Internal leakage inspecting method and internal leakage inspecting device for liquid containers

Abstract

An inspection gas introduction pipe 2-6 for introducing an inspection gas 2-8 into a heat exchanger 1 and an inspection gas suction pipe 3-1 for vacuum-exhausting the inspection gas 2-8 are inserted hermetically into the heat exchanger 1. A small sealed space 2-6a of a fixed volume is formed by a first gas valve 2-4 and a second gas valve 2-5 midway along the inspection gas introduction pipe 2-6. It should be noted that the amount of accumulated gas accumulated in the small sealed space 2-6a is adjusted such that the amount of introduced gas is 1 / 10 or less of the internal volume of the heat exchanger 1 when converted to atmospheric pressure. Further, a refrigerant inlet 1-2 and a refrigerant outlet 1-3 communicate with each other by means of a pressure equalizing pipe 4-1 that is open to the atmosphere. The suction speed when vacuum-exhausting the refrigerant outlet 1-3 is set within a range of 1×10-8m3 / s to 1×10-5m3 / s.

Description

Method and apparatus for testing internal leaks in liquid containers

[0001] The present invention relates to a method and apparatus for testing internal leaks in liquid containers, and more specifically, to a method and apparatus for testing internal leaks in liquid containers having reciprocating channels separated by partitions, by introducing a certain amount of test gas necessary for testing into the liquid container to be tested, and forming a significant time difference that can be individually detected between "the time it takes for the test gas to travel through the short-circuit channel when it passes through a leak hole" and "the time it takes for the test gas to travel through the reciprocating channel when it passes through the reciprocating channel."

[0002] Heat exchangers 1 used in residential and industrial air conditioning systems and automobiles have reciprocating flow paths 1-6 separated by partitions 1-5 as shown in the schematic top view of Figure 1. In the heat exchanger 1, a refrigerant heated by a heat source flows in from the refrigerant inlet 1-2, and as this refrigerant flows through the reciprocating flow path 1-6 of the heat exchanger 1, it is cooled by air via the heat sink 1-9 shown in the schematic three-dimensional view of Figure 1, and flows back to the heat source from the refrigerant outlet 1-3, thereby cooling the heat source. Actual heat exchanger products are constructed by stacking multiple heat exchangers 1 in stages.

[0003] In this type of heat exchanger 1, the lower part of the housing 1-4 and the partition wall 1-5 are manufactured by integral molding, and the lower and upper parts of the housing 1-4 are brazed together. Furthermore, the housing 1-4 and the inlet / outlet joining jig 1-1 are joined by brazing. If there are defects due to poor brazing at these joints, refrigerant leakage or short circuits in the refrigerant reciprocating flow path 1-6 will occur, resulting in a deterioration of the performance of the heat exchanger 1.

[0004] Since the refrigerant leak occurring at the brazed joint between the inlet / outlet joint jig 1-1 of the heat exchanger 1 and the housing 1-4 is a leak from the inside to the outside of the heat exchanger 1, it is possible to perform a leak test using a pressure change leak test method, which detects leaks by pressurizing and sealing a gas inside and detecting the pressure change, or a leak test method using a test gas, which detects the test gas that leaks out to the outside using a gas analyzer. (See, for example, Non-Patent Document 1.)

[0005] On the other hand, if there is a leak hole 1-7 due to a faulty connection between the inlet / outlet joint jig 1-1 of the heat exchanger 1 and the partition wall 1-5, a short-circuit passage 1-8 is formed, and the refrigerant passes through the short-circuit passage 1-8 (internal leakage), which deteriorates the cooling performance of the heat exchanger 1. This internal leakage cannot be detected by the aforementioned leak test from the inside to the outside of the heat exchanger 1.

[0006] Inspection devices and methods for inspecting internal leakage due to short-circuit channels in a heat exchanger 1 having reciprocating channels 1-6 are disclosed in Patent Documents 1 and 2 below. According to Patent Document 1, a pressure wave, such as a sound wave, is introduced into the fluid (air) of the heat exchanger 1, and a pressure wave detector is installed at the refrigerant outlet 1-3. A time difference is created between the time it takes for the pressure wave to travel through the short-circuit channel 1-8 passing through the leak hole 1-7 and the time it takes for the pressure wave to travel through the reciprocating channel 1-6 of the heat exchanger. It is stated that internal leakage due to the short-circuit channel 1-8 can be detected from this time difference.

[0007] On the other hand, the leak detection device disclosed in Patent Document 2 is configured to introduce nitrogen gas, which is the carrier gas, and helium gas, which is the test gas, into a heat exchanger 1, guide these mixed gases to a helium leak detector, and measure the time T until the leakage flow rate of the helium gas, which is the test gas, reaches a threshold. That is, if there is a leak hole 1-7 in the partition wall, the leakage flow rate of the helium gas is affected by the helium gas flowing through the short-circuit passage 1-8 and reaches the threshold S Ｃ The measurement time T until it reaches the leak detection time T is equal to the measurement time T. Ｃ It becomes shorter. On the other hand, if there are no partition leak holes 1-7, the helium gas, which is the test gas, flows through the reciprocating flow path 1-6, so the helium gas leakage rate is less than the threshold S. Ｃ The measurement time T until it reaches the leak detection time T is equal to the measurement time T. Ｃ It becomes longer. Therefore, the measurement time T becomes the leak detection time T. Ｃ It is said that internal leakage due to leak holes 1-7 can be detected depending on whether the hole is longer or shorter.

[0008] Japanese Patent No. 3666209, Japanese Unexamined Patent Publication No. 2004-12386

[0009] Japanese Industrial Standard JIS Z 2330:2012 Nondestructive testing - Types and selection of leak testing methods

[0010] Using the technologies described in Patent Documents 1 and 2, it becomes possible to inspect internal leakage caused by a short-circuit channel 1-8 passing through a leak hole 1-7 resulting from a joint defect between the inlet / outlet joint jig 1-1 and the partition wall 1-5 of the heat exchanger 1. However, the technologies described in Patent Documents 1 and 2 have the following problems.

[0011] In Embodiment 1 of Patent Document 1, sound waves are introduced as pulse waves, and a time difference is created between the "travel time in the short-distance short-circuit channel 1-8" and the "travel time in the long-distance round-trip channel 1-6". By measuring this difference, it is possible to detect internal leakage due to the short-circuit channel 1-8. However, the speed of sound in air at room temperature is approximately 340 m / s, making it difficult to separately measure the "travel time in the short-distance short-circuit channel" and the "travel time in the long-distance round-trip channel". Furthermore, in this case, the sound waves are introduced as time pulse waves, and the release of the introduced sound waves is located downstream of the detector, so there is no mechanism to cancel the pressure of the sound waves, which are pressure waves, within the channel.

[0012] Furthermore, in Example 2 of Patent Document 1, in order to avoid the measurement difficulties of Example 1, sound waves are introduced continuously, and a difference in the frequency of the sound waves flowing through the short-distance short-circuit channel 1-8 and the long-distance reciprocating channel 1-6 occurs. By measuring this frequency, the internal leakage due to the short-distance short-circuit channel 1-8 is detected. In this case, since sound waves are introduced continuously, a pressure difference is created within the channel, and a gas (fluid) flow occurs due to this pressure difference.

[0013] Patent Document 2 describes a configuration in which a small amount of test gas 2-8 is introduced from a He tank to a heat exchanger 1 by instantaneously opening and closing a solenoid valve. Since the flow path cross-section is constant, the flow rate of the test gas 2-8 introduced depends on the pressure difference between the upstream and downstream sides of the solenoid valve. The opening and closing of the solenoid valve is instantaneous, but since the upstream side of the solenoid valve is always connected to the He tank, the pressure on the upstream side is stable. However, the pressure on the downstream side drops sharply at the moment the solenoid valve opens in an attempt to maintain the original pressure, and conversely, the pressure rises sharply at the moment the solenoid valve closes in an attempt to maintain the original pressure. In this way, the pressure on the downstream side becomes unstable when the solenoid valve opens and closes instantaneously, making it difficult to introduce a constant amount of test gas 2-8 required for inspection from the He tank to the heat exchanger 1 by opening and closing the solenoid valve. As a result, the leakage flow rate of the test gas 2-8 exceeds the threshold S. Ｃ It becomes difficult to reliably measure the measurement time T until the point is reached, and as a result, it may become impossible to detect internal leakage through the leak holes 1-7 based on the measurement time T.

