JP2012127884A - Torque sensor and drive device equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor with high stiffness which minimize the decrease of torsion stiffness, and improves detection sensitivity or accuracy.SOLUTION: A torque sensor comprises a strain generating portion 2 having a generally cylindrical shape, inputted driving force at one end in an axial direction and a load at the other end in the axial direction, and transmitting torque with torsion between a driving side and a load side; a groove portion 5 provided on an inner peripheral surface 2a of the strain generating portion 2, and extending from one end side in the axial direction toward the other end side; and a strain detecting portion 4 attached to the groove portion 5, and detecting strain amount corresponding to stress generated in the groove portion 5 by torque input to the strain generating portion 2; and calculates the magnitude of torque acting on the strain generating portion 2 on the basis of the detection result of the strain detecting portion 4. A groove bottom bm and a groove side wall bs for configuring the groove portion 5 on a cross section orthogonal to the axial direction are configured by a curved surface 50, and the groove is formed in a shape which makes stress generating on the groove bottom bm maximum out of stress generating in the groove portion 5 by the torque input on the cross section. The strain detecting portion 4 is attached to an area including the groove bottom bm.

Description

  The present invention relates to a torque sensor with improved detection sensitivity and detection accuracy, and a drive device including the torque sensor.

  2. Description of the Related Art Conventionally, a torque sensor that detects torque acting on a shaft of a driving device such as a motor that is rotationally driven by electromagnetic action is known. For example, Patent Document 1 discloses a cylindrical shape that transmits torque while connecting a connecting portion such as a flange connected to a shaft of a driving device and a load device, and connecting the connecting portions to each other between the driving side and the load side. Such as a strain gauge that detects the amount of strain corresponding to the stress generated in the groove bottom by torque input, which is affixed to the groove bottom of the groove part. There is disclosed a torque sensor that includes a strain detection unit and calculates the magnitude of torque that acts on the strain generating unit based on the detection result of the strain detection unit.

German Patent Application Publication No. 1937293

  In the torque sensor disclosed in Patent Document 1, as illustrated in FIG. 3B, the groove 1005 formed in the strain-generating portion 1002 has a curved surface 1050 and a flat surface 1051 in a cross section orthogonal to the axial direction. The curved corner 1050 and the flat surface 1051 have a groove shape in which the corners of the curved surface 1050 and the flat surface 1051 are corners eg, and the strain detection unit 1004 is attached to a portion where the corners eg are avoided in the cross section. In this case, it is considered that the stress generated in the groove part 1005 due to the torque input to the strain generating part 1002 is concentrated on the corner part eg.

  However, although the detection sensitivity improves as the stress generated at the part where the strain detection unit is attached increases, the strain detection unit cannot be attached to the corner where stress is concentrated. This is not preferable.

  As one means for increasing the detection sensitivity of the strain detection unit, it is conceivable to increase the area occupied by the groove portion in the cross section to make the strain generation unit easier to twist. Torsional rigidity is reduced.

  Further, in the groove shape, since the strain detection unit is attached to a portion that avoids the corner where stress is concentrated, even if the installation position of the strain detection unit is slightly shifted, the detection value varies and the detection accuracy is reduced. There is a case. In particular, when detecting a combination of a plurality of distortion detectors or when amplifying a detection signal, variations in detection values become remarkable and detection accuracy is reduced.

  The present invention has been made paying attention to such a problem, and the object thereof is to provide a high-rigidity torque sensor with improved detection sensitivity and accuracy by minimizing torsional rigidity reduction, and the same. It is to provide a driving device.

  In order to achieve this object, the present invention takes the following measures.

  That is, the torque sensor of the present invention has a substantially cylindrical shape, a driving force is input to one axial end, a load is input to the other axial end, and torque is transmitted while twisting between the driving side and the load side. Corresponding to the strain generating portion, the groove portion provided on the inner peripheral surface of the strain generating portion and extending from one end side in the axial direction toward the other end side, and the stress generated in the groove portion by torque input to the strain generating portion attached to the groove portion A torque sensor for detecting the amount of strain, and a torque sensor for calculating the magnitude of torque acting on the strain generating part based on the detection result of the strain detecting part, wherein the groove part in a cross section orthogonal to the axial direction The groove bottom and the groove side wall constituting the groove are curved surfaces, and the groove shape is such that the stress generated at the groove bottom is maximized among the stresses generated at the groove portion by torque input in the cross section, and the strain is detected in the region including the groove bottom. That the part was attached And butterflies.

