JP3575106B2 - Pressure measuring device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a pressure measuring device for measuring a sudden pressure change caused by, for example, an explosion phenomenon. More specifically, the present invention relates to a pressure measuring device used for measuring a high pressure, a pressure that changes rapidly, and a pressure that is repeated in a short cycle.
[0002]
[Prior art]
Conventionally, in this type of pressure measuring device, in general, an inorganic piezoelectric crystal such as quartz, tourmaline, ceramics or the like, which exhibits piezoelectricity for converting pressure into an electric signal, is used as a pressure-sensitive element. I have. This pressure-sensitive element is arranged in a metal container or a resin container. Then, the pressure-sensitive element detects the pressure applied to the metal container or the resin container from the outside, and derives an electric signal corresponding to the pressure to the outside.
[0003]
For example, as shown in FIG. 13, electrodes 32 are attached to both sides of a pressure-sensitive element 31 made of quartz, and one electrode 32 is disposed in close contact with the inner surface of a stainless steel container 33. The pair of lead wires 34 is connected to both electrodes 32, respectively, and the other end is connected to an electric wire 35, and leads an electric signal generated in the pressure-sensitive element 31 to the outside. Then, when pressure is applied to the container 33 from the outside, the pressure-sensitive element 31 converts the pressure into an electric signal corresponding to the pressure, and the electric signal electrode is led out through the lead 32, the lead wire 34, and the electric wire 35. . Further, the derived electric signal is recorded by a recording device (not shown).
[0004]
By using this pressure measuring device, a pressure waveform as shown in FIG. 14 is obtained.
[0005]
[Problems to be solved by the invention]
However, such a conventional pressure measuring device is suitable for measuring a low pressure from one direction, but is not suitable for measuring a high pressure from multiple directions in a free fluid such as water or an organic solvent. And the pressure could not be measured with high sensitivity. In particular, when measuring a rapidly changing high pressure caused by an explosion phenomenon or the like, there was a problem that the measurement was not possible because the pressure-sensitive element portions such as quartz, tourmaline, ceramics, and Rochelle salt were brittlely broken. .
[0006]
Moreover, the conventional pressure measuring device uses an inorganic piezoelectric crystal as a pressure-sensitive element, so that it has poor frequency characteristics, and cannot measure a pressure that changes rapidly or a pressure with a short cycle with high sensitivity. was there.
[0007]
The present invention has been made by paying attention to the problems existing in the prior art as described above. An object of the present invention is to provide a pressure measuring device capable of preventing a pressure-sensitive element from being damaged and capable of measuring a rapidly changing high pressure. Another object of the present invention is to provide a pressure measuring device capable of measuring a pressure that changes rapidly or a pressure having a short cycle in a fluid with high sensitivity.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the invention of a pressure measuring device according to claim 1, a pressure measuring device for measuring a rapidly changing high pressure caused by an underwater explosion phenomenon has flexibility. A container, a pressure-sensitive element having a thickness of 20 μm to 20 mm, which is contained in the container via a silicone-based insulating oil having a viscosity of 1 to 50 centipoise and is made of a copolymer of vinylidene fluoride and fluoroalkylene; , A pair of electrodes joined to both surfaces of the pressure-sensitive element, and a pair of lead wires connected to the electrodes .
[0009]
The invention according to claim 2 is a pressure measuring device for measuring a rapidly changing high pressure generated by an explosion phenomenon in water, wherein a thickness of a copolymer of vinylidene fluoride and fluoroalkylene is measured. comprising a pressure-sensitive element of 20Myuemu～20mm, and a pair of electrodes joined to both surfaces of the sensitive圧素Ko, and a pair of leads connected to the electrode, elasticity of the pressure sensitive element and the electrodes with an electrically insulating It is covered with a resin coating layer having a property and capable of transmitting pressure.
[0010]
In the invention described in claim 3, in the invention described in claim 1, the container is made of polyamide .
In the invention described in claim 4, in the invention described in any one of claims 1 to 3, the copolymer has a vinylidene fluoride content of 20 to 95 mol% in monomer ratio .
