WO2019171811A1

WO2019171811A1 - Torque sensor

Info

Publication number: WO2019171811A1
Application number: PCT/JP2019/002578
Authority: WO
Inventors: 池田　隆男
Original assignee: 日本電産コパル電子株式会社
Priority date: 2018-03-08
Filing date: 2019-01-25
Publication date: 2019-09-12
Also published as: JP2019158420A; TW201939006A; TWI796429B; JP6980568B2

Abstract

A torque sensor (10) is provided with: a first area (1) formed in an annular shape; a second area (2) formed in an annular shape and positioned concentrically with the first area (1) on the inner side of said first area (1); a plurality of beam sections (3) connecting the inner side of the first area (1) with the outer side of the second area (2); strain-generating bodies (4) for detecting displacement of the first area (1) and the second area (2) relative to each other; and stoppers (5) for enhancing the rigidity of the beam sections (3) when the torque in a direction of measurement exceeds a reference value.

Description

Torque sensor

The present invention relates to a torque sensor that detects torque.

Generally, a sensor that detects torque by elastic deformation of a member is known. (See Patent Document 1).

However, in the case of a sensor that detects torque by elastic deformation of a member, in order to increase the sensitivity of the sensor, it is necessary to easily deform the elastically deformable member. However, if the member is easily deformed, an excessive load is applied. The durability of the sensor tends to be low.

JP 2007-40774 A

An object of an embodiment of the present invention is to provide a torque sensor that increases the sensitivity of the sensor and improves the rigidity against an excessive load.

A torque sensor according to an aspect of the present invention includes a first region portion formed in an annular shape, and a second region formed in an annular shape that is positioned concentrically with the first region portion inside the first region portion. In order to detect relative displacement between a region portion, a plurality of beam portions connecting the inside of the first region portion and the outside of the second region portion, and the first region portion and the second region portion And a rigidity improving means for improving the rigidity of the beam portion when the torque in the measuring direction exceeds a reference value.

FIG. 1 is a configuration diagram showing the configuration of the torque sensor according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the torque sensor shown in FIG. 1 cut along an α-α line using an adhesive. FIG. 3 is a cross-sectional view of the torque sensor shown in FIG. 1 cut along an α-α line using a fixing member. FIG. 4 is a top view showing an upper surface of a stopper according to a modification of the first embodiment. FIG. 5 is a simplified diagram showing the top surface of the stopper when torque is applied to the torque sensor according to the first embodiment. FIG. 6 is a graph illustrating the load torque of the torque sensor according to the first embodiment and the amount of displacement of the gap. FIG. 7 is a graph showing the load torque of the torque sensor according to the first embodiment and the amount of strain of the strain generating body. FIG. 8 is a configuration diagram showing the configuration of the torque sensor according to the second embodiment of the present invention.

(First embodiment)
FIG. 1 is a configuration diagram showing the configuration of the torque sensor 10 according to the first embodiment of the present invention.

The torque sensor 10 is a sensor for detecting the torque of the Z-axis moment Mz with the Z-axis (perpendicular to the drawing) as the rotation axis. For example, the torque sensor 10 is mounted on a robot or the like.

The torque sensor 10 includes a first region portion 1, a second region portion 2, a plurality of beam portions 3, a plurality of strain generating bodies 4, and a plurality of stoppers 5.

The first region portion 1, the second region portion 2, and the plurality of beam portions 3 are integrally formed of a material such as metal. The first region portion 1 is formed in an annular shape. The second region portion 2 is formed in an annular shape having a smaller diameter than the first region portion 1. The second region portion 2 is positioned on a concentric circle on the annular inner side (center side) of the first region portion 1. The plurality of beam portions 3 extend radially from the second region portion 2 and are provided so as to connect the inside of the first region portion 1 and the outside of the second region portion 2. Any number of the beam portions 3 may be provided.

1st area | region part 1 is a part attached to the load which receives a torque. For example, the first region portion 1 is attached to a movable portion such as a robot hand or arm. The second region portion 2 is a portion that is attached to a power source that generates torque. For example, the 2nd field part 2 is attached to a motor or a reduction gear.

The strain body 4 is provided between the first region portion 1 and the second region portion 2 so that a force due to relative displacement between the first region portion 1 and the second region portion 2 is applied. For example, the strain body 4 includes the first protrusion T1 extending in the direction from the first region 1 to the second region 2 and the first from the second region 2 between the two adjacent beam portions 3. It is provided so as to connect the second protrusion T2 extending in the direction of the region 1. Any number of strain generating bodies 4 may be provided. Further, the strain body 4 may be provided anywhere as long as it receives a force due to relative displacement between the first region portion 1 and the second region portion 2. For example, the strain body 4 may be provided on the beam portion 3.

