JP3451977B2 - Scale - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scale having a structure in which a weighing dish is supported by a plurality of load cells.

[0002]

2. Description of the Related Art Conventionally, as a balance for supporting a weighing dish of this type by a plurality of load cells, there is one disclosed in Japanese Utility Model Laid-Open No. 5-33033. This scale, as shown in FIG.
X four load cells 101-104 on the base 105
The load cells 101 to 104 are arranged symmetrically with respect to the axis and the Y-axis, and the outputs thereof are summed in parallel so as to cancel the variations in the outputs of the load cells 101 to 104 (due to the effects of partial weighting and inclination of the scale). ing.

However, in the scale having the above structure, it is premised that the shape of the load cell block (including the wiring board) is bilaterally symmetrical with respect to the center line of the flexure element. However, in order to solve the problems of the conventional load cell block, the inventor of the present application has developed and applied for a patent for a load cell block having a structure in which hard substrates are attached to the side surface of the strain generating element at intervals. Wishhei 11-102755
issue).

In the case of using a load cell block which is not symmetrical about the center line of the strain-generating body in which a hard substrate is attached to one surface of the strain-generating body as described above, each load cell is symmetrical with respect to the X axis and the Y axis. In order to offset the variations in the output of each load cell, use two types of load cells: a load cell with a hard substrate attached to the right side of the strain element and a load cell with a hard substrate attached to the left side of the strain element. Therefore, there is a problem in that the number of parts is increased due to the use of parts of the wrong type, which causes a cost increase.

Further, in the conventional weighing pan receiving structure of a balance using a plurality of load cells, as described in Japanese Utility Model Laid-Open No. 5-33033, a plate-shaped receiving member is fixed to the weighing pan by welding. Then, support it with a convex rubber receiver so that only a vertical load is applied to the load cell, but position it,
Welding parts, polishing, etc. are required, which causes a cost increase.

Since the load cell stopper alone is not sufficient to prevent the impact overload, a balance mechanism using one load cell is provided with a buffer mechanism such as two parallel springs, but the structure using the buffer mechanism is complicated. And could not be used in a balance that uses multiple load cells for large displacements.

Further, in a balance having a structure in which the load cell is fixed to the weighing pan, the change in tension applied to the cord for external connection has a great influence on the measurement accuracy, and accurate measurement cannot be performed.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and even when using a load cell block which is not bilaterally symmetric with respect to the center line of the flexure element, the number of parts does not increase, It is an object to provide a scale using a plurality of load cells at low cost.

Another object of the present invention is to provide a scale using a plurality of load cells having a dish receiving structure that does not increase the cost of positioning, welding parts, polishing and the like.

Another object of the present invention is to provide a balance using a plurality of load cells having a stopper structure having a simple structure and a sufficient impact overload preventing effect.

Another object of the present invention is to provide a plurality of load cells in which the change in tension applied to the cord for external connection does not affect the weighing accuracy even if the load cell is fixed to the weighing pan. It is to provide a scale to be used.

[0012]

In order to solve the above-mentioned problems, the invention according to claim 1 has rectangular weighing pans at four corners.
In a balance having a structure in which four load cells arranged are supported by a supporting portion provided on the load acting point side, the four load cells are raised.
It has a structure in which a substrate is attached to one side of the strain body, and
All load cells are mounted on one side of the strain element.
The digit board is placed in the upper left corner so that it faces the inside of the scale.
Load cell located in the upper right corner.
The dosels are placed in a 90 degree rotated position and are placed in the lower right corner
The loaded load cell is placed in a posture rotated by 180 degrees.
And the load cell located in the lower left corner rotates 270 degrees
It is characterized in that it is arranged in a different posture .

Further, according to the invention as defined in claim 2, the four load cells having rectangular weighing pans arranged at the four corners are fixed on the side opposite to the load action point, and the weighing is carried out by a support portion provided on the load action point side. In a scale with a structure that supports an assembly of a dish and four load cells, the four load cells mount the substrate on one side surface of the flexure element.
The four load cells are all installed
The board attached to one side of the strain body faces the inside of the scale.
As described above, the load cell arranged in the upper right corner is arranged in a posture rotated by 90 degrees with respect to the load cell arranged in the upper left corner, and the load cell arranged in the lower right corner is 18
The load cell arranged in a posture rotated by 0 ° and arranged in the lower left corner is arranged in a posture rotated by 270 °.

