JP2021021566A - Differential pressure leak test device - Google Patents

Abstract

To keep the temperature of a master container stable under repeated inspections and also to reduce the temperature change during differential pressure measurement.SOLUTION: A differential pressure leak test device (1) injects high-pressure gas into the inside of both a work (W) having a cavity and a master container (3) having airtightness in a sealed state, and inspects the airtightness of the work based on measuring the pressure difference between the inside of the work cavity and the inside of the master container. In the master container, provided are: a heat conductive member (8) that is thermally connected to the inner wall of the master container to increase the internal surface area while securing the internal volume; and a control device (4) that executes, at the start of an inspection, a warm-up operation in which high-pressure gas is injected into and exhausted from the master container at regular time intervals.SELECTED DRAWING: Figure 1

Description

The present invention relates to a differential pressure type leak test device that inspects the airtightness of a work based on measuring the pressure difference between the inside of the cavity of the work into which high-pressure gas is injected and the inside of the master container.

For example, it is known that the airtightness of parts (workpieces) is inspected by a differential pressure type leak test device for automobile parts such as molded products and die-cast products that require airtightness (for example, Patent Document 1). reference). In this differential pressure type leak test device, the opening of the work is closed by the closing device, and the cavity of the work is connected to the first connection port of the diaphragm type differential pressure gauge. On the other hand, the airtight master container is connected to the second connection port of the differential pressure gauge. Then, high-pressure air adjusted to a predetermined pressure is supplied to both the inside of the cavity of the work and the inside of the master container, and then, based on the measurement of the differential pressure by the differential pressure gauge, the presence or absence of leakage in the work is inspected. There is. In this case, a plurality of workpieces are sequentially and repeatedly inspected.

JP 2015-158522

By the way, in the above-mentioned differential pressure type leak test device, when high pressure air is suddenly supplied to the master container, the temperature of the air inside rises due to so-called adiabatic compression, and the heat is transferred to the master container. There are circumstances in which the temperature of the master container itself fluctuates. Therefore, when the inspection is performed continuously, there is a problem that the measured value of the differential pressure changes with a tendency for each number of measurements. Therefore, continuous inspection is required while the temperature of the master container is stable. For example, when measuring a differential pressure of 10 Pa or less with high accuracy, it is desirable to suppress the temperature change of the air in the master container at the time of measurement to 10 ^-3 ° C or less.

Therefore, in Patent Document 1, it is proposed that the temperature of the master container and the work is adjusted to the ambient temperature by applying cooling air to the master container and the work. However, the temperature change of the master container becomes relatively large when the cooling air is applied. As a result, the differential pressure may not be measured with the required accuracy. Alternatively, there is a problem that the time required for the inspection becomes long.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make the temperature of the master container stable when the inspection is repeatedly executed, and to keep the temperature change during differential pressure measurement small. To provide a differential pressure leak test device capable of

In order to achieve the above object, the first differential pressure type leak test device (1) of the present invention contains both the work (W) having a cavity and the master container (3) having an airtightness in a sealed state. A high-pressure gas is injected into the work, and the airtightness of the work is inspected based on measuring the pressure difference between the inside of the work cavity and the inside of the master container. Heat conductive members (8, 11, 13, 15) that are thermally connected to the inner wall of the master container to increase the internal surface area are provided in a state where the volume of the master container is secured, and when starting the inspection, It is provided with a control device (4) for executing a warm-up operation in which high-pressure gas is injected and exhausted into the master container at regular time intervals.

According to this, the heat conductive member provided in the master container is thermally connected to the inner wall of the master container and has a large surface area. At the start of the inspection, the control device executes a warm-up operation in which high-pressure gas is injected and exhausted into the master container at regular time intervals. In this warm-up operation, when a high-pressure gas is supplied into the master container, the temperature of the gas rises due to so-called adiabatic compression, but the heat is transferred to the master container via a heat conductive member having a large area. , The temperature of the master container will rise rapidly.

