Measuring device

Abstract

To improve the measurement sensitivity of a measuring device for measuring the torque, stress, and strain of a rotating shaft without increasing the size of the measuring device.SOLUTION: A measuring device is fixed in a form in which a rotating shaft 100 is sandwiched between a first fixed part 1 and a second fixed part 2 connected to both ends of an installation body 3. The installation body 3 is composed of a strain generation part 32, and a high-rigidity part 402 having high rigidity. One end of the strain generation part 32 is connected to the first fixed part 1, the other end of the strain generation part 32 is connected to one end of the high-rigidity part 402, and the other end of the high-rigidity part 402 is connected to the second fixed part 2. The strain generation part 32 is formed to be thin-walled and has low rigidity. Furthermore, the length between both ends of the strain generation part 32 is shorter than the interval between the first fixed part 1 and the second fixed part 2 in the axial direction of the rotating shaft 100. A strain gauge 4 is pasted to the strain generation part 32.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention mainly relates to a measurement device for measuring the torque of a shaft to be measured. [Background technology]

[0002] As a technique relating to a measuring device for measuring the torque of a shaft to be measured, a torque converter shown in FIG. 8 is known (for example, Patent Document 1). Figure 8a1 shows the configuration of the torque converter as viewed from the radial direction of the rotating shaft 800, and Figure 8a2 shows the configuration of the torque converter as viewed from the axial direction of the rotating shaft 800. This torque converter comprises a first mounting base 813 consisting of a first upper base 811 and a first lower base 812 that sandwich the rotating shaft 800, a second mounting base 823 consisting of a second upper base 821 and a second lower base 822 that sandwich the rotating shaft 800 at a position spaced a predetermined distance axially from the first mounting base 813, a beam-shaped strain-flexing part 830 whose both ends are fixed to the first mounting base 813 and the second mounting base 823, respectively, and a strain gauge 831 attached to the middle part of the circumferential side of the strain-flexing part 830. The torque of the rotating shaft 800 can be detected from the change in resistance value of the strain gauge 831 due to deformation accompanying distortion of the strain-flexing part 830 caused by twisting of the rotating shaft 800. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Publication No. 3029548 Summary of the Invention [Problem to be solved by the invention]

[0004] 8a1 and 8a2, when the torsion angle between the first mounting base 813 and the second mounting base 823 becomes θ due to the twisting of the rotating shaft 800, a torsion angle of θ also occurs at both ends T1 and T2 of the portion of the strain-flexing part 830 shown in Fig. 8a1 that has a length L between the first mounting base 813 and the second mounting base 823, as shown schematically in Fig. 8b1. If the radius from the central axis of the rotating shaft 800 to the strain-flexing part 830 is R, then at both ends T1 and T2, a displacement Rθ occurs as a displacement along the circumferential direction, as shown schematically in Fig. 8b2.

[0005] However, not all of the overall deformation of strain-flexing part 830, including this displacement Rθ, contributes to the deformation or change in resistance of strain gauge 831, but only the deformation of the portion to which strain gauge 831 is attached contributes to the deformation or change in resistance of strain gauge 831. In terms of displacement measured in the circumferential direction, the magnitude of the deformation or change in resistance of strain gauge 831 depends on the torsion angle θ formed by both ends T1, T2, and the larger the torsion angle θ generated for the same torsion of rotating shaft 800, the larger the deformation or change in resistance becomes, making it possible to detect the torque of rotating shaft 800 with higher sensitivity.

[0006] However, the torsion angle θ generated for the same torsion of the rotating shaft 800 can be increased by increasing the radius R from the central axis to the strain-flexing part 830, but doing so increases the size of the torque converter. Therefore, an object of the present invention is to improve the measurement sensitivity of a measuring device that measures torque, stress, or strain on a shaft to be measured without increasing the size of the measuring device. [Means for solving the problem]

[0007] To achieve the above object, the present invention provides a measuring device fixed to an axis to be measured, the measuring device comprising: a first fixed part fixed to the axis to be measured; a second fixed part fixed to the axis to be measured at a position axially separated from the first fixed part; a mounting body spanning the axis between the first fixed part and the second fixed part, with one end connected to the first fixed part and the other end connected to the second fixed part; and a strain gauge. The mounting body has a strain-flexible part to which the strain gauge is fixed and a high-rigidity part, which are parts obtained by dividing the mounting body in the direction extending between the first and second fixed parts. The length of the strain-flexible part in the direction in which the mounting body extends is shorter than the axial length of the axis to be measured between the first and second fixed parts, and the rigidity of the strain-flexible part against the strain detected by the strain gauge is lower than that of the high-rigidity part.

