Connection device

Abstract

To reduce a transmission loss of a relative rotation of two shafts to a joint.SOLUTION: In a connection device 10, a planar member 20 is fixed to a lower end part of a drive shaft 80 in an unrotatable manner. A lower end part of the drive shaft 80 is fixed to a center of the planar member 20. Further, a joint 30 includes a planar part 31 and a block 32, the planar part 31 is fixed to the planar member 20 and the fixing position is on an outer peripheral edge of the planar part 31. Further, the block 32 is fixed to a center of the planar part 31, and includes a groove 32A with V-shaped cross-section for receiving the upper end part 91 of a valve shaft 90. A cramp member 40 includes a groove 41 with V-shaped cross-section for receiving the upper end part 91 of the valve shaft 90. Fastening with the block 32 cramps the upper end part 91 between an inner face of the groove 32A and an inner face of the groove 41 from four directions. A strain gauge 70 is fixed to the planar part 31 and detects a strain at the planar part 31 by a relative rotation between the drive shaft 80 and the valve shaft 90.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a coupling device for coupling two shafts. [Background technology]

[0002] Patent Document 1 discloses a coupling device that includes a joint (coupling) that connects two shafts, such as a rotating shaft of an actuator and a valve shaft to which a valve body or the like is connected, and a strain gauge provided in the joint to detect the relative rotation of the two shafts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-96285 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 does not disclose the details of the connection manner of the connecting device, and depending on the connection manner, for example, rattle may occur between the shaft and the joint, causing a loss in the transmission of relative rotation between the two shafts to the joint, which may result in hysteresis in the detection value of the strain gauge, for example.

[0005] An object of the present invention is to reduce the transmission loss of the relative rotation between two shafts to a joint. [Means for solving the problem]

[0006] a plate-shaped member fixed to a first end of a first shaft in an orientation perpendicular to the rotation axis of the first shaft so as not to rotate relative to the first end, the plate-shaped member having a fixing point at the center of the plate-shaped member; a plate-shaped portion fixed to the plate-shaped member in an orientation perpendicular to the rotation axis, the fixing point being one of an outer peripheral edge portion and a central portion of the plate-shaped portion; and a block fixed to the other of the outer peripheral edge portion and the central portion of the plate-shaped portion, the block having a first groove with a V-shaped cross section that receives a rectangular prism-shaped second end of a second shaft coaxial with the first shaft; a clamp member having a second groove with a V-shaped cross section that receives the second end, the clamp member being fastened to the block so as to clamp the second end from four directions between the inner surfaces of the first groove and the second groove; and one or more strain gauges fixed to the plate-shaped member at a position between the outer peripheral edge portion and the central portion and detecting strain generated in the plate-shaped portion due to relative rotation between the first shaft and the second shaft. [Effects of the Invention]

[0007] According to the present invention, the transmission loss of the relative rotation between the two shafts to the joint is reduced. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a coupling device according to an embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the coupling device of FIG. [Figure 3] FIG. 3 is an exploded perspective view of the coupling device of FIG. [Figure 4] 4 is an exploded perspective view of the coupling device of FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] A coupling device according to an embodiment of the present invention will be described below with reference to the drawings. In the drawings, reference numerals may be used to denote only some of the elements.

[0010] 1 to 4, a coupling device 10 according to one embodiment of the present invention is configured to coaxially couple a drive shaft 80, which is rotationally driven by an actuator (not shown), to a valve shaft 90, which is connected to a valve body (not shown). The coupling device 10 transmits the rotation of the drive shaft 80 to the valve shaft 90, causing the drive shaft 80 and the valve shaft 90 to rotate integrally.

[0011] In this specification, the direction of the central axes of the drive shaft 80 and the valve shaft 90, i.e., the direction of the rotation axis C, is defined as the up-down direction, with the drive shaft 80 side defined as the top and the valve shaft 90 side defined as the bottom. In other words, the valve shaft 90 is located below the drive shaft 80. In this specification, the direction in which the valve shaft 90 is clamped, as will be described later, is also referred to as the front-to-back direction. This front-to-back direction is perpendicular to the up-to-down direction. Furthermore, the direction perpendicular to the up-to-down direction and the front-to-back direction, and the left and right when viewed from the front to the back, is defined as the left-to-right direction. These directions are set for convenience and do not limit the arrangement direction of the coupling device 10. For example, the up-to-down direction may differ from the actual top-to-bottom direction.

