JPS5938538B2 - Structure of leak detection tank of inspected object and its inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection tank for leakage testing of objects to be inspected, and is a method for detecting leakage from various equipment and devices that require airtightness, such as cylinders, valves, cocks, and pressure tanks, by water immersion. This is an attempt to easily detect the passing of rising bubbles generated in the detection tank through a required location through a means capable of sensing and detecting the passage of the rising bubbles.

The airtightness of the object to be inspected depends on the accuracy of the equipment, the reliability of the equipment,
This is an essential condition to maintain the safety of the equipment.
For this reason, various pressure leakage inspection and testing devices have been devised and put into practical use for the various devices concerned, based on the water immersion method or the non-water immersion method. Since the method is to pressurize with air and immerse it in water in a water tank and visually observe the presence or absence of air bubbles, if the object to be inspected is a steel system, it may cause rust or prevent rust prevention. Therefore, a drying process is required. 2. In order to visually observe whether bubbles are generated, it is necessary to have a dedicated staff member look at the bubbles, and there is a risk of overlooking the leakage of microbubbles.

3. If the leakage from the very small gap in the inspected object during water immersion does not become bubbles rising due to the influence of surface tension, but only adheres to the part concerned, it is overlooked, and non-water immersion method B, which will be described later, is applied. It lacks detection ability and detection accuracy.

4. Also, the working environment is poor, which tends to cause problems when performing in-process inspections.

There were recognized disadvantages such as: On the other hand, in order to eliminate various drawbacks associated with the water immersion method A, there is a non-water immersion method B, which can be classified into differential pressure detection type A and gas detection type B, as a means of not immersing the inspected object in water. Among them, the differential pressure detection type a connects the test object and the reference object in parallel via multiple valves, and then pressurizes both at the same time to achieve equilibrium, and then closes the required valves. For example, the presence or absence of differential pressure between the two can be detected using a highly sensitive pressure differential, such as a pressure-electric transducer or a pressure amplifier, which is recognized as part of the configuration of the "leakage inspection device" shown in Japanese Patent Application Laid-open No. 50-22685. Not only does it require the use of a sensor and an air logic circuit port attached to it, but it also requires the reference body itself, making it a complex and expensive device that lacks versatility. Using a U-shaped tube that detects differential pressure through a switch or visual observation, it is difficult to strictly control the water level, and in the event of a large leak, the liquid inside the tube may blow out or become discolored due to the relationship with the glass tube. It is necessary to use water,
Furthermore, there were also difficulties in its operability and maintainability.

On the other hand, the object to be inspected is placed inside a vacuumed inspection chamber,
According to gas detection type B, which fills and pressurizes an inert gas into the subject body and checks whether there is a gas leak through a detector,
Although it has excellent detection accuracy, it requires a large-scale inspection device, the cost of the device is high, and it lacks versatility. In addition, the "leak visual inspection device" shown in JP-A-49-54086 and the "liquid seal type leak-visual device" shown in JP-A-49-32689, which can be found here and there as other prior art, are both The method of visually observing the presence or absence of bubbles by inserting a thin tube downward into the liquid sealed in a transparent pressure-resistant container or pressure chamber is adopted, which eliminates the drawbacks associated with the visual observation described above. However, it lacked usefulness as a pressure leak inspection means for many types of equipment, and its detection accuracy was still insufficient.

In view of the above points, the present invention not only aims to eliminate the drawbacks associated with the water immersion method, but also eliminates the need for a reference body to be compared with the object to be inspected, a sealing pressurizing device for the same, etc., and the device itself It is possible to efficiently and quickly test a large number of devices through a uniquely structured detection tank that simplifies operation and maintainability, and a series of testing devices.

