JP5034832B2 - Shear force detector - Google Patents

Description

  The present invention relates to a shearing force detection device capable of measuring shearing force, shearing strain, and the like that can occur between surfaces to be measured that are spaced apart in parallel.

  Detection of mechanical quantities such as force, pressure, and displacement and detection of measurements are indispensable not only for knowing their absolute quantities but also for controlling various machines such as automobiles. Examples of such mechanical quantities include force, pressure, torque, speed, acceleration, position, displacement, impact force, weight mass, vacuum degree, rotational force, vibration, and noise.

For the detection of such a mechanical quantity, a mechanical quantity sensor element that measures through strain (or stress) that changes in accordance with each mechanical quantity is widely used. The mechanical quantity sensor element is generally configured using a pressure resistance effect material.
The pressure resistance effect is a phenomenon in which the electrical resistance of a material changes when applied to a material having a compressive stress, tensile stress, shear stress, hydrostatic pressure, etc., and the material is called a pressure resistance effect material. . An example of a mechanical quantity sensor element using such a pressure resistance effect material and an example of its use are shown in the following patent documents.

JP 2005-172793 A Japanese Patent Laid-Open No. 2004-360782

  By the way, the conventional mechanical quantity sensor element has been mainly used for measuring a vertical load (tensile load or compressive load). Conversely, it has not been used much to measure shear loads. Of course, as shown in FIG. 10, it is also possible to obtain a shear load from the strain amount of the strain generating portion by providing a strain generating portion most sensitive to the shear load for each object to be measured and attaching a strain gauge thereto.

  However, with this method, the shear load can be measured only with a single product and is not versatile. Further, the applied load is usually a composite load in which not only a shear load but also a vertical load is applied, and it has not been easy to accurately detect only the shear load. For example, when a load is detected by attaching a strain gauge to the strain generating portion, the output characteristics of the strain gauge may differ depending on the direction of the applied load. For this reason, even if individually corrected, it is difficult to accurately determine the shear load from the composite load, and even if it is possible, the range is narrow.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a versatile shear force detection apparatus suitable for measurement of shear force such as shear load and shear stress. In particular, it is an object of the present invention to provide a versatile shear force detection device that can remove the influence of vertical force (such as vertical load or vertical stress) and accurately measure only the shear force.

As a result of extensive research and trial and error, the present inventor has come up with a new shearing force detection structure capable of measuring shearing force, and has completed the present invention.
(1) That is, the shearing force detecting apparatus of the present invention includes a first base, a first arm capable of first base and integrally movable extending from the first base to the perpendicular direction, extends from the first base a third arm which faces spaced parallel to the first arm with may first base and integrally movable, a first member made of, are arranged spaced parallel to the first base The second base is disposed between the first arm and the third arm , and extends from the second base in a direction perpendicular to the first base and the third arm so as to be integrated with the second base. A second arm that is movable , and a second member comprising:
Wherein interposed between the first arm and the second arm, the first physical quantity sensor element sensitive to said first arm and said second arm in a direction substantially perpendicular to the compressive forces to be sensitive direction, wherein said A second mechanical quantity sensor element sandwiched between three arms and the second arm and sensitive to the compressive force in the sensitive direction ,
A shearing force that can be generated between parallel measurement surfaces that can be displaced relative to each other in the sensitive direction can be measured.

(2) First, the first base and the second base of the present invention are arranged so as to be movable integrally with each measurement surface between measurement surfaces provided on a part of the measurement target whose shear force is to be measured. Set up. For example, when the parallel measured surfaces are the first measured surface and the second measured surface, the first arm is integrated with the first measured surface, the second arm is integrated with the second measured surface, and each is integrally formed. Attach directly or indirectly via attachments to move.

In this way, when a shearing force is applied to the measurement target, the parallel shearing force generated between the measured surfaces is the first arm orthogonal to the first base, the third arm, and the second arm orthogonal to the second base. an arm through each of which is converted into the vertical force of the sensitive direction of the mechanical quantity sensor element. Then, the (first) mechanical quantity sensor element sandwiched between the first arm and the second arm detects the normal force applied by the first arm and the second arm. Further, the (second) mechanical quantity sensor element sandwiched between the third arm and the second arm detects the normal force applied by the third arm and the second arm. In short, according to the shearing force detection device of the present invention, the parallel shearing force generated between the measurement target surfaces is converted into a vertical force and applied to the mechanical quantity sensor element, and the mechanical quantity sensor element generates the vertical force. By detecting, the shear force which acts on a measuring object is detected exactly.

