JP2005147771A - Tension sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tension sensor in a simple structure for detecting a change in tension precisely with high sensitivity regardless of the operation direction of tension. <P>SOLUTION: The tension sensor 10 comprises a transmission member 16 in which tension F is applied; and a supermagnetostrictive member 14 (tension detection member) for detecting a change in the tension F, based on stress received from the transmission member 16. Then, the transmission member 16 and the supermagnetostrictive member 14 are arranged so that each center axis L coincides, and the line of action of tension coincides with the center axis L of the transmission member 16 and the supermagnetostrictive member 14 by freely rocking a fixing ring 30 on the center axis L as a support. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a tension sensor for detecting a change in tension.

  Conventionally, a tension sensor for detecting a change in tension as shown in FIG. 8 is widely known (see, for example, Patent Document 1).

  This conventionally known tension sensor 1 is fixed to two tension rods 2A, 2B, and is slidable in the sensor chamber 4 of the sensor housing 3, and a spring 6 provided on the plunger 5. A columnar barrier effect sensor 7 disposed between the sensor housing 3 and the sensor housing 3 (see Patent Document 1). The anti-plunger 5 side of the two tension rods 2A and 2B is connected to the tension rod head 8, and the tension rod head 8 is provided with a mounting bolt hole 8A for fixing the tension sensor 1. ing. The tension rod head 8 side of the tension sensor 1 is fixed by an installation bolt (not shown) through an installation bolt hole 8A, and a tension F1 is applied to the sensor housing 3.

  When the tension F1 is applied to the sensor housing 3 and the sensor housing 3 moves, the billiary effect sensor 7 receives an axial compressive force. Therefore, a change in the tension F1 applied to the tension sensor 1 can be detected by detecting a change in the magnetic permeability of the barrier effect sensor 7 based on the compressive force with a detection coil (not shown) or the like.

Japanese translation of PCT publication No. 2002-513475

  However, in this conventionally known tension sensor 1, when the tension F2 is applied in the direction inclined by the angle θ1 with respect to the central axis L1 of the billiary effect sensor 7, the billiary effect sensor 7 has a compressive force and a force accompanying the tension F2. Since torque acts, twist occurs in addition to deformation in the direction of the central axis L1. For this reason, there is a problem in that the change in tension cannot be accurately detected in the barrier effect sensor 7 and the detection accuracy is deteriorated.

  The present invention has been made to solve such problems, and provides a tension sensor having a simple structure capable of detecting a change in tension with high accuracy and high sensitivity regardless of the direction of action of tension. The purpose is to do.

  As a result of research, the inventors of the present invention have found a tension sensor having a simple structure capable of detecting a change in tension with high accuracy and high sensitivity regardless of the direction of action of tension.

  That is, the above-described object can be achieved by the following present invention.

  (1) A transmission member to which a tension is applied and a tension detection member for detecting a change in the tension based on the stress received from the transmission member are arranged so that the respective central axes coincide with each other; and A tension sensor characterized in that the action line of tension coincides with the central axis of the transmission member and the tension detection member by making it swingable with one point on the central axis as a fulcrum.

  (2) A transmission member to which tension is applied, and a magnetostrictive member for detecting the change in tension as a change in permeability based on the stress received from the transmission member are arranged so that their central axes coincide. In addition, the tension sensor is characterized in that the action line of the tension coincides with the central axis of the transmission member and the magnetostrictive member by making it swingable with one point on the central axis as a fulcrum. .

  (3) The magnetostrictive member is formed in a substantially cylindrical shape, and the transmission member is disposed in contact with one end surface in the axial direction of the magnetostrictive member, and the magnetostriction is based on the plate-like body. The tension sensor according to (2), wherein the tension sensor is constituted by a rod-like body provided so as to penetrate through the inner space of the member.

  (4) The magnetostrictive member has a cylindrical shape, and the plate-like body in the transmission member has a disk shape having the same outer diameter as one end surface in the axial direction of the magnetostrictive member. (3) The tension sensor described in the above.

  (5) The tension sensor according to any one of (2) to (4), wherein a preload can be applied in an axial direction of the magnetostrictive member.

  (6) The tension sensor according to any one of (2) to (5), wherein the magnetostrictive member is a giant magnetostrictive member made of a giant magnetostrictive element.

