WO2023238791A1

WO2023238791A1 - Sensor device

Info

Publication number: WO2023238791A1
Application number: PCT/JP2023/020630
Authority: WO
Inventors: 裕昭村上; 幸嗣癸生川
Original assignee: ミネベアミツミ株式会社
Priority date: 2022-06-10
Filing date: 2023-06-02
Publication date: 2023-12-14
Also published as: JP2023180817A; TW202348965A

Abstract

Provided is a sensor device with a simple configuration.　A sensor device (1, 100, 200) comprises: a shaft (S), a bearing (20) directly or indirectly disposed on the shaft (S); and a holder (10, 210) disposed on the bearing (20). The holder (10, 210) includes: an inner circumferential member (11); an outer circumferential member (12, 212); a connecting portion (13) that connects the inner circumferential member (11) and the outer circumferential member (12, 212); and a first strain sensor (16) disposed on the connecting portion (13). In the radial direction, the inner circumferential member (11) is disposed outside of the bearing (20), and the connecting portion (13) rotatably supports the inner circumferential member (11) relative to the outer circumferential member (12, 212).

Description

sensor device

The present invention relates to a sensor device.

Conventionally, as a sensor device for detecting forces in multiple directions applied to a shaft, a sensor device configured to connect multiple strain gauges attached to a strain generating part to each other and detect strain according to the force is known. (Patent Document 1).

Japanese Patent Application Publication No. 10-78360

Conventional sensor devices tend to have complicated mechanisms, and the overall size of the device tends to increase. An example of the present invention is to provide a sensor device having a simple configuration.

The sensor device of the present invention includes a shaft, a bearing disposed directly or indirectly on the shaft, and a holder disposed on the bearing, and the holder includes an inner peripheral member, an outer peripheral member, a connecting portion connecting the inner circumferential member and the outer circumferential member; and a first strain sensor disposed in the connecting portion, wherein the inner circumferential member is disposed outside the bearing in the radial direction. The connecting portion rotatably supports the inner peripheral member with respect to the outer peripheral member.

FIG. 1 is a perspective view of a sensor device according to a first embodiment, which is an example of the present invention. 1 is a schematic diagram showing an example of a usage state of a sensor device according to a first embodiment, which is an example of the present invention; FIG. FIG. 3 is a perspective view of a sensor device according to a second embodiment, which is an example of the present invention. FIG. 7 is a perspective view of a sensor device according to a third embodiment, which is an example of the present invention.

In the description of each embodiment of the present invention, for convenience of explanation, the direction of arrow b along the central axis (axis X) of the shaft S will be referred to as the back side or one side in the axial direction. The direction of arrow a along axis X is defined as the front side or the other axial side. Here, the direction along the axis X, that is, the direction of the arrow ab is referred to as the depth direction or the axial direction. Further, the direction of arrow c, that is, the direction perpendicular to the axial direction, is referred to as the radial direction, the direction of arrow c, which moves away from axis X, is referred to as the outside or one radial side, and the direction of arrow d, which approaches axis . Furthermore, the direction along the tangent of the circle around the axis X is referred to as the tangential direction.

[First embodiment]
DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment, which is an example of the present invention, will be described below with reference to the drawings. FIG. 1 is a perspective view showing the external configuration of a sensor device 1 according to the present embodiment. However, the shaft S and the boss portion G2 of the output gear G are shown in cross section. FIG. 2 is a schematic diagram showing an example of how the sensor device 1 is used.

The sensor device 1 includes a shaft S, a holder 10, and a bearing 20. In this embodiment, the bearing 20 is a ball bearing having an inner ring 21, an outer ring 22, and rolling elements. The inner ring 21 is fixed integrally with a shaft S and a boss portion G2 of an output gear G, which will be described later, and is arranged to be rotatable with respect to the outer ring 22. Note that the bearing 20 is not limited to a ball bearing, and may be a variety of other bearings such as a sleeve bearing.

