JP2006284539A - Load cell and balance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Roberval mechanism type load cell capable of constituting a balance into a thin type, and the balance using the load cell. <P>SOLUTION: In this load cell provided with a strain element 11 provided with beams 13, 14 arranged vertically in parallel and formed integrally, and a strain gage in the vicinity of resilient parts 13a, 13b, 14a, 14b formed in prescribed positions of the strain element 11, a through hole 12 is provided to be penetrated vertically through the substantially central parts of the beams 13, 14, a support leg 18 is provided to support the strain element 11 through the through hole 12, and a support point side of the strain element 11 is coupled with the support leg 18 by a coupling means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a load cell of a robust mechanism having beams arranged in parallel in the vertical direction and a balance using the load cell.

Conventionally, as a load cell of this type of robust mechanism, there is one described in Patent Document 1. FIG. 1 is a diagram showing the configuration of this load cell. As shown in the figure, the load cell of the Roverval mechanism includes a strain body 100 having beams 101 and 102 arranged in parallel vertically, and a fulcrum side member (frame) 103 is provided at a fulcrum side end of the strain body 100. The support leg member 104 is fixed to the fulcrum side member 103 and attached to the fulcrum side member 103 via attachment members 106 and 107. A weight side end portion 105 is fixed to the weight side end portion of the strain generating body 100, and the weight side end portion 105 is configured to support a weighing pan of the scale. FIG. 1 is a side sectional view of the load cell.
Utility Model Registration No. 2522882

  However, in the load cell of the conventional structure of the above-described robust mechanism, the fulcrum side member (frame) 103 is fixed to the fulcrum side end portion of the strain body 100, and the fulcrum side member 103 is attached to the support leg member 104 serving as the leg of the scale. Since the members 106 and 107 are combined, there is a problem that if the scale is configured using the load cell, the scale itself becomes thick due to the thickness of the Roverval mechanism and the mounting portion.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a load cell of a Roverval mechanism capable of making the balance thinner, and a balance using the load cell.

  In order to solve the above-mentioned problems, the invention according to claim 1 is formed at a predetermined position of a beam of a strain body including a beam that is arranged in parallel vertically and formed integrally, and the beam of the strain body. A load cell having a configuration in which a strain gauge is provided in the vicinity of a strain generating portion, and a through hole is provided in a substantially central portion of the beam in a vertical direction so as to support the strain generating body through the through hole. A leg is provided, and a fulcrum side of the strain generating body is coupled to the support leg by a coupling means.

  According to a second aspect of the present invention, in the load cell according to the first aspect of the present invention, the beam is parallel to the upper and lower sides on both sides with a through-hole formed in a substantially central portion of the strain generating body penetrating in the vertical direction. It is arranged.

  According to a third aspect of the present invention, in the load cell according to the first or second aspect, the coupling means is provided on a fulcrum side of the strain body via a leaf spring member attached to a lower portion of the fulcrum side of the strain body. It is the structure couple | bonded with the said support leg.

  According to a fourth aspect of the present invention, in the load cell according to any one of the first to third aspects, the strain gauges are arranged on both sides and vertically in parallel with the through hole of the strain generating body interposed therebetween. It is characterized in that it is provided in a symmetrical position around the support leg on the same surface of the strain generating body in the vicinity of the strain generating portion of the beam.

  According to a fifth aspect of the present invention, in the load cell according to any one of the first to fourth aspects, the upper end of the support leg passes through the through hole of the strain generating body, and is predetermined from the upper surface of the strain generating body. It is characterized in that a regulating member protruding in size is arranged.

  According to a sixth aspect of the present invention, in the scale configured to support the four corners of the weighing pan on the priority side of the four load cells, the load cell according to any one of the first to fourth aspects is used for the load cell. It is characterized by that.

  According to the first and second aspects of the present invention, the fulcrum side of the strain generating body is coupled by the coupling means to the support leg that passes through the through hole provided in the substantially central portion of the strain generating body of the load cell. It is possible to provide a load cell in which the thickness of the Roverval mechanism part and the thickness of the attachment part are not combined, the structure is simple, the scale itself is thinned, and the measurement accuracy is not lowered.