[0014] Therefore, the present invention has been made in view of the problems of the prior art described above, and its purpose is to provide a liquid container internal leak inspection method and internal leak inspection apparatus that detects internal leaks in a liquid container having a reciprocating channel separated by a partition wall, by introducing a certain amount of inspection gas necessary for inspection into the liquid container to be inspected, and forming a significant time difference that can be individually detected between "the time it takes for the inspection gas to travel through the short-circuit channel when it passes through a leak hole" and "the time it takes for the inspection gas to travel through the reciprocating channel when it passes through the reciprocating channel."

[0015] The present invention provides an internal leak inspection method for a liquid container to achieve the above objective, comprising a housing (1-4) having a reciprocating flow path (1-6) separated by a partition wall (1-5), and a connecting end (1-1) having a liquid inlet (1-2) and a liquid outlet (1-3) for liquid to flow in and out, wherein the internal leak is detected due to a leak hole (1-7) in the partition wall (1-5), and the method involves detecting a certain amount of gas (Pam) accumulated in a small sealed space (2-6a) provided in the middle of the inspection gas introduction piping (2-6). ３Introduce the inspection gas (2-8) into the interior of the liquid container (1), and move the interior of the liquid container (1) by the gas diffusion phenomenon that makes the pressure difference between the liquid inlet (1-2) and the liquid outlet (1-3) zero. At the same time, while performing vacuum exhaust on the liquid outlet (1-3), the "short-circuit flow path movement time" in which the inspection gas (2-8) reaches the liquid outlet (1-3) from the liquid inlet (1-2) through the leakage hole (1-7), and the inspection gas (2-8) passes through the reciprocating flow path (1-6) from the liquid inlet (1-2) to reach the liquid outlet (1-3). By forming a significant time difference that can be individually detected between the "reciprocating flow path movement time", the internal leakage caused by the leakage hole (1-7) is detected.

[0016] In the above configuration, the inspection gas (2-8) moves inside the liquid container (1) due to the gas diffusion phenomenon that makes the pressure difference between the liquid inlet (1-2) and the liquid outlet (1-3) zero. As a result, it becomes possible to form a significant time difference that can be individually detected between the "short-circuit flow path movement time" and the "reciprocating flow path movement time".

[0017] Further, the inspection gas (2-8) introduced into the interior of the liquid container (1) is introduced from a small sealed space (2-6a) provided in the middle of the inspection gas introduction pipe (2-6). Therefore, regarding the "pressure increase near the liquid inlet (1-2) at the time of introducing the inspection gas (2-8)" that inhibits the gas diffusion phenomenon, the amount of gas (Pam ３ ) accumulated in the small sealed space (2-6a) can be adjusted to be suppressed within a range that does not prevent the formation of a significant time difference that can be individually detected between the "short-circuit flow path movement time" and the "reciprocating flow path movement time".

[0018] The second feature of the method for inspecting internal leakage of a liquid container according to the present invention is that the accumulated gas amount (Pam ３ ) of the inspection gas (2-8) accumulated in the small sealed space (2-6a) is the introduced gas amount (Pam ３ ) of the inspection gas (2-8) introduced into the interior of the liquid container (1), which is equivalent to a gas amount (Pam ３ less than or equal to 1 / 10 of the internal volume of the liquid container (1) in terms of atmospheric pressure conversion.The pressure is regulated to be such that )

[0019] In the above configuration, the "reciprocating flow time" of the test gas (2-8) due to the pressure rise near the liquid inlet (1-2) > the time duration related to the pressure rise (the time from closing to opening of the solenoid valve). In other words, the test gas (2-8) flowing through the reciprocating flow path (1-6) due to the pressure difference caused by the pressure rise transitions from movement due to the pressure difference to diffusion movement of the gas (movement due to diffusion phenomenon) with the pressure difference reduced to zero, as instantaneous introduction is completed midway through its movement. As a result, the pressure rise near the liquid inlet (1-2) during the instantaneous introduction of the test gas (2-8) can be suppressed to a range that does not hinder the formation of a significant time difference that can be individually detected between the "short-circuit flow time" and the "reciprocating flow time".

[0020] A third feature of the liquid container internal leak inspection method according to the present invention is that the suction speed when vacuuming the liquid outlet (1-3) is 1 × 10⁻⁶ －８ I understand ３ / s to 1 x 10 －５ I understand ３ It must be within the range of / s.

[0021] In the above configuration, the "short-circuit flow time" related to the diffusion phenomenon with zero pressure difference between the liquid inlet (1-2) and liquid outlet (1-3) of the test gas (2-8) is less than the "reciprocal flow time" related to the movement of the test gas (2-8) due to the pressure drop (pressure difference) near the liquid outlet (1-3). In other words, the test gas (2-8) flowing through the reciprocal flow path (1-6) due to the pressure difference between the liquid inlet (1-2) and liquid outlet (1-3) caused by the pressure drop due to the above suction velocity cannot catch up with the test gas (2-8) moving through the short-circuit flow path (1-8) due to the diffusion phenomenon with zero pressure difference between the liquid inlet (1-2) and liquid outlet (1-3). As a result, the pressure drop near the liquid outlet (1-3) during vacuum evacuation of the test gas (2-8) can be suppressed to a range that does not hinder the formation of a significant time difference that can be individually detected between the "short-circuit flow time" and the "reciprocal flow time".

[0022] A fourth feature of the liquid container internal leak inspection method according to the present invention is that the direction of introduction when introducing the inspection gas (2-8) accumulated in the small sealed space (2-6a) into the liquid container (1), and the direction of exhaust when vacuuming the inspection gas (2-8) from the inside of the liquid container (1), are in a direction directly facing the partition wall (1-5).

[0023] In the above configuration, the inspection gas (2-8) is preferentially drawn in by a diffusion phenomenon where the pressure difference between the liquid inlet (1-2) and the liquid outlet (1-3) is zero, due to a short-circuit passage (1-8) caused by a leak hole (1-7) in the partition wall (1-5). As a result, the "short-circuit passage travel time" becomes relatively shorter than the "round-trip passage travel time". This increases the time difference between the "short-circuit passage travel time" and the "round-trip passage travel time", making it more individually detectable and significant.

[0024] The liquid container internal leak inspection device according to the present invention for achieving the above objective is a liquid container (1) comprising a housing (1-4) having a reciprocating flow path (1-6) separated by a partition wall (1-5), and a connecting end (1-1) having a liquid inlet (1-2) and a liquid outlet (1-3) for liquid to flow in and out, and a liquid container internal leak inspection device (100, 200) for detecting internal leakage caused by a leak hole (1-7) in the partition wall (1-5), wherein the liquid container internal leak inspection device comprises a connecting jig (2-7) for airtight connection of piping to the connecting end (1-1), and a small sealed space (2-6a) of a certain volume in the middle, and an inspection gas ( The device comprises an inspection gas introduction pipe (2-6) for introducing the inspection gas (2-8) into the liquid container (1), an inspection gas suction pipe (3-1) for vacuuming the inspection gas (2-8) from the inside of the liquid container (1), an inspection gas detector (3-4) for detecting the inspection gas (2-8), and an equal-pressure pipe (4-1) connecting the liquid inlet (1-2) and the liquid outlet (1-3), wherein the inspection gas introduction pipe (2-6) has a first gas valve (2-4) and a second gas valve (2-5) that form the small sealed space (2-6a), and the equal-pressure pipe (4-1) has an atmospheric release valve (4-2) and a vacuum exhaust valve (4-3).

[0025] With the above configuration, the first feature of the liquid container internal leak inspection method can be suitably implemented.

[0026] A second feature of the internal leak inspection device for liquid containers according to the present invention is the amount of accumulated gas (Pam) of the inspection gas (2-8) accumulated in the small sealed space (2-6a). ３ ) is the amount of gas introduced (Pam) of the test gas (2-8) introduced into the liquid container (1). ３ ) is equivalent to 1 / 10 or less of the internal volume of the liquid container (1) when converted to atmospheric pressure (Pam ３ The pressure is regulated to be such that )

[0027] With the above configuration, the second feature of the liquid container internal leak inspection method can be suitably implemented.

[0028] A third feature of the internal leak inspection device for liquid containers according to the present invention is that the inspection gas detector (3-4) measures the liquid outlet (1-3) at 1 × 10 －８ I understand ３ / s to 1 x 10 －５ I understand ３ This involves vacuuming at a suction speed within the range of / s.

[0029] With the above configuration, the third feature of the liquid container internal leak inspection method can be suitably implemented.

[0030] A fourth feature of the internal leak testing device for liquid containers according to the present invention is that the discharge port of the test gas (2-8) of the test gas introduction pipe (2-6) and the suction port of the test gas (2-8) of the test gas suction pipe (3-1) are oriented in a direction directly facing the partition wall (1-5).

