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 joint 20 includes a groove 21A with V-shaped cross-section for receiving a prism-shaped lower end part 81 of a drive shaft 80, and a groove 22A with V-shaped cross-section for receiving a prism-shaped upper end part 91 of a valve shaft 90. A cramp member 30 includes a groove 31 with V-shaped cross-section for receiving the lower end part 81. Fastening with the joint 20 cramps the lower end part 81 between an inner face of the groove 21A and an inner face of the groove 31 from four directions. 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 joint 20 cramps the upper end part 91 between an inner face of the groove 22A and an inner face of the groove 41 from four directions. Further, a strain gauge 70 is fixed to the joint 20 and detects a strain at the joint 20 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] The connecting device of the present invention comprises: a joint having a first groove with a V-shaped cross section that receives a first end portion of a first shaft, the first end portion being a rectangular prism; and a second groove with a V-shaped cross section that receives a second end portion of a second shaft that is coaxial with the first shaft; a first clamping member having a third groove with a V-shaped cross section that receives the first end portion and that is fastened and fixed to the joint to clamp the first end portion from four directions between the inner surfaces of the first groove and the third groove; a second clamping member having a fourth groove with a V-shaped cross section that receives the second end portion and that is fastened and fixed to the joint to clamp the second end portion from four directions between the inner surfaces of the second groove and the fourth groove; and a strain gauge that is fixed to the joint and detects torsion that occurs in the joint 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 a perspective view of a main part of the connecting device of FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A coupling device according to an embodiment of the present invention will now be described with reference to the drawings.

[0010] 1 to 3, 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 drive shaft 80 and the valve shaft 90 are clamped 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 lower end 81 of the drive shaft 80 and the upper end 91 of the valve shaft 90 are formed in a rectangular shape with a square cross section, in particular in the shape of a square pillar boss protruding from the cylindrical shaft body 82 or 92. Note that "square" includes squares with chamfered or curved corners.

[0013] The connecting device 10 includes a joint 20, a clamp member 30, a clamp member 40, two reinforcing plates 50, a strain gauge support plate 60, a strain gauge 70, and four bolts B. 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. The joint 20, the clamp member 30, the clamp member 40, the reinforcing plate 50, and the bolts B are made of, for example, a metal material. The strain gauge support plate 60 is made of, for example, a metal material. The strain gauge 70 is made of, for example, any element with an insulating base. The strain gauge 70 may be made of any element.

[0014] The joint 20 includes a block 21 , a block 22 , and a spacer 23 .

[0015] Block 21 is formed in a semi-cylindrical shape that bulges backward. On its front side, block 21 has a groove 21A, and fixing surfaces 21B and 21C.

[0016] The groove 21A is formed in a V shape in a cross-section with a cutout in the front-rear, left-right directions to receive the lower end portion 81 of the drive shaft 80, and extends in the direction of the rotation axis C. The opening angle θ of the groove 21A 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 of the lower end portion 81 (the angle formed by the adjacent side surfaces. Here, it is 90 degrees). For example, the opening angle θ is an angle obtained by subtracting an angle D within the range of 0° < D ≤ 2° from the angle formed by the two sides of the cross-section of the lower end portion 81. The apex portion of the V shape of the groove 21A forms a cylindrical space S. Note that the setting of the opening angle θ and the space S are also adopted for other grooves with a V-shaped cross-section. The space S reaches the groove 22A of the block 22 described later.

[0017] The fixing surfaces 21B and 21C are arranged on both the left and right sides of the groove 21A, and the clamp member 30 is fixed thereto. Threaded holes 21D and 21E that are screwed with bolts B for fixing the clamp member 30 are respectively opened on the fixing surfaces 21B and 21C. The threaded holes 21D and 21E are through holes that penetrate the block 21, but may be formed as bottomed holes.

[0018] Block 21 further has a support protrusion 21G that protrudes backward and supports the strain gauge support plate 60 at the center of the rear surface, that is, between the threaded holes 21D and in the left-right direction. Also, block 21 has two cuts 21H that are cut from its rear surface toward the front. The two cuts 21H are respectively provided between the support protrusion 21G and the threaded hole 21D, and between the support protrusion 21G and the threaded hole 21E.

[0019] Block 21 further has two plate-like connection pieces 21I that extend in the up-down, left-right directions and protrude left and right. A reinforcing plate 50 is fixed to each of the two connection pieces 21I (details will be described later).

