JP2018179840A - Air leak tester and air leak test method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an outer pressure type air leak tester capable of executing an air leak test of a sealing article without requiring an excessive manufacturing cost and preparing a master.SOLUTION: An air leak tester 1 includes: a constant flow air supply source 290 including a first control valve 221a; a second control valve 223; a work storage chamber 30; a first air channel 23 which communicates the first control valve 221a and the second control valve 223; a second air channel 25 which connects the second control valve 223 and the work storage chamber 30; a pressure sensor 253 connected with the second control valve 223; and a differential pressure sensor 251 connected to the air channel 23 at one end, and connected to the second air channel 25 at the other end. The first control valve 221a connects or intercepts the constant flow air supply source 290 and the first air channel 23, and the second control valve 223 connects or intercepts the first air channel 23 and the second air channel 25.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an air leak tester and an air leak test method.

<External pressure type air leak tester>
For example, Patent Document 1 discloses a constant flow rate air leak tester as an external pressure air leak tester that applies pressure to the outside of a workpiece that is an inspection object. FIG. 1 shows a constant flow type air leak tester disclosed in FIG. 3 of Patent Document 1. As shown in FIG.

  The constant flow type air leak tester disclosed in FIG. 3 of Patent Document 1 includes a positive pressure source 16, a manifold unit 200, a determination control device 300, a work capsule 6W, and a master capsule 6M.

A manifold unit 200 formed of metal or resin includes control valves 50 and 60, critical nozzles 9W and 9M, a differential pressure detector 13, and a test pressure sensor 70.
The control valve 50, the differential pressure detector 13, and the control valve 60 are arranged in line in the longitudinal direction of the manifold block 210 on the upper surface of a plate-like rectangular parallelepiped manifold block 210 having a rectangular surface. A test pressure sensor 70 is attached to one long side of the manifold block 210.

  The pipe 11 from the positive pressure source 16 is connected to the work side pipe 21 W and the master side pipe 21 M in the manifold unit 200. A two-way control valve 5'W and a critical nozzle 9W are inserted in series in order toward the work capsule 6W in the work side pipe 21W. Also in the master side pipe 21M, a two-way control valve 5'M and a critical nozzle 9M are sequentially inserted in series toward the master capsule 6M. A differential pressure detector 13 is connected between the work side pipe 21W going from the critical nozzle 9W to the work capsule 6W and the master side pipe 21M going from the critical nozzle 9M to the master capsule 6M. Furthermore, one port of each of the two-way control valves 19'W and 19'M is connected to each of the pipes 21W and 21M, and the other port of each of the two-way control valves 19'W and 19'M is It is connected to a common open hole 26. A test pressure sensor 70 is connected to the master-side pipe 21M between the critical nozzle 9M and the master capsule 6M. The test pressure sensor 70 may be connected to the work side pipe 21W instead of the master side pipe 21M. The end of the work-side pipe 21W is connected to the work capsule 6W through the pipe 41W by a joint 21JW. The end of the master-side pipe 21M is connected to the master capsule 6M through the pipe 41M by a joint 21JM.

  The determination control device 300 observes the actual test pressure detected by the test pressure sensor 70 in accordance with the control program, and controls the operation of the two-way control valves 5 And, based on the differential pressure detected by the differential pressure detector 13 at a predetermined timing, the evaluation on the workpiece 8W is determined and displayed.

The operating principle of the constant flow rate air leak tester disclosed in FIG. 3 of Patent Document 1 is as follows.
First, the normally closed two-way control valves 5'W and 5'M are closed, and the normally open two-way control valves 19'W and 19'M are left open as they are. Let the system be in the same initial state (in this example atmospheric pressure).
In this state, the workpiece 8W is accommodated in the workpiece capsule 6W, and the master 8M having the same volume as the workpiece 8W and having no leak is accommodated in the master capsule 6M.

