Load cells and combination scales

Abstract

To provide a load cell and combination scale that can improve weighing accuracy. [Solution] Each of the following is provided: fixed part 11 and movable part 12 arranged at intervals in the X-axis direction; upper and lower beam parts 13 and 14 arranged parallel to each other at intervals in the vertical direction, connecting the fixed part 11 and the movable part 12, and having a plurality of strain generating parts D1 to D4 to which strain gauges G are attached; first and second Roberval mechanism parts 2 and 3 arranged parallel to each other in the Y-axis direction perpendicular to the X-axis direction; and first and second connecting parts 4 and 5 (connecting parts) that connect the fixed parts 11 and the movable parts 12 of the first and second Roberval mechanism parts 2 and 3, respectively; the plurality of strain gauges G are arranged offset from the center C of the plurality of strain generating parts D1 to D4 in the Y-axis direction (second horizontal direction).

Description

Technical Field

[0007]

[0001] The present invention relates to the technology of load cells and combination scales.

Background Art

[0002] Conventionally, the technology of load cells for weighing objects to be weighed has been known. For example, it is as described in Patent Document 1.

[0003] Patent Document 1 has, respectively, a fixed part and a movable part, and a pair of beam parts formed with a plurality of strain generating parts that connect the fixed part and the movable part and to which strain gauges are attached, and first and second Roberval mechanism parts arranged horizontally side by side and in parallel, and a connecting part that connects the fixed parts and the movable parts of the first and second Roberval mechanism parts. A load cell is described.

[0004] A load cell as described above is used, for example, in a combination scale, and a load receiving member such as a tray or a hopper for holding an object to be weighed is detachably attached to the connecting part on the movable part side. Thus, when the attached load receiving member holds the object to be weighed, the load cell can measure the deflection of the pair of beam parts due to the load of the object to be weighed with the strain gauges and weigh the object to be weighed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the load cell and the combination scale as described above, further improvement in weighing accuracy is required.

[0007] The present invention aims to provide a load cell and a combination scale that can improve weighing accuracy in order to solve the above problems. [Means for solving the problem]

[0008] To achieve the above objective, a load cell according to one aspect of the present invention includes, each having a fixed portion and a movable portion arranged at intervals in a first horizontal direction, and a pair of beam portions arranged parallel to each other at intervals in the vertical direction, connecting the fixed portion and the movable portion, and having a plurality of strain-generating portions to which strain gauges are attached; first and second Roberval mechanism portions arranged parallel to each other in a second horizontal direction perpendicular to the first horizontal direction; and connecting portions that connect the fixed portions and the movable portions of the first and second Roberval mechanism portions, respectively, wherein the plurality of strain gauges are arranged offset from the center of the plurality of strain-generating portions in the first horizontal direction. [Effects of the Invention]

[0009] According to the present invention, it is possible to improve the accuracy of weighing. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic front view showing an example of a combination scale equipped with a load cell according to the first embodiment. [Figure 2] Figure 2 is a perspective view showing an example of a load cell according to the first embodiment. [Figure 3] Figure 3 is a schematic perspective view showing the arrangement of the load cells shown in Figure 2. [Figure 4] Figure 4(a) is a plan view of the load cell shown in Figure 2, and Figures 4(b), (c), and (d) are side views of the same load cell from different directions. [Figure 5] Figure 5 is a plan view of a load cell showing an example of the results of an analysis of the deformed portion and the amount of deformation of that portion when a moment load is applied. [Figure 6] Figure 6 is a plan view showing the arrangement of strain gauges according to the first embodiment. [Figure 7] Figure 7 is a plan view showing the arrangement of strain gauges according to the second embodiment. [Figure 8] Figure 8 is a plan view showing the arrangement of strain gauges according to the conventional technology. [Modes for carrying out the invention]

[0011] First, using Figure 1, we will describe a combination scale 100 equipped with a load cell 1 according to one embodiment of the present invention.

[0012] The combination scale 100 according to this embodiment determines a combination in which the total weight of the weighed items falls within a predetermined weight range. In this embodiment, the combination scale 100 is automatic, but it may also be semi-automatic or manual. Various granular weighed items (e.g., grains, dried fruits, and other foods) can be used as the weighed items. The combination scale 100 is configured to discharge the determined combination of weighed items to the packaging machine 200.

