JP2021096267A - Torque sensor - Google Patents

Abstract

To provide a torque sensor that can detect torque with high accuracy and with high sensitivity, while being treatable with high load torque.SOLUTION: A torque sensor 100c of the present invention comprises: a deformation body 30 that generates elastic deformation by an action of torque; and a detection circuit 40 that outputs an electric signal indicative of the acted torque on the basis of the elastic deformation. The deformation body 30 has: fixation parts 33 and 35 that are fixed with respect to an XYZ three-dimensional coordinate system; force reception parts 32 and 34 that receive the action of the torque; a deformation part 36 that generates elastic deformation by acting the torque on the force reception parts 32 and 34; and a beam structure 31 that has a supporting body 31f connected to the deformation part 36, and beam 31b supported by the supporting body 31f. In the beam 31b, a measurement point P for measuring a displacement of the beam 31b is defined, and the detection circuit 40 is configured to output the electric signal on the basis of the displacement generating in the measurement P of the beam 31b.SELECTED DRAWING: Figure 6

Description

The present invention relates to a torque sensor, and more particularly to a sensor having a function of outputting a torque (moment) acting around a predetermined rotation axis as an electric signal.

Torque sensors are widely used in the field of torque control in industrial robots, life support robots, medical robots, and the like. In particular, in a torque sensor used in a robot that requires high safety, it is important to detect torque with higher accuracy and sensitivity.

As an example of the conventional torque sensor, the one described in Patent Document 1 below can be mentioned. The torque sensor of Patent Document 1 has an annular strain-generating body (annular deformed body), and the strain-causing body is elastically deformed in the radial direction by the applied torque. A capacitance element is arranged at a predetermined position on the strain-causing body, and the torque sensor operates based on the amount of change in the capacitance value of the capacitance element due to the elastic deformation of the strain-causing body. The torque is detected.

However, in order to detect a high-load torque using a conventional torque sensor, it is necessary to increase the rigidity of the strain-causing body. However, since the annular strain-causing body is not easily deformed, it is suitable for a high-load torque sensor. However, on the other hand, there is a problem that the sensitivity of the torque sensor is lowered.

Japanese Unexamined Patent Publication No. 2012-37300

The present invention has been devised in view of the above circumstances. That is, an object of the present invention is to provide a torque sensor capable of detecting torque with high accuracy and high sensitivity while being able to handle torque of a high load.

The present invention is a torque sensor that detects torque around the Z axis in the XYZ three-dimensional coordinate system.
A deformed body that undergoes elastic deformation due to the action of torque,
A detection circuit that outputs an electric signal indicating the applied torque based on the elastic deformation generated in the deformed body is provided.
The variant is
A fixed part fixed to the XYZ three-dimensional coordinate system,
A receiving part that is provided in a part different from the fixed part and is affected by torque, and a receiving part.
A deformed portion that connects the fixed portion and the receiving portion and causes elastic deformation by applying torque to the receiving portion, and a deformed portion.
It has a beam structure having a support connected to the deformed portion and a beam supported by the support.
The beam is defined with measurement points for measuring the displacement of the beam.
The detection circuit is a torque sensor characterized in that the electric signal is output based on the displacement generated at the measurement point of the beam due to the elastic deformation of the deformed body.

According to the present invention, the elastic deformation generated in the deformed body is amplified at the measurement point due to the presence of the beam structure, so that the torque can be detected with high accuracy and high sensitivity while being able to cope with a high load torque. A torque sensor can be provided.

The deformed portion of the deformed body may have a shape along an arc centered on the origin when viewed from the Z-axis direction. In this case, elastic deformation can be effectively caused in the deformed portion.

The fixed portion of the deformed body is positioned so as to overlap one of the X-axis and the Y-axis when viewed from the Z-axis direction.
The receiving portion of the deformed body may be positioned so as to overlap the other of the X-axis and the Y-axis when viewed from the Z-axis direction.

In this case, the elastic deformation generated in the deformed portion can be efficiently amplified at the measurement point of the beam.

Further, when the V-axis and the W-axis that pass through the origin and form a predetermined angle with respect to the X-axis and the Y-axis are defined on the XY plane, the measurement point of the beam is on the V-axis or the W-axis. It may be positioned. In this case, the elastic deformation that occurs in the deformed portion can be efficiently detected as the displacement that occurs at the measurement point of the beam. The predetermined angle is, for example, 45 °.

The above torque sensors are a fixed body fixed to the XYZ three-dimensional coordinate system and
Further equipped with a receiving body that rotates around the Z axis by the action of torque.
The fixed body is connected to the fixed portion of the deformed body and is connected to the fixed body.
The receiving body may be connected to the receiving portion of the deformed body.

In this case, torque can be detected stably.

The detection circuit has a displacement electrode arranged at the measurement point of the beam and a fixed electrode arranged opposite to the displacement electrode and connected to the receiving body or the fixed body.
The displacement electrode and the fixed electrode form a capacitance element, and the displacement electrode and the fixed electrode form a capacitance element.
The detection circuit may output the electric signal based on the amount of fluctuation of the capacitance value of the capacitance element.

In this case, the applied torque can be easily detected based on the fluctuation amount of the capacitance value.

Alternatively, the present invention is a torque sensor that detects torque around the Z axis in the XYZ three-dimensional coordinate system.
An annular plasmodium that is arranged so as to surround the origin when viewed from the Z-axis direction and elastically deforms due to the action of torque.
A detection circuit that outputs an electric signal indicating the applied torque based on the elastic deformation generated in the deformed body is provided.
The variant is
Two fixed parts fixed to the XYZ three-dimensional coordinate system,
Two receiving parts that are alternately positioned with the fixed part in the circumferential direction of the deformed body and are subjected to the action of torque.
Four deformed portions that connect the fixed portion and the receiving portion that are adjacent to each other in the circumferential direction of the deformed body and cause elastic deformation by applying torque to the receiving portion.
It has four beam structures, one connected to each deformed portion, and
Each beam structure has a support connected to the deformed portion and a beam supported by the support.
Each beam has a measurement point for measuring the displacement of each beam.
The detection circuit is a torque sensor characterized in that the electric signal is output based on the displacement generated at the measurement point of each beam due to the elastic deformation of the deformed body.

According to the present invention, the elastic deformation generated in the deformed body is amplified at the measurement point due to the presence of the beam structure, so that the torque can be detected with high accuracy and high sensitivity while being able to cope with a high load torque. A torque sensor can be provided.

The two fixing portions are positioned X-axis symmetrically at a portion where the deformed body and the Y-axis overlap when viewed from the Z-axis direction.
The two receiving portions may be positioned symmetrically with respect to the Y axis at a portion where the deformed body and the X axis overlap when viewed from the Z axis direction.

In this case, since elastic deformation can be generated symmetrically in each deformed portion, it is easy to measure the applied torque.

Further, when the V-axis and the W-axis passing through the origin and forming 45 ° with respect to the X-axis and the Y-axis are defined on the XY plane, the measurement points of each beam are on the positive V-axis and the positive W. It may be positioned on the axis, on the negative V-axis, and on the negative W-axis, respectively.

In particular, the V-axis passes through the origin and makes an angle of 45 ° with respect to the X-axis.
The W axis may pass through the origin and make an angle of 45 ° with respect to the Y axis.

In these cases, the elastic deformation generated in the deformed portion can be efficiently amplified at the measurement point of the beam.

In the above torque sensor, a fixed body fixed to the XYZ three-dimensional coordinate system and
Further equipped with a receiving body that rotates around the Z axis by the action of torque.
The fixed body is connected to the fixed portion of the deformed body and is connected to the fixed body.
The receiving body may be connected to the receiving portion of the deformed body.

In this case, torque can be detected stably.

The detection circuit has four displacement electrodes arranged at each measurement point of the beam, and a fixed electrode arranged to face the displacement electrodes and connected to the receiving body or the fixed body.
Each displacement electrode and the fixed electrode constitute four sets of capacitance elements.
The detection circuit may output the electric signal based on the fluctuation amount of the capacitance value of the four sets of capacitance elements.

More specifically, the four sets of capacitance elements are arranged in the first quadrant of the XY plane and the second quadrant of the XY plane when viewed from the Z-axis direction. It has a second capacitance element, a third capacitance element arranged in the third quadrant of the XY plane, and a fourth capacitance element arranged in the fourth quadrant of the XY plane.
In the detection circuit, the sum of the fluctuation amount of the capacitance value of the first capacitance element and the fluctuation amount of the capacitance value of the third capacitance element and the static of the second capacitance element. An electric signal indicating the acting torque may be output based on the difference between the fluctuation amount of the capacitance value and the fluctuation amount of the capacitance value of the fourth capacitance element. ..

In this case, the applied torque can be easily detected, and the influence of forces other than the torque around the Z axis (forces in the X, Y, Z axis directions and torque around the X, Z axis) and the usage environment can be affected. The desired torque can be detected without being affected by the temperature change.

The fixed electrode may be configured as an individual electrode for each capacitance element. In this case, the fixed electrodes can be arranged with a high degree of freedom.

Alternatively, the present invention is a torque sensor that detects torque around the Z axis in the XYZ three-dimensional coordinate system.
An annular plasmodium that is arranged so as to surround the origin when viewed from the Z-axis direction and elastically deforms due to the action of torque.
A detection circuit that outputs an electric signal indicating the applied torque based on the elastic deformation generated in the deformed body is provided.
The variant is
Two fixed parts fixed to the XYZ three-dimensional coordinate system,
Two receiving parts that are alternately positioned with the fixed part in the circumferential direction of the deformed body and are subjected to the action of torque.
Four deformed portions that connect the fixed portion and the receiving portion that are adjacent to each other in the circumferential direction of the deformed body and cause elastic deformation by applying torque to the receiving portion.
Four outer beam structures, one connected to the outer peripheral surface of each deformed part,
It has four inner beam structures, one connected to the inner peripheral surface of each deformed portion.
Each outer beam structure has an outer support connected to the deformed portion and an outer beam supported by the outer support.
Each inner beam structure has an inner support connected to the deformed portion and an inner beam supported by the inner support.
Each inner beam and each outer beam are defined with measurement points for measuring the displacement of each beam.
The detection circuit outputs the electric signal based on at least one of the displacement caused in each inner beam due to the elastic deformation of the deformed body and the displacement caused in each outer beam due to the elastic deformation. It is a torque sensor characterized in that it is designed to be used.

According to the present invention, the presence of the inner beam structure and the outer beam structure amplifies the elastic deformation generated in the deformed body at the measurement point, so that it is possible to cope with a high load torque, but it is highly accurate and highly sensitive. Can provide a torque sensor capable of detecting torque.

The two fixing portions are positioned symmetrically with respect to the X-axis at a portion where the deformed body and the Y-axis overlap when viewed from the Z-axis direction.
The two receiving portions may be positioned symmetrically with respect to the Y axis at a portion where the deformed body and the X axis overlap when viewed from the Z axis direction.

In this case, elastic deformation can be effectively generated in each deformed portion.

When the V-axis and W-axis that pass through the origin and form a predetermined angle with respect to the X-axis and Y-axis are defined on the XY plane,
Each measurement point of the four outer beam structures is positioned on the positive V-axis, the positive W-axis, the negative V-axis, and the negative W-axis, respectively.
Each measurement point of the four inner beam structures may be positioned on the positive V-axis, the positive W-axis, the negative V-axis, and the negative W-axis, respectively.

