Torque sensor

Abstract

To provide a torque sensor which is configured to efficiently enhance detection sensitivity of torque and rigidity of a sensor.SOLUTION: A torque sensor 1 includes a strain sensor, and an elastic body which is formed into a circular shape and is composed of a plurality of sensors, wherein the elastic body includes: first structures 11 and 21 which are coupled so that the plurality of layers are integrated with each other and are formed into circular shapes; second structures 12 and 22 which are coupled so that the plurality of layers are integrate with each other, are overlapped with at least a part of the first structures 11 and 21 in a direction of a rotary shaft and are formed into circular shapes on inner peripheral sides of the first structures 11 and 21; and a plurality of third structures 13 and 23 for connecting the first structures 11 and 21 and the second structures 12 and 22. The strain sensor is provided on the third structure 13 of a first layer 10, and the third structure 23 of a second layer 20 is configured so that its rigidity to a specific force other than torque becomes higher than that of the third structure 13 of the first layer 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a torque sensor that detects torque. [Background technology]

[0002] A torque sensor is known in which a first structure and a second structure formed in an annular shape are arranged concentrically, and torque is detected by a strain sensor provided between the first structure located on the outside and the second structure located on the inside (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-107207 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a torque sensor, a configuration for increasing the torque detection sensitivity may conflict with a configuration for increasing the rigidity of the entire sensor.

[0005] The present embodiment provides a torque sensor that is configured to efficiently increase the torque detection sensitivity and the rigidity of the sensor. Effect of the Invention

[0006] According to this embodiment, it is possible to provide a torque sensor that is configured to efficiently increase the torque detection sensitivity and the rigidity of the sensor. [Means for solving the problem]

[0007] A torque sensor according to an embodiment of the present invention includes a strain sensor for detecting torque, and an elastic body formed in a circular shape centered on a rotation axis of rotation that generates the torque, and composed of a plurality of layers including a first layer and a second layer, the elastic body including a first structure formed in a circular shape by bonding the plurality of layers together, a second structure formed in a circular shape by bonding the plurality of layers together, the second structure overlapping at least a portion of the first structure in the direction of the rotation axis in each of the plurality of layers, and a plurality of third structures connecting the first structure and the second structure, the strain sensor being provided in the third structure of the first layer, and the third structure of the second layer being configured to have higher rigidity against a specific force other than the torque than the third structure of the first layer. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a top view showing the configuration of a torque sensor according to a first embodiment. [Diagram 2] FIG. 1 is a side view showing a configuration of a torque sensor according to a first embodiment. [Diagram 3] FIG. 2 is a top view showing the configuration of a first layer of the torque sensor according to the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view of the first layer of the torque sensor according to the first embodiment taken along line AA in FIG. 3. [Diagram 5] FIG. 4 is a top view showing the configuration of a second layer of the torque sensor according to the first embodiment. [Figure 6] 6 is a cross-sectional view of the second layer of the torque sensor according to the first embodiment taken along line BB in FIG. 5. [Figure 7] FIG. 4 is a diagram showing the correspondence between the shape and characteristics of a third structure according to the first embodiment. [Figure 8] FIG. 11 is a side view showing a configuration of an elastic body of a torque sensor according to a modified example of the first embodiment. [Figure 9] FIG. 11 is a perspective view showing a configuration of a portion of an elastic body of a torque sensor according to a second embodiment of the present invention. [Figure 10] FIG. 11 is a side view showing the configuration of a portion of an elastic body of a torque sensor according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (First embodiment) Fig. 1 is a top view showing the configuration of a torque sensor 1 according to the first embodiment. Fig. 2 is a side view showing the configuration of the torque sensor 1 according to the present embodiment. In the drawings, the same parts are given the same reference numerals.

[0010] The torque sensor 1 is a sensor that detects torque. The torque to be detected is the moment about the z-axis (rotation axis direction) shown in Fig. 1. Here, the x-axis, y-axis, and z-axis are mutually orthogonal. Note that the torque sensor 1 may be a sensor with a different name, such as a force sensor, as long as it is a sensor that detects at least torque.

[0011] 1, the torque sensor 1 is provided with a plurality of holes for passing screws or the like for fixing. The holes may be provided anywhere in the torque sensor 1, and the number of holes may not be limited, and it does not matter whether or not any holes are provided.

