JP2001311677A - Air leak test apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly acquire correction values for leak tests with a good workability. SOLUTION: Opening/closing valves 4a and 4b are set on branching passages 12a and 12b. Capsules 5a and 5b and capacity-changing means 20a and 20b are connected to the downstream side of the branching passages 12a and 12b. In a test mode, a work W is stored in the capsule 5a and a master member M is stored in the capsule 5b. A test pressure is supplied in a state with the opening/closing valves 4a and 4b being opened. A slight leak of the work W is detected on the basis of a detected differential pressure of a differential pressure sensor 6 after closing the opening/closing valves. Further, the capacity- changing means 20a and 20b are changed by an equal quantity to detect a large leak of the work W on the basis of the detected differential pressure of the differential pressure sensor 6. In a correction value acquirement mode, while the capsules 5a and 5b are made empty, the above control is carried out and the detected differential pressure after the capacity change is stored as the correction value. The large leak is determined on the basis of a value obtained by subtracting the correction value from the detected differential pressure after the capacity change in the test mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air leak test apparatus particularly suitable for inspecting a small volume sealed container for leaks.

[0002]

2. Description of the Related Art In a differential pressure type air leak test apparatus for detecting leakage of a work, which is a sealed container having a small volume, with high accuracy, an air passage has a common passage connected to an air pressure source and a work branched from the common passage. A side branch passage and a master side branch passage are provided. At the downstream end of the work-side branch passage, a work capsule that stores a work to be inspected for leakage is connected, and at the downstream end of the master-side branch passage, a master that stores a work without leakage as a master member. The capsule is connected. A three-way valve is provided in the common passage, and an opening / closing valve is provided in each of the work-side and master-side branch passages. The differential pressure between the work-side and master-side branch passages downstream of the on-off valve is detected by a differential pressure sensor.

In the air leak test mode, the control unit drives the three-way valve with the pair of on-off valves open to supply the work capsule and the master capsule with the air pressure of the air pressure source as a test pressure. Close the on-off valve,
The presence or absence of a work leak is determined based on the differential pressure detected by the differential pressure sensor in this state.

[0004] In the above-described apparatus, when the work has a minute flaw and air enters the work over time,
Although it can be detected as a minute leak, if there is a large scratch, it is determined that there is no leak. This is because, when the test pressure is supplied, the air of the test pressure enters the work at a stretch and the on-off valve is closed thereafter, so that the pressure of the work side closing system does not decrease and no differential pressure is generated.

Therefore, an apparatus has been developed which detects not only a minute leak but also a large leak. JP-A-10-622
In the apparatus disclosed in Japanese Patent Application Publication No. 96-96, a volume changing unit is provided in each of the branch passages on the work side and the master side. Each of the volume changing means includes an auxiliary passage connected between the on-off valve (hereinafter, referred to as a first on-off valve) and the capsule in the branch passage, a second on-off valve provided in the auxiliary passage, A tank connected to the downstream end.

In the device disclosed in the above publication, after the first on-off valve is closed to determine the presence or absence of minute leakage, the second on-off valve is opened to release the air pressure to the tank, and the differential pressure sensor detects the air pressure in this state. Based on the differential pressure, it is determined whether there is a large leak of the work. That is, the closed system on the work side and the closed system on the master side have the same volume when the second on-off valve is closed, and the same volume when the second on-off valve is open. For example, the differential pressure detected by the differential pressure sensor is zero. If there is a large leak in the work, the pressure on the work side is increased by the test pressure that has entered the work, and a differential pressure is generated between the work side and the master side.

On the other hand, in the air leak test apparatus disclosed in Japanese Patent Application Laid-Open No. 57-211032, a first on-off valve and a second on-off valve are provided in the branch passage on the work side and the master side in order from the upstream side. A tank having the same volume is provided between the first and second on-off valves. In this device, the air pressure of the air pressure source is stored in the tank with the second on-off valve closed and the first on-off valve opened. Next, by closing the first on-off valve and opening the second on-off valve, an air pressure lower than the air pressure of the air pressure source is supplied as a test pressure to the work capsule and the master capsule. Then, the presence or absence of leakage is detected from the differential pressure in this state. That is, the closed system on the work side and the closed system on the master side have the same volume when the second on-off valve is closed, and the same volume when the second on-off valve is open. For example, the pressure in both closed systems is maintained at the test pressure, and the differential pressure detected by the differential pressure sensor is zero. If there is a large leak in the work, air pressure will enter the work at a stretch, and if there is a minute leak in the work, the air pressure will gradually enter the work. A pressure difference occurs between the closed systems on the master side.

