JP2002310842A - Air leak test device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air leak test device capable of detecting the leak of a workpiece with high sensitivity. SOLUTION: A common passage 11 connected to a test pressure source 15 is branched into a passage 12 for connecting a master component housing space 52, passages 131 -13N for connecting workpiece housing spaces 531 -53N, and a back-pressure feeding passage 14. Closing valves 32, 331 -33N and 34 are installed in the passages, and by closing the closing valves, a master-side closed system A, workpiece-side closed systems B1 -BN and a back-pressure-side closed system C are formed. The differential pressure between the closed system C and the closed system A is detected by a differential pressure sensor 62, and the differential pressures between the closed system C and the closed systems B1 -BN are detected by workpiece-side differential pressure sensors 631 -63N. The deviations between the sensed differential pressure of the master-side differential pressure sensor and the sensed differential pressures of the workpiece-side differential pressure sensors are calculated by differential amplifiers 701 -70N, and the deviations are outputted as the differential pressures between the master-side closed system and the workpiece-side closed systems.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure type air leak test apparatus for accurately detecting work leakage.

[0002]

2. Description of the Related Art In a differential pressure type air leak test apparatus for detecting leakage of a workpiece with high accuracy, a common passage connected to a test pressure source, a pair of branch passages branched from the common passage,
That is, it has a work side passage and a master side passage. At the downstream end of the work-side passage, a housing container (work accommodation space) for housing a work to be inspected for leakage is connected, and at the downstream end of the master-side passage, a work without leakage is used as a master part. A storage container (master component storage space) for storing is connected. The common passage is provided with a three-way valve, and the work-side and master-side passages are provided with on-off valves, respectively. A differential pressure sensor is connected downstream of the on-off valve between the work side and the master side passages.

The controller supplies a test pressure to the work accommodating space and the master component accommodating space by driving the three-way valve with the pair of on / off valves open, and then closes the on / off valve. The differential pressure sensor detects the pressure difference between the master side closing system and the work side closing system downstream of the on-off valve,
The presence or absence of work leakage is determined based on the detected differential pressure. When there is a small leak in the work, the pressure in the work-side closing system gradually decreases, so that a differential pressure is generated between the two closing systems.

[0004]

In the differential pressure type air leak test apparatus described above, it is required that the volumes of the master side closing system and the work side closing system be as small as possible.
This is to increase the pressure fluctuation with respect to minute leakage of the work and improve the sensitivity. Further, it is preferable that the volumes of the master side closing system and the work side closing system have no great difference. This is to prevent a pressure difference between the closed systems due to temperature fluctuation from occurring.

However, in the conventional apparatus, it is necessary that one pressure receiving surface of the differential pressure sensor receives the pressure of the master side closing system and the other pressure receiving surface receives the pressure of the work side closing system. It is often difficult to shorten both of the passages of the closed system leading to the two pressure receiving surfaces of the sensor, and the demand for volume reduction of both closed systems has not been sufficiently satisfied. In particular, when the differential pressure sensor is attached to an asymmetric member such as a bottomed cylindrical casing, it has been difficult to sufficiently satisfy the above requirements. Also, in the case of a device in which the master-side closing system is shared and a plurality of works are simultaneously inspected for leakage using a plurality of work-side closing systems, the above request cannot be met.

[0006]

According to a first aspect of the present invention, there is provided:
(A) a common passage whose upstream side is connected to the test pressure source, a master side passage branched from the downstream side of the common passage and connected to a master part or a master component accommodating space, and a work branched off from the downstream side of the common passage. Alternatively, an air passage having a work-side passage to which the work accommodating space is connected, (b) first on-off valves provided in the master-side passage and the work-side passage, and (c) the first on-off valve is closed. In this state, a master-side closing system including a passage portion of the master-side passage downstream of the first opening / closing valve and a work-side closing system of the work-side passage including a passage portion downstream of the first opening / closing valve. And a differential pressure detecting means for detecting a differential pressure between the common path and the air path, further comprising a back pressure supply path branched from a downstream side of the common path. Is the above back pressure A master side differential pressure sensor for detecting a difference between the back pressure from the supply passage and the pressure of the master side closing system, and a work side for detecting a difference between the back pressure from the back pressure supply passage and the pressure of the work side closing system. The differential pressure sensor calculates a deviation between the master-side differential pressure detected by the master-side differential pressure sensor and the work-side differential pressure detected by the work-side differential pressure sensor, and calculates the difference between the master-side closed system and the work-side differential pressure. An air leak test device comprising: a differential pressure calculating means for obtaining a differential pressure of a closed system.

