JP7350605B2 - Strain sensor fixing device and torque sensor using it - Google Patents

Description

Embodiments of the present invention relate to, for example, a strain sensor fixing device provided at a joint of a robot arm, and a torque sensor using the same.

The torque sensor includes a first structure to which torque is applied, a second structure to which torque is output, and a plurality of strain-generating parts serving as beams connecting the first structure and the second structure. However, a plurality of strain gauges as sensor elements are arranged in these strain generating parts. A bridge circuit is configured by these strain gauges (see, for example, Patent Documents 1, 2, and 3).

Japanese Patent Application Publication No. 2013-096735 Japanese Patent Application Publication No. 2015-049209 Japanese Patent Application Publication No. 2017-172983

Generally, a strain sensor includes a plurality of strain gauges as sensor elements provided on a metal strain body. Methods for fixing this strain sensor to the torque sensor include, for example, welding, adhesive, and multiple screws.

However, when a strain sensor is fixed to a structure by welding, the temperature of the strain body increases rapidly due to welding. Therefore, the composition, shape, etc. of the flexure element and the strain gauge may change, which may affect the performance of the strain sensor.

Further, when fixing the strain sensor to the structure using an adhesive, a low-rigidity adhesive is interposed between the strain body and the structure. Therefore, the deformation of the structure is not directly transmitted to the strain body, which may reduce the sensitivity of the strain sensor.

On the other hand, when fixing a strain sensor to a structure using screws, a presser member is provided on the strain body, and the presser member is fastened to the structure with the screw. Fixed. In such a configuration, since the holding member and the flexural body come into surface contact, the holding member needs to maintain a high pressing force against the flexural body. In order to maintain a high pressing force, it is necessary to increase the size and rigidity of the holding member, the size of the screws, and the number of screws. Therefore, it is difficult to reduce the size and thickness of the torque sensor provided with the holding member and the screw.

The present embodiment provides a strain sensor fixing device that can reliably fix the strain sensor to a structure while preventing deterioration in sensor performance and enlargement of the device configuration, and a torque sensor using the same.

A strain sensor fixing device according to an embodiment is provided with a first side, a second side parallel to the first side, and an opening between the first side and the second side. an end of a strain-generating body constituting a strain sensor, the first side being in contact with the first structure, and the second side being provided on the first structure; a fixing member that is in contact with the first structure; a screw that is inserted into the opening and screwed into the first structure; and the fixing member is brought into line contact or point contact with another part to prevent rotation of the fixing member. a rotation stopper for preventing rotation, the surface is provided at a position away from a line connecting the first side and the second side, and the first side is attached to the first structure. Line contact or point contact is made, and the second side is made line contact or point contact with the end of the flexure element .

FIG. 1 is a perspective view showing a torque sensor to which this embodiment is applied. FIG. 2 is a plan view of FIG. 1 with a part removed. FIG. 3 is an enlarged perspective view showing the mounting portion of the strain sensor shown in FIG. 2; FIG. 3 is an enlarged plan view of a part of FIG. 2; 5 is a cross-sectional view taken along line VV in FIG. 4. FIG. FIG. 4 is an enlarged perspective view showing a fixing plate as a fixing member shown in FIG. 3; FIG. 3 is a cross-sectional view showing a first modification of the fixing plate. FIG. 7 is a sectional view showing a second modification of the fixing plate. FIG. 7 is a sectional view showing a third modification of the fixing plate. FIG. 3 is a configuration diagram showing the vicinity of a first structure provided with a rotation stopper according to the first embodiment. FIG. 7 is a configuration diagram showing the vicinity of a first structure provided with a rotation stopper according to a second embodiment. FIG. 7 is a perspective view of a fixing plate according to a third embodiment seen from below. FIG. 7 is a configuration diagram showing the vicinity of a first structure provided with a rotation stopper according to a third embodiment. FIG. 7 is a perspective view of a fixing plate according to a fourth embodiment, viewed from below. FIG. 7 is a configuration diagram showing the vicinity of a first structure provided with a rotation stopper according to a fourth embodiment.

Hereinafter, embodiments will be described with reference to the drawings. In the drawings, the same parts are designated by the same reference numerals.

