WO2014046237A1 - 漏洩検出器、漏洩検知方法および配管網の監視装置 - Google Patents
漏洩検出器、漏洩検知方法および配管網の監視装置 Download PDFInfo
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- WO2014046237A1 WO2014046237A1 PCT/JP2013/075464 JP2013075464W WO2014046237A1 WO 2014046237 A1 WO2014046237 A1 WO 2014046237A1 JP 2013075464 W JP2013075464 W JP 2013075464W WO 2014046237 A1 WO2014046237 A1 WO 2014046237A1
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- piezoelectric element
- leakage
- weight
- thin film
- leak detector
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
- G01M3/24—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using infrasonic, sonic, or ultrasonic vibrations
- G01M3/243—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using infrasonic, sonic, or ultrasonic vibrations for pipes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D5/00—Protection or supervision of installations
- F17D5/02—Preventing, monitoring, or locating loss
- F17D5/06—Preventing, monitoring, or locating loss using electric or acoustic means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P13/00—Indicating or recording presence, absence, or direction, of movement
- G01P13/0006—Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances
- G01P13/0073—Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances by using vibrations generated by the fluid
Definitions
- the present invention relates to a leak detector, a leak detection method, and a piping network monitoring device, and more particularly, to a leak detector that accurately detects a fluid leak in various pipes including water pipes, building pipes, factory pipes, and the like.
- the present invention relates to a piping network monitoring device.
- Patent Document 1 discloses a leak detector in which a detection unit incorporating a piezoelectric element and a pedestal unit made of a rigid material are connected by a rubber material. According to this, it is said that the low frequency vibration transmitted to the synthetic resin tube can be amplified by resonance. In addition, it is said that a leak point can be identified by installing two detectors on a fire hydrant in a water pipe and analyzing the obtained correlation waveform.
- Patent Document 2 discloses a wireless meter reading system that extends battery life by eliminating unnecessary reception of a wireless slave unit. This system wirelessly transmits flow rate information to a remote location using a battery.
- Patent Document 3 discloses a pipe inspection apparatus using a piezoelectric ultrasonic transducer. With this method, the laying state of the lining can be inspected from the outside of the pipe.
- the monitoring device for the piping network of Patent Document 2 uses a battery, it needs to be replaced when the battery is exhausted. If it is for an apartment house, it can be replaced relatively easily, but there is a problem that it is difficult to replace the battery with a pipe buried underground or a pipe provided at a high place.
- a generator such as a turbine in the middle of the pipe, store the electric power, and use it for wireless transmission and reception.
- a turbine or the like is provided in the middle of the piping, the pressure will be reduced as an obstacle, and if the turbine is damaged due to foreign matter being caught, the function as the piping may be impaired.
- Patent Document 3 requires manual work to perform the inspection, and it is not easy to inspect underground pipes or underground pipes. was there.
- An object of the present invention is to provide a leakage detector that is highly sensitive to vibration noise caused by water leakage from a synthetic resin pipe and can take a longer installation span, and thus can more efficiently investigate the leakage of synthetic resin pipe fluid. It is in.
- Another object of the present invention is to provide a piping network that is easy to inspect piping that is not easy to inspect manually, such as underground piping or piping in high places, and that does not require battery replacement. It is to provide a monitoring device.
- a leak detector according to the present invention is a leak detector that detects vibration sound generated by fluid leakage from a pipe, and includes a pedestal, a piezoelectric element that is supported by the pedestal and converts vibration sound into an electrical signal, and a piezoelectric element. And a weight that is loaded, and the piezoelectric element is made of a polymer piezoelectric material.
- the piezoelectric element is made of a polymer piezoelectric material, which lowers the elastic constant of the piezoelectric element and lowers the resonance frequency of a system in which a weight is loaded on the piezoelectric element. Become. Accordingly, the sensitivity to vibration sound due to fluid leakage of the synthetic resin pipe is increased, and the installation span can be increased, so that a more efficient investigation of the leakage of the synthetic resin pipe is possible.
- the piezoelectric element can be regarded as a spring.
- the elastic constant E of polyvinylidene fluoride (polymer piezoelectric material) is 2 to 5 ⁇ 10 9 (N / m 2 ).
- the elastic constant of lead zirconate titanate (ceramic piezoelectric material) is 2 to 10 ⁇ 10 10 (N / m 2 ), which is an order of magnitude larger.
- a vibration sensor using a ceramic piezoelectric element is easily designed to have a high resonance frequency, and the resonance frequency is often set to several kHz.
- the resonance frequency is often set to several kHz.
- the stress applied to the piezoelectric element is reduced, and a large output cannot be obtained.
- the piezoelectric element is made of a polymer piezoelectric material, so that the elastic constant of the piezoelectric material itself is lowered and the resonance frequency is lowered. Electrodes such as silver and nickel copper are attached to the polymer piezoelectric material as necessary.
- a piezoelectric element made of a polymer piezoelectric material has a higher piezoelectric output constant than a ceramic piezoelectric element.
- the piezoelectric output constant g 33 of polyvinylidene fluoride is about 300 ⁇ 10 ⁇ 3 (Vm / N)
- the piezoelectric output constant g 33 of lead zirconate titanate is 20 ⁇ 10 ⁇ 3 (Vm / N ) This indicates that the polymer piezoelectric material has a higher output voltage V when a constant force F is applied.
- V F ⁇ g 33 ⁇ t / A
- F force applied to the piezoelectric material
- t thickness A: cross-sectional area.
- the polymer piezoelectric material in the present invention is not particularly limited, and examples thereof include a stretched polyvinylidene fluoride film and a stretched porous polypropylene film.
- polyvinylidene fluoride has high durability and is preferable.
- the sensitivity can be further increased by laminating a plurality of piezoelectric materials.
- a potential difference can be generated by loading a weight on the piezoelectric film and applying deformation in the thickness direction.
- the thickness of the film is not particularly limited, and may be a thickness called “sheet”.
- the piezoelectric element is supported by the pedestal, and the weight is loaded on a portion not supported by the pedestal of the piezoelectric element.
- the spring constant can be reduced and the resonance frequency can be further reduced.
- the spring constant k is expressed as follows.
- the structure for supporting one end of the piezoelectric element includes, for example, a support means for supporting one end of the piezoelectric element on the pedestal, and the one end of the piezoelectric element supported by the support means. It is assumed that a weight is loaded on the other end of the.
- the spring constant k is expressed as follows.
- the structure for supporting both ends of the piezoelectric element is, for example, provided with support means for supporting both ends of the piezoelectric element on the pedestal, and each end of the piezoelectric element is supported by the corresponding support means, It is assumed that a weight is loaded at the center of the piezoelectric element.
- the detector can be set to a desired resonance frequency by supporting one end or both ends of the piezoelectric element and using the above spring constant calculation formula and the above resonance frequency calculation formula.
- the resonance frequency of a system in which a weight is loaded on the piezoelectric element is preferably set between 10 Hz and 1000 Hz. Only a part of the piezoelectric element is supported on the pedestal, and the weight is loaded on the part not supported by the pedestal of the piezoelectric element, so that the resonance frequency can be easily set to 1000 Hz or less. It becomes.
- the leak detector of the present invention can be suitable for the fluid leak investigation of the synthetic resin pipe as described above.
- the piezoelectric element is preferably laminated on at least one surface above and below the reinforcing material layer.
