Torque Sensor

Abstract

To provide a torque sensor that can be downsized by having a simpler structure.SOLUTION: The present invention includes: a rotary differential transformer (110) with a rotatable main shaft (111); and a twist spring (120) for generating a twist between the main shaft (111) and the rotary differential transformer (110) according to rotation of the main shaft (111), and the rotary differential transformer (110) outputs a voltage corresponding to an angle of rotation of the main shaft (111). A twist is generated in the twist spring (120) according to torque that acts on the main shaft (111), and the torque is thus measured on the basis of the voltage of the rotary differential transformer (110) output according to the angle of rotation of the main shaft (111) and characteristics of the twist spring (120).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a torque sensor, and more particularly to a new improvement for configuring a torque sensor more compact than conventional ones. [Background technology]

[0002] A known torque sensor detects the difference in rotation caused by the twisting of the input side and output side of a torsion bar.

[0003] For example, the torque sensor shown in Patent Document 1 has a pair of resolvers arranged on both ends of a torsion bar, and discloses a technique for measuring steering torque based on the torsion of the torsion bar detected by the pair of resolvers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-48760 A Summary of the Invention [Problem to be solved by the invention]

[0005] The above torque sensor has problems such as an increase in manufacturing cost according to the number of resolvers used and an increase in the size of the device. In addition, it is necessary to use a complex processing circuit such as an RD (Resolver Digital) converter to process the output of the resolver. Furthermore, the above torque sensor uses a torsion bar with a certain length to provide a twist, which limits the environments in which it can be used.

[0006] In order to solve the above problems, an object of the present invention is to provide a torque sensor that can be made smaller with a simple configuration. [Means for solving the problem]

[0007] The torque sensor according to the present invention is characterized by comprising a rotary differential transformer having a rotatable main shaft and outputting a voltage corresponding to the rotation angle of the main shaft, and a torsion spring that generates a twist in response to the rotation of the main shaft.

[0008] The torque sensor according to the present invention further comprises an arm attached to the main shaft and a stopper attached to the rotary type differential transformer, the arm rotates one end of the torsion spring in response to rotation of the main shaft, and the stopper fixes the position of the other end of the torsion spring.

[0009] In the torque sensor of the present invention, the torsion spring has a first hook at one end and a second hook at the other end, and when the main shaft rotates in a first direction, the first hook rotates in the first direction in response to the movement of the arm and the second hook is fixed in position by the stopper, and when the main shaft rotates in a second direction, the first hook is fixed in position by the stopper and the second hook rotates in the second direction in response to the movement of the arm. The torque sensor according to the present invention is characterized by further comprising a calculation unit that calculates the torque acting on the main shaft based on the voltage output from the rotary differential transformer and the characteristics of the torsion spring. Effect of the Invention

[0010] The torque sensor according to the present invention includes a rotary differential transformer having a rotatable main shaft, and a torsion spring that generates a torsion in response to the rotation of the main shaft, and the torsion spring is torsioned in response to the rotation of the main shaft, and the rotary differential transformer outputs a voltage corresponding to the rotation angle. Here, the main shaft is rotated and the torsion spring is torsioned in response to the rotation of the main shaft, and the torque of the rotation of the main shaft is equal to the torsional stress of the torsion spring. Therefore, the torque acting on the main shaft can be measured based on the voltage output from the rotary differential transformer in response to the rotation angle of the main shaft and the characteristics of the torsion spring. Therefore, a torque sensor that can be miniaturized with a simple configuration can be realized. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a configuration diagram showing a configuration of a torque sensor according to a first embodiment. [Diagram 2] FIG. 2 is a configuration diagram showing a state in which a stopper is removed from the configuration of the torque sensor according to the first embodiment. [Diagram 3] FIG. 4 is an explanatory diagram showing an operating state in which a main shaft rotates clockwise during torque measurement by the torque sensor of the first embodiment. [Figure 4] FIG. 4 is an explanatory diagram showing an operating state in which the main shaft rotates counterclockwise during torque measurement by the torque sensor of the first embodiment. [Diagram 5] FIG. 2 is an explanatory diagram showing a torsion spring used in the torque sensor of the first embodiment. [Figure 6] FIG. 4 is a characteristic diagram showing the characteristics of a torsion spring used in the torque sensor of the first embodiment. [Figure 7] FIG. 4 is a characteristic diagram showing characteristics of a rotary differential transformer used in the torque sensor of the first embodiment. [Figure 8] FIG. 3 is an explanatory diagram showing characteristics of the torque sensor according to the first embodiment. [Figure 9] FIG. 2 is a configuration diagram showing a configuration for performing calculations in the torque sensor of the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the torque sensor of the present invention will be described with reference to the drawings.