In particular, the V-axis passes through the origin and makes an angle of 45 ° with respect to the X-axis.
The W axis may pass through the origin and make an angle of 45 ° with respect to the Y axis.

In these cases, the elastic deformation generated in the deformed portion can be efficiently amplified at each measurement point of the inner beam and the outer beam.

The above torque sensors are a fixed body fixed to the XYZ three-dimensional coordinate system and
Further equipped with a receiving body that rotates around the Z axis by the action of torque.
The fixed body is connected to the fixed portion of the deformed body and is connected to the fixed body.
The receiving body may be connected to the receiving portion of the deformed body.

In this case, torque can be detected stably.

The detection circuit
Four inner displacement electrodes arranged one at each measurement point of the inner beam, and inner fixed electrodes arranged opposite to these inner displacement electrodes and connected to the receiving body or the fixed body.
It has four outer displacement electrodes arranged one at each measurement point of the outer beam, and outer fixed electrodes arranged opposite to these outer displacement electrodes and connected to the receiving body or the fixed body. And
Each inner displacement electrode and the inner fixed electrode constitute four sets of inner capacitance elements.
Each outer displacement electrode and the outer fixed electrode constitute four sets of outer capacitance elements.
The detection circuit is based on at least one of the fluctuation amount of the capacitance value of the four sets of inner capacitance elements and the fluctuation amount of the capacitance value of the four sets of outer capacitance elements. The electric signal may be output.

More specifically, the four sets of inner capacitance elements are arranged in the first quadrant of the XY plane and the second quadrant of the XY plane when viewed from the Z-axis direction. The arranged second inner capacitance element, the third inner capacitance element arranged in the third quadrant of the XY plane, and the fourth inner capacitance element arranged in the fourth quadrant of the XY plane. Have,
The four sets of outer capacitance elements are a first outer capacitance element arranged in the first quadrant of the XY plane and a second outer surface arranged in the second quadrant of the XY plane when viewed from the Z-axis direction. It has a capacitance element, a third outer capacitance element arranged in the third quadrant of the XY plane, and a fourth outer capacitance element arranged in the fourth quadrant of the XY plane.
The detection circuit is described by "the sum of the fluctuation amount of the capacitance value of the first inner capacitance element and the fluctuation amount of the capacitance value of the third inner capacitance element, and the second inner capacitance. "Difference between the amount of change in the capacitance value of the capacitance element and the sum of the amount of change in the capacitance value of the fourth inner capacitance element" and "the capacitance of the first outer capacitance element" The sum of the fluctuation amount of the capacitance value and the fluctuation amount of the capacitance value of the third outer capacitance element, the fluctuation amount of the capacitance value of the second outer capacitance element, and the fourth outer capacitance. The electric signal may be output based on at least one of "the difference between the sum of the capacitance value of the capacitance element and the fluctuation amount".

In this case, the applied torque can be easily detected, and the influence of forces other than the torque around the Z axis (forces in the X, Y, Z axis directions and torque around the X, Z axis) and the usage environment can be affected. The desired torque can be detected without being affected by the temperature change.

The inner fixed electrode and the outer fixed electrode may be configured as individual electrodes for each of the inner capacitance element and the outer capacitance element. In this case, each fixed electrode can be arranged with a high degree of freedom.

The detection circuit is based on the torque measured based on the fluctuation amount of the capacitance value of the four sets of outer capacitance elements and the fluctuation amount of the capacitance value of the four sets of inner capacitance elements. By comparing the torque measured with the torque sensor, it may be determined whether or not the torque sensor is functioning normally.

In this case, in addition to detecting the applied torque, the failure diagnosis can be performed by a single torque sensor.

Further, the deformed body may have a shape symmetrical with respect to the X-axis and the Y-axis when viewed from the Z-axis direction.

In particular, the deformed body may have the shape of an annulus centered on the origin when viewed from the Z-axis direction.

In these cases, the calculation for detecting the applied torque is easy.

In the above torque sensor, the beam structure may have a connecting body that connects the beam and the fixed body or the receiving body.

Alternatively, the outer beam structure has an outer connecting body that connects the outer beam and the receiving body.
The inner beam structure may have an inner connecting body that connects the inner beam and the fixed body.

In these cases, the presence of the coupling (or the outer and inner couplings) attenuates the vibrations that occur in the external environment and is transmitted to the beam structure. Therefore, the noise included in the electric signal output from the torque sensor is reduced or eliminated, and the torque can be measured with higher accuracy.

According to the present invention, the elastic deformation generated in the deformed body is amplified at the measurement point due to the presence of the beam structure, so that the torque can be detected with high accuracy and high sensitivity while being able to cope with a high load torque. A torque sensor can be provided.

Alternatively, according to the present invention, the presence of the inner beam structure and the outer beam structure amplifies the elastic deformation generated in the deformed body at the measurement point. It is possible to provide a torque sensor capable of detecting torque with high sensitivity.

It is a schematic plan view which shows the basic structure part of the torque sensor by one Embodiment of this invention. It is a schematic plan view which shows the basic structure part of the conventional torque sensor. It is a schematic diagram which shows the part located in the 1st quadrant of the deformed body of the basic structure part of FIG. FIG. 3A is a diagram corresponding to the initial state of the basic structural portion of FIG. 1, and FIG. 3B is a diagram corresponding to a negative torque acting on the basic structural portion of FIG. 3 (c) is a diagram corresponding to when a positive torque acts on the basic structure portion of FIG. It is a schematic diagram which shows the part located in the 1st quadrant of the deformed body of the basic structure part of FIG. FIG. 4A is a diagram corresponding to the initial state of the basic structure portion of FIG. 2, and FIG. 4B is a diagram corresponding to the case where a negative torque acts on the basic structure portion of FIG. 4 (c) is a diagram corresponding to when a positive torque acts on the basic structure portion of FIG. It is a chart which shows the displacement which occurs in the predetermined part collectively when the torque acts on the basic structure part shown in FIG. 1 and FIG. It is a schematic plan view which shows an example of the torque sensor which adopted the basic structure part of FIG. It is a schematic plan view which shows the basic structure part of the torque sensor by the 2nd Embodiment of this invention. It is a schematic diagram which shows the deformed body when a negative torque acts on the basic structure part of FIG. It is a schematic diagram which shows the deformed body when a positive torque acts on the basic structure part of FIG. It is a schematic plan view which shows an example of the torque sensor which adopted the basic structure part of FIG. It is a schematic plan view which shows the basic structure part of the torque sensor by the 3rd Embodiment of this invention. It is a schematic diagram which shows the deformed body when a negative torque acts on the basic structure part of FIG. It is a schematic diagram which shows the deformed body when a positive torque acts on the basic structure part of FIG. It is a schematic plan view which shows an example of the torque sensor which adopted the basic structure part of FIG. It is a schematic plan view which shows the modification of FIG. It is a schematic plan view which shows the other modification of FIG. It is a schematic plan view which shows still another modification of FIG. It is a schematic perspective view which shows the modification of the basic structure part. It is a schematic side view which shows the state which the electrode is arranged through an insulator.

<<< §1. Torque sensor according to the first embodiment of the present invention >>>
Hereinafter, the torque sensor according to the first embodiment of the present invention will be described in detail with reference to the accompanying drawings.

<1-1. Structure of basic structure ＞
FIG. 1 is a schematic plan view showing a basic structural portion 100 of a torque sensor according to the first embodiment of the present invention. Further, FIG. 2 is a basic structural portion 100a of the conventional torque sensor, and is a reference diagram for explaining the difference from FIG. 1.

In FIGS. 1 and 2, an XYZ three-dimensional coordinate system is defined, and the X-axis extends in the left-right direction, the Y-axis extends in the up-down direction, and the Z-axis (not shown) extends in the depth direction. It should be noted here that the X-axis extends from the left to the right. Further, on the XY plane, a V-axis that passes through the origin O and forms 45 ° clockwise with respect to the positive X-axis, and a W-axis that passes through the origin O and forms 45 ° clockwise with respect to the positive Y-axis. , Are defined respectively. It should be noted that such coordinate axes are similarly defined in other drawings. Further, in the present specification, the positive torque means the direction in which the right-hand screw is rotated in order to advance the right-hand screw in the Z-axis direction (direction from the front side to the back side) (clockwise in FIGS. 1 and 2). It means the torque acting in the direction of), and the negative torque means the torque acting in the opposite direction.

As shown in FIG. 1, the basic structural portion 100 surrounds the disk-shaped fixed body 10 fixed on the XY plane with the origin O as the center, and the fixed body 10 is subjected to the action of torque to form the fixed body 10. It is connected to the fixed body 10 and the receiving body 20 in the gap between the receiving body 20 that rotates relative to each other and the fixed body 10 and the receiving body 20, and is elastically deformed by the action of the torque transmitted from the receiving body 20. It has an annular deformed body 30 that produces the above.

As shown in FIG. 1, the fixed body 10 is a disk-shaped member centered on the origin O, and the receiving body 20 and the deformed body 30 are annular members centered on the origin. The fixed body 10 has fixed body connecting portions 11 and 12 protruding outward in the radial direction of the fixed body 10 at two portions on the outer peripheral surface that overlap with the Y axis. Further, the deformed body 30 has fixed portions 33 and 35 at a portion overlapping the Y-axis, and these fixed portions 33 and 35 and the fixed body connecting portions 11 and 12 are connected to each other. Further, as shown in FIG. 1, the receiving body 20 has the receiving body connecting portions 21 and 22 protruding inward in the radial direction of the receiving body 20 at two portions of the inner peripheral surface overlapping the X axis. have. The deformed body 30 has receiving portions 32 and 34 at a portion overlapping the X-axis, and these receiving portions 32 and 34 and the receiving body connecting portions 21 and 22 are connected to each other. Then, of the deformed body 30, the deformed portion 36 that connects the fixed portion 33 located on the positive Y-axis and the receiving portion 34 located on the negative X-axis is elastically deformed by the action of torque. It has become.

Of course, in the basic structural portion 100 shown in FIG. 1, all the portions (first to fourth quadrants) of the deformed body 30 that connect the fixed portions 33, 35 and the receiving portions 32, 34 that are adjacent in the circumferential direction are connected. Elastic deformation occurs due to the action of torque. However, since the beam structure 31 described later is arranged only in the deformed portion 36, attention is paid only to the elastic deformation generated in the deformed portion 36.

The conventional torque sensor (see FIG. 2) has the same configuration as the structure described above. Therefore, in FIG. 2, substantially the same reference numerals are given to the constituent parts common to those in FIG. 1, and detailed description thereof will be omitted.

The basic structure portion 100 according to the present embodiment is different from the conventional basic structure portion (see FIG. 2) in that the deformed body 30 has the beam structure 31. That is, as shown in FIG. 1, the basic structural portion 100 includes a support 31f connected to the outer peripheral surface of the deformed portion 36 and a beam 31b whose one end is supported by the support 31f. The beam structure 31 to have is provided. The beam 31b is defined with a measurement point P for measuring the displacement of the beam 31b. As shown in FIG. 1, the measurement point P is defined in the vicinity of the end of the beam 31b on the side opposite to the end connected to the support 31f. More specifically, the support 31f is connected to the deformed portion 36 in the region sandwiched by the positive V-axis and the positive X-axis, and the beam 31b connects the V-axis from the tip of the support 31f. It extends across. In the example shown in FIG. 1, the measurement point P is defined as a portion where the beam 31b and the V axis overlap.

