JPH09236478A - Load cell type platform scale - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load cell type platform scale wherein, with the structure where a load is transmitted to a load cell by way of a connection rod provided in extended manner vertically, measurement accuracy of a scale does not degrade even when environment temperature changes. SOLUTION: In this scale, a load stage 11 is held with a Roberval part 10, a load cell 7 is contained in an indicator 3 assigned diagonally above the load stage 11, a load transmission mechanism 15 which transmits a load W from the load stage 11 to a movable part 7b of the load cell 7 is provided, and, the load transmission mechanism 15 complies a loaded point lever 16 provided in extended manner, horizontally, from the load stage 11 and a connection rod 17 which is, provided in the vertical direction in extended manner, connected to the movable part 7b of the load cell 7 at its upper end part and is engaged with the loaded point lever 16 at its lower end part, and a supporting cylinder- like body 8 which supports the indicator 3 and the connection rod 17 are made of the same material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load cell type balance suitable for use in a bad environment or flammable atmosphere.

[0002]

2. Description of the Related Art In a platform scale in which a load to be measured is loaded on a load platform, one using a load cell in which a strain gauge is attached to a flexure element is known. In this type of platform scale, generally, the load cell is arranged below the load platform, and the load cell directly receives the load of the load platform. In addition, an indicator that operates and displays the platform is provided on the platform where the load platform is located near the floor surface.The indicator is suitable for operation and display for personnel such as staff. , For example, is arranged at eye level, and is arranged apart from the load base.

By the way, since the articles to be measured are loaded and unloaded on the load platform, dust and dust will increase under the load platform on which the load cell is arranged, and a part of the liquid stored in the article. However, the load cell is liable to become an adverse environment, and conventionally, the load cell is covered with a metal foil or the like in a sealed state to improve the environmental resistance. Further, in a platform scale used in a flammable atmosphere, a load cell is arranged in an explosion-proof pressure-resistant container to impart an explosion-proof function.

However, as described above, when the load cell is covered with metal foil or the like in a sealed state,
There is a problem that the manufacturing cost is increased due to the closed structure. Further, in a platform scale having an explosion-proof function, electric parts are also incorporated in the indicator, and while this indicator part is also arranged in the explosion-proof pressure-resistant container,
Since an explosion-proof pressure-resistant container for disposing the load cell is additionally required, a plurality of explosion-proof pressure-resistant containers are required, which causes a problem that the manufacturing cost increases accordingly.

As a platform for dealing with these problems,
The one as shown in FIG. 2 can be proposed. In FIG. 2, 1 is a platform scale, 2 is a base of the platform scale 1, and 3 is an indicator having a function of operating and displaying the platform scale 1. A box-shaped explosion-proof pressure-resistant container 4 forming the housing of the indicator 3 is equipped with various electric parts (not shown), and a strain gauge 5 is attached to a strain element 5 having four thin portions. It also has a built-in load cell 7 attached. The indicator 3 is fixed to an upper part of the platform scale 1 via a support tubular body 8 having a rectangular tubular shape as a support member provided upright on the base 2.
Further, the fixing portion 7a side of the load cell 7 is fixed on the bottom surface portion 4a of the pressure resistant container 4 via the first bracket 9.

At the lower part of the platform scale 1, a load platform 11 supported by a Roberval section 10 having four thin-walled sections is supported in a vertically movable posture. That is, the fixed portion 10a side of the Roberval portion 10 is fixed via the second bracket 12 fixed on the base 2, and the Roberval portion 10 is fixed.
The support portion 11a of the load platform 11 is attached to the upper surface side of the movable portion 10b.

Between the load table 11 and the load cell 7, the load W from the load table 11 is applied to the movable part 7 of the load cell 7.
A load transmission mechanism 15 that transmits to b is provided. The load transmission mechanism 15 includes a force point lever 16 that extends rearward (to the left in the plane of the drawing in FIG. 2) from the support portion 11a of the load base 11 and that projects into the inside of the tubular body 8. And a connecting rod 17 which is connected to the movable portion 7b of the load cell 7 at a portion thereof and which is engaged with the power point lever 16 at a lower end portion thereof through a mounting screw 18.

A through hole 4b is formed in the bottom surface 4a of the pressure resistant container 4, and the connecting rod 17 penetrates through the through hole 4b.
Are arranged in a non-contact state. Then, the clearance between the connecting rod 17 and the through hole 4b is set to a predetermined dimension or less, and the distance at which this clearance is formed, that is, the thickness of the bottom surface portion 4a is set to a predetermined dimension or more, and by any chance, inside the pressure vessel 4. Even if the electric component is ignited due to heat generation or a short-circuit accident, the explosion energy is stopped inside the pressure resistant container 4 so that flame escape to the outside of the pressure resistant container 4 does not occur.

If such a structure is adopted, since the load cell 7 is also arranged in the explosion-proof pressure-resistant container 4 in which the indicator 3 is arranged, only one explosion-proof pressure-resistant container 4 is required, and the manufacturing cost is reduced. Can be reduced.

Further, since the frame body of the indicator 3 does not have an explosion-proof structure, it can be used as a general platform scale, and according to this, since the load cell 7 can be arranged in a relatively environmentally friendly place, dust etc. It is not necessary to employ a closed structure for preventing the intrusion of the, and this can also reduce the manufacturing cost.

[0011]

However, such a load cell type platform scale has a structure in which the load W is transmitted to the load cell 7 by the long connecting rod 17 and the load platform 11 is held by the roberval section 10. The connecting rod 17 expands and contracts according to the change in the environmental temperature, and the force due to the expansion and contraction of the connecting rod 17 due to the temperature change is added to the load cell 7, which may deteriorate the measurement accuracy of the scale.