- the position of the piezoelectric element layer is separated from the neutral axis of the laminate, and the sensitivity can be increased. Therefore, the sensitivity to vibration sound due to fluid leakage of the synthetic resin pipe is increased, and the installation span can be increased, so that it is suitable for investigation of fluid leakage of the synthetic resin pipe.
- a film-like piezoelectric element and a sheet-like reinforcing material layer Is supported by one end or both ends of the laminate, and a bending deformation (elastic deformation) is applied to the piezoelectric element layer by a weight load to generate a current or a potential difference.
- a bending deformation elastic deformation
- a potential difference is generated in the thickness direction.
- the direction in which a potential difference occurs differs between when a tensile stress is applied and when a compressive stress is applied after being released from the tensile stress. That is, it is converted into alternating current electricity.
- tensile stress is applied to the surface on one side of the neutral axis of the laminate, and compressive stress is applied to the other surface.
- the neutral axis is a position where the stress is zero, and the tensile stress and the compressive stress increase as the distance from the neutral axis increases.
- a large stress is generated in the piezoelectric element by bending and deforming the laminated body, and accordingly, an electric signal obtained by the piezoelectric element also becomes large.
- the neutral axis when the neutral axis is located within the thickness of the piezoelectric element, it is divided into a part that receives tensile stress and a part that receives compressive stress inside the same piezoelectric element, and the signal strength rapidly increases by canceling the current and potential difference. Decreases.
- the piezoelectric element layer is laminated on at least one of the upper and lower surfaces of the reinforcing material layer, the position of the piezoelectric element is separated from the neutral axis of the laminate, and the electric signal output (sensitivity) can be increased. .
- a stretched film of polyvinylidene fluoride has a thickness of about 100 ⁇ m, and in order to increase sensitivity, it is preferable to have a laminated structure composed of a plurality of film-like piezoelectric elements provided with thin film electrodes on both upper and lower surfaces.
- the piezoelectric element layer By making the piezoelectric element layer into a laminated structure, the area of the film-like piezoelectric element that receives tensile stress and compressive stress can be increased, and high output can be obtained.
- the piezoelectric element layer may be formed by folding a long film-like piezoelectric element (having a width corresponding to one layer and a length corresponding to a plurality of layers) in which thin film electrodes are provided on both upper and lower surfaces into a bellows shape. May be formed.
- the thin film electrode When a film-like piezoelectric element with a thin film electrode is folded in a bellows shape, the thin film electrode is not short-circuited, so that an insulating layer is not necessary, and there is no need to connect individual thin film electrodes, so that a laminated structure can be easily obtained. .
- one thin film electrode of the upper piezoelectric element layer and one of the lower piezoelectric element layers corresponding thereto are arranged so as not to cancel electrical signals. Are connected to each other so that an electric signal is taken out from the other thin film electrode of the upper piezoelectric element layer and the other thin film electrode of the lower piezoelectric element layer corresponding thereto.
- either the thin film electrode or the other thin film electrode of the original piezoelectric element layer may be up or down, but the thin film electrodes are connected to each other. In this case, the electrical signals are connected so as not to cancel.
- the thin film electrode on the uppermost surface of the upper piezoelectric element layer and the thin film electrode on the lowermost surface of the lower piezoelectric element layer are one thin film electrode, and the lowermost surface of the upper piezoelectric element layer
- the other thin film electrodes are connected to each other by a connecting line (electric wire for connection), and one thin film electrode What is necessary is just to connect each other with a lead wire (electric wire for signal extraction).
- the piezoelectric element layers are arranged on the upper side and the lower side of the neutral axis, the direction of stress generated at the top and bottom is different. At that time, a large electrical signal can be obtained by connecting the thin film electrodes so as not to cancel the electrical signal.
- the flexural modulus of the reinforcing material layer is larger than that of the piezoelectric element layer.
- the position of the neutral axis is closer to the material side with higher elastic modulus.
- the ratio of the piezoelectric element layer can be increased if the elastic modulus of the reinforcing material layer is high.
- the neutral axis of bending can be easily piezoelectric It can be made not to exist inside the element layer.
- the piezoelectric element material is a polymer
- the elastic modulus can be relatively reduced, and the neutral axis can be easily moved closer to the reinforcing material layer side.
- a polymer is flexible and does not break when folded.
- the reinforcing material layer is also preferably a polymer.
- PET polyethylene terephthalate
- the thickness is larger than the thickness of the piezoelectric element layer.
- the resonance frequency is variable because the distance between the support position of the piezoelectric element support means and the load position of the weight is mechanically variable.
- the piezoelectric element that converts the vibration sound into an electric signal since the piezoelectric element that converts the vibration sound into an electric signal, the supporting means that supports one end of the piezoelectric element, and the weight that loads the other end of the piezoelectric element, the spring constant is provided. Becomes smaller and the resonance frequency becomes lower. Accordingly, the sensitivity to vibration sound due to fluid leakage of the synthetic resin pipe is increased, and the installation span can be increased, so that a more efficient investigation of the leakage of the synthetic resin pipe is possible.
- the resonance frequency can be freely controlled. Therefore, using the same leak detector, it is possible to cope with different piping members simply by changing the distance between the support position by the support means and the load position of the weight.
- the resonance frequency is changed without changing the leakage detector according to the material of the piping member and the pipe diameter, using the leakage detector whose resonance frequency is variable.
- highly accurate leakage detection can be performed. Therefore, the system can be simplified as compared with the leak detection method in which the leak detector is changed according to the material of the piping member and the diameter of the pipe.
- a film (or sheet) A potential difference may be generated by supporting one end of the piezoelectric element and bending the piezoelectric element with a weight load. Thereby, a spring constant becomes small and a resonance frequency becomes low. Accordingly, the sensitivity to vibration sound due to fluid leakage of the synthetic resin pipe is increased, and the installation span can be increased, so that a more efficient investigation of the leakage of the synthetic resin pipe is possible.
- the resonance frequency can be changed on the leak detector side, by using the same leak detector and changing the resonance frequency, fluid leakage in various piping members can be achieved. Can be detected.
- L is the length of the cantilever beam, and the distance between the support position of the piezoelectric element support means and the load position of the weight corresponds to this. That is, the resonance frequency is variable by changing the distance between the support position and the load position of the weight.
- ⁇ Leakage vibration caused by pipe leakage differs in peak frequency depending on the pipe material and diameter.
- the resonance frequency can be freely controlled by mechanically changing the length of the beam in accordance with the material and the diameter of the pipe.
- the supporting means includes a supporting means fixed to the pedestal and a portion on one end side of the piezoelectric element.
- a slider that changes the length of the portion of the piezoelectric element supported by moving on the pedestal sandwiched from both sides is provided.
- the distance between the support position and the load position of the weight can be changed with a simple configuration, and the operation for changing the distance between the support position and the load position of the weight can be facilitated.
- the resonance frequency of the leak detector when the distance between the support position and the load position of the weight is maximum is set to 150 Hz or less, and the resonance frequency of the leak detector when the distance between the support position and the load position of the weight is minimum is set to 400 Hz or more. It is preferable that
- a leak detector with a resonance frequency of 150 Hz or less is suitable when the pipe member to be leaked is made of synthetic resin and has a relatively large diameter.
- a leak detector with a resonance frequency of 400 Hz or more is suitable for leak detection. This is suitable when the piping member is made of metal and has a relatively small diameter.