According to a second aspect of the present invention, in the air leak test apparatus according to the first aspect, the volume of the master side closing system is substantially equal to the volume of the work side closing system.

According to a third aspect of the present invention, in the air leak test apparatus of the second aspect, a plurality of work-side passages are branched from a downstream side of the common passage, and these work-side passages are divided into:
Each of the workpieces or the workpiece accommodating space is connected and the first on-off valve is provided. Each of the workpiece-side passages includes a plurality of workpiece-side closing systems including a passage portion downstream of the first on-off valve. Each work-side differential pressure sensor detects a differential pressure between the pressure of the corresponding work-side closing system and the back pressure of the common back-pressure supply passage. It is characterized in that deviations between the detected differential pressure of the work side differential pressure sensor and the differential pressure detected by the common master side differential pressure sensor are calculated.

According to a fourth aspect of the present invention, in the air leak test apparatus according to the second or third aspect, a second on-off valve is connected to the master side passage downstream of the first on-off valve. A master-side tank is connected downstream of the second on-off valve, and one pressure-receiving surface of the master-side differential pressure sensor faces between the first and second on-off valves. A second on-off valve is connected downstream of the valve, a work-side tank is connected downstream of the second on-off valve, and one pressure-receiving surface of the work-side differential pressure sensor is interposed between the first and second on-off valves. In the back pressure supply passage, first and second on-off valves are sequentially connected from the upstream side to the downstream side, and a back-pressure side tank is connected downstream of the second on-off valve. Between the master side differential pressure sensor and the workpiece side differential pressure The master-side tank and the work-side tank have substantially the same volume, and the volume ratio of the back-pressure tank to the master-side and work-side tanks is determined by closing the first and second on-off valves. In this state, the ratio of the volume of the closed system of the back pressure supply passage to the volume of the closed system of the master side and the work side is substantially equal to the ratio of the volume of the closed system, and further includes control determining means. The test pressure application mode in which the test pressure is applied by opening the first on / off valve of the first, and the master side closing system, the work side closing system and the closing system of the back pressure supply passage by closing all the first on / off valves. A first leak detection mode to be formed and a second leak detection mode in which the volumes of the respective closed systems are increased by the tank volume by opening all the second on-off valves are then executed.
The presence / absence of minute leakage of the work is determined based on the differential pressure information from the differential pressure calculation means in the leak detection mode, and the large leakage of the work is determined based on the differential pressure information from the differential pressure calculation means in the second leak detection mode. It is characterized by determining the presence or absence.

According to a fifth aspect of the present invention, there is provided an air leak test apparatus according to claims 2 to 4, wherein the first block and the first block are provided.
A second block that comes into contact with and separates from the block;
In the block, a master component accommodating space and a work accommodating space are formed, and through holes continuous with the accommodating spaces are formed.
A part of a passage portion of the work-side passage downstream of the first on-off valve is formed, and a sensor assembly is mounted on the second block corresponding to the accommodation space, and a differential pressure built in the sensor assembly is provided. One pressure receiving surface of the sensor faces the housing space through a through hole formed in the second block, and the back pressure supply passage is branched into a plurality,
The other pressure-receiving surface of the master-side and work-side differential pressure sensors faces these branch passages.

According to a sixth aspect of the present invention, there is provided the air leak test apparatus according to the second to fourth aspects, wherein the master part accommodating space,
A plurality of identically shaped first blocks each having a work accommodating space formed therein; and a plurality of identically shaped second blocks respectively approaching and separating from the first blocks. Through holes are respectively formed in the spaces, and these through holes respectively constitute a part of a passage portion of the master side passage and the work side passage downstream of the first on-off valve. Sensor assemblies are installed corresponding to each space,
One of the pressure receiving surfaces of the differential pressure sensor incorporated in the sensor assembly faces the housing space through a through hole formed in the second block, and the back pressure supply passage is branched into a plurality of branches. The other pressure receiving surface of the differential pressure sensor on the master side or the workpiece side faces the other. A seventh aspect of the present invention is the air leak test apparatus according to the first to sixth aspects, wherein the master-side differential pressure sensor and the work-side differential pressure sensor are attached to the bottom of a bottomed cylindrical casing having the same shape. , The one pressure-receiving surface is connected to the master-side closing system through a through hole formed in the bottom.
It faces the work-side closing system, and the other pressure-receiving surface faces the back-pressure-side closing system via the space of the casing.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an air leak test apparatus according to a first embodiment of the present invention will be described with reference to FIGS. First, an outline of the air leak test device will be described with reference to the circuit diagram of FIG. The air leak test device has an air passage 10. The air passage 10
Common passage 11 and a single (common) branch from the downstream side
Master side passage 12 and a plurality (N) of work side passages 13
_{1 to} 13 _N and a single (common) back pressure supply passage 14. On the upstream side of the common passage 11, a compressed air pressure source 15a
And a test pressure source 15 comprising a regulator 15b.