However, in the two types of apparatuses disclosed in the publications, the volumes of the closing systems on the work side and the master side before opening the second on-off valve are equalized, and the closing after opening the second on-off valve. The volume of the system must be equal. However, it is difficult to match the volumes of the closed system on the workpiece side and the master side with high accuracy due to a manufacturing error or the like, and there is a possibility that the reliability of leak determination may be impaired.

In the air leak test apparatus disclosed in Japanese Patent Application Laid-Open No. H8-75592, in an air leak test apparatus of a type similar to that described in the first publication, the control unit executes a correction value acquisition mode prior to the air leak test. ing. In other words, in a state where a good product, that is, a work without leakage is contained in the work capsule and the master capsule, the volume changing means is driven to change the volume of the branch passage, and then the differential pressure is detected, and the differential pressure value is corrected. Store as a value. Then, in the subsequent air leak test, by subtracting this correction value from the detected differential pressure value after the volume change, a differential pressure value that is not affected by the volume difference between the work side closed system and the master side closed system is calculated. A large leak is determined based on the pressure value.

[0010]

However, Japanese Patent Application Laid-open No.
According to Japanese Patent Laid-Open No. 75592/1995, in the correction value acquisition mode,
A good product (work without leakage) had to be set in both the work capsule and the master capsule, resulting in poor workability. Further, if there is a difference in the external volume between these non-defective products, the correction value may not be calculated with high accuracy, and it may take time to select non-defective products to be stored.

[0011]

According to a first aspect of the present invention, there is provided:
(A) a common passage connected to the air pressure source, a work-side branch passage and a master-side branch passage branched from the common passage, and (b) a pair of work passages provided in the work-side and master-side branch passages, respectively. An on-off valve, (c) a work capsule and a master capsule connected respectively to the work-side and master-side branch passages on the downstream side of the on-off valve, and (d) a work side and a master on the downstream side of the on-off valve. A differential pressure sensor for detecting a differential pressure between the side branch passages,
(E) A pair of volumes provided in the work-side and master-side branch passages downstream of the on-off valve, respectively, for changing the volumes of the work-side and master-side branch passages when the on-off valve is closed by an equal amount. A changing means, and (f) in an air leak test mode, a work to be inspected for leakage is housed in a work capsule, and a master member having the same outer volume as the work and having no leakage is housed in the master capsule. Is supplied to the work-side and master-side branch passages, and then a pair of on-off valves are closed. In this state, the presence or absence of minute leakage of the work is determined based on the differential pressure detected by the differential pressure sensor. By operating a pair of volume changing means at the same time, the volumes of the closed work side and the master side branch passages are changed by an equal amount, and based on the differential pressure detected by the differential pressure sensor in this state, And determining the control unit for leaks,
In the leak test device including the above, the control unit further executes a correction value acquisition mode, and in this correction value acquisition mode, the air pressure of the air pressure source is reduced while the master capsule and the work capsule are closed empty. By supplying to the work-side and master-side branch passages, and then closing the pair of on-off valves and then driving the pair of volume changing means, the closed work-side and master-side branch passages are made equal in volume. And a correction value is obtained and stored based on the differential pressure detected by the differential pressure sensor in this state, and a large leak is detected based on a value obtained by subtracting this correction value from the differential pressure detected when the large leak is detected in the test mode. It is characterized by determining the presence or absence.

According to a second aspect of the present invention, there are provided (a) a common passage connected to an air pressure source, a work-side branch passage and a master-side branch passage branched from the common passage, and (b) the work-side branch passage. (D) a pair of on-off valves provided in the master-side branch passage, and (c) a work capsule connected to the work-side branch passage downstream of the on-off valve.
A differential pressure sensor for detecting a differential pressure between the work-side and master-side branch passages downstream of the on-off valve; and (e) a downstream pressure sensor provided on the work-side and master-side branch passages downstream of the on-off valve. A pair of volume changing means for changing the volumes of the branch passages on the work side and the master side when the on-off valve is closed, and (f) accommodating the work to be inspected for leakage in the air leak test mode in the work capsule. In this condition, the air pressure of the air pressure source is supplied to the branch passage on the work side and the master side, and then a pair of on-off valves are closed. Then, by operating a pair of volume changing means, the volumes of the closed work side and master side branch passages are changed by an equal amount, and the differential pressure detected by the differential pressure sensor in this state is changed. Based on the And a control unit for determining the presence or absence of a large leak in the leak test apparatus, wherein the internal volume downstream of the open / close valve of the master side branch passage is set to the internal volume downstream of the open / close valve of the work side branch passage. , The control unit further executes a correction value acquisition mode.In this correction value acquisition mode, the work capsule contains a leak-free work and is closed. Supplying the air pressure of the air pressure source to the branch passage on the work side and the master side, and then closing the pair of on-off valves,
Next, by driving a pair of volume changing means, the volumes of the closed work-side branch passage and the master-side branch passage are changed by an equal amount, and a correction value is obtained based on the differential pressure detected by the differential pressure sensor in this state. In the test mode, the presence / absence of a large leak is determined based on a value obtained by subtracting this correction value from the detected differential pressure at the time of detecting the large leak.

