Weighing scales – Self-positioning – Spring
Patent
1992-12-07
1994-11-15
Miller, Jr., George H.
Weighing scales
Self-positioning
Spring
177 16, 73862627, G01G 308, G01G 1114, G01L 122
Patent
active
053650220
DESCRIPTION:
BRIEF SUMMARY
The measurement of linear or two-dimensional loads by means of modern electromechanical dynamometric devices involves special problems. If a single load cell is used for a platform type scale, which by its nature has only a single point of load or force input, then limitations arise with respect to the size of the platform, due to the existence of the so-called angular load error. This also applies in a similar manner with respect to linear measuring devices, such as overhead rail scales. Consequently, numerous dynamometric cells are used for large, high-capacity platforms and long overhead rail gauge lengths, usually three to four cells for platforms, and two cells for overhead rail gauge lengths. Since under current conditions the use of four dynamometric cells is not economical until platform sizes of approximately 2.times.2 meters or greater for large-capacity scales are involved (with the same applying for overhead rail scales), an area size becomes involved at which platform scales become either too imprecise or too expensive. In the case of smaller high-capacity scales, there is still an option of stiffening metrologically vital components, although this can basically only be achieved through taller design configurations.
The goal of the invention described herein is to create a load cell which favorably allows the simple and economic and construction of larger and lower platform scales and longer overhead rail gauge lengths.
The solution to the problem described is set forth in patent claim 1. The concept of the invention is explained through numerous design variants shown in the attached drawings:
FIG. 1=An initial example of a load cell built into a platform scale.
FIG. 2=A cross-section through the design variant shown in FIG. 1.
FIG. 3a=A second design variant of a load cell with a welded section.
FIG. 3B=a perspective view of the design variant shown in FIG. 3 used as a hanging scale.
FIG. 4=A third design variant of a load cell with an extruded section.
FIG. 5=A fourth design variant of a load cell with an extruded section.
FIG. 6=A fifth design variant of a load cell with an extruded section.
FIG. 7a, b=A sixth design variant of a load cell with a bolted section.
FIG. 8=A seventh design variant of a load cell with a bolted section.
FIG. 9=An eight design variant of a load cell with an extruded section, installed in a conveyor belt scale.
FIG. 10=A ninth design variant of a load cell with a pressed section.
FIG. 1 shows the perspective of a partially cutaway view of a portion of a platform scale containing the initial design variant of a load cell as described herein. FIG. 2 shows a cross-section of the same arrangement.
A longitudinal guide section 1, consisting of a rod-shaped frame 6, a rod-shaped load-bearing element 7, and two rod-shaped plates 8 with band-shaped flexural joints, extending across the overall length of guide section 1, rest, with frame 6, on two feet 2, which are attached to the outermost exterior of frame 6. Two elbowed mounting elements 3 are attached to load-bearing element 7 at the same longitudinal position as the feet, and support a platform 5 on one side of each of the mounting elements. There is an identical load cell on the other side of platform 5 (not shown), located in axial symmetry to the first load cell.
The longitudinal extension of guide section 1 is such as to amount to a multiple of its lateral dimension.
A force sensor 4 is located in a diagonal position at half the length of guide section 1. If platform 5 is loaded by the weight of a mass 10, then the force flow is distributed in accordance with the elasticity of flexural joints 9 and that of force sensor 4, modified by the angular position of force sensor 4. Thus, what is involved is a reduction in the elasticity of flexural joints 9 and the inherent or installed elasticity of force sensor 4. The type of force sensor 4 involved can be all currently known types, such as strain gauges, and piezoelectric, optoelastic, and string sensors.
Due to the high rigidity of plate 8 of frame 6 and of load-bearing
REFERENCES:
patent: 4655306 (1987-04-01), Saner
patent: 4682664 (1987-07-01), Kemp
Miller Jr. George H.
Wirth Gallo Messtechnik AG
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