An electromagnetic three-way valve 16 is provided in the middle of the common passage 1x. The three-way valve 16 includes a test pressure supply position at which the branch passages 12, 13 ₁ to 13 _N , 14 communicate with the test pressure source 15, and the branch passages 12, 13 _{1 to} 13 _N.
The 13 N, ₁₄ shut off from the test pressure source 15 is intended to select one of the atmosphere opening position for opening to the atmosphere,
In the off state, it is in the open-to-atmosphere position.

[0014] The branch passage 12, 13 ₁ to 13 _N, in order toward the downstream side, respectively from the upstream side 14, the first on-off valve 22, 23 ₁ ~ 23 _N, 24 of the pneumatic-driven normally open, normally closed pneumatic-driven second closing valve 32,33 ₁ ~33 _N, 3
4, is provided with the tank 42,43 ₁ ~43 _N, 44.

The on-off valve 2 is provided in the master side passage 12.
The master component accommodating space 52 is connected between the two and 32, and one pressure receiving surface of the master-side differential pressure sensor 62 faces. As will be described later, when the on-off valve 22 is closed, a master-side closing system A including a passage portion of the master-side passage 12 downstream of the on-off valve 22 and the accommodation space 52 is formed. Above the workpiece-side passage ₁₃ 1 to 13 _N, off valve 23
In between ₁ ~ 23 _N off valve ₃₃ 1 ~ 33 _N, along with a work accommodating space ₅₃ 1 to 53 _N are connected respectively, facing one pressure receiving surface of the workpiece-side pressure sensor ₆₃ 1 to 63 _N, respectively In. When the opening and closing valve ₂₃ 1 ~ 23 _N are closed-off valve ₃ 1 of the work-side passage ₁₃ 1 to 13 _N ~
Passage portion downstream of 33 _N and accommodation spaces 53 _{1 to} 53 _N
Work side closed system _B 1 .about.B _N is formed including and. The differential pressure sensor 62 and 63 ₁ to 63 _N, for example preferable to use what is referred to as gauge pressure sensor or a semiconductor sensor. These sensors have a diaphragm made of silicon and can detect a differential pressure with high accuracy with little distortion.

The back pressure supply passage 14 is provided with the on-off valve 2
Branch passage portions 19a, 19b ₁ branching from between 2, 32
It contains ~19b _N. The downstream end of the branch passage portion 19a faces the other pressure receiving surface of the master-side differential pressure sensor 62. The downstream end of the branch passage portions _19b 1 through 19b _N faces the other of the pressure receiving surface of the workpiece-side pressure sensor ₆₃ 1 to 63 _N, and supplies a common back pressure.

Further, the apparatus according to the present embodiment has a plurality (N pieces).
, Differential amplifiers 70 ₁ to 70 _N (differential pressure calculating means), a controller 75 (control determining means), and a display section 76 for displaying a leak determination result. Differential amplifier 70 _{1 to} 7
0 _N , one of the input terminals is connected to the master-side differential pressure sensor 62.
, And the other input terminal receives the differential pressure detection signals from the work side differential pressure sensors 63 _{1 to} 63 _N , respectively. These differential amplifiers 70 ₁ to 70 _N
Is sent to the controller 75. This output signal will be described later in detail. Controller 75
It is intended to include a microcomputer, a memory, input-output interface, driving means such as a (both not shown), the three-way valve 16, closing valves 22, 23 ₁ ~ 23 _N, 2
4, 32, 33 _{1 to} 33 _N , 34, and a function of controlling the display unit 76 and performing leak determination. The differential pressure sensors 62, 63 _{1 to} 63 _N and the differential amplifiers 70 ₁ to 70 _N
N constitutes the differential pressure detecting means of the present invention. The microcomputer in the controller 75 is a differential amplifier 70
It may also serve as a function of _{1 ~70 N.}

Next, a specific structure of the air leak test apparatus constituting the above circuit will be described with reference to FIGS. The device includes a lower block 80 (first block) fixed at a predetermined position and an upper block 85 (second block). The upper block 85 is moved up and down by a lifting mechanism (not shown) between a position where the lower block 80 is in airtight contact and a position away from the lower block 80. On the upper surface of the lower block 80, the master component housing space 52 and the workpiece receiving space 53 ₁ to 53 _N as described above is formed. Further, in the lower block 80, the accommodation space 5 is provided.
2,53 _{1 to} 53 _N , through holes 82, 83 _{1 to} 83 _N
N is formed. The accommodation space 52 and the through hole 82 constitute a part of a master-side closed system A described later, and the accommodation space 53 ₁
To 53 _N and ₈₃ 1 to 83 _N with a work-side closed system _B 1 .about.B
_N. First on-off valves 22, 23
₁ ~ 23 _N and the second on-off valve 32, 33 ₁ ~ 33 _N are attached to the lower block 80 through a joint.

