JP2007047056A - Ultrasonic leakage position detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attempt enhancing reliability of bubble inspection using ultrasonic wave and realizing cost-lowering. <P>SOLUTION: The ultrasonic leakage position detection device is equipped with: an ultrasonic transmitter/receiver section 20 capable of irradiating ultrasonic wave to suspension L and receiving the reflected wave R; a transmitted wave receiver 30 prepared at a position receivable to transmitted wave T of ultrasonic wave; and a bubble detector detecting existence or nonexistence of and conditions of bubbles based on the signals of reflected wave R received by the reflected wave receiver section 20 and signals of the transmitted wave T received by transmitted wave receiver 30. At a condition that a test object W is sunk to be arranged at a lower position than the level surface at which the ultrasonic transmitter/receiver section 20 and the transmitted wave receiver 30 are prepared in a suspension tank 10 storing suspension L, so as to pass babbles leaked from the test object W through a gap between the ultrasonic transmitter/receiver section 20 and the transmitted wave receiver 30. Ultrasonic wave is radiated from the ultrasonic transmitter to inspect existence or nonexistence of air leakage, conditions of bubbles, and volume of air leakage at the bubble detector based on the signals of reflected wave R and transmitted wave T. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention detects bubbles using ultrasonic waves, detects small holes or cracks as a damaged part of an object to be inspected such as a sealed tube body such as a steel pipe, and performs an airtightness inspection. The present invention relates to an ultrasonic leak position detection device that can be used.

  The quality inspection of a machine part differs depending on the importance of the intended use of the part. In the case of pipes and storage parts, airtightness such as flammability, solubility, high temperature and low temperature may be extremely important, and 100% inspection is performed. For example, in order to detect airtightness of airtight parts used in automobile parts and to detect small holes as damaged parts of steel pipes and other sealed containers, air as shown in Patent Document 1 is used. Airtight inspection using a leak inspection device is performed. The air leak inspection apparatus causes air bubbles to leak from a part into the water tank by immersing the part in the water tank and filling the part with compressed air. The inspector makes a pass / fail judgment by visually confirming this. This device also has a swinging mechanism for facilitating the generation of bubbles in water, and is used in a wide range of fields because the device is inexpensive and relatively easy to inspect.

  As an example of the airtight inspection method, the method disclosed in Patent Document 2 will be described in detail with reference to FIG. First, both ends of a steel pipe material 61 as an object to be measured are held by a holding device 62 and placed in a water tank 60 filled with water. Next, air is pumped from the pneumatic feeder 63 into the steel pipe 61. At this time, if the steel pipe material 61 has a small hole portion 64 as a damaged portion penetrating the inner and outer surfaces of the steel pipe material 61, the air pumped to the steel pipe material 61 leaks outside through the small hole portion 64, It rises as bubbles 65 in the water. The rising bubbles 65 rise to the water surface and burst. The presence or absence of a small hole is detected by measuring the ultrasonic wave generated at the time of rupture with the microphone 66.

  As described above, the submerged air leak inspection apparatus has been put to practical use in various fields such as automobile parts, gas appliances, and medical instruments. However, since such an apparatus is mainly determined manually by the operator and visually, the ambiguity of the pass / fail determination due to the difference in skill level and the high cost due to the labor cost have been problems at the manufacturing site. For this reason, industries such as electric machinery, oil and gas equipment, automobiles, and food machinery related to these products have attempted to automate a number of inspection apparatuses. Currently, as shown in Patent Document 3, helium and hydrogen gas are used. A differential pressure type automatic inspection apparatus using an air leakage differential pressure as shown in Patent Literature 4 or a gas diffusion type used has been put into practical use.

  However, in the differential pressure type automatic inspection device, when the inspection object is at a high temperature due to the residual heat after welding, etc., the accuracy is not good due to the influence of pressure fluctuation due to gas expansion or the influence of environmental temperature or atmospheric pressure fluctuation. There is a drawback. On the other hand, the gas diffusion type also requires an expensive chamber tank, and there is a problem that it cannot be applied to a reinforced lightweight part using a material having hydrogen absorption / desorption properties such as a composite material such as carbon fiber or a new material.

Moreover, in the automation technology using ultrasonic waves, for example, Patent Documents 5 and 6 have a bubble collecting funnel on an inspection object, and the presence or absence of bubbles and the amount of air are detected by a detector with a bubble collecting tube or a bubble accumulation tube. In what is detected and in Patent Document 7, the presence or absence of leakage is detected by detecting the sound generated when gas leaks from the inspection object as an audible sound or an ultrasonic wave by a detector, the so-called whistling effect associated with leakage. In Patent Document 8, a sensor is directly attached to an inspection object, and the presence or absence of leakage is detected by detecting mechanical vibration or vibration sound generated when gas leaks from the inspection object as ultrasonic waves. Etc. are known. In these air leak inspection apparatuses, it was only possible to detect the presence or absence of a leak, and it was not possible to detect the position where the leak occurred or the exact amount of the leak.
Japanese Utility Model Publication No. 03-27334 Japanese Patent Laid-Open No. 50-43988 JP 2004-163223 A Japanese Utility Model Publication No. 63-63742 Japanese Patent Laid-Open No. 03-180734 No. 3044473 gazette JP-A 63-249033 JP-A-63-133334

  The present invention has been made in view of such conventional problems. The main object of the present invention is to accurately detect only bubbles from changes in the received waveform of transmitted waves and reflected waves using ultrasonic waves, and to detect the size and number of bubbles, compared to conventional devices. An object of the present invention is to provide an ultrasonic leak position detection device that can be applied to a wide range of inspection objects because it improves the reliability of inspection and reduces the cost by automation and does not require a special inspection gas. Another object of the present invention is to provide an ultrasonic leak position detection apparatus capable of detecting a leak position by switching the transmission / reception position of ultrasonic waves in a time division manner.

