JP2011226899A - Airtightness inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an airtightness inspection device which carries out a leakage inspection of a sealed container of a sealed compressor with high accuracy using a inspection gas that is availably low-cost, and in which a facility can be downsized.SOLUTION: An airtightness inspection device according to the present invention comprises: a plurality of chambers that are mounted on a transport device formed into a vertical cylinder, move on the transport device, and houses a sealed container therein; a space formed around the sealed container in the chamber; a hydrogen gas mixture filling section which fills the sealed container mounted on the transport device and housed in the chamber with hydrogen gas mixture of a first predetermined pressure; a hydrogen gas mixture accumulation section which is laid down over a predetermined length that the transport device moves along and accumulates hydrogen gas mixture in the space; and a hydrogen gas detection section which is provided on a predetermined position of the transport device, adds dried air to the sealed container so that the dried air becomes a second predetermined pressure equivalent to a predetermined airtightness test pressure and detects hydrogen gas leaking into the space.

Description

  The present invention relates to an airtightness inspection apparatus that inspects confidentiality of a hermetic container of a hermetic compressor used in a refrigeration cycle such as a refrigeration apparatus, an air conditioner, and a hot water supply apparatus.

  In a conventional method for inspecting airtightness of a hollow container, for example, helium is used as an inspection gas, and the hollow container is accommodated in a chamber to be inspected. A method for inspecting the airtightness of a hollow container has been proposed in which helium gas is sealed in a hermetically sealed hollow container and the quality of the airtightness of the hollow container is accurately inspected by detecting the helium gas leaking into the chamber. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 4-89542 (2nd page, upper left column, FIG. 1)

  However, leak inspection using helium gas can be inspected with high accuracy, but helium gas is not usually present in the atmosphere, and cannot be synthesized and manufactured. There was a problem that it was difficult to use because there was concern about price increase and depletion because it was only produced from some areas. In addition, there is a problem that the equipment becomes large, for example, a large tank for storing helium gas is required.

  The present invention was made to solve the above-described problems. Leakage inspection of a sealed container of a hermetic compressor can be performed with high accuracy by using an easily available and inexpensive inspection gas, and equipment. Provided is an airtightness inspection apparatus that can be miniaturized.

An airtightness inspection apparatus according to the present invention includes a conveyance device formed in an annular shape,
A plurality of chambers that are placed on the transfer device and move on the transfer device, and housed in a hermetically sealed airtight container without communicating with the outside,
A gap formed around the sealed container in the chamber;
A hydrogen mixed gas enclosing unit that encloses the hydrogen mixed gas at a predetermined first pressure in a sealed container provided in a predetermined position of the transfer device and housed in the chamber;
A hydrogen mixed gas depositing unit that is provided over a predetermined length in the moving direction of the transfer device following the hydrogen mixed gas sealing unit, and in which the hydrogen mixed gas is deposited in the gap,
Following the hydrogen mixed gas deposition section, the dry air is provided in a predetermined position of the transfer device, and dry air is added to the sealed container so as to become a predetermined second pressure corresponding to a predetermined airtight test pressure, and in the gap. And a hydrogen gas detector for detecting leaked hydrogen gas.

An airtightness inspection apparatus according to the present invention includes a conveyance device formed in an annular shape,
A plurality of chambers that are placed on the transfer device and move on the transfer device, and housed in a hermetically sealed airtight container without communicating with the outside,
A gap formed around the sealed container in the chamber;
A hydrogen mixed gas enclosing unit that encloses the hydrogen mixed gas at a predetermined pressure in a sealed container that is provided at a predetermined position of the transfer device and is housed in the chamber;
A hydrogen mixed gas depositing unit that is provided over a predetermined length in the moving direction of the transfer device following the hydrogen mixed gas sealing unit, and in which the hydrogen mixed gas is deposited in the gap,
A hydrogen gas detector that is provided at a predetermined position of the transfer device and detects the hydrogen gas leaking into the gap, following the hydrogen mixed gas deposition unit.

  The airtightness inspection apparatus according to the present invention can perform leak inspection of a hermetic container of a hermetic compressor, etc. with high accuracy by using an easily available and inexpensive inspection gas (hydrogen mixed gas + dry air), and can reduce the size of the equipment. Can be

FIG. 2 shows the first embodiment, and is an overall schematic configuration diagram of an airtightness inspection apparatus 100. FIG. FIG. 3 shows the first embodiment, and is a front view of the hermetic compressor 10 to be inspected by the airtightness inspection apparatus 100. FIG. FIG. 3 shows the first embodiment, and is a longitudinal sectional view of the hermetic compressor 10. The X section enlarged view of FIG. FIG. 3 is a diagram showing the first embodiment, and is a front view of the chamber 20 in a state where a lid 22 is opened before the hermetic compressor 10 is housed. FIG. 5 shows the first embodiment and is a front view of the chamber 20 in a state where the hermetic compressor 10 to which the couplers 27a and 28a are connected is accommodated and the lid portion 22 is opened. FIG. 5 is a diagram showing the first embodiment, and is a plan view of the chamber 20 in a state in which the lid portion 22 is omitted by approximately 90 degrees and the suction side coupler housing portion 25 and the discharge side coupler housing portion 26 are omitted. FIG. 5 shows the first embodiment, and is a front view of the chamber 20 in a state where a lid portion 22 is closed. FIG. 5 shows the first embodiment, and is a circuit diagram for explaining a circuit for decompression and gas filling connected to the chamber 20 by the hydrogen gas filling unit 40 of the airtightness inspection apparatus 100. FIG. 3 is a diagram illustrating the first embodiment and is a circuit diagram illustrating a circuit for decompression and gas filling connected to the chamber 20 by the leak test unit 50 of the airtightness inspection apparatus 100. FIG. 3 is a diagram illustrating the first embodiment and is a schematic circuit diagram illustrating the principle of a hydrogen gas detector. FIG. 5 shows the first embodiment, and shows the result of a hydrogen gas detection simulation experiment performed by the airtightness inspection apparatus 100. FIG. FIG. 5 shows the first embodiment and is a flowchart for explaining an inspection method of the airtightness inspection apparatus 100. FIG.

