, and as a result, allowing the differential pressure gauge to detect the presence or absence of a differential pressure, thereby storing the differential in the work capsule. A leak test device configured to determine whether or not there is a leak in the work, wherein a non-defective product is stored in the work capsule and the master capsule, and the differential pressure generated by changing the volume by the volume changing means in a state where the non-defective product is stored. Set the value to the work capsule side and master
The zero-point fluctuation value stored in the zero-point fluctuation storage means is stored as a zero-point fluctuation value generated by the internal volume difference on the capsule side, and thereafter, each time a work is inspected, the zero-point fluctuation value stored in the zero-point fluctuation storage means is generated by the differential pressure gauge. A leak inspection device characterized in that it is configured to remove from a value.