  Next, after setting the air pressure of the positive pressure source 16 to a desired pressure above the critical pressure and closing the two-way control valves 19'W and 19'M, the two-way control valve 5'W, The pressurized air of the positive pressure source 16 is supplied to the work capsule 6W and the master capsule 6M through the critical nozzles 9W and 9M while keeping the 5'M open for a predetermined time. As a result, air having the same constant flow rate is injected into the work-side air system and the master-side air system.

  The determination control device 300 observes the differential pressure detected by the differential pressure detector 13. If a hole is opened in the workpiece 8W, air leaks into the workpiece 8W, causing a difference between the total internal volume of the work-side gap and the total internal volume of the master-side gap, that is, the pressure of the workpiece-side air system is It becomes lower than the pressure on the master side air system. Therefore, when a differential pressure larger than the first reference value determined in advance by the differential pressure detector 13 is detected after a predetermined period after closing the two-way control valves 5'W and 5'M, the determination control device The test 300 is determined to be "Work 8W has a large leak", and the test is ended. If a differential pressure larger than the first reference value is not detected after the predetermined period, the determination control device 300 resets the detection output of the differential pressure detector 13 to 0 at that time, and the detection range is a sensitivity range. Switch to the high range and continue differential pressure detection. The determination control device 300 determines that “the workpiece 8W has no leak” if the detected differential pressure is equal to or less than the second reference value after the predetermined period has elapsed, and “the workpiece 8W if the detected differential pressure is larger than the second reference value”. Is judged to have a small leak, and the test is ended.

<Internal pressure type air leak tester>
The applicant of the present invention manufactures and sells an air leak tester having the functional configuration shown in FIG.

  The internal pressure air leak tester shown in FIG. 2 includes an air supply unit 201, a pressure reducing valve 210, a primary pressure sensor 213, a first control valve 221, a second control valve 223, and a third control valve 225. , First air flow passage 23, second air flow passage 25, third air flow passage 21, fourth air flow passage 27, fifth air flow passage 29, differential pressure detection A pressure sensor 253, a determination control device 300, a master connection portion 41, a work connection portion 43, and a silencer 40 are included.

  The first control valve 221 is a normally closed air operated valve having one intake port and two exhaust ports. One end of the third air flow passage 21 is connected to the intake port of the first control valve 221. An air supply unit 201 to which an air tank (not shown) is connected is attached to the other end of the third air flow passage 21. In the third air flow passage 21, a pressure reducing valve 210 for maintaining the stability of the primary side pressure and a primary side pressure sensor 213 for measuring the primary side pressure are connected in series between the air supply unit 201 and the first control valve 221. It is connected to the. Thus, the third air flow passage 21 communicates the air supply unit 201 with the first control valve 221. The third air channel 21 is, for example, a metal pipe.

  The second control valve 223 is a normally open air operated valve having two intake ports and one exhaust port. One end of the first air passage 23 is connected to one exhaust port of the first control valve 221, and the other end of the first air passage 23 is connected to one intake port of the second control valve 223. Connected The first air flow passage 23 has two pipelines in addition to the pipeline connecting the first control valve 221 and the second control valve 223. A master connection portion 41 to which the master 31 is connected is attached to an end of one of the conduits. The end of the other conduit is connected to one end of the differential pressure detector 251. Thus, the first air flow passage 23 communicates the first control valve 221, the second control valve 223, the differential pressure detector 251, and the master connection portion 41. The first air flow path 23 is, for example, a metal pipe.

  One end of the second air flow passage 25 is connected to the other intake port of the second control valve 223. At the other end of the second air flow path 25, a work connection portion 43 to which the work 33 is connected is attached. The second air flow path 25 has one pipe line in addition to the pipe line connecting the second control valve 223 and the work connection portion 43. The end of this conduit is connected to the other exhaust port of the first control valve 221. From this pipe line, one pipe line branches between a branch point at which this pipe line branches from the pipe line connecting the second control valve 223 and the work connection portion 43 and the first control valve 221 ing. The other end of the conduit is connected to the other end of the differential pressure detector 251. Thus, the second air flow path 25 communicates the first control valve 221, the second control valve 223, the differential pressure detector 251, and the work connection portion 43. The second air flow path 25 is, for example, a metal pipe.

