Torque Meters and Measurement Systems

Abstract

To reduce measurement errors of a torque meter.SOLUTION: A torque meter 1 comprises a first disc part 12, a second disc part 13, a strain part 11 of hollow cylindrical shape that connects the first disc part 12 and the second disc part 13, and a strain gauge 15 which is fixed to the inner circumferential face of the strain part 11. A bolt penetrating through an open hole 132 of the second disc part 13 is put through a bolt hole 121 of the first disc part 12 that is provided at a position which is in phase with the open hole 132 and screwed into a screw hole 311 for connection of a first flange 31 of a first revolving shaft 3 (c1) and the bolt inserted into a bolt hole for connection of a second flange 41 of a second revolving shaft 4 is screwed into a screw hole 131 of the second disc part 13 that is provided at a position which is out of phase with the bolt hole 121 (c2). The strain gauge 15 is located at a position that is in intermediate phase between the bolt hole 121 of the first disc part 12, the phase of which is closest to the strain gauge 15, and the screw hole 131 of the second disc part 13, the phase of which is closest to the strain gauge 15.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a technique for measuring torque transmitted by a rotating shaft. [Background technology]

[0002] A torque meter 9 shown in FIG. 9a is known as a technique for measuring the torque transmitted by a rotating shaft (for example, see Patent Document 1). FIG. 9a is a side view of the torque meter 9 with a part cut away, and the hatched area represents the cross section after cutting away. As shown in the figure, this torque meter 9 has a drive side flange 92 provided at one axial end of a hollow cylindrical body 91, and a load side flange 93 provided at the other end. The central portion in the axial direction of the hollow body 91 is formed thin, and a strain gauge 94 is fixed to the thin portion of the inner peripheral surface of the hollow body 91.

[0003] As shown in FIG. 9b, a flange 101 of a drive side rotating shaft 100 is fastened to a drive side flange portion 92 of the torque meter 9 with bolts, and a flange 111 of a load side rotating shaft 110 is fastened to a load side flange portion 93 with bolts.

[0004] In such a torque meter 9, the torque transmitted between the drive side rotating shaft 100 and the load side rotating shaft 110 is measured by the strain gauge 94 as strain in the thin-walled portion of the inner circumferential surface of the hollow body portion 91. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-321335 A Summary of the Invention [Problem to be solved by the invention]

[0006] When the torque meter 9 shown in Figures 9a and 9b is actually used, there are times when both the fastening operations between the flange 101 and the drive side flange portion 92 and the fastening operations between the flange 111 and the load side flange portion 93 must be performed from one of the rotating shaft sides.

[0007] For example, if the torque meter 9 shown in Figures 9a and 9b is placed near a device that applies a load to the load side rotating shaft 110, there will be no space on the rotating shaft 110 side required for the fastening work, so both the fastening between the flange 111 and the load side flange portion 93 and the fastening between the flange 101 and the drive side flange portion 92 must be performed from the drive side rotating shaft 100 side.

[0008] As shown in Figure 9c1, flange 111 and load side flange portion 93 are connected from the drive side rotating shaft 100 side with a bolt passed through hole 921 provided in drive side flange portion 92, and then, as shown in Figure 9c2, drive side flange portion 92 and flange 101 are connected with a bolt. In this way, both the fastening between flange 111 and load side flange portion 93 and the fastening between flange 101 and drive side flange portion 92 can be performed only from the drive side rotating shaft 100 side.

[0009] With such a structure, it is no longer possible to position the bolts connecting flange 101 and drive side flange portion 92 and the bolts connecting flange 111 and load side flange portion 93 in overlapping positions when viewed in the axial direction, and the connection form between flange 101 and drive side flange portion 92 and the connection form between flange 111 and load side flange portion 93 become asymmetric.