[0020] Block 22 has the same configuration as block 21. That is, block 22 includes groove 22A, fixing surface 22B, fixing surface 22C, screw-engagement hole 22D, screw-engagement hole 22E, support protrusion 22G, two notches 21H, and two connection pieces 221. Clamp member 40 is fixed to fixing surfaces 22B and 22C instead of clamp member 30.

[0021] Spacer 23 is formed in a disk shape with a through-hole in the center. Spacer 23 is configured to create a gap between blocks 21 and 22 and allow slight relative rotation between blocks 21 and 22 (relative rotation between drive shaft 80 and valve shaft 90, described below). The through-hole in the center of spacer 23 communicates with a square column-shaped space formed by groove 21A and groove 31, described below, into which a lower end 81 of drive shaft 80 fits, and a square column-shaped space formed by groove 22A and groove 41, described below, into which an upper end 91 of valve shaft 90 fits.

[0022] The block 21, the block 22, and the spacer 23 may be integrally formed from a metal or the like, or may be formed as separate bodies and connected by welding or the like.

[0023] The clamp member 30 is formed in a shape that is elongated in the left-right direction, and is fastened and fixed to the block 21 of the joint 20 by a bolt B. The clamp member 30 has a groove 31 with a V-shaped cross section that, together with the groove 21A of the block 21, receives the lower end 81 of the drive shaft 80. The groove 31 has a configuration that is substantially the same as the groove 21A, except that the groove 31 is recessed in the opposite direction to the groove 21A. The clamp member 30 has through holes 32 and 33 into which the bolt B is inserted. The bolt B inserted into the through hole 32 threads into the threaded hole 21D of the block 21 of the joint 20. The bolt B inserted into the through hole 33 threads into the threaded hole 21E of the block 21 of the joint 20. As a result, the clamp member 30 is fastened and fixed to the block 21 by the bolt B.

[0024] The lower end 81 of the drive shaft 80 is inserted into the groove 21A of the block 21 of the joint 20, and the clamp member 30 is fastened and fixed to the block 21 with two bolts B. As a result, the two surfaces forming the groove 21A and the two surfaces forming the groove 31, a total of four surfaces, press against the four side surfaces of the lower end 81 of the drive shaft 80 through surface contact, and the lower end 81 is firmly clamped from four directions.

[0025] In this embodiment, the opening angle θ of the V-shaped groove 21A is smaller than 90 degrees. Therefore, when the inner surface of the groove 21A clamps the lower end 81 of the drive shaft 80, the groove 21A is opened by the lower end 81 of the drive shaft 80, which has a square cross section, as shown by arrow R1 in FIG. 4 . Due to the elastic restoring force generated by this opening, the inner surface of the groove 21A can press against the two side surfaces of the lower end 81 of the drive shaft 80 while in surface contact with the two side surfaces. The groove 21A is easily opened by the space S. The deformation of the block 21 due to the opening of the groove 21A is absorbed by the elastic deformation that narrows the width of the notch 21H (see arrow R2). This allows the block 21 to deform so that the inner surface of the groove 21A comes into full contact with the two side surfaces of the lower end 81 of the drive shaft 80.

[0026] 1 to 3, when the inner surface of groove 31 of clamp member 30 clamps lower end 81 of drive shaft 80, the opening angle of groove 31 also increases, providing the same effect as groove 21A. Clamp member 30 is thinner in the front-to-rear direction than block 21, and is therefore relatively prone to elastic deformation. For this reason, in this embodiment, no notch similar to notch 21H is provided in clamp member 30, but such a notch may be provided as appropriate.

[0027] The clamp member 40 has a structure similar to that of the clamp member 30. That is, the clamp member 40 has a groove 41 with a V-shaped cross section that, together with the groove 22A of the block 22, receives the upper end 91 of the valve stem 90. The clamp member 40 has through holes 42 and 43 into which bolts B are inserted, which thread into the threaded holes 22D and 22E of the block 22 of the joint 20. As with the lower end 81 of the drive shaft 80, the upper end 91 of the valve stem 90 is inserted into the groove 22A of the block 22 of the joint 20. When the clamp member 40 is fastened and fixed to the block 22 with two bolts B, a total of four surfaces, namely, two surfaces forming the groove 22A and two surfaces forming the groove 41, press against the four side surfaces of the upper end 91 of the valve stem 90 in surface contact, respectively, and the upper end 91 is firmly clamped from four directions. Other explanations regarding the clamp (for example, advantages of an opening angle of less than 90 degrees) also follow the explanation regarding the clamping of the lower end 81 of the drive shaft 80 by the block 21 and the clamp member 30.