- the leakage detection method according to the present invention is characterized in that any one of the above leakage detectors is installed in the vicinity of a piping member, and the presence or absence of fluid leakage is determined by detecting vibration caused by fluid leakage from the piping. It is.
- the resonance frequency of the leak detector can be varied within a variable range for a pipe member made of synthetic resin, corresponding to whether the pipe member to be leaked is made of synthetic resin or metal.
- the resonance frequency of the leak detector is preferably set to a relatively high value within the variable range, and the leak detection target pipe member Corresponding to whether the pipe diameter is relatively large or small, the resonance frequency of the leak detector is set to a relatively low value within the variable range for piping members having a relatively large diameter.
- the leak detector is not changed according to the material of the piping member or the diameter of the pipe, and the resonance frequency is changed, thereby achieving high accuracy. Leak detection can be performed. Therefore, the system can be simplified as compared with the leak detection method in which the leak detector is changed according to the material of the piping member and the diameter of the pipe.
- a piping network monitoring device includes a plurality of piezoelectric elements that are attached to a plurality of locations of a piping network composed of pipes and joints to convert pressure fluctuations accompanying movement of fluid in the piping into electric charge signals, and each piezoelectric element.
- a communication device that transmits the obtained charge signal, and a display device that receives and displays transmission information from the communication device at a remote location are provided.
- the piezoelectric element one made of a ceramic material such as lead zirconate titanate or barium titanate or one made of a resin material such as polyvinylidene fluoride is used.
- the pipe and the joint receive a force from the fluid flowing in the pipe network, and the piezoelectric element provided in the pipe or the joint is deformed by a minute vibration or strain, and generates a voltage and an electric charge.
- the generated voltage may be transmitted as it is as a signal, or may be used as a power source used for a communication device that once accumulates electric charge in a storage element and transmits a signal.
- Signal transmission may be wired or wireless, but wireless is preferred because there is no fear of disconnection due to a disaster such as an earthquake.
- Signal transmission may be performed constantly or intermittently. Further, signal transmission may be performed only when the signal deviates from a certain standard range without performing signal transmission in normal times.
- Address information is set for each piezoelectric element and transmitted together with charge signal information. Thereby, the location can be specified, and the charge signal information of a plurality of piezoelectric elements can be easily managed.
- the total amount of electric charge stored in the electric storage element during normal operation may be used, or a part of the electric charge may be used as a signal as it is to store the remaining amount.
- the piezoelectric element that acquires electrical signal information and the piezoelectric element that stores electric charge in the power storage element do not have to be the same.
- the power storage element for example, a capacitor such as an electric double layer capacitor is used, but it is not limited to this.
- the piezoelectric element is connected to a control circuit via a charge amplifier, and the control circuit may be provided with a determination means for determining whether or not a charge signal obtained from the piezoelectric element is normal.
- the above piezoelectric element has a very large output impedance, it is preferable to amplify the charge by a charge amplifier and convert it into a voltage output in order to reduce the influence of noise and to accurately extract it as a signal.
- the normal range for determining an abnormality from the signal may be set by the upper and lower limits of the voltage output, the frequency band of vibration, etc. Whether it is within the normal range may be determined on the reception side, or may be determined by assembling a control circuit on the transmission side. By providing a control circuit on the transmission side and determining abnormality, it is preferable that unnecessary information is cut off and converted into information together with the previously described address information so that unnecessary wireless communication is not performed.
- the display device for example, a personal computer is used, but it is not limited to this.
- an alarm is given by sound or light. It is not always necessary to display numerical information or the like, and only an alarm at the time of abnormality can be provided.
- the piezoelectric element is preferably a stretched film of polyvinylidene fluoride and provided in the joint.
- the stretched film of polyvinylidene fluoride is excellent as a piezoelectric element material in that it is flexible, excellent in impact resistance, and chemically stable.
- the place where the piezoelectric element is attached is not particularly limited as long as it is a part of a pipe network such as a pipe or a joint. However, it is preferably incorporated into a joint that is installed at regular intervals and has no processing such as cutting during construction. In addition, when a large external force such as an earthquake is applied to the piping network, it is easy to detect an abnormality in the piping network because stress is easily applied to the joint.
- the material of the pipes and joints constituting the pipe network is not particularly limited, such as stainless steel, cast iron, concrete, fiber reinforced plastic, polyvinyl chloride, polyethylene, crosslinked polyethylene, polypropylene, polybutene, and fluororesin.
- the type of fluid flowing through the piping network is not particularly limited, such as water, gas, chemical solution, oil, slurry, and the like.
- the piezoelectric element is formed of a polymer piezoelectric material, the elastic constant of the piezoelectric element is lowered, and the resonance frequency of a system in which a weight is loaded on the piezoelectric element is also lowered. Therefore, the sensitivity to vibration sound caused by the fluid leakage of the synthetic resin pipe is increased and the installation span can be increased, so that a more efficient investigation of the fluid leakage of the synthetic resin pipe becomes possible.
- the charge signal obtained from the piezoelectric element is displayed on a remote display device, and this charge signal information is different between when the piping network is normal and when abnormal, It is possible to monitor whether the piping network is normal.
- FIG. 1 is a diagram schematically showing an example of a piping network monitoring device according to the present invention.
- FIG. 2 is a block diagram showing a leak detector used in the piping network monitoring apparatus according to the present invention.
- FIG. 3 is a diagram illustrating an example in which a leak detector is attached to a joint.
- FIG. 4 is a diagram showing an example in which a leak detector is attached to a pipe.
- FIG. 5 is a diagram showing an example of the normal output state of the piping network monitoring device.
- FIG. 6 is a diagram illustrating an example of an output state when the piping network monitoring apparatus is abnormal.
- FIG. 7 is a diagram schematically showing a first embodiment of a leak detector according to the present invention.
- FIG. 1 is a diagram schematically showing an example of a piping network monitoring device according to the present invention.
- FIG. 2 is a block diagram showing a leak detector used in the piping network monitoring apparatus according to the present invention.
- FIG. 3 is a diagram illustrating an
- FIG. 8 is a diagram schematically showing a second embodiment of the leak detector according to the present invention.
- FIG. 9 is a diagram schematically showing a third embodiment of the leak detector according to the present invention.
- FIG. 10 is a plan view of FIG.
- FIG. 11 is a diagram schematically showing a fourth embodiment of the leak detector according to the present invention.
- FIG. 12 is a plan view of FIG.
- FIG. 13 is a diagram schematically showing a fifth embodiment of the leak detector according to the present invention.
- FIG. 14 is a diagram schematically showing a sixth embodiment of the leak detector according to the present invention.
- FIG. 15 is a diagram schematically showing a seventh embodiment of the leak detector according to the present invention.
- FIG. 16 is a diagram schematically showing an eighth embodiment of the leak detector according to the present invention.
- FIG. 15 is a diagram schematically showing a seventh embodiment of the leak detector according to the present invention.
- FIG. 16 is a diagram schematically showing an eighth embodiment of the leak detector according to the present
- FIG. 17 is a diagram schematically illustrating the operation of the comparative example with respect to the leak detector according to the eighth embodiment.
- FIG. 18 is a diagram schematically illustrating the operation of the leak detector according to the eighth embodiment.
- FIG. 19 is a diagram schematically showing a ninth embodiment of the leak detector according to the present invention.
- FIG. 20 is a diagram schematically showing a tenth embodiment of a leak detector according to the present invention.
- FIG. 21 is a diagram illustrating how to obtain the neutral axis in the leak detector according to the eighth embodiment.