[0012] The torque sensor 1 includes an elastic body composed of a first layer 10 and a second layer 20. The elastic body is formed in a circular shape centered on the axis of rotation that generates the torque to be detected. The first layer 10 is a layer in which a strain sensor is provided, and is configured to have high rigidity against torque while increasing the detection sensitivity of torque (z-axis moment). The second layer 20 is configured to have high rigidity against forces other than torque. Here, the second layer 20 is described as being disposed on the first layer 10, but the first layer 10 may be disposed on the second layer 20.

[0013] Since the first layer 10 is a layer on which the strain sensor is provided, it is desirable that the first layer 10 is made of a material having excellent strength and lifespan. For example, the first layer 10 is made of an iron-based material such as stainless steel. The second layer 20 may be made of any material as long as it has a minimum necessary strength. The second layer 20 may be made of a material different from that of the first layer 10, and a material according to the purpose may be selected. For example, the second layer 20 may be made of a material having a lower density than the material of the first layer 10, thereby making it possible to reduce the overall weight of the torque sensor 1. The second layer 20 may be made of a resin, aluminum, or magnesium alloy, or may be made of the same iron-based material as the first layer 10. The second layer 20 may also be made of the same material as the first layer 10, and may be formed integrally with the first layer 10 in part or in whole.

[0014] Furthermore, the torque sensor 1 includes a configuration for detecting torque, such as a calculation processing unit configured by a computer. The strain sensor provided in the first layer 10 detects strain caused by the relative movement of the first structure 11 and the second structure 12 in the first layer 10. For example, the strain sensor is configured with a sensor element such as a strain gauge provided on the surface of a strain generating body where strain occurs. The sensor element forms an electric circuit such as a full bridge circuit or a bridge circuit. Data indicating the strain detected by the strain sensor is transmitted to the calculation processing unit as an electric signal. The calculation processing unit calculates the applied torque based on the strain detected by the strain sensor.

[0015] Fig. 3 is a top view showing the configuration of the first layer 10 of the torque sensor 1 according to this embodiment. Fig. 4 is a cross-sectional view of the first layer 10 according to this embodiment taken along line AA in Fig. 3. In the cross-sectional view shown in Fig. 4, the left half is a portion including the third structure 13, and the right half is a portion not including the third structure 13, and there are no holes.

[0016] The first layer 10 includes a first structure 11, a second structure 12, and a plurality of third structures 13.

[0017] The first structure 11, the second structure 12, and the third structure 13 are integrally formed. The first structure 11 and the second structure 12 are formed in a circular shape (including annular). The outer diameter of the second structure 12 is smaller than the outer diameter of the first structure 11. The second structure 12 is arranged concentrically with the first structure 11 on the inner periphery side. The second structure 12 does not have to be at exactly the same position (same height) as the first structure 11 in the rotation axis direction, and it is sufficient that the second structure 12 overlaps at least a part of the first structure 11 in the rotation axis direction.

[0018] The multiple third structures 13 are arranged radially and provided as beams connecting the first structure 11 and the second structure 12. The third structures 13 have an overall rectangular parallelepiped shape. For example, four third structures 13 are provided at equal intervals (90 degree intervals) in the circumferential direction. Any number of third structures 13 may be provided.

[0019] The surface of the third structure 13 facing the second layer 20 is formed in a shape that does not contact the third structure 23 of the second layer 20 even when a torque to be detected is applied. For example, a recess D13 shown in Fig. 4 is formed on the surface of the third structure 13 facing the second layer 20. Note that the recess D13 may be formed so as to ensure a space for arranging a strain sensor.

[0020] Fig. 5 is a top view showing the configuration of the second layer 20 of the torque sensor 1 according to this embodiment. Fig. 6 is a cross-sectional view of the second layer 20 according to this embodiment taken along line BB in Fig. 5. In the cross-sectional view shown in Fig. 6, the left half is a portion including the third structure 23, and the right half is a portion not including the third structure 23, and there are no holes.

[0021] The second layer 20 includes a first structure 21, a second structure 22, and a plurality of third structures 23. The first structure 21, the second structure 22, and the third structure 23 of the second layer 20 are formed on the first structure 11, the second structure 12, and the third structure 13 of the first layer 10, respectively.