  The tension sensor having a simple structure according to the present invention has an excellent effect that a change in tension can be detected with high accuracy and high sensitivity regardless of the direction of action of tension.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIGS. 1 and 2, a tension sensor 10 according to an embodiment of the present invention includes a box-shaped case 12 made of a non-magnetic material, and the case 12 is centered on L in the figure. A cylindrical giant magnetostrictive member 14 as a shaft, a transmission member 16 coaxially disposed in the inner space 14A of the giant magnetostrictive member 14, a disc spring 18 disposed at the top of the transmission member 16, A pickup coil 20 disposed so as to surround the outer periphery of the giant magnetostrictive member 14 is accommodated.

  A preload screw 22 for applying a preload in the axial direction L of the giant magnetostrictive member 14 via a disc spring 18 is attached to the upper portion of the case 12, thereby applying to the giant magnetostrictive member 14. The preload can be adjusted. The preload by the preload screw 22 is set to an optimum value according to the specifications of the tension sensor 10.

  Further, an attachment ring 24 is provided on the upper portion of the preload screw 22, and this attachment ring 24 is further located on the central axis L of the giant magnetostrictive member 14 and the transmission member 16 via a wire 26, and Are connected to a fixing ring 30 fixed to the base plate 28. That is, the case 12 has a swingable structure with the fixing ring 30 positioned on the central axis L as a fulcrum.

  The transmission member 16 includes a plate-like body 16A having a disc shape and a rod-like body 16B. The plate-like body 16A is disposed in contact with the one end face 14B in the axial direction L of the giant magnetostrictive member 14, and has the same outer diameter as the one end face 14B. Further, the rod-like body 16B is provided penetrating through the inside space 14A of the giant magnetostrictive member 14 with the plate-like body 16A as a base end, and the distal end thereof protrudes outside the case 12.

  The giant magnetostrictive member 14 uses a giant magnetostrictive element as a material. Here, the “super magnetostrictive element” is a magnetostrictive element made of a powder sintered alloy or a single crystal alloy containing a rare earth element and / or a specific transition metal as a main component (for example, terbium, dysprosium, iron, etc.). Say. This (super) magnetostrictive element has a characteristic that causes a large change in magnetic permeability (or residual magnetization) when deformed by receiving stress from the outside. That is, when the (super) magnetostrictive element is stretched by receiving a tensile force, the magnetic permeability is increased, and when the (super) magnetostrictive element is contracted by a compressive force, the magnetic permeability is decreased.

  The pickup coil 20 can detect a change in the magnetic permeability or the residual magnetization caused by the deformation of the giant magnetostrictive member 14 as a change in the inductance of the pickup coil 20.

  Next, the operation of the tension sensor 10 will be described.

  When the tension F is applied to the transmission member 16 of the tension sensor 10, a compressive force in the axial direction L is applied to the one end surface 14B of the giant magnetostrictive member 14 via the plate-like body 16A of the transmission member 16. The super magnetostrictive member 14 is deformed by the compressive force from the transmission member 16, and the super magnetostrictive member 14 expands in the radial direction and contracts in the axial direction. As a result, the volume of the giant magnetostrictive member 14 occupying the inner space of the pickup coil 20 changes, and the permeability or residual magnetization of the giant magnetostrictive member 14 changes. Therefore, a change in the tension F applied to the transmission member 16 can be detected by detecting this change in magnetic permeability or residual magnetic susceptibility as a change in inductance value of the pickup coil 20.

  Further, as shown in FIG. 3, even when the tension F is applied to the tension sensor 10 in the direction inclined by the angle θ with respect to the vertical direction V, the giant magnetostrictive member 14 and the transmission member in the case 12 are applied. 16 has a structure that is swingable with the fixing ring 30 as a fulcrum, so that the line of action of the tension F always coincides with the central axis L of the giant magnetostrictive member 14 and the transmission member 16. Therefore, the tension F can be transmitted to the giant magnetostrictive member 14 as a compressive force in the direction of the central axis L regardless of the direction of action of the tension F.