According to a third aspect of the present invention, there are provided (a) a common passage connected to an air pressure source, a work-side branch passage and a master-side branch passage branched from the common passage, and (b) the work-side branch passage. A pair of first on-off valves provided in the master-side branch passage, and (c) a pair of second on-off valves provided on the work-side and master-side branch passages respectively downstream of the first on-off valve. A valve; (d) a work capsule and a master capsule respectively connected to the downstream side of the second on-off valve in the work-side and master-side branch passages; and (e) a work-side and master-side branch passage. A pair of tanks having the same capacity provided between the first on-off valve and the second on-off valve, and (f) a difference between the work-side and master-side branch passages downstream of the first on-off valve. Differential pressure sensor for detecting pressure In the air leak test mode, a work to be inspected for leakage is housed in a work capsule, and a master member having an outer volume equal to that of the work and having no leakage is housed in the master capsule. With the pair of second on-off valves closed, the air pressure of the air pressure source is supplied to the work-side and master-side branch passages, then the pair of first on-off valves are closed, and then the pair of second on-off valves are closed.
A control unit that opens and closes the on-off valve and determines whether or not there is leakage of the workpiece based on the differential pressure detected by the differential pressure sensor in this state, the control unit further executes a correction value acquisition mode Then, in this correction value acquisition mode, the master capsule and the work capsule are closed while being empty,
With the pair of first on-off valves opened and the pair of second on-off valves closed, the air pressure of the air pressure source is supplied to the work-side and master-side branch passages, and then the pair of first on-off valves are closed. Thereafter, the pair of second on-off valves are opened, a correction value is obtained and stored based on the differential pressure detected by the differential pressure sensor in this state, and the correction value is subtracted from the differential pressure detected at the time of leak detection in the test mode. It is characterized in that the presence or absence of leakage is determined based on the value.

According to a fourth aspect of the present invention, there are provided (a) a common passage connected to an air pressure source, a work-side branch passage and a master-side branch passage branched from the common passage, and (b) the work-side branch passage. A pair of first on-off valves provided in the master-side branch passage, and (c) a pair of second on-off valves provided on the work-side and master-side branch passages respectively downstream of the first on-off valve. A valve; (d) a work capsule connected downstream of the second on-off valve in the work-side branch passage; and (e) a first open-close valve in the work-side and master-side branch passage. And (f) a differential pressure sensor for detecting a differential pressure between the work-side and master-side branch passages downstream of the first on-off valve. And (g) air leak test mode The work to be inspected for leakage is accommodated in a work capsule, the pair of first on-off valves are opened, and the pair of second on-off valves are closed. And then close the pair of first on-off valves, and then open the pair of second on-off valves. In this state, the control unit determines whether there is leakage of the work based on the differential pressure detected by the differential pressure sensor. And a value obtained by subtracting the external volume of the work from the internal volume of the master-side branch passage downstream of the first on-off valve and the internal volume of the work-side branch passage downstream of the open / close valve. And the control unit further executes a correction value acquisition mode,
In the correction value acquisition mode, the work capsule contains and closes a work having no leakage, opens the pair of first opening / closing valves, and closes the pair of second opening / closing valves. Supply to the branch passage on the master side, then close the pair of first on-off valves, and then open the pair of second on-off valves. Obtain and store a correction value based on the differential pressure detected by the differential pressure sensor in this state. In the test mode, the presence or absence of a leak is determined based on a value obtained by subtracting this correction value from a differential pressure detected when a leak is detected.