(Basic configuration of each embodiment)
First, the basic configuration of each embodiment will be explained.
1 and 2 show an example of a torque sensor 10 to which this embodiment is applied. The configuration of the torque sensor 10 is not limited to this, and can be applied to torque sensors with various configurations. Furthermore, the present embodiment can be applied not only to torque sensors but also to force sensors using strain gauges.

In FIG. 1, the torque sensor 10 includes a first structure 11, a second structure 12, a plurality of third structures 13, a plurality of waterproof caps 14, a case 15, a bush 16, and a cable 17.

The first structure 11 and the second structure 12 are formed in an annular shape, and the diameter of the second structure 12 is smaller than the diameter of the first structure 11 . The second structure 12 is arranged concentrically with the first structure 11, and the first structure 11 and the second structure 12 are connected by a third structure 13 as a plurality of beams arranged radially. has been done. The number of third structures 13 is, for example, eight, and the eight third structures 13 are arranged at equal intervals. The number of third structures 13 is not limited to eight.

The first structure 11 is connected to, for example, an object to be measured, the second structure 12 is connected to another structure (not shown), and the plurality of third structures 13 are connected to the first structure 11 to the second structure. Torque (moment (Mz) shown in FIG. 2) is transmitted to the structure 12. Conversely, the second structure 12 is connected to the object to be measured, the first structure 11 is connected to another structure (not shown), and a plurality of third structures are connected from the second structure 12 to the first structure 11. Torque may also be transmitted via the body 13.

In the case of a force sensor, the first structure 11, second structure 12, and third structure 13 are three-dimensionally deformed, and with respect to the three orthogonal axes (x, y, z) shown in FIG. Detect force (Fx, Fy, Fz) and moment (Mx, My, Mz).

The first structure 11, the second structure 12, and the plurality of third structures 13 are made of metal, for example, stainless steel, but if they can have sufficient mechanical strength against the applied torque. , it is also possible to use materials other than metal.

As shown in FIG. 2, a strain sensor 20, which will be described later, is arranged corresponding to each third structure 13, and each strain sensor 20 is covered with a cap 14. In FIG. 2, one cap 14 has been removed and the strain sensor 20 is exposed. In this embodiment, the number of strain sensors 20 is the same as the number of third structures 13, but the number is not limited to this, and the number of strain sensors 20 is the same as the number of third structures 13. It may be less.

The configuration of each strain sensor 20 is the same. The strain sensor 20 is provided between the first structure 11 and the second structure 12. That is, as will be described later, one end of the strain sensor 20 is joined to the first structure 11, and the other end of the strain sensor 20 is joined to the second structure 12.

The second structure 12 has a hollow part 12a, and the case 15 is attached to the second structure 12 around the hollow part 12a. Inside the case 15, a processing circuit (not shown) is provided that processes the electrical signal supplied from the strain sensor 20 and generates a torque detection signal as a sensor signal.

A bush 16 for holding a cable 17 is provided in a portion of the case 15. One end (not shown) of the cable 17 is connected to a processing circuit within the case 15, and the other end of the cable 17 is passed through, for example, the hollow portion 12a. The cable 17 supplies power to the processing circuit from the outside and outputs the sensor signal processed by the processing circuit to the outside. Since the configuration of the processing circuit is not the essence of this embodiment, its description will be omitted.

3, 4, and 5 show the strain sensor 20 and the mounting structure for the strain sensor 20.
FIG. 3 shows the configuration of the attachment part of the strain sensor 20. A recess 30 is integrally formed in the first structure 11, the second structure 12, and the plurality of third structures 13. At the bottom of the recess 30, a portion corresponding to the first structure 11 is provided with a first bottom 31a and a second bottom 32a lower than the first bottom 31a. The difference in depth between the first bottom portion 31a and the second bottom portion 32a is approximately equal to the thickness of the strain body 21, as shown in FIG.

At the bottom of the recess 30, a portion corresponding to the second structure 12 is also provided with a first bottom 31b and a second bottom 32b lower than the first bottom 31b. The difference in depth between the first bottom portion 31b and the second bottom portion 32b is also approximately equal to the thickness of the strain body 21.

At the bottom of the recess 30, a third bottom 33 lower than the second bottoms 32a and 32b is provided at a portion corresponding to the third structure 13.

