JP2007147559A - Leak inspection method and leak inspection apparatus - Google Patents

Abstract

The present invention provides a leak inspection method and a leak inspection apparatus capable of efficiently performing a leak inspection in a short time without damaging an object to be inspected.
After supplying a certain amount of fluid to the object to be inspected or discharging a certain amount of fluid from the object to be inspected, the object to be inspected is sealed for a certain time, and then the object to be inspected The body is opened, the amount of fluid flowing out or inflowing from the object to be inspected is measured, and the sealing property of the object to be inspected is checked from the difference in the amount of fluid entering and exiting the object to be inspected.
[Selection] Figure 1

Description

  The present invention relates to a leak inspection method and a leak inspection apparatus capable of efficiently inspecting the hermeticity of an object to be inspected in a short time without damaging the object to be inspected.

  Many electrical components typified by automobile headlights and the like are required to be sealed, such as being filled with an inert gas. As a method for checking the tightness of this type of electrical equipment, fluid is supplied and discharged so as to keep the pressure inside the inspected body forming a sealed container constant, and fluid inflow and outflow are separated by a certain interval. Is known, and the amount of fluid leak is determined from the flow rate difference (see, for example, Patent Document 1).

Further, by applying a constant inspection pressure to each of the object to be inspected and the reference container, and then connecting the object to be inspected and the reference container and measuring the flow rate of fluid flowing between them, the leakage in the object to be inspected is measured. It is also known to check for the presence or absence (for example, Patent Document 2). Furthermore, the flow rate of the gas flowing out from or flowing into the inspection object due to the temporal change of the pressure in the inspection object due to the fluid flowing out or inflowing from the inspection object, or from the inspection object pressurized or depressurized above the atmosphere It has also been proposed to measure the amount of leakage by measuring (see, for example, Patent Document 3).
Japanese Patent Publication No.52-24436 JP-A-3-77041 Japanese Patent Laid-Open No. 10-185749

  However, in the conventional leak inspection method described above, it is easily affected by the temperature of the object to be inspected and the ambient temperature, and it takes a long time to pressurize / depressurize the object to be inspected. If the pressure is excessively increased / decreased, there is a possibility that the object to be inspected may be damaged due to this. Moreover, if the object to be inspected is manufactured by injection molding and sent to the inspection process before it is sufficiently cooled and solidified, the object to be inspected may be deformed with the pressurization / decompression. .

  The present invention has been made in view of such circumstances, and its object is to provide a leak inspection method and a leak inspection capable of efficiently performing the leak inspection in a short time without damaging the object to be inspected. To provide an apparatus.

  In order to achieve the above-described object, the present invention, for example, after supplying a constant amount of fluid to the object to be inspected or discharging a constant amount of fluid from the object to be inspected, pressurizes or depressurizes the inside of the object to be inspected. It is noted that when the object to be inspected is sealed for a certain period of time, the amount of fluid in the object to be inspected changes if there is a leak in the object to be inspected. Therefore, in the leak inspection method according to the present invention, after supplying a certain amount of fluid to the object to be inspected or discharging a certain amount of fluid from the object to be inspected, the object to be inspected is sealed for a certain time. Then, the inspection object is opened, the amount of fluid flowing out or inflow from the inspection object is measured, and the sealing property of the inspection object is inspected from the difference in the amount of fluid entering and exiting the inspection object. It is characterized by.

  Incidentally, a mass flow meter is used for the amount of fluid supplied to or discharged from the object to be inspected and the amount of fluid flowing out or inflowing from the object to be inspected when the object to be inspected is opened. It is preferable to obtain the integrated value of the measured mass flow rate. Further, the supply of a certain amount of fluid to the object to be inspected or the discharge of a certain amount of fluid from the object to be inspected is performed by selectively connecting a pressure source or a decompression source to the object to be inspected. It is enough.