[0022] The first structure 21, the second structure 22, and the third structure 23 are integrally formed. The first structure 21 and the second structure 22 are formed in a circular shape (including annular). The outer diameter of the second structure 22 is smaller than the outer diameter of the first structure 21. The second structure 22 is arranged concentrically with the first structure 21 on the inner periphery side. The second structure 22 does not have to be at exactly the same position (same height) as the first structure 21 in the rotation axis direction, and it is sufficient that the second structure 22 overlaps at least a part of the first structure 21 in the rotation axis direction.

[0023] The first structure 21 of the second layer 20 is bonded to the first structure 11 of the first layer 10 so as to be integrated with each other. For example, the first structure 21 of the second layer 20 and the first structure 11 of the first layer 10 are firmly bonded with screws or the like. Similarly, the second structure 22 of the second layer 20 is bonded to the second structure 12 of the first layer 10 so as to be integrated with each other.

[0024] The multiple third structures 23 are arranged radially and provided as beams connecting the first structure 21 and the second structure 22. The third structures 23 have an overall rectangular parallelepiped shape. For example, four third structures 23 are provided at equal intervals (90 degree intervals) in the circumferential direction. The number of third structures 23 in the second layer 20 is the same as the number of third structures 13 in the first layer 10.

[0025] The surface of the third structure 23 facing the first layer 10 is formed in a shape that does not contact the third structure 13 of the first layer 10 even when a torque to be detected is applied. For example, a recess D23 shown in Fig. 6 is formed on the surface of the third structure 23 facing the first layer 10. Note that the recess D23 may be formed so as to ensure a space for arranging a strain sensor.

[0026] The thickness of the second layer 20 is greater than the thickness of the first layer 10. In addition, the width (circumferential length) of the third structure 23 of the second layer 20 is shorter than the width of the third structure 13 of the first layer 10. In other respects, the second layer 20 has the same shape as the first layer 10.

[0027] The number of third structures 23 in the second layer 20 may be different from the number of third structures 13 in the first layer 10. Furthermore, the third structures 23 in the second layer 20 do not have to be formed on the third structures 13 in the first layer 10, and may be disposed in positions different from the third structures 13 in the first layer 10. In this case, the recesses D13 of the third structures 13 in the first layer 10 and the recesses D23 of the third structures 23 in the second layer 20 do not have to be provided.

[0028] In addition, the length (radial length) of the third structure 23 in the second layer 20 may not be the same as the length of the third structure 13 in the first layer 10. For example, the length of the third structure 23 in the second layer 20 may be longer or shorter than the length of the third structure 13 in the first layer 10. In addition, in the first layer 10 and the second layer 20, at least one of the two first structures 11, 21 or the two second structures 12, 22 may have a different shape in response to the difference in the shapes of the two third structures 13, 23. For example, the inner peripheral side parts of the two first structures 11, 21 or the outer peripheral side parts of the two second structures 12, 22 may be formed in different shapes according to the shapes of the third structures 13, 23 connected thereto. Specifically, when the lengths of the two third structures 13, 23 are different, at least one of the sizes of the circles corresponding to the inner circumferences of the two first structures 11, 21 or the sizes of the circles corresponding to the outer circumferences of the two second structures 12, 22 may be different.

[0029] A method for designing the shapes of the third structures 13, 23 of the first layer 10 and the second layer 20 will be described with reference to Fig. 7. Fig. 7 shows the relationship between the shapes and characteristics of the third structures 13, 23. The characteristics are the rigidity against an external force or the magnitude of the detected torque output. Here, the length, width, and thickness represent the length (radial length), width (circumferential length), and thickness (length in the direction of the rotation axis) of the third structures 13, 23, respectively.

[0030] To increase the detection output indicating the strength of the torque (z-axis moment) (to increase the detection sensitivity), the length of the third structures 13, 23 is increased, the width of the third structures 13, 23 is narrowed, or the thickness of the third structures 13, 23 is reduced.

[0031] In order to increase the rigidity against torque (z-axis moment), the length of the third structures 13, 23 is shortened, the width of the third structures 13, 23 is increased, or the thickness of the third structures 13, 23 is increased.

[0032] To increase the rigidity against the x-axis moment and the y-axis moment, the length of the third structures 13, 23 is shortened, the width of the third structures 13, 23 is increased, or the thickness of the third structures 13, 23 is increased.