By arranging the load cells as described above, even if the load cells which are not bilaterally symmetrical with respect to the center line of the flexure element are used, the deflections of the load cell mounts cancel each other and the influence on the instrument difference is small. Further, the influences of the tilt of the load cell are canceled by each other, so that a non-linearity error does not occur.

The invention according to claim 3 is the same as claim 1
In the balance described in (1) above , a spherical concave recess is formed in a portion of the weighing dish supported by the load cell support portion, and the support portion is provided with a dish receiving portion made of a convex rubber material.

As described above, since the spherical concave recess is formed in the portion of the weighing pan supported by the supporting portion of the load cell,
The concave depression can be integrally formed with the weighing dish, and the positioning accuracy is good and the manufacturing cost is low.

Further, since the spherical concave portion of the weighing dish is supported by the dish receiving portion made of the convex rubber material provided in the supporting portion of the load cell, the load cell is not subjected to moment and horizontal reaction force. Since only the vertical load acts, it is possible to provide a scale with a small four-corner error by adjusting the output of the load cell and without adjusting the four corners by scraping the flexure portion of the flexure element.

Further, since the load cell does not adjust the four corners by cutting the strain-generating part of the strain-generating body, the surface treatment (corrosion-resistant alumite treatment, etc.) on the surface of the strain-generating body does not peel off, and the load cell is scaled by a corrosion-resistant load cell. Can be configured.

Further, even when it is difficult to coat the entire surface for corrosion resistance with a low weighing load cell, the load cell can be constructed with a load cell having excellent corrosion resistance.

The invention according to claim 4 is the same as claim 1.
In the balance described in (1), a load cell mounting table near the lower center of the weighing pan is provided with a stopper for overload prevention in which the weighing pan bends and abuts when the load exceeds the allowable load of the balance. It is characterized by that.

The invention described in claim 5 is the invention according to claim 2.
In the balance described in (1), a stopper for overload prevention is provided in the vicinity of the lower center of the weighing dish , and when the weighing dish is overloaded with more than the allowable load of the weighing instrument , the weighing dish bends and comes into contact with the floor surface or the like. It is characterized by being provided.

When using a plurality of load cells, for example, four load cells, by supporting the load at four points, a load cell having a capacity (1 mV / V) that is ¼ of the weight of the scale is used for each load cell. Although it was weak, the flexure of the weighing pan due to overload and the vertical displacement of the pan due to the deformation of the rubber are prevented by the overload preventing stopper provided in the center, so that a shock resistant scale can be provided.

The invention according to claim 6 is the same as claim 2
In the balance described in 1 above , a curl cord is used as a cord for external connection of the balance.

By using the curl cord as the cord for external connection as described above, even if the weighing dish, that is, the load cell vibrates due to the load being placed, the curl cord absorbs the change in the tension of the cord due to the vibration. As a result, accurate output can be obtained.

[0025]

2 is a diagram showing an example of the structure of a balance according to the present invention, FIG. 2 (a) is a plan view with a weighing pan removed, FIG. 2 (b) is a front view, and FIG. (C) is a side view,
As shown in the figure, the balance is mounted on the load cell mount 1 with 4
The load cells 2 to 5 are attached and fixed. As shown in FIG. 3, the load cell 2 includes a strain gauge 2-on a strain-generating portion of a parallelogram-type strain-generating element 2-1 having two parallel beams.
2 is attached, and the hard substrate 2-6 is attached to the side surface of the flexure element 2-1.
Are mounted at intervals. The hard substrate 2-
Various electronic components such as an output adjustment component including a resistor, a variable resistor and a DIP switch, and a temperature compensation resistor are mounted on the reference numeral 6. The structure of a load cell in which a hard substrate is attached to the side surface of the flexure element is described in Japanese Patent Application No. 11-102755.