[0012] The drive shaft 80 has a cylindrical shape. The upper end 91 of the valve shaft 90 is formed in a rectangular shape with a square cross section, in particular, in the shape of a square pillar boss protruding from a cylindrical shaft body 92. Note that the term "square" includes squares with chamfered or curved corners.

[0013] The connecting device 10 includes a plate-like member 20, a joint 30, a clamp member 40, a strain gauge 70, a plurality of (six in this case) bolts B1, and a plurality of (two in this case) bolts B2. Note that in the drawings, threads formed on the bolts and threads formed on the inner walls of the screw holes (described below) are not shown. Each element of the connecting device 10 other than the strain gauge 70 is formed, for example, from a metal material. The strain gauge 70 may be composed of any element.

[0014] The plate-shaped member 20 is formed in a disk shape. The lower end of the drive shaft 80 is joined (fixed) to the center of the plate-shaped member 20 by an appropriate joining method such as welding. Therefore, the plate-shaped member 20 is non-rotatable relative to the drive shaft 80. The plate-shaped member 20 is fixed to the drive shaft 80 in a direction perpendicular to the drive shaft 80 (particularly the rotation axis C). In other words, the in-plane direction of the plate-shaped member 20 is perpendicular to the axial direction of the drive shaft 80, i.e., the direction of the rotation axis C. The plate-shaped member 20 has a plurality of (six in this example) screw holes 21 that penetrate the plate-shaped member 20 in the vertical direction and are screwed with six bolts B1, respectively. The screw holes 21 are arranged at intervals along the outer periphery of the plate-shaped member 20. A disk-shaped recess 22 for accommodating the strain gauge 70 is opened on the underside of the plate-shaped member 20. The plate-shaped member 20 is non-rotatably fixed to the joint 30 by the bolt B1.

[0015] The joint 30 includes a plate-shaped portion 31, a block 32, and a connecting portion 33. The plate-shaped portion 31, the block 32, and the connecting portion 33 may be formed integrally, or may be formed from separate members and joined as a single member by welding or the like.

[0016] The plate-like portion 31 is formed in a disk shape. A recess 31A opens on the upper surface of the plate-like portion 31, and within the recess 31A, there are formed an island 31B (which is annular in FIG. 2, but does not have to be annular) provided in a central region thereof, and a plurality (six in this case) of rod-shaped beams 31D extending radially from the island 31B to reach an annular portion 31C on the outer periphery of the plate-like portion 31. A plurality (six in this case) of through-holes 31E into which bolts B1 are inserted are formed at each connection portion between the annular portion 31C and the plurality of beams 31D.

[0017] A plurality of bolts B1 respectively inserted into the plurality of through holes 31E from below are respectively screwed into the plurality of screw holes 21 of the plate-like member 20, so that the plate-like portion 31 of the joint 30 is in a state of being fitted to the plate-like member 20 (in a direction orthogonal to the drive shaft 80 (particularly the rotation shaft C), that is, in a direction parallel to the plate-like member 20) and is fastened and fixed to the plate-like member 20 by the bolts B1. Since the plurality of through holes 31E and the plurality of screw holes 21 used for this fixing are arranged at the outer peripheral edge portions of the plate-like member 20 and the plate-like portion 31, the fixing positions of the said fastening and fixing are arranged at the outer peripheral edge portions of the plate-like member 20 and the plate-like portion 31.

[0018] Strain gauges 70 are fixed to the upper surfaces of two of the plurality of beams 31D. The strain gauges 70 are insulated and protected with respect to the beams 31D (joint 30). For example, the strain gauges 70 have pedestal portions made of insulating materials on the side fixed to the beams 31D. The strain gauges 70 are arranged in the recess 22 of the plate-like member 20, and a gap is provided between the strain gauges 70 and the plate-like member 20.

[0019] The block 32 is formed in a semi-cylindrical shape bulging rearward. The block 32 includes a groove 32A, a fixing surface 32B, and a fixing surface 32C on its front side.

