KR20110056880A - Method and apparatus for airtight inspection using equalization - Google Patents

Abstract

PURPOSE: An airtightness inspection method and apparatus using pressure equilibrium are provided to accurately check the airtight seal of an inspection target within a short time. CONSTITUTION: An airtightness inspection apparatus using pressure equilibrium comprises a receiver tank(200) which stores compressed air, a pressure equalization line(210) which connects the receiver tank and an inspection target so that the compressed air of the receiver tank is provided to the inspection target to make pressure equilibrium, a flow meter(220) which is installed in the pressure equalization line to measure the flow rate of compressed air delivered from the receiver tank to the inspection target, a first opening/closing valve(230) which is installed in the pressure equalization line, and a control unit(600) which displays the detected flow rate of compressed air and determines the leakage of the inspection target according to the detected flow rate after the pressure equilibrium between the inspection target and the receiver tank.

Description

Method and apparatus for airtight inspection using equalization

The present invention relates to an airtight inspection apparatus and method for inspecting the airtight state of an article to be inspected.

Products that require airtightness, that is, products such as oil tanks and radiators are essentially subjected to the airtight test during the manufacturing process. One embodiment of the conventional airtight test method is to put an air-filled test object in the water to leak air When the bubble phenomenon occurs when the confidentiality was confirmed. However, this method must be inspected while the object is in the water, which increases the man-hours of the measurement, which is cumbersome, and also makes it impossible to measure the object that cannot be placed in the water.

In another embodiment, air is filled in the inspection object and a pressure gauge is attached to the inspection object to check whether it is airtight according to a change in the pressure gauge generated when air flows out. However, the method of measuring according to the change of air pressure is a large amount of the air is filled out a small amount of time, it takes a lot of time to measure, and it is inconvenient to rely on manual work because the change of the pressure gauge should be visually confirmed.

In another embodiment, Japanese Patent Application Laid-Open No. 4-221733 or Japanese Patent No. 3186438 uses a differential pressure sensor to detect the pressure of the gas in the inspection object and the pressure of the pressurized gas supplied from the pressurized gas source. The presence or absence of the leak was determined by detecting the pressure difference of. However, the method using the differential pressure sensor as disclosed in Japanese Patent Application Laid-Open Nos. 4-221733 and 3186438 described above requires a complicated piping structure in addition to the expensive sensor, and also requires a complicated correction process. In general, there is a problem of complicated systems.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object thereof is to provide an airtight inspection apparatus and method using pressure balance which can accurately check the airtight state of an inspection object in a short time.

In addition, an object of the present invention is to provide an airtight inspection apparatus and method using pressure balance, which is inexpensive, compact, automatic, and can accurately determine leakage of an inspection object.

The objects of the present invention are not limited thereto, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

Leak test device using the pressure balance of the present invention for achieving the above object is a receiver tank is stored compressed air; A pressure balancing line connecting the receiver tank and the inspection object to achieve a pressure balance while providing compressed air stored in the receiver tank to the inspection object; A mass flow meter installed on the pressure balance line to measure a flow rate of the compressed air moving from the receiver tank to the inspection object; A first opening / closing valve installed on the pressure balancing line; And a controller for displaying the flow rate of the compressed air measured by the mass flow meter and determining whether the inspection object is leaked according to the flow rate value generated after the pressure balance time between the receiver tank and the inspection object.

According to an embodiment of the present invention, a bypass line branched from the pressure balance line for quickly providing compressed air stored in the receiver tank to the inspection object without passing through the mass flow meter and the first opening / closing valve, It further includes a bypass valve installed in the bypass line.

According to an embodiment of the present invention, the volume of the receiver tank is larger than the volume of the inspection object.

According to an embodiment of the present invention, the apparatus further includes a dummy line branched between the mass flow meter and the first opening / closing valve and provided with a dummy valve having a certain amount of leakage.

According to an embodiment of the present invention, an air compressor for compressing air; A supply line for supplying compressed air to the receiver tank through the air compressor; And a pressure control valve and a second open / close valve installed on the supply line.

According to an embodiment of the invention, the first pressure gauge for measuring the pressure of the receiver tank; It further comprises a second pressure gauge for measuring the pressure of the inspection object.

According to an embodiment of the present invention, the pressure balance line or bypass line, and further comprises an exhaust line having an exhaust valve for exhausting the compressed air filled in the inspection object to the atmosphere after the leak test.