  According to the third aspect of the present invention, since the coupling means is configured to couple the fulcrum side of the strain generating body to the support leg via a leaf spring attached to the lower part of the strain generating body on the fulcrum side. Can be absorbed by the leaf spring.

  According to the invention described in claim 4, since the strain gauge is provided symmetrically around the support leg on the same surface of the strain generating body, the load applied to the strain gauge is equalized and errors can be eliminated. .

  According to the fifth aspect of the present invention, since the restricting member that protrudes from the upper surface of the strain generating body by a predetermined dimension is arranged at the upper end of the support leg through the through hole of the strain generating body, Even when a large load is applied, the restricting member can suppress a distortion of a predetermined amount or more of the strain generating body.

  According to the invention described in claim 6, since the load cell according to any one of claims 1 to 4 is used for the balance, a thin balance can be provided.

  Embodiments of the present invention will be described below in detail with reference to the drawings. 2 to 5 are views showing a configuration example of a load cell of a robust mechanism type according to the present invention, FIG. 2 is a side view, FIG. 3 is a bottom view of a load cell main body (a portion excluding a support base), and FIG. FIG. 5 is a perspective view of the load cell as viewed obliquely from below. The load cell 10 includes a strain body 11 made of metal (such as high-strength aluminum). The strain body 11 is formed of a rectangular thick plate as a whole. A rectangular through hole 12 is formed in a substantially central portion in the vertical direction. Further, the strain body 11 is arranged on both sides and vertically in parallel with the through hole 12 interposed therebetween. In addition, a total of four beams 13, 13, 14, 14 are provided, and these are integrally formed.

  The two upper beams 13 and 13 are respectively provided with strain-generating portions 13a and 13b made of arcuate recesses at predetermined positions, and the two lower beams 14 and 14 are made of arcuate recesses at predetermined positions, respectively. Strain generating portions 14a and 14b are provided. Strain cages Z1 and Z2 are respectively provided in the vicinity of the strain-generating portions 14a and 14b of one lower beam 14 (in the figure, the side surfaces opposite to the strain-generating portions 14a and 14b), and the strain-generating portions 14a and 14a of the other lower beam 14 are provided. Strain cages Z3 and Z4 are provided in the vicinity of 14b, respectively. Reference numeral 15 denotes a leaf spring attached to the fulcrum side end of the strain body 11, and the leaf spring 15 is formed in a T-shape, and the central protrusion 15 a of the leaf spring 15 is located at the center of the through hole 12. It is fixed to the fulcrum side end of the strain generating body 11 with bolts 16 and 16 so as to be positioned at.

  A first regulating member 17 is attached to the fulcrum side end of the strain generating body 11, and an upper end 17 a of the first regulating member 17 protrudes from the upper surface of the strain generating body 11 by a predetermined dimension D <b> 2. Reference numeral 18 denotes a support leg, and the support leg 18 is fixed to the central protrusion 15 a of the leaf spring 15 via a nut 19 and a nut 20. That is, the nut 19 has a thread groove formed on the outer periphery thereof to be screwed into the inner thread groove of the nut 20, and the nut 19 is passed through a hole formed in the central protrusion 15 a of the leaf spring 15. The nut 19 and the nut 20 are coupled by screwing the nut 20 into the outer peripheral thread groove 19, and the nut 19 and the nut 20 sandwich the central protrusion 15 a of the leaf spring 15, thereby coupling the nut 19 and the nut 20. Fix the body. Further, a screw hole through which the support leg 18 penetrates and is screwed is provided in the central portion of the nut 19. By passing the support leg 18 through the screw hole and screwing a screw groove on the outer periphery thereof. The support leg 18 is fixed to the nut 19. As a result, the support leg 18 is fixed to the leaf spring 15. In addition, since the support leg 18 is couple | bonded by the screw groove, the length can be adjusted. Further, the connection between the support leg 18 and the nut 19 may be a connection other than the thread groove engagement, for example, the nut 19 and the support leg 18 may be fixed by shrink fitting.