[0020] The groove 32A is formed in a V shape in a cross section with a cutout in the front-rear, left-right directions to receive the upper end portion 91 of the valve shaft 90, and extends in the direction of the rotation shaft C. The opening angle θ of the groove 32A before receiving the lower end portion 81 is set to an angle smaller than the angle formed by the two sides of the cross section with a cutout in the front-rear, left-right directions of the upper end portion 91 (the angle formed by adjacent side surfaces. Here, it is 90 degrees). For example, the opening angle θ is an angle obtained by subtracting an angle D within 0° < D ≦ 2° from the angle formed by the two sides of the cross section of the lower end portion 81. The setting of the opening angle θ is also adopted for the groove 41 described later.

[0021] Fixing surfaces 32B and 32C are disposed on both the left and right sides of groove 32A, and clamp member 40 is fixed thereto. Threaded holes 32D and 32E are formed in fixing surfaces 32B and 32C, respectively, and threadedly engage with bolts B2 that secure clamp member 40. Threaded holes 32D and 32E are through-holes that pass through block 32, but may also be formed as blind holes.

[0022] The connecting portion 33 is formed in a disk shape and is connected to the center of the underside of the plate-shaped portion 31. The block 32 is connected to the connecting portion 33. The connecting portion 33 fixes the block 32 to the center of the plate-shaped portion 31. The plate-shaped portion 31, the block 32, and the connecting portion 33 are connected so as to be unable to rotate relative to one another, i.e., so as to rotate integrally.

[0023] The clamp member 40 is formed in a shape that is elongated in the left-right direction. The clamp member 40 has a groove 41 with a V-shaped cross section that, together with the groove 32A of the block 32 of the joint 30, receives the upper end 91 of the valve shaft 90. The groove 41 is recessed in the opposite direction to the groove 32A. The apex of the V of the groove 32A forms a cylindrical space S. The rest of the description of the groove 41 is the same as the description of the groove 32A. The clamp member 40 has through holes 42 and 43 into which a bolt B2 is inserted. The bolt B2 inserted into the through hole 42 threads into the threaded hole 32D of the block 32. The bolt B2 inserted into the through hole 43 threads into the threaded hole 32E of the block 32. As a result, the clamp member 40 is fastened to the block 32 by the bolt B2.

[0024] The upper end 91 of the valve shaft 90 is inserted into the groove 32A of the block 32 of the joint 30 (as shown in FIG. 4), and the clamp member 40 is fastened to the block 32 with two bolts B2. As a result, the two surfaces forming the groove 32A and the two surfaces forming the groove 41, a total of four surfaces, press against the four side surfaces of the upper end 91 of the valve shaft 90 through surface contact, and the upper end 91 is firmly clamped from four directions.

[0025] In this embodiment, the opening angle θ of the V-shaped cross-section grooves 32A and 41 is smaller than 90 degrees. Therefore, when the inner surfaces of the grooves 32A and 41 clamp the upper end 91 of the valve stem 90, the grooves 32A and 41 are opened by the square cross-section upper end 91. The elastic restoring force caused by this opening allows the inner surfaces of the grooves 32A and 41 to press against the four side surfaces of the upper end 91 while in surface contact with the four side surfaces. The groove 41 is made easier to open by the space S at its top. Depending on the shape of the block 32, the space S may also be provided in the groove 32A.

[0026] In this embodiment, the plate-shaped member 20 connected to the drive shaft 80 is fixed to the outer periphery of the plate-shaped portion 31 of the joint 30 with bolts B1. Meanwhile, the block 32 that clamps the valve stem 90 is fixed to the center of the plate-shaped portion 31 via a connecting portion 33. Therefore, rotation of the drive shaft 80 is transmitted to the outer periphery of the plate-shaped portion 31, and rotation of the valve stem 90 is transmitted to the center of the plate-shaped portion 31. Due to the difference in the points of rotation transmission, the relative rotation between the drive shaft 80 and the valve stem 90 distorts the plate-shaped portion 31. The strain gauge 70 detects this distortion. Information on the detected deformation is sent to an external processing circuit (not shown) via wiring (not shown) and is used, for example, to calculate the torque applied to the valve stem 90. The strain gauge 70 is formed in a plate shape and is attached to the beam 31D, for example, with an adhesive.