- FIG. 22 is a diagram schematically showing an eleventh embodiment of the leak detector according to the present invention.
- FIG. 23 is a diagram showing a state when the slider is moved from the state of FIG.
- FIG. 24 is a diagram showing an example of water leakage sound obtained by using the leakage detector according to the present invention.
- FIG. 25 is a diagram illustrating an example of water leakage sound obtained by using a conventional leakage detector.
- FIG. 1 shows an embodiment of a piping network monitoring device according to the present invention.
- the pipe network monitoring device (1) includes a pipe network (shown as a water pipe network) (2) composed of a plurality of pipes (3) and a plurality of joints (4) (5), and each joint (4).
- the leak detector (6) provided in (5), the radio communication device (7) connected to each leak detector (6), and the information sent from each radio communication device (7) are received.
- an analysis device (8) for analyzing is included in the pipe network monitoring device (1).
- the leakage detector (6) includes a piezoelectric element (9) and a control board (10) electrically connected to the piezoelectric element (9).
- the piezoelectric element (9) is a stretched film (PVDF film) of polyvinylidene fluoride.
- control board (10) is provided with a power supply capacitor (storage element) (11), a charge amplifier (12), a control circuit (13), a wireless circuit (14), and the like.
- a part of the electric charge obtained by the piezoelectric element (9) is sent to the capacitor (11), and the remaining part is sent to the charge amplifier (12).
- the capacitor (11) stores electric charge and supplies a predetermined voltage to each part of the leak detector (6) (charge amplifier (12), control circuit (13), wireless circuit (14), etc.).
- the capacitor (11) may be omitted by using an external power source.
- the battery When a battery is used as the power source, the battery needs to be replaced. However, when the electric charge obtained by the piezoelectric element (9) is used for the power source, the battery need not be replaced.
- the charge signal obtained by the piezoelectric element (9) is amplified. Since the piezoelectric element (9) has a very large output impedance, it is easily affected by noise. However, by using the charge amplifier (12), the charge signal can be amplified and accurately extracted as a voltage signal.
- the voltage signal output from the charge amplifier (12) is processed in the control circuit (13) and then transmitted as monitoring information to the analyzer (8) via the wireless circuit (14).
- Each leak detector (6) is provided with address information, and the pressure fluctuation at a predetermined location of the pipe network (2) can be monitored by an analyzer (8) such as a personal computer.
- normal charge signals at positions indicated by A, B, and C are, for example, as shown in FIG.
- the charge signal is, for example, as shown in FIG. That is, the voltage signal of the leak detector (6) in the vicinity of the damaged part (position B and position C) vibrates greatly beyond the normal range due to the fluid flow, and is at the position closest to the damaged part (position C).
- the voltage signal of the leak detector (6) fluctuates the most (not only the magnitude of the voltage but also the frequency of vibration).
- the upper and lower limits of the voltage output and / or the reference value of the frequency band of vibration are set, and the voltage signal is compared with the reference value.
- the value is exceeded, it can be determined as abnormal.
- excessive vibration due to water leakage can be detected, and the location of water leakage can be identified.
- the analysis device (8) is installed in a central processing room, etc., and is a piping network (2) consisting of piping that is not easy to inspect manually, such as piping buried underground or piping in high places. Even if there is, the abnormality can be easily known.
- the leak detector (6) may be attached to the pipe (3) instead of the joints (4) and (5).
- it is made of a stretched film of polyvinylidene fluoride.
- a piezoelectric element (9) may be attached to the periphery of the tube (3) to connect the piezoelectric element (9) and the control board (10).
- control circuit (13) is provided with appropriate determination means so that monitoring information (abnormal information) is output only when an abnormality occurs.
- monitoring information abnormal information
- the voltage signal output from the charge amplifier (12) may be directly transmitted to the analysis device (8) from the leak detector (6).
- the first embodiment of the leak detector (6) includes an iron base (21), a piezoelectric element (9) installed on the base (21), and a piezoelectric element (9). It has a pair of upper and lower thin film electrodes (22), (23) formed by applying silver paste on both sides, and a weight (24) loaded on the upper thin film electrode (22). Lead wires (25) and (26) are attached to the base (21) and the weight (24), respectively. An oscilloscope, a data logger, etc. that make up the analysis device (8) are connected to the lead wires (25) and (26), so that the potential difference between the pedestal (21) and the weight (24) is measured, and the analysis device Recorded in (8).
- the piezoelectric element (9) is formed of a stretched film (PVDF film) of polyvinylidene fluoride which is a polymer piezoelectric material.
- the resonance frequency fo ⁇ (k / M) / 2 ⁇ (k is the spring constant of the piezoelectric element and M is the mass of the weight) of the system comprising the piezoelectric element (9) and the weight (24) is set to 10 Hz to 1000 Hz. Yes.
- a pedestal (21) is fixed to a polyvinyl chloride pipe (2) with a diameter of 75mm, and a synthetic resin pipe (3) made of polyvinyl chloride is used with a constant force at a point 10m away from it. I hit it.
- the frequency spectrum of the waveform (leakage sound) at that time is shown in FIG. A large signal was recorded in a frequency band lower than 1000 Hz.
- FIG. 25 shows a frequency spectrum of a waveform (water leakage sound) when the piezoelectric material is lead zirconate titanate.
- FIG. 25 it can be seen that almost no signals in the low frequency region, which are characteristic vibrations of the synthetic resin pipe (3) obtained in FIG. 24, are picked up.
- the leak detector (6) shown in FIG. 7 the sensitivity to vibration noise caused by water leakage of the synthetic resin pipe (3) made of polyvinyl chloride, which has been difficult in the past, becomes high. Therefore, since the installation span of the leak detector (6) can be made long, it is possible to efficiently investigate the leak of the synthetic resin pipe (3).
- the entire surface of the piezoelectric element (9) is supported by the pedestal (21), but the supporting method is not limited to this, and an embodiment as shown below may be adopted.
- the second embodiment of the leak detector (6) includes an iron pedestal (21), a piezoelectric element (9) installed on the pedestal (21), and a lower end (21) ) And a support (support means) (27) that supports the piezoelectric element (9) at the upper end, and a pair of upper and lower thin-film electrodes (22) formed by applying silver paste on both sides of the piezoelectric element (9) ) (23) and a weight (28) loaded on the upper thin film electrode (22).
- the column (27) is insulated from the upper and lower thin film electrodes (22) and (23), and lead wires (25) and (26) are attached to the respective thin film electrodes (22) and (23). .
- the analysis device (8) is connected to the lead wires (25) and (26), whereby the potential difference between the upper thin film electrode (22) and the lower thin film electrode (23) is measured, and the analysis device ( Recorded in 8).
- the support of the piezoelectric element (9) by the support (27) is cantilevered, and one end of the piezoelectric element (9) is supported by the upper end of the support (27).
- the weight (28) is stacked on the other end of the piezoelectric element (9).
- the piezoelectric element (9) is formed of a stretched film (PVDF film) of polyvinylidene fluoride which is a polymer piezoelectric material. Since one end of the piezoelectric element (9) is supported, the spring constant k is expressed as follows.
- E Elastic constant of piezoelectric material
- J Second moment of section
- L Length (dimension in the horizontal direction in FIG. 8)
- b Width (dimension in the front and back direction in FIG. 8)
- h Height (vertical direction in FIG. 8) Size)
- the resonance frequency fo ⁇ (k / M) / 2 ⁇ of the system composed of the piezoelectric element (9) and the weight (28) is set to 10 Hz to 1000 Hz.