  In order to achieve the above object, the ultrasonic leak position detection apparatus according to the first aspect of the present invention detects whether or not there are bubbles leaking from the inspection object in a state where the inspection object is submerged in the inspection liquid. An ultrasonic leak position detection device that detects and inspects an object to be inspected. An inspection liquid tank for holding an inspection liquid, and an inspection for sending an irradiation wave of ultrasonic waves to the inspection liquid. One ultrasonic transmission unit arranged in the liquid tank or a plurality of horizontal arrangements in the liquid tank and a plurality of horizontal transmission elements arranged in the horizontal direction in the test liquid tank to receive the reflected ultrasonic wave emitted from the ultrasonic transmission unit A plurality of ultrasonic transmission waves from the ultrasonic transmission unit are arranged in a horizontal direction at a position facing the ultrasonic transmission unit in the test liquid tank and the first ultrasonic reception unit provided at a possible position. And a second ultrasonic receiving unit provided at a position capable of receiving The inspection object is submerged to a position lower than the horizontal plane in which the ultrasonic transmission unit and the second ultrasonic reception unit are arranged in the inspection tank, and bubbles leaking from the inspection object are mixed with the ultrasonic transmission unit and the second ultrasonic wave. In a state where it is arranged so as to pass between the sound wave receiving parts, the ultrasonic wave is irradiated from the ultrasonic wave transmitting part, and the reflected wave and the transmitted wave are reflected and transmitted through the bubbles leaking from the inspection object, Each is received by the first ultrasonic receiving unit and the second ultrasonic receiving unit, and based on the result, the presence / absence and state of the bubbles can be detected. With this configuration, it is possible to accurately detect bubbles by using both the reflected wave and the transmitted wave of ultrasonic waves, and it is possible to realize a highly reliable airtight inspection while avoiding erroneous detection.

  In addition, the ultrasonic leak position detection apparatus according to the second aspect of the present invention includes an amplitude and a phase of a reflected wave signal received by the first ultrasonic receiving unit as compared with an ultrasonic wave. Based on the amount of change in frequency, the amplitude and phase of the transmitted wave signal received by the second ultrasonic wave receiver, and the amount of change in frequency, the size and number of bubbles are detected. It is configured to calculate the amount of bubbles from the product. As a result, the reflected wave detected by the first ultrasonic receiving unit has a small amplitude because there is no large reflection when there is no bubble leakage, and there is a change in phase or frequency when there is a small bubble. When the amplitude is received and there is a large bubble, a large amplitude with a change in phase or frequency is received, and the change in phase and frequency of the detected reflected wave depends on the distance to the bubble and the curvature of the bubble This is used to detect the size and number of bubbles. The transmitted wave detected by the second ultrasonic wave receiving unit receives a small amplitude decrease when there is a small bubble, receives a large amplitude decrease when there is a large bubble, and the received transmitted wave is The size and number of bubbles are detected by utilizing the fact that the phase and frequency of the reflected wave change according to the size and number of bubbles. With this configuration, it is possible to calculate and detect the amount from the product of the size and the number of bubbles from the detected spectrum waveform of the ultrasonic wave, and to realize a highly reliable airtight inspection while avoiding erroneous detection.

  Furthermore, the ultrasonic leak position detection apparatus according to the third aspect of the present invention causes a change in the shape of the surface of a large bubble by irradiating a relatively large output ultrasonic wave from the ultrasonic transmitter, and is small. The bubbles cause a relative movement in the irradiation direction, and this causes a change in phase and frequency depending on the size of the bubbles in the signals received by the plurality of first ultrasonic receivers. By changing the intensity of the ultrasonic wave radiated from the ultrasonic transmitter, the surface area where the ultrasonic wave hits is large when the bubble is large, causing the bubble surface to change its shape, and the phase of the received signal. The frequency, amplitude, and peak width can be changed, and when the bubble is small, the surface area to which the ultrasonic wave hits is small, so the positional movement in the horizontal direction is achieved without accompanying the bubble shape change, This makes it possible to change the phase, frequency, amplitude, and peak width of the received signal, thus avoiding false detections due to the viscosity of the test solution and floating substances mixed in the test solution, and a highly reliable airtight test. Can be realized.

  Furthermore, in the ultrasonic leak position detection apparatus according to the fourth aspect of the present invention, the ultrasonic transmission unit includes a plurality of ultrasonic transmission units, and each ultrasonic transmission unit receives the first ultrasonic reception. The ultrasonic transmitters are arranged in the vertical direction with each of the plurality of first ultrasonic receivers, and the ultrasonic transmitter transmits the timing for generating burst-like ultrasonic waves in a time-sharing manner. It is configured to irradiate ultrasonic waves so as to sequentially scan and scan the inside of the test liquid tank, and is configured to detect the occurrence position of bubble leakage from the signals received by the plurality of first ultrasonic receiving units. Yes. With this configuration, the bubble path in the test liquid tank can be scanned in a planar shape, so that the generation position of the bubble can be ascertained from the transmitted wave received by each of the second ultrasonic receiving units.

  Furthermore, in the ultrasonic leak position detection apparatus according to the fifth aspect of the present invention, the ultrasonic transmission unit includes a plurality of ultrasonic transmission units, and each ultrasonic transmission unit receives the first ultrasonic reception. The ultrasonic transmitters are arranged in the vertical direction with each of the plurality of first ultrasonic receivers, and the ultrasonic transmitter transmits the timing for generating burst-like ultrasonic waves in a time-sharing manner. It is configured to irradiate ultrasonic waves so as to sequentially scan and scan the inside of the test liquid tank, and is configured to detect the occurrence position of bubble leakage from the signals received by the plurality of first ultrasonic receiving units. Yes. With this configuration, the path of the bubbles in the test liquid tank can be scanned in a planar shape, so that the position where the bubbles are generated can be grasped from the reflected wave received by each of the first ultrasonic receivers.