Embodiment 1 FIG.
Hereinafter, the airtightness inspection apparatus 100 will be described with reference to FIGS. 1 to 13. Here, the hermetic compressor 10 (sealed container) will be described as an example of the target of the airtightness inspection apparatus 100. However, the target of the airtightness inspection apparatus 100 is not limited to the hermetic compressor 10, but covers hermetic containers (hollow containers) in various fields.

  FIG. 1 to FIG. 13 are diagrams showing Embodiment 1, FIG. 1 is an overall schematic configuration diagram of an airtightness inspection apparatus 100, and FIG. 2 is a front view of a hermetic compressor 10 to be inspected by the airtightness inspection apparatus 100. 3 is a longitudinal sectional view of the hermetic compressor 10, FIG. 4 is an enlarged view of a portion X in FIG. 3, and FIG. 5 is a front view of the chamber 20 with the lid portion 22 before the hermetic compressor 10 is accommodated. 6 is a front view of the chamber 20 in a state where the hermetic compressor 10 to which the couplers 27a and 28a are connected is accommodated and the lid portion 22 is opened, and FIG. 7 is a suction side coupler accommodating portion 25 and a discharge side coupler accommodating portion 26. FIG. 8 is a front view of the chamber 20 with the lid portion 22 closed, and FIG. 9 is a hydrogen gas of the hermeticity testing apparatus 100. The circuit of decompression and gas sealing connected to the chamber 20 by the sealing part 40 is explained. FIG. 10 is a circuit diagram for explaining a circuit for decompression and gas filling connected to the chamber 20 in the leak test section 50 of the airtightness inspection apparatus 100, and FIG. 11 is a schematic circuit for explaining the principle of the hydrogen gas detector. FIG. 12, FIG. 12 is a diagram showing a hydrogen gas detection simulation experiment result of the airtightness inspection apparatus 100, and FIG. 13 is a flowchart for explaining an inspection method of the airtightness inspection apparatus 100.

  The airtightness inspection apparatus 100 shown in FIG. 1 inspects the airtightness of the airtight container 12 by inspecting whether there is any leakage from a joint portion such as a welded portion of the airtight container 12 such as the airtight compressor 10 described later. is there. A plurality of chambers 20 (inspection chambers) each storing the hermetic compressor 10 to be inspected are circulated by a conveyor 30 (conveying device), and each process described later is performed at a predetermined position. Perform a leak test. 1 indicates the direction in which the chamber 20 moves.

The conveyor 30 that circulates the chamber 20 includes the following elements.
(1) Upper conveyor 30a moving in the horizontal direction (moving from right to left in FIG. 1);
(2) A lifter 30b (first lifter) that moves up and down from one end (left end in FIG. 1) of the upper conveyor 30a and connects to one end (left end in FIG. 1) of the lower conveyor 30c;
(3) A lower conveyor 30c that moves in the horizontal direction opposite to the upper conveyor 30a (moves from left to right in FIG. 1);
(4) A lifter 30d (second lifter) that moves in the vertical direction from the other end (right end in FIG. 1) of the lower conveyor 30c and is connected to the other end (right end in FIG. 1) of the upper conveyor 30a.

  Each of the chambers 20 is configured to pass through the upper conveyor 30a, the lifter 30b, the lower conveyor 30c, and the lifter 30d connected in a ring shape, and be conveyed again to the upper conveyor 30a.

The operation of the airtightness inspection apparatus 100 is briefly summarized as follows.
(1) The hermetic compressor 10 is accommodated in the chamber 20 at a substantially central position in the horizontal direction of the upper conveyor 30a (A in FIG. 1);
(2) In the hydrogen gas enclosure 40 (hydrogen mixed gas enclosure) provided at a position slightly moved from the substantially horizontal center position of the upper conveyor 30a to the lifter 30b side (position slightly moved to the left side in FIG. 1). Hydrogen gas for inspection is sealed in the hermetic compressor 10 in the chamber 20 (B in FIG. 1);
(3) If the chamber 20 moves to the lower conveyor 30c and the hermeticity of the hermetic compressor 10 is defective, the lower conveyor 30c leaks into the chamber 20 during movement (C in FIG. 1). This part is defined as “hydrogen mixed gas deposition part”;
(4) A leak test unit 50 (leak measurement unit, hydrogen gas) that measures leakage of hydrogen gas provided on the opposite side of the upper conveyor 30a from the hydrogen gas enclosure 40 (on the right side of the hydrogen gas enclosure 40 in FIG. 1). The detection unit) measures the concentration of the leaked hydrogen gas and determines whether the hermeticity of the hermetic compressor 10 is good (D in FIG. 1).