[0013] Embodiment 1 First, the configuration of a torque sensor 100 according to the first embodiment will be described with reference to FIG. Fig. 1 is a configuration diagram showing the configuration of a torque sensor 100 according to the first embodiment. Here, Fig. 1(a) is a front view of the torque sensor 100, Fig. 1(b) is a left side view of the torque sensor 100, Fig. 1(c) is a right side view of the torque sensor 100, and Fig. 1(d) is a plan view of the torque sensor 100. Each of Fig. 1(a) to (d) is drawn using an orthographic projection method at the same scale.

[0014] [Configuration of torque sensor 100] 1, torque sensor 100 mainly includes a rotary differential transformer 110, a torsion spring 120, an arm 130, and a stopper 150. Note that Fig. 1 shows the state of torque sensor 100 before torque measurement is performed.

[0015] Rotary differential transformer 110 is provided with a rotatable main shaft 111. An object to be measured (not shown) can be attached to main shaft 111. Rotary differential transformer 110 outputs a voltage corresponding to the rotation angle of main shaft 111.

[0016] Torsion spring 120 pinches arm 130 and stopper 150 with a constant force between first hook 121 provided at one end and second hook 122 provided at the other end, and is disposed around main shaft 111 so as not to come into contact with main shaft 111. Torsion spring 120 generates a twist between main shaft 111 and the main body of rotary type differential transformer 110 in response to the rotation of main shaft 111.

[0017] The arm 130 is attached to the main shaft 111 using a screw 141, a spacer 142, and a nut 143 so as to be parallel to the main shaft 111. The arm 130 is provided with a first drive unit 131 having a recessed shape that rotates the first hook 121 about its axis as the main shaft 111 rotates, and a second drive unit 132 having a recessed shape that rotates the second hook 122 about its axis as the main shaft 111 rotates.

[0018] Stopper 150 is attached to mounting hole 163 (see FIG. 2) in the main body of rotary differential transformer 110 using screw 161 and spacer 162 so as to be located outside arm 130 around main shaft 111. Stopper 150 is provided with first fixing portion 151 having a recessed shape that fixes the position of first hook 121, and second fixing portion 152 having a recessed shape that fixes the position of second hook 122.

[0019] Before torque measurement, arm 130 is sandwiched between first hook 121 and second hook 122 of torsion spring 120. At this time, first hook 121 is located at first driving portion 131, and second hook 122 is located at second driving portion 132. Furthermore, before torque measurement, stopper 150 is sandwiched together with arm 130 between first hook 121 and second hook 122 of torsion spring 120 on the outer side of arm 130 with main shaft 111 as the center. At this time, first hook 121 is located at first fixing portion 151, and second hook 122 is located at second fixing portion 152.

[0020] During torque measurement, when the main shaft 111 rotates in either direction in response to the rotation of the object to be measured (described later), the position of either the first hook 121 or the second hook 122 is fixed by the stopper 150, and the other of the first hook 121 or the second hook 122 rotates in response to the movement of the arm 130, causing a twist in the torsion spring 120.

[0021] Here, in order to clearly show the relationship between the arm 130 present inside the stopper 150 and the torsion spring 120, FIG. 2 shows a state in which the stopper 150 has been removed from the torque sensor 100. FIG. 2 is a configuration diagram showing a state in which the stopper 150 has been removed from the configuration of the torque sensor 100 of the first embodiment. Here, FIG. 2(a) is a front view of the torque sensor 100, FIG. 2(b) is a left side view of the torque sensor 100, FIG. 2(c) is a right side view of the torque sensor 100, and FIG. 2(d) is a plan view of the torque sensor 100. Each of FIG. 2(a) to (d) is drawn using an orthographic projection method at the same scale.