By this warm-up operation, the temperature of the master container can be quickly stabilized, and the differential pressure can be repeatedly measured while the temperature change of the master container is small. There is no measurement error due to the temperature change of the master container as in the case of applying cooling air from the outside. As a result, the temperature of the master container can be kept stable when the inspection is repeatedly executed, the temperature change at the time of differential pressure measurement can be suppressed to a small value, and the inspection can be performed with high accuracy. It is possible to obtain an excellent effect of becoming.

Further, in the second differential pressure type leak test device (21) of the present invention, both the work (W) having a cavity and the master container (23) having an airtightness are sealed and high-pressure gas is injected into the inside. , The airtightness of the work is inspected based on the measurement of the pressure difference between the inside of the work cavity and the inside of the master container, and a plurality of the master containers are provided in a parallel state and inspected. It is provided with a switching device (28) that is used while switching the master container in order as the work to be switched is switched.

According to this, when a plurality of workpieces are continuously inspected in sequence, the inspection can be performed while sequentially switching the master container to be used by the switching device. Therefore, in each master container, sufficient cooling time can be provided from one use to the next, and the master container can always be kept at room temperature, that is, at a relatively low temperature, and injection of high-pressure gas can be started. it can. As a result, the temperature of the master container can be kept stable when the inspection is repeatedly executed, the temperature change at the time of differential pressure measurement can be suppressed to a small value, and the inspection can be performed with high accuracy. It is possible to obtain an excellent effect of becoming.

The figure which shows the 1st Embodiment and shows roughly the structure of the differential pressure type leak test apparatus. An exploded perspective view of the master container An exploded perspective view of the master container showing the second embodiment. An exploded perspective view of a master container showing a third embodiment. An exploded perspective view of a master container showing a fourth embodiment. The figure which shows the 5th Embodiment schematicly showing the structure of the differential pressure type leak test apparatus.

Hereinafter, some embodiments embodying the present invention will be described with reference to the drawings. It should be noted that the same parts will be designated by the same reference numerals among the plurality of embodiments, and new illustrations and repetitive explanations will be omitted.

(1) First Embodiment The first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 schematically shows the overall configuration of the differential pressure type leak test device 1 according to the present embodiment. Here, the differential pressure type leak test device 1 includes a leak tester main body 2, an airtight master container 3, and a control device 4 including a computer and controlling the whole. The master container 3 is connected to the leak tester main body 2 via a master connecting pipe 5. Details of the master container 3 in this embodiment will be described later.

Further, the work W is connected to the leak tester main body 2 via the work connecting pipe 6. Although not shown in detail, the work W to be inspected for airtightness is made of, for example, automobile engine-related parts, and is required to be airtight. At this time, at the time of inspection, the work W is sealed by attaching a closing member to the opening, and the tip of the work connecting pipe 6 is connected to the closing member.

Although not shown in detail, the leak tester main body 2 includes a high-pressure gas supply unit including a compressor, a pressure regulating valve, etc., for example, a diaphragm type differential pressure gauge, an electromagnetically driven first and second switching valve, and the like. ing. Among them, the first switching valve is provided in the middle of the work connecting pipe 6, and the work connecting pipe 6 is connected to the high-pressure gas supply unit at the first position, and the work connecting pipe 6 is connected to the first differential pressure gauge. It is configured to be switchable between a second position for connecting to the connection port and a third position for opening the work connecting pipe 6 to the atmosphere. The second switching valve is provided in the middle of the master connecting pipe 5, and similarly, the master connecting pipe 5 is connected to the high pressure gas supply unit at a first position, and the master connecting pipe 5 is connected to the differential pressure gauge. It is configured to be switchable between a second position for connecting to the second connection port of the above and a third position for opening the master connection pipe 5 to the atmosphere.