<1-2. Action of basic structure>
Next, the operation of the basic structure unit 100 described above will be described with reference to FIGS. 3 and 4.

FIG. 3 is a schematic view showing a portion of the modified body 30 of the basic structural portion 100 of FIG. 1 located in the first quadrant. FIG. 3A is a diagram corresponding to the initial state of the basic structure portion 100 of FIG. 1, and FIG. 3B is a diagram corresponding to the case where a negative torque acts on the basic structure portion 100 of FIG. 3 (c) is a diagram corresponding to the case where a positive torque is applied to the basic structure portion 100 of FIG. Further, FIG. 4 is a schematic view showing a portion of the modified body 30a of the basic structural portion 100a of FIG. 2 located in the first quadrant. FIG. 4A is a diagram corresponding to the initial state of the basic structure portion 100a of FIG. 2, and FIG. 4B is a diagram corresponding to the case where a negative torque acts on the basic structure portion 100a of FIG. 4 (c) is a diagram corresponding to the case where a positive torque acts on the basic structure portion 100a of FIG. In FIGS. 3 and 4, the thickness and width of each component are ignored.

As shown in FIG. 3B, when a negative torque acts on the basic structural portion 100 of FIG. 1, the receiving portion 34 of the deformed body 30 located on the positive X-axis is moved downward. To. On the other hand, the fixed portion 33 of the deformed body 30 located on the positive Y-axis does not move. Therefore, a tensile force acts on the deformed portion 36, whereby the deformed portion 36 is elastically deformed so that the radius of curvature becomes large. In FIG. 3B, the solid line shows the deformed body 30 in the state of elastic deformation, and the broken line shows the deformed portion 36 in the initial state (see FIG. 3A). It should be noted that such an illustration is common to each of the figures of FIGS. 3 and 4.

Here, attention is paid to the tangent line of the deformed portion 36 at the connection point Q between the support 31f of the beam structure 31 and the deformed portion 36. The tangent line in the initial state is indicated by the symbol Lo in FIG. 3 (a), and the tangent line when a negative torque is applied is indicated by the symbol Lt in FIG. 3 (b). As described above, when a negative torque acts on the deformed body 30, the deformed portion 36 is elastically deformed so that the radius of curvature of the deformed portion 36 becomes large without the fixed portion 33 being displaced. Therefore, the tangent line Lt changes to a state of lying more horizontally than the tangent line Lo.

The support 31f of the beam structure 31 has a relationship orthogonal to the beam 31b and the tangents Lo and Lt. Therefore, the beam 31b and the tangents Lo and Lt are always maintained in a parallel state. Considering this, the displacement generated at the measurement point P of the beam 31b when a negative torque is applied to the deformed body 30 is the sum of the displacement generated at the connection point Q and the displacement caused by the change in the inclination of the tangent line Lt. It will be the amount of displacement. That is, the beam structure 31 amplifies the displacement generated at the connection point Q and appears at the measurement point P. In FIG. 3B, the displacement (displacement amount from the initial position Po to the position Pt after the displacement) that occurs at the measurement point P is indicated by the symbol dt. In an actual torque sensor, the displacement generated at the point Q due to the action of torque is about several tens to several hundreds of μm. Therefore, in FIG. 3B, the point P is shown as being displaced along the V axis. ..

Next, as shown in FIG. 3C, when a positive torque acts on the basic structural portion 100 of FIG. 1, the receiving portion 34 of the deformed body 30 located on the negative X-axis is moved upward. Moved to. On the other hand, the fixed portion 33 of the deformed body 30 located on the positive Y-axis does not move. Therefore, a compressive force acts on the deformed portion 36 along the direction of the applied torque, whereby the deformed body 30 is elastically deformed so that the radius of curvature becomes smaller.

Here, too, attention is paid to the tangent line of the deformed portion 36 at the connection point Q between the support 31f of the beam structure 31 and the deformed portion 36. The tangent line is indicated by the symbol Lc in FIG. 3 (b). As described above, when a positive torque acts on the deformed body 30, the deformed portion 36 is elastically deformed so that the radius of curvature of the deformed portion 36 becomes smaller without the fixed portion 33 being displaced. Therefore, the tangent line Lc is initially set. It changes to a more vertically standing state than the tangent line Lo of the state (see FIG. 3A).

The displacement generated at the measurement point P of the beam 31b when a positive torque is applied to the deformed body 30 is the sum of the displacement generated at the connection point Q and the displacement caused by the change in the inclination of the tangent line Lc, as in the previous case. It will be the amount of displacement. That is, the beam structure 31 amplifies the displacement generated at the connection point Q and appears at the measurement point P. In FIG. 3C, the displacement (displacement amount from the initial position Po to the position Pc after the displacement) that occurs at the measurement point P is indicated by the symbol dc. Again, in consideration of the magnitude of the displacement that occurs in the actual torque sensor, in FIG. 3C, the point P is shown as being displaced along the V axis.

For comparison, the elastic deformation that occurs in the deformed body 30a in the conventional torque sensor will be briefly described with reference to FIG. When a negative torque acts on the conventional torque sensor, as shown in FIG. 4 (b), the deformed portion 36a undergoes the same elastic deformation as the deformed portion 36 shown in FIG. 3 (b). On the other hand, when a positive torque acts on the conventional torque sensor, the deformed portion 36a undergoes the same elastic deformation as the deformed portion 36 shown in FIG. 3 (c) as shown in FIG. 4 (c).

The position where the radial displacement is maximum in the deformed portion 36a is the position where it intersects the V axis. Therefore, in the conventional torque sensor, the measurement point R is defined at a position intersecting the V axis, and the applied torque is detected based on the displacement of the measurement point R in the V axis direction. In FIG. 4B, the displacement of the measurement point R in the V-axis direction is indicated by the symbol dta, and in FIG. 4C, the displacement of the measurement point R in the V-axis direction is indicated by the symbol dca.

Next, FIG. 5 shows a predetermined portion when torque acts on the basic structure portion 100 (model 1) according to the present embodiment shown in FIG. 1 and the conventional basic structure portion 100a (model 2) shown in FIG. It is a chart which shows the result of FEM analysis (finite element analysis) of the displacement which occurs in. The predetermined portion is a reference defined in the basic structure portion 100 shown in FIG. 1 at a measurement point P defined by the beam 31b of the beam structure 31 and a portion where the deformed portion 36 intersects the positive V axis. It is a point R, and in the basic structure portion 100a shown in FIG. 2, it is a measurement point Ra defined at a position where the deformed body 30a intersects the positive V axis.

In FIG. 5, the displacement in the V-axis direction generated at the reference point R of the basic structure portion 100 (model 1) according to the present embodiment and the displacement in the V-axis direction generated at the measurement point Ra of the conventional basic structure portion 100a (model 2) Torque is applied to the basic structural portions 100 and 100a so that the displacement and the displacement are both the same as 253 μm (= dt2). At this time, the displacement in the V-axis direction generated at the measurement point P of the basic structure portion 100 (model 1) according to the present embodiment is 320 μm (= dt1). From this, it can be seen that the sensitivity of the basic structural portion (model 1) according to the present embodiment is 1.26 times higher than that of the conventional basic structural portion 100a (model 2).

In the basic structure portion 100 (model 1), the stress generated in the deformed body is different between the model 1 (190 MPa) and the model 2 (185 MPa) due to the influence that the beam structure 31 is provided in the deformed portion 36. Yes, but this is not a big difference. Further, FIG. 5 shows that the basic structure portion 100 according to the present embodiment is relatively more sensitive than the conventional basic structure portion 100a, and is an absolute value of the numerical value shown in the figure. Does not make sense. It should be noted that a structural design in which a stress of 190 MPa is generated in the deformed portion 36 is not preferable because it lacks mechanical reliability.

As described above, when a torque of the same magnitude acts due to the presence of the beam structure 31, the displacement generated at the measurement point P occurs at the displacement generated at the reference point R and at the measurement point Ra of the conventional basic structure unit 100. Greater than displacement. In other words, the presence of the beam structure 31 amplifies the elastic deformation that occurs in the deformed portion 36 at the measurement point P.

<1-3. Torque sensor that employs the basic structure according to this embodiment>
Next, FIG. 6 is a schematic plan view showing an example of the torque sensor 100c that employs the basic structure portion 100 of FIG.

As shown in FIG. 6, the torque sensor 100c is connected to the basic structure portion 100 shown in FIG. 1, the capacitance element C arranged in the beam structure 31 of the basic structure portion 100, and the capacitance element C. A detection circuit 40 that outputs an electric signal indicating the applied torque based on the elastic deformation generated in the deformed portion 36 of the deformed body 30 is provided.

As shown in FIG. 6, the capacitance element C includes a displacement electrode Em arranged so as to face the receiving body 20 at the measurement point P of the beam 31b, and a fixed electrode Ef arranged to face the displacement electrode Em. And is composed of. In the present embodiment, the fixed electrode Ef is arranged on the pedestal 23 provided on the inner peripheral surface of the receiving body 20. The pedestal 23 is for arranging the fixed electrodes Ef in parallel with the displacement electrodes Em at predetermined intervals. As shown in FIG. 6, since the pedestal 23 is formed with a surface parallel to the displacement electrode Em in the region facing the beam 31b, the fixed electrode Ef and the displacement electrode Em are parallel to each other (between the plates). (So that the distance is constant). Due to the arrangement of the electrodes as described above, the capacitance element C is formed on the positive V-axis.

The detection circuit 40 outputs an air signal indicating an electrically applied torque based on the displacement generated at the measurement point P of the beam 31b due to the elastic deformation of the deformed body 30. Specifically, the detection circuit 40 is connected to the capacitance element C by a predetermined electrical wiring (not shown). Further, the detection circuit 40 stores, for example, a table (not shown) in which the fluctuation amount of the capacitance value of the capacitance element C and the value of the applied torque are associated with each other. Then, when the detection circuit 40 detects the fluctuation of the capacitance value of the capacitance element C caused by the displacement of the measurement point P, the detection circuit 40 refers to the table and identifies the torque corresponding to the fluctuation amount. An electric signal indicating the torque is output.

Next, the principle of measuring torque using the torque sensor 100c as described above will be described.

When a negative torque (counterclockwise torque in FIG. 6) acts on the receiving body 20 of the torque sensor 100c, the receiving body 20 rotates counterclockwise with respect to the fixed body 10 in the Z-axis direction. .. As a result, the deformed portion 36 of the torque sensor 100c is elastically deformed as shown in FIG. 3 (b). That is, the measurement point P of the beam 31b is displaced inward in the radial direction by dt1 in the V-axis direction. As described above, this displacement dt1 is larger than the displacement of the reference point R (corresponding to the displacement of the measurement point R0 in FIG. 4B). Due to such displacement of the measurement point P, the displacement electrode Em constituting the capacitance element C moves inward in the radial direction. On the other hand, since the fixed electrode Ef is fixed to the inner peripheral surface of the receiving body 20, it does not move in the radial direction. From the above, when a negative torque acts on the torque sensor 100c, the separation distance between the electrodes Ef and Em constituting the capacitance element C increases, so that the capacitance value decreases.