[0019] upper surface of the upper block 85, the sensor assembly 86 to the position corresponding to the receiving space 52 and 53 ₁ to 53 _N is mounted. The sensor assembly 86 includes a bottomed cylindrical casing 87 and the above-described differential pressure sensor 62 attached to the bottom of the casing 87.
And 63 ₁ to 63 _N, and a joint 88 attached to the cylindrical portion of the casing 87. The bottom of the casing 87 is fixed to the upper block 86.

The lower pressure receiving surface (one pressure receiving surface) of the differential pressure sensors 62, 63 _{1 to} 63 _N is formed with through holes 85a, 8 formed in the bottom of the upper block 85 and the casing 87.
The storage spaces 52, 53 _{1 to} 53 _N are faced via 7a. The upper pressure receiving surface (the other pressure receiving surface) of the differential pressure sensors 62, 63 _{1 to} 63 _N is connected to a space 89 of the casing 87.
Through each branch passage portion 19a of the back pressure supply passage 14,
19b _{1 to} 19b _N are facing.

As described above, the master side differential pressure sensor 62
Also work side sensor 63₁~ 63_NAlso the bottom of casing 87
Mounted on the unit. Further, the differential pressure sensors 62 and 63₁~
63 _NThe pressure receiving surface on the lower side is a very short passage (through hole 85).
a, 87a) through the storage spaces 52, 53
₁~ 53_NAnd through holes 82 and 83₁~ 83
_NOn-off valves 22, 23 including₁~ 23_NPassage on the downstream side of
I'm on the minute. As a result, the master side closed system A
Work side closing system B₁~ B_NThe volume of
Can be very small. The differential pressure sensor 6
2,63₁~ 63 _NThe pressure receiving surface on the upper side of
Branch portions 19a and 19b of back pressure supply passage 14₁~ 19b
₂, The back pressure side closed system C has a relatively large volume
However, the volume of the back pressure side closed system C is set to a differential pressure as described later.
Do not affect the detection sensitivity and, consequently, the accuracy of leak determination.
No.

With the air leak test apparatus having the above configuration,
When performing a leak test on a plurality of works W _{1 to} W _N , which are products having the same specification, first, the master part M and the works W ₁ to W _N are processed.
W _N and the accommodation space 52 formed in the lower block 80,
53 housed respectively in ₁ to 53 _N, in this state, the controller 75 lowers the upper block 85 to hermetically the housing space 52 and 53 ₁ to 53 _N and. The master component M is preferably the same component as the workpieces W _{1 to} W _N , for example, and it is preferable that the master component M has been confirmed not to leak.

Next, by turning the three-way valve 16, and supplies the test pressure in the branch passage 12,13 ₁ ~13 _N, 14 (test pressure application mode). Next, the on-off valves 22, 23 ₁ to 23 _N ,
24 is closed (first leak detection mode). As a result, the downstream side of the on-off valve 22 of the master side passage 12 is closed, and a common master side closing system A including the master component housing space 52 is formed. Further, the workpiece-side passage ₁₃ 1 to 13 _N on-off valve 1
31 _{1 to} 13 _N , the downstream side is closed, and the work accommodation space 53 is closed.
_1-53 plurality of working side closed system containing _N, respectively _B 1 ~
To form a B _N. Further, the on-off valve 2 of the back pressure supply passage 14
4, the downstream side is closed, and the branch passage portions 19a, 19b ₁
19b _N and space 89 of all sensor assemblies 86
To form a common back pressure side closed system C.

As described above, the on-off valves 22, 23₁~ 2
3_N, 24 are closed immediately after closing systems A and B₁~ B_N, C
Are all test pressures. That is, the master
Master side applied to one pressure receiving surface of the side differential pressure sensor 62
The pressure of the closing system A and the back pressure side closing applied to the other pressure receiving surface
The pressure in the chain system C is equal, and therefore the master side differential pressure sensor 6
The detected differential pressure of No. 2 becomes zero. Similarly, the work side differential pressure sensor
Sa 63₁~ 63_NWork side applied to one pressure receiving surface of
Closed system B₁~ B_NPressure and the other pressure receiving surface
The pressure of the back pressure side closing system C is equal, and therefore the work side differential pressure
Sensor 63₁~ 63 _NAlso becomes zero.