According to the shearing force detection device of the present invention, the first member, the second member, and the (first and second ) mechanical quantity sensor elements are in one set. There is no need to provide an individual strain generating section, and the shearing force acting on the measurement object can be easily detected as described above only by arranging the shearing force detection device between the surfaces to be measured. Therefore, the shear force detection device of the present invention is very versatile and has a high degree of freedom of use.

(3) By the way, not only a shearing force parallel to these measurement surfaces but also a normal force perpendicular to them can act between the measurement surfaces to be measured. Even when such a composite force acts, according to the shear force detecting apparatus of the present invention, without performing any special correction, it is possible to accurately measure the shear force acting on the measurement object . For example, in the above-described shear force detection device of the present invention, a mechanical quantity sensor element that is sensitive only to the sensitive direction and is substantially insensitive to a direction orthogonal to the sensitive direction is used.
As a result, even if a normal force acts on the measurement target and a normal force other than the shear force acts on the mechanical quantity sensor element, the mechanical quantity sensor element is hardly affected by the shear force. The corresponding output can be performed accurately. That is, only the shearing force can be accurately measured without performing individual correction or the like according to the measurement object. In addition, in this case, since the structure and the measurement system can be simplified, the versatility of the shearing force detection device of the present invention can be further enhanced.

(4) “First”, “second”, “third”, and the like in this specification are merely names for convenience. Further, “orthogonal” or “parallel” may be substantially orthogonal or substantially parallel as long as the operation and function of the present invention are achieved, and is interpreted in a strict sense so that tolerance is a problem. Should not.

  In addition, expressions such as “the mechanical quantity sensor element is sensitive only to the sensitive direction” or “the mechanical quantity sensor element is not affected by the normal force” indicate that the vertical stress or the vertical strain in the direction orthogonal to the sensitive direction is a mechanical quantity sensor. It does not mean that the electrical output from the mechanical quantity sensor element becomes completely zero when acting on the element. The above expression is sufficient if the output is within a substantially negligible range as compared with the output when normal stress or normal strain acts in the sensitive direction. In other words, the output in the direction perpendicular to the output in the sensitive direction with respect to the input may be within ± 5% of the output in the sensitive direction. Of course, it is more preferable that it is within ± 3%.

(5) Incidentally, the shearing force (F), shearing stress (τ), and shearing strain (γ) are represented by the relationship of τ = F / A = γG using the lateral elastic modulus G and the area (A) of the measured surface. It is in. Then, there is essentially no difference between “detecting shear force”, “detecting shear stress”, and “detecting shear strain” between them. Result in problems. Therefore, for the sake of convenience, in the present invention, it is called a “shearing force detection device”, but this can also be called a “shearing stress detection device” or a “shearing strain detection device”.

  Furthermore, the present invention adds a calculation processing means for processing an electrical signal from the mechanical quantity sensor element, a display means for displaying the result, and the like to the configuration around the mechanical quantity sensor element described above, thereby measuring a measuring device for shearing force, etc. Or you may grasp | ascertain as a measurement system. The arithmetic processing means is, for example, a microcomputer or an ECU of an automobile, and the display means is a display, an instrument display board of the automobile, or the like.

The present invention will be described in more detail with reference to embodiments of the invention. It should be noted that which embodiment is best depends on the target, required performance, and the like.
<Structure of shear force detector>
(1) The shearing force detection device of the present invention basically includes a first member, a second member, and a mechanical quantity sensor element.
The first member includes a first base, with a first arm may first base and integrally movable extend perpendicular from the first base may first base and integrally movable extending from the first base article third Ru arm and Tona which faces spaced parallel to the first arm. In addition , the second member is disposed between the first base and the third arm, the second base disposed in parallel with the first base, and disposed between the first arm and the third arm. The second arm extends in a direction facing the three arms and can move integrally with the second base . As long as the first base, the first arm, and the third arm are substantially orthogonal to each other, an integral product or an assembly fixed by screws, press-fitting, or the like may be used. Moreover, those cross-sectional shapes may be anything such as a plate shape, a prismatic shape, or a polygonal shape. The same applies to the second base and the second arm.
Further, depending on the shape of the measurement target, the state of the surface to be measured, and the like, an attachment may be provided on the first base or the second base to facilitate attachment of the shearing force detection device of the present invention.