The shaft S is a substantially cylindrical member extending in the axial direction. In the radial direction, an output gear G is fixed to the outside (radially one side) of the shaft S. The output gear G includes a gear part G1 (see FIG. 2) and a substantially cylindrical boss part G2, which is provided coaxially with the gear part G1 and projects from the gear part G1 to the back side (one side in the axial direction). It is a member. The output gear G is glued or press-fitted onto the outer circumferential surface (radially outer surface) of the shaft S. Thereby, the output gear G is fixed to the shaft S and rotates together with the shaft S.

A bearing 20 is arranged outside the boss portion G2 of the output gear G in the radial direction. That is, in the radial direction, the bearing 20 is arranged outside the shaft S with other members interposed therebetween. Specifically, the bearing 20 is indirectly arranged on the outside of the shaft S via the output gear G. The inner ring 21 of the bearing 20 is bonded or press-fitted to the outer circumferential surface (radially outer surface) of the boss portion G2 of the output gear G. Thereby, the inner ring 21 of the bearing 20 is fixed to the boss portion G2 of the output gear G, and rotates together with the shaft S and the output gear G.

The holder 10 is arranged outside the bearing 20 in the radial direction. The holder 10 has a substantially square cylindrical shape when viewed in the axial direction (plan view), and includes an inner circumferential member 11 and an outer circumferential member 12 . The inner circumferential member 11 is a substantially cylindrical member that extends in the axial direction and has a cylindrical inner circumferential surface 11i and a substantially cylindrical outer circumferential surface 11o around the axis X.

In the radial direction, the inner peripheral member 11 is arranged outside the bearing 20. The outer ring 22 of the bearing 20 is press-fitted or bonded to the inner circumferential surface 11i of the inner circumferential member 11 of the holder 10. Thereby, the bearing 20 supports the inner peripheral member 11 of the holder 10 from inside. Further, the bearing 20 rotatably supports the shaft S and the output gear G with respect to the holder 10.

The outer circumferential member 12 is a cylindrical member that has a substantially cylindrical inner circumferential surface 12i around the axis X and is substantially square when viewed in the axial direction (plan view). The outer circumferential member 12 is arranged outside the inner circumferential member 11 in the radial direction. In the axial direction, the dimensions of the inner peripheral member 11 are the same as the dimensions of the outer peripheral member 12. In the axial direction, the front end face (the other side) and the back end face (one side) of the inner circumferential member 11 are on the same plane as the front end face and the back end face of the outer circumferential member 12, respectively.

The outer circumferential member 12 has four outer circumferential surfaces (radially outer surfaces, respectively referred to as

surfaces

12a, 12b, 12c, and 12d in the clockwise axial direction (plan view)) extending in the axial direction. have Surface 12a and surface 12c are parallel to each other, and surface 12b and surface 12d are parallel to each other. Among the

surfaces

12a, 12b, 12c, and 12d, two adjacent surfaces (surface 12a and surface 12b, surface 12b and surface 12c, surface 12c and surface 12d, and surface 12d and surface 12a) are orthogonal to each other. .

A total of four circular fixing holes 12h when viewed in the axial direction (plan view) are provided near the four corners of the outer peripheral member, one each. Each fixing hole 12h passes through the outer peripheral member 12 in the axial direction. As shown in FIG. 2, the holder 10 (outer peripheral member 12) is fixed to the housing H in which the sensor device 1 is arranged by a bolt B inserted into the fixing hole 12h.