An opening 34a is provided approximately at the center of the second bottom portion 32a corresponding to the first structure 11, and a thread is provided within this opening 34a. An opening 34b is also provided approximately at the center of the second bottom portion 32b corresponding to the second structure 12, and a screw thread is provided inside this opening 34b.

As shown in FIG. 4, the strain sensor 20 is provided within the recess 30 between the first structure 11 and the second structure 12. The strain sensor 20 includes, for example, a metal strain body 21 and a plurality of strain gauges 22 as sensor elements arranged on one surface of the strain body 21.

The strain gauge 22 is, for example, a thin film resistance element, and its resistance value changes as the strain body 21 deforms. The plurality of strain gauges 22 constitute a bridge circuit (not shown), and a change in resistance value is detected as an electric signal by the bridge circuit. The plurality of strain gauges 22 are connected to one end of a flexible substrate 23 (shown in FIGS. 2 and 5) provided at the center of the strain body 21. The other end of the flexible substrate 23 is connected to a processing circuit inside the case 15. The electrical signal output from the bridge circuit is supplied to the processing circuit via the flexible substrate 23, and the processing circuit generates a torque detection signal as a sensor signal.

The strain body 21 has a rectangular shape, for example, and the length of the strain body 21 is longer than the length of the third bottom portion 33. The strain body 21 is fixed to the first structure 11 and the second structure 12 by a fixing device 40a and a fixing device 40b while being disposed in the recess 30.

Specifically, as shown in FIG. 5, the first end of the strain body 21 is placed on the second bottom 32a of the first structure 11, and the second end of the strain body 21 is placed on the second bottom 32a of the first structure 11. It is placed on the second bottom portion 32b of the second structure 12. That is, the strain body 21 is arranged between the opening 34 a of the second bottom 32 a of the first structure 11 and the opening 34 b of the second bottom 32 b of the second structure 12 .

The first end of the strain body 21 is fixed to the first structure 11 by a fixing device 40a disposed in a portion of the recess 30 corresponding to the first structure 11, and the second end of the strain body 21 is , is fixed to the second structure 12 by a fixing device 40b disposed in a portion of the recess 30 corresponding to the second structure 12.

The fixing device 40a and the fixing device 40b have the same configuration, and each of the fixing device 40a and the fixing device 40b includes a fixing plate 41 and a screw 42 as a fixing member. In the fixing device 40a, the fixing plate 41 is attached to the first structure 11 by screws 42 that are screwed into the openings 34a. In the fixing device 40b, the fixing plate 41 is attached to the second structure 12 by screws 42 that are screwed into the openings 34b.

The screw 42 is inserted from above the fixing plate 41 and is screwed into the opening 34 a of the first structure 11 or the opening 34 b of the second structure 12 .

When the screws 42 of the fixing device 40a are tightened, the first end of the strain body 21 is fixed to the first structure 11 by the fixing plate 41, and when the screws 42 of the fixing device 40b are tightened, the first end of the strain body 21 is fixed to the first structure 11 by the fixing plate 41. The second end portion is fixed to the second structure 12 by a fixing plate 41 .

(Configuration of fixed plate)
FIG. 6 shows one form of the fixing plate 41 according to this embodiment.
The fixing plate 41 is made of, for example, the same metal as the first structure 11, but is not limited thereto, and may be made of another material.

The fixed plate 41 has, for example, a rectangular parallelepiped main body 41a. The fixed plate 41 and the main body 41a are the same, and the fixed plate 41 is also simply referred to as the main body 41a. For example, a first protrusion 41c is provided along a first side of the bottom surface 41b of the main body 41a, and a second protrusion 41d is provided along a second side parallel to the first side. The first protrusion 41c and the second protrusion 41d are linear and protrude from the bottom surface 41b in the same direction. Therefore, the bottom surface 41b is arranged at a position away from the line connecting the first protrusion 41c and the second protrusion 41d. Furthermore, the main body 41a has an opening 41f penetrating from the surface 41e to the bottom surface 41b.

The width W1 of the fixed plate 41 is narrower than the width W2 of the recess 30 (shown in FIG. ), or shorter than the length L3 of the portion of the recess 30 corresponding to the second structure 12. Here, the relationship between L2 and L3 is, for example, L2<L3, but is not limited to this. That is, the length of the fixing plate 41 is such that when the screw 42 is tightened, the fixing plate 41 can contact the first bottom portion 31a and the first end of the flexure element 21, or the length of the fixation plate 41 can contact the first bottom portion 31b and the flexure element 21. The length may be sufficient as long as it can come into contact with the second end of.