  The groove bottom means the deepest part of the groove.

  In this way, the groove bottom and the groove side wall are configured with curved surfaces in the cross section orthogonal to the axial direction, and the groove shape is such that the stress generated in the groove bottom becomes the maximum among the stress generated in the groove portion by torque input in the cross section, Since the strain detection unit is attached to the region including the groove bottom, the strain detection sensitivity of the strain detection unit is higher than when the stress is concentrated on the corner of the groove other than the region where the strain detection unit is attached. It is possible to improve the sensitivity and increase the sensitivity. In addition, since the strain detection unit is attached to the region including the groove bottom where the maximum stress is generated among the stresses generated in the groove, even if the mounting position of the strain detection unit is slightly shifted, the detection value variation is suppressed and detection accuracy is improved. It becomes possible to improve. Furthermore, since the detection sensitivity is improved by the groove shape described above, it is possible to avoid using as much as possible the widening of the area occupied by the groove portion in the cross section, and a torque sensor with high rigidity and high sensitivity can be achieved by suppressing the reduction of torsional rigidity. Can be realized.

  In order to facilitate the mounting of the strain detecting portion, the groove shape of the groove portion is formed so that the portion of the groove portion having the maximum stress caused by torque input is substantially in the center in the circumferential direction of the groove portion in the cross section. It is preferable.

  In order to improve the detection accuracy by suppressing variation in the detection value due to the displacement of the strain detector mounting position, the groove portion is arranged along the axial direction in the cross section where the maximum stress generated in the groove portion by torque input is located. The strain detector has a long sensitive area extending along a predetermined direction intersecting the axial direction, and detects a strain amount in a certain direction. And a second sensing part that has a long sensing area extending along the predetermined direction and detects a strain amount in a direction different from the first sensing part. It is effective.

  In order to improve detection sensitivity while minimizing the torsional rigidity of the strain generating portion, the circumferential width dimension of the groove portion allows the mounting of a single strain detecting portion and two or more. It is preferable that the dimensions are set so as not to allow the strain detectors to be attached in a state of being parallel in the circumferential direction.

  The torque sensor of the present invention is preferably applied to a drive device that rotates.

  As described above, according to the present invention, the groove bottom and the side wall of the groove are configured with curved surfaces in the cross section orthogonal to the axial direction, and the stress generated at the groove bottom among the stresses generated at the groove portion by torque input in the cross section is maximized. Since the strain detection part is attached to the area including the groove bottom, the strain detection part is compared with the case where the stress is concentrated in the corner part of the groove part other than the area where the strain detection part is attached. It is possible to improve the sensitivity of detecting the amount of distortion due to the high sensitivity. In addition, since the strain detection unit is attached to the region including the groove bottom where the maximum stress is generated among the stresses generated in the groove, even if the mounting position of the strain detection unit is slightly shifted, the detection value variation is suppressed and detection accuracy is improved. It becomes possible to improve. Furthermore, since the detection sensitivity is improved by the groove shape described above, it is possible to avoid using as much as possible the widening of the area occupied by the groove portion in the cross section, and a torque sensor with high rigidity and high sensitivity can be achieved by suppressing the reduction of torsional rigidity. It can be realized. Therefore, it is possible to provide a highly rigid torque sensor with improved detection sensitivity and accuracy.

The figure which shows typically the structure of the torque sensor which concerns on one Embodiment of this invention. AA site | part sectional drawing of FIG. The BB site | part end view of FIG. 2 which compares this invention and shows a conventional example about the groove shape of a groove part. The figure which shows the attachment attitude | position of the distortion | strain detection part with respect to a groove part. The figure which shows the attachment attitude | position of the distortion | strain detection part with respect to a groove part in other embodiment of this invention. The figure which shows the groove shape of the groove part which concerns on embodiment other than the above of this invention. The figure which shows typically drive apparatuses, such as a motor, to which the torque sensor of this invention is applied.

