WO2000075617A1

WO2000075617A1 - Load cell

Info

Publication number: WO2000075617A1
Application number: PCT/JP2000/003126
Authority: WO
Inventors: Kazuaki Hama; Fumiya Kobayashi
Original assignee: Kabushiki Kaisha Bridgestone
Priority date: 1999-06-03
Filing date: 2000-05-15
Publication date: 2000-12-14
Also published as: JP2000346723A

Abstract

A load cell capable of increasing a measurement accuracy and a reliability in strength by transmitting a vertical load acting on the load cell accurately to a straining body and effectively protecting the load cell against a horizontal force and a slantedly acting load without increasing the thickness of the load cell itself, a load receiving part (2) of the load cell (1) comprising a holder (2B) formed of a core part (2a) where a female screw (2M) is provided to connect it to a load table (11) and an elastic body (2b) formed so that it surrounds the core part (2a) and a load receiving part main body (2A) into which the holder (2B) is inserted.

Description

Description Load cell Technical field

The present invention relates to a structure of a load cell used for a platform weigher, a tank, a material supply hopper, a truck bed, or the like, and detects a deformation due to a load using a strain gauge. Background art

FIG. 15 (a) is a plan view showing the configuration of a platform scale 20 used for measuring the weight of a truck described in, for example, Japanese Patent Application Laid-Open No. 7-77457, and FIG. ) Is a longitudinal sectional view showing a mounting state of a laminated rubber 24 which is a load cell protection member of the platform scale 20. In the platform scale 20, the load cell 23 is fixed to the lower mounting base 21 with bolts 22, and the truck is mounted on the load receiving portion 23 A of the load cell 23 via the laminated rubber 24. For measuring the weight of the truck mounted on the upper surface of the upper frame 25. The laminated rubber 24 is formed by alternately laminating an elastic body 24 A of rubber or the like and a metal plate 24 B, and receives the mouth cell 23 through the lower flange 26. It is attached to the upper frame 25 via the upper flange 27 on the load portion 23A.

In the platform scale 20 having the above configuration, the laminated rubber 24 is interposed between the load cell 23 and the upper frame 25, and the load cell 23 does not detect a load such as a horizontal force or a tilting load. When the unnecessary force is received, the above-mentioned unnecessary force is absorbed by the laminated rubber 24 so that the load cell 23 is not directly subjected to the unnecessary force, and the measurement accuracy and durability of the load cell 23 are improved. It is intended to improve the quality. FIG. 16 is a diagram showing the configuration of a platform scale 30 described in Japanese Patent Application Publication No. Hei 8-159589, which is composed of a top surface of a load cell 23 and an upper frame. A highly rigid spherical or barrel-shaped member provided between two plate-like members 31 and 32 fixed to the lower surface of the member 25 in contact with the plate-like members 31 and 32, respectively. Or spheroidal A load cell protection member 35 comprising a vertical load supporting member 35 A having a shape and an elastic body 35 B enclosing the vertical load supporting member 35 A is provided. The load cell 23 has a horizontal force. When the vertical load supporting member 35A rolls, the unnecessary force is absorbed by the vertical load supporting member 35A, and the load cell 23 is not directly subjected to the horizontal or tilting force. It is like that.

However, in the conventional platform scales 20 and 30 described above, since the laminated rubber 24 and the vertical load supporting member 35 A constituting the load cell protection member are installed on the upper part of the load cell 23, However, there is a problem that the thickness of the load cell unit becomes large.

Further, in the platform scale 20, the strength of the laminated rubber 24, which is a protective member, is maintained by the adhesive force between the elastic body 24 A and the metal plate 24 B. There were problems such as low strength and poor reliability.

In the platform scale 30, it is necessary to produce a highly rigid spherical or barrel-shaped vertical load supporting member 35 A and enclose the vertical load supporting member 35 A having the above-mentioned shape by an elastic body 35 B. Therefore, there was a problem that the manufacturing process of the load cell protection member was complicated and the cost was high.