On the other hand, when a positive torque (clockwise torque in FIG. 6) acts on the receiving body 20 of the torque sensor 100c, the receiving body 20 rotates clockwise with respect to the fixed body 10 in the Z-axis direction. .. As a result, the deformed portion 36 of the torque sensor 100c is elastically deformed as shown in FIG. 3 (c). That is, the measurement point P of the beam 31b is displaced outward by dc1 in the radial direction in the V-axis direction. As described above, this displacement dc1 is larger than the displacement of the reference point R (corresponding to the displacement of the measurement point R0 in FIG. 4C). Due to such displacement of the measurement point P, the displacement electrode Em constituting the capacitance element C moves outward in the radial direction. Therefore, when a positive torque acts on the torque sensor 100c, the separation distance between the electrodes Ef and Em constituting the capacitance element C decreases, so that the capacitance value increases.

Then, the detection circuit 40 detects the fluctuation amount of these capacitance values, and refers to the table stored in advance to specify the applied torque. Then, an electric signal corresponding to the specified torque is output from a predetermined output terminal (not shown).

According to the present embodiment as described above, since the elastic deformation generated in the deformed portion 36 at the measurement point P is amplified by the presence of the beam structure 31, it is possible to cope with a high load torque and to have high accuracy. Moreover, it is possible to provide a torque sensor 100c capable of detecting torque with high sensitivity.

The deformed portion 36 of the deformed body 30 has an annular shape surrounding the origin O when viewed from the Z-axis direction. Further, the fixed portion 33 of the deformed body 30 is positioned so as to overlap the Y-axis when viewed from the Z-axis direction, and the receiving portion 34 of the deformed body 30 overlaps with the X-axis when viewed from the Z-axis direction. It is positioned as. As a result, elastic deformation occurs more effectively in the deformed portion 36.

Further, since the measurement point P of the beam 31b is positioned on the V-axis (intermediate position between the fixed portion 33 and the receiving portion 34) forming 45 ° with respect to the positive X-axis, it occurs in the deformed portion 36. The elastic deformation can be efficiently detected as the displacement generated at the measurement point P of the beam 31b.

Further, the detection circuit 40 is composed of a displacement electrode Em arranged at the measurement point P of the beam 31b and a fixed electrode Ef arranged on the inner peripheral surface of the receiving body 20 so as to face the displacement electrode Em. It has a configured capacitance element C, and outputs an electric signal indicating the applied torque based on the amount of fluctuation of the capacitance value of the capacitance element C. Therefore, the applied torque can be easily detected.

<<< §2. Torque sensor according to the second embodiment of the present invention >>>
Next, the torque sensor 200c according to the second embodiment of the present invention will be described.

<2-1. Structure of basic structure ＞
FIG. 7 is a schematic plan view showing the basic structural portion 200 of the torque sensor according to the second embodiment of the present invention.

As shown in FIG. 7, the basic structure portion 200 has the same structure as the basic structure portion 100 according to the first embodiment shown in FIG. 1, except that four beam structures 231A to 231D are provided. Have. In the present embodiment, the deformed body 230 utilizes elastic deformation that occurs in the portions located in each of the first to fourth quadrants when viewed from the Z-axis direction. Therefore, as shown in FIG. 7, the portion of the first quadrant that connects the fixed portion 233 located on the positive Y-axis and the receiving portion 234 located on the positive X-axis of the deformed body 30 is provided. The first deformed portion 236A and the second quadrant portion connecting the receiving portion 232 located on the negative X-axis and the fixed portion 233 located on the positive Y-axis are referred to as the second deformed portion 236B and are negative. The third quadrant that connects the fixed portion 235 located on the Y-axis and the receiving portion 232 located on the negative X-axis is the third deformed portion 236C, and the receiving portion located on the positive X-axis. The following description will be given with the fourth quadrant portion connecting the 234 and the fixed portion 235 located on the negative Y axis as the fourth deformed portion 236D. In the basic structure unit 200 shown in FIG. 7, the same reference numerals are given to the components common to the basic structure unit 100 (see FIG. 1) according to the first embodiment, and detailed description thereof will be omitted.

In the basic structure portion 200 according to the present embodiment, all four beam structures are arranged on the outer peripheral surface of the deformed body 230. Specifically, the four beam structures include a first beam structure 231A arranged in the first deformed portion 236A, a second beam structure 231B arranged in the second deformed portion 236B, and a third deformed portion. It has a third beam structure 231C arranged in 236C and a fourth beam structure 231D arranged in the fourth beam structure 231D.

The first beam structure 231A has the same structure as the beam structure 31 of the basic structure portion 100 according to the first embodiment and is arranged at the same position. That is, the first beam structure 231A has a first support 231Af connected to the outer peripheral surface of the first deformed portion 236A, and a first beam 231Ab whose one end is supported by the first support 231Af. ing. The first beam 231Ab defines a first measurement point P1 for measuring the displacement of the first beam 231Ab at a position overlapping the positive V-axis when viewed from the Z-axis direction.

The remaining second to fourth beam structures 231B to 231D have the same structure as the first beam structure 231A, and differ only in the positions where they are arranged. That is, the second beam structure 231B is arranged at a position where the first beam structure 231A is rotated 90 ° clockwise, and is connected to the second support 231Bf connected to the outer peripheral surface of the first deformed portion 236B. It has a second beam 231Bb whose one end is supported by the second support 231Bf. The second beam 231Bb is defined with a second measurement point P2 for measuring the displacement of the second beam 231Bb at a position overlapping the positive W axis when viewed from the Z-axis direction.

The third beam structure 231C is arranged at a position where the second beam structure 231B is rotated 90 ° clockwise, and is connected to the outer peripheral surface of the third deformed portion 236C and the third support 231Cf. It has a third beam 231Cb whose one end is supported by the third support 231Cf. The third beam 231Cb is defined with a third measurement point P3 for measuring the displacement of the third beam 231Cb at a position overlapping the negative V axis when viewed from the Z-axis direction.

The fourth beam structure 231D is arranged at a position where the third beam structure 231C is rotated 90 ° clockwise, and is connected to the outer peripheral surface of the fourth deformed portion 236D and the fourth support 231Df. It has a fourth beam 231Db whose one end is supported by the fourth support 231Df. The fourth beam 231Db defines a fourth measurement point P4 for measuring the displacement of the fourth beam 231Db at a position overlapping the negative W axis when viewed from the Z-axis direction.

<2-2. Action of basic structure>
Next, the operation of the basic structure portion 200 described above will be described with reference to FIGS. 8 and 9.

FIG. 8 is a schematic view showing a deformed body 230 when a negative torque T− acts on the basic structure portion 200 of FIG. 7, and FIG. 9 shows a positive torque T + acting on the basic structure portion 200 of FIG. It is a schematic diagram which shows the deformed body 230 at the time of this. In FIGS. 8 and 9, the thickness and width of each component are ignored.

When a negative torque T-acts on the receiving body 20 of the basic structure portion 200, the torque T- is transmitted to the receiving portions 232 and 234 via the receiving body connecting portions 21 and 22. As a result, as shown in FIG. 8, both the receiving portions 232 and 234 are displaced counterclockwise. As a result, a tensile force acts on the first and third deformed portions 236A and 236C, so that the deformed portions 236A and 236C are elastically deformed so that the radius of curvature becomes large. On the other hand, since a compressive force acts on the second and fourth deformed portions 236B and 236D with the displacement of the receiving force portions 232 and 234, each deformed portion 236B and 236D are elastically deformed so that the radius of curvature becomes smaller. To do.

As shown in FIG. 8, the measurement point P1 of the first beam structure 231A and the measurement point P3 of the third beam structure 231C are both within the radial direction of the deformed body 230 due to the elastic deformation of the deformed body 230 as described above. Displace towards. On the other hand, the measurement point P2 of the second beam structure 231B and the measurement point P4 of the fourth beam structure 231D are both displaced outward in the radial direction of the deformed body 230. The magnitude of the displacement generated at each measurement point P1 to P4 is larger than the magnitude of the radial (V-axis direction or W-axis direction) displacement generated at each of the deformed portions 236A to 236D (the displacement generated at the deformed body 230 is amplified). Will be).

The principle that the radial displacement generated in each deformed portion 236A to 236D is amplified and appears at each measurement point P1 to P4 is described in the above 1-2. Can be understood by the description given in. This is because the first deformed portion 236A and the first beam structure 231A in FIG. 8 are the same as the deformed portion 36 and the beam structure 31 shown in FIG. 3 (b), and the second beam structure 231B is shown in FIG. 3 (c) is symmetrically moved with respect to the Y axis, and then the beam structure 31 is symmetrically moved with respect to the W axis. The fourth beam structure 231D is symmetrically moved with respect to the X axis. This is because the beam structure 31 is symmetrically moved with respect to the W axis, and the third beam structure 231C has a structure in which FIG. 3B is rotated 180 ° around the origin.

Next, when a positive torque T + acts on the receiving body 20 of the basic structure portion 200, both the receiving portions 232 and 234 are displaced clockwise as shown in FIG. As a result, a compressive force acts on the first and third deformed portions 236A and 236C, so that the deformed portions 236A and 236C are elastically deformed so that the radius of curvature becomes smaller. On the other hand, since a tensile force acts on the second and fourth deformed portions 236B and 236D with the displacement of the receiving force portions 232 and 234, each deformed portion 236B and 236D are elastically deformed so that the radius of curvature becomes large. To do.

As shown in FIG. 9, the measurement point P1 of the first beam structure 231A and the measurement point P3 of the third beam structure 231C are both outside the radial direction of the deformed body 30 due to the elastic deformation of the deformed body 230 as described above. Displace towards. On the other hand, the measurement point P2 of the second beam structure 231B and the measurement point P4 of the fourth beam structure 231D are both displaced inward in the radial direction of the deformed body 230. The magnitude of the displacement appearing at each of the measurement points P1 to P4 is larger (amplified) than the magnitude of the radial (V-axis direction or W-axis direction) displacement that occurs in each of the deformed portions 236A to 236D.

Also in this case, the principle that the radial displacement generated in each of the deformed portions 236A to 236D is amplified and occurs in each of the measurement points P1 to P4 is described in the above 1-2. Can be understood by the description given in. This is because the deformed body 230 of FIG. 9 is the same as the structure in which the deformed body 230 of FIG. 8 is symmetrically moved (reversed) with respect to the X axis, and the beam structures 231A to 231D are symmetrically moved with respect to the V axis or the W axis. That's why.

<2-3. Torque sensor that employs the basic structure according to this embodiment>
Next, FIG. 10 is a schematic plan view showing an example of a torque sensor 200c that employs the basic structure portion 200 of FIG. 7.

As shown in FIG. 10, the torque sensor 200c has four capacitances arranged one by one in the basic structure portion 200 shown in FIG. 7 and the beams 231Ab to 231Db of the beam structures 231A to 231D of the basic structure portion 200. A detection circuit that is connected to the capacitive elements C1 to C4 and these capacitive elements C1 to C4 and outputs an electric signal indicating the applied torque based on the elastic deformation generated in each deformed portion 236A to 236D of the deformed body 230. It is equipped with 240 and.

As shown in FIG. 10, the four capacitance elements are the first capacitance element C1 arranged in the first beam structure 231A and the second capacitance element arranged in the second beam structure 231B. The element C2, the third capacitance element C3 arranged in the third beam structure 231C, and the fourth capacitance element C4 arranged in the fourth beam structure 231D.

