JP2005121603A - Rotational torque detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque detector capable of a highly accurate measurement of a torque around a Z-axis. <P>SOLUTION: This rotational torque detector includes a toroidal frame body 20, a center load receiving part 30, a prismatic beam-type strain generation part 40 for connecting crosswise both components, and strain gages 48 stuck on the strain generation part 40. The strain generation part 40 includes a through hole 42 constituting a Roberval mechanism, and the strain gages 48 are stuck on the unopened side face of the through hole 42, and a T-shaped part 50 comprising a long hole 52 and a flexure 53 is provided on a connection part between the toroidal frame body 20 and the strain generation part 40. A bending strain generated in the beam-type strain generation part 40 is detected by the strain gages 48, and the torque T around the Z-axis is measured, and the connection part between the toroidal frame body 20 and the strain generation part 40 is constituted by the T-shaped part 50, and unmeasured stress which becomes a detection error to the beam-type strain generation part 40 is not generated in the connection part, and thereby the torque T around the Z-axis can be measured highly accurately. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rotational torque detector used, for example, for detecting torque acting on an automobile axle, and more particularly to a rotational torque detector capable of detecting torque with high accuracy.

The following Patent Document 1 is known as this type of rotational torque detector. As shown in FIG. 5, the torque detector (sensing unit) 1 is arranged at the center of the annular upper ring 2 and the annular lower ring 3 and the rings 2 and 3 arranged in parallel. The cross-shaped beam 4 connecting the rings 2 and 3 is formed. The cross beam 4 includes vertical and horizontal beams 4A and 4B that are orthogonal to each other. The vertical beam 4A is integrated with the upper ring 2, while the horizontal beam 4B is integrated with the lower ring 3. The vertical and horizontal beams 4A and 4B are provided with through holes 5 to form a Roverval mechanism, and the strain generating portions 4a, 4a, 4b and 4b of the beams 4A and 4B act between the upper and lower rings 2 and 3. A strain gauge 6 for detecting a bending strain generated in the strain generating portion with respect to the torque around the Z axis is attached. The torque detector 1 is formed by cutting a metal block such as aluminum or iron so that accurate dimensional accuracy can be obtained in the beam shape or the like.
Japanese Patent Laid-Open No. 10-332502 (prior art column and FIG. 4)

  However, in the above-described conventional technology, the rotational torque detector (sensing unit) 1 is formed integrally with the vertical beam 4A of the cross beam 4 on the upper ring 2 and the horizontal beam 4B on the lower ring 3, respectively. The whole is formed in a very complicated shape, which makes it difficult to manufacture the sensing unit 1 and contributes to an increase in cost.

  Further, since the connecting portions between the upper and lower rings 2 and 3 and the beams 4A and 4B are formed by rigid joints, the strains in the strain generating portions 4a, 4a, 4b, and 4b are affected by the stress generated in these connecting portions. Accordingly, there has been a first problem that accurate torque cannot be detected.

  The vertical and horizontal beams 4A and 4B are attached with, for example, a second strain gauge 7 for detecting a strain with respect to a force in the X or / and Y direction with respect to the eccentric rotational torque. Although configured to detect the force in the X and / or Y direction, in order to provide a space for attaching the second strain gauge 7, a flat region other than the region where the through hole 5 is provided is used as a beam. Therefore, there is a second problem that the lengths of the vertical and horizontal beams 4A and 4B become longer and the entire torque detector (sensing unit) becomes larger.

  The present invention has been made in view of the above-described problems of the prior art, and its object is to provide a simple structure for each of the beam-type strain generating portions that connect the outer annular frame and the inner load receiving portion in a cross shape. It is an object of the present invention to provide a rotational torque detector that is easy to manufacture and can measure the torque around the Z axis with high accuracy.