(2) a first mechanical quantity sensor element that is sandwiched between the first arm and the second arm and is sensitive to a compressive force having a sensitive direction in a direction substantially orthogonal to the first arm and the second arm ; and a third arm; There may be a plurality of second mechanical quantity sensor elements sandwiched between the second arms and sensitive to the compressive force in the sensitive direction in series or in parallel . By providing a plurality of mechanical quantity sensor elements, the shear force can be measured more accurately.

With the above configuration, at least one of the first mechanical quantity sensor element and the second mechanical quantity sensor element is provided even if the direction of the shearing force generated in the measurement object is changed in the sensitive direction even though the structure is simple. By means of this, the shearing force is detected. For this reason, stable detection of the shearing force is possible, and the versatility of the shearing force detection device is enhanced.

(3) However, even if there is only one mechanical quantity sensor element, if the compression force (preload) is applied to the mechanical quantity sensor element in advance, the direction of the shearing force acting on the mechanical quantity sensor element changes. However, as long as the preload remains, the mechanical quantity sensor element can detect the shearing force. Therefore, even when the direction of the shearing force acting on the measurement object changes, such a shearing force detection device can widely detect the shearing force.
In particular, as described above, the first member of the shearing force detection device of the present invention includes the first arm and the third arm, and the first physical quantity sensor element includes the second arm and the second arm. It is more preferable that the mechanical quantity sensor element is in a state where a preload is applied by the third arm and the second arm.

  In this case, when a shearing force acts between the first member and the second member, one of the compressive forces acting on the first mechanical quantity sensor element and the second mechanical quantity sensor element is increased, and the other is reduced. Show the trend. Here, if the zero point correction is performed accurately with the preload applied, and the difference between the outputs of the two mechanical quantity sensor elements is taken, the input shear force is 0.4, compared to the case where there is only one mechanical quantity sensor element. The output obtained for is doubled. In addition, by taking the difference, a noise portion caused by a disturbance or the like common to both is canceled out, and it becomes possible to detect and measure a shearing force with higher accuracy.

<Mechanical quantity sensor element>
(1) In the present invention, regardless of the type or form of the mechanical quantity sensor element, the mechanical quantity sensor element includes, for example, a pressure-sensitive body capable of changing electrical characteristics by applying a compressive force in a specific direction, It is preferable that the pressure sensitive body comprises an electrically insulating insulator disposed on both sides in the specific direction and an electrode for taking out an electrical signal that changes in accordance with a compressive force applied from the pressure sensitive body. is there.
As described above, it is preferable that the mechanical quantity sensor element is sensitive only in the sensitive direction and is not substantially sensitive in the direction orthogonal to the sensitive direction, because the shear force of the surface to be measured can be detected accurately and efficiently.

(2) By the way, as such a mechanical quantity sensor element, for example, an electrical insulating material in which the pressure sensitive body is a matrix, and a pressure resistance effect material dispersed in the electrical insulating material and having conductivity There is something to be.
As this pressure resistance effect material, for example, there are ruthenium oxide (RuO ₂ ), lead ruthenate, or perovskite type complex oxide (La _1-X Sr _X MnO ₃ : 0 <x <0.4). These may be used alone or in combination of two or more.

An example of the electrically insulating material that is a matrix of the pressure sensitive body is lead borosilicate glass. The insulator is, for example, ZrO ₂ (zirconia), Al ₂ O ₃ (alumina), MgAl ₂ O ₄ , SiO ₂ , 3Al ₂ O ₃ .2SiO ₂ , Y ₂ O ₃ , CeO ₂ , La ₂ O _3. , Si ₃ N ₄ or the like. In addition, a metal or the like whose surface is covered with these to be electrically insulated can be used as the insulator.