  Hereinafter, a torque sensor according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the torque sensor Ts has a substantially cylindrical shape, and both ends in the axial direction are connected to the drive side (drive device) and the load side (load device), respectively, and twisted between the drive side and the load side. The strain generating portion 2 that transmits torque while being accompanied, the connecting portion 3 such as a flange for connecting the shaft of the driving device and the load device provided at both axial ends of the strain generating portion 2, and the strain generating portion 2 And a strain detection unit 4 using a strain gauge that detects a strain amount corresponding to the stress generated in the strain generation unit 2 by torque input, and torque acting on the strain generation unit 2 based on the detection result of the strain detection unit 4 It is an apparatus which calculates the magnitude | size of. That is, one end in the axial direction of the strain generating portion 2 is associated with a driving force output shaft (shaft) of a driving device such as a motor that is rotationally driven, and a driving force is input by the driving device, and the other end in the axial direction of the strain generating portion 2 The load is input by the load device in association with the shaft of the load device. The torque sensor Ts of the present embodiment is used to configure a driving device including a torque sensor by connecting one axial end of the strain generating portion 2 and a driving force output shaft (shaft). Of course, you may comprise the drive device in which the torque sensor is integrated integrally by integrally forming the axial direction end and driving force output shaft (shaft) of the strain generating part as the same member. In this case, it is possible to reduce the axial dimension of the entire device including the torque sensor and the drive device.

  As schematically shown in FIG. 7 using a conceptual diagram, the driving device M uses a known motor or the like. The driving device M is fixed to the casing M1 and generates a magnetic field. And a rotor M3 that is supported by the casing M1 in a rotatable state and rotates by receiving a magnetic field. The magnetic field is changed by energization control of the stator M2, and a repulsive force is generated between the stator M2 and the rotor M3. The rotor M3 is rotated by applying a suction force or the like to obtain a rotational driving force from the electric energy. The strain generating portion 2 is associated with the driving force output shaft M3a (shaft) of the rotor M3. The driving device M shown in FIG. 7 is merely a conceptual diagram, and is not limited to the illustrated driving device. A drive device other than a motor may be used.

  Returning to the description of the torque sensor Ts, the strain generating portion 2 and the connecting portion 3 are both substantially cylindrical as shown in FIGS. 1 and 2, and the connecting portions 3. In the state where 3 is connected, the shaft is constituted by using both as an integral member. In other words, it can be said that both end portions in the axial direction of the shaft are set to the connecting portions 3 and 3 and a portion between the connecting portions 3 and 3 is set to the strain generating portion 2. The inner diameters of the strain generating portion 2 and the connecting portion 3 are the same, but the outer diameter of the connecting portion 3 is made larger than the outer diameter of the strain generating portion 2 to form the connecting portion 3 in a flange shape. A twist due to torque input is likely to occur in the strain generating portion 2. A closing part 3a for closing the inner hollow space SP1 is formed in one of the connecting parts 3 and 3, and an opening 3b for releasing the inner hollow space SP1 in the axial direction is formed in the other connecting part 3. At the same time, the sealing plate 30 is configured to be detachable through a sealing member 31 such as an O-ring and a fastening tool vo such as a screw at a position that closes the opening 3b. As described above, since each part such as the strain detecting unit 4 is easily sealed in the hollow space SP1, each part can be protected from oil, dust, and the like. The connecting portion 3 is provided with a screw hole 32 for mounting the sealing plate 30 and a sealing member 31 such as an O-ring, and a connection hole 33 for connecting a shaft of a driving device or a load device. Is formed.

  As shown in FIGS. 1 and 2, the strain generating portion 2 is thinned to form an inner peripheral surface 2a along an arc centered on the axis Cn. The inner peripheral surface 2a is formed with a groove portion 5 that reduces the thickness between the outer peripheral surface 2b and the inner peripheral surface 2a, that is, the radial thickness, extending from one axial end toward the other end. A plurality of the groove portions 5 are provided at equal intervals along the circumferential direction. As shown in FIG. 1, each groove 5 is paired with another groove 5 that is disposed at a position that is symmetrical with respect to the axis Cn. Further, as shown in FIG. 2, the groove portion 5 is provided in a state where it is thinned along the axial direction from one end in the axial direction of one connection portion 3 to the other connection portion 3 via the strain generating portion 2. It is formed over the entire axial direction of the strain generating portion 2. In addition, in this embodiment, although the groove part 5 is extended along the axial direction, if it extends toward the other end side from the axial direction one end side, it will not be limited to this. For example, the groove portion may be inclined with respect to the axial direction of the strain generating portion.