In order to achieve the first object, in the rotational torque detector according to claim 1, a fixed-side annular frame, a load receiving portion disposed at a central portion of the annular frame, In a rotational torque detector comprising four prismatic beam-type strain-generating portions that connect an annular frame and the load receiving portion in a cross shape, and a strain gauge attached to each strain-generating portion. ,
The strain-generating portion is provided with a through hole for constituting a Roverval mechanism that is elastically deformed with respect to the rotational torque acting on the load receiving portion, and the Z-axis is rotated around the non-opening side surface of the through-hole in the strain generating portion. The strain gauge for torque detection was affixed, and a T-shaped portion composed of a long hole and a flexure was provided at the connecting portion between the annular frame and the strain generating portion.

  (Operation) Each of the prismatic beam-type strain generating portions that connect the annular frame body and the load receiving portion in a cross shape is a Roverval mechanism that deforms with respect to the rotational torque around the Z axis that acts on the load receiving portion. In this configuration, when a rotational torque acts on the load receiving portion, a bending strain generated in the strain generating portion is detected via the strain gauge, and the torque around the Z axis can be measured with high accuracy.

In particular, the connecting portion between the annular frame 20 and the strain-generating portion 40 is formed by the T-shaped portion 50, and no unexpected stress that becomes a detection error in the beam-type strain-generating portion is generated in the connecting portion. The torque around the axis can be measured with higher accuracy.
The connecting portion between the annular frame body and the strain generating portion is constituted by a T-shaped portion composed of a long hole and a flexure, and the connecting portion (T-shaped portion) between the annular frame body and the strain generating portion includes: Since no unexpected stress is generated as an error for the beam-type strain generating portion, the torque measurement error around the Z axis is small.

  In addition, the annular frame, the load receiving portion, and the four beam-type strain-generating portions are provided on substantially the same plane, and the through hole in the strain-generating portion opens in the Z-axis direction. It is easy to form the rotational torque detector main body by cutting with the above method.

  In order to achieve the second object, according to claim 2, in the rotational torque detector according to claim 1, the T-shaped vertical bar-shaped portion in the T-shaped portion composed of the long hole and the flexure, A plane perpendicular to the non-opening side surface of the through hole in the strain generating portion is formed, and a second strain gauge for detecting force acting along the extending direction of the strain generating portion is attached to the plane. did.

  (Operation) If the rotational torque acts on the strain-generating portion in a form that is eccentric with respect to the Z-axis, or if a lateral load acts on the load receiving portion when the rotational torque is applied, a separate affixing is applied to the strain-generating portion. Two strain gauges can be detected as a force in the direction along the strain-generating portion (force in the X or / and Y direction). And in order to stick the 2nd strain gauge which detects the distortion with respect to X or / and Y direction force to a strain generating part, a flat area other than the Roverval mechanism formation field which provided a through hole is provided in a strain generating part. In relation to this, the length of the strain generating portion is increased accordingly, and the entire rotational torque detector is increased in size. On the other hand, in claim 2, the T-shape provided at the connecting portion between the annular frame body and the strain generating portion. Since a flat surface is formed on the T-shaped vertical bar-shaped portion in the shape-shaped portion, and the second strain gauge for detecting the force acting in the X or / and Y direction is stuck on the flat surface, the length of the strain-generating portion However, the entire rotational torque detector is not enlarged.

  According to the first aspect, torque around the Z-axis is detected via the strain gauge provided in the strain-generating portion constituting the Roverval mechanism, and T provided in the connecting portion between the annular frame and the strain-generating portion. Since the detection error of the torque around the Z axis is small due to the action of the character-shaped portion, the torque around the Z axis can be measured with high accuracy.

  Further, since it is easy to form the rotational torque detector main body by cutting the metal block, the rotational torque detector can be provided at a low cost.

  According to the second aspect, since the length of the strain generating portion does not increase, it is possible to provide a compact rotational torque detector that can simultaneously measure forces in the X and / or Y directions.

  Next, embodiments of the present invention will be described based on examples.