  As shown in FIG. 4, the nut 20 protrudes from the upper surface of the strain body 11 by a predetermined dimension D <b> 1, and acts as a second restricting member. When the upper end protruding dimension of the first restricting member 17 is D2, D2> D1. Since D2> D1 as described above, when a large load is applied to the stress side of the strain generating body, the lower surface of the strain generating body 11 first comes into contact with the first regulating member 17, and the strain generating body 11 When the load is so large that the distortion by the first restricting member 17 cannot be suppressed, the lower surface of the strain body 11 first comes into contact with the upper end of the nut 20, and further strain applied to the strain body 11 is suppressed. It can be reliably suppressed.

  A support base 21 is attached to the lower end of the support leg 18. The support base 21 has a thick disk shape made of a resin material or the like, and has a shape in which a circular protrusion 21a is formed at the bottom. A disc-shaped metal plate (for example, SUS plate) 22 is inserted into the support base 21. A substantially arc-shaped recess is formed at the center of the metal plate 22, and a steel ball 23 is interposed between the recess and the lower end of the support leg 18 so that the lower end of the support leg 18 is supported by the support base 21. Yes. A disk-shaped lid member 24 is provided on the upper surface of the support base 21, and the lid member 24 is connected to the metal plate 22 by a connecting member 25.

  As shown in FIG. 3, the lower surfaces of the lower beams 14 and 14 of the strain generating body 11 are provided with substrates 26 and 26 on which electronic components for incorporating the strain gauges Z1 to Z4 into the Wheatstone bridge are mounted. A substrate 27 on which various electronic components for compensation and the like are mounted is mounted on the lower surface of the body side end portion, and a cable 28 for inputting a DC power source or outputting a signal is output to the output terminal of the substrate 27. It is connected.

  As described above, the load cell 10 is configured so that the fulcrum side of the strain body 11 is coupled via the leaf spring 15 to the support leg 18 that passes through the through hole 12 provided in the substantially central portion of the strain body 11. Unlike a conventional balance using a load mechanism type load cell, the balance itself can be made thin with a simple configuration without the thickness of the balance combining the robust mechanism and the mounting portion. In addition, since the load is applied to the load cell almost uniformly by the substantially central portion, it is possible to prevent a decrease in measurement accuracy. Further, since the fulcrum side of the strain body 11 is coupled to the support leg 18 via the leaf spring 15, the overload applied to the load cell 10 can be absorbed by the leaf spring 15. Further, since the strain gauges Z1 to Z4 are provided symmetrically around the support leg 18 on the same surface of the strain generating body, the load applied to the strain gauges Z1 to Z4 is equalized and errors can be eliminated.

  6 and 7 are diagrams showing the configuration of a balance using the load cell having the above-described configuration. FIG. 6 is a partially cutaway plan view of the balance, and FIG. 7 is a cross-sectional view taken along line BB in FIG. As shown in the figure, this scale has a rectangular weighing dish 30 and has a structure in which the bottom surface of the four corners of the weighing dish 30 is supported by the priority side end of the load cell 10. The weight side end portions of the four load cells 10 are arranged so that the nut fixed to the upper end of the support leg 18 serving as the second restricting member and the upper end of the first restricting member 17 are positioned on the diagonal line of the weighing pan 30. The bolts 31, 32, and 33 are fixed to the attachment portions 30a provided at the four corners on the back of the weighing pan.

  In the scale having the above-described configuration, the lower surface (back surface) of the weighing pan 30 comes into contact with the upper end of the first regulating member 17 to suppress the distortion of the strain body 11 of the load cell 10. When a larger load is applied to the weighing pan 30, the upper end of the nut 20 passes through the through hole 12 of the strain body 11 of the load cell 10 and protrudes from the upper surface of the strain body 11 by a predetermined dimension D1 (see FIG. 4). Therefore, the upper end portion of the nut 20 abuts on the lower surface of the weighing pan 30 and acts as a second restricting member, and the upper end material of the nut 20 and the lower surface of the weighing pan 30 ( The strain of the strain generating body 11 of the load cell 10 can be suppressed by setting the distance to the back surface.

