Leakage inspection method and leakage inspection device for resin sheet sealed product

Abstract

Provided are a leakage inspection device and a leakage inspection method capable of performing quantitative leakage evaluation / airtightness assurance using an inspection gas on a resin sheet sealed article in which a contained article is tightly sealed in a vacuum state by a resin sheet.　A contained article 3 is packaged by two upper and lower resin sheets 4, 4 in which a recessed part 4r is formed in a central part, and a flat part 14a of a needle connection jig 14 is sandwiched by projecting parts 4f2, 4f2 of the resin sheets 4, 4. In a first-stage resin sheet welding process, a projection-shaped welding seal part comprising a first welding seal part 4a in which "inner peripheral surfaces are welded to each other" and a second welding seal part 4b in which "the inner peripheral surface of the resin sheets 4, 4 and the outer peripheral surface of the flat part 14a are welded" is formed on the outer periphery of the resin sheets 4, 4. In a second-stage resin sheet welding process, a resin sheet opening 4a1 sandwiched between two recessed corner parts b2, b2 of the first welding seal part 4a is welded and sealed to form a linear third welding seal part 4c.

Description

Leak inspection method and leak inspection device for sealed resin sheet products

[0001] The present invention relates to a leak inspection method and a leak inspection device for a resin sheet sealed product, and more particularly to a leak inspection method and a leak inspection device for a resin sheet sealed product in which an internal component is tightly sealed in a vacuum state by a resin sheet, and which is capable of quantitatively evaluating leaks and ensuring airtightness using a probe gas.

[0002] In order to prevent deterioration of food, medicine, mechanical parts, and electrical parts, these foods, medicines, and parts (hereinafter referred to as "internal parts") are sealed in a resin sheet bag. There are two methods for sealing internal parts in a resin sheet bag: one is to introduce an inert gas such as nitrogen gas or carbon dioxide gas at a pressure higher than atmospheric pressure into the resin sheet bag and seal it (hereinafter referred to as "positive pressure sealing"), and the other is to seal the resin sheet bag by creating a vacuum below atmospheric pressure (hereinafter referred to as "negative pressure sealing").

[0003] Leak testing of positive pressure hermetic sealing is performed by detecting inert gas leaking from within the resin sheet bag to the outside (see, for example, Patent Documents 1, 2 and 3).

[0004] On the other hand, in the case of leak inspection of negative pressure sealed products, a resin sheet sealed product in which the resin sheet and the internal components are in close contact with each other by creating a vacuum below atmospheric pressure inside is placed in a pressurized container and held in a pressurized atmosphere of helium gas for a certain period of time, and then placed in a vacuum container and held in vacuum for a certain period of time, and after the pressure is returned to atmospheric pressure, deformations caused by pinholes or the like formed in the resin sheet of the resin sheet sealed product are checked visually or by touch (see, for example, Patent Document 4).

[0005] Japanese Patent Publication No. 63-33440 JP 2023-8779 A JP 10-185752 A JP 2004-93208 A

[0006] The visual inspection or tactile inspection described in Patent Document 4 is performed because it is difficult to apply conventional leak inspection methods, such as the immersion method of the helium leak test (JIS Z 2331:2006) or the sealed product chamber method of the pressure change leak test (JIS Z 2332:2012), to leak inspection of resin sheet sealed products with a vacuum inside.

[0007] The immersion method of helium leak testing (JIS Z 2331:2006) involves immersing a test object in a sealed container filled with helium gas for a certain period of time, allowing the helium gas to penetrate into the test object, placing the test object with the helium gas infiltrated into a vacuum container, and detecting the helium gas using the vacuum container method of helium leak testing to perform a leak inspection.

[0008] When this immersion method for helium leak testing is applied to a resin sheet-sealed product with a vacuum inside, even if pinholes are formed in the resin sheet when the resin sheet-sealed product is immersed in a container filled with helium gas, it is difficult for helium gas to penetrate into the gap between the tightly adhered resin sheet and the internal components. Furthermore, a certain amount of helium gas dissolves in the resin sheet during helium gas immersion, and helium gas may be detected during the next helium leak test even though there is no leak. From these findings, it can be seen that the immersion method for helium leak testing is not very suitable as a leak detection method for resin sheet-sealed products with a vacuum inside.

[0009] In the immersion method of helium leak testing, the test object immersed in helium is placed in a vacuum container and evacuated to perform the helium leak test, but if the leak hole is large and there is a large amount of leak, the helium gas that has entered will be evacuated, making it impossible to detect the leak. In other words, the immersion method has the disadvantage that it is not suitable for leak testing of large leaks and is limited to leak testing of small leaks.

[0010] The sealed chamber method of pressure change leak testing (JIS Z 2332:2012) involves placing a test object in a sealed container, pressurizing the container with gas, and then measuring the amount of leakage from the change in pressure inside the container after a certain period of time. In other words, if a leak occurs in a sealed test object with a vacuum inside, gas inside the pressurized container will enter the test object, causing a decrease in the pressure inside the container. This change in pressure in the container is used to detect leaks.

[0011] When this sealed product chamber method of pressure change leak testing is applied to a resin sheet sealed product in which a resin sheet with a vacuum inside and an internal component are tightly attached to each other, the gap between the tightly attached resin sheet and the internal component is very small, and even if there is a leak in the resin sheet, the amount of gas that enters when gas is pressurized is very small, so the pressure change in the container for leak detection is small, making leak detection difficult.In other words, it can be seen that the sealed product chamber method of pressure change leak testing is not very suitable as a means of leak inspection for resin sheet sealed products.

[0012] However, when the internal components are sealed with a resin sheet, it is nearly impossible to accurately detect the pressure inside the sealed resin sheet product, because a pressure detection probe cannot be inserted into the sealed resin sheet product after the sealing.

[0013] Similarly, it is nearly impossible to accurately detect the pressure inside a resin sheet-sealed product immediately before the internal components are welded and sealed with the resin sheet. This is because the area to be welded and sealed is pressed from above and below by the welding device (heat sealer), and it is not possible to bring the pressure detection probe close to the area to be welded and sealed immediately before welding.

[0014] In other words, when the internal components are tightly sealed in a vacuum state using a resin sheet, it was impossible to detect the pressure inside the resin sheet sealed product when the resin sheet was welded, and ultimately it was impossible to control the pressure inside the resin sheet sealed product when it was welded.

[0015] Therefore, when applying the vacuum chamber method as a leak test method for resin sheet sealed products, in which "the inside of the test object placed inside a vacuum chamber maintained at a predetermined vacuum level is pressurized with a probe gas and the probe gas leaking from the test object into the vacuum chamber is detected," the pressure difference between the inside and outside of the resin sheet sealed product is unknown, and the threshold value of the helium leak flow rate [Pa m ３ Thus, for sealed resin sheet products with a vacuum inside, quantitative leak evaluation and airtightness assurance (for example, 10 －７ P.A.M. ３ It is believed that there is no leak inspection method that can perform this at a speed of less than 1 / s.

[0016] Therefore, the present invention has been made in consideration of the problems of the above-mentioned conventional technology, and its object is to provide a leak inspection method and leak inspection device for resin sheet sealed products that can quantitatively evaluate leaks and guarantee airtightness using a probe gas for resin sheet sealed products in which internal components are tightly sealed in a vacuum state by a resin sheet.

[0017] In order to achieve the above object, the leak inspection method for resin sheet sealed products according to the present invention is a method for inspecting leaks in resin sheet sealed products, in which a resin sheet sealed product (10) in which an internal component (3) is tightly sealed in a vacuum state by welding two upper and lower resin sheets (4, 4) is placed inside a vacuum container (1) maintained at a predetermined vacuum level, and a leak inspection is performed using a detection gas. When the internal component (3) is covered with the resin sheets (4, 4), a piping connection jig (14) for vacuum exhaust or detection gas introduction is sandwiched between parts of the resin sheets (4, 4), and a welded seal part (4a, 4b) is formed "so as to include the internal component (3) inside and form a protruding part (b2-b1-b1-b2) that protrudes partly outward." a first leak test is carried out in which a probe gas is introduced from a narrow resin sheet opening (4a1) formed in the resin sheet (4, 4) and the built-in component (3) and the protruding portion (b2-b1-b1-b2) into a gap space (5) formed between the resin sheet (4, 4) and the built-in component (3) and the protruding portion (b2-b1-b1-b2), and the probe gas leaking from the welded seal portion (4a, 4b) into the outside of the vacuum container (1) is detected; the gap space (5) is then evacuated to a pressure at which "a sufficient amount of probe gas remains below atmospheric pressure to be able to detect a leak flow rate," and then a welded seal portion (4c) is formed to seal the resin sheet opening (4a1), and the probe gas leaking from the welded seal portion (4c) downstream of the piping connection jig (14) is detected.

[0018] In the above configuration, the welded seal portions (4a, 4b) have protruding portions (b2-b1-b1-b2), forming a convex shape overall. Therefore, the welded seal portions (4a, 4b) have two recessed corners (b2, b2), and a small opening (resin sheet opening (4a1)) is formed between the recessed corners (b2, b2). Because the resin sheet opening (4a1) is also an opening for the protruding portions (b2-b1-b1-b2), a clearance space (5) containing the built-in component (3) is formed on one side of the resin sheet opening (4a1), and a pipe introduction space (6) containing the pipe connection jig (14) is formed on the other side.