  Next, the hermetic compressor 10 as an example of a hermetic container will be described in more detail. The hermetic compressor 10 compresses a refrigerant used in a refrigeration cycle such as an air conditioner, a refrigerator, and a water heater. Examples of the hermetic compressor 10 include a rotary compressor, a scroll compressor, and a reciprocating compressor. The rotary compressor and the scroll compressor are a high-pressure shell type in which the inside of the hermetic container has a high pressure, and a low-pressure shell type in which the inside of the reciprocating compressor hermetic container has a low pressure. A shell is synonymous with an airtight container.

  An example of the hermetic compressor 10 will be described with reference to FIGS. The hermetic compressor 10 described here is a one-cylinder rotary compressor.

  The hermetic compressor 10 houses a compression element 10a and an electric element 10b (electric motor) that drives the compression element 10a (compression mechanism) in a hermetic container 12. Moreover, the refrigerator oil 18 which lubricates the sliding part of the compression element 10a is stored in the bottom part of the airtight container 12 (refer FIG. 3).

  The compression element 10a and the electric element 10b of the rotary compressor have the same configuration as a known one, and a detailed description thereof will be omitted.

  The hermetic container 12 of the hermetic compressor 10 includes, for example, a body part 12b (cylinder part), an upper container 12a, and a lower container 12c, which are joined by welding.

  A suction muffler 15 is provided outside the sealed container 12. The suction muffler 15 includes a suction pipe 11 connected to the low pressure side of the refrigeration cycle. The suction pipe 11 has a flange 11a (see FIG. 4) that is expanded at the tip in order to connect a later-described suction-side coupler 27a. The suction muffler 15 is fixed to the sealed container 12 by welding.

  Low-pressure refrigerant is sucked into the compression element 10a from the suction muffler 15. The compression element 10 a compresses the low-pressure refrigerant and discharges the high-pressure refrigerant into the sealed container 12. Accordingly, the sealed container 12 is filled with a high-pressure refrigerant.

  The high-pressure refrigerant in the sealed container 12 passes through the electric element 10b (cools) and flows out from the discharge pipe 16 to the high-pressure side of the refrigeration cycle. The discharge pipe 16 has a flange 16a (see FIG. 4) that is expanded at the tip in order to connect a discharge-side coupler 28a described later.

For example, the hermetic compressor 10 for a hot water heater using a carbon dioxide refrigerant (Co ₂ refrigerant) is used at a very high pressure such that the inside of the hermetic container 12 becomes 10 MPa (megapascal) or more. It is essential to check the airtightness for leakage from the welded portion of the container 12.

  Next, a detailed configuration of the chamber 20 will be described with reference to FIGS. The chamber 20 is formed of a metal member such as stainless steel so as to have a sufficient strength and ensure a pressure resistance. The shape of the chamber 20 is formed in a square box shape, for example. The rectangular box-shaped chamber 20 is formed into a front part and a rear part by a body part 21 and a lid part 22 attached to the body part 21 so as to be freely opened and closed. In order to house the hermetic compressor 10 inside the chamber 20, the inner side of the main body portion 21 and the lid portion 22 facing (facing each other) is slightly wider than the outer shape of the hermetic compressor 10 over the entire outer shape. Thus, the recessed storage portion 23 is formed.

  In the upper part of the chamber 20, a suction-side coupler 27 a and a discharge-side coupler 27 a for allowing a hydrogen gas for inspection to be sealed from the outside into the suction pipe 11 and the discharge pipe 16 of the hermetic compressor 10 housed in the chamber 20. A suction-side coupler housing portion 25 for housing the coupler 28a and a discharge-side coupler housing portion 26 are formed.

  A tray 24 on which the hermetic compressor 10 is placed is provided in the chamber 20. On the upper surface of the tray 24, a recess (concave portion) having substantially the same shape as the outer shape of the foot portion of the hermetic compressor 10 is formed. The hermetic compressor 10 is placed on the tray 24 and stored in the main body 21 of the chamber 20. At this time, the hermetic compressor 10 is arranged such that a gap 23a is formed (see FIG. 6). The tray 24 is preferably formed of a resin material such as plastic having a shape that allows the hermetic compressor 10 to be stably mounted and having sufficient strength and wear resistance.

  Further, packing 90 made of an elastic member such as rubber stretched around the entire circumference of the storage portion 23 is provided on both the main body portion 21 and the lid portion 22 of the chamber 20. The packing 90 seals the outer periphery of the gap 23a, thereby preventing the gas from flowing outside the chamber 20 and inside the gap 23a, thereby improving the airtightness of the gap 23a.

  With the lid portion 22 of the chamber 20 open, a coupler 27a and a coupler 28a are mounted on the suction pipe 11 and the discharge pipe 16 of the hermetic compressor 10 placed on the tray 24, respectively. The couplers 27a and 28a use the flange portions 11a and 16a (see FIG. 4) formed at the distal ends of the suction pipe 11 and the discharge pipe 16 to keep the suction pipe 11 and the discharge pipe 16 airtight. It is attached with.

  After the couplers 27a and 28a are attached to the suction pipe 11 and the discharge pipe 16, the lid portion 22 is closed. A fixing member 22a is formed on the lid portion 22 (see FIG. 7), and a predetermined pressure is applied to the packing 90 by engaging with the hook portion 21a (see FIG. 7) of the main body portion 21. The main body 21 and the lid 22 are securely fixed.