[0033] 7, the circled items indicate those whose characteristics are significantly affected by the amount of change in the shape of the third structures 13, 23. For example, the characteristics change in proportion to approximately the cube of the amount of deformation in the shape of the third structures 13, 23.

[0034] The amount of change in the length of the third structures 13, 23 has a large effect on the magnitude of the torque detection output, the rigidity against torque, the rigidity against the x-axis moment, and the rigidity against the y-axis moment.

[0035] The change in width of the third structures 13, 23 has a large effect on the magnitude of the torque detection output and on the rigidity against torque, but has a small effect on the rigidity against the x-axis moment and the rigidity against the y-axis moment.

[0036] The change in thickness of the third structures 13, 23 has a small effect on the magnitude of the torque detection output and on the rigidity against torque, but has a large effect on the rigidity against the x-axis moment and the rigidity against the y-axis moment.

[0037] From these facts, by adjusting the thickness of the third structures 13, 23, it is possible to adjust the rigidity with respect to the x-axis moment and the y-axis moment while suppressing the influence on the torque detection output and the rigidity with respect to the torque. Also, by adjusting the width of the third structures 13, 23, it is possible to adjust the torque detection output and the rigidity with respect to the torque while suppressing the influence on the rigidity with respect to the x-axis moment and the y-axis moment. Note that by adjusting the length of the third structures 13, 23, it is possible to adjust any characteristic of the third structures 13, 23, but this has a large influence on other characteristics. For this reason, adjusting the length of the third structures 13, 23 is not suitable for adjusting only a specific characteristic of the third structures 13, 23.

[0038] The shapes of the third structural body 13 of the first layer 10 and the third structural body 23 of the second layer 20 are designed as follows.

[0039] A strain sensor for detecting torque is provided in the third structure 13 of the first layer 10. For this reason, the width of the third structure 13 is mainly adjusted so as to balance the two opposing characteristics of the magnitude of the torque detection output and the rigidity against torque. The third structure 13 is formed so as to ensure sufficient rigidity against torque while ensuring the magnitude of the torque detection output at least at a certain level.

[0040] The thickness of the third structure 23 of the second layer 20 is adjusted mainly so as to increase the rigidity against moments other than torque (x-axis moment and y-axis moment). For example, the third structure 23 of the second layer 20 is formed so as to be thicker than the third structure 13 of the first layer 10.

[0041] Furthermore, in order to suppress the effect of the torque on the magnitude of the detection output, the third structure 23 of the second layer 20 is formed to be narrower than the third structure 13 of the first layer 10. It is desirable that the third structure 23 of the second layer 20 is formed to have a lower rigidity against torque than the third structure 13 of the first layer 10 in which the strain sensor is provided.

[0042] Here, the third structure 23 of the second layer 20 is configured to have high rigidity against the x-axis moment and the y-axis moment, but may be configured to have high rigidity against a specific force other than torque, not limited to the x-axis moment and the y-axis moment. For example, the third structure 23 of the second layer 20 may be configured to have high rigidity against translational forces of the x-axis, y-axis, and z-axis.

[0043] 8, the elastic body of the torque sensor 1a according to the modified example of this embodiment may be composed of three layers 10, 20, and 30. The order in which the first layer 10, the second layer 20, and the third layer 30 are laminated may be changed to any order.

[0044] The third layer 30 can have any role. The third layer 30 may have the same role as the first layer 10 or the second layer 20, or may have a different role from the first layer 10 and the second layer 20. The third layer 30 may or may not be provided with a strain sensor for detecting torque. The third layer 30 may have the same shape as the first layer 10 or the second layer 20, or may have a different shape from the first layer 10 and the second layer 20. The third layer 30 may be made of the same material as the first layer 10 or the second layer 20, or may be made of a different material from the first layer 10 and the second layer 20.

[0045] The third structure of the third layer 30 may have rigidity against any specific force. When a strain sensor is provided in the third structure of the third layer 30, the third structure of the third layer 30 is formed to ensure sufficient rigidity against torque while ensuring a certain level of torque detection output, similar to the third structure 13 of the first layer 10. When a strain sensor is not provided in the third structure of the third layer 30, the third structure of the third layer 30 may be configured to have high rigidity against the same force as the third structure 23 of the second layer 20, or may be configured to have high rigidity against a force different from that of the third structure 23 of the second layer 20.