[0013] The combination scale 100 comprises, for example, a supply device 110, a base 120, a distribution feeder 130, a linear feeder 150, a supply hopper 160, a weighing hopper 170, and a collection unit 90.

[0014] The supply device 110 transports the object to be weighed toward the tip and drops it downward (to the distribution feeder 130). The base 120 is positioned below the tip of the supply device 110 and is located approximately in the center of the combination scale 100 in a plan view. The base 120 is formed in a hollow, roughly box-like shape and houses various devices inside.

[0015] The distribution feeder 130 is positioned above the base 120. The distribution feeder 130 distributes the material to be weighed, supplied from the supply device 110, radially outward in a plan view, and drops it downward (to the straight feeder 150). The straight feeder 150 moves the material to be weighed, supplied from the distribution feeder 130, toward the front end and drops it downward (to the supply hopper 160).

[0016] The supply hopper 160 is substantially box-shaped with an open top and has an opening / closing gate 161 at its bottom. The supply hopper 160 can store the metered material supplied from the straight feeder 150 when the gate 161 is closed. Also, the supply hopper 160 can switch the gate 161 from the closed state to the open state to supply the stored metered material to the weighing hopper 170.

[0017] The weighing hopper 170 is substantially box-shaped with an open top and has an opening / closing gate 171 at its bottom. Also, the weighing hopper 170 has a load cell 1 for measuring the weight of the metered material. The weighing hopper 170 can store the metered material supplied from the supply hopper 160 when the gate 171 is closed and can measure the weight of the stored weighted material by the load cell 1. Also, the weighing hopper 170 can switch the gate 171 from the closed state to the open state to supply the stored metered material to the collecting section 190.

[0018] The collecting section 190 is configured to collect the metered material supplied from the weighing hopper 170 and be capable of being input into the packaging machine 200.

[0019] Next, the configuration of the load cell 1 according to an embodiment of the present invention will be described with reference to FIGS. 2 to 4.

[0020] In the description of this specification, the X-axis direction, the Y-axis direction, and the Z-axis direction are defined according to the arrows shown in the figures. In this specification, the X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to each other. The X-axis direction and the Y-axis direction represent the horizontal direction, and the Z-axis direction represents the vertical direction. Also, in this specification, the Z-axis direction may be simply referred to as the up-and-down direction. Also, the X-axis direction and the Y-axis direction respectively correspond to the "first horizontal direction" and the "second horizontal direction" according to the present invention.

[0021] Figure 2 is a perspective view showing an example of the load cell 1 of this embodiment. Figure 3 is a schematic perspective view showing the arrangement of the load cell 1. Figure 4(a) is a plan view of the load cell 1 shown in Figure 2, Figure 4(b) is a side view of the load cell 1 viewed from the direction of arrow b in Figure 4(a) (one side in the X-axis direction), Figure 4(c) is a side view of the load cell 1 viewed from the direction of arrow c in Figure 4(a) (the other side in the X-axis direction), and Figure 4(d) is an enlarged view of the side view of the load cell 1 viewed from the direction of arrow d in Figure 4(a) (Y-axis direction). Note that in Figure 4(d), only the first Roberval mechanism 2 and its vicinity, which will be described later, are shown, and the stopper member 6 and the like are not shown.

[0022] The load cell 1 of this embodiment measures the material to be weighed stored in the weighing hopper 170 as described above. The load cell 1 includes first and second Roberval mechanisms 2 and 3, first and second connecting parts 4 and 5 that connect the first and second Roberval mechanisms 2 and 3, a stopper member 6, and a plurality of strain gauges G, etc.

[0023] The first and second Roberval mechanisms 2 and 3 have the same configuration and are arranged horizontally apart and parallel to each other.

[0024] Each Roberval mechanism 2,3 has a columnar fixed part 11 that is supported and fixed, a columnar movable part 12 onto which a load is applied, an upper beam part 13 connecting the upper part of the fixed part 11 and the upper part of the movable part 12, and a lower beam part 14 connecting the lower part of the fixed part 11 and the lower part of the movable part 12. The upper beam part 13 and the lower beam part 14 are spaced apart in the vertical direction, and multiple strain-generating parts D1 to D4 made of thin-walled portions are formed at two symmetrical locations in the vertical direction of each. Strain gauges G for load detection are attached to the outer surfaces (upper and lower surfaces) of each strain-generating part D1 to D4.

