JPS6239928B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a load transducer that electrically measures the magnitude of a load applied to a beam using a strain gauge.

FIGS. 1A and 1B show the configuration of an example of a conventional parallelogram type (parallel beam type) load converter.

In FIGS. 1A and B, 1 is a beam of a load converter, which is a rectangular plate-shaped member with an appropriate thickness, and is arranged along the longitudinal direction of the plate-like member and has two circles penetrating it in a direction perpendicular to this. The beam 1 is formed by forming holes 1a and 1b and communicating them by cutting them apart (for example, by slotting).In other words, the beam 1 is made up of a pair of rigid body parts facing each other with an appropriate interval between them. 11, 12 and these rigid body parts 1
1 and 12 (parts in which the round holes 1a and 1b are formed are particularly thin), strain-generating beam parts 13 and 14 that are parallel to each other and have the same length are deformed by a load and function as strain-generating parts. The respective ends are integrally connected to each other. The round holes 1a and 1 of the strain-generating beams 13 and 14 of this beam 1
Strain gauges S are installed on the upper and lower surfaces corresponding to b.
1, S2, S3, and S4 are attached. These strain gauges S1 to S4 are bridge-connected as shown in FIG. In the beam 1 configured in this way, the rigid body part 11 is fixedly supported by the fixed part 2 of the load converter main body, and the load introduction part 15 provided on the rigid body part 12 at the other end is connected to the rigid body part 11 in the direction along the rigid body part 12. When a load W is applied, it deforms as shown exaggeratedly with a chain line in FIG. 1B, and an electrical signal corresponding to the applied load is obtained. And this parallelogram type converter is
Since it has the feature that the load detection output is not affected even if the load application position (load point) shifts to a certain extent, it is often applied to dish scales and the like.

However, as mentioned above, in a load converter that fixes one end of a parallelogram-shaped beam and applies a load to the other end, when the beam 1 is deflected by the load, the load point moves outward by a distance. Particularly, when a diaphragm is attached to beam 1 to prevent lateral loads and prevent moisture absorption of strain gauges, the movement of the load point causes a tensile force to act on the diaphragm, which causes the diaphragm to move by 1. This was a factor that affected the deflection characteristics and inhibited the linearity of the load-output characteristics of the strain gauge.

The present invention was developed in view of these circumstances, and has a simple structure that does not cause lateral movement of the load point, and does not generate beam tension, even if a diaphragm is installed to prevent lateral loads. The purpose is to provide a load converter that is not affected by the diaphragm and has good linearity in load-output characteristics.

That is, in order to achieve the above object, the present invention has two holes that communicate with each other along the longitudinal direction and penetrate in a direction perpendicular to the longitudinal direction, and strain gauges are attached to the surface corresponding to these holes. It has one or two or more pairs of two beams, and the beams forming the pair are arranged parallel to each other, and the ends of the beams forming the pair are integrally formed or firmly formed. The present invention is characterized in that the other end of one of the paired beams is fixed, and the other end of the other beam is left free to provide a load converter.

Embodiments of the present invention will be described below with reference to the drawings.

3A and 3B are a plan view and a front view, respectively, showing the configuration of the first embodiment of the present invention. In the same figure, 3 and 4 are a pair of first and second beams, respectively, similar to the beams in the conventional load converter shown in FIG.
Round holes 3a, 3b, and 4 are arranged along the longitudinal direction of a rectangular plate-like member having an appropriate thickness and penetrated in a direction perpendicular to the longitudinal direction (lateral direction).
a, 4b are formed, and these are connected by cutting and machining, and the wall thickness is thinner than the pair of rigid body parts 31, 32 and 41, 42 facing each other with an appropriate interval (round holes 3a, 3b and The strain-generating beam parts 33, 34 and 43, 44, which are parallel to each other and have the same length and which function as strain-generating parts by being deformed by a load, are mutually connected at each end. It has a configuration in which it is integrally combined with the . These first beam 3 and second beam 4 are arranged parallel to each other in a plane perpendicular to the load direction, and their one ends are integrally formed or welded together via a connecting part 5. , firmly connected by means such as screws. The other end of the first beam 3 is fixed to a fixed part (for example, a case) 6 of the load converter, and the other end of the second beam 4 is free and provided with a load introduction part 45. There is. Further, eight sheets are formed on the upper and lower surfaces of the first beams 3 and 4 corresponding to the round holes 3a, 3b and 4a, 4b of the strain beams 33, 34 (not shown in the figure) and 43, 44, respectively. Strain gauges S5, S6, S7, S8, S9, S10,
S11 and S12 are attached by adhesive, fusion, or other means.

