JP2024013126A - Ultrasonic leakage inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably locate a leaked position of an inspected object by accurately locating a position of bubbles floating within an inspection liquid tank.

SOLUTION: An ultrasonic leakage inspection device includes: an inspection liquid tank 1 allowing an inspected object W to go under an inspection liquid L; a transmission portion 2 radiating ultrasonic vibrations to the inspection liquid L of the inspection liquid tank 1; a reception portion 3 receiving ultrasonic vibrations radiated to the inspection liquid L by the transmission portion 2; and a controller 30 detecting bubbles B within the inspection liquid L by a reception signal of the reception portion 3. The transmission portion 2 includes multiple ultrasonic vibrators 4 that are aligned sideways at a predetermined interval in a horizontal direction within a first peripheral wall 11. The reception portion 3 includes multiple ultrasonic sensors 5 aligned sideways at a predetermined interval in a horizontal direction within a second peripheral wall 12. The inspection liquid tank 1 includes a humidifier 22 of an elevating mechanism 20 forcibly raising the bubbles B by an ascending stream for raising the inspection liquid L. The controller 30 detects the bubbles B that are accelerated by the ascending stream of the inspection liquid L and rise by reception signals detected by the respective ultrasonic sensors 5 and detects leakage and leaked positions of the inspected object W.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a device that uses ultrasonic waves to detect air bubbles floating in a liquid to detect leaks and leak locations in a test object. This invention relates to an ultrasonic leak testing device that is most suitable for detecting the location of leaks.

The present inventor has developed a device that detects pinholes, cracks, etc. in hollow parts with sealed structures, such as gasoline tanks and mufflers, by detecting minute bubbles floating in liquid. (See Patent Document 1). This inspection device seals the opening of the object to be inspected and submerges it in a test liquid such as water, then pressurizes air into the object to prevent air leakage from minute gaps such as pinholes. Detect air bubbles.

Japanese Patent Application Publication No. 2020-143939

The perspective view of FIG. 17 shows an ultrasonic leak testing device 900 that was previously developed by the present inventor. This inspection device 900 pressurizes pressurized air into the test object W while the test object W is submerged in the test liquid L to check for air bubbles B leaking out from gaps caused by pinholes or cracks. is detected to inspect the object W for leakage. The inspection apparatus 900 shown in this figure includes a test liquid tank 1 in which an object to be inspected W is immersed in a test liquid L, and a test liquid tank 1 that is placed inside the test liquid tank 1 and emits ultrasonic vibrations toward the opposing surface of the test liquid tank 1. a transmitting section 2 that receives ultrasonic vibrations emitted by the transmitting section 2 and a receiving section 3 that is disposed inside the test liquid tank 1 and receives the ultrasonic vibrations emitted by the transmitting section 2; The controller 30 detects bubbles B.

The transmitter 2 includes a plurality of ultrasonic transducers 4 arranged horizontally inside the test liquid tank 1, and the receiver 3 includes a plurality of ultrasonic transducers 4 arranged horizontally inside the test liquid tank 1. A sound wave sensor 5 is provided. The transmitter 2 divides the plurality of ultrasonic transducers 4 into a plurality of blocks 2X, and the ultrasonic transducers 4 of adjacent blocks 2X emit ultrasonic vibrations of different frequencies. The ultrasonic vibrations emitted by each ultrasonic transducer 4 in the horizontal direction are reflected by air bubbles, and the reflected waves are received by the ultrasonic sensor 5 . The controller 30 detects the bubbles B floating in the test liquid L using the reflected waves of the bubbles received by the receiving section 3 . The controller 30 can detect the floating bubble B by calculating the received signal. The controller 30 can detect a bubble by detecting a frequency shift of a reflected wave reflected by a floating bubble using the Doppler effect, for example.

The ultrasonic atomization device 900 of FIG. 17 has a plurality of ultrasonic transducers 4 and a plurality of ultrasonic sensors 5 arranged side by side and facing each other, and the ultrasonic sensors 5 are arranged at opposing positions. The reflected wave of the bubble B of the ultrasonic vibration emitted by the child 4 is detected. This ultrasonic atomization device 900 horizontally divides an area for emitting ultrasonic vibrations into a plurality of detection zones, and arranges an ultrasonic vibrator 4 and an ultrasonic sensor 5 to face each detection zone. By specifying the detection zone where the bubbles B are detected, it is possible to specify the area where the inspected object W emits the bubbles B. Bubbles B coming out of the pinhole in the test object W into the test liquid L float in a specific detection zone. However, as the particle size of the bubbles decreases, the buoyancy of the bubbles decreases and the floating speed of the bubbles decreases, so that local fluctuations in the test liquid L may cause the bubbles to move to an adjacent detection zone. Although the test liquid L in the test liquid tank 1 can be kept completely stationary to prevent the bubbles B from moving upward and into the adjacent detection zone, in actual use, the test liquid In reality, it is impossible to maintain L in a completely stationary state. Therefore, a device that divides the test liquid tank 1 horizontally into a plurality of detection zones and detects air bubbles floating in each detection zone cannot accurately identify the leak position when the air bubbles move to the adjacent detection zone. There are drawbacks that go away.

The present invention was developed with the aim of eliminating the above-mentioned drawbacks of the conventional ones.One purpose of the present invention is to detect leakage such as pinholes and cracks in the test object from air bubbles floating in the test liquid. In addition to this, it is an object of the present invention to provide an ultrasonic leak testing device that can accurately identify the location of a leak.

An ultrasonic leak testing device according to an aspect of the present invention detects air bubbles leaking from a test object submerged in a test liquid and floating in the test liquid to detect leakage of the test object. . Ultrasonic leak testing equipment consists of a test liquid tank that submerges the test object in the test liquid, a transmitter that emits ultrasonic vibrations to the test liquid in the test liquid tank, and an ultrasonic vibration that is emitted to the test liquid by the transmitter. It includes a receiving section that receives sonic vibrations, and a controller that detects air bubbles in the test liquid using the received signal from the receiving section. The test liquid tank includes a first circumferential wall and a second circumferential wall that are arranged opposite to each other, and the transmitter includes a plurality of transmitters that are arranged side by side at predetermined intervals inside the first circumferential wall. The receiving unit includes a plurality of ultrasonic sensors arranged side by side at predetermined intervals in the horizontal direction inside the second peripheral wall, and the test liquid tank raises the test liquid. It is equipped with a rising mechanism that forcibly floats air bubbles in the test liquid with an upward flow, the rise mechanism is equipped with a warmer that warms the test liquid and generates an upward flow, and the controller controls each ultrasonic sensor. Using the received signal to detect air bubbles that are accelerated and floated up by the upward flow of the test liquid, the leakage of the object to be inspected and the location of the leakage are detected.

The above-described ultrasonic leak testing device has the advantage of being able to accurately pinpoint the position of air bubbles floating inside the test liquid tank, thereby accurately pinpointing the leak position of the object to be tested.

1 is a schematic perspective view of an ultrasonic leak testing device according to an embodiment of the present invention. FIG. 1 is a vertical cross-sectional view of an ultrasonic leak testing device according to an embodiment of the present invention. FIG. 2 is a vertical cross-sectional view of an ultrasonic leak testing device showing an example in which upward flow circulates. It is a vertical cross-sectional view which shows another example of arrangement|positioning of a warmer. FIG. 1 is a schematic horizontal sectional view of an ultrasonic leak testing device according to an embodiment of the present invention. FIG. 3 is a schematic diagram of a transmission beam emitted from an ultrasonic transducer. FIG. 3 is a plan view showing an example of an ultrasonic vibrating section. It is a top view which shows another example of an ultrasonic vibrating part. It is a graph showing the spectrum of reflected waves when there are no bubbles. It is a graph showing the spectrum of reflected waves when there is one small bubble. It is a graph showing the spectrum of reflected waves when there are multiple small bubbles. It is a graph showing the spectrum of reflected waves when there is one large bubble. It is a graph showing the spectrum of reflected waves when there are a plurality of large bubbles. It is a graph which shows the amplitude waveform of a direct wave when there is no bubble. It is a graph which shows the amplitude waveform of a direct wave when there is a bubble. FIG. 3 is a vertical cross-sectional view showing an example of a drainage part that overflows a test liquid. FIG. 1 is a schematic perspective view of a conventional inspection device.

Hereinafter, the present invention will be explained in detail based on the drawings. In the following explanation, terms indicating specific directions or positions (for example, "upper", "lower", and other terms containing these terms) are used as necessary, but the use of these terms is The purpose of the drawings is to facilitate understanding of the invention with reference to the drawings, and the technical scope of the invention is not limited by the meanings of these terms. Further, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or members. Further, the embodiments shown below are illustrative of specific examples of the technical idea of the present invention, and the present invention is not limited to the following. In addition, the dimensions, materials, shapes, relative arrangements, etc. of the component parts described below are not intended to limit the scope of the present invention, unless specifically stated, but are merely illustrative. It was intended. Furthermore, the content described in one embodiment or example is also applicable to other embodiments or examples. Furthermore, the sizes, positional relationships, etc. of members shown in the drawings may be exaggerated for clarity of explanation.

The ultrasonic leak testing device according to one embodiment of the present invention detects leakage of the test object by detecting air bubbles leaking from the test object submerged in the test liquid and floating in the test liquid. do. Ultrasonic leak testing equipment consists of a test liquid tank that submerges the test object in the test liquid, a transmitter that emits ultrasonic vibrations to the test liquid in the test liquid tank, and an ultrasonic vibration that is emitted to the test liquid by the transmitter. It includes a receiving section that receives sonic vibrations, and a controller that detects air bubbles in the test liquid using the received signal from the receiving section. The test liquid tank includes a first circumferential wall and a second circumferential wall that are arranged opposite to each other, and the transmitter includes a plurality of transmitters that are arranged side by side at predetermined intervals inside the first circumferential wall. The receiving section includes a plurality of ultrasonic sensors arranged side by side at predetermined intervals in the horizontal direction inside the second peripheral wall, and the test liquid tank raises the test liquid. The controller is equipped with a rising mechanism that forcibly floats air bubbles in the rising test liquid, and the rising mechanism is equipped with a warmer that warms the test liquid.The controller uses the received signals detected by each ultrasonic sensor to Air bubbles floating in the liquid are detected to detect leakage of the object to be inspected and the location of the leakage. In the present invention, raising the test liquid refers to moving the test liquid from a lower level to an upper level, and includes flowing the test liquid upward.