[0025] The first connecting part 4 connects the fixed parts 11, 11 of the first and second Roberval mechanism parts 2, 3, and the second connecting part 5 connects the movable parts 12, 12 of the first and second Roberval mechanism parts 2, 3. Each fixed part 11, 11 is provided with a fixing hole 21 for fixing the load cell 1. In this embodiment, the load cell 1 is attached to the base body 120 of the combination scale 100 using the hole 21 (see Figure 3). The first connecting part 4 is used to attach the load cell 1 to the base body 120, and the second connecting part 5 is provided with a hole 22 for attaching a weighing hopper 170, such as a tray or hopper, for holding the object to be weighed. In this embodiment, as shown in Figure 3, the weighing hopper 170 is attached to the second connecting part 5 via a mounting device inserted into the hole 22. Multiple holes 22 are provided (two in this embodiment) and are arranged spaced apart from each other in the Y-axis direction. In this way, when the object to be weighed is held in the weighing hopper 170, a load is applied to the second connecting part 5, which is provided with a hole 22, and the movable parts 12, 12 connected thereto.

[0026] In each of the above-described Roberval mechanisms 2 and 3, the fixed part 11 and the movable part 12 are arranged at a distance from each other in the X-axis direction, and the first Roberval mechanism 2 and the second Roberval mechanism 3 are arranged parallel to each other in the Y-axis direction, which is perpendicular to the X-axis direction. The first connecting part 4 and the second connecting part 5 are each formed extending in the Y-axis direction and are arranged parallel to each other in the X-axis direction.

[0027] The stopper member 6 is a component that prevents damage to the load cell 1 due to overload. To attach this stopper member 6, the first connecting portion 4 is provided with a first projection 40 that extends from its center along the X-axis toward the second connecting portion 5, and a stepped hole 41 is provided that penetrates the first projection 40 and the first connecting portion 4 in the X-axis direction. In addition, the second connecting portion 5 is provided with a second projection 50 that extends from its center along the X-axis toward the first connecting portion 4, and a through hole 51 is provided that penetrates the second projection 50 and the second connecting portion 5 in the X-axis direction.

[0028] Furthermore, the first and second protrusions 40 and 50 may be located away from the central parts of the first and second connecting parts 4 and 5, respectively. That is, the first protrusion 40 is provided in the middle of the Y-axis extension of the first connecting part 4, and the second protrusion 50 is provided in the middle of the Y-axis extension of the second connecting part 5, with the first protrusion 40 and the second protrusion 50 being located opposite each other. Thus, the first and second protrusions 40 and 50 are provided away from the first Roberval mechanism 2 and the second Roberval mechanism 3, and in a position between them, facing each other.

[0029] Furthermore, the first projection 40 extends beyond the positions of the strain-generating portions D1 and D3 on the fixed portion 11 side towards the movable portion 12 side (towards the second connecting portion 5 side) in the X-axis direction. The second projection 50 extends beyond the positions of the strain-generating portions D2 and D4 on the movable portion 12 side towards the fixed portion 11 side (towards the first connecting portion 4 side) in the X-axis direction. The first and second projections 40 and 50 are formed integrally with the first and second connecting portions 4 and 5, respectively. The upper and lower surfaces of the first projection 40 are on the same plane as the upper surface 4a and lower surface 4b of the first connecting portion 4, respectively, and the upper and lower surfaces of the second projection 50 are on the same plane as the upper surface 5a and lower surface 5b of the second connecting portion 5, respectively.

[0030] The stopper member 6 is inserted from the outside of the stepped hole 41 and then further inserted into the through hole 51. At this time, the base end of the stopper member 6 is press-fitted into the stepped hole 41, thereby fixing the stopper member 6 in the stepped hole 41. The diameter of the tip end of the stopper member 6 is configured to be smaller than the diameter of the through hole 51. Under normal circumstances (when no excessive load exceeding the allowable range is applied), the tip end of the stopper member 6 does not contact the inner wall of the through hole 51. However, when an excessive load exceeding the allowable range is applied to the movable parts 12, 12 and the second connecting part 5, the tip end of the stopper member 6 comes into contact with the inner wall of the through hole 51, thereby preventing further deflection of the upper and lower beam parts 13, 14 and preventing damage to the load cell 1 due to overload.