In the pressure-sensitive body, for example, the pressure resistance material is preferably dispersed in a ratio of 10 to 50 parts by weight with respect to 100 parts by weight of the electrically insulating material. If the pressure resistance effect material is too small, the contact between the conductive particles such as RuO ₂ is reduced, the resistance value of the pressure sensitive body becomes very large, and the sensitivity of the mechanical quantity sensor element can be lowered. On the other hand, if the pressure resistance effect material is excessive, the contact between the conductive particles such as RuO ₂ increases, the resistance value of the pressure sensitive body becomes very small, and the sensitivity of the mechanical quantity sensor element also decreases. Can do.

  In addition, the mechanical quantity sensor element is also described in detail in the descriptions of JP-A-2003-63868, JP-A-2005-172793, JP-A-2007-107963, etc. that have already been filed by the present inventor. It is.

The present invention will be described more specifically with reference to examples.
<Shearing force detection device>
(1) Structure FIG. 1 shows a shearing force detection device M that is an embodiment of the present invention. The shear force detection device M includes a pedestal 1 (first member), a pedestal 2 (second member), a mechanical quantity sensor element S 1 (first mechanical quantity sensor element), and a mechanical quantity sensor element S 2 (second mechanical quantity). Sensor element).

  The pedestal 1 is a prismatic member having a U-shaped cross section made of iron. That is, the base 1 is formed by integrally forming a base 11 (first base), an arm 12 (first arm) and an arm 13 (third arm) extending perpendicularly from both ends thereof. The base 11 is provided with attachment holes 111 and 112 for attaching the shearing force detection device M to an attachment or a measurement target. Further, flat bolts 5 and 6 having flat tip surfaces for applying a preload (preload) to the mechanical quantity sensor elements S1 and S2 are screwed into the arm 12 and the arm 13, respectively.

The pedestal 2 is a prismatic member having a T-shaped cross section made of iron. That is, the base 2 is formed by integrally forming a base 21 (second base) and an arm 22 (second arm) extending perpendicularly from the center thereof. The base 21 is provided with mounting holes 211 and 212 for mounting the shearing force detection device M to an attachment or a measurement target.
The mechanical quantity sensor element S <b> 1 is sandwiched between the arm 12 of the base 1 and the arm 22 of the base 2 via the shim 7. The mechanical quantity sensor element S <b> 2 is sandwiched between the arm 13 of the base 1 and the arm 22 of the base 2 via the shim 8.

  One side of each of the mechanical quantity sensor elements S1 and S2 is bonded and fixed to both sides of the arm 22 with a thermosetting adhesive at the bonding surface b. Further, the other surface side of each of the mechanical quantity sensor elements S1 and S2 is bonded to one surface of the shims 7 and 8 with a thermosetting adhesive on the bonding surface b. The shims 7 and 8 are iron thin discs. By these shims 7 and 8, the preload by the screwed flat bolts 5 and 6 acts equally on the mechanical quantity sensor elements S1 and S2. Note that the pedestal 1 and the pedestal 2 are eventually connected by the application of a load by the flat bolts 5 and 6.

Moreover, you may carry out by press injection as a method of attaching a sensor between the arm 12 and the arm 22, and between the arm 13 and the arm 22. FIG. That is, the distance between the arm 12 and the arm 13 of the base 1, the distance of the arm 22 and the shim 7,8 and the mechanical quantity sensor element S1, S2 mounted on both sides (length) than shorter (several to several tens of When the shim 7 and 8 attached to the arm 22 and the mechanical quantity sensor elements S1 and S2 are attached , the distance between the arm 12 and the arm 13 is mechanically increased using a jig, Thereafter, the arm 22 is attached, the jig is removed, and it is attached by press fitting.
The detailed structure of the mechanical quantity sensor elements S1 and S2 used in the shearing force detection device M is shown in FIG. The mechanical quantity sensor elements S1 and S2 include a pressure sensitive body, an insulator covering both sides thereof, and electrodes provided on both ends of the pressure sensitive body. This pressure sensitive member is obtained by dispersing RuO2 particles as a pressure resistance effect material in glass (electrical insulating material) as a matrix. The insulator is made of ZrO2. The electrode is silver. This electrode is connected to a measurement system such as an oscilloscope (not shown). Thereby, when the load in the direction shown in FIG. 2 is applied to the mechanical quantity sensor element, the resistance value of the pressure sensitive body changes, and the applied load is measured from the change amount. For reference, an example of output characteristics (load characteristics) of the mechanical quantity sensor elements S1 and S2 used in this embodiment is shown in FIG. Incidentally, the mechanical quantity sensor elements S1 and S2 have a prismatic shape of 2 × 2 × 2.5 (mm).