[0012]
[Action]
According to the first and third aspects of the present invention, when pressure is applied while the pressure measuring device is immersed in a fluid such as water, the pressure is transmitted to the organic polymer material constituting the pressure-sensitive element. . The organic polymer material generates an electric signal proportional to the pressure. By recording this electrical signal, the pressure can be measured. In this pressure measurement, a high pressure or a fast-changing pressure can be measured with high sensitivity while preventing the pressure-sensitive element from being damaged due to characteristics such as viscoelasticity of the organic polymer material. Further, a pressure-sensitive element having a thickness of 20 μm to 20 mm made of a copolymer of vinylidene fluoride and fluoroalkylene is placed in a flexible container via a silicone-based insulating oil having a viscosity of 1 to 50 centipoise. Since it is accommodated, the pressure applied from the outside is transmitted to the pressure-sensitive element via the container and the insulating oil. For this reason, a high pressure can be measured efficiently, and at the same time, the pressure-sensitive element can be protected against a strong impact pressure.
[0013]
According to the second aspect of the present invention, since the pressure-sensitive element is covered with the resin coating layer and the resin coating layer is formed so as to be capable of transmitting pressure, a high externally applied pressure is applied via the resin coating layer. To the pressure sensitive element. Further, since the resin coating layer is electrically insulating, it is possible to prevent an electric signal generated in the pressure-sensitive element from leaking through the resin coating layer.
[0014]
According to the fourth aspect of the present invention, since the copolymer constituting the pressure-sensitive element contains vinylidene fluoride at a monomer ratio of 20 to 95 mol%, the pressure received from the outside is highly sensitive and faithfully converted to an electric signal. Can be converted.
[0016]
According to the first and second aspects of the present invention, since the organic polymer material constituting the pressure-sensitive element is a copolymer of vinylidene fluoride and fluoroalkylene, the pressure received from the outside is more sensitive and can respond to the pressure. It can be converted into a converted electric signal.
[0017]
【Example】
(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
[0018]
As shown in FIGS. 1 to 3, the pressure-sensitive element 11 has a columnar shape and is formed of an organic polymer material that generates an electric signal proportional to a pressure applied from the surroundings. As the pressure-sensitive element 11, any organic polymer that exhibits piezoelectricity can be used. For example, an organic fluorine-based polymer such as polyvinylidene fluoride, a copolymer of vinylidene fluoride, and a cyan-based polymer may be used. Among these, in addition to polyvinylidene fluoride, a copolymer of a fluoroalkylene and vinylidene fluoride is preferable because of its ease of production and the large piezoelectric constant and dielectric constant.
[0019]
As the fluoroalkylene, monofluoroethylene in which one hydrogen is substituted by fluorine can be used, and trifluoroethylene or the like in which one or two hydrogens are left and other hydrogens are substituted by fluorine is preferable, and all hydrogens are substituted. Perfluoroalkylene such as hexafluoropropylene and tetrafluoroethylene substituted with fluorine is more preferred. Further, trifluoroethylene chloride, tetrafluoroalkoxyethylene and the like can be used.
[0020]
In addition, from the viewpoint of high sensitivity and miniaturization of the pressure-sensitive element, polyvinylidene fluoride, a copolymer of vinylidene fluoride and a fluoroalkylene such as trifluoroethylene, which is polarized according to a conventional method, is preferred. As for the composition of the copolymer, usually, vinylidene fluoride is preferably 20 to 95 mol% in terms of monomer ratio, and more preferably 20 to 85 mol%.
[0021]
As the pressure-sensitive element 11, those having various shapes according to the magnitude of the pressure to be measured, such as a plate, a lump, and a disk, are used. In particular, from the viewpoint of manufacturability, workability, and durability, a thin plate having a thickness of 20 mm or less is desirable, and a thin plate or disk having a thickness of 10 mm or less is more desirable. The size must be large enough to produce sufficient polarization for the pressure to be measured.
[0022]
That is, if the pressure is about 10 bar or less, it is desirable to use a disc having a thickness of about 10 μm to 10 mm and a diameter of about 1 to 15 mm, or a polygon having the same size. If the pressure is about 10 bar or more, a disc having a thickness of about 20 μm to 20 mm and a diameter of about 3 to 25 mm, or a polygon having a similar size is desirable. Furthermore, a plurality of pressure-sensitive elements can be stacked and used as one pressure-sensitive element 11. In addition, the pressure-sensitive element 11 in each figure is exaggerated and drawn large.