[0010] This asymmetry was a factor that caused measurement errors in the torque meter. An object of the present invention is to perform highly accurate torque measurement with reduced error in a torque meter that is disposed between two rotating shafts and allows connection work with each rotating shaft to be performed from one of the rotating shafts. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides a torque meter for detecting torque, comprising a first disk portion connected by a bolt to a first flange, which is the flange of a first rotating shaft, a second disk portion connected by a bolt to a second flange, which is the flange of a second rotating shaft, a hollow strain-flexing portion connecting the first disk portion to the second disk portion, and a strain gauge fixed to the inner peripheral surface of the strain-flexing portion, wherein the first disk portion is provided with n (where n is a plural) bolt holes arranged in the circumferential direction and through which bolts connecting the first flange to the first disk portion are passed, and the second disk portion is provided with n through holes for passing bolts connecting the first flange to the first disk portion, the through holes being arranged at positions overlapping with each of the n bolt holes when viewed in the axial direction of the torque meter, and m (where m is a plural) screw holes arranged in the circumferential direction and through which bolts connecting the second flange to the second disk portion are screwed. Here, the angle moving in one direction around the axis of the torque meter is defined as the phase angle, and each of the screw holes is provided at a position having a different phase angle from the bolt holes, and the strain gauge is arranged at a position where the phase angle difference between the strain gauge and the bolt hole whose phase angle is closest to the strain gauge is equal to the phase angle difference between the strain gauge and the screw hole whose phase angle is closest to the strain gauge.

[0012] In such a torque meter, m may be a number equal to n, the n bolt holes may be arranged at phase angle intervals of 360 / n°, and the n screw holes may be arranged at phase angle intervals of 360 / n°. In this case, the n screw holes and the n bolt holes may differ in phase angle by 360 / 2n°, and the strain gauge may be arranged at a position whose phase angle differs by 360 / 4n° from both the bolt hole whose phase angle is closest to the strain gauge and the screw hole whose phase angle is closest to the strain gauge.

[0013] In this case, the torque meter may include n strain gauges, and the n strain gauges may be arranged at phase angle intervals of 360 / n° and with a phase angle difference of 360 / 4n° from the n bolt holes.

[0014] In the above torque meter, at least a portion of the area around the bolt hole on the surface of the first disk portion that faces the first flange when the first flange is connected may be shaped to protrude in the direction of the first flange so that the only place where the first disk portion and the first flange abut in the axial direction when the first flange is connected is the same portion, and at least a portion of the area around the screw hole on the surface of the second disk portion that faces the second flange when the second flange is connected may be shaped to protrude in the direction of the second flange so that the only place where the second disk portion and the second flange abut in the axial direction is the same when the second flange is connected.

[0015] The present invention also provides a measurement system comprising a torque meter, the first rotatable shaft having the first flange, and the second rotatable shaft having the second flange. Such a measurement system may be configured such that the first flange and the first disk portion abut in the axial direction only in the area surrounding the bolt hole, and the second flange and the second disk portion abut in the axial direction only in the area surrounding the screw hole. Alternatively, such a measurement system may include at least one of a first member, which is arranged between the first flange and the first disk portion so that the first flange and the first disk portion do not directly abut in the axial direction, and has one end face axially abutting the first flange and the other end face axially abutting the first flange in the area around the bolt hole when viewed in the axial direction, and a second member, which is arranged between the second flange and the second disk portion so that the second flange and the second disk portion do not directly abut in the axial direction, and has one end face axially abutting the second flange and the other end face axially abutting the second flange in the area around the screw hole when viewed in the axial direction.

[0016] These torque meters and measurement systems allow the connection of both the first flange of the first rotating shaft and the second flange of the second rotating shaft to the torque meter from the second rotating shaft side, and it is possible to balance the force acting from the first flange, which is a cause of error, and the force acting from the second flange, which is a cause of error, thereby reducing strain measurement errors by strain gauges and changes in measurement error due to changes in condition. Effect of the Invention

[0017] According to the present invention, in a torque meter that is disposed between two rotating shafts and in which the connection work with each rotating shaft can be performed from one of the rotating shafts, it is possible to perform highly accurate torque measurement with reduced error. [Brief description of the drawings]