(2) Manufacturing Method of Mechanical Quantity Sensor Element The mechanical quantity sensor elements S1 and S2 are formed by integrally forming a pressure sensitive body and an insulator by firing. This manufacturing method will be outlined.
First, two zirconia plates (manufactured by Tosoh Corporation) are prepared as insulators, and a resistance paste (manufactured by ESL Co., Ltd.) containing RuO2 particles having a particle diameter of 0.2 to 5 [mu] m and glass as a pressure-sensitive material. 3414A) is prepared.

  This resistance paste is screen-printed on one side of a zirconia plate and baked by holding at a temperature of 850 ° C. for 10 minutes. Similarly, the resistance paste is baked on one side of another zirconia plate. By this baking, the binder and the organic solvent are evaporated from the resistance paste, and a pressure sensitive body in which conductive particles made of conductive material (RuO2) are dispersed in a matrix of an electrically insulating material (glass) is formed on the surface of the zirconia plate. It was done. The thickness of the pressure sensitive body was 10 μm.

The two zirconia plates having the pressure-sensitive body formed on the surface in this way were superposed on the surfaces on which the pressure-sensitive body was formed, and baked at a temperature of 850 ° C. for 10 minutes. Thereby, the two zirconia plates were integrated. After firing, it was processed into a desired size, and mechanical quantity sensor elements S1 and S2 having a sandwich structure in which a pressure-sensitive body was sandwiched between insulators (zirconia plates) as shown in FIG. 2 were obtained.
Further, a silver paste (manufactured by Shoei Chemical Industry Co., Ltd.) was applied to the pair of side surfaces where the pressure sensitive bodies of the mechanical quantity sensor elements S1, S2 were exposed, and heated at a temperature of 850 ° C. for 10 minutes. Thereby, the silver paste was baked on the pressure sensitive body, and a pair of electrodes sandwiching the pressure sensitive body was formed.
The mechanical quantity sensor elements S1 and S2 were obtained as described above.

<Evaluation>
(1) FIGS. 4 and 5 show the attachment of the attachments A1 and A2 to be experimentally measured using the attachment holes 111 and 112 and the attachment holes 211 and 212 to the above-described shear force detection device M. . FIG. 4 shows a state in which a shear load is applied to the shear force detection device M. FIG. 5 shows a state in which a vertical load is applied to the shearing force detection device M.
In each of these cases, the relationship between the input load applied to the shear force detection device M and the output loads (sensor output loads F _S1 and F _S2 ) of the mechanical quantity sensor elements S1 and S2 was obtained by an autograph. Further, the relationship between the output load (F _t = F _S1 −F _S2 ) calculated from each sensor output load and the input load was also obtained. These results are shown in FIGS.

Note that a preload of about 20 kg was previously applied to the mechanical quantity sensor elements S1 and S2 by the flat bolts 5 and 6. In addition, the zero point correction was performed so that the outputs of the mechanical quantity sensor elements S1 and S2 were zero when no load was applied to the shear force detection device M.
Needless to say, what is obtained from the mechanical quantity sensor elements S1, S2 is a change in resistance value (electrical signal). Therefore, the correspondence between the electrical signals output from the mechanical quantity sensor elements S1 and S2 and the input load has been obtained by calibration in advance (FIG. 3).

(2) First, from FIGS. 6 and 7, the sensor output loads (F _S1 , F _S2 ) of the mechanical quantity sensor elements S 1, _{S 2} and the output load (F _t ) obtained from both are relative to the shear input load. It turns out that it increases or decreases almost linearly. Therefore, it was confirmed that the shearing load (shearing force) acting between the measurement target surfaces to be measured can be accurately detected by using the shearing force detection device M of the present embodiment.