The control device 4 controls each mechanism of the leak tester main body 2 to execute the inspection. Specifically, first, both the first and second switching valves are driven to the first position, and high-pressure air as a high-pressure gas adjusted to a predetermined high pressure by the high-pressure gas supply unit is sent into the work W and the master. It is supplied into the container 3. After injecting a predetermined amount of high-pressure air into the work W and the master container 3, both the first and second switching valves are switched to the second positions to reduce the pressure in the work W and the pressure in the master container 3. It is introduced into the first connection port and the second connection port of the differential pressure gauge, respectively. As a result, the pressure difference between the work W and the master container 3 is measured by the differential pressure gauge, and the measurement signal is input to the control device 4. When the inspection of the airtightness of the work W is completed, both the first and second switching valves are switched to the third position to open the inside of the work W and the inside of the master container 3 to the atmosphere.

At this time, the control device 4 sequentially repeats the inspection process by the leak tester main body 2 described above for a plurality of work Ws at regular intervals. In the present embodiment, when the inspection is started, the control device 4 executes a warm-up operation in which high-pressure air as a high-pressure gas is injected into the master container 3 and exhaust is performed at regular time intervals. Then, by executing the warm-up operation, the inspection of the work W, that is, the measurement of the differential pressure is started in a stable state in which the master container 3 has risen to a constant temperature.

Now, the master container 3 will be described in detail with reference to FIG. The master container 3 is made of a metal such as aluminum or SUS, and has a main body portion 3a having an open upper surface in the shape of a cylindrical container, and a disk-shaped lid portion 3b for opening and closing the upper surface opening of the main body portion 3a. To be equipped. At this time, the volume inside the master container 3 is set to be substantially equal to or larger than the volume inside the cavity of the work 3.

Further, although not shown, a lock mechanism (not shown) for locking the lid portion 3b to the main body portion 3a in a closed state is provided between the main body portion 3a and the lid portion 3b. At this time, as shown in FIG. 2, the main body portion 3a has a flange portion at the upper end portion, and a packing 7 made of an O-ring is arranged between the upper surface of the flange portion and the lid portion 3b. Airtightness when the lid portion 3b is closed is ensured. The tip of the master connecting pipe 5 is connected to the lid 3b.

Then, in the main body 3a of the master container 3, a heat conductive member 8 which is thermally connected to the inner wall of the master container 3 to increase the internal surface area is housed in a state where the internal volume is secured. In the present embodiment, the heat conductive member 8 is composed of corrugated fins 9 made of a thin plate of metal, for example, aluminum, arranged in multiple layers. In this case, the corrugated fin 9 is formed by forming a thin plate of metal, for example aluminum, into a corrugated shape, that is, a corrugated shape, into a circular shape and an arc shape having a different radius of curvature. Then, the corrugated fins 9 are arranged so as to be spread in a circular shape so as to form a circular shape as a whole, and are stacked in multiple layers to form the entire heat conductive member 8.

Next, the action / effect of the above configuration will be described. In the differential pressure type leak test device 1 of the present embodiment, when inspecting the airtightness of the work W, first, as shown in FIG. 1, the work is connected with the master container 3 connected to the master connection pipe 5. The work W is connected to the pipe 6. At the start of the inspection, the control device 4 executes a warm-up operation on the master container 3. This warm-up operation is performed by injecting and exhausting high-pressure air into the master container 3 at regular time intervals.

In this warm-up operation, when high-pressure air is supplied into the master container 3, the temperature of the air rises due to so-called adiabatic compression, and the heat of the air rises through the heat conductive member 8 having a large area. It is transmitted to the inner wall of the master container 3 and the temperature of the master container 3 rises. In the present embodiment, the heat conductive member 8 made of corrugated fins 9 provided in the master container 3 is made of a thin plate of metal having good thermal conductivity, for example, aluminum, and is thermally connected to the inner wall of the master container 3. At the same time, it has a large surface area. Therefore, the temperature of the master container 3 rises rapidly, and the injection and exhaust of high-pressure air are performed at regular time intervals, so that the temperature of the master container 3 becomes stable in a short time.

Then, by executing the warm-up operation, the inspection of the work W, that is, the measurement of the differential pressure is started in a stable state in which the master container 3 has risen to a constant temperature. When the inspection is started, as described above, high-pressure air of a predetermined pressure is injected into the work W and the master container 3 at the first position of the first and second switching valves. With high pressure air injected into the work W and the master container 3, the first and second switching valves are switched to the second position, and the inside of the work W and the master container 3 are connected to the differential pressure gauge. The pressure difference is measured by a differential pressure gauge. This differential pressure measurement is performed in a state where the temperature of the master container 3 is stable at a constant temperature.

