JPH085444A - Load cell balance - Google Patents

Abstract

PURPOSE:To precisely calculate a weight based on the output of a first load cell even if a second load cell mistakenly outputs a lighter weight by linking the fixed end of the second load cell with a moving frame connected to the moving end of the first load cell and linking a pan to its moving end. CONSTITUTION:The fixed end 3 of a load cell 4 penetrates an aperture 12 formed at the bottom plate 11 of a moving frame 6, and the moving end 5 of the load cell 4 is fixed to the bottom surface of the top table 13 of the frame 6. The fixed end 3 of a load cell 8 is fixed to the top surface of the bottom plate 11 of the frame 6, and the moving end 9 of the load cell 8 penetrates an aperture 14 formed at the top table 13 of the frame 6. A support frame 10 is fixed to the moving end 9, and a pan 15 is supported. And, CPU compares the output value of the load cell 4 with a preset reference value, and when the output value of the load cell 4 is greater than the reference value, CPU calculates a weight based on this output value, and when it is smaller, CPU calculates the weight based on the output value of the load cell 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load cell balance in which the weighing range is expanded by two load cells without lowering the weighing accuracy.

[0002]

2. Description of the Related Art At present, a load cell balance for calculating the weight of an article as electric data is put into practical use. This load cell scale is constructed by connecting a fixed end of a load cell with a strain gauge connected in a bridge to the main body base and connecting a saucer to a movable end, depending on the weight of articles loaded on the saucer. The strain amount generated in the load cell is electrically measured with a strain gauge to perform the measurement.

In the load cell balance as described above, it has recently been demanded to expand the weighing range without lowering the weighing accuracy. Therefore, in order to cope with this, the load cell balance proposed by the present applicant is used. , JP-A-61-24
It is disclosed in Japanese Patent No. 6631 and Japanese Patent Laid-Open No. 61-260124.

This load cell balance is provided with a first load cell for large weighing and a second load cell for small weighing, and a movable frame is connected to the movable end of the first load cell whose main body base is connected to the fixed end. The structure is such that the support frame is connected to the movable end of the second load cell whose fixed end is connected to this movable frame, and the saucer is supported by the end of this support frame. Then, in such a load cell balance, the output value of the second load cell and a preset reference value are compared, and when the output value of the second load cell is larger than the reference value, the output value of the first load cell is set. Calculate the weight based on
When the output value of the second load cell is smaller than the reference value, the weight is calculated based on the output value of the second load cell.

By doing so, since the heavy weight is measured by the first load cell and the light weight is measured by the second load cell, the weighing range can be expanded without lowering the weighing accuracy. it can. In addition, in such a load cell scale, rather than the first load cell for large weighing,
Since the second load cell for small weighing has a narrower measuring range and thus has a larger output per unit weight, the first load cell and the second load cell are switched with reference to this second load cell.

[0006] In such a load cell balance, the first four corner stoppers facing each other in the vertical direction are provided at the four corners of at least one of the upper surface of the main body base and the lower surface of the movable frame so as to prevent the first load from being applied by an excessive load. The first four-corner stopper prevents the one load cell from being destroyed, and the second four-corner stoppers facing each other in the up-down direction are provided at the four corners of at least one of the upper surface of the movable frame and the lower surface of the support frame so as to be excessive. The second load cell is prevented from being broken by the load by the second four corner stoppers.

[0007]

In the above-mentioned load cell balance, the heavy weight and the light weight are shared by the first load cell and the second load cell to measure the weight, thereby measuring a wide range of weights with good accuracy. It is supposed to do. here,
In such a load cell balance, when a large load acts on the saucer, the second four-corner stoppers support the support frame descending together with the saucer on the movable frame, and the first load cell deforms as the movable frame descends. The weight is measured by.

However, in the state where the second four corner stoppers are in contact with each other under a large load as described above, for example, a bending moment acts on the second load cell due to the deformation of the support frame, and the second load cell is May output a light weight. In such a case, even if the first load cell outputs an accurate weight, an incorrect weight will be calculated based on the output of the second load cell.

[0009]

[Means for Solving the Problems] A first load cell for large weighing and a second load cell for small weighing are provided, and a movable frame is attached to a movable end of the first load cell in which a fixed end is connected to a main body base. Connected, the saucer is connected to the movable end of the second load cell whose fixed end is connected to this movable frame,
An output comparing means for comparing an output value of the first load cell with a preset reference value is provided, and when the output comparing means detects that the output value of the first load cell is larger than the reference value, the first load cell is output. The first load calculating means for calculating the weight based on the output value of the load cell, and when the output comparing means detects that the output value of the first load cell is smaller than the reference value, the output of the second load cell A second weight calculation means for calculating the weight based on the value is provided.

