JP2010008343A - Force sensor and process for assembling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure in which no failures occur in a diaphragm section even when excessive force is applied. <P>SOLUTION: A conductive diaphragm section 210 supported by a pedestal 220 therearound is provided, and electrodes E11 to E15 are provided on an upper surface of a base section 410 disposed below the diaphragm section 210. Above an upper surface of the diaphragm section, a board-like force receptor 110 is connected via a columnar connection section 120. Because the diaphragm section 210 bends when external force is applied to the board-like force receptor 110, the external force is detected according to values of capacitance with respect to the electrodes E11 to E15. The board-like force receptor 110 includes lower hole sections H11 and H12 and upper hole sections H21 and H22 in each of which pillar members 31 and 32 and stopper members 41 and 42 are disposed. Each of the pillar members 31 and 32 has its lower end attached to the pedestal 220. Displacement of the board-like force receptor 110 is restricted by the upper surface of the pedestal 220 and the stopper members 41 and 42. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a force sensor, and more particularly to a force sensor of a type that causes a diaphragm portion to bend based on an external force to be detected and electrically detects the deformation state.

  Practical use of a force sensor that detects the magnitude and direction of the applied external force by applying an external force to the flexible diaphragm and electrically detecting the deformation state of the diaphragm. Has been. This type of sensor has a relatively simple structure and can be manufactured at a low cost. Therefore, it is used as a mass-produced product in various industrial fields. Further, if a force based on acceleration is detected as an external force, it can be applied to an acceleration sensor, and if a Coriolis force is detected as an external force, it can be applied to an angular velocity sensor.

  As a method for electrically detecting the deformation state of the diaphragm portion, a method using a capacitive element, a method using a piezoresistive element, a method using a piezoelectric element, and the like have been proposed. By arranging each of these elements at a plurality of locations and detecting the displacement of each position of the diaphragm portion as an electrical signal, the magnitude of each coordinate axis direction component of the applied external force in the XYZ three-dimensional orthogonal coordinate system is independent. Can be detected.

  For example, in Patent Documents 1 and 2 below, it is possible to independently detect forces acting in the coordinate axis directions by detecting displacement of each part of the diaphragm part using a capacitance element. A multidimensional force sensor is disclosed. Patent Documents 3 and 4 disclose multidimensional force sensors that detect forces in the directions of the respective coordinate axes based on changes in electrical resistance of piezoresistive elements provided at individual positions of the diaphragm portion. In Patent Documents 5 and 6, the displacement of each part of the diaphragm portion is detected based on the electric charge generated in the piezoelectric element, and the force based on the acceleration acting as an external force or the Coriolis force is detected, so that A multi-axis sensor that detects angular velocity around each coordinate axis is disclosed.

Further, in Patent Documents 7 and 8 below, by detecting the bending generated in a plurality of diaphragm portions separately and independently, the moment acting around the XYZ axis is detected together with the force acting in the XYZ axis direction. A six-axis sensor capable of the above is disclosed.
JP-A-4-148833 JP 2001-165790 A JP-A-6-174571 JP 2004-69405 A JP-A-8-226931 JP 2002-71705 A JP 2004-325367 A JP 2004-354049 A

  In the force sensor of the type described above, in order to increase the force detection sensitivity, it is necessary to reduce the thickness of the diaphragm portion or to make it flexible and to increase its flexibility. On the other hand, in order to increase the robustness, it is necessary to reduce the flexibility by increasing the thickness of the diaphragm portion or by using a material that is difficult to bend. For this reason, when designing a force sensor, a diaphragm unit matching the force measurement range according to the application is incorporated.

  However, even if a force sensor corresponding to a predetermined measurement range according to the application is designed, in practice, an external force within the measurement range does not always act, and an excessive external force is applied for some reason. It is inevitable that the situation will end up. Thus, if an excessive external force that far exceeds the measurement range acts on the force sensor, excessive deflection exceeding the elastic deformation limit will occur in the diaphragm, and after the external force is removed However, there is a problem that the shape of the diaphragm portion does not return to its original shape, or the diaphragm portion is damaged. In particular, in the case of a high-sensitivity force sensor incorporating a delicate diaphragm portion that causes bending even with a slight external force, the diaphragm portion is likely to be damaged when an excessive external force is applied. For this reason, in practical use, it is necessary to design a product in consideration of the balance between detection sensitivity and robustness, and it is necessary to pay sufficient attention to the handling of products that place importance on detection sensitivity.

  Therefore, an object of the present invention is to provide a force sensor having a structure that does not cause a failure in a diaphragm portion even when an excessive external force is applied.

(1) According to a first aspect of the present invention, there is provided a diaphragm portion made of a thin plate having flexibility, a pedestal that supports the periphery of the diaphragm portion, a disk-shaped force receiving body disposed above the diaphragm portion, A columnar connecting part that connects the diaphragm part and the disk-shaped power receiver, and a detection that detects the force acting on the disk-shaped power receiver in a state where the base is fixed by electrically detecting the deformation state of the diaphragm part. A force sensor comprising:
The upper surface of the diaphragm part and the upper surface of the pedestal form a first reference plane, and the lower surface of the disk-shaped force receiving member forms a second reference plane opposite to the first reference plane. In a state in which is not acting, the first reference plane and the second reference plane are configured to be maintained in a parallel state with a predetermined gap,
A lower end of a column member extending vertically upward with respect to the first reference plane is fixed at a predetermined position on the upper surface of the pedestal, and the disc-shaped force receiving body is placed on the upper layer by a third reference plane parallel to the second reference plane. When partitioning into a part and a lower layer part, the strut member has a length so that the upper end reaches the upper layer part,
A lower layer hole having an inner diameter larger than the outer diameter of the column member is formed at a position where the column member extends in the lower layer portion of the plate-shaped force receiving member, and above the lower layer hole portion of the upper layer portion of the disk-shaped force receiving member. An upper layer hole portion having an inner diameter larger than the inner diameter of the lower layer hole portion is formed at a position adjacent to, and the support member is inserted through the lower layer hole portion, and its upper end is above the third reference plane by a predetermined gap dimension. Located in
In the upper layer hole, a stopper member having an outer diameter larger than the inner diameter of the lower layer hole and smaller than the inner diameter of the upper layer hole and fixed to the upper end of the support member is arranged.

(2) According to a second aspect of the present invention, in the force sensor according to the first aspect described above,
Prepare a single substrate with a cavity formed by hollowing out the central portion of the lower surface, and form a diaphragm portion with a thin portion remaining above the cavity portion of this substrate, and a pedestal with a peripheral portion surrounding the cavity portion In which the upper surface of the substrate is the first reference plane.

(3) According to a third aspect of the present invention, in the force sensor according to the first or second aspect described above,
The disk-shaped force receiving body and the columnar connection portion are made of an integral structure made of the same material, and the columnar connection portion is configured by a downward projecting portion continuous from the lower surface of the disk-shaped force receiving body. .

(4) According to a fourth aspect of the present invention, in the force sensor according to the first to third aspects described above,
A plurality of electrodes arranged to face the diaphragm portion at a predetermined interval below the conductive diaphragm portion, a base portion for supporting and fixing these electrodes, and each of the diaphragm portion and the plurality of electrodes And a detection circuit configured to electrically detect a capacitance between them.

(5) According to a fifth aspect of the present invention, in the force sensor according to the first to fourth aspects described above,
The lower layer hole is made of a cylindrical cavity having an inner diameter φ10, the upper layer hole is made of a columnar cavity having an inner diameter φ20, and the column member is made of a columnar member having an outer diameter φ30, and a stopper member Consists of a cylindrical member having an outer diameter of φ40,
In a state where no force is applied to the disk-shaped force receiving member, the concentric arrangement is made such that the central axes of the respective cylinders constituting the lower layer hole portion, the upper layer hole portion, the column member, and the stopper member coincide with each other, and φ30 <φ10 < In this case, φ40 <φ20 is set.

(6) According to a sixth aspect of the present invention, in the force sensor according to the first to fifth aspects described above,
The upper surface center position of the diaphragm part and the lower surface center position of the disk-shaped force receiving body are connected by a single columnar connection part.

(7) According to a seventh aspect of the present invention, in the force sensor according to the first to sixth aspects described above,
When two arrangement axes that are orthogonal to each other at the center point of the upper surface of the diaphragm portion and a circle with a radius r centered on the center point are defined on the first reference plane, the defined circle and two Four strut members are arranged at four intersection positions where the arrangement axis intersects, and a stopper member is fixed to the upper end of each strut member,
The disc-shaped force receiving member is provided with a lower layer hole and an upper layer hole at four locations suitable for inserting four support members, respectively.