The inner peripheral member 11 and the outer peripheral member 12 are integrally connected by two connecting parts 13. The two connecting parts 13 are arranged at symmetrical positions with respect to the axis X. The two connecting portions 13 are arranged on the side closer to the surface 12a and the side closer to the surface 12c, respectively. Specifically, in this embodiment, the two connecting portions 13 are arranged point-symmetrically with respect to the axis X, in other words, the center of the shaft S. In the axial direction, the end face on the front side (the other side) and the end face on the back side (one side) of the connecting portion 13 are the same as the end face on the front side and the end face on the back side of the inner peripheral member 11 (and outer peripheral member 12), respectively. Extends on a plane. An axis Y connecting the two connecting parts 13 passes through the axis X and is perpendicular to the axis X. Each connecting portion 13 has an extending direction perpendicular to the axial direction (direction along the axis X), that is, an extending direction along the axis Y.

Furthermore, the two connecting portions 13 each have a shape that is line symmetrical with respect to the axis Y when viewed in the axial direction (viewed in the axial direction with respect to the axis X). In addition, each of the two connecting portions 13 has a width in the tangential direction of the portion connected to the inner circumferential member 11 and a width in the tangential direction of the portion connected to the outer circumferential member 12, respectively, when viewed in the axial direction (viewed in the axial direction with respect to the axis X). The width is larger than the width in the tangential direction of the portion between the portion connected to the inner peripheral member 11 and the portion connected to the outer peripheral member 12. In other words, each of the two connecting portions 13 has a concave portion recessed in the tangential direction in a portion between a portion connecting to the inner circumferential member 11 and a portion connecting to the outer circumferential member 12 when viewed in the axial direction.

In the radial direction, the outer circumferential surface 11o of the inner circumferential member 11 and the inner circumferential surface 12i of the outer circumferential member 12 are opposed to each other via two substantially semicylindrical grooves 14, except for a portion connected by the connecting portion 13. are doing. The two grooves 14 are formed symmetrically with respect to the axis X. Each groove 14 passes through the holder 10 in the axial direction. The two grooves 14 are arranged on the side closer to the surface 12b and the side closer to the surface 12d, respectively.

Both ends of each groove 14 are connected to a total of four circular through holes 15 when viewed in the axial direction (plan view), which penetrate the holder 10 in the axial direction. That is, the through holes 15 are connected to both ends of one groove 14, and the groove 14 and the two through holes 15 are in communication. The diameter of the through hole 15 is the same or approximately the same as the diameter of the fixing hole 12h of the outer circumferential member 12, and is larger than the width of the groove 14 (the distance between the inner circumferential member 11 and the outer circumferential member 12 in the radial direction). .

In the axial direction (plan view), two of the four fixing holes 12h and two of the four through holes 15 are located near the surface 12a of the outer peripheral member 12. They are arranged on a straight line parallel to the surface 12a. In addition, in the axial direction (plan view), the other two fixing holes 12h among the four fixing holes 12h and the other two through holes 15 among the four through holes 15 are located in the outer peripheral member 12. In the vicinity of the surface 12c, they are arranged on a straight line parallel to the surface 12c. The connecting portion 13 is formed as a region between two adjacent through holes 15.

The connecting portion 13 is a deformable portion that undergoes elastic deformation or plastic deformation when subjected to stress. The connecting portion 13 rotatably supports the inner peripheral member 11 with respect to the outer peripheral member 12. Specifically, the connecting portion 13 supports the inner circumferential member 11 with respect to the outer circumferential member 12 so as to be able to twist and rotate. In other words, the connecting portion 13 is arranged to be twisted and rotatable with respect to the inner circumferential member 11 or the outer circumferential member 12. The torsional rotation referred to herein is a torsional rotation in the circumferential direction (direction indicated by arrow e) about the axis Y connecting the two connecting portions 13. Thereby, the inner circumferential member 11 can be twisted and displaced in the direction of arrow e with respect to the outer circumferential member 12.

A first strain sensor 16 is disposed on each of the two connecting portions 13 on the front surface in the axial direction. That is, a total of two first strain sensors 16 are installed at symmetrical positions with respect to the axis X. The first strain sensor 16 can detect strain deformation of the connecting portion 13 due to twisting. When viewed in the axial direction, each of the first strain sensors 16 is arranged obliquely with respect to the extending direction of the connecting portion 13 (direction along the axis Y). This inclination angle and the like will be described later.

