JP2013217815A - Load cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pin type load cell capable of reducing influence exerted to support parts on both sides or load parts on both sides by curvature of a shaft-like elastic body by a load, and improving measurement accuracy.SOLUTION: For the load cell, a load part 1a is provided on the center in an axial direction of a shaft-like elastic body 1, support parts 1b and 1c are provided on both sides, strain parts 1d and 1e are provided between the load part 1a and the support parts 1b and 1c, recessed parts 1h are recessed in a shaft perpendicular direction facing each other to the respective strain parts 1d and 1e to configure a thin part 1i between bottom surfaces of the recessed parts 1h facing each other, a strain gauge is attached to the center of the bottom surface of the recessed part 1h, and the respective strain gauges are connected so as to configure a Wheatstone bridge circuit. The shaft-like elastic body 1 is arranged so as to be a posture that the thin part 1i is erected, and a slit S that penetrates in the shaft perpendicular direction in the plane view, passes through the lower part of the recessed part 1h, and extends in an axial direction, is provided between the support parts 1b and 1c on both sides.

Description

  The present invention relates to a pin type load cell used for vehicles such as garbage trucks, cranes and the like.

  2. Description of the Related Art Conventionally, a load cell is incorporated in a vehicle such as a garbage collection vehicle, a water supply / watering vehicle, or a tank lorry equipped with a cargo box in order to measure the weight of the contents accommodated in the cargo box or the tank. A pin-type load cell may be used for such a vehicle or a crane (for example, refer to Patent Documents 1 and 2).

  FIG. 5 is a front view showing an example of a conventional pin type load cell. In this conventional load cell, a first force application unit 1a serving as a load load portion (or support portion) is provided in the center of the axial elastic body 40 in the axial direction, and support portions (or load load portions) are provided on both sides in the axial direction. The second force application units 1b and 1c are provided, and the strain generating units 1d and 1e are provided between the first force application unit 1a and the second force application units 1b and 1c on both sides. . The strain generating portions 1d and 1e are respectively provided with concave portions 1h on both sides of the front surface (front surface) and the back surface, and a strain gauge for detecting shear strain is bonded to each concave portion 1h. Connected to form a Wheatstone bridge circuit. A connecting hole 3 is provided in the axial elastic body 40 in the axial direction. A lead wire of a strain gauge is inserted into the connecting hole 3 and is drawn out from one end (right end) of the axial elastic body 40.

JP 2007-139511 A Japanese Patent Laid-Open No. 10-038713

  The conventional load cell is attached so that the first and second force applying portions 1a, 1b, and 1c are supported by the bearing portions 11 and 12 (see FIG. 1). For example, as indicated by arrows 41 to 43 in the direction in which an external force acts, a load is applied to the first first force application unit (load load unit) 1a from above, and second force application units (support units) on both sides. ) When 1b and 1c are attached to be supported, stress in the compression direction is generated in the upper portion of the shaft-like elastic body 40 as indicated by arrows 44 and 45, and in the lower portion of the shaft-like elastic body 40, As indicated by arrows 46 and 47, stress in the tensile direction is generated. As a result, the shaft-like elastic body 40 is bent and, for example, the position of the fulcrum that supports the lower portions of the second force application units 1b and 1c on both sides fluctuates, which adversely affects the measurement accuracy (measurement error occurs). ) Problem. Here, when the shaft-like elastic body 40 is curved, the lower end portion thereof is curved as indicated by a two-dot chain line L3, for example.

  Conventionally, the first and second force application units 1a, 1b, and 1c are used in order to reduce fluctuations in the position of the fulcrum of the second force application units 1b and 1c on both sides due to the bending of the shaft-like elastic body 40. The first and second force application units 1a, 1b, and 1c may be formed into a barrel shape so that the width of the first and second force application units 1a, 1b, and 1c is in point contact with the bearing units 11 and 12.

  Even in such a case, when the shaft-like elastic body 40 is curved, the lower end thereof is curved as indicated by a two-dot chain line L3, and the positions P7 and P8 at both ends of the lower end of the curved portion are the second force. There is no change in being very close to the fulcrum positions P1 and P2 supporting the lower portions of the application units 1b and 1c. For this reason, the position of the fulcrum of the second force application units 1b and 1c on both sides is likely to change due to the influence of the curvature of the shaft-like elastic body 40, and the measurement accuracy is not greatly improved.