  The third control valve 225 is a normally open air operated valve having one intake port and one exhaust port. One end of the fourth air passage 27 is connected to the exhaust port of the second control valve 223, and the other end of the fourth air passage 27 is connected to the intake port of the third control valve 225. . The fourth air flow passage 27 has one conduit in addition to the conduit connecting the second control valve 223 and the third control valve 225. The end of this conduit is connected to a pressure sensor 253. Thus, the fourth air flow path 27 communicates the second control valve 223, the third control valve 225, and the pressure sensor 253. The fourth air passage 27 is, for example, a metal pipe.

  One end of the fifth air flow passage 29 is connected to the exhaust port of the third control valve 225, and the other end of the fifth air flow passage 29 has a silencer 40 for reducing the exhaust noise from the air leak tester. It is attached.

According to the above-described configuration, when the first control valve 221 is in the open state, the first control valve 221 connects the air supply unit 201, the first air flow path 23, and the second air flow path 25. When the first control valve 221 is in the closed state, the first control valve 221 blocks the communication between the air supply unit 201 and the first air flow passage 23, and similarly, the air supply unit 201 and the second Communication with the air flow path 25 is shut off.
When the second control valve 223 is in the open state, the second control valve 223 connects the first air flow path 23, the second air flow path 25, and the fourth air flow path 27. When the second control valve 223 is in the closed state, the second control valve 223 blocks the communication between the first air flow passage 23 and the fourth air flow passage 27, and similarly, the second air flow The communication between the passage 25 and the fourth air flow passage 27 is cut off, and the communication between the first air flow passage 23 and the second air flow passage 25 is also cut off.

  The determination control device 300 observes the supply pressure detected by the primary side pressure sensor 213 and the test pressure detected by the pressure sensor 253 in accordance with the control program to determine the first, second and third control valves 221, 223, The operation of 225 is controlled, and the evaluation on the work 33 is determined and displayed based on the differential pressure detected by the differential pressure detector 251 at a predetermined timing.

The operation procedure of the internal pressure air leak tester shown in FIG. 2 is as follows.
First, the first control valve 221 is closed, and the second control valve 223 and the third control valve 225 are opened, so that the first air flow path 23 and the second air flow path 25; The fourth air flow path 27 and the fifth air flow path 29 are in the same initial state (in this example, atmospheric pressure). The third air flow passage 21 is set to a predetermined pressure equal to or higher than the critical pressure by the pressure reducing valve 210.
In this state, the master 31 is connected to the master connection portion 41, and the work 33 is connected to the work connection portion 43.

  Next, after the third control valve 225 is closed and the second control valve 223 is opened, the first control valve 221 is opened only for a predetermined time, and the air supply unit 201 is opened. The pressurized air of the connected air tank is supplied to the master 31 and the work 33 through the first air flow path 23, the second air flow path 25, and the third air flow path 21.

  Next, in a state where the third control valve 225 is closed, the first control valve 221 is closed while the second control valve 223 is in the open state, and the pressure fluctuation is reduced for a predetermined time. Wait for the decline. If the pressure sensor 253 detects a pressure drop during this time, the determination control device 300 determines that “the work 33 has a large leak”.

