JP2005274159A - Torque sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque sensor capable of reducing cost and improving detection sensitivity, and simultaneously preventing beforehand breakage or the like of a device and improving the strength against a torque. <P>SOLUTION: This torque sensor 10 has a constitution having an approximately cylindrical super-magnetostrictive rod 14 equipped with a super-magnetostrictive member and having one end 14A fixed to a base 12, a shaft 18 disposed through an inside space of the super-magnetostrictive rod 14 and equipped with an upper plate 16 having a larger diameter than the inner diameter of the super-magnetostrictive rod 14 on the other end 14B side of the super-magnetostrictive rod 14, a spring 20 for energizing the upper plate 16 of the shaft 18 to the other end 14B side of the super-magnetostrictive rod 14, and a detection coil 22 capable of detecting the change of the magnetic permeability or the residual magnetizing quantity of the super-magnetostrictive rod 14 based on deformation of the super-magnetostrictive rod 14. The torque of the shaft 18 can be transferred to the super-magnetostrictive rod 14 by a frictional force working between the upper plate 16 and the super-magnetostrictive rod 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a torque sensor using a magnetostrictive element.

  Conventionally, a torque sensor that can detect a change in torque by using a stress magnetic effect of a magnetostrictive element is widely known. Such a torque sensor is applied to detection of a rotational operation force of an automobile handle, and a predetermined strength is required.

  For example, the torque sensor 1 shown in FIG. 10 is configured by bonding and fixing a magnetostrictive alloy ribbon 2 having a plurality of holes 2 </ b> A to the outer periphery of the shaft 3. In this torque sensor 1, the strength is improved by dispersing the torque in the plurality of holes 2 </ b> A of the magnetostrictive alloy ribbon 2 so that the torque of the shaft 3 is not concentrated in one place.

JP-A-7-113702

  However, while this conventionally known torque sensor 1 can secure a certain degree of strength against the torque of the shaft 3, it is difficult to process and bond the magnetostrictive alloy ribbon 2 and increases the cost. In addition, the change in magnetic properties in the magnetostrictive alloy ribbon 2 is small, and there is a limit to the improvement of detection sensitivity.

  The present invention has been made to solve such problems, and while being able to reduce costs and improve detection sensitivity, at the same time, it is possible to prevent damage to the device and to prevent torque. It aims at providing the torque sensor which can improve the intensity | strength with respect to.

  As a result of earnest research, the inventor of the present invention is able to reduce costs and improve detection sensitivity, but at the same time, can prevent damage to the device and the like, and can improve the strength against torque I found a sensor.

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

  (1) A substantially cylindrical magnetostrictive rod having a magnetostrictive member and having one end fixed to a fixed portion, and disposed through the inner space of the magnetostrictive rod, and the other end side of the magnetostrictive rod A shaft provided with a protruding portion having a diameter larger than the inner diameter of the magnetostrictive rod, an elastic member for biasing the protruding portion of the shaft toward the other end of the magnetostrictive rod, and based on deformation of the magnetostrictive rod. Detecting means capable of detecting a change in permeability or residual magnetization amount of the magnetostrictive rod, and the torque of the shaft is caused by a frictional force acting between the protruding portion of the shaft and the magnetostrictive rod. A torque sensor characterized in that transmission to the magnetostrictive rod is possible.

  (2) The torque sensor according to (1), wherein the urging force of the elastic member is adjustable.

  (3) The torque sensor according to (1) or (2), wherein a predetermined bias magnetic field is applied to the magnetostrictive rod.

  (4) The torque sensor according to any one of (1) to (3), wherein the protruding portion of the shaft has a larger diameter than the outer diameter on the other end side of the magnetostrictive rod.

  (5) The torque sensor according to any one of (1) to (4), wherein an elastic sheet is interposed between the protruding portion of the shaft and the magnetostrictive rod.

