Torque sensor
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- MINEBEAMITSUMI INC
- Filing Date
- 2025-08-28
- Publication Date
- 2026-07-30
Smart Images
Figure JP2025030370_30072026_PF_FP_ABST
Abstract
Description
Torque sensor
[0001] This invention relates to a torque sensor.
[0002] Torque sensors that have a strain-generating element are known. For example, Patent Document 1 discloses a bicycle torque sensor that has a sensor element having a specific shape and with a strain gauge attached to its outer surface.
[0003] Japanese Patent Publication No. 2000-193540
[0004] In torque sensors having a strain-generating element, there is room for improvement in the structure and fixing method of the strain-generating element. One example of the objectives of the present invention is to provide a torque sensor that can be fixed with a simple structure.
[0005] In one embodiment of the present invention, the torque sensor comprises, for example, a shaft, a strain generating body connected to the shaft, and a housing supporting the strain generating body, wherein the strain generating body has portions fixed to the housing in the axial and radial directions, and the portions of the strain generating body have a first surface facing an axially extending surface of the housing and a second surface facing a radially extending surface of the housing. In another embodiment of the present invention, the torque sensor comprises, for example, a shaft, a strain-generating body connected to the shaft, and a housing supporting the strain-generating body, wherein the strain-generating body has a portion fixed to the housing in the radial direction, the portion of the strain-generating body has a first surface facing an axially extending surface of the housing, the first surface of the strain-generating body has a portion projecting toward the axially extending surface of the housing, the portion of the first surface of the strain-generating body is in contact with the axially extending surface of the housing, and the other portion is away from the axially extending surface of the housing, and in the axial direction, the portion of the first surface of the strain-generating body and the other portion of the first surface of the strain-generating body are aligned.
[0006] This is a view of a part of the configuration of the torque sensor according to the first embodiment, as seen in the axial direction. This is a perspective view showing a part of the configuration of the torque sensor according to the first embodiment. This is a cross-sectional view showing a part of the configuration of the torque sensor according to the first embodiment. This is a cross-sectional view of the torque sensor according to the first embodiment. This is a view of a part of the torque sensor in Figure 4. This is a perspective view of the case of the torque sensor according to the first embodiment. This is a view of the frame of the torque sensor according to the first embodiment, as seen in the axial direction. This is a perspective view showing a part of the configuration of the torque sensor according to the second embodiment. This is a cross-sectional of the torque sensor according to the second embodiment. This is a view of a part of the torque sensor in Figure 10.
[0007] In describing embodiments of the present invention, for convenience of explanation, the direction along the rotation axis X of the shaft S is referred to as the rotation axis direction or axial direction. In the axial direction, the direction of arrow a is referred to as one side, and the direction of arrow b is referred to as the other side. The directions of arrows cd perpendicular to the rotation axis X are referred to as the radial direction. In the radial direction, the direction of arrow c moving away from the rotation axis X is referred to as the outside or one side, and the direction of arrow d moving towards the rotation axis X is referred to as the inside or the other side. In a certain member or part, the outer surface in the radial direction may be referred to as the outer circumferential surface, and the inner surface in the radial direction may be referred to as the inner circumferential surface. In a certain member or part, the outer part in the radial direction may be referred to as the outer circumferential portion, and the inner part in the radial direction may be referred to as the inner circumferential portion. The direction of rotation around the rotation axis X is referred to as the circumferential direction.
[0008] [First Embodiment] Hereinafter, a first embodiment, which is an example of the present invention, will be described with reference to the drawings. Figure 1 is a view of the torque sensor 1 according to this embodiment in the axial direction. However, the case 30 is omitted in Figure 1. Figure 2 is a perspective view of the sensor device 10 provided in the torque sensor 1. Figure 3 is a cross-sectional view of the sensor device 10 along the rotation axis X. Figure 4 is a cross-sectional view of the torque sensor 1 along the rotation axis X. Figure 5 is an enlarged view of a part of Figure 4. Figures 3, 4 and 5 are cross-sectional views corresponding to the A-A cross-section in Figure 1. Figure 6 is a perspective view of the case 30 of the housing 40. Figure 7 is a view of the frame 20 of the housing 40 in the axial direction.
[0009] As shown in Figures 1 and 4, the torque sensor 1 comprises a shaft S, a sensor device 10 having a strain-generating body 101 connected to the shaft S, and a housing 40 (frame 20 and case 30) supporting the strain-generating body 101. The shaft S may be a bicycle crankshaft or a rod connected to a crankshaft. The shaft S rotates around a rotation axis X. The frame 20 and case 30 form a housing 40 that accommodates the sensor device 10.
[0010] The sensor device 10 includes a strain-generating body 101. The material of the strain-generating body 101 is not particularly limited. The material of the strain-generating body 101 may be, for example, steel, stainless steel, aluminum alloy, titanium, plastic, carbon fiber reinforced plastic, ceramic, or other metallic or non-metallic material. The strain-generating body 101 has a deformable surface 101a that extends in the radial direction. As shown in Figures 1 and 2, the deformable surface 101a of the strain-generating body 101 has a first portion 101a1, a second portion 101a2, and a third portion 101a3. As will be described later, the first portion 101a1, the second portion 101a2, and the third portion 101a3 are arranged at a predetermined interval in the circumferential direction.
[0011] Multiple strain sensors 103s are attached to the strain generating body 101. The multiple strain sensors 103s include a first strain sensor 103s1, a second strain sensor 103s2, and a third strain sensor 103s3. The first strain sensor 103s1 is attached to a first portion 101a1 of the deformable surface 101a of the strain generating body 101. The second strain sensor 103s2 is attached to a second portion 101a2 of the deformable surface 101a of the strain generating body 101. The third strain sensor 103s3 is attached to a third portion 101a3 of the deformable surface 101a of the strain generating body 101. The first strain sensor 103s1, the second strain sensor 103s2, and the third strain sensor 103s3 are arranged at predetermined intervals in the circumferential direction.