  Further, as indicated by broken line arrows 51 to 53, the direction in which the external force acts is, for example, the second force application units 1b and 1c on both sides are load-loading units to which a load is applied, and the central first force application unit The same problem arises when the load cell is attached so that 1a is the support.

  The present invention has been made to solve the above-described problems, and reduces the influence of the bending of the shaft-like elastic body caused by the load on the support portions on both sides or the load load portions on both sides, thereby improving the measurement accuracy. An object of the present invention is to provide a pin type load cell that can be realized.

  In order to achieve the above object, a load cell according to an aspect of the present invention includes a load-loading portion at the center in the axial direction of the shaft-like elastic body, and also includes support portions on both sides, Between the bottom surfaces of the concavities facing each other, by forming concavities that are perpendicular to the axis in the direction perpendicular to the axis. The load cell is configured such that a thin portion is formed at the center along the axis of the shaft-like elastic body, a strain gauge is attached to the center of the bottom surface of the recess, and the strain gauges are connected to form a Wheatstone bridge circuit. The shaft-like elastic body is arranged so that the thin-walled portion is in an upright posture, a load is applied from above to the central load-loading portion, and the support portions on both sides are supported from below. When both sides Lower end position of the two ends of the curved portion that occurs during the serial support portion is configured so as to be position above the lower end position of the strain generating part.

  According to this configuration, when a load is applied from above to the central load-loading portion of the shaft-like elastic body and the support portions on both sides are supported from below, the shaft-like elastic body is set so that the central load-loading portion sinks downward. However, the lower end position of both ends of the curved portion generated between the support portions on both sides is configured to be a position above the lower end position of the strain-generating portion. The influence of the curvature of the shaft-like elastic body on the support portions on both sides can be reduced, the fluctuation of the position of the fulcrum supporting the lower portions of the support portions on both sides can be suppressed, and the measurement accuracy can be improved.

  The shaft-like elastic body is disposed so that the thin-walled portion is in an upright posture, and a curved portion is generated between the support portions on both sides when a load is applied to the load load portion from above. In order for the lower end positions of both ends of the shaft to be higher than the lower end position of the strain-generating portion, the shaft-like elastic body is disposed so that the thin-walled portion is in an upright posture, Between the support portions, there may be provided a slit that extends in a direction perpendicular to the axis in plan view and extends below the recess and extends in the axial direction.

  By providing such a slit, it is possible to prevent the transmission of stress to the part outside (below) the slit, so the influence of the curvature of the shaft-like elastic body on the support parts on both sides is reduced, and the support on both sides is supported. The variation in the position of the fulcrum that supports the lower part of each part can be suppressed, and the measurement accuracy can be improved.

  A load cell according to another aspect of the present invention includes a support portion at the center of the axial direction of the shaft-like elastic body and load load portions on both sides, and the load cell is provided between the support portion and each load load portion. A strain generating portion for generating a shear strain is provided, and a concave portion in a direction perpendicular to the axis is provided to face each of the strain generating portions so as to be opposed to each other. A load cell connected to form a Wheatstone bridge circuit, wherein a strain gauge is attached to the center of the bottom surface of the recess, and each of the strain gauges is connected to form a Wheatstone bridge circuit. The body is arranged so that the thin-walled portion is in an upright posture, the load is applied to the load-loading portions on both sides from above, and the load on both sides is supported when the central support portion is supported from below. Bay generated between load parts The upper end position of the ends of the portions is configured so as to be positioned lower than the upper end position of the strain generating part.

  According to this configuration, when the load is applied to the load-loading portions on both sides of the shaft-like elastic body from above, and the center support portion is supported from below, the shaft-like elastic body is set so that the load-loading portions on both sides sink downward. However, the shaft-like elastic body is configured so that the upper end positions of both ends of the curved portion generated between the load-loading portions on both sides are lower than the upper end position of the strain-generating portion. , To reduce the influence of the bending of the shaft-like elastic body on the load-bearing parts on both sides, to suppress the fluctuation of the position of the load point where the load on each of the load-loading parts on both sides is loaded, and to improve the measurement accuracy be able to.

  Further, when the shaft-like elastic body is arranged so that the thin-walled portion is in an upright posture, a load is applied to the load-loading portions on both sides from above and the central support portion is supported from below. In addition, in order to make the upper end positions of both ends of the curved portion generated between the load-loading portions on both sides be lower than the upper end position of the strain-generating portion, the shaft-like elastic body has the thin wall A slit is provided between the load-loading portions on both sides so as to penetrate in a direction perpendicular to the axis in a plan view and extend in the axial direction through the upper portion of the recess. It may be.

