JP5137807B2 - thermocouple - Google Patents

Description

    The present invention relates to a thermocouple that can be used in an environment in which bending, expansion and contraction, etc. occur repeatedly.

    In general, a thermocouple joins the tip of two types of metal wires to form a hot junction, and obtains a thermoelectromotive force based on the temperature difference between the tip and rear ends of these metal wires. The temperature at the contact is measured, and the temperature can be easily and accurately measured in various environments. Here, among the above-mentioned environments, the environment in which bending, expansion and contraction, etc. are repeatedly applied to the thermocouple is extremely severe for the thermocouple because large bending stress, tensile stress, etc. act repeatedly on the metal wire. May break or break.

For example, in the one described in Patent Document 1 below, a tip including a hot junction of a thermocouple is inserted into a resin flow path provided in a cylinder so as to be orthogonal to the flow direction of the resin. The temperature of the resin flowing in the channel is measured by a thermocouple. At this time, the tip of the thermocouple protruding into the resin flow path receives a force from the high viscosity resin and the resin Bends in an arc in the flow direction.
JP-A-9-57823

    And when such a thermocouple flows in the opposite direction, the bending direction also changes in the opposite direction, and when the resin flow rate changes, the bending amount also changes. There was a problem that it was repeatedly deformed and could be broken or broken. In order to suppress such a situation, it is conceivable to use a structure in which a plurality of single wires are twisted as the metal wire of the thermocouple, but it is difficult to obtain sufficient durability even with this.

  An object of the present invention is to provide a thermocouple that can be used for a long period of time in an environment in which bending, expansion and contraction, etc. occur repeatedly.

    The purpose of this is, firstly, a pair of central cords formed by bundling a plurality of filaments made of organic fibers, and extending along one central cord, and the spiral central axis is coaxial with the central line of the central cord An anode metal body made of a spirally deformed metal, and extending along the other central cord, the spiral central axis is deformed into a spiral coaxial with the center line of the central cord, and the tip is This can be achieved by a thermocouple that is joined to the tip of the anode metal body to form a hot junction and that includes a cathode metal body made of a metal different from the anode metal body.

  Second, one central cord formed by bundling a plurality of filaments made of organic fibers, and extending along the central cord, the spiral central axis is transformed into a spiral shape coaxial with the central line of the central cord. An anode metal body made of a metal, extending along the center cord while being insulated from the anode metal body, the spiral center axis being deformed into a spiral shape coaxial with the center line of the center cord, and the tip thereof being This can be achieved by a thermocouple that is joined to the tip of the anode metal body to form a hot junction and that includes a cathode metal body made of a metal different from the anode metal body.

  In the inventions according to claims 1 and 2, the anode and cathode metal bodies made of different metals extend along the center cord while being deformed in a spiral shape, so that the anode is generated when the thermocouple is bent. The amount of deformation (deflection) of the cathode metal body is smaller than that when the anode and cathode metal body extend linearly along the center line of the center cord. Fatigue failure is suppressed.

  In addition, when expansion and contraction is applied to the thermocouple, the expansion and contraction is absorbed by changing the helical pitch of the anode and cathode metal bodies, so that the situation where the anode and cathode metal bodies break due to tension or buckling is suppressed. The Furthermore, when the twist is applied to the thermocouple, the winding of the spiral of the anode and the cathode metal body is loosened or tightened so that the twist is absorbed. It is suppressed.

  On the other hand, the central cord, which is a part of the thermocouple, is formed by bundling a plurality of filaments made of organic fibers, so that the bending rigidity and tensile rigidity of the entire thermocouple are reduced. It is easy to follow the expansion and contraction, deforms and expands, and the breakage is effectively suppressed. For this reason, the thermocouple can be used for a long time even in an environment in which bending, expansion and contraction, etc. occur repeatedly. In addition, since the center cord has a certain degree of bending rigidity and tensile rigidity, shape stability, bending strength, and tensile strength are ensured during manufacture, transportation, laying, measurement, etc. of the thermocouple, and , Handling becomes easy.

  Further, if configured as described in claim 3, the thicknesses of the anode and cathode metal bodies are reduced, and the distance from the neutral surface to the front and back surfaces is shortened. As a result, the thermocouple is bent. When applied, the bending stress generated in the anode and cathode metal bodies is reduced, and these fatigue fractures are further suppressed. In addition, since the metal foil only needs to be spirally wound around the center cord, the manufacturing operation is facilitated.