Specifically, as shown in FIGS. 4 and 5, in a state where two fixing plates 41 are inserted into a portion of the recess 30 corresponding to the first structure 11 and a portion corresponding to the second structure 12. It is only necessary that the first protrusion 41c of each fixed plate 41 can be in line contact with the first bottom part 31a or the first bottom part 31b, and the second protrusion 41d should be in line contact with the first end part or the second end part of the strain body 21.

In this manner, with the two fixing plates 41 inserted into the recesses 30, the screws 42 are inserted into the openings 41f of each fixing plate 41, and the screws 42 are inserted into the openings 34a of the first structure 11 or the second structure. By being screwed into the opening 34b of the body 12, the first protrusion 41c of the fixing plate 41 is in line contact with the first bottom 31a or the first bottom 31b, and the second protrusion 41d is in line contact with the first end of the strain body 21. or the second end.

Note that, as shown in FIG. 6, the first protrusion 41c of the fixing plate 41 was linear, and the first protrusion 41c was in line contact with the first bottom portion 31b. However, the present invention is not limited thereto, and, for example, as shown by the broken line in FIG. 6, the first protrusion 41c may be a dot-shaped protrusion, and the first protrusion 41c may make point contact with the first bottom portion 31b. Although the dot-shaped first protrusion 41c is provided approximately at the center of the first side, for example, two first protrusions may be provided at both ends of the first side. Alternatively, three first protrusions may be provided at the center of the first side and at both ends.

(Effects due to the basic configuration of the embodiment)
According to the embodiment described above, the fixing plate 41 has the first protrusion 41c and the second protrusion 41d, and by tightening the screw 42, the first protrusion 41c comes into line contact with the first bottom portion 31a or the first bottom portion 31b. , the second protrusion 41d is in line contact with the first end or the second end of the strain body 21. Therefore, it is possible to fix the strain body 21 to the first structure 11 and the second structure 12 with a higher pressure than, for example, when the strain body and the fixing plate are in surface contact with each other. Therefore, it is possible to reduce variations in the fixing strength of the strain body 21 to the first structure 11 and the second structure 12, and it is possible to prevent a decrease in sensor performance.

Moreover, according to the fixing method using the fixing plate 41 of the present embodiment, by simply bringing the second protrusion 41d of the fixing plate 41 into line contact with the strain body 21, the strain body 21 can be moved between the first structure 11 and the strain body 21. 2 structure 12. Therefore, thermal deformation of the strain body 21 and the strain gauge can be prevented, for example, when the strain body 21 is fixed to the first structure 11 and the second structure 12 by welding. Moreover, unlike the case where the strain body 21 is fixed with an adhesive, a low-rigidity portion is not interposed between the strain body 21 and the first structure 11 and the second structure 12. Therefore, according to the fixing method using the fixing plate 41 of this embodiment, the force applied to the first structure body and the second structure body 12 can be reliably transmitted to the strain body 21, and the sensor performance It is possible to improve

Moreover, the fixing devices 40a, 40b are each composed of one fixing plate 41 and one screw 42. Therefore, the number of parts is small, and it is possible to prevent the fixing devices 40a and 40b from increasing in size and the torque sensor 10 from increasing in size.

Furthermore, since the fixing devices 40a, 40b are composed of one fixing plate 41 and one screw 42, assembly of the fixing devices 40a, 40b is easy.

Further, the screw 42 is inserted from above the fixing plate 41 and is screwed into the opening 34 a of the first structure 11 or the opening 34 b of the second structure 12 . Therefore, the assembly work is easier than, for example, when the screw 42 is inserted from the opening 34a of the first structure 11 or the opening 34b of the second structure 12 and screwed into the fixing plate 41. is possible.

(Modified example of fixed plate)
(First modification)
FIG. 7 shows a first modification of the fixing plate. In the case of the embodiment shown in FIG. 6, the main body 41a is provided with a first protrusion 41c and a second protrusion 41d on a flat bottom surface 41b.