[0046] The elastic body of the torque sensor 1 may be formed of four or more layers. Moreover, in the elastic body of the torque sensor 1, only the third structures 13, 23 acting as beams may be formed of two or more layers, and the portions corresponding to the first structures 11, 21 and the second structures 12, 22 may be formed of one layer.

[0047] According to this embodiment, the elastic body of the torque sensor 1 is formed of two layers 10, 20: a first layer 10 that provides a strain sensor for detecting torque, and a second layer 20 that increases rigidity against forces other than torque (e.g., x-axis moment and y-axis moment), making it easy to adjust the torque detection sensitivity and the rigidity of the elastic body separately.

[0048] The third structure 13 of the first layer 10 and the third structure 23 of the second layer 20 are configured not to come into contact with each other even when the torque to be detected is applied, so that the third structure 13 of the first layer 10 elastically deforms due to the torque without being affected by the elastic deformation of the third structure 23 of the second layer 20. This allows the strain sensor provided in the third structure 13 of the first layer 10 to accurately detect strain due to torque.

[0049] For example, the third structure 13 of the first layer 10 and the third structure 23 of the second layer 20 can be configured not to come into contact with each other even when the torque to be detected is applied by providing recesses D13, D23 on their respective opposing surfaces. In addition, by forming the recesses D13, D23 so as to ensure a space in which the strain sensor can be disposed, the strain sensor can be disposed in the third structure 13 of the first layer 10 below or in the vicinity of the third structure 23 of the second layer 20.

[0050] By bonding the first structures 11, 21 of the first layer 10 and the second layer 20 integrally and bonding the second structures 12, 22 of the first layer 10 and the second layer 20 integrally, the first structures 11, 21 of the layers 10, 20 and the second structures 12, 22 of the layers 10, 20 undergo elastic deformation equivalent to that of an elastic body formed as a single unit when a torque to be detected is applied. Also, by creating an elastic body for each of the layers 10, 20, a simpler manufacturing method can be adopted than creating an elastic body as a single unit.

[0051] In the first layer 10 and the second layer 20, respectively, the first structures 11, 21 are configured to overlap at least a portion of the second structures 12, 22 in the rotational axis direction, thereby making it possible to reduce the size (height) of the torque sensor 1 in the rotational axis direction.

[0052] Second embodiment Fig. 9 is a perspective view showing a configuration of a portion of an elastic body of a torque sensor 1A according to a second embodiment of the present invention, and Fig. 10 is a cross-sectional view showing a configuration of a portion of an elastic body of the torque sensor 1A according to the present embodiment.

[0053] The torque sensor 1A according to this embodiment is obtained by changing the configuration for forming the elastic body from the two layers 10, 20 to three layers 10A, 20A, 30A in the torque sensor 1 according to the first embodiment, and by changing the shape of the elastic body. In other respects, the torque sensor 1A is similar to the torque sensor 1 according to the first embodiment.

[0054] The torque sensor 1A includes a first layer 10A, a second layer 20A, and a third layer 30A. The first layer 10A is configured similarly to the first layer 10 according to the first embodiment. The second layer 20A is configured similarly to the second layer 20 according to the first embodiment. The third layer 30A is configured similarly to the second layer 20A according to the present embodiment, except for the position where the third layer 30A is disposed. The thickness of the first layer 10A is thinner than the thicknesses of the second layer 20A and the third layer 30A. The thickness of the second layer 20A and the thickness of the third layer 30A may be the same or different.

[0055] The first layer 10A, the second layer 20A, and the third layer 30A are bonded to form one elastic body. The second layer 20A is bonded on top of the first layer 10A, and the third layer 30A is bonded below the first layer 10A. That is, the first layer 10A is sandwiched between the second layer 20A and the third layer 30A. The order in which the first layer 10A, the second layer 20A, and the third layer 30A are laminated may be changed to any order.

[0056] The first layer 10A includes a first structure 11A, a second structure 12A, and a plurality of third structures 13A. The first structure 11A, the second structure 12A, and the plurality of third structures 13A correspond to the first structure 11, the second structure 12, and the plurality of third structures 13 of the first layer 10 according to the first embodiment, respectively.