[0031] In this embodiment, the entire upper surface Fa and the entire lower surface Fb of the first and second Roberval mechanism parts 2 and 3 are set back from the upper surfaces 4a and 5a and lower surfaces 4b and 5b of the first and second connecting parts 4 and 5, and strain gauges G are attached to the portions of these set-back surfaces corresponding to the strain-generating portions D1 to D4.

[0032] Specifically, the entire upper surface Fa of the first and second Roberval mechanism parts 2 and 3 is set back and lower than the upper surfaces 4a and 5a of the first and second connecting parts 4 and 5, and strain gauges G are attached to the portions of this set-back upper surface Fa corresponding to the strain-generating portions D1 and D2. Furthermore, the entire lower surface Fb of the first and second Roberval mechanism parts 2 and 3 is set back and higher than the lower surfaces 4b and 5b of the first and second connecting parts 4 and 5, and strain gauges G are attached to the portions of this set-back lower surface Fb corresponding to the strain-generating portions D3 and D4.

[0033] A brief explanation of the manufacturing method for this load cell 1 will be given. For example, a rectangular parallelepiped strain-generating body made of aluminum or the like is processed to form the parts other than the strain gauge G and stopper member 6. The strain gauge G and stopper member 6 are prepared separately. The stopper member 6 may be made of the same material as the strain-generating body, or it may be made of a different material.

[0034] When processing the above-described rectangular parallelepiped strain-generating body, for example, in a plan view, the area enclosed by the first and second Roberval mechanism parts 2,3, the first and second connecting parts 4,5, and the first and second protruding parts 40,50 is hollowed out to form the internal space Sp1. Next, in the formation areas of the first and second Roberval mechanism parts 2,3, the area enclosed by the fixed part 11 and movable part 12 and the upper beam part 13 and lower beam part 14 is hollowed out from the respective side directions to form space Sp2. In this case, the arc-shaped regions corresponding to the strain-generating parts D1 to D4 may be formed last.

[0035] Next, the entire upper and lower surfaces of the first and second Roberval mechanism parts 2 and 3 are cut or ground to form surfaces (upper surface Fa and lower surface Fb) that are recessed from the upper surfaces 4a, 5a and lower surfaces 4b, 5b of the first and second connecting parts 4 and 5.

[0036] Next, the stopper member 6 is attached, and the strain gauges G are glued to the upper surface Fa and lower surface Fb of the first and second Roberval mechanisms 2 and 3.

[0037] In this embodiment, the device (load cell 1) can be made thinner by arranging the first Roberval mechanism 2 and the second Roberval mechanism 3 horizontally and parallel to each other. Furthermore, by machining the entire upper and lower surfaces of the first and second Roberval mechanisms 2 and 3, the upper surface Fa and lower surface Fb can be formed that are recessed from the upper surfaces 4a, 5a and lower surfaces 4b, 5b of the first and second connecting parts 4 and 5, thus facilitating processing. In addition, during transportation and installation of the load cell 1, contact between the strain gauges G attached to the upper surface Fa and lower surface Fb and other objects can be avoided, thereby preventing damage to the strain gauges G.

[0038] Furthermore, in this embodiment, the first protrusion 40 for providing the stopper mechanism is provided extending outwards from the movable part 12 side (the second connecting part 5 side), and the upper and lower surfaces of the first protrusion 40 are on the same plane as the upper surface 4a and lower surface 4b of the first connecting part 4, respectively. The second protrusion 50 is provided extending outwards from the fixed part 11 side (the first connecting part 4 side), and the upper and lower surfaces of the second protrusion 50 are on the same plane as the upper surface 5a and lower surface 5b of the second connecting part 5, respectively. Therefore, since the upper and lower surfaces of the first and second protrusions 40 and 50 extend above and below the upper surface Fa and lower surface Fb to which the strain gauge G is attached, it is possible to better avoid contact between the strain gauge G and other objects, and to better prevent damage to the strain gauge G.

[0039] Furthermore, in this embodiment, the surfaces of the strain gauges G attached to the upper surface Fa and lower surface Fb of the first and second Roberval mechanism parts 2 and 3 are set back from the upper surfaces 4a, 5a and lower surfaces 4b, 5b of the first and second connecting parts 4 and 5, thereby further preventing damage to the strain gauges G.