  Furthermore, the ultrasonic leak position detection apparatus according to the sixth aspect of the present invention is a reflected wave signal received by the first ultrasonic receiver and a transmitted wave signal received by the second ultrasonic receiver. And a bubble detector for detecting the presence and state of bubbles. The bubble detector detects changes in amplitude, phase, and frequency in which the reflected wave received by the first ultrasonic receiver and the transmitted wave received by the second ultrasonic receiver are both related by the size and number of bubbles. Therefore, by comparing the change in the reflected wave with the change in the transmitted wave, it is possible to easily identify whether the change in the signal is due to bubbles or due to other floating substances. By adding a calculation function necessary for detecting the state of the bubble to the ultrasonic leak position detection device, the bubble detection can be completed.

  As described above, according to the ultrasonic leak position detection apparatus of the present invention, bubbles are detected reliably and easily without visual observation, and bubble detection and inspection of small holes, cracks, and the like of the inspection object based on the bubbles are detected. Can improve the reliability and accuracy. In particular, since the presence / absence and state of bubbles are detected from the amplitude change, phase change, and frequency change of the received signal using both the reflected wave and transmitted wave of the ultrasonic wave, false detection is prevented and high accuracy is achieved. Realizes accurate leak detection. In addition, the detection by visual inspection is troublesome and there is a drawback that the determination standard is ambiguous because it cannot be quantified.According to the present invention, it is possible to automate and quantify, and the labor cost for uniform determination standard is also high. The advantage is that it can be reduced, and inexpensive and highly reliable detection can be easily performed. Further, this method has a wider range of applicability than the differential pressure type and gas diffusion type inspection methods using hydrogen and helium, and further has the advantage of being able to detect the leak position in addition to the leak amount. In particular, the differential pressure method is affected by residual heat, and the gas diffusion method cannot be applied to a composite material. However, the present invention is not subject to these limitations, and can inspect a wide range of objects to be inspected.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies an ultrasonic leak position detecting device for embodying the technical idea of the present invention, and the present invention is an ultrasonic leak position detecting device as follows. Not specified. Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention unless otherwise specified, and are merely explanations. It's just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and a plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.
(Embodiment 1)

  FIG. 1 is a perspective view showing a schematic configuration of an ultrasonic leak position detection apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a side view thereof. The ultrasonic leak position detection device shown in these drawings includes a test liquid tank 10, a plurality of ultrasonic transmission / reception units 20 arranged in the horizontal direction in the test liquid tank 10, and a position facing the ultrasonic transmission / reception unit 20. And a transmitted wave receiving unit 30 capable of receiving an ultrasonic transmitted wave T from the ultrasonic transmitting / receiving unit 20. The ultrasonic transmission / reception unit 20 receives a reflected wave corresponding to an ultrasonic wave transmission unit that emits an ultrasonic wave and a first ultrasonic wave reception unit that detects a reflected wave R generated by reflection of an ultrasonic wave generated by itself. Also serves as a department. The ultrasonic transmission / reception unit 20 that serves as both the ultrasonic transmission unit and the ultrasonic reception unit is configured by using an ultrasonic transmission / reception element or the like, and has an advantage that the number of parts can be reduced and the arrangement space in the test liquid tank 10 can be reduced. can get.

  The inspection object W is submerged in a state where the inspection liquid L is stored in the inspection liquid tank 10, or the inspection liquid L is filled and submerged in a state where the inspection object W is first placed in the inspection liquid tank 10. . At this time, the inspection object W is submerged to a position lower than the horizontal plane where the ultrasonic transmission / reception unit 20 and the transmission wave reception unit 30 are arranged, and bubbles leaking from the inspection object W are transmitted to the ultrasonic transmission / reception unit 20 and the transmission wave reception unit. It passes between 30.

  The ultrasonic transmission / reception unit 20 and the transmitted wave reception unit 30 are connected to the controller 50. The controller 50 functions as a bubble detection unit for detecting the presence and state of bubbles based on the reflected wave R signal received by the ultrasonic transmission / reception unit 20 and the transmitted wave T signal received by the transmitted wave reception unit 30. Realize. The controller 50 can be an external device such as an external computer. However, by incorporating the controller in the ultrasonic leak position detection device itself, it is possible to detect bubbles and detect their position and amount without adding an external device. Can be realized. The controller 50 includes a display unit that displays a spectrum waveform of the ultrasonic reflected wave R and transmitted wave T detected as necessary, a bubble detection result, and the like. The display unit can be a CRT, a liquid crystal panel, or the like. In addition, an input device such as an operation panel, a console, or a keyboard for operating members of the ultrasonic leak position detection device such as a controller is provided as necessary.

Further, the inspection liquid tank 10 includes an air pipe 12 for supplying compressed air to the inside of the inspection object W submerged in the inspection liquid L. Thereby, compressed air is sent out to the inspection object W, and when the inspection object W has a small hole or a crack, a bubble leaks from the small hole or the crack. The bubbles rise in the test liquid L in the test liquid tank 10, reach the liquid level of the test liquid L, and disappear. In the process of rising bubbles, ultrasonic waves are irradiated from the ultrasonic transmission / reception unit 20 to the movement path of the bubbles to generate a reflected wave R in which the ultrasonic waves are reflected by the bubbles and a transmitted wave T that is transmitted through the bubbles. The reflected wave R is received by the ultrasonic wave transmitting / receiving unit 20, and the transmitted wave T is received by the transmitted wave receiving unit 30. Based on this received signal, the controller 50 detects the presence / absence of air bubbles, that is, the presence of airtight leakage, and detects information such as the amount of bubbles and the position of occurrence based on the state of the air bubbles.
(Inspection bath 10)

  The test liquid tank 10 is a water tank that stores the test liquid L, and is formed in a substantially rectangular container shape that opens upward. Further, on the wall surface of the test liquid tank 10, an ultrasonic transmission / reception unit 20 as an ultrasonic transmission unit and a reflected wave reception unit and an ultrasonic reception unit as a transmitted wave reception unit 30 are arranged.

