JPS6259768B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protection device for a load cell in a measuring instrument.

In weighing instruments, such as digital fare scales, a load cell is used as a means of sensing the weight of the item placed on the weighing plate, and a strain gauge is attached to the part that deforms when a load is applied. The applied load, or weight, is measured by electrically detecting the strain on this object, but the attached strain gauge has a load limit, and if a load is applied beyond this limit, I'll break it. In order to prevent this breakage, various stoppers are generally provided to prevent the movable part of the load cell from being displaced beyond a predetermined value.

On the other hand, if the load cell is displaced in the opposite direction from when weight is applied to the load cell due to impact or vibration during transportation when such a scale is not used, or impact or vibration due to an unexpected accident during use. There is. If this displacement is small, there is no problem, but if it is large enough to exceed the load limit, measures must be taken to prevent this. As a means for this, for example, a stopper is used, but even this may cause the strain gauge to break depending on the magnitude of the impact. This is especially the case when transporting scales. One way to deal with this is to lock the load cell itself, but there are various problems with load cells that have a small amount of absolute deformation or deflection, and it is common that such locking means are not provided. is the actual situation.

However, for relatively large load cells, there are examples of locking means as shown in FIGS. 1 to 3.

FIG. 1 is a side view of a so-called square load cell, and near the corners of the inner circumference of the frame 1 constituting the Roberval mechanism, there are approximately semicircular notches 1a, 1b,
1c and 1d are formed, and strain gauges (not shown) are attached on the corresponding outer peripheral surfaces. The left side view of the frame 1 shows that it is fixed to a stationary part 2, and the weight transmission member 3 is fixed to the right side part. The weight transmitting member 3 is directly connected to a placing plate (not shown), and when an item is placed on the placing plate, the frame 1 receives a load on its right side through the weight transmitting member 3 and bends in the direction shown by the arrow. The figure shows the locked state of such a load cell, and this lock is released when it is used.

That is, a locking means 4 is provided on the right side of the load cell frame 1, and this mainly consists of a rod holding section 5 fixed to the stationary section 2, and a rod holding section 5 that is rotatably held relative to the rod holding section 5. 6. A spring support 9 fixed to the lower end of the rod 6, a spring 10 stretched between the pin 9a attached to one end of the spring support 9 and the stationary part 2, and a stopper pin 11 integrally fixed to the rod 6. , a pin engaging member 12.

The rod 6 is rotatably supported by the U-shaped holding part 5 by E-rings 7 and 8, but when the scale is not in use, the stopper pin 11 is engaged with the pin engaging member 12 by the biasing force of the spring 10. It is pressed against the end of the matching groove 12a as shown in FIG. The stopper pin 11 is also in close contact with the upper and lower walls of the engagement member 12, so that vertical movement of the frame 1 is restricted via the pin engagement member 12. When using the scale, if the rod 6 is rotated counterclockwise in Fig. 2 against the biasing force of the spring 10, it will be stopped at a position of approximately 90 degrees by the action of the spring 10, and the lock will be released. be done. That is, the stopper pin 11 is completely removed from the engagement groove 12a of the pin engagement member 12. Thereby, the frame 1 can be freely displaced in the vertical direction. Although not shown, it is assumed that a stopper for the maximum allowable load is provided at an appropriate location.

The above-mentioned locking means 4 prevents shock during transportation,
Although it prevents breakage due to vibration, it has a large number of components and can be configured for large displacements such as relatively large rectangular load cells, but it is difficult to configure for small load cells. This makes manufacturing and assembly difficult. In particular, if the dimensional accuracy of the groove 12a of the engaging member 12 or the alignment accuracy between the stopper pin 11 and the groove 12a is poor, a static load will be applied to the frame 1 in the locked state.
There is a risk that the materials of the frame 1 and the load cell may creep. In some cases, vibrations and shocks may be applied repeatedly to this, and the material of the load cell may become fatigued.

The present invention has been made in view of the above points, and an object of the present invention is to provide a reliable load cell protection device. According to the present invention, in a measuring instrument equipped with a load cell as a weight sensing means, the movable part that is displaced when weight is applied to the load cell and the stationary part to which the load cell is fixed are aligned in phase. Forms screw holes of equal diameter and pitch,
A protection device for a load cell in a measuring instrument, characterized in that at least one of these screw holes is a through hole, and a common screw is screwed into both the screw holes when the measuring instrument is not in use. achieved.

Hereinafter, details of the present invention will be explained with reference to the drawings. 4 and 5 are side views of a protection device for a load cell in a scale according to a first embodiment of the present invention, with FIG. 4 showing the balance in a non-use state and FIG. 5 showing it in a use state.