[0022] 2, arm 130 is attached parallel to main shaft 111 using screw 141, spacer 142, and nut 143 at a position outside the annular portion of torsion spring 120 and inside stopper 150, with main shaft 111 as the center. Before torque measurement is performed, arm 130 is sandwiched between first hook 121 and second hook 122 of torsion spring 120. At this time, first hook 121 is located at first driving portion 131, and second hook 122 is located at second driving portion 132.

[0023] [Operation of torque sensor 100] Next, the operation of the torque sensor 100 will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is an explanatory diagram showing an operating state in which the main shaft rotates clockwise during torque measurement by the torque sensor 100 of the first embodiment. Fig. 4 is an explanatory diagram showing an operating state in which the main shaft rotates counterclockwise during torque measurement by the torque sensor 100 of the first embodiment. In Fig. 3 and Fig. 4, the torque sensor 100 is installed on a reference plane 1 so that a stable state can be maintained during torque measurement. In addition, the shaft 31 of the measurement object 30 is connected to the main shaft 111 of the torque sensor 100 via a coupling 20.

[0024] When the main shaft 111 rotates in either direction in response to the rotation of the measurement target 30, the position of either the first hook 121 or the second hook 122 is fixed by the stopper 150, and the other of the first hook 121 or the second hook 122 rotates in response to the movement of the arm 130. At this time, the rotary differential transformer 110 outputs a voltage corresponding to the rotation angle of the main shaft 111.

[0025] 3, when the main shaft 111 rotates in a clockwise direction (hereinafter, the first direction) in response to the rotation of the measurement object 30, the arm 130 rotates in the first direction in conjunction with the rotation of the main shaft 111. Here, the first hook 121 rotates in the first direction together with the first driving part 131 in response to the movement of the arm 130. And the second hook 122 remains fixed to the first fixing part 151 of the stopper 150.

[0026] 4, when the main shaft 111 rotates in a counterclockwise direction (hereinafter, the second direction) in response to the rotation of the measurement target 30, the arm 130 rotates in the second direction in conjunction with the rotation of the main shaft 111. Here, the first hook 121 remains fixed to the first fixing portion 151 of the stopper 150. Then, the second hook 122 rotates in the second direction together with the second driving portion 132 in response to the movement of the arm 130.

[0027] In the case of Figs. 3 and 4, the main shaft 111 is rotated in response to the rotation of the measurement object 30, and the torsion spring 120 is twisted in response to the rotation of the main shaft 111. As a result, the torque of the rotation of the measurement object 30 is equal to the torsional stress of the torsion spring 120. Here, the voltage output from the rotary differential transformer 110 is a voltage corresponding to the rotation angle of the main shaft 111, and indicates the torsional stress corresponding to the torsion angle of the torsion spring 120. In other words, the voltage output from the rotary differential transformer 110 indicates the torque acting on the main shaft 111. Therefore, the torsional stress of the torsion spring 120, that is, the torque acting on the main shaft 111, can be measured based on the voltage output from the rotary differential transformer 110 in response to the rotation angle of the main shaft 111 and the characteristics of the torsion spring 120.

[0028] [Detailed explanation of each part of the torque sensor 100] Each part constituting the torque sensor 100 will be described in detail below. First, the torsion spring 120 will be described with reference to Fig. 5. Fig. 5 is an explanatory diagram showing the torsion spring 120 used in the torque sensor 100 of the first embodiment. The torsion spring 120 is a coil spring including a coil portion 123 having multiple turns, a first hook 121 provided at one end, and a second hook 122 provided at the other end. Here, D is the average diameter which is the average of the outer diameter and inner diameter of the torsion spring 120, and d is the wire diameter of the spring material.

[0029] Next, the characteristics of the torsion angle θ and torque T of the torsion spring 120 will be described using mathematical expressions with reference to Fig. 6. Fig. 6 is a characteristic diagram showing the characteristics of the torsion spring 120 used in the torque sensor 100 of the first embodiment. In Fig. 6, the horizontal axis represents the torsion angle θ [°] of the torsion spring 120, and the vertical axis represents the torque T [Nm]. In the torsion spring 120, an inherent spring constant k1 is determined by the wire material, wire diameter d, and average diameter D used.