A supporting portion 2-3 for supporting the weighing dish 6 is provided on the load acting point side of the strain generating body 2-1 and the anti-load acting point side of the strain generating body 2-1 is supported. Part 2-4 to base plate 2-
It is designed to be fixed at 5. Although not shown, the other load cells 3, 4, and 5 have the same configuration.

The load cell having the above structure is attached and fixed by welding the base plate 2-5 to the load cell attachment base 1. Each load cell 2, 3, 4, 5 has a support portion 2-3, 3-3, 4-3, 5-3 provided on the load action point side and has a circumference 7 around the center O of the weighing dish 6. The load cells 2 to 5 are arranged at the above equally divided positions (in the illustrated example, divided into four), and the load cells 2 to 5 are arranged to have the same posture with respect to the central portion O, respectively. That is, the center line of the flexure element of each load cell 2-5 and the support portions 2-3, 3 of each load cell 2-5.
-3, 4-3, 5-3 and the line connecting the central portion O are arranged at the same intersection angle (45 ° in the illustrated example).

In other words, each of the load cells 2 to 5 has a predetermined angle (90 in the illustrated example) about the center O.
°) It is placed in a position that overlaps when rotated. That is, in FIG. 2, the load cell 3 arranged in the upper left corner is different from the load cell 2 arranged in the upper right corner in the supporting portion 3-.
The load cell 4 arranged in the lower left corner at a position rotated counterclockwise by 90 degrees about 3 is arranged in the lower right corner at a position rotated counterclockwise by 180 degrees about the support portion 4-3. The load cells 5 are arranged at positions rotated 270 ° counterclockwise about the support 5-3.

The load cell mount 1 is supported by four supporting legs 8 whose height can be adjusted. Reference numeral 9 is a level for adjusting the horizontal level of the scale. In the figure, reference numeral 1a is a summing box arranged in the center of the load cell mount 1 for summing outputs of the load cells 2 to 5 in parallel and outputting the sum.

By arranging the four load cells 2 to 5 as described above, even if the scale is tilted as shown in FIGS.
It does not appear as a synthetic output because it occurs so as to be canceled at ~ 5. For example, as shown in Fig. 2 (b), move the balance to the upper side by +
When tilted by α °, this causes load cell 2 to be + α.
Since the load cell 4 is tilted by-° and tilted by -α °, non-linearity due to tilting is offset. In addition, the scale is shown in FIG.
When the right direction is tilted by + β ° as described above, the load cell 5 is tilted by + β ° and the load cell 3 is tilted by -β °, so that the non-linearity due to the tilt is offset.

Further, even when the load cell mount 1 is bent, the load cell 3 and the load cell 5 act as forces in the opposite directions with respect to the X direction deflection, and are offset, and the Y direction deflection occurs with the load cell. Two
, And the load cell 4 act as forces in opposite directions, respectively, so that they cancel each other out and have little influence on the instrumental error.

In the above embodiment, the weighing dish 6 has a square shape, and the supporting portions of the load cells 2 to 5 are arranged so as to be located on the circumference 7 centered on the central portion O. In the case where the weighing dish is not a square but a rectangle, it is possible to expect substantially the same action and effect by arranging the weighing dish in each of the corners in the above-mentioned posture even if it is not necessarily located on the circumference.

Further, in the vicinity of the four corners of the weighing dish 6, FIG.
As shown in FIG. 5, a spherical concave depression 6-1 is formed. The top of the support portion 2-3 of the load cell 2 is shown in FIG.
As shown in FIG. 5, the dish receiving portion 10 made of a convex rubber material that supports the concave depression 6-1 is embedded. Further, the support portions 3-3, 4-3, 5-3 of the other load cells 3, 4, 5 are also provided with the dish receiving portions 10 each made of a convex rubber material. Support parts 2-3 of four load cells 2-5
In the dish receiving portion 5-3, concave recesses 6 near the four corners of the weighing dish 6 are provided.
When the weighing dish 6 is placed with the -1 abutting on it, the scale of the present invention is constructed.

