JPS5967424A - Load converter - Google Patents

Abstract

PURPOSE:To achieve a higher measuring accuracy and a simpler construction by maximizing and uniformizing the distortion generated at the adhered section of a strain gauge with a tapered narrower section providing on a strain gauge mount part of beams. CONSTITUTION:A distortion generator is provided to constitute a Roberval's parallel motion mechanism with a pair of beam 5 and 6 and a pair of stays 3 and 4. The load of an object to be measured is applied to a distortion generator whose one end is fixed at a fixed end 7 and a distortion generated on the surface of the distortion generator is detected with strain gauges 12a and 12b to measure the load. A tapered narrower section is provided on the adhered section of the strain gauges at horizontal and longitudinal positions. The gradient of the taper is selected so that the distortion is generated evenly at the adhered section of the strain gauges, in other words, so as to cancel changes in the bend moment due to position. Moreover, a fixed cut is provided to improve the sensitivity without concentration of load on the fixed end. This achieves a higher measuring accuracy and a simpler construction.

Description

[Detailed description of the invention] The present invention relates to load transducers.

In load transducers for military weapons and the like, errors and fluctuations in the load sensor directly affect the constant value of the load sensor, so improving and improving its characteristics and precision is an important issue.

A strain sensor is known as a load sensor. According to this method, the load of the object to be measured is applied to a strain body fixed at one end, and the strain generated on the surface of this strain body is measured. Then, it is converted to a weight value and displayed. Figure 1,
FIG. 2 shows an example of the structure of a conventional strain-generating body, showing a top view, a front view, and a strain amount of 2] at each position. Figure 1 shows an inexpensive load cell-type load transducer that consists of a flexible body made by drilling holes in a metal block, and Figure 2 shows an inexpensive load cell type load transducer that has a flexible body made up of a pair of plate beams and a pair of stays. Both of them have a so-called donkey pal mechanism in order to eliminate eccentricity errors in one direction. Also,
The bonded part of the strain gauge is made thin or narrow in order to increase the detection sensitivity, so that the section modulus is small and the strain generated is small.

Now, the conventional load transducer described above is constructed as described above, but as is clear from Figures 1 and 2, the strain generated in the overlapping part (bonded part) of the strain gauge is not uniform. (varies depending on the position), and even unnecessary parts, such as the strain gauge lead ffIJnA terminal processing section, are affected by the strain, making it difficult to detect! It was having a negative effect on the If degree. Furthermore, there is a high possibility that concentrated loads will be generated at the fixed ends (screwed, welded) that form and maintain the load transducer in the shape of a parallelogram. This has the disadvantage of worsening the performance and detection accuracy.

The present invention was proposed in view of these points, and it eliminates the conventional drawbacks by improving the beam constituting the strain body of the load transducer, and further improves the functionality of the load transducer. The purpose of this invention is to provide a load converter with a simple structure and high accuracy.

FIG. 3 shows the relationship between the beam shape before improvement and its distortion distribution, shown for comparison with the present invention.

An actual strain-generating body is often constructed by arranging two beams shown here to face each other and connecting both ends with a pair of stays. In Fig. 3, a and b indicate strain gauges, but in this type of beam, the strain that occurs at the bonded part of the strain gauge is not uniform, and the further away from the center to the end, the more the strain increases. It's big. Further, since strain is continuously generated around the bonded portion of the strain gauge, the effect of strain also appears on the lead wire end processing portion of the strain gauge.

Therefore, in the present invention, in order to eliminate the above-mentioned conventional drawbacks, tapered narrow portions are provided at symmetrical positions in the overlapping portion (adhesive portion) of the strain gauge as shown in FIG. 4.

The slope of this chi is selected so that the strain generated at the bonded part of the strain gauge becomes uniform, that is, so as to cancel out the change in bending moment due to position tel, and to cause a concentrated load on the fixed A1 part. A certain number of cuts are made to improve sensitivity. In addition, if the shape of the chi/mother is described specifically, it will be a fixed end side; a case or shape narrowed in the direction of the load moving end; a load end side; a tapered shape narrowed in the fixed end direction.

