TW201939006A - Torque sensor - Google Patents

Abstract

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

Description

Torque sensor

FIELD OF THE INVENTION The present invention relates to a torque sensor for detecting torque.

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

However, if a torque sensor is used to detect the torque by the elastic deformation of the component, to increase the sensitivity of the sensor, it is necessary to make the elastically deformed component easy to deform. However, if the component is easily deformed, the When the load is too large, the durability of the sensor tends to be low.
Prior art literature

Patent Literature Patent Literature 1: Japanese Patent Laid-Open No. 2007-40774

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

A torque sensor according to an aspect of the present invention includes: a first region portion formed in a ring shape; and a second region portion formed inside the first region portion on a concentric circle with the first region portion and formed as Ring shape; a plurality of beam portions connecting the inside of the first area portion and the outside of the second area portion; a strain body for detecting relative displacement between the first area portion and the second area portion; and a rigid lifting mechanism When the torque in the measurement direction exceeds a reference value, the rigidity of the beam portion is improved.

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

The torque sensor 10 is a sensor for detecting a torque of a Z-axis moment Mz having a Z-axis (vertical direction with respect to the drawing) as a 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 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 a ring shape. The second region portion 2 is formed in a ring shape having a smaller diameter than the first region portion 1. The second area portion 2 is located on the inner side (center side) of the ring of the first area portion 1 and is located on a concentric circle. The plurality of beam portions 3 are provided to extend radially from the second region portion 2 and connect the inside of the first region portion 1 and the outside of the second region portion 2. The beam portion 3 may be provided in plural.

The first area portion 1 is a portion attached to a load that receives torque. For example, the first area portion 1 is a movable portion attached to a hand, an arm, or the like of a robot. The second area portion 2 is a portion attached to a power source that generates torque. For example, the second area portion 2 is mounted on a motor, a reduction gear, or the like.

The strain body 4 is provided between the first region portion 1 and the second region portion 2 so that a force caused by a relative displacement of the first region portion 1 and the second region portion 2 is applied. For example, the strain body 4 is provided between two adjacent beam portions 3 to connect the first protruding portion T1 extending from the first region portion 1 toward the second region portion 2 and the second projection portion 2 from the second region portion 2. Between the second protruding portions T2 extending in the direction of the first region portion 1. Moreover, several strain bodies 4 may be provided. The strain body 4 can be installed anywhere as long as it can withstand the force caused by the relative displacement between the first region portion 1 and the second region portion 2. For example, the strain body 4 may be provided in the beam portion 3.

The strain body 4 includes a strain gauge that functions as a sensor that detects strain. The strain gage is configured to cause electrical displacement once deformed. In addition, as long as the strain gage is capable of generating a detectable displacement electrically, it can be any object. For example, the strain gauge can change the resistance according to the amount of deformation, and can also generate the voltage according to the amount of deformation. The torque sensor 10 measures the torque by detecting these electrical displacements from the strain body 4 (strain gage).

For example, the strain body 4 is used as follows. The pair of strain bodies 4 are provided at positions where stresses that are symmetrical to each other are applied to the torque sensor 10 (positions such as left-right symmetry or vertical symmetry). The force in the direction in which the measurement is not performed is performed by canceling the outputs of the strain gauges of the pair of strain bodies 4 with each other. As a result, the torque sensor 10 detects a torque in a direction (Z-axis moment Mz) in which measurement is performed.

The stopper 5 has a rectangular or trapezoidal shape with an upper surface and a bottom surface. The stopper 5 is provided between the first region portion 1 and the second region portion 2 so as to restrict the force caused by the relative displacement of the first region portion 1 and the second region portion 2 from being applied for more than a predetermined amount. For example, the stopper 5 is provided so as to be fitted in a space surrounded by the first region portion 1, the second region portion 2, and 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, for example, metal.

The stopper 5 is attached in a state where a gap SP is maintained at a predetermined distance from each of the two beam portions 3. The width of the slot SP is determined based on the rated torque of the torque sensor 10 and the like. For example, the width of the slit SP is 15 to 30 μm. The stopper 5 may be provided with a gap SP from each of the first region portion 1 and the second region portion 2. Moreover, as long as the stopper 5 is maintained in the state which maintains the space | interval of the slot SP, it can be attached by any method.

FIG. 2 is a cross-sectional view after the torque sensor 10 shown in FIG. 1 is cut by an α-α line using an adhesive AD. A method of mounting the stopper 5 with the adhesive AD will be described with reference to FIG. 2.

The upper surface and the bottom surface of the stopper 5 are chamfered. Although the chamfering of the stopper 5 is shown here, the 1st area part 1, the 2nd area part 2, or the beam part 3 may be chamfered.

The adhesive AD is, for example, a resin adhesive such as silicon. It is necessary for the hardness of the adhesive AD to be lower than the rigidity of the stopper 5 at least. This hardness is better as the resistance to the torque applied to the torque sensor 10 does not form. That is, as long as the stopper 5 does not come loose, the state after the adhesive AD hardens is as soft as possible.