Since the spherical recess 6-1 can be integrally formed when the weighing dish 6 is press-molded, the positioning accuracy can be improved. Since the concave depression 6-1 is supported by the convex dish receiving portion 10 made of a flexible rubber material (for example, silicon rubber), even if the load is small (5 k
(g or less) Since horizontal component force and moment are not applied, and only vertical force is transmitted to the load cells 2 to 5, it is possible to form a movable fulcrum of high-quality position fixing. For this reason, only by adjusting the outputs of the load cells 2 to 5, the scales of the flexure elements 2-1 to 5-1 are not shaved, and the four corners are not adjusted.

The load cells 2 to 5 are the flexure elements 2-1 to 2-1.
Since the flexure portion 5-1 is not cut and the four corners are not adjusted, the flexure body 2-1 having good corrosion resistance is not peeled off without removing the corrosion-resistant alumite-treated film on the surface of the flexure bodies 2-1 to 5-1. A balance can be composed of load cells 2 to 5 equipped with ˜5-1. Further, since the flexure portion is not cut and the four corners are not adjusted, even if it is difficult to coat the entire surface for corrosion resistance with a low weighing load cell, the weighing cell can be configured with a load cell having excellent corrosion resistance.

In the above tray receiving structure, the load cells 2 to 5 are not limited to the scale having the arrangement shown in FIG.
When a load cell block that is bilaterally symmetric with respect to the center line of the flexure element is used, the same operational effect can be obtained by applying the load cell block as shown in FIG.

5A and 5B are views showing another example of the construction of the balance according to the present invention, FIG. 5A is a plan view with the weighing pan removed, and FIG. 5B is a front view. 5 is different from the scale shown in FIG. 2 in that stoppers 11 and 12 for preventing overload are provided on the load cell mount 1 near the lower center of the weighing pan 6. By providing the overload preventing stoppers 11 and 12 as described above, when the weighing pan 6 is overloaded with more than the allowable load of the scale, the weighing pan 6 is bent and the lower surface thereof is overloaded, as shown in FIG. It contacts the screws 11a, 12a of the load preventing stoppers 11, 12.

Assuming that the combined spring constant of the weighing pan 6 and the pan receiving portion 10 is k, when the object w falls from the height h, the initial impact force F is F = k · Δx = mg · [1+ ( 1 + 2 kh / m
g) ^1/2 ], so that the screws 11a and 12a of the overload prevention stoppers 11 and 12 come into contact with the central portion of the weighing pan 6 with the amount of deflection Δl when the maximum load that avoids breakage is applied to the load cell. To do. Even if the displacement Δx of the weighing dish due to the impact force is Δl or more, it is pressed by a screw (also used as a cover stop) at the center of the weighing dish 6, and thereafter, only the force due to the inertial displacement due to the stored momentum is applied to the load cell. This is each load cell 2
It is held down by the stopper of 5.

This shock absorbing mechanism is used in the load cell 2
The present invention can be applied without being limited to the arrangement of ~ 5, and can also be applied to a scale using one load cell.

FIG. 7 is a side view (corresponding to FIG. 1B) showing another structural example of the balance according to the present invention. In the balance shown in FIG. 2, the weighing dish 6 is supported by the supporting portions 2-3, 3-3, 4-3, 5-3 on the load action point side of the load cells 2, 3, 4, 5. In the scale, the support portions 2-4, 3-4, 4-4, 5-4 on the side of the anti-load action points of the load cells 2, 3, 4, 5 (see FIG.
2) is fixed to the weighing pan 6, and the supporting portion 2 on the side of the load acting point
3, 3-3, 4-3, and 5-3 are configured to support the assembly of the weighing dish 6 and the load cells 2, 3, 4, and 5. Further, stoppers 11 and 12 for preventing overload are provided at the center of the weighing dish 6.

In this way, the load cells 2 to 5 are placed in the weighing pan 6
By fixing the load cell to the side, the load cell mounting base becomes unnecessary, and the scale can be made thinner and lighter. However, when a load is placed on the weighing dish 6, the load cells 2 to 5 vibrate together with the weighing dish 6. I will end up. For this reason, the curl code 13 is used as a transfer code for supplying power to each load cell 2-5 and transferring an electric signal. By placing a load on the weighing pan 6, the weighing pan 6, that is, the load cell 2
Although -5 vibrates, even in that case, the curl cord 13 absorbs the tension applied to the cord due to the vibration, so that an accurate measurement output can be obtained.

