JPS5876728A - Load cell type platform scale - Google Patents

Abstract

PURPOSE:To make it possible to prepare accurate data in response to loads all the time and to elongate the life of the load cells, by mounting a mounting pan on each load cell so that it can be freely separated, adding the outputs of the cells, and obtaining the weight data. CONSTITUTION:The mounting pans 23 and placed on the load cells 4-7. Conductive elastic concave members 24-27 are fixed to the parts facing convex members 16-19 of the cells. The cells 4-7 constitute bridges wherein strain gages 11-14 form their arms. The outputs of the cells are supplied to an adder 33. The added output is made to be counted data by an A/D converter 51 and supplied to a controller device 55. The device 55 computes the counted data in relation to a preset minimum objective value count, converts the result into the weight data in gram unit, and supplies the result to a display 56.

Description

[Detailed description of the invention] (1) Technical field of the invention This invention relates to a load cell type platform scale.

(2) Prior Art Conventionally, one load cell was used, a plate was fixed to the load receiver of the load cell, and the output of the load cell was amplified to obtain weight data.

(3) Problems with the conventional technology There was a problem in that the displacement of the load cell when a load was applied varied depending on where the object to be weighed was placed on the mounting pan, and this was reflected directly in the measured value. . In addition, since the loading plate and the load cell are fixed, there is a risk that the funnel 9 cells may be deformed when the plate is lifted, and for this reason, it is necessary to provide a stopper 4- that restricts the upward movement of the plate. Also, the load impact on the plate is loaded (4)
Purpose of the Invention This invention is capable of suppressing changes in measured values due to differences in the load position relative to the mounting plate as much as possible, and in addition, the mounting plate and the load cell can be separated, so there is no risk of deformation of the load cell even if the mounting plate is lifted. The purpose is to provide a load cell type platform scale that does not require a load cell type platform scale.

Further, the present invention provides a load cell type platform scale in which there is no fear that a load impact on a mounting plate is directly applied to the load cell, and the life of the load cell can be extended.

(5) Invention 4! This invention distributes at least three or more load cells approximately evenly around the periphery of the pace, places a mounting plate separably over each load cell, and connects the output of each load cell to a plurality of buffer amplifiers. After amplification, the outputs of each amplifier are added together by an adder having a variable resistor for adjusting each, and weight data is obtained from the output of the adder.

Further, in this invention, a pedestal made of an elastic member is interposed between each load cell and the mounting plate.

(6) Embodiment of the Invention As shown in FIG.
2d and overload stocking protrusions 3a to 3d are integrally molded as a pair. That is, the protrusions 2a and 3a,
2b and 3b.

2c and? c, 2d and 3d each form a pair, and each overload stop horn 91 protrusion 3a to 3d is formed to be located on the outside of the pace 1 with respect to each load cell mounting protrusion 2a to 2d. ing.

Four load cells 4.5 and 6.7 are respectively attached to each of the load cell attachment projections 2a to 2d. As shown in FIG. 2, each of the load cells 4 to 7 has a hole 8.9 in which the side surfaces communicate with each other, and thin-walled portions 10h, 10b, 10c are formed on the upper and lower surfaces of each of the holes 8 and 9, respectively. 10
d, and two strain r-gears 11, 12, 13, and 14 are attached to each of the thin-walled portions 10h and 10b formed on the upper surface of each of the thin-walled portions. As shown in FIG. 4, portions A of the non-load receivers of each of the load cells 4 to 7 are fixed to the respective load cell mounting protrusions 2a to 2d by screws 15. Each of the overload stopper protrusions 3a to 3d corresponds to each of the load cells 4 to 3d.
The load receiver is made slightly lower than the height of each of the load cell mounting protrusions 2a to 2d so that when an overload exceeding the weighing load is applied to the load receiver 7, the lower end of the portion B comes into contact with the load receiver. The load receivers of each of the load cells 4 to 7 have truncated cone-shaped convex members 16, 17, 18, and 19 made of a conductive elastic member that form part of the pedestal fixed to the upper end surface of part B with screws 20. There is. A circuit unit 21 containing a buffer amplifier, an adder, etc. is attached to the center of the pace 1, and this circuit unit 21 is connected to each strainage 11 to 14 of each of the load cells 4 to 7 through a cord 22. and is connected to an external circuit unit (not shown).

6. Each of the load cells 4 to 7 is mounted with a support @23 whose end is bent downward as shown in FIG. Convex members 16 - of each of the load cells 4 - 7 on the mounting plate 23
19, there are concave members 24, 2 made of a conductive elastic material forming the remaining part of the pedestal, as shown in FIG.
5°26.27 is fixed. Each of the concave members 24~
Reference numeral 27 has a shape in which the inner surface of the recess expands outward, and the expansion is set to be sufficiently larger than the cheeks of each of the convex members 16 to 19.