The adhesive AD is applied once around the periphery of the upper surface and the bottom surface of the stopper 5. Due to the chamfering, the adhesive AD becomes easy to adhere to the periphery of the stopper 5. At this time, the adhesive agent AD may be applied only to the chamfered portions of the upper surface and the bottom surface, and it is not necessary to apply the adhesive agent AD even to the side surface of the stopper 5. In addition, it is not necessary to apply the adhesive AD once even on the upper surface and the bottom surface, and for example, it may be applied to only four corners of the respective surfaces. That is, as long as the strength as the torque sensor 10 is maintained, the position where the adhesive AD is applied is at the required minimum.

FIG. 3 is a cross-sectional view after the torque sensor 10 shown in FIG. 1 is cut by the α-α line using the fixing member H1. A method of mounting the stopper 5 with the fixing member H1 will be described with reference to FIG. 3.

In a state where the stopper 5 is installed in a predetermined position of the torque sensor 10, the fixing member H1 is fixedly provided on each of the left and right sides (the beam portion 3 side) of the upper and bottom surfaces of the stopper 5, and Department 3 is not fixed. At this time, a part of the fixing member H1 provided on the upper surface and the bottom surface is formed so as to cover the upper surface and the bottom surface of the beam portion 3. Thereby, the fixed stopper 5 is moved in the vertical direction. On the other hand, the movement of the stopper 5 in the horizontal direction has a degree of freedom corresponding to the amount of the slit SP.

In addition, although the stopper 5 is mounted with four fixing members H1 here, several fixing members H1 may be provided. The fixing member H1 may not be fixed to the stopper 5 but may be fixed to the beam portion 3. 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 upper surface of a stopper 5a according to a modification of the embodiment.

The upper surface (bottom surface) of the stopper 5a is formed in a quadrangular shape with respect to the upper surface of the space in which the stopper 5a is installed, and the shape of an X-shaped plate is alternately overlapped along two diagonal lines. The stopper 5 a is attached in a state where the four corners have a gap SP with a predetermined interval as viewed from the upper surface. The mounting method of the stopper 5a is the same as that of the above-mentioned stopper 5, and the adhesive agent AD may be applied to the gap SP, or the fixing member H1 may be used. By forming the stopper 5a into such a shape, it is possible to suppress the amount of the material used to make the stopper 5a to be small.

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 this embodiment.

The torque is generated by rotation applied by a power source mounted on the torque sensor 10. When torque is applied, the Z-axis torque Mz is generated in the torque sensor 10. When the Z-axis moment Mz is generated, the first area portion 1 located outside the stopper 5 and the second area portion 2 located inside the stopper 5 will move in opposite directions to each other. Thereby, the beam portions 3 located at both ends of the stopper 5 are elastically deformed to become inclined.

As long as 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 will not contact due to the gap SP between the stopper 5 and the beam portion 3. If the Z-axis moment Mz exceeds a predetermined reference value, the gap SP will partially disappear due to the deformation of the beam portion 3, and as shown in FIG. 5, the first region portion 1 side and the second region of the stopper 5 The corners on the opposite sides of the portion 2 come into contact with the beam portion 3. When the beam portion 3 is in contact with the stopper 5, the beam portion 3 is restricted from further deforming due to the rigidity of the material of the stopper 5.

The reference value is, for example, the maximum load assumed by the torque sensor 10 under the conditions of normal use. The reference value can be determined based on the rated load just like multiplying or adding a factor to the rated load, or it can be determined in any way. The rated load is, for example, a load that is assumed to be applied to the maximum in the torque sensor 10.

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

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

The amount of deformation of the beam portion 3 is determined by the amount of relative displacement between the first region portion 1 and the second region portion 2, and therefore is almost proportional to the amount of deformation of the strain body 4. The greater the degree of deformation of the strain body 4 under a small torque, the better the sensitivity (or measurement accuracy) of the measured torque as the torque sensor 10.

In FIG. 6, when the load torque is between 0 and 1000 Nm, since there is a gap SP around the stopper 5, 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 cannot be maintained, and the stopper 5 starts to contact the beam portion 3. Therefore, the rigidity of the stopper 5 makes it difficult for the beam portion 3 to deform. Thereby, although the sensitivity as a sensor is deteriorated, it is possible to prevent plastic deformation or destruction of the beam portion 3 under an excessive load.

In FIG. 6, the amount of displacement at 1000 Nm is 20 μm. Assuming that the stopper 5 is not provided and the load is increased to 2000 Nm, which is the maximum load, the amount of displacement by a simple calculation becomes 40 μm that is twice as large. However, after the stopper 5 comes into contact with the beam portion 3, the elastic deformation rate with respect to the load decreases, so the amount of deformation at the actual maximum load is 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 body 4 in the present embodiment. The torque sensor 10 is the same as that of FIG. 6.

7 is also the same as FIG. 6. From the viewpoint that the strain amount at 1000 Nm is 10 μm, without the stopper 5, if the load is increased to 2000 Nm, which is the maximum load, the strain amount by simple calculation becomes 20 μST. However, by providing the stopper 5, the amount of strain at the actual maximum load is suppressed to 13 μST.

