Sensor device

Abstract

A sensor device (1) is provided with: a bearing (202); a shaft (S) having a portion supported by the bearing (202); a holder (201) having a holding part (210) for holding the bearing (202) and a deformable surface (222) extending in the axial direction of the bearing (202); a plurality of strain sensors (203) that detect information on a force (F ') acting on the shaft (S); a sensor (100) that detects information on the position of the shaft (S) in the circumferential direction of the bearing (202); and an arithmetic circuit (10) to which the plurality of strain sensors (203) are attached to the deformable surface (222) and to which signals outputted from the plurality of strain sensors (203) and the sensor (100) are inputted. The arithmetic circuit (10) calculates the magnitude (fr) of a component (Fr) in the radial direction of the bearing (202) and the magnitude (ft) of a component (Ft) in the circumferential direction of the bearing (202) in information of a force (F) applied to rotate the shaft (S) at a predetermined position of the shaft (S).

Description

Technical Field

[0001] The present invention relates to a sensor device. Background Art

[0002] Conventionally, in a device including a rotating shaft, a device for measuring the force applied to rotate the shaft has been known. For example, Patent Document 1 discloses a measuring device and a measuring mechanism that can indicate the direction of a force corresponding to a crank angle in a human-powered machine such as a bicycle.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: International Publication No. 2012 / 053114 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In a device including a rotating shaft, if information on the force that rotates the shaft can be calculated by separating it into a radial component and a circumferential component, useful information may be obtained in various analyses and controls. An example of the problem of the present invention is to provide a sensor device that can calculate information on the force that rotates the shaft by separating it into a radial component and a circumferential component.

[0008] Means for Solving the Problems

[0009] The sensor device of the present invention includes: a bearing; a shaft having a portion supported by the bearing; a retainer having a holding portion for holding the bearing and a deformable surface extending in the axial direction of the bearing; a plurality of strain sensors for detecting information on the force acting on the shaft; a sensor for detecting information on the position of the shaft in the circumferential direction of the bearing; and an arithmetic circuit. The plurality of strain sensors are mounted on the deformable surface, and signals output from the plurality of strain sensors and the sensor are input to the arithmetic circuit. The arithmetic circuit calculates the magnitude of the radial component and the magnitude of the circumferential component of the force that rotates the shaft at a specified position in the circumferential direction of the bearing. Brief Description of the Drawings

[0010] Figure 1 is a block diagram schematically showing the structure of a sensor device according to an embodiment as an example of the present invention.

[0011] Figure 2 is a diagram showing an example of the relationship between the force that rotates the shaft and its radial component and circumferential component.

[0012] Figure 3 ​​​is a diagram showing an example of the relationship between the force that rotates the shaft and its radial and circumferential components.

[0013] Figure 4 is a diagram showing an example of the relationship between the force that rotates the shaft and its radial and circumferential components.

[0014] Figure 5 is a diagram showing an example of the relationship between the force that rotates the shaft and its radial and circumferential components.

[0015] Figure 6 is a perspective view of the holder, strain sensor, and plate portion of the sensor device according to an embodiment as an example of the present invention.

[0016] Figure 7 is a cross-sectional view of the sensor device according to an embodiment as an example of the present invention (wherein the arithmetic circuit is omitted).

[0017] Figure 8 is a cross-sectional view showing another example of the holder included in the sensor device according to an embodiment as an example of the present invention.

[0018] Figure 9 is a cross-sectional view showing still another example of the holder included in the sensor device according to an embodiment as an example of the present invention.

[0019] Figure 10 is a cross-sectional view showing still another example of the holder included in the sensor device according to an embodiment as an example of the present invention.

[0020] Figure 11 is a plan view showing still another example of the holder included in the sensor device according to an embodiment as an example of the present invention.

[0021] Figure 12 is a cross-sectional view showing still another example of the holder included in the sensor device according to an embodiment as an example of the present invention, and is a cross-sectional view corresponding to the A-A cross-section in Figure 11

[0022] Figure 13 is a plan view showing still another example of the holder included in the sensor device according to an embodiment as an example of the present invention.

[0023] Figure 14 is a cross-sectional view showing still another example of the holder included in the sensor device according to an embodiment as an example of the present invention, and is a cross-sectional view corresponding to the B-B cross-section in Figure 13

[0024] Figure 15 ​​​​​​​​​​​​is a perspective view showing another example of the holder included in the sensor device according to an embodiment as an example of the present invention.

[0025] Figure 16 is a plan view showing another example of the holder included in the sensor device according to an embodiment as an example of the present invention.

[0026] Figure 17 is a schematic view showing an application example of the sensor device according to an embodiment as an example of the present invention.

[0027] Figure 18 is a schematic view showing another application example of the sensor device according to an embodiment as an example of the present invention. Detailed Embodiments

[0028] In the description of the embodiment of the present invention, for the sake of convenience of explanation, the direction of arrow a along the axis X (the central axis of the axis S) is set as the upper side or one side in the axial direction. The direction of arrow b along the axis X is set as the lower side or the other side in the axial direction. Here, the directions of arrows a and b are referred to as the up-down direction or the axial direction (the axial direction of the first bearings 202 and 602). Among them, the up-down direction does not necessarily coincide with the vertical direction. In addition, the directions of arrows c and d are referred to as the radial direction (the radial direction of the first bearings 202 and 602), the direction of arrow c away from the axis X is referred to as the outer side or one side in the radial direction, and the direction of arrow d approaching the axis X is referred to as the inner side or the other side in the radial direction. Furthermore, the direction along the tangent of the circle around the axis X (the direction perpendicular to the radial direction) is referred to as the tangential direction, and the direction of rotation around the axis X is referred to as the circumferential direction (the circumferential direction of the first bearings 202 and 602).

[0029] Hereinafter, an embodiment as an example of the present invention will be described with reference to the drawings. Figure 1 is a block diagram schematically showing the structure of the sensor device 1 of the present embodiment. The sensor device 1 includes: a first bearing 202; a shaft S having a portion supported by the first bearing 202; a plurality (four in the case of the present embodiment) of strain sensors 203; a sensor 100 for detecting information (rotation angle) on the position of the shaft S in the circumferential direction of the first bearing 202; and an arithmetic circuit 10. Figures 2 to 5 is a diagram showing the relationship between the force F applied to rotate the shaft S (applied for this purpose) and its radial component F r and its circumferential component F t in various examples. In addition, hereinafter, the "force for rotating the shaft" will be referred to as the "force applied to rotate the shaft". The "force for rotating the shaft" is a vector and may include components that are difficult to contribute to rotating the shaft.

[0030] ​​​A plurality of strain sensors 203 are configured to detect components x1 and y1 in two orthogonal directions in the information of the force F' acting radially on the shaft S. The force F' is a force that, when a force F is applied to a member 3 (e.g., a crank different from the shaft S or a member such as a pedal connected to the shaft via a crank) connected to the shaft S at a position far from the shaft S, acts on the position of the shaft S via the member 3. Here, x1 is the component of F' in the direction of the x-axis along Figures 2 to 5 and y1 is the component of F' in the direction of the y-axis along Figures 2 to 5 . x1 and y1 can be positive or negative values. The specific configuration and structure of the plurality of strain sensors 203 will be described later. The plurality of strain sensors 203 output information corresponding to x1 and y1 as signals. The output signals are input to the arithmetic circuit 10.

[0031] In addition, for ease of explanation, in Figure 1 , it is shown that two of the plurality (four) of strain sensors 203 output information of x1 as signals and the other two output information of y1 as signals, but in reality, the strains detected by the plurality of strain sensors 203 do not have to correspond only to either x1 or y1. For example, it can also be configured such that the arithmetic circuit 10 that inputs information on the strains detected by the plurality of strain sensors 203 respectively, or another circuit (not shown) arbitrarily arranged on the signal path between the plurality of strain sensors 203 and the arithmetic circuit 10 combines the information on the strains detected by the plurality of strain sensors 203 respectively and calculates x1 and y1.

[0032] The sensor 100 detects information (rotation angle) on the position in the circumferential direction of the shaft S. The specific structure of the sensor 100 will be described later. The sensor 100 outputs information on the rotation angle θ a of the shaft S in the circumferential direction with respect to a specified angle as a signal. Here, the rotation angle θ a indicates how much the shaft S has rotated counterclockwise with respect to the positive direction of the x-axis along Figures 2 to 5 and is 0 ≦ θ a ≦ 2π. The output signal is input to the arithmetic circuit 10. Among them, it is not necessarily required to output the information on the rotation angle θ a from the sensor 100, and it can also be configured such that based on the signal output from the sensor 100, the arithmetic circuit 10 or another circuit (not shown) arbitrarily arranged on the signal path between the sensor 100 and the arithmetic circuit 10 calculates the rotation angle θ a .

[0033] The arithmetic circuit 10 is, for example, a program processing device (such as a microcontroller) having a structure in which various storage devices such as a processor (e.g., a Central Processing Unit (CPU)), a Random Access Memory (RAM), and a Read Only Memory (ROM), a counter (timer), an Analog to Digital (A / D) conversion circuit, a Digital to Analog (D / A) conversion circuit, a clock generation circuit, and an input / output I / F circuit are interconnected via a bus or dedicated lines.