Airtight inspection method of the inspection object using the air flow change to achieve the above object is the step of storing the compressed air in the receiver tank; A pressure balance step of achieving a pressure balance between the receiver tank and the inspection object by providing the compressed air stored in the receiver tank to the inspection object; Detecting an air flow rate through a mass flow meter to determine whether there is air movement from the receiver tank to the inspected object after the pressure balance between the receiver tank and the inspected object is achieved; And a determining step of determining whether the inspection object is leaked according to a flow rate value generated after the pressure balance time of the receiver tank and the inspection object.

According to an embodiment of the present invention, the pressure balancing step is to open the pressure balance line and the bypass line connecting the receiver tank and the inspection object to quickly provide the compressed air stored in the receiver tank to the inspection object. Moving step; And a pressure balance stabilization step of achieving a pressure balance stabilization between the receiver tank and the inspection object after closing the bypass line.

According to an embodiment of the present invention, in the flow rate detecting step, the mass flow meter is installed in the pressure balance line to detect the flow rate moving through the pressure balance line.

According to an embodiment of the present invention, the determining step, if the detection amount from the mass flow meter is zero or less than a predetermined value, it is determined that the leak is not present because the airtightness of the inspection object is complete, and the inspection object in the receiver tank When the air flow is generated while the detection amount from the mass flow meter is detected or more than a predetermined value, it is determined that there is a leak in the inspection object.

According to an embodiment of the present invention, the pressure movement step further comprises the step of supplying compressed air to the receiver tank to replenish the amount of compressed air moved to the inspection object to replenish the compressed air to the receiver tank.

According to an embodiment of the present invention, to determine whether there is a blockage failure of the inspection object by measuring the internal pressure of the inspection object to confirm whether compressed air is provided to the inspection object from the receiver tank before the flow rate detecting step. It further comprises a step.

According to the present invention, the airtight state of the inspection object can be confirmed accurately in a short time.

In addition, the present invention is inexpensive, compact, automatic, and can accurately determine the leakage of an inspection object.

Hereinafter, an airtight inspection apparatus and a method using pressure balance according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible, even if shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

(Example)

1 is a block diagram for explaining an airtight inspection apparatus using the pressure balance according to the present invention.

1, the airtight inspection apparatus 10 of the present invention is an air compressor 100, supply line 110, receiver tank 200, pressure balance line 210, mass flow meter 220, the first opening and closing The valve 230, the bypass line 300, the dummy line 400, the exhaust line 500, and the controller 600 may be included.

The air compressor 100 generates air of a constant pressure (compressed air), and the compressed air thus generated is stored in the receiver tank 200 through a supply line. The supply line 110 is provided with a normal pressure control valve 112 and a second open / close valve 114 that is an on / off valve. The pressure of the receiver tank 200 is raised to a predetermined pressure (for example, 3kg / cm 2 pressure) by the pressure control valve 112.

The receiver tank 200 stores the compressed air supplied through the air compressor 100. The volume of the receiver tank 200 must be larger than the volume of the inspection object 1, and in this embodiment, the volume of the receiver tank 200 is set to 15L, the volume of the inspection object 1 is 1L. However, this is only one example, and at least the receiver tank 200 preferably has a volume of 2 times or more than the inspection object 1, and more preferably, 10 to 20 times the volume. Of course, as the volume of the receiver tank 200 is larger than the volume of the inspection object, more precise and rapid flow rate detection is possible in the leak inspection process.

The receiver tank 200 communicates the inspection object 1 through the pressure balance line 210. A connector 218 is installed at one end of the pressure balancing line 210, and the connector 218 is connected to the inlet (cooling water injection port) of the radiator, which is the measurement object 1, in a state of airtightness, and the entrance of the measurement object. It is detachably connected in a clamping manner. The connector 218 is selectively formed depending on the size or shape of the entrance of the object to be inspected to maintain the airtightness of the connection portion. On the other hand, the first pressure gauge 20 is for checking the pressure state of the receiver tank 200, it is possible to determine the pressure state inside the receiver tank 200 through the first pressure gauge 20. And the second pressure gauge 30 is for checking the pressure state of the inspection object (1). The second pressure gauge 30 preferably measures the pressure at the rear end of the inspection object, that is, the position farthest from the portion where the compressed air is introduced.