The strain body 4 includes a strain gauge that serves as a sensor for detecting strain. The strain gauge is configured to generate an electrical displacement when deformed. Any strain gauge may be used as long as an electrically detectable displacement occurs. For example, the strain gauge may change its electric resistance or generate a voltage according to the amount of deformation. The torque sensor 10 measures torque by detecting these electrical displacements from the strain body 4 (strain gauge).

For example, the strain body 4 is used as follows. When torque is applied to the torque sensor 10, a pair of strain generating bodies 4 are provided at positions where symmetrical stresses are applied (positions that are left-right symmetric or vertically symmetric). The force in the direction not to be measured is not detected by canceling the output of each strain gauge of the pair of strain generating bodies 4. Thereby, the torque sensor 10 detects only the torque in the measuring direction (Z-axis moment Mz).

The stopper 5 has a rectangular parallelepiped shape whose top and bottom are rectangular or trapezoidal. The stopper 5 is provided between the first region portion 1 and the second region portion 2 so as to be limited when a force due to relative displacement between the first region portion 1 and the second region portion 2 is applied for a predetermined amount or more. . For example, the stopper 5 is provided so as to fit in a space surrounded by the first region portion 1, the second region portion 2, and the two adjacent beam portions 3. The stopper 5 is a member for improving the rigidity of the beam portion 3. The material of the stopper 5 is metal, for example.

The stopper 5 is attached in a state where a gap SP of a predetermined interval is maintained between each of the two beam portions 3. The width of the gap SP is determined based on the rated torque of the torque sensor 10 or the like. For example, the width of the gap SP is 15 to 30 μm. The stopper 5 may be provided with a gap SP between the first region portion 1 and the second region portion 2. The stopper 5 may be attached in any way as long as the stopper 5 is maintained in a state where the gap SP is maintained.

FIG. 2 is a cross-sectional view of the torque sensor 10 shown in FIG. 1 cut along an α-α line using an adhesive AD. With reference to FIG. 2, the method of attaching the stopper 5 with the adhesive agent AD is demonstrated.

The top and bottom surfaces of the stopper 5 are chamfered. Here, although the case where the stopper 5 is chamfered is shown, the first region portion 1, the second region portion 2, or the beam portion 3 may be chamfered.

The adhesive AD is an adhesive made of resin such as silicon. The adhesive AD needs to have a cured hardness that is at least lower than the rigidity of the stopper 5. This hardness is so good that it is not resistant to the torque applied to the torque sensor 10. That is, the adhesive AD is better as the cured state is softer as long as the stopper 5 cannot be removed.

The adhesive AD is applied around the top and bottom surfaces of the stopper 5 once. By being chamfered, the adhesive AD can easily become familiar around the stopper 5. At this time, the adhesive AD need only be applied to the chamfered portions of the top surface and the bottom surface, and the adhesive AD need not be applied to the side surface of the stopper 5. Further, it is not necessary to apply the adhesive AD once on the top and bottom surfaces, for example, only the four corners of each surface. That is, as long as the strength as the torque sensor 10 is maintained, the number of places where the adhesive AD is applied is the minimum necessary.

FIG. 3 is a cross-sectional view of the torque sensor 10 shown in FIG. 1 cut along an α-α line using the fixing member H1. With reference to FIG. 3, the method of attaching the stopper 5 with the fixing member H1 is demonstrated.

In a state where the stopper 5 is assembled at a predetermined position of the torque sensor 10, the fixing member H <b> 1 is fixedly provided on both the left and right sides (the beam portion 3 side) of the upper surface and the bottom surface of the stopper 5. Is not fixed. At this time, a part of the fixing member H1 provided on the upper surface and the bottom surface covers the upper surface and the bottom surface of the beam portion 3. Thereby, the movement of the stopper 5 in the vertical direction is fixed. On the other hand, the movement of the stopper 5 in the horizontal direction has a degree of freedom corresponding to the gap SP.

Note that, here, the stopper 5 is attached with four fixing members H1, but any number of fixing members H1 may be provided. Further, the fixing member H <b> 1 may be fixed to the beam portion 3 without being fixed to the stopper 5. Furthermore, the fixing member H1 may have any shape such as a plate shape or a block shape.