[0008] Here, in this measuring device, the erection body may consist of the strain-flexible portion and the high-rigidity portion, one end of the strain-flexible portion being connected to the first fixed portion, the other end of the strain-flexible portion being connected to one end of the high-rigidity portion, and the other end of the high-rigidity portion being connected to the second fixed portion.

[0009] Alternatively, this measuring device may have the installation body having a first high-rigidity portion and a second high-rigidity portion as the high-rigidity portion, and consisting of the strain-generating portion, the first high-rigidity portion and the second high-rigidity portion, one end of the first high-rigidity portion being connected to the first fixed portion, the other end of the first high-rigidity portion being connected to one end of the strain-generating portion, the other end of the strain-generating portion being connected to one end of the second high-rigidity portion, and the other end of the second high-rigidity portion being connected to the second fixed portion.

[0010] Furthermore, in this measuring device, the strain-causing portion may include a portion in the shape of a beam of uniform strength. In this measuring device, the direction in which the installation body of the strain-flexing portion extends may be a radial direction of the axis to be measured. Furthermore, when the installation body is composed of the strain-flexing portion, the first high-rigidity portion, and the second high-rigidity portion as described above, the first fixing portion may include a first block and a second block, and be fixed to the axis of measurement by fastening the first block and the second block together with the axis of measurement therebetween at a first fastening position that does not interfere with the axis of measurement, and the second fixing portion may include a third block and a fourth block, and be fixed to the axis of measurement by fastening the third block and the fourth block together with the axis of measurement therebetween at a second fastening position that does not interfere with the axis of measurement. The one end of the first high-rigidity portion may be connected to the first fixing portion at a position where the first fastening position is sandwiched between the first fixing portion and the axis of measurement, and the other end of the second high-rigidity portion may be connected to the second fixing portion at a position where the second fastening position is sandwiched between the second fixing portion and the axis of measurement. The direction in which the installation body of the strain-generating portion extends may be set to the radial direction of the axis to be measured.

[0011] Furthermore, the above-mentioned measuring device may be one in which the strain-causing part has a thin shape in a thickness direction, which is the tangential direction or circumferential direction of a circle passing through the strain-causing part concentric with the axis to be measured, and the strain gauge is fixed to a surface that intersects with the thickness direction. With the above-described measuring device, deformation of the installation caused by the torsion angle between the first and second fixed parts appears mainly as deformation of the strain-generating part with low rigidity. Because the length of the strain-generating part is shorter than the axial length of the axis to be measured between the first and second fixed parts, the magnitude of deformation and resistance change of the strain gauge caused by deformation of this strain-generating part is larger than if the entire installation had approximately the same rigidity.

[0012] Therefore, according to this measuring device, the measurement sensitivity can be improved without increasing the size of the measuring device. [Effects of the Invention]

[0013] As described above, according to the present invention, it is possible to improve the measurement sensitivity of a measuring device that measures torque, stress, or strain on a shaft to be measured without increasing the size of the measuring device. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing a configuration of a measurement device according to an embodiment of the present invention. [Figure 2] 1 is a diagram showing a usage form of a measurement device according to an embodiment of the present invention. [Figure 3] 1 is a diagram showing an installation structure of a measuring device according to an embodiment of the present invention; [Figure 4] FIG. 10 is a diagram illustrating another example of the configuration of a measurement device according to an embodiment of the present invention. [Figure 5] FIG. 10 is a diagram illustrating another example of the configuration of a measurement device according to an embodiment of the present invention. [Figure 6] FIG. 10 is a diagram illustrating another example of the configuration of a measurement device according to an embodiment of the present invention. [Figure 7] FIG. 10 is a diagram illustrating another example of the configuration of a measurement device according to an embodiment of the present invention. [Figure 8] 1 shows a diagram illustrating the configuration of a known torque converter and the problem to be solved by the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described. Figure 1 shows the configuration of the measurement device. For convenience, the front, back, top, bottom, left and right are defined as shown in the figures, with Figure 1a1 showing the front of the measuring device, Figure 1a2 showing the top, and Figure 1a3 showing the right side of the measuring device. Also, Figure 1b shows the measuring device from an oblique perspective. Note that the rear, bottom, and left sides of the measuring device are represented as the front, the top, and the right sides, respectively.