  In another leak inspection method according to the present invention, a predetermined amount of fluid is supplied to a container containing a sealed object to be inspected, or after a predetermined amount of fluid is discharged from the container, the container is kept at a predetermined time. Sealing, and then opening the container, measuring the amount of fluid flowing out or inflowing from the container, and inspecting the sealing property of the object to be inspected from the difference in the amount of fluid entering and exiting the container. It is a feature.

  In this case as well, the amount of fluid supplied to or discharged from the container and the amount of fluid flowing out or inflow from the container when the container is opened are measured using a mass flow meter. It is preferable to obtain the integrated value of. Further, it is sufficient to supply a certain amount of fluid to the container or to discharge a certain amount of fluid from the container by selectively connecting a pressure source or a reduced pressure source to the container.

Moreover, the leak inspection apparatus according to the present invention includes:
<a> a first valve that selectively connects a pressurized source or a reduced pressure source to the object to be inspected or a sealed container to be inspected;
<b> a second valve for selectively opening the object to be examined or the container;
<c> a mass flow meter for measuring the mass flow rate of the fluid entering and exiting the object to be inspected or the container through the first or second valve;
<d> The first valve is opened to supply a constant amount of fluid to the object to be inspected or the container, and after discharging a predetermined amount of fluid, the first valve is closed to close the target object. A valve control means for sealing the inspection object or the container for a certain period of time, and then opening the second valve;
<e> Under this valve control means, the amount of fluid flowing into and out of the object to be inspected or the container is respectively determined by the mass flow meter, and the sealing property of the object to be inspected is checked from the difference in the amount of fluid. And an inspection means.

  Also in this leak inspection apparatus, the amount of fluid entering and exiting the container may be obtained as an integrated value of the mass flow rate of the fluid measured by the mass flow meter. In general, it is sufficient to use the above-mentioned fluid by pressurizing or depressurizing air, but it is of course possible to use nitrogen gas or the like in some cases. A mass flow meter having a flow rate control function may be used.

  According to the leak inspection method of the present invention, after supplying a certain amount of fluid to the object to be inspected or discharging a certain amount of fluid from the object to be inspected, the object to be inspected is sealed for a certain period of time, After that, the amount of fluid flowing out or inflowing from the object to be inspected with the opening of the object to be inspected is measured, and the difference in the amount of fluid entering and exiting the object to be inspected is inspected for the presence or absence of leakage. A leak test can be performed easily. In particular, when a certain amount of fluid is supplied to the object to be inspected while measuring the flow rate of the fluid, or when a certain amount of fluid is discharged and the object to be inspected is opened after being sealed for a certain period of time. Since it is only necessary to measure the amount of fluid flowing out from or flowing into the object to be inspected, the inspection work is very simple.

  In addition, since the fluid is supplied to the object to be inspected or the discharge of the fluid from the object is controlled while measuring the flow rate of the fluid, excessive pressure is not applied to the object to be inspected. Further, even if a high pressure source or a decompression source is used, a certain amount of fluid can be accurately supplied / discharged to / from the inspected object, which is required for supplying / discharging the fluid to / from the inspected object. The effect that the time can be shortened and the inspection time can be shortened is exhibited. In particular, since the mass flow rate is measured using a mass flow meter, the leak inspection can be performed with high accuracy without being affected by the temperature change or pressure change of the inspected object and its surroundings. Moreover, the effect that the amount of leakage can be measured with high accuracy is exhibited.

  Instead of supplying a constant amount of fluid to the object to be inspected or discharging a constant amount of fluid from the object to be inspected to increase or decrease the pressure inside the object, the container containing the object to be inspected A certain amount of fluid is supplied, or a certain amount of fluid is discharged from the container to increase or decrease the pressure outside the object to be inspected, and then the container is sealed for a certain period of time, and then the container is opened. If the amount of fluid that sometimes flows out of the container or flows into the container is measured, the inspection object can be inspected for leaks from the outside. Therefore, a container for accommodating the object to be inspected is required, but it is very effective when performing a leak inspection on an object to be inspected that has already been sealed.