  At this time, the entire circumference of the coupler 27a and the coupler 28a is sealed by the packing 90 of the main body portion 21 and the lid portion 22, so that gas does not leak to the outside through the gap 23a and the outer circumference of the coupler 27a and coupler 28a. It has become.

  FIG. 8 shows a state in which the coupler 27a and the coupler 28a are attached to the hermetic compressor 10 and the lid portion 22 is closed. The first connection passage 29 and the second connection passage 31 to the gap 23a so that the gas (hydrogen) in the gap 23a can be taken out from the outside of the chamber 20 for leak inspection and the gap 23a can be decompressed. Are formed above and below the chamber 20. At the outlet of the first connection passage 29, a first connection port 29a is formed for detachably connecting a pump or the like described later. Similarly, a second connection port 31 a is formed at the outlet of the second connection passage 31.

  The couplers 27a and 28a are in communication with each other when a pair of other couplers (described later) is attached. However, in the case of the couplers 27a and 28a alone, communication with the outside is blocked by a valve mechanism (not shown). ing.

  The couplers 27a and 28a are attached to the hermetic compressor 10 in FIG. 1A (the hermetic compressor 10 is housed in the chamber 20 at a substantially central position in the horizontal direction of the upper conveyor 30a). D (The leak test unit 50 (leak measurement unit) that measures the leakage of hydrogen gas from the upper conveyor 30a measures the concentration of the leaked hydrogen gas and determines whether the hermeticity of the hermetic compressor 10 is good or bad. ) Until the process of () is completed. When the leak test (air tightness test) is completed, the couplers 27 a and 28 a are removed from the hermetic compressor 10.

  As shown in FIG. 6, when the hermetic compressor 10 is housed in the housing portion 23, a gap 23 a is formed across the entire circumference of the hermetic compressor 10 between the outer shape of the hermetic compressor 10 and the housing portion 23. The volume of 23a is defined as "gap volume". In FIG. 6, a portion corresponding to the gap 23a is indicated by hatching.

  The airtightness of the hermetic compressor 10 (sealed container 12) is inspected by detecting that the leak test hydrogen gas sealed in the hermetic compressor 10 leaks into the gap 23a.

  With reference to FIG. 9, the decompression and gas filling circuit connected to the chamber 20 by the hydrogen gas filling unit 40 of the airtightness inspection apparatus 100 will be described. The first connection passage 29 and the second connection passage 31 to the gap 23a so that the gas (hydrogen) in the gap 23a can be taken out from the outside of the chamber 20 for leak inspection and the gap 23a can be decompressed. Are formed above and below the chamber 20.

  At the outlet of the first connection passage 29, a first connection port 29a is formed for detachably connecting a pump or the like described later. Similarly, a second connection port 31 a is formed at the outlet of the second connection passage 31. The first connection port 29a and the second connection port 31a are closed when a pump or the like is not connected from the outside by a valve mechanism (not shown) to prevent the gas from flowing from the outside of the chamber 20 to the gap 23a. The gap 23a is airtight.

  When the hermetic compressor 10 is housed in the chamber 20 and the chamber 20 is set in the hydrogen gas enclosure 40 (see FIG. 1), the suction connected to the suction pipe 11 is controlled by a control device (computer or the like) not shown. The coupler 27b on the hydrogen gas enclosure 40 side is detachably connected to the coupler 27a on the side. A coupler 28b on the hydrogen gas enclosure 40 side is detachably connected to the coupler 28a on the discharge side connected to the discharge pipe 16. In this way, the hermetic compressor 10 and the hydrogen gas enclosure 40 are in communication.

  Then, a pump 51 for feeding inspection hydrogen gas connected to the suction side couplers 27a and 27b and the discharge side couplers 28a and 28b into the hermetic compressor 10, and leakage inspection A hydrogen gas tank 52 for supplying the hydrogen gas and a vacuum pump 53 for reducing the pressure in the hermetic compressor 10 are connected. Moreover, each process for detecting a leak can be performed by switching the valves 54-56 which switch or open / close a flow path with a control device (not shown).

  Further, when the chamber 20 is set in the hydrogen gas sealing part 40, it is controlled by a control device (computer or the like) (not shown), and the pump 57 and the dry air are also supplied to the upper and lower first connection ports 29a and 31a. A dry air tank 58 for supplying (air), a vacuum pump 59 for reducing the pressure in the gap 23a, and the like are connected. Moreover, each process for detecting a leak can be performed by switching the flow path or switching the valves 60 to 62 to be opened and closed by a control device (not shown).

  Next, a schematic configuration of a circuit connected to the chamber 20 in the leak test unit 50 (leak measurement unit) will be described with reference to FIG. When the chamber 20 is set in the leak test section 50, the leak test section 50 (leak measurement section) side coupler is connected to the suction side coupler 27 a connected to the suction pipe 11 under control of a control device (computer or the like) not shown. 27c is detachably connected. A coupler 28c on the leak test unit 50 (leak measurement unit) side is detachably connected to the coupler 28a on the discharge side connected to the discharge pipe 16. In this way, the hermetic compressor 10 and the leak test unit 50 (leak measurement unit) are in communication.

  Then, the suction couplers 27a and 27c and the discharge couplers 28a and 28c are supplied with a pump 71 for feeding dry air connected by piping into the hermetic compressor 10 and dry air (air). A dry air tank 72 is connected via valves 73 to 75 for switching and opening / closing the flow path. By switching the connection of the valves 73 to 75 with a control device (not shown), each step for detecting leakage can be performed.