- one piezoelectric element is fixed to one support means.
- the present invention is not limited to this.
- a plurality of piezoelectric elements are fixed to one support means and a weight corresponding to the piezoelectric element is provided. By doing so, it can also be set as the structure with multiple cantilever beams.
- the third embodiment of the leak detector (6) includes an iron pedestal (21), a piezoelectric element (9) installed on the pedestal (21), and a lower end portion of the pedestal (21 ) And a pair of struts (support means) (29), (30) that support the piezoelectric element (9) at the upper end, and upper and lower parts 1 formed by applying silver paste on both sides of the piezoelectric element (9).
- a pair of thin film electrodes (22) and (23) and a weight (31) mounted on the upper thin film electrode (22) are provided.
- Each column (29) (30) is insulated from the upper and lower thin film electrodes (22) (23), and lead wires (25) (26) are connected to each thin film electrode (22) (23). It is attached.
- the lead wires (25) and (26) are connected to the analyzer (8), whereby the potential difference between the pair of upper and lower thin film electrodes (22) and (23) is measured and recorded in the analyzer (8). .
- the support of the piezoelectric element (9) by the support columns (29) and (30) is a both-end support, and both ends of the piezoelectric element (9) are the upper ends of the support columns (29) and (30).
- the weight (31) is loaded on the center of the piezoelectric element (9).
- the piezoelectric element (9) is formed of a stretched film (PVDF film) of polyvinylidene fluoride. Since both ends of the piezoelectric element (9) are supported, the spring constant k is expressed as follows.
- E Elastic constant of piezoelectric material
- J Secondary moment of section
- L Length (dimension in the horizontal direction in FIG. 9)
- b Width (dimension in the front and back direction in FIG. 9)
- h Height (vertical direction in FIG. 9) Size)
- the resonance frequency fo ⁇ (k / M) / 2 ⁇ of the system composed of the piezoelectric element (9) and the weight (31) is set to 10 Hz to 1000 Hz.
- the shapes of the piezoelectric element (9) and the thin film electrodes (22) (23) in the leak detector (6) of the third embodiment are not particularly limited, but as shown in FIG.
- the length corresponding to the distance of the rectangle By making the length corresponding to the distance of the rectangle longer than the width orthogonal to the distance, the amount of bending deformation can be increased. When it is desired to reduce the resonance frequency, it can be dealt with by making it a more elongated rectangular shape.
- FIG. 10 shows a diagram corresponding to the third embodiment.
- the piezoelectric element (9) is supported at both ends with respect to the relationship between the support position of the rectangular piezoelectric element (9) and the load position of the weight (31) (
- the weight of the weight (31) is loaded at the center of the piezoelectric element (9), but the center of the piezoelectric element is supported and the weight is loaded at both ends.
- the support of the piezoelectric element can be regarded as having two cantilevers, and the spring constant k can be made as large as that of the second embodiment.
- both end portions of the rectangular piezoelectric element (9) are supported.
- the piezoelectric element (9) has a square or circular shape. The same effect can be obtained even if the weight (33) is stacked on the central portion of the piezoelectric element (9) by supporting the peripheral portion (not both ends).
- This embodiment is shown in FIG. 11 and FIG.
- the fourth embodiment of the leak detector (6) includes an iron pedestal (21), a circular piezoelectric element (9) installed on the pedestal (21), and a lower end portion of the pedestal.
- the column (32) is insulated from the upper and lower thin film electrodes (22) and (23), and lead wires (25) and (26) are attached to the respective thin film electrodes (22) and (23).
- the analysis device (8) is connected to the lead wires (25) and (26), whereby the potential difference between the pair of upper and lower thin film electrodes (22) and (23) is measured and recorded in the analysis device (8). .
- the support of the piezoelectric element (9) by the support pillar (32) is the peripheral edge support, and the peripheral edge part (annular) of the piezoelectric element (9) is at the upper end of the support pillar (32). It is supported. Further, the weight (33) is stacked on the central portion of the circular piezoelectric element (9).
- the piezoelectric element (9) is formed of a stretched film (PVDF film) of polyvinylidene fluoride. Since the peripheral portion of the piezoelectric element (9) is supported, the compression deformation is small and the bending deformation is large, and the spring constant k can be made as large as the both-end support. .
- the peripheral portion of the piezoelectric element (9) according to the fourth embodiment is supported and the relation of the weight (33) is reversed to the central portion, and the central portion of the piezoelectric element (9) is supported by a cylindrical support means.
- an annular weight may be loaded on the peripheral edge of the piezoelectric element (9).
- the load is applied by loading the weights (24), (28), (31), and (33) on the upper surface of the piezoelectric element (9), but the weight is suspended from the lower surface of the piezoelectric element.
- the load may be applied to the piezoelectric element.
- the piezoelectric element is supported to be suspended at the lower end of the support means. May be. Examples thereof are shown in FIGS.
- the pedestal (34) has a rectangular parallelepiped hollow shape having a bottom wall (34a), a top wall (34b) and a side wall (34c), Columnar support means (35) is provided on the top wall (34b) in a hanging manner.
- the piezoelectric element (9) has a rectangular shape shown in FIG.
- a pair of upper and lower thin film electrodes (22), (23) is formed on both surfaces of the piezoelectric element (9) by applying silver paste.
- the upper surface of the central portion of the piezoelectric element (9) is fixed to the lower end surface of the support means (35) via the upper thin film electrode (22).
- Two cuboids are used for the weights (36) and (37), and the upper surfaces thereof are respectively bonded to the lower surfaces of both end portions of the lower thin film electrode (23).
- the lower end of the support means (35) and the upper thin film electrode (22) are insulated, and lead wires (25) and (26) are attached to the thin film electrodes (22) and (23), respectively.
- the analysis device (8) is connected to the lead wires (25) and (26), whereby the potential difference between the pair of upper and lower thin film electrodes (22) and (23) is measured and recorded in the analysis device (8). .
- the central portion of the piezoelectric element (9) is supported, and weights (36) and (37) are loaded on both ends of the piezoelectric element (9).
- the spring constant k can be increased.
- the piezoelectric element (9) is changed into a circular shape or a rectangular shape, and the weights (36) and (37) are changed into a cylindrical shape or a rectangular tube shape (first embodiment shown in FIGS. 11 and 12). (Embodiment similar to the fourth embodiment).
- FIG. 14 shows a modification in the case of cantilever.
- the pedestal (38) has a rectangular parallelepiped hollow shape having a bottom wall (38a), a top wall (38b) and a side wall (38c), Near the end of the top wall (38b), columnar support means (39) is provided in a hanging manner.
- the piezoelectric element (9) has a rectangular shape shown in FIG. A pair of upper and lower thin film electrodes (22), (23) is formed on both surfaces of the piezoelectric element (9) by applying silver paste.
- the piezoelectric element (9) is cantilevered, that is, one end is fixed to the lower surface of the support means (39) via the upper thin film electrode (22), and the other end is a free end.
- the weight (40) has a rectangular parallelepiped shape and is loaded on the other end of the piezoelectric element (9).
- the lower end of the support means (39) is insulated from the upper thin film electrode (22), and lead wires (25) and (26) are attached to the thin film electrodes (22) and (23).