  Here, when a plurality of filaments constituting the center cord extend linearly along the center line of the center cord, when bending is applied to the thermocouple, the center of curvature is closer to the center of curvature than the neutral plane of the bend. There is no escape space for the compressive strain generated in the filament, and buckling called a kink band occurs, which may lead to a decrease in the strength of the filament and progress to breakage. However, when twisting is applied to the center cord as described in claim 4, each filament is inclined with respect to the center line of the center cord. Therefore, when the filament is subjected to the compressive strain described above, the inclination angle changes. Thus, the compressive strain is absorbed, thereby suppressing the occurrence of buckling (kink band).

  Furthermore, when the twist coefficient Nt is in the range of 0.20 to 0.65 as described in claim 5, the tensile strength of the center cord is set to an appropriate value, and the shape stability of the thermocouple is reliably maintained while being compressed. The occurrence of buckling based on strain can be strongly suppressed. Moreover, if comprised as described in Claim 6, the tensile rigidity of a center code | cord | chord will further improve, Thereby, the long-term use of a thermocouple is attained.

  Furthermore, if it comprises as described in Claim 7, when the thermocouple bends, the abrasion amount of the anode and cathode metal body which consists of a filament and metal foil will reduce, and abrasion of these anode and cathode metal body is effective. Can be suppressed. Further, if configured as described in claim 8, stress based on bending, expansion and contraction, etc. is dispersed, and long-term use can be easily achieved. Can continue to be used. Furthermore, if it comprises as described in Claim 9, even when a measurement environment will become high temperature, it can be used without a problem.

Embodiment 1 of the present invention will be described below with reference to the drawings.
1 and 2, reference numeral 11 denotes a conveyor device extending in the front-rear direction. The conveyor device 11 includes a support frame 12 extending in the front-rear direction, and rollers 13 rotatably supported on front and rear ends of the support frame 12, respectively. An endless belt-like conveyor belt 14 made of vulcanized rubber as a measurement object spanned between these rollers 13, and a motor for running the conveyor belt 14 by applying a driving rotational force to any of the rollers 13. It is composed of

  Such a conveyor belt 14 is deformed when an article is placed thereon, or is elastically deformed by reversing the traveling direction of the roller 13 so that the temperature rises due to self-heating. Reference numerals 19 denote rollers fixed to the support shafts 20 of the rollers 13 projecting outward from the support frame 12, and the diameters of these rollers 19 are the same as those of the rollers 13. A narrow belt 21 extending parallel to the conveyor belt 14 is stretched between these rollers 19, and the narrow belt 21 runs synchronously at the same speed in the same direction as the conveyor belt 14.

  24 is a thermocouple for measuring the internal temperature at the center in the width direction of the conveyor belt 14, and the front end side of the thermocouple 24 including the temperature measuring unit 25 provided at the front end of the thermocouple 24 is connected to the conveyor belt 14. Buried. As a result, a portion of the thermocouple 24 embedded in the conveyor belt 14 is repeatedly bent, stretched, twisted, and the like due to the above-described deformation of the conveyor belt 14.

  The thermocouple 24 is pulled out from one side surface of the conveyor belt 14, and a rear end is connected to a transmitter 26 fixed at one place on the narrow belt 21. Then, the internal temperature of the conveyor belt 14 measured by the thermocouple 24 is put on the radio signal as temperature data from the transmitter 26 and sent to a temperature measuring device installed at a location away from the conveyor device 11. .

  2, 3, and 4, the thermocouple 24 has a pair of center cords 28 and 29 configured by bundling a plurality of filaments 27, here, seven filaments 27, and the filaments 27 of the center cords 28 and 29 are organic. Consists of fibers. In this way, if the central cords 28 and 29, which are part of the thermocouple 24, are configured by bundling a plurality of filaments 27 made of organic fibers (which are arranged while being densely packed), the thermocouple is a single wire or a stranded wire. Compared to the case where only the thermocouple 24 is configured, the bending rigidity and tensile rigidity of the entire thermocouple 24 are lowered.