(8) The eighth aspect of the present invention is the force sensor according to the first to seventh aspects described above,
In the state where no force is applied to the disk-shaped force receiving body, the lower layer hole is disposed so that the entire lower layer hole is positioned above the pedestal.

(9) According to a ninth aspect of the present invention, in the force sensor according to the first to eighth aspects described above,
The portion of the wall surface that forms the upper layer hole portion that faces the surface of the stopper member, the portion of the surface of the stopper member that faces the wall surface that forms the upper layer hole portion, and the column member of the wall surface that forms the lower layer hole portion At least one of a portion facing the surface of the support member and a portion facing the wall surface forming the lower layer hole portion of the surface of the support member, and has a height that does not reach the facing surface, and a predetermined pressure Protrusions made of a material that is plastically deformed when the is applied are provided.

(10) According to a tenth aspect of the present invention, in the force sensor according to the first to eighth aspects described above,
The portion of the wall surface that forms the upper layer hole portion that faces the surface of the stopper member, the portion of the surface of the stopper member that faces the wall surface that forms the upper layer hole portion, and the column member of the wall surface that forms the lower layer hole portion At least one of the portion facing the surface of the column member and the portion facing the wall surface forming the lower layer hole portion of the surface of the support member has a thickness that does not reach the facing surface, and a predetermined pressure is applied. When applied, the optical characteristics change, and a film layer made of a material having the property of maintaining the optical characteristics after the change is provided even after the pressure is removed.

(11) The eleventh aspect of the present invention is the force sensor according to the first to tenth aspects described above,
The strut member and the stopper member are constituted by a locking pin that forms an integral structure,
A shaft hole is formed in the central axis of the locking pin, and a female screw hole is formed at a position for fixing the column member on the upper surface of the base.
The locking pin is fastened and fixed to the pedestal by inserting and screwing a bolt with a male screw formed into the shaft hole.

(12) A twelfth aspect of the present invention is the force sensor assembly method according to the eleventh aspect described above,
Prepare a cylindrical jig whose inner diameter matches the outer diameter of the stopper member of the locking pin and whose outer diameter matches the inner diameter of the upper layer hole,
In a state where the cylindrical jig is fitted into the upper layer hole and the locking pin is fitted inside the cylindrical jig, the locking pin is fastened and fixed to the pedestal with a bolt,
Thereafter, the locking pin is attached by removing the cylindrical jig.

  According to the force sensor of the present invention, the displacement of the disk-shaped force receiving body is limited within a predetermined range by the upper surface of the pedestal, the column member, and the stopper member. The displacement of the force body is kept within a safe tolerance. Therefore, even if an excessive external force is applied, a structure in which no failure occurs in the diaphragm portion can be realized. Further, according to the method for assembling the force sensor according to the present invention, when the stopper member is fixed on the pedestal, accurate positioning is performed by the cylindrical jig. The range dimension can be set accurately.

  Hereinafter, the present invention will be described based on the illustrated embodiments.

<<< §1. Structure of basic embodiment >>
FIG. 1 is a side sectional view of a force sensor according to a basic embodiment of the present invention, and FIG. 2 is a top view of the force sensor. Here, for convenience of explanation, an origin O is defined at the center of gravity of the plate-shaped force receiving body 110, and an XYZ three-dimensional orthogonal coordinate system having an X axis, a Y axis, and a Z axis in each direction as illustrated is defined. The following explanation will be given. FIG. 1 is a side sectional view showing a state in which the force sensor shown in FIG. 2 is cut along the XZ plane, and the Y-axis is oriented in a direction perpendicular to the paper surface.

  FIG. 3 is a side sectional view showing a state where the force sensor shown in FIG. 1 is disassembled into parts. Here, first, the structure of each part will be described with reference to FIG. As illustrated, the basic components of the force sensor are a first substrate 100, a second substrate 200, a third substrate 300, and a detection unit 400. Here, the first substrate 100, the second substrate 200, and the third substrate 300 are disk-shaped components having the same diameter, and the detection unit 400 is a disk-shaped component having a smaller diameter. It is a component.

  The first substrate 100 is constituted by a plate-shaped force receiving body 110 and a columnar connecting portion 120. The disk-shaped force receiving body 110 is a component having a disk shape as a whole, and columnar holes are formed at four locations as will be described later. The diameter of the hole is different between the lower layer portion 10 and the upper layer portion 20 of the disk-shaped force receiving body 110. For example, in the side cross-sectional view shown in FIG. 3, the diameter φ10 of the lower layer holes H11 and H12 is set smaller than the diameter φ20 of the upper layer holes H21 and H22, and at the boundary between the lower layer part 10 and the upper layer part 20 A step is formed.

  The columnar connecting portion 120 is a columnar member having a height L1 joined to the lower surface central portion of the disc-shaped force receiving member 110, and the central axis thereof is located on the Z axis. In the case of the example shown here, the disk-shaped force receiving body 110 and the columnar connection part 120 are made of an integral structure of the same material, and the columnar connection part is formed by a downward projecting portion continuous from the lower surface of the disk-shaped force receiving body 110. 120 is configured.

  FIG. 4 is a top view of the first substrate 100. As shown by a broken line in the figure, the columnar connecting portion 120 is located at the center of the lower surface of the disk-shaped force receiving body 110. Further, as shown in the figure, the lower layer hole H11 and the upper layer hole H21 are formed in the positive part of the X axis, the lower layer hole H12 and the upper layer hole H22 are formed in the negative part of the X axis, and the positive part of the Y axis is formed. The lower layer hole portion H13 and the upper layer hole portion H23 are formed in this portion, and the lower layer hole portion H14 and the upper layer hole portion H24 are formed in the negative portion of the Y axis. All of the four lower layer holes H11 to H14 constitute a cylindrical cavity of the same size. Similarly, all of the four upper layer holes H21 to H24 form a cylindrical cavity of the same size.

  On the other hand, the second substrate 200 shown in FIG. 3 is configured by punching a central portion of the lower surface of one disk-shaped substrate into a cylindrical shape having a diameter φH. As shown in FIG. 3, a cylindrical hollow portion H having a diameter φH is formed on the lower surface side of the second substrate 200. The thin portion remaining above the hollow portion H constitutes the diaphragm portion 210, and the peripheral thick portion (the peripheral portion surrounding the hollow portion H) constitutes the base 220. FIG. 5 is a bottom view of the second substrate 200, and clearly shows a state where an annular pedestal 220 supports the periphery of a diaphragm portion 210 made of a thin disc.

  The diaphragm unit 210 is a flexible thin plate, and the detection sensitivity of the force sensor depends on the degree of flexibility of the diaphragm unit 210. Usually, as the thickness of the diaphragm portion 210 is reduced, the flexibility is increased and the detection sensitivity is improved, but conversely, the robustness is lowered and is easily damaged.

  As shown in FIG. 3, the upper surface of the diaphragm part 210 and the upper surface of the pedestal 220 form the same plane (the upper surface of the second substrate 200). Here, for convenience of explanation, the upper surface of the second substrate 200 is referred to as a first reference plane S1. Similarly, the lower surface of the disc-shaped force receiving member 110 is referred to as a second reference plane S2, and the boundary surface between the lower layer portion 10 and the upper layer portion 20 of the disc-shaped force receiving member 110 is referred to as a third reference plane S3. To do. In a state where no force is applied to the disk-shaped force receiving body 110, the first reference plane S1 and the second reference plane S2 are in a parallel state. On the other hand, the second reference plane S2 and the third reference plane S3 are always parallel.

  The third substrate 300 functions as a support substrate for fixing the pedestal 220 and the detection unit 400. In the example shown here, the third substrate 300 is a simple disk. Practically, a part of the housing of the device using this force sensor can be used as it is as the third substrate 300.

  The detection unit 400 is a component having a function of electrically detecting the deformation state of the diaphragm unit 210, and functions to detect a force acting on the disk-shaped force receiving body 110 in a state where the base 220 is fixed. . In the case of the embodiment shown here, the detection unit 400 is configured by a columnar base 410, five electrodes E11 to E15 formed on the upper surface thereof, and a detection circuit (not shown).

  FIG. 6 is a top view showing a state in which the detection unit 400 is attached on the third substrate 300. As shown in the figure, a cylindrical base 410 is placed on a third substrate 300 made of a disk, and five electrodes E11 to E15 are arranged on the upper surface thereof. The base 410 is a cylindrical structure having a size that can be accommodated in the cavity H provided in the second substrate 200, and is made of an insulating material so that the electrodes E11 to E15 are not short-circuited to each other. Has been.