[0040] Alternatively, the entire upper surface Fa and the entire lower surface Fb of the first and second Roberval mechanism parts 2 and 3 may be set back from either the upper surface 4a, 5a and the lower surface 4b, 5b of the first and second connecting parts 4 and 5, and a strain gauge G may be attached to the portion of this set-back surface corresponding to the strain-generating area. In this case, the strain gauge G is attached only to the set-back surface of the entire upper surface Fa and the entire lower surface Fb of the first and second Roberval mechanism parts 2 and 3.

[0041] In the load cell 1 configured in this way, when the weighing hopper 170 is attached to the two holes 22 as described above, the loads acting on each hole 22 from the weighing hopper 170 may not be exactly the same (they may be slightly different). When the loads acting on each hole 22 are different in this way, a force is generated on the second connecting part 5 side of the load cell 1 where the holes 22 are provided (the side of the movable part 12 in the X-axis direction) that causes it to tilt to one side in the Y-axis direction. In other words, a force (hereinafter referred to as "moment load") is generated in the load cell 1 that causes the movable part 12 to twist relative to the fixed part 11.

[0042] When a moment load is applied in this way, a portion of the load cell 1 may deform. Figure 5 shows an example of the results of analyzing the deformed portion of the load cell 1 and the amount of deformation of that portion when a moment load is applied to the load cell 1. In Figure 5, the portion with a change in color in part of the whole is the deformed portion, and the portion with a darker color within that deformed portion is deformed more than the portion with a lighter color. As shown in Figure 5, when a moment load is applied, the strain-generating portions D1 to D4, which are made up of thin-walled parts of the load cell 1, deform more than other parts.

[0043] Specifically, when a moment load is applied, the deformation in the strained areas D1 to D4 is greater on the side opposite to the first and second connecting parts 4 and 5 in the Y-axis direction (hereinafter referred to as the "outer side in the Y-axis direction" with respect to each strained area, see Figure 5) than on the side of the first and second connecting parts 4 and 5 in the Y-axis direction (hereinafter referred to as the "inner side in the Y-axis direction" with respect to each strained area, see Figure 5).

[0044] Furthermore, when a moment load is applied, the deformation in the strained sections D1 to D4 is greater on the side of the movable part 12 in the X-axis direction (hereinafter sometimes referred to as the "movable side in the X-axis direction," see Figure 5) than on the side of the fixed part 11 in the X-axis direction (hereinafter sometimes referred to as the "fixed side in the X-axis direction," see Figure 5).

[0045] Figure 5 shows an example of the analysis results as described above. When a moment load is applied, the deformation areas (locations of deformation) of the strain-generating parts D1 to D4 show a generally similar trend regardless of the magnitude of the moment load, and it is assumed that the amount of deformation of these deformation areas changes according to the magnitude of the moment load. Figure 5 shows the upper surface of load cell 1, but the lower surface of load cell 1 shows a generally similar trend.

[0046] In this case, the weighing hopper 170 may be removed from the load cell 1, for example, for cleaning. After being cleaned by an operator, the removed weighing hopper 170 is reattached to the load cell 1. When the weighing hopper 170 is attached and detached in this manner, the way the load from the weighing hopper 170 is applied to the two holes 22 differs before and after attachment and detachment, and the moment load generated in the load cell 1 may differ. In this case, the amount of deformation of the deformed parts of the strain-generating sections D1 to D4 will change according to the moment load.

[0047] If the amount of deformation of the deformed parts of the strain-generating sections D1 to D4 differs before and after the attachment and detachment of the weighing hopper 170, the strain gauges G attached to the strain-generating sections D1 to D4 may deform before and after the attachment and detachment. In other words, when the weighing hopper 170 is attached or detached, errors may occur in the subsequent weighing of the load cell 1.

[0048] Therefore, the load cell 1 according to this embodiment has a distinctive configuration to suppress errors in subsequent weighing of the load cell 1, even when the weighing hopper 170 is attached or detached. Specifically, the load cell 1 has a significantly different arrangement of strain gauges G compared to the conventional technology.

[0049] The arrangement of strain gauges G according to the first and second embodiments will be described below with reference to Figures 6 and 7.