An embodiment of the present invention will be described with reference to the accompanying drawings. T is a detection tank for leakage inspection of the object to be inspected It consists of a lower tank 1, an upper tank 2, a narrow tube 3 for bubble passage, and a bypass pipe 4 for pressure balance, which are integrally molded or connected in an hourglass-like shape, and the detection liquid 5 is supplied to an appropriate height of the upper tank 2. It is enclosed. The lower tank 1 and the upper tank 2 are arranged to face each other vertically, and the base 5 has a tapered (conical) lower tank 1 whose upper head is hemispherical or gradually becomes smaller in diameter.
A lid member 6 is attached to the upper tank 2, which has a tapered (conical) shape with a hemispherical or gradually smaller diameter lower bottom portion, and seals the detection tank T. In addition, a transparent bubble passage thin tube 3 is interposed at the axial position between the two tanks 1 and 2, and connects the lower end side wall port 5 of the lower tank 1 and the bottom side wall port 5 below the liquid level of the upper tank 2. A pressure balancing bypass pipe 4 is fixed between them. At the center of the lower end of the lower tank 1, a nozzle hole 7 is arranged upward facing the axial position of the thin tube 3, and is connected to external air supply lines Ll and L2.
An exit port 8 connected to the test object side line L4 is provided on the upper end side wall portion of the test piece. At this time, the size of the bubble 8 formed through the nozzle hole 7 is a diameter that allows the rising bubble C to pass through while contacting the inner wall surface of the thin tube 3, that is, the bubble diameter ≧
The inner diameter of the tube is the same. Z is a detection device that photoelectrically detects the passage of rising bubbles 5 generated from the nozzle hole 7 of the lower tank 1 through the inner wall surface of the thin tube 3, and detects the passage of the rising bubbles 5 through the inner wall surface of the thin tube 3 through the detection parts 9 on both sides of the thin tube 3, the detection line L5, and the power amplifier 10. This causes the leakage indicator 11 to respond accordingly.

As shown in FIG. 2, a light emitting body 13 such as an incandescent light bulb or a light emitting diode is connected to one side of the sensing portion 9 of the thin tube 3 through a slit plate 12 in which a fine hole is formed, and a light emitting body 13 such as an incandescent light bulb or a light emitting diode is connected to the other side of the thin tube 3 through a slit plate 12 in which a fine hole is formed. A photoreceptor 15, which is a photoelectric conversion element such as a phototransistor or the like, is installed inside the photoreceptor 15 with a plate 14 interposed therebetween. At this time, the aperture of each microhole in the slit plates 12 and 14 and the amount of light generated by the light emitting body 13 are controlled to minimize the amount of light transmitted to the photoreceptor 15 through the inner wall surface of the thin tube 3, that is, the amount of light that goes around, and The value is set in accordance with the characteristics of the photoreceptor 15 so that the difference in the amount of light transmitted through the thin tube 3 due to a change in the refractive index of water (detection liquid) and air (bubbles) can be most efficiently transmitted to the photoreceptor 15. The power amplifier 10 has built-in well-known circuit elements that supply light emission power to the light emitter 13 and amplify the signal from the photoreceptor 15. The leakage display device 11 is configured to be able to sound an alarm or display a lighting display via the detection line L5 when bubbles rise and pass through the inner wall surface of the thin tube 3. Next, to explain the circuit configuration to the detection tank T, the primary pressure air supply line L1, the secondary pressure air supply line L2
It is connected to the nozzle hole 7 in the lower tank 1 through the outlet port 8 of the upper tank 2, and is connected to the equipment to be inspected Y via the inspection object side line L4, and from the secondary pressure air supply line L2. The branched bypass line L3 is connected to the test object side line L4 without intervening the detection tank T.

The primary pressure air supply line L has an air source connection port 16 with an air supply device having a pressure higher than the inspection pressure,
Pressure control switch 17 that has the function of stopping the inspection device itself when the pressure of the air source drops below the inspection pressure
, an air filter 18 that removes oil cysts, water droplets, dust, etc. from the air and prevents contamination of the detection liquid 5.
, pressure reducing valve 19 for inspection pressure setting with precise secondary pressure stability;
Pressure gauge 20 for inspection pressure setting and checking, pressure reducing valve 1
An exhaust throttle valve 21 is connected to the secondary pressure air supply line L2, and the exhaust throttle valve 21 has a function of setting the pressure to the minimum value that is sufficient to stably operate the test pressure 9 and increase the stability of the test pressure. The supply line L2 includes a main switching valve 22 for supplying air to the inspection device only during testing, a switching valve 23 for supplying water to the detection liquid 5, and a check valve 24.
They are connected in this order to provide conduction into the lower tank 1. The water supply switching valve 23 is connected to the water supply pipe 2 from the water storage tank 25 or the water faucet itself when the liquid level in the detection tank T drops below a certain level.
The facility is equipped with a water supply system that can be directly supplied via water pipe 6. Test object side line L4 connected to the outlet port 8 of the upper tank 2
, a throttle valve 2 is provided to prevent the detection liquid 5 from boiling and blowing out to the outside when a large leak occurs from the test object X.
7. A preload detection changeover valve 28 and an inspection start changeover valve 29 for supplying preload and detection air to the object x to be inspected are successively installed and connected to the apparatus Y to be inspected.