  As a result, it is easily deformed and stretched following any direction of bending and expansion and contraction, and breakage of the thermocouple 24 is effectively suppressed. For this reason, the thermocouple 24 can be used for a long time even in an environment in which bending, expansion and contraction, etc. occur repeatedly. Since the center cords 28 and 29 have a certain degree of bending rigidity and tensile rigidity, they have shape stability, bending strength, and tensile strength at the time of manufacturing, transporting, laying, and measuring the thermocouple 24. Secured and easy to handle. Here, as the above-mentioned organic fibers, for example, polyester, acrylic, polyurethane, and the like can be used. Particularly, when the measurement environment becomes high temperature, nylon having a melting point of 200 ° C. or higher, polyethylene terephthalate Aromatic polyamides are preferred because they can be used without problems.

  Further, the filament 27 constituting the center cords 28 and 29 may extend linearly along the center line L of the center cords 28 and 29. However, as in this embodiment, the filaments 27 and 29 It is preferable to extend each filament 27 in a spiral shape by applying twist to the filament. The reason is as follows. That is, when the filament 27 of the center cords 28 and 29 extends linearly along the center line L as described above, when the thermocouple 24 is bent, it is closer to the center of curvature than the neutral plane of the bend. There is no escape space for the compressive strain generated in the filament 27, and buckling called a kink band occurs, which may lead to a decrease in the strength of the filament 27 and progress to breakage.

  However, when twisting is applied to the center cords 28 and 29 as described above, the filaments 27 are inclined with respect to the center line L of the center cords 28 and 29 because the filaments 27 extend spirally. This is because when the compressive strain is received, the inclination angle is changed and the compressive strain is absorbed, whereby the occurrence of buckling (kink band) in the filament 27 can be effectively suppressed.

Here, when the number of twists of the center cords 28 and 29 is T (times / 10 cm), the specific gravity is ρ, and the total decitex number, so-called fineness (dtex) is D, the following formula is given: Nt = T × {0.125 × ( D / 2) × 1 / ρ} ^1/2 × 10 ⁻³
It is preferable to set the twist coefficient Nt of the center cords 28 and 29 shown by the following in the range of 0.20 to 0.65.

  The reason is that if the twist coefficient Nt is less than 0.20, buckling based on the above-described compression strain may occur. On the other hand, if it exceeds 0.65, the tensile strength of the center cords 28 and 29 decreases, and the thermoelectric The shape stability of the pair 24 may be insufficient, but if it is within the range of 0.20 to 0.65, the tensile strength of the center cords 28 and 29 is set to an appropriate value, and the shape stability of the thermocouple 24 is adjusted. This is because it is possible to strongly suppress the occurrence of buckling based on the compressive strain while securely holding.

  In this embodiment, the central cords 28 and 29 (filaments 27) are unidirectionally twisted (single twisted), but the intermediate cords are provided by unidirectionally twisting a plurality of filaments. Then, two or more such intermediate cords may be bundled together to give an upper twist in a direction opposite to the lower twist (in the other direction) to constitute a twin twisted central cord. In this way, the tensile rigidity of the center cord is further improved, and thus the thermocouple 24 can be used for a longer period of time.

  32 is an anode metal body made of a metal that extends along one of the center cords, in this embodiment, extends along the center cord 28, and is formed into a spiral shape. The spiral center axis of the anode metal body 32 is the center line L of the center cord 28. And coaxial. 33 is a cathode metal body made of a metal which extends along the other center cord, in this embodiment, extends along the center cord 29, and is deformed in a spiral shape. This cathode metal body 33 is made of a metal different from the anode metal body 32. The center axis of the spiral is coaxial with the center line L of the center cord 29.

  Since the anode and cathode metal bodies 32 and 33 made of different metals extend while spirally deforming along the center cords 28 and 29, respectively, the anode generated when the thermocouple 24 is bent, The amount of deformation (deflection) of the cathode metal bodies 32 and 33 is smaller than when the anode and cathode metal bodies 32 and 33 extend linearly along the center line L of the center cords 28 and 29. Thereby, fatigue failure of the anode and cathode metal bodies 32 and 33 is suppressed.