[0027] As described above, in the coupling device 10 according to this embodiment, the plate-shaped member 20 is fixed to the lower end of the drive shaft 80 in a direction perpendicular to the rotation axis C of the drive shaft 80 (the front-rear and left-right directions are in-plane directions) so as not to rotate relative to the drive shaft 80. Here, the lower end of the drive shaft 80 is fixed to the center of the plate-shaped member 20. Furthermore, the joint 30 includes a plate-shaped portion 31 and a block 32. The plate-shaped portion 31 is fixed to the plate-shaped member 20 in a direction perpendicular to the rotation axis C, and the fixing point is the outer periphery of the plate-shaped portion 31. Furthermore, the block 32 is fixed to the center of the plate-shaped portion 31, and has a groove 32A with a V-shaped cross section that receives the upper end 91 of the rectangular prism-shaped valve shaft 90 that is coaxial with the drive shaft 80. Alternatively, the fixing location of the plate-shaped member 20 and the plate-shaped portion 31 may be the central portion of the outer peripheral edge portion and the central portion, and the fixing location of the plate-shaped portion 31 and the block 32 may be the outer peripheral edge portion of the outer peripheral edge portion and the central portion. Furthermore, the clamp member 40 has a groove 41 with a V-shaped cross section that receives an upper end portion 91 of the valve stem 90, and when fastened to the block 32, the inner surfaces of the grooves 32A and 41 clamp the upper end portion 91 from four directions (front-rear, back-rear, left-right directions that are in-plane directions perpendicular to the axial direction of the rotation axis C). The strain gauge 70 is fixed to the plate-shaped portion 31 at a position between the outer peripheral edge portion and the central portion of the plate-shaped portion 31, and is configured to detect strain generated in the plate-shaped portion 31 due to the relative rotation of the drive shaft 80 and the valve stem 90. With this configuration, the drive shaft 80 is fixed non-rotatably to the plate-like portion 31 (joint 30) via the plate-like member 20, and the valve shaft 90 is securely clamped from all four sides by the block 32 and clamp member 40. This prevents rattle and other issues compared to, for example, when a conventional set screw is used, stabilizes the clamp, and reduces transmission loss of the relative rotation between the two shafts to the joint. This prevents hysteresis from occurring in the detection value of the strain gauge 70, for example. Here, relative rotation refers to the rotation of one shaft relative to the other, and includes cases where one shaft is stationary and the other is rotating, and cases where both shafts rotate in opposite directions. Relative rotation also includes cases where both shafts rotate in the same direction but at different rotational speeds. While the number of strain gauges 70 is two in the above example, it may be one or more.

[0028] The one or more strain gauges 70 may be disposed at any position. As described above, the one or more strain gauges 70 may be disposed on one or more beams 31D among the beams 31D that extend radially from the island 31B located at the center of the plate-shaped portion 31 and are connected to the annular portion 31C at the outer periphery of the plate-shaped portion 31. The island 31B, the annular portion 31C, and the beams 31D form the framework of the plate-shaped portion 31. The beams 31D are susceptible to distortion due to distortion of the plate-shaped portion 31 caused by the relative rotation of the drive shaft 80 and the valve stem 90. By fixing the strain gauges 70 to the beams 31D, distortion of the plate-shaped portion 31 can be detected with high sensitivity. Furthermore, for deformations such as bending in the front-rear and left-right directions, two strain gauges 70 are disposed as a pair at positions 180° symmetrical with respect to the rotation angle (opposite positions about the rotation axis C), and the outputs of both strain gauges 70 are processed to prevent erroneous strain detection. Although there is a possibility that beam 31D may deform in the vertical direction, strain gauge 70 is insensitive to deformation in the vertical direction, which is its thickness direction (it does not detect strain or the detected value is small), so deformation of beam 31D in the vertical direction does not pose any particular problem from the standpoint of erroneous detection of strain.

[0029] As described above, the opening angle of the V-shaped cross section of groove 32A and groove 41 before clamping should preferably be less than the angle formed by two sides of the cross section (cut along a plane perpendicular to rotation axis C) of the upper end 91 of the valve stem 90 to be clamped. Note that this angle setting may be applied to at least one of groove 32A and groove 41. Setting the angle allows the two surfaces constituting the groove to press the two side surfaces of the upper end 91 with greater force, respectively, resulting in more stable clamping. Furthermore, even if the valve stem 90 is subjected to a torque load, for example, the contact points between the two surfaces constituting the V-shaped cross section of the groove and the upper end 91 are separated from the center of torque, reducing the axial load for the same torque load and stabilizing clamping.