The present invention has been made in view of the conventional problems, and accurately transmits a vertical load acting on a load cell to a strain body without increasing the thickness of the load cell itself. An object of the present invention is to effectively protect a load cell against a force and a tilting load, and to improve measurement accuracy and strength reliability of a mouth cell. Disclosure of the invention

A mouthpiece according to the present invention includes: a load receiving portion that receives a load from a load table on which an object to be weighed is mounted; and a strain body having strain detecting means and deformed by a load applied to the load receiving portion. A joint member comprising a core having a joint with a load table and an elastic body formed so as to surround the core; And a load receiving portion main body joined thereto.

Further, in the present invention, the joint portion is constituted by a member provided with a female screw or a through hole, or a member having a male screw projecting from the core to the load table side. Further, in the present invention, a through hole is formed in the load receiving portion main body, and the joining member is inserted into the through hole.

Further, in the present invention, the outer dimensions of the joining member on the side opposite to the load table are formed larger than the external dimensions on the load table side.

In the present invention, the outer dimensions of the core portion on the side opposite to the load table are formed larger than the external dimensions of the load table side.

Further, in the present invention, a concave portion is formed in the load receiving portion main body, and the joining member is inserted into the concave portion. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a configuration of a mouth cell according to a first preferred embodiment of the present invention. FIG. 2 is a schematic diagram showing a configuration of a platform weigher according to a first preferred embodiment of the present invention. FIG. 3 is a diagram for explaining the operation of the load cell.

FIG. 4 is a diagram showing a configuration of a holder according to Best Mode 1.

FIG. 5 is a diagram showing another configuration of the holder according to the first embodiment.

FIG. 6 is a diagram showing another configuration of the holder according to the first embodiment.

FIG. 7 is a diagram showing another configuration of the holder according to the first embodiment.

FIG. 8 is a diagram showing another configuration of the holder according to the first embodiment.

FIG. 9 is a view showing another configuration of the holder according to the first embodiment.

FIG. 10 is a schematic diagram of a platform weigher according to a second preferred embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of a load cell according to the second embodiment.

FIG. 12 is a diagram showing a configuration of a load cell according to the third embodiment.

FIG. 13 is a schematic view of a platform weigher according to Best Mode 3.

FIG. 14 is a diagram showing a state of a load receiving portion when one load cell is used. FIG. 15 is a diagram showing a configuration of a conventional load cell.

FIG. 16 is a diagram showing another configuration of a conventional load cell. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best mode of the present invention will be described with reference to the drawings. Best mode 1.

FIG. 1 is a view showing a configuration of a mouthpiece 1 according to a first preferred embodiment of the present invention. FIG. 1 (a) is a plan view, and FIG. 1 (b) is a sectional view taken along line AA of FIG. 1 (a). . FIG. 2 is a schematic diagram showing a configuration of a platform scale 10 using the four load cells 1 described above. FIG. 2 (a) is a front view thereof, and FIG. It is a figure which shows the detail of a joining part. As shown in FIG. 1 and FIG. 2, the load cell 1 has a cylindrical load receiving portion 2 for receiving a load from a load table 11 on which an object to be weighed is mounted, and the outer periphery of the load receiving portion 2 A thin frame-shaped strain-generating body 3 which is formed integrally with the load-receiving part 2 and is deformed by the load applied to the load-receiving part 2; A plurality of strain gauges 4a and 4b adhered to the opposite surface), and are fixed to the mounting base 12 of the load cell 1 with the lower surface 5a, and the side walls 5b are connected to the receiving member 12 via the strain generating element 3. It is composed of a load section 2 and a peripheral frame 5 joined thereto. The strain body 3 is fixed to the peripheral frame 5 at a joint portion on an outer peripheral side thereof, and is fixed to the load receiving portion 2 at a joint portion on an inner peripheral side thereof. It has an annular plate-like structure.

Reference numeral 6 denotes a fixing screw hole for fixing the load cell 1 to the mounting base 12. Reference numeral 7 denotes a drawer provided on the side surface of the peripheral frame 5 for drawing out a measurement cable from the measurement terminal of each of the strain gauges 4a and 4b to the outside of the load cell 1. Connected to a distortion detection circuit (not shown).

In addition, the load cell 1 includes the load receiving portion 2, the strain generating body 3, and the peripheral frame 5 formed integrally, and the height of the upper surface of the load receiving portion 2 is set to It is set higher than the height of the upper surface of the frame 5 by a predetermined size, and when the load table 11 moves downward due to the load, the load table 11 and the strain element 3 and the surrounding frame 5 They do not touch.