  In addition, according to the leak inspection apparatus of the present invention, the first valve that selectively connects a pressure source or a reduced pressure source to the object to be inspected or a container containing the sealed object to be inspected, and the object to be inspected Or a second valve that selectively opens the container, and only measures the flow rate of fluid entering and exiting the object to be inspected or the container while controlling the opening of the first and second valves, respectively. Therefore, the configuration is simple and the control is simple, and furthermore, the mass flow rate of the fluid can be accurately measured using a mass flow meter, so that the accuracy of leak inspection can be made sufficiently high, etc. An effect is produced.

DESCRIPTION OF EMBODIMENTS Hereinafter, a leak inspection method according to an embodiment of the present invention with reference to the drawings and a leak inspection apparatus suitable for carrying out this inspection method will be described. For example, an automotive headlamp (lamp unit) manufactured by injection molding, etc. A leak inspection using a sealed part as an inspection object will be described as an example.
FIG. 1 is a schematic configuration diagram showing a first embodiment of a leak inspection apparatus, and A shows an object to be inspected which is a target of a leak inspection. This leak inspection apparatus basically includes a first pipe line 2 that forms a supply path for fluid (for example, air) to the object A via a first valve (valve) 1 and a second valve. (Valve) 3 is provided with a second conduit 4 that forms a discharge passage for fluid from the object A to be inspected, and mass flow meters 5 and 6 are inserted into these conduits 2 and 4, respectively. Composed. The measurement control unit 7 selectively controls the opening of the first and second valves 1 and 3 as will be described later, and the flow rate of the fluid entering and exiting the inspected object A along with this is controlled by the mass flow rate. Measured by a total of 5 and 6, respectively, and the presence or absence of leakage of the inspected object A is determined from the difference in the amount of fluid flowing into and out of the inspected object A (inflow / outflow) indicated as the integrated value of the flow rate It is supposed to be.

  In the leak inspection apparatus configured as described above, a pressurizing source 8 such as a booster pump is provided in the first pipeline 2 to supply a constant amount of fluid to the object A to be inspected. When connected, the second conduit 4 is opened to the atmosphere, and a vacuum pump is connected to the second conduit 4 to discharge a certain amount of fluid from the object A to be inspected and to perform a leak test. When the decompression source 9 is connected, the first pipe line 3 is opened to the atmosphere.

  FIG. 2 shows a procedure for performing a leak test, which is performed by supplying a certain amount of fluid (air) to the inspected object A, specifically using the leak test apparatus configured as described above. A schematic control procedure of the measurement control unit 7 is shown. As described above, the leak inspection is performed in a state where the pressurizing source 8 such as a booster pump is connected to the first conduit 2 while the second conduit 4 is opened to the atmosphere. Then, the measurement control unit 7 first opens the first valve 1 and supplies the fluid supplied from the pressurizing source 8 to the object A to be inspected [Step S1]. The fluid is supplied from the pressurization source 8 to the object A to be inspected while measuring the mass flow rate of the fluid with the mass flow meter 5 inserted in the first pipe 2, and integrating the mass flow rate. This is performed until the value (inflow amount) Qin reaches a certain amount. By supplying a certain amount of fluid to the inspection object A, the internal pressure of the inspection object A is increased to a predetermined pressure. When a certain amount of fluid is supplied to the object A, the object A is sealed by closing the first valve 1 [step S2].

  Thereafter, the first and second valves 3 and 4 are kept closed, and the sealed state of the inspected object A is held for a certain time [step S3]. This sealing time is set according to the specification of the inspection object A, the amount of fluid (pressure) supplied to the inspection object A, and the like. When the predetermined time has elapsed, the second valve 4 is opened, and the fluid supplied to the object A to be inspected is discharged to the outside (atmosphere) via the second conduit 4 [Step S4]. At this time, the mass flowmeter 6 inserted in the second pipe 4 is used to measure the flow rate of the fluid flowing out from the object A to be inspected, and the accumulated flow value flows out from the object A to be inspected. The amount (outflow amount) Qout of the fluid is obtained [Step S5].