Ultrasound is irradiated along the horizontal direction or in an oblique direction including a horizontal component. As a result, it is possible to detect the generation position of bubbles in the traveling direction of ultrasonic waves in the horizontal plane as a time difference from irradiation to reflection. In addition, by arranging ultrasonic elements side by side in a direction perpendicular to the traveling direction of ultrasonic waves and irradiating ultrasonic waves from each ultrasonic element in a time-sharing manner in a linear manner, a planar detection surface can be configured, and reflected waves From the presence / absence of changes in R and transmitted wave T, it is possible to grasp the generation position of bubbles in the arrangement direction of the ultrasonic elements.
(Embodiment 2)

  In the first embodiment described above, one ultrasonic transmission / reception unit 20 serves as both the ultrasonic transmission unit and the reflected wave reception unit, but these can also be provided individually. As Embodiment 2 of the present invention, FIG. 3 shows an ultrasonic transmission unit 21 that is an ultrasonic wave generation source and a reflected wave reception unit 40 that receives the reflected wave R of the ultrasonic wave emitted from the ultrasonic transmission unit 21. The perspective view of the ultrasonic type leak position detection apparatus provided individually is shown. In the ultrasonic leak position detection apparatus shown in FIG. 3, the ultrasonic transmitter 21 and the reflected wave receiver 40 are arranged one above the other on one side. Further, by irradiating the ultrasonic wave from the ultrasonic transmission unit 21 while being inclined with respect to the horizontal direction, the reflected wave R in which the ultrasonic wave is reflected by the bubble is reflected at a position different from the irradiation position according to the incident angle. It is configured. Thereby, even if the ultrasonic transmission part 21 and the reflected wave receiving part 40 are arrange | positioned in a different position, the reflected wave R of an ultrasonic wave can be transmitted / received correctly. Further, the transmitted wave receiving unit 30B is disposed so as to be positioned on the diagonal line of the ultrasonic transmitting unit 21, and can correctly receive the transmitted wave T of the ultrasonic wave.

  In the example of FIG. 3, the ultrasonic transmitter 21 is arranged above the wall surface of the test liquid tank 10B so that the ultrasonic irradiation surface is inclined obliquely downward, and on the wall surface facing the test liquid tank 10B, The transmitted wave receiving unit 30B is arranged at a position corresponding to the ultrasonic wave traveling direction of the sound wave irradiation surface so that the transmitted wave reception surface faces obliquely upward. Similarly, the reflected wave receiving unit 40 is also arranged so as to coincide with the traveling direction of the reflected wave R below the wall surface of the test liquid tank 10B, and the traveling direction of the reflected wave R with the reflected wave receiving surface obliquely upward. It is inclined to face each other.

This arrangement is an example, and the arrangement of the ultrasonic transmitter 21, the reflected wave receiver 40, and the transmitted wave receivers 30, 30B, etc. is transmitted waves in the traveling direction of the ultrasonic waves emitted from the ultrasonic transmitter 21. If the receiving units 30 and 30B have such a layout that the reflected wave receiving unit 40 is positioned in the traveling direction of the reflected wave R, the reflected wave R and the transmitted wave T of the ultrasonic wave can be reliably detected. For example, in the ultrasonic leak position detection apparatus according to Embodiment 3 of the present invention shown in FIG. 4, the ultrasonic transmitter 21B is inclined below the wall surface of the test liquid tank 10C and the ultrasonic irradiation surface is inclined obliquely upward. Further, the transmitted wave receiving unit 30C is placed on the opposite wall surface of the test liquid tank 10C at a position corresponding to the ultrasonic wave traveling direction from the ultrasonic wave irradiation surface so that the transmitted wave receiving surface faces obliquely downward. Further, the reflected wave receiving unit 40B is arranged above the wall surface of the test liquid tank 10C so as to coincide with the traveling direction of the reflected wave R, and the reflected wave R advances with the reflected wave receiving surface obliquely downward. It is inclined so as to face the direction. Needless to say, even with such a configuration, it is possible to achieve the same effects as the ultrasonic leak position detection apparatus of FIG.
(Ultrasonic transmitter 21)

  Next, the ultrasonic transmission unit 21 or the ultrasonic transmission / reception unit 20 that generates ultrasonic waves will be described. FIG. 5 shows a front view of the ultrasonic transmitter 21. As shown in this figure, the ultrasonic transmitter 21 has a plurality of ultrasonic elements arranged in a horizontal row. As the element arrangement pattern, various patterns can be appropriately adopted as shown in FIG. 5. However, when the elements to be arranged are wide, each ultrasonic element is superposed between the ultrasonic transmission unit 21 and the ultrasonic transmission / reception unit 20. Even if the sound wave burst is irradiated in a time-sharing manner in a line shape, a planar detection surface cannot be formed, so that two or more elements can be irradiated simultaneously and shifted one by one in a time-division manner or larger than the width of each element. It is necessary to use an element shape or an acoustic lens that can emit sound waves. Alternatively, a configuration may be adopted in which a plurality of individual ultrasonic transmission devices are arranged in the test liquid tank 10. The term “a plurality of ultrasonic transmission units” in the claims is used to include an aspect including a plurality of ultrasonic transmission units including a plurality of such ultrasonic elements and a plurality of ultrasonic transmission units themselves. As the ultrasonic element, an ultrasonic transmission / reception element that combines an ultrasonic transmission element and an ultrasonic reception element, such as the ultrasonic transmission / reception unit 20, can also be used. In addition, one ultrasonic element is provided in the ultrasonic transmission unit, the ultrasonic transmission surface is rotated in a rotating manner or a swinging manner, and the ultrasonic receiving portion is arranged at a corresponding position, thereby allowing one ultrasonic transmission portion to be arranged. It is also possible to configure a planar detection surface by scanning ultrasonic waves with a sound wave element.