[0018] [Figure 1] 1 is a diagram showing a configuration of a torque measuring device and a measurement system according to an embodiment of the present invention; [Diagram 2] FIG. 1 is a diagram showing a torque meter according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram showing a configuration for detecting rotation of a torque measuring device according to an embodiment of the present invention. [Figure 4] 1 is a diagram showing a structure for connecting a rotating shaft to a torque meter according to an embodiment of the present invention; [Diagram 5] FIG. 2 is a diagram showing the periphery of a bolt hole and a screw hole of the torque meter according to the embodiment of the present invention. [Figure 6] 1 is a diagram showing a strain gauge and its arrangement according to an embodiment of the present invention; [Figure 7] FIG. 2 is a diagram illustrating a distortion detection circuit according to an embodiment of the present invention. [Figure 8] FIG. 11 is a diagram showing another example of the configuration of a torque meter according to an embodiment of the present invention. [Figure 9] FIG. 1 shows a known torque meter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] An embodiment of the present invention will be described. FIG. 1a shows the configuration of a torque measuring device according to this embodiment. In FIG. 1a, FIG. 1a1 shows a front view of the torque measuring device, FIG. 1a2 shows a side view of the torque measuring device, and FIG. 1a3 shows a rear view of the torque measuring device. As shown in the figure, the torque measuring device is composed of a torque meter 1 and a stator 2, and the stator 2 has an annular ring portion 21. Using the torque measuring device, for example, a measurement system as shown in FIG. 1b is configured. In the measurement system of Fig. 1b, a first flange 31, which is a flange provided at an end of a first rotating shaft 3, is connected to the front side of the torque meter 1, and a second flange 41, which is a flange provided at an end of a second rotating shaft 4, is connected to the rear side of the torque meter 1. The second rotating shaft 4 is rotated by a driving device 6 such as an engine or an electric motor, the first rotating shaft 3 is connected to a load device 5 such as a dynamometer, and the torque measuring device measures the torque acting between the first rotating shaft 3 and the second rotating shaft 4. However, it is also possible to configure the second rotating shaft 4 to be connected to the load device 5, and the first rotating shaft 3 to be rotated by the driving device 6.

[0020] In the measurement system, the torque meter 1 is supported by a first rotating shaft 3 and a second rotating shaft 4 connected to the torque meter 1 so that a portion of the torque meter 1 is positioned within the hollow of the ring portion 21 of the stator 2 in a non-contact manner.

[0021] The ring portion 21 of the stator 2 forms a one-turn coil that functions both as a power transmission coil for wireless power supply and as a wireless communication antenna, and the stator 2 can transmit power to the torque meter 1 wirelessly and communicate with the torque meter 1 wirelessly.

[0022] Next, the configuration of the torque meter 1 is shown in FIG. FIG. 2a1 shows a front view of the torque meter 1, FIG. 2a2 shows a side view of the torque meter 1, and FIG. 2a3 shows a rear view of the torque meter 1. As shown in Figures 2a1 and 2a3, the phase angle of the torque meter 1 which progresses clockwise from 0° to 360° as viewed from the front is defined, and Figure 2b shows a cross section taken along the cutting line AA at a phase angle of 0° shown in Figure 2a1. Here, where i is an integer from 0 to 7, the cross section taken along the cutting line at a phase angle of 0+(45×i)° is the same as Figure 2b.

[0023] Also, Fig. 2c shows a cross-sectional view taken along the cutting line BB at a phase angle of 22.5° shown in Fig. 2a3, where the cross-section taken along the cutting line at a phase angle of 22.5+(45×i)° is the same as Fig. 2c. Also, Fig. 2d shows a cross-sectional view taken along line CC at a phase angle of 11.25° shown in Fig. 2a3, where the cross-section taken along the line at a phase angle of 11.25+(45×i)° is the same as Fig. 2d. As shown in each figure, the torque meter 1 has a hollow cylindrical strain-flexing part 11, a disk-shaped first disk portion 12 with a central hole and provided in the form of a flange on the front side of the strain-flexing part 11, a disk-shaped second disk portion 13 with a central hole and provided in the form of a flange on the back side of the strain-flexing part 11, and an auxiliary flange 14 provided on the outer peripheral surface of the second disk portion 13.

[0024] In addition, the central portion of the strain-generating part 11 in the axial direction is made thin so that it can be easily deformed, and as shown in Figure 2d, a strain gauge 15 is fixed at a phase angle of 11.25 + (45 × i) ° in this thin portion.

[0025] The first disk portion 12 has eight bolt holes 121 arranged at equal phase angle intervals along the circumference, and each bolt hole 121 is provided at a position of a phase angle of 0+(45×i)°. The second disk portion 13 has eight screw holes 131 arranged at equal phase angle intervals along the circumference, and each screw hole 131 is provided at a position of a phase angle of 22.5+(45×i)°. The radial position of the central axis of each screw hole 131 is equal to the radial position of the central axis of the bolt hole 121 of the first disk portion 12.