  By providing such a slit, it is possible to prevent the transmission of stress to the outside (upper) part from the slit, so the influence of the curvature of the shaft-like elastic body on the load-bearing parts on both sides is reduced. The measurement accuracy can be improved by suppressing fluctuations in the position of the load point where the load on each upper portion of the load application portion is applied.

  Further, the shaft-like elastic body is cut into a plate shape in which all the portions outside the slit on the opposite side of the concave portion across the slit have a boundary surface with the slit as one surface. May be.

  According to this configuration, the portion outside the slit on the side opposite to the load loading portion or the support portion provided in the center in the axial direction of the shaft-like elastic body is formed into a plate shape by cutting. Interference (contact) with the supporting member (bearing portion) that supports the load loading portion or the supporting portion can be eliminated, and the measurement accuracy can be further improved.

  The present invention has the configuration described above, and in a pin type load cell, the influence of the bending of the shaft-like elastic body due to the load load on the support portions on both sides or the load load portions on both sides is reduced, and the measurement accuracy is improved. There is an effect that can be achieved.

(A) is the figure which looked at the load cell of an example in the embodiment of the present invention from the front, (b) is an AA arrow sectional view of the load cell in Drawing 1 (a), (c) These are BB arrow sectional drawing of the load cell in Fig.1 (a). It is a figure which shows an example of the connection diagram of the strain gauge of the load cell of embodiment of this invention. (A) is a side view which shows an example of the vehicle in which the load cell of embodiment of this invention was used, (b) is a perspective view which shows the attachment part of a load cell. It is the figure which looked at the load cell of the other example in embodiment of this invention from the front. It is a front view which shows an example of the conventional pin type load cell.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference symbols throughout all the drawings, and redundant description thereof is omitted. Further, the present invention is not limited to the following embodiment.

(Embodiment)
Fig.1 (a) is the figure which looked at the load cell of the example in embodiment of this invention from the front, FIG.1 (b) is AA arrow sectional drawing of the load cell in Fig.1 (a). FIG.1 (c) is BB arrow sectional drawing of the load cell in Fig.1 (a).

  The load cell of this embodiment is a pin type load cell, and eight strain gauges G1 to G4 and G10 to G40 constituting a Wheatstone bridge circuit are bonded to the shaft-like elastic body 1.

  The shaft-like elastic body 1 is formed by processing a columnar elastic body, and a first force application portion 1a serving as a load load portion (or support portion) is provided at the center of the shaft-like elastic body 1 in the axial direction. The second force application units 1b and 1c are provided on both sides in the axial direction and serve as support units (or load-loading units). The first force application unit 1a and one second force application unit 1b Between the first force applying unit 1a and the other second force applying unit 1c, strain generating portions 1d and 1e that generate shear strain are provided.

  The bearing portions 11 and 12 are examples of members used for mounting the load cell, and the through hole 11a of the bearing portion 11 and the through holes 12a of the two bearing portions 12 on both sides are circular in cross section and have the same diameter. It is formed as follows. The diameters of the through holes 11a and 12a are formed slightly larger (for example, about 10 to 20 μm) than the outer diameters of the first and second force applying portions 1a, 1b, and 1c of the load cell so that the load cell can be mounted. .

  In this example, the first force application unit 1 a is supported by the bearing unit 11, and the second force application units 1 b and 1 c on both sides are supported by the bearing unit 12. In this case, the first force application unit 1a becomes a load loading unit in which a load is applied from above via the bearing unit 11, and the second force application units 1b and 1c are supported by the bearing unit 12 from below. It is attached to become. Hereinafter, in the case of being attached as in this example, the first force application unit 1a will be described as a load application unit 1a, and the second force application units 1b and 1c will be described as support units 1b and 1c. .

  As shown in FIG. 1C, the portions where the elastic portions 1d and 1e of the shaft-like elastic body 1 are formed are formed so that their diameters are slightly smaller than the diameters of the columnar support portions 1b and 1c. The upper part 1p and the lower part 1q, the front part 1r and the rear part 1s are scraped off and formed into a flat shape. Further, in the strain generating portions 1d and 1e, concave portions 1h in a direction perpendicular to the axis are formed on both sides of the front surface (front surface) and the back surface so as to face each other with the axis (center axis) 1x of the shaft-like elastic body 1 therebetween. Thus, a plate-like (disc-like in this example) thin-walled portion 1i is formed between the bottom surfaces 1hb of the opposing concave portions 1h and along the axis 1x of the shaft-like elastic body 1.