[0019] Therefore, when airtightness is ensured in the welded seal portions (4a, 4b) and the interiors (14ca, 14cb) of the pipe connection jig (14), the pressure in the clearance space (5) and the pressure in the pipe introduction space (6) can be considered to be equal to each other. This makes it possible to control and measure the pressure in the clearance space (5) directly or indirectly via the pressure in the pipe introduction space (6).

[0020] Furthermore, since the pipe connection jig (14) is disposed on the convex protrusion (b2-b1-b1-b2), the pipe connection jig (14) does not interfere with the welding and sealing of the resin sheet opening (4a1). This makes it possible to control and measure the pressure in the gap space (5) up until just before the resin sheet opening (4a1) is welded and sealed.

[0021] A second feature of the resin sheet sealed product leak inspection method according to the present invention is that the first leak inspection continues until the end of the second leak inspection, thereby detecting the detection gas leaking into the external vacuum container (1) from the "welded seal portion (4c) associated with the resin sheet opening (4a1)" in addition to the welded seal portion (4a, 4b).

[0022] With the above configuration, it is possible to confirm that the previously sealed welded seal portions (4a, 4b) are maintaining a normal sealed state during the second leak test, and it is also possible to confirm the leakage flow rate of the detection gas from the "welded seal portion (4c) relating to the resin sheet opening (4a1)" into the vacuum vessel (1).

[0023] A third feature of the resin sheet sealed product leakage inspection method according to the present invention is that the resin sheets (4, 4) are welded and sealed so that the protruding portions (b2-b1-b1-b2) cross the piping connection jig (14), and the portion (14a) of the piping connection jig (14) that is sandwiched between the resin sheets (4, 4) is formed to be a flat portion (14a).

[0024] In the above configuration, the portion of the pipe connection jig (14) that is sandwiched between the resin sheets (4, 4) is the flat portion (14a), so it is extremely easy to ensure airtightness at the welded seal portion (4b) between the inner surface of the resin sheets (4, 4) and the outer surface of the pipe connection jig (14).

[0025] A fourth feature of the method for inspecting leaks in sealed resin sheet products according to the present invention is that the pipe (15a) can move back and forth inside the pipe connection jig (14) while maintaining airtightness.

[0026] In the above configuration, by advancing the pipe (15a) close to the gap space (5), it becomes extremely easy to perform pressure control such as vacuum evacuation of the gap space (5) or introduction of a detection gas, etc. On the other hand, by retracting the pipe (15a) away from the gap space (5), it becomes possible to avoid interference between the pipe (15a) and the welding device (2-2) during the welding sealing process.

[0027] A fifth feature of the method for inspecting leaks in sealed resin sheet products according to the present invention is that a recess (4r) into which the built-in component (3) fits is formed in the center of the resin sheet (4), and the bottom portions (4f, 4f) of the recess (4r) are formed in a convex shape that combines a square frame portion (4f1) and a protruding portion (4f2).

[0028] In the above configuration, the resin sheets (4, 4), the built-in components (3) and the piping connection jig (14) can be set up extremely easily inside the vacuum vessel (1).

[0029] A sixth feature of the method for inspecting leaks in sealed resin sheet products according to the present invention is that when the gap space (5) is evacuated to a predetermined pressure and the resin sheet opening (4a1) is welded, the pressure fluctuation in the gap space (5) is made smaller than the pressure fluctuation at the start of evacuation, and then the weld-sealing is performed.

[0030] In the above configuration, the pressure transition in the gap space (5) during welding can be considered to be almost the same as the pressure transition on the downstream side (second vacuum gauge (17)). As a result, it is possible to estimate the pressure in the gap space (5) during welding with high accuracy, and it is possible to set a highly reliable threshold value for the leakage flow rate of the detection gas.

[0031] A seventh feature of the resin sheet sealed product leak inspection method according to the present invention is that when the second leak inspection is carried out, the flow rate of the probe gas introduced into the probe gas detector (18) that measures the leakage flow rate of the probe gas is made smaller than the flow rate of the probe gas introduced into the vacuum pump (16) that evacuates the "welded seal portion (4c) related to the resin sheet opening (4a1)."

[0032] In the above configuration, the amount of probe gas remaining in the piping leading to the probe gas detector (18) is reduced, thereby maintaining the reliability of the measured leak flow rate of the probe gas.

[0033] An eighth feature of the resin sheet sealed product leak inspection method according to the present invention is that after measuring the leakage flow rate of the detection gas leaking from the "welded seal portion (4c) relating to the resin sheet opening (4a1)" to the downstream side of the piping connection jig (14), the vacuum exhaust system and the leakage flow rate measurement system are purged with an inert gas other than the detection gas.

[0034] In the above configuration, residual detection gas is forcibly removed from the vacuum exhaust system and the leakage flow rate measurement system, which significantly improves the reliability of the measured leakage flow rate of the detection gas.

[0035] The resin sheet sealed product leak inspection device according to the present invention for achieving the above object includes a vacuum container (1) that houses an internal component (3) covered with resin sheets (4, 4) and a piping connection jig (14) sandwiched between parts of the resin sheets (4, 4) under a predetermined vacuum environment, a first vacuum pump (11) that evacuates the internal space of the vacuum container (1) formed around the internal component (3), a pair of first welding devices (2-1) that weld overlapping parts (4f, 4f) of the resin sheets (4, 4) into a convex shape along the outer periphery to form convex welded seal parts (4a, 4b), a second vacuum pump (16) that evacuates a gap space (5) formed between the resin sheets (4, 4) and the internal component (3), and a probe for filling the gap space (5). a detection gas source (19) for introducing a detection gas; a first pipe (15) connected to the gap space (5), the second vacuum pump (16), and the detection gas source (19), respectively; a first detection gas detector (13) for detecting the leakage flow rate of the detection gas leaking from the convex-shaped welded seal portion (4a, 4b) into the inside of the vacuum vessel (1); a pair of second welding devices (2-2) for welding a narrow resin sheet opening (4a1) sandwiched between two recessed corners (b2, b2) of the convex-shaped welded seal portion (4a, 4b) to form a linear welded seal portion (4c); and a second detection gas detector (18) for detecting the leakage flow rate of the detection gas leaking from the linear welded seal portion (4c) to the first pipe (15).

[0036] With the above configuration, the first and second features of the "Method for inspecting a sealed resin sheet product for leaks" can be suitably implemented.

[0037] A second feature of the resin sheet sealed product leak inspection device according to the present invention is that the piping connection jig (14) comprises a molded product in which "a flat portion (14a) and a cylindrical portion (14b) are integrally molded with a resin compatible with the resin sheets (4, 4)" and have penetration portions (14aa, 14ba) therein, and the flat portion (14a) is sandwiched between portions (4f2, 4f2) of the overlapping portions (4f, 4f) of the resin sheets (4, 4) that protrude outward from the resin sheet opening (4a1).

[0038] With the above configuration, the third feature of the "method for inspecting a sealed resin sheet product for leaks" can be suitably implemented.

[0039] A third feature of the resin sheet sealed product leak inspection device according to the present invention is that a pipe (15a) connected to the first pipe (15) via a flexible movable pipe (15b) is arranged in the through-hole (14aa, 14ba) so as to be freely movable back and forth.

[0040] With the above configuration, the fourth feature of the "method for inspecting a sealed resin sheet product for leakage" can be suitably implemented.

[0041] A fourth feature of the resin sheet sealed product leak inspection device of the present invention is that a through hole (14aa) is formed inside the flat portion (14a) so that the piping (15a) can move back and forth.

[0042] With the above configuration, the fourth feature of the "method for inspecting a sealed resin sheet product for leakage" can be suitably implemented.

[0043] A fifth feature of the resin sheet sealed product leak inspection device according to the present invention is that the piping connection jig (14) has a separate metallic female cylindrical portion (14c) that includes a large diameter portion (14ca) into which the cylindrical portion (14b) fits and a small diameter portion (14cb) through which the piping (15a) passes, and sealing members (14cc, 14cd) that maintain airtightness are provided between the cylindrical portion (14b) and the large diameter portion (14ca) and between the piping (15a) and the small diameter portion (14cb), respectively.

[0044] With the above configuration, the fourth feature of the "method for inspecting a sealed resin sheet product for leakage" can be suitably implemented.

[0045] The sixth feature of the resin sheet sealed product leakage inspection device according to the present invention is that the bottom portion (4f) of the resin sheet (4) has a convex shape formed by combining a square frame portion (4f1) and a protruding portion (4f2), and a recess (4r) is formed inside the bottom portion (4f) into which the built-in component (3) fits.

[0046] With the above configuration, the fifth feature of the "Method for inspecting a sealed resin sheet product for leaks" can be suitably implemented.

[0047] A seventh feature of the resin sheet sealed product leakage inspection device according to the present invention is that one or more small conductance components (41) having a conductance value smaller than that of the second pipe (16a) are connected in parallel to the second pipe (16a) connecting the first pipe (15) and the second vacuum pump (16).

[0048] With the above configuration, the sixth feature of the "Method for inspecting leaks in sealed resin sheet products" can be suitably implemented.

[0049] An eighth feature of the resin sheet sealed product leak inspection device according to the present invention is that one or more small conductance components (42, 43) having a conductance value smaller than that of the third pipe (18a) are connected in parallel to the third pipe (18a) connecting the first pipe (15) and the second gas detector (18).

[0050] With the above configuration, the seventh feature of the "Method for inspecting leaks in sealed resin sheet products" can be suitably implemented.

[0051] A ninth feature of the resin sheet sealed product leak inspection device according to the present invention is that it is configured so that an inert gas other than the detection gas can be supplied in parallel to the second vacuum pump (16) and the second detection gas detector (18).