[0050] Figures 6 and 7 are plan views focusing on each Roberval mechanism 2 and 3 of the load cell 1. Note that the arrangement of the strain gauges G in the first and second embodiments is the same (vertically symmetrical) on the upper surface Fa and lower surface Fb of each Roberval mechanism 2 and 3, so the bottom views focusing on each Roberval mechanism 2 and 3 are omitted in the following description. Also, the strain gauges G in the first and second embodiments are arranged in the same position (symmetrical in the Y-axis direction) in each Roberval mechanism 2 and 3.

[0051] In the first and second embodiments, the strain gauges G are attached to the upper surfaces of the strain generating sections D1 and D2 in the upper beam section 13 of each Roberval mechanism section 2 and 3 (see Figure 4). Here, in the prior art (see, for example, Japanese Patent Application Publication No. 2021-81292 shown in Patent Document 1), a typical strain gauge is positioned in the center in the Y-axis direction on the upper surface of the strain generating section to balance it in the Y-axis direction, as shown in Figure 8.

[0052] In contrast, the strain gauge G according to the present invention is positioned offset from the center C of the strain-generating portions D1 and D2 in the Y-axis direction (see the dashed line in the figure).

[0053] First, the arrangement of the strain gauge G according to the first embodiment will be described in detail using Figure 6.

[0054] The strain gauge G is positioned in the Y-axis direction between the center C of the strain-generating sections D1 and D2 and the inner ends E of the strain-generating sections D1 and D2 in the Y-axis direction. That is, the outer end A of the strain gauge G in the Y-axis direction is positioned inward in the Y-axis direction from the center C. Also, the inner end B of the strain gauge G in the Y-axis direction is positioned outward in the Y-axis direction from the inner ends E of the strain-generating sections D1 and D2 in the Y-axis direction. In this way, the strain gauge G is positioned so as not to overlap with the center C of the strain-generating sections D1 and D2 in the Y-axis direction. Furthermore, the strain gauge G is positioned spaced apart from the inner ends E of the strain-generating sections D1 and D2 in the Y-axis direction.

[0055] As shown in Figure 5, when a moment load is applied to the load cell 1, the deformation of the strain-generating parts D1 and D2 is greater on the outer side in the Y-axis direction than on the inner side in the Y-axis direction. In contrast, in the configuration according to the first embodiment, the strain gauge G is positioned on the upper surface of the strain-generating parts D1 and D2, inward in the Y-axis direction from the center C. Therefore, even when a moment load is applied, the strain gauge G is positioned in the part of the strain-generating parts D1 and D2 that is relatively difficult to deform. This suppresses deformation of the strain gauge G attached to the strain-generating parts D1 and D2 before and after the attachment and detachment of the weighing hopper 170 (more specifically, it suppresses changes in the amount of deformation even if deformation occurs), thereby improving weighing accuracy. In other words, even when the weighing hopper 170 is attached and detached, errors in subsequent weighing of the load cell 1 can be suppressed.

[0056] Furthermore, since the strain gauge G is positioned at a distance from the inner ends E of the strain-generating portions D1 and D2 in the Y-axis direction (i.e., not exposed from the inner ends E in the Y-axis direction), it is possible to prevent other components, such as the weighing hopper 170, from coming into contact with the strain gauge G when attaching or detaching the weighing hopper 170. In this way, it is possible to prevent the strain gauge G from being damaged or deformed, thereby improving the weighing accuracy of the load cell 1.

[0057] Next, the arrangement of the strain gauge G according to the second embodiment will be described in detail with reference to Figure 7.

[0058] In the following, the arrangement of the strain gauges G according to the second embodiment will be described, focusing on the differences from the first embodiment. The main difference between the arrangement of the strain gauges G according to the second embodiment and the first embodiment is that the two strain gauges G attached to the upper surfaces of the strain generating sections D1 and D2 are positioned differently in the Y-axis direction. In the following, of the two strain gauges G attached to the upper surfaces of the strain generating sections D1 and D2, the one fixed in the X-axis direction may be referred to as the "fixed strain gauge G1," and the one movable in the X-axis direction may be referred to as the "movable strain gauge G2."

[0059] In the second embodiment, the strain gauges G1 and G2 are positioned on the upper surfaces of the strain-generating portions D1 and D2, in the Y-axis direction, relative to the center C, similar to the first embodiment. The movable strain gauge G2 is positioned in the Y-axis direction relative to the fixed strain gauge G1. More specifically, the movable strain gauge G2 is positioned near the Y-axis direction relative ends E of the strain-generating portions D1 and D2. Thus, the Y-axis direction relative end B of the movable strain gauge G2 is positioned in the Y-axis direction relative to the Y-axis direction relative end B of the fixed strain gauge G1.