[0016] As shown in the figure, the measuring device has a first fixed part 1 having a hollow space that is open in the front-to-back direction, a second fixed part 2 having a hollow space that is open in the front-to-back direction, and four installation bodies 3 that connect the first fixed part 1 and the second fixed part 2 in the front-to-back direction. The first fixed part 1 has a first upper block 11 and a first lower block 12 connected at the left and right ends to the lower part of the first upper block 11. The left ends of the first upper block 11 and the first lower block 12 are connected vertically by a first left bolt 14 with a first left spacer 13 in between, and the right ends of the first upper block 11 and the first lower block 12 are connected by a first right bolt 16 with a first right spacer 15 in between.

[0017] The central portion in the left-right direction of the lower surface of the first upper block 11 is recessed upward in a V-shaped groove, and the central portion in the left-right direction of the upper surface of the first lower block 12 is recessed downward in a V-shaped groove. The space between these two V-shaped recesses forms the hollow of the first fixed part 1. The second fixed part 2 has the same configuration as the first fixed part 1. That is, the second fixed part 2 has a second upper block 21 and a second lower block 22 connected at the left and right ends to the lower part of the second upper block 21. The left ends of the second upper block 21 and the second lower block 22 are connected vertically by a second left bolt 24 with a second left spacer 23 in between, and the right ends of the second upper block 21 and the second lower block 22 are connected by a second right bolt 26 with a second right spacer 25 in between.

[0018] The central portion in the vertical and horizontal directions of the lower surface of the second upper block 21 is recessed upward in a V-shaped groove, and the central portion in the vertical and horizontal directions of the upper surface of the second lower block 22 is recessed downward in a V-shaped groove. The space between these two V-shaped recesses forms the hollow of the second fixed part 2. Next, two of the four erection bodies 3 are suspended between the first upper block 11 and the second upper block 21 in the form of beams extending in the front-to-back direction, and the remaining two are suspended between the first lower block 12 and the second lower block 22 in the form of beams extending in the front-to-back direction. In addition, the first left spacer 13, the first right spacer 15, the second left spacer 23, and the second right spacer 25 may be provided interchangeably with different vertical lengths to accommodate a wider range of different diameters of the rotating shaft 100. Measurements using such a measuring device are performed by fixing the measuring device to the rotating shaft 100 to be measured. The measuring device is fixed to the rotating shaft 100 as follows. As shown in Figure 2a, the blocks are arranged so that the rotating shaft 100 to be measured is located between the first upper block 11 and the first lower block 12, which have been separated by removing the first left bolt 14 and the first right bolt 16, and between the second upper block 21 and the second lower block 22, which have been separated by removing the second left bolt 24 and the second right bolt 26.

[0019] As shown in the front view of Figure 2b and the oblique view of Figure 2c, the first upper block 11 and the first lower block 12 are fastened together with a first left bolt 14 and a first right bolt 16, sandwiching a first left spacer 13 and a first right spacer 15 between them, and the second upper block 21 and the second lower block 22 are fastened together with a second left bolt 24 and a second right bolt 26, sandwiching a second left spacer 23 and a second right spacer 25 between them, thereby clamping the rotating shaft 100 between the four V-groove-shaped recesses and fixing the measuring device to the rotating shaft 100.

[0020] The rotating shaft 100 to be measured may be, for example, a drive shaft of an automobile. Next, when the measuring device is fixed to the rotating shaft 100, the surfaces of the four V-groove-shaped recesses that come into contact with the rotating shaft 100 to be measured are curved surfaces with the central part in the front-to-back direction bulging out toward the rotating shaft 100, as shown in Figure 2d, which shows the cross section of line DD in Figure 2b, and the four V-groove-shaped recesses come into contact with the rotating shaft 100 to be measured in a manner that is close to point contact.