  Then, two strain gauges for detecting shear strain are bonded to approximately the center of the bottom surface 1hb of each recess 1h. Here, two strain gauges G1 and G2 are attached to the concave portion 1h on the front surface side of the strain generating portion 1d, and two strain gauges G10 and G20 are attached to the concave portion 1h on the rear surface side, so that the front side of the strain generating portion 1e. Two strain gauges G3 and G4 are attached to the concave portion 1h, and two strain gauges G30 and G40 are attached to the concave portion 1h on the back surface side. That is, a total of eight strain gauges are attached, and these strain gauges are connected to form a Wheatstone bridge circuit. FIG. 2 shows an example of a Wheatstone bridge circuit. The resistor R provided at the output portion of the Wheatstone bridge circuit is a variable resistor for adjusting a change in resistance of the strain gauge due to a difference in mounting angle or fixing method. The output signal of the Wheatstone bridge circuit of FIG. 2 is an output signal of the load cell, that is, a signal indicating a measured value of a load applied.

  Further, the lower portion of the load-loading portion 1a of the shaft-like elastic body 1 is formed into a flat shape by cutting off the lower portion 1t as shown in FIG.

  The load-loading portion 1a between the support portions 1b and 1c on both sides of the shaft-like elastic body 1 and the lower portions of the strain-generating portions 1d and 1e are perpendicular to the axis in plan view (in the direction perpendicular to the axis 1x in plan view). There is a slit S that penetrates in the direction indicated by the arrow 13) and passes below the concave portions 1 h of the strain-generating portions 1 d, 1 e and extends in the axial direction apart from the concave portions 1 h. Thereby, the lower part of the slit S of the shaft-like elastic body 1 is a thin plate-like portion 1j, 1k. The upper surface of the plate-like portion 1j below the load applying portion 1a and the upper surface of the plate-like portion 1k below the concave portions 1h of the strain-generating portions 1d and 1e continuously form the lower surface of the slit S. In order to provide such a slit S in the lower part, the recess 1h having a circular cross section is provided so that the center thereof is slightly above the axis 1x of the shaft-like elastic body 1. Further, here, both side surfaces 1js of the plate-like portion 1j below the load-loading portion 1a are slightly cut to form a flat shape, and the axis 1x of the plate-like portion 1j is formed as shown in FIG. The cross section in the direction orthogonal to is trapezoidal.

  Further, the thin-walled portion 1i of the strain-generating portions 1d and 1e is provided with a through hole 2, and a lead wire of a strain gauge attached to the concave portion 1h on the back side is inserted and pulled out to the front side. Further, a connecting hole 3 is provided in the shaft-like elastic body 1 in parallel with the axis 1x, and a strain gauge lead wire is inserted into the connecting hole 3, and a signal is output from one end (right end) of the shaft-like elastic body 1. It is pulled out as a cable (not shown). A lid 6 is attached to each recess 1h by welding.

  In this load cell, the axial direction of the shaft-like elastic body 1 is horizontal or substantially horizontal, the strained portions 1d and 1e of the shaft-like elastic body 1 are in an upright posture, and the slit S is below the recess 1h. It is inserted and attached to the through holes 11a and 12a of the bearing portions 11 and 12 so as to be. At this time, the shaft-like elastic body 1 is inserted in a state where the centers of the through holes 11a and 12a of the bearing portions 11 and 12 are matched.

  Then, a retaining portion 1g protrudes from the tip of one support portion 1b of the shaft-like elastic body 1, and a concave portion 4 to which a flat locking piece 5 is engaged is formed on the side surface of the retaining portion 1g. Is formed. The locking piece 5 is fixed to the bearing portion 12 with, for example, a bolt (not shown) while being locked to the recess 4. Thus, the shaft-like elastic body 1 is prevented from rotating or misaligned by passing through the shaft-like elastic body 1 through the bearing portions 11 and 12 and attaching the locking pieces 5.

  A metal fitting 1f protrudes from the tip of the other support portion 1c of the shaft-like elastic body 1, and a signal output cable for outputting an output signal of the load cell is embedded at the tip of the metal fitting 1f. A drawer fitting (not shown) is attached.