- the analysis device (8) is connected to the lead wires (25) and (26), whereby the potential difference between the pair of upper and lower thin film electrodes (22) and (23) is measured and recorded in the analysis device (8). .
- one end of the piezoelectric element (9) is supported and a weight (40) is loaded on the other end of the piezoelectric element (9).
- a weight (40) is loaded on the other end of the piezoelectric element (9).
- FIG. 15 shows another modification in the case of cantilever.
- the pedestal (41) has a rectangular parallelepiped hollow shape having a bottom wall (41a), a top wall (41b) and side walls (41c) (41d). ing.
- the top wall (41b) is not provided with support means, but any one of the side walls (41d) is used as support means, and the piezoelectric element (9) has the rectangular shape shown in FIG. Then, one end thereof is fixed to the side wall (support means) (41d).
- a pair of thin film electrodes (22) and (23) are formed on both surfaces of the piezoelectric element (9) by applying silver paste.
- the weight (42) has a rectangular parallelepiped shape, and its upper surface is bonded to the lower surface of the other end of the lower thin film electrode (23).
- the side wall (41d) as the support means is insulated from the upper and lower thin film electrodes (22) (23), and lead wires (25) (26) are attached to the respective thin film electrodes (22) (23). ing.
- the analysis device (8) is connected to the lead wires (25) and (26), whereby the potential difference between the pair of upper and lower thin film electrodes (22) and (23) is measured and recorded in the analysis device (8). .
- one end of the piezoelectric element (9) is supported and a weight (42) is loaded on the other end of the piezoelectric element (82).
- a weight (42) is loaded on the other end of the piezoelectric element (82).
- the piezoelectric element (9) of the first embodiment is more advantageous than the embodiment in which the entire surface is supported and the weight (24) is loaded on the entire surface.
- the eighth embodiment of the leak detector (6) includes an iron pedestal (21), and upper and lower piezoelectric element layers (9A) (9B) and upper and lower piezoelectric element layers (9A) (9B).
- a laminated body (51) composed of a reinforcing material layer (52) interposed between and a support (support means) (27) having a lower end fixed to a pedestal (21) and supporting the laminated body (51) at the upper end And a weight (28) loaded on the end of the laminated body (51) on the non-fixed side.
- Thin film electrodes (22A) (23A) (22B) (23B) are formed on the piezoelectric element layers (9A) (9B) by applying silver paste on both upper and lower surfaces.
- the column (27) and the thin film electrodes (22A) (23A) (22B) (23B) are insulated, and the upper thin film electrode (22A) and the lower piezoelectric element layer (upper side of the upper piezoelectric element layer (9A) (
- the lead wires (25) and (26) for signal extraction are attached to the lower thin film electrode (23B) of 9B).
- the thin film electrode (23A) on the lower side of the upper piezoelectric element layer (9A) and the thin film electrode (22B) on the upper side of the lower piezoelectric element layer (9B) are connected by an electric wire (53).
- An analysis device (8) is connected to the lead wires (25) and (26), whereby the potential difference between the upper thin film electrode (22A) and the lower thin film electrode (23B) is measured, and the analysis device Recorded in (8).
- the support of the laminate (51) by the support column (27) is cantilevered, and one end of the laminate (51) is supported by the upper end of the support column (27).
- the weight (28) is stacked on the other end of the laminate (51).
- the piezoelectric element layers (9A) and (9B) are formed of a stretched film of polyvinylidene fluoride.
- E elastic constant in the piezoelectric material
- L Length (dimension in the horizontal direction in FIG. 16)
- b Width (dimension in the front and back direction in FIG. 16)
- h Height (dimension in the vertical direction in FIG. 16)
- the resonance frequency fo ⁇ (k / M) / 2 ⁇ of the system composed of the laminate (51) and the weight (28) is set to 10 Hz to 1000 Hz.
- the piezoelectric element layers (9A) (9B) are laminated on the reinforcing material layer (52). This effect is demonstrated with reference to FIG. 17 and FIG.
- the neutral axis of the piezoelectric element layer (9) indicated by the alternate long and short dash line coincides with the center plane of the piezoelectric element layer (9) and is located within the thickness of the piezoelectric element layer (9). is doing. For this reason, there is a problem that the positive and negative potentials generated inside the piezoelectric element layer (9) cancel each other, the potential difference is canceled and the signal intensity is reduced.
- the position of the upper and lower piezoelectric element layers (9A) (9B) is the neutral axis of the laminate (51) (in this embodiment, the reinforcing material layer (52)
- the potential difference signal output (sensitivity) can be increased.
- the piezoelectric element layers (9A) (9B) are provided on both the upper and lower sides of the reinforcing material layer (52), but either one of the upper and lower piezoelectric element layers (9A) is provided. (9B) may be used.
- each of the upper and lower piezoelectric element layers (9A) (9B) is represented by one layer, but each piezoelectric element layer (9A) (9B) is formed by one film-like piezoelectric element.
- the present invention is not limited to this, and is preferably formed by laminating a plurality of film-like piezoelectric elements.
- the neutral axis of the laminate (51) and the upper and lower piezoelectric element layers (9A) (9B) are separated from each other.
- the distance between the boundary surface between the upper and lower piezoelectric element layers (9A) and (9B) and the reinforcing material layer (52) and the neutral axis is 1/10 or more of the total thickness of the laminate (51), more preferably 1 / 6 or more.
- the neutral axis of the laminated body (51) is defined as follows: the elastic modulus of the piezoelectric element layers (9A) and (9B) is E 1 , the thickness is h 1 , the elastic modulus of the reinforcing layer (52) is E 2 , and the thickness is h 2 . As shown in FIG. 21, a distance h na from the upper surface of the laminate (51) to the neutral axis is obtained by the following equation.
- h na ⁇ (E 1 / E 2) h 1 (h 1/2) + h 2 (h 1 + h 2/2) ⁇ / ⁇ (E 1 / E 2) h 1 + h 2 ⁇
- film-like piezoelectric elements having thin film electrodes formed on both upper and lower surfaces are laminated one by one via an insulating layer, and lead wires are provided for each pair of piezoelectric element layers corresponding to the upper and lower sides. And the signal may be taken out.
- the film-like piezoelectric elements having thin film electrodes formed on the upper and lower surfaces are elongated and folded into a bellows shape.
- a laminated structure composed of film-like piezoelectric elements (9a), (9b) and (9c) with three layers of thin film electrodes (22a), (22b) and (22c) may be used.
- the lead wires (25) and (26) are provided so as to connect the uppermost thin film electrode (22a) and the lowermost thin film electrode (thin film electrode on the back side of the thin film electrode indicated by reference numeral (22c)).
- the thin film electrode indicated by reference numeral (22b) and the thin film electrode indicated by reference numeral (22c) are superposed, but these are originally thin film electrodes on the same side of the piezoelectric element layer (9), so that the short circuit There is nothing to do. Therefore, since an insulating layer is not required and it is not necessary to connect individual thin film electrodes, a laminated structure can be easily obtained as compared with a case where film-like piezoelectric elements are laminated one by one through an insulating layer.
- the laminated structure consisting of the three layers of film-like piezoelectric elements (9a), (9b) and (9c) folded in a bellows shape shown in FIG. 19 is vertically symmetrical with respect to the center plane of the reinforcing material layer (52).
- positioned also so that it may become lower is shown.