  Further, when expansion and contraction is applied to the thermocouple 24, the expansion and contraction of the anode and cathode metal bodies 32 and 33 are changed to absorb the expansion and contraction, so that the anode and cathode metal bodies 32 and 33 are tensioned or buckled. This suppresses the situation of breaking. Further, when a twist is applied to the thermocouple 24, the anode and cathode metal bodies 32 and 33 absorb the twist by loosening or tightening the spiral of the anode and cathode metal bodies 32 and 33. The situation of breaking is effectively suppressed.

  Here, as the metals constituting the anode and cathode metal bodies 32 and 33, K (chromel, alumel), J (iron, constantan), T (copper, constantan), E defined in JIS C 1610, respectively. (Chromel, Constantan), etc. or non-JIS standard tungsten rhenium (tungsten rhenium alloy containing 5% rhenium, tungsten rhenium alloy containing 26% rhenium), platinel (alloys mainly composed of palladium, platinum and gold) , Alloys mainly composed of gold and palladium).

  The tip portions of the center cords 28 and 29 are brought close to each other, whereby the tip of the anode metal body 32 and the tip of the cathode metal body 33 are brought into contact with each other and then joined together by welding to form a hot junction. However, this hot junction serves as the temperature measuring unit 25 of the thermocouple 24 described above. The thermocouple 24 can measure the temperature in the temperature measuring unit 25 by obtaining the thermoelectromotive force based on the temperature difference between the temperature measuring unit 25 and the rear end.

  Further, in this embodiment, the above-described anode and cathode metal bodies 32, 33 are configured by winding a metal foil 37 around the center cords 28, 29 in a spiral manner. As a result, the thickness of the anode and cathode metal bodies 32 and 33 is reduced, and the distance from the neutral plane of bending to the front and back surfaces of the anode and cathode metal bodies 32 and 33 is shortened. When bending is applied, bending stress generated in the anode and cathode metal bodies 32 and 33 is reduced, and these fatigue fractures can be further suppressed. In addition, since the anode and cathode metal bodies 32 and 33 can be formed simply by winding the metal foil 37 around the center cords 28 and 29 in a spiral shape, the forming operation is facilitated.

  Here, the width of the metal foil 37 constituting the anode and cathode metal bodies 32 and 33 is preferably in the range of 0.20 to 1.00 mm, and the thickness is preferably in the range of 10 to 40 μm. The reason for this is that if it is within such a range, it can be easily wound around the center cords 28 and 29 while preventing breakage when spirally wound, and it can be easily formed into foil. Because it becomes. The anode and cathode metal bodies 32 and 33 are formed by overlapping the metal foil 37 around the center cords 28 and 29 with the width direction side ends being overlapped, or while the width direction side ends are butted together, and further in the width direction. It can be configured by winding spirally while forming a narrow gap between the side ends.

  The anode and cathode metal bodies 32 and 33 have a laminated structure in which the metal foil 37 is wound around two or more layers around the center cords 28 and 29, in this case, only four layers. Thus, when the anode and cathode metal bodies 32, 33 have a laminated structure of the metal foil 37, stress based on bending, stretching, etc. is dispersed in the plurality of metal foils 37, and can be easily used for a long period of time. Even if the metal foil 37 of any layer breaks, the use as the anode and cathode metal bodies 32 and 33 can be continued without any problem.

  Here, when the metal foil 37 is wound, the next metal foil 37 may be wound while being slightly shifted in the width direction with respect to the metal foil 37 that has already been wound as in this embodiment, or a shift is provided. The metal foil 37 having two or more layers may be overlapped in advance, and the overlapped metal foil 37 may be spirally wound around the center cords 28 and 29. Good.

  Further, the winding direction of the above-described anode and cathode metal bodies 32, 33 is preferably the same as the twisting direction of the filament 27 located on the outermost side of the center cords 28, 29 as in this embodiment. The reason for this is that when the thermocouple 24 is bent as described above, the amount of abrasion between the filament 27 and the anode and cathode metal bodies 32 and 33 when the thermocouple 24 is bent is reduced. This is because wear can be effectively suppressed.

  The anode and cathode metal bodies described above may be composed of a single wire having a circular cross section. In this case, for example, one of the filaments 27 constituting the center cords 28 and 29 is replaced with the single wire, and the center cord 28 29 may be twisted to deform the single wire into a spiral shape, or the single wire may be wound around the center cords 28 and 29 in a spiral shape.