[0030] Here, the relationship between the torsion angle θ of the torsion spring 120 and the torque T is as follows: T=k1·θ...Equation (1), This can be expressed as: In addition, when the effective number of turns is Na and the modulus of longitudinal elasticity is E, the spring constant k1 as a characteristic of the torsion spring 120 is given by k1=π·E·d 4 / (11520·D·Na) …(2) This can be expressed as:

[0031] Therefore, as shown in Fig. 6, the torque T [Nm] is linearly proportional to the absolute value of the torsion angle θ [°]. In Fig. 6, the region where the torsion angle θ [°] is positive is a state where the torsion spring 120 is wound in a first direction by the first hook 121. In Fig. 6, the region where the torsion angle θ [°] is negative is a state where the torsion spring 120 is wound in a second direction opposite to the first direction by the second hook 122.

[0032] Next, the output characteristics of rotary differential transformer 110 will be described with reference to Fig. 7. Fig. 7 is a characteristic diagram showing the characteristics of rotary differential transformer 110 used in torque sensor 100 of the first embodiment. 7, the horizontal axis indicates the rotation angle θ [°] of rotary differential transformer 110, and the vertical axis indicates voltage V [Vrms]. Here, Va indicates voltage Va generated in phase A of rotary differential transformer 110, Vb indicates voltage Vb generated in phase B of rotary differential transformer 110, and Vout indicates output voltage Vout (=Va-Vb) of rotary differential transformer 110 obtained by subtracting voltage Vb from voltage Va. Also, Vsum indicates the sum voltage Vsum (=Va+Vb) of voltage Va generated in phase A and voltage Vb generated in phase B. As shown in FIG. 7, rotary differential transformer 110 has the characteristic of linearly changing output voltage Vout [Vrms] in linear proportion to rotation angle θ [°]. Here, if the sensitivity constant of the rotary differential transformer 110 is k2, the output voltage Vout [Vrms] of the rotary differential transformer 110 is expressed as follows: Vout=k2·θ …(3) This can be expressed as: Therefore, by rearranging the above equations (1) and (3), T = k1·θ =k1 (1 / k2) Vout =(k1 / k2) Vout As shown above, the torque T [Nm] can be calculated from the output voltage Vout [Vrms], the spring constant k1, and the sensitivity constant k2. If the spring constant k1 and the sensitivity constant k2 are considered as coefficients, the torque T can be calculated from the output voltage Vout.

[0033] Next, referring to FIG. 8, the characteristics of the torque sensor 100 using the rotary differential transformer 110 and the torsion spring 120 will be described. FIG. 8 is an explanatory diagram showing the characteristics of the torque sensor 100 of the first embodiment. In FIG. 8, the characteristics of the torsion angle θ and the torque T of the torsion spring 120 are shown by a dashed line, and the output characteristics of the rotary differential transformer 110 are shown by a two-dot chain line. Here, the horizontal axis of FIG. 8 indicates the torsion angle θ of the torsion spring 120 and the rotation angle θ of the rotary differential transformer 110, and the vertical axis indicates the torque T of the torsion spring 120 and the output voltage Vout of the rotary differential transformer 110. Note that the torsion angle θ of the torsion spring 120 is based on the rotation angle θ of the rotary differential transformer 110. Therefore, the torsion angle θ and the rotation angle θ are the same.

[0034] For example, when measurement #1 is performed on measurement object 30, it is assumed that output voltage Vout1 of rotary differential transformer 110 in torque sensor 100 is obtained (see (11) in FIG. 8). First, rotation angle θ1 [°] of rotary differential transformer 110 corresponding to this output voltage Vout1 is found (see (12)-(13) in FIG. 8). Then, torque T1 [Nm] corresponding to torsion angle θ1 of torsion spring 120 is found (see (13)-(14)-(15) in FIG. 8).

[0035] Also, when measurement #2 is performed on measurement object 30, it is assumed that output voltage Vout2 of rotary differential transformer 110 in torque sensor 100 is obtained (see (21) in FIG. 8). First, rotation angle θ2 [°] of rotary differential transformer 110 corresponding to this output voltage Vout2 is found (see (22)-(23) in FIG. 8). Then, torque T2 [Nm] corresponding to torsion angle θ2 of torsion spring 120 is found (see (23)-(24)-(25) in FIG. 8). Here, since the sign of output voltage Vout2 of rotary differential transformer 110 in measurement #2 is negative, it is clear that the rotation is in the opposite direction to measurement #1 of output voltage Vout1, which has a positive sign.