  Following this step, the second control valve 223 is closed while the first control valve 221 and the third control valve 225 are closed. The determination control device 300 observes the differential pressure detected by the differential pressure detector 251. If a hole is formed in the work 33, air leaks from the work 33, causing a difference between the pressure of the first air flow path 23 and the master 31, and the pressure of the second air flow path 25 and the work 33 That is, the pressure of the second air flow passage 25 becomes lower than the pressure of the first air flow passage 23. Therefore, when a differential pressure greater than the first reference value determined in advance by the differential pressure detector 251 is detected after a predetermined time has elapsed since the second control valve 223 was closed, the determination control device 300 It is determined that "33 has a large leak", and the test ends. If a differential pressure larger than the first reference value is not detected after the predetermined time has elapsed, the determination control device 300 resets the detection output of the differential pressure detector 251 to 0 at that time, and the sensitivity is detected in the detection range. Switch to the high range of and continue differential pressure detection. After a predetermined time has elapsed, the determination control device 300 determines that “the work 33 has no leak” if the detected differential pressure is less than or equal to the second reference value, and “work 33 if it is larger than the second reference value. Is judged to have a small leak, and the test is ended.

Patent No. 5758546 gazette

The external pressure air leak tester shown in FIG. 1 is suitable for the air leak test of a sealed product, but a master must be prepared. Further, since the internal pressure air leak tester shown in FIG. 2 does not measure the difference in void volume between the work side and the master side, the air leak test of the sealed product can not be performed.
Although it is not impossible to design an external pressure air leak tester that can perform air leak tests on sealed products without preparing a master, it is usually expensive to manufacture because of the new design, and this cost is transferred to the selling price. It will

  In view of such problems, the present invention uses an external pressure type air leak tester capable of performing an air leak test of a sealed product without preparing a master and without using an excessive manufacturing cost, and the external pressure type air leak tester. The purpose is to provide an air leak test method.

  The air leak tester according to the present invention communicates the constant flow rate air supply source including the first control valve, the second control valve, the work storage chamber, and the first control valve and the second control valve. Connected to the first air flow path or the second air flow path or the second control valve, and the second air flow path connecting the second control valve and the work storage chamber And a differential pressure sensor having one end connected to the first air flow path and the other end connected to the second air flow path. The first control valve connects or disconnects the constant flow air supply source and the first air flow path, and the second control valve connects the first air flow path and the second air flow path or Cut off.

  The air leak test method according to the present invention is an air leak test method using the air leak tester, wherein a) a constant flow rate air supply source to the first air flow path, the second air flow path, and the air in the work storage chamber. Is supplied for a predetermined time, and a first leak detection step of detecting leaks of the work stored in the work storage chamber by the pressure sensor; b) a first air flow path and a second following the first leak detection step And a second leak detection step of detecting leaks of the work stored in the work storage chamber by the differential pressure sensor in a state where the air flow path is shut off.

  According to the present invention, it is possible to carry out an air leak test of a sealed product without preparing a master without increasing the manufacturing cost.

The functional configuration example of the conventional external pressure type air leak tester. The functional configuration example of the conventional internal pressure type air leak tester. The functional configuration example of the embodiment of the present invention. The functional structural example of other embodiment of this invention. The processing flow of the air leak test in the embodiment of the present invention.

<Point of the present invention>
The main point of the present invention is to realize an external pressure type air leak tester capable of performing an air leak test of a sealed product without preparing a master by slightly changing the configuration of the existing internal pressure type air leak tester. The pressure sensor of the existing internal pressure type air leak tester is used to predict the timing of controlling the control valve, but in the present invention, this pressure sensor is used for leak detection.

Embodiment
Embodiments of the present invention will be described with reference to the drawings. FIG. 3 shows a functional configuration of an embodiment of the external pressure air leak tester of the present invention. The main difference between the external pressure air leak tester 1 shown in FIG. 3 and the conventional internal pressure air leak tester shown in FIG. 2 is that the external pressure air leak tester 1 is replaced with the first control valve 221 and the first control valve 221a is replaced. It is a point that contains. For this reason, the same reference numerals are assigned to components common to the external pressure air leak tester 1 shown in FIG. 3 and the conventional internal pressure air leak tester shown in FIG. The external pressure air leak tester 1 shown in FIG. 3 can be implemented by slightly changing the structure of the conventional internal pressure air leak tester shown in FIG.