The mass flow meter 220 and the on / off valve first opening / closing valve 230 are installed on the pressure balancing line 210. As the mass flow meter 220, a precision flow meter capable of detecting a flow rate of 5 cc / min, for example, 5 cc / min is used. The mass flow meter 220 is positioned in front of the first opening / closing valve 230 with respect to the receiver tank 200.

The bypass line 300 is a line branched from the pressure balance line 200 and bypassed without passing through the mass flow meter 220 and the first opening / closing valve 230. The bypass line 300 is for quickly providing the compressed air stored in the receiver tank 200 to the inspection object 1. The bypass line 300 is provided with a bypass valve 310 that is an on-off valve. The bypass line 300 is used in the pressure movement stage, which is the pressure balance stage, and in the pressure movement stage, the pressure balance line 210 and the bypass line 300 connecting the receiver tank 200 and the inspection object 1 to each other. By opening, the compressed air stored in the receiver tank 200 is quickly provided to the inspection object 1. If the bypass line 300 is not provided, the compressed air stored in the receiver tank 200 should be moved to the inspection object 1 only through the pressure balance line 210, so that a considerable time is required to move the pressure. Thus, bypass line 300 is an essential configuration for rapid pressure movement.

The dummy line 400 branches off from the pressure balance line 210. The branch point of the dummy line 400 is located between the mass flow meter 220 and the first opening / closing valve 230, and the dummy line 400 is provided with a dummy valve 410 which is an on / off valve, and the dummy line 400. At the rear end, a dummy master 420 having a constant leakage amount is installed to allow a constant flow rate to escape to the atmosphere when the dummy valve 410 is opened. That is, the dummy line 400 is an amount of leakage from the dummy master 420 by opening the dummy valve 410 in a state in which the first opening / closing valve 230 is blocked before the leak inspection of the inspection object (initial inspection). If the mass flowmeter does not detect this, a warning is taken and then checked.

The exhaust line 500 is connected to the bypass line 300, and is used to vent the compressed air filled in the inspection object 1 into the atmosphere after the leak inspection. The exhaust line 500 is provided with an exhaust valve 510 that is an on-off valve.

The controller 600 determines whether the inspection object 1 is leaked based on a flow rate value generated after the pressure balance time between the receiver tank 200 and the inspection object 1. If the detection amount from the mass flow meter 220 is zero or less than or equal to a preset value (a leak discrimination reference value, expressed as a leak flow rate), the control unit 600 determines that leak is not present because the airtightness of the inspection object 1 is complete. When the air flow is generated from the receiver tank 200 to the inspection object 1 and the amount of detection from the mass flow meter 220 is detected or more than a predetermined value, it is determined that a leak exists in the inspection object 1.

The control unit 600 controls to selectively turn on / off valves provided in the supply line 110, the pressure balancing line 210, and the bypass line 300, the dummy line 400, and the exhaust line 500, respectively. do. The first opening / closing valve 230, the second opening / closing valve 112, the bypass valve 310, the exhaust valve 510, and the like controlled by the controller 600 may open or close the flow line of air by an electrical signal. It is most preferable to use a solenoid valve.

The control unit 600 has a display unit 610 to visually check the detection amount checked from the mass flow meter 220. The display unit 610 of the controller 600 displays the detected flow rate, the leak flow rate, the leak detection time, the pressure equilibrium time, the vent time, the pressure reaching delay time, and the first and second open / close valves 230 and 112 and the bypass valve. An on / off state of the 310 and the exhaust valve 510 is displayed. And, it may include a warning light that is lit in accordance with the presence or absence of the leak determination of the inspection object (1).

Referring to the airtight test method in the airtight test apparatus of the present invention having the above-described configuration is as follows.

Figure 2 is a flow chart for explaining the airtight inspection method using the pressure balance according to the present invention, Figure 3 is a graph showing the pressure change of the receiver tank and the inspection object.

First, the airtightness inspection process is largely divided into compressed air storage step, pressure balance step (S100), flow rate detection step (S200), determination step (S300) and vent step (S400).

In the compressed air storage step, the compressed air generated by the air compressor 100 is stored in the receiver tank 200 through the supply line 110. The compressed air storage step is carried out only once in the initial stage of starting the inspection, and since that time, since enough compressed air is always stored in the receiver tank, it is omitted in the flowchart of FIG.

When the pressure balancing step (S100) is subdivided, it can be divided into a pressure moving step (S110), a pressure reaching time delay step (S120) and a stabilization step (S130).