FIG. 4 is a top view showing the top surface of a stopper 5a according to a modification of the present embodiment.

The upper surface (bottom surface) of the stopper 5a is shaped like an X shape in which elongated plates are overlapped along two diagonals with respect to the rectangular shape of the upper surface of the space where the stopper 5a is mounted. The stopper 5a is attached in a state where gaps SP of a predetermined interval are maintained at the four corners when viewed from above. The method of attaching the stopper 5a is the same as that of the stopper 5 described above, and the adhesive AD may be applied to the gap SP, or the fixing member H1 may be used. By making the stopper 5a into such a shape, the amount of material for making the stopper 5a can be reduced.

FIG. 5 is a simplified diagram showing the upper surface of the stopper 5 when torque is applied to the torque sensor 10 according to the present embodiment.

Torque is generated by rotation applied by a power source attached to the torque sensor 10. When torque is applied, a Z-axis moment Mz is generated in the torque sensor 10. When the Z-axis moment Mz occurs, the first region portion 1 outside the stopper 5 and the second region portion 2 inside the stopper 5 move in directions opposite to each other. Thereby, the beam part 3 located in the both ends of the stopper 5 is elastically deformed so that it may become diagonal.

If the Z-axis moment Mz is within a predetermined reference value, even if the beam portion 3 is elastically deformed, the stopper 5 and the beam portion 3 do not come into contact with each other due to the gap SP between the stopper 5 and the beam portion 3. When the Z-axis moment Mz exceeds a predetermined reference value, the beam portion 3 is deformed, so that there is no gap SP in a part, and as shown in FIG. The two regions 2 come in contact with the beam 3 at opposite corners on the side of the region 2. When the beam portion 3 comes into contact with the stopper 5, the beam portion 3 is further prevented from being further deformed by the rigidity of the material of the stopper 5.

The reference value is, for example, the maximum load assumed under the condition where the torque sensor 10 is normally used. The reference value may be determined based on the rated load, such as a value obtained by multiplying or adding a coefficient to the rated load, or may be determined in any manner. The rated load is, for example, a load that is assumed to be applied most frequently in the torque sensor 10.

FIG. 6 is a graph showing the load torque of the torque sensor 10 according to this embodiment and the displacement amount of the gap SP. Here, the rated load is 800 Nm, the initial state of the gap SP is 20 μm, and the reference value of the overload is 1000 Nm.

The width of the gap SP is determined based on the reference value. Specifically, when the reference value torque is applied, the width of the gap SP is determined so that the beam portion 3 is deformed and the gap SP is eliminated. Here, when a torque of 1000 Nm is applied, as shown in FIG. 5, the gap of 20 μm disappears and the stopper 5 starts to contact the beam portion 3.

Since the deformation amount of the beam portion 3 is determined by the relative displacement amount between the first region portion 1 and the second region portion 2, it is substantially proportional to the deformation amount of the strain body 4. The greater the deformation of the strain body 4 with a small torque, the better the sensitivity (or measurement accuracy) for measuring the torque as the torque sensor 10.

In FIG. 6, when the load torque is between 0 and 1000 Nm, there is a gap SP around the stopper 5, so that the beam portion 3 is deformed without being affected by the stopper 5. Therefore, during this time, the strain body 4 is also easily deformed, and the sensitivity as a sensor is good. On the other hand, when the load torque exceeds 1000 Nm, the gap SP is crushed and the stopper 5 starts to contact the beam portion 3. For this reason, the beam part 3 becomes difficult to be deformed due to the rigidity of the stopper 5. As a result, the sensitivity as a sensor is deteriorated, but the beam portion 3 is prevented from being plastically deformed or broken due to an excessive load.

In FIG. 6, the displacement at 1000 Nm is 20 μm. If there is no stopper 5 and the load is increased to 2000 Nm, which is the maximum load, the displacement amount by simple calculation is doubled to 40 μm. However, since the elastic deformation rate with respect to the load decreases after the stopper 5 comes into contact with the beam portion 3, the amount of deformation at the actual maximum load can be suppressed to about 26 μm.

FIG. 7 is a graph showing the load torque of the torque sensor 10 and the strain amount of the strain generating body 4 according to the present embodiment. The torque sensor 10 is the same as in FIG.