  In the description of the embodiment, a dustproof filter, an auto leak calibrator (a device for converting a differential pressure change to a leak flow rate change), etc. are actually used, but are not essential in the description and understanding of the embodiment of the present invention. Components are omitted. Therefore, the term "connected" used in the description of the embodiment means that the components related to the term "connected" are directly connected (in other words, not via other components) When the component related to the term “connection” is connected indirectly (in other words, via another component) according to the actual need. It also implies to allow.

  The external pressure type air leak tester 1 shown in FIG. 3 includes a constant flow rate air supply source 290 that supplies air at a constant flow rate, a second control valve 223, a third control valve 225, and a first air flow path 23. , Second air flow path 25, fourth air flow path 27, fifth air flow path 29, differential pressure detector 251, pressure sensor 253, determination control device 300, work storage chamber 30 And a valve cap 43 and a silencer 40. The constant flow rate air supply source 290 includes an air supply unit 201, a pressure reducing valve 210, a primary side pressure sensor 213, a third air flow passage 21, and a first control valve 221a.

  The first control valve 221a is a normally closed air operated valve having one intake port and two exhaust ports. The valve structure of the first control valve 221 used in the conventional internal pressure air leak tester shown in FIG. 2 includes a normal orifice plate, but the valve structure of the first control valve 221a is replaced with the orifice plate and the sonic nozzle 27a , 27b (also referred to as critical nozzles, sonic nozzles, etc.). The critical nozzle (screw type pipe) disclosed by patent document 1 can be mentioned as an example of sonic nozzle 27a, 27b. The critical pressure ratio (the ratio of the secondary pressure to the primary pressure) of a threaded pipe of φ0.2 or φ0.3 is about 0.37, and under this condition, the exhaust port of the first control valve 221a is a constant flow air Discharge. In the example shown in FIG. 3, the sonic nozzle 27a is attached to one exhaust port of the first control valve 221a, and the sonic nozzle 27b is attached to the other exhaust port. Therefore, the constant flow rate air supply source 290 can supply air at a constant flow rate using the sonic nozzles 27a and 27b.

  One end of the third air flow passage 21 is connected to the intake port of the first control valve 221a. An air supply unit 201 to which an air tank (not shown) is connected is attached to the other end of the third air flow passage 21. In the third air flow passage 21, a pressure reducing valve 210 for maintaining the stability of the primary side pressure and a primary side pressure sensor 213 for measuring the primary side pressure are connected in series between the air supply unit 201 and the first control valve 221a. It is connected to the. Thus, the third air flow passage 21 communicates the air supply unit 201 with the first control valve 221a. The third air channel 21 is, for example, a metal pipe.

  The second control valve 223 is a normally open air operated valve having two intake ports and one exhaust port. One end of the first air flow path 23 is connected to one exhaust port of the first control valve 221 a, and the other end of the first air flow path 23 is connected to one intake port of the second control valve 223. Connected The first air flow passage 23 has two pipelines in addition to the pipeline connecting the first control valve 221 a and the second control valve 223. A valve cap 43 is attached to an end of one of the conduits, so that the end of the one of the conduits is sealed. The external pressure air leak tester 1 shown in FIG. 3 is a slight modification of the structure of the conventional internal pressure air leak tester shown in FIG. 2 (that is, the sonic nozzle 27a, 27b has a valve structure of the first control valve 221a instead of the orifice plate). In the external pressure type air leak tester 1, the master 31 is not necessary, and the end of the one conduit needs to be sealed by the valve cap 43. Therefore, since the one conduit is not essential, the external pressure air leak tester 1 may not include the one conduit as in the modification shown in FIG. 4. The end of the other conduit is connected to one end of the differential pressure detector 251. Thus, the first air flow path 23 communicates the first control valve 221 a, the second control valve 223, and the differential pressure detector 251. The first air flow path 23 is, for example, a metal pipe.