In the pressure movement step (S110), the receiver tank 200 and the receiver valve 200 are opened by opening the first opening / closing valve 230 and the bypass valve 310 so that the compressed air stored in the receiver tank 200 is quickly provided to the inspection object 1. The pressure movement between the inspection object 1 is made. In particular, the reason for opening the second opening / closing valve 112 in the pressure movement step is to replenish the compressed air to the receiver tank by the amount of compressed air moved from the receiver tank 200 to the inspection object 1. In the pressure equalization step, the receiver tank 200 temporarily drops in pressure, but recovers to a reference pressure (supply pressure) before inspection as sufficient compressed air is replenished through the supply line 110.

4 is a graph showing a change in pressure of the receiver tank and the inspection object when the compressed air is not replenished in the receiver tank in the pressure movement step. As shown in Figure 4, the pressure of the receiver tank is dropped from the start point of the test to achieve the pressure balance of the test object. That is, if the receiver tank is not replenished with compressed air in the pressure movement step, the equilibrium pressure of the receiver tank and the inspection object is made at a pressure lower than the supply pressure.

The reason for replenishing the compressed air to the receiver tank in the pressure movement step, as shown in Figure 5a, in the state in which the receiver tank is filled with compressed air, the flow rate of the mass flow meter is exactly as the flow rate leaked from the inspection object Can be measured. However, in the state in which the compressed air of the receiver tank is not replenished as shown in FIG. 5B, the mass flow meter after pressure equilibrium does not accurately measure the leak flow rate 100% after a slight delay time. Of course, the lack of replenishment of compressed air in the receiver tank does not mean that the mass flowmeter cannot measure the flow rate leaked from the inspection object at all.

Pressure reaching delay step (S120) is a process that can be seen to be included in the pressure stabilization step (S130), but the control unit 600 will be described briefly this part by setting a delay time called the pressure reaching delay separately. In the pressure delay delay step S120, the bypass valve 310 and the second open / close valve 112 are blocked except the first open / close valve 230. The pressure arrival delay step may be set differently depending on the volume of the inspection object 1 and the characteristics of the internal space. For example, if the internal space of the inspection object is curved and complex structure (for example, an object such as a radiator), the time taken for compressed air to reach every corner of the interior space of the inspection object is relatively higher than that of a simple container type object. It takes Therefore, the additional time of the pressure arrival time according to the internal structure of the inspection object is to be set separately. However, the pressure delivery delay may be included in the pressure stabilization step (S130) as described above.

Pressure stabilization step (S130) is the time required for the pressure balance between the receiver tank 200 and the inspection object (1) to be stable.

As described above, in the present invention, since the leak inspection of the inspection object is performed using the compressed air stored in the receiver tank, the amount of change in the compressed air supplied to the receiver tank is not affected.

Flow detection step (S200) is for detecting the flow of the flow on the pressure balance line 210 after the pressure balance between the receiver tank 200 and the inspection object 1 is completely made, the mass installed in the pressure balance line 210 The flow meter 220 detects the flow rate and provides the detected amount to the control unit 600. For example, if there is a leak in the inspection object, the compressed air of the receiver tank having a large volume moves to the inspection object, and the mass flow meter 220 detects the moving flow rate.

The determination step (S300) determines whether the inspection object 1 is leaked according to the flow rate value generated after the pressure balance time between the receiver tank 200 and the inspection object 1. If the detected amount from the mass flow meter 220 is zero or less than or equal to the preset value (leak discrimination reference value, denoted as the leak flow rate), the controller 600 detects a good quality or a flow rate from the mass flow meter 220 or exceeds the preset value. It is determined that the leak is bad. The reason why the preset value (leak flow rate) is set here can be regarded as a reference value for determining the leak since fine leak can be determined as good quality according to the inspection object. However, if the test object should not be allowed to have a minute leak, the reference value is set to zero. After the controller 600 determines whether there is a leak, the result is displayed on the display unit 610.

After the determination step (S300), the inspection is completed by passing the vent step (S400) for shutting off the first opening / closing valve and opening the exhaust valve to vent the compressed air filled in the inspection object.

On the other hand, although not shown in the drawing, the second pressure gauge 30 connected to the inspection object 1 checks the internal pressure to check whether compressed air is provided to the inspection object 1 from the receiver tank 200 immediately before the flow rate detection step. The step of measuring and checking whether there is a blockage of the inspection object 1 may be added, and this process may or may not be applied depending on the inspection object.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

1 is a block diagram for explaining an airtight inspection apparatus using the pressure balance according to the present invention.