FIG. 4 is a circuit diagram showing an example of strain gauge connection in the embodiment shown in FIG. Input ei is supplied from a bridge power supply between opposing connection parts a and b of the strain gauges that make up the circuit, and output eo is taken out from the other connection parts c and d.
Incidentally, the circuit using the strain gauges may be configured such that a single Wheatstone bridge circuit is formed by four strain gauges.

Next, the operation of the embodiment shown in FIGS. 3A and 3B will be explained.

When the measurement load W is applied to the load introduction part 45, the third
As shown exaggeratedly with chain lines in FIG.
4a and 4b are bent and bent, and the free end portion (left end in the figure) of the second beam 4 having the load introducing portion 45 is greatly lowered downward, and the supporting end of the second beam 4 is bent. The free end (right end in the figure) of the first beam 3 as shown in FIG.
The free end of the second beam 4 will therefore be lowered approximately twice as much as the free end of the first beam 3. At this time, the free end of the second beam 4 moves by a horizontal distance l in the direction of its supporting end (in the direction of the free end of the first beam 3), but at the same time, the free end of the first beam 3 also moves from its fixed position. Since the second beam 4 moves by a horizontal distance l in the direction of the section 6, the free end of the second beam 4, that is, the position of the load introducing section 45 does not move at all in the horizontal direction. For example, even if the load introduction part 45 of the second beam 4 is connected to the center of a diaphragm (not shown) for preventing lateral loads and the second beam 4 is restrained from moving in the lateral direction, there is no problem. This means that there is no problem, and unlike conventional parallelogram-shaped beams of this type, even when the diaphragm is attached to the second beam 4, it is not possible to apply a lateral tensile force to the diaphragm. In other words, since the reaction force of the diaphragm is not applied, the deflection characteristics of the first beam 3 and the second beam 4 are not affected at all, and the linearity of the load-output characteristics by the strain gauge becomes good.

Moreover, each rigid body part 31 and 32 of both beams 3 and 4
between 41 and 42 and each strain-generating beam section 32 and 3
4, 43 and 44 have the advantage that even if deflection occurs due to the measurement load w, the parallel relationship is always maintained, so even if the load point shifts to some extent, the load detection output is not affected and therefore no measurement error occurs. be.

In this way, when both beams 3 and 4 are bent due to the application of the measurement load W, they are attached to the surface portions corresponding to the holes 3a, 3b and 4a, 4b of the strain-generating beam portions 33, 34 and 43, 44, respectively. Strain (deformation) also occurs in the strain gauges S5 to S12, and an electrical output corresponding to the strain can be obtained. That is, if both beams 3 and 4 are bent as shown in FIG. 3B, the strain gauges S5 and S
8, S10, and S11, and compressive strain occurs in strain gauges S6, S7, S9, and S12. As shown in Figure 4, the strain gauge is
Strain gauges S5, S8, S10, S11 that generate tensile strain due to measurement load W and strain gauges S6, S7, S9, S12 that generate compressive strain are connected adjacently to form a double Wheatstone bridge circuit. Therefore, by supplying the input ei between the opposing connections a and b that make up this Wheatstone bridge circuit, it is possible to extract the output eo that corresponds only to the load W from the other connections c and d. .

FIG. 5 is a plan view showing the configuration of a second embodiment of the present invention. This second embodiment is shown in FIG.
The beams 3 and 4 in the first embodiment shown in B are
Two pairs of beams are arranged symmetrically with respect to the dashed-dotted line _L1 shown in Fig. 5, and the fixed ends and free ends of the two pairs of beams are integrally molded or firmly connected. It is. In the same figure, the left half and right half of the dashed-dotted line _L1 are the same as the embodiments shown in FIGS. The explanation will be omitted.