[0034] The arithmetic circuit 10 has, for example, a storage unit 11, an angle calculation unit 12, a force information calculation unit 13, a first component calculation unit 14, and a second component calculation unit 15. The storage unit 11, the angle calculation unit 12, the force information calculation unit 13, the first component calculation unit 14, and the second component calculation unit 15 are realized, for example, by a processor in the program processing device serving as the arithmetic circuit 10 executing various arithmetic processes according to a program stored in a memory and controlling peripheral circuits such as a counter or an A / D conversion circuit. In addition, the arithmetic circuit 10 may have other functions.

[0035] Signals output from a plurality of strain sensors 203 and the sensor 100 are input to the arithmetic circuit 10. The storage unit 11 stores the input values of x1, y1, and θ a The angle calculation unit 12 calculates the angle θ of the direction of the force F with respect to a specified angle with reference to the values of x1 and y1 stored in the storage unit 11, b and stores the value of θ b in the storage unit 11. Here, θ b is Figures 2 to 5 the angle formed by the positive direction of the x-axis and the direction of the force F, and 0 ≤ θ b ≤ 2π. When the force F' acting in the radial direction of the axis S is directed towards the Figures 2 to 5 n-th quadrant of the coordinates shown, θ b can be calculated, for example, using the following formula (1). Among them, the method for obtaining θ b is not limited to the method using formula (1). Which quadrant of the coordinates the force F' is directed towards can be determined based on the signs of the values of x1 and y1.

[0036] [Equation 1]

[0037]

[0038] The force information calculation unit 13 calculates the magnitude f of the force F by referring to the values of x1 and y1 stored in the storage unit 11 and the value of the distance r from the position where the force F is applied to the axis S, and stores the value (information) of f in the storage unit 11. For example, when the sensor device 1 is used for a bicycle, the force F is the pedaling force applied to the pedal, and r is the distance (the length of the crank) from the pedal to the axis S (crankshaft). f can be calculated using the following formula (2), for example. The method of obtaining f is not limited to the method using formula (2).

[0039] [Equation 2]

[0040]

[0041] The first component calculation unit 14 calculates the magnitude f of the radial component F of the force F by referring to f and θ stored in the storage unit 11 a and θ b values, and stores the value (information) of f in the storage unit 11. f r can be calculated using the following formula (3), for example. The method of obtaining f r is not limited to the method using formula (3). r value (information) is stored in the storage unit 11. f r For example, it can be calculated using the following formula (3). Among them, the method of obtaining f r is not limited to the method using formula (3).

[0042] [Equation 3]

[0043] f r = |f cos(θ a - θ b )| (3)

[0044] The second component calculation unit 15 calculates the magnitude f of the circumferential component F of the force F by referring to f and θ stored in the storage unit 11 a and θ b values, and stores the value (information) of f in the storage unit 11. f t can be calculated using the following formula (4), for example. The method of obtaining f t is not limited to the method using formula (4). t value (information) is stored in the storage unit 11. f t For example, it can be calculated using the following formula (4). Among them, the method of obtaining f t is not limited to the method using formula (4).

[0045] [Equation 4]

[0046] f t = |f sin(θ a - θ b )| (4)

[0047] Here, in the examples of Figure 2 and Figure 3 , the angle formed by the force F and the component F r is θa -θ b , in Figure 4 's example, the angle formed by the force F and the component F r is 2π - θ b +θ a , in Figure 5 's example, the angle formed by the force F and the component F r is θ b -π - θ a . Even in these cases, according to cos(2π - θ b +θ a ) = cos(θ a -θ b ), sin(2π - θ b +θ a ) = sin(θ a -θ b ), and cos(θ b -π - θ a ) = -cos(θ a -θ b ), sin(θ b -π - θ a ) = sin(θ a -θ b ), the magnitude f r and f t can be correctly obtained using the above formula.

[0048] The magnitude f r of the radial component F r of the force F and the magnitude f t of the circumferential component F t are calculated as an example. As long as the correct values or approximate values of these can be obtained, any calculation method can be used. By calculating the magnitude f r of the radial component F r of the force F and the magnitude f t of the circumferential component F t obtained, the value (information) does not necessarily need to be strictly correct and can include errors within the range that does not hinder practical applications.

[0049] Hereinafter, the specific structure of the sensor device 1 of the present embodiment other than the arithmetic circuit 10 will be described. Figure 6 is a perspective view showing a part of the holder 201, the strain sensor 203, and the sensor 100 of the sensor device 1. Figure 7 is a cross-sectional view of the sensor device 1 (wherein the arithmetic circuit 10 is not shown).

[0050] The sensor device 1 includes a sensor 100 that detects information (rotation angle) on the position of the shaft S and a torque sensor 200. The sensor 100 includes: a second bearing 101 having an inner peripheral surface 101a and an outer peripheral surface 101b; and a strain gauge 102 mounted on the outer peripheral surface 101b of the second bearing 101 via a plate portion 141. The torque sensor 200 has a first bearing 202 and a plurality (four in the present embodiment) of strain sensors 203.

[0051] In the present embodiment, the first bearing 202 is a ball bearing having an inner ring 202i, an outer ring 202o, and rolling elements. The second bearing 101 is a ball bearing having an inner ring 101i, an outer ring 101o, and rolling elements. In addition, the first bearing 202 and the second bearing 101 are not limited to ball bearings, and may be various other bearings such as sleeve bearings. In the axial direction, the second bearing 101 is arranged at an interval on one side (arrow a direction) of the first bearing 202. The shaft S has a portion S1 supported by the first bearing 202 and a portion S2 supported by the second bearing 101.

[0052] First, the torque sensor 200 will be described. As Figure 6 shown, the retainer 201 has a substantially square cylindrical shape in plan view and has a holding portion 210 and an outer peripheral member 220. The holding portion 210 is a cylindrical member extending in the axial direction and having a cylindrical inner peripheral surface 210a around the axis X. The holding portion 210 is a member that holds the first bearing 202. The outer peripheral member 220 is a member arranged on one side (arrow c direction) in the radial direction relative to the holding portion 210.

[0053] In the axial direction, the size of the holding portion 210 is the same as the size of the outer peripheral member 220. The end surface on one side (arrow a direction) in the axial direction of the holding portion 210 and the end surface on the other side (arrow b direction) in the axial direction are respectively in the same plane as the end surface on one side (arrow a direction) in the axial direction of the outer peripheral member 220 and the end surface on the other side (arrow b direction) in the axial direction. At the end portion on one side (arrow c direction) in the radial direction and one side (arrow a direction) in the axial direction of the holding portion 210, four substantially rectangular connecting portions 230 in plan view project radially outward (arrow c direction) from the holding portion 210. The four connecting portions 230 are arranged at positions of rotational symmetry (hereinafter, also referred to as "four-fold symmetry" in this specification) that overlap when rotated 90° around the axis X. The connecting portion 230 connects the holding portion 210 to a deformable surface 222 described later.

[0054] At each connecting portion 230, a strain generating body 221 that is rectangular in plan view and substantially L-shaped in side view is connected. The strain generating body 221 is a deforming portion that deforms by receiving stress, and elastically deforms or plastically deforms by receiving stress. The four strain generating bodies 221 form the outer peripheral member 220 of the present embodiment. Since all four strain generating bodies 221 have the same structure, only one strain generating body 221 will be described in detail hereinafter, and the detailed description of the other strain generating bodies 221 will be omitted.

[0055] The strain generating body 221 (outer peripheral member 220) has a deformable surface 222 that extends in the axial direction. The retainer 201 includes a gap 240, which will be described later, between the deformable surface 222 and a holding portion 210 located on the side of the first bearing 202 with respect to the deformable surface 222. Due to the shape of the gap 240, the wall thickness (thickness in the radial direction) of the deformable surface 222 is thinner than other portions of the strain generating body 221 (outer peripheral member 220), and deformation accompanied by strain is likely to occur.

[0056] As Figure 7 shown, in the radial direction, the strain generating body 221 (outer peripheral member 220) faces the holding portion 210 via a gap 240 that extends in the tangential direction or circumferentially. The gap 240 includes a through hole (hole portion) 241 having a circular or substantially circular cross section and a slit 242 connected to the through hole 241. The slit 242 is connected to the through hole 241 at a position near the other side in the axial direction (arrow b direction) and the other side in the radial direction (arrow d direction). In addition, the width (width in the radial direction) of the slit 242 is narrower than the outer shape (diameter) of the through hole 241.

[0057] By forming the through hole 241, in the strain generating body 221 (outer peripheral member 220), a concave portion that is recessed toward one side in the radial direction (arrow c direction) is formed on the surface on the other side in the radial direction (arrow d direction), in the connecting portion 230, a concave portion that is recessed toward one side in the axial direction (arrow a direction) is formed on the surface on the other side in the axial direction (arrow b direction), and in the holding portion 210, a concave portion that is recessed toward the other side in the radial direction (arrow d direction) is formed on the surface on one side in the radial direction (arrow c direction).

[0058] Since each strain generating body 221 has a deformable surface 222, the retainer 201 of the torque sensor 200 as a whole includes a plurality of (four in the present embodiment) deformable surfaces 222. The plurality of deformable surfaces 222 are arranged in the circumferential direction at positions that are four-fold symmetric (rotationally symmetric) ( Figure 6 ).