Members such as the ultrasonic transmission / reception unit 20 or the ultrasonic transmission unit 21, the reflected wave reception unit 40, and the transmitted wave reception units 30 and 30B are preferably submerged. As a result, a signal can be directly transmitted to and detected from the test liquid L to improve accuracy. These members are covered with a surface member having corrosion resistance, water resistance, acid resistance, alkali resistance, etc. with respect to the test liquid L, or are subjected to resistance treatment such as coating the surface. On the other hand, these ultrasonic members can be provided outside the inspection liquid tank 10. In this case, ultrasonic waves are transmitted and received through the wall surface of the test liquid tank 10. Since the test liquid L is not submerged in water so that the resistance is not so much required, there is an advantage that the cost of the transmission unit and the like can be reduced.
(Time division)

The ultrasonic element can irradiate ultrasonic waves from each element at the same time. Preferably, the ultrasonic elements are irradiated so that the ultrasonic irradiation from the ultrasonic elements is sequentially switched while switching the ultrasonic elements in time division. Interference of elements can be prevented and ultrasonic waves can be detected with high resolution. FIG. 6A shows a timing chart for generating ultrasonic waves in a time-sharing manner from the ultrasonic element shown in FIG. As shown in this figure, the timing for generating burst-like ultrasonic waves is switched in a time-sharing manner, and ultrasonic waves are irradiated so that the inside of the test liquid tank 10 is sequentially scanned in the ultrasonic element array direction without any gaps. As a result, it is possible to determine the time difference between the detection of the reflected wave R and the transmitted wave T from the irradiation and the element at which position of the ultrasonic wave transmitting / receiving unit 20 has detected the signal. Can be identified.

  Further, the multiple of the product of the period of the burst-like ultrasonic wave irradiated from the ultrasonic transmission / reception unit 20 and the rising speed of the bubbles in the test liquid L is based on the vertical beam width of the ultrasonic wave irradiated from the ultrasonic transmission / reception unit 20. If it is small, the same bubble can be repeatedly detected in a specific ultrasonic element, and the accuracy of bubble detection can be improved by comparing the reproducibility of received waves.

  Further, the configuration is not limited to the configuration in which the ultrasonic waves are irradiated by switching in a time division manner, and other configurations can be appropriately employed. For example, as shown in FIG. 6B, ultrasonic waves are simultaneously irradiated from a plurality of elements arranged in a line, and each ultrasonic transmission unit and its reflected wave reception unit and transmitted wave reception unit pair are independent. It is good also as a structure detected. In this case, the resolution between adjacent elements is somewhat lowered. In addition, it is not always necessary to pair the ultrasonic transmitter and the ultrasonic receiver. For example, by changing the irradiation direction of the ultrasonic wave irradiated from one ultrasonic transmitter, a plurality of reflected wave receivers can be provided. On the other hand, the position of the bubble can also be detected by irradiating the irradiation wave radially and scanning the test liquid tank 10 in a planar shape.

  In this way, by scanning the irradiation of ultrasonic waves, the position of the bubble can be detected in a planar shape, and thereby the position of an airtight leak or a crack as a bubble generation source can be detected. In addition, the inspection object W needs to be placed at a position lower than this so that the bubbles pass through the ultrasonic wave irradiation and reflection plane. The inspection liquid tank 10 is preferably provided with a holding structure for holding the inspection object W so as not to move on the bottom surface or below.

  The inspection object W is a member that is desired to detect the occurrence of airtightness, cracks, and small holes, and any member that can be submerged in the inspection liquid L is a target. For example, a vehicle catalytic converter or a fuel tank. In addition, as the inspection liquid L, a liquid that does not cause damage such as corrosion to the object W to be inspected or has little influence is selected, for example, water. The inspection liquid L is preferably an aqueous solution of a rust inhibitor, and is adjusted to a viscosity and temperature in consideration of bubble flow and ultrasonic wave propagation as necessary.

Further, the test liquid tank 10 is made of a material having resistance to the test liquid L, or is coated on the surface with resistance to the test liquid L.
(Ultrasonic)

  Each ultrasonic element transmits ultrasonic waves in the order of MHz. In consideration of attenuation in the test liquid L, it is preferable to use ultrasonic waves of 1 MHz to 20 MHz, and 1 MHz to 2 MHz is desirable from the viewpoint of the ease of the signal processing circuit. When the ultrasonic wave hits the bubble, 90% or more of it is reflected, and the reflected wave R can be detected remarkably. When bubbles rise in the test liquid L, the test liquid L is prevented from rising and floats with fluctuations such as spiral motion, pendulum motion, and surface shape change. When irradiated from the horizontal direction, the reflected wave R causes a frequency shift accompanying fluctuation. The frequency shift is the amount of change in frequency, in other words, the amount of change in frequency, and is usually expressed in hertz (Hz). Furthermore, since the ultrasonic waves are diffracted and superimposed, they are also observed behind the bubbles. As described above, the amount of frequency shift of the transmitted wave T and the reflected wave R varies depending on the fluctuation of the bubble. Therefore, by detecting these, it is possible to detect the state of the bubbles, and consequently the airtightness, leakage amount, etc. of the inspection object W can be detected.

Ultrasonic waves are applied to the bubbles to generate a transmitted wave T and a reflected wave R. Since these signals have different properties, they can be used in combination to prevent misdetection and accurately specify the properties of bubbles. In general, the transmitted wave T is suitable for detection when the amount of bubbles is large, whereas the reflected wave R is suitable when the amount of bubbles is small. The reflected wave R causes a significant change in a plurality of arbitrary frequencies when there are a plurality of small bubbles, and when there are a plurality of large bubbles, the power spectrum of the frequency rises widely and shows a correlation with the size and number of bubbles. . Further, 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 bubble size and the frequency power spectrum. On the other hand, the amplitude of the transmitted wave T decreases when there is a bubble.
(Reflected wave R)

  First, a method for detecting the state of bubbles will be described with reference to FIGS. First, FIG. 7 is a reception signal of the reflected wave R when there is no bubble. Thus, when there is no bubble, a peak appears at a position that is substantially the same as the frequency of the ultrasonic wave.