  FIG. 8 is an external perspective view showing another configuration example of the load cell according to the present invention. In FIG. 8, the same reference numerals as those in FIGS. 2 to 7 denote the same or corresponding parts. The same applies to other drawings. The load cell 10 is different from the load cells shown in FIGS. 2 to 5 in that strain gauges Z1 and Z2 are provided on the upper surface of one upper beam 13 (on the side surface opposite to the strain generating portions 13a and 13b), and the strain gauges Z3 and Z4 are provided. Is provided on the upper surface of the other upper beam 13 (on the side surface opposite to the strain-generating portions 13a and 13b). And although illustration is abbreviate | omitted, the board | substrates 26 and 26 (refer FIG. 3) by which the electronic component for incorporating the strain gauges Z1-Z4 in a Wheatstone bridge was mounted in the upper surface of both the upper beams 13 and 13 of the strain body 11 is shown. A substrate 27 (see FIG. 3) on which various electronic components for compensation are mounted is mounted on the upper surface of the stress side end portion of the strain generating body 11, and a DC power supply is input to the output terminal of the substrate 27. Or a cable 28 (see FIG. 3) for outputting a signal is connected.

  Even if the load cell is configured as shown in FIG. 8, similarly to the load cell shown in FIGS. 2 to 5, similarly to the load cell shown in FIGS. Since the fulcrum side is connected, the configuration is simple, the scale using the load cell itself can be made thin, and the load is applied almost evenly to the load cell by the central part to prevent a decrease in weighing accuracy. Can do. Further, since the fulcrum side of the strain body 11 is coupled to the support leg 18 via the leaf spring 15, the overload applied to the load cell 10 can be absorbed by the leaf spring 15. Further, since the strain gauges Z1 to Z4 are provided symmetrically around the support leg 18 on the same surface of the strain generating body, the load applied to the strain gauges Z1 to Z4 is equalized and errors can be eliminated. It is also possible to attach a load cell 10 to the four corners on the back of the weighing pan to constitute a scale as shown in FIGS. Further, the structure in which the support leg 18 passes through the through-hole and the nut 20 is positioned at the upper portion as in the present invention allows the nut 20 to be accessed from above the load cell, thereby improving the operability of assembly and the like.

  9 to 12 are diagrams showing another example of the configuration of the load cell according to claims 1 and 2 of the present invention. FIG. 9 is an external perspective view of the load cell as viewed from obliquely above, FIG. 10 is a plan view, and FIG. 9 is a side view seen from the direction of arrow B in FIG. 9, and FIG. 12 is a side view seen from the direction of arrow C in FIG. As shown in the figure, this load cell has a rectangular support leg fixed integrally with the strain-generating body 11 at the center of a rectangular through-hole 12 formed in the vertical direction at the center of the strain-generating body 11. A part 36 is arranged. Third support members 35, 35 are attached to both sides of the support leg fixing portion 36 with the support leg 18 interposed therebetween so as to protrude from the upper surface by a predetermined dimension.

  Strain gauges Z1 and Z2 are provided on the upper surface of one upper beam 13 (opposite side surface of the strain generating portions 13a and 13b), and strain gauges Z3 and Z4 are provided on the upper surface of the other upper beam 13 (opposite side surface of the strain generating portions 13a and 13b). ). And although illustration is abbreviate | omitted, the board | substrates 26 and 26 (refer FIG. 3) by which the electronic component for incorporating the strain gauges Z1-Z4 in a Wheatstone bridge was mounted in the upper surface of both the upper beams 13 and 13 of the strain body 11 is shown. A substrate 27 (see FIG. 3) on which various electronic components for compensation are mounted is mounted on the upper surface of the stress side end portion of the strain generating body 11, and a DC power supply is input to the output terminal of the substrate 27. Or a cable 28 (see FIG. 3) for outputting a signal is connected.