  (6) The detection means includes a detection coil disposed so as to surround the outer periphery of the magnetostrictive rod, and detects a change in permeability or residual magnetization of the magnetostrictive rod as a change in inductance value of the detection coil. The torque sensor according to any one of (1) to (5), wherein the torque sensor is configured as described above.

  (7) The detection means includes a Hall element, and detects a change in magnetic permeability or residual magnetization of the magnetostrictive rod as a change in electromotive force of the Hall element. The torque sensor according to any one of the above.

  (8) The detection means includes a magnetoresistive effect element, and detects a change in magnetic permeability or residual magnetization of the magnetostrictive rod as a change in electromotive force of the magnetoresistive effect element. The torque sensor according to any one of (5) to (5).

  (9) The torque sensor according to any one of (1) to (8), wherein the magnetostrictive member is a giant magnetostrictive member made of a giant magnetostrictive element.

  According to the torque sensor of the present invention, it is possible to reduce costs and improve detection sensitivity, but at the same time, it is possible to prevent damage to the device and to improve strength against torque. Has an effect.

  The torque sensor according to the present invention includes a substantially cylindrical magnetostrictive rod having a magnetostrictive member, one end of which is fixed to a fixed portion, an inner space of the magnetostrictive rod, and the magnetostrictive rod. A shaft provided with a protrusion having a diameter larger than the inner diameter of the magnetostrictive rod on the other end of the rod; an elastic member for biasing the protrusion on the shaft toward the other end of the magnetostrictive rod; and the magnetostriction Detecting means capable of detecting a change in permeability or residual magnetization of the magnetostrictive rod based on deformation of the rod, and the torque of the shaft is between the protruding portion of the shaft and the magnetostrictive rod. The above-mentioned problem is solved by being able to transmit to the magnetostrictive rod by the acting frictional force.

  Hereinafter, the torque sensor according to the first and second embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIGS. 1 and 2, the torque sensor 10 according to the first embodiment includes a substantially cylindrical giant magnetostrictive rod 14 having a lower end 14 </ b> A fixed to a base (fixed portion) 12, and the giant magnetostrictive rod 14. And a shaft 18 provided with an upper plate (protrusion) 16 on the upper end 14B side of the giant magnetostrictive rod, and the upper plate 16 of this shaft 18 is connected to the upper end of the giant magnetostrictive rod 14. A spring (elastic member) 20 for biasing to the 14B side, a detection coil (detection means) 22 capable of detecting a change in permeability or residual magnetization of the giant magnetostrictive rod 14 based on deformation of the giant magnetostrictive rod 14, and It is comprised.

  The giant magnetostrictive rod 14 is made of a giant magnetostrictive element. 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 (eg, terbium, dysprosium, iron, etc.). It has the property of producing a large change in magnetic permeability or residual magnetization when deformed by external stress.

  In this example, the upper plate 16 disposed above the shaft 18 is made of a substantially disk-shaped member, and the outer diameter thereof is larger than the outer diameter of the giant magnetostrictive rod 14 on the upper end 14B side. Yes. An elastic sheet 24 is interposed between the upper plate 16 of the shaft 18 and the upper end 14 </ b> B of the giant magnetostrictive rod 14.

  On the other hand, a lower plate 26 having substantially the same shape as the upper plate 16 is disposed below the shaft 18, and the lower plate 26 has a structure that can be moved up and down along the shaft 18 by a nut 28. ing. A spring 20 is contracted between the lower plate 26 and the base 12, and the urging force of the spring 20 can be adjusted by moving the lower plate 26 up and down.

  The detection coil 22 is disposed so as to surround the outer periphery of the giant magnetostrictive rod 14 and can detect a change in the permeability or residual magnetization of the giant magnetostrictive rod 14.

  Next, the operation of the torque sensor 10 according to the first embodiment will be described.