The load-receiving part 2 has a through-hole 2 K in the center, whose inner diameter on the lower side (opposite to the load table 11) is larger than the inner diameter on the upper side (load table 11 side). A female screw 2 M is formed as a joint with the loading platform 1 1, and the columnar core 2 a and the core 2 a whose outer diameter on the lower side is larger than the outer diameter on the upper side are formed. (Hereinafter referred to as a holder) 2B having an elastic body 2b made of urethane rubber or the like formed so as to surround the holder 2B. Insert into K Formed.

Further, as shown in FIGS. 2 (a) and (b), each load cell 1 and the load table 11 are supplied with bolts 11M through the mounting holes 11p provided in the load table 11 to receive the load. It is joined by inserting 2 M female screw of part 2.

Next, the operation of the platform scale 10 having the above configuration will be described.

When the object X is mounted on the load table 11, the load of the object X acts as W _{x on the} load table 11 as shown in FIG. 3, and is distributed to each load cell, as shown in FIG. A load cell 1 acts as a force P on the load receiving portion 2 of the mouth cell 1 (the distribution ratio varies depending on the position of the object X).

When the load receiving portion 2 is displaced downward by the load, the inner periphery is fixed to the load receiving portion 2 and the ring-shaped strain generating element 3 having the outer periphery fixed to the peripheral portion 5 is deformed. The amount of strain of the flexure element 3 is detected by the strain gauges 4 a and 4 b attached to the back of the thin portion 3 a of the flexure element 3, and the load applied to the load cell 1 based on the amount of distortion is detected. Ask for. Similarly, the loads from the other load cells are obtained, and the weight of the object X can be obtained by summing the loads.

The load receiving portion 2 of the present invention is composed of a core portion 2a joined to the load base 11 and an elastic body 2b formed so as to surround the core portion 2a. 11 The vertical load P from 1 is transmitted directly to the load receiving body 2A. In addition, the horizontal load F _x generated when the object X is placed or unloaded, the horizontal load F _y generated due to thermal expansion due to the temperature change of the load table 11, and the load caused by placing the object X base 1 1 and tilting the load M _x generated by to deformation, the load F to the core 2 a of the holder 2 B, acts as a moment M, which forces arranged in 2 a peripheral core portion Since it is absorbed and buffered by the elastic body 2b, power which may adversely affect the load cell 1 is not transmitted to the load receiving portion body 2A. Thus, since the flexure element 3 is deformed only by the vertical load P, it is possible to perform an accurate load measurement, the horizontal load F _x, damage to the load cell 1 due to F _y and tilting loads M _x It can be prevented.

Further, when the load table 11 is attached to the load cell 1, even if the load table 11 is deformed, the inclination of the bolt due to the deformation can be absorbed by the elastic body 2b. As shown in FIGS. 4 (a) and (b), the load-receiving portion 2 is made substantially equal in height to the load-receiving portion main body 2A and the strain-generating body 3, and the holder 2B If the part 2a is made to protrude from the upper surface of the load receiving part body 2A by a predetermined height and the area around the protruding part of the core part 2a is surrounded by the elastic body 2c, horizontal load and tilt The load can be absorbed more reliably, and the load can be measured more accurately.

In the first best mode, the diameter of the lower part of the core 2a of the holder 2B is formed larger than the diameter of the upper part, so that when a large upward force is applied, the elastic body 2b The core 2a itself does not come off from the load receiving portion main body 2A even if broken, so that the strength reliability is also improved.

Furthermore, as shown in FIGS. 5 (a) and 5 (b), when the holder 2B and the load receiving portion main body 2A are joined from the lower portion (larger diameter side) of the holder 2B by the pins 2P, The center of the holder 2B can be reliably prevented from coming off, and the center of the bolt 11M when the bolt 11M is tightened or loosened can also be reliably prevented.

Alternatively, as shown in FIGS. 6 (a) and 6 (b), the cross-sectional shape of the through hole 2K formed in the lower part of the core 2a and the load receiving body 2A may be an ellipse, an ellipse or a rectangle. If this is the case, it is possible to more reliably prevent the holder 2B from coming off the core and around the core.