[0028] Each of the two reinforcing plates 50 is fixed to adjacent connecting pieces 21I and 22I in the vertical direction of the joint 20, and extends in the vertical and horizontal directions. As a result, even if a force is applied to either the drive shaft 80 or the valve shaft 90 while they are clamped to the coupling device 10, tending to tilt them in the horizontal direction (the direction in which the reinforcing plates extend), the reinforcing plates 50 suppress deformation such as bending of the joint 20 in the horizontal direction.

[0029] The strain gauge support plate 60 is supported by the support protrusions 21G of the block 21 of the joint 20 and the support protrusions 22G of the block 22. In other words, the strain gauge support plate 60 is disposed across the block 21, which clamps the drive shaft 80 and thereby rotates integrally with the drive shaft 80, and the block 22, which clamps the valve shaft 90 and thereby rotates integrally with the valve shaft 90. A strain gauge 70 is mounted on the strain gauge support plate 60. For example, when torque is applied to the valve shaft 90, the drive shaft 80 and the valve shaft 90 rotate relative to each other, which causes the blocks 21 and 22 to rotate relative to each other and twist the joint 20. This twisting deforms the strain gauge support plate 60, which is disposed across the blocks 21 and 22. The strain gauge 70 detects this deformation (strain). Information on the detected deformation is sent to an external processing circuit (not shown) via wiring (not shown) and is used for torque calculations, etc.

[0030] As described above, in the coupling device 10 according to this embodiment, the joint 20 includes a groove 21A with a V-shaped cross section that receives the lower end 81 of the drive shaft 80, and a groove 22A with a V-shaped cross section that receives the upper end 91 of the valve shaft 90, both of which are rectangular prisms. The clamp member 30 includes a groove 31 with a V-shaped cross section that receives the lower end 81, and when fastened to the joint 20, the inner surfaces of grooves 21A and 31 clamp the lower end 81 from four directions. The clamp member 40 includes a groove 41 with a V-shaped cross section that receives the upper end 91 of the valve shaft 90, and when fastened to the joint 20, the inner surfaces of grooves 22A and 41 clamp the upper end 91 from four directions. The strain gauge 70 is fixed to the joint 20 (here, it is fixed via the strain gauge support plate 60, but it may also be fixed directly) and detects torsion that occurs in the joint 20 due to relative rotation between the drive shaft 80 and the valve shaft 90. With this configuration, the drive shaft 80 and the valve shaft 90 are securely clamped from all four sides, which eliminates wobble and stabilizes the clamp, reducing transmission loss of the relative rotation between the two shafts to the joint compared to when, for example, conventional set screws are used. This prevents hysteresis from occurring in the detected values ​​of strain gauges, for example. Here, relative rotation refers to one rotating relative to the other, and includes cases where one is stationary and the other is rotating, and cases where both rotate in opposite directions. Relative rotation also includes cases where both rotate in the same direction but at different rotational speeds.

[0031] As described above, the opening angle of the V-shaped cross section of grooves 21A, 31, 22A, and 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 lower end 81 of drive shaft 80 or the upper end 91 of valve shaft 90 to be clamped. Note that this angle setting may be applied to at least one of grooves 21A, 31, 22A, and 41. Setting the angle allows the two surfaces constituting the groove to press the two side surfaces of the shaft end with greater force, respectively, resulting in more stable clamping. Furthermore, even if valve shaft 90 is subjected to a torque load, for example, the contact points between the two surfaces constituting the groove and the shaft end are separated from the center of torque, reducing the shaft load for the same torque load and stabilizing clamping.

[0032] Furthermore, blocks 21 and 22 may include notches 21H and 22H, respectively, that narrow as blocks 21 and 22 deform due to the increase in the opening angle. This narrowing reduces deformation of the external shapes of blocks 21 and 22 due to the increase in the opening angle. Blocks 21 and 22 can also deform so that the inner surfaces of grooves 21A and 22A come into full contact with two side surfaces of end 81 or 91 of drive shaft 80 or valve shaft 90.

[0033] In this embodiment, the plate-shaped strain gauge 70 and the reinforcing plate 50 both extend in the up-down and left-right directions and are parallel to each other. Here, the strain gauge 70 detects not only its own twisting caused by the twisting of the joint 20 but also deformation of the drive shaft 80 and the valve stem 90 in a left-right shift as strain. In this embodiment, the reinforcing plate 50 suppresses deformation of the joint 20 in the direction in which the reinforcing plate 50 extends (deformation in the left-right direction) and therefore prevents erroneous detection by the strain gauge 70 of detecting this deformation, i.e., a deformation different from the twisting of the joint 20 that the strain gauge 70 is intended to detect.