Also in FIG. 7, since the strain amount at 1000 Nm is 10 μm as in FIG. 6, if the load is increased to 2000 Nm which is the maximum load without the stopper 5, the strain amount by simple calculation becomes 20 μST. However, by providing the stopper 5, the amount of distortion at the actual maximum load can be suppressed to 13 μST.

According to the present embodiment, by providing the stopper 5, if the torque of the Z-axis moment Mz is equal to or less than the reference value, the strain generating body 4 is easily deformed and the sensitivity of the torque sensor 10 as a sensor is increased. When the torque exceeds the reference value, the rigidity of the beam portion 3 can be improved, and plastic deformation or destruction of the beam portion 3 due to an excessive load can be prevented.

In addition, even when a force other than the Z-axis moment Mz due to torque is applied to the torque sensor 10, the rigidity of the beam portion 3 can be improved by the stopper 5. For example, for a force that deforms the beam portion 3 in the direction in which the gap SP is not provided, the rigidity of the stopper 5 is always increased regardless of the strength of the force.

In addition, although the structure which provides the stopper 5 was demonstrated in this embodiment, it is not restricted to this. For example, if the beam portion 3 is configured so that the beam portion 3 is less likely to be deformed when the torque exceeds the reference value than when the torque is below the reference value, the stopper 5 may not be provided. .

(Second Embodiment)
FIG. 8 is a configuration diagram showing a configuration of a torque sensor 10A according to the second embodiment of the present invention.

In the torque sensor 10A according to the first embodiment shown in FIG. 1, the torque sensor 10A is provided with a beam portion 3A instead of the first protrusion T1 and the second protrusion T2 in order to install the strain generating body 4. It is a thing. Other points are the same as in the first embodiment.

The same number of the plurality of beam portions 3A as the strain body 4 is provided. The beam portion 3 </ b> A is obtained by changing the shape of some of the beam portions 3 among the plurality of beam portions 3.

The beam portion 3A has a shape that is more easily deformed than the other beam portions 3 due to the torque of the Z-axis moment Mz. Specifically, the portion connected to the beam portion 3A of the first region portion 1 is widened outward (to the first region portion 1 side) so that the length of the beam portion 3A is longer than the other beam portions 3. It is deformed as follows. Further, the outer portion of the beam portion 3A is made thinner than the other beam portions 3, thereby making the deformation easier.

According to the present embodiment, in addition to the functions and effects of the first embodiment, the following functions and effects can be obtained.

By providing the stopper 5, when the excessive torque is applied, the beam portion 3 is configured to be prevented from being plastically deformed or broken, so that the sensitivity of torque detection is increased. Therefore, there is no problem in the durability of the torque sensor 10A even if the beam portion 3A provided with the strain generating body 4 is formed into a shape that can be easily deformed. Therefore, by providing the strain body 4 in the beam portion 3 </ b> A that is easily deformed, the sensitivity of torque detection can be increased as compared with the case where the strain body 4 is provided in the normal beam portion 3.

It should be noted that the present invention is not limited to the above-described embodiment, and constituent elements may be deleted, added or changed. Moreover, it is good also as a new embodiment by combining or exchanging a component about several embodiment. Even if such an embodiment is directly different from the above-described embodiment, those having the same gist as the present invention are described as the embodiment of the present invention, and the description thereof is omitted.

Claims

A first region formed in an annular shape;
A second region portion that is concentric with the first region portion and formed in an annular shape inside the first region portion;
A plurality of beam portions connecting the inside of the first region portion and the outside of the second region portion;
A strain generating body for detecting a relative displacement between the first region portion and the second region portion;
A torque sensor comprising: a rigidity improving means for improving the rigidity of the beam portion when the torque in the measuring direction exceeds a reference value.
2. The torque sensor according to claim 1, wherein the rigidity improving unit is provided with a rigidity improving member for improving the rigidity of the beam portion between two adjacent beam portions of the plurality of beam portions.
The torque sensor according to claim 2, wherein the rigidity improving member is provided in a state in which a gap between each of the two adjacent beam portions is maintained at a distance determined based on the reference value. .
The torque sensor according to claim 3, wherein the rigidity improving member maintains a state in which the gap is maintained with an adhesive.
The torque sensor according to claim 3, further comprising a fixing member for maintaining the rigidity improving member in a state in which the gap is maintained.
The torque sensor according to claim 1, wherein the strain body is provided at a location other than the plurality of beam portions between the first region portion and the second region portion.
The torque sensor according to claim 1, wherein the strain body is provided in a beam portion having a shape that is more easily deformed than the other beam portions among the plurality of beam portions.