FIG. 8 shows another example of using the curl cord. This scale is a so-called conveyor scale, and it has a belt 15 between pulleys 14-1 and 14-2.
And the belt 15 is moved by driving the pulley 14-1 with the motor 17. By placing a load on the moving belt 15, the weight is moved and measured by the load cell 16.

In the scale having the above construction, the curl cord 13 is used as a cord for supplying driving power to the motor 17 and a cord for supplying power to the load cell 16 and transmitting / receiving an electric signal. As a result, the rotation of the motor 17 causes the belt 1
5, that is, the load cell 15 vibrates, and even in that case, the tension applied to the cord due to the vibration is applied to the curl cord 13
Since it absorbs at, an accurate measurement output can be obtained.

In the above-described embodiment, the load cells 2 to 5 are two.
Although a double beam type load cell having parallel beams is used, the load cell used in the scale of the present invention is not limited to the double beam type load cell, and a load cell of any configuration can be applied.

FIG. 9 is a diagram showing a structural example of a balance using a single beam load cell. Weighing pan 2 as shown
Four load cells 22, 23, 24, 25 are arranged in positions equally divided on the circumference 7 centered on the central portion O of 1 in the same posture as in the case of FIG.

The load cell 22, as shown in FIG.
The beam 22-1 of the book is provided, the fixing member 22-4 for fixing the load cell 22 to the weighing pan 21 is attached to the supporting portion 22-2 on the side of the load acting point, and the supporting portion 2 on the side of the anti-load acting point is attached.
2-3 are attached to the base of the caster 26. The other load cells 23, 24 and 25 have the same structure as the load cell 22. Thus, even if the four single beam load cells 22 to 25 are arranged to form a scale and the scale is tilted, the non-linearity due to the tilt is not affected by each load cell 22.
It does not appear as a composite output because it occurs so as to be canceled at ~ 25.

[0047]

As described above, according to the invention described in each claim, the following excellent effects can be obtained.

According to the first and second aspects of the present invention, even when a load cell which is not symmetrical with respect to the center line of the flexure element is used, the deflection of the load cell mounting base and the force applied laterally to the scale are symmetrical to each other. The load cell arranged at the position cancels out the influence on the instrument difference. Also,
The effects of the tilt of the load cell cancel each other out and no non-linearity error occurs. Therefore, it is not necessary to use a plurality of types of load cells such as a load cell in which a hard substrate is attached to the right side of the flexure element and a load cell in which a hard substrate is attached to the left side of the flexure element. Therefore, when using a plurality of types of load cells, the number of parts is increased, and the inconvenience that causes a high cost is eliminated.

According to the third aspect of the present invention, since the spherical concave recess is formed in the portion of the weighing pan that is supported by the supporting portion of the load cell, the concave recess can be integrally formed with the weighing pan, and the positioning can be performed. Highly accurate and inexpensive to manufacture.
Further, since the spherical concave depression of the weighing dish is supported by the dish receiving portion made of the convex rubber material provided in the supporting portion of the load cell,
Moment and horizontal reaction force are not applied to the load cell,
Since only the vertical load acts, it is possible to provide a scale with less four errors by only adjusting the output of the load cell and without adjusting the four corners by cutting the strain generating portion of the strain generating body.

Since the load cell does not adjust the four corners by cutting the strained portion of the strained body, the surface treatment (corrosion-resistant alumite treatment, etc.) on the surface of the strainable body does not peel off, and the load cell is scaled with good corrosion resistance. Can be configured. Further, even when it is difficult to coat the entire surface for corrosion resistance with a low weighing load cell, the weighing cell can be configured with a load cell having excellent corrosion resistance.

According to the fourth and fifth aspects of the invention, when a plurality of load cells, for example, four load cells are used, the load is 4
Since each load cell uses a load cell with a capacity (1 mV / V) that is ¼ of the weighing capacity of the weighing scale, it was weak against impact, but the weighing dish was bent due to overload, and the dish was deformed due to rubber deformation. Since the vertical displacement of the is blocked by the overload prevention stopper provided in the center, it is possible to provide a scale resistant to impact.