[0059] A strain sensor 203 is mounted on one side (in the direction of arrow c) in the radial direction of the deformable surface 222. By mounting the strain sensor 203 on each of the plurality of deformable surfaces 222, a plurality (four in the present embodiment) of strain sensors 203 are mounted on the torque sensor 200. The directions of the strains detected by the respective strain sensors 203 are different from each other. The deformable surface 222 and the strain sensor 203 extend along a plane parallel to the axial direction. The strain sensor 203 is mounted in such a manner as to be able to detect the strain of the deformable surface 222. Therefore, in the case where the strain sensor 203 is a strain gauge, it is mounted on the deformable surface 222 in such a manner that the direction of the gate (typically the long side direction of the strain gauge) is the axial direction (refer to Figure 6 arrow D1). In addition, the direction of the gate of the plurality of strain sensors 203 is not limited to the axial direction, and may be a direction inclined with respect to the axial direction. Alternatively, among the plurality of strain sensors, the directions of the gates of two strain sensors 203 facing each other may be the axial direction, and the directions of the other two strain sensors 203 facing each other may be the circumferential direction. Alternatively, the directions of the gates of two strain sensors 203 facing each other may be a direction inclined with respect to the axial direction (first direction), and the directions of the other two strain sensors 203 facing each other may be a direction inclined with respect to the axial direction and a direction crossing the first direction (second direction) and other different directions. In the case where the strain sensor 203 is a strain gauge, the strain of the deformable surface 222 is detected as a change in the resistance value. In addition, the strain sensor 203 is not limited to a strain gauge, and may be various other sensors such as a piezoelectric element.

[0060] In the radial direction, a fixing portion 223 connected to the external device 2 is disposed on one side (in the direction of arrow c) of the strain generating body 221 closer to the deformable surface 222. The fixing portion 223 is a plate-like portion having a quadrilateral shape extending from the end on the other side (in the direction of arrow b) in the axial direction of the deformable surface 222 toward one side (in the direction of arrow c) in the radial direction. A circular through-hole (hole portion) 223h is formed near the central portion of the fixing portion 223. The strain generating body 221 is fixed to the external device 2 via a spacer 205 by a bolt 204 inserted through the through-hole 223h. Thereby, the entire holder 201 is fixed to the external device 2.

[0061] In the radial direction, the first bearing 202 is disposed on the other side (in the direction of arrow d) of the holding portion 210 of the retainer 201. The first bearing 202 is held by the holding portion 210 of the retainer 201. The inner ring 202i of the first bearing 202 is then joined or press-fitted onto the outer peripheral surface (one of the surfaces in the radial direction) of the portion S1 of the cylindrical shaft S supported by the first bearing 202. Thereby, the inner ring 202i of the first bearing 202 is fixed to the shaft S. The outer ring 202o of the first bearing 202 is press-fitted onto the inner peripheral surface 210a of the holding portion 210 of the retainer 201. The first bearing 202 supports the shaft S so as to be rotatable relative to the retainer 201. The end portion on the other side (in the direction of arrow b) in the axial direction of the shaft S projects outward from the through hole (hole portion) 21 of the external device 2 to the outside of the external device 2.

[0062] The end portion on the other side (in the direction of arrow b) in the axial direction of the retainer 201 has an annular contact portion 211 that projects to the other side (in the direction of arrow d) in the radial direction. In the present embodiment, the contact portion 211 projects from the holding portion 210 of the retainer 201 to the other side (in the direction of arrow d) in the radial direction. The contact portion 211 contacts the end surface on the other side (in the direction of arrow b) in the axial direction of the outer ring 202o of the first bearing 202. Thereby, the contact portion 211 supports the first bearing 202 in a state of restricting downward movement in the axial direction.

[0063] Near the end portion on the other side (in the direction of arrow b) in the axial direction of the inner peripheral surface 210a of the holding portion 210, a recess 212 having a semi-circular or substantially semi-circular cross-section that is recessed toward one side (in the direction of arrow c) in the radial direction is formed. The recess 212 is formed in an annular shape around the axis X on one side (in the direction of arrow a) in the axial direction of the contact portion 211. The end portion on the other side (in the direction of arrow b) of the concave surface of the recess 212 is smoothly connected to the end surface on one side (in the direction of arrow a) in the axial direction of the contact portion 211.

[0064] When the sensor device 1 is used for a bicycle, the shaft S is a crankshaft that connects the crank (crank arm) and the pedal. If one of the pedals is depressed, a force acts such that the pedal side of the shaft S tends to tilt downward in the vertical direction. Therefore, the first bearing 202 tends to move in the radial direction, and a part of the retainer 201 is pressed toward one side (in the direction of arrow c) in the radial direction. In the retainer 201, since stress easily concentrates on the deformable surface 222 of the strain generating body 221, deformation accompanied by strain occurs on the deformable surface 222.

[0065] If there are multiple deformable surfaces 222 equipped with strain sensors 203, strain corresponding to tilts in all directions with respect to the axis S can be detected. In particular, in the torque sensor 200, since the four strain generating bodies 221 are located at positions that are four-fold symmetric about the axis X, strain in all directions can be detected more accurately. The amount by which the deformable surface 222 deforms is detected by the multiple strain sensors 203 as information about the force F' acting on the axis S. Based on the detected strain, information about the components x1 and y1 in two orthogonal directions of the force F' acting in the radial direction of the axis S can be calculated.

[0066] The torque sensor 200 has a simple structure including a holder 201, a first bearing 202, and a strain sensor 203, and does not have a detection coil or the like required in the case of using a magnetostrictive sensor disposed around the axis S, so miniaturization of the device can be achieved. In addition, since there is no need to perform processing such as pasting a magnetic layer on the axis S, manufacturing is easy.

[0067] In the torque sensor 200, in the radial direction, the strain generating body 221 (outer peripheral member 220) faces the holding portion 210 via a gap 240. Thus, in the torque sensor 200, the deformable surface 222 of the strain generating body 221 is easily deformed, and stress can be detected with good sensitivity.

[0068] In the torque sensor 200, by forming the recess 212, the wall thickness near the end on the other side (in the direction of arrow b) in the axial direction of the holding portion 210 becomes thinner, so the contact portion 211 is easily elastically deformed in the axial direction to the other side (in the direction of arrow b). Thus, even when a preload is applied to the first bearing 202 in the axial direction to the other side (in the direction of arrow b), since the contact portion 211 elastically deforms, the influence of the preload can be absorbed. Therefore, in the torque sensor 200, it is possible to suppress the preload on the first bearing 202 from being manifested as strain in the deformable surface 222, and the strain sensor 203 can detect stress with high sensitivity.

[0069] Next, a part on one side (in the direction of arrow a) in the axial direction of the torque sensor 200 in the sensor device 1 (the sensor 100 that detects information (rotation angle) about the position of the axis S) will be described. As described above, the sensor 100 has: a second bearing 101 having an inner peripheral surface 101a and an outer peripheral surface 101b; and a strain gauge 102 mounted on the outer peripheral surface 101b of the second bearing 101 via a holder 201.

[0070] An eccentric member 103 having an axial dimension equal to or substantially equal to that of the second bearing 101 is disposed between the inner peripheral surface 101a of the second bearing 101 and the shaft S. The eccentric member 103 eccentrically positions the second bearing 101 and the shaft S relative to each other. In other words, the eccentric member 103 causes the second bearing 101 to be eccentric with respect to the shaft S.

[0071] The eccentric member 103 is a cylindrical member extending in the axial direction and has a cylindrical through-hole (hole portion) having an inner diameter equal to or substantially equal to the outer diameter (diameter) of the shaft S. That is, the eccentric member 103 forms an annular member. In the eccentric member 103, the central axis of the outer peripheral surface (one of the surfaces in the radial direction) does not coincide with the central axis of the inner peripheral surface (the other surface in the radial direction). Therefore, the eccentric member 103 has a portion with the maximum radial thickness (hereinafter referred to as the maximum thickness portion) 103a and a portion with the minimum radial thickness (hereinafter referred to as the minimum thickness portion) 103b.

[0072] The shaft S is joined or press-fitted into the inner peripheral surface (the inner side surface in the radial direction) of the eccentric member 103 at the portion S2 supported by the second bearing 101. Thereby, the shaft S and the eccentric member 103 are integrally fixed. The inner ring 101i of the second bearing 101 is joined or press-fitted into the outer peripheral surface (the outer side surface in the radial direction) of the eccentric member 103. Thereby, the inner ring 101i of the second bearing 101 is fixed to the eccentric member 103. With the above structure, the central axis X of the shaft S is deviated from the central axis Y of the eccentric member 103 and the second bearing 101, and thus the second bearing 101 and the shaft S are in an eccentric positional relationship with respect to each other.

[0073] On the end surface of the holding portion 210 of the retainer 201 on one side (in the direction of arrow a) in the axial direction, four portions (hereinafter referred to as plate portions) 141 stand up toward one side (in the direction of arrow a) in the axial direction. The four plate portions 141 are arranged at positions that are rotationally symmetric four times about the axis X on one side (in the direction of arrow c) of the second bearing 101 in the radial direction. In the circumferential direction, the four plate portions 141 are arranged at positions corresponding to the four strain generating bodies 221. Each plate portion 141 is in contact with the outer peripheral surface 101b of the second bearing 101 via the front end portion 145a on the other side (in the direction of arrow d) in the radial direction of a transmission portion 145 described later. In addition, the second bearing 101 is axially disposed closer to one side (in the direction of arrow a) than the end surface of the holding portion 210 on one side (in the direction of arrow a) in the axial direction.