  In the load cell having the above configuration, the priority side end portion of the load cell 10 is fixed to a mounting attachment portion 30 a provided on the back surface of the weighing pan 30 as shown in FIG. 12. When a large load is applied to the weighing pan 30, the lower surface (back surface) of the weighing pan 30 is disposed on both sides of the first restricting member 17 and the support leg 18 protruding from the upper surface of the support leg fixing portion 36. It abuts on the upper ends of 35 and 35 and suppresses the distortion of the strain body 11 of the load cell 10. An arc-shaped groove 11 a is provided at the connecting portion between the support leg fixing portion 36 and the strain body 11.

  9 to 12, the support leg fixing portion 36 is formed integrally with the strain body 11 and is disposed so as to protrude into the through hole 12 from the fulcrum side of the strain body 11. Therefore, like the load cell having the configuration shown in FIGS. 2 to 5 and 8, the fulcrum side of the strain-generating body 11 is coupled to the support leg 18 passing through the through hole provided in the substantially central portion of the strain-generating body 11 by the coupling means. As a result, the configuration becomes simple, the scale itself using the load cell can be made thin, and the substantially central portion prevents the measurement accuracy from being lowered because the load is applied almost evenly to the load cell. Further, as shown in FIGS. 2 to 5, since the fulcrum side of the strain generating body 11 is not coupled to the support leg 18 via the leaf spring 15, the thickness can be further reduced by the absence of the leaf spring 15. Naturally, the load cell 10 having the configuration shown in FIGS. 9 to 12 may be attached to the four corners of the back surface of the weighing pan to constitute the balance shown in FIGS.

  FIGS. 13 to 15 are diagrams showing another configuration example of the load cell according to claims 1 and 2 of the present invention. FIG. 13 is a plan view, FIG. 14 is a side view, and FIG. 15 is an external perspective view seen from below. . As shown in the figure, the load cell 10 includes a strain body 11 having two beams 13 and 14 that are arranged in parallel vertically and are integrally formed, and the two beams above and below the strain body 11. In this configuration, a circular through hole 39 penetrating the substantially central portion of 13 and 14 is provided, and the fulcrum side of the strain body 11 is coupled to the support leg 18 passing through the through hole 39 via a plate-shaped coupling member 38. . Strain gauges Z1 and Z2 are provided on the opposite side surfaces (upper surface) of the strain generating portions 13a and 13b with the through hole 39 of the upper beam 13 interposed therebetween, and the opposite side surfaces of the strain generating portions 14a and 14b with the through hole 39 of the lower beam 14 interposed therebetween. Strain gauges Z3 and Z4 are provided on the (lower surface).

  Although illustration is omitted, a substrate on which electronic components for incorporating strain gauges Z1 to Z4 into the Wheatstone bridge are mounted on the upper surface of the upper beam 13 and the lower surface of the lower beam 14 of the strain generating body 11, and the strain generating body 11 is provided with a substrate on which various electronic components for compensation are mounted, and a cable for inputting a DC power source or outputting a signal is connected to an output terminal of the substrate. (See FIG. 3).

  Two first restricting members 37 are erected on the upper surface of the plate-like coupling member 38 at portions located on both sides of the strain-generating body 11 and at the center in the longitudinal direction of the upper and lower beams 13 and 14.

  In the load cell having the above configuration, the priority side end of the load cell 10 is fixed to a mounting portion 30 a provided on the back surface of the weighing pan 30 as shown in FIG. 14. When a large load is applied to the weighing pan 30, the lower surface (back surface) of the weighing pan 30 comes into contact with the upper end of the first regulating member 37, and the distortion of the strain body 11 of the load cell 10 is suppressed.

