Load Cell Web Air Gaps for Overload Protection
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Solution Overview
Problem
Existing load cells are expensive to produce due to the need for precise tolerances and complex manufacturing processes, particularly in the production of bending rods with overload protection features.
Innovation Solution
A load cell design featuring a bending rod with a web that separates two recesses, where the web's outer sides are straight and engage in a material-free area, creating upper and lower air gaps that open into a third recess with a round contour, allowing for cost-effective manufacturing and reliable overload protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional overload protection designs with precise dowel pins and contoured spigots are used, then reliable overload protection is achieved, but manufacturing cost and complexity increase due to precise tolerance requirements
Solution Approach 1:
The bending rod is segmented into distinct functional zones: a deformation zone with recesses for measurement, and a web structure with air gaps for overload protection. This segmentation allows each zone to be optimized independently - the deformation zone for precise measurement and the web structure for simple, cost-effective overload protection without requiring precise tolerances across the entire component.
Solution Approach 2:
The invention changes the critical parameter from precise dimensional tolerances (in traditional dowel pin designs) to air gap dimensions. The air gaps provide overload protection through geometric constraints rather than precision-fit mechanical elements, significantly reducing manufacturing complexity and cost while maintaining reliability.
2Reliability
If long thin slots with small tolerances are formed in the bending rod, then effective overload protection is achieved, but manufacturing cost increases due to tight tolerance requirements
Solution Approach 1:
Instead of creating long thin slots that extend through the bending rod (as in prior art), the invention inverts the approach by creating air gaps within a web structure. The air gaps are bounded by the web's outer sides and provide overload protection without requiring the bending rod material to form long, tolerance-critical slots.
3Ease of manufacture
If the web structure with air gaps is used for overload protection, then manufacturing cost and complexity are reduced, but the design must ensure proper engagement in material-free areas
Solution Approach 1:
The web structure with air gaps is designed to engage in material-free areas (air gaps) that are inherent to the bending rod's deformation zone. The web's outer sides naturally define the air gap boundaries, and the structure self-regulates overload conditions through the geometric constraints of the air gaps without requiring additional components or complex assembly procedures.
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 design reduces manufacturing complexity and costs while providing effective overload protection, enabling the load cell to be produced economically and ensuring operational reliability across various weight ranges.
Implementation Method 1
between the outer sides of the web running parallel to the central plane and the force introduction side there is an upper and a lower air gap
Data Source
Figure 1
Figure 2
AI summary
To achieve cost-effective manufacturing, the overload protection device is designed to have a web (4) extending parallel to the central plane of the bending bar (2), which engages freely in a recess on the movable force application side (23) of the bending bar (2), so that an upper and a lower air gap (41, 42) exist between the web (4) and the force application side (23). In the event of an overload, the upper or lower air gap is bridged and the force application side (23) comes into contact with the web (4), so that no further movement of the force application side (23) relative to the fixed side (21) of the load cell is possible.