  40 and 41 are coating layers for covering the center cord 28, the anode metal body 32 and the center cord 29, and the cathode metal body 33 from the outside, respectively. These coating layers 40 and 41 are, for example, fluororesin, polyester, heat-resistant vinyl, etc. It is made of an insulating material that can be bent easily. Note that the coating layers 40 and 41 are omitted at the tip portions of the anode and cathode metal bodies 32 and 33, so that the tips of the anode and cathode metal bodies 32 and 33 are joined to each other as described above. Can do.

  In addition to the conveyor belt 14, the thermocouple 24 can be suitably used for measuring the internal temperature of an object that is repeatedly elastically deformed, such as a buffer rubber block, a rubber crawler, and the like. Alternatively, the surface temperature of the object can be measured by fixing the temperature measuring unit 25 of the thermocouple 24 to the surface of the object that is repeatedly displaced using an adhesive or the like.

    5 and 6 are views showing Embodiment 2 of the present invention. In this embodiment, the central cord 44 of the thermocouple 24 is not a pair as in the first embodiment, but only one, but the structure is the same as in the first embodiment, and is composed of a plurality of organic fibers. The filament 27 is configured by bundling and is provided with a single twist. In addition, the anode metal body 45 is formed by winding a metal foil 46 spirally around the central cord 44 in two or more layers (here, only two layers). An anode metal body 45 made of a spirally deformed metal extending along the center cord 44 and having a spiral center axis coaxial with the center line L of the center cord 44 is disposed.

  Further, an insulating layer 49 surrounding the anode metal body 45 from the outside is disposed around the center cord 44, and this insulating layer 49 is wider than the metal foil 46 of the anode electrode body 45 and is an insulating material that is easily bent, for example, An insulating film 50 made of a fluororesin is formed by spirally wrapping the width direction side end portions thereof. Around the insulating layer 49, a cathode metal body 52 made of a metal different from the anode metal body 45 and insulated from the anode metal body 45 by the insulating layer 49 is disposed.

  Here, the cathode metal body 52 is constituted by winding a metal foil 53 spirally around the center cord 44 (insulating layer 49) in two or more layers (here, only two layers). Around the cord 44, a cathode metal body 52 made of a metal deformed in a spiral shape extending along the central cord 44 and having a spiral central axis coaxial with the center line L of the central cord 44 is disposed. The tips of the anode metal body 45 and the cathode metal body 52 are joined to each other by removing the insulating layer 49 interposed therebetween to form a hot junction (temperature measuring unit 25). Reference numeral 56 denotes a coating layer similar to the coating layers 40 and 41 described above, which covers the central cord 44, the anode, the cathode metal bodies 45 and 52, and the insulating layer 49 from the periphery.

  Thus, if the anode and cathode metal bodies 45 and 52 are provided around the center cord 44 with the insulating layer 49 interposed therebetween, the structure of the thermocouple 24 is simplified, and the carrying work, Handling in laying work etc. becomes easy. In this embodiment, the anode metal body 45 is arranged radially inside and the cathode metal body 52 is arranged radially outside. In the present invention, the cathode metal body is arranged radially inside and the anode metal body anode outside. You may make it arrange | position a metal body. Other configurations and operations are the same as those of the first embodiment.

    Next, test examples will be described. For this test, a conventional thermocouple 1 including a pair of anode and cathode metal wires each having a diameter of 0.1 mm and a pair of anode and cathode metal wires configured by bundling 30 single wires having a diameter of 0.1 mm are provided. Conventional thermocouple 2, a pair of central cords made by bundling seven filaments, and metal foil (width 0.35mm, thickness 23μm) around each central cord, spirally in four layers, 20 times per 10mm The implementation thermocouples 1-5 provided with the anode comprised by winding and a cathode metal body were prepared.

  Here, the anode metal wire and the anode metal body were both made of copper, and the cathode metal wire and the cathode metal body were both made of constantan (55% copper and 45% nickel). Further, the material of the center cord, the fineness (dtex), the twisted structure, the number of twists (times / 10 cm), and the twist coefficient Nt in the thermocouples 1 to 5 are as shown in Table 1 below.

