Torsion Load Cell with Limit Post Overload Protection
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Solution Overview
Problem
Torsional load cells lack effective overload protection, leading to inaccurate readings and potential deformation under excessive torque, as conventional methods like mechanical stops are unreliable and complicate the design.
Innovation Solution
A load cell structure with a resilient body and sensing beams, featuring a limit post with contact surfaces that create overload gaps, providing bidirectional protection against sudden impacts and excessive torque by limiting relative rotation and preventing permanent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical stops are used to limit relative rotation in torsion monitoring load cells, then overload protection is provided, but the device complexity increases and reliability decreases due to difficult setup and false readings
Solution Approach 1:
The patent merges the overload protection function directly into the sensing beams themselves by creating discontinuities within the beams. This eliminates the need for separate mechanical stops, reducing device complexity while maintaining reliability. The sensing beams incorporate internal discontinuities that allow controlled deflection under overload conditions, integrating multiple functions into a single structural element.
Solution Approach 2:
The patent introduces discontinuities as intermediary elements within the sensing beams that mediate between the applied overload and the beam structure. These discontinuities act as controlled weak points that allow the beam to deflect in a predictable manner under overload, providing reliable protection without requiring complex external mechanical stops.
2Reliability
If high deflection load cell design is used to tolerate high levels of sensing beam distortion, then overload protection is achieved, but frequency response deteriorates due to reduced material stiffness
Solution Approach 1:
The patent applies local quality by creating discontinuities at specific locations within the sensing beams rather than uniformly reducing stiffness throughout. This allows the majority of the beam structure to maintain high stiffness for good frequency response, while localized discontinuities provide controlled deflection pathways under overload conditions. The discontinuities are strategically positioned to enable overload protection without compromising overall structural rigidity.
3Device complexity
If conventional load cell design without overload protection is used, then device complexity is minimized, but measurement precision deteriorates under excessive torque due to deformation
Solution Approach 1:
The patent implements preliminary action by pre-configuring discontinuities within the sensing beams during manufacturing. These discontinuities are prepared in advance to activate only when overload conditions occur, allowing the beam to deflect in a controlled manner that prevents permanent deformation. This approach maintains measurement precision under normal operating conditions while providing automatic protection when limits are exceeded, all within a simple structural design.
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 load cell structure ensures accurate and precise measurement of torsional forces by preventing deformation and maintaining structural integrity under rated capacity, enhancing reliability and frequency response.
Implementation Method 1
The sensing beams have strain gages applied thereto. The torque applied to the structure results in torsional forces producing dimensional changes in the sensing beams. The electrical strain gages are sensitive to the changes and an accurate reading of the applied load is derived by external measurement apparatus.
Implementation Method 2
a body of resilient material having opposing force-receiving ends spaced along the axis of rotation
Data Source
AI summary
A load cell structure for receiving strain gages to monitor applied torsional forces wherein the opposing force-receiving ends have a plurality of sensing beams spaced about an axis of rotation. Limit posts located between the ends each have a discontinuity therein that includes a U-shaped gap to limit relative rotation about the axis and thereby providing overload protection.