  Bubbles floating in the test liquid L exhibit different oscillations related to the size of the bubbles due to the viscosity of the test liquid L. For example, small bubble fluctuations are dominated by changes in the horizontal trajectory, so the power spectrum of that frequency has a sharp waveform with a narrow base, and large bubble fluctuations are caused by changes in the horizontal locus and the surface shape of the bubbles. Since both of the distortions of the power wave are dominant, the power spectrum of the frequency has a wide waveform, so that the shape of the power spectrum of the frequency of the reflected wave R and the transmitted wave T generated by the fluctuation is 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 position inspection machine using the test liquid L, the difference between the power spectrum value at the peak frequency excluding the transmission frequency and the power spectrum value at one or more frequencies having a certain width from the peak frequency. , The shape of the frequency power spectrum, that is, the area of the frequency power spectrum, can be obtained, and the size of the bubble, that is, the volume of the bubble, in other words, the amount of leakage can be detected.

  Further, the reflected wave R has a single peak except for the peak due to the transmission frequency when the frequency of the reflected wave R is one bubble accompanying leakage from the same small hole or crack, and the frequency due to the fluctuation of the bubble. When there are a plurality of bubbles, each bubble exhibits a slightly different fluctuation, so that the power spectrum waveform has a frequency having a plurality of peaks within a certain range. A waveform having a plurality of peaks due to the superposition of the power spectrum and a wide range of the power spectrum of the frequency is shown. 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 the frequency within a certain frequency range in the bubble detection unit of the ultrasonic leak position detection device using the test liquid L. The number of bubbles can be detected by obtaining the number of.

Regarding the reflected wave R, when the above is summarized, the reflected wave R when the number of microbubbles is one is changed at an arbitrary frequency as shown in FIG. 8, for example, the half-value width is narrow at a position higher than the irradiation wave. A peak is detected. On the other hand, as for the reflected wave R when there are a plurality of microbubbles, as shown in FIG. Here, a plurality of peaks are detected in the vicinity of the irradiation wave. In the reflected wave R when there is one larger bubble, a broad peak is observed as shown in FIG. The reflected wave R when there are a plurality of large bubbles is in a state where the entire spectrum is broadened as a result of the formation of a plurality of wide peaks as shown in FIG. Thus, the reflected wave R correlates with the size and number of bubbles, and the amount of bubbles, that is, the amount of leakage can be converted by using such a difference.
(Forced bubble oscillation)

  Also, in this embodiment, the bubble is actively generated by irradiating the bubble with ultrasonic waves, and this change is detected as a phase / frequency change of the received signal, thereby detecting the bubble with high accuracy. Can be achieved. For example, when bubbles rise in the test liquid L, the rise is blocked by the resistance force associated with the viscosity of the test liquid L, and as a result, there is a slight influence such as the flow of the test liquid L or the rotation of the earth. Oscillations such as spiral movement, pendulum movement, and surface shape change occur. These fluctuations have a correlation with the bubble size, but in reality, the reproducibility is low because changes occur due to slight mechanical influences. However, by irradiating a bubble with a relatively high power ultrasonic wave from the horizontal direction, it is possible to induce a specific fluctuation related to the size of the bubble, and a fluctuation having a correlation with the size of the bubble. Reproducibility can be improved. For example, in the case of large bubbles, even if ultrasonic waves are received from the horizontal direction, the horizontal position of the bubbles is hardly changed by changing the surface shape. A relative position shift occurs. As a result, the reflected wave R and the transmitted wave T are actively caused to change in phase and frequency, which have a correlation with the bubble size, and fluctuations, which tend to diverge, are caused by specific fluctuations related to the bubble size. It is possible to calculate the stable amount of bubbles by converging on the movement.

Thus, the number and size of bubbles can be grasped by observing the change in the spectrum waveform. The observation of the spectrum waveform can be quantitatively processed by arithmetic processing. For example, these determinations can be automated by calculating the peak position, half-value width, average value, etc. of the spectrum and comparing them with a predetermined reference value or threshold value. This calculation and determination are performed by the controller 50. This makes it possible to detect the size and number of bubbles compared to the conventional method of counting the number of bubbles or guiding bubbles to a tank or funnel and counting them. Can be detected more accurately. It can also be performed visually by the operator based on the spectrum waveform.
(Prevention of false detection)

  On the other hand, even if the reflected wave R is free from bubbles due to leakage, as shown in FIG. 12 due to the floating matter other than bubbles floating in the test liquid L in the test liquid tank 10 and the flow of the test liquid L. A change in the power spectrum of the frequency similar to the change of the power spectrum of the frequency when a plurality of bubbles are generated may occur. However, the reflected wave R due to the flow of the suspended matter or the test liquid L is a reflection that is much lower than the bubble reflecting 90% or more due to the difference in acoustic impedance, so the frequency power spectrum has a peak. It is not noticeable, and occurs close to the peak of the power spectrum due to the transmission frequency, so it can be easily identified that it is not caused by bubbles. Very rarely, in the bubble detection unit of the ultrasonic leak position inspection machine using the test liquid L, the amount of change in the power spectrum of a frequency within a certain frequency range or the power at one or more frequencies of a certain width from the peak frequency When measuring the difference from the spectrum value or when the acoustic impedance is a floating object that has characteristics similar to bubbles, it may be difficult to identify, but in the transmitted wave T, changes in frequency and amplitude due to the floating object Since the change is reduced by the diffraction and superposition of the irradiated ultrasonic wave, and the amplitude does not change due to the flow of the test liquid L, the erroneous detection can be prevented by using the reflected wave R and the transmitted wave T together. The nature of the bubbles can be specified with high accuracy.