According to this improvement, since uniform strain is generated over the entire sensitive area of the strain gauge, the detection accuracy is improved, and the strain gauge is
Since the strain generated is sufficiently small in areas other than the bonded part of the lead wire, the effect on the lead wire end processing area can be greatly reduced. On the other hand, in the conventional beam configuration as shown in Fig. 3, it was necessary to consider the concentrated load on the fixed end in order to increase the detection sensitivity, but according to the present invention, the maximum load just before the fixed end has to be considered. It is possible to apply a strain equal to or greater than the strain to the strain gauge, and conversely, it is possible to reduce the concentrated load at the fixed end for the same detection sensitivity, making it suitable for use as a load converter. Repeatability, reproducibility, and linearity can be improved.

Next, FIG. 5 is a sectional view of a scale equipped with the load converter of the present invention inside, and the display element as the scale and its remaining circuit portion are omitted. Also,
FIG. 6 is a perspective view showing the main parts of FIG. 5, and the same parts are given the same reference numerals. In FIG. 5, reference numeral 1 denotes an upper tray, which has a four-part shape to prevent the placed object to be measured from falling outside. Reference numeral 2 denotes a load receiving plate, which is connected to the upper plate 1 by a claw portion at the bottom of the upper plate 1. This load-receiving plate 2 is made of a material having sufficient strength to resist the unbalanced weighing object placed on it (for example, 〇〇, h〇), and its lower end faces the stopper 8. , it is constructed so as not to transmit red flame load to the strain-generating body when an excessive load is applied.
It consists of five bodies, forming a parallelogram-shaped so-called robo-hull mechanism. The stays 3 and 4 have the same shape, both ends are bent, and a beam 5.6 is connected to the ends with screws. 4 is attached to a fixed end 7 which is a part of the case body. Note that the stays 3 and 4, like the load receiving plate 2, have sufficient strength to withstand the load. On the other hand, strain cages 12a, 2b serving as strain electric transducers are attached to the beam 6 with an adhesive, and their lead wires are led to the circuit board 9.

Further, IO indicates the case body, and 11 indicates rubber feet. In addition, misalignment of the joints between the stays 3 and 4 and the beams 5 and 6, and between the stays 3 and 4 and the load receiving plate 2 and fixed end 7 will cause errors and hysteresis in the load converter. , must be connected without any deviation.

FIG. 7 shows a small block diagram of the configuration of the circuit section, which performs everything from detecting strain to displaying weight values. In FIG. 7, D is a bridge circuit, the two sides of which include the aforementioned strain gauges 12a and 12b, and AC voltage for measurement is supplied from the bridge power supply A via the balance adjustment circuit B to both ends of the bridge. is given. In addition, strain gauge 1.2a
, 1.2b are desirably bonded to the front and back sides of the beam, respectively, as shown in FIG. 8, in order to perform temperature compensation. Similarly, 4
It is also possible to use separate strain cages, and the layout in that case is shown in Figure 9 (A) and Figure 10 (A), and the wiring of the bridge circuit in that case is shown in Figure 9 (Ro). ) and are shown in FIG. 10(b), respectively. Note that the strain gauges are provided on both sides of the beam in order to offset the eccentricity error in the Y direction in FIG. 6. Returning to FIG. 7 and explaining the other configuration, the deviation output of the bridge circuit is the amplifier E1 phase separator F, V
O change JiA device G1 calculation/processing circuit H1 display circuit I to l1
It is connected to the display element J via the ll'i. In addition,
The phase separator F reproduces a distortion signal from the output voltage of the bridge which is amplitude modulated by the distortion signal, taking into account the sign of the distortion.