[0052] With the above configuration, the eighth feature of the "Method for inspecting leaks in sealed resin sheet products" can be suitably implemented.

[0053] According to the resin sheet sealed product leak inspection method and leak inspection device of the present invention, it is possible to quantitatively evaluate leaks and guarantee airtightness using a probe gas for a resin sheet sealed product (10) in which an internal component (3) is tightly sealed in a vacuum state by resin sheets (4, 4).

[0054] FIG. 1 is an explanatory diagram showing the configuration of the main parts of a leak inspection device for sealed resin sheets according to a first embodiment of the present invention. FIG. 1 is an explanatory diagram showing the placement of a sealed resin sheet product in a vacuum container and the welded seal portion of the resin sheet. FIG. 2 is an explanatory diagram showing the cutting of a resin sheet related to a sealed resin sheet product and the separation of a needle connecting jig. FIG. 3 is an explanatory diagram showing the configuration of a needle connecting jig according to the present invention. FIG. 4 is a process diagram showing a leak inspection process using a leak inspection device for sealed resin sheets according to a first embodiment of the present invention. FIG. 5 is an explanatory diagram showing a resin sheet welding process before a first leak inspection. FIG. 6 is an explanatory diagram showing a resin sheet welding process before a second leak inspection. FIG. 7 is a graph showing measurement results of the pressure before and after welding of an opening portion of a resin sheet according to the first embodiment of the present invention and the helium leakage flow rate leaking from a third welded seal portion over time. FIG. 8 is an explanatory diagram showing the configuration of the main parts of a leak inspection device for sealed resin sheets according to a second embodiment of the present invention. FIG. 9 is a graph showing measurement results of the pressure before and after welding of an opening portion of a resin sheet according to the second embodiment of the present invention and the helium leakage flow rate leaking from a third welded seal portion over time. 10 is a graph showing measurement results of the pressure before and after welding of the opening of the resin sheet according to the third embodiment of the present invention and the time transition of the leakage flow rate of helium leaking from the third weld seal portion. It is an explanatory diagram showing the main configuration of a piping connection jig of the resin sheet sealed product leak inspection device according to the fourth embodiment of the present invention. It is a graph showing measurement results of the pressure before and after welding of the opening of the resin sheet according to the fourth embodiment of the present invention and the time transition of the leakage flow rate of helium leaking from the third weld seal portion. It is an explanatory diagram showing the main configuration of a piping connection jig of the resin sheet sealed product leak inspection device according to the fourth embodiment of the present invention.

[0055] The present invention will now be described with reference to the accompanying drawings.

[0056] (First embodiment) Fig. 1 is an explanatory diagram showing the main configuration of a resin sheet sealed product leak inspection device 100 according to a first embodiment of the present invention. Note that a needle connection jig 14 is shown in cross section. Fig. 1(a) is a plan view of the resin sheet sealed product leak inspection device 100. Fig. 1(b) is a cross-sectional view taken along line A-A in Fig. 1(a).

[0057] This resin sheet sealed product leak inspection device 100 is configured so that when the internal component 3 is welded and sealed with two upper and lower resin sheets 4, 4, the internal component 3 can be welded and sealed with the two upper and lower resin sheets 4, 4 while measuring the pressure in the gap space 5 formed between the resin sheets 4, 4 and the internal component 3 and controlling the pressure to a predetermined value. This makes it possible for the resin sheet sealed product leak inspection device 100 to perform quantitative leak evaluation and airtightness assurance for the resin sheet sealed product 10 using helium gas. Note that the "quantitative leak evaluation" referred to here means determining a threshold value (for example, 10) of the helium leakage flow rate leaking from the welded seal portion based on the pressure difference between the inside and outside of the gap space 5 (inside the vacuum vessel 1). －７ [Pa·m ３ / s or less). "Airtightness assurance" means measuring the helium leakage flow rate from the welded seal and determining whether the welded seal is good or bad based on a preset threshold.

[0058] Although details will be described later, the resin sheet welding process for welding and sealing the built-in component 3 with two upper and lower resin sheets 4, 4 is performed in two stages, and leak inspection of the welded and sealed portion corresponding to the resin sheet welding process is performed in two stages, "first leak inspection" and "second leak inspection." Incidentally, Figure 1 shows the resin sheet sealed product leak inspection device 100 during the second leak inspection. The configuration of the resin sheet sealed product leak inspection device 100 will be described below.

[0059] This resin sheet sealed product leak inspection device 100 includes a vacuum container 1 capable of maintaining a vacuum inside, two upper and lower resin sheets 4, 4 for packaging an internal component 3, a first welding device 2-1 for welding the outer peripheries of the two upper and lower resin sheets 4, 4, a second welding device 2-2 for welding resin sheet openings 4a1 (FIG. 2(b)) of the two upper and lower resin sheets 4, 4, a first vacuum pump 11 for evacuating the inside of the vacuum container 1 to a predetermined pressure, and a first vacuum gauge 12 for measuring the degree of vacuum inside the vacuum container 1. The device includes a first helium gas detector 13 for detecting helium gas leaking from the first welded seal portion 4 a and the second welded seal portion 4 b, a needle connecting jig 14 for connecting a needle pipe 15 a for evacuating the gap space 5 or introducing helium gas, a first pipe 15 having a flexible movable pipe 15 b directly connected to the needle pipe 15 a, a second vacuum pump 16 for evacuating the gap space 5 via the needle pipe 15 a, and a pump for connecting the first pipe 15 and the second vacuum pump 16. a second pipe 16a connecting the first pipe 15 and the second helium gas detector 18; a second vacuum gauge 17 for measuring the degree of vacuum in the gap space 5; a second helium gas detector 18 for detecting helium gas leaking from the third welded seal portion 4c, etc.; a third pipe 18a connecting the first pipe 15 and the second helium gas detector 18; a helium gas cylinder 19 for supplying helium gas to the gap space 5; a fourth pipe 19a connecting the first pipe 15 and the helium gas cylinder 19; and a fourth pipe 19a for cutting off communication between the vacuum vessel 1 and the first vacuum pump 11. The system is comprised of a first vacuum valve 21, a second vacuum valve 22 that cuts off communication between the vacuum vessel 1 and the first helium gas detector 13, a third vacuum valve 23 that cuts off communication between the gap 5 and the first pipe 15, a fourth vacuum valve 24 that cuts off communication between the first pipe 15 and the second vacuum pump 16, a first gas valve 31 that opens the vacuum vessel 1 to the atmosphere, and a second gas valve 32 that cuts off communication between the first pipe 15 and the helium gas cylinder 19. Each component will be described in further detail below.

[0060] The first welding device 2-1 has, for example, a convex frame structure and forms a convex welded seal portion. The convex welded seal portion is composed of a first welded seal portion 4a, which is a welded seal portion between the inner peripheral surfaces of the two upper and lower resin sheets 4, 4, and a second welded seal portion 4b, which is a welded seal portion between the inner peripheral surfaces of the two upper and lower resin sheets 4, 4 and the outer peripheral surface of the needle connecting jig 14. The first welding devices 2-1 are disposed above and below the built-in components 3 and are configured to be movable in the vertical direction by an elevator device (not shown). A heater (not shown) is built into the frame.

[0061] Similarly, the second welding device 2-2 has, for example, a linear frame structure and forms a linear welded seal portion. The linear welded seal portion is a third welded seal portion 4c formed by welding the inner circumferential surfaces of the resin sheets 4, 4 located at the resin sheet opening 4a1 (FIG. 2(b)). The second welding devices 2-2 are disposed above and below the built-in component 3 and are configured to be movable in the vertical direction by an elevator device (not shown). A heater (not shown) is built into the frame.

[0062] 2(a), the resin sheet 4 has a recess 4r formed in the center that resembles half the outline of the built-in component 3. The recess 4r is surrounded by a skirt 4f, most of which forms a rectangular frame 4f1, and the portion that sandwiches the needle connecting jig 14 forms a protruding portion 4f2. The resin sheet 4 can be made of, for example, a resin film having a laminated structure of an easily weldable resin film and a metal film, or a resin film having a laminated structure of an easily weldable resin film and a low gas permeable film.

[0063] As shown in Figure 2(b), the first welding device 2-1 melts and presses the outer peripheries of the two upper and lower resin sheets 4, 4 (the square frame portions 4f1, 4f1 and the protruding portions 4f2, 4f2 in Figure 2(a)) from above and below, sealing the internal components 3 with the two upper and lower resin sheets 4, 4. Therefore, the airtightness of the gap space 5 formed between the resin sheets 4, 4 and the internal components 3 is ensured by the first weld seal portion 4a (dotted line portion), the second weld seal portion 4b (solid line portion), and the needle connecting jig 14. The sealing means (helium leakage prevention means) of the needle connecting jig 14 will be described later with reference to Figure 4.

[0064] Incidentally, the aforementioned "first leak test" involves detecting helium gas leaking from the first welded seal portion 4a, the second welded seal portion 4b, and the needle connecting jig 14 into the external vacuum vessel 1 using the first helium gas detector 13.

[0065] 2(c), the second welding device 2-2 melts and presses the resin sheet opening 4a1 from above and below, sealing the built-in component 3 with the two upper and lower resin sheets 4, 4. Therefore, the airtightness of the final resin sheet sealed product 10 is ensured by the first welded seal portion 4a (dotted line portion) and the third welded seal portion 4c.