  When torque is applied to the shaft 18, the upper plate 16 fixed to the shaft 18 rotates as the shaft 18 is twisted. Since the upper plate 16 is biased to the upper end 14B side of the giant magnetostrictive rod 14 by the spring 20, the torque of the shaft 18 is caused by the frictional force acting between the upper plate 16 and the giant magnetostrictive rod 14. 14 is transmitted. As a result, the giant magnetostrictive member 14 is twisted (deformed), and the permeability or residual magnetization of the giant magnetostrictive member 14 changes based on this deformation. Therefore, if a change in the magnetic permeability or residual magnetic susceptibility of the giant magnetostrictive member 14 is detected as a change in the inductance value of the detection coil 22, a change in the torque of the shaft 18 can be detected.

  The inventor of the present invention uses the torque measuring device 30 and the LCR meter 32 as shown in FIG. 3 to obtain data on the relationship between the torque applied to the shaft 18 of the torque sensor 10 and the inductance value in the detection coil 22. Collected. In this experiment, a cylindrical giant magnetostrictive rod 14 having an outer diameter of 8 mm, an inner diameter of 5 mm, and a length of 20 mm and a detection coil 22 having a wire diameter of 0.2 mm, a wire type UEW, a number of turns of 200 turns, and a coil length of 0.13 cm are used. It was. Further, a Teflon (registered trademark) sheet was interposed as the elastic sheet 24 between the giant magnetostrictive rod 14 and the upper plate 16.

  In order to make a comparison with the torque sensor 10 according to the first embodiment, the same data was collected for the torque sensor 40 according to the first comparative example as shown in FIG. The torque sensor 40 according to the comparative example 1 is obtained by bonding and fixing a substantially disk-shaped plate 44 fixed to a shaft 42 to the upper end 14B of the giant magnetostrictive rod 14.

  As a result, as shown in FIG. 5, the torque sensor 40 according to Comparative Example 1 gradually increased the torque from 0 (cN · m), and the torque exceeded 80 (cN · m). The giant magnetostrictive rod 14 was damaged.

On the other hand, as shown in FIGS. 6 and 7, the torque sensor 10 according to the first embodiment has a maximum torque value of 50 (cN · m) even when a torque exceeding 80 (cN · m) is applied. The giant magnetostrictive rod 14 was not damaged and was not damaged. This is because a torque exceeding 80 (cN · m) was applied to the shaft 18, but the giant magnetostrictive rod 14 returned to its original shape rather than the frictional force acting between the upper plate 16 and the giant magnetostrictive rod 14. As a result of the increased force, slippage occurred between the upper plate 16 and the giant magnetostrictive rod 14, meaning that no torque exceeding 50 (cN · m) was transmitted to the giant magnetostrictive rod 14. To do. 6 shows data when a preload of 60 kg / cm ² is applied to the giant magnetostrictive rod 14, and FIG. 7 shows data when a preload of 80 kg / cm ² is applied.

  According to the torque sensor 10 according to the first embodiment, the substantially magnetostrictive rod 14 having a giant magnetostrictive member and having one end 14 </ b> A fixed to the base (fixed portion) 12, and the giant magnetostrictive rod 14. A shaft 18 provided through the inner space and having an upper plate (protrusion) 16 having a diameter larger than the inner diameter of the giant magnetostrictive rod 14 on the other end 14B side of the giant magnetostrictive rod, A spring (elastic member) 20 for urging the upper plate 16 of the shaft 18 toward the other end 14B of the giant magnetostrictive rod 14 and the permeability or residual magnetization amount of the giant magnetostrictive rod 14 based on the deformation of the giant magnetostrictive rod 14 are obtained. And a detection coil (detection means) 22 capable of detecting a change, and the torque of the shaft 18 is reduced by a magnetostrictive force due to a frictional force acting between the upper plate 16 of the shaft 18 and the giant magnetostrictive rod 14. Because it is possible to transmit the de 14, when a predetermined or more torque is transmitted to the giant magnetostrictive rod 14 from the shaft 18, it is possible to cut off the transmission of torque from the shaft 18. Therefore, it is possible to prevent an excessive torque from being applied to the giant magnetostrictive rod 14 from the shaft 18, prevent the giant magnetostrictive rod 14 from being damaged, and improve the strength. Further, as compared with the conventional torque sensor, the processing is easy and the cost can be reduced, and the substantially cylindrical giant magnetostrictive rod 14 is used, so that the detection sensitivity of the torque change can be improved.