  Next, the conventional thermocouples 1 and 2 and the implementation thermocouples 1 to 5 as described above are extended in the longitudinal direction at the center in the thickness direction of the unvulcanized rubber sheet having a length of 50 cm, a width of 5 cm, and a thickness of 1 cm. The test sheet was manufactured by vulcanization. Next, after the above test sheet was stretched over a free rotating pulley having a diameter of 20 mm, the rear end of the thermocouple protruding from the test sheet was connected to a measuring instrument.

Next, while applying a load of 100 N to the test sheet, the test sheet was reciprocated 5 × 10 ⁵ times in the longitudinal direction (the number of bendings was twice this), and the temperature in the temperature measuring unit was measured with a thermocouple. As shown in Table 1, the results are as follows. As shown in Table 1, the conventional thermocouples 1 and 2 break the anode or cathode metal wire (body) at the beginning of the test, and the test thermocouple 5 late in the test, making it impossible to measure the temperature. However, all of the implementation thermocouples 1 to 4 were able to measure the temperature to the end.

  Next, the thermocouples 1 to 5 for which the above-described bending test was completed were taken out of the test sheet and subjected to a tensile test to obtain the breaking strength. Thereafter, the breaking strength after the end of the test was divided by the initial breaking strength obtained in advance before the start of the test, and then multiplied by 100 to obtain the strength retention as an index of fatigue. The results are shown in Table 1.

  The present invention can be applied to the industrial field of thermocouples that can be used in an environment in which bending, expansion and contraction, etc. occur repeatedly.

It is a partially broken top view of the conveyor belt vicinity in which the thermocouple which shows Embodiment 1 of this invention was installed. It is a front view of the thermocouple with a part broken. It is an enlarged front view of a thermocouple partially broken and developed. FIG. 4 is a cross-sectional view taken along the arrow I-I in FIG. 3. It is a front view of the thermocouple by which a part which shows Embodiment 2 of this invention was fractured | ruptured. It is an enlarged front view of a thermocouple partially broken and developed.

Explanation of symbols

24 ... Thermocouple 27 ... Filament
28, 29 ... Center code 32 ... Anode metal body
33 ... Cathode metal body 37 ... Metal foil
44 ... Center code 45 ... Anode metal body
52 ... Cathode metal body L ... Center line

Claims (9)

    A pair of center cords formed by bundling a plurality of filaments made of organic fibers, and a spirally deformed metal extending along one center cord and having a spiral center axis coaxial with the center line of the center cord. An anode metal body that extends along the other central cord, the spiral central axis is deformed into a spiral shape that is coaxial with the center line of the central cord, and the tip is joined to the tip of the anode metal body. A thermocouple characterized by comprising a hot metal junction and a cathode metal body made of a metal different from the anode metal body.     One central cord formed by bundling a plurality of filaments made of organic fibers, and a spirally deformed metal extending along the central cord and having a spiral central axis coaxial with the central cord centerline An anode metal body that extends along the center cord while being insulated from the anode metal body, and has a spiral center axis that is coaxially deformed with the center line of the center cord, and the tip of the anode metal body A thermocouple characterized by comprising a cathode metal body made of a metal different from the anode metal body while being joined to the tip to form a hot junction.     The thermocouple according to claim 1 or 2, wherein a metal foil is spirally wound around a central cord as the anode and cathode metal bodies.     The thermocouple according to claim 3, wherein the center cord is twisted. When the number of twists of the center cord is T (times / 10 cm), the specific gravity is ρ, and the total decitex number (dtex) is D, the following formula: Nt = T × {0.125 × (D / 2) × 1 / ρ} ^1/2 × 10 ^-3
The thermocouple according to claim 4, wherein the twist coefficient Nt of the center cord indicated by is set within a range of 0.20 to 0.65.     6. The thermoelectric device according to claim 4, wherein the center cord is formed by imparting an upper twist in a direction opposite to the lower twist to two or more intermediate cords formed by imparting a lower twist to a plurality of filaments. versus.     The thermocouple according to any one of claims 4 to 6, wherein the winding direction of the anode and cathode metal bodies is the same as the twist direction of the filament located on the outermost side of the center cord.     The thermocouple according to any one of claims 4 to 7, wherein two or more layers of the metal foil are wound around a center cord to form a laminated structure of anode and cathode metal bodies.     The thermocouple according to any one of claims 4 to 8, wherein an organic fiber having a melting point of 200 ° C or higher is used as the filament constituting the center cord.

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