On the other hand, in the first modification, the rectangular parallelepiped-shaped main body 51a of the fixing plate 51 has a curved bottom surface 51b, the first side of the bottom surface 51b functions as the first protrusion 51c, and the first A second side parallel to the side functions as the second protrusion 51d. Therefore, the curved bottom surface 51b is arranged at a position away from the line connecting the first protrusion 51c and the second protrusion 51d. An opening 51f that penetrates the surface 51e is provided in the center of the bottom surface 51b.

Also according to the first modification, it is possible to obtain the same effects as in the embodiment described above. Moreover, according to the second modification, the bottom surface 51b of the main body 51a is curved, so that the elasticity of the fixed plate 51 is improved. Therefore, it is possible to securely fix the strain body 21 by the fixing plate 51.

Furthermore, according to the first modification, the first protrusion 51c and the second protrusion 51d can be formed simply by processing the bottom surface of the main body 51a into a curve, so that manufacturing can be facilitated.

(Second modification)
FIG. 8 shows a second modification of the fixing plate. In the first modification shown in FIG. 7, the main body 51a has a curved bottom surface 51b.

On the other hand, in the second modification, for example, the rectangular parallelepiped-shaped main body 61a of the fixed plate 61 is entirely curved. Therefore, it has a curved bottom surface 61b, a first side of the bottom surface 61b functions as a first protrusion 61c, and a second side parallel to the first side functions as a second protrusion 61d. Therefore, the curved bottom surface 61b is arranged at a position away from the line connecting the first protrusion 61c and the second protrusion 61d. An opening 61f penetrating the surface 61e is provided in the center of the bottom surface 61b.

The second modification also allows the same effects as those of the embodiment described above to be obtained. Furthermore, according to the second modification, the entire body 61a is curved, so the elasticity of the fixing plate 61 is improved. Therefore, the strain-generating body 21 can be fixed more reliably by the fixing plate 61.

Furthermore, according to the second modification, the first protrusion 61c and the second protrusion 61d can be formed simply by processing the main body 61a into a curved shape, so that manufacturing can be facilitated.

(Third modification)
FIG. 9 shows a third modification of the fixing plate. In the above embodiment and each modified example, protrusions are provided on two sides of the main body of the fixing plate.

On the other hand, in the third modification shown in FIG. 9, the main body 71a of the fixed plate 71 is, for example, a rectangular parallelepiped, and protrusions 71c are provided along the four sides of the bottom surface 71b of the main body 71a. That is, the protrusion 71c is provided around the bottom surface 71b.

It is possible to obtain the same effect as the embodiment described above also by the third modification. Furthermore, by providing the projections 71c around the bottom surface 71b, it is possible to increase the rigidity of the fixing plate 71, and it is possible to fix the strain body 21 more reliably.

Furthermore, although the case has been described in which the shape of the main body 71a of the fixed plate 71 is a rectangular parallelepiped and the shape of the bottom surface 71b is a rectangle, the shape of the main body 71a of the fixed plate 71 is a cube and the shape of the bottom surface 71b is a square. It is also possible. In this case, the strain body 21 can be fixed using any two parallel sides among the four sides. Therefore, there is no need to consider the orientation of the fixing plate 71 with respect to the recess 30a, so the assembly work can be simplified.

Note that in the first modification and the second modification as well, it is possible to provide a protrusion around the main body.

(First embodiment)
In the first embodiment, changes will be mainly described based on the basic configuration described above, but changes may be made in the same manner based on the first to third modified examples. Note that the same applies to subsequent embodiments.

In addition, in this embodiment, the fixed plate 41 mainly explains the structure which makes line contact or point contact with the 1st structure body 11 or the 2nd structure body 12, and the strain body 21, but surface contact may be sufficient as it. The contact can be made in any way. The same applies to subsequent embodiments.

FIG. 10 is a configuration diagram showing the vicinity of the first structure 11 provided with the rotation stoppers 35a and 36a according to the first embodiment of the present invention. Further, FIGS. 3 and 4 show rotation stoppers 35a, 35b, 36a, and 36b.

