JP4140445B2 - Leak inspection method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is used in a leakage inspection method suitable for inspecting leakage of an object to be inspected that uses the inside as a fluid storage space, such as a cylinder block constituting a part of a compressor housing, and the method. It relates to the device.
[0002]
[Prior art]
For example, a compressor used in a vehicle air conditioner often uses an aluminum die-cast housing from the viewpoint of weight reduction. In such a housing, an accurate inspection for refrigerant leakage is required. For this reason, at present, the compressor that has been assembled is inspected for leaks with a helium leak inspection device or the like in the final inspection process (see Patent Document 1). Then, after disassembling the compressor and replacing the corresponding parts causing the leakage, the work is reassembled.
[0003]
However, according to such a method, it is necessary to reassemble the compressor each time a leak is detected, which is troublesome and results in poor production efficiency. For this reason, it is desirable to inspect for leakage in the housing alone constituting the compressor, but the helium test apparatus is very expensive and large-scale, so it is not suitable for inspecting the housing one by one. is there. For this reason, conventionally, the housing is formed in a hermetic state with a jig, then submerged in a water tank, and high-pressure air is applied to the inside of the housing to inspect whether air leaks and bubbles are generated. (See Patent Document 2).
[0004]
[Patent Document 1]
JP 2001-235386 A (see column 0003)
[Patent Document 2]
JP 2000-310579 A (see column 0003)
[0005]
[Problems to be solved by the invention]
However, in the submergence inspection as described above, since a method for visually determining the presence or absence of bubbles is taken, it is inefficient to inspect the housings one by one, and there is no guarantee that accurate inspection can be performed. It was.
[0006]
Therefore, in the present invention, a leakage inspection method capable of simply and accurately inspecting an inspection object such as a housing that uses the inside as a fluid storage space to check for leakage and improve inspection efficiency. The main object is to provide an apparatus used for carrying out the method.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a leakage inspection method according to the present invention is a leakage inspection method for inspecting leakage of an object to be inspected using the inside as a fluid containing space, wherein the first is sealed inside the object to be inspected. And a second sealed space that surrounds the object to be inspected is formed outside the object to be inspected, and is formed in one of the first sealed space and the second sealed space. sealed in a state filled with other incompressible fluid supplies more gas atmospheric pressure, determining the presence or absence of leakage of the inspection object by capturing a change in pressure of the sealed space sealed the incompressible fluid (1).
[0008]
In particular, in an inspection object that is sealed using the internal pressure of the inspection object, a gas at atmospheric pressure or higher is supplied to the first sealed space, and an incompressible fluid is supplied to the second sealed space. It is preferable to seal (Claim 2). Here, air may be used as the gas, and water may be used as the incompressible fluid (claims 3 and 4).
[0009]
Accordingly, a sealed space to which high-pressure gas is supplied is formed on one of the inside and the outside of the object to be inspected, and a sealed space in which the incompressible fluid is sealed is formed on the other side. When the high-pressure gas supplied to the air leaks through the object to be inspected, the pressure in the other sealed space increases. For this reason, it is possible to determine the presence or absence of leakage of the inspection object by grasping the presence or absence of pressure change in the other sealed space (the sealed space where the incompressible fluid is sealed). There is no need to rely on, and accurate inspection for leaks is possible. In order to improve the inspection accuracy, a process for removing fluid other than the incompressible fluid is performed on the sealed space where the incompressible fluid is sealed before determining whether there is a leakage of the inspection object. (Claim 5).
[0010]
Further, as an inspection apparatus for realizing the inspection method as described above, the inspection object is accommodated, a first sealed space sealed inside the inspection object is formed, and outside the inspection object. A test object container that forms a sealed second sealed space surrounding the test object, and a pressurized gas supply means for supplying a pressurized gas to one of the first sealed space and the second sealed space And a non-compressible fluid sealing means for sealing the other of the first sealed space and the second sealed space with the incompressible fluid, and a pressure change in the sealed space sealed with the incompressible fluid. Thus, it may be possible to have a judging means for judging the presence or absence of leakage of the inspection object (claim 6).