[0074] Each plate portion 141 holds the strain gauge 102. That is, when viewed from above, the sensor 100 includes, in the clockwise direction: a total of four strain gauges 102 including a first strain gauge 102a held by the first plate portion 141a, a second strain gauge 102b held by the second plate portion 141b, a third strain gauge 102c held by the third plate portion 141c, and a fourth strain gauge 102d held by the fourth plate portion 141d.

[0075] Two adjacent strain gauges 102 in the circumferential direction, for example, the first strain gauge 102a and the second strain gauge 102b, are arranged at positions symmetric with respect to a plane containing the axis X. In the sensor 100, the angle formed by the direction from the axis X toward the first strain gauge 102a and the direction from the axis X toward the second strain gauge 102b is 90°. Here, the angle may not be 90°. Since all four plate portions 141 have the same structure, hereafter only one plate portion 141 will be described in detail, and for the other plate portions 141, detailed descriptions will be omitted except in necessary cases.

[0076] In the radial direction, on the other side (in the direction of arrow d) of the plate portion 141, a concave portion 144 having a semi-circular cross-section extending in the tangential direction or the circumferential direction is formed. The concave portion 144 is formed near the end on the other side (in the direction of arrow b) in the axial direction of the plate portion 141. In the plate portion 141, the wall thickness of the portion where the concave portion 144 is formed becomes thinner, and it becomes a deformable portion 142 that can deform along with the strain. The strain gauge 102 is mounted on one side (in the direction of arrow c) in the radial direction of the deformable portion 142. The strain-induced deformation of the deformable portion 142 can be detected as a change in the resistance value of the strain gauge 102. At the central portion of the plate portion 141 in the tangential direction or the circumferential direction and on the side closer to one side (in the direction of arrow a) in the axial direction than the concave portion 144, a circular hole penetrating in the radial direction, that is, an opening portion 141h, is formed. A transfer portion 145 having a pin-like outer shape is inserted into the opening portion 141h. The transfer portion 145 is fixed to the opening portion 141h by bonding or press-fitting.

[0077] The transfer portion 145 has a pointed front end portion 145a. The transfer portion 145 is arranged such that the front end portion 145a protrudes more toward the other side (in the direction of arrow d) than the plate portion 141 in the radial direction. The outer peripheral surface 101b of the second bearing 101 is in point contact with the front end portion 145a of the transfer portion 145. Therefore, the transfer portion 145 can transmit the displacement of the second bearing 101 to the plate portion 141 via the front end portion 145a.

[0078] At Figure 7In this case, the maximum thickness portion 103a of the eccentric member 103 is located close to the third plate portion 141c, and the minimum thickness portion 103b of the eccentric member 103 is located close to the first plate portion 141a. Therefore, the third plate portion 141c is pressed by the second bearing 101 to one side in the radial direction (arrow c direction). In addition, the second plate portion 141b and the fourth plate portion 141d adjacent to the third plate portion 141c are also slightly pressed by the second bearing 101 to one side in the radial direction (arrow c direction).

[0079] Therefore, in Figure 7 this case, the deformed portion 142 of the third plate portion 141c deforms maximally with strain, and one side in the axial direction (arrow a direction) of the third plate portion 141c is in a state of warping toward one side in the radial direction (arrow c direction). The deformed portions 142 of the second plate portion 141b and the fourth plate portion 141d adjacent to the third plate portion 141c are in a state of slightly deforming with strain. The deformed portion 142 of the first plate portion 141a is in a state of minimally deforming with strain or not deforming with strain at all.

[0080] If the shaft S rotates, the eccentric member 103 fixed to the shaft S also rotates together, and accordingly, the central axis Y of the second bearing 101 rotates about the axis X. For example, if the shaft S rotates in the clockwise direction in a top view, the central axis Y of the second bearing 101 rotates about the axis X in the clockwise direction in a top view. If starting from the Figure 7 state, the central axis Y of the second bearing 101 is rotated 90° about the axis X in the clockwise direction in a top view, the deformed portion 142 of the fourth plate portion 141d migrates to the state of maximally deforming with strain.

[0081] Thus, in the sensor 100, every time the central axis Y of the second bearing 101 rotates 90° about the axis X in the clockwise direction in a top view, the deformed portions 142 of the third plate portion 141c, the fourth plate portion 141d, the first plate portion 141a, and the second plate portion 141b migrate in sequence to the state of maximally deforming with strain. Therefore, the rotation angle of the shaft S can be detected by the strain gauges 102 installed on each plate portion 141.

[0082] In the sensor device 1 of the present embodiment, signals output from the plurality of strain sensors 203 and the sensor 100 are input to the arithmetic circuit 10, and the arithmetic circuit 10 calculates the magnitude f r of the radial component F r and the magnitude f t of the circumferential component F t in the information of the force F that rotates the shaft S. Thereby, the sensor device 1 can separate the information of the force F that rotates the shaft S into the radial component F r and the circumferential component Ft Calculated as follows.

[0083] When the sensor device 1 is used for a bicycle, the force F applied to rotate the shaft S is the pedaling force applied by the driver's foot to the pedal. The circumferential component of the pedaling force F (corresponding to F t ) contributes to the rotation of the crank and the shaft S. In other words, it is equivalent to the driving force for the rotation of the crank and the shaft S. On the other hand, the radial component of the pedaling force F (corresponding to F r ) is difficult to contribute to the rotation of the crank and the shaft S. In other words, it is difficult to contribute to the rotation of the crank and the shaft S and is equivalent to a loss force. The sensor device 1 can calculate the magnitude f r of the radial component F r and the magnitude f t of the circumferential component F t . Therefore, for example, by outputting this information from the arithmetic circuit 10 to the cycle computer, the driver can be prompted to change to a more efficient pedaling method. Further, when the sensor device 1 is used for an electric assist bicycle or the like, by outputting a signal corresponding to the magnitude f r of the radial component F r and the magnitude f t of the circumferential component F t of the pedaling force F to the motor drive unit, it is possible to assist the control based on the motor drive unit.

[0084] [Modification Example]

[0085] As described above, the sensor device of the present invention has been described by listing preferred embodiments, but the sensor device of the present invention is not limited to the structure of the above-described embodiments. For example, although the sensor device 1 of the above-described embodiment is described as being used for a bicycle, the sensor device of the present invention is not limited to being used for a bicycle and can also be used for a moving body or a rotating device.

[0086] Since the sensor 100 and the torque sensor 200 of the sensor device 1 of the above-described embodiment are of an integrated structure, the overall design can be made small. However, in the sensor device of the present invention, the sensor for detecting the information on the position of the shaft may not be integrated with the holder on which a plurality of strain sensors are mounted.

[0087] The sensor 100 of the sensor device 1 of the above-described embodiment is mounted in a state where it is eccentric with the shaft S by the second bearing 101 by using the annular eccentric member 103. However, without using the annular eccentric member 103, a wedge-shaped member is interposed between the second bearing 101 and the shaft S, whereby the second bearing 101 and the shaft S can be made eccentric with each other.

[0088] The sensor 100 of the sensor device 1 of the above-described embodiment detects information on the position of the shaft S through the strain gauge 102. However, in the sensor device of the present invention, the sensor for detecting information on the position of the shaft may be any sensor as long as it can detect the rotation angle of the shaft. For example, the sensor for detecting information on the position of the shaft may be an optical sensor using a light-emitting element and a light-receiving element, or a magnetic sensor such as a Hall sensor. The sensor for detecting information on the position of the shaft may not be a sensor in the strict sense. For example, it may be a device that can detect the position of the shaft based on the rotational speed of a roller or the like that rotates in contact with the shaft. The sensor for detecting information on the position of the shaft may be arranged near the holder on which a plurality of strain sensors are mounted, or may be arranged at a remote position. The sensor for detecting information on the position of the shaft may be configured to be away from the shaft. For example, the sensor for detecting information on the position of the shaft may be arranged on a chain link, a sprocket, a rear wheel, a crank, or a pedal of a bicycle. In addition, in a moving body or a rotating device, a sensor may also be provided inside or on the side of the housing.

[0089] In the sensor device 1 of the above-described embodiment, four strain sensors 203 are mounted on the holder 201. However, regarding the number of strain sensors mounted on the holder in the sensor device of the present invention, as long as the arithmetic circuit can finally calculate the magnitudes of the components in the radial and circumferential directions of the force applied to rotate the shaft, the number may be two, three, or five or more. At least two of the plurality of strain sensors are preferably arranged to be circumferentially offset from each other by 90°. However, the offset angle may be more than 0° and less than 180°, may be 20° or more and 160° or less, may be 40° or more and 140° or less, may be 60° or more and 120° or less, or may be 80° or more and 100° or less.

[0090] In the sensor device of the present invention, the structure of the holder on which a plurality of strain sensors are mounted is not limited to the holder 201 of the torque sensor 200 of the sensor device 1 of the above-described embodiment. For example, in the sensor device of the present invention, the holder on which a plurality of strain sensors are mounted may have Figures 8 to 16 the structure of the shown modification, or may have a further different structure. In addition, in Figures 8 to 16 the sensor for detecting information on the position of the shaft S and the arithmetic circuit are omitted.