The above-mentioned ultrasonic leak detection device can detect leakage of the object to be inspected by detecting air bubbles floating in the test liquid, and can also accurately detect the position of the air bubbles floating in the test liquid to detect the leakage of the object. It has the advantage of being able to accurately identify the location of leaks in the test object. In particular, since fine air bubbles are forcibly raised by the rising test liquid, the test object is placed in the rising area where the test liquid rises, and the air bubbles discharged from the test object are used to remove minute cracks in the test object. It has the advantage of being able to reliably detect objects such as holes and pinholes. In addition to inspecting for leaks, the leakage test for the inspected object also allows cracks and pinholes to be repaired simply, easily, and quickly by pinpointing the location of the leak accurately. Therefore, it is particularly important to accurately identify the location of a leak, especially a minute leak location. This is because it takes time and effort to take out the test liquid from the test liquid tank and visually identify the leak location, and in particular, visually identifying minute leak locations is extremely time consuming and not easy. Accurate detection of leaks and leak locations can also have an economical effect on repairable test objects, as the test object whose leak location has been identified can be used effectively by repairing cracks and pinholes that cause leaks. Extremely large.

Furthermore, the above-mentioned ultrasonic leak testing device warms the test liquid and uses the upward flow of the test liquid generated by the heating to smoothly float air bubbles, so it Bubbles can be quickly raised by the upward flow of the test liquid without stirring the test liquid. Therefore, the bubbles can be raised quickly without changing the state of the bubbles, that is, the physical properties of the bubbles in response to ultrasonic vibrations, making it possible to reliably detect minute bubbles with ultrasonic vibrations and accurately locate the detection position. There are features that can be determined.

Furthermore, the above-described ultrasonic leak testing device has the advantage of shortening the testing time by quickly raising air bubbles with the upward flow generated by heating the testing liquid. This is because by accelerating the bubbles with an upward flow and causing them to float, even minute bubbles that rise slowly can quickly rise to the surface. Leak testing equipment immerses the test object in the test liquid and detects air bubbles emitted from the cracks. This turbulent flow irregularly shifts the floating direction of the bubbles and makes the floating of the bubbles unstable, resulting in a decrease in inspection accuracy. Furthermore, the turbulent flow of the test liquid caused by the submergence of the test object is further reflected on the peripheral wall of the test liquid tank, the bottom plate, and the water surface, and wave interference occurs where multiple waves overlap, strengthening or weakening each other. The direction, speed, amount, etc. change, resulting in an uneven and complex flow state, which causes an increase in the noise component of the detection signal used to detect the presence or absence of bubbles by detecting the ultrasonic waves reflected by the bubbles. Furthermore, when the leak test device moves and/or changes the posture of the test object in the test liquid after submerging the test object in water to remove air bubbles attached to the outer surface of the test object, it may be necessary to use different postures and positions. When testing for leaks, additional flow of the test liquid occurs, resulting in a more complicated flow state. By delaying the start of the test until the flow of these test liquids has subsided, the influence can be relatively reduced, but this increases the test time and makes it impossible to complete the test within the limited time on the production line. It is difficult to satisfy both accurate leak detection inspection and shortened inspection time. In the above inspection device, the test liquid is heated by the warmer of the rising mechanism to generate an upward flow, and this upward flow accelerates the rising speed of the bubbles so that the bubbles can rise quickly. Therefore, the influence of the irregular turbulence of the test liquid that occurs when the test object is submerged in water is suppressed, and the floating of bubbles is stabilized at an early stage, so that the test object can rise quickly. Therefore, the above inspection device suppresses the drop in inspection accuracy caused by the irregular flow of the test liquid that occurs when the test object is submerged in water, while also suppressing the air bubbles that are discharged from the test object into the test liquid after being submerged in water. can be detected quickly, reducing inspection time after submersion.

In the ultrasonic leak testing device according to another embodiment of the present invention, the warming mechanism of the rising mechanism arranged in the central region between the first peripheral wall and the second peripheral wall heats the test liquid. can generate an upward flow. The above ultrasonic leak detection device generates an upward flow in the test liquid in the central region of the test liquid, so it has the advantage of being able to accurately detect leaks by placing the test object in the center of the test liquid tank. be. In the central region between the first peripheral wall and the second peripheral wall, the influence of the test liquid on the inner surface area near the peripheral wall can be reduced. Furthermore, in the central region, the detection range of the region where the receiving beam and the transmitting beam overlap can be widened by adjusting the orientation and position of the ultrasonic transducer of the transmitting section and the ultrasonic sensor of the receiving section.

In an ultrasonic leak test device according to another embodiment of the present invention, a warmer of the rising mechanism can be placed in the test liquid. In the above ultrasonic leak testing device, since the warmer heats the test liquid, the test liquid can be efficiently heated to generate an upward flow. Therefore, it has the advantage of reducing the energy needed to heat the heater and efficiently generating upward flow.

The ultrasonic leak testing device according to another embodiment of the present invention can heat the bottom plate of the test liquid tank with the warming mechanism of the rising mechanism, and can heat the test liquid via the bottom plate. In the above-described ultrasonic leak testing device, the warmer heats the bottom plate to warm the test liquid, so the bottom plate can diffuse thermal energy and heat the test liquid over a wide area. The bottom plate, which is heated over a wide area, generates an upward flow of the test liquid over a wide area, and has the advantage of being able to detect leaks while expanding the submerged position of the test object.

In an ultrasonic leak testing device according to another embodiment of the present invention, the heater may be an electric heater. The above ultrasonic leak testing device has a simple structure and can control the power supply to the warmer to control the temperature of the warmer to an optimal value. Therefore, it has the advantage that the energy used by the warmer to cause the test liquid to flow upward can be easily set to an optimum value.

In an ultrasonic leak testing device according to another embodiment of the present invention, the transmitter divides the plurality of ultrasonic transducers into a plurality of blocks, and the ultrasonic transducers of adjacent blocks transmit ultrasonic waves of different frequencies. It can radiate sonic vibrations.

The above-described ultrasonic leak testing device has the advantage that the ultrasonic transducers of adjacent blocks emit ultrasonic vibrations of different frequencies, so that the leak position can be detected more accurately. This is because the detection zone where bubbles are rising can be identified by the frequency of the reception signal received by the ultrasonic sensor. Each ultrasonic transducer emits ultrasonic vibrations of a sharp transmission beam specified by directionality to the test liquid. Therefore, transmission beams of different frequencies are emitted from the ultrasonic transducers of each block. Transmission beams emitted in parallel from a plurality of blocks have different frequencies from adjacent transmission beams. When a bubble is generated and passes one of the transmitted beams, it is excited by the ultrasonic vibrations of the transmitted beam and emits a reflected wave. Since the reflected wave of the bubble has a frequency close to the excited ultrasonic vibration, the controller can determine which position the transmission beam has passed from the frequency of the ultrasonic reception signal received by the ultrasonic sensor. Therefore, since the controller can identify the position of the transmitted beam, that is, the position of the ultrasonic transducer, from the frequency of the reflected wave, it can reliably identify the position of the bubble.

The position of the bubble can be determined based on where the ultrasonic sensor placed receives the reflected wave from the bubble. However, bubbles excited by ultrasonic vibrations emit reflected waves to the surrounding area, and the emitted reflected waves reflect or interfere in the test liquid and are received by the ultrasonic sensor. Errors are likely to occur in detecting the position of the bubble if only the intensity of the reflected wave is used. The above-mentioned ultrasonic leak testing device determines the position by detecting the reflected waves of bubbles, but since it identifies the ultrasonic vibrator that emitted ultrasonic vibrations to the transmission beam through which the bubble passes, the bubble's position is It has the characteristic of being able to determine with extremely high accuracy.

In an ultrasonic leak testing device according to another embodiment of the present invention, the transmitter has one ultrasonic transducer arranged in each block. The above ultrasonic leak detection device has the advantage that adjacent ultrasonic transducers emit ultrasonic vibrations of different frequencies, so the detection zone can be set in a narrow area and the leak location can be determined with higher accuracy. be.
(Embodiment 1)

An ultrasonic leak testing device 100 according to Embodiment 1 of the present invention is shown in FIGS. 1 to 5. FIG. 1 is a schematic perspective view of an ultrasonic leak testing device 100, FIG. 2 is a vertical cross-sectional view of the leak testing device 100, FIG. 3 is a vertical cross-sectional view of an example in which upward flow circulates, and FIG. FIG. 5 shows a vertical cross-sectional view showing another example of the arrangement of the warmer, and FIG. 5 shows a schematic horizontal cross-sectional view of the leak testing device 100. The ultrasonic leak testing device 100 shown in these figures includes a test liquid tank 1 in which an object to be inspected W is placed and submerged in a test liquid L, and a test liquid tank 1 placed inside the test liquid tank 1 and facing the test liquid tank 1. A transmitting section 2 that emits ultrasonic vibrations toward a surface, a receiving section 3 that is placed inside the test liquid tank 1 and receives the ultrasonic vibrations that the transmitting section 2 emits, and a transmitting section 2 and a receiving section 3. and a connected controller 30. The test liquid tank 1 includes a lifting mechanism 20 that raises the test liquid L in the vertical direction and forcibly floats the bubbles B.
(Test liquid tank 1)

The test liquid tank 1 shown in FIG. 1 has a rectangular parallelepiped shape with a square upper opening, and a peripheral wall 10 is provided around a bottom plate 15. The peripheral wall 10 consists of a first peripheral wall 11 to a fourth peripheral wall 14, in which the first peripheral wall 11 and the second peripheral wall 12 are arranged at opposite positions to form opposing walls, and the third peripheral wall 13 and the fourth peripheral wall 14 are placed at opposing positions to form opposing walls. The test liquid tank 1 in FIG. 1 is an elongated rectangular parallelepiped with a rectangular upper opening. This test liquid tank 1 has a first circumferential wall 11 and a second circumferential wall 12 as side plates provided on both sides in the longitudinal direction in plan view, and a third circumferential wall 13 and a fourth circumferential wall 14 as side plates provided on both ends in the longitudinal direction. The end plate is attached to the In the test liquid tank 1, a transmitting wall 6 and a receiving wall 7 are disposed facing each other, the transmitting section 2 is disposed on the inner surface of the transmitting wall 6, and the receiving section 3 is disposed on the inner surface of the receiving wall 7. . In the illustrated test liquid tank 1, a first peripheral wall 11 is used as a transmitting wall 6 and a transmitting section 2 is arranged therein, and a second peripheral wall 12 is used as a receiving wall 7 and a receiving section 3 is arranged therein. The transmitter 2 and the receiver 3 are arranged on the inner surface of the peripheral wall 10 and below the liquid level. The transmitter 2 emits ultrasonic waves to the floating bubbles B, and the receiver 3 is arranged at a position to receive reflected waves from the bubbles B.