[0011]
Here, the pressurized gas supply means supplies the pressurized gas to the first sealed space, and the incompressible fluid sealing means seals the incompressible fluid to the second sealed space. 7) Further, air may be used as a gas, and water may be used as an incompressible fluid (claims 8 and 9). In order to improve detection accuracy, means for removing fluid other than the incompressible fluid may be further provided in the sealed space where the incompressible fluid is sealed.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, a leak inspection apparatus 1 for inspecting a leak of an inspection object is shown. Here, the object to be inspected is an object whose inside is used as a fluid accommodating space, and in this example, the object is a cylinder block 2 constituting a part of the housing of the compressor.
[0013]
The leak inspection apparatus 1 is airtightly attached to a base body 4 in which a recess 3 for accommodating a cylinder block 2 is formed, and a sealing member 5 to the base body 4, and provides a space for accommodating the cylinder block 2 between the base body 4. An inspection object container 7 having a lid 6 to be formed is provided.
[0014]
Here, the cylinder block 2 forms a cylindrical body, and is fixed to a support portion 8 formed substantially at the center away from the inner wall of the base body 4. A sealing member 9 such as an O-ring is provided on the inner surface of the base 4 on which the base 4 comes into contact, so that the base 4 and the cylinder block 2 are in airtight contact. Further, when the lid body 6 is attached with the cylinder block 2 attached to the base body 4, the gap between the lid body 6 and the end face of the cylinder block 2 facing the lid body 6 is hermetically sealed via a seal member 10 such as an O-ring. It comes to contact.
[0015]
Therefore, when the cylinder block 2 is accommodated in the base body 4 and the lid body 6 is attached, the inside of the cylinder block 2 is closed by the base body 4 and the lid body 6, and the first sealing is sealed inside the cylinder block 2. A space 11 is defined. Further, the outside of the cylinder block 2 is closed by the base body 4 and the lid body 6, and a second sealed space 12 sealed outside the cylinder block 2 is defined so as to surround the cylinder block 2.
[0016]
The base 4 of the inspected object container 7 has a first piping connector 13 communicating with the first sealed space 11, second and third piping connectors 14 communicating with the second sealed space 12, 15 are attached.
[0017]
Two poppet type solenoid valves 16 and 17 are piped in parallel to the first pipe connector 13. One poppet valve type electromagnetic valve 16 is connected to the discharge side of a pump 18 that pressurizes and pumps gas, and constitutes an air supply valve for supplying the gas pumped from the pump 18 to the first sealed space 11. ing. The other poppet valve type electromagnetic valve 17 constitutes an exhaust valve for opening the first sealed space 11 to the atmosphere and discharging the pressurized gas supplied to the first sealed space 11. .
[0018]
Two poppet type solenoid valves 19 and 20 are piped in parallel to the second pipe connector 14. One poppet valve type electromagnetic valve 19 is connected to a discharge side of a pump 21 that pressurizes and compresses an incompressible fluid, and supplies the incompressible fluid pumped from the pump 21 to the second sealed space 12. It constitutes a fluid supply valve. The other poppet valve type electromagnetic valve 20 constitutes a discharge valve for discharging the incompressible fluid supplied into the second sealed space 12 to the tank 22.
[0019]
The third pipe connector 15 is disposed on the upper part of the inspection object container 7, and two poppet valve type electromagnetic valves 23 and 24 are connected in parallel to the pipe connector. One poppet valve type electromagnetic valve 23 is connected to the discharge side of a pump 25 that pressurizes and feeds air, and supplies air to the second sealed space 12 when the incompressible fluid is extracted from the second sealed space 12. This constitutes a pressure valve. The other poppet valve type electromagnetic valve 24 opens the second sealed space 12 to the atmosphere, and draws air from the second sealed space 12 when supplying the incompressible fluid to the second sealed space 12. The air purge valve for this is comprised.
[0020]
Between the third piping connector 15 and the branch point of the two poppet type solenoid valves 23 and 24, a safety valve 26 for relieving the pressure when the pipe internal pressure becomes a predetermined pressure or more, A pressure switch 27 is connected to detect that the pressure of the incompressible fluid is equal to or higher than a predetermined pressure.