[0091] (Modification 1)

[0092] Hereinafter, the Figure 8 shown torque sensor 300 will be described. Figure 8It is a sectional view showing the state where the torque sensor 300 is installed on the shaft S and the external device 2. The torque sensor 300 has the same structure as the torque sensor 200 except for the aspect that the retainer 301 is included instead of the retainer 201. The retainer 301 has the same structure as the retainer 201 except for the aspect that the holding portion 310 is included instead of the holding portion 210 and has a clearance 340 with a shape different from that of the clearance 240. Hereinafter, for members and parts having the same functions and structures as those of the torque sensor 200, the same reference signs are given and their detailed descriptions are omitted.

[0093] The retainer 301 has a substantially square cylindrical shape in a plan view and has a holding portion 310 and an outer peripheral member 220. The holding portion 310 is a cylindrical member extending in the axial direction and having a cylindrical inner peripheral surface 310a around the axis X. The holding portion 310 is a member for holding the first bearing 202. The outer peripheral member 220 is a member arranged radially outside the holding portion 310.

[0094] At the end of the holding portion 310 on one side in the radial direction (arrow c direction) and one side in the axial direction (arrow a direction), four connecting portions 330 having a substantially rectangular shape in a plan view project radially from the holding portion 310 to one side in the radial direction (arrow c direction). The four connecting portions 330 are arranged at positions that are four-fold symmetric around the axis X. A strain generating body 221 is connected to each connecting portion 330.

[0095] As Figure 8 shown, in the radial direction, the strain generating body 221 (outer peripheral member 220) faces the holding portion 210 via a clearance 340 extending in the tangential or circumferential direction. The clearance 340 includes: a through-hole (hole portion) 341 having a circular or substantially circular cross-section; and a slit 342 connected to the other side in the axial direction (arrow b direction) of the through-hole 341 and having a width (radial width) narrower than the diameter of the through-hole 341. In the radial direction, the size of the slit 342 formed in the retainer 301 is smaller than Figure 7 the size of the slit 242 formed in the retainer 201 as shown.

[0096] By forming the through-hole 341, a concave portion recessed toward one side in the radial direction (arrow c direction) is formed on the surface of the strain generating body 221 (outer peripheral member 220) on the other side in the radial direction (arrow d direction), a concave portion recessed toward one side in the axial direction (arrow a direction) is formed on the surface of the connecting portion 330 on the other side in the axial direction (arrow b direction), and a concave portion recessed toward the other side in the radial direction (arrow d direction) is formed on the surface of the holding portion 310 on one side in the radial direction (arrow c direction).

[0097] The end of the retainer 301 on the other axial side (in the direction of arrow b) has an annular contact portion 311 that protrudes toward the other radial side (in the direction of arrow d). In this modification, the contact portion 311 protrudes from the end of the holding portion 310 of the retainer 301 on the other axial side (in the direction of arrow b) toward the other radial side (in the direction of arrow d). The contact portion 311 contacts the end face on the other axial side (in the direction of arrow b) of the outer ring 202o of the first bearing 202. Thus, the contact portion 311 supports the first bearing 202 in a state of restricting downward movement in the axial direction.

[0098] Figure 8 The clearance 340 formed in the retainer 301 shown in Figure 7 has a simpler shape compared to the clearance 240 formed in the retainer 201 shown in. Further, in Figure 8 the retainer 301 shown in, no member corresponding to the concave portion 212 formed in the retainer 201 shown in Figure 7 is formed. Therefore, Figure 8 the retainer 301 shown in Figure 7 is easier to manufacture than the retainer 201 shown in.

[0099] (Modification 2)

[0100] Next, the torque sensor 400 shown in Figure 9 will be described. Figure 9 is a cross-sectional view showing the state where the torque sensor 400 is installed on the shaft S and the external device 2. The torque sensor 400 has the same structure as the torque sensor 300 of Modification 1 except that a retainer 401 is included instead of the retainer 301. Hereinafter, members and parts having the same functions and structures as those of the torque sensor 300 of Modification 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0101] The retainer 401 has a substantially square cylindrical shape in plan view and has a holding portion 410 and an outer peripheral member 420. The holding portion 410 is a cylindrical member extending in the axial direction and having a cylindrical inner peripheral surface 410a around the axis X. The outer peripheral member 420 is a member disposed radially on the one side (in the direction of arrow c) closer to the holding portion 410.

[0102] Axially, the dimension of the holding portion 410 is smaller than that of the outer peripheral member 420. Axially, the end surface of one side (in the direction of arrow a) of the holding portion 410 is in the same plane as the end surface of one side (in the direction of arrow a) of the outer peripheral member 420. At the end portion on one side in the radial direction (in the direction of arrow c) and one side in the axial direction (in the direction of arrow a) of the holding portion 410, four connecting portions 430, which are substantially rectangular in plan view, project radially outward in the radial direction (in the direction of arrow c) from the holding portion 410. The four connecting portions 430 are arranged at positions that are four-fold symmetric about the axis X.

[0103] Connected to each of the connecting portions 430 is a strain generating body 421 that is rectangular in plan view and substantially T-shaped in side view. The strain generating body 421 is a deforming portion that deforms by receiving stress and undergoes elastic deformation or plastic deformation by receiving stress. The four strain generating bodies 421 constitute the outer peripheral member 420 of the present embodiment. Since all four strain generating bodies 421 have the same structure, only one strain generating body 421 will be described in detail hereinafter, and the detailed description of the other strain generating bodies 421 will be omitted.

[0104] The strain generating body 421 (outer peripheral member 420) has a deformable surface 422 that extends in the axial direction. The retainer 401 includes a gap 440, which will be described later, between the deformable surface 422 and the holding portion 410 on the side of the first bearing 202 with respect to the deformable surface 422. Due to the shape of the gap 440, the wall thickness (thickness in the radial direction) of the deformable surface 422 is thinner than that of the other parts of the strain generating body 421 (outer peripheral member 420), and deformation accompanied by strain is likely to occur.

[0105] As Figure 9 shown, radially, the strain generating body 421 (outer peripheral member 420) faces the holding portion 410 via a gap 440 that extends in the tangential or circumferential direction. The gap 440 includes: a first through hole (hole portion) 441 having a circular or substantially circular cross section; a second through hole (hole portion) 442 that is connected to the other side in the axial direction (in the direction of arrow b) of the first through hole 441 and has a diameter equal to or slightly smaller than that of the first through hole 441; and a slit 443 that extends from the end portion on the other side in the axial direction (in the direction of arrow b) of the second through hole 442 toward the other side in the radial direction (in the direction of arrow d) to the first bearing 202.

[0106] By forming a first through-hole 441, in the strain generating body 421 (outer peripheral member 420), a concave portion that is recessed toward one side in the radial direction (arrow c direction) is formed on the surface on the other side in the radial direction (arrow d direction). In the connecting portion 430, a concave portion that is recessed toward one side in the axial direction (arrow a direction) is formed on the surface on the other side in the axial direction (arrow b direction). In the holding portion 410, a concave portion that is recessed toward the other side in the radial direction (arrow d direction) is formed on the surface on one side in the radial direction (arrow c direction).

[0107] Each strain generating body 421 has a deformable surface 422. Therefore, the holder 401 of the torque sensor 400 as a whole includes a plurality of (four in this modification example) deformable surfaces 422. The plurality of deformable surfaces 422 are arranged in the circumferential direction at positions that are four-fold symmetric.

[0108] A strain sensor 203 is mounted on one side in the radial direction (arrow c direction) of the deformable surface 422. By mounting the strain sensor 203 on each of the plurality of deformable surfaces 422, a plurality of (four in this modification example) strain sensors 203 are mounted on the torque sensor 400. The deformable surface 422 and the strain sensor 203 each extend along a plane parallel to the axial direction. The strain sensor 203 is mounted in such a manner that the strain of the deformable surface 422 can be detected. Therefore, when the strain sensor 203 is a strain gauge, it is mounted on the deformable surface 422 with the direction of the grid (typically the long side direction of the strain gauge) as the axial direction. When the strain sensor 203 is a strain gauge, the strain of the deformable surface 422 is detected as a change in the resistance value. The directions of the strains detected by the respective strain sensors 203 are different from each other.

[0109] The holder 401 has a plate-like contact portion 424 that protrudes toward the other side in the radial direction (arrow d direction) at the end on the other side in the axial direction (arrow b direction). In this modification example, the contact portion 424 protrudes from the end on the other side in the axial direction (arrow b direction) of the strain generating body 421 (outer peripheral member 420) of the holder 401 toward the other side in the radial direction (arrow d direction). In the axial direction, the contact portion 424 faces the holding portion 410 via a slit 443. The tangential direction or the circumferential dimension of the contact portion 424 is the same as the tangential direction or the circumferential dimension of the strain generating body 421. Here, the contact portion 424 may be formed in an annular shape around the axis X. In the axial direction, the contact portion 424 contacts the end surface on the other side (arrow b direction) of the outer ring 202o of the first bearing 202. Thereby, the contact portion 424 supports the first bearing 202 in a state of restricting downward movement in the axial direction.

[0110] In this modified example, since the contact portion 424 is not provided in the holding portion 410, the influence of the preload in the axial direction on the first bearing 202 can be suppressed from being transmitted to the deformable surface 422 via the connecting portion 430.