  In particular, since the giant magnetostrictive rod 14 made of a giant magnetostrictive element is used, it is possible to further increase the sensitivity of detecting a torque change.

  Further, since the biasing force of the spring (elastic member) 20 can be adjusted, the frictional force acting between the upper plate 16 and the giant magnetostrictive rod 14 can be changed. The magnitude of the torque that can be transmitted to can be easily adjusted.

  Furthermore, since the upper plate (projecting portion) 16 of the shaft 18 has a larger diameter than the outer diameter on the other end 14B side of the giant magnetostrictive rod 14, the contact area between the upper plate 16 and the giant magnetostrictive rod 14 is increased. can do. Therefore, the torque of the shaft 18 can be more reliably transmitted to the giant magnetostrictive rod 14, and the detection sensitivity of torque change can be further improved.

  Further, since the elastic sheet 24 is interposed between the giant magnetostrictive rod 14 and the upper plate 16, only the torque of the shaft 18 is efficiently applied to the giant magnetostrictive rod 14 while absorbing the axial pressure of the shaft 18 by the elastic sheet 24. Can be transmitted.

  Next, the torque sensor 50 according to the second embodiment of the present invention will be described in detail with reference to FIG.

  As shown in the figure, the torque sensor 50 according to the second embodiment is provided with magnets 52 at both ends in the axial direction of the giant magnetostrictive rod 14 of the torque sensor 10 according to the first embodiment. A predetermined bias magnetic field is applied. In addition, about the part similar to the torque sensor 10 which concerns on Example 1, it shall attach | subject the same number in a figure, and the description is abbreviate | omitted.

  According to the torque sensor 50 according to the second embodiment, since a predetermined bias magnetic field is applied to the giant magnetostrictive member 14, not only the torque change of the shaft 18 but also the rotation direction of the shaft 18 can be detected. it can.

  The torque sensor according to the present invention is not limited to the shape and structure of the torque sensors 10 and 50 according to the first and second embodiments. For example, the giant magnetostrictive rod 14 is limited to a cylindrical member. Instead, a member such as a rectangular tube shape may be used.

  Moreover, although the protrusion part of the shaft 18 was comprised by the substantially disk-shaped upper plate 16, this invention is not limited to this, For example, a protrusion part may be integrally formed with the shaft 18, Moreover, a polygonal shape etc. may be sufficient. Furthermore, the elastic member according to the present invention is not limited to the spring 20.

  Furthermore, although the biasing force of the spring 20 can be adjusted, the present invention is not limited to this, and the biasing force of the spring 20 may be constant and is based on a torque value that the giant magnetostrictive rod 14 can withstand. What is necessary is just to set optimally.

  Further, the detection means in the present invention is not limited to the detection coil. For example, like the torque sensor 60 shown in FIG. May be applied to detect a change in permeability or residual magnetization of the giant magnetostrictive rod 14 as a change in electromotive force of the Hall element 62 (or magnetoresistive element).

  Note that when the detection sensitivity of the torque sensor is sufficiently obtained, a magnetostrictive member made of a magnetostrictive element may be applied instead of the super magnetostrictive member.

  That is, the torque sensor according to the present invention is provided with a magnetostrictive member, and has a substantially cylindrical magnetostrictive rod whose one end is fixed to the fixing portion, and is disposed through the inner space of the magnetostrictive rod, and A shaft provided with a protruding portion having a diameter larger than the inner diameter of the magnetostrictive rod on the other end side of the magnetostrictive rod, and an elastic member for biasing the protruding portion of the shaft toward the other end side of the magnetostrictive rod; Detecting means capable of detecting a change in magnetic permeability or residual magnetization amount of the magnetostrictive rod based on deformation of the magnetostrictive rod, and the torque of the shaft is calculated between the protruding portion of the shaft and the magnetostrictive rod. What is necessary is just to be able to transmit to the said magnetostrictive rod by the frictional force which acts in between.