[0057] The second layer 20A includes a first structure 21A, a second structure 22A, and a plurality of third structures 23A. The first structure 21A, the second structure 22A, and the plurality of third structures 23A correspond to the first structure 21, the second structure 22, and the plurality of third structures 23 of the second layer 20 according to the first embodiment, respectively.

[0058] The third layer 30A includes a first structure 31A, a second structure 32A, and a plurality of third structures 33A. The first structure 31A, the second structure 32A, and the plurality of third structures 33A are configured similarly to the first structure 21A, the second structure 22A, and the plurality of third structures 23A of the second layer 20A according to this embodiment, respectively.

[0059] The first structures 11A, 21A, 31A of each layer 10A, 20A, 30A do not have to be at exactly the same position (same height) as the second structures 12A, 22A, 32A of the same layer in the rotation axis direction, but the first structures 11A, 21A, 31A of each layer 10A, 20A, 30A only need to overlap at least a portion of the second structures 12A, 22A, 32A of the same layer in the rotation axis direction.

[0060] The first structures 11A, 21A, 31A of each layer 10A, 20A, 30A are bonded together to be integrated. Similarly, the second structures 12A, 22A, 32A of each layer 10A, 20A, 30A are bonded together to be integrated. For example, the first structures 11A, 21A, 31A or the second structures 12A, 22A, 32A of each layer 10A, 20A, 30A are firmly bonded together by screws or the like.

[0061] Figures 9 and 10 show a cut-out configuration of the elastic third structures 13A, 23A, and 33A of the torque sensor 1A. Figure 10 shows a cross section of the configuration shown in Figure 9 cut in half in the longitudinal direction. The torque sensor 1A differs from the torque sensor 1 according to the first embodiment mainly in the third structures 13A, 23A, and 33A.

[0062] The first structures 11A, 21A, 31A and the second structures 12A, 22A, 32A are circular in shape as in the first embodiment. The torque sensor 1A is provided with holes for fixing as in the first embodiment, but the holes may be provided anywhere in the torque sensor 1, and the number of holes may not be limited, or may not be provided at all.

[0063] The third structure 13A of the first layer 10A is provided with a strain sensor for detecting torque. Therefore, the third structure 13A of the first layer 10A is formed to ensure sufficient rigidity against torque while ensuring a certain level of torque detection output. The third structures 23A and 33A of the second layer 20A and the third layer 30A are formed to have high rigidity against moments other than torque.

[0064] For example, taking into consideration the relationship between the characteristics and the shape shown in Fig. 7, the third structural body 13A of the first layer 10A is formed to have a smaller thickness (length in the z-axis direction), a longer length (length in the radial direction), and a wider width (length in the circumferential direction) than the third structural bodies 23A, 33A of the second layer 20A and the third layer 30A. Note that the length of the third structural body 13A of the first layer 10A may be the same as or shorter than the length of the third structural bodies 23A, 33A of the second layer 20A and the third layer 30A.

[0065] The upper surface of the third structure 13A of the first layer 10A and the lower surface of the third structure 23A of the second layer 20A are configured not to come into contact with each other even when the torque to be detected is applied, as in the first embodiment. Similarly, the lower surface of the third structure 13A of the first layer 10A and the upper surface of the third structure 33A of the third layer 30A are configured not to come into contact with each other even when the torque to be detected is applied. As a result, the third structure 13A of the first layer 10A elastically deforms due to torque without being affected by the elastic deformation of the third structure 23A of the second layer 20A and the third structure 33A of the third layer 30A. Therefore, the strain sensor provided in the third structure 13A of the first layer 10A can accurately detect the strain due to torque.

[0066] For example, the third structure 13A of the first layer 10A and the third structure 23A of the second layer 20A can be configured to not come into contact with each other even when the torque to be detected is applied by providing recesses D13a and D23 on their respective opposing surfaces. Similarly, the third structure 13A of the first layer 10A and the third structure 33A of the third layer 30A can be configured to not come into contact with each other even when the torque to be detected is applied by providing recesses D13b and D33 on their respective opposing surfaces.

[0067] The recesses D13a, D13b, D23, and D33 may be formed so as to secure a space in which the strain sensor can be disposed. For example, the recesses D13a, D13b, D23, and D33 may be formed so as to allow the strain sensor to be disposed in the third structure 13A of the first layer 10A, below the third structure 23A of the second layer 20A, above the third structure 33A of the third layer 30A, or in the vicinity of these.