[0111] (Modified Example 3)

[0112] Next, the torque sensor 500 shown Figure 10 will be described. Figure 10 is a cross-sectional view showing a state in which the torque sensor 500 is mounted on the shaft S and the external device 2. The torque sensor 500 has the same structure as the torque sensor 300 of the first modified example, except that a retainer 501 is included instead of the retainer 301. The retainer 501 has the same structure as the retainer 301 of the first modified example, except that a holding portion 510 is included instead of the holding portion 310 and a clearance 540 having a shape different from that of the clearance 340 is formed. Hereinafter, members and parts having the same functions and structures as those of the torque sensor 300 of the first modified example will be denoted by the same reference numerals, and their detailed descriptions will be omitted.

[0113] The retainer 501 has a substantially square cylindrical shape in plan view and includes a holding portion 510 and an outer peripheral member 220. The holding portion 510 is a cylindrical member extending in the axial direction and having a cylindrical inner peripheral surface 510a around the axis X. In the axial direction, the size of the holding portion 510 is smaller than that of the outer peripheral member 220. In the axial direction, the end surface of one side (arrow a direction) of the holding portion 510 is in the same plane as the end surface of one side (arrow a direction) of the outer peripheral member 220. At the end of the holding portion 510 on one side (arrow c direction) in the radial direction and one side (arrow a direction) in the axial direction, four substantially rectangular connecting portions 530 project radially outward (arrow c direction) from the holding portion 510. The four connecting portions 530 are arranged at positions that are four-fold symmetric about the axis X. A strain generating body 221 is connected to each of the connecting portions 530.

[0114] As Figure 10 shown, in the radial direction, the strain generating body 221 (outer peripheral member 220) faces the holding portion 510 via a clearance 540 extending in the tangential or circumferential direction. The clearance 540 includes: a through hole (hole portion) 541 having a circular or substantially circular cross section; and a slit 542 connected to the other side (arrow b direction) in the axial direction of the through hole 541 and having a width (radial dimension) narrower than the diameter of the through hole 541. The slit 542 widens in a manner such that the cross section expands in an arc shape toward the other side (arrow d direction) in the radial direction as it approaches the other side (arrow b direction) in the axial direction.

[0115] By forming a through hole 541, in the strain generating body 221 (outer peripheral member 220), a concave portion that is recessed toward one side in the radial direction (arrow c direction) is formed on the surface on the other side in the radial direction (arrow d direction). In the connecting portion 530, a concave portion that is recessed toward one side in the axial direction (arrow a direction) is formed on the surface on the other side in the axial direction (arrow b direction). In the holding portion 510, a concave portion that is recessed toward the other side in the radial direction (arrow d direction) is formed on the surface on one side in the radial direction (arrow c direction).

[0116] A protruding portion 22 that protrudes toward one side in the axial direction (arrow a direction) toward the first bearing 202 and is formed in a circular ring shape around the axis X is fixed to the external device 2. Here, the protruding portion 22 may also be a plurality of convex portions arranged on the circumference around the axis X. In the axial direction, the protruding portion 22 is in contact with the end surface on the other side (arrow b direction) of the first bearing 202. Thus, the protruding portion 22 supports the first bearing 202 in a state of restricting downward movement in the axial direction. More specifically, in the axial direction, the protruding portion 22 supports the first bearing 202 by being in contact with the end surface on the other side (arrow b direction) of the outer ring 202o.

[0117] In this modification, since the protruding portion 22 supports the first bearing 202 in the axial direction, it is possible to suppress the influence of the preload in the axial direction on the strain of the deformable surface 222 of the first bearing 202.

[0118] (Modification 4)

[0119] Next, an explanation will be given of Figure 11 and Figure 12 the retainer 601 and the torque sensor 600 shown. Figure 11 is a plan view of the retainer 601 and the strain sensor 603. Figure 12 is a cross-sectional view showing the cross-section corresponding to the A-A cross-section in Figure 11 in a state where the torque sensor 600 is mounted on the shaft S and the external device 60.

[0120] The torque sensor 600 includes a retainer 601, a first bearing 602, and a strain sensor 603. In this modification, the first bearing 602 is a ball bearing having an inner ring 602i, an outer ring 602o, and rolling elements. In addition, the first bearing 602 is not limited to a ball bearing, and may be other various first bearings such as a sleeve bearing, for example.

[0121] The retainer 601 has a substantially square cylindrical shape in a plan view and includes a holding portion 610 and an outer peripheral member 620. The holding portion 610 is a cylindrical member extending in the axial direction and having a cylindrical inner peripheral surface 610a around the axis X. The outer peripheral member 620 is a member arranged on one side (arrow c direction) in the radial direction relative to the holding portion 610.

[0122] In the axial direction, the dimension of the holding portion 610 is the same as that of the outer peripheral member 620. In the axial direction, the end surfaces on one side (in the direction of arrow a) and the other side (in the direction of arrow b) of the holding portion 610 are in the same plane as the end surfaces on one side (in the direction of arrow a) and the other side (in the direction of arrow b) of the outer peripheral member 620, respectively.

[0123] In the radial direction, on one side (in the direction of arrow c) of the holding portion 610, two strain generating bodies 621 are connected in a manner that is mirror-symmetrical with respect to the plane containing the axis X. The strain generating body 621 is a deforming portion that deforms by receiving stress and undergoes elastic deformation or plastic deformation by receiving stress. The strain generating body 621 is in a substantially rectangular parallelepiped shape with the tangential direction or the circumferential direction as the long side direction, and is formed in a shape where the central portion in the long side direction is lacking in an arc shape along the outer shape of the holding portion 610 to about half of the radial dimension. The two strain generating bodies 621 form the outer peripheral member 620 of the present embodiment. Since the two strain generating bodies 621 have the same structure, only one strain generating body 621 will be described in detail hereafter, and the detailed description of the other strain generating body 621 will be omitted.

[0124] As Figure 11 shown, near the middle points between the central portion and the both end portions in the long side direction of the strain generating body 621, one through-hole (hole portion) 641 each, for a total of two, that penetrates in the axial direction and is circular or substantially circular in a top view is formed. In addition, two slits 642 that extend from the vicinity of the connecting portion with the holding portion 610 on the surface facing the holding portion 610 of the strain generating body 621 in the tangential direction or the circumferential direction to the through-hole 641 are formed in the strain generating body 621. The width of the slit 642 is narrower than the diameter of the through-hole 641. The through-hole 641 and the slit 642 constitute the gap 640.

[0125] The strain generating body 621 (outer peripheral member 620) has a deforming portion 622. In the portion of the strain generating body 621 that extends along the plane perpendicular to the radial direction, the region near the through-hole 641 becomes the deforming portion 622. In the radial direction, the deforming portion 622 faces the holding portion 610 with a gap 640 therebetween. The deforming portion 622 has a concave portion (a part of the through-hole 641) that is recessed in the radial direction on the surface facing the holding portion 610. Due to the presence of the through-hole 641, the wall thickness of the deforming portion 622 is thinner than other parts of the strain generating body 621 (outer peripheral member 620), and it is easy to generate deformation accompanied by strain.

[0126] Since the respective strain generating bodies 621 of the torque sensor 600 have deformation portions 622, the torque sensor 600 as a whole includes a plurality (four in this deformation example) of deformation portions 622. In the circumferential direction, the plurality of deformation portions 622 are arranged and disposed on one side (arrow c direction) of the holder 601 (on one side (arrow c direction) in the radial direction relative to the holding portion 610).

[0127] On the surface of each strain generating body 621 on the side opposite to the side connected to the holding portion 610 and extending in the axial direction and the tangential direction or the circumferential direction (the deformable surface), two strain sensors 603 are mounted. The strain sensors 603 are mounted on the deformation portions 622 of the strain generating bodies 621. The deformation portions 622 and the strain sensors 603 extend along a plane extending in the axial direction and the long side direction of the strain generating bodies 621. The strain sensors 603 are mounted so as to be able to detect the strain in the direction of the plane perpendicular to the axial direction of the deformation portions 622. Therefore, in the case where the strain sensors 603 are strain gauges, they are mounted on the deformation portions 622 in such a manner that the direction of the grid (gauge) (typically the long side direction of the strain gauge) is along the long side direction of the strain generating bodies 621. In the case where the strain sensors 603 are strain gauges, the strain of the deformation portions 622 is detected as a change in the resistance value. In addition, the strain sensors 603 are not limited to strain gauges, and may also be various other sensors such as piezoelectric elements.

[0128] The portions on both ends of the strain generating bodies 621 on the long side direction relative to the deformation portions 622 become fixed portions 623 connected to the external device 60. A through hole (hole portion) 623h that is circular in plan view and penetrates in the axial direction is formed near the central portion of the fixed portion 623. As Figure 12 shown, the strain generating body 621 is fixed to the external device 60 via a spacer 605 by a bolt 604 inserted into the through hole 623h from one side (arrow a direction) in the axial direction. Thereby, the holder 601 is fixed to the external device 60.