  1 to 4 show an embodiment of the present invention, FIG. 1 is a front view of a torque detector according to a first embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of the torque detector (in FIG. 1). 3 is a cross-sectional view taken along line II-II), FIG. 3 is a diagram showing the arrangement of strain gauges with serial numbers, FIGS. 4A, 4B, and 4C are rotational torque, force in the X direction, and Y It is a figure which shows the Whiston bridge circuit of the strain gauge which measures each directional force.

  In these drawings, the rotational torque detector 10 includes a fixed-side annular frame 20, a load receiving portion 30 disposed at the center of the annular frame 20, and the annular frame 20 and the load receiving portion 30. Are formed with four prismatic beam-type strain-generating portions 40 that are connected to each other in a cross shape, and a strain gauge 48 attached to each strain-generating portion 40.

  A fixed disk 24 integrally formed with a fixed shaft 22 is integrated with a fastening screw 26 at the center of the annular frame 20. On the other hand, a torque input shaft 32 is integrally formed at the center of the load receiving portion 30, and four beam-type strain generating portions 40 extend radially outward at intervals of 90 degrees in the circumferential direction. The beam-type strain generating portion 40 is connected to the annular frame body 20 via a T-shaped portion 50 including a long hole 52 and a flexure 53.

  Each strain generating portion 40 is constituted by a beam having a rectangular cross section, and a glasses-type through hole 42 is provided at a substantially central portion in the longitudinal direction of the beam so as to act via the torque input shaft 32. A robust mechanism that is elastically deformed with respect to the torque T is configured. A strain gauge 48 is attached to the non-opening side surface 41 of the through hole 42 in the strain generating portion 40 to detect bending strain generated in the strain generating portion 40 when the rotational torque T acts.

  Further, the T-shaped portion 50 provided between each strain generating portion 40 and the annular frame 20 is formed by a long hole 52 provided in the inner peripheral edge of the annular frame 20 and the long hole 52. The first thin plate-like portion 54, which is a T-shaped horizontal bar-like portion, and the T-shaped vertical rod-like portion formed by the constricted portions 55, 55 provided between the thin plate-like portion 54 and the leading end portion of the strain-generating portion 40. The flexure 53 is composed of the first thin plate portion 54 and the second thin plate portion 56.

  The first thin plate-like portion 54 has a width corresponding to the thickness t of the flange-shaped inner peripheral edge portion 21 of the annular frame 20 and extends in a direction orthogonal to the extending direction of the strain-generating portion 40. The second thin plate-like portion 56 extends parallel to the extending direction of the strain-generating portion 40 with the pair of arc-shaped constricted portions 55, 55 as the left and right side edges, and the entire T-shaped portion 50 is formed. Due to the flexibility, the T-shaped portion 50 when the rotational torque is applied to the load receiving portion 30 does not generate unexpected stress that causes an error with respect to the bending strain generated in the strain generating portion 40.

  That is, in the case of a structure in which the connecting portion between the annular frame 20 and the strain generating portion 40 is directly rigidly joined without the T-shaped portion 50 being interposed, a rotational torque is applied to the torque input shaft 32 to apply the strain gauge 48. In the strain generating portion 40 configured by the Roverval mechanism, the torque is detected by the unexpected stress generated in the rigidly connected connection portion between the strain generating portion 40 and the annular frame 20 when the torque is detected via Although there is a possibility that an accurate bending strain cannot be detected, in the present embodiment, the annular frame body 20 and the strain generating portion 40 are connected via a T-shaped portion 50 including a long hole 52 and a flexure 53 ( Since the connecting portion between the strain-generating portion 40 and the annular frame 20 is composed of a T-shaped portion 50 that does not generate unexpected stress when the rotational torque is applied), in the strain-generating portion 40 (the strain gauge 48) Accurate bending strain detection is possible.

  Further, the side edge (constricted portion 55) of the second thin plate-like portion 56 is formed in an arc shape, and the stress at the connection portion between the flexure 53 (first thin plate-like portion 54) and the second thin plate-like portion 56. Concentration is avoided, and the durability in the T-shaped portion 50 is secured accordingly.