  In the present embodiment, when a load (vertical downward load) is applied to the upper portion of the load load portion 1a via the bearing portion 11, the support portions 1b and 1c on both sides are supported from below by the bearing portion 12, and the load load The shaft-like elastic body 1 tends to bend so that the portion 1a sinks downward, but by providing the slit S, transmission of stress to the plate-like portions 1j and 1k outside (downward) from the slit S is prevented. Therefore, the positions P3 and P4 at both ends of the lower end of the curved portion of the shaft-like elastic body 1 are positioned higher than the lower ends of the strain generating portions 1d and 1e, and the positions P3 and P4 at both ends are connected by a straight line. For example, the portion tends to be curved as indicated by a two-dot chain line L1. Thus, the positions P3 and P4 at both ends of the lower end of the curved portion are positions far away from the fulcrum positions P1 and P2 that support the lower portions of the support portions 1b and 1c on both sides. Therefore, the influence of the bending of the shaft-like elastic body 1 on the support portions 1b and 1c on both sides can be reduced, and the fluctuation of the position of the fulcrum that supports the lower portions of the support portions 1b and 1c on both sides can be suppressed and measured. The accuracy can be improved. Further, in this case, the plate-like portions 1j and 1k outside (downward) from the slit S act as a beam, and it is more effective to suppress fluctuations in the position of the fulcrum of the support portions 1b and 1c on both sides. .

  Further, the shaft-like elastic body 1 is cut from the outer side (lower side) of the slit S from the outer side (lower side) of the slit S on the opposite side of the concave portion 1h across the slit S, and By forming the slit S, the thin plate-like portions 1j and 1k having a boundary surface with the slit S (a surface in contact with the slit S) as one surface are formed. In particular, the opposite side of the load portion 1a across the slit S is a thin plate-like portion 1j, so that interference (contact) between the plate-like portion 1j outside the slit S and the bearing portion 11 is eliminated, and measurement is performed. The accuracy can be further improved.

  Moreover, in this embodiment, although the load cell is attached so that the thin part 1i may stand in the same direction as the vertical direction, the thin part 1i is slightly inclined (about 7 to 8 degrees) from the vertical direction. Even so, it was confirmed by experiments that the measurement accuracy could be improved.

  Conventionally, for example, in the configuration of FIG. 5, the first and second force application units are configured so that the first and second force application units 1 a, 1 b, and 1 c and the bearing units 11 and 12 are in point contact. 1a, 1b, 1c may be formed into a barrel shape. In this case, the bearings 11, 12 and the like are significantly deteriorated due to use and aging, and as a result, the service life of the apparatus using the load cell is shortened. . On the other hand, as in the load cell of the present embodiment, the first force application unit 1a has a substantially cylindrical shape, the second force application units 1b and 1c have a cylindrical shape, and the first and second force application units 1a and 1b. By making the outer shape of 1c into a surface along the cylinder, that is, a surface along the through holes 11a and 12a of the bearing portions 11 and 12, the service life of the apparatus using the load cell can be improved.

  Next, a usage example of the load cell of the present embodiment will be described with reference to FIG. FIG. 3A is a side view showing an example of a vehicle in which the load cell of the present embodiment is used, and FIG. 3B is a perspective view showing an attachment portion of the load cell.

  The vehicle 20 includes left and right chassis frames 22 that extend from the cabin 21 in the front-rear direction, and a tank 23 is mounted on each chassis frame 22 via two load cells LC (load cells of the present embodiment). The output signals of the total four load cells LC are added by a control unit (not shown) to obtain the total load.

  Each load cell LC is attached as shown in FIG. 3B, for example. Here, a pair of bearing portions 12 are erected on an attachment plate 24 fixed to the chassis frame 22, and the support portions 1 b and 1 c of the load cell LC are supported by the pair of bearing portions 12. Further, the upper end surface of the center bearing portion 11 is fixed to the bottom surface of the bottom wall of the tank 23, and the load of the tank 23 is applied to the load loading portion 1 a via the bearing portion 11.