  In addition, when the chamber 20 is set in the leak test unit 50 (leak measurement unit), the pump is connected to the upper and lower first connection ports 29a and the second connection port 31a by being controlled by a control device (computer or the like) not shown. 76 and a detector 77 (hydrogen gas detector) for detecting the concentration of hydrogen gas leaking into the gap 23 a are connected via valves 78 and 79.

  The leak test unit 50 (leak measurement unit) includes three detection units 50a to 50c as shown in FIG. 1, and each of the detection units 50a to 50c includes a circuit as shown in FIG. . For example, the detection unit 50a prepares for leak detection, the detection unit 50b performs leak detection, and the detection unit 50c takes out the chamber 20 that has been inspected from the detection unit 50c, so that work can be performed in parallel at three locations. In this case, a leak test (leak detection) can be performed efficiently.

Further, in this embodiment, each of the detection units 50a to 50c is configured by a protective structure that houses one chamber 20 and covers each chamber 20 at a high pressure such as a hermetic compressor 10 using CO _2. It is necessary to configure so that the sealed container 12 can be protected even if the sealed container 12 is damaged in the leak test of the sealed container 12 that needs to be inspected.

Next, the general principle of the detector 77 (hydrogen gas detector) for detecting hydrogen gas will be described with reference to FIG. The two electrodes 77a and 77b are connected to a power source 77d through a predetermined resistor 77c. The voltage between the two electrodes 77a and 77b is detected by a voltmeter 77e. When an inspection gas containing hydrogen gas leaking from the sealed container 12 passes between the electrodes 77a and 77b, hydrogen (H ₂ ) reacts with oxygen (O ₂ ) between the electrodes 77a and 77b to form water ( H ₂ O). When water (H ₂ O) is generated between the electrodes 77a and 77b, the hydrogen content can be detected by changing the voltage of the voltmeter 77e.

  Next, the hydrogen gas for inspection will be described. Leak inspection with helium gas can be inspected with high accuracy, but helium gas is not usually present in the atmosphere, and cannot be synthesized and produced, and is only produced from some areas. Therefore, there is a problem that it is difficult to use because there is a concern about price increase and depletion.

In contrast, hydrogen gas is generated as a by-product of the petroleum industry and the bio industry, for example, in large quantities by steam reforming and partial oxidation, for example, when generating synthetic gas from natural gas, and is therefore readily available and inexpensive. As the hydrogen gas for inspection, for example, a hydrogen-containing gas for inspection recognized as an inert gas conforming to the international standard ISO-101562 may be used. As an example, 5% hydrogen (H ₂ ), nitrogen Inspection may be performed using a clean inert gas such that (N ₂ ) is 95%. By inspecting with an inert gas, safety can be ensured without danger of explosion.

  Next, the hydrogen gas leak detection accuracy from the hermetic compressor 10 will be described. For example, in the case of a general water heater or a domestic air conditioner (air conditioner), the hermetic compressor 10 is mounted on a unit of a water heater or an air conditioner (air conditioner), and the capacity is reduced by 10%. The design specifications are acceptable for the product. Then, it is assumed that the capabilities of a water heater, a domestic air conditioner (air conditioner), and the like are proportional to the amount of refrigerant enclosed.

Hereinafter, a specific numerical example is estimated for the hermetic compressor 10 using the Co ₂ refrigerant for the water heater. CO ₂ loading of the refrigerant is 1050 g, the user of the life expectancy is 15 years, the amount of leakage of CO ₂ refrigerant in the acceptable 15 years is 10% of the initial loading, the Co ₂ refrigerant per year allowed The amount of leakage is
1050 [g] × 0.1 ÷ 15 [year] ≈7 [g / year]
It becomes.

Here, from the molecular weight 44 of CO _2, the number of moles per gram is 0.023, and the volume of CO ₂ per gram is calculated from the following gas equation of state.

PV = nRT
here,
P: Gas pressure (atmospheric pressure)
V: Volume n: Number of moles (0.023)
R: Constant T: Temperature (0 ° C)
It is.

From the above equation of state, the volume V of Co ₂ per gram at 0 ° C. at atmospheric pressure is 5.09 × 10 ⁻⁴ [m ³ / g]. Therefore, when the allowable leakage amount of Co ₂ refrigerant per year of 7 [g / year] is converted into a volume, it is 3.56 × 10 ⁻³ [m ³ / year]. When this is converted from year to second, 1.13 × 10 ⁻⁴ [cc / sec] is the minimum required leak detection sensitivity. By taking a margin of about 10 times and detecting a leak of 1 × 10 ⁻⁵ [cc / sec] or more, a leak failure can be detected.

  And when detecting leakage of the hermetic compressor 10 with hydrogen gas, the hydrogen gas is usually present in the atmosphere at around 0.5 ppm, and unlike helium gas, it is adsorbed on the plastic or metal surface or released again. Therefore, the hydrogen gas causes false detection.

The false detection density level 81 shown in FIG. 12 is measured by the following procedure.
(1) Hydrogen gas is sealed in the hermetic compressor 10 and a leak standard (not shown) is attached to a predetermined location of the hermetic compressor 10 (for example, between the hermetic container 12 and the suction muffler 15). Then, hydrogen gas is leaked into the chamber 20 in an amount of 1 × 10 ⁻⁵ [cc / sec] using a leak standard device;
(2) Next, the inside of the chamber 20 is cleaned with dry air by air blowing, and hydrogen gas is discharged from the inside of the chamber 20.
(3) The hydrogen gas concentration in the chamber 20 is measured in a state where there is no leakage of hydrogen gas from the hermetic compressor 10 (a state where there is no leakage of hydrogen gas from the leak standard).