FIG. 5 shows the circuit configuration, and each load cell 4.5, 6
．． 7 is for each strain r-ge 11.12, 13.1, respectively.
It constitutes a four-sided resistance bridge with 4 on each side. Each load cell 4.5.6.7 is connected to the battery 28 by one opposing contact of the Kelbridge. One of the other opposing contacts of the bridge in each of the load cells 4, 5, 6.7 is connected to a buffer amplifier 29,
JO...? Z, J2 non-inverting input terminal (+)
and the other is grounded. Each of the buffer amplifiers 29
, ,? The outputs of 0, 3 J, and j2 are input to the adder 33. The adder 33 has a variable resistor 34
, 35, 36, J7, JR and an operational amplifier 39, each of the buffer amplifiers 29, 30, 37
, ,? Each output of 2 is a variable resistor, ? 4,
35. ,? 6, :? 7 to the inverting input terminal (-) of the operational amplifier 39. The non-inverting input terminal (10) of the operational amplifier 39 is grounded. Further, a reference voltage generation circuit 40 is connected to the battery 28. The reference voltage generation circuit 40 includes a buffer amplifier 41
, 42 , differential amplifier 43 and resistor 44 . variable resistance 45
．． In the series circuit of the resistor 46, the positive terminal of the battery 28 is connected to the non-inverting input terminal (+) of the buffer amplifier 41, and the negative terminal is connected to the non-inverting input terminal (+) of the buffer amplifier 42. The output terminal of the buffer amplifier 4 is connected to the non-inverting input terminal (+) of the differential amplifier 43 via a resistor 47, and is further grounded via a resistor 48. resistance 4
9 to the inverting input terminal (-) of the differential amplifier 43, and further connected to the output terminal of the differential amplifier 43 via a resistor 5o. The differential amplifier 43
The output terminal of the resistor 44. Variable resistance 45. It is grounded via a resistor 46. Then, a standard voltage is generated from the movable terminal of the variable resistor 45, and the reference voltage is supplied to the A/1) converter 51, and is passed through the buffer amplifier 52 and the variable resistor 38 of the adder 33 to the operational amplifier 39.
It depends on the inverting input terminal (-) of . The operational amplifier 39 has a resistor 53 connected between its inverting input terminal (-) and its output terminal, and its output terminal is used as the output terminal of the adder 33. The operational amplifier 39 supplies its output to the A/D converter 51 via a low-pass filter 54. The A/[) converter 51 is, for example, of a double integral type, and outputs count data according to the input voltage from the adder 33. The A/D converter s1c) cD9- The count data is taken into the control device 55, and based on the predetermined minimum scale value X = Y count, the count data 2 is calculated by z/YxX to form a duram unit. The data is converted into broken data and displayed on the display 56.

In the figure, 57 is a part of the gear, which is used for setting zero points, tare weight subtraction, etc.

In the embodiment of the present invention configured as described above, the load receivers of the load cells 4 to 7 are provided with overload stopper protrusions 3a to 3d below part B, so that no overload is applied to the mounting plate 23. Even if each load cell 4~7 is shaped like each protrusion? It can be stopped at points a to 3d, and abnormal deformation of the load cell can be prevented. In addition, since each load cell 4 to 7 and the mounting plate 23 are separated by a pedestal, even if the plate 23 is lifted upward, each load cell 4 to 7
There is no risk that it will be deformed as a result. Even if there is a side impact on the broken mounting plate 23, the convex members 16 to 19 of the pedestal
and the concave members 24 to 27 are separated from each other and combined, but only 10
- Since these are also made of elastic members, the impact is sufficiently absorbed and there is no risk of large impact being transmitted to the load cells 4-7. Further, even if an impact is applied to the mounting plate 23 from above, it can be absorbed by the pedestal, so that the impact is not directly transmitted to the load cells 4 to 7. Therefore, the load cell can be protected from impact and the life of the load cell can be extended. There are also two thin-walled portions 10 a on the top and bottom surfaces as pedestals or load cells.
* Donkey that formed 10b + 10c r1θd
Thin parts 10a and 10b on the top surface are used.
Strain r-ges 11, 12 and 1 are installed at two locations each.
3゜14 is installed, so how far in part B is the load receiver?
Even if a load is applied carefully, the output voltage can be kept constant with respect to the load, and the installation and wiring of the strainer can be easily performed.

Furthermore, load cells 4 to 7 are attached to the four corners of pace 1 with their load receivers facing outward, and each load cell 4 to 7 is shrunk.
Since the load cells 23 are separably placed on the load cells 4 to 7 via the pedestal, the strain of each load cell 4 to 7 is reduced.
1. rゝ-JI-14 is affected by the bending moment due to the unbalanced load. The il of the load cell output for the load on the blood 23 can be prevented by canceling out each other. It is possible to sufficiently maintain the forest character. The outputs of the load cells 4 to 7 attached to the four corners of the trench base L are added by the adder 33, and the added output is converted into count data by the A/I) converter 51 to obtain weight data. Accurate weight data corresponding to the load can be obtained no matter where on the tray 23 the load is applied. Moreover, even if there are variations in sensitivity among the load cells 4 to 7, the variable resistors 34 to 37 can be adjusted so that the same addition input is generated when the same load is applied to each load cell 4 to 7. It is possible to sufficiently correct variations in sensitivity between load cells.