[0012] In the circumferential direction, the angles formed by the rotation axis X, the first portion 101a1, and the second portion 101a2, and the angles formed by the rotation axis X, the first portion 101a1, and the third portion 101a3 are both obtuse angles. In the present embodiment, the angle formed by the rotation axis X, the second portion 101a2, and the third portion 101a3 is also an obtuse angle. Here, the "angle formed by the rotation axis X, the first portion 101a1, and the second portion 101a2" refers to the angle formed by a virtual line segment along the radial direction connecting the rotation axis X and the center (the central position in the circumferential direction) of the first strain sensor 103s1, and a virtual line segment along the radial direction connecting the rotation axis X and the center (the central position in the circumferential direction) of the second strain sensor 103s2 (the angle θ in FIG. 1 １ ). Similarly, the "angle formed by the rotation axis X, the second portion 101a2, and the third portion 101a3" refers to the angle formed by a virtual line segment along the radial direction connecting the rotation axis X and the center (the central position in the circumferential direction) of the second strain sensor 103s2, and a virtual line segment along the radial direction connecting the rotation axis X and the center (the central position in the circumferential direction) of the third strain sensor 103s3 (the angle θ in FIG. 1 ２ ), and the "angle formed by the rotation axis X, the first portion 101a1, and the third portion 101a3" refers to the angle formed by a virtual line segment along the radial direction connecting the rotation axis X and the center (the central position in the circumferential direction) of the first strain sensor 103s1, and a virtual line segment along the radial direction connecting the rotation axis X and the center (the central position in the circumferential direction) of the third strain sensor 103s3 (the angle θ in FIG. 1 ３ ).
[0013] The angle θ １ and the angle θ ３ may be, for example, within the range of 95° to 150°, may be within the range of 100° to 140°, or may be within the range of 110° to 130°. In the illustrated embodiment, the angle θ １ and the angle θ ３ are both 120°. The difference (absolute value) between the angle θ １ and the angle θ ３ may be, for example, 30° or less, may be 15° or less, or may be 5° or less. In the illustrated embodiment, the difference between the angle θ １ and the angle θ ３ is 0°.
[0014] Angle θ ２ For example, it may be in the range of 60° to 170°, in the range of 100° to 140°, or in the range of 110° to 130°. In the illustrated form, angle θ ２ The angle is 120°. That is, in the illustrated configuration, the first strain sensor 103s1, the second strain sensor 103s2, and the third strain sensor 103s3 are arranged at equal intervals in the circumferential direction.
[0015] The multiple strain sensors 103s may include one, two, or four or more strain sensors. If the number of strain sensors included in the multiple strain sensors 103s is n (where n is a natural number), the n strain sensors may be arranged at intervals of (360 / n)° in the circumferential direction. For example, four strain sensors may be arranged at intervals of 90° in the circumferential direction.
[0016] As shown in Figure 1, the frame 20 of the torque sensor 1 has portions h1, h2, and h3 for connecting to an external device (for example, a bicycle). The portions h1, h2, and h3 for connecting to an external device may be holes for inserting fastening members such as bolts. In the circumferential direction, one of the portions h1, h2, and h3 for connecting to an external device is located between the first portion 101a1 and the second portion 101a2, or between the second portion 101a2 and the third portion 101a3. In the illustrated configuration, in the circumferential direction, the portion h1 for connecting to an external device is located between the first portion 101a1 and the second portion 101a2, the portion h2 for connecting to an external device is located between the second portion 101a2 and the third portion 101a3, and the portion h3 for connecting to an external device is located between the third portion 101a3 and the first portion 101a1. These parts h1, h2, and h3 that connect to external devices are formed as portions that protrude outward (radially) from the outer circumference of the frame 20. Note that the parts h1, h2, and h3 that connect to external devices may also be holes formed in the outer circumference of the frame 20. However, the number of parts that connect to external devices may be one, two, or four or more.
[0017] Next, the configuration of the sensor device 10 will be described in detail with reference to Figures 2 and 3. The sensor device 10 comprises a strain generating body 101, a bearing 102, a plurality of strain sensors 103s, a ring 104, and a substrate 105. The bearing 102 rotatably supports the shaft S relative to the strain generating body 101.
[0018] In this embodiment, the bearing 102 is a ball bearing having an inner ring 102i and an outer ring 102o. The bearing 102 is not limited to a ball bearing, and may be any other type of bearing, such as a sleeve bearing. In the drawing, the bearing 102 is shown as a shielded bearing, but the bearing 102 does not have to have a shield. The ring 104 is configured to rotate together with the inner ring 102i of the bearing 102. Multiple strain sensors 103s and the substrate 105 are electrically connected.
[0019] As shown in Figure 3, the strain generating body 101 has an inner circumference 110 that holds the bearing 102, an outer portion (outer circumference 120) that surrounds the inner circumference 110 in the radial direction, and a connecting portion 130 that connects the inner circumference 110 and the outer circumference 120. As shown in Figure 4, the outer circumference 120 of the strain generating body 101 is the portion that is fixed to the housing 40. As will be described later, the connecting portion 130 is the portion that extends from the inner circumference 110 of the strain generating body 101 toward the outer circumference 120, and in this embodiment it is formed as a plate-like portion (plate).
[0020] The inner circumference 110 of the strain generating body 101 supports the shaft S via a bearing 102. The inner circumference 110 comprises a first portion 111 extending toward the shaft S and a cylindrical second portion 112 extending in the axial direction. In the axial direction, the first portion 111 is provided at one end of the inner circumference 110 (in the direction of arrow a). The second portion 112 has a cylindrical shape around the rotation axis X and has an inner circumference 110i.
[0021] In the radial direction, the bearing 102 is positioned inside (in the direction of arrow d) the second portion 112 of the inner circumference 110 of the strain body 101. The inner ring 102i of the bearing 102 is fixed to the outer circumferential surface of the shaft S by adhesive or press-fitting. The outer ring 102o of the bearing 102 is fixed to the inner circumferential surface 110i of the inner circumference 110 of the strain body 101 by adhesive or press-fitting. The first portion 111 of the inner circumference 110 of the strain body 101 is in contact with the end face of the outer ring 102o of the bearing 102o on one side in the axial direction (in the direction of arrow a). The first portion 111 and the second portion 112 of the inner circumference 110 of the strain body 101 house the bearing 102 from one side in the axial direction and the outside in the radial direction, or surround the bearing 102 from one side in the axial direction and the outside in the radial direction, thereby restricting the movement of the bearing 102.
[0022] In the axial direction, a plate-shaped, annular connecting portion 130 is connected to one end of the inner circumference portion 110 (in the direction of arrow a). The connecting portion 130 extends outward in the radial direction. In the radial direction, the outer circumference portion 120 is connected to the outside of the connecting portion 130. Therefore, the connecting portion 130 connects the inner circumference portion 110 and the outer circumference portion 120 in the radial direction. The connecting portion 130 is elastic and easily deformed with strain, partly due to the shape of the gap 140 described later. Deformation here includes curving and twisting in the directions of arrows a, b, c, and d. In the axial direction, the surface of the connecting portion 130 facing one side (in the direction of arrow a) is the deformable surface 101a of the strain-generating body 101. In the radial direction, the deformable surface 101a of the strain-generating body 101 is located between the inner circumference portion 110 and the outer circumference portion 120.