[0021]
Here, as the gas supplied to the first sealed space 11, for example, air is used, and as the incompressible fluid supplied to the second sealed space 12, for example, water is used. The air supplied to the first sealed space 11 is pressurized to atmospheric pressure or higher (for example, 10 to 30 kg / cm ² ) by the pump 18, and the water supplied to the second sealed space 11 is pressurized. In this example, it is assumed that no pressure is applied.
[0022]
Each poppet valve type solenoid valve (16, 17, 19, 20, 23, 24) and each pump (18, 21, 25) are controlled based on an output signal from the control unit 28. Yes. The control unit 28 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), an input / output port (I / O), etc. (not shown), and each poppet valve type electromagnetic valve and pump. And a drive circuit for driving and controlling the signal, a signal from the pressure switch 27 is input, the input signal is processed in accordance with a predetermined program given to the memory, and the poppet valve type solenoid valve is switched, The on / off state of the pump is controlled to inspect for the leakage of the inspection object (cylinder block 2).
[0023]
In FIG. 2, an example of processing for inspecting a leakage of an inspection object is shown as a flowchart, and the processing for leakage inspection will be described below based on this flowchart.
[0024]
First, in inspecting the leakage of the inspection object (cylinder block 2), in step 50, a work consisting of the cylinder block 2 is set on the base body 4, and in the next step 52, the control unit 36 is energized to perform a memory check. Perform initial settings such as.
[0025]
In step 54, the lid 6 is attached to the base body 4, the object to be inspected (cylinder block 2) is clamped between them, the first sealed space 11 is placed inside the cylinder block 2, and the cylinder block 2. The second sealed space 12 is formed on the outer side of the first.
[0026]
Thereafter, in step 56, the poppet valve type electromagnetic valve 16 is switched to the open state (ON), and the compressed air is supplied to the first sealed space 11 by the pump 18 via the first piping connector 13, and the poppet valve The electromagnetic valve 19 is switched to the open state (ON), and water is supplied to the second sealed space 12 by the pump 21 via the second piping connector 14.
[0027]
At the same time, in step 58, the poppet valve type electromagnetic valve 24 is switched to the open state (ON) to open the second sealed space 12 to the atmosphere, and with the inflow of water into the second sealed space 12. The air in the space where there was no place to go is released to the atmosphere.
[0028]
Thereafter, after the second sealed space 12 is filled with water, the poppet valve type solenoid valve (air purge valve) 24 is closed (OFF) to form a state in which the second sealed space 12 is sealed with water, Wait in a state (steps 60 and 62). Further, the poppet valve type electromagnetic valve 19 is closed (OFF) to stop water supply to the second sealed space 12 and wait for the pressure in the second sealed space 12 to stabilize in this state (step 64). 66).
[0029]
After the pressure is stabilized, the signal output from the pressure switch 27 is read as pressure data, and this measurement state is continued for a predetermined time (steps 68 and 70). Thereafter, in step 72, based on a signal from the pressure switch 35, a leakage determination of the inspection object (cylinder block 2) is performed.
[0030]
Around the first sealed space 11 to which the pressurized air is supplied, a second sealed space in which an incompressible fluid is sealed through an object to be tested (cylinder block 2) is provided. When an air leak occurs in the object, the compressed air is leaked into the incompressible fluid in the second sealed space, and the pressure in the second sealed space is increased. For this reason, if the operating point of the pressure switch 27 is adjusted to a predetermined pressure that does not operate in a leak-free state, the pressure of the second sealed space 12 exceeds the predetermined pressure and the pressure switch 27 is activated. In this case, it is recognized that there is a leak in the inspection object (cylinder block 2). In this case, the inspection object is regarded as a defective product (NG), and the process of sorting the defective products in steps 74 to 84 is performed. Do. Further, if the pressure in the second sealed space 12 does not change even after a predetermined time has passed and the pressure switch 27 does not operate, it is recognized that there is no leakage in the inspection object (cylinder block 2). The inspection object is regarded as a non-defective product (OK), and in steps 86 to 96, the non-defective product is sorted.
