Weigh-In-Motion System With External Tension Load Cells
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Solution Overview
Problem
Current vehicle weighing systems face challenges in achieving accurate measurements of heavy loads due to moment-induced inaccuracies, complex and costly installation processes, and maintenance difficulties, particularly when weighing individual axles or large vehicles.
Innovation Solution
A weighing system with a base and a platform structure, featuring pivotable load cell assemblies positioned outwardly from the platform, which generates signals based on tension forces and stabilizes quickly to provide accurate and efficient weight measurements, allowing for prefabricated and easily installable axle scales with reduced maintenance requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If load cells are positioned underneath the active section to support the platform, then the scale can measure compression forces from vehicle weight, but moment forces are generated when tires roll onto the platform causing forward and downward movement that reduces measurement accuracy
Solution Approach 1:
The load cells are inverted from their conventional position underneath the platform to an external position where they measure tension forces in the linkages rather than compression forces directly on the platform. This inversion eliminates the moment-induced platform movement because the load cells are positioned outside the active section and measure forces in the linkages connecting the platform to the foundation, rather than supporting the platform directly and being subjected to moment forces from tire rolling.
2Stability of the object's composition
If the platform is designed to abut against a stop to arrest forward and downward movement, then measurement stability is improved, but the time required for stabilization increases reducing productivity
Solution Approach 1:
The measurement system is inverted from measuring platform position directly to measuring tension forces in the linkages. By positioning load cells externally to measure linkage forces, the system eliminates the need for a stop mechanism and allows continuous measurement during platform movement, thereby improving weighing speed while maintaining measurement stability through force-based rather than position-based measurement.
3Ease of manufacture
If load cells are positioned inside the active section, then installation is simpler, but maintenance requires removal of the active section and decoupling of load cells which is complex and time-consuming
Solution Approach 1:
The load cells are extracted from within the active section and positioned externally where they measure tension forces in the linkages. This extraction allows the load cells to be independently accessible for maintenance without requiring removal of the active section or decoupling from the platform structure. The load cells can be easily replaced or serviced by accessing them at their external mounting locations while the scale remains operational.
4Measurement precision
If a static scale large enough to accommodate the entire vehicle is used, then accurate total weight determination is achieved, but the scale becomes very large and expensive increasing device complexity
Solution Approach 1:
The weighing system is segmented into multiple small axle-scale units positioned along the roadway, each capable of weighing individual axles as vehicles pass over them. This segmentation replaces the need for a single large static scale that must accommodate entire vehicles. The segmented approach uses several small scales with load cells positioned externally to measure forces in linkages, thereby achieving accurate weight determination through multiple measurements while reducing the size and complexity of each individual scale component.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves faster stabilization and improved measurement accuracy for moving loads, simplifies the installation and maintenance of vehicle scales, and ensures precise weight readings without moment-induced errors, making it suitable for heavy-duty applications.
Implementation Method 1
each of the plurality of load cell assemblies includes an upper portion supported by the base and a lower portion supporting the platform structure... generate a signal based on a tension force on the load cell
Data Source
AI summary
A weighing system has a base, a platform structure, and a plurality of load cell assemblies. The platform structure is movable with respect to the base and includes a planar top surface defining a horizontal plane. Each of the plurality of load cell assemblies includes an upper portion supported by the base and a lower portion supporting the platform structure. Each of the plurality of load cell assemblies is positioned such that when the upper portion of each of the plurality of load cell assemblies is projected onto the plane and the planar top surface is projected onto the plane, each of the projected upper portions is located outwardly of the projected planar top surface. A load on the planar top surface is therefore located between the load cell assemblies.