  In addition, when the load cell LC is disposed and used so that the slit S is below the concave portion 1h as in the above usage example, the first first force application unit 1a serves as a load loading unit, The second force application portions 1b and 1c on both sides serve as support portions, but the load cell LC can be disposed and used so that it is upside down. In this case, the load cell LC is disposed so that the slit S is above the concave portion 1h, the second force applying portions 1b and 1c on both sides serve as load loading portions, and the central first force applying portion 1a is the support portion. It becomes. For example, when the upper end surfaces of the pair of bearing portions 12 are fixed to the lower surface of the bottom wall of the tank 23 and the central bearing portion 11 is erected on the mounting plate 24, the load cell LC is different from the case of FIG. It is mounted in a state where it is turned upside down and penetrates into the bearing portions 11 and 12.

  In this case, when a load is applied from above (bearing portion 12) to the second force application portions (load load portions) 1b and 1c on both sides, the central first force application portion (support portion) 1a is moved from below. The shaft-like elastic body 1 is supported by the bearing portion 11 so that the second force application portions 1b and 1c on both sides sink downward, but by providing the slit S, the outer side of the slit S (upward) ) Can be prevented from being transmitted to the plate-like portions 1j and 1k, so that the influence of the curvature of the shaft-like elastic body 1 on the second force application portions 1b and 1c on both sides is the same as in the case of FIG. The measurement accuracy can be improved by suppressing fluctuations in the position of the load point where the load on the upper part of the second force application units 1b, 1c on both sides is applied.

  In the same manner as described above, the load cell LC of the present embodiment can also be applied to a vehicle such as a garbage collection vehicle equipped with a cargo box (corresponding to the tank 23) that accommodates garbage. Note that the mounting structure of the load cell LC is not limited to the above example, and can be changed as appropriate.

  Moreover, you may apply the load cell of this embodiment also to a crane other than the above vehicles.

  Next, another example of the load cell of this embodiment is shown in FIG. FIG. 4 is a view of another example load cell according to the present embodiment as viewed from the front.

  The load cell shown in FIG. 4 has a configuration in which cut portions C1 and C2 are provided on the left and right instead of the slit S of the load cell shown in FIG. The left cut portion C1 is formed by cutting a predetermined portion from the bottom to the top in the vicinity of the left support portion 1b in the left strain generating portion 1d. The right cut portion C2 is formed by cutting a predetermined portion from the bottom to the top in the vicinity of the right support portion 1c in the right strain portion 1e. Other configurations are the same as those of the load cell shown in FIG. This load cell can also be applied to the aforementioned vehicles and cranes.

  In place of the slit S, even when such cut portions C1 and C2 are provided, when the load is applied to the upper portion of the load load portion 1a and the shaft-like elastic body 1 is about to bend, the shaft-like elastic body Positions P5 and P6 at both ends of the lower end of the curved portion 1 are positions above the lower ends of the strain generating portions 1d and 1e, and a portion connecting the positions P5 and P6 at both ends with a straight line is indicated by, for example, a two-dot chain line L2. To try to bend. In this way, the positions P5 and P6 at both ends of the lower end of the curved portion are positions far away from the fulcrum positions P1 and P2 that support the lower portions of the support portions 1b and 1c on both sides. Therefore, the influence of the bending of the shaft-like elastic body 1 on the support portions 1b and 1c on both sides can be reduced, and the fluctuation of the position of the fulcrum that supports the lower portions of the support portions 1b and 1c on both sides can be suppressed and measured. The accuracy can be improved.

  This load cell can also be used by being arranged upside down. In this case, the cut portions C1 and C2 are arranged at the top, and the second force application units 1b and 1c on both sides are provided. It becomes a load loading part, and the first first force applying part 1a becomes a support part.

  As described above, the load cell of this embodiment illustrated in FIGS. 1 and 4 is arranged so that the thin portion 1i is in an upright posture, and a load is applied to the central load load portion 1a from above. When the support portions 1b and 1c on both sides are supported from below, the lower end positions (P3, P4 or P5 and P6) of both ends of the curved portion (flexible portion) generated between the support portions 1b and 1c on both sides are The strain generating portions 1d and 1e are configured to be positioned above the position of the lower end (lowermost end) of the strain generating portions 1d and 1e. In other words, the bending (deflection) generated between the support portions 1b and 1c on both sides does not occur at the lower ends (lowermost ends) of the strain generating portions 1d and 1e and the vicinity thereof, but the lower ends of the strain generating portions 1d and 1e ( It is configured to occur at a portion away from the lowermost end. An example for this is a configuration in which the shaft-like elastic body 1 is processed and the slits S or the cut portions C1 and C2 are provided, and is not limited thereto.