The first capacitance element C1 is arranged to face the first displacement electrode Em1 arranged so as to face the receiving body 20 at the first measurement point P1 of the first beam 231Ab, and to face the first displacement electrode Em1. It is composed of a first fixed electrode Ef1. Similarly, the second capacitance element C2 faces the second displacement electrode Em2 arranged so as to face the receiving body 20 at the second measurement point P2 of the second beam 231Bb and the second displacement electrode Em2. It is composed of a second fixed electrode Ef2 arranged. The third capacitance element C3 is arranged to face the third displacement electrode Em3 and the third displacement electrode Em3 arranged so as to face the receiving body 20 at the third measurement point P3 of the third beam 231Cb. It is composed of a third fixed electrode Ef3. The fourth capacitance element C4 is arranged to face the fourth displacement electrode Em4 and the fourth displacement electrode Em4 arranged so as to face the receiving body 20 at the fourth measurement point P4 of the fourth beam 231Db. It is composed of a fourth fixed electrode Ef4.

The first to fourth capacitance elements C1 to C4 have the same effective facing area of the electrodes constituting the respective capacitance elements C1 to C4, and the separation distances between the electrodes are all the same. ..

As shown in FIG. 10, the first fixed electrode Ef1 is arranged on the first pedestal 23A provided on the inner peripheral surface of the receiving body 20, and the second fixed electrode Ef2 is inside the receiving body 20. The third fixed electrode Ef3 is arranged on the second pedestal 23B provided on the peripheral surface, and the third fixed electrode Ef3 is arranged on the third pedestal 23C provided on the inner peripheral surface of the receiving body 20, and is fixed to the fourth. The electrode Ef4 is arranged on the fourth pedestal 23D provided on the inner peripheral surface of the receiving body 20. Since the pedestals 23A to 23D are formed with surfaces parallel to the displacement electrodes Em1 to Em4 in the region facing the beams 231Ab to 231Db, the displacement electrodes Em1 to Em4 corresponding to the fixed electrodes Ef1 to Ef4 are different from each other. , Are arranged parallel to each other (so that the distance between the plates is constant). Due to the arrangement of the electrodes as described above, the first capacitance element C1 is formed on the positive V-axis, the second capacitance element C2 is formed on the positive W-axis, and the third The capacitance element C3 is formed on the negative V-axis, and the fourth capacitance element C4 is formed on the negative W-axis.

The detection circuit 240 is connected to the first to fourth capacitance elements C1 to C4 by predetermined electrical wiring (not shown), and the first to fourth beams 231Ab to the first to fourth beams 231Ab due to the elastic deformation of the deformed body 230. An electric signal indicating the applied torque is output based on the displacement generated at each measurement point P1 to P4 of 231Db. Similar to the first embodiment, the detection circuit 240 is obtained by, for example, performing a predetermined calculation using each fluctuation amount of the capacitance values of the first to fourth capacitance elements C1 to C4. A table (not shown) in which the value to be obtained and the value of the applied torque are associated with each other is stored. When the detection circuit 240 detects the fluctuation of the capacitance value of the capacitance element C, the detection circuit 240 is adapted to specify the applied torque by referring to this table. Details of the specific measurement of torque will be described later.

Next, the principle of measuring torque using the torque sensor 200c as described above will be described.

When a negative torque (counterclockwise torque in FIG. 10) acts on the receiving body 20 of the torque sensor 200c, the receiving body 20 rotates counterclockwise with respect to the fixed body 10 in the Z-axis direction. .. As a result, the first to fourth deformed portions 236A to 236D of the torque sensor 200c are elastically deformed as shown in FIG. As a result, in the first capacitance element C1 and the third capacitance element C3, the separation distance between the electrodes constituting the respective capacitance elements C1 and C3 increases, so that the capacitance value decreases. .. On the other hand, in the second capacitance element C2 and the fourth capacitance element C4, the separation distance between the electrodes constituting the respective capacitance elements C2 and C4 decreases, so that the capacitance value increases.

On the other hand, when a positive torque (clockwise torque in FIG. 10) acts on the receiving body 20 of the torque sensor 200c, the receiving body 20 rotates clockwise with respect to the fixed body 10 in the Z-axis direction. .. As a result, the first to fourth deformed portions 236A to 236D of the torque sensor 200c are elastically deformed as shown in FIG. As a result, in the first capacitance element C1 and the third capacitance element C3, the separation distance between the electrodes constituting the respective capacitance elements C1 and C3 is reduced, so that the capacitance value is increased. .. On the other hand, in the second capacitance element C2 and the fourth capacitance element C4, the capacitance value decreases because the separation distance between the electrodes constituting the respective capacitance elements C2 and C4 increases. After all, when the direction of the torque acting on the receiving body 20 is reversed, the fluctuation (increase or decrease) of the capacitance values of the first to fourth capacitance elements C1 to C4 is also reversed.

In the present embodiment, as described above, the displacement generated at each measurement point P1 to P4 due to the presence of the first to fourth beam structures 231A to 231D is larger than the displacement generated at each deformed portion 236A to 236D. Therefore, the amount of fluctuation in the capacitance value of each of the capacitance elements C1 to C4 is larger than that of the conventional torque sensor in which the capacitance elements are directly arranged in the deformed portions 236A to 236D.

In view of the fluctuation of the capacitance value of the capacitance elements C1 to C4 as described above, the detection circuit 240 calculates the torque T around the Z axis acting on the torque sensor 200c using the following [Equation 1]. .. In [Equation 1], C1 to C4 indicate the amount of fluctuation in the capacitance value of the first to fourth capacitance elements C1 to C4.

[Equation 1]
T = C1-C2 + C3-C4
Then, the detection circuit 240 refers to the table stored in advance and identifies the applied torque from the value obtained based on [Equation 1]. Then, an electric signal corresponding to the specified torque is output from a predetermined output terminal (not shown).

According to the present embodiment as described above, the elastic deformation generated in the deformed portions 236A to 236D of the deformed body 230 is amplified at the measurement points P1 to P4 by the presence of the four beam structures 231A to 231D. Therefore, it is possible to provide a torque sensor 200c capable of detecting torque with high accuracy and high sensitivity while being able to handle torque of a high load.

Also in the present embodiment, the two fixing portions 233 and 235 are positioned symmetrically with respect to the Y axis at the portion where the deformed body 230 and the X axis overlap when viewed from the Z axis direction, and the two receiving portions 232 and 234 are , The portion where the deformed body 230 and the Y-axis overlap when viewed from the Z-axis direction is positioned symmetrically with respect to the X-axis. Further, each measurement point P1 to P4 is positioned on the positive W axis, the positive V axis, the negative W axis, and the negative V axis one by one. As a result, the elastic deformation generated in the first to fourth deformed portions 236A to 236D can be efficiently detected as the displacement generated in the measurement points P1 to P4 of the first to fourth beams 231Ab to 231Db.

Further, the detection circuit 240 of the present embodiment includes four displacement electrodes Em1 to Em4 arranged one at each measurement point P1 to P4 of the first to fourth beams 231Ab to 231Db, and these displacement electrodes Em1 to Em1. It has four sets of capacitance elements C1 to C4 composed of fixed electrodes Ef1 to Ef4 arranged opposite to Em4. Then, the detection circuit 240 is adapted to output an electric signal indicating the applied torque based on the above-mentioned [Equation 1]. Therefore, the applied torque can be easily detected, and the influence of forces other than the torque around the Z axis (forces in the X, Y, Z axial directions and torques around the X axis and the Y axis) can be detected. Only the torque around the Z axis can be detected without being affected by the temperature change in the usage environment.

<<< §3. Torque sensor according to the third embodiment of the present invention >>>
Next, the torque sensor 300c according to the third embodiment of the present invention will be described.

<3-1. Structure of basic structure ＞
FIG. 11 is a schematic plan view showing the basic structural portion 300 of the torque sensor according to the third embodiment of the present invention.

As shown in FIG. 11, the basic structure portion 300 has a second embodiment shown in FIG. 7, except that four beam structures 331E to 331H are also provided on the inner peripheral surface of the deformed body 330. It has the same structure as the basic structure part 200 according to the above. Therefore, in the basic structure unit 200 shown in FIG. 11, the components common to the basic structure unit 200 (see FIG. 1) according to the second embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. ..

However, for convenience of explanation, the beam structure common to the second embodiment, which is arranged on the outer peripheral surface of the deformed body 330, is replaced as follows. That is, the beam structure arranged in the first quadrant of the XY plane is referred to as the first outer beam structure 331A, and the beam structure arranged in the second quadrant of the XY plane is referred to as the second outer beam structure 331B. The beam structure arranged in the third quadrant is referred to as the third outer beam structure 331C, and the beam structure arranged in the fourth quadrant of the XY plane is referred to as the fourth outer beam structure 331D.

The basic structure portion 300 according to the present embodiment is arranged on the inner peripheral surface of the deformed body 330 in the first inner beam structure 331E and the second deformed portion 336B arranged in the first deformed portion 336A of the deformed body 330. Four beam structures, a second inner beam structure 331F, a third inner beam structure 331G arranged in the third deformed portion 336C, and a fourth inner beam structure 331H arranged in the fourth deformed portion 336D. Has additionally.

As shown in FIG. 11, one end of the first inner beam structure 331E is supported by the first inner support 331Ef connected to the inner peripheral surface of the first deformed portion 336A and the first inner support 331Ef. It has a first inner beam 331Eb. The first inner beam 331Eb extends parallel to the beam 331Ab of the first outer beam structure 331A. Further, the first inner beam 331Eb is defined with a measurement point P21 for measuring the displacement of the first inner beam 331Eb at a position overlapping the positive V-axis when viewed from the Z-axis direction.

Further, as shown in FIG. 11, the connection portion between the first inner support 331Ef and the deformed body 330 is deformed from the first outer support 331Af of the first outer beam structure 331A in the circumferential direction of the deformed body 330. It is the same as the connection site with the body 330. As shown in FIG. 11, the same thing can be said between the second to fourth inner beam structures 331F to 331H and the corresponding second to fourth outer beam structures 331B to 331D. It holds.

The second inner beam structure 331F includes a second inner support 331Ff connected to the inner peripheral surface of the second deformed portion 336B, and a second inner beam 331Fb whose one end is supported by the second inner support 331Ff. have. The connection portion between the second inner support 331Ff and the deformed body 330 is the same as the connection portion between the second inner support 331Bf and the deformed body 330 of the second outer beam structure 331B in the circumferential direction of the deformed body 330. is there. The second inner beam 331Fb extends parallel to the beam 331Bb of the second outer beam structure 331B. Further, the second inner beam 331Fb is defined with a measurement point P22 for measuring the displacement of the second inner beam 331Fb at a position overlapping the positive W axis when viewed from the Z-axis direction.

The third inner beam structure 331G includes a third inner support 331Gf connected to the inner peripheral surface of the third deformed portion 336C, and a third inner beam 331Gb whose one end is supported by the third inner support 331Gf. have. The connection portion between the third inner support 331Gf and the deformed body 330 is the same as the connection portion between the third inner support 331Cf and the deformed body 330 of the third outer beam structure 331C in the circumferential direction of the deformed body 330. is there. The third inner beam 331Gb extends parallel to the beam 331Cb of the third outer beam structure 331C. Further, the third inner beam 331Gb is defined with a measurement point P23 for measuring the displacement of the third inner beam 331Gb at a position overlapping the negative V axis when viewed from the Z-axis direction.