Figure 2 is a flow chart for explaining the airtight inspection method using the pressure balance according to the present invention.

3 is a graph showing the change in pressure of the receiver tank and the inspection object.

4 is a graph showing a change in pressure of the receiver tank and the inspection object when the compressed air is not replenished in the receiver tank in the pressure movement step.

5A is a view showing that the mass flow meter detects a flow rate leaking from an inspection object in a state where the receiver tank is filled with compressed air.

5B is a view showing that the mass flow meter detects the flow rate leaked from the inspection object in the state that the compressed air of the receiver tank is not replenished.

<Description of Symbols for Main Parts of Drawings>

100: air compressor 110: supply line

200: receiver tank 210: pressure balance line

220: mass flow meter 300: bypass line

400: dummy line 500: exhaust line

600: control unit

Claims (13)

In the air tightness tester using pressure balance: A receiver tank in which compressed air is stored;  A pressure balancing line connecting the receiver tank and the inspection object to achieve a pressure balance while providing the compressed air stored in the receiver tank to the inspection object; A mass flow meter installed on the pressure balance line to measure a flow rate of the compressed air moving from the receiver tank to the inspection object; A first opening / closing valve installed on the pressure balancing line; And And a control unit for displaying the flow rate of the compressed air detected by the mass flow meter and determining whether the inspection object is leaked according to the detection amount generated after the pressure balance time of the receiver tank and the inspection object. Inspection device. The method of claim 1, A bypass line branched from the pressure balancing line to provide compressed air stored in the receiver tank to the inspection object without passing through the mass flow meter and the first opening / closing valve, and a bypass valve installed in the bypass line. Leakage inspection device characterized in that it further comprises. The method according to claim 1 or 2, The receiver tank is characterized in that the volume of the receiver tank is larger than the volume of the inspection object. The method according to claim 1 or 2, And a dummy line branched between the mass flow meter and the first opening / closing valve and provided with a dummy valve having a certain amount of leakage. The method according to claim 1 or 2, An air compressor for compressing air; A supply line for supplying compressed air to the receiver tank through the air compressor; And The air tightness inspection device further comprises a pressure regulating valve and a second opening and closing valve installed on the supply line. The method according to claim 1 or 2, A first manometer for measuring the pressure of the receiver tank; A gas tightness inspection device further comprises a second pressure gauge for measuring the pressure of the inspection object. The method according to claim 1 or 2, And an exhaust line connected to the pressure balance line or the bypass line, the exhaust line having an exhaust valve for releasing compressed air filled in the inspection object into the atmosphere after the leak inspection. In the airtight inspection method of the inspection object using the air flow change: Storing compressed air in the receiver tank; A pressure balance step of achieving a pressure balance between the receiver tank and the inspection object by providing the compressed air stored in the receiver tank to the inspection object; Detecting an air flow rate through a mass flow meter to determine whether there is air movement from the receiver tank to the inspected object after the pressure balance between the receiver tank and the inspected object is achieved; And And a determining step of determining whether the inspection object is leaked according to a flow rate value generated after the pressure balance time of the receiver tank and the inspection object. The method of claim 8, The pressure balancing step A pressure movement step of opening a pressure balance line and a bypass line connecting the receiver tank and the inspection object so that the compressed air stored in the receiver tank is quickly provided to the inspection object; And And closing the bypass line to stabilize the pressure balance between the receiver tank and the inspection object. The method of claim 9, In the flow rate detection step The mass flow meter is installed in the pressure balance line, the airtight inspection method of the inspection object, characterized in that for detecting the flow rate moving through the pressure balance line. 10. The method according to claim 8 or 9, The determining step If the detection amount from the mass flow meter is zero or less than the preset value, it is determined that the leak is not present because the airtightness of the inspection object is complete, and the air flow is generated from the receiver tank to the inspection object, and the detection amount from the mass flow meter is detected. And if it is detected or equal to or more than a preset value, it is determined that leak exists in the inspection object. The method of claim 9, In the pressure movement step And supplying compressed air to the receiver tank to replenish the amount of compressed air moved to the inspection object. 10. The method according to claim 8 or 9, And checking the internal pressure of the inspection object to check whether there is a blockage of the inspection object to determine whether compressed air is provided to the inspection object from the receiver tank before the flow rate detecting step. Method of confidentiality inspection of the inspection object.

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