WO2019035290A1

WO2019035290A1 - Torque detector

Info

Publication number: WO2019035290A1
Application number: PCT/JP2018/025894
Authority: WO
Inventors: 祐希瀬戸; 石倉　義之; 里奈小笠原
Original assignee: アズビル株式会社
Priority date: 2017-08-14
Filing date: 2018-07-09
Publication date: 2019-02-21
Also published as: CN111033198B; JP2019035637A; JP6820101B2; CN111033198A; KR20200019244A; KR102333525B1

Abstract

The present invention is provided with: a silicon layer (11) provided with a resistance gauge (13); and an insulation layer (12) of which one surface is joined to at least both ends of the silicon layer (11), and of which both ends in the longitudinal direction of a facing surface facing the one surface are joined to a rotational shaft (5).

Description

Torque detector

The present invention relates to a torque detector that detects torque applied to a rotating shaft.

A metal strain gauge is attached to the peripheral surface of the rotating shaft as one of the methods to detect the torque applied to the rotating shaft, and the magnitude of shear stress generated on the peripheral surface of the rotating shaft by torque There is a method of detecting by value change. In this method, a bridge circuit is configured by mounting four or more metal strain gauges at 45 degrees with respect to the axial direction of the rotating shaft.
However, with a metal strain gauge, it is difficult to detect minute strain with high accuracy because the gauge factor is small.

On the other hand, as a method of increasing the detection sensitivity of torque, there is considered a method of decreasing the rigidity of the rotating shaft and increasing the amount of distortion. In patent document 1, the improvement of sensitivity is implement | achieved by giving various processes to a rotating shaft and forming a beam part.

JP, 2016-109568, A

However, in the method of reducing the rigidity of the rotating shaft, a problem of hysteresis due to stress increase (a problem of trade-off between sensitivity and hysteresis) occurs, and improvement in accuracy can not be expected.
In the conventional method, it is necessary to arrange at least four metal strain gauges. Therefore, it is necessary to exactly match the relative positions and angles of the metal strain gauges, which causes a problem of difficulty.

Here, in an industrial robot, detection of torque is essential to control its operation. Therefore, conventionally, a torque detector is attached to the industrial robot to detect the torque of each joint of the robot arm.
On the other hand, in recent years, in order for industrial robots to coexist with people without being separated, there is a demand for safety that instantaneously detects contact and stops operation when touching an object such as a person or a thing. There is. However, since the industrial robot has its own weight and the weight of the object to be held, and it is a robust casing in consideration of the operation speed, it is not possible to detect the torque with high accuracy with the conventional metal strain gauge. difficult.

The present invention has been made to solve the problems as described above, and it is an object of the present invention to provide a torque detector that improves the detection accuracy of torque.

The torque detector according to the present invention has a resistance gauge, and a substrate layer in which strain occurs in response to an external force, and one surface is joined to at least both ends of the substrate layer, and both longitudinal direction ends of opposing surfaces facing the one surface are rotated. And an insulating layer bonded to the shaft.

According to this invention, since it comprised as mentioned above, detection accuracy of a torque improves.

1A to 1C are diagrams showing a configuration example of a torque detector according to Embodiment 1 of the present invention, FIG. 1A is a top view, FIG. 1B is a side view, and FIG. 1C is AA FIG. FIG. 2A is a top view showing an arrangement example of the resistance gauges according to the first embodiment of the present invention, and FIG. 2B is a view showing a construction example of a full bridge circuit constituted by the resistance gauges shown in FIG. 2A. It is a flowchart which shows an example of the manufacturing method of the distortion sensor in Embodiment 1 of this invention. FIGS. 4A and 4B are diagrams showing a state in which the strain sensor according to Embodiment 1 of the present invention is attached to a rotating shaft, FIG. 4A is a top view, and FIG. 4B is a side view. 5A and 5B are diagrams for explaining the basic operation principle of the torque detector, and FIG. 5A is a side view showing the torque applied to the rotating shaft, and FIG. 5B is a strain sensor based on the torque shown in FIG. It is a figure which shows an example of the stress distribution which generate | occur | produced in. It is a side view which shows another structural example of the distortion sensor in Embodiment 1 of this invention. It is a side view (figure which shows the state in which the distortion sensor was attached to the rotating shaft) which shows another structural example of the distortion sensor in Embodiment 1 of this invention. It is a side view (figure which shows the state in which the distortion sensor was attached to the rotating shaft) which shows another structural example of the distortion sensor in Embodiment 1 of this invention. It is a side view (figure which shows the state in which the distortion sensor was attached to the rotating shaft) which shows another structural example of the distortion sensor in Embodiment 1 of this invention. 10A to 10C are top views showing another example of arrangement of the resistance gauges according to the first embodiment of the present invention. FIG. 11A is a top view showing another arrangement example of the resistance gauge in accordance with the first embodiment of the present invention, and FIG. 11B is a view showing a construction example of a half bridge circuit constituted by the resistance gauge shown in FIG. 11A. 12A to 12C are back views showing another configuration example of the silicon layer in the first embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1
FIG. 1 is a view showing a configuration example of a torque detector according to Embodiment 1 of the present invention.
The torque detector detects the torque applied to the rotating shaft 5 (see FIG. 4). In the rotating shaft 5, a drive system 6 such as a motor is connected to one end in the axial direction, and a load system such as a robot hand is connected to the other end. The torque detector includes a strain sensor 1 as shown in FIG.