Further, the fourth inner beam structure 331H has a fourth inner support 331Hf connected to the inner peripheral surface of the fourth deformed portion 336D and a fourth inner beam 331Hb whose one end is supported by the fourth inner support 331Hf. And have. The connection portion between the fourth inner support 331Hf and the deformed body 330 is the same as the connection portion between the fourth inner support 331Df and the deformed body 330 of the fourth outer beam structure 331D in the circumferential direction of the deformed body 330. is there. The fourth inner beam 331Hb extends parallel to the beam 331Db of the fourth outer beam structure 331D. Further, the fourth inner beam 331Hb is defined with a measurement point P24 for measuring the displacement of the fourth inner beam 331Hb at a position overlapping the negative W axis when viewed from the Z-axis direction.

In the present embodiment, the first to fourth inner beam structures 331E to 331H have the same structure as each other, and only the mounting positions are different.

After all, in the example shown in FIG. 11, the connection portions between the first to fourth outer beam structures 331A to 331D and the corresponding deformed portions 336A to 336D correspond to the first to fourth inner beam structures 331E to 331H. The connection portions with the deformed portions 336E to 336H are arranged at the same positions in the circumferential direction of the deformed body 330. Further, in the example shown in FIG. 11, the first to fourth outer beams 331Ab to 331Db and the corresponding first to fourth inner beams 331EAb to 331Hb are parallel to each other.

Of course, the present invention is not limited to such a form, and in other embodiments, the connecting portion between the first to fourth inner beam structures 331E to 331H and the corresponding deformed portions 336E to 336H is the deformed body 330. They may be arranged at different positions in the circumferential direction. Further, the first to fourth outer beams 331Ab to 331Db and the corresponding first to fourth inner beams 331EAb to 331Hb may be non-parallel to each other.

<3-2. Action of basic structure>
Next, the operation of the basic structure unit 300 described above will be described with reference to FIGS. 12 and 13.

FIG. 12 is a schematic view showing a deformed body 330 when a negative torque T- is applied to the basic structure portion 300 of FIG. 11, and FIG. 13 is a positive view of the basic structure portion 300 of FIG. It is a schematic diagram which shows the deformed body 330 when the torque T + acts. In FIGS. 12 and 13, the thickness and width of each component are ignored.

When a negative torque T- is applied to the receiving body 20 of the basic structure portion 300, the deformed body 330 is elastically deformed in the same manner as the basic structure portion 200 according to the second embodiment shown in FIG. As described above, the first to fourth outer beam structures 331A to 331D arranged on the outer peripheral surface of the deformed body 330 are the same as the first to fourth beam structures 231A to 231D shown in FIG. Therefore, the first to fourth outer beam structures 331A to 331D exhibit the same behavior as the first to fourth beam structures 231A to 231D due to the elastic deformation of the deformed body 330. That is, as shown in FIG. 12, the measurement points P11 and P13 of the first and third outer beam structures 331A and 331C are both substantially inward in the radial direction of the deformed body 330 along the V axis. Displace. On the other hand, the measurement points P12 and P14 of the second and fourth outer beam structures 331B and 331D are both substantially displaced outward in the radial direction of the deformed body 330 along the W axis.

Next, the behaviors of the first to fourth inner beam structures 331E to 331H are as follows. First, as described above, the first inner beam structure 331E is configured such that the first inner beam 331Eb and the first beam 331Ab of the first outer beam structure 331A are parallel to each other. From this, the measurement point P21 of the first inner beam 331E is substantially displaced inward in the radial direction of the deformed body 330 along the V axis, similarly to the measurement point P11 of the first beam 331Ab. Further, the second to fourth inner beam structures 331F to 331H are configured such that the inner beams 331Fb to 331Hb are parallel to the beams 331Bb to 331Db of the corresponding outer beam structures 331B to 331D. From these facts, the measurement points P22 to P24 of the second to fourth inner beams 331F to 331H are displaced in the same direction as the measurement points P12 to P14 of the corresponding outer beam structures 331B to 331D. That is, the measurement points P22 and P24 of the second and fourth inner beams 331Fb and 331Hb are displaced outward in the radial direction of the deformed body 330 along the W axis, and the measurement points P23 of the third inner beam 331Gb are the V axis. Displaces inward in the radial direction along.

The magnitude of the displacement occurring at the measurement points P21 to P24 of the first to fourth inner beams 331Eb to 331Hb is larger than the magnitude of the displacement in the radial direction (V-axis direction or W-axis direction) occurring in the deformed portions 336A to 336D. , Large (displacement generated in the deformed body 330 is amplified). This is because the magnitude of the displacement that occurs at each measurement point P11 to P14 of the first to fourth outer beams 331Ab to 331Db is the displacement in the radial direction (V-axis direction or W-axis direction) that occurs in each of the deformed portions 336A to 336D. For the same reason that it is larger than the size. This is because each of the inner beam structures 331E to 331H has a structure in which the outer beam structures 331A to 331D are inverted with respect to the tangent line at the connection points Q1 to Q4 (see FIG. 8) with the deformed body 330. Because there is. However, the lengths of the inner beams 331Eb to 331Hb do not necessarily have to match the lengths of the beams 331Ab to 331Db of the corresponding outer beam structures 331A to 331D.

Next, when a positive torque T + acts on the receiving body 20 of the basic structure portion 300, both the receiving portions 332 and 334 are displaced clockwise as shown in FIG. As a result, the deformed body 330 is elastically deformed in the same manner as the basic structural portion 200 according to the second embodiment shown in FIG. Since the first to fourth outer beam structures 331A to 331D arranged on the outer peripheral surface of the deformed body 330 are the same as the first to fourth beam structures 231A to 231D shown in FIG. 9, the deformed body 330 Due to the elastic deformation, it exhibits the same behavior as the first to fourth beam structures 231A to 231D. That is, as shown in FIG. 13, the measurement points P11 and P13 of the first and third outer beam structures 331A and 331C are both substantially displaced outward in the radial direction of the deformed body 330 along the W axis. To do. On the other hand, the measurement points P12 and P14 of the second and fourth outer beam structures 331B and 331D are both substantially displaced inward in the radial direction of the deformed body 330 along the V axis. Also in this case, the magnitude of the displacement occurring at each measurement point P21 to P24 is larger than the magnitude of the radial (V-axis direction or W-axis direction) displacement occurring at each of the deformed portions 336A to 336D (to the deformed body 330). The resulting displacement is amplified).

<3-3. Torque sensor that employs the basic structure according to this embodiment>
Next, FIG. 14 is a schematic plan view showing an example of the torque sensor 300c that employs the basic structure portion 300 of FIG.

As shown in FIG. 14, eight torque sensors 300c are arranged in the basic structure portion 300 shown in FIG. 11 and in each of the beams 331Ab to 331Hb of the eight beam structures 331A to 331H of the basic structure portion 300. It is connected to the capacitance elements C11 to C24 and these capacitance elements C11 to C24, and outputs an electric signal indicating the applied torque based on the elastic deformation generated in each of the deformed portions 336A to 336D of the deformed body 330. It includes a detection circuit 340 and.

As shown in FIG. 14, the eight capacitance elements are the first outer capacitance element C11 arranged in the first outer beam structure 331A and the second outer capacitance element C11 arranged in the second outer beam structure 331B. The outer capacitance element C12, the third outer capacitance element C13 arranged in the third outer beam structure 331C, the fourth outer capacitance element C14 arranged in the fourth beam structure 331D, and the first 1 First inner capacitance element C21 arranged in the inner beam structure 331E, second inner capacitance element C22 arranged in the second inner beam structure 331F, and arranged in the third inner beam structure 331G. The third inner capacitance element C23 and the fourth inner capacitance element C24 arranged in the fourth inner beam structure 331H.

Of these eight capacitance elements, the first to fourth outer capacitance elements C11 to C14 arranged outside the deformed body 330 are the first arranged in the torque sensor 200c according to the second embodiment. It has the same configuration as the fourth capacitance elements C1 to C4. However, for convenience of explanation, for each of the electrodes constituting the first to fourth outer capacitance elements C11 to C14, the displacement electrode is referred to as the outer displacement electrode Em11 to Em14, and the fixed electrode is referred to as the outer fixed electrode Ef11 to Ef14. And.

Regarding the first to fourth inner capacitance elements C21 to C24 arranged inside the deformed body 330, the first inner capacitance element C21 faces the fixed body 10 at the measurement point P21 of the first inner beam 331Eb. It is composed of a first inner displacement electrode Em21 arranged in such a manner and a first inner fixed electrode Ef21 arranged to face the first inner displacement electrode Em21. Similarly, the second inner capacitance element C22 is attached to the second inner displacement electrode Em22 and the second inner displacement electrode Em22 arranged so as to face the fixed body 10 at the measurement point P22 of the second inner beam 331Fb. It is composed of a second inner fixed electrode Ef22 arranged to face each other. The third inner capacitance element C23 is arranged to face the third inner displacement electrode Em23 and the third inner displacement electrode Em23 arranged so as to face the fixed body 10 at the measurement point P23 of the third inner beam 331Gb. It is composed of a third inner fixed electrode Ef23. The fourth inner capacitance element C24 is arranged to face the fourth inner displacement electrode Em24 and the fourth inner displacement electrode Em24 arranged so as to face the fixed body 10 at the measurement point P24 of the fourth inner beam 331Hb. It is composed of a fourth inner fixed electrode Ef24.

Similar to the torque sensor 200c according to the second embodiment, the first to fourth outer capacitance elements C11 to C14 have all the effective facing areas of the electrodes constituting the outer capacitance elements C11 to C14. They are the same, and the separation distances between the electrodes are all the same. Further, in the first to fourth inner capacitance elements C21 to C24, the effective facing areas of the electrodes constituting the inner capacitance elements C21 to C24 are all the same, and the separation distances between the electrodes are all the same. ing.

As shown in FIG. 14, the first outer fixed electrode Ef11 is arranged on the first pedestal 23A provided on the inner peripheral surface of the receiving body 20, and the second outer fixed electrode Ef12 is the receiving body 20. The third outer fixed electrode Ef13 is arranged on the second pedestal 23B provided on the inner peripheral surface of the receiving body 20, and the third outer fixed electrode Ef13 is arranged on the third pedestal 23C provided on the inner peripheral surface of the receiving body 20. The fourth outer fixed electrode Ef14 is arranged on the fourth pedestal 23D provided on the inner peripheral surface of the receiving body 20. As shown in FIG. 14, each of the pedestals 23A to 23D is formed with a surface parallel to the outer displacement electrodes Em11 to Em14 in the region facing the outer beams 231Ab to 231Db, so that the outer fixed electrodes Ef11 to 1 The outer displacement electrodes Em11 to Em14 corresponding to Ef14 are arranged in parallel with each other (so that the distance between the plates is constant). Due to the arrangement of the electrodes as described above, the first outer capacitance element C11 is formed on the positive V axis, and the second outer capacitance element C12 is formed on the positive W axis. The third outer capacitance element C13 is formed on the negative V-axis, and the fourth outer capacitance element C14 is formed on the negative W-axis.