  The hydrogen gas concentration measured in (3) becomes the false detection concentration level 81. Although there is no leakage from the hermetic compressor 10, the hydrogen adsorbed on the surface of the storage portion 23 of the chamber 20 that remains after cleaning by air blow is released and detected.

Then, the amount of 1 × 10 ⁻⁵ [cc / sec] is used again from the hermetic compressor 10 by using a leak standard (not shown) attached to a predetermined portion of the hermetic compressor 10 in the chamber 20. As a result, hydrogen gas is leaked, and a leaked hydrogen gas concentration 82 is obtained which is the hydrogen gas concentration when the gas is leaked into the chamber 20 while changing the time. The linear approximation of the experimental value obtained from this measurement result becomes two straight lines of the false detection level 81 and the leaked hydrogen gas concentration 82 in the figure.

  In order to prevent erroneous detection, it is sufficient that the leaked hydrogen gas concentration 82 exceeds the erroneous detection concentration level 81, but there are variations in each. Therefore, in order to perform accurate detection, the leaked hydrogen gas concentration 82 must exceed the erroneous detection level 81 by 3σ (σ is a standard deviation) or more.

  When the variation of the measured value is a normal distribution, 99.7% of the measured value is distributed within the range of the average value ± 3σ. Therefore, by measuring at a concentration that is higher than the average value + 3σ of the false detection level 81 obtained from the experimental results, false detection can be suppressed to a practical range of 0.3% or less.

3σ is obtained from the measured value, and a location 3σ away from the average value of each of the false detection level 81 and the leaked hydrogen gas concentration 82 is set as a threshold value. From the experimental results, the threshold is 1.6 [ppm], and the accumulation time is 360 [sec] = 6 [min]. From this result and concentration = leakage amount × time / volume, volume at the shortest accumulation time 360 [sec] = 1 × 10 ⁻⁵ [cc / sec] × 360 [sec] /1.6 [ppm] = 2250 [cc] ].

  Therefore, the gap volume of the gap 23a that can detect the leaked hydrogen gas without erroneous detection in the shortest time is 2250 [cc] or less. If the gap volume of the gap 23a is 2000 [cc] or less, leaked hydrogen gas can be detected in a shorter time, which is more preferable.

  In order to guarantee the resolution of the measuring device for leaked hydrogen gas, the sensitivity needs to satisfy 1/10 of the minimum scale of the measuring device. If the gap volume of the chamber 20 varies by 10% or more, the leaked hydrogen gas concentration also varies accordingly, and the detection sensitivity decreases. Therefore, regardless of the ability of the measuring instrument, the variation in the volume of the gap 23a between the chambers 20 is 10% or less.

  Next, the operation of the airtightness inspection apparatus 100 of the hermetic compressor 10 will be described with reference to the flowchart of FIG.

  First, in the workpiece loading step (A in FIG. 1), the hermetic compressor 10 (work) is housed in the chamber 20 on the upper conveyor 30a, and the suction side coupler 27a is connected to the suction pipe 11. Further, the discharge-side coupler 28a is connected to the discharge pipe 16 (step 1).

Next, in the hydrogen filling step (B in FIG. 1), the couplers 27a and 27b on the suction side and the couplers 28a and 28b on the discharge side are connected at the hydrogen gas filling unit 40. After the lid portion 22 of the chamber 20 is closed, vacuuming in the hermetic compressor 10 is performed by a vacuum pump 53 (see FIG. 9). The ultimate pressure at this time is checked, and a large leak check of the workpiece is performed. If there is no large leakage of the workpiece, a hydrogen mixed gas (for example, a mixed gas of 5% hydrogen (H ₂ ) and 95% nitrogen (N ₂ )) is sealed from the couplers 27a and 27b on the suction side (about 1 MPa ( 0.9 MPa)). This pressure (about 1 MPa (0.9 MPa)) is defined as a first pressure or a predetermined pressure. At this time, the gas in the hermetic compressor 10 is discharged from the coupler couplers 28a and 28b on the discharge side, and the hydrogen mixture gas is uniformly sealed in the hermetic compressor 10 to eliminate air accumulation, and a later leak test Check leakage is prevented in the process (D in FIG. 1) (step 2).

  After the hydrogen mixed gas is sealed in the hermetic compressor 10, a vacuum pump 59 (see FIG. 9) is connected to the first connection port 29a and the second connection port 31a of the chamber 20 to reduce the pressure in the gap 23a. The ultimate pressure at this time is checked to check the sealing degree of the gap 23a. Furthermore, pressure reduction and air blow are repeated twice, for example, to drive out residual hydrogen.

  By performing this depressurization, the same effect as reducing the dead volume within the volume of the gap 23a is obtained. At this time, it is confirmed that the detector 77 (see FIG. 10) used in the subsequent leak test process (see FIG. 1D) has a thermochemical reaction and requires about 1 to 2 minutes to reach an accurate value. Has been. Further, since pressure P × volume V = constant, volume V = volume flow rate G × time t, the required pressure at the time of measurement can be obtained by the following equation.