When the inspection of the airtightness of the work W is completed, the first and second switching valves are switched to the third position, and the inside of the work W and the inside of the master container 3 are opened to the atmosphere. The work W for which the inspection has been completed is removed from the work connecting pipe 6, the next work W is connected to the work connecting pipe 6, and the above inspection process is repeated. When the inspection is repeated continuously for a plurality of work Ws, the next inspection can be performed in a state where the temperature of the master container 3 is stable. By providing the heat conductive member 8, the volume of the master container 3 is not unnecessarily reduced, and the volume required for inspection can be maintained. In addition, a measurement error due to a temperature change of the master container 3 does not occur as in the case of applying cooling air from the outside.

Therefore, according to the present embodiment, the temperature of the master container 3 can be kept stable when the inspection is repeatedly executed, and the temperature change at the time of differential pressure measurement can be suppressed to a small value, and thus high accuracy. It is possible to obtain an excellent effect that the inspection of the above can be performed. By the way, in the present embodiment, the temperature change of the air in the master container 3 at the time of measuring the differential pressure can be suppressed to 10 ^-3 ° C or less, and for example, the differential pressure of 10 Pa or less can be measured with high accuracy. It became.

Further, in particular, in the present embodiment, the heat conductive member 8 is composed of corrugated fins 9 arranged in multiple layers. By adopting the corrugated fin 9, the surface area of the heat conductive member 8 can be sufficiently increased, and the heat conductivity to the master container 3 can be improved, which is more effective. By adopting aluminum as the material of the corrugated fin 9, it is possible to obtain advantages such as excellent thermal conductivity, light weight, and good workability.

(2) Second to Fourth Embodiments FIG. 3 shows a second embodiment. The difference between this second embodiment and the first embodiment is the configuration of the heat conductive member 11 housed in the master container 3. That is, the master container 3 is also composed of the main body portion 3a, the lid portion 3b, the packing 7, and the like, but in this second embodiment, for example, a large amount of metal fine wire 12 made of stainless steel wool is formed to some extent. It is composed of a columnar structure that is hardened with a gap. The heat conductive member 11 is also provided so as to increase the internal surface area by being thermally connected to the inner wall of the master container 3 while securing the volume inside the master container 3.

According to such a second embodiment, similarly to the first embodiment, the heat conductive member 11 is provided in the master container 3, and a warm-up operation is executed at the start of the inspection. As a result, the temperature of the master container 3 can be kept stable when the inspection is repeatedly executed, and the temperature change at the time of differential pressure measurement can be suppressed to a small value, which in turn enables high-precision inspection. It is possible to obtain an excellent effect of being possible. By forming the heat conductive member 11 so as to solidify the thin metal wire 12, the shape, size, density, etc. can be freely adjusted while playing the role of the heat conductive member 11. , It is possible to correspond to various shapes of the master container 3 and the desired thermal conductivity.

FIG. 4 shows a third embodiment. In the third embodiment, the configuration of the heat conductive member 13 housed in the master container 3 is different from that of the first and second embodiments. That is, the master container 3 is also composed of a main body portion 3a, a lid portion 3b, a packing 7, and the like. The heat conductive member 13 is composed of, for example, a thin disk-shaped aluminum metal thin plate 14 having a thickness dimension of about 0.5 mm arranged in multiple layers. In this case, although not shown, spacers and the like are provided between the upper and lower metal thin plates 14 to provide gaps, and each metal thin plate 14 has an opening for communicating the gaps in the vertical direction. ing. The heat conductive member 13 is also provided so as to increase the internal surface area by being thermally connected to the inner wall of the master container 3 while securing the volume inside the master container 3.