When the first strain sensor 16 is a strain gauge, the orientation of the grid (gauge) (typically, the longitudinal direction of the strain gauge) is relative to the extending direction of the connecting portion 13 (direction along axis Y). It is attached to the connecting part 13 so as to be inclined. When the first strain sensor 16 is a strain gauge, strain deformation of the connecting portion 13 is detected as a change in resistance value. Note that the first strain sensor 16 is not limited to a strain gauge, and may be various other sensors such as a piezoelectric element.

In this embodiment, each of the first strain sensors 16 is attached so as to be inclined at 45 degrees with respect to the axis Y connecting the two connecting parts 13. The two first strain sensors 16 are mounted so as to be inclined in the same direction. However, the angle of inclination is not limited to 45°. For example, the angle of inclination may be within the range of 5° to 85° relative to axis Y, may be within the range of 10° to 80° relative to axis Y, and may be within the range of 10° to 80° relative to axis Y. It may be within the range of 20° to 70°, it may be within the range of 30° to 60° with respect to axis Y, and it may be within the range of 40° to 50° with respect to axis Y. good. Note that the angle of inclination here refers to the smaller of the angles formed by the axis Y and the extending direction of the first strain sensor 16. Furthermore, the two first strain sensors 16 may be inclined at different angles. Furthermore, the two first strain sensors 16 may be mounted so as to be inclined in different directions.

A total of four second strain sensors 17, two each on the surface 12a and surface 12c of the outer peripheral member 12, are arranged. Each second strain sensor 17 is attached near the through hole 15. Specifically, in the direction along the axis Y, the second strain sensor 17 is arranged at a position facing the through hole 15. The second strain sensor 17 is attached so as to be able to detect the strain of the

surfaces

12a and 12c in a direction along a plane perpendicular to the axial direction (direction along the axis X). The second strain sensor 17 can detect deformation of the holder 10 in a direction perpendicular to the axial direction (direction along the axis X).

When the second strain sensor 17 is a strain gauge, the orientation of the grid (gauge) (typically, the longitudinal direction of the strain gauge) is along the longitudinal direction (direction perpendicular to the axial direction) of

surfaces

12a and 12c. It is installed like this. When the second strain sensor 17 is a strain gauge, strain in the holder 10 is detected as a change in resistance value. Note that the second strain sensor 17 is not limited to a strain gauge, and may be various other sensors such as a piezoelectric element.

FIG. 2 is a schematic diagram showing a state in which the sensor device 1 is attached to a power-assisted bicycle. The holder 10 is fixed by a bolt B to a housing H of a drive unit 5 of the electrically assisted bicycle. In FIG. 2, the sensor device 1 is mounted with the axial back side (one axial side) of the holder 10 facing the housing H. However, the sensor device 1 may be mounted with the axial front side (the other axial side) of the holder 10 facing the housing H. On the opposite side of the holder 10 across the housing H (hereinafter also referred to as "the outside of the drive unit 5"), the shaft S and the boss portion G2 of the output gear G penetrate and protrude. On the outside of the drive unit 5, a pedal (not shown) is fixed to the end of the shaft S.

On the outside of the drive unit 5, a chain ring (load member) 30 is fixed to the outer peripheral surface (radially outer surface) of the boss portion G2 of the output gear G via a hub (not shown) or the like. The chain ring (load member) 30 is arranged on one side of the shaft S in the axial direction. In the axial direction, the chain ring (load member) 30 and the holder 10 are separated from each other. The electrically assisted bicycle has a rear wheel (not shown) centered around a rear wheel shaft 3, and a cassette sprocket 2 including five

sprockets

2a, 2b, 2c, 2d, and 2e with different diameters is mounted on the rear wheel shaft 3 (not shown). It is fixed via a hub etc.