- the thin film electrode on the lower side of the film-like piezoelectric element (9c) in contact with the reinforcing material layer (52) in the upper piezoelectric element layer (9A) (the thin film on the back side of the thin film electrode indicated by reference numeral (22c)). Electrode) and the thin film electrode (22f) on the upper side of the film-like piezoelectric element (9f) in contact with the reinforcing material layer (52) in the lower piezoelectric element layer (9B)
- the thin film electrodes on the same side of the element film are connected to each other by an electric wire (53).
- the uppermost thin film electrode (22a) of the uppermost piezoelectric film (9a) of the upper piezoelectric element layer (9A) and the lowermost film of the lower piezoelectric element layer (9B) The thin film electrode on the lower side of the piezoelectric element (9d) (the thin film electrode on the back side of the thin film electrode indicated by reference numeral (22d)) is the thin film electrode on the same side of the original long piezoelectric element film and the above-mentioned
- the thin film electrodes are opposite to the thin film electrodes connected by the electric wire (53), and lead wires (25) and (26) are connected to them.
- the film-like piezoelectric elements (9a) (9b) (9c) (9d) (9e) (9f) are folded in a bellows shape, so that the thin-film electrodes (22b) (22c) (22d) (22e) Since a short circuit can be prevented, an insulating layer is not necessary, and it is only necessary to connect the upper and lower thin film electrodes, so that a laminated structure can be easily obtained.
- the laminate (51) composed of the piezoelectric element layers (9A) (9B) and the reinforcing material layer (52) is only a part thereof. Since it is supported by the pedestal (21) and the weight (28) is loaded on the portion of the laminate (51) that is not supported by the pedestal (21), the resonance frequency is the same as in the second embodiment. Can be reduced.
- the detector can be set to a desired resonance frequency by the above-described spring constant calculation formula and the above-described resonance frequency calculation formula.
- the resonance frequency of a system in which a weight is loaded on the piezoelectric element is preferably set between 10 Hz and 1000 Hz. Only a part of the piezoelectric element is supported by the pedestal, and the weight is loaded on the part not supported by the pedestal of the piezoelectric element, so that the resonance frequency can be easily set to 1000 Hz or less.
- the leak detector (6) described above can be made suitable for investigating fluid leaks in synthetic resin pipes.
- the configuration for bending and deforming the piezoelectric element may be an embodiment corresponding to the third to seventh embodiments in addition to the above embodiment (corresponding to the second embodiment).
- the reinforcing material layer (52) has a length (horizontal dimension in FIG. 16) of 40 mm, a width (dimension in the paper direction of FIG. 16) 25 mm, and a thickness of 700 ⁇ m.
- the piezoelectric element layers (9A) and (9B) are formed by stacking three PVDF films having a thickness of 110 ⁇ m. By providing thin film electrodes on the piezoelectric element layers (9A) and (9B), the thickness of one layer of the piezoelectric element layers (9A) and (9B) is 122 ⁇ m.
- the bending elastic modulus of the piezoelectric element layers (9a), (9b) and (9c) with the thin film electrodes (22a), (22b) and (22c) is 21 GPa, and the bending elastic modulus of the reinforcing material layer (52) is 3.0 GPa. It was.
- the mass of the weight (28) was 1.2 g.
- the thickness of the piezoelectric element layers (9A) and (9B) is 366 ⁇ m, which is the total thickness of three layers, and the total thickness of the laminate (51) is 1066 ⁇ m.
- the neutral axis at this time is calculated as a position of 673 ⁇ m from the upper surface of the laminate (51) using the relationship shown in FIG. 21, and this position is inside the reinforcing material layer (52) made of a PET sheet. .
- the distance from the neutral axis of the laminate (51) to the lower surfaces of the piezoelectric element layers (9A) and (9B) is 207 ⁇ m. This corresponds to about 1/5 of the thickness of the laminate (51).
- the reinforcing material layer (23) is the same as that of Example 1, and the upper and lower piezoelectric element layers (9A) and (9B) are both in Example 1. From the same film. Therefore, the total thickness of the laminate (51) is 1432 ⁇ m.
- the position of the neutral axis is a position of 716 ⁇ m from the upper surface of the laminate (51) and is inside the reinforcing material layer (52) made of a PET sheet.
- a distance from the neutral axis of the laminate (51) to the boundary surface between each piezoelectric element layer (9A) (9B) and the reinforcing material layer (52) is 350 ⁇ m. This corresponds to about 1/4 of the thickness.
- the second embodiment it is possible to obtain a signal having a magnitude necessary for detecting a water leakage sound as shown in FIG. 24, and it is possible to obtain a larger signal than that of the first embodiment.
- the bending frequency can be used for vibration, so that the resonance frequency of the system in which the weight (28) is loaded on the piezoelectric element layers (9A) (9B) is reduced to a desired small value. It can be set easily. That is, according to the leak detector (6) of each of the above embodiments, a large signal can be recorded in a frequency band lower than 1000 Hz, and a synthetic resin tube such as polyvinyl chloride, which has been difficult in the past, can be recorded.
- the leak detector (6) is installed on an iron pedestal (21) and a pedestal (21).
- the support means (61) includes a support (62) whose lower end is fixed to the pedestal (21) and supports the piezoelectric element (9) at the upper end, and a slider (63) that moves on the pedestal (21). ing.
- the column (62) is insulated from the upper and lower thin film electrodes (14) (15), and lead wires (17) (18) are attached to the thin film electrodes (14) (15). .
- the analysis device (8) is connected to the lead wires (17) and (18), whereby the potential difference between the upper thin film electrode (14) and the lower thin film electrode (15) is measured and the analysis device ( Sent to 8).
- the support of the piezoelectric element (9) by the support (62) is cantilevered, and one end of the piezoelectric element (9) is supported by the upper end of the support (62).
- the weight (28) is stacked on the other end of the piezoelectric element (9).
- the slider (63) is a cantilevered piezoelectric element (9) and thin film electrodes (22) (23) on the upper and lower holding plates (64 ) (65) and a connecting plate (66) for connecting the upper and lower clamping plates (64) and (65).
- the cantilever structure increases sensitivity to vibration noise caused by fluid leakage of the synthetic resin pipe (3).
- the installation span of the leak detector (6) can be increased, so that more efficient water leakage investigation of the synthetic resin pipe (3) becomes possible.
- the slider (63) is separated from the piezoelectric element (9) when in the initial position shown in FIG.
- the slider (63) is movable to the right in the figure from the initial position shown in FIG. 22.
- the piezoelectric element (9) and the thin film electrodes (22) (23) It is possible to move on the pedestal (21) by sandwiching the portion close to the column (62) from both the upper and lower sides. As a result, the length of the supported portion of the piezoelectric element (9) is increased, and the length of the cantilever beam (that is, the length L in the above formula) is decreased.
- the leak detector (6) has the same resonance frequency as the leak detector (6) shown in FIG. 8 when the slider (63) is at the initial position shown in FIG. In addition, the resonance frequency increases as the slider (63) moves to the right.
- ⁇ Leakage vibration caused by pipe leakage differs in peak frequency depending on the pipe material and diameter.
- a synthetic resin pipe tends to have a lower frequency than a metal pipe, and the frequency tends to be smaller as the diameter is larger.
- a leakage frequency peak at 10 to 200 Hz
- a cast iron pipe of ⁇ 75 there is often a leakage frequency peak at 300 to 500 Hz.
- a leakage frequency peak at 100 to 300 Hz.
- the peak of the leakage frequency is various, but if the above leakage detector (6) is used, the resonance phenomenon is used, and the length of the beam is mechanically changed according to the material and the diameter of the pipe, The resonance frequency can be freely controlled.