  In addition, the front surface and the back surface of the second thin plate-like portion 56 are formed by planes orthogonal to the Z axis, and the second strain gauge for detecting the axial force in the X direction or the Y direction is formed on these surfaces. 49 is affixed. That is, at the time of torque detection, in addition to the case where only the rotational torque that is not eccentric with respect to the axis of the input shaft 32 acts, for example, the rotational torque that is eccentric with respect to the axis of the input shaft 32 may act. In such a case, an appropriate rotational torque cannot be detected only by the output of the strain gauge 48. Therefore, when the eccentric rotational torque acts, the force acting in the direction (X direction or / and Y direction) along the extending direction of the strain generating portion 40 is detected by the strain gauge 49, and the strain gauge 48 By correcting the measured value (rotational torque) based on the output using the measured value based on the output of the strain gauge 49, it is configured so that proper rotational torque can be detected for the eccentric rotational torque.

  As shown in FIG. 3, the total number of strain gates 48 is 16 from z1 to z16, and the number of strain gates 49 is 8 from x1 to x4 and y1 to y4. Connected as shown in (c), a Whiston bridge circuit that detects rotational torque, force in the X direction, and force in the Y direction is configured.

  In addition, the rotational torque detector 10 is formed by cutting a metal block made of aluminum or iron alloy, but the through hole 42 of the beam-type strain generating portion 40 opens in the front-rear direction (Z-axis direction). With respect to a disk-shaped metal block corresponding to the outer shape of the annular frame 20, the load receiving portion 30, the beam-type strain-generating portion 40 having the Roverval structure, and the T-shaped portion 50 are formed relatively easily using a cutting tool. Therefore, the manufacturing process is very simple compared to the case where the conventional torque detector (sensing unit) 1 is formed by cutting.

It is a front view of the torque detector which is the 1st example of the present invention. It is a longitudinal cross-sectional view (cross-sectional view which follows the line II-II shown in FIG. 1) of the torque detector. It is a figure which shows arrangement | positioning of the strain gauge which attached | subjected the serial number. (A) It is a figure which shows the Whiston bridge circuit of the strain gauge which measures rotational torque. (B) It is a figure which shows the Whiston bridge circuit of the strain gauge which measures the force of a X direction. (C) It is a figure which shows the Whiston bridge circuit of the strain gauge which measures the force of a Y direction. It is a perspective view of the conventional rotational torque detector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rotational torque detector 20 Fixed side annular frame 30 Load receiving part 32 Torque input shaft T Rotational torque 40 Beam type strain generating part 48 Strain gauge 49 Second strain gauge 42 Through hole 50 T-shaped part 52 Long hole 53 flexure 54 first thin plate-like portion 56 second thin plate-like portion which is a T-shaped vertical bar-like portion

Claims (2)

A fixed annular ring frame, a load receiving portion disposed at the center of the annular frame, and four prismatic beams that connect the annular frame and the load receiving portion in a cross shape. In a rotational torque detector comprising a mold strain portion and a strain gauge attached to each strain portion,
The strain-generating portion is provided with a through hole for constituting a Roverval mechanism that is elastically deformed with respect to the rotational torque acting on the load receiving portion, and a non-opening side surface of the through-hole in the strain-generating portion is provided around the Z axis. A rotation gauge is provided with a strain gauge for detecting rotational torque, and a T-shaped portion comprising a long hole and a flexure is provided at a connecting portion between the annular frame and the strain generating portion. Torque detector.   A plane perpendicular to the non-opening side surface of the through hole in the strain-generating portion is formed in the T-shaped vertical bar-shaped portion in the T-shaped portion including the long hole and the flexure, and the strain-generating portion extends on the plane. The rotational torque detector according to claim 1, wherein a second strain gauge for detecting a force acting along the direction is attached.

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