According to this embodiment, by providing the stopper 5, as long as the torque of the Z-axis moment Mz is equal to or less than the reference value, the strain body 4 can be easily deformed, and the sensitivity of the sensor as the torque sensor 10 can be improved. In addition, 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 caused by excessive load can be prevented.

Further, even when a force other than the Z-axis moment Mz due to the 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 a direction in which the gap SP is not provided, the rigidity of the stopper 5 always increases the rigidity of the beam portion 3 regardless of the strength of the force.

In addition, in this embodiment, although the structure which provided the stopper 5 was demonstrated, it is not limited to this. For example, as long as the beam portion 3 and the like are configured so that the beam portion 3 becomes more difficult to deform when the torque exceeds 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 a second embodiment of the present invention.

The torque sensor 10A is a torque sensor 10 of the first embodiment shown in FIG. 1. In order to provide a strain body 4, a beam portion is provided instead of the first protrusion portion T1 and the second protrusion portion T2. 3A person. The other points are the same as those of the first embodiment.

The plurality of beam portions 3A are provided in the same number as the strain bodies 4. The beam portion 3A is a shape in which the shape of the beam portion 3 is changed among some of the plurality of beam portions 3.

The beam portion 3A has a shape that is easier to deform by the torque of the Z-axis moment Mz than the other beam portions 3. Specifically, it is modified to expand the portion of the first region portion 1 that is connected to the beam portion 3A to the outside (first region portion 1 side) so that the length of the beam portion 3A is longer than that of the other beam portions 3 . In addition, the outer portion of the beam portion 3A is made thinner than the other beam portions 3 to make it easier to deform.

According to this embodiment, the following effects can be obtained in addition to the effects obtained by the first embodiment.

The structure is such that, for example, the stopper 5 is provided to prevent the beam portion 3 from being plastically deformed or broken when an excessive torque is applied. Therefore, a strain body is provided to increase the sensitivity of the torque detection. The beam portion 3A of 4 has a shape that is easily deformed, and the durability of the torque sensor 10A is not a problem. Therefore, by providing the strain body 4 in the beam portion 3A which is easily deformed, the sensitivity of the torque detection can be increased more than that in which the strain body 4 is provided in the normal beam portion 3.

In addition, the present invention is not limited to the above-mentioned embodiment, and constituent elements may be deleted, added, or changed. In addition, for a plurality of embodiments, a new embodiment can be made by combining or exchanging constituent elements and the like. Even if this embodiment is directly different from the above-mentioned embodiment, those who have the same object as the present invention are regarded as those who have described the embodiment of the present invention, and descriptions thereof are omitted.

1‧‧‧1st Regional Division

2‧‧‧ 2nd Regional Division

3, 3A‧‧‧Beam

4‧‧‧ strain body

5,5a‧‧‧stop

10, 10A‧‧‧torque sensor

AD‧‧‧Adhesive

H1‧‧‧Fixed components

SP‧‧‧ Gap

T1‧‧‧The first protrusion

T2‧‧‧ 2nd protrusion

X, Y, Z‧‧‧ directions

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

FIG. 2 is a cross-sectional view of the torque sensor shown in FIG. 1 cut by an α-α line using an adhesive.

FIG. 3 is a cross-sectional view of the torque sensor shown in FIG. 1 after the torque sensor shown in FIG. 1 is cut 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 upper surface of the stopper when torque is applied to the torque sensor of the first embodiment.

Fig. 6 is a graph showing a load torque and a displacement amount of a gap of the torque sensor of the first embodiment.

7 is a graph showing a load torque and a strain amount of a strain body of the torque sensor according to the first embodiment.

8 is a configuration diagram showing a configuration of a torque sensor according to a second embodiment of the present invention.

Claims (7)

A torque sensor is characterized by: have: The first area portion is formed in a ring shape; The second region portion is formed inside the first region portion on a concentric circle with the first region portion and is formed in a ring shape; A plurality of beam portions connecting the inside of the first region portion and the outside of the second region portion; A strain body for detecting a relative displacement between the first region portion and the second region portion; and The rigid lifting mechanism is used to increase the rigidity of the beam portion when the torque in the measurement direction exceeds a reference value. For example, the torque sensor according to claim 1, wherein the rigid lifting mechanism is a rigid lifting member for improving the rigidity of the beam portion between two adjacent beam portions among the plurality of beam portions. The torque sensor according to claim 2, wherein the rigid lifting member is provided in a state where a gap between each of the two adjacent beam portions is maintained at an interval determined based on the reference value. The torque sensor according to claim 3, wherein the rigid lifting member maintains the state of the gap with an adhesive. The torque sensor according to claim 3, further comprising: a fixing member for maintaining the rigid lifting member in a state of maintaining the gap. The torque sensor according to claim 1, wherein the strain body is provided between the first region portion and the second region portion at a position other than the plurality of beam portions. For example, the torque sensor according to claim 1, wherein the strain body is provided in the beam portion having a shape that is easier to deform than other beam portions among the plurality of beam portions.