  The five electrodes E <b> 11 to E <b> 15 are layers made of a conductive material disposed at a position facing the diaphragm portion 210. On the other hand, in the case of the embodiment shown here, the diaphragm portion 210 is also made of a conductive material, and a total of five sets of capacities are formed by the five electrodes E11 to E15 and the portions of the diaphragm portion 210 facing the electrodes. Elements C11 to C15 are formed. As described in §3, if the capacitance values of the five capacitive elements C11 to C15 are measured by a detection circuit (not shown), the deformation state of the diaphragm section 210 can be grasped, and the disk-shaped power receiving body The direction and magnitude of the external force acting on 110 can be detected.

  In the force sensor according to the present invention, the support members 31, 32 and the stopper members 41, 42 shown in the upper part of FIG. The support members 31 and 32 are columnar members having a diameter φ30, and the stopper members 41 and 42 are columnar members having a larger diameter φ40. As shown in the figure, the stopper member 41 is fixed at a concentric position at the upper end of the column member 31, and the stopper member 42 is fixed at a concentric position at the upper end of the column member 32.

  The structure of each component shown in FIG. 3 has been described above. This force sensor is configured by joining these components to each other. That is, as shown in FIG. 6, the base portion 410 is placed and fixed on the center portion of the third substrate 300, and the second substrate 200 is placed thereon, and the bottom surface of the pedestal 220 is placed on the third substrate. Bonded to the top surface of 300. Further, the first substrate 100 is placed on the second substrate 200, and the lower surface of the columnar connecting portion 120 is bonded and attached to the center of the upper surface of the diaphragm portion 210. Finally, the column members 31 and 32 with the stopper members 41 and 42 fixed to the upper ends are inserted into the holes of the plate-shaped force receiving body 110, and the lower surface thereof is fixed to the upper surface of the pedestal 220. 1, the force sensor shown in FIG. 2 is completed.

  As shown in FIG. 1, between the upper surface (first reference plane S1) of the second substrate 200 and the lower surface (second reference plane S2) of the plate-shaped force receiving body 110, the columnar connecting portion 120 is provided. A gap corresponding to the length L1 is secured. Further, the upper ends of the support members 31 and 32 are positioned above the boundary surface (third reference plane S3) between the lower layer portion 10 and the upper layer portion 20 of the disc-shaped force receiving member 110 by a predetermined gap dimension L2. Therefore, a gap having a dimension L2 is also secured between the lower surfaces of the stopper members 41 and 42 and the bottom surfaces of the upper layer holes H21 and H22.

  Although not all of them are shown in the side sectional views of FIGS. 1 and 3, in fact, as shown in the top view of FIG. Are formed, and a column member and a stopper member are inserted into each hole, and the lower surface of each column member is fixed to the upper surface of the pedestal 220. That is, in FIG. 2, the column member 31 and the stopper member 41 are inserted into the lower layer hole H11 and the upper layer hole H21, and the column member 32 and the stopper member 42 are inserted into the lower layer hole H12 and the upper layer hole H22. Is inserted into the lower layer hole H13 and the upper layer hole H23, and the column member 33 and the stopper member 43 are inserted into the lower layer hole H14 and the upper layer hole H24. Is done.

  In the top view of FIG. 2, quadruple concentric circles are drawn at each position of the four holes. The innermost broken line circle indicates the outer diameter (φ30) of the support member, the outer broken line circle indicates the inner diameter (φ10) of the lower layer hole, and the outer solid line circle indicates the outer diameter of the stopper member ( φ40), and the outermost solid line indicates the inner diameter (φ20) of the upper layer hole. Here, φ30 <φ10 <φ40 <φ20.

  Quadruple concentric circles are drawn in the top view because each lower layer hole is formed of a cylindrical cavity having an inner diameter φ10, each upper layer hole is formed of a columnar cavity having an inner diameter φ20, and each column member is In the state where each stopper member is made of a columnar member having an outer diameter φ40 and no force is applied to the disk-shaped force receiving body 110, This is because a concentric arrangement is made such that the central axes of the respective cylinders constituting the upper layer hole portion, the column member, and the stopper member coincide with each other.

  In the embodiment shown here, the arrangement of each quadruple concentric circle has symmetry on the XY coordinates. That is, in the top view of FIG. 2, when a circle with a radius r is drawn around the center point P of the disk-shaped force receiving body 110, the arrangement point Q of the quadruple concentric circles drawn in the X-axis positive region is Located at the intersection of the circle of r and the positive X-axis region. Similarly, the arrangement point of the quadruple concentric circle drawn in the X-axis negative area is located at the intersection of the circle of radius r and the X-axis negative area, and the arrangement point of the quadruple concentric circle drawn in the Y-axis positive area Is located at the intersection of this circle of radius r and the Y-axis positive region, and the arrangement point of the quadruple concentric circle drawn in the Y-axis negative region is located at the intersection of this circle of radius r and the Y-axis negative region To do. The arrangement having such symmetry is in consideration for effective displacement control of the disk-shaped force receiving body 110.

  In short, paying attention to the arrangement positions of the four support members 31 to 34 on the upper surface (first reference plane S1) of the second substrate 200, the two arrangement axes orthogonal to each other at the center point of the upper surface of the diaphragm portion 210 When a circle with a radius r centered on the center point is defined, four support members 31 to 34 are arranged at four intersection positions where the circle and two arrangement axes intersect. It will be. And the stopper members 41-44 are being fixed to the upper end of each support | pillar members 31-34, respectively, and it is suitable for inserting these four support | pillar members 31-34 in the disc-shaped force receiving body 110. The lower layer hole portions H11 to H14 and the upper layer hole portions H21 to H24 are provided at four locations, respectively. Of course, in carrying out the present invention, the number and arrangement of the support members and the stopper members are not limited to the illustrated embodiment. For example, three sets of strut members and stopper members may be arranged on the circumference of radius r with a central angle of 120 ° apart, or six sets of strut members and stopper members on the circumference of radius r. You may make it arrange | position at intervals of 60 degrees of center angles. Or you may arrange | position 3 or more sets side by side on a straight line.

  In addition, as long as the material of each component which comprises the force sensor which concerns on this invention is a material suitable for fulfill | performing the function as each component, what kind of thing may be used. In the case of the embodiment shown here, the first substrate 100 and the second substrate 200 are both made of a metal (for example, aluminum or stainless steel) processed material, and the base portion 410 is made of ceramic or The synthetic resin and the electrodes E11 to E15 are made of gold or copper. Further, the support members 31 to 34 and the stopper members 41 to 44 are made of metal such as aluminum or stainless steel.

<<< §2. Displacement control in basic embodiment >>
Next, it will be described that the displacement control of the disc-shaped force receiving body 110 is appropriately performed in the force sensor having the structure shown in FIGS. The basic principle of force detection by this force sensor is that the periphery of a diaphragm portion 210 made of a flexible thin plate is supported by a pedestal 220, and the diaphragm portion 210 and a disk-shaped force receiving member 110 disposed above the diaphragm portion 210 are provided. Are connected by the columnar connecting portion 120, and the deformation state of the diaphragm portion 210 is electrically detected by the detecting portion 400, thereby detecting the force acting on the disk-shaped force receiving member 110 in a state where the pedestal 220 is fixed. That's it.

  The greater the external force acting on the disk-shaped force receiving body 110, the greater the displacement of the disk-shaped force receiving body 110. As a result, the degree of deformation generated in the diaphragm section 210 increases, and the detection section 400 A large electrical signal is detected. However, as described above, when an excessive external force far exceeding the measurement range is applied, excessive deflection exceeding the elastic deformation limit occurs in the diaphragm portion 210, and the diaphragm is removed even after the external force is removed. There is a problem that the shape of the portion 210 does not return to its original shape or the diaphragm portion 210 is damaged. Since the force sensor described in §1 has a structure that suppresses the amount of displacement of the disk-shaped force receiving body 110 within an allowable range, even if an excessive external force is applied, the disk-shaped force receiving body 110 is detected. The displacement is controlled and has a function of preventing the diaphragm unit 210 from being damaged.

  Here, paying attention to the structural features of the force sensor, the upper surface of the diaphragm portion 210 and the upper surface of the pedestal 220 form a first reference plane S1, and the lower surface of the disk-shaped force receiving body 110 is a second reference surface. If the plane S <b> 2 is formed, the first reference plane S <b> 1 and the second reference plane S <b> 2 correspond to the length L <b> 1 of the columnar connecting portion 120 in a state where no force is applied to the disc-shaped force receiving body 110. Are maintained in a parallel state with a gap.

  Further, the lower ends of the support members 31 to 34 extending vertically upward with respect to the first reference plane S1 are fixed at four predetermined positions on the upper surface of the pedestal 220, and a third parallel to the second reference plane S2 is fixed. When the disc-shaped force receiving member 110 is partitioned into the upper layer portion 20 and the lower layer portion 10 by the reference plane S3, the column members 31 to 34 have such a length that the upper ends thereof reach the upper layer portion.