  Since the load cell has the configuration shown in FIGS. 13 to 15, the fulcrum side of the strain generating body 11 is coupled to the support leg 18 that passes through the through hole provided in the substantially central portion of the strain generating body 11 by the coupling means. The structure of the distorted body 11 is simple, and the balance itself using the load cell can be made thin, and the load can be applied to the load cell almost uniformly because of the substantially central portion, thereby preventing a reduction in measurement accuracy. Naturally, it is possible to construct the balance shown in FIGS. 6 and 7 by attaching the load cell 10 having the configuration shown in FIGS.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible. For example, when the length of the support leg 18 can be adjusted so that the upper end of the support leg 18 is located above the upper surface of the nut 20, a recess is formed at a position where the upper end of the support leg 18 on the back of the weighing pan 30 faces. You may make it provide.

It is a figure which shows the structural example of the conventional load cell. It is a side view which shows the structural example of the load cell which concerns on this invention. It is a bottom view which shows the structural example of the load cell (except a support stand) which concerns on this invention. It is a sectional side view (AA sectional drawing of FIG. 3) which shows the structural example of the load cell which concerns on this invention. It is the perspective view seen from the lower part which shows the structural example of the load cell which concerns on this invention. It is a partially notched top view of the balance which concerns on this invention. It is sectional drawing (BB sectional drawing of FIG. 6) of the balance which concerns on this invention. It is the perspective view seen from the top which shows the example of composition of the load cell concerning the present invention. It is the perspective view seen from the lower part which shows the structural example of the load cell which concerns on this invention. It is a top view which shows the structural example of the load cell which concerns on this invention. FIG. 10 is a side view illustrating a configuration example of a load cell according to the present invention (a side surface viewed from the direction of arrow B in FIG. 9). FIG. 10 is a side view illustrating a configuration example of a load cell according to the present invention (a side surface viewed from the direction of arrow C in FIG. 9). It is a top view which shows the structural example of the load cell which concerns on this invention. It is a side view which shows the structural example of the load cell which concerns on this invention. It is the perspective view seen from the lower part which shows the structural example of the load cell which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Load cell 11 Strain body 12 Through-hole 13 Upper beam 14 Lower beam 15 Leaf spring 16 Bolt 17 Restriction member 18 Support leg 19 Nut 20 Nut 21 Support stand 22 Metal plate 23 Steel ball 24 Lid member 25 Connecting member 26 Substrate 27 Substrate 28 Cable 30 Weighing pan 31 Bolt 32 Bolt 33 Bolt 36 Support leg fixing part 37 Restriction member 38 Plate-like coupling member 39 Through hole

Claims (6)

A load cell having a configuration in which a strain body having a beam that is arranged in parallel vertically and integrally formed, and a strain gauge is provided in the vicinity of the strain section formed at a predetermined position of the beam of the strain body There,
A through hole is provided in a substantially central portion of the beam in the vertical direction, a support leg for supporting the strain body through the through hole is provided, and a fulcrum side of the strain body is coupled to the support leg. A load cell characterized by being combined with The load cell according to claim 1, wherein
2. The load cell according to claim 1, wherein the beam is arranged on both sides and vertically in parallel with a through hole provided in a substantially central portion of the strain generating body penetrating in the vertical direction. The load cell according to claim 1 or 2,
The load cell is characterized in that the coupling means is configured to couple a fulcrum side of the strain generating body to the support leg via a leaf spring member attached to a lower portion on the fulcrum side of the strain generating body. The load cell according to any one of claims 1 to 3,
The strain gauge is located on both sides of the strain-generating body through the through-hole and in the vicinity of the strain-generating portion of the beam arranged in parallel vertically and on the same surface on the front and / or back surface of the strain-generating body. A load cell provided at a symmetrical position with the support leg as a center. The load cell according to any one of claims 1 to 4,
A load cell characterized in that a regulating member that protrudes from the upper surface of the strain generating body by a predetermined dimension is disposed at the upper end of the support leg through the through hole of the strain generating body. In a scale configured to support the four corners of the weighing pan on the priority side of the four load cells,
A scale using the load cell according to any one of claims 1 to 4 as the load cell.

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