[0026] The second disk portion 13 has eight through holes 132 spaced at equal phase angle intervals along the circumference, and each through hole 132 is arranged at a phase angle of 0+(45×i)° such that its central axis overlaps with the central axis of the bolt hole 121 of the first disk portion 12 when viewed in the axial direction. The hole diameter of each through hole 132 is set to a hole diameter that allows a bolt to pass through the through hole 132 in the axial direction.

[0027] A coil 16 is wound around the outer circumferential end of the first disk portion 12, and serves as both a power receiving coil for wireless power supply and a wireless communication antenna. Here, as shown in FIG. 1a, the first disk portion 12 is arranged coaxially with the ring portion 21 of the stator 2 within the hollow thereof which houses the stator side coil, and the torque meter 1 can wirelessly receive power from the stator 2 via the coil 16 wound around the outer peripheral end of the first disk portion 12, and can communicate with the stator 2 wirelessly.

[0028] The torque meter 1 is equipped with a strain detection circuit configured using a strain gauge 15. The strain detection circuit detects the strain of the strain-generating part 11 using power supplied to a coil 16, and the strain detected by the strain detection circuit is transmitted to the stator 2 by wireless communication via the coil 16.

[0029] As shown in the side view of Fig. 3a and the rear view of Fig. 3b, an annular gear 17 used for rotation detection can be attached to the torque meter 1 by using the auxiliary flange 14 provided on the outer circumferential surface of the second disk portion 13. When rotation detection is performed using the gear 17, a magnetic sensor 22 that detects magnetic changes caused by the passage of teeth of the gear 17 is provided on the stator 2, and the rotation angle and rotation speed of the torque meter 1 are calculated from the output of the magnetic sensor 22. However, instead of the gear 17, an annular disk with slits arranged in the circumferential direction may be attached to the torque meter 1 by using the auxiliary flange 14, and instead of the magnetic sensor 22, an optical sensor that detects optical changes caused by the passage of the slits may be provided on the stator 2, and the rotation angle and rotation speed of the torque meter 1 may be calculated from the output of the optical sensor.

[0030] Next, a connection structure between the first rotating shaft 3 connected to the load device 5, the second rotating shaft 4 rotated and driven by the drive device 6, and the torque meter 1 when the measurement system is configured will be described.

[0031] As shown diagrammatically in FIG. 4a, a first flange 31 at the end of a first rotating shaft 3 is connected to the front side of the torque meter 1, and a second flange 41 at the end of a second rotating shaft 4 is connected to the rear side of the torque meter 1. The torque meter 1 detects the torque transmitted between the second rotating shaft 4 and the first rotating shaft 3 as a strain in the strain-flexing part 11 using a strain gauge 15.

[0032] As shown in the side view of FIG. 4b, the first flange 31 is connected to the torque meter 1 by fastening the first disk portion 12 and the first flange 31 with bolts, and the second flange 41 is connected to the torque meter 1 by fastening the second disk portion 13 and the second flange 41 with bolts.

[0033] The first rotating shaft 3 and the second rotating shaft 4 are connected to the torque meter 1 in the following procedure. First, as shown in FIG. 4c1, a bolt is passed through the through hole 132 of the second disc portion 13 from the rear side and passed through the bolt hole 121 of the first disc portion 12, and the bolt passed through the bolt hole 121 is screwed into the connecting screw hole 311 provided in the first flange 31 of the first rotating shaft 3, thereby fastening the first disc portion 12 and the first flange 31.

[0034] Next, as shown in Figure 4c2, a bolt is passed through a connecting bolt hole provided in the second flange 41 of the second rotating shaft 4 and screwed into the screw hole 131 of the second disk portion 13 to fasten the second disk portion 13 and the second flange 41.