  Then, lower layer holes H11 to H14 having an inner diameter φ10 larger than the outer diameter φ30 of the column members 31 to 34 are formed at positions where the column members 31 to 34 extend in the lower layer portion 10 of the disk-shaped power receiving body 110. The upper layer holes H21 to H24 having an inner diameter φ20 larger than the inner diameter φ10 of the lower layer holes H11 to H14 are formed at positions adjacent to the upper layer part H11 to H14 of the upper layer part 20 of the plate-shaped force receiving body 110. The column members 31 to 34 are inserted through the lower layer holes H11 to H14, and their upper ends are positioned above the third reference plane S3 by a predetermined gap dimension L2. Further, the upper layer holes H21 to H24 have an outer diameter φ40 that is larger than the inner diameter φ10 of the lower layer holes H11 to H14 and smaller than the inner diameter φ20 of the upper layer holes H21 to H24. The stopper members 41 to 44 fixed to the are arranged.

  In the force sensor having such a structure, even if an external force having any component acts on the disk-shaped force receiving body 110, the displacement generated in the disk-shaped power receiving body 110 is set within a predetermined allowable range. Can be suppressed within.

  For example, FIG. 7 is a side sectional view showing displacement control when a force + Fz in the positive direction of the Z axis is applied to the disc-shaped force receiving body 110. As shown in the drawing, the Z-axis positive direction force + Fz is a force that displaces the disc-shaped force receiving member 110 upward, and the diaphragm portion 210 is bent so that its central portion is pulled upward. Become. In the case of this force sensor, the displacement in the positive direction of the Z-axis is controlled so as to be at most the gap dimension L2 shown in FIG. As shown in FIG. 7, when the disc-shaped force receiving member 110 is displaced by L2 in the positive direction of the Z axis, the bottom surfaces of the upper layer holes H21 to H24 (stepped portions of the holes) This is because it abuts on the lower surface periphery and prevents further upward displacement. If the gap dimension L2 is set to an appropriate value, the upward displacement of the disk-shaped force receiving body 110 can be suppressed within a range in which the diaphragm portion 210 is not damaged.

  On the other hand, FIG. 8 is a side sectional view showing displacement control when a force −Fz in the negative Z-axis direction acts on the disc-shaped force receiving body 110. As shown in the drawing, the Z-axis negative direction force -Fz is a force that displaces the disk-shaped force receiving member 110 downward, and the diaphragm portion 210 bends so that its central portion is pulled downward. become. In the case of this force sensor, the displacement in the negative Z-axis direction is controlled so as to be at most the gap dimension L1 shown in FIG. This is because when the disc-shaped force receiving body 110 is displaced by L1 in the negative Z-axis direction, the lower surface peripheral portion of the disc-shaped force receiving body 110 abuts on the upper surface of the pedestal 220 as shown in FIG. This is to prevent displacement. If the gap dimension L1 is set to an appropriate value, the downward displacement of the disk-shaped force receiving body 110 can be suppressed within a range where the diaphragm portion 210 is not damaged.

  In FIG. 8, for convenience of illustration, a state in which the lower surface of the diaphragm portion 210 is in contact with the upper surface of the electrode is illustrated, but in actuality, in a state in which the disc-shaped force receiving body 110 is displaced to the lowest position. However, it is preferable that a gap be secured between the lower surface of the diaphragm portion 210 and the upper surface of the electrode so that they are not short-circuited.

  Next, consider the case where a moment is applied. FIG. 9 shows a moment around the Y-axis positive direction with respect to the disc-shaped force receiving body 110 (here, the rotation direction for advancing the right screw in the Y-axis positive direction is referred to as the Y-axis positive direction). It is a sectional side view showing displacement control when + My acts. The moment + My about the positive direction of the Y-axis is a force that displaces the right end of the disc-shaped force receiving body 110 downward and the left end upward as shown in the figure, and the diaphragm section 210 bends as shown in the figure. It will be. In this force sensor, the displacement based on such moment + My is controlled so as to be in the state shown in FIG. 9 at the maximum. As shown in FIG. 9, when the right end of the disc-shaped force receiving body 110 is displaced downward, the lower surface thereof abuts against the upper surface of the pedestal 220, preventing further downward displacement, and the disc-shaped receiving member 110. When the left end of the force member 110 is displaced upward, as shown in FIG. 9, the bottom surface of the upper layer hole H22 (stepped portion of the hole) comes into contact with the peripheral portion of the lower surface of the stopper member 42 and further upwards. This is to prevent displacement.

  On the contrary, when the moment -My around the Y-axis negative direction is applied, the state is reversed left and right in FIG. 9, and similarly, the displacement is controlled within a predetermined allowable range. In addition, the force sensor maintains the same structure even when rotated 90 ° in the top view of FIG. 2, and the same phenomenon occurs even if the X axis and the Y axis are interchanged. Therefore, the same displacement control is performed even when the moments + Mx, -My around the X axis are applied.

  On the other hand, FIG. 10 is a side cross-sectional view showing displacement control when force + Fx in the X-axis positive direction is applied to the disk-shaped force receiving body 110. As shown in the figure, the X-axis positive direction force + Fx is a force that displaces the disc-shaped force receiving body 110 in the right direction in the figure, and the diaphragm part 210 is contracted in the lateral direction on the right side and the left side part in the figure. The bending which extends to a horizontal direction will be produced. In the case of this force sensor, the displacement in the X-axis positive direction is controlled so as to be in the state shown in FIG. 10 at the maximum. This is because when the disc-shaped force receiving body 110 is displaced in the X-axis positive direction to the position shown in the figure, the side wall portions of the upper layer holes H21 to H24 abut against the outer peripheral surface of the stopper members 41 to 44, and to the right. This is to prevent displacement. FIG. 11 is a top view showing the state of FIG. 10, and clearly shows a state in which the side wall portions of the four upper layer hole portions H21 to H24 are in contact with the outer peripheral surfaces of the stopper members 41 to 44, respectively.

  On the contrary, when the force -Fx in the negative X-axis direction is applied, the state is reversed left and right in FIG. 10, and similarly, the displacement is controlled within a predetermined allowable range. The same displacement control is also performed when a force + Fy in the Y-axis positive direction or a force -Fy in the Y-axis negative direction is applied. As described above, since the inner diameters of the upper layer holes H21 to H24 are φ20 and the outer diameters of the stopper members 41 to 44 are φ40, the displacement in the positive or negative direction with respect to the X axis and the Y axis is eventually “( It is controlled to a value of “φ20−φ40) / 2”. Therefore, if the dimension values φ20 and φ40 are set to appropriate values, the horizontal displacement of the disc-shaped force receiving member 110 can be suppressed within a range where the diaphragm portion 210 is not damaged.

  Finally, consider the case where a moment around the Z axis is applied. FIG. 12 is a top view showing displacement control when a moment + Mz around the positive direction of the Z-axis acts on the disc-shaped force receiving body 110. The moment + Mz around the positive direction of the Z-axis is a force that rotates and displaces the disk-shaped force receiving member 110 counterclockwise when viewed from above, as shown in the figure. Will occur. In this force sensor, the displacement based on the moment + Mz is controlled so as to be in the state shown in FIG. 12 at the maximum. This is because when the disc-shaped force receiving member 110 is rotationally displaced counterclockwise, the side wall portions of the four upper layer holes H21 to H24 come into contact with the outer peripheral surfaces of the stopper members 41 to 44, respectively, as shown in the figure. This is to prevent the counterclockwise rotational displacement.

  On the other hand, when the moment -Mz around the negative direction of the Z-axis acts, when viewed from above, the disc-shaped force receiving body 110 is rotationally displaced clockwise. In this case as well, the side wall portions of the four upper layer holes H21 to H24 come into contact with the outer peripheral surfaces of the stopper members 41 to 44, respectively, and further clockwise rotational displacement is prevented.

  Thus, in the force sensor described in §1, the force ± Fx in the X-axis direction, the force ± Fy in the Y-axis direction, the force ± Fz in the Z-axis direction, Regardless of the moment ± Mx, the moment ± My about the Y axis, or the moment ± Mz about the Z axis, the displacement is suppressed to a predetermined allowable range. As described above, it is a very important effect that the displacement control with respect to the disc-shaped force receiving body 110 is accurately performed regardless of which of the force in the direction of each coordinate axis and the moment around each coordinate axis is applied.