[0036] In the above measurements #1 and #2, the torques T1 and T2 can be calculated from the rotation angles θ1 and θ2 by calculation using the above-mentioned formulas. Furthermore, since the torques T1 and T2 are determined based on the absolute values ​​of the torsion angles θ1 and θ2 from the starting point regardless of the direction of rotation of the measurement object 30, calculations may be performed as absolute values ​​for the output voltage Vout and the torsion angle θ.

[0037] Next, a configuration for calculating torque T by performing a calculation on output voltage Vout of rotary differential transformer 110 in torque sensor 100 will be described with reference to Fig. 9. Fig. 9 is a configuration diagram showing a configuration for performing calculations in torque sensor 100 of the first embodiment. 9, in torque sensor 100, a calculation unit 170 is connected to the output of rotary differential transformer 110. The calculation unit 170 calculates the following equation from the spring constant k1 and the sensitivity constant k2 stored in the table 180 and the output voltage Vout of the rotary differential transformer 110: Torque T=(k1 / k2)·Vout Calculate the torque T according to the formula:

[0038] It is possible to realize the table 180 and the calculation unit 170 using a scaling calculation function of a general-purpose digital multimeter. Therefore, according to the torque sensor 100 of the first embodiment, it is possible to measure torque quickly and accurately with a simple configuration.

[0039] The torque sensor 100 of the first embodiment uses a rotary differential transformer 110 and a torsion spring 120 to calculate the torque T from the output voltage Vout of the rotary differential transformer 110, the spring constant k1, and the sensitivity constant k2. Therefore, compared to conventional methods that use a torsion bar or the like, the torque sensor 100 can be made smaller with a simpler configuration.

[0040] Furthermore, since the torque sensor 100 of the first embodiment uses the torsion spring 120, the torsion angle θ can be made larger than that of a torsion bar. This allows the torque sensor 100 of the first embodiment to have a wider measurement range than conventional torque sensor. In other words, compared to conventional torque sensor, it becomes possible to measure torques from small to large with a single torque sensor 100.

[0041] In addition, in the torque sensor 100 of embodiment 1, by using a torsion spring 120 having a different spring constant k1 or configuring the torsion spring 120 to be replaceable with a torsion spring having a different spring constant k1, it becomes possible to change the measurement range of the torque T.

[0042] In addition, since the torque T is calculated through a simple calculation using the output voltage Vout, the spring constant k1, and the sensitivity constant k2, there is no need to use a complex processing circuit such as a conventional RD converter, and the torque can be measured quickly and accurately using a simple processing circuit.

[0043] 7, the sum of the A-phase voltage Va and the B-phase voltage Vb of rotary differential transformer 110, Vsum=Va+Vb, has the characteristic of always being a constant voltage. Therefore, if a break occurs in at least one of the A-phase or B-phase windings of rotary differential transformer 110, sum voltage Vsum drops below the constant voltage. Using this characteristic, calculation unit 170 can detect a failure of torque sensor 100 by monitoring sum voltage Vsum.

[0044] [Effects obtained by the embodiment] The torque sensor 100 described in the first embodiment includes a rotary differential transformer 110 having a rotatable main shaft 111, and a torsion spring 120 which generates a torsion in response to the rotation of the main shaft 111. The torsion spring 120 is torsioned in response to the rotation of the main shaft 111, and the rotary differential transformer 110 outputs a voltage corresponding to the rotation angle. Here, the main shaft 111 is rotated and the torsion spring 120 is torsioned in response to the rotation of the main shaft, and the torque of the rotation of the main shaft 111 is equal to the torsion stress of the torsion spring 120. Therefore, the torque acting on the main shaft 111 can be measured based on the voltage output from the rotary differential transformer 110 in response to the rotation angle of the main shaft 111 and the characteristics of the torsion spring 120. Therefore, a torque sensor 100 which can be miniaturized with a simple configuration can be realized.

[0045] The torque sensor 100 described in the first embodiment further includes an arm 130 attached to the main shaft 111 and a stopper 150 attached to the rotary differential transformer 110. Here, the stopper 150 fixes the position of one end of the torsion spring 120, and the arm 130 rotates the other end of the torsion spring 120 in response to the rotation of the main shaft 111. As a result, when the main shaft 111 rotates in either direction, the position of either one end of the torsion spring 120 is fixed by the stopper 150, and the other end of the torsion spring 120 rotates in response to the movement of the arm 130, causing a twist in the torsion spring 120. Therefore, by rotating the main shaft 111, a torsion is reliably induced in the torsion spring 120 via the arm 130 with the stopper 150 attached to the rotary differential transformer 110 as a reference, and a compact torque sensor 100 can be realized that can reliably measure torque based on the voltage output from the rotary differential transformer 110 in accordance with the rotation angle of the main shaft 111 and the characteristics of the torsion spring 120.