[0031] With the above configuration, the fourth feature of the liquid container internal leak inspection method can be suitably implemented.

[0032] According to the leak inspection method and leak inspection apparatus of the present invention, by introducing a certain amount of inspection gas necessary for inspection into the liquid container to be inspected, and by creating a significant time difference that can be individually detected between "the time it takes for the inspection gas to travel through the short-circuit path when it passes through the short-circuit path due to the leak hole" and "the time it takes for the inspection gas to travel through the reciprocating path when it passes through the reciprocating path," it becomes possible to detect internal leaks in a liquid container having a reciprocating path separated by a partition wall.

[0033] These are schematic top view and three-dimensional view diagrams of the heat exchanger that is the subject of inspection in the present invention. This is an explanatory diagram showing the main components of the leak inspection device according to the first embodiment of the present invention. This is a flow diagram of the leak inspection process using the leak inspection device according to the first embodiment of the present invention. This is an explanatory diagram showing the configuration of the outlet of the inspection gas introduction pipe and the inlet of the inspection gas suction pipe of the leak inspection device according to the first embodiment of the present invention. This is a graph of the measurement results of the leak inspection according to the first embodiment of the present invention. This is an explanatory diagram showing the configuration of the outlet of the inspection gas introduction pipe and the inlet of the inspection gas suction pipe of the leak inspection device according to the second embodiment of the present invention. This is a graph of the measurement results of the leak inspection third embodiment of the present invention.

[0034] The present invention will be described below with reference to the attached drawings.

[0035] (First Embodiment) Figure 2 is an explanatory diagram showing the main components of a leak inspection device 100 according to the first embodiment of the present invention. This leak inspection device 100 is configured to include an inspection gas introduction means 2, an inspection gas detection means 3, and an atmospheric release means 4 for a heat exchanger 1 having reciprocating flow paths 1-6 separated by partition walls 1-5. In this specification, pressure is absolute pressure. The amount of gas in the small sealed space 2-6a and inside the heat exchanger 1 is expressed as the pressure (Pa) and volume (m³) of the small sealed space 2-6a and the heat exchanger 1. ３ Using ) the amount of gas (Pam ３ ) = Pressure (Pa) × Volume (m³) ３ The expression is given as follows, but the temperature is assumed to be constant at room temperature. Each component will be explained further below.

[0036] The inspection gas introduction means 2 is a system for introducing a small amount of inspection gas 2-8 near a leak hole 1-7 caused by a joint defect between the inlet / outlet joint jig 1-1 and the partition wall 1-5 of the heat exchanger 1, which is the object under test. The pressure reducing valve 2-2 is installed to reduce the pressure of the inspection gas 2-8, which is compressed and filled into the inspection gas cylinder 2-1 under high pressure, to a certain pressure and introduce it into the piping (small sealed space 2-6a) between the first gas valve 2-4 and the second gas valve 2-5.

[0037] Pressure gauge 2-3 is installed to measure the pressure of the test gas 2-8 introduced into the piping between the pressure reducing valve 2-2 and the second gas valve 2-5.

[0038] The first gas valve 2-4 and the second gas valve 2-5 are installed to maintain a constant amount of the test gas 2-8 introduced into the heat exchanger 1.

[0039] The inspection gas introduction pipe 2-6 is installed to instantaneously introduce inspection gas 2-8 from the refrigerant inlet 1-2 of the heat exchanger 1 to the vicinity of the leak hole 1-7.

[0040] The connection jig 2-7 is a jig for installing the inspection gas introduction pipe 2-6 and the inspection gas suction pipe 3-1 near the leak hole 1-7, and is designed to be sealed (airtight) connected to the heat exchanger 1.

[0041] The inspection gas detection means 3 is a system for drawing in and detecting the inspection gas 2-8 introduced into the heat exchanger 1.

[0042] The inspection gas suction pipe 3-1 is installed to draw in the inspection gas 2-8 and air that have reached the vicinity of the leak hole 1-7 of the refrigerant outlet 1-3 of the heat exchanger 1.

[0043] The gas valve 3-2 is installed to introduce the inspection gas 2-8 into the inspection gas detector 3-4.

[0044] The flow control valve 3-3 is installed to adjust the suction speed of the test gas 2-8 and air introduced into the test gas detector 3-4. The test gas detector 3-4 is installed to detect the test gas 2-8.

[0045] The atmospheric release means 4 is a means to prevent a pressure increase near the refrigerant inlet 1-2 inside the heat exchanger 1 due to the instantaneous introduction of the inspection gas 2-8 by the inspection gas introduction means 2, and a pressure decrease near the refrigerant outlet 1-3 inside the heat exchanger 1 due to the vacuum exhaust of the inspection gas detector 3-4 while the inspection gas detection means 3 is detecting a leak.

[0046] The atmospheric release means 4 consists of an equal-pressure pipe 4-1, an atmospheric release valve 4-2, and a vacuum exhaust valve 4-3, and is attached to the refrigerant inlet 1-2 and refrigerant outlet 1-3 of the heat exchanger 1 via a connecting jig 2-7. The vacuum exhaust valve 4-3 is installed to dispose of the inspection gas 2-8 remaining in the inspection gas introduction pipe 2-6, the heat exchanger 1, and the inspection gas suction pipe 3-1 after the inspection is completed.

[0047] Figure 3 is a flowchart of the leak inspection process using the leak inspection device 100 according to the first embodiment of the present invention.

[0048] Step 1 is the installation of the test fixture. The test gas introduction pipe 2-6 and the test gas suction pipe 3-1 are installed near the leak holes 1-7 at the inlet and outlet of the heat exchanger 1 via the connecting fixture 2-7. The connecting fixture 2-7 is also sealed (airtight) to the inlet and outlet joining fixture 1-1 of the heat exchanger 1.

[0049] Step 2 is the preparation of the test gas 2-8 to be introduced into the heat exchanger 1, and involves accumulating (storing) the test gas 2-8 in the piping between the first gas valve 2-4 and the second gas valve 2-5 of the test gas introduction means 2. The piping from the test gas cylinder 2-1 to the first gas valve 2-4 is pre-filled with test gas 2-8 at a constant pressure. The piping from the first gas valve 2-4 to the second gas valve 2-5 is then evacuated after the test gas has been disposed of.

[0050] Step 2 is as follows: (1) Open the first gas valve 2-4 and introduce a test gas 2-8 at a constant pressure into the piping between the first gas valve 2-4 and the second gas valve 2-5. (2) After introducing the test gas, close the first gas valve 2-4 and accumulate the test gas 2-8 at a constant pressure in the space of the piping between the first gas valve 2-4 and the second gas valve 2-5.

[0051] In step 2, the amount of test gas 2-8 accumulated in the piping space between the first gas valve 2-4 and the second gas valve 2-5 (the amount of [pressure] × [volume] in the piping space between the first gas valve 2-4 and the second gas valve 2-5 (small sealed space 2-6a)) is adjusted by changing the [pressure] of the small sealed space 2-6a according to the amount of test gas 2-8 introduced into the heat exchanger 1. The [pressure] for accumulating the test gas 2-8 will henceforth be referred to as [accumulation pressure]. The amount of test gas 2-8 accumulated in the small sealed space 2-6a at that [accumulation pressure] will henceforth be referred to as [accumulated gas amount].

[0052] Step 3 is the process of introducing the test gas 2-8 into the heat exchanger 1. The test gas 2-8 accumulated in the piping of the small sealed space 2-6a between the first gas valve 2-4 and the second gas valve 2-5 is instantaneously introduced near the leak hole 1-7 that has occurred at the joint between the inlet / outlet joint jig 1-1 and the partition wall 1-5 inside the heat exchanger 1 by opening the second gas valve 2-5. Here, it is necessary to avoid a slight pressure rise near the refrigerant inlet 1-2 inside the heat exchanger 1 due to the instantaneous introduction of the test gas 2-8. From the theoretical verification described later, it is found that it is desirable to set the amount of test gas 2-8 introduced into the heat exchanger 1 (amount of ([accumulated pressure] - [atmospheric pressure]) × [space volume] in the small sealed space 2-6a) to 1 / 10 or less of the amount of air gas inside the heat exchanger 1 (amount of [atmospheric pressure] × [internal volume of heat exchanger 1]). In the following, the amount of test gas 2-8 introduced into heat exchanger 1 will be referred to as [introduced gas amount].