The test liquid tank 1 is surrounded by a first peripheral wall 11, a second peripheral wall 12, and a bottom plate 15 in the cross-sectional view of FIG. The central region 8 is located between the first peripheral wall 11 and the second peripheral wall 12, and is a region other than at least the inner surface regions 9 on both sides. The inner surface region 9 is a region including a range facing inside of the first peripheral wall 11 or the second peripheral wall 12. In the test liquid tank 1 shown in FIG. 2, the central region 8 is arranged in the middle, and the inner surface regions 9 are arranged on both sides thereof. The central region 8 in the figure is a region including the center line of the object to be inspected W disposed between the first peripheral wall 11 and the second peripheral wall 12. The central area 8 can be conveniently used as an area where the object W to be inspected is placed. The central region 8 is preferably a region that includes the width of the object W to be inspected. However, the range and width of the central region and inner surface region, and the boundaries of each region are not clearly and uniformly determined, and may vary depending on the width, shape, and size of the object to be inspected, the width of the test liquid tank, the type of lifting mechanism, etc. It is determined appropriately according to the structure, arrangement, rise of the test liquid, etc. A region that does not belong to either the central region or the inner surface region may exist between the two regions.

Although the object W to be inspected shown in the figure is placed on the bottom surface of the test liquid tank 1, the present invention is not limited thereto. Although not shown in the drawings, for example, the inspection device can place the object to be inspected at a position separated from the bottom surface of the test liquid tank. Furthermore, the inspection device can include a mechanism for submerging the object to be inspected in the test liquid. This inspection device has a mechanism for submerging the test object in the test liquid, and can place the submerged test object at a predetermined position and posture in the test liquid tank.
(Ascent mechanism 20)

The rising mechanism 20 includes a warmer 22 that heats the test liquid L to cause an upward flow. The warmer 22 is placed at a predetermined position within the test liquid tank 1, and heats the test liquid L to generate an upward flow. In the ultrasonic leak testing device 100 shown in FIG. 2, the object W to be tested is placed in the central region 8. In this ultrasonic leak testing device 100, the warmer 22 of the rising mechanism 20 generates an upward flow in the test liquid L in the central region 8, accelerates and floats the bubbles B, and removes the bubbles caused by leakage. B is detected to accurately identify the presence or absence of leakage in the object W to be inspected and the location of the leakage. The bubbles B leaking out from minute gaps such as pinholes and cracks in the inspected object W become finer in particle size as the gap becomes smaller. In the test liquid tank 1, there are bubbles B with a large particle size that leak out from gaps in the object W to be inspected and float smoothly upwards, and bubbles B with a small particle size and a slow floating speed. The fine bubbles B having a slow floating speed are affected by local fluctuations in the test liquid L, and have a high probability of moving to the adjacent detection zone.

The warmer 22 of the rising mechanism 20 makes the test liquid L in the central region 8 where the test object W is placed an upward flow, accelerates and forcibly floats the bubbles B having small particle diameters. The warmer 22 of the rising mechanism 20 accelerates the rising speed of the bubbles B with the rising flow of the central region 8, thereby improving the detection accuracy using the Doppler effect for detecting the frequency shift of the reflected wave of the bubbles. By suppressing the movement of the fine bubbles B to the adjacent detection zone, it is possible to improve the accuracy of the detection position of fine bubbles. The ultrasonic leak testing device 100 equipped with the warmer 22 of the rising mechanism 20 accelerates particularly fine air bubbles B with the rising flow of the test liquid L and forcibly moves them upward to the adjacent detection zone. By suppressing misalignment, minute cracks, pinholes, etc. in the inspected object W can be accurately detected without misalignment.

The warmer 22 of the rising mechanism 20 causes the test liquid L in at least the region where the object W to be inspected to be arranged to rise, accelerates the floating of the bubbles, and forcibly floats the bubbles. The warmer 22 of the rising mechanism 20 in FIG. 2 causes the test liquid L in at least a part of the central region 8 to flow upward. The upward flow in the central region 8 is set within an appropriate range depending on the size and shape of the object W to be inspected, the distance to the peripheral walls 10 on both sides, and the like. The upward flow traces the surface of the object W to be inspected and the test liquid L rises, thereby covering the three-dimensional range of the object W to be inspected. By making the range in which the upward flow occurs wider than the width of the object W to be inspected, the three-dimensional range of the object W to be inspected can be covered with sufficient margin. The range heated by the heater 22 can be limited to the central region 8 or a part thereof. By narrowing the range heated by the warmer 22, the size and number of the warmers 22 can be reduced, and the cost of the warmer can be reduced. Although not shown, the raising mechanism can raise the test liquid in a wider range than the central region, that is, in regions other than the central region. For example, it is possible to raise the temperature of the test liquid by heating the entire bottom plate of the test liquid tank and by heating the test liquid in the lower layer of the test liquid tank below the object to be tested in a wider range than the central area. can. By widening the range heated by the warmer 22, it is possible to widen the range that the inspection apparatus can handle, such as the shape and size of the object to be inspected.

The rising mechanism 20 shown in FIGS. 1 and 2 warms the test liquid L with a warmer 22 to generate an upward flow. The warmer 22 is a device that directly or indirectly heats the test liquid L. An electric heater is suitable for the warmer 22 of the lifting mechanism 20. Electric heaters are convenient to use because they are easy to adjust and control the temperature, and can generate an upward flow of a predetermined test liquid at a predetermined location. However, the heater is not limited to electric heaters, and can be used without any restrictions as long as it can heat the test liquid and generate an upward flow, so the structure, configuration, and mode of the warmer are Not limited. As the warmer, products currently on the market, such as steam heaters that circulate heating steam internally for heating, can be used, and also include warmers that will be developed in the future.

In the ultrasonic leak testing device 100 shown in FIG. 2, the test liquid L is heated through the bottom plate 15 by the warmer 22 of the lifting mechanism 20. This warmer 22 heats the bottom plate 15 in the central region of the test liquid tank 15 to generate an upward flow. The heated test liquid L expands, becomes less dense, and flows upward. In FIG. 2, the test liquid L heated by the bottom plate 15 flows upward in the central region 8 as indicated by an arrow B, accelerating the bubbles B and forcing them to float.

The warmer 22 heats the test liquid L through the bottom plate 15, as shown in FIGS. 2 and 3, or is arranged inside the bottom plate 15 and directly heats the test liquid L, as shown in FIG. The test liquid L near the object W to be inspected is heated to an upward flow, and the bubbles B are quickly floated. The warmer 22 is provided according to the shape and arrangement of the object to be inspected, and in addition to the heating temperature, the shape of the warmer 22, heating area, arrangement, mode of contact with the test liquid, distance from the object to be inspected, Depending on the heating mode such as the heating method, the range of the test liquid to be heated, the range in which the test liquid is raised, the position, and the rate of rise can be regulated. By defining the range, area, etc. of the test liquid L to be heated by the warmer 22, a predetermined rise can be caused in a specific position and range within the test liquid tank 1. Therefore, the warmer 22 covers the range in the central region 8 where the bubbles B can be generated from the gaps in the object W to be inspected, and the range where the generated bubbles B can exist to cause the test liquid L to flow upward. Can be done.

Further, as shown in FIG. 3, the test liquid L flowing upward in the central region 8 becomes a downward flow in the inner surface region 9 of the test liquid tank 1 and convects up and down. The warmed test liquid L rises in the central region 8, is cooled by the peripheral wall 10 of the test liquid tank 1 in the inner surface region 9, and flows downward. In the test liquid tank 1, the test liquid L heated by the warmer 22 flows upward, floats near the liquid surface, and spreads in the width direction. In the cross-sectional view of FIG. 3, the test liquid L moves toward the first peripheral wall 11 and the second peripheral wall 12 on both the left and right sides, and further moves toward the inner surface of each of the first and second peripheral walls 11 and 12. The test liquid L that descends in the region 9 and settles near the bottom moves to the central region 8, where it is heated by the warmer 22 again and rises. As shown by the arrow in the figure, an upward flow of the test liquid L occurs in the test liquid tank 1, and this upward flow has an axis of symmetry about the center line passing through the center between the first and second peripheral walls 11 and 12. The test liquid L convects in the test liquid tank 1 in a loop shape with the upward flow in the central region 8 and the downward flow in the inner surface region 9 in a line-symmetrical manner, and the upward flow accelerates the floating bubbles and forces them to rise. be able to.

The warmer 22 can generate an upward flow in a predetermined position and range by having a vertically long rectangular shape or a linear shape, or by arranging the warmers 22 in a vertically long rectangular shape or a linear shape. Since the inspection apparatus shown in FIG. 2 inspects for leaks by disposing the inspected object W in the central region 8 of the bottom surface of the test liquid tank 1, the warmer 22 is disposed below the inspected object W. In the illustrated inspection apparatus, a warmer 22 is disposed on the outer surface of a bottom plate 15 of a test liquid tank 1, and the test liquid L in the lower layer near the object W to be inspected is heated via the bottom plate 15. A warmer 22 is provided in the central region 8, and the test liquid L heated in the central region 8 becomes an upward flow, accelerating the floating bubbles and causing them to rise.