  As shown in FIG. 4, the inventors of the present invention prepare a tension sensor 40 fixed in the vertical direction V, and then apply a tension F along the vertical direction V (FIG. 4A). The tension F and the pickup coil in the case of applying the tension F in the direction inclined by the angle θ with respect to the vertical direction V (Comparative Example 2 in FIG. 4B) as in FIG. Data on the relationship with the inductance value I of 20 was collected and compared with the tension sensor 10. In this example, an element having an outer diameter of 10 mm, an inner diameter of 6 mm, and a length of 6 mm was used as the giant magnetostrictive member 14, and the angle θ with respect to the vertical direction V was set to 19 degrees.

  As a result, as shown in FIG. 5, when the tension F is applied in the direction of the angle θ in the tension sensor 40 (Comparative Example 2), the tension F is applied along the vertical direction V as in Comparative Example 1. Compared with the case, the detection accuracy of the tension F was remarkably lowered. On the other hand, when the tension F was applied in the direction of the angle θ in the tension sensor 10 according to the present embodiment (Example), it was confirmed that the detection accuracy substantially equal to that of Comparative Example 1 could be secured.

  According to the tension sensor 10 according to the present invention, the transmission member 16 to which the tension F is applied and the giant magnetostrictive member 14 (for detecting a change in the tension F based on the compression force (stress) received from the transmission member 16. The tension detection member) is arranged so that the respective central axes L coincide with each other, and the fixed ring 30 on the central axis L is swingable about the fulcrum, so that the action line of the tension F is transmitted. Since it is made to coincide with the central axis L of the member 16 and the giant magnetostrictive member 14, the tension F is transmitted to the giant magnetostrictive member 14 as a compressive force in the direction of the central axis L by the transmission member 16 regardless of the acting direction of the tension F. The change in tension can be detected with high accuracy and high sensitivity.

  In particular, the substantially cylindrical giant magnetostrictive member 14, the plate-like body 16A disposed in contact with the one end face 14B in the axial direction L of the giant magnetostrictive member 14, and the giant magnetostrictive member 14 with the plate-like body 16A as a base end. And the transmission member 16 constituted by the rod-like body 16B provided so as to penetrate through the inner space 14A of the inner space 14A. Therefore, the structure is extremely simple and easy to manufacture, and the transmission member 16 is applied. The applied tension can be uniformly transmitted to the giant magnetostrictive member 14 without deviation, and a change in tension can be detected with higher accuracy and sensitivity.

  The giant magnetostrictive member 14 has a cylindrical shape, and the plate-like body 16A of the transmission member 16 has a disk shape having the same outer diameter as the axial end surface 14B of the giant magnetostrictive member 14. The tension applied to the magnetostrictive member 14 can be efficiently transmitted to the giant magnetostrictive member 14, and the detection of a change in tension is further enhanced.

  Further, since the preload can be applied in the axial direction L of the giant magnetostrictive member 14 by the preload screw 22, if the preload is adjusted according to the specifications of the tension sensor 10, the tension detection characteristics (linearity and hysteresis) Characteristics) can be optimally designed.

  The tension sensor according to the present invention is not limited to the structure, shape, and the like of the tension sensor 10 according to the above-described embodiment. For example, the giant magnetostrictive member 14 is not in a cylindrical shape but in a rectangular tube shape or the like. Also good. Further, the plate-like body 16A of the transmission member 16 is not limited to a disk-shaped member having the same outer diameter as the axial end surface 14B of the giant magnetostrictive member 14. Further, when it is not necessary to increase the detection sensitivity so much, a magnetostrictive member made of a magnetostrictive element may be applied instead of the super magnetostrictive member 14, and when a desired tension detection characteristic can be obtained, a preload is applied. The screw 22 may not be attached.

  Further, the tension detection member for detecting the change in the tension F based on the stress received from the transmission member 16 is not limited to the (super) magnetostrictive member, and the tension sensor includes the transmission member to which the tension is applied. The tension detection members for detecting the change in tension based on the stress received from the transmission member are arranged so that the respective central axes coincide with each other, and swing about one point on the central axis as a fulcrum It is only necessary that the action line of the tension coincides with the central axis of the transmission member and the tension detection member.

  Therefore, for example, a substantially cylindrical conductive rubber 52 may be applied as the tension detecting member instead of the giant magnetostrictive member 14 as in the tension sensor 50 shown in FIG. An upper end electrode 54A and a lower end electrode 54B are disposed at the upper end and the lower end of the conductive rubber 52, and a predetermined current is passed through the conductive rubber 52, and a change in the current value is detected by the current detection means 56. It has a possible structure.