According to the third embodiment as described above, the heat conductive member 13 is also provided in the master container 3, and the warm-up operation is executed when the inspection is started. As a result, the temperature of the master container 3 can be kept stable when the inspection is repeatedly executed, and the temperature change at the time of differential pressure measurement can be suppressed to a small value, which in turn enables high-precision inspection. It is possible to obtain an excellent effect of being possible. By adopting the metal thin plate 14 as the heat conductive member 13, the heat conduction performance of the heat conductive member 13 can be easily improved by changing the number and arrangement of the metal thin plates 14 while requiring a relatively simple and inexpensive configuration. It will be possible to change to.

FIG. 5 shows a fourth embodiment. In this fourth embodiment, the heat conductive member 15 housed in the master container 3 is composed of the metal porous member 16. The metal porous member 16 is formed of a metal such as stainless steel, titanium, nickel, and copper in a columnar shape having a large number of pores. The heat conductive member 15 is also provided so as to increase the internal surface area by being thermally connected to the inner wall of the master container 3 while securing the volume inside the master container 3.

According to the fourth embodiment as described above, the heat conductive member 15 is also provided in the master container 3, and the warm-up operation is executed when the inspection is started. As a result, the temperature of the master container 3 can be kept stable when the inspection is repeatedly executed, and the temperature change at the time of differential pressure measurement can be suppressed to a small value, which in turn enables high-precision inspection. It is possible to obtain an excellent effect of being possible. By adopting the metal porous member 16 as the heat conductive member 15, the specific surface area of the heat conductive member 15 can be made extremely large, and the contact area with the inner wall of the master container 3 can be made large. It becomes. Therefore, the effect of enabling the temperature stabilization of the master container 3 in a short time is excellent.

(3) Fifth Embodiment Next, the fifth embodiment will be described with reference to FIG. FIG. 6 schematically shows the overall configuration of the differential pressure type leak test device 21 according to the fifth embodiment. The differential pressure type leak test device 21 includes a leak tester main body 22, a plurality of (N) master containers 23 having airtightness, and a control device 24 which is configured to include a computer and controls the whole. The work W is connected to the leak tester main body 22 via the work connecting pipe 26.

Although not shown in detail, each of the master containers 23 has a main body portion 23a having a cylindrical container shape with an open upper surface, and a disk-shaped lid portion 23b for opening and closing the upper surface opening of the main body portion 23a. Not equipped with packing. The inside of the master container 23 has a volume substantially equal to or larger than the volume inside the cavity of the work W. The plurality of master containers 23 are connected to the leak tester main body 22 via the master connecting pipe 25. The master connecting pipe 25 is branched into a plurality of (N pieces), and the tip of each of the branch pipes 25a is connected to the lid 23b of each master container 23. As a result, the plurality of master containers 23 are provided in parallel.

At this time, each branch pipe 25a portion of the master connecting pipe 25 is provided with an electromagnetic opening / closing type on-off valve 27. These on-off valves 27 are controlled by the control device 24. The control device 24 controls so that only one on-off valve 27 corresponding to the master container 23 to be used is opened out of the plurality of on-off valves 27, and the remaining on-off valve 27 is closed. That is, when the inspection is repeatedly executed for a plurality of work W, the master container 23 is used while being sequentially switched according to the switching of the work W to be inspected. Therefore, the switching device 28 is composed of the control device 24, each on-off valve 27, and the like.

Next, the operation of the differential pressure type leak test device 21 having the above configuration will be described. As shown in FIG. 6, when it is necessary to distinguish between a plurality of master containers 23, (A), (B), (C), ... (N) should be added after the reference numeral "23". In order to distinguish the on-off valve 27 corresponding to the above, (A), (B), (C), ... (N) are added after the reference numeral "27". When inspecting the airtightness of the work W, the first work W is connected to the work connecting pipe 26. When the inspection is started, only the first on-off valve 27 (A) is opened, and a predetermined amount of high-pressure air is injected into the master container 23 (A) and the work W. The remaining on-off valve 27 is in a closed state, and high-pressure air is not supplied into the remaining master container 23.