A roller chain 4 is stretched across the chain ring (load member) 30 and one of the sprockets of the cassette sprocket 2. The rotation of the chain ring (load member) 30 is transmitted by the roller chain 4 to the cassette sprocket 2 and, in turn, to the rear wheel. During gear shifting, the sprocket on which the roller chain 4 is mounted is changed by a derailleur (not shown).

In FIG. 2, the roller chain 4 is shown hanging on the sprocket 2a, which has the largest diameter among the five sprockets and is located closest to the rear wheel (4a), and the state where the roller chain 4 is mounted on the sprocket 2a, which has the largest diameter among the five sprockets and is located closest to the rear wheel (4a); The state (4e) in which the sprocket 2e is small and is placed over the sprocket 2e located furthest from the rear wheel is shown by imaginary lines.

When the roller chain 4 is in position 4a, a load Fa derived from the tension of the roller chain 4 is applied to the chain ring (load member) 30. The direction of the load Fa is different from the direction in which the connecting portion 13 of the holder 10 extends (the direction along the axis Y). The load Fa has an axial component Fa1 (direction along the axis X) and a component Fa2 in a direction perpendicular to the axial direction. Further, when the roller chain 4 is in the position 4e, a load Fe derived from the tension of the roller chain 4 is applied to the chain ring (load member) 30. The load Fe has an axial component Fe1 (direction along the axis X) and a component Fe2 in a direction perpendicular to the axial direction. The axial component Fa1 of the load Fa and the axial component Fe1 of the load Fe face opposite directions in the axial direction (direction along the axis X).

Since the loads Fa and Fe have components Fa1 and Fe1 in the axial direction (direction along the axis X), stress that tilts the chain ring (load member) 30 in the axial direction (direction along the axis X) is generated. do. Such stress is transmitted to the inner peripheral member 11 of the holder 10 via the output gear G and the bearing 20. Then, the inner circumferential member 11 slightly rotates (twists) with respect to the outer circumferential member 12 at an angle corresponding to the stress. The rotation can be detected by the first strain sensor 16. As described above, the first strain sensor 16 can detect the load applied to the chain ring (load member) 30 via the output gear G and the bearing 20.

Since the magnitude and direction of the axial component of the load applied to the chain ring (load member) 30 differ depending on which sprocket of the cassette sprocket 2 the roller chain 4 is mounted on, the inner peripheral member 11 is adjusted accordingly. The angle of rotation is also different. Therefore, the first strain sensor 16 can detect which sprocket of the cassette sprocket 2 the roller chain 4 is mounted on (that is, which gear shift stage the electrically assisted bicycle is in).

Furthermore, when the sensor device 1 is used for an electrically assisted bicycle, the shaft S is a crankshaft provided with pedals. When one of the pedals is stepped on, a force is applied that tends to tilt the pedal side of the shaft S downward in the vertical direction, so the bearing 20 tends to move in the radial direction, causing a part of the holder 10 to move outward in the radial direction (in the vertical direction). (lower side). In the holder 10, stress is concentrated near the through hole 15 of the outer peripheral member 12, and elastic strain deformation is likely to occur. This strain deformation can be detected by the second strain sensor 17.

In the sensor device 1 according to the present embodiment, the connecting portion 13 rotatably supports the inner circumferential member 11 of the holder 10 with respect to the outer circumferential member 12, and the first strain sensor 16 is attached to the connecting portion 13. Due to the simple arrangement, the load applied to the chain ring (load member) 30 can be detected as torsion. Further, the sensor device 1 according to the present embodiment can also detect the force of pressing the pedal as a strain by the second strain sensor 17 arranged on the outer peripheral member 12 of the holder 10. In this way, the sensor device 1 can detect multiple types of forces simultaneously with a simple configuration.