Further, the first inner fixed electrode Ef21 is arranged on the first inner pedestal 13A provided on the outer peripheral surface of the fixed body 10, and the second inner fixed electrode Ef22 is provided on the outer peripheral surface of the fixed body 10. The third inner fixed electrode Ef23 is arranged on the second inner pedestal 13B, the third inner fixed electrode Ef23 is arranged on the third inner pedestal 13C provided on the outer peripheral surface of the fixed body 10, and the fourth inner fixed electrode Ef24 is arranged. It is arranged on the fourth inner pedestal 14C provided on the outer peripheral surface of the fixed body 10. As shown in FIG. 14, each inner pedestal 13A to 13D is formed with a surface parallel to each inner displacement electrode Em21 to Em24 in a region facing the inner beams 331Eb to 331Hb, so that each inner fixed electrode Ef21 ~ Ef24 and the corresponding inner displacement electrodes Em21 to Em24 are arranged in parallel with each other (so that the distance between the plates is constant). Due to the arrangement of the electrodes as described above, the first inner capacitance element C21 is formed on the positive V-axis, and the second inner capacitance element C22 is formed on the positive W-axis. The third inner capacitance element C23 is formed on the negative V-axis, and the fourth inner capacitance element C24 is formed on the negative W-axis.

The detection circuit 340 is connected to the first to fourth outer capacitance elements C11 to C14 and the first to fourth inner capacitance elements C21 to C24 by predetermined electrical wiring (not shown). Then, the detection circuit 340 has displacements generated at the measurement points P11 to P14 of the first to fourth outer beams 331Ab to 331Db due to the elastic deformation of the deformed body 330, and the first to fourth inner beams 331Eb. An electric signal indicating the applied torque is output based on at least one of the displacements generated at the respective measurement points P21 to P24 of ~ 331Hb. In the detection circuit 340, for example, a value obtained by performing a predetermined calculation described later using each fluctuation amount of the capacitance value of the first to fourth outer capacitance elements C11 to C14, and an action. A predetermined table (not shown) associated with the torque value and the fluctuation amount of the capacitance value of the first to fourth inner capacitance elements C21 to C24, which will be described later, will be used. A table (not shown) in which the value obtained by performing the calculation and the value of the acting torque are associated with each other is stored. When the detection circuit 340 detects the amount of fluctuation in the capacitance value of each of the capacitance elements C11 to C24, the detection circuit 340 identifies the applied torque by referring to this table.

Next, the principle of measuring torque using the torque sensor 300c as described above will be described.

When a negative torque (counterclockwise torque in FIG. 14) acts on the receiving body 20 of the torque sensor 300c, the receiving body 20 rotates counterclockwise with respect to the fixed body 10 in the Z-axis direction. .. As a result, the first to fourth deformed portions 336A to 336D of the torque sensor 300c are elastically deformed as shown in FIG. As a result, in the first outer capacitance element C11, the third outer capacitance element C13, the second inner capacitance element C22, and the fourth inner capacitance element C24, the respective capacitance elements C11 and C13 , C22, and C24 increase the distance between the electrodes, so that the capacitance value decreases. On the other hand, in the second outer capacitance element C12, the fourth outer capacitance element C14, the first inner capacitance element C21 and the third inner capacitance element C23, the respective capacitance elements C12, C14, C21 , The capacitance value increases because the separation distance between the electrodes constituting C23 decreases.

On the other hand, when a positive torque (clockwise torque in FIG. 14) acts on the receiving body 20 of the torque sensor 300c, the receiving body 20 rotates clockwise with respect to the fixed body 10 in the Z-axis direction. .. As a result, the first to fourth deformed portions 336A to 336D of the torque sensor 300c are elastically deformed as shown in FIG. As a result, in the first outer capacitance element C11, the third outer capacitance element C13, the second inner capacitance element C22, and the fourth inner capacitance element C24, the respective capacitance elements C11 and C13 , C22, the separation distance between the electrodes constituting C24 is reduced, so that the capacitance value is increased. On the other hand, in the second outer capacitance element C12, the fourth outer capacitance element C14, the first inner capacitance element C21 and the third inner capacitance element C23, the respective capacitance elements C12, C14, C21 , The capacitance value decreases because the separation distance between the electrodes constituting C23 increases. After all, when the direction of the torque acting on the receiving body 20 is reversed, the fluctuation (increase or decrease) of the capacitance value of each capacitance element C11 to C24 is also reversed.

In the present embodiment, as described above, the displacement generated at the measurement points P11 to P24 due to the presence of the beam structures 331A to 331H is larger than the displacement generated at the deformed portions 336A to 336D. Therefore, the fluctuation amount of the capacitance value of each of the capacitance elements C11 to C24 is large as compared with the conventional torque sensor in which the capacitance element is directly arranged on each of the deformed portions 336A to 336D.

In view of the fluctuation of the capacitance value of the capacitance elements C11 to C24 as described above, the detection circuit 340 acted on the torque sensor 200c by using either T1 or T2 shown in the following [Equation 2]. The torque T around the Z axis is calculated. T1 is an equation for measuring the torque T acted by using the outer capacitance elements C11 to C14, and T2 is an equation for measuring the torque acted by using the inner capacitance elements C21 to C24. Is. Further, in [Equation 2], C11 to C24 indicate the amount of fluctuation in the capacitance value of the first to fourth outer capacitance elements C11 to C14 and the first to fourth inner capacitance elements C21 to C24. ing.

[Equation 2]
T1 = C11-C12 + C13-C14
T2 = C21-C22 + C23-C24
Alternatively, instead of [Equation 2], the acting torque can be measured using the following [Equation 3]. This [Equation 3] is the sum of T1 and T2 shown in [Equation 2].

[Equation 3]
T3 = (C11 + C21)-(C12 + C22) + (C13 + C13)-(C14 + C24)
Then, the detection circuit 340 refers to the table stored in advance and identifies the applied torque from the values obtained based on [Equation 2] or [Equation 3]. Then, an electric signal corresponding to the specified torque is output from a predetermined output terminal (not shown).

Further, the torque sensor 300c according to the present embodiment can also diagnose whether or not the torque sensor 300c is functioning normally as follows. That is, as shown in [Equation 2], the torque sensor 300c includes the four capacitance elements C11 to C14 of the first to fourth outer capacitance elements and the first to fourth inner capacitance elements C21 to C21. It is possible to measure the torque acted by using any of the four capacitance elements of C24. Therefore, when the torque sensor 300c is functioning normally, the torque value measured based on T1 shown in [Equation 2] and the torque value measured based on T2 are substantially equal to each other. It will be the same value. On the other hand, when the torque sensor 300c is not functioning normally, the torque value measured based on T1 shown in [Equation 2] and the torque value measured based on T2 are substantially equal to each other. It will be a different value.

Based on this, when the difference (T1-T2) between the torque value measured based on T1 and the torque value measured based on T2 exceeds a predetermined threshold value, the torque sensor 300c normally operates. It can be determined that it is not functioning (it is out of order). In the present embodiment, the predetermined threshold value is stored in the detection circuit 340 in advance.

According to the present embodiment as described above, the elastic deformation generated in the deformed body 330 is measured by the presence of the first to fourth outer beam structures 331A to 331D and the first to fourth inner beam structures 331E to 331H. It is amplified at points P11 to P24. Therefore, it is possible to provide a torque sensor 300c capable of detecting torque with high accuracy and high sensitivity while being able to handle torque of a high load.

Also in this embodiment, the two fixing portions 333 and 335 are positioned X-axis symmetrically at the portion where the deformed body 330 and the Y axis overlap when viewed from the Z-axis direction, and the two receiving portions 332 and 334 are located. Is positioned symmetrically with respect to the Y axis at a portion where the deformed body 330 and the X axis overlap when viewed from the Z axis direction. Therefore, elastic deformation can be effectively generated in each of the deformed portions 336A to 336D.

Further, each measurement point P11 to P14 of the four outer beam structures 331A to 331D is positioned one by one on the positive V axis, the positive W axis, the negative V axis, and the negative W axis. The measurement points P21 to P24 of the four inner beam structures 331E to 331H are also positioned one on the positive V axis, one on the positive W axis, one on the negative V axis, and one on the negative W axis. There is. Therefore, at the measurement points P11 to P24, the elastic deformation that occurs in the corresponding deformation portions 336A to 336D can be efficiently amplified.

The detection circuit 340 of the present embodiment outputs an electric signal indicating the applied torque based on at least one of T1 and T2 shown in [Equation 2]. Therefore, regardless of which of the equations T1 and T2 is used, the applied torque can be easily detected, and the force other than the torque around the Z axis (force in the X, Y, Z axis direction or X, Z) can be detected. The desired torque can be detected without being affected by the torque around the shaft) or the temperature change in the usage environment.

Further, the detection circuit 340 includes the torque T1 measured based on the fluctuation amount of the capacitance value of the first to fourth outer capacitance elements C11 to C14 and the first to fourth inner capacitance elements C21 to By comparing with the torque measured based on the fluctuation amount of the capacitance value of C24, it is determined whether or not the torque sensor 300c is functioning normally. Therefore, in addition to detecting the applied torque, the failure diagnosis can be performed by a single torque sensor 300c.

<<< §4. Deformation example of beam structure in each embodiment >>>
In each of the above-described embodiments, the beam structure is configured as a so-called cantilever. Since one end of the cantilever beam is a free end, the resonance frequency of the cantilever beam is lower than that of the double-sided beam, and the cantilever beam is easily affected by external vibration. For example, when the torque sensors 100c, 200c, and 300c according to each embodiment are directly connected to the motor, there is a possibility that each beam structure (cantilever) and the frequency of the motor (several KHz) match. In addition, the beam structure is also affected by vibrations that occur in the external environment. In this case, the vibration generated in the beam structure provided in the torque sensors 100c, 200c, and 300c is added to the electric signal output as noise. That is, due to the influence of vibration generated in the environment in which the torque sensors 100c, 200c, and 300c are installed, the outputs of the torque sensors 100c, 200c, and 300c also vibrate, and the acting torque may not be accurately detected.

As one of the solutions to such a problem, it is effective to configure the beam structure with double-sided beams as shown in FIGS. 15 and 16.

FIG. 15 is a schematic plan view showing a modified example of FIG. 10, and FIG. 16 is a schematic plan view showing another modified example of FIG. Here, a modified example of FIG. 10 (second embodiment) will be mainly described, but similar structures are shown in FIGS. 6 (first embodiment) and 14 (third embodiment). Can also be adopted.

As shown in FIG. 15, the torque sensor 201c according to the present modification has connecting bodies 231Ac to 231Dc for connecting the tips of the beams 231Ab to 231Db of the beam structures 231A to 231D and the fixed body 10 or the receiving body 20. This is different from the torque sensor 200c according to the second embodiment.

Specifically, the fixed body 10 is connected to the fixed body connecting portion 11 located on the positive Y-axis with the first extending portion 11e extending in the positive direction of the Y-axis via the fixed portion 233 of the deformed body 230. The fixed body connecting portion 12 located on the negative Y-axis has a second extending portion 12e extending in the negative direction of the Y-axis via the fixed portion 235 of the deformed body 230. A predetermined gap exists between the tips of the extending portions 11e and 12e and the inner peripheral surface of the receiving body 20. Then, as shown in FIG. 15, the tip of the beam 231Ab of the first beam structure 231A and the first extending portion 11e are connected by a flexible first connecting body 231Ac. Further, the tip of the beam 231Bb of the second beam structure 231B and the receiving body connecting portion 21 are connected by the flexible second connecting body 231Bc, and the tip of the beam 231Cb of the third beam structure 231C and the second extension The protruding portion 12e is connected by a flexible third connecting body 231Cc, and the tip of the beam 231Db of the fourth beam structure 231D and the receiving body connecting portion 22 are connected by a flexible fourth connecting body 231Dc. ..