Furthermore, even when there are no bubbles, when radiating ultrasonic waves with relatively high power in the horizontal direction from the ultrasonic transmitter, most of the suspended solids are hydrophilic, so almost no shape change or position movement occurs. Since the flow of the test liquid L hardly changes, by changing the intensity of the ultrasonic wave, the test liquid is irradiated with ultrasonic waves that act only on the bubbles and do not affect the flow of the suspended matter or the test liquid L. It is possible to reduce false detections due to floating substances mixed in L and the flow of the test liquid L.
(Transmission wave T)

  In the present embodiment, it is possible to detect the presence or absence of bubbles by detecting the amplitude attenuation or the phase frequency change of the transmitted wave T of ultrasonic waves. This principle will be described with reference to FIGS. Ultrasound has the property of decaying as it progresses. The amplitude attenuation of the transmitted signal is significant when there are bubbles, and is not significant depending on the flow and floating matter. This is because the bubbles in the test liquid L reflect 90% or more of the ultrasonic waves due to the difference in acoustic impedance, whereas the flow of the test liquid L is almost 0%, and most of the suspended matter is hydrophilic. The reflection is low and there is a difference that can be sufficiently distinguished.

  As shown in FIG. 13, when there is no bubble, there is no attenuation by the bubble, and the waveform of the transmitted wave T shows a high amplitude. On the other hand, when there are bubbles, the bubbles are attenuated and the amplitude is reduced as shown in FIG. Therefore, the presence or absence of bubbles can be detected by detecting the amount of change in amplitude. Since such a change in amplitude is relatively remarkable, the presence or absence of a bubble can be reliably detected using the transmitted wave T, and even if a change in the bubble is erroneously detected in the reflected wave R, the attenuation of the transmitted wave T is reduced. Since the presence / absence of bubbles can be determined from the amount of change, such erroneous detection can be avoided, and highly reliable and stable bubble detection can be achieved.

Further, in this embodiment, since air is generally used as the gas to be supplied into the inspection object W, the running cost is lower than that of the helium gas diffusion type, and the hydrogen adsorption / desorption component is difficult with the hydrogen gas diffusion type. The present invention is also applicable to an inspected object W in which materials such as aluminum and carbon fiber are used.
(Actual spectrum waveform)

  Next, FIG. 15 to FIG. 17 show an example in which the ultrasonic wave is actually irradiated to the bubbles, the spectrum waveform of the reflected wave R is measured, and the frequency distribution curve is displayed by the spectrum analyzer. FIG. 15 shows the spectrum waveform of the reflected wave R in a state where there is no inspection object W in the inspection liquid tank 10, and FIG. 16 shows the change of the spectrum waveform when the inspection object W is submerged in the inspection liquid tank 10. Show. As shown in this figure, the change due to the flow of the test liquid L that occurs when the test object W is being submerged in the test liquid tank 10 appears at a low frequency. Further, FIG. 17 shows a spectrum waveform in which compressed air is press-fitted into the inspection object W to generate bubbles and the leakage of the bubbles is detected. The spectrum change due to the leakage of bubbles at this time is larger than that in FIG. 16, and the amplitude increases particularly from the low frequency region to the middle region. As described above, the frequency distribution curve changes significantly in each state. Therefore, by detecting these changes, not only the state of bubbles but also the state in the test liquid tank 10, that is, the state in which the flow occurs or the flow is It is also possible to distinguish between a state where there is no bubble or a state where bubbles are generated.

  A conventional air leak inspection apparatus using ultrasonic waves employs a configuration in which ultrasonic waves are irradiated from above in order to detect the rising speed of bubbles in water by Doppler shift. In other words, the configuration in which the ultrasonic wave is irradiated from the side with respect to the rising direction of the bubbles cannot be adopted, and thus it is difficult to detect the position of the bubbles in the horizontal plane. On the other hand, in the present embodiment, it is possible to detect the position of the bubble by adopting a configuration in which ultrasonic waves are irradiated from the lateral direction and scanning the ultrasonic waves. In addition, in the conventional air leak inspection apparatus using ultrasonic waves, the size of the bubbles cannot be detected because of the method of counting the number of bubbles, and as a result, the amount of leakage cannot be accurately detected. . On the other hand, in this embodiment, since a relatively strong MHz-order ultrasonic wave is irradiated from the horizontal direction and the amount of leakage is calculated from the fluctuation of the bubbles, the amount of leakage is detected regardless of the size of the bubbles. It becomes possible to do. On the other hand, in an air leak inspection apparatus using only the Doppler effect, there is a risk of erroneous detection that reacts even if there are no bubbles. For this reason, in the embodiment of the present invention, by providing the transmitted wave receiving unit 30 that detects the transmitted wave T of the ultrasonic wave, the attenuation of the transmitted wave T is monitored to prevent such erroneous detection. That is, when the suspended matter in the test liquid L, the flow / vibration in the liquid tank, and the amount of bubbles are large, the amplitude intensity, phase, and frequency changes of the ultrasonic signal received by the ultrasonic element array are reflected. It is discriminated from the disturbance generated in the phase and frequency of the received ultrasonic signal and used for the calibration of the bubble amount.

  The ultrasonic leak position detection apparatus of the present invention can be suitably applied to a submerged air leak inspection apparatus using an ultrasonic measurement sensor. Examples of inspection objects include engine parts, transmission cases, shock absorbers, fuel pipes, fuel tanks and other automotive parts, electrical equipment parts, gas / water supplies, food / medicine, medical instruments, and the like. For example, it can be suitably used for air leakage inspection of a catalytic converter for a vehicle and detection of a sealing failure such as a pinhole of a sealed and filled packaging container.