  When a force sensor is incorporated into a product and actually used, not only the normal operating environment for detecting the external force that is the original measurement target, but also the user hits the product itself or drops it on the floor. It is necessary to take into account the emergency situation. In such an emergency, it is impossible to predict what impact force will be applied to the force sensor from which direction. In the embodiment shown here, as described above, even if any of the forces ± Fx, ± Fy, ± Fz in the three axes and the moments ± Mx, ± My, ± Mz around the three axes is applied, Since accurate displacement control with respect to the force receiving body 110 is performed, even if an emergency such as a collision or a drop occurs, the diaphragm portion can be prevented from being damaged.

  In the past, it was necessary to select the material used for the diaphragm part in consideration of the balance between the required measurement range and the elastic deformation region of the diaphragm part, and the robustness of the diaphragm part. If used, you will be freed from such restrictions. That is, in the force sensor according to the present invention, the maximum displacement amount of the disk-shaped force receiving body 110 is the gap dimensions L1 and L2 shown in FIG. 1, the inner diameter φ20 of the upper layer holes H21 to H24, and the stopper members 41 to 44. By setting the outer diameter φ40 to a desired value, it can be arbitrarily set. Therefore, no matter what material is used for the diaphragm portion, the allowable displacement can be set to a desired value.

<<< §3. Detection unit function >>
The force sensor according to the present invention detects an external force acting on a disk-shaped power receiving body by electrically detecting the deformation state of the diaphragm portion. The detection unit 400 is a component that detects the deformation state of the diaphragm unit, and in the case of the force sensor according to the embodiment described in §1 and §2, as shown in the top view of FIG. The five electrodes E11 to E15 arranged to face the diaphragm portion 210, the base portion 410 that supports and fixes these electrodes, and the capacitance between the diaphragm portion 210 and each of the electrodes E11 to E15 are electrically The detection unit 400 is configured by a detection circuit (not shown) that detects the above.

  As shown in the side sectional view of FIG. 1, the electrodes E11 to E15 are arranged at a predetermined interval below the diaphragm portion. Here, the diaphragm portion 210 is made of a conductive material, and a total of five sets of capacitive elements C11 to C15 are formed by the five electrodes E11 to E15 and each portion of the diaphragm portion 210 facing the electrodes E11 to E15. . The detection circuit (not shown) measures the capacitance values of the five capacitative elements C11 to C15, grasps the deformation state of the diaphragm 210, and the direction of the external force acting on the disk-shaped force receiving body 110. And a function of detecting the size.

  Specifically, for example, as shown in FIG. 7, when a force + Fz in the positive direction of the Z-axis is applied, the capacitance values of the five sets of capacitive elements C11 to C15 all become small because the electrode spacing increases. . Conversely, as shown in FIG. 8, when the force −Fz in the negative Z-axis direction is applied, the capacitance values of the five sets of capacitive elements C <b> 11 to C <b> 15 all increase because the electrode spacing becomes narrow. Therefore, for example, if the capacitive element C15 (the capacitive element constituted by the electrode E15 and the opposing portion of the conductive diaphragm portion 210) is used for detecting the force ± Fz in the Z-axis direction, the electrostatic capacitance of the capacitive element C15 is detected. The increase / decrease in the capacitance value indicates the force ± Fz in the Z-axis direction.

  As shown in FIG. 9, when the moment + My around the Y-axis is applied, among the five capacitive elements C11 to C15, the capacitance value of C11 increases and the capacitance value of C12 decreases. . When the counter-rotating moment -My is applied, the capacitance value of C11 decreases and the capacitance value of C12 increases. Therefore, the difference between the capacitance values of both the capacitive elements C11 and C12 indicates the moment ± My around the Y axis. Similarly, the difference between the capacitance values of the capacitive elements C13 and C14 indicates a moment ± Mx around the X axis.

  As described above, in the force sensor, the technology for grasping the deformation state of the diaphragm unit 210 based on the capacitance values of the plurality of capacitive elements and detecting the force in the predetermined axis direction and the moment around the predetermined axis is described above. Since this is a known technique disclosed in Patent Documents 1 and 2, etc., detailed description thereof is omitted here.

  The present invention is a technique related to displacement control for preventing damage to a diaphragm portion when an excessive force is applied to the force sensor having the diaphragm portion. Therefore, the specific method for detecting the deformation state of the diaphragm portion is not an essential part of the invention, and the detection unit 400 has a function of electrically detecting the deformation state of the diaphragm portion 210. Anything can be used.

  For example, in the above-mentioned Patent Documents 3 and 4, a piezoresistive element is arranged at a predetermined position of the diaphragm part, and the mechanical expansion and contraction of individual parts of the diaphragm part is performed based on the change in the electric resistance of each piezoresistive element. A technique for grasping the state is disclosed. In the present invention, such a piezoresistive element can also be used as a detection unit. In that case, the diaphragm part 210 is made of an insulating material, and instead of providing the pedestal part 410 and the electrodes E11 to E15, a piezoresistive element is arranged on the upper surface or the lower surface of the diaphragm part (or may be embedded inside). Then, a change in the electrical resistance of these piezoresistive elements may be detected using a bridge circuit or the like, and the deformation state of the diaphragm unit 210 may be detected electrically.

  Specifically, for example, an orthogonal projection of the XY plane is obtained on the surface of the diaphragm unit 210, and a total of four pairs of piezoresistive elements are arranged, one pair in the X-axis positive region and one pair in the X-axis negative region on the orthogonal projection. For example, it is possible to detect the force Fx in the X-axis direction and the moment My around the Y-axis acting on the disc-shaped force receiving body 110. Similarly, if a total of four sets of piezoresistive elements, one pair in the Y-axis positive region and one pair in the Y-axis negative region on this orthogonal projection, are arranged, the force Fy in the Y-axis direction acting on the disc-shaped force receiving member 110 and The moment Mx around the X axis can be detected. Further, on the surface of the diaphragm unit 210, an arbitrary coordinate axis is defined with the center point as an origin and directed in an arbitrary direction, and a pair of a positive region and a pair of a negative region of the arbitrary coordinate axis, a total of four sets. If the piezoresistive element is arranged, it is possible to detect the force Fz in the Z-axis direction acting on the disk-shaped force receiving body 110. The specific arrangement of such elements is a well-known matter disclosed in, for example, the above-mentioned Patent Documents 3 and 4, and detailed description thereof is omitted here.

  Of course, these elements may be provided on the upper surface or the lower surface of the diaphragm section 210. Alternatively, elements may be arranged on both the upper surface and the lower surface, and detection may be performed by combining these elements. For example, it is also possible to detect forces and moments in the X-axis direction and Y-axis direction with elements provided on the upper surface, and detect forces and moments in the Z-axis direction with elements provided on the lower surface.

  Note that it is not always necessary to use a piezoresistive element as an element for detecting the mechanical expansion / contraction state of each part of the diaphragm. Any element that changes its electrical properties in accordance with the mechanical expansion and contraction state can electrically detect the deformation state of each part of the diaphragm portion. Such an element is generally called a strain gauge, and an element using a metal foil (for example, an element made of aluminum, copper, or an alloy thereof) or an element using a semiconductor is in practical use.

  Also, the above-mentioned Patent Documents 5 and 6 disclose techniques for detecting displacement of each part of the diaphragm part based on electric charges generated in the piezoelectric element. In the present invention, such a piezoelectric element can also be used as the detection unit. In this case, instead of providing the pedestal part 410 and the electrodes E11 to E15, the piezoelectric element is arranged at a predetermined position where stress is generated according to the deformation of the diaphragm part 210, and the electric charge generated in each piezoelectric element is measured, whereby the diaphragm The deformation state of the part 210 may be detected electrically.

  In the above-mentioned Patent Documents 7 and 8, forces ± Fx, ± Fy, ± Fz acting in the XYZ-axis directions and around the XYZ-axis are detected by independently detecting deflections generated in a plurality of diaphragm portions. A six-axis sensor capable of independently detecting all of the moments ± Mx, ± My, and ± Mz acting on is disclosed. The present invention is also applicable to such a six-axis sensor. In the basic embodiment described so far, a single diaphragm portion 210 is used, and the center position of the upper surface of the diaphragm portion 210 and the center position of the bottom surface of the disk-shaped force receiving body 110 are connected by a single columnar connection portion 120. However, the present invention uses a plurality of diaphragm portions as in the 6-axis sensor disclosed in the above-mentioned Patent Documents 7 and 8, and each of the diaphragm portions and the disk-shaped force receiving body is used. The present invention can also be applied to a sensor having a configuration in which the gaps are connected by independent columnar connecting portions. In other words, the present invention is a technique applicable to a sensor using a plurality of diaphragm portions and a sensor using a plurality of columnar connection portions. Further, in the above-described embodiment, one thin plate-like diaphragm portion 210 is used. However, the diaphragm portion does not necessarily need to be constituted by one plate, and for example, a beam structure whose plan view forms a cross shape. You may comprise by (the structure which piled up the two thin-plate bridge parts in the cross shape.). In short, the diaphragm portion referred to in the present invention may have any structure as long as it is a structure made of a thin plate having flexibility.