[0030] Although the present invention has been described above with reference to the embodiments and modifications, the present invention is not limited to the above embodiments and modifications. For example, the present invention includes various modifications to the above embodiments and modifications that are understandable to those skilled in the art within the scope of the technical concept of the present invention. The configurations listed in the above embodiments and modifications can be combined as appropriate within a consistent range. For example, the two axes to be connected by the connecting device 10 may be any axes.

[0031] The configurations disclosed in this specification are described below. (Appendix 1) a plate-like member fixed to a first end of a first shaft in a direction perpendicular to a rotation axis of the first shaft so as not to rotate relative to the first end, the fixed location of the first end being the center of the plate-like member; a joint including: a plate-like portion fixed to the plate-like member in a direction perpendicular to the rotation axis, the fixed portion being one of an outer periphery and a center of the plate-like portion; and a block fixed to the other of the outer periphery and the center of the plate-like portion, the block having a first groove with a V-shaped cross section that receives a second end portion of a rectangular prism shape of a second shaft coaxial with the first shaft; a clamp member including a second groove having a V-shaped cross section that receives the second end portion, the clamp member being fastened and fixed to the block to clamp the second end portion from four directions between inner surfaces of the first groove and the second groove; one or more strain gauges fixed to the plate-shaped portion at a position between the outer peripheral edge portion and the central portion, and detecting a strain occurring in the plate-shaped portion due to relative rotation between the first axis and the second axis; A coupling device comprising: (Appendix 2) the plate-like portion includes a framework including an island located in the central portion, an annular portion disposed on the outer peripheral edge portion, and a plurality of beams extending radially from the island to reach the annular portion, The one or more strain gauges are fixed to one or more beams among the plurality of beams, respectively. 10. The coupling device of claim 1. (Appendix 3) an opening angle of at least one of the first groove and the second groove is less than an angle formed by two sides of a cross section of the second end portion, and is widened by the clamped second end portion; 3. A coupling device according to claim 1 or 2. (Appendix 4) the first shaft is a drive shaft that is rotationally driven by an actuator, The second shaft is a valve shaft connected to the valve body. A coupling device according to any one of appendices 1 to 3. [Explanation of symbols]

[0032] 10...Coupling device, 20...Plate-shaped member, 21...Threaded hole, 22...Recess, 30...Joint, 31...Plate-shaped portion, 31A...Recess, 31B...Island, 31C...Annular portion, 31D...Beam, 31E...Through hole, 32...Block, 32A...Groove, 32B, 32C...Fixing surface, 32D, 32E...Through hole, 33...Connection portion, 40...Clamp member, 41...Groove, 42, 43...Through hole, 70...Strain gauge, 80...Drive shaft, 81...Lower end, 90...Valve shaft, 91...Upper end, 92...Shaft body, B1, B2...Bolt, C...Rotating shaft, S...Space, θ...Opening angle

Claims

1. a plate-like member fixed to a first end of a first shaft in a direction perpendicular to a rotation axis of the first shaft so as not to rotate relative to the first end, the first end being fixed at a center of the plate-like member; a joint including: a plate-like portion fixed to the plate-like member in a direction perpendicular to the rotation axis, the fixed location being one of an outer periphery and a center of the plate-like portion; and a block fixed to the other of the outer periphery and the center of the plate-like portion, the block having a first groove with a V-shaped cross section that receives a second end of a rectangular prism-shaped second shaft coaxial with the first shaft; a clamp member including a second groove having a V-shaped cross section that receives the second end portion, the clamp member being fastened and fixed to the block to clamp the second end portion from four directions between inner surfaces of the first groove and the second groove; one or more strain gauges fixed to the plate-like portion at a position between the outer peripheral edge portion and the central portion, and detecting a strain occurring in the plate-like portion due to relative rotation between the first axis and the second axis; A coupling device comprising:

2. the plate-like portion includes a framework including an island located in the central portion, an annular portion disposed on the outer peripheral edge portion, and a plurality of beams extending radially from the island to reach the annular portion, the one or more strain gauges are fixed to one or more beams among the plurality of beams, respectively; The coupling device of claim 1 .

3. an opening angle of at least one of the first groove and the second groove is less than an angle formed by two sides of a cross section of the second end portion, and is widened by the clamped first end portion; The coupling device of claim 1 .

4. the first shaft is a drive shaft that is rotationally driven by an actuator, The second shaft is a valve shaft connected to a valve body. A coupling device according to any one of claims 1 to 3.

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