The warmer 22, which is an electric heater, can control the upward flow of the test liquid L by controlling the power supply and controlling the amount of heat generated. The warming device 22, which is an electric heater, can improve the accuracy of bubble inspection by setting the rising speed of the upward flow so that fine bubbles B can be detected. The heater 22 controls the temperature to a set temperature and controls the upward flow, accelerates the fine bubbles B to float, suppresses their movement to the adjacent detection zone, and removes the air from the floating bubbles. It is possible to detect leakage of the test object W and to accurately detect the position of the leakage based on the position of the floating bubbles. The warmer 22, which is an electric heater, can stably generate an upward flow by maintaining a set temperature using a thermostat or the like. The temperature setting of the warmer 22 is optimal depending on the overall temperature of the test liquid, the temperature difference from the heated test liquid, the type and amount of the test liquid, the water tank capacity, the thickness and material of the bottom plate, the test time, etc. is adjusted to the set value. In order to heat and raise the temperature of the test liquid L, a temperature difference between the test liquid L and the surrounding test liquid L is required. For example, if the heating time is long, consider that the temperature of the test liquid L in the test liquid tank 1 will gradually rise as the test liquid L is heated by the warmer 22 and the rising temperature circulates. , the temperature of the test liquid L, especially the temperature of the test liquid L in the lower part of the central region 8, and temperature changes are determined, or control is performed to increase the set temperature in response to temperature changes. do.

It is preferable that the warmer 22 be placed at a position where the air bubbles B coming out of the object W to be inspected can be forcibly floated. The bubbles B ejected from the pinhole are heated by the test liquid L and expand. The expanded bubble B has increased buoyancy and its floating speed increases. This is combined with the fact that the upward flow of the test liquid L increases the floating speed, and the floating speed of the bubbles B can be further increased. In particular, when the pressurized air that has been injected into the test object W is ejected from a pinhole or the like, the air bubbles B expand adiabatically and the temperature decreases, but the ejected air bubbles B are heated by the test liquid L. It expands and becomes larger, increasing its buoyancy. Therefore, even if the temperature of the bubbles B ejected from the object W to be inspected decreases due to adiabatic expansion, the bubbles B are heated by the heated test liquid L, and the floating speed is prevented from decreasing. Therefore, the bubbles B ejected from the object W to be inspected are heated by the convecting test liquid L and the floating speed does not decrease, and the bubbles B are quickly floated and detected.

Since the warmer 22 in FIG. 2 is provided outside the bottom plate 15 of the test liquid tank 1 and warms the test liquid L, the warmer 22 can be easily installed, replaced, and maintained. The warmer 22 in FIG. 4 is provided under the test object W and inside the bottom plate 15 of the test liquid tank 1, and directly heats the test liquid L. The electric heater warmer 22 provided in the test liquid L can be placed in the test liquid as a waterproof structure. The warmer 22 placed in the liquid can efficiently heat the liquid it comes into direct contact with, and can more finely control the temperature of the heated liquid. However, although not shown, the warmer 22 can also be placed at a position where it can generate an upward flow that can float air bubbles discharged from the object to be inspected, for example, on both sides or one side of the object to be inspected, or above the object to be inspected. You can also combine them. One or more warmers 22 can be provided. When placing a warmer above the test object, the test liquid that is heated and raised will forcibly pull up the test liquid below the warmer, so the test object should be placed in an area of upward flow. can force the bubbles to rise.

It is preferable that the warmer 22 is provided under the test object W, but it is possible to forcibly float the air bubbles B discharged from the test object W with the upward flow generated by heating the test liquid L. It can be placed in any position. Therefore, it is preferable that the warmer 22 be placed near the object W to be inspected. This is because the warmer 22 placed near the object W to be inspected warms the test liquid L near the object W to be inspected, so that the bubbles B discharged from the object W to be inspected can float up in an upward flow. . The warmer is preferably placed below the object to be inspected, but the warmer can also be placed above the object to be inspected. This heater generates an upward flow of the heated test liquid, and this upward flow pulls up the test liquid below the warmer, forcing air bubbles discharged from the test object to the surface. be.

The warmer 22 warms the test liquid L, raises the test liquid L, and quickly floats the bubbles B, so that the test liquid L around the bubbles B is not stirred. The test liquid L can rise together with the bubbles B. Therefore, the bubble B can be raised quickly without changing the acoustic impedance of the bubble, that is, without changing the physical properties of the bubble against ultrasonic vibration, so that the bubble B can be reliably detected by ultrasonic vibration. , its detection position can also be determined accurately.

Also, although not shown, the connecting portion between the inner peripheral wall of the test liquid tank and the bottom plate may be formed into a gently curved surface, so that the test liquid can flow smoothly without interfering with its approximately circular upward movement. Similarly, a guide portion or the like may be provided near the liquid level inside the peripheral wall to smoothly guide the rise. Furthermore, a partition plate for defining the range of the upward flow, a guide for guiding the upward flow, etc. may be provided.

The lifting mechanism 20 that heats the test liquid L with the warmer 22 in FIGS. 2 and 3 above raises the test liquid L in the test liquid tank 1 upward in the central region 8, so that the rising speed is low. Air bubbles, air bubbles with a fine particle size that hardly float up on their own, air bubbles that are affected by local fluctuations in the test liquid L, etc. are forced to rise, and the air bubbles move outside the detection range, such as into the adjacent detection zone. can be suppressed. Therefore, the ultrasonic leak testing device 100 that heats the test liquid L in the central region 8 with the warmer 22 and causes the bubbles B to float as an upward flow can locate the bubbles B floating inside the test liquid tank 1. It is possible to accurately identify the leakage position of the object W to be inspected.
(Transmission section 2)

The transmitter 2 has a plurality of ultrasonic transducers 4 arranged side by side in the horizontal direction at predetermined intervals. Each ultrasonic transducer 4 emits ultrasonic vibrations in the direction shown by arrow A in FIG. The ultrasonic waves emitted from the ultrasonic transducer 4 travel straight through the test liquid L. The ultrasonic vibrator 4 emits ultrasonic vibrations in a beam specified by directionality. FIG. 6 shows a transmission beam from which the ultrasonic transducer 4 emits ultrasonic vibrations. As shown in this figure, the ultrasonic transducer 4 radiates ultrasonic vibrations most strongly to the central axis 4x of the transmission beam, and also radiates ultrasonic vibrations around the center axis 4x. The radiation angle of the transmitted beam is specified by the directivity of the ultrasonic transducer 4. The directivity of the ultrasonic transducer 4 can be adjusted by adjusting the frequency, the shape of the horn, etc., but generally the half-value angle (θ) of the transmitted beam is about 8 to 30 degrees. The half-power angle (θ) is the angle at which the intensity of ultrasonic vibration is halved, and is one of the indicators representing directivity. The half-value angle (θ) is an angle at which the signal level decreases to 1/2 of the central axis 4x when the intensity of ultrasonic vibration is measured by shifting the angle. Therefore, the ultrasonic transducer 4 can increase the intensity of ultrasonic vibration inside the half-power angle (θ) to 1/2 or more of the transmission beam center axis 4x.

The ultrasonic transducer 4 can reduce the half-value angle (θ) of the transmitted beam, that is, narrowly converge the ultrasonic vibrations and radiate them with high intensity over a long distance. The ultrasonic transducer 4 with a small half-value angle (θ) can generate stronger ultrasonic vibrations at a distant position, so that air bubbles at a position distant from the ultrasonic transducer 4 can be detected. However, since the ultrasonic transducer 4 with a narrow half-value angle (θ) emits ultrasonic vibrations in a specific narrow area, the detection range in which bubbles can be detected becomes narrow.

The transmitting unit 2 arranges a plurality of ultrasonic transducers 4 side by side in a horizontal direction at predetermined intervals in a posture parallel to the radiation direction of the ultrasonic waves, that is, the center axis 4x of the transmission beam, to form a plurality of rows of ultrasonic transducers 4. Emits a transmit beam. The transmitting unit 2 emits ultrasonic waves using a plurality of ultrasonic transducers 4, and emits a plurality of rows of transmission beams in parallel in a horizontal plane, thereby generating ultrasonic waves for detecting air bubbles B floating in the test liquid L. constitutes a radiation surface. The intervals between the ultrasonic transducers 4 are set to such an interval that the ultrasonic waves are emitted almost uniformly onto the ultrasonic emission surface. If the interval between the ultrasonic transducers 4 is too wide, the ultrasonic vibration between the ultrasonic transducers 4 will become weak, making it impossible to reliably detect the bubbles B floating in this area. By narrowing the interval between the ultrasonic transducers 4, the entire ultrasonic radiation surface can be vibrated with sufficient intensity of ultrasonic waves, but the increased number of ultrasonic transducers 4 increases component costs. Therefore, the intervals between the ultrasonic transducers 4 are set to be wider than 1 cm and larger than 5 cm so as to reduce the number of ultrasonic transducers 4 as much as possible while making the ultrasonic radiation surface almost uniformly vibrate. Make it narrower.

Since the angle at which the ultrasonic transducer 4 emits ultrasonic vibrations is specified by the half-value angle (θ) of the transmission beam, the plurality of ultrasonic transducers 4 arranged in the transmitter 2 (θ), the interval between adjacent ultrasonic transducers 4 is adjusted to the optimum value, the ultrasonic transducers 4 with a large half-power angle (θ) have a wide interval, and the ultrasonic transducers 4 with a small half-power angle (θ) have a large interval. Reduce the spacing. For this reason, the interval between the ultrasonic transducers 4 is not specified within the above-mentioned range, but is set to an optimum value in consideration of the characteristics of the ultrasonic transducer 4, the accuracy of the inspection, and the like.