  In the tension sensor 50, when a tension F is applied to the transmission member 16, a compressive force in the axial direction L is applied to the upper end of the conductive rubber 52 via the plate-like body 16 </ b> A of the transmission member 16. The compressive force from the transmission member 16 causes deformation (distortion) in the conductive rubber 52, and the resistance value of the conductive rubber 52 changes. Therefore, as shown in FIG. 7, by detecting this change in resistance value as a change in current value in the current detection means 56, a change in the tension F applied to the transmission member 16 can be detected.

  Also in the tension sensor 50, similarly to the above-described tension sensor 10, the transmission member 16 transmits the tension F to the conductive rubber 52 as a compressive force in the direction of the central axis L, regardless of the direction in which the tension F acts. The tension change can be detected with high accuracy and high sensitivity.

  In the tension sensor 10 according to the above embodiment, the pickup coil 20 is applied as detection means for detecting a change in the magnetic permeability of the giant magnetostrictive member 14, but the present invention is not limited to this. Therefore, for example, a magnetoresistive effect element such as MR, GMR, or TMR or a Hall element may be applied as the detecting means, and a change in magnetic permeability may be detected as a change in electromotive force of the magnetoresistive effect element or the Hall element.

Schematic side sectional view showing a tension sensor according to an embodiment of the present invention Schematic cross-sectional view along line II-II in FIG. Schematic side sectional view showing a state in which a tension in a predetermined direction is applied to the tension sensor in FIG. Schematic side sectional view showing a comparative example with the tension sensor in FIG. FIG. 1 and FIG. 4 are graphs showing the relationship between the tension applied to the tension sensor and the inductance value of the pickup coil. Schematic side sectional view showing a tension sensor according to another embodiment of the present invention. Table showing the relationship between the tension applied to the tension sensor in FIG. 6 and the strain rate, resistance, and current. Schematic side sectional view showing a conventional tension sensor

Explanation of symbols

F, F1, F2 ... tension L, L1 ... central axis I ... inductance θ, θ1 ... angle 1, 10, 40, 50 ... tension sensor 2A, 2B ... tension rod 3 ... sensor housing 4 ... sensor chamber 5 ... plunger 6 ... Spring 7 ... Bilder effect sensor 8 ... Tensile rod head 8A ... Installation bolt hole 12 ... Case 14 ... Giant magnetostrictive member 14A ... Inner space 14B ... Axial end face 16 ... Transmission member 16A ... Plate-like body 16B ... Rod-like body 18 ... Conical spring DESCRIPTION OF SYMBOLS 20 ... Pick-up coil 22 ... Preload screw 24 ... Mounting ring 26 ... Wire 28 ... Base plate 30 ... Fixing ring 52 ... Conductive rubber 54A ... Upper end electrode 54B ... Lower end electrode 56 ... Current detection means

Claims (6)

  A transmission member to which tension is applied and a tension detection member for detecting a change in the tension based on the stress received from the transmission member are arranged so that the respective central axes coincide with each other, and the central axis A tension sensor characterized in that the action line of tension coincides with the central axis of the transmission member and the tension detection member by making it swingable with the upper point as a fulcrum.   A transmission member to which tension is applied, and a magnetostrictive member for detecting the change in tension based on the stress received from the transmission member as a change in permeability, so that the respective central axes coincide, and A tension sensor characterized in that the action line of tension coincides with the central axis of the transmission member and the magnetostrictive member by making it swingable with one point on the central axis as a fulcrum. In claim 2,
The magnetostrictive member is formed into a substantially cylindrical shape, and the transmission member is disposed in contact with one end surface in the axial direction of the magnetostrictive member, and the inner side of the magnetostrictive member with the plate-like body as a base end A tension sensor characterized by comprising a rod-like body provided through the space. In claim 3,
The tension sensor according to claim 1, wherein the magnetostrictive member has a cylindrical shape, and the plate-like body of the transmission member has a disc shape having the same outer diameter as one axial end surface of the magnetostrictive member. In any of claims 2 to 4,
A tension sensor characterized in that a preload can be applied in the axial direction of the magnetostrictive member. In any of claims 2 to 5,
A tension sensor comprising the magnetostrictive member made of a giant magnetostrictive member made of a giant magnetostrictive element.

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