It is a schematic diagram which shows the ultrasonic type leak position detection apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the ultrasonic type leak position detection apparatus of FIG. It is a schematic diagram which shows the ultrasonic type leak position detection apparatus which concerns on Embodiment 2 of this invention. It is a schematic diagram which shows the ultrasonic type leak position detection apparatus which concerns on Embodiment 3 of this invention. It is a front view which shows an example of an ultrasonic transmission part. It is a timing chart which shows the timing which generates an ultrasonic wave by the time division from the ultrasonic element shown to Fig.5 (a). It is a graph which shows the spectrum of the reflected wave when there is no bubble. It is a graph which shows the spectrum of the reflected wave in case there is one small bubble. It is a graph which shows the spectrum of the reflected wave when there are a plurality of small bubbles. It is a graph which shows the spectrum of the reflected wave in case there is one big bubble. It is a graph which shows the spectrum of the reflected wave when there are a plurality of large bubbles. It is a graph which shows the spectrum of a reflected wave when there exists a flow in the test liquid in a test liquid tank. It is a graph which shows the amplitude waveform of the transmitted wave when there is no bubble. It is a graph which shows the amplitude waveform of the transmitted wave in case there exists a bubble. It is an image figure which shows the spectrum of the reflected wave in a state with no to-be-inspected object in a test liquid tank. It is an image figure which shows the spectrum of the reflected wave at the time of submerging a to-be-inspected object to a test | inspection liquid tank. It is an image figure which shows the spectrum of a reflected wave in case there exists a leak of the bubble which arises from a to-be-inspected object. It is a schematic diagram which shows an example of the conventional airtight test | inspection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 10B, 10C ... Test | inspection liquid tank 12 ... Air piping 20 ... Ultrasonic transmission / reception part 21, 21B ... Ultrasonic transmission part 30, 30B, 30C ... Transmitted wave receiving part 40, 40B ... Reflected wave receiving part 50 ... Controller 60 ... Water tank 61 ... Steel pipe material 62 ... Holding device 63 ... Pneumatic feeding device 64 ... Small hole portion 65 ... Bubble 66 ... Microphone W ... Inspection object L ... Test solution T ... Transmission wave R ... Reflected wave

Claims (6)

An ultrasonic leak position detection device that inspects an inspection object by detecting the presence or absence of bubbles leaking from the inspection object in a state where the inspection object is submerged in the inspection liquid,
A test solution tank for holding the test solution;
In order to send out the irradiation wave of ultrasonic waves to the test liquid, one or a plurality of ultrasonic transmitters arranged in the horizontal direction in the test liquid tank,
A plurality of first ultrasonic receiving units arranged in a horizontal direction in the test liquid tank and provided at a position capable of receiving a reflected wave of an ultrasonic wave emitted from the ultrasonic transmitting unit;
A plurality of second ultrasonic waves arranged in a horizontal direction at a position facing the ultrasonic transmission unit in the inspection liquid tank and provided at a position capable of receiving a transmitted wave of ultrasonic waves from the ultrasonic transmission unit. A sound wave receiver,
The inspection object is submerged to a position lower than the horizontal plane in which the ultrasonic transmission unit and the second ultrasonic reception unit are arranged in the inspection liquid tank storing the inspection liquid, and bubbles leaking from the inspection object are In a state of being arranged so as to pass between the sound wave transmitting unit and the second ultrasonic wave receiving unit, the ultrasonic wave is irradiated from the ultrasonic wave transmitting unit, and the ultrasonic wave is reflected and transmitted to the bubbles leaking from the inspection object. The reflected wave and the transmitted wave are received by the first ultrasonic receiving unit and the second ultrasonic receiving unit, respectively, and the presence / absence and state of bubbles are detected based on the results. An ultrasonic leak position detecting device. The ultrasonic leak position detecting device according to claim 1,
Compared with the irradiation wave of the ultrasonic wave, the amplitude and phase of the reflected wave signal received by the first ultrasonic wave receiver, the amount of change in the frequency, and the transmitted wave received by the second ultrasonic wave receiver It is configured to detect the size and number of bubbles based on the amplitude, phase, and frequency variation of the signal, and to calculate the amount of bubbles from the product of the size and number of bubbles. Sonic leak position detector. The ultrasonic leak position detection device according to claim 1 or 2,
By irradiating ultrasonic waves with a relatively large output from the ultrasonic transmission unit, a change in the shape of the surface is caused in a large bubble, and a relative movement is caused in the irradiation direction in a small bubble. An ultrasonic leak position detecting apparatus, wherein a signal received by one ultrasonic wave receiving section is caused to change in phase and frequency depending on the size of a bubble. The ultrasonic leak position detection device according to any one of claims 1 to 3,
The ultrasonic transmission unit includes a plurality of ultrasonic transmission units, and each ultrasonic transmission unit is arranged to face each of the plurality of second ultrasonic reception units in the horizontal direction,
The ultrasonic transmission unit is configured to switch the timing for generating burst-shaped ultrasonic waves in a time-sharing manner, and to irradiate ultrasonic waves so as to sequentially scan the inspection liquid tank. An ultrasonic leak position detection apparatus configured to detect a bubble leak occurrence position from a signal received by a sound wave receiver. The ultrasonic leak position detecting device according to any one of claims 1 to 4,
The ultrasonic transmission unit includes a plurality of ultrasonic transmission units, and each ultrasonic transmission unit has the function of the first ultrasonic reception unit or each of the plurality of first ultrasonic reception units. Are arranged to correspond to the vertical direction,
The ultrasonic transmission unit is configured to switch the timing for generating burst-shaped ultrasonic waves in a time-sharing manner and to irradiate ultrasonic waves so as to sequentially scan the inspection liquid tank, and the plurality of first ultrasonic waves An ultrasonic leak position detection apparatus configured to detect a bubble leak occurrence position from a signal received by a sound wave receiver. The ultrasonic leak position detection device according to any one of claims 1 to 5, further comprising:
A bubble detection unit is provided for detecting the presence and state of bubbles based on the reflected wave signal received by the first ultrasonic receiving unit and the transmitted wave signal received by the second ultrasonic receiving unit. An ultrasonic leak position detecting device characterized by the above.