As shown in FIG. 7, the transmitter 2 divides a plurality of ultrasonic transducers 4 into a plurality of blocks 2X, and the ultrasonic transducers 4 of adjacent blocks 2X emit ultrasonic vibrations of different frequencies. . The transmitter 2 preferably arranges one ultrasonic transducer 4 in each block 2X, that is, one ultrasonic transducer 4 constitutes one block 2X, and the adjacent ultrasonic transducer 4 emits ultrasonic vibrations of different frequencies. This leakage testing device 100 emits a plurality of rows of transmission beams with different frequencies on the ultrasonic emission surface, narrows the pitch of the transmission beams with different frequencies, and can specify the position of the bubble B with higher resolution. However, as shown in FIG. 8, the transmitter 2 can also arrange a plurality of ultrasonic transducers 4 in each block 2X, and configure one block 2X with the plurality of ultrasonic transducers 4.

By increasing the frequency difference emitted by adjacent blocks 2X, it is possible to reliably identify from which ultrasonic transducer 4 the ultrasonic wave was received, but if the ultrasonic transducer 4 deviates from its resonant frequency, it will emit ultrasonic waves. Therefore, the frequency difference between the ultrasonic vibrations emitted by adjacent blocks 2X is preferably 10% or less of the resonant frequency of the ultrasonic transducer 4. Since the ultrasonic vibrator 4 emits an ultrasonic vibration with a frequency of preferably 1 MHz to 3 MHz, for example, 1 MHz or 2 MHz, the frequency difference between the ultrasonic vibrations emitted by the block 2X is greater than 30 Hz, for example. The range shall be smaller than 200kHz. This leakage testing device 100 uses ultrasonic transducers 4 having the same resonant frequency in all transmitting units 2, and allows the frequencies of the ultrasonic transducers 4 in adjacent blocks 2X to be set to different frequencies.

For example, the transmitter 2 sets the frequency of the ultrasonic vibrations emitted by the ultrasonic transducers 4 of the adjacent blocks 2X to frequencies that alternately become higher and lower in the arrangement direction of the blocks 2X, thereby increasing the overall frequency. The ultrasonic transducer 4 of the adjacent block 2X can emit ultrasonic waves of different frequencies while narrowing the frequency range. For example, as shown in FIG. 7, 15 ultrasonic transducers 4 with a resonant frequency of 2 MHz are arranged side by side, and ultrasonic vibrations of the following frequencies are emitted so that adjacent ultrasonic transducers 4 It can emit ultrasound waves of different frequencies.

Frequency of ultrasonic vibration emitted by the first ultrasonic transducer...2015kHz
(Frequency difference 70Hz decrease)
Frequency of ultrasonic vibration emitted by the second ultrasonic vibrator...1945kHz
(Frequency difference 75Hz increase)
The frequency of ultrasonic vibration emitted by the third ultrasonic transducer...2020kHz
(Frequency difference 70Hz decrease)
The frequency of ultrasonic vibration emitted by the fourth ultrasonic transducer...1950kHz
(Frequency difference 75Hz increase)
Frequency of ultrasonic vibration emitted by the fifth ultrasonic transducer...2025kHz
(Frequency difference 70Hz decrease)
The frequency of ultrasonic vibration emitted by the sixth ultrasonic transducer...1955kHz
(Frequency difference 75Hz increase)
The frequency of ultrasonic vibration emitted by the seventh ultrasonic transducer...2030kHz
(Frequency difference 70Hz decrease)
Frequency of ultrasonic vibration emitted by the 8th ultrasonic transducer...1960kHz
(Frequency difference 75Hz increase)
The frequency of ultrasonic vibration emitted by the 9th ultrasonic transducer...2035kHz
(Frequency difference 70Hz decrease)
Frequency of ultrasonic vibration emitted by the 10th ultrasonic transducer...1965kHz
(Frequency difference 75Hz increase)
Frequency of ultrasonic vibration emitted by the 11th ultrasonic transducer...2040kHz
(Frequency difference 70Hz decrease)
Frequency of ultrasonic vibration emitted by the 12th ultrasonic transducer...1970kHz
(Frequency difference 75Hz increase)
The frequency of ultrasonic vibration emitted by the 13th ultrasonic transducer...2045kHz
(Frequency difference 70Hz)
Frequency of ultrasonic vibration emitted by the 14th ultrasonic transducer...1975kHz
(Frequency difference 75Hz increase)
Frequency of ultrasonic vibration emitted by the 15th ultrasonic transducer...2050kHz

The transmitter 2 sets the frequency of the ultrasonic vibration of each block 2X to a higher value than the frequency difference with the adjacent block 2X to 70 Hz or 75 Hz, and determines which block 2X the bubble B is excited by the ultrasonic vibration of. The position of the bubble B can be accurately determined by accurately determining whether the bubble B is large or not. In addition, the above transmitter 2 alternately increases and decreases the frequency of the ultrasonic waves emitted by the ultrasonic transducers 4 of the blocks 2X in the arrangement direction of the blocks 2X, and transmits the waves from the odd-numbered blocks 2X to the even-numbered blocks 2X. By lowering the frequency for block 2X and increasing the frequency from even-numbered blocks 2X to odd-numbered blocks 2X, increasing the ultrasonic vibration difference between adjacent blocks 2X to 70Hz or 75Hz, the overall The frequency width is set from the lowest frequency of 1945 kHz to the highest frequency of 2050 kHz, and is set within a range of -2.75% to +2.5%, which is less than 10% of the resonance frequency of 2 MHz.

Furthermore, as described above, the leakage inspection device 100 in which the transmitting section 2 sets the frequencies of the radiated ultrasonic waves of the ultrasonic transducers 4 of all the blocks 2X to different frequencies, transmits a beam at the frequency that the receiving section 3 receives. It has the feature that the position of the bubble B can be detected accurately by specifying the bubble B. Another feature is that by setting the frequency of the ultrasonic transducer 4 of each block 2X to a frequency that is not a harmonic of a specific frequency, the transmission beam can be determined without error based on the frequency received by the receiver 3.
(Receiving section 3)

The receiving unit 3 has a plurality of ultrasonic sensors 5 arranged side by side in the horizontal direction. The reception sensitivity of the ultrasonic sensor 5 changes depending on the incident angle of the ultrasonic vibration, and the sensitivity of the ultrasonic vibration incident from the direction of the central axis 5x of the reception beam is maximum. The transmitter 2 has a plurality of ultrasonic transducers 4 arranged side by side in the horizontal direction. The ultrasonic transducer 4 emits ultrasonic vibrations most strongly in the direction of the central axis 4x of the transmission beam. As shown in the schematic horizontal cross-sectional view of FIG. 5, the ultrasonic sensor 5 and the ultrasonic transducer 4 are arranged at opposing positions in a horizontal plane, and are excited by the ultrasonic vibrations of the ultrasonic transducer 4 located at the opposing position. The reflected wave from the bubble B is received by the ultrasonic sensor 5. The leak testing device 100 having this structure receives ultrasonic vibrations from the ultrasonic transducer 4 located at the opposing position with the ultrasonic sensor 5 located at the opposing position, so it floats between the ultrasonic transducer 4 located at the opposing position. The ultrasonic sensor 5 can receive the reflected waves from the bubbles B with high sensitivity.

In the ultrasonic leak testing device 100, lowering the receiving level of direct waves and increasing the receiving level of reflected waves is effective in detecting minute bubbles. This is because the ultrasonic sensor 5 can receive low-level reflected waves with high reception sensitivity. The leak inspection device 100 can detect bubbles B by detecting both direct waves and reflected waves, or can detect bubbles B by detecting changes in the frequency of reflected waves due to the Doppler effect. In a device that detects both waves, since the direct wave has a high signal level, the ultrasonic sensor 5 is placed at a position offset from the center axis 5x of the receiving beam, and the direct wave signal detected by the ultrasonic sensor 5 is Even if the level is low, direct waves can be received at a sufficient signal level. Since the signal level of the reflected wave is lower than that of the direct wave, how highly sensitive it can be detected is extremely important in detecting minute bubbles in any type of leak testing device.

For this reason, it is extremely important for a leak testing device to reliably and stably detect reflected waves with weak signal levels. However, since the signal level of the ultrasonic waves reflected by minute bubbles is extremely low, the ultrasonic sensor 5 is required to have high sensitivity and low noise characteristics to stably receive low-level reflected waves with extremely high sensitivity. The ultrasonic sensor 5 detects low-level reflected waves, but the ultrasonic sensor 5 also detects not only the reflected waves but also the direct waves that the ultrasonic vibrator 4 emits to the test liquid L. Since the direct wave has a higher signal level than the reflected wave, it can be detected by the low-sensitivity ultrasonic sensor 5, but the low-sensitivity ultrasonic sensor 5 cannot reliably and stably detect the low-level reflected wave. Furthermore, although the frequency of the reflected wave differs from that of the direct wave, the ratio is extremely small, and the difference in frequency between the reflected wave and the direct wave is extremely small. In order to reliably detect reflected waves with similar frequencies and extremely low signal levels, the low-level reflected waves are efficiently received by the ultrasonic sensor 5, and in order to lower the signal level of the high-level direct waves. , the ultrasonic sensor 5 is arranged at a position where it does not receive direct waves from the ultrasonic transducer 4.

In order to realize this, the ultrasonic leak testing device 100 shown in FIG. The ultrasonic sensor 5 is arranged at a position offset from the central axis 4x of ultrasonic vibration. This is because when the ultrasonic sensor 5 is placed on the central axis 4x from which ultrasonic vibrations are radiated, direct waves, which are ultrasonic vibrations that are not reflected by the bubbles B, are incident on the ultrasonic sensor 5. The ultrasonic sensor 5 which is not disposed on the central axis 4x of ultrasonic radiation has a lower direct wave input level and can receive reflected waves with high sensitivity.