Next, to explain the operation of the above-mentioned scale as a whole, the load of the object placed on the top 1111 is transmitted from the top plate 1 to the load receiving plate 2 to the stay 3, and the beam 5.6 is deflected. Strain occurs on the beam surface in proportion to the load. This distortion is caused by strain cages 12 provided on the front and back sides of the beam 6, respectively.
a, 12b causes a change in VC resistance and generates a deviation voltage in the bridge circuit with an amplitude proportional to the load. This deviation voltage is amplified to an appropriate level by an amplifier E, and then converted by a phase separator F into a DC signal representing distortion. That is, since an in-phase or inverted amplitude modulated signal is output from the bridge circuit depending on whether the distortion is positive or negative, the phase separator F takes this phase into consideration when reproducing the distorted signal. The A/D converter G converts the distortion signal, which is an analog signal, into an r sotal signal, and the subsequent calculation and processing circuit H outputs the corresponding weight value a, which is then sent to the display element J via the display circuitry. Displays the weight value. In addition, as for the peeling, the error caused by the place where the upper plate l is placed, that is, the eccentricity error is a problem, but
The eccentricity error is absorbed by the robal pal mechanism, and in the Y direction perpendicular to it, since distortion cannons are placed on both sides of the beam, it is averaged and does not affect the output.

As described above, the present invention includes a strain-generating body that constitutes a donkey pal mechanism with a pair of beams and a pair of stays,
In a load transducer that measures the load by applying a load of an object to be measured to the strain body having one end fixed, and detecting the strain generated on the surface of the strain body using a strain gauge, the strain gauge is attached to the beam. A tapered narrow part is provided in the part to maximize and uniformly generate strain at the bonded part of the strain cane.
The present invention provides a load transducer with a simple configuration and high stiffness, which can improve the detection accuracy of the wire, eliminate the influence of the pure lead terminal processing section, and reduce the concentrated load on the flexure element fixing section. can.

[Brief explanation of the drawing]

1st I! ￥l and Figure 2 are conventional strain body structure diagrams,
3 and 4 are explanatory diagrams of the present invention, and FIGS. 5 to 10.
The figure shows the configuration of a scale to which the load converter of the present invention is applied. 1... Upper plate, 2...-load receiver + L3, 4... stay, 5, 6-... beam, 7... fixed fa, 12a,
12b - Strain gauge. Applicant Matsushita Electric Works Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 7 Figure 9 Procedure? ■Authentic (spontaneous) January 13, 1980 Patent Agency Director-General Kazuo Wakasugi 1, Indication of the case 1983 Patent Application No. 178837 2, Name of the invention Load converter 3, Case of the person making the amendment Relationship with Patent applicant name (583) Matsushita Electric Works Co., Ltd. 4, Agent
Person: 160 Address: 7th Floor, 2nd Mizota Building, 7-10-13 Nishi-Shinjuku, Shinjuku-ku, Tokyo Telephone (031365-1982-17＼゛Pa) Error 5, subject of amendment (1) Clear 1 letter `` "Brief explanation of the drawing" column (2)
Drawing 6, contents of correction (1) As shown in the attached sheet (2) Figures 1 to 4 will be corrected as shown in the attached sheet. 1. In the description, page 10, line 7 to line 8, it says "Fig. 1 to explanatory drawing". Figure (a) is a plan view, and (a) is also a plan view.
(b) is a front view, (c) is a diagram showing the distribution of strain on the beam, and FIGS. 3 and 4 show the beam shape before implementation of the present invention and the beam shape of the present invention. (a) is a plan view, (b) is a front view, and (c) is a diagram showing the distribution of strain on the beam. Figure 1 (c) Figure 2 (c) Figure 3 (b) a Figure 4 (a) (b) (c)

Claims (1)

[Claims] A strain-generating body is provided with a pair of beams and a pair of nuts to form a white bar pal mechanism, and when the load of a mass to be covered is applied to the rail strain-generating body with one end fixed, the strain generated on the surface of the strain-generating body is In a load transducer that measures the load by detecting it with a strain sensor, a small A-shaped pinched part is provided at the strain gauge mounting part of the curved beam to maximize and uniformly generate strain at the bonded part of the strain gauge. A load converter characterized by: