JP3211213B2 - Beam type load cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam type load cell.

[0002]

2. Description of the Related Art A beam-type load cell is used, for example, as a load detecting element of an electronic balance, and has a pair of upper and lower beams arranged in parallel and connected to both ends of the upper and lower beams. A well-known structure having a fixed and a movable column and a strain-generating body constituting a parallelogram-shaped robarbal mechanism, and a strain gauge disposed in a thin portion of the strain-generating body is well known.

[0003] The thin portion is formed by forming a pair of eyeglass-shaped through-holes in the strain body, and a total of four thin portions are arranged at predetermined intervals in the upper and lower beams. Usually, the strain gauges are respectively attached to the upper and lower beams on the back side of the thin portion, and are connected so as to form four resistance elements of the bridge circuit, thereby constituting a load detecting unit.

[0004] In the beam type load cell thus configured, when a load is applied to the movable column portion of the flexure element,
The magnitude of the applied load is measured by detecting an electric signal corresponding to the amount of deformation of the Roberval mechanism by the load detection unit.

The measurement range of this type of beam load cell is determined by the thickness of the thin portion and the characteristics of the strain gauge to be used, and the like. There was no other way but to replace it.

[0006] Thus, for example, Japanese Akira 62 -32 324
Japanese Patent Application Laid-Open No. 63-201543 and JP-A-63-201543 propose a beam-type load cell having a plurality of measurement ranges.

[0007] The former publication discloses two types for low weighing and high weighing.
A multi-range beam-type load cell is disclosed in which a plurality of independent flexure elements are arranged vertically or horizontally and connected to each other.

In the latter publication, one flexure element is
A multi-range beam load cell is disclosed in which two independent eyeglass-shaped through holes are provided and the thickness of the thin portion is made different.

However, the conventional beam type load cell having such a configuration has the following technical problems.

[0010]

That is, in the beam type load cell disclosed in the former publication, two independent strain bodies are vertically connected or arranged to be connected in the left-right direction, so that the whole becomes large. Also, in the beam type load cell disclosed in the latter publication,
Since two independent eyeglass-shaped through-holes are provided, there is a problem that the whole becomes large.

In this type of load cell, the through holes of the strain body are generally formed by machining, but the through holes disclosed in the latter publication are independent of each other. , It could not be processed all at once, and the processing was troublesome.

The present invention has been made in view of such a conventional problem, and an object of the present invention is to make it possible to expand the measurement range while avoiding an increase in the overall size.
Another object of the present invention is to provide a beam-type load cell in which the use of the load cell is not interrupted when a failure occurs.

Another object of the present invention is to provide a beam type load cell which can easily machine a through hole.

Further, the present invention provides a beam type load cell which can achieve a reduction in size and weight by integrating a conventional independent roberval mechanism into a single roberval mechanism and incorporating a load detecting section comprising a plurality of bridge circuits. To provide.

[0015]

In order to achieve the above object, the present invention provides a pair of upper and lower beams arranged in parallel, and a fixed and movable beam connected to both ends of the upper and lower beams. A flexure element comprising a column and a roberval mechanism provided with one continuous through hole vertically and horizontally symmetrically;
Disposed thin portion of the strain body, a beam-type load cell having a load detection section composed of a plurality of strain gauges which are connected to the bridge circuit, the through hole is cross-one
Consists of multiple circular through holes of the same diameter where the parts overlap each other
And the thin part has four upper and lower beams, respectively.
Are provided, and the four inner members centered on the center of the strain body
A first load detecting unit is configured and the first load
The second 4 load detectors are composed of the remaining 4 units located outside the unit
The thickness of the thin portion of the first load detector is the circle
By displacing the through hole vertically, the second load
The thickness of the thin portion of the detecting section is different from that of the thin section . According to the beam-type load cell configured as described above, the plurality of first and second load detectors are provided on the flexure element.
If one fails, the other can be used to continue the measurement. Further, in the beam-type load cell having the above configuration, the thickness of the thin portion of the first load detecting unit is set to be larger than that of the circular through hole.
By deviating downward, the thin portion of the second load detector
Because the thickness is different from the thickness , the measurement range can be expanded.
In this case, it is only necessary to provide a continuous through hole in the strain body that is symmetrical in the left and right and up and down directions.
Enlargement of both directions can be avoided. Furthermore, in the beam-type load cell having the above-described configuration, the through-hole of the strain body is formed of one continuous body which is symmetrical in the left-right direction and the up-down direction , so that the machining is simplified. Also, according to the present invention,
The chromatography beam load cell, the thin portion is on, provided four each lower beam, as well as constituting a first loading heavy detector with four inner about a central strain member, the first
Since the second four load detection units are located outside the load detection unit, the influence between the first and second load detection units can be reduced when the four corners are adjusted.

[0016]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 to 4 show a beam-type load cell according to a first embodiment of the present invention.

The beam-type load cell shown in FIG. 1 has a flexure element 10 and a plurality of load detectors 12. The flexure element 10 constitutes a Roberval mechanism, and is made of a narrow and rectangular metal block.

By forming one continuous through-hole 14 in the thickness direction of the strain body 10, a pair of upper beam 16 and lower beam 18 arranged in parallel in the vertical direction is formed.
And a fixed column 20 and a movable column 22 that connect both ends of the upper and lower beams 16 and 18.

The through-hole 14, extend through between both opposite sides of it is wide, have a circular diameter through hole 14 _{1-14 8} eight same diameter of a portion mutually overlap, The central axis L1 in the longitudinal direction and the central axis L in the lateral direction of the flexure element 10
2 are symmetrical with respect to each other, and the flexure element 1
0 is formed symmetrically in the vertical and horizontal directions.

[0020] Of the circular through hole 14 _{1-14 8,} the strain body 1
Located in the center G side of the 0 four circular through-hole 14 _{2, 3, 6, 7
Has the} center deviated in the vertical direction by the same size (δ) with respect to the remaining four circular through holes ₁₄₁ , ₄ , ₅ , and ₈ .

[0021] By forming such a circular through-hole 14 _{1-14 8,} on the strain member 10, the lower beam 16, 18
The total of eight thin-walled portion 24 _{1-24 8} is formed.

[0022] Among the thin-walled portion 24 _{1-24 8,} four thin portions 24 located in the center G (center of gravity) of the strain member 10 _2,3,6,7
The remaining four thickness than the thin portion 24 _1,4,5,8 is thinner by the amount corresponding to the deviation amount of the circular through hole 14 _2,3,6,7 (δ).

The back side of the thin-walled portion 24 _{1-24 8,} i.e., on, on the upper and lower surfaces of the lower beam 16, 18, distortion is connected to the bridge circuit as shown in FIG. 4 constitute a load detection unit 12 gauge 26 _{1-26 8} is bonded, respectively.

[0024] adhering position of each of the strain gauge 26 _{1-26 8,}
As shown in FIGS. 2 and 3, the center of each thin portion 24 _{1-24 8,} the center axis L3 of the width direction of the strain body 10 is adhered so as to be positioned at a point intersecting.

In the case of this embodiment, eight strain gauges 2
6 _{1-26 8} is divided into two groups of four each, the strain member 10
The four strain gauges 26 _2,3,6,7 arranged in a parallelogram so as to surround the center G of FIG.
As shown in, and has a first load detection unit 12 ₁ is connected to the bridge circuit.

[0026] Then, the strain gauges 26 remaining four located outside the four strain gauges 26 _2,3,6,7 constituting the first load detection unit 12 _{1 1,4,5,8} There is likewise a bridge circuit second load detection unit 12 ₂ is connected to.

The strain gauge 26 _{1-26 8} the first and second load detection unit 12 ₁ connected to the bridge circuit, one of the nodal point which faces are common connection, predetermined DC in this part A voltage is applied, and between the other opposing nodal points is the output terminal of each load detecting unit _121,2 .