The receiver 3 detects the bubbles B by detecting low-level reflected waves, but the signal level of the reflected waves from the minute bubbles B is extremely low. The receiving unit 3 that detects low-level reflected waves can stably detect minute bubbles B by lowering the noise level and stably detecting low-level reflected waves with a high S/N ratio. Affects detection ability. The leak testing device 100 emits ultrasonic vibrations into the test liquid L. The ultrasonic vibrations emitted into the test liquid L collide with all surfaces, are reflected, and are diffused, and are transmitted from the ultrasonic vibrator 4 to the ultrasonic sensor. The ultrasonic waves whose distances to the ultrasonic sensor 5 are changed and whose phases are shifted interfere with each other and become noise components that are received by the ultrasonic sensor 5. The noise component lowers the S/N ratio of the receiving section 3 that receives the reflected waves with high sensitivity, and becomes a cause of increasing the minimum level of the reflected waves that can be substantially received. The lowest level of reflected waves that can be received by the receiver 3 influences the size of the bubbles B that can be detected. Therefore, in order to detect finer bubbles B, it is important to lower the noise component detected by the ultrasonic sensor 5 and to stably and reliably receive lower level reflected waves.

The receiving unit 3 is arranged at a position and posture to receive the reflected waves of the bubbles B floating in the test liquid L with high sensitivity. The receiving unit 3 includes a plurality of ultrasonic sensors 5, and the ultrasonic sensors 5 are arranged horizontally at predetermined intervals. The receiving section 3 has a plurality of ultrasonic sensors 5, and the transmitting section 2 has a plurality of ultrasonic transducers 4 arranged horizontally. The receiving section 3 has a plurality of ultrasonic sensors 5 arranged horizontally, but the number of ultrasonic transducers 4 of the transmitting section 2 and the ultrasonic sensors 5 of the receiving section 3 are the same, in a horizontal plane, i.e. In plan view, the ultrasonic sensors 5 are arranged at positions facing the ultrasonic transducers 4, and each ultrasonic sensor 5 receives ultrasonic vibrations from the ultrasonic transducers 4 located at the facing positions, that is, at the facing positions. The direct wave from the ultrasonic transducer 4 and the reflected wave from the bubbles B are received.

The ultrasonic sensor 5 also has sharp directivity like the ultrasonic transducer 4, and can further increase the reception sensitivity by narrowing the half-value angle (θ) of the reception beam. Since the ultrasonic sensor 5 with high reception sensitivity can receive weak reflected waves from the bubble B, the ultrasonic sensor 5 has a narrow half-value angle (θ) of the reception beam, for example, 8 degrees to 30 degrees. The half-value angle (θ) of the ultrasonic sensor 5 can be adjusted by adjusting the frequency of the ultrasonic vibration to be received and the horn. The ultrasonic sensor 5 can receive the reflected wave from the bubble B located inside the half-value angle (θ) at a signal level of 1/2 or more with respect to the central axis 4x of the transmission beam.

In order to lower the signal level of the direct wave from the ultrasonic transducer 4, the receiving unit 3 arranges the ultrasonic sensor 5 at a position offset from the central axis 4x of the transmission beam. Since the direct wave has a higher signal level than the reflected wave from the bubble B, it is possible to receive the direct wave from the ultrasonic transducer 4 at a sufficient signal level by placing it at a position away from the central axis 4x of the transmission beam. The closer the ultrasonic sensor 5 is placed to the central axis 4x of the transmission beam, the higher the signal level of the direct wave becomes, and the further away from the central axis 4x of the transmission beam, the lower the signal level of the direct wave. The position of the ultrasonic sensor 5 on the reception wall 7, that is, the displacement interval (d) between the center of the ultrasonic sensor 5 and the central axis 4x of the transmission beam, is determined by the half-value angle (θ) between the transmission beam and the reception beam. It is set to an optimum value taking into consideration, but preferably it is set to 5 mm or more and 50 mm or less. The ultrasonic sensor 5 whose receiving beam has a wide half-value angle (θ) can increase the displacement interval (d) and widen the detection range of the bubbles B floating in the test liquid tank 1 in the horizontal plane.

FIG. 2 shows the range in which the ultrasonic sensor 5 detects bubbles B floating in the test liquid tank 1. In this receiving section 3, the position of the ultrasonic sensor 5 is arranged within a range of a half-power angle (θ) from the central axis 4x of the transmission beam. This ultrasonic sensor 5 can receive the signal level of the direct wave at a signal level that is 1/2 or more with respect to the central axis 4x of the transmission beam. A leakage inspection device that places the ultrasonic sensor 5 inside the half-power angle (θ) of the transmitted beam can increase the signal level of the direct wave, so it uses both the direct wave and the reflected wave to detect the bubble B. It is suitable for methods that The leak test device can also detect bubbles B by detecting changes in the frequency of reflected waves due to the Doppler effect, so this leak test device does not need to detect direct waves at a high signal level. The position of the ultrasonic sensor 5 can also be placed outside the half-power angle (θ) of the transmitted beam. In a leakage inspection device that detects bubble B from the Doppler effect of the reflected wave, the signal level of the reflected wave from bubble B can be adjusted by locating the ultrasonic sensor 5 inside the half-value angle (θ) of the transmitted beam. Can be made high. This is because the bubble B located inside the half-power angle (θ) of the transmission beam has a strong ultrasonic vibration emitted from the ultrasonic transducer 4, so the reflected wave from the bubble B also becomes strong. Therefore, the ultrasonic sensor 5 is preferably placed inside the half-power angle (θ) of the transmitted beam.

In the leakage testing device 100 shown in FIG. 2, the ultrasonic sensor 5 is arranged in a position where the central axis 5x of the receiving beam and the central axis 4x of the transmitting beam intersect in the test liquid tank 1. In the leakage testing device 100 shown in this figure, the ultrasonic sensor 5 is arranged in a position where the central axis 5x of the receiving beam intersects the central axis 4x of the transmitting beam at the center. The ultrasonic sensor 5 arranged in this posture can spread the bubble B over a wide area with the detection range extending on both sides of the receiving beam. Preferably, the intersection X of the receiving beam and the transmitting beam in the test liquid tank 1 is located at a position displaced toward the receiving wall 7 from the center of the central axis 4x of the transmitting beam. This is because the receiving beam gradually spreads from the transmitting wall 6 toward the receiving wall 7, and the area within the half-power angle becomes wider on the receiving wall 7 side than in the center.

In the leakage testing device 100 shown in FIG. 2, in the region where the transmitting beam and the receiving beam overlap (the region marked with light ink in the figure), the bubble B exceeds the intensity of 1/2 or more of the central axis 4x of the transmitting beam. It is excited by acoustic vibration and can receive reflected waves at a signal level of 1/2 or more of the central axis 5x of the receiving beam. Therefore, the bubble B floating in the area where the transmitting beam and the receiving beam intersect is excited with a sufficient ultrasonic vibration level, and the reflected wave emitted by the bubble B is received by the ultrasonic sensor 5 with a sufficient signal level. . The energy with which the bubble B is excited by ultrasonic vibration decreases as it moves away from the ultrasonic vibrator 4, but the reflected wave from the bubble B becomes stronger as it approaches the ultrasonic sensor 5. can receive the reflected wave from the bubble B floating in the area where the transmit beam and the receive beam overlap at a sufficient signal level. Bubbles B floating in the area away from the ultrasonic transducer 4 and approaching the ultrasonic sensor 5 reduce the energy of the ultrasonic vibration, but the reception sensitivity of the ultrasonic sensor 5 increases, and the bubble B moves away from the ultrasonic sensor 5. Bubbles B floating in the area approaching the ultrasonic transducer 4 will reduce the reception sensitivity of the ultrasonic sensor 5, but the energy of the excited ultrasonic vibration will become stronger and the reflected wave of the bubble B will become stronger. , the ultrasonic sensor 5 can receive reflected waves at a sufficient signal level.

The leakage testing device 100 described above is used in the following conditions to detect leakage from an object to be tested. The object W to be inspected is submerged in the test liquid L filled in the test liquid tank 1. The object to be inspected W is submerged in water to a position lower than the horizontal plane on which the transmitting section 2 and the receiving section 3 are arranged, so that the reflected wave of the floating bubble B can be received by the receiving section 3. Air bubbles B leaking from W are made to pass between the transmitting section 2 and the receiving section 3.

Further, the transmitter 2 and the receiver 3 are connected to the controller 30. The controller 30 includes a bubble detection section (not shown) that detects the presence or absence of bubbles B by detecting the ultrasonic waves received by the reception section 3. The controller 30 can be an external device such as an external computer, but by incorporating the controller 30 into the ultrasonic leak testing device 100 itself, it is possible to detect air bubbles, their positions, and amounts without adding any external devices. detection can be realized. The controller 30 includes a display section (not shown) that detects and displays the floating bubble B from the direct wave and reflected wave detected by the receiving section 3, or from the frequency change of the reflected wave. The display section can be a CRT, a liquid crystal panel, or the like. Further, input devices such as an operation panel, a console, and a keyboard for operating members such as a controller are provided as necessary.

Furthermore, the test liquid tank 1 is provided with an air pipe 31 for supplying compressed air to the inside of the test object W submerged in the test liquid L. Thereby, compressed air is sent to the object W to be inspected, and when a small hole or a crack exists in the object W to be inspected, air bubbles B are caused to leak from the small hole, crack, or gap. The bubbles B rise in the test liquid L in the test liquid tank 1, reach the liquid level of the test liquid L, and are destroyed. The ultrasonic vibrations emitted from the ultrasonic transducer 4 excites the bubbles B and emit reflected waves. The receiving unit 3 receives the reflected wave from the bubble B and the direct wave from the ultrasonic transducer 4 . The controller 30 detects the bubble B using both the reflected wave and the direct wave, or the reflected wave, and determines airtight leakage. Furthermore, the controller 30 also detects the position and amount of bubbles B generated.

The plurality of ultrasonic transducers 4 arranged side by side next to each other emit ultrasonic waves of different frequencies, and the plurality of ultrasonic transducers 4 and the ultrasonic sensor 5 located at the opposing position are paired to generate direct waves. and detect reflected waves.