[0066] In the aforementioned "second leak test," helium gas leaking from the third weld seal portion 4c toward the first piping 15 is detected by the second helium gas detector 18. In the "first leak test," helium gas leaking from the first weld seal portion 4a into the external vacuum vessel 1 is detected by the first helium gas detector 13. Even when the "second leak test" is being performed, the "first leak test" is continued, and helium gas leaking from the first weld seal portion 4a and the newly welded third weld seal portion 4c into the external vacuum vessel 1 is detected by the first helium gas detector 13.

[0067] The clearance space 5 is an extremely small space formed between the two upper and lower resin sheets 4, 4 and the built-in components 3, and during the first leak test, helium gas is introduced from a helium gas cylinder 19 via a needle pipe 15a. Furthermore, during the second leak test, the clearance space 5 is evacuated via the needle pipe 15a by a second vacuum pump 16 so that helium gas equivalent to 100 Pa or more of the helium gas introduced during the first leak test remains in the clearance space 5.

[0068] As shown in FIG. 3A, the protruding portions 4f2, 4f2 of the bottom portions 4f, 4f of the upper and lower resin sheets 4, 4 are cut off after the second leak test is completed, and the square frame portions 4f1, 4f1 are left.

[0069] 3(b), the flat portion 14a and the male fitting portion 14b sandwiched between the cut protruding portions 4f2, 4f2 cannot be reused because the second weld seals 4b, 4b are formed, and they are separated from the female fitting portion 14c and discarded together with the protruding portions 4f2, 4f2. The female fitting portion 14c of the needle connecting jig 14 is reused while remaining fixed to the vacuum vessel 1.

[0070] Returning to FIG. 1( b), the needle connecting jig 14 is configured so that the needle pipe 15a can freely move back and forth within it. The needle pipe 15a has a flow path formed therein and is connected to the clearance space 5 and the first pipe 15 via a movable pipe 15b. The movable pipe 15b is a flexible pipe having a bellows structure, for example. Therefore, the needle pipe 15a can be brought close to the resin sheet opening 4a1 of the clearance space 5, which enables pressure control and pressure measurement for the clearance space 5 via the needle pipe 15a. Details of the needle connecting jig 14 will be described later with reference to FIG. 4.

[0071] The first vacuum pump 11 is a vacuum pump for evacuating the vacuum vessel 1, and may be, for example, a compound pump consisting of a Roots-type vacuum pump (not shown) and an oil-sealed rotary vacuum pump (not shown) connected downstream of the Roots-type vacuum pump.

[0072] Returning to FIG. 1A, the first vacuum gauge 12 is a vacuum gauge for measuring the degree of vacuum in the vacuum vessel 1, and for example, a Pirani vacuum gauge can be used.

[0073] The first helium gas detector 13 is used in the first leak test. The "first leak test" is a leak test that detects helium gas leaking from the first welded seal portion 4a and the second welded seal portion 4b, and further from the needle connecting jig 14 into the external vacuum vessel 1. This first leak test is continued until the second leak test is completed.

[0074] The first pipe 15 is a pipe for controlling and measuring the pressure in the gap space 5. Therefore, the first pipe 15 is connected to a second vacuum pump 16 of the vacuum exhaust system, a second vacuum gauge 17 of the pressure measurement system, a second helium gas detector 18 of the leakage flow rate measurement system, and a helium gas cylinder 19 of the helium gas introduction system.

[0075] The second vacuum pump 16 is a vacuum pump for evacuating the gap space 5, and may be, for example, a positive displacement vacuum pump that operates at a low vacuum, such as an oil rotary pump.

[0076] The second helium gas detector 18 is used in the second leak test. The "second leak test" is a leak test to detect helium gas leaking from the third welded seal portion 4c where the resin sheet opening 4a1 (FIG. 2(b)) is welded and sealed to the first piping 15 side.

[0077] The second vacuum gauge 17 is a vacuum gauge for measuring the degree of vacuum in the gap space 5, and a Pirani vacuum gauge can be used as in the first vacuum gauge 12.

[0078] 4A and 4B are explanatory diagrams showing the configuration of the needle connecting jig 14 according to the present invention. Fig. 4A shows the state of the needle connecting jig 14 after the first welding and sealing step. Fig. 4B shows the view from arrow B in Fig. 4A. Fig. 4C shows the helium leakage prevention means for the gap space 5.

[0079] The needle connecting jig 14 is composed of a flat portion 14a that is sandwiched between two upper and lower resin sheets 4, 4, a male mating portion 14b that is integrally molded with the flat portion 14a, and a female mating portion 14c into which the male mating portion 14b is press-fitted.

[0080] The flat portion 14a is made of a high-hardness resin that is the same as or compatible with the resin sheet 4, and has, for example, a rectangular and flat shape. A through-hole 14aa penetrates the inside of the flat portion 14a, allowing the needle pipe 15a to move forward and backward without load. Note that the flat portion 14a is not limited to the above-mentioned high-hardness resin, and may be made of a resin having elasticity.

[0081] The male fitting portion 14b is integrally molded with the flat portion 14a and has a cylindrical shape. The male fitting portion 14b has a through-hole 14ba formed therein through which the needle pipe 15a passes.

[0082] The female fitting portion 14c is made of metal and has a two-stage cylindrical structure with a large diameter portion 14ca and a small diameter portion 14cb. The male fitting portion 14b is press-fitted into the large diameter portion 14ca. A needle pipe 15a is inserted into the small diameter portion 14cb.

[0083] An O-ring 14cc is provided on the large-diameter portion 14ca to ensure airtightness between the outer circumferential surface of the male fitting portion 14b and the large-diameter portion 14ca of the female fitting portion 14c. Similarly, an O-ring 14cd is provided on the small-diameter portion 14cb to ensure airtightness between the outer circumferential surface of the needle pipe 15a and the small-diameter portion 14cb of the female fitting portion 14c. Therefore, as shown in FIG. 4(c), the clearance space 5 is ensured to be airtight by the first weld seal portion 4a, the second weld seal portion 4b, and the O-rings 14cc and 14cd.

[0084] The female fitting portion 14c is fixed to the vacuum container 1 so as to be reusable. The leak inspection process using the leak inspection device 100 for sealed resin sheet products will be described below.

[0085] FIG. 5 is an explanatory diagram showing a leak inspection process using the leak inspection device 100 for sealed resin sheet products according to the first embodiment of the present invention.

[0086] In process P1, the internal component 3 is packaged in two upper and lower resin sheets 4, 4, and the flat portion 14a of the needle connecting jig 14 is sandwiched between them and set inside the vacuum container 1. As shown in Figure 2(a), the flat portion 14a of the needle connecting jig 14 is sandwiched between the protruding portions 4f2, 4f2 of the two upper and lower resin sheets 4, 4. The two upper and lower resin sheets 4, 4 are also temporarily fastened together with a first welding device 2-1 to prevent movement.

[0087] In process P2, the first vacuum valve 21 is opened and the vacuum vessel 1 is evacuated by the first vacuum pump 11. The ultimate pressure of the vacuum vessel 1 is, for example, less than 100 Pa.

[0088] In process P3, the first welding device 2-1 welds and seals the outer peripheries of the two upper and lower resin sheets 4, 4. As shown in Figure 6, the welded and sealed area by the first welding device 2-1 consists of a first welded seal portion 4a, where the inner peripheries of the resin sheets 4 are welded together, and a second welded seal portion 4b (section b1-b1), where the "inner periphery of the resin sheet 4" and the "outer periphery of the flat portion 14a of the needle connecting jig 14" are welded together. This second welded seal portion 4b is formed in two locations, one above the other. In the weld-sealing step of process P3, the internal component 3 is sealed between the two upper and lower resin sheets 4, 4 and the needle connecting jig 14.

[0089] Note that, when the inner peripheral surfaces of the upper and lower resin sheets 4, 4 are joined together, the area corresponding to the section b2-b2 remains as a non-welded portion (resin sheet opening 4a1) that is not welded by the first welding device 2-1. This resin sheet opening 4a1 will be welded and sealed by the second welding device 2-2 before the second leak test.

[0090] In process P4, the third vacuum valve 23 and the fourth vacuum valve 24 are opened, and the clearance space 5 (the area shaded diagonally upward to the right in FIG. 6 ) and the needle introduction space 6 (the area shaded diagonally downward to the right, the rectangular area b1-b2-b2-b1) are evacuated by the second vacuum pump 16. The degree of vacuum in the clearance space 5 is measured by the second vacuum gauge 17.

[0091] In process P5, the first vacuum valve 21 is closed, the second vacuum valve 22 is opened, the vacuum vessel 1 is evacuated by the first helium gas detector 13, and a leak detection is performed.

[0092] In process P6, the fourth vacuum valve 24 is closed, and the second gas valve 32 is opened to introduce helium gas from the helium gas cylinder 19 into the gap space 5.

[0093] In process P7, the first helium gas detector 13 detects helium gas leaking into the vacuum vessel 1 from the gap 5 through the first welded portion 4a and the second welded portion 4b, and helium gas leaking into the vacuum vessel 1 through the needle connecting jig 14 (first leak test). This first leak test is continued until the second leak test, which will be described later, is completed.

[0094] In process P8, the second gas valve 32 is closed, the fourth vacuum valve 24 is opened, and the gap 5 is again evacuated to a vacuum by the second vacuum pump 16. The ultimate pressure of the gap 5 is a vacuum pressure at which a sufficient amount of helium gas remains to enable the second leak test to be performed, for example, 100 Pa or more.