[0021] Next, the four installation members 3 of the measuring device will be described. The four installation bodies 3 have the same shape, and only the orientation and arrangement are different, as shown in FIG. 2c. 3a1, a2 and a3 show the shape of one of the installation bodies 3. FIG. The tangential direction at the position of the installation body 3 of a circle concentric with the rotating shaft 100 passing through the installation body 3 is defined as the TL direction, the radial direction of the rotating shaft 100 passing through the installation body 3 is defined as the RD direction, and the axial direction of the rotating shaft 100 (the front-to-back direction of the measuring device) is defined as the AX direction, with Fig. 3a1 showing the shape of the installation body 3 as seen in the RD direction, Fig. 3a2 showing the shape of the installation body 3 as seen in the TL direction, and Fig. 3a3 showing a perspective view of the installation body 3. However, both ends of the installation body 3 in the AX direction are actually connected to the first upper block 11 and the second upper block 21, or the first lower block 12 and the second lower block 22.

[0022] As shown in the figure, the installation body 3 is divided in the AX direction into a first high-rigidity portion 31, a strain-flexing portion 32, and a second high-rigidity portion 33. Therefore, as shown in Figure 3a1, the AX-direction length L' of the strain-flexing portion 32 is smaller than the AX-direction length L of the installation body 3. To facilitate bending deformation around the axis in the RD direction, the strain-flexing portion 32 is thinner and has lower rigidity in the TL direction than the first high-rigidity portion 31 and the second high-rigidity portion 33. On the other hand, the first high-rigidity portion 31 and the second high-rigidity portion 33 are thicker than the strain-flexing portion 32 in the TL direction, and are formed in a shape that is not thin in any of the TL, RD, and AX directions and has high rigidity in each direction.

[0023] A strain gauge 4 is attached to the surface of the strain-flexing part 32 facing the TL direction so as to detect bending strain around an axis in the RD direction. Here, the number of strain gauges 4 attached to the strain-generating portion 32 of each of the erection bodies 3 may be set arbitrarily. The position in the AX direction of the strain gauge 4 attached to the strain-flexing part 32 of each installation body 3 may be set arbitrarily except for the center in the AX direction of the strain-flexing part 32. However, the strain gauge 4 has higher sensitivity when positioned closer to both ends of the strain-flexing part 32. 2b and 2c, with a measuring device fixed to the rotating shaft 100, when torque is applied to the rotating shaft 100 and the rotating shaft 100 twists as it rotates, a torsion angle is generated between the first fixed part 1 and the second fixed part 1 fixed to the rotating shaft 100, and a strain corresponding to the torsion angle is generated in the strain-generating part 32 of the erected body 3. Then, the resistance value of the strain gauge 4 changes due to deformation caused by this strain, and the amount of this change is wirelessly transmitted to an external measuring device by a signal processing part (not shown). Then, in the measuring device, the torque, strain, and stress of the rotating shaft 100 are calculated from the amount of change in the resistance value of the strain gauge 4 and output.

[0024] Now, in the above measurement, when the twisting of the rotating shaft 100 causes the torsion angle between the first fixed part 1 and the second fixed part 2 to become θ, and the radius from the central axis of the rotating shaft 100 to the installation body 3 is R, a displacement Rθ occurs at both ends of the installation body 3 as a displacement along the circumferential direction CD, as shown schematically in Figure 3b1.

[0025] At this time, since the first high rigidity portion 31 and the second high rigidity portion 33 have high rigidity and the strain-generating portion 32 has low rigidity, the first high rigidity portion 31 and the second high rigidity portion 33 do not deform at all, and it is the strain-generating portion 32 that deforms mainly, and a displacement Rθ along the circumferential direction CD occurs at both ends of the strain-generating portion 32. Furthermore, since the AX-direction length L' of the strain-flexing part 32 is smaller than the AX-direction length L of the erection body 3, the deformation and change in resistance value of the strain gauge 4 that occurs at this time is larger than when the entire erection body 3 is made into a strain-flexing part with low rigidity in the TL direction, as shown in Figure 3b2. Therefore, according to this embodiment, the sensitivity of the measuring device can be improved without increasing the length of the installation body 3. The embodiments of the present invention have been described above. Here, as the installation body 3 in the above embodiment, any shape and arrangement of the installation body 3 can be used as long as the length L' of the strain-generating part 32 in the AX direction is shorter than the distance between the first fixed part 1 and the second fixed part 2. For example, as shown in Figure 4a, an oblique view of the measuring device, Figure 4b1, the shape of the installation body 3 as viewed in the RD direction, Figure 4b2, the shape of the installation body 3 as viewed in the TL direction, and Figure 4b3, an installation body 3 may be used in which the side of the first fixed part 1 is a strain-generating part 401 and the side of the second fixed part 2 is a high-rigidity part 402.