  In addition, the load cell of the present embodiment in the case of being disposed upside down from FIGS. 1 and 4 is disposed so that the thin portion 1i is in an upright posture, and the load loading portions ( 1b and 1c) are loaded from above and both ends of the curved portion (flexible portion) formed between the load loading portions (1b and 1c) on both sides when the central support portion (1a) is supported from below. Is configured such that the upper end position is lower than the upper end (uppermost end) position of the strain generating portions 1d and 1e. In other words, the bending (bending) that occurs between the load-loading portions (1b, 1c) on both sides does not occur at the upper ends (uppermost ends) of the strain-generating portions 1d, 1e and in the vicinity thereof, but the strain-generating portions 1d, 1e. It is comprised so that it may arise in the part away from the upper end (uppermost end). An example for this is a configuration in which the shaft-like elastic body 1 is processed and the slits S or the cut portions C1 and C2 are provided, and is not limited thereto.

  INDUSTRIAL APPLICABILITY The present invention is useful as a pin-type load cell or the like that can reduce the influence of the bending of a shaft-like elastic body caused by a load on the support portions on both sides or the load load portions on both sides and can improve measurement accuracy.

DESCRIPTION OF SYMBOLS 1 Shaft-shaped elastic body 1a 1st force application part (load load part or support part)
1b, 1c 2nd force application part (support part or load application part)
1d, 1e Straining part 1h Recessed part 1i Thin part 1j, 1k Plate-like part 1x Axis G1-G4, G10-G40 Strain gauge S Slit

Claims (5)

A load-bearing portion is provided at the center in the axial direction of the shaft-like elastic body, and support portions are provided on both sides, and a strain-generating portion that generates a shear strain between the load-load portion and each of the support portions is provided. By forming a concave portion in the direction perpendicular to the axis opposite to the strain-generating portion, a thin portion is formed between the bottom surfaces of the opposed concave portions and in the central portion along the axis of the axial elastic body, A load cell is attached to the center of the bottom surface of the recess, and each of the strain gauges is connected to form a Wheatstone bridge circuit,
The shaft-like elastic body is arranged so that the thin-walled portion is in an upright posture, a load is applied to the load-loading portion at the center from above, and the support portions on both sides are supported from below. A load cell configured such that lower end positions of both ends of a curved portion generated between the support portions on both sides are positioned higher than a lower end position of the strain generating portion. Both ends of the curved portion generated between the support portions on both sides when the shaft-like elastic body is arranged so that the thin-walled portion is in an upright posture and a load is applied to the load load portion from above. In order for the lower end position of the to be a position above the lower end position of the strain generating portion,
The shaft-like elastic body is disposed so that the thin-walled portion is in an upright posture, passes between the support portions on both sides in a direction perpendicular to the axis in a plan view, and passes below the recess. The load cell according to claim 1, wherein a slit extending in the axial direction is provided. A support is provided in the center of the axial direction of the shaft-like elastic body, and load-loading portions are provided on both sides, and a strain-inducing portion that generates a shear strain between the support portion and each of the load-loading portions is provided. By forming a concave portion in the direction perpendicular to the axis opposite to the strain-generating portion, a thin portion is formed between the bottom surfaces of the opposed concave portions and in the central portion along the axis of the axial elastic body, A load cell is attached to the center of the bottom surface of the recess, and each of the strain gauges is connected to form a Wheatstone bridge circuit,
The shaft-like elastic body is disposed so that the thin-walled portion is in an upright posture, a load is applied to the load-loading portions on both sides from above, and the support portion in the center is supported from below. A load cell configured such that upper end positions at both ends of a curved portion generated between the load-loading portions on both sides are positioned lower than an upper end position of the strain-generating portion. When the shaft-like elastic body is disposed so that the thin-walled portion is in an upright posture, a load is applied to the load-loading portions on both sides from above, and the central support portion is supported from below, In order for the upper end positions of both ends of the curved portion generated between the load-loading parts on both sides to be lower than the upper end position of the strain-generating part,
The shaft-like elastic body is arranged so that the thin-walled portion is in an upright posture, passes between the load-loading portions on both sides in a direction perpendicular to the axis in plan view, and passes above the recess. The load cell according to claim 3, further comprising a slit extending in the axial direction.   In the shaft-like elastic body, all portions of the region outside the slit that is opposite to the concave portion across the slit are cut into a plate shape having a boundary surface with the slit as one surface. The load cell according to claim 2 or 4.

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