[0095] In process P9, the needle pipe 15a is retracted, and the resin sheet opening 4a1 is welded by the second welding device 2-2. As shown in FIG. 7, the resin sheet opening 4a1 represented by the section b2-b2 is welded to form the third weld seal portion 4c. As a result, the clearance space 5 is airtightly sealed by the first weld seal portion 4a excluding the section b2-b1-b1-b2 and the third weld seal portion 4c consisting of the section b2-b2, with a sufficient amount of helium gas remaining inside to perform the second leak test.

[0096] In process P10, the second vacuum pump 16 evacuates the inside of the piping (the insides of the needle introduction space 6, the needle pipe 15a, the first piping 15, and the second piping 16a) from the third weld seal portion 4c to the second vacuum pump 16. The ultimate pressure inside the piping is, for example, less than 10 Pa.

[0097] In process P11, the fourth vacuum valve 24 is closed, the fifth vacuum valve 25 is opened, and the second helium gas detector 18 detects helium gas leaking from the third weld seal portion 4c into the piping (second leak test). The first leak test is also performed during the second leak test. That is, the second helium gas detector 18 ensures that there is no leakage from the third weld seal portion 4c, among the weld seal portions where the inner circumferential surfaces of the upper and lower resin sheets 4 are welded together, into the piping. The first helium gas detector 13 ensures that there is no leakage from the first weld seal portion 4a, the second weld seal portion 4b, and the third weld seal portion 4c into the external vacuum vessel 1.

[0098] After the first and second leak tests are completed, the first gas valve 31 is opened, the vacuum container 1 is exposed to the atmosphere, and the upper and lower resin sheets 4, 4 are tightly attached to the internal components 3. Then, as shown in Figure 3(a), the protruding portions 4f2 of the resin sheets 4, 4 are cut and the resin sheet-sealed component 10 is removed.

[0099] The leak inspection performance of the leak inspection device 100 for sealed resin sheet products according to the first embodiment of the present invention was examined as follows.

[0100] A relatively large electrical appliance was prepared as the built-in component 3. Its dimensions were a rectangular parallelepiped of 1000 mm x 750 mm x 30 mm, and since it was an electrical appliance, it was required to be weather resistant for a long period of several years or more and to be able to block the atmosphere. For this reason, the resin sheet 4 was made of a material with low gas permeability for atmospheric gases, as it was necessary to prevent the penetration of the atmosphere for a long period of several years or more. Therefore, the threshold value (determination value) of the leakage flow rate for the leak test of the resin sheet 4 and the built-in component 3 was set to 1 x 10 ５ 1 x 10 for helium gas equivalent to atmospheric pressure of 10 Pa －７ P.A.M. ３ / s, which is a relatively low leakage flow rate.

[0101] In the above process P1, the built-in component 3 and the two upper and lower resin sheets 4, 4 could be installed in the vacuum vessel 1 without any problems in the form shown in Figure 2(a). Similarly, in the above process P2, the vacuum vessel 1 could be evacuated to a desired pressure (less than 100 Pa) by the first vacuum pump 11. Here, the reason why the pressure in the vacuum vessel 1 was set to less than 100 Pa in the above process P2 is that －７ P.A.M. ３ This is to detect a low leakage flow rate of 1 / s and to set the pressure inside the bags (gap space 5) of the resin sheets 4, 4 to 100 Pa or more for the second leakage test.

[0102] Furthermore, in the above process P3, the welded seal (first welded seal portion 4a) between the inner surfaces of the two upper and lower resin sheets 4, 4 and the welded seal (second welded seal portion 4b) between each inner surface of the two upper and lower resin sheets 4, 4 and each outer surface of the needle connecting jig 14 (flat portion 14a) were able to be formed without any problems.

[0103] Furthermore, the evacuation of the gap space 5 in the process P4, the introduction of helium gas into the gap space 5 in the process P6, and the detection of helium gas leaking from the first welded seal portion 4a and the second welded seal portion 4b into the external vacuum vessel 1 (first leak test) were all carried out without any problems.

[0104] This first leak test was continued until the end of the second leak test, and leaks of helium gas leaking into the external vacuum vessel 1 from the first welded seal portion 4a, the second welded seal portion 4b, and the third welded seal portion 4c were detected.

[0105] The welding of the resin sheet opening 4a1 and the leak inspection thereof in the processes P8 to P11, that is, the pressure in the gap space 5 and the leakage flow rate [Pa m ３ The results of the time transition of the helium leakage flow rate [Pa m / s] are shown in Figure 8. The pressure in the gap space 5 is measured by the second vacuum gauge 17 via the needle pipe 15a, the first pipe 15, and the third pipe 18a.３ / s] is detected by the second helium gas detector 18 via the needle pipe 15a and the first pipe 15. Note that Fig. 8 shows the results when there is no leakage at the third welded seal portion 4c.

[0106] The following describes a leak test (second leak test) for helium gas leaking from the third weld seal portion 4c created by welding the resin sheet opening 4a1 to the first piping 15 side (the needle introduction space 6, the needle pipe 15a, the movable piping 15b, and the inside of the first piping 15).

[0107] As shown in Figure 8, welding of the resin sheet opening 4a1 began two seconds after the start of evacuation by the second vacuum pump 16 and the pressure on the second vacuum gauge 17 reached 1000 Pa. Welding was completed seven seconds later. The pressure on the second vacuum gauge 17 at this time was 240 Pa. Here, assuming that the pressure inside the four resin sheet bags (gap space 5) is 240 Pa, the leakage threshold is 1.0 x 10 －１０ P.A.M. ３ It was estimated at / s.

[0108] Thereafter, evacuation by the second vacuum pump 16 continued, and 15 seconds after the start, the fifth vacuum valve 25 was opened and measurement of the helium leak flow rate was started by the helium gas detector 18. Evacuation by the second vacuum pump 16 and the second helium gas detector 18 continued until 27 seconds after the start. During this time, the helium leak flow rate was 10 －５ P.A.M. ３ / s to 10 －９ P.A.M. ３ / s.

[0109] Then, 27 seconds after the start of the second leak test, the fourth vacuum valve 24 was closed, and only the second helium gas detector 18 was evacuated, and the detection of the helium leak flow rate was continued. The helium leak flow rate was 1×10 after 34 seconds. －１０ P.A.M. ３ / s, and after about 45 seconds, it becomes 1 x 10 －１１ P.A.M. ３ / s. The leakage threshold is 1.0 x 10 －１０ P.A.M. ３ / s, but 10 －１１ P.A.M. ３By waiting until the time t1 / s stabilizes, it can be seen that the second leak test can be completed in about 45 seconds, including the time required for welding and sealing the resin sheet opening 4a1. Since the first leak test took about 30 seconds, the total leak test time using the resin sheet sealed product leak test device 100 of the first embodiment was about 75 seconds (= 30 seconds + 45 seconds).

[0110] As described above, the second leak test was carried out without any problems.

[0111] However, the second leak test of the first embodiment has the following two problems. One is that although welding to the resin sheet opening 4a1 is completed 7 seconds after the start of evacuation, a significant pressure drop (pressure fluctuation) during welding may occur. In this case, the pressure difference between the "pressure in the clearance space 5" and the "pressure measured by the second vacuum gauge 17" also increases. Because the "pressure in the clearance space 5 during welding" cannot be directly measured, the "change in pressure in the clearance space 5" is considered to be almost equal to the "change in pressure measured by the second vacuum gauge 17," and the helium leak flow rate threshold is set based on the "pressure measured by the second vacuum gauge 17 during welding." Therefore, in the worst case scenario, a significant pressure drop measured by the second vacuum gauge 17 during welding could invalidate the set helium leak flow rate threshold, thereby reducing the reliability of the leak test.

[0112] The other is the influence of residual helium in the needle connection jig 14, the first pipe 15, and the second helium gas detector 18. This is because, in the second leak test, the second helium gas detector 18 detected a leak flow rate of 100 s at 15 seconds to 28 seconds after the start of evacuation. －４ P.A.M. ３ / s to 10 －９ P.A.M. ３ / s, helium gas was detected, but at this time, helium may remain in the needle connection jig 14, the first piping 15, and the second helium gas detector 18, making it difficult to perform multiple inspections. Below, we will explain a resin sheet sealed product leak inspection device 200 that solves the above two problems.

[0113] 9 is an explanatory diagram showing the main configuration of a leak inspection device 200 for sealed resin sheet products according to a second embodiment of the present invention. In order to solve the problems of the second leak inspection described above, the leak inspection device 200 for sealed resin sheet products is improved as follows compared to the leak inspection device 100 for sealed resin sheet products according to the first embodiment.

[0114] First, in order to reduce the pressure fluctuation (pressure drop) during welding of the resin sheet opening 4a1 after evacuation, i.e., to reduce the pressure gradient during welding, a vacuum evacuation flow path in which the sixth vacuum valve 26 and the first small conductance component 41 are connected in series is separately connected to the second vacuum pump 16 in parallel with the vacuum evacuation flow path (second piping 16a) from the fourth vacuum valve 24 to the second vacuum pump 16, so that the pressure drop due to evacuation is gradual.

[0115] Here, the conductance value [m ３ / s] is the effective pumping speed S' at the inlet of the needle pipe 15a when the first small conductance component 41 is present. ｅｆｆ [m ３ / s] when there is no effective pumping speed S ｅｆｆ [m ３ The conductance value [m / s] of the first small conductance component 41 is set to a small value. ３ / s] to a small value, the time constant τ of exhaust during welding (= V / S' ｅｆｆ ) becomes longer, which allows the pressure drop during welding to be gradual, and as a result, the pressure on the second vacuum gauge 17 during welding and the pressure filled in the gap space 5 during welding can be considered to be approximately the same.