- the distance between the support position by the support means (13) and the load position of the weight (16) is the maximum (in the state of FIG. 22).
- the resonance frequency of the leak detector (6) is 150 Hz or less and the distance between the support position by the support means (13) and the load position of the weight (16) is the minimum (from the state of FIG. 23, the slider (20) is further to the right
- the resonance frequency of the leak detector (6) in the state where the connecting plate (33) is in contact with the support means (19) is set to 400 Hz or higher.
- the thickness of the piezoelectric element 12 of the leak detector 6 is 2 mm, the length is 60 mm, the width is 25 mm, the elastic modulus as a beam is 3 GPa, and the weight of the weight 16 is 1 g (Example 3) ).
- the resonance frequency of the leak detector (6) shown in FIG. 22 is 133 Hz. If the leak detector (6) is in the state shown in FIG. 23 and the length of the beam is 35 mm, the resonance frequency is 298 Hz, and if the length of the beam is 25 mm, the resonance frequency is 493 Hz.
- the leakage frequency is within the variable range of the resonance frequency of the leakage detector (6) regardless of any of ⁇ 75 polyvinyl chloride piping, ⁇ 75 cast iron pipe and ⁇ 250 cast iron pipe. This can be done by changing the frequency.
- the minimum value that is, the variable range of the resonance frequency of the leak detector (6) can be changed.
- this leak detector (6) fluid leaks in various piping members can be detected by using the same leak detector (6) and changing its resonance frequency.
- the leak detector (6) of each of the above embodiments is used for detecting leaks from water pipe devices, for detecting leaks in various pipes other than water pipes, and for example, pipes for chemicals in factories, etc. It is also used in applications for detecting leakage of fluids such as chemicals.
- fluid leakage can be detected with high accuracy in various pipes including water pipes, building pipes, factory pipes, etc., it is possible to improve the accuracy of flow rate monitoring and abnormality detection in the pipes.
Abstract
Description
V:出力電圧 g33:圧電出力定数 F:圧電材料にかかる力 t:厚み A:断面積。
E:圧電材料の弾性定数 J:断面2次モーメント L:長さ b:幅 h:高さ。
圧電素子の両端を支持する構成は、例えば、台座上に圧電素子の両方の端部を支持する支持手段が設けられて、圧電素子の各端部が対応する各支持手段に支持されており、圧電素子の中央部に錘が負荷されているものとされる。
E:圧電材料の弾性定数 J:断面2次モーメント L:長さ(図8の左右方向の寸法) b:幅(図8の紙面表裏方向の寸法) h:高さ(図8の上下方向の寸法)
圧電素子(9)と錘(28)からなる系の共振周波数fo=√(k/M)/2πは、10Hz~1000Hzに設定されている。
E:圧電材料の弾性定数 J:断面2次モーメント L:長さ(図9の左右方向の寸法) b:幅(図9の紙面表裏方向の寸法) h:高さ(図9の上下方向の寸法)
圧電素子(9)と錘(31)からなる系の共振周波数fo=√(k/M)/2πは、10Hz~1000Hzに設定されている。
複数枚のフィルム状圧電素子を積層する場合、上下両面に薄膜電極が形成されたフィルム状圧電素子を1枚ずつ絶縁層を介して積層し、上下で対応する圧電素子層の組ごとにリード線を設けて信号を取り出すようにすればよい。
Claims (8)
- 配管からの流体漏洩によって生じる振動音を検知する漏洩検出器であって、台座と、台座に支持されて振動音を電気信号に変換する圧電素子と、圧電素子に負荷された錘とを備えており、圧電素子が高分子圧電材料によって形成されていることを特徴とする漏洩検出器。
- 圧電素子は、その一部のみが台座に支持されており、錘は、圧電素子の台座に支持されていない部分に負荷されていることを特徴とする請求項1に記載の漏洩検出器。
- 圧電素子に錘を負荷した系における共振周波数が10Hz~1000Hzの間に設定されていることを特徴とする請求項1または2に記載の漏洩検出器。
- 圧電素子は、補強材層の上下の少なくとも一方の面に積層されていることを特徴とする請求項1から3までのいずれかに記載の漏洩検出器。
- 圧電素子の支持手段による支持位置と錘の負荷位置との距離が機械的に可変とされていることにより、共振周波数が可変とされていることを特徴とする請求項1から4までのいずれかに記載の漏洩検出器。
- 圧電素子は、ポリフッ化ビニリデンの延伸フィルムである請求項1から5までのいずれかに記載の漏洩検出器。
- 請求項1から6までのいずれかに記載の漏洩検出器を配管部材の近傍に設置し、配管からの流体漏洩によっておこる振動を検知することで流体漏洩の有無を判定することを特徴とする漏洩検知方法。
- 管および継手からなる配管網の複数箇所にそれぞれ取り付けられて配管内流体の移動に伴う圧力変動を電荷信号に変換する複数の漏洩検出器と、各漏洩検出器で得られた電荷信号を送信する通信機と、通信機からの送信情報を遠隔地で受信して表示する表示装置とを備えており、漏洩検出器は、台座と、台座に支持されて振動音を電気信号に変換する圧電素子と、圧電素子に負荷された錘とを備えており、圧電素子が高分子圧電材料によって形成されていることを特徴とする配管網の監視装置。
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AU2013318975A AU2013318975B2 (en) | 2012-09-24 | 2013-09-20 | Leakage detector, leakage detection method, and pipe network monitoring apparatus |
SG11201502179QA SG11201502179QA (en) | 2012-09-24 | 2013-09-20 | Leakage detector, leakage detection method, and pipe network monitoring apparatus |
US14/430,413 US10168243B2 (en) | 2012-09-24 | 2013-09-20 | Leakage detector, leakage detection method, and pipe network monitoring apparatus |
EP13839205.5A EP2899526B1 (en) | 2012-09-24 | 2013-09-20 | Leakage detector, leakage detection method, and pipe network monitoring apparatus |
CN201380049680.XA CN105247335A (zh) | 2012-09-24 | 2013-09-20 | 泄露检测器、泄露检测方法及配管网的监视装置 |
KR1020157007126A KR20150056784A (ko) | 2012-09-24 | 2013-09-20 | 누설 검출기, 누설 검지 방법 및 배관망의 감시 장치 |
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JP2013041449A JP5873453B2 (ja) | 2012-09-24 | 2013-03-04 | 漏洩検出器 |
JP2013-099943 | 2013-05-10 | ||
JP2013-099949 | 2013-05-10 | ||
JP2013099943A JP5810127B2 (ja) | 2013-05-10 | 2013-05-10 | 圧電型振動センサー |
JP2013099949A JP6134198B2 (ja) | 2013-05-10 | 2013-05-10 | 圧電型振動センサーおよびこれを用いた漏洩検知方法 |
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EP (1) | EP2899526B1 (ja) |
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EP2899526A4 (en) | 2016-06-15 |
EP2899526B1 (en) | 2019-03-20 |
KR20150056784A (ko) | 2015-05-27 |
AU2013318975A1 (en) | 2015-04-09 |
CN105247335A (zh) | 2016-01-13 |
AU2013318975B2 (en) | 2017-02-02 |
EP2899526A1 (en) | 2015-07-29 |
US10168243B2 (en) | 2019-01-01 |
US20150247777A1 (en) | 2015-09-03 |
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