The controller 75 determines, for example, that a predetermined time has elapsed.
When the differential amplifier 70₁~ 70 _NReceiving the output signal of
To make a small leak determination. Differential amplifier 70₁~ 70_NIs
The difference from the master side differential pressure sensor 62 is
Receive the pressure detection signal, and use the other input terminal to
Sensor 63₁~ 63_NReceived the differential pressure detection signal from
A signal corresponding to the deviation is output. Master side differential pressure
The differential pressure detected by the sensor 62 is different between the master side closing system A and the back pressure side closing.
The differential pressure of the chain system B,₁~
63_NDifferential pressure of the work side closed system B₁~ B_NAnd back pressure
Differential pressure of the side closing system C and a common back pressure side closing system
The pressure of C is equal to the master-side differential pressure sensor 62 and the workpiece-side differential pressure sensor.
Sa 63₁~ 63_NOf the other pressure receiving surface
The differential amplifier 70₁~ 70_NDeviation output from
According to the information, the pressure of the back pressure side closed system C was canceled.
This deviation is caused by the master side closing system A and the work side closing system B
₁~ B_NWill be indicated.

First, a description will be given of a case where the works W _{1 to} W _N have no flaws and there is no change in the environmental temperature surrounding the apparatus. In this case, since the pressurized air does not enter the works W _{1 to} W _N and all the closed systems A, B _{1 to} B _N , C are maintained at the test pressure, all the differential pressure sensors 62, 63 ₁
Detection differential pressure to 63 _N are zero, therefore, the detection differential pressure of the differential amplifier ₇₀ 1 to 70 _N is also zero. Controller 75, a detection differential pressure of the differential amplifiers ₇₀ 1 to 70 _N is compared with a threshold value, determines that the minute leakage without.

Next, a case will be described in which the workpieces W _{1 to} W _N have no flaws and there is a change in the environmental temperature surrounding the apparatus. In this case, the pressure changes in the closed systems A, B _{1 to} B _N , C although the pressure is very small. The extent of pressure change, the master-side closed system A and the work side closed system B ₁ in .about.B _N equal. These closed system _A, the volume and the environment of the B 1 .about.B _N because equal. However, the degree of change in the pressure of the closed system A, B ₁ ~B _N back pressure side closed system C to be compared with the pressure of different. This is because the volume and environment of the back pressure side closed system C are different. Therefore, the differential pressure sensors 62, 63 _{1 to} 63 _N detect a non-zero differential pressure. However, this differential pressure sensor 62,
Since the detected differential pressures of 63 _{1 to} 63 _N are equal to each other, the detected differential pressures of the differential amplifiers 70 ₁ to 70 _N become zero, and the temperature fluctuation can be canceled. As a result, the controller 75 determines that there is no minute leakage without being affected by the temperature fluctuation.

If any of the works W _{1 to} W _N has a minute flaw, pressurized air enters (leaks) inside the work, so that the flaw is included in the work side closing systems B _{1 to} B _N. The pressure of the work-side closing system that accommodates the work with the pressure decreases, and a pressure difference corresponding to the amount of leakage is generated between the work-side closing system A and the pressure of the master-side closing system A. This corresponding differential amplifier of the differential amplifier 70 ₁ to 70 _N is output as the detection differential pressure. When the detected differential pressure exceeds the threshold, the controller 75
It is determined that there is a minute leak, and the damaged work is regarded as a defective product, and is displayed on the display unit 76. The controller 7
5 may convert the detected differential pressure into an atmospheric pressure equivalent leakage amount and compare it with a threshold value.

Next, the second on-off valve 32, 33 ₁ ~ 33 _N,
34, and pressurized air is supplied to the tanks 42 and 43 ₁ to 4.
3 _N, 44 to lead, closed system _A, B 1 _.about.B N, increasing the C of the volume (second leak detection mode). Since the master-side tank 42 and the volume of the workpiece-side tank ₄₃ 1 ~ 43 _N are equal, not detect a differential pressure caused by the differential amplifier ₇₀ 1 to 70 _N in this volume increase. In addition, tank 44 and tank 4
The volume ratio of 2,43 ₁ to 43 _N is determined by the closed system C before the volume increase.
Since equal closed system _A, the volume ratio of B 1 .about.B _N and differential pressure sensor 62 and 63 ₁ to 63 _N, 64 either does not detect the principle differential pressure due to the volume increase, even if The detection sensitivity is small and the detection sensitivity can be kept high.