  As shown in FIG. 3A, the groove portion 5 has a partial cylindrical shape along an arc having a radius r1 centered at one point P1 on the inner peripheral surface 2a of the strain-generating portion 2 in a cross section orthogonal to the axial direction. As a result, the stress generated by the torque input is concentrated on the groove bottom bm, which is the deepest part of the groove in the cross section, and the stress generated on the groove bottom bm is the maximum of the stress generated on the groove portion 5 as a result. It has become. The groove bottom bm is the deepest part of the groove. The thickness in the radial direction of the groove portion 5 is such that the groove bottom bm at the center in the circumferential direction of the groove portion 5 is the thinnest, and the thickness gradually increases as the groove bottom bm is displaced along the circumferential direction from the groove bottom bm at the center in the circumferential direction. The groove shape of the groove part 5 is formed. That is, the groove bottom bm and the groove side wall bs constituting the groove 5 are formed by the curved surface 50, and the groove shape is set such that the stress generated in the groove bottom bm is the maximum among the stress generated in the groove 5 due to torque input in the cross section. Has been. The curved surface 50 constituting the groove bottom bm and the groove side wall bs is set to a curvature having a size that allows the strain detector 4 such as a strain gauge to be attached (attached), and has a continuous curved surface with no corners. The curvature is set so as not to cause stress concentration at a portion other than the bottom bm. In the groove shape of the groove portion 5, a portion (groove bottom bm) where the stress caused by torque input is maximized is positioned substantially at the center in the circumferential direction of the groove portion 5 in the cross section. Further, since the groove 5 has the same cross section along the axial direction, the maximum stress generated in the groove 5 due to torque input in the cross section is shown in FIG. A site | part (groove bottom bm) will be arrange | positioned along an axial direction. In other words, in the present embodiment, the groove portion 5 has a groove shape in which a portion where stress is concentrated becomes one portion of the groove bottom bm in the cross section.

  As shown in FIG. 4, the strain detection unit 4 is a sheet-like component that detects a minute change (strain) in the mechanical dimension generated in the strain generation unit 2 as a result of torque acting on the strain generation unit 2. A strain gauge is used, and is attached to an area including the groove bottom bm in the groove 5 via an adhesive. By providing the strain detecting unit 4 on the inner peripheral surface 2a (groove 5) of the strain generating unit 2 in this way, it is effective that the strain detecting unit 4 is damaged or separated from the strain generating unit 2 by centrifugal force during high-speed rotation. To prevent.

  As shown in FIG. 4, the strain detection unit 4 of the present embodiment has a long shape extending along a predetermined direction orthogonal (or crossing) to the axial direction of the strain generation unit 2 when attached to the groove 5. A first sensitive part 4a for detecting a strain amount in a certain direction (a direction indicated by an arrow Y1 in FIG. 4 and a direction inclined by 45 degrees with respect to the axial direction); Distortion in the direction different from the first sensitive part 4a (specifically, the direction perpendicular to the arrow Y1 and the direction indicated by the arrow Y2) having the elongated sensitive area 41 extending along the direction. And a second sensing part 4b for detecting the amount, and a lead wire Li extends in a predetermined direction. In other words, the strain detection unit 4 includes a plurality of sensory parts 4a and 4b each having a long sensory region 40 and 41 extending along a predetermined direction, and the predetermined direction is orthogonal (or intersects) with the axial direction. It is affixed on the groove portion 5 in such a posture. Metal sensitive elements such as metal foils are arranged in the sensitive areas 40 and 41, and the strain generated on the pasting surface of the strain detecting unit 4 is transmitted to the sensitive areas 40 and 41 so that the metal resistive elements expand and contract. In this case, the amount of distortion is detected by utilizing the change in resistance value. In the present embodiment, a plurality of (for example, eight) strain gauges are formed by attaching a strain detection unit to each pair of groove portions 5 that are symmetrical with respect to the axis Cn to form a pair or a plurality of pairs. Are connected by configuring a bridge circuit by a known 4-gauge method. Note that the sensitive areas 40 and 41 shown in FIG. 4 are merely image diagrams of the gauge pattern of the strain gauge, which means that the strain detection unit applicable to the present invention is limited to the gauge pattern shown in FIG. is not.