The object to be inspected W is a member whose airtightness, cracks, and occurrence of small holes are to be detected, and any member that can be submerged in the test liquid L is targeted. For example, fuel tanks, vehicle catalytic converters, mufflers, etc. In addition, the test liquid L is selected from a liquid that does not cause damage such as corrosion to the test object W, or has a small effect on the test object W, such as water. It is preferable to use an aqueous solution of a rust preventive agent as the test liquid L, and the viscosity and temperature are adjusted as necessary in consideration of bubble flow and ultrasonic propagation.

The ultrasonic transducer 4 transmits ultrasonic waves on the order of MHz. In consideration of attenuation in the test liquid L, ultrasonic waves of preferably 1 MHz or more and 20 MHz or less, more preferably 1 MHz to 5 MHz, are used, and 1 MHz to 2 MHz is preferable from the viewpoint of ease of signal processing circuit. Since 90% or more of the ultrasonic wave is reflected when it hits the bubble B, the ultrasonic sensor 5 can detect the reflected wave. In addition, when the bubble B rises in the test liquid L, it is blocked by the test liquid L and floats with oscillations such as spiral movement, pendulum movement, and changes in surface shape, so that ultrasonic waves on the order of MHz are generated. When radiated from the horizontal direction, the reflected wave causes a frequency shift due to vibration. Frequency deviation is the amount of change in frequency, in other words, the amount of change in vibration frequency, and is usually expressed in Hertz (Hz). Furthermore, since the ultrasonic waves are diffracted and superimposed, they can also be observed behind the bubble. In this way, the amount of frequency shift of the direct wave and the reflected wave differs depending on the vibration of the bubble. Therefore, by detecting these, air bubbles can be detected, and the airtightness, leakage amount, etc. of the object W to be inspected can be detected.

In the leak testing device 100, in which a transmitting section 2 and a receiving section 3 are disposed at opposite positions of a test liquid tank 1, the transmitting section 2 emits ultrasonic waves toward the receiving section 3, and converts direct waves and reflected waves into ultrasonic waves. Received by sensor 5. Since direct waves and reflected waves have different properties, a leak test device that detects them using both can prevent false detection and accurately identify the properties of bubbles. In general, direct waves are suitable for detecting large amounts of bubbles, while reflected waves are suitable for detecting small amounts of bubbles. In addition, when there are multiple small bubbles, the reflected wave causes a noticeable change in a plurality of arbitrary frequencies, and when there are multiple large bubbles, the power spectrum of the frequency increases widely, showing a correlation between the size and number of bubbles. Furthermore, when there is one small bubble, a narrow and steep waveform is shown, and when there is one large bubble, a wide waveform is shown, showing a correlation between the size of the bubble and the power spectrum of the frequency. On the other hand, the amplitude of the direct wave decreases when there is a bubble.

A method for detecting the state of bubbles will be explained based on FIGS. 9 to 13. First, the figure shows the received signal of the reflected wave when there are no bubbles. In this way, when there are no bubbles, a peak appears at almost the same position as the frequency of the ultrasonic radiation wave.

The bubbles B floating in the test liquid L exhibit different oscillations depending on the size of the bubbles B depending on the viscosity of the test liquid L. For example, the oscillation of a small bubble is dominated by changes in the trajectory in the horizontal direction, so the power spectrum at that frequency becomes a sharp waveform with a narrow base, while the oscillation of a large bubble is caused by changes in the trajectory in the horizontal direction and the surface shape of the bubble. Since both distortions become dominant, the power spectrum of that frequency becomes a waveform with a wide base, so the shape of the power spectrum of the frequency of the reflected wave and direct wave that occurs with the vibration is independent of the size of the bubble. The area of the power spectrum at this frequency corresponds to the amount of bubbles, that is, the size of the bubbles. In the bubble detection unit of the ultrasonic leak testing device 100 using the test liquid L, the power spectrum value at a peak frequency excluding the transmission frequency and the power spectrum value at one or more frequencies within a certain width from this peak frequency are determined. By calculating the difference, the shape of the frequency power spectrum, that is, the area of the frequency power spectrum can be determined, and the size of the bubble, that is, the volume of the bubble, in other words, the leakage amount can be detected. Furthermore, the leak position is detected from the position of the bubble, and the position of the bubble is identified from the frequency received by the ultrasonic sensor 5.

Furthermore, when there is only one bubble due to leakage from the same small hole or crack, the power spectrum of the frequency associated with the vibration of the bubble is different from that of the ultrasonic wave emitted by the ultrasonic transducer 4. It has only one peak except for the peak due to frequency, but if there are multiple bubbles, each bubble exhibits slightly different fluctuations, so the frequency power spectrum waveform has multiple peaks within a certain range. In reality, the superposition of power spectra of frequencies having these peaks results in a waveform that has a plurality of peaks and the base of the power spectrum of frequencies rises broadly. The total amount of bubbles, that is, the amount of leakage, can be calculated by measuring the amount of change in the power spectrum of frequencies within a certain frequency range in the bubble detection section of the ultrasonic leak test device 100 using the test liquid L. The number of bubbles can be detected by determining the number of peaks.

Regarding the reflected waves, to summarize the above, in the reflected waves when there is one microbubble, as shown in Figure 10, small peaks can be seen at frequencies far away from the main peak, for example, at frequencies higher than the main peak of the radiated waves. A small peak with a narrow half-width is detected. On the other hand, in the reflected wave when there are a plurality of microbubbles, as shown in FIG. 11, a plurality of small peaks are observed at positions away from the main peak. Here, a plurality of small peaks are detected near the main peak of the radiation wave. When there is one even larger bubble, a small broad peak is observed in the reflected wave as shown in FIG. Further, in the reflected wave when there are a plurality of large bubbles, a plurality of small wide peaks are formed as shown in FIG. 13, and as a result, the entire spectrum becomes broad. In this way, the reflected waves are correlated with the size and number of bubbles, and by using such a difference, the amount of bubbles, that is, the amount of leakage can be calculated. Also, since the main peak is the frequency emitted by the ultrasonic transducer 4, it is possible to determine which ultrasonic transducer 4 radiated from the frequency of the main peak, in other words, which ultrasonic transducer 4 emitted the transmitted beam. You can determine whether there are air bubbles on the top.

In addition, the leak testing device 100 emits ultrasonic waves to air bubbles to actively cause the bubbles to oscillate, and detects this change as a change in phase or frequency of the received signal, thereby detecting air bubbles with high precision. can be achieved. For example, when air bubbles rise in the test liquid L, they are prevented from rising by the resistance force associated with the viscosity of the test liquid L, and as a result, the air bubbles are prevented from rising due to the flow of the test liquid L, the rotation of the earth, etc. It causes oscillations such as spiral movement, pendulum movement, and changes in surface shape. Although these oscillations have a correlation with the size of the bubble, their reproducibility is low in reality because changes occur due to trivial mechanical effects. However, by emitting relatively high-power ultrasonic waves horizontally to bubbles, it is possible to induce unique oscillations related to the size of the bubbles, and reproduce the oscillations that are correlated with the size of the bubbles. You can increase your sexuality. For example, even if a large bubble receives ultrasonic waves from the horizontal direction, the shape of the surface will only change, and the horizontal position of the bubble will hardly change.On the other hand, if a small bubble receives ultrasonic waves from the horizontal direction, it will change radially. Causes a relative positional shift. This actively causes changes in the phase and frequency of reflected waves and direct waves that are correlated with the size of the bubble, and also changes the fluctuations that tend to diverge into specific fluctuations related to the size of the bubble. It is possible to converge and calculate the amount of bubbles stably.

In this way, by identifying the transmission beam from the main peak of the spectrum waveform and observing the small peaks, it is possible to understand the number and size of bubbles. Observation of the spectral waveform can be quantitatively processed through arithmetic processing. For example, by calculating the peak position, half-width, average value, etc. of the spectrum and comparing it with a predetermined reference value or threshold value, it is possible to automate these determinations. This calculation and determination are performed by the controller 30.

In this embodiment, the presence or absence and position of bubbles can be detected by detecting the amplitude attenuation or phase change of the direct ultrasonic wave. This principle will be explained based on FIGS. 14 and 15. Ultrasonic waves have the property of attenuating as they advance. The amplitude of the direct wave transmitted through the test liquid L is significantly attenuated when there are bubbles, and the amplitude is not attenuated significantly depending on the flow or floating objects. This is because the bubbles B in the test liquid L reflect over 90% of the ultrasonic waves due to the difference in acoustic impedance, whereas the flowing test liquid L reflects almost 0% and much more because most of the suspended matter is hydrophilic. The reflection is much lower, and there is a difference that is sufficiently distinguishable.

As shown in FIG. 14, when there are no bubbles, the direct wave received by the ultrasonic sensor 5 is attenuated less by the bubbles, and the amplitude of the signal level becomes large. On the other hand, if there are bubbles, the bubbles attenuate the ultrasonic vibrations, and as shown in FIG. 15, the amplitude of the direct wave received by the ultrasonic sensor 5 becomes small. Therefore, by detecting the amount of change in amplitude, the presence or absence of bubbles can be detected. Since such changes in amplitude are relatively significant, the presence or absence of bubbles can be reliably detected using the direct wave, and even if a change in the bubble is falsely detected by the reflected wave, it can be detected from the amount of change in the attenuation of the direct wave. Since the presence or absence of bubbles can be determined, such erroneous detection can be avoided, and highly reliable and stable bubble detection can be achieved. In addition, the frequency of the ultrasonic wave that excited the bubble B is determined from the small peak of the spectrum of the ultrasonic wave received by the ultrasonic sensor 5, and the frequency of the ultrasonic wave that excited the bubble B is determined, and the bubble B is emitted from the ultrasonic transducer 4 of which block 2X. The position of bubble B can be determined by detecting whether it is located in the transmission beam.

In addition, in this embodiment, since air is generally used as the gas supplied into the inspected object W, the running cost is lower than that of the helium gas diffusion type, and the hydrogen adsorption/desorption component is difficult to use with the hydrogen gas diffusion type. It is also applicable to the inspected object W in which materials such as aluminum and carbon fiber are used.