  Then, the fluid supply amount (inflow amount) Qin to the inspected object A measured using the mass flow meter 5 and the outflow of the fluid from the inspected object A measured using the mass flow meter 6. A difference ΔQ from the amount Qout is obtained, and the amount of fluid leakage (leakage) in the inspection object A is evaluated from the difference ΔQ [step S6]. That is, when there is no leak in the inspected object A, the fluid supplied to the inspected object A flows out from the inspected object A with the opening of the second valve 3, and naturally the outflow amount Qin Is equal to the fluid supply amount Qin to the inspected object A. However, if there is a leak in the inspected object A, the fluid supplied to the inspected object A gradually leaks during the sealing period of the inspected object A as shown in FIG. As a result, the amount of fluid flowing out from the object A to be inspected with the opening of the second valve 3 decreases, and the fluid outflow amount Qout at that time is smaller than the inflow amount Qin described above.

  Accordingly, as described above, the inflow amount Qin of the fluid into the inspected object A and the outflow amount Qout of the fluid from the inspected object A are respectively measured, and the difference ΔQ between them is obtained to determine the leakage of the inspected object A. It is possible to accurately evaluate the presence / absence, and hence the leak amount, as the difference ΔQ. In other words, the inflow amount Qin of the fluid supplied to the inspected object A is compared with the outflow amount Qout of the fluid that flows out from the inspected object A after sealing the inspected object A for a certain time. When the amount Qin and the outflow amount Qout are different, it can be determined that the fluid is flowing out from the inspected object A even though the inspected object A has been sealed for a certain period of time. As a result, it is possible to detect the presence of a leak location in the inspection object A.

  In the above-described embodiment, whether a fluid leaks from the inspection object A in a state where the inspection object A is supplied with a certain amount of fluid to increase the internal pressure of the inspection object A and the inspection object A is sealed. Was judged. However, instead of the pressure source 8 described above, a decompression source 9 is connected, and a constant amount of fluid (air) is discharged from the object A to be inspected to lower the internal pressure of the object to be inspected. Sealing may be performed to determine whether or not fluid (air) enters the inspected object A. That is, the discharge amount Qout of the fluid from the inspection object A and the amount Qin of the fluid flowing into the inspection object A after sealing for a certain time are measured, and the inflow amount Qin and the outflow amount Qout are compared. In this way, the leakage of the inspected object A can be similarly determined.

  In the above-described embodiment, the amount Qin of the fluid supplied (flowed in) to the object A to be inspected using the two mass flow meters 5 and 6 and the amount Qout of the fluid discharged (flowed out) from the object A to be inspected. Although each was measured independently, if a bi-directional mass flow meter capable of measuring the flow rate regardless of the flow direction of the fluid is used, it is possible to leak only by using one mass flow meter 5 as shown in FIG. An inspection device can be constructed. That is, the mass flow meter 5 is connected to the fluid input / output port (leak test port) of the inspected object A, and the first pipe line 1 and the second pipe line 3 are branched through the mass flow meter 5. These valves 1 and 3 may be provided with valves 2 and 4 respectively. Even if the leak inspection apparatus is configured in this manner, the leak inspection of the inspected object A can be performed in the same manner as in the previous embodiment.

  By the way, in each embodiment mentioned above, the internal pressure of the to-be-inspected object A was made higher or lower than the outside, and the leak between the outside was inspected. However, for example, when the inspected object A is sealed in advance, a container 10 that can accommodate the inspected object A is prepared as shown in FIG. The container 10 is sealed after supplying or discarding the fluid (air), and when the container 10 is opened, the amount of fluid flowing out of the container 10 or the amount of fluid flowing into the container is measured. Also good. The container 10 has been confirmed in advance to be free from leaks.