[0046] In the torque sensor 100 described in the first embodiment, the torsion spring 120 has a first hook 121 at one end and a second hook 122 at the other end. Here, when the main shaft 111 rotates in a first direction, the position of the first hook 121 is fixed by the stopper 150, and the second hook 122 rotates in the first direction in response to the movement of the arm 130. On the other hand, when the main shaft 111 rotates in a second direction, the position of the second hook 122 is fixed by the stopper 150, and the first hook 121 rotates in the second direction in response to the movement of the arm 130. Therefore, it is possible to realize a small-sized torque sensor 100 that can reliably measure torque in response to both the rotation of the main shaft 111 in the first direction and the rotation in the second direction.

[0047] In the torque sensor 100 described in the first embodiment, the calculation unit 170 calculates the torque T acting on the main shaft 111 based on the voltage Vout output from the rotary differential transformer 110. This makes it possible to measure the torque quickly and accurately through calculations by a simple processing circuit, without using a complicated processing circuit such as a conventional RD converter.

[0048] [Other embodiments] In the above torque sensor 100, the torsion spring 120 and the object to be measured 30 are provided on the same side of the main shaft 111 with respect to the rotary differential transformer 110, but this configuration is not limited to this. For example, the main shaft 111 may be provided penetrating the rotary differential transformer 110, the torsion spring 120, the arm 130, and the stopper 150 may be provided on one end of the main shaft, and the object to be measured 30 may be attached via the coupling 20 to the other end of the main shaft.

[0049] Although the arm 130 and the stopper 150 are shown as rectangular plates having recesses in some parts, they are not limited to this and various modifications are possible. For example, the first driving unit 131 and the second driving unit 132 can be provided on the first arm and the second arm, which are independent of each other. [Industrial Applicability]

[0050] The torque sensor 100 of the present invention is smaller and has a simpler configuration than a conventional torque sensor using a torsion bar, and can measure torque quickly and accurately through calculations in a simple processing circuit. Therefore, the torque sensor 100 can be used for precise torque measurement in moving objects such as aircraft. [Explanation of symbols]

[0051] 1 reference surface, 20 coupling, 30 measurement object, 31 axis, 100 torque sensor, 110 rotary differential transformer, 111 main shaft, 120 torsion spring, 121 first hook, 122 second hook, 123 coil portion, 130 arm, 131 first drive portion, 132 second drive portion, 141 screw, 142 spacer, 143 nut, 150 stopper, 151 first fixed portion, 152 second fixed portion, 161 screw, 162 spacer, 163 mounting hole, 170 calculation portion, 180 table.

Claims

1. A rotary differential transformer (110) having a rotatable main shaft (111) and outputting a voltage corresponding to the rotation angle of the main shaft (111); a torsion spring (120) that generates a torsion in response to the rotation of the main shaft (111); An arm (130) attached to the main shaft (111); A stopper (150) attached to the rotary differential transformer (110); Equipped with The arm (130) rotates one end of the torsion spring (120) in response to the rotation of the main shaft (111), The stopper (150) fixes the position of the other end of the torsion spring (120). A torque sensor characterized by:

2. The torsion spring (120) has a first hook (121) at one end and a second hook (122) at the other end; When the main shaft (111) rotates in a first direction, the first hook (121) rotates in the first direction in response to the movement of the arm (130), and the second hook (122) is fixed in position by the stopper (150); When the main shaft (111) rotates in a second direction, the first hook (121) is fixed in position by the stopper (150), and the second hook (122) rotates in the second direction in response to the movement of the arm (130).

2. The torque sensor according to claim 1 .

3. and a calculation unit (170) that calculates a torque acting on the main shaft (111) based on the voltage output from the rotary differential transformer (110) and the characteristics of the torsion spring (120).

3. The torque sensor according to claim 1, wherein the first and second electrodes are arranged in a first direction.

Images