[0035] In this manner, in the torque meter 1 according to this embodiment, the operation of connecting both the first flange 31 and the second flange 41 to the torque meter 1 can be performed from the rear side. Next, FIG. 5a1 shows a schematic perspective view of the periphery of the bolt hole 121 of the first disk portion 12 as viewed from the front side, and FIG. 5a2 shows a schematic cross section of the bolt hole 121 of the first disk portion 12. The front end face of first disk portion 12 forms the same plane with the axial direction as the normal line, except for the periphery of bolt hole 121, but as shown in the figure, the periphery of bolt hole 121 protrudes (is convex) slightly toward the front in an annular shape with bolt hole 121 as the central hole, from the plane outside the periphery of bolt hole 121. For example, the shape of the convex portion is such that bolt hole 121 has a diameter of φ19, the height of the portion protruding from the plane around bolt hole 121 is 0.1 mm, and the diameter is φ29.

[0036] On the other hand, the end face of the first flange 31 of the first rotating shaft 3, which faces the front end face of the first disk portion 12, is formed into a flat surface. Therefore, when the first rotating shaft 3 is connected to the torque meter 1 with a bolt, the area of ​​the first disk portion 12 that abuts axially with the first flange 31 of the first rotating shaft 3 is only the area around the bolt hole 121 shown in gray fill in Figure 5a3.

[0037] Next, FIG. 5b1 shows a schematic perspective view of the periphery of the screw hole 131 of the second disk portion 13 as viewed from the rear side, and FIG. 5b2 shows a schematic cross section of the screw hole 131 of the second disk portion 13. The rear end face of the second disk portion 13 forms the same plane with the axial direction as the normal line, except for the periphery of the screw hole 131, but as shown in the figure, the periphery of the screw hole 131 protrudes (is convex) slightly toward the rear in a circular shape with the screw hole 131 as the central hole from the plane outside the periphery of the screw hole 131. For example, the shape of the convex portion is M18 for the screw hole 131, the height of the portion protruding from the plane around the screw hole 131 is 0.1 mm, and the diameter is φ29.

[0038] On the other hand, the end face of the second flange 41 of the second rotating shaft 4 that faces the front end face of the second disk portion 13 is formed into a flat surface. Therefore, when the second rotating shaft 4 is connected to the torque meter 1 with a bolt, the area of ​​the second disk portion 13 that abuts axially with the second flange 41 of the second rotating shaft 4 is only the area around the screw hole 131 shown in gray fill in Figure 5b3.

[0039] In such a torque meter 1, the contact points between the first disk and the first flange 31 are concentrated only in the area around the bolt fastening them together, reducing the contact area. Similarly, the contact points between the second disk and the second flange 41 are concentrated only in the area around the bolt fastening them together, reducing the contact area.

[0040] FIG. 6a shows the structure of the strain gauge 15. As shown in the figure, each strain gauge 15 has a resistance element L and a resistance element R whose resistance value changes with deformation. Each strain gauge 15 is fixed to the inner circumferential surface of the strain-flexing part 11 so that the direction indicated by the arrow in the figure is the direction in which the phase angle advances.

[0041] 6b shows a schematic arrangement of the strain gauges 15. Eight strain gauges 15 are fixed on the inner peripheral surface of the strain-flexing part 11 along the circumferential direction with a phase angle difference of 45°. The eight strain gauges 15 are fixed at positions where the phase angle is 11.25+(45×i)°, i.e., where the phase angles are 11.25°, 56.25°, 101.25°, 146.25°, 191.25°, 236.25°, 281.25°, and 326.25°, so that resistance element L is located on the side where the phase angle decreases and resistance element R is located on the side where the phase angle advances.

[0042] FIG. 7 shows a strain detection circuit provided in the torque meter 1. The distortion detection circuit is a circuit that operates using a constant voltage power supply generated by power supply circuit 700 from power received wirelessly by coil 16 as its operating power source, and is equipped with a bridge circuit 701 that outputs a detection signal indicating the amount of distortion of strain-generating portion 11, an amplifier 702 that amplifies the output of bridge circuit 701, a voltage-frequency converter 703 whose oscillation frequency is controlled by the magnitude of the output voltage of amplifier 702, an amplitude shift modulation circuit 704 that amplitude-modulates the oscillation signal output by voltage-frequency converter 703 with a carrier wave of, for example, 5.5 MHz, and a transmission amplifier 705 that amplifies the amplitude-modulated wave signal output by amplitude shift modulation circuit 704.