[0116] Next, in order to reduce residual helium gas in the leak testing device, which makes it difficult to perform multiple tests, a nitrogen gas cylinder 40 is connected to the first pipe 15 via a third gas valve 33 and to the helium gas detector 18 via a fourth gas valve 34. This makes it possible to purge most of the helium gas remaining in the vacuum exhaust system with nitrogen gas after the sealed resin sheet product 10 is removed from the vacuum container 1.

[0117] Using the improved resin sheet sealed product leak inspection device 200, the same leak inspection process as in embodiment 1 was carried out. Here, in order to achieve a gradual pressure drop during the evacuation in the welding process, which was performed 2 to 7 seconds after the start of evacuation, the fourth vacuum valve 24 was closed and the sixth vacuum valve 26 was opened, and evacuation was performed via the first small conductance component 41.

[0118] FIG. 10 is a graph showing the results of the second leak test regarding the pressure before and after welding of the resin sheet opening 4a1 and the time transition of the leakage flow rate of helium leaking from the third weld seal portion 4c to the first piping 15 side.

[0119] Between 2 and 7 seconds after the start of evacuation, the pressure on the second vacuum gauge 17 gradually decreased to 1300 Pa after 2 seconds, 1000 Pa after 5 seconds, and 850 Pa after 7 seconds. The average pressure from 5 to 7 seconds was 930 Pa. This was the pressure on the second vacuum gauge 17 immediately before welding.

[0120] On the other hand, from the effective pumping speed at the inlet of the needle pipe 15a and the effective pumping speed at the second vacuum gauge 17, the pressure immediately before welding of the opening welded portion of the resin sheet 4 (third welded seal portion 4c) could be calculated to be 1100 Pa. This made it possible to set the leak threshold for the second leak test to a substantially constant value without significant variation between tests. This means that by clarifying the sealing pressure of the resin sheet 4, it is thought that it will be possible to improve the quality control of the resin sheet sealed product 10.

[0121] 10, the time transition of the pressure measured by the second vacuum gauge 17 and the leakage flow rate measured by the second helium gas detector 18 after 7 seconds from the start of evacuation was similar to the results of the leak inspection device 100 for sealed resin sheet products of the first embodiment. This is because, after welding after 7 seconds from the start, the volume to be evacuated is small and the evacuation speed is high, so evacuation of several hundred Pa is performed in a short time of less than 1 second.

[0122] The leak test (second leak test) using the second helium gas detector 18 starts at 15 seconds, but the helium leak flow rate after 28 seconds from the start of evacuation using only the second helium gas detector 18 is 1×10 －９ P.A.M.３ / s, and after 34 seconds it becomes 1 x 10 －１０ P.A.M. ３ In the leak test of the second embodiment, the pressure at the resin sheet opening 4a1 immediately before welding was found to be 1100 Pa, so the leak threshold value in the second leak test was 5.6×10 －１０ P.A.M. ３ / s. －１０ P.A.M. ３ It took 30 seconds for the test to reach 1 / s. This shows that the test in the second embodiment is more reliable and can be performed in less time than the first embodiment, in which the threshold value of the leakage flow rate could not be determined.

[0123] Next, in order to reduce residual helium gas within the leak testing device, which makes it difficult to perform multiple tests, after the test is completed, the third vacuum valve 23, the fourth vacuum valve 24, the sixth vacuum valve 26, and the seventh vacuum valve 27 are closed, the third gas valve 33 is opened to flow nitrogen gas from the nitrogen gas cylinder 40, and the first pipe 15 is exposed to atmospheric pressure with nitrogen gas.After that, the third gas valve 33 is closed, the fourth vacuum valve 24 is opened, and the nitrogen gas is evacuated by the second vacuum pump 16.At the same time, the fourth gas valve 34 is opened to flow a small amount of nitrogen gas from the nitrogen gas cylinder 40 while the second helium gas detector 18 is operated. Since the time required from the end of the inspection to the replacement of the resin sheet sealed product 10, the first stage of evacuation of the vacuum vessel 1, the first stage of the welding process of the two upper and lower resin sheets 4, 4 (first weld seal portion 4a, second weld seal 4b), and the introduction of helium gas for the first leak inspection was approximately 20 seconds, it was possible to carry out the process of reducing the residual helium in the first piping 15 twice.

[0124] The residual helium reduction process was performed twice for each test, and the start time of helium leak flow rate detection by the second helium gas detector 18 in the second leak test was set to the helium leak flow rate 10 －５ P.A.M. ３ 10 seconds after / s is detected －７ P.A.M. ３ When the value was changed 20 seconds after the detection of / s and the leak test was performed repeatedly, it was possible to perform up to 100 leak tests.

[0125] As described above, by using the leak inspection device 200 for a sealed resin sheet product according to the second embodiment of the present invention, leak inspections for sealed resin sheet products can be carried out multiple times.

[0126] 11 is an explanatory diagram showing the main configuration of a leak inspection device 300 for sealed resin sheet products according to a third embodiment of the present invention. This leak inspection device 300 for sealed resin sheet products is an improved version of the leak inspection device 200 for sealed resin sheet products according to the second embodiment in terms of the second leak inspection.

[0127] Specifically, in order to determine the helium concentration at the time of completion of welding of the resin sheet opening 4a1 after evacuation, a 2×10 volt helium gas detector 18 was connected to the fifth vacuum valve 25 (third pipe 18a) via the eighth vacuum valve 28 as a vacuum evacuation flow path from the first pipe 15 to the second helium gas detector 18. －１０ m ３ A second small conductance component 42 having a very small conductance value of 2×10 / s was connected. Furthermore, in order to reduce residual helium in the second helium gas detector 18 during helium detection by the second helium gas detector 18 after 15 seconds from the start of evacuation, a ninth vacuum valve 29 was connected in parallel with the fifth vacuum valve 25 (third pipe 18a) via the ninth vacuum valve 29. －６ m ３ A third small conductance 43 having a small conductance value of 1 / s was connected to allow measurement at a low leakage flow rate.

[0128] Using the thus improved resin sheet sealed product leak inspection device 300, the same leak inspection process as in the first embodiment was carried out. Here, from 2 seconds after the start of evacuation until 15 seconds, evacuation was carried out by the second helium gas detector 18 via the second vacuum pump 16, the eighth vacuum valve 28, and the second small conductance component 42. Then, from 15 seconds to 39 seconds, evacuation was carried out by the second helium gas detector 18 via the second vacuum pump 16, the ninth vacuum valve 29, and the third small conductance component 43. Then, from 39 seconds onwards, evacuation was carried out by only the second helium gas detector 18 via the fifth vacuum valve 25.

[0129] FIG. 12 is a graph showing the results of the time transition of the pressure in the gap space 5 when the resin sheet opening 4a1 is welded and the leakage flow rate of helium leaking from the third weld seal portion 4c to the first pipe 15 side.

[0130] Between 2 and 7 seconds after the start of evacuation, the pressure measured by the second vacuum gauge 17 gradually decreased to 1,300 Pa after 2 seconds, 1,000 Pa after 5 seconds, and 850 Pa after 7 seconds. The average pressure measured between 5 and 7 seconds was 930 Pa. This was taken as the pressure measured by the second vacuum gauge 17 immediately before welding. The pressure at the opening welded portion of the resin sheet 4 (resin sheet opening 4a1) immediately before welding was estimated to be 1,080 Pa.

[0131] On the other hand, the helium leakage flow rate detected by the second helium gas detector 18 from 2 seconds to 7 seconds after the start of evacuation was 2.44×10 －７ P.A.M. ３ / s, the leakage flow rate after 5 seconds is 1.88 × 10 －７ P.A.M. ３ / s, and the pressure after 7 seconds is 1.60 x 10 －７ P.A.M. ３ / s. The average leakage flow rate from 5 seconds to 7 seconds was 1.74 × 10 －７ P.A.M. ３ / s. The conductance of the second small conductance element 42 connected to the second helium gas detector 18 was 2×10 －１０ m ３ / s, the helium partial pressure at the position of the second vacuum gauge 17 was estimated to be 869 Pa, and the helium concentration was calculated to be 94%.

[0132] Since the sealing pressure of the resin sheet is 1080 Pa and the helium concentration can be estimated to be 94%, the threshold value of the helium leakage flow rate in the second leak test is 5.1 × 10 －１０ P.A.M. ３ / s. In this way, the leak inspection device 300 for sealed resin sheet products according to the third embodiment can specify the threshold value of the leakage flow rate for each inspection, and therefore can perform highly reliable inspections.

[0133] The helium leak rate from 15 seconds to 38 seconds in FIG. －６P.A.M. ３ / s to 6 x 10 －１１ P.A.M. ３ / s. This is 2 x 10 －６ m ３ This is because helium gas is introduced into the second helium gas detector 18 via the third small conductance component 43 having a small conductance value of 1 / s, and it can be seen that the countermeasure against residual helium is working effectively.

[0134] Next, after 38 seconds when helium gas was introduced only into the second helium gas detector 18, the helium leakage flow rate was 1×10 －９ P.A.M. ３ / s to 1 x 10 after 46 seconds －１０ P.A.M. ３ / s. The helium leak flow rate measured in this second leak test reached the threshold value of 5.1 × 10 －１０ P.A.M. ３ The time required for the pressure to reach or fall below 1 / s was approximately 42 seconds. This time was approximately 10 seconds longer than that in the second embodiment 2, but this was because helium gas was introduced into the second helium gas detector 18 via the second small conductance component 43 during the evacuation 15 seconds after the start of evacuation.