The fixing device 40a includes two rotation stoppers 35a and 36a. The fixing device 40b includes two rotation stoppers 35b and 36b. The rotation stop portions 35a, 36a in the fixing device 40a and the rotation stop portions 35b, 36b in the fixing device 40b are configured identically. The rotation stoppers 35a to 36b prevent the fixed plate 41 from rotating together with the rotation of the screws 42 when the fixed plate 41 is attached with the screws 42.

The rotation stoppers 35a to 36b are formed on the inner surfaces of the recess 30 of the third structure 13 on both sides where the fixing plates 41 are located. The surface of each of the rotation stoppers 35a to 36b has a curved surface shape that is bent in two so that a vertex extending linearly in the z-axis direction (torque rotation axis direction) is formed. The rotation stoppers 35a to 36b are integrally formed with the third structure 13. Note that the rotation stoppers 35a to 36b may not be formed integrally with the third structure 13, but may be formed of separate members.

Here, if the screw 42 is a right-handed screw that is tightened by rotating to the right, the rotation stop portion 35a is located on the strain sensor 20 side (inside) from the center of the opening 41f and on the right side toward the strain sensor 20 side. , 35b, the other rotation stopper 36a, 36b may be omitted. On the other hand, if the screw 42 is a left-handed thread, if there are rotation stoppers 36a and 36b located on the strain sensor 20 side (inside) from the center of the opening 41f and on the left side toward the strain sensor 20 side, The other rotation stoppers 35a and 35b may be omitted.

Note that when the rotation stopper is provided outside the center of the opening 41f (on the opposite side from the strain sensor 20), if the screw 42 has a right-hand thread, the rotation stopper should be placed on the left side toward the strain sensor 20 side. When the screw 42 is a left-handed screw, a rotation stopper may be provided on the right side when facing the strain sensor 20 side.

With reference to FIG. 10, the function of the rotation stopper 35a provided on the first structure 11 side when the screw 42 is a right-hand thread will be described. The same applies to the function of the rotation stopper 36a on the opposite side.

Before the fixed plate 41 is placed at an appropriate position and fixed with the screws 42, the fixed plate 41 and the rotation stopper 35a are in substantially contact with each other. However, a slight gap may be provided between the fixed plate 41 and the rotation stopper 35a.

To fix the fixing plate 41, the screw 42 is rotated. At this time, when the fixed plate 41 tries to rotate together with the screws 42, the strain sensor 20 side portion of the side surface of the fixed plate 41 on the rotation stopper 35a side is connected to the apex portion of the rotation stopper 35a extending in the z-axis direction and the z-axis. line contact in the direction. As a result, the fixed plate 41 does not rotate any further, and only the screws 42 rotate.

Note that the rotation stoppers 35a to 36b may be divided into several parts such that the apex portions are lined up in the z-axis direction, and formed so that each of the plurality of apexes makes point contact with the fixed plate 41.

According to this embodiment, the rotation stop parts 35a to 36b are provided, and the fixed plate 41 that is about to rotate comes into line contact with the rotation stop parts 35a to 36b in the z direction, so that the fixed plate 41 can be placed at an appropriate position. This can prevent it from rotating and shifting. Furthermore, when fixing with the screws 42, no jig is required to prevent the fixing plate 41 from rotating.

Here, when the strain sensor 20 is held in line contact (or point contact) with the fixed plate 41, interference with other axes is suppressed, and the rotation stoppers 35a to 36b are formed in a shape that makes line contact with the fixed plate 41. By doing so, interference with other axes can be further suppressed.

By forming the rotation stoppers 35a to 36b in a shape that makes line contact with the fixed plate 41, interference with other axes can be suppressed. Furthermore, since the line contact is in the z-axis direction, a desirable effect is more likely to be obtained than in the x-axis or y-axis direction.

By providing the rotation stop parts 35a to 36b on both sides of the fixed plate 41, the rotation stop parts 35a to 36b can have the function of positioning the fixed plate 41, and when the screw 42 rotates in the direction of loosening, the fixed plate It is also possible to provide a function to prevent 41 from rotating together and shifting.

(Second embodiment)
FIG. 11 is a configuration diagram showing the vicinity of the first structure 11 provided with rotation stoppers 37a and 38a according to the second embodiment of the present invention.