P1 = P2 × V2 / V1 = (G × t) / V1
(P1: pressure at reduced pressure, P2: atmospheric pressure, V1: volume at reduced pressure, V2: volume at atmospheric pressure, G: volume flow rate, t: measurement time)
Therefore, V1 = the gap volume of the chamber 20 = 2000 [cc], and in the hydrogen detector used this time, G = 100 [cc / min], so that t = 2 [min] and the pressure during decompression is 0.1 [atm]. ]. The chamber 20 whose decompression has been completed is conveyed to the lower conveyor 30c by the lifter 30b (step 3).

  In the accumulation step (C in FIG. 1, hydrogen deposition 1), when there is a leak location in the hermetic compressor 10, the hydrogen gas leaked into the gap 23 a is accumulated. In this accumulation process (hydrogen deposition 1), it is necessary to leak hydrogen gas until sufficient detection accuracy is obtained. From the experimental results of FIG. 12, the shortest accumulation time for obtaining sufficient detection accuracy is 6 [min]. Therefore, the lower conveyor 30c needs to have a length that can secure at least the shortest accumulation time (6 [min]). The chamber 20 that has completed the accumulation process is transported to the upper conveyor 30a by the lifter 30d (step 4).

  In the leak test step (D in FIG. 1), the chamber 20 is put in the protective structure detection units 50a to 50c in order, for example, the detection unit 50a prepares for leak detection, and the detection unit 50b performs leak detection. The chamber 20 that has been inspected by the detection unit 50c is taken out from the detection unit 50c.

First, dry air in a dry air tank 72 (see FIG. 10) is sealed from the couplers 27a and 27c on the suction side, and additional pressure is applied from about 1 MPa to 14 MPa (second pressure) inside the hermetic compressor 10. Even if additional pressure is applied with dry air that is cheap and easy to procure instead of hydrogen mixed gas, the leaked concentration is reduced to 1/14, but the leak amount is 14 times proportional to the pressure. The amount of hydrogen that is offset by × 1/14 and leaks from the hermetic compressor 10 into the gap 23a of the chamber 20 does not change. The reason for the additional pressure is that, in the case of CO ₂ refrigerant, the design pressure is about 10 MPa, and the airtight test needs to be performed at a design pressure (10 MPa) or higher, for example, 14 MPa. In the hydrogen filling process, a high pressure of about 14 MPa may be used instead of about 1 MPa. However, it is not preferable because the chamber 20 needs to be put in a huge protective box in the accumulation process from the viewpoint of safety (step 5).

  Next, the gap 23a and the pump 76 (see FIG. 10) are connected to the first connection port 29a and the second connection port 31a of the chamber 20, and after the inside of the gap 23a is sufficiently stirred, the mixed gas ( The hydrogen mixed gas + dry air is led to a sensor of a detector 77 (hydrogen gas measuring device) connected to a circuit with the pump 76 (step 6).

  The detector 77 (hydrogen gas measuring device) measures the hydrogen gas of the mixed gas (hydrogen mixed gas + dry air) in the gap 23a. When the hydrogen gas concentration is equal to or higher than a predetermined value (for example, 1.6 ppm), the detector 77 determines that the work (sealed compressor 10) is poor in airtightness. In the measurement of hydrogen gas, for example, the final stable value may be predicted in 10 seconds. By doing so, the cycle time of the airtightness test is shortened (step 7).

  After the measurement of the hydrogen gas at the detector 77 is completed, the mixed gas (hydrogen mixed gas + dry air) inside the hermetic compressor 10 is exhausted by the couplers 27a and 27c on the suction side and the couplers 28a and 28c on the discharge side. The residual hydrogen is cleaned by evacuating the measurement circuit and air blowing to complete the leak test process (step 8).

  The hermetic compressor 10 for which the leak test process has been completed is taken out from the inside of the chamber 20, and the airtightness test (hydrogen gas leak test) is completed. The chamber 20 from which the hermetic compressor 10 has been removed is used as it is for the hermetic compressor 10 to be the next object to be tested.

  As described above, in this embodiment, the accumulation process is ensured during the movement of the chamber 20 filled with hydrogen gas by separating the hydrogen gas filling unit 40 and the leak test unit 50 (hydrogen gas measuring device). In addition, it is possible to increase the number of specimens simultaneously processed without increasing the size of the equipment.

  In addition, the hydrogen gas sealing part 40 and the leak test part 50 (hydrogen gas measuring device) are carried out by the upper conveyor 30a, and the accumulation process is carried out by the lower conveyor 30c. The property inspection apparatus 100) can be reduced in size. Since the hydrogen gas sealing unit 40 and the leak test unit 50 (hydrogen gas measuring device) involve an operator, the above-described embodiment in which the hydrogen gas sealing unit 40 and the leak test unit 50 (hydrogen gas measuring device) are provided in the upper conveyor 30a. Is preferred, but the opposite is also possible. That is, the hydrogen gas sealing unit 40 and the leak test unit 50 (hydrogen gas measuring device) may be performed by the lower conveyor 30c, and the accumulation process may be performed by the upper conveyor 30a.

  Further, by utilizing the characteristic that the dimension of the hermetic compressor 10 is stable, the volume of the gap 23a between the chamber 20 and the hermetic compressor 10 is limited to a predetermined value or less (for example, 2250 cc or less) to cause leakage. The concentration of the generated hydrogen gas can be increased, and the accumulation time in the accumulation process can be shortened.

  Further, by setting the volume of the gap 23a of the chamber 20 to 2000 cc or less, the accumulation time in the accumulation process is minimized, which is more preferable.