In the above example, the joint of the load receiving portion 2 with the load table 11 was constituted by the core portion 2a cut with the female screw 2M. However, as shown in FIG. It may be constituted by a core part 2 a having a male screw 2 N protruding from the core part main body embedded in the load part main body 2 A to the load table 11 side. In this case, a through hole is provided in a portion of the load table 11 corresponding to the male screw 2N, and the load table 11 and the load receiving section 2 are connected by a nut or the like. Alternatively, as shown in FIG. 7 (b), the connecting portion is constituted by a core portion 2a provided with a through hole 2Q, and for example, using a bolt and a nut, the load base 11 and the load receiving portion 2 are formed. And may be connected.

Further, as shown in FIG. 8 (a), the holder 2B has a configuration in which the holder 2B is a cylinder having a female thread cut in a length direction and the inner diameter of the load receiving portion main body 2A is constant. It goes without saying that even a simple structure having the through-hole 2R can absorb the horizontal load and the tilting load, and can accurately measure the load. Further, by adopting such a configuration of the load receiving portion 2, the entire load cell 1 is integrally formed. can do.

Also, as shown in FIGS. 8 (b) and 8 (c), the joint between the load base 11 and the male body protruding from the core main body embedded in the load receiving main body 2A to the load base 11 side. A core 2a having a screw 2N or a core 2a having a through hole 2Q may be used. Alternatively, as shown in FIGS. 9 (a) and 9 (b), the load-receiving portion 2 is formed into a cylindrical shape in which a concave portion 2S is formed in the load-receiving portion main body 2A, and a female screw is formed in the concave portion 2S. The holder 2 having the core 2a or the core 2a having a male screw 2N projecting from the core body toward the load table 11 may be inserted.

As described above, according to the present best mode 1, the load receiving portion 2 is formed so as to surround the core portion 2 a provided with the female screw 2 M for joining to the load table 1 1 and the core portion. Since it is composed of the holder 2B composed of the elastic body 2b and the load receiving section main body 2A into which the holder 2B is inserted, the vertical load P from the load table 11 is directly transmitted to the load receiving section main body 2A. Since the horizontal load F and the tilting load M are absorbed by the elastic body 2b and are not transmitted to the load cell 1, accurate load measurement can be performed, and the load cell caused by the horizontal load F and the tilting load M can be measured. 1 can prevent damage. Furthermore, since the lower outer diameter of the core 2a and the holder 2B is formed larger than the upper outer dimension, even when a large upward force is applied, the core 2a itself receives the load receiving portion. Since it does not come off from the main body 2 A, the strength reliability can be improved. In the first embodiment, the load cell having a circular planar shape has been described. However, the planar shape of the load cell is not limited to this, and may be a quadrangle or a polygon.

Best mode 2.

In the above-described best mode 1, a general platform balance 10 using four load cells has been described. However, as shown in FIGS. 10 (a) and 10 (b), a platform using two mouth cells is used. It is also possible to configure a scale of 1 OA. FIGS. 11 (a) and (b) show the configuration of a load cell 101 used for the platform scale 1 OA. The load cell 101 has a rectangular plate-shaped load receiving portion 2 and the load receiving portion 2. A frame-shaped peripheral part 5 provided around the load part 2 and four corners in the longitudinal direction of the load-receiving part 2 are provided so as to bridge between the load-receiving part 2 and the peripheral part 5. And a beam-shaped flexure element 3. Also, on The inner diameter of the lower part for inserting the holder 2B, which is a joining member with the load base 11, is placed on the strain body 3 side of the load part main body 2A of the receiving load part 2. A through hole 2 K larger than the inner diameter of the hole 2 K is provided, and the holder 2 B is inserted into the through hole 2 K. Here, for example, by using a holder as shown in FIG. 1 or FIGS. 4 to 7 as the holder 2B, it is possible to prevent a horizontal load or a tilting load from being transmitted to the load cell 101. Therefore, accurate load measurement can be performed. In FIGS. 10 (a) and (b), reference numeral 8 denotes a peripheral frame having an inclined surface for guiding the object to be weighed to the platform scale 1OA, and reference numeral 9 denotes a distortion detection circuit not shown. It is a measurement cape of distortion gauge.