The strain sensor 1 is a semiconductor strain gauge attached to the rotating shaft 5 and outputting a voltage according to external shear stress (tensile stress and compressive stress). The strain sensor 1 is realized by MEMS (Micro Electro Mechanical Systems). The strain sensor 1 has a silicon layer (substrate layer) 11 and an insulating layer 12 as shown in FIGS.

The silicon layer 11 is a single crystal silicon in which strain is generated in response to an external force, and is a sensor layer having a Wheatstone bridge circuit composed of a plurality of resistance gauges (diffusion resistances) 13. A groove 111 is formed in the center of the back surface (one surface) of the silicon layer 11. The thin portion 112 is formed in the silicon layer 11 by the groove portion 111. The resistance gauge 13 is formed on the thin portion 112.

The thickness of the thin portion 112 is appropriately designed in accordance with the rigidity and the like of the silicon layer 11. For example, when the rigidity of the silicon layer 11 is low, the thin portion 112 is thick, and when the rigidity of the silicon layer 11 is high, the thin portion 112 is thin.

In addition, single crystal silicon has crystal anisotropy, and in the p-type silicon (100) plane, the piezoresistance coefficient is largest in the <110> direction. Therefore, the resistance gauge 13 is formed, for example, in the <110> direction of the silicon layer 11 whose crystal orientation on the surface is (100).
In FIG. 2, four resistance gauges 13 (R1 to R4) constituting a full bridge circuit (Wheatstone bridge circuit) are formed in a diagonal direction (45 degrees direction) with respect to the side direction of the silicon layer 11. Shows the case of detecting shear stress in two directions. Here, although the case where it is 45 degrees direction was shown as a specific example of the above-mentioned oblique direction, the above-mentioned oblique direction is not limited to 45 degrees direction, but the characteristic of distortion sensor 1 46 degrees direction etc) is acceptable.

The insulating layer 12 is a pedestal in which the upper surface (one surface) is joined to at least both ends of the back surface of the silicon layer 11 and the longitudinal opposite ends of the back surface (facing surface facing the one surface) are joined to the rotating shaft 5. For example, glass or sapphire can be used as the insulating layer 12.
FIG. 1 shows the case where the upper surface of the insulating layer 12 is bonded to the entire surface of the back surface of the silicon layer 11. Further, in the insulating layer 12, a groove portion 121 is formed in a region excluding both ends in the longitudinal direction of the back surface. Bonding portions 122 are formed at both ends in the longitudinal direction of the back surface of the insulating layer 12 by the groove portions 121. Then, as shown in FIG. 4, the bonding portion 122 of the insulating layer 12 is directly bonded to the rotating shaft 5.

Next, an example of a method of manufacturing the strain sensor 1 will be described with reference to FIG.
In the method of manufacturing the strain sensor 1, as shown in FIG. 3, first, a plurality of resistance gauges 13 are formed in the silicon layer 11 by ion implantation (Step ST1). Then, a plurality of resistance gauges 13 form a Wheatstone bridge circuit.
Next, the groove portion 111 is formed on the back surface of the silicon layer 11 by etching (step ST2). Thereby, the portion of the silicon layer 11 where the resistance gauge 13 is formed is made to be the thin portion 112.
Further, the groove 121 is formed by etching in the region excluding the both ends in the longitudinal direction of the back surface of the insulating layer 12 (step ST3). Thus, the bonding portions 122 are formed at both ends in the longitudinal direction of the back surface of the insulating layer 12.
Next, the back surface of the silicon layer 11 and the top surface of the insulating layer 12 are bonded by, for example, anodic bonding (step ST4).

When the strain sensor 1 manufactured as described above is attached to the rotating shaft 5, the joint portion 122 of the insulating layer 12 and the rotating shaft 5 are joined by, for example, solder bonding. At this time, solder bonding is performed after metalizing the bonding portion 122 of the insulating layer 12 and the bonding portion of the rotating shaft 5. FIG. 4 shows a state in which the strain sensor 1 is attached to the rotating shaft 5.