[0030] If the workpiece is a large scratch on the work internally upon introduction test pressure has become the test pressure, the corresponding pressure of the workpiece a closed system when opened second on-off valve 43 ₁ ~ 43 _N are It will be higher than expected. as a result,
A differential pressure is generated between the master side and the closed system. This differential pressure is detected by the corresponding differential amplifier, and the controller 75 can compare the detected differential pressure with a threshold value to determine a large leak.

When the controller 75 determines that there is no minute leak or large leak, the controller 75 controls the display unit 76 to display a non-defective product, and when there is a leak, displays a defective product. In addition,
The display unit 76 may also display information such as differential pressure information and atmospheric pressure equivalent leakage amount.

Next, the controller 75 turns off the three-way valve 16 to the atmospheric release position, and sets the first on-off valves 22 and 23 _1.
~ 23 _N, 24 by opening in the off, the branch passage 22, 23 ₁ ~ 23 _N, 24 on the downstream side opened to the atmosphere, then turns off the second on-off valve 22, 23 ₁ ~ 23 _N, 24 And close.

As described above, in the present embodiment, a plurality of works W _{1 to} W _N can be simultaneously judged by one leak test apparatus for leaks, and the work efficiency can be improved. In addition, since only one master side passage 12 is required, the configuration is simple. Also, the differential pressure sensors 63 _{1 to} 63 _1
N is the master side, and each equipped with a closed system A of the workpiece side, the B ₁ .about.B _N, since the structure and comparing the pressure with a common back pressure, the master-side, closed system A of the work side, B ₁ ~ B _N
It is possible to easily and structurally make the volume equal and small, improve the sensitivity, and perform an accurate leak test without being affected by temperature fluctuation or the like.

Next, a second embodiment of the present invention will be described.
This will be described with reference to FIG. In this embodiment, each other first block 80 of the same shape ', the second block 85 of the same shape' is, in the first embodiment except for the master M, a point that is separated for each workpiece W ₁ to _W-N The same is true. According to this embodiment, design becomes easy.

Next, a third embodiment of the present invention will be described with reference to FIG. In this embodiment, the sensor assemblies 86 ′ on the master side and the work side each have a casing 87, a joint 88 attached to a cylindrical portion of the casing 87, and a joint 90 attached to the bottom of the casing 87. ing. On the bottom of the casing 87, as in the first embodiment, the differential pressure sensors 62, 63 _1-
63 _N are respectively attached. Differential pressure sensor 6
_2, 63 _{1 to} 63 _N is provided with a casing 87.
Faces respectively through the through holes 87a and the joint 90 of the bottom master side closed system A, the work side closed system _B 1 .about.B _N of the other pressure-receiving surface of the differential pressure sensor 62 and 63 ₁ to 63 _N is space 8
9 and through the joint 88, the branch passage portion _19a of the back pressure supply passage 14 is connected to 19b 1 through 19b _N.

In the third embodiment, the blocks 80,
Since it is the same as the first embodiment except that 85 is not used, detailed description is omitted, but the same operation and effect as in the first embodiment can be obtained.

Next, a fourth embodiment will be described with reference to FIG. In this embodiment, there is one work passage, and the sensor assembly 86 ″ has a cylinder 95 and a pair of casings 87 attached to both ends of the cylinder 95. A master-side differential pressure sensor 62 is attached, and a work-side differential pressure sensor 63 is attached to the bottom of the other casing 87. A back pressure supply passage 1 is provided on the peripheral wall of the cylinder 95.
A joint 96 connected to the first on-off valve and a joint 97 connected to the second on-off valve are attached. Master side differential pressure sensor 6
2 is provided with a through hole 8 at the bottom of the casing 87.
Via the 7 a and the joint 90, the master side passage faces downstream from the first on-off valve, and the other pressure receiving surface faces the back pressure supply passage 14 via the space 98 of the cylinder 95. One pressure-receiving surface of the work-side differential pressure sensor 63 faces downstream from the first opening / closing valve of the work-side passage through the through-hole 87 a at the bottom of the casing 87 and the joint 90, and the other pressure-receiving surface corresponds to the cylinder 95. Space 98
Through the back pressure supply passage 14. Also in this embodiment, the volumes of the master side closing system and the work side closing system can be made equal and small.