<<< §4. Example using locking pin and its assembly method >>
As described in the embodiment shown in FIG. 1, the column members 31 to 34 and the stopper members 41 to 44 play an important role in the displacement control in the present invention. Here, in order to perform a sufficient displacement control function even when an excessive external force is applied, the lower ends of the support members 31 to 34 are firmly fixed to the upper surface of the base 220, and the stopper members 41 to 44 are attached to the support columns. It is necessary to firmly fix the upper ends of the members 31 to 34.

  Therefore, here, a specific embodiment in which the support members 31 to 34 and the stopper members 41 to 44 are configured by locking pins that form an integral structure is shown. FIG. 13 is a side sectional view showing an example of a force sensor using such a locking pin. The basic structure of the embodiment shown in FIG. 13 is exactly the same as that of the force sensor shown in FIG. 1, but the specific structure of the support member and the stopper member is shown as a sectional view. A locking pin 51 shown in FIG. 13 is a structure in which the support member 31 and the stopper member 41 shown in FIG. 1 are formed of an integral structure, and is made of a metal such as stainless steel. Similarly, the locking pin 52 shown in FIG. 13 is a structure in which the support member 32 and the stopper member 42 shown in FIG. Although only two are shown in the side sectional view of FIG. 13, a total of four locking pins are used in this embodiment.

  As shown in the drawing, an axial core hole is formed in the central axis of each locking pin 51, 52, and a female screw hole is formed at a position for fixing each column member on the upper surface of the pedestal 220. , 52 are fastened and fixed to the pedestal 220 by inserting bolts 61, 62, on which male screws are formed, into the shaft hole and screwing them together. In this manner, the tip portions of the bolts 61 and 62 are fixed by screwing into the female screw holes in the pedestal 220, and the heads of the bolts 61 and 62 are inserted into the shaft core holes of the locking pins 51 and 52. Since the step portion is locked, the locking pins 51 and 52 are fixed on the base 220 very firmly.

  14 is a side sectional view showing a method for assembling the force sensor shown in FIG. In the left part of the figure, a locking pin 52 and a bolt 62 before assembly are shown. A female screw hole H72 is formed at a position where the bolt 62 is attached on the base 220, and a male screw that is screwed into the female screw hole H72 is formed at the tip of the bolt 62. On the other hand, the locking pin 52 is formed with an axial hole H52 through which the bolt 62 is inserted at the center axis thereof. A step portion is provided in the shaft hole H52, and the upper portion of the step portion has a diameter sufficient to accommodate the head of the bolt 62, but the lower portion of the step portion is the head of the bolt 62. It has a smaller diameter. Therefore, the locking pin 52 can be locked by the head of the bolt 62.

  A cylindrical jig 70 shown in FIG. 14 is a cylindrical structure in which an inner wall surface and an outer wall surface are concentric columns, and alignment is performed when the locking pins 51 and 52 are mounted on the base 220 by bolts 61 and 62. It is a tool to do. An inner diameter φ40 of the cylindrical jig 70 coincides with an outer diameter φ40 of a stopper member (parts indicated by reference numerals 41 and 42 in FIG. 3) of the locking pins 51 and 52, and the outer diameter φ20 is the upper layer hole H21, It corresponds to the inner diameter φ20 of H22. Therefore, the thickness of the cylinder constituting the cylindrical jig 70 is equal to “(φ20−φ40) / 2”.

  The right part of the figure shows a state in which the cylindrical pin 70 is used to attach the locking pin 51 and the bolt 61 to the upper surface of the pedestal 220. That is, first, the cylindrical jig 70 is fitted into the upper layer hole H21 of the disc-shaped force receiving member 110. As described above, the outer diameter φ20 of the cylindrical jig 70 coincides with the inner diameter φ20 of the upper layer hole H21, so that they fit together while maintaining an accurate concentric position. Subsequently, the locking pin 51 is inserted into the cylindrical jig 70 and fitted. As described above, since the inner diameter φ40 of the cylindrical jig 70 matches the outer diameter φ40 of the locking pin 51 (the diameter of the stopper member portion), both of them are fitted while maintaining an accurate concentric position. Match. Eventually, by interposing the cylindrical jig 70, the locking pin 51 can be disposed at an exact concentric position in the upper layer hole H21.

  In this way, with the locking pin 51 fitted in the cylindrical jig 70, the locking pin 51 is fastened and fixed to the base 220 with the bolt 61, and then the cylindrical jig 70 is pulled upward. The locking pin 51 is attached by detaching it. Then, the locking pin 51 can be attached in a state where the locking pin 51 is aligned with the exact concentric position in the upper layer hole H21, and the outer peripheral surface of the locking pin 51 and the inner peripheral surface of the upper layer hole H21. Can be set to the dimension “(φ20−φ40) / 2” at any location. This dimension is a value that defines the allowable range of displacement in the horizontal direction of the disk-shaped force receiving member 110. Therefore, if this dimension can be set uniformly during assembly work, the allowable range of displacement in the horizontal direction can be set to any value. The direction can also be set to the same value.

  If each locking pin is attached with a bolt as in this embodiment, it is only necessary to perform an operation from above the disk-shaped force receiving body 110, and there is no interference in the space in the cavity H. There is no effect. Therefore, it is possible to seal the cavity H in a state where the second substrate 200 is bonded to the third substrate 300 in advance and the detection unit 400 including the detection system electrical components is accommodated. A high performance sealed structure type sensor can be realized.

<<< §5. Modification of the present invention >>
Finally, some modifications of the present invention will be described.

(1) Modified example in which the downward displacement control is performed more reliably In §2, even if forces and moments are applied from various directions to the disk-shaped force receiving body 110 of the force sensor shown in FIG. As shown in FIGS. 7 to 12, it has been described that the displacement is controlled within a predetermined allowable range. Here, attention is again paid to FIG. FIG. 8 is a side cross-sectional view showing displacement control when a force -Fz in the negative Z-axis direction acts on the disc-shaped force receiving body 110. As described above, even if a downward force -Fz is applied to the disk-shaped force receiving body 110, the lower surface peripheral portion of the disk-shaped power receiving body 110 contacts the upper surface of the pedestal 220 as shown in FIG. The displacement is controlled at the contact stage.

  However, as shown in FIG. 8, the downward displacement of the peripheral portion of the disk-shaped force receiving body 110 is blocked by the pedestal 220, but the central portion of the disk-shaped power receiving body 110 (in the diaphragm 210). Since the opposing portion) is in contact with the diaphragm portion 210, a force that pushes the diaphragm portion 210 further downward may be applied by the central portion of the disc-shaped force receiving member 110. In particular, when a very large downward force is applied, the diaphragm 210 may be damaged by the central portion of the disc-shaped force receiving member 110.

  In order to cope with such a situation, in order to more reliably control the downward displacement, adopt a structure in which the downward displacement of the central portion of the disk-shaped force receiving body 110 can be prevented by the pedestal 220. That's fine. FIG. 15 is a side sectional view showing a state in which an example of the force sensor having such a structure is cut along the XZ plane. The modification shown in FIG. 15 is obtained by reducing the outer diameter of the diaphragm portion 210, the inner diameter of the pedestal 220, and the outer diameter of the base portion 410 in the basic embodiment shown in FIG.

  The positional relationship between the disk-shaped force receiving member 110 and the pedestal 220 in this modification is clearly shown in the exploded view of FIG. That is, the dimensions of the respective parts of the first substrate 100 of this modification are exactly the same as those of the basic embodiment shown in FIG. 1, but the second substrate 200 has an outer diameter φH (that is, the diaphragm portion 210). The inner diameter of the pedestal 220 is smaller than that of the basic embodiment shown in FIG. As a result, the diameter of the hollow portion H is reduced, and accordingly, the outer diameter of the base portion 410 is designed to be small. As shown in the upper part of FIG. 16, if the distance between the inner wall surface of the lower hole H11 and the inner wall surface of the lower hole H12 is J, φH <J. Therefore, in FIG. 16, when the first substrate 100 is moved downward in the drawing, the wall 111 constituting the lower layer hole H11 and the wall 112 constituting the lower layer hole H12 are both of the pedestal 220. It will contact the upper surface.

  FIG. 17 is a side sectional view showing displacement control when a force -Fz in the negative Z-axis direction is applied to the force sensor according to this modification. The wall portions 111 and 112 are in contact with the upper surface of the pedestal 220, and the downward displacement of the central portion of the disc-shaped force receiving body 110 is prevented by the pedestal 220. Therefore, even when a large downward force is applied, it is possible to suppress the pressing force applied to the diaphragm portion 210 from the central portion of the disk-shaped force receiving body 110, and to prevent the diaphragm portion 210 from being damaged.