[0028] In this case, the first and second load detection unit 12 _{1 and 2} need not necessarily connect one nodal point opposite common, may be supplied a voltage separately.

[0029] Now, according to the configuration beam type load cell as described above, have been the load detection unit 12 is provided two, strain gauges 26 _1-26 constituting each detector 12 _1,2
Since ₈ are different in thickness of the thin portion 24 _{1-24 8} which is attached, unlike the detection value when a load is applied to the movable pillar 22, thereby expanding or changing the load cell measurement range .

In the case of this embodiment, as shown in FIG. 2, the pitch p1 between the strain gauges 26 ₁ and 26 ₄
And a strain gauge 26 ₂ are different and the pitch p2 between the 26 _3, bending moment at the time of applying a load to the strain member 10 on the basis of this difference is different.

[0031] Therefore, when changing the thickness of the thin portion 24 _{1-24 8} in consideration of such a difference in bending moment, the measurement range of the load detection unit 12 ₁ can be the same. If the measurement range is the same, it can be replaced when a failure occurs.

Further, in the beam type load cell of the present embodiment, the flexure element 10 has a vertically symmetrical and horizontally symmetric continuous one-piece.
Since only one through-hole 14 may be provided, it is possible to avoid an increase in size as a whole.

At this time, as in this embodiment, the through holes 14
Was constituted by a plurality of circular through-holes 14 ₁ to 14 ₈ in portions mutually overlap in the vicinity of the center G of the strain body 10, by providing concentrated near the center G, further downsizing is achieved Is done.

Further, since the through holes 14 are continuous, machining becomes easy.

Further, in the case of this embodiment, the thin portion 24
_{1-24 8} is on, it provided four under each beam 16, 18, along with constituting the first load detection unit 12 with _one to four inner centered on the center G of the strain member 10, the first since the structure remaining four at the second load detection unit 12 ₂ located outside of one load detection unit 12 _1, when performing corner adjustment, first and second load detection unit between 12 _{1 and 2} Can be reduced.

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

As described above in detail with the embodiments, according to the beam-type load cell according to the present invention, it is possible to change the measurement range and the like while avoiding an increase in the size of the whole, and to reduce the trouble. Occasionally, use is not interrupted, and processing of the through-hole can be easily performed.

Further, according to the present invention, the conventional independent roberval mechanism is replaced with one roberval mechanism, and a load detecting section composed of a plurality of bridge circuits is incorporated, thereby achieving a reduction in size and weight.

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of a beam-type load cell according to the present invention.

FIG. 2 is a top view of FIG.

FIG. 3 is a bottom view of FIG. 1;

FIG. 4 is a circuit diagram of a load detector of the load cell of FIG. 1 ;

DESCRIPTION OF SYMBOLS 10 Strain element 12 Load detector 121 First load detector 122 Second load detector 14 Through hole 16 Upper beam 18 Lower beam 20 Fixed column 22 Movable column 241-248 Thin portion 261-268 Strain gauge

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01L 1/22 G01G 3/14

Claims (1)

(57) [Claims] An upper and lower beam arranged in parallel with each other and fixed and movable columns connected to both ends of the upper and lower beams, and one continuous vertically and horizontally symmetrical through hole is provided. A beam-type load cell comprising a strain-generating body that constitutes a provided roberval mechanism, and a load detection unit that is arranged in a thin portion of the strain-generating body and that is configured with a plurality of strain gauges connected to a bridge circuit. The through-holes have the same diameter and partially overlap each other.
And four thin-walled portions are provided in each of the upper and lower beams.
The first load is formed by the four inner members centered on the center of the strain body.
The first load detecting unit and the first load detecting unit.
The second four load detectors constitute the second load detector, and the thickness of the thin portion of the first load detector is equal to the circular penetration.
By displacing the through hole vertically, the second load detection is performed.
A beam-type load cell , wherein the thickness of the thin portion is different from that of the thin portion .