At this time, the air temperature in the master container 23 (A) rises from the low temperature (normal temperature) state due to the supply of high-pressure air to the master container 23 (A), but the air temperature in the master container 23 is stable at a relatively low temperature. In this state, the inside of the work W and the inside of the master container 23 (A) are connected to the differential pressure gauge, and the pressure difference between them is measured by the differential pressure gauge. When the airtightness inspection of the work W is completed, the inside of the work W and the inside of the master container 23 (A) are opened to the atmosphere. The work W for which the inspection has been completed is removed from the work connecting pipe 6, and the next work W is connected to the work connecting pipe 26.

The inspection for the next work W is performed using the master container 23 (B) with only the second on-off valve 27 (B) open. When the second inspection is completed, the inspection for the next work W is performed using the master container 23 (C) with only the third on-off valve 27 (C) opened. In this way, the switching device 28 performs the inspection while switching the master container 23 to be used in order. By using the master container 23 while switching in order in this way, a sufficient time can be allowed from one use to the next use in each master container 23, and the master container 23 that is always used is cooled to room temperature. The inspection can be performed in the state.

According to this, when sequentially inspecting a plurality of work Ws, the master container 23 is always kept stable at a relatively low constant temperature even if the time interval from the inspection to the next inspection is shortened. The differential pressure can be measured. As a result, according to the fifth embodiment, the temperature of the master container 23 can be kept stable when the inspection is repeatedly executed, and the temperature change at the time of differential pressure measurement can be suppressed to a small value, which in turn can be suppressed. , It is possible to obtain an excellent effect that high-precision inspection can be performed.

It should be noted that the present invention is not limited to each of the above-described embodiments, and various changes can be made to, for example, the material and shape of the master container and the heat conductive member. The work W is not limited to vehicle parts, but can be applied to all parts that are inspected for airtightness. Although the present disclosure has been described in accordance with the examples, it is understood that the present disclosure is not limited to the examples and structures. The present disclosure also includes various modifications and modifications within an equal range. In addition, various combinations and forms, as well as other combinations and forms that include only one element, more, or less, are also within the scope of the present disclosure.

In the drawings, 1, 21 are differential pressure type leak test devices, 2, 22 are leak tester bodies, 3, 23 are master containers, 4, 24 are control devices, 8, 11, 13, 15 are heat conductive members, and 9 are corrugated fins. , 12 is a thin metal wire, 14 is a thin metal plate, 16 is a porous metal member, 25 is a master connecting pipe, 27 is an on-off valve, 28 is a switching device, and W is a work.

Claims (6)

Both the work (W) having a cavity and the master container (3) having an airtightness are sealed, high-pressure gas is injected into the inside, and the pressure difference between the inside of the work cavity and the inside of the master container is measured. A differential pressure type leak test device (1) that inspects the airtightness of the work based on the above.
Inside the master container, heat conductive members (8, 11, 13, 15) are provided, which are thermally connected to the inner wall of the master container to increase the internal surface area while securing the internal volume. With
A differential pressure type leak test device including a control device (4) that executes a warm-up operation in which high-pressure gas is injected and exhausted into the master container at regular time intervals when starting an inspection. The differential pressure type leak test device according to claim 1, wherein the heat conductive member (8) is composed of corrugated fins (9) arranged in multiple layers. The differential pressure type leak test device according to claim 1, wherein the heat conductive member (11) is composed of a metal wire (12) assembled so as to be solidified. The differential pressure type leak test device according to claim 1, wherein the heat conductive member (13) is composed of a thin metal plate (14) arranged in multiple layers with voids. The differential pressure type leak test device according to claim 1, wherein the heat conductive member (15) is composed of a metal porous member (16). Both the work (W) having a cavity and the master container (23) having an airtightness are sealed, high-pressure gas is injected into the inside, and the pressure difference between the inside of the work cavity and the inside of the master container is measured. A differential pressure type leak test device (21) that inspects the airtightness of the work based on the above.
A differential pressure type leak test device including a switching device (28) in which a plurality of the master containers are provided in a parallel state and the master containers are switched in order as the workpiece to be inspected is switched.

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