The rotation stop portions 37a, 38a are provided in place of the rotation stop portions 35a, 36a according to the first embodiment shown in FIG. The rotation stop portions 37a, 38a are formed by forming screw holes on the inner surface of the recess 30 at the same positions as the rotation stop portions 35a, 36a according to the first embodiment, and inserting screws into the screw holes. Other points are similar to the first embodiment. For example, only one of the rotation stoppers 37a and 38a may be provided corresponding to the rotational direction of the screw 42.

According to this embodiment, in addition to the effects of the first embodiment, the following effects can be obtained.

Since the rotation stop portions 37a and 38a are formed by inserting screws, they can be easily configured. Further, since the fixed plate 41 makes point contact with the tops of the screw heads of the rotation stoppers 37a and 38a to prevent rotation, interference with other axes can be suppressed more than in the case of line contact.

In this embodiment, a configuration has been described in which screws serving as the rotation stoppers 37a and 38a are provided on the inner surface of the recess 30, but screws may be provided on the fixing plate 41 at positions corresponding to the rotation stoppers 37a and 38a. It may also be configured in the same way.

(Third embodiment)
FIG. 12 is a perspective view of a fixing plate 41A according to a third embodiment of the present invention viewed from below. FIG. 13 is a configuration diagram showing the vicinity of the first structure 11 provided with rotation stoppers 41g and 41h according to the third embodiment of the present invention.

In this embodiment, rotation stoppers 41g and 41h are provided instead of the rotation stoppers 35a and 36a according to the first embodiment. The fixed plate 41A has the same shape as the fixed plate 41 according to the first embodiment shown in FIG. 6, with rotation stoppers 41g and 41h provided therein. Other points are similar to the first embodiment. For example, only one of the rotation stoppers 41g and 41h may be provided corresponding to the rotational direction of the screw 42.

When the fixing plate 41A is properly arranged, the rotation stoppers 41g and 41h are located on the left and right side surfaces of the fixing plate 41A toward the strain sensor 20, and are closer to the strain sensor 20 than the center of the opening 41f. inside). That is, the rotation stoppers 41g and 41h are arranged at substantially the same positions as the rotation stoppers 35a and 36a according to the first embodiment. The surface of each rotation stopper 41g, 41h is formed in the same shape as the surface of each rotation stopper 35a to 36b according to the first embodiment.

Similarly to the first embodiment, when the fixed plate 41A tries to rotate together with the screws 42, the apex portions of the rotation stoppers 41g and 41h of the fixed plate 41A, which extend in the z-axis direction, collide with the recess of the third structure 13. It makes line contact with the inner surface facing the rotation stoppers 41g and 41h of No. 30 in the z-axis direction. As a result, the fixed plate 41A does not rotate any further, and only the screws 42 rotate.

The rotation stoppers 41g and 41h may be divided into several parts such that the apex portions are lined up in the z-axis direction, and may be formed so that each of the plurality of apexes makes point contact with the inner surface of the recess 30.

According to this embodiment, the same effects as in the first embodiment can be obtained by providing the rotation stoppers 41g and 41h on the fixed plate 41A.

(Fourth embodiment)
FIG. 14 is a perspective view of a fixing plate 41B according to a fourth embodiment of the present invention, viewed from below. FIG. 15 is a configuration diagram showing rotation stoppers 41i and 41j provided on the first structure 11 side according to the fourth embodiment of the present invention.

In this embodiment, a fixing plate 41B is provided in place of the fixing plate 41A according to the third embodiment shown in FIG. The fixed plate 41B has a shape in which rotation stoppers 41i and 41j are provided in place of the rotation stoppers 41g and 41h in the fixed plate 41A according to the third embodiment. Other points are similar to the third embodiment. For example, only one of the rotation stoppers 41i and 41j may be provided corresponding to the rotational direction of the screw 42.

The rotation stoppers 41i and 41j are the same as the rotation stoppers 41g and 41h according to the third embodiment except for the difference in surface shape. The surfaces of the rotation stoppers 41i and 41j are formed by bending the plane in two and cutting the cross section so that a vertex extending linearly in the y-axis direction (perpendicular to the torque rotation axis, longitudinal direction of the strain sensor 20) is formed. It has a convex shape that is triangular. Note that the rotation stoppers 41i, 41j may be shaped so that not only the strain sensor 20 side portion of the side surface of the fixed plate 41B but the entire side surface serves as the rotation stoppers 41i, 41j. Moreover, the surfaces of the rotation stoppers 41i and 41j may have a curved surface shape that is a curved plane.