[0053] Step 4 is the detection step for the test gas 2-8. Simultaneously with the introduction of the test gas 2-8 into the heat exchanger 1 in step 3, the gas valve 3-2 is opened, and the test gas 2-8 and air drawn in from the test gas suction pipe 3-1 are passed through the flow control valve 3-3 and introduced into the test gas detector 3-4 to detect the test gas 2-8. Here, it is necessary to avoid a slight pressure drop near the refrigerant outlet inside the heat exchanger 1 due to the suction of the test gas 2-8 and air from the test gas suction pipe 3-1. From the theoretical verification described later, in order to reduce the suction speed of the drawn-in test gas and air, the suction speed of the test gas 2-8 and air at the inlet of the test gas suction pipe 3-1 by the test gas detector 3-4 is set to 1 × 10⁻⁶ －８ I understand ３ / s to 1 x 10－５ I understand ３ It is desirable to set it within the range of / s.

[0054] During the instantaneous introduction of the inspection gas 2-8 in step 3 and the suction of the inspection gas 2-8 and air via the inspection gas suction pipe 3-1 for detection of the inspection gas 2-8 in step 4, the atmospheric release valve 4-2 of the atmospheric release means 4, which is installed via a connecting jig 2-7 at the positions of the refrigerant inlet 1-2 and refrigerant outlet 1-3 of the heat exchanger 1, is opened, and the inside of the heat exchanger 1 is opened to the atmosphere via the equal-pressure pipe 4-1. This brings the inside of the heat exchanger 1 to an atmospheric pressure state, compensating for the movement of the inspection gas 2-8 due to diffusion. Note that atmospheric release by the atmospheric release means 4 is carried out from the stage of step 1.

[0055] By going through steps 1 to 4, the internal pressure of the heat exchanger 1 becomes approximately atmospheric pressure during the time domain in which gas is detected. Therefore, the test gas 2-8 introduced near the leak hole 1-7 moves inside the heat exchanger 1 by diffusion. At this time, a significantly large time difference can be created between "the time it takes for the test gas 2-8 introduced from the test gas introduction pipe 2-6 installed at the refrigerant inlet 1-2 of the heat exchanger 1 to pass through the short-circuit path 1-8 caused by the leak hole 1-7 and reach the test gas suction pipe 3-1 installed at the refrigerant outlet 1-3 (short-distance gas movement time)" and "the time it takes for the test gas 2-8 introduced from the test gas introduction pipe 2-6 installed at the refrigerant inlet 1-2 to pass through the return-and-forth path 1-6 and reach the test gas suction pipe 3-1 installed at the refrigerant outlet 1-3 (long-distance gas movement time)," making it possible to detect internal leakage due to the leak hole 1-7.

[0056] Step 5 involves removing the remaining inspection gas 2-8 inside the inspection gas introduction pipe 2-6 downstream of the first gas valve 2-4, inside the heat exchanger 1, and inside the inspection gas suction pipe 3-1 upstream of the gas valve 3-2 of the inspection gas detection means 3 by opening the vacuum exhaust valve 4-3 and evacuating the system. Next, the vacuum exhaust valve 4-3 is closed and the atmospheric release valve 4-2 is opened to introduce air into the evacuated space and return it to atmospheric conditions. Theoretical verification of the present invention

[0057] In this invention, in order to create a significant time difference between the time it takes for the test gas to travel from the refrigerant inlet 1-2 through the leak hole 1-7 to the refrigerant outlet 1-3 (short-circuit movement time) and the time it takes for the test gas to travel from the refrigerant inlet 1-2 through the reciprocating flow path 1-6 to the refrigerant outlet 1-3 (reciprocating flow path movement time) inside a heat exchanger 1 filled with air at atmospheric pressure, the invention devised to move the test gas 2-8 by diffusion by performing a small amount introduction of the test gas 2-8, a small amount of the test gas 2-8 and air aspirator, and atmospheric release by atmospheric release means 4.

[0058] Therefore, we theoretically verified the travel time of the test gas 2-8 in the short-circuit path and the travel time in the round-trip path, specifically the travel time of the test gas 2-8 when there is a constant pressure difference and the gas is flowing, and the travel time of the test gas 2-8 when there is no pressure difference and the gas is diffusing. The theoretical verification was carried out as follows.

[0059] The dimensions of the heat exchanger 1 are as follows: the flow path width of the reciprocating flow paths 1-6 is 5.0 × 10 －２ m, channel height 3.0 × 10 －３ Let m be the diameter of the leak holes 1-7, which are 5.0 × 10 －４ m, length 2.0 × 10 －３ The value was set to m. The length of the reciprocating flow path was then used as a parameter and varied within the range of 0.4 m to 10 m.

[0060] In the theoretical verification, the time it takes for test gas 2-8 to move from refrigerant inlet 1-2 to refrigerant outlet 1-3 was calculated. In this theoretical verification, calculations were performed under two conditions: one where there is a constant pressure difference between refrigerant inlet 1-2 and refrigerant outlet 1-3, causing the test gas 2-8 to move due to gas flow; and another where there is no pressure difference between refrigerant inlet 1-2 and refrigerant outlet 1-3, causing the test gas 2-8 to move due to diffusion. In the calculations under both conditions, the flowing gas was assumed to be air present in the heat exchanger (average molecular weight 28.8), and the temperature was assumed to be room temperature of 20°C.

[0061] This section explains the calculation method and results for the travel time of test gas 2-8 when there is a constant pressure difference and gas is flowing.

[0062] When there is a pressure difference in a certain flow path and a gas flows through it, the following equation (1) holds true. Formula 1

[0063] [Average pressure in the flow path (Pa)] × [Volume of the flow path (m³)] ３ )] = [Flow rate of gas flowing through the channel (Pam ３ / s)] × [Travel time (s)] (1)

[0064] In equation (1), the average pressure of the flow path (Pa) was calculated by setting the inlet pressure of the flow path (pressure at refrigerant inlets 1-2) to atmospheric pressure and the outlet pressure of the flow path (pressure at refrigerant outlets 1-3) to a value less than atmospheric pressure as appropriate. [Volume of the flow path (m³) ３ The following was calculated from the geometric size of the heat exchanger 1 for the case where the gas flows through the reciprocating flow path 1-6 and the case where it flows through the short-circuit flow path 1-8. [Flow rate of gas flowing through the flow path (Pam ３ The calculation for the flow rate ( / s) was performed using the modified Knudsen equation, assuming air as the flowing gas, and using the inlet pressure, outlet pressure, and the geometric size of the heat exchanger 1 as parameters. Here, the modified Knudsen equation is a gas flow rate calculation formula applicable to all flow regions, including molecular flow, intermediate flow, viscous flow, turbulent flow, critical flow, and subcritical flow. (Reference: Surface and Vacuum Vol. 63, No. 7, pp. 373-380, 2020)

[0065] As described above, by setting appropriate parameters such as the inlet pressure, outlet pressure, and geometric size of the heat exchanger 1, the following equations are used: [Average pressure of the flow path (Pa)], [Volume of the flow path (m³)] ３ )], [Flow rate of gas flowing through the channel (Pam ３ The values ​​for [travel time (s)] were calculated, and from these, the travel time (s) was calculated.

[0066] Table 1 shows the lengths of the reciprocating flow paths 1-6 of the heat exchanger 1 as 0.4 m, 1 m, 2 m, 4 m, and 10 m, and the pressure difference between the refrigerant inlet 1-2 and the refrigerant outlet 1-3 as 1 Pa, 5 Pa, and 1 × 10⁻¹⁰ m. １ Pa, 5 x 10 １ Pa, 1 × 10 ２ Pa, 5 x 10 ２ Pa, 1 × 10 ３ Pa, 5 x 10 ３ Pa, 1 × 10 ４This document presents the results of calculating the travel time of the test gas 2-8 when it passes through the reciprocating path 1-6 (reciprocating path travel time) and when it passes through the short-circuit path 1-8 (short-circuit path travel time) when the pressure is Pa, as well as the results of determining whether the test gas 2-8 that has traveled through each path can be individually detected. Here, the determination of whether individual detection is possible was made when the reciprocating path travel time was 1 s or more. This is because, in actual leak testing measurements, the signal of the test gas 2-8 moving through the reciprocating path 1-6 and the signal of the test gas 2-8 moving through the short-circuit path 1-8 have a time width, so a time difference of about 1 s or more is required between the reciprocating path travel time and the short-circuit path travel time.

[0067] Table 1 shows that when the reciprocating flow path length is 0.4 m, individual detection is possible only when the pressure difference is 1 Pa, and when the pressure difference is 5 Pa or more, the reciprocating flow path travel time becomes less than 1 s, making individual detection impossible. On the other hand, when the reciprocating flow path length is 10 m, the pressure difference is from 1 Pa to 1 × 10⁻¹⁰ ３ Individual detection is possible in the case of Pa, and the pressure difference is 5 × 10 ３ Individual detection became impossible at Pa levels and above.