[0031]
Specifically, as a result of the leakage determination, if it is determined that there is leakage in the inspection object, the poppet valve type electromagnetic valve 16 is closed (OFF), and the poppet valve type electromagnetic valve 17 is opened (ON). Then, the compressed air in the first sealed space 11 is discharged, the poppet valve type solenoid valve 19 is closed (OFF), the poppet valve type solenoid valve 20 is opened (ON), and the second sealed space 12 is opened. The water is discharged and this state is continued for a while (steps 74 and 76). Thereafter, the poppet valve type electromagnetic valve 20 is closed (OFF) to stop the drainage treatment (step 78), the lid body 6 is removed, and the cylinder block 2 held in the inspection object container 7 is unclamped. (Step 80), this inspection object (work) is removed from the base body 4 (Step 82), and distributed to a conveyor for collecting defective products (Step 84).
[0032]
On the other hand, if it is determined that there is no leakage of the inspection object, the poppet valve type solenoid valve 16 is closed (OFF) and the poppet valve type solenoid valve 17 is opened (ON). Then, the compressed air in the first sealed space 11 is discharged, the poppet valve type solenoid valve 19 is closed (OFF), the poppet valve type solenoid valve 20 is opened (ON), and the second sealed space 12 is opened. The water is discharged and this state is continued for a while (steps 86 and 88). Thereafter, the poppet valve type solenoid valve 20 is closed (OFF) to stop the drainage process (step 90), the lid body 6 is removed, and the cylinder block 2 held in the object container 7 is unclamped. (Step 92), this inspection object (workpiece) is removed from the substrate 4 (Step 94), and is distributed to a conveyor for collecting good products.
[0033]
Therefore, according to the above leakage inspection method, it is possible to determine the presence or absence of leakage of the inspection object by capturing the pressure change in the second sealed space 12 with the pressure switch 27. No need to rely on judgment. Therefore, it is possible to individually inspect the inspection object with a simple apparatus without using a large-scale apparatus such as a helium leak inspection apparatus, and all inspection objects to be inspected can be easily and accurately performed. It becomes possible to inspect.
[0034]
In addition, according to the above-described inspection method, it is possible to inspect the total number of inspected objects in advance before making the final product, and to sort defective products that cause leakage and good products that do not leak. There is no inconvenience that good products are assembled.
[0035]
As described above, according to the above-described leak inspection method, the leak inspection is performed by capturing the pressure change that occurs when the compressed air leaks into the second sealed space. The air (gas) mixed in the water (incompressible fluid) is preferably completely removed in advance for highly accurate inspection.
[0036]
FIG. 3 shows a configuration example of the leakage inspection apparatus 1 to which a deaeration process is added based on this point. Hereinafter, the apparatus will be described with a focus on differences from the configuration example.
[0037]
In this example, two poppet valve-type electromagnetic valves 30 and 31 are connected in series with the second piping connector 14 of the inspected object container 7 with the directions of the check valves being reversed. It is connected to the water tank 32 through 31. Further, a water level control tank 33 having a float switch 33 a is connected to the third piping connector 15 via a poppet valve type electromagnetic valve 32. This water level control tank 33 reaches a predetermined water level after the second sealed space 12 is completely filled with water, and the float switch 33a is activated (ON). The float switch 33a operates. Thus, it can be detected that the second sealed space 12 is full.
[0038]
A mist separator 34 is connected to the gas phase region of the water level control tank 33, and two poppet valve type electromagnetic valves 35, 36 are arranged in the lower part of the mist separator 34 with the check valves facing in opposite directions. The water connected in series and separated by the mist separator 34 is discharged to the tank 37 through the poppet valve type electromagnetic valves 35 and 36. Further, a vacuum pump 40 is connected to the mist separator 34 via a poppet valve type electromagnetic valve 38 constituting a vacuum valve and a buffer tank 39 so that air separated by the mist separator 34 is sucked.
[0039]
In addition, two poppet valve type solenoid valves 41 and 42 are connected in parallel to the mist separator 34, and one poppet valve type solenoid valve 41 is connected to a discharge side of a pump 43 that pressurizes and pumps air. When water sealed in the second sealed space 12 is drained, pressurized air is supplied to the second sealed space 12 to constitute an air supply valve for promoting drainage. The other poppet valve type electromagnetic valve 42 is connected to a pump 43 through a regulator 44, and has a low pressure adjusting valve for returning the second sealed space 12 to a slightly higher atmospheric pressure after deaeration with the vacuum pump 40. It is composed.