Alternatively, as shown in FIG. 16, instead of the extending portions 11e and 12e, the first protruding portion 24 projecting radially inward to two portions of the inner peripheral surface of the receiving body 20 located on the Y axis. And the second protruding portion 25 may be provided. In this case, one end of the first connecting body 231Ac is connected to the first protruding portion 24 instead of the first extending portion 11e, and one end of the third connecting body 231Cc is replaced with the second extending portion 12e. It may be connected to 25.

According to the torque sensors 201c and 202c having the beam structure with the double-sided beam as described above, the vibration generated in the external environment is attenuated by the presence of the connecting bodies 231Ac to 231Dc and transmitted to the beam structures 231A to 231D. It will be. Therefore, noise contained in the electric signals output from the torque sensors 201c and 202c is reduced or eliminated, and the torque can be measured with higher accuracy.

When the structure with the double-sided beam as described above is adopted for the torque sensor 100c (see FIG. 6) according to the first embodiment, the torque sensor 201c shown in FIG. 15 or the torque sensor 202c shown in FIG. 16 The structure shown in the first quadrant of the above may be adopted. Further, when the structure having the double-sided beam as described above is adopted for the torque sensor 300c (see FIG. 14) according to the third embodiment, the first to fourth outer beam structures 331A to 331D are shown in FIG. The same structure as the torque sensor 201c shown in FIG. 16 or the torque sensor 202c shown in FIG. 16 can be adopted. For the remaining first to fourth inner beam structures 331E to 331H, for example, the tips of the first and third inner beams 331Eb and 331Gb and the fixed body connecting portions 11 and 12 are connected by a flexible connecting body, respectively. The tips of the second and fourth inner beams 331Fb and 331Hb and the fixed body 10 may be connected by a flexible connecting body.

<<< §4. Ingenuity to keep the effective facing area between the plates constant >>>
Each of the above torque sensors is static so that the effective facing area of the pair of electrodes constituting the capacitance element does not change even when the relative position of the displacement electrode with respect to the fixed electrode changes as a result of the torque acting. It is also conceivable to set the area of one of the fixed electrode and the displacement electrode constituting the capacitance element to be larger than the area of the other. This is the case where the contour of the electrode having a smaller area (for example, a displacement electrode) is projected onto the surface of the electrode having a larger area (for example, a fixed electrode) in the normal direction of the electrode to form a normal projection image. , The projected image of the electrode having the smaller area is completely included in the surface of the electrode having the larger area. If this state is maintained, the effective area of the capacitance element composed of both electrodes becomes equal to the area of the smaller electrode and is always constant. That is, the force detection accuracy can be improved.

In each of the embodiments and modifications described so far, the area of the fixed electrode is larger than the area of the displacement electrode, as shown in the corresponding drawings.

<<< §5. Other variants >>>
In each of the above-described embodiments and modifications, the receiving body 20 is a fixed body fixed to the XYZ three-dimensional coordinate system, and the fixed body 10 is configured as a receiving body that can rotate around the Z axis. It is also possible to do. When a positive torque acts on the receiving body of such a torque sensor (corresponding to the fixed body 10 in each of the above embodiments and modifications), the deformed bodies 30, 230, and 330 are subjected to the above embodiments. In each torque sensor according to the deformation example, elastic deformation similar to the case where a negative torque acts on the receiving body 20 occurs. On the other hand, when a negative torque acts on the receiving body of such a torque sensor, the deformed bodies 30, 230, and 330 are positive to the receiving body 20 in each of the torque sensors according to the above embodiments and modifications. The same elastic deformation occurs when the torque of. Therefore, when the torque is measured by this torque sensor, T, T1, T2 and T3 should be read as -T, -T1, -T2 and -T3 in the above-mentioned [Equation 1] to [Equation 3], respectively. Just do it.

Next, FIG. 17 is a schematic plan view showing the torque sensor 203c according to still another modification of FIG. 10. As shown in FIG. 17, this modification is different from the example of FIG. 10 in that the pedestals 23Ac to 23Dc supporting the fixed electrodes Ef1 to Ef4 are arranged apart from the receiving body 20. In this modification, the pedestals 23Ac to 23Dc extend from the front side to the back side of FIG. 17, and the end portion on the back side is connected to the fixed body 10. As a result, the pedestals 23Ac to 23Dc do not move with respect to the fixed body 10. In the torque sensor 200c shown in FIG. 10, the pedestals 23Ac to 23Dc are arranged on the inner surface of the receiving body 20.

Therefore, when a force other than the torque around the Z axis (for example, a force in the X-axis direction and a force in the Y-axis direction) acts on the receiving body 20, each of the fixed electrodes Ef1 to Ef4 moves in the Z-axis direction and / It moves in the Y-axis direction. On the other hand, in the torque sensor 203c shown in FIG. 17, a force other than the torque around the Z axis (for example, a force in the X-axis direction and a force in the Y-axis direction) acts on the receiving body 20 to cause the receiving body 20 to act. Even if the center position does not coincide with the origin O when viewed from the Z-axis direction, the fixed electrodes Ef1 to Ef4 will not be displaced due to the influence thereof. As a result, the torque sensor shown in FIG. 17 can measure the applied torque more stably.

Of course, such an arrangement of the pedestal is relative to the torque sensor 100c (see FIG. 6), the torque sensors 200c to 202c (see FIGS. 10, 15 and 16) and the torque sensor 300c (see FIG. 14) described so far. Even if it can be applied.

Alternatively, in each of the above-described embodiments and modifications, the fixed body 10 and the receiving body 20 are arranged concentrically on the XY plane, but as shown in FIG. 18, the deformed body 30 is arranged in the Z-axis direction. , 230, 330 may be arranged so as to sandwich them. In FIG. 18, only the fixed body 10, the receiving body 20, and the deformed bodies 30, 230, and 330 are shown, and the beam structure, the capacitance element, and the like are not shown. Of course, in this case as well, either one of the fixed body 10 and the receiving body 20 may be fixed to the XYZ three-dimensional coordinate system.

Further, in each of the embodiments and modifications shown in §2 to §4, the fixed electrodes constituting each capacitance element were individually arranged for each capacitance element. As a result, the fixed electrodes can be arranged with a high degree of freedom. However, the present invention is not limited to such an embodiment, and for example, the fixed electrodes constituting each capacitance element may be configured as a common electrode.

Further, in the above description, the beam structure, the receiving body 20 and the fixed body 10 that support the capacitance element are often made of a metal (aluminum light alloy, iron-based alloy). In this case, the electrodes are short-circuited and the torque cannot be detected properly. Therefore, when the constituent member supporting the electrode is made of metal, the insulator I may be arranged between the constituent member B and the electrode E as shown in FIG.

In the above description, the V-axis and W-axis in which the measurement points P, P1 to P4, and P11 to P24 are arranged are assumed to be axes that are orthogonal to each other at 45 ° with respect to the X-axis and the Y-axis. The form has been described, but the present invention is not limited to this. The amount of fluctuation in the capacitance value is related to the length of the beam of the beam structure, and the longer the beam, the larger the change in capacitance and the higher the sensitivity of the torque sensor. Therefore, even if the V-axis and W-axis are not defined as shown in the attached drawings, the sensitivity of the torque sensor is as long as the position of the measurement point P is set away from the support of the beam structure. Is enhanced, and the effect according to the present invention can be obtained. Therefore, the V-axis and the W-axis may be defined to be at angles different from 45 °, such as 40 ° or 50 °, with respect to the X-axis and the Y-axis. Further, the V-axis and the W-axis do not have to be orthogonal to each other.

10 Fixed body 11 Fixed body connection part 11e 1st extension part 12 Fixed body connection part 12e 2nd extension part 13A to 13D 1st to 4th inner pedestals 20 Receiving bodies 21, 22 Receiving body connecting parts 23 Pedestal 23A ~ 23D 1st to 4th pedestal 24 1st protruding part 25 2nd protruding part 30, 30a Deformed part 31 Beam structure 31b Beam 31f Support 32, 34 Receiving part 33, 35 Fixed part 36, 36a Deformed part 40 detection Circuit 100, 100a Basic structure 100c Torque sensor 200 Basic structure 200c, 201c, 202c Torque sensor 230 Deformed bodies 231A to 231D First to fourth beam structures 231Ab to 231Db First to fourth beams (first to fourth beams) Outer beam)
231Ac to 231Dc 1st to 4th connecting bodies 231Af to 231Df 1st to 4th supports 231Dc 4th connecting body 231Df 4th support 232, 234 Receiving part 233, 235 Fixed part 236A to 236D 1st to 4th deformation Part 240 Detection circuit 300 Basic structure part 300c Torque sensor 330 Deformed body 331A to 331D First to fourth outer beam structures 331Ab to 331Db First to fourth outer beams 331Af to 331Df First to fourth outer supports 331E to 331H 1st to 4th inner beam structures 331Eb to 331Hb 1st to 4th inner beams 331Ef to 331Hf 1st to 4th inner beams 332, 334 Receiving part 333, 335 Fixing part 336A to 336D 1st to 4th deformation Part 340 detection circuit

Claims (2)

A torque sensor that detects torque around the Z axis in the XYZ three-dimensional coordinate system.
The first fixed / receiving body centered on the origin of the XYZ three-dimensional coordinate system,
An annular second fixed / received body arranged so as to surround the first fixed / received body when viewed from the Z-axis direction.
A first elastically deformed body whose first end is supported by the first fixed / receiving body and whose second end is supported by the second fixed / receiving body.
A second elastically deformed body whose third end is supported by the first fixed / receiving body and whose fourth end is supported by the second fixed / receiving body.
A first capacitance element having a first displacement electrode arranged on the first elastically deformed body and a first fixed electrode facing the first displacement electrode.
A second capacitance element having a second displacement electrode arranged on the second elastically deformed body and a second fixed electrode facing the second displacement electrode.
An electrical wiring that is provided so as to extend from the second fixed / receiving body and conveys the capacitance value of the first capacitance element and the capacitance value of the second capacitance element. When,
It is connected to the electrical wiring and includes a detection circuit that outputs an electrical signal indicating torque around the Z-axis.
One of the first fixed / receiving body and the second fixed / receiving body is fixed to the XYZ three-dimensional coordinate system, and the first fixed / receiving body and the second fixed / receiving body are fixed. The other of the fixed / receiving bodies rotates around the Z-axis by the action of the torque around the Z-axis.
The first fixed electrode is arranged on a first pedestal provided on the inner peripheral surface of the second fixed / receiving body.
The second fixed electrode is arranged on a second pedestal provided on the inner peripheral surface of the second fixed / receiving body.
The first end of the first elastically deformed body and the third end of the second elastically deformed body are arranged symmetrically with respect to the X-axis or the Y-axis when viewed from the Z-axis direction. Torque sensor. The torque according to claim 1, wherein the first elastic deformed body and the second elastic deformed body are arranged point-symmetrically with respect to the origin of the XYZ three-dimensional coordinate system when viewed from the Z-axis direction. Sensor.

Images