[0135] On the other hand, when a leak test was performed using the process of the third embodiment and the residual helium reduction process using nitrogen gas was carried out twice for each test after the test was completed, the second helium gas detector 18 remained stable even after 200 leak tests.

[0136] As described above, by using the leak inspection device 300 for a sealed resin sheet product of the third embodiment, precise leak inspections of the sealed resin sheet product 10 can be performed many times.

[0137] (Fourth embodiment) The leakage threshold of the detection gas in the first leakage test is 10 －８ P.A.M. ３When the gas permeability drops to the order of / s or less, it is necessary to reduce gas permeation through the resin pipe connection jig 14 that connects the "gap space 5 formed between the resin sheets 4, 4 and the built-in component 3" and the "metal pipe (first pipe 15) for supplying the detection gas." This is because the resin used for the pipe connection jig 14 is an easily weldable resin, and these resins have high gas permeability.

[0138] FIG. 13 is an explanatory diagram showing the main configuration of a pipe connection jig 14' of a resin sheet sealed product leak inspection device according to a fourth embodiment of the present invention. This pipe connection jig 14' has a male fitting portion 14b', which serves as the probe gas introduction and evacuation portion for the clearance space 5, in a thin pipe shape (small hollow cylinder), reducing the gas permeation area and suppressing the amount of gas permeation. Specifically, as shown in FIG. 13(a), the male fitting portion 14b' does not have the flat portion 14a of the needle connection jig 14, and the axial length of the male fitting portion 14b is extended and the outer diameter is reduced to form a thin pipe shape. On the other hand, the female fitting portion 14c' replaces the two-stage cylindrical shape of the needle connection jig 14 with a single-stage cylindrical shape with a smaller outer diameter.

[0139] The male fitting portion 14b' is made of a high-hardness resin (easily weldable resin) that is the same as or compatible with the resin sheet 4. The female fitting portion 14c' is made of metal.

[0140] As shown in FIG. 13(b), it can be seen that both the male fitting portion 14b' and the female fitting portion 14c' are miniaturized, resulting in a smaller gas permeable area.

[0141] 13(c), the opening 4a1 of the resin sheet 4 is sealed by welding the inner circumferential surfaces of the resin sheet 4. Therefore, in the second leak test, the leakage flow rate of the detection gas leaking from the third weld seal portion 4c to the first piping 15 side is detected by the second helium gas detector 18.

[0142] Although the first pipe 15 is directly connected to the female fitting portion 14c', it may be connected to the female fitting portion 14c' using a needle pipe 15a and a movable pipe 15b.

[0143] A leak test was carried out using a thin pipe-shaped pipe connection jig 14' in the same manner as in the first embodiment. The leak threshold value for the first leak test was 1×10 －８ P.A.M. ３ Although the leak flow rate was very small at 1 / s, the first leak test was carried out without any problems in 30 seconds.

[0144] Next, a second leak test was performed using the resin sheet sealed product leak test device 300. Here, from 4 seconds after the start of evacuation until 30 seconds after, evacuation was performed by the second vacuum pump 16, the eighth vacuum valve 28, and the second small conductance component 42 via the second helium gas detector 18. Then, from 30 seconds after the start of evacuation until 62 seconds after, evacuation was performed by the second vacuum pump 16, the ninth vacuum valve 29, and the third small conductance component 43 via the second helium gas detector 18. Then, from 62 seconds after the start of evacuation until 30 seconds after, evacuation was performed by the fifth vacuum valve 25 using only the second helium gas detector 18.

[0145] 14 is a graph showing the results of the time transition of the pressure in the gap space 5 when the resin sheet opening 4a1 is welded and the helium leakage flow rate leaking from the fourth weld seal portion 4d to the first piping 15 side. From 4 seconds to 9 seconds after the start of evacuation, the pressure on the second vacuum gauge 17 gradually decreased from 950 Pa at 4 seconds, to 870 Pa at 7 seconds, and to 630 Pa at 9 seconds. The average value of the pressure from 7 seconds to 9 seconds was 680 Pa. This was the pressure on the second vacuum gauge 17 immediately before welding. The pressure immediately before welding the resin sheet opening 4a1 was estimated to be 1020 Pa.

[0146] On the other hand, the helium leakage flow rate detected by the second helium gas detector 18 from 4 seconds to 9 seconds after the start of evacuation was 1.82×10 －７ P.A.M. ３ / s, and the leakage flow rate after 7 seconds is 1.40 x 10 －７ P.A.M. ３ / s, and the pressure after 9 seconds is 1.21 x 10 －７ P.A.M. ３ / s. The average leakage flow rate from 7 seconds to 9 seconds was 1.30 × 10 －７ P.A.M. ３ / s. The conductance of the second small conductance element 42 connected to the second helium gas detector 18 was 2×10 －１０ m3 / s, the helium partial pressure at the position of the second vacuum gauge 17 was estimated to be 650 Pa, and the helium concentration was calculated to be 95%.

[0147] Since the sealing pressure of the resin sheet is 1020 Pa and the helium concentration can be estimated to be 95%, the threshold value of the helium leakage flow rate in the second leak test is 5.8 × 10 －１１ P.A.M. ３ / s.

[0148] The helium leak flow rate from 30 seconds to 62 seconds in Figure 14 is 1.7 × 10 －７ P.A.M. ３ / s to 1 × 10 －１０ P.A.M. ３ / s. This is 2 x 10 －６ m ３ This is because helium gas is introduced into the second helium gas detector 18 via the third small conductance component 43 having a small conductance value of 1 / s.

[0149] Next, after 62 seconds when helium gas was introduced only into the second helium gas detector 18, the helium leakage flow rate was 1×10 －１０ P.A.M. ３ / s to 1 x 10 after 86 seconds －１１ P.A.M. ３ / s. The helium leak flow rate measured in this second leak test reached the threshold value of 5.8 × 10 －１１ P.A.M. ３ The time required to reach 1 / s or less was approximately 76 seconds. This time was approximately 35 seconds longer than that of the third embodiment, but this is due to the small conductance of the thin pipe-shaped pipe connection jig 14'. Note that the time required for the first leak test was approximately 30 seconds, so the leak test time for the resin sheet sealed product leak test device 300 using the thin pipe-shaped pipe connection jig 14' of the fourth embodiment was approximately 106 seconds (= 30 seconds + 76 seconds).

[0150] As described above, by using the resin sheet sealed product leak inspection device 300 equipped with the thin pipe piping connection jig 14' of the fourth embodiment, precise leak inspection of the resin sheet sealed product 10 can be carried out many times.

[0151] (Fifth embodiment) Figure 15 is an explanatory diagram showing the main configuration of a pipe connection jig 14" of a resin sheet sealed product leak inspection device according to a fifth embodiment of the present invention. This pipe connection jig 14" has a double-tube structure for the male fitting portion 14b', which serves as the portion for introducing and evacuating the probe gas into the gap space 5, and supplies the probe gas to the inner tube 14ba', but suppresses permeation of the probe gas into the vacuum container 1 by evacuating the space between the outer tube 14bb and the inner tube 14ba'. In detail, as shown in Figure 15(a), the male fitting portion 14b" does not have the flat portion 14a that the needle connecting jig 14 has, and the axial length of the male fitting portion 14b is extended to form a double-tube structure consisting of an inner tube 14ba' and an outer tube 14bb. On the other hand, the female fitting portion 14c" has a medium-diameter portion 14ce that is larger than the outer diameter of the inner tube 14ba' and smaller than the inner diameter of the outer tube 14bb, and an O-ring 14cf that maintains the airtightness of the inner tube 14ba'. Furthermore, a vacuum exhaust path 14cg is provided in the medium-diameter portion 14ce to recover the detection gas that permeates from the inner tube 14ba'.

[0152] The male fitting portion 14b'' is made of a high-hardness resin (easily weldable resin) that is the same as or compatible with the resin sheet 4. The female fitting portion 14c'' is made of metal.

[0153] As shown in FIG. 15(b), it can be seen that the male fitting portion 14b'' has a double-tube structure consisting of an inner tube 14ba' and an outer tube 14bb.

[0154] 15(c), the opening 4a1 of the resin sheet 4 is sealed by welding the inner circumferential surfaces of the resin sheet 4. Therefore, in the second leak test, the leakage flow rate of the detection gas leaking from the third welded seal portion 4c to the first piping 15 side is detected by the second helium gas detector 18.

[0155] Although the first pipe 15 is directly connected to the female fitting portion 14c'', it may be connected to the female fitting portion 14c' using a needle pipe 15a and a movable pipe 15b.

[0156] The embodiments of the present invention have been described above with reference to the drawings. The embodiments of the present invention are not limited to those described above, and various modifications and variations can be made without departing from the technical features of the present invention. For example, other gases (e.g., hydrogen, argon, or air) can be used instead of helium as the detection gas. Furthermore, instead of a helium leak detector, a quadrupole mass spectrometer or a discharge emission gas analyzer can be used as the detection gas detector.

[0157] The shape of the welded seal portion is not limited to the convex polygonal shape described above, and may be any closed curve with a "starting point and an ending point coinciding" that has a "protruding portion" that can seal the built-in component 3 between the upper and lower resin sheets 4 and sandwich the flat portion 14 a. The outer shape of the welding device (heat sealer) that forms the welded seal portion is also not limited to the shapes described above, and may be any shape that can weld and seal the inner peripheral surfaces of the resin sheets 4, or the inner peripheral surface of the resin sheet 4 and the outer peripheral surface of the flat portion 14 a in a desired shape.