Schematic side sectional view of a torque sensor according to Embodiment 1 of the present invention Schematic sectional view taken along line II-II in FIG. Sectional drawing which shows the measurement means of the torque of the torque sensor which concerns on Example 1 of this invention, and an inductance value Side sectional view showing measuring means of torque and inductance value of torque sensor according to comparative example 1 The graph which shows the relationship between the torque of the torque sensor which concerns on the comparative example 1, and an inductance value The graph which shows the relationship between a torque and an inductance value at the time of applying the preload of 60 kg / cm < ² > to the torque sensor which concerns on Example 1 of this invention. Graph showing the relationship between torque and inductance value when a preload of 80 kg / cm ² is applied to the torque sensor Schematic side sectional view of a torque sensor according to Embodiment 2 of the present invention Sectional drawing which shows the example which applied the magnetoresistive effect element as a detection means of the torque sensor which concerns on Example 1 of this invention Schematic side sectional view of a conventional torque sensor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 10, 40, 50, 60 ... Torque sensor 2 ... Magnetostrictive alloy ribbon 3 ... Shaft 12 ... Base 14 ... Giant magnetostrictive rod 16, 42 ... Shaft 18 ... Upper plate 20 ... Spring 22 ... Detection coil 24 ... Sheet 26 ... Lower plate 28 ... Nut 30 ... Torque measuring instrument 32 ... LCR meter 44 ... Plate 52 ... Magnet 62 ... Hall element

Claims (9)

  A substantially cylindrical magnetostrictive rod having a magnetostrictive member and having one end fixed to a fixed portion, and disposed through the inner space of the magnetostrictive rod, and the magnetostrictive rod on the other end side of the magnetostrictive rod A shaft provided with a protrusion having a diameter larger than the inner diameter of the rod, an elastic member for urging the protrusion on the shaft toward the other end of the magnetostrictive rod, and the magnetostrictive rod based on deformation of the magnetostrictive rod Detecting means capable of detecting a change in magnetic permeability or residual magnetization amount of the shaft, and the torque of the shaft is generated by the frictional force acting between the protruding portion of the shaft and the magnetostrictive rod. A torque sensor characterized by being able to transmit to the motor. In claim 1,
A torque sensor characterized in that an urging force of the elastic member is adjustable. In claim 1 or 2,
A torque sensor, wherein a predetermined bias magnetic field is applied to the magnetostrictive rod. In any one of Claims 1 thru | or 3,
The torque sensor, wherein the protruding portion of the shaft has a larger diameter than the outer diameter of the other end side of the magnetostrictive rod. In any one of Claims 1 thru | or 4,
A torque sensor comprising an elastic sheet interposed between the projecting portion of the shaft and the magnetostrictive rod. In any one of Claims 1 thru | or 5,
The detection means includes a detection coil disposed so as to surround the outer periphery of the magnetostrictive rod, and detects a change in permeability or residual magnetization of the magnetostrictive rod as a change in inductance value of the detection coil. Torque sensor characterized by the above. In any one of Claims 1 thru | or 5,
The torque sensor according to claim 1, wherein the detecting means includes a Hall element and detects a change in magnetic permeability or residual magnetization of the magnetostrictive rod as a change in electromotive force of the Hall element. In any one of Claims 1 thru | or 5,
The torque sensor according to claim 1, wherein the detecting means includes a magnetoresistive effect element, and detects a change in magnetic permeability or residual magnetization of the magnetostrictive rod as a change in electromotive force of the magnetoresistive effect element. In any one of Claims 1 thru | or 8.
The magnetostrictive member comprises a giant magnetostrictive member made of a giant magnetostrictive element.

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