[0040]
The third piping connector 15 is provided with a safety valve 46 for relieving the pressure when the second sealed space 12 becomes a predetermined pressure or higher via a poppet valve type electromagnetic valve 45, and an uncompressed A pressure switch 47 is connected to operate when the pressure of the sexual fluid (water) exceeds a predetermined pressure. In addition, since the other structure is the same as that of the said structural example, the same number is attached | subjected to the same location and description is abbreviate | omitted.
[0041]
FIG. 4 is a flowchart showing an example of processing for inspecting leakage of an inspection object using this inspection apparatus. In this example, steps 100 to 106 are performed instead of steps 58 to 64 in FIG. 2. Hereinafter, this point will be described. In step 56, high-pressure air is introduced into the first sealed space 11. When the water is supplied to the second sealed space 12, the float switch 33a of the water level control tank 33 is actuated in the next step 100 until the second sealed space 12 becomes full. The system waits and stops water absorption when the float switch 33a is turned on (step 102).
[0042]
Thereafter, the vacuum pump 40 is actuated to start degassing, and the pressure in the second sealed space 12 is once lowered below the atmospheric pressure, and then a low pressure adjusting valve (poppet valve electromagnetic) is used to return it to a slightly positive pressure. The valve 42) is operated to supply low-pressure air (104, 106). And it seals in this state, and waits for the pressure in 2nd sealed space to become stable (step 66). Since other processes are the same as those in the above configuration example, the same portions are denoted by the same reference numerals and description thereof is omitted.
[0043]
Therefore, in such an inspection method, the air dissolved in the water supplied to the second sealed space 12 and the air remaining in the bag-like portion of the workpiece (cylinder block 2) are forcibly taken (step 104). Then, since the pressure change in the second sealed space 12 is captured thereafter, it is possible to inspect the leakage of the inspection object with high accuracy and eliminate erroneous determination.
[0044]
In the above-described configuration, the pressure change in the second sealed space 12 is captured using the pressure switch 27 that operates at a predetermined pressure. However, the pressure in the second sealed space 12 is detected in real time by the pressure sensor. It is also possible to detect whether there is a leakage of the inspection object by detecting that the pressure detected by the pressure sensor has changed so as to satisfy a predetermined condition. Alternatively, the pressure data is not taken into the sequencer, the panel meter (pressure switch amplifier) is reset to zero when the pressure is stable, and if the specified value set in the panel meter is exceeded after a certain period of time, the object to be inspected is defective (NG ) May be determined.
[0045]
Further, in the above description, an example using a cylinder block as an object to be inspected is shown. However, if an object to be inspected uses the inside as a fluid storage space, a leak inspection can be performed using the same method. Yes, it is not limited to the cylinder block. For example, it may be used when leak detection is performed on a cylinder head constituting a compressor, and an assembly in which individual parts are assembled depending on a jig for holding an inspection object in an inspection object container. It may be used to check for product leaks.
[0046]
When leak inspection is performed on an assembly such as a compressor, corrosion is a problem for ferrous materials and erosion is a problem for seal materials. Instead of using, it is desirable to substitute a suitable fluid. In particular, it is desirable to select an incompressible fluid according to the application such as HCFC solvent, alcohol solvent, hydrocarbon solvent, etc. in consideration of quick drying after inspection.
[0047]
Furthermore, as a leakage inspection method using the above-described leakage inspection apparatus, the inspection object is sealed and filled with a pressurized gas, and this inspection object is set in the inspection object container and surrounded by the surroundings. An incompressible fluid may be filled so that changes in pressure can be captured as well.
[0048]
The above inspection apparatus is configured to detect leakage by applying a pressure higher than atmospheric pressure to the inside of the object to be detected and detecting a pressure change of the incompressible fluid sealed outside, It is good also as a structure which reverses the introductory location of an incompressible fluid, seals an incompressible fluid inside a to-be-inspected object, and applies the pressure more than atmospheric pressure to the outside.