[0023]
The pair of electrodes 12 a, 12 b has a disk shape and is joined to both upper and lower surfaces of the pressure-sensitive element 11. Each of these electrodes 12a and 12b is in close contact with the surface of the pressure-sensitive element 11 and has an electric conductivity capable of deriving a polarization according to the pressure generated inside the pressure-sensitive element 11 to the outside as an electric signal. Can be used. For example, electrically conductive organic substances such as metals, metal oxides, graphite, and polyacetylene are used. Of these, from the viewpoints of manufacturability, electrical conductivity, and adhesion to the pressure-sensitive element, a material obtained by vapor deposition, plating, or spraying a metal such as aluminum, gold, silver, copper, or tin is preferably used. More desirably, a material obtained by evaporating aluminum is used.
[0024]
One ends of a pair of lead wires 13a and 13b are connected to the electrodes 12a and 12b, and lead out an electric signal from the pressure-sensitive element 11. As the lead wires 13a and 13b, any material can be used as long as it can accurately conduct electric signals from the electrodes 12a and 12b. The size is set so as to obtain a strength that can withstand vibration due to the pressure to be measured. Desirably, a single wire or a stranded wire having a diameter of 5 mm or less and a plate having a thickness of 5 mm or less are used. More preferably, a single wire having a diameter of 3 mm or less, a stranded wire, or a plate having a thickness of 2 mm or less is used. Most preferably, a single wire having a diameter of 1 mm or less, a stranded wire, or a plate having a thickness of 1 mm or less is used.
[0025]
Further, as the material thereof, copper, aluminum or the like is desirable. More desirably, copper, tin, or silver-plated copper is used in terms of manufacturability, price, and availability. Note that the two lead wires 13a and 13b do not necessarily have to have the same shape, and one may be a plate-like wire and the other may be a single wire, or may be combined as appropriate.
[0026]
The container 14 having a substantially rectangular parallelepiped shape is sealed in a state where the lid 15 into which the lead wires 13a and 13b are inserted is heated and melted, joined and integrated. Insulating oil 16 is accommodated in this sealed space, and the pressure-sensitive element 11 is supported in a state of floating in the insulating oil 16. The container 14 is made of a material such as an organic polymer, an inorganic polymer, or a thin metal which has flexibility and can transmit pressure applied from the outside to the insulating oil 16 inside.
[0027]
As organic polymers, synthetic polymers such as vinyl, vinylidene, polyamide, ester, paraffin, and aromatic, synthetic rubber, silicone rubber, and natural rubber polymers have flexibility, Used for easy processing. Among these, a polyamide polymer is particularly desirable. As the inorganic polymer, a silicone resin or silicone rubber is used. As the thin metal, stainless steel, iron, bronze, aluminum, titanium or the like is used. Among these, stainless steel and titanium are desirable because of their good corrosion resistance and durability.
[0028]
The size of the container 14 is such that the insulating oil 16, the pressure-sensitive element 11, the electrodes 12 a and 12 b, and the leads 13 a and 13 b can be accommodated inside the container 14. It is desirable to have a gap of, specifically, a thickness of a portion that transmits pressure to the inside of the container 14 that desirably has a gap of 0.01 mm or more is a thickness having a strength that does not burst even when a measured pressure is applied. It is. For example, a metal plate preferably has a thickness of 0.01 mm or more, and more preferably has a thickness of 0.05 mm or more. The polyamide polymer preferably has a thickness of 0.1 mm or more, more preferably 0.3 mm or more.
[0029]
The container 14 does not necessarily have to have the same thickness as a whole. For example, a portion of the container 14 that transmits external pressure to the internal insulating oil 16 has a thin structure that facilitates pressure transmission as described above. The portion may have a thick structure so as to be advantageous in strength.
[0030]
As the insulating oil 16, any substance can be used as long as it is a liquid to pasty substance at the operating temperature. Usually, hydrocarbon-based, silicone-based oily substances and the like are used. Desirably, silicone-based insulating oil having good insulating properties and durability is preferable. More preferably, a silicone insulating oil having a viscosity of 100 centipoise or less is preferable. Most preferably, a silicone oil having a viscosity of 1 to 50 centipoise and an insulation resistance of 1 megaohm or more is used.