[0043] Then, the coil 16 is driven by the amplitude-modulated wave signal amplified by the transmission amplifier 705, and the amplitude-modulated wave signal is wirelessly transmitted to the stator 2. The stator 2 demodulates the amplitude-modulated wave signal received by the stator side coil of the ring portion 21 into an oscillation signal, and converts the frequency of the demodulated oscillation signal into a measurement signal representing the amount of distortion of the strain-generating portion 11 or the torque transmitted from the first rotating shaft 3 to the second rotating shaft 4.

[0044] The bridge circuit 701 of the strain detection circuit is a bridge circuit 701 configured using 16 resistance elements, which are the resistance elements L and R of the eight strain gauges 15. As shown in FIG. 6b, the strain gauge 15 at the position of 11.25° is designated as 15A, the strain gauge 15 at the position of 56.25° is designated as 15B, the strain gauge 15 at the position of 101.25° is designated as 15C, and the strain gauge 15 at the position of 146.25° is designated as 15D. The strain gauge 15 at the position of 191.25° is 15D, the strain gauge 15 at the position of 236.25° is 15F, the strain gauge 15 at the position of 281.25° is 15G, and the strain gauge 15 at the position of 326.25° is 15H, and in the bridge circuit 701, resistance element 15x_L represents resistance element L of strain gauge 15x, and resistance element 15x_R represents resistance element R of strain gauge 15x. Here, x represents A to H as above.

[0045] As described above, in this embodiment, so that both the first flange 31 and the second flange 41 can be fastened to the torque meter 1 from the rear side, the bolt hole 121 in the first disk portion 12 used to fasten the first disk portion 12 to the first flange 31 with a bolt and the screw hole 131 in the second disk portion 13 used to fasten the second disk portion 13 to the second flange 41 with a bolt are arranged with a phase angle shift of 22.5°, and a through hole 132 for attaching a bolt to the bolt hole 121 in the first disk portion 12 from the rear side of the torque meter 1 is arranged in the second disk portion 13 at a position overlapping with the bolt hole 121 in the first disk portion 12 when viewed in the axial direction.

[0046] In addition, eight strain gauges 15 were provided at phase angle intervals of 45°, and the phase angle of each strain gauge 15 was made to differ by 11.25° both with respect to the bolt hole 121 in the first disk portion 12, which has the closest phase angle to that strain gauge 15, and with respect to the screw hole 131 in the second disk portion 13, which has the closest phase angle to that strain gauge 15.

[0047] The inventors have confirmed through experiments that by arranging the bolt hole 121 of the first disk portion 12 and the screw hole 131 of the second disk portion 13 in such a positional relationship, it is possible to reduce the strain measurement error by the strain gauge 15 and to suppress changes in the measurement error due to changes in the torque applied to the torque meter 1.

[0048] It is believed that such an effect is obtained for the following reasons. Fastening the first disk portion 12 and the first flange 31 with bolts creates a force that pulls the first disk portion 12 towards the first flange 31, and fastening the second disk portion 13 and the second flange 41 with bolts creates a force that pulls the second disk portion 13 towards the second flange 41. At a position where these forces in both directions are not balanced, the magnitude and direction of the force applied to that position due to the forces in both directions fluctuates greatly according to changes in conditions such as the magnitude of the torque applied to the torque meter 1, and when the distortion is measured at that position, this appears as a large measurement error.

[0049] In this embodiment, strain gauge 15 is positioned at a position where the phase angle is midway between the phase angle of bolt hole 121 and the phase angle of screw hole 131, where the forces in both directions mentioned above are balanced. Therefore, fluctuations in response to changes in the magnitude and direction of the force applied due to the forces in both directions are small, and measurement errors and changes in measurement error of strain gauge 15 are suppressed.

[0050] Furthermore, in this embodiment, force is transmitted between the first disk portion 12 and the first flange 31 only in the area where the first disk portion 12, concentrated around the bolt hole 121, and the first flange 31 abut in the axial direction, and force is transmitted between the first disk portion 12 and the first flange 31 only in the area where the second disk portion 13, concentrated around the screw hole 131, and the second flange 41 abut in the axial direction. Therefore, the force acting on the strain gauge 15, which is a cause of error, can be more stably reduced.