In the sensor device 1 according to the present embodiment, each first strain sensor 16 is attached so as to be inclined with respect to the axis Y connecting the two connecting parts 13. This makes the first strain sensor 16 less susceptible to slight strain in the connecting portion 13 that may occur due to the force of pressing the pedal downward in the vertical direction. Strain in the connecting portion 13 caused by the rotation of the connecting portion 13 can be detected with higher accuracy.

In the sensor device 1 according to the present embodiment, a total of four second strain sensors 17, two each on the surface 12a and the opposite surface 12c of the outer peripheral member 12, are arranged, so that when the pedal is Stress in the direction along the axis Y (typically stress in the vertical direction), which is likely to occur when stepping on the pedal, can be detected with high sensitivity. Depending on the detected stress, the output of the motor of the electrically assisted bicycle can be adjusted.

[Second embodiment]
Next, a second embodiment, which is an example of the present invention, will be described with reference to the drawings. FIG. 3 is a perspective view showing the external configuration of sensor device 100 according to this embodiment. However, the shaft S and the output gear G are shown in cross section. The sensor device 100 has the same configuration as the sensor device 1 according to the first embodiment, except that it includes a first strain sensor 116 instead of the first strain sensor 16. Hereinafter, members and components having the same functions and configurations as those in the first embodiment will be designated by the same reference numerals as in the first embodiment, and detailed description thereof will be omitted.

In this embodiment, a first strain sensor 116 is arranged on the front surface of each connecting portion 13 in the axial direction. That is, a total of two first strain sensors 116 are installed at symmetrical positions with respect to the axis X. Each first strain sensor 116 can detect strain deformation of each connecting portion 13 due to torsional rotation. When viewed in the axial direction, each first strain sensor 116 is arranged to extend perpendicularly to the extending direction of the connecting portion 13 (direction along the axis Y).

When the first strain sensor 116 is a strain gauge, the orientation of the grid (gauge) (typically, the longitudinal direction of the strain gauge) is relative to the extending direction of the connecting portion 13 (direction along axis Y). They are attached to the connecting portion 13 so as to be perpendicular to each other. When the first strain sensor 116 is a strain gauge, strain deformation of the connecting portion 13 is detected as a change in resistance value. Note that the first strain sensor 116 is not limited to a strain gauge, and may be various other sensors such as a piezoelectric element.

In the sensor device 100 according to the present embodiment, unlike the sensor device 1 according to the first embodiment, each first strain sensor 116 is tilted with respect to the axis Y connecting the two connecting parts 13. It is not installed to do so. Therefore, in the sensor device 100 according to the present embodiment, the first strain sensor 116 detects slight strain in the connecting portion 13 that may occur due to the force of pressing the pedal downward in the vertical direction. There may be some impact.

However, the sensor device 100 according to the present embodiment can still simultaneously detect the load applied to the chain ring (load member) 30 and the pedal depression force with a simple configuration. Further, the sensor device 100 according to the present embodiment similarly has the other characteristics described above for the sensor device 1 according to the first embodiment.

Furthermore, in the sensor device 100 according to the present embodiment, there is no need to attach each first strain sensor 116 so as to be inclined with respect to the axis Y connecting the two connecting portions 13. Therefore, when manufacturing the sensor device 100, the work of attaching the first strain sensor 116 is simplified and work efficiency is improved.

[Third embodiment]
Next, a third embodiment, which is an example of the present invention, will be described with reference to the drawings. FIG. 4 is a perspective view showing the external configuration of sensor device 200 according to this embodiment. However, the shaft S and the output gear G are shown in cross section. The sensor device 200 has the same configuration as the sensor device 1 according to the first embodiment, except that it includes a holder 210 instead of the holder 10. Hereinafter, members and components having the same functions and configurations as those in the first embodiment will be designated by the same reference numerals as in the first embodiment, and detailed description thereof will be omitted.