  After all, the main point of this modified example is that all the lower layer holes H11 to H14 are located above the pedestal 220 in a state where no external force is applied to the disk-shaped power receiving body 110 (in other words, The lower layer hole portions H11 to H14 are arranged above the diaphragm portion 210 (so as not to cover a part of the lower layer hole portions H11 to H14).

(2) Modification with structure capable of detecting overload An important feature of the force sensor according to the present invention is a structure that prevents damage to the diaphragm portion even when an excessive external force is applied. However, even with a force sensor having such a structure, when an extreme overload is applied, damage to the diaphragm is inevitable. For example, in the case of a force sensor attached to an indirect part of an industrial robot, if the robot itself falls from a high place or collides during high-speed movement, the force sensor described so far will also be applied to the diaphragm section. There are cases where damage is inevitable.

  The occurrence of such an overload can be recognized by monitoring the signal while the power sensor is turned on and an electrical detection signal is being output. However, in practice, the force sensor is not always supplied with power, so when a fall accident or a collision accident occurs, if the force sensor is not in operation, an extreme overload will occur. It is not possible to recognize the fact that.

  The modification described here has a function of leaving the fact that such an extreme overload is applied as a physical trace. For example, FIG. 18 is a partially enlarged side sectional view showing a state in which the force sensor shown in FIG. 1 is provided with a protrusion for detecting overload. The basic structure shown in FIG. 18 corresponds to the upper right portion of the force sensor shown in FIG. 1, but conical protrusions are formed at several positions on the wall surface and the surface of the locking pin forming each hole. Is provided. These protrusions are made of a material that can be plastically deformed (for example, a metal such as aluminum or SAS) when a predetermined pressure (pressure equal to or higher than a certain threshold) is applied, and is plastic when an extreme overload is applied. By causing the deformation, it functions to leave the overload as a physical trace.

  For example, in FIG. 18, when the extreme overload that moves the first substrate 100 to the left in the drawing is applied to the three protrusions P1 arranged on the right side of the stopper member 41, the front ends thereof are opposed to each other. Will cause plastic deformation. Similarly, the three protrusions P2 disposed on the left side of the stopper member 41 are pressed against the opposing surface when extreme overload is applied to move the first substrate 100 to the right in the drawing. This will cause plastic deformation. Further, the three protrusions P3 and the three protrusions P4 disposed below the stopper member 41 have their front ends facing the opposite surface when an extreme overload is applied to move the first substrate 100 upward in the drawing. The three projections P7 disposed below the first substrate 100 are subjected to plastic deformation and are subjected to extreme overload that moves the first substrate 100 downward in the figure. The front end portion is pressed against the opposing surface to cause plastic deformation.

  Similarly, the three protrusions P5 arranged on the right side of the column member 31 and the three protrusions P6 arranged on the left side are also extremely movable to move the first substrate 100 leftward or rightward. When overloaded, plastic deformation occurs. Here, the protrusion P1 and the protrusion P5 can detect overload in the same direction, but have different sensitivities. The same applies to the protrusions P2 and P6.

  As described above, the direction and magnitude of overload for causing plastic deformation varies depending on the individual protrusions. Therefore, as shown in the illustrated example, various protrusions should be provided at various locations. For example, it is possible to recognize the direction and magnitude of the applied overload by confirming which projection portion has undergone plastic deformation. In particular, if a conical (or pyramid-shaped) protrusion as shown in the example shown in the figure is used, the plastic deformation is concentrated on the tip portion, so that the confirmation work is facilitated.

  In particular, in the case of the example shown in FIG. 18, the shape of the protrusions P1 and P2 can be visually confirmed or confirmed using a magnifying glass by looking into the upper layer hole H21 from above. Similarly, the shape of the protrusion P7 can be confirmed by looking into the gap between the first substrate 100 and the second substrate 200 from the side, and the shape of each of the other protrusions can be changed as necessary. If the operation of removing the stopper member 41 is performed, it can be confirmed.

  Usually, a metal has a property of causing elastic deformation until an applied pressure reaches a predetermined elastic limit, and when the strength of the pressure exceeds the elastic limit, it turns into plastic deformation. It depends on the type. Therefore, if projections made of various shapes, sizes, and materials are provided at various locations, the mode of plastic deformation that occurs in each projection depending on the direction and size of the applied overload. Therefore, it is also possible to analyze what overload was applied from the trace of plastic deformation left in each projection.

  In the example shown in FIG. 18, protrusions are provided on both the locking pin (stopper member 41 and column member 31) side and on the wall surface side of the upper layer hole 21 and the lower layer hole H11 facing each other. Of course, it may be provided only on one side. In short, in the modification described here, a portion of the wall surface forming the upper layer hole H21 that faces the surface of the stopper member 41, and a portion of the surface of the stopper member 41 that faces the wall surface forming the upper layer hole H21. In at least one of the portion of the wall surface that forms the lower layer hole H11 that faces the surface of the column member 31 and the portion of the surface of the column member 31 that faces the wall surface that forms the lower layer hole portion H11 (Practically, it is preferable to be provided at a plurality of locations as in the example shown in the figure.) Protruding portions made of a material that has a height that does not reach the opposing surface and plastically deforms when a predetermined pressure is applied. What should I do?

  Of course, plastic deformation occurs in these protrusions only when an external force (overload) exceeding the rating is applied to the force sensor. In other words, as long as an external force below the rating is applied, each protrusion is designed not to contact the opposing surface or to apply only pressure within the range of elastic deformation even if contacted. . Therefore, at the time of periodic inspection, if the shape of each protrusion is inspected and plastic deformation cannot be confirmed, it can be recognized that the sensor has been used in a normal state in which only an external force below the rated value has been applied. . On the other hand, if plastic deformation is observed in any of the protrusions, it can be determined that an overload exceeding the rating is applied to the sensor. Of course, even if a trace indicating the effect of overload exceeding the rating remains, the sensor according to the present invention has a structure for preventing the diaphragm portion from being damaged, and thus does not necessarily have a failure. . However, if the overload indicated by plastic deformation is extremely large, the possibility of failure increases, so that measures such as replacement with a new sensor can be taken as necessary.

  In addition, instead of the protrusion, it has a thickness that does not reach the opposing surface, and when a predetermined pressure (pressure above a certain threshold) is applied, the optical characteristics change, and even after the pressure is removed It is also possible to provide a film layer made of a material having the property of maintaining the above optical characteristics. The film layer P8 shown in FIG. 18 is a film layer having such a property, and its function is to physically apply a downward overload applied to the first substrate 100, like the protrusion P7. It is a function to leave as a trace.

  For example, when a predetermined pressure is applied, the color changes, and after the pressure is removed, the film layer P8 is formed of a material having the property of maintaining the changed color. On the other hand, when an overload is applied downward and the film layer P8 is pressed against the upper surface (the upper surface of the pedestal) of the second substrate 200, the film layer P8 leaves a trace as a color change. Therefore, by visually observing this, it is possible to recognize the fact that a downward overload acts.

(3) Modification regarding shape of locking pin etc. In the embodiment described so far, the shape of the upper layer hole portion, the lower layer hole portion, the column member, and the stopper member is a cylindrical shape, but these are necessarily required to be a cylindrical shape. For example, it may be a prismatic shape such as a quadrangular prism or a hexagonal prism, or any other arbitrary shape. “Diameter” as used in the present application does not mean only the radius or diameter of a circle, but the length of “I am” in a certain direction. Therefore, when the upper layer hole portion, the lower layer hole portion, the support member, and the stopper member are arbitrarily shaped, the “diameter” in each direction subject to displacement control is a dimensional condition of φ30 <φ10 <φ40 <φ20. As long as

It is a sectional side view which shows the state which cut | disconnected the force sensor which concerns on fundamental embodiment of this invention along XZ plane. It is a top view of the force sensor shown in FIG. It is a sectional side view which shows the state which decomposed | disassembled the force sensor shown in FIG. 1 into each component. FIG. 4 is a top view of the first substrate 100 shown in FIG. 3. FIG. 4 is a bottom view of the second substrate 200 shown in FIG. 3. FIG. 4 is a top view illustrating a state where a detection unit 400 is attached on the third substrate 300 illustrated in FIG. 3. FIG. 3 is a side sectional view showing displacement control when a force + Fz in the positive direction of the Z-axis acts on the force sensor shown in FIG. 1. FIG. 3 is a side sectional view showing displacement control when a force −Fz in a negative Z-axis direction acts on the force sensor shown in FIG. 1. FIG. 3 is a side sectional view showing displacement control when a moment + My around the positive direction of the Y-axis acts on the force sensor shown in FIG. 1. It is a sectional side view which shows displacement control when force + Fx of the X-axis positive direction acts on the force sensor shown in FIG. It is a top view which shows displacement control when force + Fx of the X-axis positive direction acts on the force sensor shown in FIG. It is a top view which shows the displacement control when the moment + Mz around the Z-axis positive direction acts on the force sensor shown in FIG. It is a sectional side view which shows an example of the fixing method of the support | pillar member and stopper member in the force sensor shown in FIG. It is a sectional side view which shows the assembly method of the force sensor shown in FIG. It is a sectional side view which shows the state which cut | disconnected the force sensor which concerns on the modification of this invention along XZ plane. FIG. 16 is a side sectional view showing some components when the force sensor shown in FIG. 15 is disassembled. FIG. 16 is a side sectional view showing displacement control when a force −Fz in the negative Z-axis direction acts on the force sensor shown in FIG. 15. FIG. 2 is a partially enlarged side cross-sectional view showing a state where a projection for detecting an overload is provided on the force sensor shown in FIG. 1.