[0051] The embodiment of the present invention has been described above. In the above embodiment, the number of strain gauges 15 is eight, but the number of strain gauges 15 may be any number. In either case, however, strain gauges 15 are placed at a phase angle intermediate between the phase angle of bolt hole 121 and the phase angle of screw hole 131. When the number of strain gauges 15 is four, for example, as shown in Fig. 6c, strain gauges 15 are placed at phase angle positions of 11.25°, 101.25°, 191.25°, and 281.25° at phase angle intervals of 90°.

[0052] In the above embodiment, the number of bolt holes 121, through holes 132, and screw holes 131 is eight, but these numbers may be arbitrary. Also, the number of screw holes 131 may be a multiple or divisor of the number of bolt holes 121 / through holes 132. However, in any case, strain gauge 15 is disposed at a position with a phase angle intermediate between the phase angle of bolt hole 121 and the phase angle of screw hole 131.

[0053] In addition, in the above embodiment, the first disk portion 12 and the first flange 31 are configured to abut in the axial direction only around the bolt holes 121, and the second disk portion 13 and the second flange 41 are configured to abut in the axial direction only around the screw holes 131. However, the first disk portion 12 and the first flange 31, or the second disk portion 13 and the second flange 41 may abut in the axial direction over a wider surface, for example, by abutting the entire annular area that contains each bolt hole 121 on the end face of the first disk portion 12 with the first flange 31, or by abutting the entire annular area that contains each screw hole 131 on the second disk portion 13 with the second flange 41.

[0054] Even in this way, the force between the first disk portion 12 and the first flange 31 is stronger around the bolt hole 121 where the fastening force of the bolt is directly applied, and the force between the second disk portion 13 and the second flange 41 is stronger around the screw hole 131 where the fastening force of the bolt is directly applied, so that a certain effect can be expected in suppressing the measurement error of the strain by the strain gauge 15 and the fluctuation of the measurement error due to changes in the condition.

[0055] In addition, in the above embodiment, the periphery of the bolt hole 121 in the front end face of the first disk portion 12 is protruded in the front direction so that the area where the first disk portion 12 and the first flange 31 abut in the axial direction is limited to the area around the bolt hole 121. However, this may be achieved by forming the front end face of the first disk portion 12 as a flat surface without protruding the periphery of the bolt hole 121 in the front end face, and instead, by slightly protruding the periphery of the connecting screw hole 311 in the first flange 31 in the rear direction, as shown in the schematic oblique view of the first flange 31 of the first rotating shaft 3 in Figure 8a1 and the schematic oblique view of the periphery of the connecting screw hole 311 in the first flange 31 in Figure 8a2, so that the area where the first disk portion 12 and the first flange 31 abut in the axial direction is limited to the area around the bolt.

[0056] Similarly, the rear end face of the second disk portion 13 may be formed flat without protruding the area around the screw hole 131, and instead, as shown in the schematic oblique view of the second flange 41 of the second rotating shaft 4 in Figure 8b1 and the schematic oblique view of the area around the connecting bolt hole of the second flange 41 in Figure 8b2, the area where the second disk portion 13 and the second flange 41 abut in the axial direction may be limited to the area around the bolt.

[0057] In another embodiment, the front end face of the first disk portion 12 may be formed flat without protruding the area around the bolt hole 121 in the front end face, and instead, as shown in the schematic diagram of Figure 8c1, the bolt used to connect the first disk portion 12 to the first flange 31 may be passed through the central hole of the annular member 7 between the front end face of the first disk portion 12 and the first flange 31 and screwed into the connecting screw hole 311 in the first flange 31, thereby limiting the area of ​​axial contact between the first disk portion 12 and the first flange 31 to the area around the bolt.

[0058] Similarly, the rear end face of the second disk portion 13 may be formed flat without protruding the periphery of the screw hole 131 on the rear end face, and as shown in FIG. 8c2, a bolt used to connect the second disk portion 13 to the second flange 41 may be passed through a central hole of the annular member 7 between the rear end face of the second disk portion 13 and the second flange 41 and screwed into the screw hole 131 of the second disk portion 13, thereby limiting the area where the second disk portion 13 comes into axial contact with the second flange 41 to the area around the bolt. [Explanation of symbols]