[0129] In the radial direction, the first bearing 602 is disposed on the other side (arrow d direction) of the holding portion 610 of the holder 601. The first bearing 602 is held by the holding portion 610 of the holder 601. The inner ring 602i of the first bearing 602 is then connected to or press-fitted onto the outer peripheral surface (one side surface in the radial direction) of the cylindrical shaft S. Thereby, the inner ring 602i of the first bearing 602 is fixed to the shaft S. The outer ring 602o of the first bearing 602 is press-fitted onto the inner peripheral surface 610a of the holding portion 610 of the holder 601. The first bearing 602 supports the shaft S so as to be rotatable relative to the holder 601. The end portion on the other side (arrow b direction) in the axial direction of the shaft S protrudes from the through hole 61 of the external device 60 to the outside of the external device 60.

[0130] The end of the retainer 601 on the other axial side (in the direction of arrow b) has an annular contact portion 611 protruding toward the other radial side (in the direction of arrow d). In this modified example, the contact portion 611 protrudes from the end of the holding portion 610 of the retainer 601 on the other axial side (in the direction of arrow b) toward the other radial side (in the direction of arrow d). Axially, the contact portion 611 contacts the end face of the outer ring 602o of the first bearing 602 on the other side (in the direction of arrow b). Thus, the contact portion 611 supports the first bearing 602 in a state of restricting downward movement axially.

[0131] When the torque sensor 600 is used for a bicycle, the shaft S is a crankshaft connecting the crank and the pedal. If one of the pedals is depressed, a force acts such that the pedal side of the shaft S tends to tilt downward in the vertical direction. Therefore, the first bearing 602 tends to move radially, and a part of the retainer 601 is pressed toward one of the radial sides (in the direction of arrow c). In the retainer 601, since stress easily concentrates on the deformed portion 622 of the strain generating body 621, deformation accompanied by strain occurs in the deformed portion 622. The deformation accompanied by strain is detected by the strain sensor 603.

[0132] (Modified Example 5)

[0133] Next, the retainer 701 and the torque sensor 700 shown in Figure 13 and Figure 14 will be described. Figure 13 is a plan view of the retainer 701 and the strain sensor 603. Figure 14 is a cross-sectional view showing a cross-section corresponding to the B-B cross-section in Figure 13 in a state where the torque sensor 700 is mounted on the shaft S and the external device 70. The torque sensor 700 has the same structure as the torque sensor 600 of the modified example 4 except for including a retainer 701 instead of the retainer 601. Hereinafter, members and parts having the same functions and structures as those of the modified example 4 are denoted by the same reference numerals and their detailed descriptions are omitted.

[0134] The torque sensor 700 has a retainer 701, a first bearing 602, and a strain sensor 603. The retainer 701 has a substantially square cylindrical shape in a top view and has a holding portion 710 and an outer peripheral member 720. The holding portion 710 is a cylindrical member extending in the axial direction and having a cylindrical inner peripheral surface 710a around the axis X. The outer peripheral member 720 is a member disposed radially on one side (in the direction of arrow c) relative to the holding portion 710. The schematic structure of the retainer 701 is similar to that of the retainer 601 of the torque sensor 600 in Modification 4, but is different from the retainer 601 of the torque sensor 600 in Modification 4 in that the axial dimension of the holding portion 710 is longer and the holding portion 710 and the outer peripheral member 720 are connected in a manner that they are offset from each other in the axial direction.

[0135] As Figure 14 shown, in the axial direction, the dimension of the holding portion 710 is larger than the dimension of the outer peripheral member 720. In the axial direction, one end surface (in the direction of arrow a) and the other end surface (in the direction of arrow b) of the holding portion 710 are respectively disposed on one side (in the direction of arrow a) relative to one end surface (in the direction of arrow a) and the other end surface (in the direction of arrow b) of the outer peripheral member 720. One end (in the direction of arrow a) of the outer peripheral member 720 in the axial direction is connected near the other end (in the direction of arrow b) of the holding portion 710 in the axial direction.

[0136] The retainer 701 has an annular contact portion 711 protruding toward the other side (in the direction of arrow d) in the radial direction at a position slightly closer to one side (in the direction of arrow a) from the central portion in the axial direction. In the axial direction, the contact portion 711 is disposed on one side (in the direction of arrow a) relative to one end (in the direction of arrow a) of the outer peripheral member 720. In this modification, the contact portion 711 protrudes toward the other side (in the direction of arrow d) in the radial direction from near the central portion of the holding portion 710 of the retainer 701 in the axial direction. In the axial direction, the contact portion 711 contacts the other end surface (in the direction of arrow b) of the outer ring 602o of the first bearing 602. Thus, the contact portion 711 supports the first bearing 602 in a state of restricting downward movement in the axial direction.

[0137] In the axial direction, the portion of the holding portion 710 on the other side (in the direction of arrow b) relative to the contact portion 711 penetrates the external device 70 and extends to the other side (in the direction of arrow b) relative to the external device 70. In the axial direction, the outer peripheral member 720 is disposed on the other side (outside the external device 70) of the external device 70. The bolt 604 is inserted axially from the other side (in the direction of arrow b) into a through hole (hole portion) 623h of a fixing portion 623 of a strain generating body 621 formed in the outer peripheral member 720.

[0138] In this modification example, since the outer peripheral member 720 is disposed outside the external device 70, the structure inside the external device 70 is further simplified, and miniaturization of the device can be achieved.

[0139] (Modification Example 6)

[0140] Next, the retainer 801 shown in Figure 15 will be described. Figure 15 is a perspective view of the retainer 801 and the strain sensor 803 of this modification example.

[0141] The retainer 801 has a flat plate shape and includes a holding portion 810 and an outer peripheral member 820. The holding portion 810 is a plate-like member having a substantially square shape in plan view and having a cylindrical inner peripheral surface 810a around the axis X. The outer peripheral member 820 is a member disposed on one side (in the direction of arrow c) in the radial direction with respect to the holding portion 810.

[0142] On two surfaces of the outer peripheral surface (one surface in the radial direction) of the holding portion 810 that face each other across the axis X, a strain generating body 821 is connected to the center of each. The strain generating body 821 is a member that extends with the radial direction as the long side direction and has an end portion on one side (in the direction of arrow c) that is substantially semicircular in plan view. In the tangential direction or the circumferential direction, the size of the strain generating body 821 is smaller than the size of the holding portion 810. The two strain generating bodies 821 form the outer peripheral member 820 in this modification example. Since the two strain generating bodies 821 have the same structure, only one strain generating body 821 will be described in detail hereinafter, and the detailed description of the other strain generating bodies 821 will be omitted.

[0143] In the strain generating body 821 (outer peripheral member 820), a through hole (gap) 840 that penetrates in the axial direction is formed near the connecting portion with the holding portion 810. The through hole 840 is formed in a shape in which two holes that are circular or substantially circular in plan view and are arranged in the tangential direction or the circumferential direction are connected by a hole that is rectangular in plan view.

[0144] The strain generating body 821 (outer peripheral member 820) has a deformed portion 822. In the strain generating body 821, two portions that face each other in the tangential direction or the circumferential direction via the through hole 840 become the deformed portion 822. By forming the through hole 840, the wall thickness of the deformed portion 822 is thinner than other portions of the strain generating body 821 (outer peripheral member 820), and deformation accompanied by strain is likely to occur. Since each strain generating body 821 of the retainer 801 has two deformed portions 822, the retainer 801 as a whole includes a plurality of (four in this modification example) deformed portions 822.

[0145] Two strain sensors 803 are mounted on the axially extending outer peripheral surface (deformable surface) of each strain generating body 821. The strain sensors 803 are mounted on the deformation portion 822. The deformation portion 822 and the strain sensors 803 extend in the axial direction and the protruding direction (long side direction) of the strain generating body 821. The strain sensors 803 are mounted so as to be able to detect the strain in the direction along the plane perpendicular to the axial direction of the deformation portion 822. Therefore, when the strain sensor 803 is a strain gauge, it is mounted on the deformation portion 822 in such a manner that the direction of the gate (gauge) (typically the long side direction of the strain gauge) is along the protruding direction (long side direction) of the strain generating body 821. Herein, the strain sensor 803 may also be mounted on the deformation portion 822 in such a manner that the direction of the gate is the axial direction (refer to Figure 15 arrow D2). When the strain sensor 803 is a strain gauge, the strain of the deformation portion 822 is detected as a change in the resistance value. In addition, the strain sensor 803 is not limited to a strain gauge, and may also be various other sensors such as a piezoelectric element.

[0146] In the radial direction, on one side (arrow c direction) of the deformation portion 822 of the strain generating body 821, there is a fixed portion 823 connected to an external device (not shown). A circular through-hole (hole portion) 823h is formed near the central portion of the fixed portion 823. The holder 801 can be fixed to the external device via the through-hole 823h and by means of bolts or the like.

[0147] In the radial direction, a bearing (not shown) is disposed on the other side (arrow d direction) of the holding portion 810 of the holder 801. The end portion of the holder 801 on the other side (arrow b direction) in the axial direction has an annular contact portion 811 protruding toward the other side (arrow d direction) in the radial direction. In this modification example, the contact portion 811 protrudes from the holding portion 810 of the holder 801 toward the other side (arrow d direction) in the radial direction. In the axial direction, the contact portion 811 contacts the end surface on the other side (arrow b direction) of the bearing. Thereby, the contact portion 811 can support the bearing in the axial direction.