According to the sixth aspect of the invention, since the curl cord is used as the cord for external connection for power supply and electric signal transmission / reception, the weighing pan, that is, the load cell vibrates when a load is placed. Even if it is done, the change in the tension of the cord due to the vibration is absorbed by the curl cord, so that an accurate output can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a conventional balance using a plurality of load cells.

FIG. 2 is a diagram showing a configuration of a balance according to the present invention, and FIG.
Is a plan view with the weighing pan removed, FIG. 2 (b) is a front view, and FIG. 2 (c) is a side view.

FIG. 3 is a diagram showing a configuration of a load cell used in the balance according to the present invention.

4A is a partially enlarged view of FIG. 2B, and FIG.
(A) is an enlarged view of a support part.

FIG. 5 is a diagram showing a configuration of a balance according to the present invention, and FIG.
Is a plan view with the weighing pan removed, and FIG. 5B is a front view.

FIG. 6 is an operation explanatory view of the scale shown in FIG.

FIG. 7 is a side view showing the configuration of the balance according to the present invention (see FIG.
(Corresponding to (b)).

FIG. 8 is a diagram showing a configuration of a balance according to the present invention.

FIG. 9 is a diagram showing a configuration of a balance according to the present invention, and FIG.
Is a plan view, FIG. 9 (b) is a side view, and FIG. 9 (c) is a front view.

FIG. 10 is a diagram showing a configuration of a single beam type load cell used in the balance according to the present invention.

[Explanation of symbols]

1 Load cell mount 2 load cell 3 load cell 4 load cell 5 load cell 6 weighing dish 7 circle 8 support legs 9 spirit level 10 Plate receiver 11 Overload prevention stopper 12 Overload prevention stopper 13 curl code 14 pulley 15 belts 16 load cell 17 motor 21 weighing dish 22 load cell 23 load cell 24 load cell 25 load cell 26 casters

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01G 21/23 G01G 23/02

Claims (6)

(57) [Claims] 1.RectangularWeighing pan4 pieces placed in the four corners
A structure that is supported by a support unit that is provided on the load application point side of the load cell.
In the built scale,The four load cells have a substrate on one side of the flexure.
It is the attached structure, Each of the four load cells is on one side of the flexure element.
In the upper left corner so that the board attached to the surface faces the inside of the scale.
It is placed in the upper right corner of the loaded load cell.
The loaded load cell is placed in a posture rotated 90 degrees and
The load cell placed in the lower corner is rotated 180 degrees
The load cell in the lower left corner is 2
It is placed in a posture rotated by 70 degrees Characterized by
Scales. 2. A rectangular weighing dish with four
Fix the anti-load action point side of the load cell to the load action point side
With the support provided, the assembly of the weighing pan and four load cells
In the supporting structure scale,The four load cells have a substrate on one side of the flexure.
It is the attached structure, Each of the four load cells is on one side of the flexure element.
In the upper left corner so that the board attached to the surface faces the inside of the scale.
It is placed in the upper right corner of the loaded load cell.
The loaded load cell is placed in a posture rotated 90 degrees and
The load cell placed in the lower corner is rotated 180 degrees
The load cell in the lower left corner is 2
It is placed in a posture rotated by 70 degrees Characterized by
Scales. 3.The scale according to claim 1, A ball is placed on the portion of the weighing dish supported by the load cell support.
Form a planar concave recess, and from the convex rubber material to the support
A scale which is provided with a dish receiving part. 4. The balance according to claim 1, wherein the load cell mount near the lower center of the weighing pan,
A balance provided with a stopper for preventing overload that the weighing dish bends and abuts when the weighing dish is loaded with a load more than an allowable load. 5. The balance according to claim 2, wherein when the weighing pan is overloaded in the vicinity of the lower center of the weighing pan over the allowable load of the balance, the weighing pan bends to a floor or the like. A scale provided with a stopper for preventing abutting overload. 6. The balance according to claim 2, wherein a curl cord is used as a cord for external connection of the balance.