Incidentally, between the outlet port 8 and the throttle valve 28, an exhaust switching valve 30 is provided in a line branching from the line L4. This is the switching valve 30 when water is supplied to the detection tank T.
It is used when the valve is opened to release the accumulated air in the upper tank 2, and the water supply switching valve 23 is switched to supply water. The bypass line L3 is branched between the output switching valve 22 and the water supply switching valve 23, and is provided between the preload/inspection switching valve 28 of the inspection object side line L4, and sends preload air to the inspection object X. It is a line that can supply air. In addition, the device to be inspected Y
The rod end 5 of the cylinder 37 is connected to the air supply line L6 through the air source connection port 31, filter 32, pressure reducing valve 33, pressure gauge 34, luplicator 35, and switching valve 36.
and the head end 5, and a sealing member 40 is embedded in the pressing head 39 at the end of the piston rod 38.
A conduit 41 is bored through which the central part and the side part communicate with each other, and is connected to the end of the line L4 on the side to be inspected.

42 is an inspection jig in which the seal member 43 is embedded;
A fitting part 46 between an upper cylinder member 44 and a lower cylinder member 45 is brazed to internally support an object to be inspected.

47 is a micro switch that detects the completion of clamping of the object to be inspected.

Next, the operating process of the inspection and detection device according to the present invention was configured as shown in the overall schematic diagram of FIG. 1, and an air supply device (not shown) was connected to each air source connection port 16, 31. Explain by condition.

First, the main switching valve 22 is opened in response to an inspection preparation command, and the pressure reducing valve 19 is set to an appropriate inspection pressure.

As a result, a large number of bubbles are generated from the nozzle hole 7 through the secondary pressure air supply line L2, rise up, and pass through the detection tank T.
Further, the pressure in the line L4 on the side of the object to be inspected up to the inspection start switching valve 29 via the bypass line L3 is increased to the inspection setting pressure to complete the inspection preparation (first step). This is transmitted to the switching valve 36 of the device to be inspected Y, and the pressing head 39 at the end of the piston rod 38 is moved downward, thereby moving the object to be inspected
42 (second step). Completion of clamping is detected by the micro switch 47, and is transmitted to the inspection start switching valve 29 to open it and pressurize the inside of the inspected object X to the inspection pressure (third step).

The completion of pressurization is communicated to the preload/detection switching valve 28 and a circuit switching operation is performed, and the supplied air passes through the detection tank T to the object to be inspected
(4th step). If there is a leak in the fitting part 46 of the object to be inspected X in such a state,
This causes a pressure drop in the detection tank T corresponding to the amount of leakage, and as a result, the pressure balance with the nozzle hole 7 side is broken, and bubbles 8 corresponding to the pressure drop are generated from the nozzle hole 7. . The air bubbles 8 rise through the lower tank 1 and reach the bubble passage application capillary tube 3, but at this time, as the rising bubbles pass through the inner wall surface of the capillary tube 3 in contact with each other, the volume of the air bubbles 8 remains in the lower tank 1. A negative pressure corresponding to . However, a pressure balancing bypass pipe 4 is fixedly installed between the lower tank 1 and the upper tank 2, and the detection liquid Q corresponding to the volume of the bubbles 8 is supplied from the side wall port 5 below the liquid level of the upper tank 2. Since the air bubbles are replenished and circulated downward, the air bubbles 8 can smoothly pass through contact with the inner wall surface of the thin tube 3, thereby preventing the air bubbles 8 from stopping at that point. Therefore, when the bubbles 8 pass through the detection unit 9, the refractive index of light changes due to the influence of the bubbles 8, and the transmitted light from the light emitter 13, which would have reached the photoreceptor 15 when there were no bubbles, decreases. , the change is converted into a change in the amount of electricity, and the amplifier 1
After being amplified by 0, the signal is transmitted to the leakage display device 11 and an alarm is sounded. Thereby, it is possible to detect whether or not the object to be inspected is leaking. Further, if there is no leakage in the object X to be inspected, the inspection start switching valve 29 is closed after a certain inspection time, and at the same time, the preload/detection switching valve 28 and the switching valve 36 are operated to return to their original positions. Then, the piston rod 38 also moves upward and returns (fifth step). Through this series of inspection steps, the leakage of the object X to be inspected is automatically inspected. As a modification in which the detection tank T of the present invention is interposed, the circuit is configured without providing the bypass line L3, the water supply switching valve 23, and the preload/detection switching valve 28, and the detection tank T is installed in substantially the same process as described above. It is also possible to perform a leakage test on the test object X. In addition, in the present invention, external air supply (air) lines Ll and L2 are connected to the nozzle hole 7 of the lower tank 1, but conversely, the test object side connected to the outlet port 8 of the upper tank 2 is connected to the nozzle hole 7 of the lower tank 1. It is also possible to apply vacuum suction from the air line L4 side and perform a leakage test similar to that described above.