According to a fifth aspect of the present invention, in the air leak test apparatus according to any one of the first to fourth aspects, a test mode is executed by using the correction value obtained in the correction value acquisition mode. The correction value is updated based on a plurality of data of the detected differential pressure value when it is determined that there is no pressure difference.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an air leak test apparatus according to the present invention will be described with reference to the drawings. The air leak test apparatus according to the first embodiment shown in FIG. The air passage 10 has a common passage 11, a work-side branch passage 12 a and a master-side branch passage 12 b connected to a downstream end of the common passage 11. Common passage 11
The compressed air source 1 is connected to the upstream end of the compressed air source 1. The common passage 11 is provided with a regulator 2 and a three-way valve 3 in order from the upstream side. The compressed air source 1 and the regulator 2 constitute an air pressure source 9. Three-way valve 3
Is used to select one of an air pressure supply position at which the pair of branch passages 12a and 12b communicate with the air pressure source 9 and an atmosphere release position at which the air is released from the air pressure source 9 to the atmosphere. Is in the open-to-atmosphere position.

The branch passages 12a and 12b are provided with normally open first on-off valves 4a and 4b, respectively, and have a work capsule 5a and a master capsule 5 having the same shape and the same volume at the downstream end.
b are connected respectively. The capsules 5a and 5b can be opened and closed so that the work W to be inspected and the master member M can be accommodated in a sealed state.
In addition, as the master member M, it is general to use a work that has been confirmed to have no leakage.

A differential pressure sensor 6 is connected between the branch passages 12a and 12b downstream of the first on-off valves 4a and 4b via introduction passages 15a and 15b.

A volume changing means 20a is provided in the work-side branch passage 12a downstream of the first on-off valve 4a. This volume changing means 20 a
a, a second opening / closing valve 22a provided in the middle of the auxiliary passage 21a, and a tank 23a having a predetermined volume connected to the other end (downstream end). I have. Similarly, in the master side branch passage 12b downstream of the first on-off valve 4b, an auxiliary passage 21b,
A volume changing means 20b including a second on-off valve 22b and a tank 23b is provided. In addition, a pair of tanks 23a,
Reference numeral 23b has the same volume, and is substantially the same as the master capsule 5b in a state in which the master member M is housed.

When the second on-off valves 22a, 22b are closed, the first on-off valves 4a, 4a in the branch passages 21a, 21b are closed.
4b (introduction passage 1 to differential pressure sensor 6)
The volumes 5a and 15b and the volumes of the auxiliary passages 21a and 21b to the second on-off valves 22a and 22b are equal to each other in design. Further, the volumes of the branch passages 21a and 21b when the second on-off valves 22a and 22b are opened (and the tank 23
a, 23b and auxiliary passage 21 to tanks 23a, 23b
a, 21b) are also equal in design.

Further, the air leak test device includes a control unit 50 for controlling the various valves 3, 4a, 4b, 22a, 22b described above, and a display unit 60.

Next, the operation (air leak test method) of the air leak test apparatus having the above configuration will be described. The control unit 50 executes the correction value acquisition mode before the test mode. When executing the correction value acquisition mode, the capsules 5a and 5b are closed empty. Then, the second on-off valves 22a and 22b are closed to shut off the auxiliary passages 21a and 21b, and the tanks 23a and 23b are connected to the branch passages 12a and 12b.
Isolate from Thus, the tanks 23a and 23b are maintained at the atmospheric pressure.

Next, by turning on the three-way valve 3 with the first on-off valves 4a and 4b open, the air pressure Pt of the air pressure source 9 is supplied to the capsule 5 via the branch passages 12a and 12b.
a, 5b. Next, by closing the first on-off valves 4a and 4b, the branch passages 12a and 12b and the capsules 5a and 5b downstream of the first on-off valves 4a and 4b are closed. Since the capsules 5a and 5b are empty, the differential pressure between the two closed systems detected by the differential pressure sensor 6 should be zero in this state.

Next, the second on-off valves 22a and 22b are opened.
When the second open / close valve 22a on the work side is opened, the pressure of the work side closing system escapes to the tank 23a. That is, in the work-side closing system, only the volume ΔVw of the auxiliary passage 21a downstream of the second on-off valve 22a and the volume of the tank 23a increases from the volume Vw in a state in which the second on-off valve 22a is closed. The pressure of the work side closing system decreases from the pressure Pt to the pressure Pw. Similarly, when the second on-off valve 22b on the master side is opened, the closing system on the master side moves the auxiliary passage 21b on the downstream side of the second on-off valve 22b and the tank from the volume Vm in a state where the second on-off valve 22b is closed. The volume increases by the volume ΔVm of the volume 23b, and accordingly, the pressure of the master-side closed system also decreases from the pressure Pt to the pressure Pm.