By the way, as shown in FIG. 6, the sensor output loads (F _S1 , F _S2 ) of the respective mechanical quantity sensor elements S1, S2 when a shear load is inputted have non-linearity (NL: Non-Linear). The full scale (FS) has a sufficiently small hysteresis of 4% FS or less and a hysteresis of 2% FS or less. In particular, as shown in FIG. 7, by calculating the shear load as F _t = F _S1 −F _S2 , the non-linearity becomes 2% FS or less and the hysteresis becomes 2% FS or less.

(3) Next, from FIGS. 8 and 9, the sensor output loads (F _S1 , F _S2 ) of the mechanical quantity sensor elements S 1, _{S 2} and the output load (F _t ) obtained from both are the vertical input loads. On the other hand, it was found that there was little change. Therefore, if the shear force detection device M of the present embodiment is used, even if a vertical load (vertical force) is applied between the measurement target surfaces, the influence is removed and only the shear load is accurately measured. It was confirmed that it could be detected well.
Thus, according to the shearing force detection apparatus concerning this invention, it was confirmed that only a shearing load can be measured correctly, without receiving the influence of a perpendicular | vertical load etc. substantially.

It is a figure which shows the composition of the shearing force detection apparatus which is one Example which concerns on this invention. It is a figure which shows the structure of the mechanical quantity sensor element used with the shearing force detection apparatus. It is an example which shows the output characteristic of the mechanical quantity sensor element single-piece | unit. It is a figure which shows the case where a shear load acts on a shear force detection apparatus. It is a figure which shows the case where a vertical breaking load acts on a shearing force detection apparatus. It is a figure which shows the relationship between a shear input load and a sensor output load. It is a figure which shows the relationship between a shear input load and an output load. It is a figure which shows the relationship between a vertical input load and a sensor output load. It is a figure which shows the relationship between a vertical input load and an output load. It is a figure which shows the conventional shear load detection apparatus.

Explanation of symbols

1 pedestal (first member)
2 Pedestal (second member)
11, 21 Base 12, 13, 22 Arm S1, S2 Mechanical quantity sensor element M Shear force detection device

Claims (6)

A first base, a first arm extending perpendicularly from the first base and movable integrally with the first base; and extending from the first base and movable integrally with the first base; A first member comprising a third arm facing and spaced apart from one arm in parallel ;
A second base disposed apart from and parallel to the first base; and the first arm and the third arm disposed between the first arm and the third arm in a direction perpendicular to the second base . a second arm capable of second base and integrally movable extending in a direction opposed to the arm, and a second member made of,
Is sandwiched between the second arm and the first arm, a first physical quantity sensor element sensitive to said first arm and said second arm in a direction substantially perpendicular to the compressive forces to be sensitive direction,
A second mechanical quantity sensor element sandwiched between the third arm and the second arm and sensitive to the compressive force in the sensitive direction ,
A shearing force detection device capable of measuring a shearing force that can be generated between parallel measurement surfaces that can be relatively displaced in the sensitive direction. The shear force detection device according to claim 1 , wherein the mechanical quantity sensor element is in a state in which a preload is applied.   The shear force detection device according to claim 1, wherein the mechanical quantity sensor element is sensitive only to the sensitive direction and is not substantially sensitive to a direction orthogonal to the sensitive direction. The mechanical quantity sensor element includes a pressure-sensitive body capable of changing electrical characteristics by applying a compressive force in a specific direction;
An insulator having electrical insulation disposed on both sides in the specific direction of the pressure sensitive body;
The shearing force detection device according to any one of claims 1 to 3 , comprising an electrode that extracts an electric signal that changes in accordance with an applied compressive force from the pressure-sensitive body. The pressure-sensitive body includes an electrically insulating material serving as a matrix,
The shear force detection device according to claim 4 , comprising a pressure resistance effect material dispersed in the electrically insulating material and having conductivity. 6. The shear force detecting device according to claim 5 , wherein the pressure resistance effect material is made of ruthenium oxide (RuO ₂ ) or a perovskite complex oxide (La _1-X Sr _X MnO ₃ : 0 <x <0.4).

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