[0068] According to this embodiment, the elastic body of the torque sensor 1A is formed of three layers 10A, 20A, and 30A, namely, a first layer 10A having a strain sensor for detecting torque, and a second layer 20A and a third layer 30A for increasing the rigidity against moments other than torque, so that the torque detection sensitivity and the rigidity of the elastic body can be easily adjusted separately. In addition, the lengths of the third structures 13A, 23A, and 33A of the layers 10A, 20A, and 30A can be adjusted separately to adjust the balance of the overall characteristics of the elastic body.

[0069] By providing recesses D13a, D13b, D23, D33 on the surfaces of the third structures 13A, 23A, 33A of the elastic layers 10A, 20A, 30A of the torque sensor 1A, the third structure 13A of the first layer 10A in which the strain sensor is provided does not come into contact with the third structures 23A, 33A of the adjacent second layer 20A or third layer 30A even when a torque to be detected is applied. Therefore, even if the third structures 13A, 23A, 33A are configured in multiple layers, the third structure 13A of the first layer 10A elastically deforms upon application of torque without coming into contact with the third structures 23A, 33A of the other layers, and the torque sensor 1A can accurately detect torque.

[0070] In addition, by providing recesses D13a, D13b, D23, D33 on the surfaces of the third structures 13A, 23A, 33A of each layer 10A, 20A, 30A of the elastic body of the torque sensor 1A, the strain sensor can be positioned at any location of the third structure 13A of the first layer 10A.

[0071] For example, if the third structures 13A, 23A, 33A of the layers 10A, 20A, 30A are integrally formed and the recesses D13a, D13b, D23, D33 are not provided, in the third structure 13A of the first layer 10A, a strain sensor cannot be provided below the third structure 23A of the second layer 20A, and further, a strain sensor cannot be provided near the bottom of the third structure 23A of the second layer 20A because the third structure 23A of the second layer 20A becomes an obstacle. Similarly, in the third structure 13A of the first layer 10A, a strain sensor cannot be provided above or near the third structure 33A of the third layer 30A.

[0072] In each of the layers 10A, 20A, 30A, the first structures 11A, 21A, 31A are configured to overlap at least a portion of the second structures 12A, 22A, 32A in the rotational axis direction, thereby making it possible to reduce the size (height) of the torque sensor 1A in the rotational axis direction.

[0073] However, additional advantages and modifications may readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific detailed representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0074] 1...torque sensor, 10...first layer, 11...first structure, 12...second structure, 13...third structure, 20...second layer, 21...first structure, 22...second structure, 23...third structure.

Claims

1. A strain sensor for detecting torque; an elastic body formed in a circular shape centered on a rotation axis of the rotation that generates the torque and configured with a plurality of layers including a first layer and a second layer; The elastic body is a first structure in which the plurality of layers are integrally bonded and formed into a circular shape; the plurality of layers are bonded together so as to be integrated, and each of the plurality of layers overlaps at least a portion of the first structure in the direction of the rotation axis, and a second structure is formed in a circular shape on the inner circumferential side of the first structure; a plurality of third structures connecting the first structure and the second structure; the strain sensor is provided in the third structure of the first layer, The third structure of the second layer is configured to have higher rigidity against a specific force other than the torque than the third structure of the first layer. A torque sensor comprising:

2. The third structure of the second layer is configured to have a lower rigidity against the torque than the third structure of the first layer.

2. The torque sensor according to claim 1 .

3. The specific force is a moment other than the torque.

2. The torque sensor according to claim 1 .

4. The third structure of the first layer has a smaller thickness and a larger width, which is a length in a circumferential direction, than the third structure of the second layer.

2. The torque sensor according to claim 1 .

5. The third structure of the first layer has a different radial length from the third structure of the second layer.

2. The torque sensor according to claim 1 .

6. the first layer is formed of an iron-based material; The second layer is formed of a material different from that of the first layer.

2. The torque sensor according to claim 1 .

7. The second layer is formed of a material having a lower density than the material of the first layer.

2. The torque sensor according to claim 1 .

8. The third structure of the first layer and the third structure of the second layer are formed in a shape that does not contact each other even when the torque is applied.

2. The torque sensor according to claim 1 .

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