[0034] The strain gauge 70 is insensitive to deformation in the direction along its thickness (it does not detect strain or the detected value is small). In this embodiment, this insensitivity is utilized to allow deformation of the joint 20 in this direction (for example, deformation in the front-to-rear direction due to the application of a force to tilt one of the drive shaft 80 and the valve shaft 90 in the front-to-rear direction (a direction other than the direction in which the reinforcing plate extends)). This prevents excessive rigidity from being added to the joint 20, ensuring the sensitivity of the torque detection.

[0035] 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 of 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 described 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. The spacer 23 may be semicircular or the like, and may separate the rectangular prism-shaped space formed by grooves 21A and 31 from the rectangular prism-shaped space formed by grooves 22A and 41 without communicating with each other.

[0036] The configurations disclosed in this specification are described below. (Appendix 1) a joint including a first groove having a V-shaped cross section that receives a first end of a first shaft having a rectangular prism shape, and a second groove having a V-shaped cross section that receives a second end of a second shaft having a rectangular prism shape coaxial with the first shaft; a first clamping member including a third groove having a V-shaped cross section that receives the first end portion, and fastened to the joint to clamp the first end portion from four directions between inner surfaces of the first groove and the third groove; a second clamping member including a fourth groove having a V-shaped cross section that receives the second end portion, and fastened to the joint to clamp the second end portion from four directions between inner surfaces of the second groove and the fourth groove; a strain gauge fixed to the joint for detecting a torsion occurring in the joint due to relative rotation between the first shaft and the second shaft; A coupling device comprising: (Appendix 2) an opening angle of at least one of the first groove and the third groove is less than an angle formed by two sides of a cross section of the first end portion, and is widened by the clamped first end portion; 10. The coupling device of claim 1. (Appendix 3) the joint comprises a first block having the first groove and a second block having the second groove; the at least one groove includes the first groove, the first block includes a notch that becomes narrower due to deformation of the first block caused by an increase in the opening angle of the first groove; 10. A coupling device as described in Appendix 2. (Appendix 4) the joint comprises a first block having the first groove, a second block having the second groove, and a spacer that provides a gap between the first block and the second block; The strain gauge is plate-shaped, The device further includes a plate-shaped reinforcing plate that connects the first block and the second block and is parallel to the strain gauge. 4. A coupling device according to any one of appendices 1 to 3. (Appendix 5) 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 4. [Explanation of symbols]

[0037] 10...Coupling device, 20...Joint, 21...Block, 21A...Groove, 21B, 21C...Fixing surface, 21D, 21E...Threaded hole, 21G...Support protrusion, 21I...Connecting piece, 22...Block, 22A...Groove, 22B, 22C...Fixing surface, 22D, 22E...Threaded hole, 22G...Support protrusion, 22I...Connecting piece, 23...Spacer, 30...Clamping member, 31...Groove, 32, 33...Through hole, 40...Clamping member, 41...Groove, 42, 43...Through hole, 50...Reinforcing plate, 60...Strain gauge support plate, 70...Strain gauge, 80...Drive shaft, 81...Lower end, 82...Shaft body, 90...Valve shaft, 91...Upper end, 92...Shaft body, B...Bolt, C...Rotating shaft, R1, R2...Arrow, S...Space, θ...Opening angle

Claims

1. a joint including a first groove having a V-shaped cross section that receives a first end of a first shaft having a rectangular prism shape, and a second groove having a V-shaped cross section that receives a second end of a second shaft having a rectangular prism shape coaxial with the first shaft; a first clamping member including a third groove having a V-shaped cross section that receives the first end portion, the first clamping member being fastened and fixed to the joint so as to clamp the first end portion from four directions between inner surfaces of the first groove and the third groove; a second clamping member including a fourth groove having a V-shaped cross section that receives the second end portion, the second clamping member being fastened and fixed to the joint so as to clamp the second end portion from four directions between inner surfaces of the second groove and the fourth groove; a strain gauge fixed to the joint for detecting a torsion occurring in the joint due to relative rotation between the first shaft and the second shaft; A coupling device comprising:

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

3. the joint comprises a first block having the first groove and a second block having the second groove; the at least one groove includes the first groove, the first block includes a notch that becomes narrower due to deformation of the first block caused by an increase in the opening angle of the first groove; The coupling device of claim 2 .

4. the joint includes a first block having the first groove, a second block having the second groove, and a spacer that provides a gap between the first block and the second block, The strain gauge is plate-shaped, a plate-shaped reinforcing plate that connects the first block and the second block and is parallel to the strain gauge; The coupling device of claim 1 .

5. 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 4.

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