[0148] In the case where a torque sensor including a retainer 801 is used for a bicycle, the shaft S is a crankshaft including a pedal. If one of the pedals is depressed, a force acts such that the pedal side of the shaft S tends to tilt downward in the vertical direction, and thus the bearing tends to move radially, and a part of the retainer 801 is pressed toward one side in the radial direction (the direction of arrow c). In the retainer 801, since stress easily concentrates on the deformed portion 822 of the strain generating body 821, deformation accompanied by strain is generated in the deformed portion 822. The deformation accompanied by strain is detected by the strain sensor 803. The retainer 801 of this modification example is in a flat plate shape, and moreover, since it is fixed to an external device only by two fixing portions 823, the structure is simple, and miniaturization and weight reduction of the device can be achieved.

[0149] (Modification Example 7)

[0150] Next, the retainer 901 shown Figure 16 will be described. Figure 16 is a plan view of the retainer 901 and the strain sensor 903 of this modification example.

[0151] The retainer 901 is in a flat plate shape and has a substantially rhombic shape when viewed from above, and includes a holding portion 910 and an outer peripheral member 920. The holding portion 910 is an annular member having a cylindrical inner peripheral surface 910a around the axis X. The outer peripheral member 920 is a member disposed on one side in the radial direction (the direction of arrow c) with respect to the holding portion 910.

[0152] In the radial direction, on one side of the holding portion 910 (the direction of arrow c), two small annular fixing portions 923 are arranged at positions symmetric twice around the axis X and are slightly separated from the holding portion 910. Near four tangents that are externally tangent to the holding portion 910 and the two fixing portions 923, four beam-shaped deformed portions 922 connect the holding portion 910 and the two fixing portions 923. The two fixing portions 923 and the deformed portions 922 form the outer peripheral member 920 of the present embodiment. A gap 940 is formed between the holding portion 910 and the fixing portion 923. In the radial direction, the deformed portion 922 faces the holding portion 910 with the gap 940 therebetween.

[0153] A strain sensor 903 is mounted on a surface of each of the deformed portions 922 that is opposite to the surface facing the holding portion 910 and that extends in the axial direction (a deformable surface). The deformed portions 922 and the strain sensor 903 each extend along a plane parallel to the axial direction. The strain sensor 903 is mounted so as to be able to detect the strain of the deformed portion 922 in a direction perpendicular to the axial plane. Therefore, in the case where the strain sensor 903 is a strain gauge, it is mounted on the deformed portion 922 such that the direction of the gate (gauge) (typically the long side direction of the strain gauge) is along the long side direction of the deformed portion 922. In the case where the strain sensor 903 is a strain gauge, the strain of the deformed portion 922 is detected as a change in the resistance value. In addition, the strain sensor 903 is not limited to a strain gauge, and may be various other sensors such as a piezoelectric element.

[0154] The fixing portion 923 is a portion connected to an external device (not shown). In the radial direction, the fixing portion 923 is disposed on one side (the direction of arrow c) of the deformed portion 922. A circular through hole (hole portion) 923h is formed near the central portion of the fixing portion 923. The retainer 901 can be fixed to the external device via the through hole 923h and by means of a bolt or the like.

[0155] In the radial direction, a bearing (not shown) is disposed on the other side (the direction of arrow d) of the holding portion 910 of the retainer 901. The end portion of the retainer 901 on the other side (the direction of arrow b) in the axial direction has an annular contact portion 911 that protrudes toward the other side (the direction of arrow d) in the radial direction. In this modification example, the contact portion 911 protrudes from the holding portion 910 of the retainer 901 toward the other side (the direction of arrow d) in the radial direction. In the axial direction, the contact portion 911 contacts the end surface on the other side (the direction of arrow b) of the bearing. Thereby, the contact portion 911 can support the bearing in the axial direction. Since the retainer 901 of this modification example can be designed to be lightweight, the weight reduction of the device can be achieved.

[0156] As described above, as the structures of the retainer and the torque sensor in which a plurality of strain sensors are mounted in the sensor device of the present invention, various modification examples have been described, but the structures of the retainer and the torque sensor are not limited to the above-described embodiments and modification examples.

[0157] For example, in Figure 17 an example is shown in which the sensor device is applied to a device having a crank 30 and a shaft S used in a moving body 1000 such as a bicycle. The moving body 1000 includes a shaft S, a crank 30 fixed to the shaft S via a fixing member N, a cover 20 covering a part of the shaft, and the sensor device connected to the cover 20. In addition, in Figure 17 for convenience, a torque sensor 300 is illustrated, but the form of the sensor device is not limited to using the torque sensor 300. In addition, inFigure 17 In this case, the arithmetic circuit and the sensor for detecting the position information of the shaft S are omitted. Inside the cover 20, the end portion of the shaft S on the side opposite to the side where the torque sensor 300 is disposed is supported by another bearing 302. An external force can be applied to the crank 30, and the crank 30 receiving the external force transmits the rotational force accompanied by the external force to the shaft S, and the shaft S receiving the rotational force rotates. The bearing of the sensor device rotatably supports the rotating shaft S.

[0158] On the other hand, Figure 18 An example of applying the sensor device to a rotating device 2000 having one or more gears G1, G2, G3 and a motor M is shown. In addition, in Figure 18 for convenience, the torque sensor 300 is illustrated, but the form of the sensor device is not limited to using the torque sensor 300. Further, in Figure 18 the arithmetic circuit and the sensor for detecting the position information of the shaft are omitted. The rotating device 2000 includes one or more gears G1, G2, G3 and a motor M having a shaft MS connected to one gear G1. By driving the motor M, the shaft MS rotates, the gear G1 fixed to the shaft MS rotates, the other gear G2 meshing with the gear G1 rotates, and the shaft S fixed to the other gear G2 rotates. The bearing of the sensor device rotatably supports the shaft S fixed to the other gear G2. The sensor device is supported by the housing H of the rotating device 2000. The end portion of the shaft S on the side opposite to the side where the torque sensor 300 is disposed is supported by another bearing 402.

[0159] As described above, in Figure 17 the moving body 1000, an external force acts on the crank 30 to rotate the shaft S, but the sensor device is applicable to the shaft. In Figure 18 the rotating device 2000, the other gear G2 meshing with the gear G1 to which the driving force of the motor M is applied rotates, but the sensor device is applicable to the shaft S supporting the other gear G2. In Figure 18 the rotating device 2000, regarding the circumferential component F t (propulsive force) and the radial component F r (loss force) of the force (the force for rotating the shaft S) acting on the other gear G2 from the gear G1, the magnitudes of each can be calculated by the sensor device of the present invention. As described above, the sensor device can be applied to a device using the lever principle.

[0160] In addition to this, those skilled in the art can appropriately change the sensor device of the present invention according to the known existing opinions and change the combination of various structures. As long as the structure of the present invention is still included by the said change, it is of course also included in the scope of the present invention.

[0161] Explanation of the Attached Drawing Reference Numerals

[0162] 1: Sensor device

[0163] 10: Operational circuit

[0164] 100: Sensor

[0165] 201, 301, 401, 501, 601, 701, 801, 901: Retainer

[0166] 202, 602: Bearing (first bearing)

[0167] 203, 603, 803, 903: Strain sensor

[0168] 210, 310, 410, 510, 610, 710, 810, 910: Holding part

[0169] 222, 422: Deformable surface

[0170] 230, 330, 430, 530: Connecting part

[0171] 240, 340, 440, 540, 640, 840, 940: Gap

[0172] S: Shaft

Claims

1. A sensor device, comprising: Bearing; Shaft, having a portion supported by the bearing; Holder, having a holding portion for holding the bearing and a deformable surface extending in the axial direction of the bearing; A plurality of strain sensors for detecting information on the force acting on the shaft; Sensor for detecting information on the position of the shaft in the circumferential direction of the bearing; And Arithmetic circuit, The plurality of strain sensors are mounted on the deformable surface, Signals output from the plurality of strain sensors and the sensor are input to the arithmetic circuit, The arithmetic circuit calculates: the magnitude of the radial component and the magnitude of the circumferential component of the bearing in the information on the force for rotating the shaft at a specified position in the circumferential direction of the bearing.

2. The sensor device according to claim 1, wherein, The information on the position of the shaft is the rotation angle of the shaft.

3. The sensor device according to claim 1 or 2, wherein, The information on the force acting on the shaft is the amount of deformation of the deformable surface.

4. The sensor device according to any one of claims 1 to 3, wherein, In the circumferential direction of the bearing, when the rotation angle of the shaft with respect to a specified angle is set to θ a , the angle of the direction of the force that rotates the shaft with respect to the specified angle is set to θ b , and when the magnitude of the force that rotates the shaft is set to f, the arithmetic circuit calculates, respectively, f r = |f × cos(θ a - θ b )| and f t = |f × sin(θ a - θ b )| to calculate the magnitudes f r of the components in the radial direction of the bearing and f t of the components in the circumferential direction of the bearing in the information of the force that rotates the shaft.

5. The sensor device according to any one of claims 1 to 4, wherein, The directions of the strains respectively detected by the plurality of strain sensors are different from each other.

6. The sensor device according to claim 1, wherein, The holding portion is located on the bearing side with respect to the deformable surface.

7. The sensor device according to claim 6, wherein, The holder includes a connecting portion that connects the holding portion and the deformable surface.

8. The sensor device according to claim 7, wherein, In the radial direction of the bearing, the holder includes a gap between the deformable surface and the holding portion, The connecting portion includes a concave portion that is recessed in the axial direction of the bearing.

Images