[0060] As shown in Figure 5, when a moment load is applied to the load cell 1, the deformation of the strain-generating portion D1 and D2 is greater on the movable side in the X-axis direction than on the fixed side in the X-axis direction. In contrast, in the second embodiment, the strain gauges G1 and G2 are positioned on the upper surface of the strain-generating portion D1 and D2, in the Y-axis direction inward from the center C, and the movable strain gauge G2 is positioned inward in the Y-axis direction than the fixed strain gauge G1.

[0061] According to this, when comparing the locations in the X-axis direction where strain gauges G1 and G2 are attached, the movable strain gauge G2, which is attached to the more easily deformable part, can be positioned inward in the Y-axis direction (a part that is relatively less deformable in the Y-axis direction). This makes it possible to more effectively suppress the deformation of strain gauges G1 and G2 attached to the strain-generating parts D1 and D2 before and after the attachment and detachment of the weighing hopper 170, and to further improve the weighing accuracy of the load cell 1. Therefore, even when the weighing hopper 170 is attached and detached, errors in subsequent weighing of the load cell 1 can be effectively suppressed.

[0062] As described above, in the load cell 1 according to this embodiment (first and second embodiment), Each has a fixed part 11 and a movable part 12 arranged at intervals in the X-axis direction (first horizontal direction), and upper and lower beam parts 13, 14 (a pair of beam parts) arranged parallel to each other at intervals in the vertical direction, connecting the fixed part 11 and the movable part 12, and having a plurality of strain-generating parts D1 to D4 to which strain gauges G are attached, and first and second Roberval mechanism parts 2, 3 arranged parallel to each other in the Y-axis direction (second horizontal direction) perpendicular to the X-axis direction (first horizontal direction), The first and second connecting parts 4 and 5 (connecting parts) connect the fixed parts 11 and the movable parts 12 of the first and second Roberval mechanism parts 2 and 3, respectively. Equipped with, The multiple strain gauges G are positioned offset from the center C of the multiple strain-generating portions D1 to D4 in the Y-axis direction (second horizontal direction).

[0063] More preferably, in the load cell 1 according to this embodiment (first and second embodiment), The multiple strain gauges G are positioned so as to be offset in the Y-axis direction (second horizontal direction) from the center C of the multiple strain-generating portions D1 to D4 towards the first and second connecting portions 4 and 5 (inward in the Y-axis direction).

[0064] More preferably, in the load cell 1 according to this embodiment (first and second embodiment), The multiple strain gauges G are arranged so as not to overlap with the center C of the multiple strain-generating portions D1 to D4 in the Y-axis direction (second horizontal direction).

[0065] With this configuration, for example, deformation of the strain gauges G attached to the strain-generating parts D1 and D2 before and after the attachment and detachment of the weighing hopper 170 can be suppressed (more specifically, even if deformation occurs, the amount of deformation cannot be changed), thereby improving weighing accuracy. In other words, even if the weighing hopper 170 is attached or detached, errors in subsequent weighing of the load cell 1 can be suppressed.

[0066] Furthermore, in the load cell 1 according to this embodiment (first and second embodiment), The multiple strain gauges G are arranged spaced apart from the inner ends E (connecting end) in the Y-axis direction of the multiple strain-generating portions D1 to D4.

[0067] With this configuration, for example, when attaching or detaching the weighing hopper 170, it is possible to suppress changes in the attachment state of the strain gauge G, thereby improving weighing accuracy. In other words, it is possible to suppress errors in the weighing of the load cell 1.

[0068] Furthermore, in the load cell 1 according to this embodiment (second embodiment), In each of the Roberval mechanisms 2 and 3, the multiple strain gauges G are arranged offset from each other in the X-axis direction (first horizontal direction).

[0069] Furthermore, preferably, in the load cell 1 according to this embodiment (second embodiment), Of the plurality of strain gauges G, the strain gauge G on the movable part 12 side in the X-axis direction (first horizontal direction) is positioned offset in the Y-axis direction (second horizontal direction) toward the first and second connecting parts 4 and 5 side (inward in the Y-axis direction) compared to the strain gauge G on the fixed part 11 side in the X-axis direction (first horizontal direction).