The present invention provides a leakage testing device for an object to be inspected, which is configured to put a detection liquid into a tube for bubble passage as described above and photoelectrically detect the bubbles rising and passing through the tube, in which:
An upper tank having an upper port connected to an external air line and a lower tank having a nozzle hole connected to an external air line are connected and fixed to the lower part of the pipe body, and provided between the two tanks. The tubular body is configured as a bubble passage thin tube having a diameter through which the bubbles generated in the nozzle hole slide upwardly and pass through the inner wall surface of the tubular body, and the port of the lower tank and the port of the upper tank are connected to a pressure balancing bypass pipe. Since the leak detection tank has a unique structure in which the detection liquid is sealed up to at least the port position of the upper tank, various drawbacks associated with the water immersion method can be solved, and the test object This eliminates the need for a reference body to be compared with, a sealing pressurizing device for the same, etc., the device itself can be simplified, has excellent operability and maintainability, and can efficiently and quickly test a large number of devices.

Moreover, in the present invention, since the pressure balancing bypass pipe is fixedly installed between the lower tank and the upper tank, if the bypass pipe is not provided, the generated air bubbles pass through the inner wall surface of the thin pipe for passing through while being in contact with the inner wall surface of the thin pipe. In this case, a negative pressure corresponding to the volume of the bubbles is generated in the lower tank, which acts to prevent the bubbles from rising and passing through. However, by providing the bypass pipe as described above, Since the detection liquid corresponding to the volume of the bubbles is supplied and circulated downward from the port, the rising bubbles can smoothly pass through contact with the inner wall surface of the thin tube, and the bubbles can be prevented from stopping at that point. In particular, in the present invention, the diameter of the capillary tube for air bubble passage is
Since the aperture is configured such that the bubbles generated in the nozzle hole rise and pass through sliding contact with the inner wall surface of the tube, the amount of light generated by the luminous body is lower than that of bubble detection means that simply passes through the inner wall surface of the tube without sliding contact. This not only minimizes the loss of light quantity caused by the loss of light as it travels along the inner wall surface of the tube, but also minimizes the
In order to efficiently transmit the difference in the amount of light transmitted through the capillary tube due to the change in the refractive index of the light to the photoreceptor side, it has various effects such as eliminating detection errors and contributing to a dramatic improvement in inspection accuracy.

[Brief explanation of drawings]

The drawings illustrate embodiments of the present invention, and FIG. 1 is an overall schematic view of the inspection device, and FIG. 2 is a plan cross-sectional view of the detection portions formed on both sides of the bubble passage application capillary.

Claims (1)

[Scope of Claims] 1. In a leakage testing device for a test object configured to fill a tube for bubble passage with a detection liquid and photoelectrically detect bubbles rising and passing through the tube, an external An upper tank having an upper port connected to the air line of The body is configured as a bubble passage thin tube having a diameter through which the bubbles generated in the nozzle hole slide upwardly and pass through the inner wall surface of the tube, and the port of the lower tank and the port of the upper tank are connected by a bypass pipe for pressure equalization. A leakage detection tank for an object to be inspected, characterized in that the detection liquid is sealed up to at least a port position of the upper tank. 2. In the leak testing device for a test object as set forth in claim 1, the upper head of the lower tank is hemispherical or conical, a base is fixed to the lower bottom of the lower tank, and the upper head of the lower tank is fixed to the lower bottom of the lower tank. The lower bottom part is hemispherical or conical, a lid member is fixed to the upper head of the upper tank, and the center of the bottom of the upper tank and the center of the head of the lower tank are configured to freely communicate with each other through a thin tube for passing air bubbles. A leakage detection tank for a test object, characterized by: 3. In the leakage testing device for an inspected object according to claim 1 or 2, the pressure balancing bypass pipe is connected to a side wall port on the lower end side of the lower tank and a side wall port on the bottom side below the liquid level of the upper tank. A leak detection tank for an object to be inspected, characterized in that the tank is fixed in a manner that allows communication between the tank and the tank.