  Moreover, the detection accuracy of the hydrogen gas measuring device in the leak test process can be improved by setting the variation in the volume of the gaps 23a between the plurality of chambers 20 to ± 10% or less.

  In addition, in the hydrogen gas sealing unit 40, a hydrogen mixed gas of about 1.0 MPa is sealed in the hermetic compressor 10 to ensure safety in the accumulation process. By performing additional pressure from about 1 MPa to 14 MPa (pressure required in the air tightness test) with dry air, the explosion-proof structure may be only the leak test unit 50, so that the equipment (the airtightness inspection device 100) can be downsized. Further, since the additional pressure is performed with dry air, it is superior in safety, cost and the like as compared with the case of additional pressure with a hydrogen mixed gas.

  DESCRIPTION OF SYMBOLS 10 Sealing type compressor, 10a Compression element, 10b Electric element, 11 Suction pipe, 11a Flange part, 12 Sealed container, 12a Upper container, 12b Body part, 12c Lower container, 13 Cap part, 14 Cap part, 15 Inhalation muffler, 16 discharge pipe, 16a flange, 18 refrigerating machine oil, 20 chamber, 21 body, 22 lid, 23 storage, 23a clearance, 24 tray, 25 suction side coupler storage, 26 discharge side coupler storage, 27a coupler, 27b coupler, 28a coupler, 28b coupler, 29 first connection passage, 29a first connection port, 30 conveyor, 30a upper conveyor, 30b lifter, 30c lower conveyor, 30d lifter, 31 second connection passage, 31a second Connection port, 40 hydrogen gas filling section, 50 leak test section, 51 ports 52, hydrogen gas tank, 53 vacuum pump, 54-56 valve, 57 pump, 58 dry air tank, 60-62 valve, 70 hydrogen gas detector, 70a detector, 70b detector, 71 pump, 71a detector, 72 drying Air tank, 73 to 75 valve, 76 pump, 77 detector, 77a electrode, 77b electrode, 78 to 79 valve, 81 false detection concentration level, 82 leaked hydrogen gas concentration, 90 packing, 100 airtightness inspection device.

Claims (10)

A transfer device formed in a ring shape in the vertical direction;
A plurality of chambers that are mounted on the transfer device and move on the transfer device, and in which a sealed container is housed in an airtight manner without communicating with the outside;
A gap formed around the sealed container in the chamber;
A hydrogen mixed gas sealing portion that is provided at a predetermined position of the transfer device and seals the hydrogen mixed gas at a predetermined first pressure in the sealed container housed in the chamber;
Following the hydrogen mixed gas enclosing unit, a hydrogen mixed gas depositing unit is provided over a predetermined moving direction length of the transfer device, and the hydrogen mixed gas is deposited in the gap,
Following the hydrogen mixed gas deposition section, provided at a predetermined position of the transfer device, the dry air is added to the sealed container to a predetermined second pressure corresponding to a predetermined airtight test pressure. An airtightness inspection apparatus comprising: a hydrogen gas detection unit that detects hydrogen gas leaking into the gap. A transfer device formed in a ring shape in the vertical direction;
A plurality of chambers that are mounted on the transfer device and move on the transfer device, and in which a sealed container is housed in an airtight manner without communicating with the outside;
A gap formed around the sealed container in the chamber;
A hydrogen mixed gas sealing portion that is provided at a predetermined position of the transfer device and seals the hydrogen mixed gas at a predetermined pressure in the sealed container housed in the chamber;
Following the hydrogen mixed gas enclosing unit, a hydrogen mixed gas depositing unit is provided over a predetermined moving direction length of the transfer device, and the hydrogen mixed gas is deposited in the gap,
An airtightness inspection apparatus comprising: a hydrogen gas detection unit that is provided at a predetermined position of the transfer device and detects hydrogen gas leaking into the gap, following the hydrogen mixed gas deposition unit. The transfer device is a conveyor that moves by placing a plurality of the chambers,
The said conveyor is comprised by the following elements, The airtightness inspection apparatus of Claim 1 or Claim 2,
(1) An upper conveyor that moves in the horizontal direction;
(2) a first lifter that moves up and down from one end of the upper conveyor and connects to one end of the lower conveyor;
(3) A lower conveyor that moves in a horizontal direction opposite to the upper conveyor;
(4) A second lifter that moves in the vertical direction from the other end of the lower conveyor and is connected to the other end of the upper conveyor.   The airtightness inspection apparatus according to any one of claims 1 to 3, wherein a volume of the gap is restricted to a predetermined value or less.   The airtightness inspection apparatus according to any one of claims 1 to 4, wherein the gap has a volume of 2000 cc or less.   6. The airtightness inspection apparatus according to claim 5, wherein variation in volume of the gap in the plurality of chambers is within ± 10%.   4. The airtightness inspection apparatus according to claim 3, wherein the hydrogen mixed gas sealing part and the hydrogen gas detection part are provided on the upper conveyor.   8. The airtightness inspection apparatus according to claim 7, wherein the hydrogen mixed gas accumulation part is provided on the lower conveyor.   2. The airtightness inspection apparatus according to claim 1, wherein a ratio between the first pressure and the second pressure is about 1:14. The gas tightness inspection apparatus according to claim 1 or 2, wherein an inert gas containing 5% hydrogen (H ₂ ) and 95% nitrogen (N ₂ ) is used as the hydrogen mixed gas.