Explanation of symbols

10: Lower layer portion 20 of the disk-shaped power receiver 20: Upper layer portions 31-34 of the disk-shaped power receiver: Column members 41-44: Stopper members 51, 52: Locking pins 61, 62: Bolt 70: Cylindrical jig DESCRIPTION OF SYMBOLS 100: 1st board | substrate 110: Disk-shaped receiving body 111,112: Wall part 120: Columnar connection part 200: 2nd board | substrate 210: Diaphragm part 220: Base 300: 3rd board | substrate 400: Detection part 410: Base Portions E11 to E15: Electrode + Fx: Force in the positive direction of the X axis + Fz: Force in the positive direction of the Z axis-Fz: Force in the negative direction of the Z axis + My: Moment about the positive direction of the Y axis + Mz: Around the positive direction of the Z axis Moment H: Cavity H11-H14: Lower layer hole H21-H24: Upper layer hole H51, H52: Shaft hole H71, H72: Female screw hole J: Center portion dimension L1: Columnar connecting portion length L2: Gap size P: Center points P1 to P7: Origin Q: Arrangement point r: Circle radius S1: First reference plane S2: Second reference plane S3: Third reference plane X, Y, Z: Coordinate axis φH of three-dimensional orthogonal coordinate system: Cavity H Inner diameter φ10: inner diameter φ20 of lower layer holes H11 to H14: inner diameter φ30 of upper layer holes H21 to H24: outer diameter of strut members 31 to 34 φ40: outer diameter of stopper members 41 to 44

Claims (12)

A diaphragm made of a flexible thin plate;
A pedestal that supports the periphery of the diaphragm portion;
A disc-shaped force receiving member disposed above the diaphragm portion;
A columnar connecting portion connecting the diaphragm portion and the disk-shaped force receiving member;
A detection unit for detecting a force acting on the disc-shaped force receiving member in a state where the pedestal is fixed by electrically detecting a deformation state of the diaphragm unit;
With
The upper surface of the diaphragm part and the upper surface of the pedestal form a first reference plane, and the lower surface of the disk-shaped force receiving member forms a second reference plane opposite to the first reference plane, In a state where no force is applied to the force receiving body, the first reference plane and the second reference plane are configured to be maintained in a parallel state with a predetermined gap therebetween,
A lower end of a column member extending vertically upward with respect to the first reference plane is fixed at a predetermined position on the upper surface of the pedestal, and the disc-shaped support is received by a third reference plane parallel to the second reference plane. When the force body is partitioned into an upper layer portion and a lower layer portion, the support member has a length that the upper end reaches the upper layer portion,
A lower layer hole having an inner diameter larger than the outer diameter of the column member is formed at a position where the column member extends in the lower layer portion of the plate-shaped force receiving member, and the upper layer portion of the disk-shaped force receiving member An upper layer hole portion having an inner diameter larger than the inner diameter of the lower layer hole portion is formed at a position adjacent to the lower layer hole portion of the lower layer hole portion. 3 above the reference plane of 3 by a predetermined gap dimension,
A stopper member having an outer diameter larger than the inner diameter of the lower layer hole portion and smaller than the inner diameter of the upper layer hole portion and fixed to the upper end of the column member is disposed in the upper layer hole portion. Force sensor. The force sensor according to claim 1,
A peripheral portion surrounding the cavity is prepared by preparing a single substrate in which a cavity is formed by hollowing out a central portion of the lower surface, and forming a diaphragm portion by a thin portion remaining above the cavity of the substrate. A force sensor characterized by comprising a pedestal and using the upper surface of the substrate as a first reference plane. The force sensor according to claim 1 or 2,
The disk-shaped force receiving body and the columnar connecting portion are made of an integral structure of the same material, and the columnar connecting portion is constituted by a downward projecting portion continuous from the lower surface of the disk-shaped power receiving body. Sense sensor. The force sensor according to any one of claims 1 to 3,
A plurality of electrodes arranged to face the diaphragm portion at a predetermined interval below the conductive diaphragm portion, a base portion for supporting and fixing these electrodes, the diaphragm portion and the plurality of electrodes A force sensor characterized in that a detection unit is configured by a detection circuit that electrically detects capacitance between each of them. The force sensor according to any one of claims 1 to 4,
The lower layer hole is made of a cylindrical cavity having an inner diameter φ10, the upper layer hole is made of a columnar cavity having an inner diameter φ20, and the column member is made of a columnar member having an outer diameter φ30, and a stopper member Consists of a cylindrical member having an outer diameter of φ40,
In a state where no force is applied to the disk-shaped force receiving member, the concentric arrangement is made such that the central axes of the respective cylinders constituting the lower layer hole portion, the upper layer hole portion, the column member, and the stopper member coincide with each other, and φ30 <φ10 < A force sensor characterized in that φ40 <φ20. The force sensor according to any one of claims 1 to 5,
A force sensor characterized in that the center position of the upper surface of the diaphragm portion and the center position of the lower surface of the disc-shaped force receiving member are connected by a single columnar connecting portion. In the force sensor in any one of Claims 1-6,
When two arrangement axes orthogonal to the center point of the upper surface of the diaphragm portion and a circle with a radius r centering on the center point are defined on the first reference plane, the circle and the two Four strut members are arranged at four intersection positions where the arrangement axis intersects, and a stopper member is fixed to the upper end of each strut member,
A force sensor, wherein the disk-shaped force receiving member is provided with a lower layer hole and an upper layer hole at four locations suitable for inserting the four strut members. The force sensor according to any one of claims 1 to 7,
A force sensor characterized in that the lower layer hole is arranged so that the entire lower layer hole is positioned above the pedestal in a state where no force is applied to the disk-shaped force receiving body. The force sensor according to any one of claims 1 to 8,
The portion of the wall surface that forms the upper layer hole portion that faces the surface of the stopper member, the portion of the surface of the stopper member that faces the wall surface that forms the upper layer hole portion, and the column member of the wall surface that forms the lower layer hole portion At least one of a portion facing the surface of the support member and a portion facing the wall surface forming the lower layer hole portion of the surface of the support member, and has a height that does not reach the facing surface, and a predetermined pressure A force sensor characterized in that a protrusion made of a material that plastically deforms when applied is provided. The force sensor according to any one of claims 1 to 8,
The portion of the wall surface that forms the upper layer hole portion that faces the surface of the stopper member, the portion of the surface of the stopper member that faces the wall surface that forms the upper layer hole portion, and the column member of the wall surface that forms the lower layer hole portion At least one of the portion facing the surface of the column member and the portion facing the wall surface forming the lower layer hole portion of the surface of the support member has a thickness that does not reach the facing surface, and a predetermined pressure is applied. A force sensor comprising a film layer made of a material having a property of changing optical characteristics when applied and maintaining the changed optical characteristics even after the pressure is removed.
The force sensor according to any one of claims 1 to 10,
The strut member and the stopper member are constituted by a locking pin that forms an integral structure,
An axial core hole is formed in the central axis of the locking pin, and a female screw hole is formed at a position for fixing the column member on the pedestal upper surface.
The force sensor, wherein the locking pin is fastened and fixed to a pedestal by inserting and screwing a bolt on which a male screw is formed into the shaft hole. The force sensor assembly method according to claim 11,
Prepare a cylindrical jig whose inner diameter matches the outer diameter of the stopper member of the locking pin and whose outer diameter matches the inner diameter of the upper layer hole,
In the state where the cylindrical jig is fitted into the upper layer hole, and the locking pin is fitted inside the cylindrical jig, the locking pin is fastened and fixed to the base with a bolt,
Thereafter, the locking pin is attached by detaching the cylindrical jig, and a force sensor assembling method is characterized.