Also, the output of each load cell 4 to 7 is Et l
R21Es * Ea, variable resistor 34 to 37
The resistance value is R34* Ras + Rsa + R37
And if the resistance value of the resistor 53 is R53, then the adder 3
3, that is, the output E5 of the operational amplifier 39 is as follows. Here R54= a 2・Et3s * R3
4= R3HRs6* R34=a4°R37 (however, a
2+a3. R4 is a coefficient), and if R53≠R34, then R5
is E s = E t + a 2 R2 + a 3
E 3 + a 4 E 4 ...■.

In this way, the outputs of the load cells 4 to 7 can be added, and the sensitivity of the output to the load can be sufficiently increased.

Further, the buffer amplifier 52 and the variable resistor 38 are used to set the zero point, and the reference voltage from the reference voltage generation circuit 13-40 is set as R7, the resistance value of the variable resistor 38 is set as Ras, and R34=IL t · If it is R2H, the adder output E5 considering this is R5=J +a2 ・Ex +a3 ・FJ* +a4
・R4+a7 ・R7...■ Also, R7 is a resistance of 47.4B, 49°50.44
．． 46 and variable resistor 45, respectively, R471R.
4H, R4G, Rso, R44* R46+R
41i, the voltage of the battery 28 is v9, and GatsuR
47"R41, R48""R50 will be enough. However, R'45 is the resistance value to the movable terminal ◇ Therefore, A/
The count data NR from the D converter 51 is the A/D
If the input voltage to the converter 5 is Ea, and the reference count data in the A/l converter 51 is N, then the following equation is obtained. Here, if E5=E7, it becomes 14-. Here, the output E of each load cell 4-7.

~E4 and the battery voltage E7 are related to the battery 28 voltage v, so that E, = -V, (1 = 1 to 4), E7 = X (1
Since it is expressed as vo, it can be understood from the relationship of the 0 equation that the zero point can be set by changing a7 using the variable resistor 38.

In the above embodiment, four load cells were used, but the present invention is not limited to this, and three or five or more load cells may be used.

(7) Effects of the Invention As described above, in the present invention, at least three or more load cells are distributed approximately evenly around the base of the pace, and a plate can be placed on each of the load cells in a separable manner. The weight data is obtained by adding the output of each load cell using an adder with a variable resistance that adjusts the output, so no matter where on the plate the load is placed, it always corresponds to the load. Get accurate weight data,
Moreover, it is possible to provide a load cell type platform scale in which there is no possibility that the load cell will be deformed even if a force is applied to lift the plate upward.

In addition, since a pedestal made of an elastic member is interposed between each load cell and the mounting plate, even if there is a load impact on the mounting plate, the pedestal absorbs the impact and suppresses the impact on each load cell. It is possible to provide a load cell type platform scale that can extend the life of the weigher.

[Brief explanation of drawings]

The figures show an embodiment of the present invention, in which Fig. 1 is a perspective view showing the internal structure, and Fig. 2 is a diagonal screw 11 showing the load cell structure.
FIG. 4 is an enlarged sectional view of a part of FIG. 3, and FIG. 5 is a circuit diagram. I...Pace, 4.5, 6.7...Load cell, 1
B, 17.18.19...Convex member, 23...Plate, 24,25,26.27...Concave member, 28...Battery, 29.30. :41.32...Buffer amplifier, 33...Adder, 34.35, 36.37...Variable resistor, 5-channel converter, 55...Control unit!
deep red. Applicant's agent Patent attorney Takehiko Suzue 17-

Claims (6)

[Claims] (1) A base, at least three or more load cells distributed approximately evenly around the base, a mounting tray separably placed over each of the load cells, and amplifying the output of each of the load cells. A load cell type platform scale comprising a plurality of buffer amplifiers, each having a variable resistor for adjusting the output of each amplifier, and an adder for adding the outputs of each amplifier, and obtaining weight data from the output of the adder. . (2) The load cell has a donkey pal mechanism in which two thin sections are formed on each of the upper and lower surfaces, and a strain r-gee is attached to the thin sections. Load cell type platform scale. (3) Claims characterized in that the strain r-gear is attached only to two thin parts formed on one side, and the load cell is attached with its fTm receiver facing outward of the base. The load cell type platform scale described in item 2. (4) A base, at least three or more load cells distributed approximately evenly around the top of the base, a mounting plate separably placed over each of the load cells, and each of the load cells and the mounting plate. a pedestal made of an elastic member interposed therebetween, a plurality of buffer amplifiers that amplify the outputs of each of the load cells, and an adder that has variable resistors that adjust the outputs of each of the amplifiers and adds the outputs of each of the amplifiers; A load cell type platform scale, characterized in that weight data is obtained from the output of the adder. (5) The load cell type platform scale according to claim 4, wherein the base is made of a conductive elastic member. (6) The pedestal consists of a concave member whose concave inner surface expands outward and a convex member that is fitted into the concave part of the concave member. A load cell type platform scale according to claim 4 or 5, characterized in that the load receiver of the load cell is attached to the portion.