[0059] Reference Signs List 1...torque meter, 2...stator, 3...first rotating shaft, 4...second rotating shaft, 5...load device, 6...drive device, 7...annular member, 9...torque meter, 11...strain-generating portion, 12...first disk portion, 13...second disk portion, 14...auxiliary flange, 15...strain gauge, 16...coil, 17...gear, 21...ring portion, 22...magnetic sensor, 31...first flange, 41...second flange, 91...hollow body portion, 92...drive side flange portion, 93...load side flange portion, 94...strain gauge, 121...bolt hole, 131...screw hole, 132...through hole, 700...power supply circuit, 701...bridge circuit, 702...amplifier, 703...voltage-frequency converter, 704...amplitude shift modulation circuit, 705...transmitting amplifier.

Claims

1. A torque meter for detecting torque, comprising: a first disk portion connected to a first flange, which is a flange of a first rotating shaft, by a bolt; a second disk portion connected to a second flange, which is a flange of a second rotating shaft, by a bolt; a hollow strain-generating portion that connects the first disk portion and the second disk portion; A strain gauge fixed to an inner peripheral surface of the strain-flexing part, the first disk portion has n bolt holes (where n is a plural number) arranged in a circumferential direction and through which bolts are inserted to connect the first flange and the first disk portion; the second disk portion has n through holes for passing bolts connecting the first flange and the first disk portion therethrough, the through holes being provided at positions overlapping with the n bolt holes as viewed in the axial direction of the torque meter, and m (where m is a plural number) screw holes arranged in a circumferential direction into which the bolts connecting the second flange and the second disk portion are screwed; a phase angle is an angle that advances in one direction around an axis of the torque meter, and each of the screw holes is provided at a position having a different phase angle from the bolt holes, The strain gauge is arranged at a position where a phase angle difference between the strain gauge and the bolt hole, whose phase angle is closest to the strain gauge, is equal to a phase angle difference between the strain gauge and the screw hole, whose phase angle is closest to the strain gauge.

2. 2. The torque meter according to claim 1, The m is a number equal to the n, The n bolt holes are arranged at phase angle intervals of 360 / n°, The n screw holes are arranged at phase angle intervals of 360 / n°, The n screw holes and the n bolt holes have a phase angle difference of 360 / 2n°, The torque meter is characterized in that the strain gauge is arranged at a position whose phase angle differs by 360 / 4n° from both the bolt hole whose phase angle is closest to the strain gauge and the screw hole whose phase angle is closest to the strain gauge.

3. 3. The torque meter according to claim 2, The strain gauge includes n strain gauges, The n strain gauges are arranged at phase angle intervals of 360 / n°, A torque meter, characterized in that the n strain gauges and the n bolt holes have a phase angle difference of 360 / 4n°.

4. 4. The torque meter according to claim 1, 2 or 3, at least a part of a region around the bolt hole on a surface of the first disk portion that faces the first flange when the first flange is connected has a shape that protrudes toward the first flange such that the first disk portion and the first flange abut only on the part in the axial direction when the first flange is connected; a torque meter characterized in that at least a portion of the area surrounding the screw hole on the surface of the second disk portion that faces the second flange when the second flange is connected has a shape that protrudes toward the second flange so that the only point where the second disk portion and the second flange abut in the axial direction when the second flange is connected is the said portion.

5. A measurement system comprising the torque meter according to claim 1, 2 or 3, the first rotating shaft having the first flange, and the second rotating shaft having the second flange, the first flange and the first disk portion are in axial contact with each other only in a region around the bolt hole, A measurement system, characterized in that the second flange and the second disk portion abut in the axial direction only in the area surrounding the screw hole.

6. A measurement system comprising the torque meter according to claim 1, 2 or 3, the first rotating shaft having the first flange, and the second rotating shaft having the second flange, a first member, which is disposed between the first flange and the first disk portion so that the first flange and the first disk portion do not come into direct axial contact with each other, and which has one end face that comes into axial contact with the first disk portion and the other end face that comes into axial contact with the first flange in a region around the bolt hole as viewed in the axial direction; a second member having one end face that axially abuts against the second flange and the other end face that axially abuts against the second disk portion in a region around the screw hole as viewed in the axial direction, the second member being disposed between the second flange and the second disk portion so that the second flange and the second disk portion do not directly abut against each other in the axial direction; A measurement system comprising at least one of the following:

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