[0068] In other words, when there is a pressure difference and gas is flowing, the reciprocating flow path length increases and the reciprocating flow time increases, resulting in a significant time difference with the short-circuit flow time. On the other hand, when the reciprocating flow path length is short, the reciprocating flow time is short, so a significant time difference with the short-circuit flow time occurred only when the pressure difference was small. This suggests that when there is a pressure difference and gas is flowing, there is a limit to the pressure difference required to perform an internal leak test. From the results in Table 1, the pressure difference between the inlet pressure (pressure at refrigerant inlet 1-2) and the outlet pressure (pressure at refrigerant outlet 1-3) of heat exchanger 1 is 1 × 10⁻⁶ ３ It can be said that a pressure of 1 Pa or less is necessary. Furthermore, it can be seen that the pressure at which internal leakage testing is possible along the entire length of the reciprocating flow path is 1 Pa or less.

[0069] We consider the reciprocating flow path length when a gas flows with a pressure difference. From the results in Table 1, when the reciprocating flow path length is 0.4 m, the reciprocating flow path travel time is 3.47 s with a pressure difference of 1 Pa, so a reciprocating flow path length of approximately 0.4 m or more is necessary. Expressed as reciprocating flow path length / flow path width, this can be expressed as reciprocating flow path length / flow path width = 8 (= 0.4 m / 5 × 10) －２ m or more is required.

[0070] Based on the theoretical verification above, when there is a constant pressure difference and gas is flowing, the pressure difference is 1 × 10⁻⁶ ３ For pressures below Pa, the reciprocating channel length / channel width must be 8 or greater. In this analysis, the channel width of reciprocating channels 1-6 is set to 5.0 × 10⁻⁶. －２ m, channel height 3.0 × 10 －３ Let m be the length of the reciprocating flow path, and set to 0.4 m to 10 m. Generally, in heat exchanger 1, the flow path height is 1.0 × 10 －３ m to 5.0 × 10 －３ Since the length of the reciprocating flow path and the width of the flow path are often set in the range of 20 to 200, the above theoretical verification can be extended and applied to heat exchangers 1 of different geometric sizes.

[0071] Next, we will explain the calculation method and results for the movement time of test gas 2-8 when there is no pressure difference and the gas moves due to diffusion.

[0072] According to the one-dimensional diffusion equation, at t=0, N is located at x=0. ０ If we place a number of gases, the number of gases n(x,t) at a distance x from x=0 at time t can be expressed by the following equation (2). Formula 2

[0073] n(x,t)=[(N ０ / (2(πDt) ０．５ ) ] × EXP [ - (x ２ / (4Dt))) (2) Here, D is the diffusion coefficient of the gas.

[0074] Using equation (2), the travel time of test gas 2-8 was determined as follows.

[0075] The dimensions of heat exchanger 1 are the same as when there is a pressure difference and gas is flowing, with the flow path width of the reciprocating flow paths 1-6 being 5.0 × 10 －２ m, channel height 3.0 × 10 －３ Let m be the diameter of the leak holes 1-7, which are 5.0 × 10 －４ m, length 2.0 × 10 －３ The value was set to m. The reciprocating flow path length was then used as a parameter and varied within the range of 0.4 m to 10 m. The gas placed at position x = 0 was designated as test gas 2-8, and the number of test gases N ０ The number of air molecules inside each heat exchanger 1 was set to 1 / 100 of the total number of air molecules present inside each heat exchanger 1. Then, the number of test gases n(x,t) at a distance x at time t when the test gas 2-8 moves through the reciprocating flow path 1-6, and the number of test gases n(x,t) at a distance x at time t when the test gas 2-8 moves through the short-circuit flow path 1-8 were calculated from equation (2). Here, when the test gas 2-8 moves through the reciprocating flow path 1-6, the distance x is set to the length of the reciprocating flow path, and when the test gas 2-8 moves through the short-circuit flow path 1-8, the distance x is set to 5.0 × 10⁻⁶. －２ The distance was set to m (the distance from the outlet of the inspection gas introduction pipe 2-6 to the leak hole 1-7 and then to the inlet of the inspection gas suction pipe 3-1). Furthermore, since the number of gas molecules moving differs depending on whether they move through the reciprocating flow path 1-6 or the short-circuit flow path 1-8, the probability of movement was calculated from the ratio of the cross-sectional area of ​​the reciprocating flow path 1-6 (flow path width × flow path height) to the cross-sectional area of ​​the leak hole 1-7 in the short-circuit flow path 1-8. The diffusion coefficient D was calculated using the helium gas diffusion coefficient D = 5.31 × 10⁻¹⁰, where the inspection gas 2-8 is helium gas and the intrinsic gas is air. －５ I understand ２ I used / s.

[0076] There are two cases: when the test gas 2-8 diffuses through the reciprocating flow path 1-6, and when the test gas diffuses through the short-circuit flow path 1-8. The number of test gases n(x,t) at distance x at time t calculated from equation (2) and the number of air units originally inside the heat exchanger 1 (100N) ０ Therefore, the concentration of test gas 2-8 at position x at time t is (= n / (N) ０ The values ​​for +n) were calculated respectively. The time at which the calculated concentration of test gas 2-8 reached a concentration that could be measured by the test gas detector 3-4 was defined as the round-trip flow time and the short-circuit flow time.

[0077] Table 2 shows the calculated travel time (reciprocating path travel time) when the test gas 2-8 moves by diffusion through the reciprocating path 1-6 and through the short-circuit path 1-8, respectively, when the lengths of the reciprocating paths 1-6 are 0.4 m, 1 m, 2 m, 4 m, and 10 m. It also shows the results of determining whether the test gas 2-8 that has moved through each path can be individually detected. Here, individual detection was determined when the reciprocating path travel time was 100 s or more. This is because when a gas moves by diffusion, the signal of the test gas 2-8 used in leak testing measurements has a wide time window.

[0078] Focusing on the round-trip flow time, when the round-trip flow length is 0.4 m, the round-trip flow time is 1.18 × 10⁻⁶. ２ When the reciprocating flow path length is 10m, the reciprocating flow path travel time is 3.40 × 10 ５ The time was s. In other words, it can be seen that when the test gas 2-8 moves by diffusion through the reciprocating flow path, it takes a long time of more than 100 s. On the other hand, when it moves through the short-circuit flow path, the travel distance is 5.0 × 10 －２ Given the relatively short distance of m, it can be seen that the short-circuit flow time is a short 1.7 s.

[0079] From the above, it can be seen that when the test gas 2-8 moves by diffusion, a large time difference occurs between the travel time in the round-trip path and the travel time in the short-circuit path at all round-trip path lengths from 0.4 m to 10 m, making individual detection possible.

[0080] In the leak testing method of the present invention, the inside of the heat exchanger 1 is opened to the atmosphere using the atmospheric release means 4. When the test gas 2-8 is instantaneously introduced near the refrigerant inlet of the heat exchanger 1, the internal pressure of the heat exchanger 1 rises slightly instantaneously. On the other hand, when a leak is detected, the test gas 2-8 and air are drawn in from the test gas suction pipe 3-1, so it is thought that the pressure near the refrigerant outlet 1-3 of the heat exchanger 1 drops slightly. We will consider these instantaneous pressure rises near the refrigerant inlet 1-2 and pressure drops near the refrigerant outlet 1-3.

[0081] First, we will consider the limitation (allowable pressure rise value) of the pressure rise near the refrigerant inlet 1-2 due to the instantaneous introduction of inspection gas 2-8 using inspection gas introduction means 2. The instantaneous introduction time of inspection gas 2-8 by inspection gas introduction means 2 is approximately 0.1 s or less. This is because, when introducing inspection gas 2-8, the second gas valve 2-5 is opened from closed, and when an electromagnetic valve is used, the valve opening and closing operation time is several tens of milliseconds. If the opening and closing time of the second gas valve 2-5 is assumed to be 0.1 s, this 0.1 s period will cause a pressure rise near the refrigerant inlet 1-2 inside the heat exchanger 1. As a result, a pressure difference will be created between the refrigerant inlet 1-2 and the refrigerant outlet 1-3.