The present invention is not limited to the above embodiment, and various modes are possible. For example, instead of the work being housed in the housing space, the work may be formed in a container shape and connected to the work-side passage. The work-side closing system, the master-side closing system, and the back-pressure-side closing system may each be provided with a volume changer for balancing the volumes. The device may detect only minute leaks without the second on-off valve and the tank. A pseudo leak generator may be attached to each work side closed system to calibrate the sensitivity. The back pressure side tank may have a variable capacity according to the work. The air pressure source may be a negative pressure. Also in this case, the air pressure source side is the upstream side.

[0039]

As described above, according to the first aspect of the present invention, a differential pressure sensor is provided for each of a master part and a work, and the master-side differential pressure sensor and the pressure of the master-side closing system are different from each other. Detects the pressure difference, the work side differential pressure sensor detects the difference between the work side closing system pressure and the back pressure, and calculates the deviation of the detected differential pressure from these differential pressure sensors to cancel the effect of the back pressure. As a result, since the differential pressure between the master-side closing system and the work-side closing system is detected, it is easy in design to reduce the volumes of the master-side and work-side closing systems, and the sensitivity can be improved.

According to the second aspect of the present invention, the master side,
Since the volume of the closed system on the work side is made substantially equal, the influence of temperature fluctuation is reliably eliminated, and the differential pressure between the two closed systems can be accurately detected. Further, it is easy to make the volumes equal by using the first aspect. According to the third aspect of the present invention, it is possible to simultaneously detect leakage of a plurality of works by using a plurality of work-side paths and a common master-side path and a back pressure supply path, thereby improving work efficiency. Can be. Even if a plurality of work-side passages are used, it is easy to make the volumes of the master-side closed system and the work-side closed system equal. According to the fourth aspect of the present invention, not only a minute leak of a work but also a large leak can be detected. In addition, by devising the tank volume ratio, a decrease in sensitivity can be avoided.

According to the fifth aspect of the present invention, the size of the apparatus can be reduced by using the common block, and the volumes of the master side closing system and the work side closing system can be reduced. According to the sixth aspect of the present invention, by using the master and the first and second blocks independent for each work,
Design becomes easy. Moreover, since the first and second blocks have the same shape, the influence of temperature fluctuation can be eliminated. Further, the volumes of the master side closing system and the work side closing system can be reduced, and the sensitivity can be improved. According to the fifth aspect of the present invention, even when the differential pressure sensor is attached to the bottom of the casing, the volumes of the master side closing system and the work side closing system can be reduced.

[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 plan view specifically showing a main part structure of the air leak test device.

FIG. 3 is a cross-sectional view of a main structure of the air leak test device.

FIG. 4 is a cross-sectional view showing a main structure of an air leak test apparatus according to a second embodiment of the present invention.

FIG. 5 is a circuit diagram showing a cross section of a main part structure of an air leak test apparatus according to a third embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a main structure of an air leak test apparatus according to a fourth embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 10 air passage 11 common passage 12 master side passage 13 _{1 to} 13 _N work side passage 14 back pressure supply passage 15 test pressure source 19a, 19b _{1 to} 19b branch passage portion of _N back pressure supply passage 22 first open / close valve on master side 23 ₁ to 23 _N First open / close valve on _N work side 24 First open / close valve on back pressure side 32 Second open / close valve on master side 33 _{1 to} 33 Second open / close valve on _N work side 34 Second open / close valve on back pressure side 42 Master Tanks 43 ₁ to 43 _N Work side tank 44 Back pressure side tank 52 Master parts storage space 53 _{1 to} 53 _N work storage space 62 Master side differential pressure sensor 63 _{1 to} 63 _N Work side differential pressure sensor 70 ₁ to 70 _N differential amplifier (differential pressure calculating means) 75 controller (control determining means) 80, 80 'lower block (first block) 85, 85' upper block (second Bro H) 86 sensor assembly 87 casing M master component W ₁ to _W-N workpiece A master closed system B ₁ .about.B _N workpiece side closed system C back pressure side closed system

Claims (7)