[0026] Alternatively, as shown in Figure 5a, an oblique view of the measuring device, Figure 5b1, the shape of the installation body 3 as viewed in the RD direction, Figure 5b2, the shape of the installation body 3 as viewed in the TL direction, and Figure 453, an oblique view of the installation body 3, the installation body 3 may use, instead of the strain-flexing part 32 in the installation body 3 shown in Figure 3, a strain-flexing part 501 having beam-shaped ends with equal strength at both ends in the AX direction.

[0027] The shape of both ends of this strain-flexing part 501 is that of a beam with uniform strength, which equalizes the bending stress within both ends. Therefore, stress concentrated at the ends can be dispersed within both ends without increasing the overall rigidity of the strain-flexing part 501, thereby suppressing damage to both ends of the strain-flexing part 501. Furthermore, because the bending stress is uniform within both ends, it becomes possible to install the strain gauges 4 at any position within both ends.

[0028] Alternatively, as shown in Fig. 6a (a perspective view of the measuring device), Fig. 6b1 (a view of the installation body 3 in the RD direction from the rotating shaft 100 side), Fig. 6b2 (a view of the installation body 3 from the opposite side of Fig. 6b1), Fig. 6b3 (a view of the installation body 3 in the TL direction), and Fig. 6b4 (a perspective view of the installation body 3), the installation body 3 may be composed of a strain-flexing part 601 extending from the first fixed part 1 in the RD direction to the side opposite the rotating shaft 100, and a high-rigidity part 602 connected to the end of the strain-flexing part 601 opposite the first fixed part 1 and to the second fixed part 2. Here, although Fig. 6 shows a simple shape for the strain-flexing part 601, it may also be a beam of uniform strength like the strain-flexing part 501 in Fig. 5.

[0029] In addition, in the above, we have shown a case where a total of four erection bodies 3 are provided, including two erection bodies 3 connecting the first upper block 11 and the second upper block 21, and two erection bodies 3 connecting the first lower block 12 and the second lower block 22, but the number of erection bodies 3 may be any number.

[0030] For example, when using the erection bodies 3 of the shape shown in Fig. 6, as shown in Fig. 7a, a total of two erection bodies 3 may be provided, one erection body 3 connecting the first upper block 11 and the second upper block 21, and one erection body 3 connecting the first lower block 12 and the second lower block 22. Note that even when the erection bodies 3 are provided as in Fig. 7a, the strain-flexing part 601 may be a beam with uniform strength like the strain-flexing part 501 in Fig. 5.

[0031] In addition, in the above, the connection position between the first fixing part 1 and the erected body 3 is set to a position between the first left bolt 14 and the first right bolt 16, and the connection position between the second fixing part 2 and the erected body 3 is set to a position between the second left bolt 24 and the second right bolt 26, but the connection position between the first fixing part 1 and the erected body 3 may be set to a position to the left of the first left bolt 14 or to the right of the first right bolt 16, or the connection position between the second fixing part 2 and the erected body 3 may be set to a position to the left of the second left bolt 24 or to the right between the second right bolt 26.

[0032] That is, for example, as shown in Figure 7b, the erection body 3 connecting the first upper block 11 and the second upper block 21 may be arranged in a form in which both ends are connected to a position to the right of the first right bolt 16 of the first upper block 11 and a position to the right of the second right bolt 26 of the second upper block 21. In Figure 7b, the erection body 3 is composed of a first high rigidity portion 701 connected to a position to the right of the second right bolt 26 of the second upper block 21, a second high rigidity portion 703 connected to a position to the right of the first right bolt 16 of the first upper block 11, and a strain-flexing portion 702 connecting the first high rigidity portion 701 and the second high rigidity portion 703. 7b shows a case where a strain-flexing part 702 having a simple shape extending in the RD direction opposite to the rotating shaft 100 is used, as in Figures 6 and 7a, but a beam with uniform strength like the strain-flexing part 501 in Figure 5 may also be used. According to the configuration in Figure 7b, the installation body 3 can be arranged closer to the rotating shaft 100 than in the cases of Figures 6 and 7a, thereby making more effective use of space. [Explanation of symbols]