[0082] Focusing on the reciprocating flow time in Table 1, the pressure rise near the refrigerant inlet 1-2 due to the instantaneous introduction of test gas 2-8 corresponds to the pressure difference along the reciprocating flow path length. The allowable pressure rise value is equivalent to the maximum pressure difference when the reciprocating flow time of test gas 2-8 is longer than the valve opening / closing time (= 0.1 s). From Table 1, in heat exchanger 1 with a reciprocating flow path length of 10 m, the pressure difference = 1 × 10 ４ The round-trip flow time at Pa is 4.08 × 10⁻⁶. －１ The value is s, which is longer than the valve opening / closing time of 0.1 s. Therefore, the allowable pressure rise value for test gas 2-8 is 1 × 10⁻⁶. ４ It becomes Pa.

[0083] From here on, the amount of test gas 2-8 introduced into the small sealed space 2-6a to be introduced into the heat exchanger 1 (([storage pressure] - [atmospheric pressure]) × [space volume]) must be 1 / 10 or less of the pressure (atmospheric pressure) × internal volume inside the heat exchanger 1. It should be added that, for the time after the instantaneous introduction of test gas 2-8 (0.1 s), the area near the refrigerant inlet 1-2 will be at atmospheric pressure inside the heat exchanger 1 due to the atmospheric release means 4.

[0084] Next, we consider limiting the pressure drop near the refrigerant outlet 1-3 due to the suction of inspection gas 2-8 and air using the inspection gas detection means 3, and estimate the maximum allowable suction speed of the inspection gas detection means 3. Based on the above considerations, the allowable pressure rise due to the instantaneous introduction of inspection gas 2-8 for approximately 0.1 s is 1 × 10⁻⁶. ４It was Pa. On the other hand, the inspection gas detection means 3 always sucks the inspection gas 2-8 and air within the time of detecting the inspection gas 2-8. If this always-sucking time is taken as the short-circuit flow path movement time of the inspection gas 2-8, it was 1.7 s from Table 2. The gas that has moved through the reciprocating flow path 1-6 within this 1.7 s must not reach the refrigerant outlet.

[0085] According to the results of the movement time when there is a pressure difference in Table 1, at a reciprocating flow path length of 10 m and 1×10 ３ Pa, the reciprocating flow path movement time is longer than 2.82 s and 1.7 s. Therefore, the allowable pressure drop value ΔP' due to the suction of the inspection gas 2-8 and air is considered to be 1×10 ３ Pa. When this is converted to the reduction in the internal volume of the heat exchanger 1 with a reciprocating flow path length of 10 m, the internal volume V １ of this heat exchanger 1 is 1.5×10 －３ m ３ Therefore, the allowable volume reduction amount is 1.5×10 －５ m ３ (= V1×ΔP' / P ０ = 1.5×10 －３ m ３ × 1×10 ３ Pa / 1×10 ５ Pa). Assuming that the volume is reduced by suction during the 1.7 s of the short-circuit flow path movement time of the inspection gas 2-8, the allowable maximum volume reduction rate, that is, the allowable maximum suction rate, is 8.82×10 －６ m ３ / s (= 1.5×10 －５ m ３ / 1.7 s). In addition, in the present invention, it is noted that since the atmosphere release means 4 is used and the atmosphere is always released during the leak inspection, the above large pressure drop does not occur.

[0086] When the suction speed of the inspection gas detection means 3 decreases, the flow rate of the inspection gas 2-8 in the inspection gas detector 3-4 decreases, making detection difficult. Therefore, the concentration of the inspection gas 2-8 in the inspection gas detector 3-4 when the suction speed is changed is calculated, and a determination is made as to whether leakage can be detected, and the minimum allowable suction speed at which leakage detection is possible is estimated. In the calculation, the introduced gas amount of the inspection gas 2-8 to be introduced is set to the internal pressure (atmospheric pressure) of the heat exchanger 1, which is the upper limit amount that can be introduced, multiplied by 1 / 10 of the internal volume. This amount of inspection gas 2-8 is introduced near the refrigerant inlet 1-2, and the suction speed is reduced from 1×10 －５ m ３ / s. When the inspection gas 2-8 moves through the reciprocating flow path 1-6 and when it moves through the short-circuit flow path 1-8 are considered as two cases, and the time change of the concentration of the inspection gas 2-8 at the refrigerant outlet 1-3 is calculated using the formula (2). Then, it is determined whether the calculated concentration of the inspection gas 2-8 can be detected by the inspection gas detector 3-4. As a result, in the heat exchanger 1 having a reciprocating flow path length in the range of 0.4 m to 10 m, the minimum allowable suction speed was determined to be 1×10 －８ m ３ / s.

[0087] From the above consideration of the suction speed by the inspection gas detection means 3, it was found that it is desirable to set the suction speed in the range of 1×10 －８ m ３ / s to 1×10 －５ m ３ / s.

[0088] (First Embodiment of the Present Invention) The first embodiment of the present invention measures both the inspection gas 2-8 passing through the short-circuit flow path 1-8 due to the leakage hole 1-7 of the heat exchanger 1 and the inspection gas 2-8 passing through the reciprocating flow path 1-6. The first embodiment was carried out as follows.

[0089] The heat exchanger 1 was prepared with a flow path width of 5.0×10 －２ m × a reciprocating flow path length of 2 m × a height of 3.0×10 －３ m and an internal volume of 3.0×10 －４ m ３ . At the joint of the inlet / outlet joining jig 1-1 (length 3.0×10 －２ m) and the partition wall 1-5, a diameter of 5.0×10 －４ m · a length of 2×10 －３A leak hole 1-7 of length m was created. Here, the leak hole 1-7 was created by pre-damaging the partition wall 1-5. Tap water (water pressure 3.0 × 10) was then introduced into the heat exchanger 1 having this leak hole 1-7. ５ When Pa) is flowed, the flow rate ratio of water flowing through the leak holes 1-7 (100 × [flow rate of water flowing through leak holes 1-7] / ([flow rate of water flowing through the reciprocating flow path 1-6] + [flow rate of water flowing through leak holes 1-7]) is 2%, and the deterioration of the cooling capacity of the heat exchanger 1 is sufficiently small.

[0090] In this invention, as shown in Figure 2, the inspection gas introduction pipe 2-6 of the inspection gas introduction means 2, the inspection gas suction pipe 3-1 of the inspection gas detection means 3, and the isobaric pipe 4-1 of the atmospheric release means 4 need to be installed on the refrigerant inlet 1-2 and refrigerant outlet 1-3 of the heat exchanger 1 via a connecting jig 2-7. As shown in the three-dimensional schematic diagram in Figure 1, the refrigerant inlet 1-2 and refrigerant outlet 1-3 of the heat exchanger 1 each have two ports. Therefore, the inspection gas introduction pipe 2-6 is installed on one port of the refrigerant inlet 1-3, the inspection gas suction pipe 3-1 is installed on one port of the refrigerant outlet 1-3, and the atmospheric release isobaric pipe 4-1 is installed on the other port of the refrigerant inlet 1-3 and the other port of the refrigerant outlet 1-3.

[0091] Regarding the piping of the inspection gas introduction means 2, the piping from the pressure reducing valve 2-2 to the first gas valve 2-4 has an outer diameter of 6.35 × 10 －３ m / inner diameter 4.93 x 10 －３ The length was set to 3m. The piping between the first gas valve 2-4 and the second gas valve 2-5, which store the inspection gas 2-8, has an outer diameter of 6.35 x 10 －３ m ・Inner diameter 4.93×10 －３ m, length 3.66 x 10 －１ m・inner volume 7.0×10 －６ I understand ３ Furthermore, the inspection gas introduction pipe 2-6 downstream of the second gas valve 2-5 has an outer diameter of 1.58 x 10 －３ m・Inner diameter 5.60×10 －４ m, length 2.0 x 10 －１ m and internal volume 4.9 × 10 －８ I understand ３ This resulted in an extremely small volume.

[0092] Regarding the inspection gas suction pipe 3-1 of the inspection gas detection means 3, the outer diameter from the inlet of the suction pipe 3-1 to the gas valve 3-2 is 1.58 × 10 －３ m・Inner diameter 5.60×10 －４ m, length 2.0 x 10 －１ The length was set to m. The piping from gas valve 3-2 to flow control valve 3-3 has an outer diameter of 6.35 x 10 －３ m・Inner diameter 4.93×10 －３ m, length 2.0 x 10 －１ The distance from the flow control valve 3-3 to the inspection gas detector 3-4 is 2.35 × 10 －２ The connections were made using a 3m long flexible tube.

[0093] The flow rate control valve 3-3 of the inspection gas detection means 3 determines the suction speed, and therefore has a valve conductance of 1 × 10 －８ I understand ３ / s to 1 x 10 －５ I understand ３ A flow control valve that can be changed in / s was used.