  As shown in FIG. 3A, the torsional rigidity of the strain-generating portion 2 decreases as the circumferential width dimension w1 of the groove portion 5 increases. Therefore, the circumferential width dimension w1 of the groove portion 5 is a single strain detection. The dimension of the torsional rigidity is reduced to the minimum necessary by setting the dimensions so as to permit the attachment of the part 4 and not allow the two or more strain detection parts 4 to be attached in parallel in the circumferential direction.

  As shown in FIG. 2, in the hollow space SP1 inside the strain generating portion 2 and the connecting portion 3, a voltage is applied to the strain detecting portion 4 that is a strain gauge, and the strain signal detected by the strain detecting portion 4 is transmitted to the hollow space SP1. A transmission unit 60 such as a telemeter for transmission to the outside of SP1 is provided. Further, outside the strain generating unit 2, a distortion signal transmitted from the transmission unit 60 is received, and a calculation unit 61 that calculates the magnitude of torque by calculation processing, and power is supplied to the transmission unit 60 in a contactless manner. A power supply unit 62 is provided. That is, power is supplied from the power supply unit 62 to the transmission unit 60 via an antenna coil (not shown), and a voltage is applied to the distortion detection unit 4. When a torque acts on the strain generating portion 2, the strain generating portion 2 is twisted, and this twist is detected as a strain amount by the strain detecting portion 4 attached to the region including the groove bottom bm. Since the strain detection unit 4 is affixed to a region including the groove bottom bm where the stress is maximized among the stresses generated in the groove 5 by torque input, the strain amount is detected efficiently and with high sensitivity. A distortion signal corresponding to the amount of distortion detected by the distortion detector 4 is transmitted from the transmitter 60 to the calculator 61, and the calculator 61 calculates the magnitude of torque based on the distortion signal (detection result of the distortion detector). The

  As described above, the torque sensor according to the present embodiment has a substantially cylindrical shape, and a driving force is input to one end in the axial direction and a load is input to the other end in the axial direction, causing torsion between the driving side and the load side. The strain generating portion 2 that transmits torque, the groove portion 5 that is provided on the inner peripheral surface 2a of the strain generating portion 2 and extends from one end side in the axial direction toward the other end side, and the torque applied to the strain generating portion 2 that is attached to the groove portion 5 A torque sensor that includes a strain detector 4 that detects a strain amount corresponding to the stress generated in the groove 5 by input, and that calculates the magnitude of the torque acting on the strain generating unit 2 based on the detection result of the strain detector 4. In addition, the groove bottom bm and the groove side wall bs constituting the groove portion 5 in the cross section orthogonal to the axial direction are formed by the curved surface 50, and the stress generated in the groove bottom bm among the stresses generated in the groove portion 5 by torque input in the cross section. Groove shape to maximize the groove Attach the strain detecting section 4 in a region including the m.

  The groove bottom bm means the deepest part of the groove part 5.

  As described above, the groove bottom bm and the groove side wall bs are configured by the curved surface 50 in the cross section orthogonal to the axial direction, and the stress generated in the groove bottom bm is maximized in the stress generated in the groove portion 5 by torque input in the cross section. Since the strain detection unit 4 is attached to the region including the groove bottom bm, the strain detection is performed as compared with the case where the stress is concentrated on the corner portion of the groove portion other than the region to which the strain detection unit is attached. It is possible to improve the detection sensitivity of the distortion amount by the unit 4 and to increase the sensitivity. In addition, since the strain detection unit 4 is attached to a region including the groove bottom bm where the maximum stress among the stresses generated in the groove 5 is generated, even when the mounting position of the strain detection unit 4 is slightly shifted, variation in the detection value is suppressed. Thus, the detection accuracy can be improved. Furthermore, since the detection sensitivity is improved by the groove shape, it is possible to avoid using as much as possible the widening of the area occupied by the groove portion 5 in the cross section, and the torque sensor having high rigidity and high sensitivity by suppressing the reduction of torsional rigidity. Can be realized.