[0033] 1...first fixing part, 2...second fixing part, 3...elevation body, 4...strain gauge, 11...first upper block, 12...first lower block, 13...first left spacer, 14...first left bolt, 15...first right spacer, 16...first right bolt, 21...second upper block, 22...second lower block, 23...second left spacer, 24...second left bolt, 25...second right spacer, 26...second right bolt , 31...first high rigidity portion, 32...strain-flexing portion, 33...second high rigidity portion, 100...rotating shaft, 402...high rigidity portion, 701...first high rigidity portion, 702...strain-flexing portion, 703...second high rigidity portion, 800...rotating shaft, 811...first upper base, 812...first lower base, 813...first mounting base, 821...second upper base, 823...second mounting base, 830...strain-flexing portion, 831...strain gauge.

Claims

1. A measuring device fixed to a shaft to be measured, a first fixed portion fixed to the shaft to be measured; a second fixed portion fixed to the shaft to be measured at a position spaced apart from the first fixed portion in the axial direction of the shaft to be measured; a bridge bridged between the first fixed portion and the second fixed portion in the axial direction, the bridge having one end connected to the first fixed portion and the other end connected to the second fixed portion; and a strain gauge; the installation body has a strain-generating portion to which the strain gauge is fixed and a high-rigidity portion as portions obtained by dividing the installation body in a direction extending between the first fixing portion and the second fixing portion, a length of the strain-generating portion in the direction in which the installation body extends is shorter than a length of the measurement target axis between the first fixed portion and the second fixed portion; A measuring device characterized in that the rigidity of the strain-generating portion against the strain detected by the strain gauge is lower than that of the high-rigidity portion.

2. 2. The measuring device according to claim 1, the installation body is composed of the strain-generating portion and the high-rigidity portion, A measuring device characterized in that one end of the strain-flexing portion is connected to the first fixed portion, the other end of the strain-flexing portion is connected to one end of the high-rigidity portion, and the other end of the high-rigidity portion is connected to the second fixed portion.

3. 2. The measuring device according to claim 1, the installation body has a first high-rigidity portion and a second high-rigidity portion as the high-rigidity portion, and the installation body is made up of the strain-generating portion, the first high-rigidity portion, and the second high-rigidity portion; A measuring device characterized in that one end of the first high-rigidity portion is connected to the first fixed portion, the other end of the first high-rigidity portion is connected to one end of the strain-flexing portion, the other end of the strain-flexing portion is connected to one end of the second high-rigidity portion, and the other end of the second high-rigidity portion is connected to the second fixed portion.

4. 2. The measuring device according to claim 1, The measuring device is characterized in that the strain-causing portion includes a portion in the shape of a beam of uniform strength.

5. 2. The measuring device according to claim 1, A measuring device characterized in that the direction in which the installation body of the strain-generating portion extends is the radial direction of the axis to be measured.

6. 4. The measuring device according to claim 3, the first fixing portion includes a first block and a second block, and is fixed to the shaft to be measured by fastening the first block and the second block together at a first fastening position that does not interfere with the shaft to be measured, with the shaft to be measured sandwiched therebetween; the second fixing portion includes a third block and a fourth block, and is fixed to the shaft to be measured by fastening the third block and the fourth block together at a second fastening position that does not interfere with the shaft to be measured, with the shaft to be measured sandwiched therebetween; the one end of the first high-rigidity portion is connected to the first fixed part at a position where the first fastening position is sandwiched between the first high-rigidity portion and the shaft to be measured, and the other end of the second high-rigidity portion is connected to the second fixed part at a position where the second fastening position is sandwiched between the second high-rigidity portion and the shaft to be measured, A measuring device characterized in that the direction in which the installation body of the strain-generating portion extends is the radial direction of the axis to be measured.

7. 7. The measuring device according to claim 1, 2, 3, 4, 5 or 6, The strain-causing portion has a thin shape in a thickness direction, which is the tangential direction or circumferential direction of a circle that passes through the strain-causing portion and is concentric with the axis to be measured, and the strain gauge is fixed to a surface that intersects with the thickness direction.

Images