In this embodiment, a holder 210 is arranged on the radially outer side of the bearing 20. In the holder 10 of the sensor device 1 according to the first embodiment, the holder 210 is a part of the outer peripheral member 12 (between the two fixing holes 12h near the surface 12b, extending along the surface 12b). The portion extending along the surface 12d between the two fixing holes 12h near the surface 12d is cut off.

The holder 210 has a substantially square cylindrical shape when viewed in the axial direction (plan view), and includes an inner circumferential member 11 and two outer circumferential members 212. The outer peripheral member 212 is arranged outside the inner peripheral member 11 in the radial direction. In the axial direction, the dimensions of the inner peripheral member 11 are the same as the dimensions of the outer peripheral member 212. In the axial direction, the front end face (the other side) and the back end face (one side) of the inner circumferential member 11 are on the same plane as the front end face and the back end face of the outer circumferential member 212, respectively.

The two outer circumferential members 212 are each connected to the inner circumferential member 11 by the connecting portions 13 so as to have mirror symmetry with respect to a plane including the axis X. Each outer circumferential member 212 has a substantially rectangular parallelepiped shape with the tangential direction as the longitudinal direction, and has a substantially circular arc shape along the outer circumferential surface 11o of the inner circumferential member 11 up to about half of the radial dimension at the central portion in the longitudinal direction. It has a chipped shape. Since the two outer circumferential members 212 have the same configuration, only one outer circumferential member 212 will be described in detail hereafter, and detailed explanations of the other outer circumferential members 212 will be omitted.

One fixing hole 212h, which is circular when viewed in the axial direction (planar view), is provided near both ends of the outer peripheral member. Each fixing hole 212h passes through the outer peripheral member 212 in the axial direction. The holder 210 (outer peripheral member 212) can be fixed to the housing H (not shown) by a bolt B (not shown) inserted into the fixing hole 212h.

The outer circumferential member 212 has two inner circumferential surfaces 212i that face the outer circumferential surface 11o of the inner circumferential member 11 and have an arcuate shape when viewed in the axial direction (planar view) with the axis X as the center. In the radial direction, each inner circumferential surface 212i of the outer circumferential member 212 is formed through an arcuate groove 214 when viewed in the axial direction, except for a portion connected by the connecting portion 13 and a portion where a through hole 215, which will be described later, is present. It faces the outer peripheral surface 11o of the inner peripheral member 11. Each groove 214 extends axially through the holder 210.

The end portion of each groove 214 (the end portion on the side closer to the connecting portion 13) is connected to a through hole 215 that passes through the holder 10 in the axial direction and is circular in axial direction (plan view). That is, the through hole 215 is connected to the end of one groove 214, and the groove 214 and the through hole 215 communicate with each other. The diameter of the through hole 215 is the same or approximately the same as the diameter of the fixing hole 212h of the outer circumferential member 212, and is larger than the width of the groove 214 (the distance between the inner circumferential member 11 and the outer circumferential member 212 in the radial direction). .

In an axial view (plan view), the two fixing holes 212h and the two through holes 215 are arranged in a straight line in the longitudinal direction of the outer peripheral member 212. The connecting portion 13 is formed as a region between two adjacent through holes 215.

Two second strain sensors 17 are arranged on a surface 212a of the outer peripheral member 212 opposite to the side connected to the inner peripheral member 11. Each second strain sensor 17 is attached near the through hole 215. Specifically, in the direction along the axis Y, the second strain sensor 17 is arranged at a position facing the through hole 215. The second strain sensor 17 is attached so as to be able to detect the strain of the surface 212a in a direction along a plane perpendicular to the axial direction (direction along the axis X). The second strain sensor 17 can detect deformation of the holder 210 in a direction perpendicular to the axial direction (direction along the axis X). Note that since there are two outer peripheral members 212, the sensor device 200 has a total of four second strain sensors 17 as a whole.