  In particular, in the present embodiment, the groove shape of the groove portion 5 is formed so that the portion (groove bottom bm) in the groove portion 5 where the stress generated by torque input is maximum is approximately the center in the circumferential direction of the groove portion 5 in the cross section. Therefore, it is possible to facilitate the attachment of the strain detecting unit 4 as compared with the case where the groove bottom bm is deviated from the substantially center in the circumferential direction of the groove 5 in the transverse section.

  Further, in the present embodiment, the groove portion 5 has a groove shape in which a portion (groove bottom bm) having the maximum stress generated in the groove portion 5 due to torque input in the cross section is arranged along the axial direction, thereby detecting strain. The unit 4 has a long sensitive region 40 extending along a predetermined direction that intersects the axial direction, a first sensitive unit 4a that detects a strain amount in a certain direction (Y1), and a predetermined direction. And a second sensing part 4b for detecting a strain amount in a direction (Y2) different from that of the first sensing part 4a. Even when the attachment position of the strain detection unit 4 is displaced in the axial direction or the circumferential direction, for example, the state where the plurality of sensitive areas 40 and 41 simultaneously straddle the groove bottom bm that is the stress concentration portion is maintained, and the detected value due to the attachment position displacement It is possible to improve the detection accuracy by suppressing the variation of the above.

  In addition, although the torsional rigidity of the strain generating portion 2 is impaired as the circumferential width dimension w1 of the groove portion 5 is increased, in the present embodiment, the circumferential width dimension w1 of the groove portion 5 is a single strain detection. Since the dimension is set so as to permit the attachment of the portion 4 and not allow the two or more strain detection portions 4 to be attached in the circumferential direction, it is necessary to reduce the torsional rigidity of the strain-generating portion 2 to the minimum necessary. The detection sensitivity is effectively secured.

  As mentioned above, although embodiment of this invention was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present invention is shown not only by the above description of the embodiments but also by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the present embodiment, as shown in FIG. 4, the strain detection unit includes a plurality of sensory parts 4 a and 4 b each having a long sensory area 40 and 41 extending in a predetermined direction and parallel to each other. 4 is affixed to the groove 5 in a posture in which the predetermined direction is orthogonal to the axial direction. However, as shown in FIG. 5, the strain detector 4 is affixed to the groove 5 in a posture in which the predetermined direction and the axial direction are substantially coincident. May be. If it does in this way, it will become possible to reduce the width dimension of the circumferential direction of the groove part 5 required for attachment of the distortion | strain detection part 4. FIG. In this case, the first sensor 4a detects the amount of distortion in the direction indicated by the arrow Y1 in the figure, and the second sensor 4b detects the amount of distortion in the direction indicated by the arrow Y2 in the figure. . In the present embodiment, the strain amount in two directions corresponding to the torsion of the strain generating portion 2 is detected using the strain detecting portion 4 in which the two sensitive portions 4a and 4b are paired. A plurality of strain detection units in which the first and second sensing units 4a and 4b are separately configured may be used as a set.

  Moreover, in this embodiment, as shown to Fig.3 (a), the groove shape of the groove part 5 formed in the strain generation part 2 is comprised by the partial cylindrical-shaped curved surface 50 along the circular arc in the cross section. However, as shown to Fig.6 (a), the groove shape of the groove part 105 formed in the strain generation part 102 may be comprised by the curved surface 150 along the partial parabola in the cross section. Further, as shown in FIG. 6B, the groove shape of the groove portion 205 formed in the strain-generating portion 202 may be constituted by a curved surface 250 along a partial ellipse in the cross section. The thickness in the radial direction of these groove portions 105 and 205 is such that the groove bottom bm at the center in the circumferential direction is the thinnest, and the wall thickness gradually increases with displacement from the center groove bottom bm along the circumferential direction. A groove shape is formed.

  Other grooves include those shown in FIG. That is, the groove shape of the groove portion 305 formed in the strain generating portion 302 may be configured by a curved surface 350 in which a plurality of curved surfaces along arcs centering on different points in the cross section are continuously connected. The groove bottom bm of the groove 305 is displaced in the circumferential direction from the circumferential center of the groove 305. Alternatively, the groove shape may be formed by a curved surface along an oval shape in the cross section.