[0031]
As shown in FIG. 5, the other ends of the lead wires 13a and 13b are connected to an electric wire 18 covered with an insulating material 17, and further connected to a recording device (not shown). As the electric wire 18, a JIS standard coaxial cable is preferable from the viewpoint of electric noise resistance and availability. It is desirable that the connection point between the lead wires 13a and 13b and the electric wire 18 be electrically insulated with a tape, a resin, or the like, and a self-sealing tape is preferable.
[0032]
The insulating covering portion 19 covers the lead wires 13a and 13b led out of the container 14 and connected to the electric wire 18 with an insulating material to secure insulation.
Now, as shown in FIG. 5, an explosive 21 is disposed in the water 20, and a pressure measuring device is disposed. Then, when the explosive 21 is exploded, the pressure is applied to the container 14 of the pressure measuring device via the water 20. The impact pressure applied to the container 14 is transmitted to the pressure-sensitive element 11 via the insulating oil 16. The pressure sensing element 11 senses the pressure and emits an electric signal corresponding to the pressure. The electric signal is led out via the leads 13 a and 13 b and the electric wire 18.
[0033]
In the pressure measurement of this embodiment, a high pressure can be measured based on the properties of the organic polymer material such as viscoelasticity while preventing the pressure-sensitive element 11 from being brittlely broken. Or a pressure repeated in a short cycle can be measured with high sensitivity. Therefore, it is possible to measure up to a higher pressure than a conventional pressure measuring device using a piezoelectric crystal for the pressure-sensitive portion. In addition, in the measurement in water, the acoustic impedance between the organic polymer material and water is close, and the measurement can be performed more faithfully than the conventional pressure measuring device.
[0034]
Here, in the first embodiment, a container made of polyamide having a diameter of 15 mm and a thickness of 1.0 mm was used as the container 14. As the pressure-sensitive element 11, a sheet-like polyvinylidene fluoride of an appropriate size stretched to a thickness of 50 μm is used, and aluminum is vapor-deposited on both surfaces, and a voltage that causes a potential gradient of 1 MV / cm according to a conventional method. After polarization treatment was performed at 60 to 80 ° C. until a predetermined piezoelectricity was generated by applying the voltage, a material cut to a diameter of 10 mm was used.
[0035]
As the electrodes 12a and 12b, aluminum deposited on both surfaces was used. As the lead wires 13a and 13b, tin-plated copper wires having a diameter of 0.5 mm were used. As the insulating oil 16, silicone oil having a viscosity of 20 centipoise was used. After connecting a commercially available coaxial cable to the lead wires 13a and 13b, the connection portions were insulated with a self-sealing tape.
[0036]
Then, as shown in FIG. 5, 200 g of a general industrial water-containing explosive as an explosive 21 and a pressure measuring instrument were set in the water 20, and a pressure waveform accompanying the explosion was measured and recorded at a distance of 1 m. FIG. 6 shows the relationship between the pressure and time. As can be seen from FIG. 6, a good pressure waveform can be obtained and a high peak pressure of 200 bar or more can be measured by the pressure measuring device of this embodiment.
(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS.
[0037]
As shown in FIGS. 7 and 8, the container is composed of a cup-shaped container main body 14 a and a thick lid 15. The container main body 14 a is made of polyamide having a diameter of 15 mm and a thickness of 1.0 mm. An epoxy resin having a diameter of 13 mm and a length of 20 mm and having lead wires 13a and 13b penetrated therein was used, and both were bonded by an adhesive. The container body 14a was formed thin to transmit external pressure to the pressure-sensitive element 11, and the cover 15 was formed thick to maintain strength. The container body 14a and the lid 15 can be integrated by means such as fitting or welding.
[0038]
A pressure measuring device was manufactured in the same manner as in Example 1 except for this container. Then, using the same explosive 21 as in the first example, the impact pressure at the time of the explosion was measured by this pressure measuring device. The pressure waveform was almost the same as FIG. 6 of the first embodiment. Therefore, the pressure measuring device of this embodiment can measure a high pressure of 200 bar or more. Further, in this embodiment, the container is composed of the container main body 14a and the thick lid 15, and the lid 15 is joined to the container main body 14a with an adhesive. The pressure can be transmitted at the portion, and the strength of the container can be maintained at the thick lid 15 portion.