[0023] The outer periphery 120 is the portion fixed to the housing 40 in the axial and radial directions. The outer periphery 120 has a bent shape and a substantially L-shaped cross-section. The outer periphery 120 is curved along the circumferential direction. As shown in Figure 2, the strain generating body 101 comprises three outer periphery 120s. In this embodiment, the three outer periphery 120s are arranged in positions that are three times symmetrical around the rotation axis X. That is, the three outer periphery 120s are arranged at predetermined intervals in the circumferential direction. In this embodiment, the three outer periphery 120s are arranged at 120° intervals in the circumferential direction. The arrangement of each of the three outer periphery 120s corresponds to the arrangement of the first portion 101a1, the second portion 101a2, and the third portion 101a3 of the deformable surface 101a of the strain generating body 101.
[0024] The strain-generating body 101 may include one, two, or four or more outer periphery portions 120. If the number of outer periphery portions 120 is m (where m is a natural number), the m outer periphery portions 120 may be arranged at intervals of (360 / m)° in the circumferential direction. For example, four outer periphery portions 120 may be arranged at intervals of 90° in the circumferential direction.
[0025] As shown in Figure 3, the outer periphery 120 has a projection 121 extending in the axial direction and a flange 122 extending in the radial direction. The projection 121 extends from the radial outer end of the connecting portion 130 toward the other side in the axial direction (direction of arrow b). The flange 122 extends radially outward from the other end of the projection 121 in the axial direction (direction of arrow b).
[0026] As shown in Figure 3, in the radial direction, the inner circumference 110 and the outer circumference 120 face each other with a gap 140 in between. In the axial direction, the gap 140 is formed on the other side of the connecting portion 130 (in the direction of arrow b). Due to the presence of the gap 140, the inner circumference 110 and the outer circumference 120 are separated by a predetermined distance in the radial direction. The gap 140 is formed to be a curved space along the circumferential direction.
[0027] Multiple strain sensors 103s are provided on the deformable surface 101a of the strain generating body 101 to detect the strain on the deformable surface 101a. Each of the multiple strain sensors 103s is positioned in the portion to which the outer periphery 120 is connected.
[0028] The first strain sensor 103s1, the second strain sensor 103s2, and the third strain sensor 103s3, each included in the plurality of strain sensors 103s, are mounted on a deformable surface 101a such that the orientation of the grid (not shown) is in a predetermined direction (for example, radial, circumferential, or oblique to the radial direction, oblique to the circumferential direction, etc.). The first strain sensor 103s1, the second strain sensor 103s2, and the third strain sensor 103s3 may each have multiple grids with different orientations. The first strain sensor 103s1, the second strain sensor 103s2, and the third strain sensor 103s3 may each be strain gauges. Strain gauges can detect surface strain as a change in resistance. The plurality of strain sensors 103s may also be various other sensors such as resistive elements and piezoelectric elements.
[0029] As shown in Figure 2, an annular substrate 105 is positioned on the deformable surface 101a of the strain body 101. The substrate 105 is, for example, a flat printed circuit board (PCB) on which circuits and electronic components (neither shown) are arranged. The substrate 105 is positioned between the strain body 101 and a plurality of strain sensors 103s. As shown in Figure 3, the substrate 105 surrounds the ring 104 from the outside in the radial direction. The substrate 105 extends parallel or substantially parallel to the deformable surface 101a of the strain body 101. The substrate 105 has a surface (front) 105a and a surface (back) 105b. In the axial direction, surface 105a faces one side (direction of arrow a) and surface 105b faces the other side (direction of arrow b). Surfaces 105a and 105b extend radially.
[0030] In the axial direction, a plurality of strain sensors 103s are arranged between the substrate 105 and the strain generating body 101. The substrate 105 and the plurality of strain sensors 103s are electrically connected by a conductive member or the like (not shown).
[0031] As shown in Figure 2, a sensor 105s is positioned on the surface 105a of the substrate 105. The sensor 105s is attached to the inner edge of the substrate 105 in the radial direction. As will be described later, this inner edge of the substrate 105 or the sensor 105s is positioned in a location that overlaps in the axial direction with the position (in the radial direction) of the outer ring 102o of the bearing 102 or the position (in the radial direction) of the second portion 112 of the inner circumference 110 of the strain generating body 101. In particular, the sensor 105s is positioned in the axial direction facing the outer ring 102o of the bearing 102 or the second portion 112 of the inner circumference 110 of the strain generating body 101 via the substrate 105. The sensor 105s is a sensor capable of detecting magnetic flux and may be, for example, a Hall element, a Hall IC, or a magnetoresistive element. The sensor 105s detects the magnetic flux or change in magnetic flux of the magnet M, which will be described later and is positioned in the ring 104, in the radial direction. The sensor 105s is positioned radially opposite the magnet M. The substrate 105 is provided with, for example, a circuit (not shown) for amplifying signals from the sensor 105s and a plurality of strain sensors 103s and communicating with the outside.
[0032] The ring 104 is an annular member that surrounds the shaft S from the outside in the radial direction. In the radial direction, the ring 104 is positioned inside the substrate 105. In the radial direction, the ring 104 and the substrate 105 are separated by a predetermined distance. The ring 104 and the substrate 105 have overlapping positions in the axial direction and face each other in the radial direction.
[0033] As shown in Figure 3, the ring 104 comprises a flange 104a extending radially outward, a plate portion 104b extending radially inward, and a cylindrical portion 104c. The cylindrical portion 104c is a cylindrical part extending axially. The flange 104a and the plate portion 104b are connected to the cylindrical portion 104c. In the axial direction, the flange 104a is positioned to one side (in the direction of arrow a) of the plate portion 104b.
[0034] An annular, plate-shaped magnet M is arranged on the ring 104. In the axial direction, the magnet M is attached to one side of the flange 104a (direction of arrow a). The magnet M is arranged coaxially with the shaft S. The magnet M is, for example, alternately magnetized in the circumferential direction, and the inner surface of the magnet M has multiple sets of two different magnetic poles (N pole, S pole) arranged alternately. The positions of the magnet M and the sensor 105s, which is placed on the substrate 105, overlap in the axial direction. In the radial direction, the distance between the magnet M and the sensor 105s is within the range in which the sensor 105s can detect the magnetic flux of the magnet M. Note that the magnet M does not have to be annular, and may be multiple magnets M arranged in an annular shape. In this case, the inner surfaces of two adjacent magnets M have different magnetic poles. In this case, the magnet M may be attached to one or more locations in the circumferential direction of the ring 104. The sensor device 10 can detect the rotational speed or rotational position of the shaft S using the sensor 105s and the magnet M. However, the presence of the sensor 105s, ring 104, and magnet M in the sensor device 10 is optional. Furthermore, if the sensor 105s can detect magnetic flux, a magnet M magnetized in the axial direction, or multiple magnets M arranged in a ring shape may be used.
[0035] In the axial direction, the ring 104 is disposed on one side of the bearing 102 (in the direction of arrow a). The inner ring 102i of the bearing 102 protrudes axially on one side (in the direction of arrow a) more than the outer ring 102o. The plate portion 104b and the cylindrical portion 104c of the ring 104 are connected to the inner ring 102i of the bearing 102. Thereby, the ring 104 rotates together with the inner ring 102i of the bearing 102.
[0036] Next, with reference to FIGS. 4 to 7, how the sensor device 10 is housed in the housing 40 (the frame 20 and the case 30) will be described in detail. As shown in FIG. 4, in the axial direction, the sensor device 10 is housed between the frame 20 and the case 30. The materials of the frame 20 and the case 30 are not particularly limited. The materials of the frame 20 and the case 30 may be, for example, aluminum alloy, magnesium alloy, steel, stainless steel, plastic, carbon fiber reinforced plastic, metal matrix composite, or other metal or non-metal materials. The material of the frame 20 may be the same as or different from the material of the case 30.
[0037] In the radial direction, the shaft S is surrounded by the sensor device 10, the frame 20, and the case 30. The shaft S has a portion Sa supported by the bearing 102. A groove Sb extending in the circumferential direction is formed in the portion Sa of the shaft S. The portion Sa of the shaft S is fixed to the inner ring 102i of the bearing 102 on one side (in the direction of arrow a) and the other side (in the direction of arrow b) of the groove Sb in the axial direction. The shaft S has an annular portion Sc protruding outward in the radial direction. In the axial direction, the annular portion Sc is in contact with the end face on the other side (in the direction of arrow b) of the inner ring 102i of the bearing 102.
[0038] The frame 20 includes a bottom portion 21, an inner wall 22, and an outer wall 23. In the axial direction, the sensor device 10 is disposed on one side (in the direction of arrow a) of the bottom portion 21 of the frame 20. A hole 21h through which the shaft S is inserted is formed in the bottom portion 21 of the frame 20. The inner wall 22 and the outer wall 23 of the frame 20 project from the bottom portion 21 in one side (in the direction of arrow a) in the axial direction. The outer wall 23 of the frame 20 extends in the axial direction and is formed in a cylindrical shape. In the radial direction, the outer peripheral portion 120 (the protruding portion 121 and the flange 122) of the strain generating body 101 of the sensor device 10 is disposed between the inner wall 22 and the outer wall 23 of the frame 20.
[0039] The case 30 is a member that covers the sensor device 10 and the frame 20 from one side (in the direction of arrow a) in the axial direction. The case 30 includes a lid 31 that faces the bottom portion 21 of the frame 20 in the axial direction, and a protruding portion 32 that extends in the axial direction. A hole 31h through which the shaft S is inserted is formed in the lid 31 of the case 30. The protruding portion 32 projects from the outer peripheral portion of the lid 31 to the other side (in the direction of arrow b) in the axial direction. The protruding portion 32 extends toward the flange 122 of the outer peripheral portion 120 of the strain generating body 101 and faces the surface of the flange 122. In the radial direction, the protruding portion 32 is sandwiched between the outer peripheral portion 120 (the protruding portion 121) of the strain generating body 101 and the outer wall 23 of the frame 20. And the protruding portion 32 is disposed in a space formed between the outer peripheral portion 120 (the protruding portion 121) of the strain generating body 101 and the outer wall 23 of the frame 20.
[0040] FIG. 6 is a perspective view of the case 30. In the radial direction, a flange 33 is formed outside the protruding portion 32. The flange 33 is provided with portions (in the illustrated form, four holes 33h) for connecting the case 30 to the frame 20. The four holes 33h of the case 30 are formed at positions corresponding to the four holes 24 (see FIG. 7) of the frame 20. The case 30 is fixed to the frame 20 by inserting a fastening member such as a bolt through the holes 33h and the holes 24.
[0041] Figure 5 is an enlarged view of a portion of Figure 4. As shown in Figure 5, the outer periphery 120 of the strain generating body 101 has a first surface 121o facing the surface 34 extending in the axial direction of the housing 40, and a second surface 122a facing the surface 35 extending in the radial direction of the housing 40.
[0042] In this embodiment, the first surface 121o is the outer circumferential surface of the projection 121 of the outer circumferential portion 120 of the strain-generating body 101. In this embodiment, the second surface 122a is the surface of the flange 122 of the outer circumferential portion 120 of the strain-generating body 101 that faces one side in the axial direction (direction of arrow a). In this embodiment, the surface 34 extending in the axial direction of the housing 40 is the inner surface of the case 30 (the inner circumferential surface of the projection 32). In this embodiment, the surface 35 extending in the radial direction of the housing 40 is the end surface of the projection 32 of the case 30 (the surface facing the other side in the axial direction (direction of arrow b)). That is, in this embodiment, both the surface 34 extending in the axial direction and the surface 35 extending in the radial direction of the housing 40 are surfaces of the case 30. However, the surface 34 extending in the axial direction, the surface 35 extending in the radial direction, or both of the surfaces of the housing 40 may be surfaces of the frame 20.
[0043] The axially extending surface 34 of the housing 40 (case 30) is provided with three protrusions 34p projecting radially inward (see Figure 6). The first surface 121o of the outer peripheral portion 120 of the strain generating body 101 is provided with a first protrusion 123 projecting radially outward (see Figure 2). As shown in Figure 5, when the strain generating body 101 is fixed to the housing 40, the protrusions 34p of the case 30 contact the first protrusions 123 of the strain generating body 101.
[0044] The inner circumferential surface 121i of the protruding portion 121 on the outer circumferential portion 120 of the strain generating body 101 is provided with a second convex portion 124 that protrudes radially inward (see Figure 3). As shown in Figure 5, when the strain generating body 101 is fixed to the housing 40, the inner wall 22 of the frame 20 contacts the second convex portion 124 of the strain generating body 101.
[0045] In the radial direction, the protruding portion 121 of the outer periphery 120 of the strain-generating body 101 is sandwiched between the inner wall 22 of the frame 20 and the protruding portion 32 of the case 30. In the axial direction, the flange 122 of the outer periphery 120 of the strain-generating body 101 is sandwiched between the bottom 21 of the frame 20 and the protruding portion 32 of the case 30. In this way, the outer periphery 120 is fixed to the housing 40 in both the axial and radial directions.
[0046] As shown in Figure 5, in the axial and radial directions, the inner circumference 110 of the strain generating body 101 is separated from the housing 40 by a predetermined distance. In particular, in the axial direction, the second portion 112 of the inner circumference 110 of the strain generating body 101 is separated from the frame 20 by a predetermined distance D １ They are separated by only a small amount.
[0047] Figure 7 is a view of the frame 20 from one side to the other in the axial direction (in the direction of arrow b in Figure 4). The inner surface 25 of the frame 20 (the inner circumferential surface of the outer wall 23) is provided with a plurality of protrusions 25p (five in the illustrated configuration) that project inward in the radial direction. The plurality of protrusions 25p contact the outer circumferential portion 120 of the strain generating body 101 in the circumferential direction (see Figure 1). The plurality of protrusions 25p include one or more protrusions 25pe on one side (direction of arrow e) and one or more protrusions 25pf on the other side (direction of arrow f) of the outer circumferential portion 120 of the strain generating body 101 in the circumferential direction. In this way, the plurality of protrusions 25p of the frame 20 restrict the rotation of the strain generating body 101.
[0048] The torque sensor 1 according to this embodiment has the above configuration. When a radial force acts on the shaft S, a part of the strain generating body 101 is pressed radially outward by the bearing 102, and another part of the strain generating body 101 is pulled radially inward by the bearing 102. Since the outer circumference 120 of the strain generating body 101 is attached to the frame 20 and the case 30, stress is concentrated near the outer circumference 120. As a result, strain occurs on the deformable surface 101a of the strain generating body 101, and this strain is detected by a plurality of strain sensors 103s. The sensor device 10 can obtain information on the force acting on the shaft S from the strain detected by the plurality of strain sensors 103s.
[0049] The outer periphery 120 of the strain-generating body 101 of the torque sensor 1 is fixed to the housing 40 in the axial and radial directions. The first surface 121o of the outer periphery 120 of the strain-generating body 101 faces a surface 34 extending in the axial direction of the housing 40, and the second surface 122a faces a surface 35 extending in the radial direction of the housing 40. By adopting such a structure, for example, it becomes unnecessary to use fastening members such as bolts to fix the strain-generating body 101 to the housing 40. However, of course, fastening members such as bolts may be used to fix the strain-generating body 101 to the housing 40. Furthermore, by adopting the above structure, the deformable surface 101a becomes more easily deformable even without adopting a complex shape for the gap 140, making it possible to improve the accuracy of torque detection. However, of course, the shape of the gap 140 may be a more complex shape such as a keyhole shape.
[0050] In this embodiment, in the axial direction, the inner circumference 110 of the strain-generating body 101 housing the bearing 102 is at a predetermined distance D from the frame 20 of the housing 40. １ They are separated by only a small amount. By adopting this structure, when the strain-generating body 101 is pressed radially by the bearing 102, the deformable surface 101a becomes more easily deformed. Therefore, the torque sensor 1 is more likely to improve the accuracy of torque detection.
[0051] The torque sensor 1 has a simple configuration comprising a strain generating body 101 and a plurality of strain sensors 103s. Furthermore, since it can detect force information in all directions using the first strain sensor 103s1, the second strain sensor 103s2, and the third strain sensor 103s3, the overall size of the device can be reduced.
[0052] The sensor device 10 of the torque sensor 1 can detect not only information about the force acting on the shaft S, but also the rotational speed or rotational position of the shaft S using the sensor 105s and the magnet M. Here, the substrate 105 to which the sensor 105s is attached is positioned on the deformable surface 101a of the strain generating body 101. Therefore, the overall thickness of the device can be reduced.
[0053] Although a preferred embodiment of a torque sensor according to one aspect of the present invention has been described above, the torque sensor of the present invention is not limited to the configuration of the above-described embodiment. For example, the portion fixed to the housing may be any other part of the strain-generating body, as long as it has a first surface facing a surface extending in the axial direction of the housing and a second surface facing a surface extending in the radial direction of the housing. The housing may be a frame and case integrated into one. The sensor device may omit a sensor and magnet capable of detecting magnetic flux. The substrate may be separated from the holder. The end of the shaft may have a spline (a shape with circumferentially aligned irregularities) as shown in the figure, or it may have another shape. The torque sensor of the present invention may also be a force meter for a bicycle. In that case, the bicycle may be an electric assist bicycle or any other type of bicycle.
[0054] [Second Embodiment] Hereinafter, a second embodiment, which is an example of the present invention, will be described with reference to the drawings. Figure 8 is a perspective view of the sensor device 200 provided in the torque sensor 2 according to this embodiment. Figure 9 is a cross-sectional view of the sensor device 200 along the rotation axis X. Figure 10 is a cross-sectional view of the torque sensor 2 along the rotation axis X. Figure 11 is an enlarged view of a part of Figure 10.
[0055] The sensor device 200 comprises a strain generating body 201, a bearing 202, a plurality of strain sensors 203s, a ring 204, and a substrate 206 which is a flexible substrate.
[0056] In this embodiment, the bearing 202 is a ball bearing having an inner ring 202i and an outer ring 202o (see Figure 9). The bearing 202 rotatably supports the shaft S with respect to the strain body 201. The bearing 202 is not limited to a ball bearing, and may be any other type of bearing, such as a sleeve bearing. In the drawing, the bearing 202 is shown as a shielded bearing, but the bearing 202 does not have to have a shield. The ring 204 is configured to rotate together with the inner ring 202i of the bearing 202. Multiple strain sensors 203s and the substrate 206 are electrically connected.
[0057] The material of the strain-generating body 201 is not particularly limited. The material of the strain-generating body 201 may be, for example, steel, stainless steel, aluminum alloy, titanium, plastic, carbon fiber reinforced plastic, ceramic, or other metallic or non-metallic material. As shown in Figure 9, the strain-generating body 201 has an inner circumference portion 210 that holds the bearing 202, an outer portion (outer circumference portion 220) that surrounds the inner circumference portion 210 in the radial direction, and a connecting portion 230 that connects the inner circumference portion 210 and the outer circumference portion 220. As shown in Figure 10, the outer circumference portion 220 of the strain-generating body 201 is the portion that is fixed to the housing 40a. The connecting portion 230 is the portion of the strain-generating body 201 that extends from the inner circumference portion 210 toward the outer circumference portion 220, and in this embodiment it is formed as a plate-like portion (plate).
[0058] The inner circumference 210 of the strain-generating body 201 supports the shaft S via a bearing 202. The inner circumference 210 comprises a first portion 211 extending toward the shaft S and a cylindrical second portion 212 extending in the axial direction. In the axial direction, the first portion 211 is provided at the other end (direction of arrow b) of the inner circumference 210. The second portion 212 has a cylindrical shape around the rotation axis X and has an inner circumference 210i.
[0059] In the radial direction, the bearing 202 is positioned inside (in the direction of arrow d) the second portion 212 of the inner circumference 210 of the strain body 201. The inner ring 202i of the bearing 202 is fixed to the outer circumferential surface of the shaft S by adhesive or press-fitting. The outer ring 202o of the bearing 202 is fixed to the inner circumferential surface 210i of the inner circumference 210 of the strain body 201 by adhesive or press-fitting. The first portion 211 of the inner circumference 210 of the strain body 201 is in contact with the other end face (in the direction of arrow b) of the outer ring 202o of the bearing 202 in the axial direction. The first portion 211 and the second portion 212 of the inner circumference 210 of the strain body 201 house the bearing 202 from the other side in the axial direction and the outside in the radial direction, or surround the bearing 202 from the other side in the axial direction and the outside in the radial direction, thereby restricting the movement of the bearing 202.
[0060] In the axial direction, a plate-shaped, annular connecting portion 230 is connected to one end of the inner circumference portion 210 (in the direction of arrow a). The connecting portion 230 extends radially outward. In the radial direction, the outer circumference portion 220 is connected to the outside of the connecting portion 230. Therefore, the connecting portion 230 connects the inner circumference portion 210 and the outer circumference portion 220 in the radial direction. The connecting portion 230 is elastic and easily deformed with strain, partly due to the shape of the gap 240 described later. Deformation here includes bending and twisting in the directions of arrows a, b, c, and d.
[0061] The strain-generating body 201 has a deformable surface 201a that extends in the radial direction. In the axial direction, the surface facing one side of the connecting portion 230 (direction of arrow a) is the deformable surface 201a of the strain-generating body 201. In the radial direction, the deformable surface 201a of the strain-generating body 201 is located between the inner circumference 210 and the outer circumference 220. As shown in Figure 8, the deformable surface 201a of the strain-generating body 201 has a first portion 201a1, a second portion 201a2, and a third portion 201a3. The first portion 201a1, the second portion 201a2, and the third portion 201a3 are arranged in the circumferential direction at a predetermined interval.
[0062] Multiple strain sensors 203s are attached to the strain generating body 201. The multiple strain sensors 203s include a first strain sensor 203s1, a second strain sensor 203s2, and a third strain sensor 203s3. The first strain sensor 203s1 is attached to a first portion 201a1 of the deformable surface 201a of the strain generating body 201. The second strain sensor 203s2 is attached to a second portion 201a2 of the deformable surface 201a of the strain generating body 201. The third strain sensor 203s3 is attached to a third portion 201a3 of the deformable surface 201a of the strain generating body 201. The first strain sensor 203s1, the second strain sensor 203s2, and the third strain sensor 203s3 are arranged at predetermined intervals in the circumferential direction.
[0063] In the circumferential direction, the angles formed by the rotation axis X, the first portion 201a1, and the second portion 201a2, and the angles formed by the rotation axis X, the first portion 201a1, and the third portion 201a3, are both obtuse angles. In this embodiment, the angles formed by the rotation axis X, the second portion 201a2, and the third portion 201a3 are also obtuse angles. The relationships between these angles are the same as in the first embodiment described above, and the description and the matters shown in Figure 1 of the first embodiment also apply to the second embodiment.
[0064] The outer periphery 220 is the portion fixed to the housing 40a in the radial direction. The outer periphery 220 is curved along the circumferential direction. As shown in Figure 8, the strain generating body 201 comprises three outer periphery 220s. In this embodiment, the three outer periphery 220s are arranged in positions that are three times symmetrical around the axis of rotation X. That is, the three outer periphery 220s are arranged at predetermined intervals in the circumferential direction. In this embodiment, the three outer periphery 220s are arranged at 120° intervals in the circumferential direction. The arrangement of each of the three outer periphery 220s corresponds to the arrangement of the first portion 201a1, the second portion 201a2, and the third portion 201a3 of the deformable surface 201a of the strain generating body 201.
[0065] The strain-generating body 201 may include one, two, or four or more outer periphery portions 220. If the number of outer periphery portions 220 is m (where m is a natural number), the m outer periphery portions 220 may be arranged at intervals of (360 / m)° in the circumferential direction. For example, four outer periphery portions 220 may be arranged at intervals of 90° in the circumferential direction.
[0066] As shown in Figure 9, the outer peripheral portion 220 has a projection 221 that extends in the axial direction. The projection 221 extends from the radial outer end of the connecting portion 230 toward the other side in the axial direction (direction of arrow b).
[0067] As shown in Figure 9, in the radial direction, the inner circumference 210 and the outer circumference 220 face each other with a gap 240 in between. In the axial direction, the gap 240 is formed on the other side of the connecting portion 230 (in the direction of arrow b). Due to the presence of the gap 240, the inner circumference 210 and the outer circumference 220 are separated by a predetermined distance in the radial direction. The gap 240 is formed to be a curved space along the circumferential direction.
[0068] As described above, the deformable surface 201a of the strain generating body 201 is provided with a plurality of strain sensors 203s for detecting the strain on the deformable surface 201a. Each of the plurality of strain sensors 203s is located in the portion to which the outer periphery 220 is connected.
[0069] The first strain sensor 203s1, the second strain sensor 203s2, and the third strain sensor 203s3, each included in the plurality of strain sensors 203s, are mounted on a deformable surface 201a such that the orientation of the grid (not shown) is in a predetermined direction (for example, radial, circumferential, or oblique to the radial direction, oblique to the circumferential direction, etc.). The first strain sensor 203s1, the second strain sensor 203s2, and the third strain sensor 203s3 may each have multiple grids with different orientations. The first strain sensor 203s1, the second strain sensor 203s2, and the third strain sensor 203s3 may each be strain gauges. Strain gauges can detect surface strain as a change in resistance. The plurality of strain sensors 203s may also be various other sensors such as resistive elements and piezoelectric elements.
[0070] A substrate 206, which is an annular flexible substrate, is placed on the deformable surface 201a of the strain generating body 201. The substrate 206 surrounds the ring 204, which will be described later, from the outside in the radial direction. The substrate 206 extends parallel or substantially parallel to the deformable surface 201a of the strain generating body 201. The substrate 206 has a wiring pattern (not shown). As shown in Figure 8, the outer periphery 206o of the substrate 206 has a plurality of protrusions 206c extending radially outward (in the direction of arrow c) and a plurality of recesses 206r recessed relative to the protrusions 206c. The substrate 206 is electrically connected to a plurality of strain sensors 203s at the plurality of protrusions 206c. The substrate 206 has one protrusion 206c for each strain sensor 203s. The recesses 206r are notches recessed radially inward. In the circumferential direction, each protrusion 206c is positioned between a pair of recesses 206r.
[0071] As shown in Figure 8, a sensor 206s is positioned on a surface 206a of the substrate 206 facing one side in the axial direction (direction of arrow a). Other elements may also be positioned on surface 206a. The sensor 206s is mounted on the inner radial edge of the substrate 206. The sensor 206s is a sensor capable of detecting magnetic flux and may be, for example, a Hall element, a Hall IC, or a magnetoresistive element. The sensor 206s detects the magnetic flux or change in magnetic flux of the magnet M, which will be described later and is positioned on the ring 204, in the radial direction. The substrate 206 is provided with, for example, a circuit (not shown) for amplifying signals from the sensor 206s and a plurality of strain sensors 203s and communicating with the outside.
[0072] The ring 204 is an annular member that surrounds the shaft S from the outside in the radial direction. As shown in Figure 9, in the radial direction, the ring 204 is positioned inside the substrate 206. In the radial direction, the ring 204 and the substrate 206 are separated by a predetermined distance. The ring 204 and the substrate 206 have overlapping positions in the axial direction and face each other in the radial direction.
[0073] As shown in Figure 9, the ring 204 comprises a flange (projecting portion) 204a extending radially outward, a plate portion 204b extending radially inward, and a cylindrical portion 204c. The cylindrical portion 204c is a cylindrical part extending axially. The flange 204a and the plate portion 204b are connected to the cylindrical portion 204c. The flange 204a and the plate portion 204b form a single continuous surface on one side in the axial direction (direction of arrow a).
[0074] An annular, plate-shaped magnet M is arranged on the ring 204. The magnet M is attached to the other side of the flange 204a of the ring 204 in the axial direction (direction of arrow b). The magnet M is arranged coaxially with the ring 204. The magnet M is, for example, alternately magnetized in the circumferential direction and has multiple sets of two different magnetic poles arranged alternately. The positions of the magnet M and the sensor 206s, which is placed on the substrate 206, overlap in the axial direction. In the radial direction, the magnet M and the sensor 206s face each other. In the radial direction, the distance between the magnet M and the sensor 206s is within the range in which the sensor 206s can detect the magnetic flux of the magnet M. Note that the magnet M does not have to be annular, and may be multiple magnets M arranged in an annular shape. In this case, the inner circumferential surfaces of two adjacent magnets M have different magnetic poles. The magnet M may be attached, for example, to one or more locations in the circumferential direction of the ring 204. The sensor device 200 can detect the rotational speed or rotational position of the shaft S using the sensor 206s and the magnet M. However, the presence of the sensor 206s, the ring 204, and the magnet M in the sensor device 200 is optional. Furthermore, as long as the sensor 206s can detect magnetic flux, a magnet M magnetized in the axial direction may be used, or multiple magnets M arranged in a ring may be used.
[0075] In the axial direction, the ring 204 is positioned on one side of the bearing 202 (in the direction of arrow a). The inner ring 202i of the bearing 202 protrudes further in the axial direction (in the direction of arrow a) than the outer ring 202o. The plate portion 204b and the cylindrical portion 204c of the ring 204 are connected to the inner ring 202i of the bearing 202. As a result, the ring 204 rotates together with the inner ring 202i of the bearing 202.
[0076] Next, the sensor device 200 will be described in detail with reference to Figures 10 and 11 to explain how it is housed in the housing 40a. As shown in Figure 10, the sensor device 200 is housed in the housing 40a in the axial direction. The material of the housing 40a is not particularly limited. The material of the housing 40a may be, for example, an aluminum alloy, a magnesium alloy, steel, stainless steel, plastic, carbon fiber reinforced plastic, a metal matrix composite, or other metallic or non-metallic material. The housing 40a may consist of a frame and a case, as in the first embodiment.
[0077] In the radial direction, the shaft S is surrounded by the sensor device 200 and the housing 40a. The shaft S has a portion Sa facing the bearing 202. A groove Sb extending in the circumferential direction is formed in portion Sa of the shaft S. A hole 41h is formed in the housing 40a through which the shaft S is inserted. The shaft S passes through the hole 41h in the housing 40a and protrudes to the other side in the axial direction (direction of arrow b).
[0078] Figure 11 is an enlarged view of a portion of Figure 10. As shown in Figure 11, the inner circumference 210 of the strain-generating body 201 is separated from the housing 40a by a predetermined distance in the axial and radial directions. As shown in Figure 11, the outer circumference 220 of the strain-generating body 201 has a first surface 221o that faces the surface 44 extending axially from the housing 40a. In this embodiment, the first surface 221o is the outer surface of the projection 221 of the outer circumference 220 of the strain-generating body 201 (see Figure 9). In this embodiment, the surface 44 extending axially from the housing 40a is the inner surface of the housing 40a.
[0079] As shown in Figure 11, the first surface 221o of the strain-generating body 201 has a portion (hereinafter also referred to as the "contact portion 221o1") that protrudes toward the surface 44 extending in the axial direction of the housing 40a. Of the first surface 221o of the strain-generating body 201, the contact portion 221o1 contacts the surface 44 extending in the axial direction of the housing 40a, and the other portion 221o2 is at a predetermined distance D from the surface 44 extending in the axial direction of the housing. ２ They are separated by a certain distance. As shown in Figures 8, 9, and 11, in the axial direction, the contact portion 221o1 of the first surface 221o of the strain body 201 and the other portion 221o2 of the first surface 221o of the strain body 201 are aligned. That is, the contact portion 221o1 is located on the other side in the axial direction (direction of arrow b) of the first surface 221o of the strain body 201. As a result, the outer periphery 220 of the strain body 201 has a portion that is separated from the housing 40a (by a predetermined distance) on the side closer to the multiple strain sensors 203s (one side in the axial direction), and the portion that is farther from the multiple strain sensors 203s (the other side in the axial direction) is in contact with the housing 40a.
[0080] In the strain generating body 201, the number of contact portions 221o1 is the same as the number of strain sensors included in the plurality of strain sensors 203s. As shown in Figures 8 and 9, each of the plurality of contact portions 221o1 of the strain generating body 201 and each of the plurality of strain sensors 203s (first strain sensor 203s1, second strain sensor 203s2, and third strain sensor 203s3) are aligned in the radial direction. In other words, each of the plurality of contact portions 221o1 of the strain generating body 201 and each of the plurality of strain sensors 203s (first strain sensor 203s1, second strain sensor 203s2, or third strain sensor 203s3) are in an overlapping position in the circumferential direction.
[0081] The torque sensor 2 according to this embodiment has the above configuration. When a radial force acts on the shaft S, a part of the strain generating body 201 is pressed radially outward by the bearing 202, and another part of the strain generating body 201 is pulled radially inward by the bearing 202. Since the outer circumference 220 of the strain generating body 201 is attached to the housing 40a, stress is concentrated near the outer circumference 220. As a result, strain occurs on the deformable surface 201a of the strain generating body 201, and this strain is detected by a plurality of strain sensors 203s. The sensor device 200 can obtain information on the force acting on the shaft S from the strain detected by the plurality of strain sensors 203s. In particular, in the torque sensor 2 of this embodiment, of the first surface 221o of the strain generating body 201, the contact portion 221o1 contacts the surface 44 extending in the axial direction of the housing 40a, and the other portion 221o2 is at a predetermined distance D from the surface 44 extending in the axial direction of the housing. ２ They are separated by only a small distance. Therefore, strain is more easily generated on the deformable surface 201a of the strain-generating body 201, and the accuracy of torque detection is further improved.
[0082] Although a preferred embodiment of another aspect of the present invention has been described above, the torque sensor of the present invention is not limited to the configuration of the above-described embodiment. For example, the portion fixed to the housing may be any other part of the strain-generating body, as long as it has a first surface facing the surface extending in the axial direction of the housing. The sensor device may omit a sensor and magnet capable of detecting magnetic flux. The end of the shaft may have a spline (a shape with circumferentially aligned irregularities) as shown in the figure, or it may have another shape. The torque sensor of the present invention may also be a force meter for a bicycle. In that case, the bicycle may be an electric assist bicycle or any other bicycle. Some of the configurations of the first embodiment and some of the configurations of the second embodiment may be arbitrarily combined or replaced.
[0083] Furthermore, those skilled in the art can modify the torque sensor of the present invention as appropriate, and change the shape, dimensions, and combinations of various components, in accordance with conventionally known knowledge. As long as such modifications still possess the configuration of the present invention, they are of course included within the scope of the present invention.
[0084] 1, 2... Torque sensor, 10, 200... Sensor device, 20... Frame, 30... Case, 40, 40a... Housing, 101, 201... Strain generating body, 101a, 201a... Deformable surface, 102, 202... Bearing, 103s, 203s... Strain sensor, 110, 210... Inner circumference, 111, 211... First part, 112, 212... Second part, 120, 220... Outer circumference (part fixed to the housing), 121, 221... Protrusion, 121o, 221o... First surface, 122... Flange, 122a... Second surface, S... Shaft.
Claims
1. A torque sensor comprising: a shaft; a strain generating body connected to the shaft; and a housing supporting the strain generating body, wherein the strain generating body has portions fixed to the housing in the axial and radial directions, and the portions of the strain generating body have a first surface facing an axially extending surface of the housing and a second surface facing a radially extending surface of the housing.
2. The torque sensor according to claim 1, wherein the portion of the strain generating body comprises a projection extending in the axial direction and a flange extending in the radial direction, the projection of the strain generating body has the first surface, and the flange of the strain generating body has the second surface.
3. The torque sensor according to claim 2, wherein the housing comprises a frame and a case, and the case comprises a surface extending in the axial direction of the housing and a surface extending in the radial direction of the housing.
4. The torque sensor according to claim 3, wherein the axially extending surface of the housing is the inner surface of the case.
5. The torque sensor according to claim 3, wherein the case comprises a projection extending toward the flange, and the projection of the case comprises a surface extending radially from the housing.
6. The torque sensor according to claim 5, wherein the end face of the protrusion of the case is a surface extending radially from the housing.
7. The torque sensor according to any one of claims 1 to 6, wherein the strain generating body comprises an outer circumferential portion which is the portion fixed to the housing and an inner circumferential portion which is located at a predetermined distance from the housing.
8. The torque sensor according to claim 7, comprising a strain sensor, wherein the strain sensor is provided on a deformable surface between the inner and outer circumferential portions of the strain-generating body.
9. The torque sensor according to claim 7 or 8, comprising a bearing, wherein the inner circumference of the strain-generating body supports a shaft via the bearing.
10. The torque sensor according to claim 9, wherein the inner circumference of the strain-generating body comprises a first portion extending radially toward the shaft and a second portion extending axially, and the first portion and the second portion house or surround the bearing.
11. A torque sensor comprising: a shaft; a strain-generating body connected to the shaft; and a housing supporting the strain-generating body, wherein the strain-generating body has a portion fixed to the housing in the radial direction; the portion of the strain-generating body has a first surface facing an axially extending surface of the housing; the first surface of the strain-generating body has a portion projecting toward the axially extending surface of the housing; the projecting portion of the first surface of the strain-generating body is in contact with the axially extending surface of the housing, and the other portion is away from the axially extending surface of the housing; and in the axial direction, the projecting portion of the strain-generating body and the other portion of the first surface of the strain-generating body are aligned.
12. A torque sensor according to claim 11, comprising a strain sensor, wherein the strain generating body comprises an outer circumferential portion which is the portion fixed to the housing and an inner circumferential portion which is a predetermined distance from the housing in the axial direction, the strain sensor is provided on a deformable surface between the inner circumferential portion and the outer circumferential portion of the strain generating body, and the protruding portion of the strain generating body and the strain sensor are aligned in the radial direction.
13. The torque sensor according to claim 12, wherein, in the circumferential direction, the protruding portion of the strain-generating body is located in a position that overlaps with the strain sensor.