The ultrasonic leak testing device 100 described above emits ultrasonic vibrations from the transmitter 2 to the test liquid L while the test object W is submerged in the test liquid L stored in the test liquid tank 1. The bubble B is detected by receiving the signal excited by the bubble B at the receiving section 3. For this reason, the ultrasonic leak testing device 100 has a structure in which a predetermined amount of the test liquid L can be stored inside the test liquid tank 1. Here, the test liquid L stored in the test liquid tank 1 is generated by the flow when the test object W is submerged in water, by the vibration of direct waves or reflected waves of emitted ultrasonic vibrations, or by the vibration of the reflected waves of the ultrasonic vibrations emitted, or by the The liquid surface may ripple due to an impact when the bubbles B floating in the liquid L burst near the liquid surface. The waves generated on the liquid surface cause the ultrasonic waves traveling in the test liquid L to be diffusely reflected, which may generate noise and reduce the reception sensitivity of the ultrasonic sensor. Therefore, for this type of ultrasonic leak testing device, it is never a desirable state that the surface of the test liquid L stored in the test liquid tank 1 is undulating. In this way, in order to prevent the surface of the test liquid L from undulating, the ultrasonic leak test device 100 can also have the structure shown below.

The ultrasonic leak testing device 100 shown in FIG. 16 prevents the surface of the test liquid L from undulating by overflowing and draining the test liquid L stored in the test liquid tank 1. . The ultrasonic leak testing device 100 shown in the figure has a drain section 16 provided in the test liquid tank 1 and a test liquid L stored in the test liquid tank 1 in order to cause the test liquid L stored in the test liquid tank 1 to overflow. The liquid supply unit 17 supplies liquid.

The drain portion 16 formed in the test liquid tank 1 can be configured, for example, by forming a specific peripheral wall lower than other peripheral walls. In the test liquid tank 1 shown in FIG. 16, among the peripheral walls 10 that constitute four sides of a rectangular shape in plan view, one side, the second peripheral wall 12 (on the right side in the figure), is set higher than the peripheral walls 10 on the other three sides. The drain portion 16 is formed low and allows the test liquid L in the test liquid tank 1 to overflow. This liquid drain part 16 is formed by cutting the upper edge of the second peripheral wall 12 so that it is in a horizontal position, and uniformly overflows the liquid level of the test liquid L stored in the test liquid tank 1. Allows for drainage. In particular, by providing the liquid drain part 16 formed in the test liquid tank 1 over the entire length of the peripheral wall that allows the test liquid L to overflow, the test liquid L near the liquid level can be uniformly distributed from the entire peripheral wall that becomes the liquid drain part 16. The liquid can be drained by overflowing. However, although not shown, the drain portion may be provided by forming only a specific peripheral wall or only a part of a specific peripheral wall to be low.

Furthermore, although not shown in the drawings, the test liquid tank may have two peripheral walls formed lower than the other two peripheral walls of the four sides of the rectangular shape in plan view to serve as a liquid drainage section. Alternatively, the peripheral walls on three sides may be formed lower than the peripheral wall on the other side to serve as a liquid drainage section. In particular, a structure in which a liquid drainage section is provided by forming the first and second peripheral walls on two opposing sides, for example, lower than the peripheral walls on the other two sides among the four sides constituting the rectangle, is suitable for inspection near the liquid surface. The liquid overflows to both sides of the test liquid tank and can be drained smoothly. Furthermore, the test liquid tank does not necessarily have to have one of the peripheral walls lower than the other; instead, all the peripheral walls should be at the same height, and the upper end of the entire circumference of the peripheral wall should be used as a drainage part so that the liquid overflows from the entire peripheral wall. The liquid can also be drained.

As described above, the ultrasonic leak testing device 100 that causes the test liquid L stored in the test liquid tank 1 to overflow is configured to move the test liquid L near the liquid surface to the liquid drain part 16 as shown by the arrow in FIG. Since the test liquid L is caused to flow and overflow, it is possible to effectively prevent the surface of the test liquid L from continuously undulating, and it is possible to effectively suppress and prevent the adverse effects of waves generated on the liquid surface, thereby reducing noise.

The liquid supply unit 17 continuously supplies the test liquid L to the test liquid tank 1 and causes the excess test liquid L to overflow from the test liquid tank 1 . As such a liquid supply section 17, for example, a liquid supply pump or a liquid supply mechanism that utilizes pressure due to a height difference can be used. In particular, when water is used as the test liquid L, the liquid supply section 17 can be used as a water supply, and tap water supplied from a faucet or faucet can be supplied to the test liquid tank 1. The above liquid supply section 17 can adjust the amount of overflow from the test liquid tank 1 by adjusting the supply amount of the test liquid L that is continuously supplied to the test liquid tank 1. The liquid supply unit 17 adjusts the supply amount of the test liquid L so that the overflow amount can suppress the surface of the test liquid L stored in the test liquid tank 1 from undulating.

In the test liquid tank 1 shown in FIG. 16, a supply section 18 to which the test liquid L is supplied from the liquid supply section 17 is arranged at the upper part of the test liquid tank 1. This structure is efficient by supplying the test liquid L to a position close to the liquid surface, allowing only the test liquid L near the liquid surface to flow without causing the entire test liquid L in the test liquid tank 1 to flow. Can easily overflow and dispense liquid. By suppressing the flow of the test liquid L inside the test liquid tank 1, this leak test device can accurately detect the bubbles B while reducing the influence on the bubbles B rising in the test liquid L. Although not shown, the supply section is arranged in the center area of the upper part of the test liquid tank, and the drain part is arranged in the first and second peripheral walls on both sides, so that the test liquid near the liquid level is distributed from the center area to the inner surface areas on both the left and right sides. By causing the liquid to flow and overflow, it is possible to particularly promote the rise of the upper layer test liquid from the central region to the inner surface regions on both the left and right sides without inhibiting the substantially circular rise.

Further, although not shown in the drawings, the test liquid tank may have a supply section to which the test liquid is supplied from the liquid supply section, located at the bottom of the test liquid tank. With this structure, the test liquid supplied from the supply unit located at the bottom of the test liquid tank can be drained by flowing to the top of the test liquid tank and overflowing, so the test liquid can be replaced with a new one over time. You can inspect it while you are doing it. For example, when inspecting a dirty test object, by discharging the dirt components in the test liquid, the test can be continued while the test liquid is made clear. Therefore, the test can be performed while effectively suppressing and preventing false detections and noise caused by dirt components floating in the test liquid.

The content described above regarding the ultrasonic leak testing device 100 according to the first embodiment is applicable to the following embodiments unless there is a contradiction. The reverse is also true.

The ultrasonic leak testing device of the present invention can be suitably applied to a submerged air leak testing device that detects air bubbles using an ultrasonic measurement sensor. Items to be inspected include automobile parts such as castings, engine blocks, transmission cases, shock absorbers, fuel pipes, and fuel tanks, electrical equipment parts, gas and water appliances, food and medicine, and medical equipment. For example, it can be suitably used for inspecting air leaks in vehicle catalytic converters and detecting seal defects such as pinholes in sealed packaging containers.

100, 900...Ultrasonic leak testing device 1...Testing liquid tank 2...Transmitting section 2X...Block 3...Receiving section 4...Ultrasonic vibrator 4x...Central axis 5...Ultrasonic sensor 5x...Central axis 6...Transmitting wall 7...Receiving wall 8...Central region 9...Inner surface area 10...Peripheral wall 11...First circumferential wall 12...Second circumferential wall 13...Third circumferential wall 14...Fourth circumferential wall 15...Bottom plate 16...Drain section 17...Supply Liquid part 18... Supply part 20... Lifting mechanism 22... Warmer 30... Controller L... Inspection liquid W... Inspection object B... Air bubbles

Claims (7)

Detects air bubbles that leak from the test object submerged in the test liquid and float up in the test liquid.
An ultrasonic leak testing device for detecting leakage of the object to be inspected,
a test liquid tank for submerging the test object in the test liquid;
a transmitter that emits ultrasonic vibrations to the test liquid in the test liquid tank;
a receiving unit that receives ultrasonic vibrations emitted to the test liquid by the transmitting unit;
and a controller that detects air bubbles in the test liquid using the received signal of the receiving unit,
The test liquid tank is
comprising a first circumferential wall and a second circumferential wall disposed opposite each other,
The transmitter includes:
A plurality of ultrasonic transducers arranged side by side at predetermined intervals in the horizontal direction inside the first peripheral wall,
The receiving section includes:
A plurality of ultrasonic sensors arranged side by side at predetermined intervals in the horizontal direction inside the second peripheral wall,
The test liquid tank is
Equipped with a lifting mechanism that forcibly floats air bubbles in the test liquid with an upward flow that raises the test liquid.
The rising mechanism includes a warmer that heats the test liquid to generate an upward flow,
The controller,
In the received signal detected by each of the ultrasonic sensors,
An ultrasonic leak testing device characterized by detecting air bubbles accelerated and floating by the upward flow of a test liquid to detect leakage of the object to be tested and the location of the leak. The ultrasonic leak testing device according to claim 1,
The warmer of the rising mechanism is
An ultrasonic leak testing device that heats a test liquid in a central region between the first peripheral wall and the second peripheral wall to generate an upward flow. The ultrasonic leak testing device according to claim 1,
The warmer of the rising mechanism is
Ultrasonic leak detection device placed in the test liquid. The ultrasonic leak testing device according to claim 1,
The warmer of the rising mechanism is
An ultrasonic leak test device that heats the bottom plate of the test liquid tank. The ultrasonic leak testing device according to claim 1,
An ultrasonic leak testing device, wherein the warmer is an electric heater. The ultrasonic leak testing device according to any one of claims 1 to 5,
The transmitter includes:
By dividing multiple ultrasonic transducers into multiple blocks,
An ultrasonic leak testing device in which ultrasonic vibrators in adjacent blocks emit ultrasonic vibrations of different frequencies. The ultrasonic leak testing device according to claim 6,
The transmitter includes:
An ultrasonic leak testing device characterized by having one ultrasonic vibrator placed in each block.

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