As described above, since the capsules 5a and 5b are empty, the differential pressure detected by the differential pressure sensor 6 should be zero even when the second on-off valves 22a and 22b are open.
However, the volumes Vw and Vm of the closed system when the second on-off valves 7a and 7b are closed are slightly different due to manufacturing errors and the like. Further, the above-mentioned volume increases ΔVw and ΔVm are slightly different. Therefore, the pressures Pw and Pm of the two closed systems are different, and the differential pressure detected by the differential pressure sensor 6 does not become zero.

The controller 50 stores the differential pressure ΔP = Pw−Pm detected by the differential pressure sensor 6 at this time as a correction value H. Although the detected differential pressure before the volume change should be essentially zero, the impact of the closing operation of the first on-off valves 4a and 4b causes deformation of the sealing material and the like, and therefore the detected differential pressure Δ
When P ′ occurs, the correction value H is expressed by the following equation:
It is determined in consideration of the detected differential pressure ΔP ′. H = ΔP−kΔP ′ Here, k = Vm / Vm + ΔVm. In the following description, kΔP ′ is called an unbalance pressure.

Finally, the first on-off valves 4a and 4b are opened and the three-way valve 3 is set to the open-to-atmosphere position, so that the air passage 10 downstream of the three-way valve 3 is entirely opened to the atmosphere.

Next, an air leak test mode normally performed by the control unit 50 will be described. Work capsule 5a
Is closed with the work to be inspected housed therein, and the master capsule 5b is closed with the master member M housed. The subsequent operation order of the valves 3, 4a, 4b, 22a, 22b is the same as in the correction value acquisition mode. More specifically, the first on-off valves 4a and 4b are opened, and the second on-off valves 22a and 22a are opened.
When the three-way valve 3 is turned on with the valve 22b closed, the air pressure source 9
After the test pressure is supplied to the branch passages 12a and 12b, the first on-off valves 4a and 4b are closed and the differential pressure detected by the differential pressure sensor 6 is monitored for a predetermined time. If the detected differential pressure does not change while remaining zero or the amount of change is equal to or less than the threshold, it is determined that there is no minute leakage. If the amount of change exceeds the threshold, it is determined that there is minute leakage.

Next, after opening the second on-off valves 22a and 22b to change the volumes of the branch passages 12a and 12b by the same amount, the differential pressure of the differential pressure sensor 6 is detected and compared with a threshold value. To determine if there is a major leak. In this case, when the volumes of the work-side closing system and the master-side closing system are equal to each other as designed and there is no leakage in the work W, the differential pressure should be zero. However, even if there is no leak in the work W, if the volumes of the work-side closing system and the master-side closing system are different due to a manufacturing error or the like, the detected differential pressure does not become zero. This detected differential pressure matches the correction value H obtained in the correction value acquisition mode. Therefore, the control unit 50 calculates a corrected differential pressure value depending only on the workpiece W by subtracting the correction value H from the detected differential pressure. If the above-described unbalance pressure exists, the correction differential pressure value is calculated by subtracting the correction value H and the unbalance pressure from the detected differential pressure.

The controller 50 determines that there is no large leak when the corrected differential pressure value is less than the threshold value, and determines that there is a large leak when the corrected differential pressure value exceeds the threshold value. When the control unit 50 determines that there is no minute leak or large leak, the control unit 50 controls the display unit 60 to display a non-defective product, and when there is a leak, displays a defective product.

In the above embodiment, the correction value acquisition mode may be performed a plurality of times, and the average value of the detected differential pressures may be used as the correction value H. Further, the correction value H calculated in the correction value acquisition mode may be updated in the process of repeating the test mode. For example, each time a non-defective product is determined in the test mode, the detected differential pressure at that time (or a value obtained by subtracting the unbalance pressure from the detected differential pressure) is stored. The correction value is updated with the correction value obtained in. In this case, the stored value in the test mode closer to the present time may be weighted to calculate an average value as the correction value, or the moving average value may be used as the correction value. As a result, a more accurate correction value can be obtained in response to a change over time of the apparatus. In this case, the corrected differential pressure value at the time of large leak determination is a predetermined value smaller than the threshold value (for example, a threshold value of 50).
%) If the correction value is calculated based on the average value of the detected differential pressures only for the non-defective products which are equal to or less than a good value, a more accurate correction value can be obtained.