  One end of the second air flow passage 25 is connected to the other intake port of the second control valve 223. At the other end of the second air flow path 25, a work storage chamber 30 for storing a work 33 is attached. The second air flow passage 25 has one conduit in addition to the conduit connecting the second control valve 223 and the work storage chamber 30. The end of this conduit is connected to the other end of the differential pressure detector 251. From this pipe line, a pipe line branches between a branch point at which this pipe line branches from the pipe line connecting the second control valve 223 and the work storage chamber 30, and the differential pressure detector 251. There is. The end of this conduit is connected to the other exhaust port of the first control valve 221a. Thus, the second air flow path 25 communicates the first control valve 221 a, the second control valve 223, the differential pressure detector 251, and the work storage chamber 30. The second air flow path 25 is, for example, a metal pipe.

  The third control valve 225 is a normally open air operated valve having one intake port and one exhaust port. One end of the fourth air passage 27 is connected to the exhaust port of the second control valve 223, and the other end of the fourth air passage 27 is connected to the intake port of the third control valve 225. . The fourth air flow passage 27 has one conduit in addition to the conduit connecting the second control valve 223 and the third control valve 225. The end of this conduit is connected to a pressure sensor 253. Thus, the fourth air flow path 27 communicates the second control valve 223, the third control valve 225, and the pressure sensor 253. The fourth air passage 27 is, for example, a metal pipe. The pressure sensor 253 is not limited to the configuration in which the pressure sensor 253 is connected to the second control valve 223 via the fourth air channel 27, and the pressure sensor 253 is connected to the first air channel 23 or the second air channel 25. Configurations are also acceptable.

  One end of the fifth air flow passage 29 is connected to the exhaust port of the third control valve 225, and the other end of the fifth air flow passage 29 reduces the exhaust noise from the external pressure air leak tester 1 A silencer 40 is attached.

According to the above-described configuration, when the first control valve 221a is in the open state, the first control valve 221a brings the air supply unit 201, the first air flow passage 23, and the second air flow passage 25 into communication. When the first control valve 221a is in the closed state, the first control valve 221a blocks the communication between the air supply unit 201 and the first air flow passage 23, and similarly, the air supply unit 201 and the second Communication with the air flow path 25 is shut off.
When the second control valve 223 is in the open state, the second control valve 223 connects the first air flow path 23, the second air flow path 25, and the fourth air flow path 27. When the second control valve 223 is in the closed state, the second control valve 223 blocks the communication between the first air flow passage 23 and the fourth air flow passage 27, and similarly, the second air flow The communication between the passage 25 and the fourth air flow passage 27 is cut off, and the communication between the first air flow passage 23 and the second air flow passage 25 is also cut off.
When the third control valve 225 is in the open state, the third control valve 225 establishes communication between the fourth air passage 27 and the fifth air passage 29. When the third control valve 225 is in the closed state, the third control valve 225 blocks communication between the fourth air passage 27 and the fifth air passage 29.

  The determination control device 300 observes the supply pressure detected by the primary side pressure sensor 213 and the test pressure detected by the pressure sensor 253 in accordance with the control program, and determines the first, second and third control valves 221a, 223, The operation of 225 is controlled, and the evaluation on the work 33 is determined based on the differential pressure detected by the differential pressure detector 13 at a predetermined timing, and the determination result is displayed.

The procedure of the leak test by the external pressure air leak tester 1 shown in FIG. 3 is as follows.
First, the first control valve 221a is closed, and the second control valve 223 and the third control valve 225 are opened, so that the first air flow path 23 and the second air flow path 25; The fourth air flow path 27 and the fifth air flow path 29 are set to the same initial state (in this example, the atmospheric pressure) (step S1). The third air flow passage 21 is set to a predetermined pressure equal to or higher than the critical pressure by the pressure reducing valve 210.
In this state, the work 33 of the sealed product is airtightly stored in the work storage chamber 30.