When the second strain sensor 17 is a strain gauge, it is installed so that the orientation of the grid (gauge) (typically, the longitudinal direction of the strain gauge) is along the longitudinal direction (direction perpendicular to the axial direction) of the surface 212a. It is being When the second strain sensor 17 is a strain gauge, strain in the holder 210 is detected as a change in resistance value. Note that the second strain sensor 17 is not limited to a strain gauge, and may be various other sensors such as a piezoelectric element.

The sensor device according to this embodiment similarly has the characteristics described above with respect to the sensor device 1 according to the first embodiment. In addition, in the torque sensor according to this embodiment, the holder 210 is lighter than the holder 10 of the sensor device 1 according to the first embodiment, so that the device can be made lighter.

Although the sensor device of the present invention has been described above with reference to preferred embodiments, the sensor device of the present invention is not limited to the configuration of the above embodiments. For example, the

sensor devices

1, 100, and 200 according to the embodiments described above are used for electrically assisted bicycles, but the sensor device of the present invention is not limited to that used for electrically assisted bicycles.

In the

sensor devices

1, 100, 200 according to the above embodiments, the load member is the chain ring 30, but the load member may be any other member as long as it generates stress that causes it to tilt in the axial direction due to the load. It may be.

In the

sensor devices

1, 100, 200 according to the embodiments described above, the second strain sensor 17 is attached to the outer

peripheral member

12, 212 of the

holder

10, 210, but the sensor device of the present invention The strain sensor 17 may not be provided.

In the

sensor devices

1, 100, 200 according to the embodiments described above, the bearing 20 was fixed to the shaft S via the boss portion G2 of the output gear G, but in the sensor device of the present invention, the bearing is directly attached to the shaft S. may be fixed. In this case, a load member such as a chain ring is also fixed to the shaft S without intervening the boss portion G2 of the output gear G.

In addition, those skilled in the art can appropriately modify the sensor device of the present invention and change the combinations of various configurations according to conventionally known knowledge. As long as such changes still have the structure of the present invention, they are, of course, included within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1,100,200... Sensor device, 10,210... Holder, 11... Inner peripheral member, 12,212... Outer peripheral member, 13... Connection part, 16... First strain sensor, 17... Second strain sensor, 20 ...Bearing, 21...Inner ring, 22...Outer ring, 30...Chain ring (load member), S...Shaft, Fa, Fe...Load.

Claims

shaft and
a bearing disposed directly or indirectly on the shaft;
a holder disposed on the bearing;
The holder includes an inner circumferential member, an outer circumferential member, a connecting portion connecting the inner circumferential member and the outer circumferential member, and a first strain sensor disposed in the connecting portion,
In the radial direction, the inner circumferential member is arranged outside the bearing,
In the sensor device, the connecting portion rotatably supports the inner circumferential member with respect to the outer circumferential member.
The sensor device according to claim 1, wherein the connecting portion is arranged so as to be twisted and rotatable with respect to the outer peripheral member.
The sensor device according to claim 1 or 2, wherein the first strain sensor is arranged obliquely with respect to the extending direction of the connecting portion when viewed in the axial direction.
The bearing has an outer ring that supports the inner peripheral member, and an inner ring that is rotatably arranged with respect to the outer ring,
The sensor device according to claim 1 or 2, wherein the inner ring rotates together with the shaft.
a load member on one side of the shaft;
The sensor device according to claim 1 or 2, wherein the first strain sensor detects a load applied to the load member via the bearing.
The sensor device according to claim 5, wherein the load applied to the load member has a component in a direction perpendicular to the axial direction.
The connecting portion has an extending direction perpendicular to the axial direction,
The sensor device according to claim 6, wherein the direction of the load applied to the load member is different from the direction of extension of the connecting portion.
The sensor device according to claim 5, wherein the load member and the holder are separated from each other in the axial direction.
The sensor device according to claim 1 or 2, comprising a second strain sensor arranged on the outer peripheral member of the holder.
The sensor device according to claim 9, wherein the second strain sensor detects deformation of the holder in a direction perpendicular to the axial direction.