Further, the strain sensor 1 is disposed such that the resistance gauge 13 is directed obliquely (45 degrees) with respect to the axial direction of the rotating shaft 5. That is, the resistance gauge 13 is disposed so as to face the generation direction of the shear stress generated when the torque is applied to the rotating shaft 5. Here, although the case where it is 45 degrees direction was shown as a specific example of the above-mentioned oblique direction, the above-mentioned oblique direction is not limited to 45 degrees direction, but the characteristic of distortion sensor 1 46 degrees direction etc) is acceptable.

Next, the basic operation principle of the torque detector will be described with reference to FIG. In FIG. 5A, the drive system 6 is connected to one end of the rotary shaft 5 to which the strain sensor 1 is attached, and a state where torque is applied to the rotary shaft 5 by the drive system 6 is shown.
As shown in FIG. 5A, by applying torque to the rotating shaft 5, the strain sensor 1 attached to the rotating shaft 5 is strained, and shear stress as shown in FIG. 5B is generated on the surface of the strain sensor 1. . FIG. 5 shows that the deeper the color, the stronger the tensile stress, and the lighter the color, the stronger the compressive stress. And resistance gauge 13 which turned to a diagonal direction (45 degrees direction) to the axial direction of axis of rotation 5 changes resistance value according to this shear stress, and strain sensor 1 changes according to change of resistance value. Output voltage. The torque detector detects the torque applied to the rotating shaft 5 from the voltage output by the strain sensor 1.

In the torque detector according to the first embodiment, bonding portions 122 are formed on both ends in the longitudinal direction of the back surface of the insulating layer 12, and only the bonding portions 122 are bonded to the rotating shaft 5.
Here, in the case where the strain sensor 1 is directly attached to the rotating shaft 5, the relative amount of strain increases as the mounting position becomes farther in the axial direction of the rotating shaft 5. Therefore, by setting the joint portion 122 of the strain sensor 1 only to the outside in the axial direction, the largest displacement difference can be transmitted to the strain sensor 1, and the detection sensitivity to the torque applied to the rotating shaft 5 is improved.

In this method, when the strain sensor 1 itself, in particular, the rigidity of the insulating layer 12 is low, the deformation of the rotary shaft 5 is hard to be transmitted to the strain sensor 1, so the insulating layer 12 should be made of a harder material. The effect is higher. For example, using sapphire or the like as the insulating layer 12 is more effective than using glass.

In the torque detector described above, the thin portion 112 is formed by forming the groove portion 111 in the center of the back surface of the silicon layer 11, and the resistance gauge 13 is formed in the thin portion 112. Thereby, the stress can be concentrated on the thin portion 112 in which the resistance gauge 13 is formed, and the detection sensitivity to the torque applied to the rotating shaft 5 is improved.

In the above, the case where the upper surface of the insulating layer 12 is bonded to the entire back surface of the silicon layer 11 is shown. However, the present invention is not limited to this. For example, as shown in FIG. 6, even if the insulating layer (first insulating layer) 123 and the insulating layer (second insulating layer) 124 in which the insulating layer 12 is divided into two at the center are used. Good. Thereby, the deformation of the rotating shaft 5 can be transmitted to the strain sensor 1 more efficiently.

In the above, the case where the groove portion 121 is formed on the back surface of the insulating layer 12 is shown. However, the present invention is not limited to this, as long as only both longitudinal ends of the insulating layer 12 are joined to the rotating shaft 5.
For example, as shown in FIG. 7, two plate-like insulating layers (a first insulating layer, a second insulating layer) disposed as an insulating layer 12 with a gap and facing only both ends in the longitudinal direction of the silicon layer 11 The two insulating

layers

125 and 126 may be directly bonded to the rotating shaft 5 using 125 and 126.
For example, as shown in FIG. 8, a column member 14 with high rigidity is joined to both ends in the longitudinal direction of the back surface of the plate-like insulating layer 12, and the insulating layer 12 is connected to the rotary shaft 5 via the column member 14. It may be configured to be bonded to
For example, as shown in FIG. 9, both ends in the longitudinal direction of the back surface of the plate-like insulating layer 12 may be directly bonded to the rotating shaft 5 by an adhesive member (adhesive, solder or the like) 15.

Further, the arrangement of the four resistance gauges 13 is not limited to the arrangement shown in FIG. 2, but may be an arrangement as shown in FIG. 10, for example.

Also, in the above description, the case where a full bridge circuit composed of four resistance gauges 13 (R1 to R4) is used as the Wheatstone bridge circuit is shown. However, the present invention is not limited to this, and as shown in FIG. 11, a half bridge circuit composed of two resistance gauges 13 (R1 and R2) may be used as a Wheatstone bridge circuit. Note that R in FIG. 11B is a fixed resistance.