  Next, after the third control valve 225 is closed with the second control valve 223 kept open, the first control valve 221a is kept open for a predetermined time ΔT to supply air. The pressurized air of the air tank connected to the unit 201 is supplied to the first air passage 23, the second air passage 25, the fourth air passage 27, and the work storage chamber 30, and the work is accommodated. The leak of the work 33 contained in the chamber 30 is detected by the pressure sensor 253 (step S2).

In this step S2, the presence or absence of a leak is determined by the detection of a pressure rise in a predetermined time ΔT. Since air is supplied at a constant flow rate from the exhaust port of the first control valve 221a, the change according to time of the secondary side pressure measured by the pressure sensor 253 has linearity. When the work 33 is not airtightly manufactured, the pressure measurement value by the pressure sensor 253 at the time when a predetermined time ΔT has elapsed from the start of air supply is the pressure measurement value when the work 33 is airtightly manufactured. In comparison, it becomes a low value. However, when the workpiece 33 is manufactured airtight, the pressure measurement value by the pressure sensor 253 at the time when a predetermined time ΔT has elapsed from the start of the air supply is obtained in advance by the external pressure air leak tester 1 I assume. By previously setting the first reference value based on the pressure measurement value when the work 33 is airtightly manufactured, the determination control device 300 detects the pressure sensor 253 when a predetermined time ΔT has elapsed from the start of air supply. If the measured pressure value is lower than the first reference value or lower than the first reference value, it is determined that "the work 33 has a large leak". The first reference value is set as a value obtained by subtracting a predetermined value in which an error or a pressure fluctuation is expected from a pressure measurement value when the work 33 is manufactured airtight.
According to this embodiment, when the primary pressure is a gauge pressure of 300 kPa, it is possible to generate a secondary pressure which changes linearly up to 50 kPa, and when the primary pressure is a gauge pressure of 500 kPa, it linearly changes up to 100 kPa. It is preferable that the side pressure can be generated, and the air supply time ΔT is 1 second or more and 5 seconds or less.

  In addition, according to such a configuration, the secondary side pressure changes linearly by supplying air at a constant flow rate from the exhaust port of the first control valve 221a, so there is a minute opening in the work 33. Even if this is the case, it is possible to detect the presence or absence of the leak of the work 33 without sealing the opening with the instantaneous air supply pressure.

  Next, with the third control valve 225 closed, with the second control valve 223 open, the first control valve 221 a is closed, and the pressure fluctuation is waited for a predetermined time period (see FIG. Step S3). Even during this standby time, the judgment control device 300 can observe the fluctuation of the pressure measurement value by the pressure sensor 253, and can judge that “the work 33 has a leak” if a drop in the pressure measurement value is observed. is there. That is, in this step S3, the presence or absence of a leak is determined by the detection of the pressure drop.

Following step S3, the second control valve 223 is closed while the first control valve 221a and the third control valve 225 are closed. In the state where the first air flow passage 23 and the second air flow passage 25 are shut off, the determination control device 300 detects a leak of the work 33 stored in the work storage chamber 30 by the differential pressure detector 251. (Step S4). In step S4, the presence or absence of a leak is determined by detecting a change in differential pressure.
If a hole is formed in the work 33, air flows into the work 33, and the pressure in the second air flow path 25 becomes lower than the pressure in the first air flow path 23. Therefore, if a differential pressure greater than a second reference value predetermined by the differential pressure detector 251 is detected after a predetermined time has elapsed since the second control valve 223 was closed, the determination control device 300 It is determined that “33 has a leak,” and the test is ended. If a differential pressure larger than a predetermined second reference value is not detected after a predetermined time has elapsed, the determination control device 300 resets the detection output of the differential pressure detector 251 to 0 at that time, and performs detection. Switch the range to a range with high sensitivity and continue differential pressure detection. If the detected differential pressure is equal to or less than a predetermined third reference value after a predetermined time has elapsed, the determination control device 300 determines that "the workpiece 33 has no leak", and if it is larger than the third reference value For example, it is determined that "the work 33 has a leak", and the test is ended.