In FIG. 4, approximately semicircular notches 20a, 20b, 20c, and 20d are formed near the corners of the inner peripheral surface of a so-called square load cell frame 20, and correspondingly semicircular notches 20a, 20b, 20c, and 20d are formed on the outer peripheral surface. A strain gauge is attached even though it is not shown. Frame body 20
The left side part of is fixed to the stationary part 21, and the leg part 22a of the weight transmission member 22 is fixed to the right side part. Although not shown, the weight transmitting member 22 is directly connected to the tray, and when an item is placed on the tray, the weight is transmitted to the frame 20 through this member 22, as shown in FIG. When the locking means described later is released, the frame bends downward.

The lower end of the leg 22a of the weight transmitting member 22 is bent, and a slit 22b is formed therein, through which the rod 23 passes. The rod 23 is erected on the stationary part 21, and an upper limit stopper 24 is fixed to its tip, and a lower limit stopper 25 is fixed below the bent part of the leg part 22a.

A through screw hole 2 is provided at the right end of the weight transmission member 22.
6 is formed, and a screw hole 28 is formed in the lock post 27 in alignment with this. The lock post 27 is provided upright on the stationary part 21, and its screw hole 28 and the through screw hole 26 of the weight transmission member 22 are equal in diameter and pitch. Further, a predetermined distance is provided between the lower surface of the member 22 and the upper end of the locking post 27.

The first embodiment of the present invention is constructed as described above, but when the scale is not in use, the bolt 29 is screwed into the above-mentioned screw hole 26, and the lock post 27 is screwed into the bolt 29.
It is also screwed into the screw hole 28 of and tightened to the member 22. Note that even if the member 22 is tightened with a sufficiently strong force at this time, the member 22 will not bend and no load will be applied to the load cell. Moreover, if member 2
If the screw holes 26 were not formed in the screw hole 26 but a round hole was formed in the screw hole 26, the member 22 would bend when the bolt 29 was tightened with force.

Although the locking means according to this embodiment has an extremely simple structure as described above, it is possible to integrate the movable part and the stationary part of the load cell without applying any load to the load cell, and it is possible to transport the scale. Even if vibration or impact is applied inside, no load is applied to the load cell and it is safely protected.

When using the scale, remove the bolt 29 and the fifth
As shown in the figure, if an item is placed on the tray in this state, the frame body 20 receives the load via the weight transmission member 22 and bends downward. If a load greater than the allowable load is applied, the bent portion of the leg 22a of the member 22 will come into contact with the lower limit stopper 25, preventing the frame 20 from flexing any further and protecting the load cell from tearing. .

Furthermore, even if the frame body 20 receives an upward load for some reason during use, its deflection is limited by the upper limit stopper 24, so that the load cell is still prevented from being damaged.

FIG. 6 shows a second embodiment of the present invention, and corresponding parts in FIG. 4 are given the same reference numerals.

In this embodiment, the locking post 27 is connected to the weight transmitting member 22.
The locking member 30 is secured to an extension 30a of the locking member 30, while the through screw hole 26 is formed in the extension 30a of the locking member 30. Since the lock member 30 is fixed to the stationary part 21, the through screw hole 26 is formed on the fixed side of the load cell in this embodiment, but it is necessary to screw the bolt 29 into the screw holes 26 and 28. It is clear that the same effect as in the first embodiment can be obtained.

Although the embodiments of the present invention have been described above, it is obvious that the present invention is not limited thereto, and that various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiments, the case where the present invention is applied to a scale has been described, but the present invention is not limited to this, and can be applied to any measuring instrument that uses a load cell.

Further, in the above embodiments, the case where the present invention is applied to a so-called square-shaped load cell has been described, but it can also be applied to a so-called beam-type load cell.
Further, in the above description, the load cell is limited to a strain gauge attached to a deforming part, but in the present invention, the load cell includes a spring in a spring-type scale.

As described above, the load cell protection device according to the present invention has a simple structure, can reliably lock the load cell without applying any stress to the load cell, and is extremely easy to operate.

[Brief explanation of the drawing]

Figures 1 to 3 show an example of a conventional load cell protection device. Figure 1 is a side view of the device, Figure 2 is a plan view of the main parts of the device, and Figure 3 is the same as in Figure 2. - It is a line direction cross-sectional view. FIG. 4 is a side view of the load cell protection device according to the first embodiment of the present invention when the load cell is not in use, FIG. 5 is a side view of a part of the same device when the load cell is in use, and FIG. 6 is a side view of the load cell protection device according to the first embodiment of the present invention. FIG. 7 is a side view of a part of the load cell protection device according to the second embodiment in a state where the load cell is not in use. In addition, in the figure, 20...frame body, 26...penetrating screw hole, 27...lock column, 28...screw hole,
29...Bolt, 30...Lock member.

Claims (1)

[Claims] 1. In a measuring instrument equipped with a load cell as a weight sensing means, screw holes of equal diameter and pitch are formed to align with the movable part that is displaced when weight is applied to the load cell and the stationary part that fixes the load cell. A protection device for a load cell in a measuring instrument, characterized in that at least one of these screw holes is a through hole, and a common screw is screwed into both the screw holes when the measuring instrument is not in use.