[0094] In this first embodiment, helium gas was used as the inspection gas 2-8, and a helium leak detector was used as the inspection gas detector 3-4 of the inspection gas detection means 3.

[0095] The isobaric piping 4-1 of the atmospheric release means 4 has an outer diameter of 6.35 × 10 －３ m・Inner diameter 4.93×10 －３ A relatively thick pipe of m was used.

[0096] As shown in Figure 4, in the first embodiment, the outlet of the inspection gas introduction pipe 2-6 is positioned directly opposite the cross-section of the reciprocating flow path 1-6, which has a flow path width × flow path height, and the inspection gas 2-8 is introduced along the flow direction of the reciprocating flow path. The inlet of the inspection gas suction pipe is also positioned directly opposite the cross-section of the reciprocating flow path 1-6, which has a flow path width × flow path height.

[0097] Using the inventive apparatus configured as described above, 7.0 × 10⁻¹⁶ units of atmospheric pressure are applied inside the heat exchanger 1. －１ Pam ３ (Pressure × Volume = (1.0 × 10) ５ Pa)×(7.0×10 －６ I understand ３) = 7.0 × 10 －１ Pam ３ To introduce the inspection gas 2-8, the accumulated pressure × volume of the inspection gas 2-8 (helium gas) accumulated in the small sealed space 2-6a between the first gas valve 2-4 and the second gas valve 2-5 is calculated as (2.0 × 10⁻¹⁰ ５ Pa)×(7.0×10 －６ I understand ３ ) = 1.4 × 10 ０ Pam ３ The valve conductance of flow control valve 3-3 is set to 5 × 10 －７ I understand ３ The leak inspection process from step 1 to step 5 described in Figure 3 was performed with the speed fixed at / s. Here, the atmospheric release valve 4-2 of the atmospheric release means 4 was kept open from the introduction of the inspection gas 2-8 in step 3 to the detection of the inspection gas in step 4.

[0098] Figure 5 shows the measurement results of the test gas 2-8 in the first embodiment. The horizontal axis represents time, and the vertical axis represents the leakage flow rate of the test gas 2-8 (helium gas) detected by the gas detector 3-5 (helium leak detector).

[0099] The sharp peak signal that appears immediately after time 0s is due to the test gas 2-8 (helium gas) passing through the short-circuit channel 1-8. This sharp peak signal is caused by a pressure difference being created between the refrigerant inlet 1-2 and the refrigerant outlet 1-3 when the test gas 2-8 is instantaneously introduced, and this pressure difference causes gas to flow inside the heat exchanger 1, albeit momentarily.

[0100] The signal of the test gas 2-8 passing through this short-circuit channel 1-8 shows a sharp peak signal, which then gradually decreases over a period of about 200 seconds. This is because the test gas 2-8 introduced after instantaneous introduction moves due to diffusion.

[0101] On the other hand, the signal for test gas 2-8 increases from time 300 s, peaks around time 500 s, and then decreases. This broad-spectrum signal is caused by test gas 2-8 passing through the reciprocating channel 1-6. When test gas 2-8 is instantaneously introduced, gas moves in the reciprocating channel due to the pressure difference between the refrigerant inlet 1-2 and the refrigerant outlet 1-3, but thereafter, gas moves due to diffusion, resulting in a broad-spectrum signal.

[0102] From the above results, it can be seen that there is a time difference of 500 seconds between the time it takes for the test gas 2-8 to pass through the short-circuit channel 1-8 and the time it takes to pass through the reciprocating channel 1-6. This time difference of several hundred seconds is more than 10 times greater than the time difference of several tens of seconds that occurs when gas flows due to a pressure difference. In other words, in the first embodiment, by utilizing the diffusion phenomenon, it is possible to create a time difference of several hundred seconds between the time it takes for the test gas 2-8 to travel through the short-circuit channel 1-8 and the time it takes for the test gas 2-8 to travel through the reciprocating channel 1-6, making it possible to clearly separate the passage times of the two channels. Second Embodiment of the Invention

[0103] A second embodiment of the present invention increases the signal of the test gas 2-8 passing through the short-circuit channel 1-8 formed by the leak hole 1-7 of the heat exchanger 1 of the first embodiment. The second embodiment was carried out as follows.

[0104] In the second embodiment, the difference from the first embodiment is that, as shown in Figure 6, the discharge port of the inspection gas introduction pipe 2-6' of the inspection gas introduction means 2 and the suction port of the inspection gas suction pipe 3-1' of the inspection gas detection means 3 are directly facing the leak hole 1-7 of the short-circuit passage 1-8. The other leak inspection devices (inspection gas introduction means 2, inspection gas detection means 3, and atmospheric release means 4) are the same as in the first embodiment. Also, the geometric dimensions of the heat exchanger 1, the dimensions of the leak hole, and the pressure × volume of the inspection gas to be introduced are the same as in the first embodiment.

[0105] Figure 7 shows the measurement results of the test gas 2-8 in the second embodiment. The horizontal axis represents time, and the vertical axis represents the leakage flow rate of the test gas 2-8 (helium gas) detected by the gas detector 3-5 (helium leak detector).

[0106] The intensity of the sharp peak signal that appears immediately after time 0 s due to the test gas 2-8 (helium gas) passing through the short-circuit channel 1-8 is 1.2 × 10⁻¹⁴. －５ Pam ３ The value was / s, which was approximately twice as high as that of the first embodiment.

[0107] The increase in the inspection gas 2-8 signal after passing through the short-circuit passage 1-8 is due to the fact that by positioning the discharge port of the inspection gas introduction pipe 2-6' directly opposite the short-circuit passage 1-8, the inspection gas 2-8 is preferentially introduced into the short-circuit passage through the leak hole 1-7 during instantaneous introduction of the inspection gas 2-8, and by positioning the suction port of the inspection gas suction pipe 3-1' directly opposite the short-circuit passage 1-8, the inspection gas that has passed through the short-circuit passage 1-8 is preferentially drawn in. Third Embodiment of the Present Invention

[0108] A third embodiment of the present invention demonstrates that even when the leakage hole 1-7 is reduced in size and the leakage flow rate of the short-circuit passage 1-8 is minute, the signal of the inspection gas 2-8 passing through the short-circuit passage 1-8 can be detected. The third embodiment was carried out as follows.

[0109] In the third embodiment, the diameter of the leak holes 1-7 is 1.0 × 10 －４ This was set to m. The diameter of this leak hole is 5.0 × 10 of the diameter of leak holes 1-7 in the first or second embodiment. －４ It is 1 / 5 of m, and tap water (water pressure 3.0 × 10) is supplied to the heat exchanger 1 which has these leak holes 1-7. ５ When Pa) is flowed, the percentage of water flowing through leak holes 1-7 (100 × [flow rate of water flowing through leak holes 1-7] / ([flow rate of water flowing through reciprocating channel 1-6] + [flow rate of water flowing through leak holes 1-7])) is a very low percentage of 0.13%.

[0110] In the leak detection of the third embodiment, since the probability of the inspection gas 2-8 passing through the short-circuit passage 1-8 is low, it is necessary to increase the amount of inspection gas 2-8 introduced into the heat exchanger 1 and the suction speed of the inspection gas 2-8 and air by the flow rate control valve 3-3. The amount of inspection gas 2-8 to be introduced is 9.0 × 10 －１ Pam ３ (Pressure × Volume = (1.0 × 10) ５Pa)×(9.0×10 －６ I understand ３ ) = 9.0 × 10 －１ Pam ３ ) and 7.0 × 10 of the first or second embodiment. －１ Pam ３ It was increased slightly. Also, the suction speed was 2 x 10 －６ I understand ３ / s and 5 × 10 of the first or second embodiment －７ I understand ３ The rate was increased fourfold from / s. Here, it was important to note that if the amount of introduced test gas 2-8 is significantly increased, a large pressure rise occurs near the refrigerant inlet 1-2 of the heat exchanger 1 when the test gas is instantaneously introduced. This shortens the passage time of the test gas 2-8 through the reciprocating flow path 1-6, and in leak measurement, the test gas signal that has passed through the reciprocating flow path 1-6 and the test gas signal that has passed through the short-circuit flow path 1-8 will be superimposed.

[0111] Figure 8 shows the measurement results of the test gas 2-8 in Embodiment 3. The horizontal axis represents time, and the vertical axis represents the leakage flow rate of the test gas 2-8 (helium gas) detected by the gas detector 3-5 (helium leak detector).