  According to such an inspection method using the container 10, the pressure inside the container 10 containing the object A to be inspected, that is, the external pressure of the object A to be inspected is kept constant while keeping the internal pressure of the object A to be inspected constant. Since it can be increased by supplying a certain amount of fluid or lowered by discharging a certain amount of fluid, a pressure difference is applied to the inside and outside of the inspection object A in the same manner as in the previous embodiment, and leakage of the inspection object A is reduced. Existence can be checked. Specifically, if there is a leak in the inspected object A, the fluid supplied to the container 10 gradually enters the inspected object A during the sealing period of the container 10 for a certain period of time. The amount of fluid flowing out of the container 10 when opening is reduced. Therefore, if the supply amount Qin of the fluid supplied to the container 10 and the outflow amount Qout of the fluid flowing out from the container 10 are measured, the presence or absence of leakage of the object A is detected from the inflow amount Qin and the outflow amount Qout. It becomes possible to do.

  When a certain amount of fluid is discharged from the container 10 and the pressure of the container 10 is lowered, the fluid enclosed in the object A to be inspected gradually during the sealing period of the container 10 for a certain time. Flows out. As a result, the amount of fluid flowing out of the container 10 increases when the container 10 is opened. Similarly, by comparing the inflow amount Qin and the outflow amount Qout of the fluid into the container 10, the leakage of the inspected object A can be reduced. The presence or absence can be detected. Therefore, if such a leak inspection method is employed, even if the inspection object A is already sealed, the leakage inspection can be performed without unsealing the inspection object A. So its practical advantages are tremendous.

  Thus, according to the leak inspection method and the leak inspection apparatus shown in the above-described embodiments, a certain amount of fluid is supplied to and discharged from the object A or the container 10 containing the object A, and then the object A to be inspected. Alternatively, the container 10 is sealed for a certain period of time, and whether or not the fluid is moving between the inside and the outside of the object A during the sealing period is opened. Since the determination is made by measuring the amount of fluid flowing out or flowing in, the leak of the object A can be inspected easily and reliably. Moreover, since the inflow amount Qin and the outflow amount Qout are measured while measuring the mass flow rate of the fluid using the mass flowmeters 5 and 6, for example, regardless of the inspected object A, the ambient temperature, and further the temperature change. The leak inspection can be performed accurately. Therefore, even if the inspection object A is manufactured by injection molding of plastic or the like and is subjected to a leak inspection before the heat removal is sufficiently performed, it is affected by the residual heat. A leak test can be performed without any problems. In particular, even when the pressure of the fluid changes depending on the ambient temperature, the leak inspection can be performed regardless of the pressure, so that there is an advantage that it is not necessary to allow time for the pressure to stabilize. That is, the leak inspection can be performed with high accuracy without being affected by temperature and pressure.

  In addition, as described above, since only a fixed amount of fluid is supplied to or discharged from the inspected object A while monitoring the flow rate of the fluid, an extra pressure load is not applied to the inspected object A. The leak test can be performed without damaging the system. In addition, since a constant amount of fluid is supplied to or discharged from the inspected object A while monitoring the flow rate of the fluid, the pressurizing source 8 or the decompressing source 9 is used to supply fluid at high speed by using a high pressurizing / depressurizing capability. Even if it is discharged, the supply amount or the discharge amount can be made constant with high accuracy. Therefore, the time required for the leak inspection can be shortened by the amount that can supply / discharge fluid at high speed.

  The present invention is not limited to the embodiment described above. For example, the amount of fluid supplied to the inspection object A may be measured in advance and prepared in a cylinder or the like, and this may be supplied to the inspection object A. Further, an inert gas such as nitrogen may be used as the fluid. In this case, the air present inside the inspection object A and the inert gas are mixed, so the amount of fluid flowing out from the inspection object A is multiplied by a predetermined coefficient, and the outflow amount is calculated. Just ask for it. Further, when inspecting the inspection object A in which the inert gas is sealed in advance, the outflow amount of the fluid may be corrected similarly.