Next, another embodiment of the present invention will be described. In these embodiments, configurations corresponding to the embodiments described earlier are denoted by the same reference numerals in the drawings, and description thereof will be omitted. The illustration of the control unit 50 and the display unit 60 is omitted.

In the second embodiment shown in FIG. 2, a sealed container 30 is connected to the downstream end of the master side branch passage 12b instead of the master capsule 5b in the first embodiment of FIG. 12b is closed on the downstream side of the first on-off valve 4b. The closed container 30 has an inner volume substantially equal to a value obtained by subtracting the outer volume of the work W from the inner volume of the work capsule 5a. As a result, the first
The volume of the master-side branch passage 12b downstream of the on-off valve 4b is equal to the work-side branch passage 12a downstream of the first on-off valve 4a.
Is substantially equal to a value obtained by subtracting the outer volume of the work W from the volume of the workpiece W. Here, “substantially equal” includes not only a case where the design is equal but also a case where there is a slight difference within an allowable range, assuming that a plurality of types of works having different outer volumes are tested.

In the second embodiment, in the correction value acquisition mode, the control unit 50 accommodates the work W without leakage in the work capsule 5a. In the leak test mode, the work W to be inspected is accommodated in the work capsule 5a. Valve control, correction value acquisition and leak detection methods are the first
Since the configuration is the same as that of the embodiment, the description for avoiding duplication is omitted. In this embodiment, there is no master capsule, and the labor for accommodating the master member in the master capsule can be omitted.

In the second embodiment as well, the correction value may be updated using the detected differential pressure data relating to the work judged to be non-defective in the test mode as in the first embodiment. Instead of the closed container 30, the pipe of the branch passage 12b may be extended to close the downstream end.

The third embodiment shown in FIG. 3 does not have the volume changing means 20a and 20b of the first and second embodiments. In the branch passages 12a and 12b, second on-off valves 7a and 7b are provided between the first on-off valves 4a and 4b and the capsules 5a and 5b, respectively. The branch passages 12a and 12b between the first on-off valves 4a and 4b and the second on-off valves 7a and 7b have:
The tanks 40a, 40b are provided via the auxiliary passages 16a, 16b.
Is connected.

In the third embodiment, in the correction value acquisition mode, the control unit 50 closes the work capsule 5a and the master capsule 5b while leaving them empty, opens the first open / close valves 4a, 4b, and opens the second open / close valves 7a, 7b. Is closed, the three-way valve 3 is driven to supply the air pressure of the air pressure source 9 to the work-side and master-side branch passages 12a and 12b, and then the first on-off valves 4a and 4b.
4b is closed, and then the second on-off valves 7a and 7b are opened. Then, the differential pressure detected by the differential pressure sensor 6 in this state is stored as a correction value.

In the air leak test mode, the control unit 50 accommodates the work W to be inspected for leakage in the work capsule 5a, and accommodates the master member M, which is the work having no leakage, in the master capsule 5b. The same control as in the correction value acquisition mode is performed. That is,
By driving the three-way valve 3 with the first on-off valves 4a, 4b opened and the second on-off valves 7a, 7b closed, the air pressure of the air pressure source 9 is reduced by the work side and the master side branch passages 12a,
Then, the first on-off valves 4a and 4b are closed, and then the second on-off valves 7a and 7b are opened. In this state, the differential pressure detected by the differential pressure sensor 6 is read. A corrected differential pressure value is calculated by subtracting the correction value from the detected differential pressure, and the presence or absence of leakage is determined based on the corrected differential pressure value. In this embodiment, a leak is detected without distinguishing between a minute leak and a large leak, as in the above-described related art.

In the fourth embodiment shown in FIG. 4, a closed container 30 is connected to the downstream end of the branch passage 12b instead of the master capsule 5b in the third embodiment shown in FIG. As in the second embodiment, the closed container 30 has an inner volume substantially equal to a value obtained by subtracting the outer volume of the work W from the inner volume of the work capsule 5a. As a result, the volume of the master-side branch passage 12b downstream of the first on-off valve 4b is
The value is substantially equal to a value obtained by subtracting the outer volume of the work W from the capacity of the work-side branch passage 12a on the downstream side of the first on-off valve 4a.

In the fourth embodiment, in the correction value acquisition mode, the control unit 50 accommodates the work W without leakage in the work capsule 5a. In the leak test mode, the work W to be inspected is accommodated in the work capsule 5a. The method of valve control, acquisition of the correction value, and detection of the leak are the same as those of the third embodiment, so that the description for avoiding duplication is omitted. In this embodiment, there is no master capsule,
The labor for accommodating the master member in the master capsule can be omitted.