Furthermore, since the operation of the second embodiment is the same as that of the first embodiment, the explanation thereof will be omitted, but the amount of deflection of each beam for the same measurement load W is different from that of the first embodiment. The difference is that it becomes 1/2.

In addition, the present invention can be modified in various ways without departing from the gist thereof.

For example, as shown in the third embodiment in FIG. 6, two pairs of beams are arranged symmetrically with respect to the dashed line _L2 , and their free ends are formed integrally or firmly. It is also possible to have a structure in which they are connected and each fixed end is separately fixed to a fixed part at a different position.

Furthermore, as shown in FIG. 7 as a fourth embodiment, four pairs of _the two beams shown in FIG. It is also possible to have a structure in which the ends are integrally molded or firmly connected, and fixed ends of every two pairs (each upper half and lower half of the dashed-dotted line L ₄ ) are integrally molded or firmly connected.

In addition, as shown in FIG. 8 as a fifth embodiment, 1
A pair of beams 3 and 4 are arranged in two stages so as to be parallel to each other in the load direction, and one ends of these beams 3 and 4 are integrally formed or firmly connected, and the other end of one beam 3 is It is also possible to have a structure in which the other end of the other beam 4 is left free and a load introduction part is provided while the other end of the other beam 4 is fixed.

In addition, holes 3a, 3b, 4 formed in each beam
Although a and 4b show examples of round holes, they may also be elliptical holes or square holes, and the slit width of the slit-shaped hole connecting these holes is made equal to the diameter of the round hole, It may be substantially one oblong hole,
Alternatively, one hole may be formed by forming four round holes, two each in the longitudinal direction of the beam and in a direction perpendicular thereto, so as to partially overlap each other.

Further, in the above embodiment, the strain gauges are attached to both the upper and lower surfaces of the strain-generating beam portion of each beam, but they may be attached only to either the upper surface or the lower surface.

As described in detail above, according to the present invention, the configuration is simple, the load point does not move in the lateral direction, and no tensile force is generated in the beam, and even if a diaphragm is installed to prevent lateral loads, the diaphragm It is possible to provide a load converter that is not affected by the load and has good linearity of load-output characteristics.

[Brief explanation of the drawing]

Figures 1A and B are a plan view and a front view, respectively, showing the configuration of an example of a conventional parallelogram-type load transducer, Figure 2 is a wiring diagram of a strain gauge bridge in the same example, and Figures 3A and B are A plan view and a front view showing the configuration of the first embodiment of the present invention, and a fourth
The figure is a wiring diagram of the strain gauge bridge in the same embodiment, and FIGS. 5, 6, and 7 show the configurations of the second, third, and fourth embodiments of the present invention, respectively. The plan view and FIG. 8 are front views showing the configuration of a fifth embodiment of the present invention. 3...first beam, 3a, 3b, 4a, 4b
... Round hole, 31, 32, 41, 42 ... Rigid body part,
33, 34, 43, 44... strain beam section, 4...
...Second beam, 45...Load introduction part, 5...Connection part, 6...Fixing part, S5-S12...Strain gauge.

Claims (1)

[Claims] 1. A pair of beams having two holes communicating with each other along the longitudinal direction and penetrating in a direction perpendicular to the longitudinal direction, and having strain gauges attached to the surfaces corresponding to these holes. one or more pairs of beams, the pairs of beams are arranged parallel to each other, and the ends of the beams of the pairs are integrally molded or firmly connected to each other, and the beams forming the pair are A load converter characterized in that the other end of one of the beams is fixed, and the other end of the other beam is free to provide a load introducing section. 2. The load transducer according to claim 1, characterized in that two pairs of beams are integrally formed or firmly connected at fixed ends and free ends. 3. Claim 1, characterized in that two pairs of beams are formed with their respective free ends integrally formed or firmly connected, and each fixed end is separately fixed to a fixed part.
Load transducer as described in section. 4. Claim 1, characterized in that the free ends of four pairs of beams are integrally molded or firmly connected, and the fixed ends of every two pairs are integrally molded or firmly connected. Load transducer as described in section.