Further, as shown in FIG. 12, a communication groove portion 113 may be formed on the back surface of the silicon layer 11 so as to communicate the groove portion 111 with the side surface of the silicon layer 11. Here, in the bonding of the silicon layer 11 and the insulating layer 12, a temperature of about 400 ° C. is applied by anodic bonding. Therefore, when the communication groove portion 113 is not present, the air present in the groove portion 111 between the silicon layer 11 and the insulating layer 12 is sealed in a high temperature state at the time of anodic bonding, and when the temperature drops to normal temperature As a result, the thin-walled portion 112 may be deformed and the zero point of the strain sensor 1 may be displaced. On the other hand, by providing the communication groove portion 113, air present in the groove portion 111 can be released to the outside at the time of anodic bonding, and deformation of the thin portion 112 can be avoided.
The silicon layer 11 needs to be configured so as to be partially thinned by the groove portion 111 and the communication groove portion 113 so as not to be entirely thinned.

Moreover, in the above, the case where the semiconductor strain gauge which has the thin part 112 for making stress concentrate was used as the strain sensor 1 was shown. However, the present invention is not limited to this, and a semiconductor strain cage of another shape (for example, a shape without the thin portion 112) may be used.

As described above, according to the first embodiment, the silicon layer 11 having the resistance gauge 13 and one surface are joined to at least both ends of the silicon layer 11, and both longitudinal direction ends of the opposing surface facing the one surface are rotation axes Since the insulating layer 12 joined to the body 5 is provided, the torque detection accuracy is improved.

In addition, although the case where the silicon layer 11 was used as a board | substrate layer was shown in the above, it does not restrict to this, and should just be a member which distortion produces according to external force. For example, as the substrate layer, an insulator (such as glass) or a metal can be used. Here, when the substrate layer is an insulator, the resistance gauge 13 is formed by depositing a film on the insulator by sputtering or the like. When the substrate layer is metal, the resistance gauge 13 is formed by sputtering the metal via an insulating film. Alternatively, the silicon layer 11 may be used as a substrate layer, and the resistance gauge 13 may be formed on the silicon layer 11 by sputtering or the like.
Even when the above-mentioned insulator or metal is used as the substrate layer, the gauge factor becomes higher than that of a general metal strain gauge. Further, when the resistance gauge 13 is formed by film formation, the gauge ratio does not change depending on the crystal orientation as opposed to the case where the resistance gauge 13 is formed in the silicon layer 11 by ion implantation, that is, the direction needs to be limited. There is no
On the other hand, the gauge factor is 4 to 10 times higher in the case where the resistance gauge 13 is formed by ion implantation in the silicon layer 11 than when the resistance gauge 13 is formed by film formation.

In the present invention, within the scope of the invention, modifications of optional components of the embodiment or omission of optional components of the embodiment is possible.

The torque detector according to the present invention is suitable for use in, for example, a torque detector that detects a torque applied to a rotating shaft because the torque detection accuracy is improved.

Reference Signs List 1 strain sensor 5 rotating shaft 6 driving system 11 silicon layer (substrate layer)
12 insulation layer 13 resistance gauge (diffusion resistance)
14 Column member 15 Bonding member 111 Groove portion 112 Thin portion 113 Communication groove portion 121 Groove portion 122 Bonding portion 123 Insulating layer (first insulating layer)
124 Insulating layer (second insulating layer)
125 insulating layer (first insulating layer)
126 insulating layer (second insulating layer)

Claims

A substrate layer which has a resistance gauge and is distorted in response to an external force;
An insulating layer, one surface of which is joined to at least both ends of the substrate layer, and the opposite longitudinal ends of the opposing surface opposed to the one surface are joined to the rotating shaft.
The torque detector according to claim 1, wherein the substrate layer is a silicon layer.
The crystal orientation of the surface of the said silicon layer is (100). The torque detector of Claim 2 characterized by the above-mentioned.
The torque detector according to any one of claims 1 to 3, wherein the resistance gauge is formed by forming a film on the substrate layer.
The said resistance gauge was formed in the <110> direction of the said silicon layer. The torque detector of Claim 2 or Claim 3 characterized by the above-mentioned.
A groove is formed on the facing surface of the insulating layer and has a bonding portion at both ends in the longitudinal direction of the facing surface.
The said junction part is directly joined to the said rotating shaft. The torque detector in any one of the Claims 1-5 characterized by the above-mentioned.
The insulating layer comprises a first insulating layer and a second insulating layer disposed with a gap,
The torque detector according to any one of claims 1 to 5, wherein the first insulating layer and the second insulating layer are directly bonded to the rotating shaft.
One surface is joined to both ends in the longitudinal direction of the facing surface of the insulating layer, and the facing surface facing the one surface is provided with a pillar member directly joined to the rotary shaft.
The said insulating layer is joined to the said rotating shaft via the said pillar member. The torque detector in any one of the Claims 1-5 characterized by the above-mentioned.
The torque detector according to any one of claims 1 to 5, wherein the insulating layer is directly bonded to the rotating shaft by an adhesive member.