[0010]

When the output comparing means compares the output value of the first load cell and the preset reference value, the first weight calculating means determines that the first weight calculating means is the first when the output value of the first load cell is larger than the reference value. The weight is calculated based on the output value of the load cell, and when the output value of the first load cell is smaller than the reference value, the second weight calculating means calculates the weight based on the output value of the second load cell.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. First, in the electronic charge balance 1 which is this load cell balance, as illustrated in FIGS. 1 and 2, a box-shaped movable end 5 of a first load cell 4 having a fixed end 3 connected to a flat plate-shaped main body base 2. The movable frame 6 of is connected,
An X-shaped support frame 10 is connected to a movable end 9 of a second load cell 8 whose fixed end 7 is connected to the movable frame 6.

More specifically, the fixed end 3 of the first load cell 4 fixed to the upper surface of the main body base 2 passes through an opening hole 12 formed in the bottom plate 11 of the movable frame 6, The movable end 5 of the first load cell 4 is fixed to the lower surface of the top plate 13 of the movable frame 6.
The fixed end 3 of the second load cell 8 is fixed to the upper surface of the bottom plate 11 of the movable frame 6, and the movable end 9 of the second load cell 8 is the top plate 1 of the movable frame 6.
3 penetrates the opening hole 14 formed. A support frame 10 is fixed to a movable end 9 of the second load cell 8 that penetrates through an opening hole 14 in a top plate 13 of the movable frame 6, and the support frame 10 supports a saucer 15.

In the electronic charge balance 1, support pillars 16 made of bolts and nuts are provided at the four corners of the upper surface of the main body base 2 in a protruding manner. The support pillars 16 are provided at the four corners of the movable frame 6. The first four-corner stopper 18 is formed between the support member 17 and the support column 16 by facing the support member 17 made up of bolts and nuts, etc.
Are formed. Support pins 19 project from four corners of the lower surface of the support frame 10. The support pins 19 face the support member 17 of the movable frame 6 from directly above, so that the support members 17 and Second four-corner stoppers 20 are formed with the support pins 19.

By doing so, the electronic charge balance 1
Then, the first four-corner stopper 18 composed of the support column 16 and the support member 17 and the second four-corner stopper 20 composed of the support member 17 and the support pin 19 are located at the same position in the horizontal direction. It is located in.

In the load cell balance 1, the first load cell 4 and the second load cell 8 have strain gauges (not shown) attached to the upper and lower surfaces of the strain-flexing portions thereof. As illustrated in FIG. 3, the strain gauges of the first load cell 4 and the second load cell 8 are bridge-connected and then connected to one CPU (Central Processing Unit) 21 that executes various data processing. ing. Here, the CPU 21 has a ROM (Read Only) in which various data such as a control program is stored in advance.
Memory) 22, a RAM (Random Access Memory) 23 for temporarily storing process data and the like in an updatable manner, and an exchangeable EEPROM (Elect
rically Erasable Programmable Read Only Memory) 2
4, a display 25 for displaying and outputting various data, a keyboard 26 for inputting and operating various data, etc. are connected.

Therefore, in the load cell balance 1, as will be described later as step T6 in the flow chart illustrated in FIG. 4, the output comparing means outputs the output value of the first load cell 4 and the reference value preset in the ROM 22 or the like. It is designed to compare with. Then, as will be described later in step T7, the first load cell 4 is set on the basis of this reference value.
Is detected, the first weight calculation means calculates the weight based on the output value of the first load cell 4, and as described later in step T8, the weight is calculated from the reference value. When it is detected that the output value of the first load cell 4 is small, the second weight calculating means calculates the weight based on the output value of the second load cell 8.

In this load cell balance 1, since the reference value serves as a threshold value for switching the first load cell 4 and the second load cell 8 as described above, this is the second value for small weighing. It is set as the output value of the first load cell 4 before the four corner stoppers 20 are activated.

In the electronic charge balance 1 having such a structure, when the first and second load cells 4 and 8 are distorted in accordance with the weight of articles (not shown) loaded on the tray 15, The CPU 21 calculates the weight of the article based on the output values of the first and second load cells 4 and 8 that generate distortion.