<Modification>
The functional configuration of another embodiment of the external pressure air leak tester of the present invention is shown in FIG. Unlike the embodiment shown in FIG. 3, the external pressure air leak tester of the embodiment shown in FIG. 4 includes a first control valve 221b instead of the first control valve 221a. The first control valve 221 b is a normally closed air operated valve having one intake port and one exhaust port. The valve structure of the first control valve 221b includes a sonic nozzle 27a instead of the conventional orifice plate. In the example shown in FIG. 4, the sonic nozzle 27a is attached to the exhaust port of the first control valve 221b. Therefore, the constant flow rate air supply source 290 can supply air at a constant flow rate using the sonic nozzle 27a.

  In the configuration shown in FIG. 4, one end of the first air flow path 23 is connected to the exhaust port of the first control valve 221 b. Further, in the configuration shown in FIG. 4, unlike the configuration shown in FIG. 3, the pipe branch from the pipe connecting the second control valve 223 and the work storage chamber 30 is a branch directed to the first control valve 221 b There is no pipeline.

Addendum
In the description and the claims, the term "comprise" and its variations are used as non-exclusive representations. For example, the sentence "X contains A and B" does not deny that X contains anything other than A and B. However, this is not the case when the term or its inflection is combined with a negative word. For example, the sentence "X does not contain A and B" admits that X may contain more than A and B.

  The term ".smallcircle." In the above description is a term used to clearly describe the configuration of the embodiment. The present invention is not limited by the term itself, that is, by the order of components itself. Nor is the use of the term intended for such limitation.

  While the embodiments of the present invention have been described above, it will be apparent to those skilled in the art that the present invention is not limited to the embodiments described herein. The present invention can be embodied as modifications and alterations without departing from the spirit and scope of the present invention defined by the description of the claims. The description of the present specification is for the purpose of illustration and does not have any limiting meaning with respect to the present invention unless otherwise specified.

Claims (4)

A constant flow air source including a first control valve;
A second control valve,
A work storage room,
A first air passage communicating between the first control valve and the second control valve;
A second air flow passage communicating the second control valve with the work storage chamber;
A pressure sensor connected to the first air flow path or the second air flow path or the second control valve;
A differential pressure sensor connected at one end to the first air flow path and at the other end to the second air flow path;
The first control valve communicates or shuts off the constant flow air supply source and the first air flow path,
An air leak tester, wherein the second control valve connects or shuts off the first air flow path and the second air flow path. In the air leak tester according to claim 1,
An air leak tester characterized in that the constant flow rate air supply source supplies air at a constant flow rate using a sonic nozzle. In the air leak tester according to claim 2,
An air leak tester characterized in that the sonic nozzle is incorporated in the valve structure of the first control valve. A constant flow air source including a first control valve;
A second control valve,
A work storage room,
A first air passage communicating between the first control valve and the second control valve;
A second air flow passage communicating the second control valve with the work storage chamber;
A pressure sensor connected to the first air flow path or the second air flow path or the second control valve;
A differential pressure sensor connected at one end to the first air flow path and at the other end to the second air flow path;
The first control valve communicates or shuts off the constant flow air supply source and the first air flow path,
An air leak test method using an air leak tester, wherein the second control valve connects or shuts off the first air flow path and the second air flow path.
a) Air is supplied from the constant flow air supply source to the first air flow path, the second air flow path, and the work storage chamber for a predetermined time, and the leak of the work stored in the work storage chamber is A first leak detection step detected by the pressure sensor;
b) Following the first leak detection step, with the first air flow path and the second air flow path blocked, the leak of the work stored in the work storage chamber is reduced to the pressure difference. A second leak detection step detected by a sensor;
Have an air leak test method.

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