In the third and fourth embodiments, the correction value may be updated in the same manner as in the first embodiment. The volume changing means of the first and second embodiments may reduce the volume and increase the pressure in the branch passage. The air pressure source may be a negative pressure. Also in this case, the air pressure source side is the upstream side.

[0042]

As described above, according to the first aspect of the present invention, in a device for sequentially detecting a small leak and a large leak, the capsule is emptied and the correction value acquisition mode is executed, so that the workability is improved. Is good. According to the second aspect, micro leak,
In a device that sequentially detects large leaks, the correction value acquisition mode is executed only by accommodating a work having no leak in the work capsule, so that workability is good. According to a third aspect,
In a device that simultaneously performs a small leak and a large leak, the capsule is emptied and the correction value acquisition mode is executed, so that workability is good. According to the fourth aspect, in a device that simultaneously performs a small leak and a large leak, the correction value acquisition mode is executed only by accommodating a work having no leak in the work capsule.
Good workability.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an air leak test device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of an air leak test device according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of an air leak test device according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram of an air leak test device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 4a, 4b First open / close valve (open / close valve) 5a Work capsule 5b Master capsule 6 Differential pressure sensor 7a, 7b Second open / close valve 9 Air pressure source 10 Air passage 11 Common passage 12a Work side branch passage 12b Master side branch passage 20a, 20b Volume changing means 40a, 40b Tank 50 Control unit W Workpiece M Master member

Claims (5)