[0158] Furthermore, the first weld seal portion 4a, the second weld seal portion 4b, and the third weld seal portion 4c may be formed by a single welding device. Explanation of symbols

[0159] REFERENCE SIGNS LIST 1 vacuum vessel 2-1 first welding device 2-2 second welding device 3 built-in components 4 resin sheet 4 resin sheet 4a first welding seal portion 4a1 resin sheet opening 4b second welding seal portion 4c third welding seal portion 4f bottom portion 4f1 square frame portion 4f2 protruding portion 5 gap space 6 needle introduction space (piping introduction space) 10 resin sheet sealed component 11 first vacuum pump 12 first vacuum gauge 13 first helium gas detector 14 needle connection jig (piping connection jig) 14a flat portion 14aa through hole 14b male fitting portion 14b' male fitting portion 14b" male fitting portion 14ba through hole 14ba' inner tube 14bb outer tube 14c female fitting portion 14c' Female fitting portion 14c" Female fitting portion 14ca Large diameter portion 14cb Small diameter portion 14cc O-ring 14cd O-ring 15 First pipe 15a Needle pipe (piping) 15b Movable pipe 16 Second vacuum pump 16a Second pipe 17 Second vacuum gauge 18 Second helium gas detector 18a Third pipe 19 Helium gas cylinder 19a Fourth pipe 21 First vacuum valve 22 Second vacuum valve 23 Third vacuum valve 24 Fourth vacuum valve 25 Fifth vacuum valve 26 Sixth vacuum valve 27 Seventh vacuum valve 31 First gas valve 32 Second gas valve 33 Third gas valve 34 Fourth gas valve 40 Nitrogen gas cylinder 40a Fifth pipe 41 First small conductance part 42 Second small conductance part 43 Third small conductance component 100 Resin sheet sealed product leak inspection device 200 Resin sheet sealed product leak inspection device 300 Resin sheet sealed product leak inspection device

Claims

1. A resin sheet sealed product leak inspection method in which a resin sheet sealed product (10) in which an internal component (3) is tightly sealed in a vacuum state by welding two upper and lower resin sheets (4, 4) is placed inside a vacuum container (1) maintained at a specified vacuum level, and a leak inspection is performed using a detection gas. When covering the internal component (3) with the resin sheets (4, 4), a pipe connection jig (14) for vacuum exhaust or detection gas introduction is sandwiched between parts of the resin sheets (4, 4), forming a welded seal part (4a, 4b) "so as to include the internal component (3) inside and form a protruding part (b2-b1-b1-b2) that protrudes outward in part," a first leak test is performed to detect the detection gas leaking from the welded seal portion (4a, 4b) into the external vacuum container (1), by introducing a detection gas from a narrow resin sheet opening (4a1) formed in the protruding portion (b2-b1-b1-b2) into a gap space (5) formed between the resin sheet (4, 4) and the built-in component (3) and the protruding portion (b2-b1-b1-b2); and a second leak test is performed to detect the detection gas leaking from the welded seal portion (4a, 4b) into the external vacuum container (1). The gap space (5) is then evacuated to a pressure at which "a sufficient amount of detection gas remains below atmospheric pressure to detect a leakage flow rate." A second leak test is then performed to form a welded seal portion (4c) that seals the resin sheet opening (4a1), and a second leak test is performed to detect the detection gas leaking from the welded seal portion (4c) to the downstream side of the piping connection jig (14).

2. A method for inspecting a resin sheet sealed product for leaks as described in claim 1, characterized in that the first leak inspection is continued until the end of the second leak inspection, thereby detecting detection gas leaking from "the welded seal portion (4c) associated with the resin sheet opening portion (4a1)" into the external vacuum container (1) in addition to the welded seal portions (4a, 4b).

3. A method for inspecting leaks in sealed resin sheet products as defined in claim 1, characterized in that the resin sheets (4, 4) are welded and sealed so that the protruding portion (b2-b1-b1-b2) crosses the piping connection jig (14), and a portion (14a) of the piping connection jig (14) that is sandwiched between the resin sheets (4, 4) is formed to be a flat portion (14a).

4. A method for inspecting leaks in sealed resin sheet products as claimed in claim 1, characterized in that the pipe (15a) can move back and forth inside the pipe connection jig (14) while maintaining airtightness.

5. A method for inspecting leaks in sealed resin sheet products as claimed in claim 1, characterized in that a recess (4r) into which the built-in component (3) fits is formed in the centre of the resin sheet (4), and the bottom portions (4f, 4f) of the recess (4r) are made into a convex shape combining a square frame portion (4f1) and a protruding portion (4f2).

6. A method for inspecting a resin sheet sealed product for leaks as claimed in claim 1, characterized in that when the gap space (5) is evacuated to a predetermined pressure and the resin sheet opening (4a1) is welded, the pressure fluctuation in the gap space (5) is made smaller than the pressure fluctuation at the start of evacuation, and then the opening is welded and sealed.

7. A method for leak inspection of a resin sheet sealed product as described in claim 6, characterized in that, when carrying out the second leak inspection, the flow rate of the probe gas introduced into a probe gas detector (18) which measures the leakage flow rate of the probe gas is made smaller than the flow rate of the probe gas introduced into a vacuum pump (16) which evacuates "the welded seal portion (4c) relating to the resin sheet opening (4a1)".

8. A method for inspecting leaks in sealed resin sheet products as described in claim 7, characterized in that after measuring the leakage flow rate of the detection gas leaking from "the welded seal portion (4c) relating to the resin sheet opening (4a1)" to the downstream side of the piping connection jig (14), a vacuum exhaust system and a leakage flow rate measurement system are purged with an inert gas other than the detection gas.

9. A vacuum vessel (1) that houses an internal component (3) covered with a resin sheet (4, 4) and a piping connection jig (14) sandwiched between a part of the resin sheet (4, 4) under a predetermined vacuum environment; a first vacuum pump (11) that evacuates the internal space of the vacuum vessel (1) formed around the internal component (3); a pair of first welding devices (2-1) that weld the overlapping parts (4f, 4f) of the resin sheet (4, 4) into a convex shape along the outer periphery to form a convex welded seal part (4a, 4b); a second vacuum pump (16) that evacuates the gap space (5) formed between the resin sheet (4, 4) and the internal component (3); a search gas source (19) that introduces a search gas into the gap space (5); and a first pipe (15) that is connected to the gap space (5), the second vacuum pump (16), and the search gas source (19), respectively. a first detection gas detector (13) that detects a leakage flow rate of the detection gas leaking from the convex-shaped welded seal portion (4a, 4b) into the inside of the external vacuum vessel (1); a pair of second welding devices (2-2) that weld a narrow resin sheet opening (4a1) sandwiched between two recessed corners (b2, b2) of the convex-shaped welded seal portion (4a, 4b) to form a linear welded seal portion (4c); and a second detection gas detector (18) that detects the leakage flow rate of the detection gas leaking from the linear welded seal portion (4c) to the downstream side of the first piping (15) through the piping connection jig (14).

10. A resin sheet sealed product leak inspection device as described in claim 9, wherein the piping connection jig (14) comprises a molded product having a "flat portion (14a) and a cylindrical portion (14b) integrally molded from a resin compatible with the resin sheet (4, 4)" with an internal through-hole (14aa, 14ba), and the flat portion (14a) is sandwiched by a portion (4f2, 4f2) of the overlapping portion (4f, 4f) of the resin sheet (4, 4) that protrudes outward from the resin sheet opening (4a1).

11. A resin sheet sealed product leak inspection device as described in claim 10, characterized in that a pipe (15a) connected to the first pipe (15) via a flexible movable pipe (15b) is arranged in the penetration portion (14aa, 14ba) so as to be freely movable back and forth.

12. A resin sheet sealed product leak inspection device as described in claim 11, characterized in that a through hole (14aa) is formed inside the flat portion (14a) through which the piping (15a) can move back and forth.

13. A resin sheet sealed product leak inspection device as described in claim 11, wherein the piping connection jig (14) has a separate metallic female cylindrical portion (14c) having a large diameter portion (14ca) into which the cylindrical portion (14b) fits and a small diameter portion (14cb) through which the piping (15a) passes, and sealing members (14cc, 14cd) for maintaining airtightness are provided between the cylindrical portion (14b) and the large diameter portion (14ca), and between the piping (15a) and the small diameter portion (14cb).

14. A resin sheet sealed product leakage inspection device as described in claim 9, characterized in that the bottom portion (4f) of the resin sheet (4) has a convex shape formed by combining a square frame portion (4f1) and a protruding portion (4f2), and a recess (4r) into which the built-in component (3) fits is formed on the inside of the bottom portion (4f).

15. A resin sheet sealed product leak inspection device as described in claim 9, characterized in that one or more small conductance components (41) having a smaller conductance value than the second pipe (16a) are connected in parallel to the second pipe (16a) connecting the first pipe (15) and the second vacuum pump (16).

16. A resin sheet sealed product leak inspection device as described in claim 9, characterized in that one or more small conductance components (42, 43) having a smaller conductance value than a third pipe (18a) are connected in parallel to the third pipe (18a) connecting the first pipe (15) and the second gas detector (18).

17. A resin sheet sealed product leak inspection device as described in claim 9, characterized in that an inert gas other than the detection gas can be supplied in parallel to the second vacuum pump (16) and the second detection gas detector (18).

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