Best mode 3.

In the first and second embodiments, the platform scales 10 and 10A using a plurality of load cells have been described. However, the platform scales can be configured by one load cell.

FIGS. 12 (a) and (b) show an example of a load cell 102 having a square planar shape, and FIGS. 13 (a) and (b) show a load cell 102 having the above structure. FIG. 3 is a diagram showing a configuration of a platform scale 10B.

The load cell 102 includes a rectangular plate-shaped load receiving portion 2, a frame-shaped peripheral portion 5 provided around the load receiving portion 2, and four diagonal corners of the load receiving portion 2. It is composed of a beam-shaped flexure element 3 provided so as to bridge between the part 2 and the peripheral part 5. At the four corners of the load portion main body 2 A of the load receiving portion 2, a core portion 2 a provided with a female screw 2 M for joining with the load table 11 and the core portion 2 a were formed so as to surround the core portion. The holder 2B composed of the elastic body 2b is inserted, and the load table 11 and the load cell 102 are joined via the elastic sheet 2d.

Conventionally, when one load table is fastened to one mouth cell with multiple bolts, the object to be weighed is placed on the load table, and when a load is applied, the load receiving part of the load cell and the load table The horizontal load and the tilting load applied to the mouth cell via the bolts, which could impair the accuracy of the load measurement. As shown in FIG. 14, the horizontal load F and the tilting load M can be absorbed by the holder 2B and the sheet 2d, so that the load can be measured accurately. Industrial applicability

As described above, the load cell of the present invention is configured such that a load receiving portion receiving a load from a load base is formed of a core having a joint with the load base and an elastic body formed so as to surround the core. And a load receiving portion main body to which the joining member is inserted and which is joined to the strain-generating body so that a horizontal load or a tilting load is absorbed by the elastic body and is not transmitted to the mouth cell. As a result, accurate load measurement can be performed, and damage to the load cell due to the horizontal load and the tilting load can be prevented.

In addition, since the above-mentioned joint portion is formed of a member having a female screw or a through hole or a member having a male screw projecting from the core to the load table side, it is possible to connect the load cell to the load table with a simple configuration. it can.

In addition, a through-hole is formed in the load-receiving part body, and the joining member is inserted into this through-hole, so that horizontal load and tilting load can be absorbed with a simple structure, and the entire mouth cell is integrally formed. can do.

Further, since the outer dimension of the joining member on the side opposite to the load table is formed larger than the outer dimension of the load table, the joining member can be prevented from coming off from the load receiving portion main body.

In addition, since the outer dimensions of the above-mentioned core part on the side opposite to the load table are made larger than the external dimensions of the load table side, even when a large upward force is applied, the core part itself will be separated from the load receiving part body. Since there is no escape, strength reliability can be improved. Further, since the concave portion is formed in the load receiving portion main body and the joining member is inserted into the concave portion, the load receiving portion can be easily formed.

Claims

The scope of the claims

A load receiving portion that receives a load from a load table on which the object to be weighed is mounted; a strain generating body that includes a strain detecting means and is deformed by a load applied to the load receiving portion; and the load receiving portion and the strain generating body In the load cell including the peripheral frame joined through the interposition, the load receiving portion is formed by a core having a joint with the load base and an elastic body formed so as to surround the core. A load cell comprising: a joining member having the above structure; and a load receiving portion main body having the joining member inserted therein and joined to the strain generating body.

2. The load cell according to claim 1, wherein the joint is formed by a member having a female screw or a through hole, or a member having a male screw protruding from the core toward the load table.

2. The mouthpiece according to claim 1, wherein a through hole is formed in the load receiving portion main body, and the joining member is inserted into the through hole.

2. The load cell according to claim 1, wherein an outer dimension of the joining member on a side opposite to the load table is larger than an outer dimension of the load table on the load table side.

2. The load cell according to claim 1, wherein an outer dimension of the core portion on the side opposite to the load table is larger than an outer dimension of the load table side.

2. The load cell according to claim 1, wherein a concave portion is formed in the load receiving portion main body, and the joining member is inserted into the concave portion.