[0070] With this configuration, when comparing the locations where strain gauges G1 and G2 are attached (i.e., in the X-axis direction), the movable strain gauge G2, which is attached to the more easily deformable part, can be positioned inward in the Y-axis direction (a part that is relatively less deformable in the Y-axis direction).

[0071] Furthermore, in the combination scale 100 according to this embodiment, The system comprises a load cell 1 according to the (first and second embodiments) and performs combination calculations based on the weight of the object to be weighed measured by the load cell 1.

[0072] With this configuration, for example, deformation of the strain gauges G attached to the strain-generating parts D1 and D2 before and after the attachment and detachment of the weighing hopper 170 can be suppressed, thereby improving weighing accuracy. In other words, even when the weighing hopper 170 is attached or detached, the combination scale 100 can suppress errors in subsequent weighing.

[0073] Although embodiments of the present invention have been described above, the present invention is not limited to the above configuration, and various modifications are possible within the scope of the invention as described in the claims.

[0074] For example, the strain gauge G may be positioned on the upper surface of the strain-generating sections D1 and D2, outward in the Y-axis direction from the center C. This improves the weighing accuracy when a moment load is generated and the load cell 1 deforms more inward in the Y-axis direction than outward in the strain-generating sections D1 to D4.

[0075] Furthermore, the arrangement of the strain gauges G according to the first and second embodiments is not limited to these. For example, the outer end A of the strain gauge G in the Y-axis direction may overlap with the center C in the Y-axis direction. Also, the strain gauge G may overlap with the inner end E of the strain generating sections D1 and D2 in the Y-axis direction. Moreover, the arrangement of the strain gauges G may differ on the upper surface Fa and the lower surface Fb of each Roberval mechanism section 2 and 3.

[0076] Furthermore, it is not necessary for all strain gauges G to be positioned offset from the center C of the multiple strain-generating sections D1 to D4 in the Y-axis direction (second horizontal direction); some of the strain gauges G may be positioned offset (i.e., the positioning of some of the strain gauges G does not need to be offset from the center C of the multiple strain-generating sections D1 to D4).

[0077] Furthermore, the number of strain gauges G is not limited to that of this embodiment. That is, one or more strain gauges G may be provided on the upper surface Fa and lower surface Fb of each Roberval mechanism 2,3. [Explanation of Symbols]

[0078] 1 load cell 2. First Roberval mechanism 3. Second Roberval mechanism 4. First connecting section 5. Second connecting section 11 Fixed part 12 Moving parts 13 Upper beam section 14 Lower beam section D1~D4 Strain part G strain gauge

Claims

1. Each has a fixed part and a movable part arranged at intervals in the first horizontal direction, and a pair of beam parts arranged parallel to each other at intervals in the vertical direction, connecting the fixed part and the movable part, and having a plurality of strain-generating parts to which strain gauges are attached, and first and second Roberval mechanism parts arranged parallel to each other in a second horizontal direction perpendicular to the first horizontal direction, A connecting portion that connects the fixed portions and the movable portions of the first and second Roberval mechanism, Equipped with, The multiple strain gauges are arranged offset from the center of the multiple strain-generating portions in the second horizontal direction. Load cell.

2. The multiple strain gauges are positioned so as to be offset in the second horizontal direction from the center of the multiple strain-generating portions toward the connecting portion. The load cell according to claim 1.

3. The multiple strain gauges are arranged so as not to overlap with the centers of the multiple strain-generating portions in the second horizontal direction. The load cell according to claim 2.

4. Multiple strain gauges are arranged spaced apart from the connecting end portions of the multiple strain-generating portions. A load cell according to any one of claims 1 to 3.

5. In each of the Roberval mechanisms, the plurality of strain gauges are arranged offset from each other in the first horizontal direction. The load cell according to claim 1.

6. Of the plurality of strain gauges, the strain gauge on the movable part side in the first horizontal direction is positioned so as to be shifted toward the connecting part side in the second horizontal direction compared to the strain gauge on the fixed part side in the first horizontal direction. The load cell according to claim 5.

7. A combination scale comprising a load cell as described in any one of claims 1 to 6, which performs combination calculations based on the weight of the object to be weighed measured by the load cell.

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