[Claims] (1) a common passage connected to an air pressure source;
A work-side branch passage and a master-side branch passage branched from the common passage, (b) a pair of on-off valves provided respectively in the work-side and master-side branch passages, and (c) a work-side and master-side branch passage. A differential pressure sensor for detecting a differential pressure between a work capsule and a master capsule connected to the branch passage downstream of the on-off valve, respectively, and (d) a work-side and master branch passage downstream of the on-off valve; And (e) a pair of branch passages on the work side and the master side which are respectively provided on the downstream side of the on-off valve to change the volumes of the branch passages on the work side and the master side when the on-off valve is closed. (F) In the air leak test mode, a work to be inspected for leakage is accommodated in a work capsule, and a machine having an outer volume equal to that of the work and having no leak is provided. With the master member housed in the master capsule, the air pressure of the air pressure source is supplied to the branch passage on the work side and the master side, and then a pair of on-off valves are closed. Then, the presence or absence of minute leakage of the work is determined, and then the volume of the closed work-side and master-side branch passages is changed by an equivalent amount by operating a pair of volume changing means. And a control unit for determining whether there is a large leak of the workpiece based on the differential pressure detected by the differential pressure sensor. In the leak test apparatus, the control unit further executes a correction value acquisition mode to acquire the correction value. In the mode, with the master capsule and the work capsule closed in an empty state, the air pressure of the air pressure source is supplied to the branch passage on the work side and the master side, then the pair of on-off valves is closed, and then the pair of on-off valves is closed. Drive volume changing means In this manner, the volumes of the closed work-side and master-side branch passages are changed by the same amount, and a correction value is obtained and stored based on the differential pressure detected by the differential pressure sensor in this state. An air leak test apparatus characterized in that the presence or absence of a large leak is determined based on a value obtained by subtracting this correction value from a detected differential pressure at the time of detection. 2. A common passage connected to an air pressure source;
In the work-side branch passage and the master-side branch passage branched from the common passage, (b) a pair of on-off valves provided respectively in the work-side and master-side branch passages, and (c) the work-side branch passage. A work capsule connected to the downstream side of the on-off valve; (d) a differential pressure sensor for detecting a pressure difference between the work-side and master-side branch passages downstream of the on-off valve; (F) a pair of volume changing means provided in the branch passage on the master side downstream of the on-off valve, respectively, for changing the volumes of the branch passages on the work side and the master side when the on-off valve is closed; In the air leak test mode, while the work to be inspected for leakage is housed in the work capsule, the air pressure of the air pressure source is supplied to the branch passage on the work side and the master side, and then a pair of on-off valves are closed. In this state, based on the differential pressure detected by the differential pressure sensor, the presence / absence of minute leakage of the work is determined, and then the pair of volume changing means is operated. And a control unit for determining whether there is a large leak of the work based on the differential pressure detected by the differential pressure sensor in this state. The inner volume on the further downstream side is made substantially equal to a value obtained by subtracting the outer volume of the work from the inner volume on the downstream side of the on-off valve of the work-side branch passage, and the control unit further executes a correction value acquisition mode, In this correction value acquisition mode, in a state in which the work capsule contains a leak-free work and is closed, the air pressure of the air pressure source is supplied to the work-side and master-side branch passages. Close, then pair By changing the volume changing means, the volumes of the closed work-side branch passage and the master-side branch passage are changed by an equal amount, and a correction value is obtained and stored based on the differential pressure detected by the differential pressure sensor in this state. An air leak test apparatus for determining whether a large leak exists in the test mode based on a value obtained by subtracting the correction value from a differential pressure detected when the large leak is detected. 3. A common passage connected to an air pressure source;
(B) a pair of first on-off valves provided in the work-side branch passage and the master-side branch passage branched from the common passage;
In the branch passage on the work side and the master side, the first
A pair of second on-off valves respectively provided on the downstream side of the on-off valve, and (d) a work capsule and a master capsule respectively connected to the work-side and master-side branch passages on the downstream side of the second on-off valve. (E) a pair of tanks of the same capacity respectively provided between the first and second on-off valves in the work-side and master-side branch passages; and (f) the first on-off valve A differential pressure sensor for detecting the differential pressure between the branch passages on the work side and the master side on the downstream side of the work, and (g) in the air leak test mode, the work to be inspected for leakage is housed in a work capsule.
A master member having an outer volume equal to that of the work and having no leakage is accommodated in the master capsule, and a pair of first on-off valves are opened and a pair of second on-off valves are closed. And then close the pair of first on-off valves, and then open the pair of second on-off valves. In this state, it is determined whether or not the work leaks based on the differential pressure detected by the differential pressure sensor. The control unit further executes a correction value acquisition mode, in which the master capsule and the work capsule are closed while being empty, and a pair of first opening and closing is performed. With the valves opened and the pair of second on-off valves closed, the air pressure of the air pressure source is supplied to the work-side and master-side branch passages, then the pair of first on-off valves are closed, and then the pair of first on-off valves are closed. 2 Open the on-off valve and set the differential pressure An air leak test apparatus for obtaining and storing a correction value based on the differential pressure detected by the sensor, and determining the presence or absence of a leak based on a value obtained by subtracting the correction value from the differential pressure detected at the time of leak detection in the test mode. . 4. A common passage connected to an air pressure source,
(B) a pair of first on-off valves provided in the work-side branch passage and the master-side branch passage branched from the common passage;
In the branch passage on the work side and the master side, the first
A pair of second on-off valves provided respectively on the downstream side of the on-off valve, and (d) the second on-off valve in the work-side branch passage.
A work capsule connected downstream of the on-off valve;
In the branch passage on the work side and the master side, the first
(F) detecting a differential pressure between a pair of tanks having the same capacity provided between the on-off valve and the second on-off valve, and between the work-side and master-side branch passages downstream of the first on-off valve; In a differential pressure sensor and (g) air leak test mode, a work to be inspected for leakage is housed in a work capsule, a pair of first on-off valves are opened, and a pair of second on-off valves are closed. The air pressure is supplied to the branch passages on the work side and the master side, then the pair of first on-off valves are closed, and then the pair of second on-off valves are opened. In this state, based on the differential pressure detected by the differential pressure sensor. And a control unit for determining whether or not the work leaks. In the leak test apparatus, the internal volume of the master-side branch passage downstream of the first on-off valve is set downstream of the work-side branch passage of the on-off valve. Value obtained by subtracting the external volume of the work from the internal volume of the The control unit further executes a correction value acquisition mode. In the correction value acquisition mode, the work capsule contains and closes a work without leak, opens a pair of first opening / closing valves, and opens a pair of second valves. With the on-off valve closed, the air pressure of the air pressure source is supplied to the work-side and master-side branch passages, then the pair of first on-off valves are closed, and then the pair of second on-off valves are opened. A correction value is obtained and stored based on the differential pressure detected by the differential pressure sensor in the state, and the presence or absence of a leak is determined based on a value obtained by subtracting this correction value from the differential pressure detected when a leak is detected in the test mode. And air leak test equipment. 5. A test mode is executed using a correction value obtained in the correction value acquisition mode, and based on a plurality of data of a detected differential pressure value when it is determined that there is no work leakage in the test mode. The air leak test apparatus according to claim 1, wherein the correction value is updated.