When the fixing plate 41B tries to rotate together with the screws 42, the apex portions of the rotation stoppers 41i and 41j of the fixation plate 41B that extend in the y-axis direction engage with the rotation stoppers 41i and 41j of the recess 30 of the third structure 13. It makes line contact with the opposing inner surface in the y-axis direction. As a result, the fixed plate 41B does not rotate any further, and only the screws 42 rotate. In other respects, the fixed plate 41B functions similarly to the first embodiment.

The rotation stoppers 41i and 41j may be divided into several parts such that the apex portions are lined up in the y-axis direction, and may be formed so that each of the plurality of apexes makes point contact with the inner surface of the recess 30.

According to this embodiment, the rotation stoppers 41i, 41j are provided on the fixed plate 41B, and the rotation stoppers 41i, 41j are brought into contact with the inner surface of the recess 30 in the y-axis direction, thereby achieving the same effect as in the first embodiment. effect can be obtained.

In each of the embodiments, the fixed plates 41 to 41B are brought into line contact or point contact with other parts (structures 11 to 13, etc.) by providing a rotation stopper, but the fixing plates 41 to 41B are not limited to those described here. First, any part of the torque sensor 10 may be contacted.

In addition, the present invention is not limited to the above-mentioned embodiments as they are, and in the implementation stage, the constituent elements can be modified and embodied without departing from the spirit of the invention. Moreover, various inventions can be formed by appropriately combining the plurality of constituent elements disclosed in each of the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components of different embodiments may be combined as appropriate.

DESCRIPTION OF SYMBOLS 10... Torque sensor, 11... First structure, 12... Second structure, 13... Third structure, 21... Strain body, 40a, 40b... Fixing device, 41... Fixing plate, 41a, 51a, 61a, 71a...Body, 41b, 51b, 61b, 71b...Bottom surface, 41c, 51c, 61c...First protrusion, 41d, 51d, 61d...Second protrusion, 41f, 51f, 61f...Opening, 42...Screw, 35a, 35b , 36a, 36b... Rotation stop portion.

Claims (7)

a first side, a second side parallel to the first side, and a surface provided between the first side and the second side and including an opening; a fixing member having one side in contact with a first structure and the second side in contact with an end of a strain-generating body constituting a strain sensor provided on the first structure;
a screw inserted into the opening and screwed into the first structure;
a rotation stopper that brings the fixing member into line contact or point contact with another part and prevents rotation of the fixing member;
The surface is provided at a position away from a line connecting the first side and the second side,
the first side is in line contact or point contact with the first structure,
The second side may be in line contact or point contact with the end of the strain-generating body.
A strain sensor fixing device characterized by : 2. The strain sensor fixing device according to claim 1, wherein the rotation stopper is provided closer to the strain sensor than the center of the opening. 3. The strain sensor fixing device according to claim 2 , wherein the rotation stopper is not provided on a side opposite to the strain sensor from the center of the opening. The strain sensor fixing device according to claim 1, wherein the rotation stopper is provided on the fixing member. The strain sensor fixing device according to claim 1, wherein the rotation stopper is provided in the other portion. The strain sensor fixing device according to claim 1, wherein the rotation stopper includes a screw. a first structure;
a second structure;
a plurality of third structures connecting the first structure and the second structure;
a strain-generating body that constitutes a strain sensor provided between the first structure and the second structure;
a first fixing device provided on the first structure and fixing a first end of the strain body to the first structure;
a second fixing device that is provided on the second structure and fixes the second end of the strain body to the second structure;
Equipped with
Each of the first fixing device and the second fixing device,
a first side, a second side parallel to the first side, and a surface provided between the first side and the second side and including an opening; a fixing member having one side in contact with the first structure and a second side in contact with an end of the strain body provided on the first structure;
a screw inserted into the opening and screwed into the first structure;
a rotation stopper that brings the fixing member into line contact or point contact with another part and prevents rotation of the fixing member;
The surface is provided at a position away from a line connecting the first side and the second side,
the first side is in line contact or point contact with the first structure,
The second side may be in line contact or point contact with the end of the strain-generating body.
A torque sensor featuring :

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