  Moreover, the number of the groove parts provided in the inner peripheral surface of the strain generating part may be larger than the number of the groove parts to which the strain detecting part is attached. The groove width in the circumferential direction of the groove portion can be changed as appropriate. When a plurality of groove portions are formed, the shape and size of each groove portion may be different. In addition, a plurality of strain detectors may be attached to the single groove portion along the axial direction. Further, the groove portion formed in the strain generating portion does not need to be formed over the entire region in the axial direction of the strain generating portion 2 as long as the groove portion is provided at a position overlapping at least the radial position with the position where the strain detecting portion is attached. Of course, the groove portion may or may not penetrate through the members such as the strain generating portion 2 and the connecting portion 3. The torsional rigidity of the strain generating portion 2 can be adjusted within the scope of the above invention according to the size of the inner and outer diameters of the strain generating portion 2, the width dimension in the circumferential direction of the groove portion, and the number thereof. The stress generated in the groove 5, that is, the detection sensitivity can be adjusted within the scope of the invention by the shape of the groove and the distance between the bottom of the groove and the outer peripheral surface of the strain generating part.

  In addition, although a strain gauge is described as an example of the strain detection unit, a strain gauge other than the strain gauge may be used as long as the strain generated in the strain generation unit can be detected. For example, a piezoelectric element may be used, or a material that emits light according to the stress may be applied to the inner peripheral surface of the strain generating portion and detected by a light receiving sensor.

  Furthermore, the connection part 3 is not limited to a flange as long as it can be connected to the shaft of the drive device or the load device. For example, a spline shape or a shape connected by a key may be used. In the present embodiment, the connecting portion 3 and the strain generating portion 2 are formed as an integral member, but separate members may be coupled by a connecting method such as a screw or press fitting.

  In addition, the transmission of the detected distortion signal to the calculation unit 61 and the power supply from the power supply unit 62 to the distortion detection unit 4 may be performed not only wirelessly but also by wire using a slip ring, for example.

  The specific configuration of each part is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

Ts ... torque sensor 2 ... strain generating portion 2a ... inner peripheral surface 4 ... strain detecting portions 40, 41 ... sensitive region 4a ... first sensitive portion 4b ... second sensitive portion 5 ... groove 50 ... curved surface bm ... Groove bottom bs ... groove side wall w1 ... width dimension

Claims (5)

A strain generating portion that is substantially cylindrical and has a driving force input to one axial end and a load input to the other axial end to transmit torque while twisting between the driving side and the load side, and the strain generating portion A groove portion that is provided on the inner peripheral surface of the groove portion and extends from one end side in the axial direction toward the other end side, and a strain detection portion that is attached to the groove portion and detects a strain amount corresponding to a stress generated in the groove portion by torque input to the strain generating portion. A torque sensor for calculating the magnitude of torque acting on the strain generating portion based on the detection result of the strain detecting portion,
The groove bottom and the groove side wall constituting the groove part are configured with curved surfaces in a cross section perpendicular to the axial direction, and the groove shape is such that the stress generated at the groove bottom is maximized among the stresses generated in the groove part by torque input in the cross section. A torque sensor, wherein the strain detector is attached to a region including a groove bottom.   2. The torque sensor according to claim 1, wherein a groove shape of the groove portion is formed such that a portion of the groove portion having the maximum stress generated by torque input is substantially in the center in the circumferential direction of the groove portion in a cross section. The groove portion has a groove shape in which a portion where the stress generated in the groove portion by the torque input in the cross section is maximum is arranged along the axial direction,
The strain detection unit includes a first sensor unit that has a long sensory region extending along a predetermined direction intersecting the axial direction, and detects a strain amount in a certain direction. The torque according to claim 1, further comprising: a second sensing part that has a long sensing area extending along the first sensing part and detects a strain amount in a direction different from that of the first sensing part. Sensor.   The circumferential width dimension of the groove part is set to a dimension that allows attachment of a single strain detection part and does not allow attachment of two or more strain detection parts in parallel with each other in the circumferential direction. The torque sensor in any one of 1-3.   The drive device provided with the torque sensor in any one of Claims 1-4.

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