[0112] The sharp peak signal that appears immediately after time 0s is the signal of the test gas 2-8 (helium gas) that has passed through the short-circuit channel 1-8, and the peak signal with a wide time span that appears after time 100s is the signal of the test gas 2-8 that has passed through the reciprocating channel 1-6. In this way, even when the leakage flow rate is minute, the apparatus of the present invention makes it possible to measure both the signal of the test gas 2-8 passing through the short-circuit channel 1-8 and the signal of the test gas 2-8 passing through the reciprocating channel 1-6 by separating them in time.

[0113] (Other Embodiments) In the first and second embodiments, the reciprocating flow path length of the heat exchanger 1 was 2 m. In leak testing of heat exchangers 1 with a longer or shorter reciprocating flow path length, it was possible to measure both the test gas 2-8 passing through the short-circuit flow path 1-8 and the test gas 2-8 passing through the reciprocating flow path 1-6, similar to the first or second embodiment, by appropriately setting the amount of accumulated gas (pressure × volume) in the small sealed space 2-6a of the test gas 2-8 introduced into the heat exchanger 1.

[0114] As described above, the present invention can handle inspection of internal leaks using short-circuit channels 1-8 with a wide range of reciprocating flow lengths and a wide range of permissible leak flow rates.

[0115] Finally, we will discuss the helium consumption in the leak detection device of the present invention. The helium consumption in one leak detection test in the first and second embodiments is 1.4 × 10⁻⁶. －５ I understand ３ The gas storage capacity of a general-purpose gas cylinder is 7 m³. ３ Therefore, one gas cylinder can perform 500,000 leak tests. In other words, using the leak testing device of this invention makes it possible to reduce the consumption of expensive helium gas.

[0116] The objects of inspection according to the present invention are not limited to heat exchangers and the like, but can be any device (liquid container) having a reciprocating flow path separated by a partition wall. Furthermore, when internal leakage occurs due to a short-circuit flow path in such a device, the leak inspection method and leak inspection apparatus of the present invention can be applied. Explanation of symbols

[0117] 1 Heat exchanger (liquid container) 1-1 Inlet / outlet joint jig (connecting end) 1-2 Refrigerant inlet (liquid inlet) 1-3 Refrigerant outlet (liquid outlet) 1-4 Housing 1-5 Partition wall 1-6 Reciprocating flow path 1-7 Leak hole 1-8 Short-circuit flow path 2 Inspection gas introduction means 2-1 Inspection gas cylinder 2-2 Pressure reducing valve 2-3 Pressure gauge 2-4 First gas valve 2-5 Second gas valve 2-6 Inspection gas introduction piping 2-6' Inspection gas introduction piping 2-6a Small sealed space 2-7 Connection jig 2-8 Inspection gas 3 Inspection gas detection means 3-1 Inspection gas suction piping 3-1' Inspection gas suction piping 3-2 Gas valve 3-3 Flow rate adjustment valve 3-4 Inspection gas detector 4 Atmospheric release means 4-1 Isobaric piping 4-2 Atmospheric release valve 4-3 Vacuum exhaust valve 100 Leak detection device (internal leak detection device for liquid containers) 200 Leak detection device (internal leak detection device for liquid containers)

[0118] [Table 1] shows the calculated travel time of the test gas 2-8 through the reciprocating flow path 1-6 (reciprocating flow path travel time) and the travel time through the short-circuit flow path 1-8 (short-circuit flow path travel time) when the length of the reciprocating flow path 1-6 and the pressure difference between the refrigerant inlet 1-2 and refrigerant outlet 1-3 of the heat exchanger 1 are appropriately set.

[0119] [Table 2] This table shows the calculated travel time of the inspection gas 2-8 through the reciprocating path 1-6 (reciprocating path travel time) and the travel time through the short-circuit path 1-8 (short-circuit path travel time) when the length of the reciprocating path 1-6 is appropriately set and the inspection gas 2-8 moves due to diffusion.

Claims

1. A liquid container (1) comprising a housing (1-4) having a reciprocating flow path (1-6) separated by a partition wall (1-5), and a connecting end (1-1) having a liquid inlet (1-2) and a liquid outlet (1-3) for liquid to flow in and out, wherein the internal leakage of the liquid container is detected due to a leak hole (1-7) in the partition wall (1-5), and the method for testing internal leakage of the liquid container is to detect a certain amount of gas (Pam) accumulated in a small sealed space (2-6a) provided in the middle of the inspection gas introduction piping (2-6). ３ A method for inspecting internal leaks in a liquid container, characterized by introducing an inspection gas (2-8) into the liquid container (1), moving the inspection gas (2-8) inside the liquid container (1) by the diffusion phenomenon of a gas with zero pressure difference between the liquid inlet (1-2) and the liquid outlet (1-3), and simultaneously performing vacuum evacuation from the liquid outlet (1-3), thereby creating a significant time difference that can be individually detected between the "short-circuit movement time" when the inspection gas (2-8) travels from the liquid inlet (1-2) through the leak hole (1-7) to the liquid outlet (1-3) and the "reciprocating flow time" when the inspection gas (2-8) travels from the liquid inlet (1-2) through the reciprocating flow path (1-6) to the liquid outlet (1-3), and detecting internal leaks caused by the leak hole (1-7).

2. In the method for testing the internal leakage of a liquid container according to claim 1, the amount of accumulated gas (Pam) of the test gas (2-8) accumulated in the small sealed space (2-6a) ３ ) is the amount of gas introduced (Pam) of the test gas (2-8) introduced into the liquid container (1). ３ ) is equivalent to 1 / 10 or less of the internal volume of the liquid container (1) when converted to atmospheric pressure (Pam ３ A method for testing internal leaks in a liquid container, characterized in that the pressure is adjusted to such a state.

3. In the method for inspecting internal leaks of a liquid container according to claim 1, the suction speed when vacuuming the liquid outlet (1-3) is 1 × 10⁻¹⁰ －８ I understand ３ / s to 1 x 10 －５ I understand ３ A method for testing internal leaks in a liquid container, characterized by being within the range of / s.

4. A method for inspecting internal leaks in a liquid container according to claim 1, characterized in that the direction of introduction when introducing the inspection gas (2-8) accumulated in the small sealed space (2-6a) into the liquid container (1), and the direction of exhaust when vacuuming the inspection gas (2-8) from the inside of the liquid container (1), are in a direction directly facing the partition wall (1-5).

5. A liquid container (1) comprising a housing (1-4) having a reciprocating flow path (1-6) separated by a partition wall (1-5), and a connecting end (1-1) having a liquid inlet (1-2) and a liquid outlet (1-3) for liquid to flow in and out, wherein the liquid container internal leak inspection device (100, 200) detects internal leakage caused by a leak hole (1-7) in the partition wall (1-5), the liquid container internal leak inspection device comprising: a connecting jig (2-7) for airtightly connecting piping to the connecting end (1-1); an inspection gas introduction pipe (2-6) capable of forming a small sealed space (2-6a) of a certain volume in the middle and for introducing an inspection gas (2-8) into the liquid container (1); an inspection gas suction pipe (3-1) for vacuuming the inspection gas (2-8) from the inside of the liquid container (1); and an inspection gas detector (3-4) for detecting the inspection gas (2-8), An internal leak inspection device for a liquid container, comprising an isobaric pipe (4-1) connecting the liquid inlet (1-2) and the liquid outlet (1-3), wherein the inspection gas introduction pipe (2-6) has a first gas valve (2-4) and a second gas valve (2-5) that form the small sealed space (2-6a), and the isobaric pipe (4-1) has an atmospheric release valve (4-2) and a vacuum exhaust valve (4-3).

6. In the internal leakage inspection device for a liquid container according to claim 5, the accumulated gas amount (Pam ３ ) of the inspection gas (2-8) accumulated in the small sealed space (2-6a) is such that the introduced gas amount (Pam ３ ) of the inspection gas (2-8) introduced into the interior of the liquid container (1) is adjusted to a gas amount (Pam ３ ) equivalent to 1 / 10 or less of the internal volume of the liquid container (1) in terms of atmospheric pressure. An internal leakage inspection device for a liquid container, characterized in that.

7. In the liquid container internal leak inspection device according to claim 5, the inspection gas detector (3-4) measures the liquid outlet (1-3) at 1 × 10 －８ I understand ３ / s to 1 x 10 －５ I understand ３ A liquid container internal leak inspection device characterized by vacuum evacuation at a suction speed within the range of / s.

8. A liquid container internal leak inspection device according to claim 5, characterized in that the discharge port of the inspection gas (2-8) of the inspection gas introduction pipe (2-6) and the suction port of the inspection gas (2-8) of the inspection gas suction pipe (3-1) are in a direction directly facing the partition wall (1-5).

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