  In addition, when sequentially performing a leak test on a plurality of test objects A under a certain condition, a change characteristic of the flow rate of the fluid flowing out when the test object A is opened is examined in advance, and the fluid during the leak test is checked. You may make it investigate how the amount of outflow changes. In this way, it is possible to determine the presence or absence of a leak before the outflow of fluid from the object A to be inspected completely, so that the time required for the leak inspection can be shortened. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

1 is a schematic configuration diagram of a leak inspection apparatus according to an embodiment of the present invention. The figure which shows the process sequence of the leak test | inspection method performed using the leak test | inspection apparatus shown in FIG. The figure which shows the concept of a leak test | inspection. The schematic block diagram of the leak test | inspection apparatus which concerns on another embodiment of this invention. The schematic block diagram of the leak test | inspection apparatus which concerns on another embodiment of this invention.

Explanation of symbols

A Inspected object 1, 3 Valve 2, 4 Pipe line 5, 6 Mass flow meter 7 Measurement control unit 8 Pressurization source 9 Depressurization source 10 Container

Claims (8)

After supplying a certain amount of fluid to the object to be inspected or discharging a certain amount of fluid from the object to be inspected, the object to be inspected is sealed for a certain period of time,
Thereafter, opening the object to be inspected, measuring the amount of fluid flowing out or inflowing from the object to be inspected, and inspecting the sealing property of the object to be inspected from the difference in the amount of fluid entering and exiting the object to be inspected. A characteristic leak inspection method.   The amount of fluid supplied to or discharged from the object to be inspected and the amount of fluid flowing out or inflow from the object to be inspected when the object to be inspected is measured using a mass flow meter. The leak inspection method according to claim 1, which is obtained as an integrated value of the mass flow rate.   The supply of a certain amount of fluid to the object to be inspected or the discharge of a certain amount of fluid from the object to be inspected is performed by selectively connecting a pressure source or a decompression source to the object to be inspected. The leak inspection method according to claim 1. Supplying a certain amount of fluid to a container containing a sealed object to be inspected, or after discharging a certain amount of fluid from the container, sealing the container for a certain period of time;
Thereafter, the container is opened, the amount of fluid flowing out or inflow from the container is measured, and the sealing property of the object to be inspected is checked from the difference in the amount of fluid entering and exiting the container. .   The amount of fluid supplied to or discharged from the container and the amount of fluid flowing out or inflow from the container when the container is opened are obtained as an integrated value of mass flow rate measured using a mass flow meter. The leak inspection method according to claim 4, which is performed.   5. The supply of a certain amount of fluid to the container or the discharge of a certain amount of fluid from the container is performed by selectively connecting a pressure source or a decompression source to the container. Leak inspection method. A first valve for selectively connecting a pressurized source or a reduced pressure source to a test object or a container containing a sealed test object;
A second valve for selectively opening the object to be examined or the container;
A mass flow meter for measuring the mass flow rate of the fluid entering and exiting the inspected object or the container via these first or second valves;
The first valve is opened to supply a constant amount of fluid to the object to be inspected or the container, and after discharging a constant amount of fluid, the first valve is closed and the object to be inspected. Or valve control means for sealing the container for a certain period of time and then opening the second valve;
Inspection means for determining the amount of fluid entering and exiting the object to be inspected or the container under the valve control means by the mass flow meter, and inspecting the sealing property of the object to be inspected from the difference in the fluid amount; A leak inspection apparatus comprising:   The leak inspection apparatus according to claim 7, wherein the amount of fluid entering and exiting the container is obtained as an integrated value of the mass flow rate of the fluid measured by the mass flow meter.

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