When the workpiece is set in the inspection object container 7 and an internal pressure higher than atmospheric pressure is applied to the inside, it is necessary to increase the clamp pressure so as not to leak and press the jig against the workpiece with a considerable sheet force. However, there is concern about the deformation or damage of the workpiece, but the configuration in which the pressure higher than atmospheric pressure is applied to the outside makes it possible to reduce the clamping pressure and eliminate the risk of workpiece deformation or damage. Has the advantage of being able to.
[0049]
【The invention's effect】
As described above, according to the present invention, a first sealed space sealed inside is formed with respect to an object to be inspected using the inside as a fluid storage space, and the object to be inspected is surrounded on the outside. a sealed second closed space formed, and sealed in a state filled with the other closed space incompressible fluid supplies atmospheric pressure or more gases at one of the closed space, and sealing the non-compressible fluid Since it is possible to determine the presence or absence of leakage of the inspection object by detecting the pressure change in the sealed space, it is not necessary to rely on human judgment by visual inspection etc., and it is possible to inspect the inspection object for leakage easily and accurately. Thus, the inspection efficiency can be improved.
[0050]
In addition, by performing a process for removing fluid other than the incompressible fluid on the sealed space in which the incompressible fluid is sealed before determining whether there is a leakage of the object to be inspected, the inspection accuracy of the leakage is further increased. It becomes possible to raise.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of a leakage inspection apparatus.
FIG. 2 is a flowchart for explaining a leakage inspection method using the leakage inspection apparatus shown in FIG. 1;
FIG. 3 is a diagram illustrating another configuration example of the leakage inspection apparatus.
FIG. 4 is a flowchart for explaining a leak inspection method using the leak inspection apparatus shown in FIG. 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Leak inspection apparatus 2 Cylinder block 11 1st sealed space 12 2nd sealed space

Claims (10)

In a leakage inspection method for inspecting leakage of an object to be inspected using the inside as a fluid storage space,
Forming a sealed first sealed space inside the inspected object, and forming a sealed second sealed space surrounding the inspected object outside the inspected object;
Sealing one of the first sealed space and the second sealed space in a state where a gas at atmospheric pressure or higher is supplied and the other is filled with an incompressible fluid ;
A leakage inspection method, wherein the presence or absence of leakage of the object to be inspected is determined by capturing a pressure change in a sealed space in which the incompressible fluid is sealed. The leak inspection method according to claim 1, wherein a gas having an atmospheric pressure or higher is supplied to the first sealed space, and the incompressible fluid is sealed in the second sealed space. The leak inspection method according to claim 1, wherein the gas at or above atmospheric pressure is air. The leak inspection method according to claim 1, wherein the incompressible fluid is water. 2. The sealed space in which the incompressible fluid is sealed is subjected to a process for removing fluid other than the incompressible fluid before determining whether or not the inspection object has leaked. Leak inspection method. In a leak inspection apparatus for inspecting leakage of an object to be inspected using the inside as a fluid storage space,
The test object is accommodated, a first sealed space sealed inside the test object is formed, and a sealed second sealed space surrounding the test object is formed outside the test object. An object container to be formed; and
Pressurized gas supply means for supplying a pressurized gas to one of the first sealed space and the second sealed space;
Incompressible fluid sealing means for sealing in a state where the other of the first sealed space and the second sealed space is filled with an incompressible fluid;
A leak inspection apparatus comprising: determination means for determining presence or absence of leakage of the object to be inspected by capturing a pressure change in a sealed space in which the incompressible fluid is sealed. The pressurized gas supply means supplies pressurized gas to the first sealed space, and the incompressible fluid sealing means seals an incompressible fluid in the second sealed space. The leak inspection apparatus according to claim 5. 8. The leak inspection apparatus according to claim 6, wherein the pressurized gas is air. The leak inspection apparatus according to claim 6 or 7, wherein the incompressible fluid is water. The leak inspection apparatus according to claim 6, further comprising a means for removing fluid other than the incompressible fluid in the sealed space in which the incompressible fluid is sealed.

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