The present invention solves the above-mentioned problems, and has a structure in which a load is transmitted to a load cell through connecting rods extending vertically, but the measurement accuracy of the scale deteriorates according to changes in environmental temperature. The purpose of the present invention is to provide a load-cell type platform scale that does not require the operation.

[0013]

In order to solve the above-mentioned problems, the present invention provides a load base on which a load to be measured is loaded, a fixed side of which is fixed to a base and a load base is attached to its movable side. The load bar is supported by the Roberval part that holds the load platform in a vertically movable posture and the strain gauge is attached to the strain body, and the support member that extends upward or downward from the base. A load cell type balance having a load cell whose fixed portion side is supported at a location distant from the load cell, and a load transmission mechanism for transmitting a load from a load platform to the movable portion of the load cell, wherein the load transmission mechanism is a load Consists of a force point lever extending laterally from the table and a connecting rod extending in the up and down direction and connected to the movable part of the load cell at one end and engaged with the force point lever at the other end. The above It is made to constitute the connecting rod and the support member of the same material.

According to this structure, since the support member and the connecting rod are made of the same material, the support member and the connecting rod expand and contract similarly with respect to the ambient temperature, and the expansion and contraction due to the temperature change of the connecting rod. It is possible to prevent the resulting force from being applied to the load cell.

Further, the supporting member is formed of a supporting cylindrical body whose axial center extends along the up-down direction, and the connecting rod is inserted and arranged in the supporting cylindrical body to support the supporting member. By forming the ventilation hole in the cylindrical body, outside air is introduced well into the inside of the supporting cylindrical body through the ventilation hole, and even if the environmental temperature changes, the temperature of the connecting rod is almost equal to the temperature of the supporting cylindrical body. It becomes equal, and it is possible to prevent the force due to the expansion and contraction due to the temperature change of the connecting rod from being applied to the load cell.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The same functions as those of the load cell type platform scale shown in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 1, it is extended vertically.
A support for supporting the connecting rod 17 connected to the movable portion 7b of the load cell 7 at the upper end and engaged with the power point lever 16 at the lower end, and the pressure resistant container 4 of the indicator 3 having the load cell 7 built therein. With the support tubular body 8 as a member,
The lengths are substantially the same in the vertical direction and are made of the same material, for example, iron. Further, a plurality of ventilation holes 8a are formed in a part of the support tubular body 8.

According to this structure, since the supporting tubular body 8 and the connecting rod 17 are made of the same material, their expansion coefficients are also the same, and the supporting tubular body 8 and the connecting rod 17 with respect to the ambient temperature. It is possible to prevent the force due to the expansion and contraction due to the temperature change of the connecting rod 17 from being applied to the load cell 7 by expanding and contracting similarly. Further, a ventilation hole 8a is formed in the support tubular body 8, and outside air is passed through the ventilation hole 8a.
The temperature of the connecting rod 17 becomes substantially equal to the temperature of the supporting tubular body 8 even if the environmental temperature changes rapidly, and the force due to the expansion and contraction of the connecting rod 17 due to the temperature change is introduced. Can be prevented from being added to the load cell 7.

In the above embodiment, the case where the support cylindrical body 8 and the connecting rod 17 are made of the same material has been described, but other members, for example, the bottom surface portion 4 of the pressure vessel 4 is described.
It is needless to say that a and the like may be made of the same material such as iron, or may be the same material, and may be a material other than iron. Further, in the above-described embodiment, the ventilation hole 8
Although the case where a is provided on the back side of the support tubular body 8 is illustrated,
The present invention is not limited to this, and the vent hole 8a may be provided at a position close to the connecting rod 17, for example, on the front surface side of the support tubular body 8.

[0020]

As described above, according to the present invention, since the support cylindrical body and the connecting rod are made of the same material, it is possible to prevent the force due to the expansion and contraction due to the temperature change of the connecting rod from being applied to the load cell. it can. In addition, since the support cylindrical body is formed with a vent hole and the outside air is satisfactorily introduced into the inside of the support cylindrical body through the vent hole, even if the environmental temperature changes suddenly, the temperature change of the connecting rod It is possible to prevent a force due to expansion and contraction from being applied to the load cell. As a result, it is possible to prevent the measurement accuracy of the balance from deteriorating due to temperature changes, and it is possible to maintain good measurement accuracy.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view of a pressure and explosion proof load cell type platform scale according to an embodiment of the present invention.

FIG. 2 is a partially cutaway side view of a conventional load cell type platform scale.

[Explanation of symbols]

 1 scale 2 base 3 indicator 4 pressure vessel 7 load cell 7b, 10b movable part 8 supporting tubular body (supporting member) 8a vent hole 10 roberval part 11 load base 15 load transfer mechanism 16 force lever 17 connecting rod

Claims (2)

[Claims] 1. A load platform on which a load to be measured is loaded,
The fixed side is fixed to the base, the load side is attached to the movable side, the Roberval part that holds the load stand in a vertically movable posture, and the strain gauge is attached to the strain body, and the base is attached. A load cell whose fixed portion side is supported at a location away from the load platform by a support member extending along a more upward or downward direction, and a load transmission mechanism for transmitting a load from the load platform to a movable portion of the load cell. A load cell type platform scale having a load transmission mechanism,
With a force point lever extending laterally from the load platform, and a connecting rod extending in the vertical direction, which is connected to the movable part of the load cell at one end and engaged with the force point lever at the other end. A load cell type scale comprising the supporting member and the connecting rod made of the same material. 2. The support member is formed of a support tubular body whose axial center extends along the up-down direction, and a connecting rod is inserted and arranged in the support tubular body. The load cell platform scale according to claim 1, wherein a vent hole is formed in the body to introduce outside air into the body to bring the temperature of the connecting rod close to the temperature of the supporting cylindrical body.