(Third embodiment)
Next, a third embodiment of the invention will be described.
[0039]
As the pressure-sensitive element 11, a sheet-like element having a thickness of 50 μm and an appropriate size was used, and was formed of a copolymer having a monomer molar ratio of vinylidene fluoride and propylene fluoride of 1: 1. Furthermore, aluminum was vapor-deposited on both surfaces thereof, and after a polarization treatment, aluminum was cut out to a diameter of 10 mm. A pressure measuring device was manufactured in the same manner as in the second embodiment except for the pressure-sensitive element 11 described above.
[0040]
Then, using the same explosive 21 as in the second embodiment, the impact pressure at the time of the explosion was measured by this pressure measuring device. FIG. 9 shows the pressure waveform. As can be seen from FIG. 9, a high pressure of 200 bar or more can be measured, and a pressure waveform faithfully corresponding to the pressure generated from the explosive 21 is obtained. Therefore, using the copolymer of vinylidene fluoride and propylene fluoride as the pressure-sensitive element 11 can increase the sensitivity in pressure measurement more than using the polyvinylidene fluoride of the first embodiment.
(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIGS.
[0041]
The resin coating layer 22 covers the entire outer surfaces of the pressure-sensitive element 11 and the electrodes 12a and 12b. In this case, the container 14 and the insulating oil 15 are omitted. As the resin coating layer 22, a layer having good electric insulation and elasticity is used. Usually, silicone-based, fluorine-based, and hydrocarbon-based substances are used. In particular, silicone-based and fluorine-based rubbers are preferred from the viewpoints of durability and insulating properties.
[0042]
In this embodiment, the resin coating layer 22 is formed by dispersing a fluorine-based rubber in a solvent, spraying the dispersion several times on the outer surfaces of the pressure-sensitive element 11 and the electrodes 12a and 12b, and then volatilizing the solvent. did. The thickness of the resin coating layer 22 is about 50 μm on average.
[0043]
The pressure-sensitive element 11 was a 50 μm-thick sheet made of a copolymer having a molar ratio of monomers of vinylidene fluoride and trifluoroethylene of 1: 1.
When the impact pressure of the explosive 21 at the time of the explosion was measured in the same manner as in the first embodiment, a good pressure waveform was obtained, a high pressure measurement of 200 bar or more was possible, and the sensitivity in the pressure measurement was improved. Was completed. .
(Comparative example)
As a comparative example, a pressure was measured at a distance of 1 m from the explosive using 200 g of a water-containing explosive in the same manner as in Example 1, except that a commercially available 102A type pressure sensor from PCB was used as the pressure measuring device. However, the pressure gauge was damaged and could not be measured.
[0044]
Therefore, the amount of the water-containing explosive was reduced to 、, the pressure applied to the pressure measuring device was reduced to ／, and the test was performed again to measure the change in pressure. FIG. 14 shows the pressure waveform.
As is clear from the comparison between FIG. 6 and FIG. 14, the pressure measuring device according to the first embodiment can measure a shock wave having a pressure as high as 200 atm. In addition, in FIG. 14, an abnormal V-shaped waveform is recorded around 110 μsec, but such an abnormality is not observed in the pressure measuring device of the first embodiment.
[0045]
The present invention can be embodied by changing the configuration as follows.
(A) As shown in FIG. 12 (a), the container should be tapered so as to become thinner toward one end. As shown in FIG. 12 (b), the container is tapered so as to become thinner toward one end, and has a constant thickness at the end. As shown in FIG. 12C, the container is formed in a cylindrical shape. As shown in FIG. 12 (d), the container should be spherical.
(B) To measure a pressure that changes rapidly and a pressure that is repeated in a short cycle with the pressure measuring device of the present invention.
(C) In the fourth embodiment, a pressure-sensitive element 11 formed of polyvinylidene fluoride is used.
[0046]
Further, a technical idea grasped from the embodiment will be described below.
(1) The pressure measuring device according to claim 1, wherein the pressure-sensitive element is formed in a thin plate shape. With this configuration, the production and processing of the pressure measuring device can be facilitated, and the durability of the pressure measuring device can be improved.
(2) The pressure measuring device according to claim 1, wherein a pair of thin electrodes are attached to the pressure-sensitive element, and a lead wire is connected to these electrodes so that an electric signal can be led out. With this configuration, an electric signal generated by the pressure-sensitive element can be easily taken out through the electrode and the lead wire.
(3) The pressure measuring device according to claim 1 , wherein the insulating oil is a silicone-based insulating oil having a viscosity of 1 to 50 centipoise. According to this configuration, pressure can be transmitted with high sensitivity, and insulation and durability can be improved.
(4) The pressure measurement according to claim 1 , wherein the container is constituted by a container body and a lid, and a pair of lead wires is supported by penetrating the lid, and a pressure-sensitive element is attached to a tip of the lead wire via an electrode. vessel. With this configuration, the pressure-sensitive element can be easily housed in the container, and the pressure-sensitive element can be supported in the insulating oil.
[0047]
【The invention's effect】
As described in detail above, according to the first and third aspects of the present invention, it is possible to prevent the pressure-sensitive element from being damaged and to measure a rapidly changing high pressure. In addition, a pressure that changes rapidly or a pressure that has a short cycle in a fluid can be measured with high sensitivity.
[0048]
According to the second aspect of the present invention, it is possible to prevent the pressure-sensitive element from being damaged by the resin coating layer and to prevent the electric signal generated by the pressure-sensitive element from leaking through the resin coating layer. it can.
[0049]
According to the fourth aspect of the invention, a high pressure received from the outside can be measured with high sensitivity.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a pressure measuring device according to a first embodiment.
FIG. 2 is a sectional view taken along line 2-2 in FIG. 1;
FIG. 3 is a perspective view showing a pressure measuring device.
FIG. 4 is an exploded perspective view showing the assembly of the pressure measuring device.
FIG. 5 is a cross-sectional view of a state in which a pressure measuring device and an explosive are placed in water and pressure is measured.
FIG. 6 is a graph showing a relationship between time and pressure measured by a pressure measuring device.
FIG. 7 is a longitudinal sectional view showing a pressure measuring device according to a second embodiment.
FIG. 8 is a sectional view taken along line 8-8 in FIG. 7;
FIG. 9 is a graph showing a relationship between time and pressure in the third embodiment.
FIG. 10 is a longitudinal sectional view showing a pressure measuring device according to a fourth embodiment.
FIG. 11 is a cross-sectional view showing a pressure measuring device according to a fourth embodiment.
12 (a) to 12 (d) are perspective views of a container showing another example of the present invention.
FIG. 13 is a partial longitudinal sectional view showing an example of a conventional pressure measuring device.
FIG. 14 is a graph showing a relationship between time and pressure based on a conventional pressure measuring device.
[Explanation of symbols]
11: pressure-sensitive element, 14: container, 16: insulating oil, 22: resin coating layer.

Claims (4)

A pressure measuring device for measuring a rapidly changing high pressure generated by an explosion phenomenon in water, comprising a flexible container and a silicone-based insulating oil having a viscosity of 1 to 50 centipoise in the container. A pressure-sensitive element having a thickness of 20 μm to 20 mm made of a copolymer of vinylidene fluoride and fluoroalkylene, a pair of electrodes joined to both surfaces of the pressure-sensitive element, and connected to the electrodes. A pressure measuring device comprising a pair of lead wires . A pressure measuring device for measuring a rapidly changing high pressure generated by an explosion phenomenon in water, the pressure-sensitive element having a thickness of 20 μm to 20 mm made of a copolymer of vinylidene fluoride and fluoroalkylene, The pressure-sensitive element includes a pair of electrodes joined to both sides of the pressure-sensitive element, and a pair of lead wires connected to the electrode. The pressure-sensitive element and the electrode are electrically insulating and elastic, and transmit pressure. pressure measuring device is coated with a resin coating layer as possible. The pressure measuring device according to claim 1, wherein the container is made of polyamide . The pressure measuring device according to any one of claims 1 to 3, wherein in the copolymer, vinylidene fluoride has a monomer ratio of 20 to 95 mol% .

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