[Claims] (A) A common passage whose upstream side is connected to a test pressure source, a master side passage branched from a downstream side of the common passage and connected to a master component or a master component housing space, and a downstream side of the common passage. An air passage having a work or a work-side passage branched from the side and connected to the work or the work accommodating space; (b) first opening / closing valves provided in the master-side passage and the work-side passage, respectively; With the one on-off valve closed, a master side closing system including a passage portion of the master side passage downstream of the first on / off valve, and a work including a passage portion of the work side passage downstream of the first on / off valve. A differential pressure detecting means for detecting a differential pressure between the common passage and the side closing system, wherein the air passage further includes a back pressure supply passage branched from a downstream side of the common passage, Above differential pressure detection hand Is a master side differential pressure sensor for detecting a difference between the back pressure from the back pressure supply passage and the pressure of the master side closing system, and a difference between the back pressure from the back pressure supply passage and the pressure of the work side closing system. Calculate the deviation between the master side differential pressure detected by the master side differential pressure sensor and the work side differential pressure detected by the work side differential pressure sensor,
An air leak test apparatus comprising: a differential pressure calculating means for setting the deviation as a differential pressure between the master side closing system and the work side closing system. 2. The air leak test apparatus according to claim 1, wherein the volumes of the master side closing system and the work side closing system are substantially equal. 3. A plurality of work-side passages are branched from a downstream side of the common passage, a work or a work accommodation space is connected to each of the work-side passages, and the first on-off valve is provided. Work side differential pressure sensors are respectively provided corresponding to a plurality of work side closing systems including a passage portion downstream of the first opening / closing valve of the passage, and each work side differential pressure sensor is provided with a corresponding work side closing system. A differential pressure between the pressure and the back pressure of the common back pressure supply passage is detected, and the differential pressure calculating means calculates the difference between the detected differential pressure of the work side differential pressure sensor and the detected differential pressure of the common master side differential pressure sensor. 3. The air leak test apparatus according to claim 2, wherein each of the deviations is calculated. 4. A second on-off valve is connected to the master side passage downstream of the first on-off valve.
A master-side tank is connected to the downstream side of the on-off valve, and one pressure-receiving surface of the master-side differential pressure sensor faces between the first and second on-off valves. A second on-off valve is connected on the further downstream side, a work-side tank is connected on the downstream side of the second on-off valve, and one pressure-receiving surface of the work-side differential pressure sensor is provided between the first and second on-off valves. In the back pressure supply passage, first and second on-off valves are connected in order from the upstream side to the downstream side, and a back-pressure side tank is connected downstream of the second on-off valve. The other pressure-receiving surface of the master-side differential pressure sensor and the work-side differential pressure sensor faces between the second on-off valves. The master-side tank and the work-side tank have substantially equal volumes. The volume ratio of the work-side tank is determined by closing the first and second on-off valves. And the control system is provided with control determination means, and the control determination means closes all the second on-off valves and completely closes the second open / close valve. The test pressure application mode in which the test pressure is applied by opening the first on / off valve of the first, and the master side closing system, the work side closing system and the closing system of the back pressure supply passage by closing all the first on / off valves. The first leak detection mode to be formed, and then the second second on-off valve is opened to increase the volume of each closed system by the tank volume.
A leak detection mode is executed, and the presence or absence of a minute leak of the work is determined based on the differential pressure information from the differential pressure calculation means in the first leak detection mode. 4. The air leak test apparatus according to claim 2, wherein the presence or absence of a large leak of the work is determined based on the differential pressure information. 5. A system according to claim 1, further comprising a common first block and a common second block which comes into contact with and separates from the first block. The first block includes a master component accommodating space and a work accommodating space. Through holes are respectively formed in the housing spaces, and these through holes form a part of a passage portion downstream of the first on-off valve in the master side passage and the work side passage. A sensor assembly is mounted corresponding to each of the spaces, and one of the pressure receiving surfaces of the differential pressure sensor incorporated in the sensor assembly faces the housing space via a through hole formed in the second block, and The supply passage is branched into a plurality of portions, and the other pressure-receiving surfaces of the master-side and work-side differential pressure sensors face these branch passage portions. On-board air leak test equipment. 6. A plurality of first blocks having the same shape, each having a master component accommodating space and a work accommodating space formed therein, and a plurality of second blocks having the same shape which are respectively brought into contact with and separated from the first blocks. , In the first block,
Through holes are respectively formed in the accommodation spaces, and these through holes respectively constitute a part of a passage portion of the master side passage and the work side passage downstream of the first on-off valve, and the second block includes: A sensor assembly is attached to each of the housing spaces, and one of the pressure receiving surfaces of the differential pressure sensor incorporated in the sensor assembly is the second pressure receiving surface.
The back pressure supply passage is branched into a plurality of portions through a through hole formed in the block, and the other pressure receiving surface of the master-side and work-side differential pressure sensors faces these branch passage portions. The air leak test apparatus according to any one of claims 2 to 4, wherein: 7. The master-side differential pressure sensor and the workpiece-side differential pressure sensor are mounted on the bottom of a bottomed cylindrical casing having the same shape, and the one pressure receiving surface has a through hole formed in the bottom. 7. The master-side closing system and the work-side closing system via a housing, and the other pressure-receiving surface faces the back-pressure-side closing system via the space of the casing. Air leak test equipment.