At this time, the CPU 21 sequentially takes in the output values of the first load cell 4 and the second load cell 8 as shown in FIG. 4 (steps T1 and T2), and flicker-processes these output values. After each is executed (steps T3, T4), the key processing corresponding to the input operation of the keyboard 26 is executed (step T5). Then, the output value of the first load cell 4 is compared with a reference value preset in the ROM 22 or the like (step T6), and if the output value of the first load cell 4 is larger than the reference value, the first The weight is calculated based on the output value of the load cell 4 (step T7). When the output value of the first load cell 4 is smaller than the reference value, the weight is calculated based on the output value of the second load cell 8 ( Step T8). Then, the weight calculated in this way is displayed and output on the display 25 (step T9), and when this display output is completed, the initial state is restored.

By doing so, for example, when a large load acts on the tray 15 and the second four corner stoppers 20 are in contact with each other, a bending moment is applied to the second load cell 8 due to the deformation of the support frame 10. Even if the second load cell 8 acts to output a light weight by mistake, the weight can be accurately calculated based on the output of the first load cell 4.

In the electronic charge balance 1, when an excessive weight acts on the tray 15, the second four-corner stoppers 20 support the support frame 10 that descends together with the tray 15 on the movable frame 6 to make the second Of the movable frame 6 that protects the load cell 8 and descends together with the saucer 15 in this state.
The first four-corner stoppers 18 are supported on the main body base 2 to protect the first load cell 4.

At this time, in the electronic charge balance 1, the movable frame 6 is pressed from below at the position of the first four corner stoppers 18 and from above at the position of the second four corner stoppers 20. First and second four corner stopper 20
Are arranged at the same position in the horizontal direction, the bending stress does not act on the movable frame 6. Therefore, in this electronic charge balance 1, even if an excessive weight acts on the tray 15, the movable frame 6 does not bend,
Weighing accuracy is constantly maintained.

In the electronic charge balance 1 of this embodiment, since the support members 17 mounted on the four corners of the movable frame 6 are shared by the first and second four corner stoppers 18 and 20, the number of parts is reduced. As a result, the productivity is improved, and the horizontal positions of the first and second four-corner stoppers 18, 20 are exactly the same, so the characteristics are extremely good.

Further, in the electronic charge balance 1 of the present embodiment, the first and second load cells 4 and 8 exemplify that the weighing range is expanded without lowering the weighing accuracy. It is also possible to add a fourth load cell (both not shown), etc. to further expand the weighing range. In this case, the load cell that measures heavy weight is used as a reference and the load cell that calculates weight is switched sequentially. become.

[0025]

As described above, the present invention provides the first load cell for large weighing and the second load cell for small weighing,
A movable frame is connected to the movable end of the first load cell whose fixed end is connected to the main body base, and a saucer is connected to the movable end of the second load cell whose fixed end is connected to this movable frame. Output comparing means for comparing the output value of the load cell with a preset reference value is provided, and when the output comparing means detects that the output value of the first load cell is larger than the reference value, the output of the first load cell A first weight calculating means for calculating weight based on a value is provided, and when the output comparing means detects that the output value of the first load cell is smaller than a reference value, based on the output value of the second load cell. By providing the second weight calculation means for calculating the weight, for example, a large load acts on the saucer and a bending moment acts on the second load cell due to deformation or contact of each part. Even if this second load cell outputs a light weight by mistake, the output of the first load cell in this case is larger than the reference value, so it is possible to accurately calculate the weight based on the output of this first load cell. It is possible.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view illustrating the internal structure of an electronic charge balance that is a load cell balance according to an embodiment of the present invention.

FIG. 2 is a vertical sectional front view illustrating the internal structure of the electronic toll scale.

FIG. 3 is a block diagram illustrating a circuit structure of an electronic toll scale.

FIG. 4 is a flowchart illustrating data processing of an electronic toll scale.

[Explanation of symbols]

 1 load cell scale 2 main body base 3,7 fixed end 4 first load cell 5,9 movable end 6 movable frame 8 second load cell 15 saucer

Claims (1)

[Claims] 1. A first load cell for large weighing and a second load cell for small weighing are provided, and a movable frame is connected to a movable end of the first load cell whose fixed end is connected to a main body base. An output comparing means is provided for connecting the receiving end to the movable end of the second load cell, whose fixed end is connected to the movable frame, and comparing the output value of the first load cell with a preset reference value. When the means detects that the output value of the first load cell is larger than the reference value, the first weight calculating means for calculating the weight based on the output value of the first load cell is provided, and the output comparing means is the reference value. The load cell balance further comprising second weight calculating means for calculating weight based on the output value of the second load cell when it is detected that the output value of the first load cell is smaller.