Single-Use Torque Limiter with Elastic Gear Prongs
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Solution Overview
Problem
Existing torque limiting tools in orthopedic surgical procedures require frequent recalibration for precise torque application, and single-use tools lack a reliable mechanism to ensure consistent torque delivery without bias members or washers.
Innovation Solution
A single-use torque limiting tool with opposing gears having outwardly extending prongs with angular orientations and ramp surfaces, where torque is transferred between prongs until a maximum limit is exceeded, causing the prongs to flex and disengage, preventing further torque transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If reusable torque limiting tools are used, then the tool can be reused multiple times, but frequent recalibration is required to ensure precise torque application
Solution Approach 1:
The patent employs a single-use torque limiting tool where the torque limiting mechanism is designed to be discarded after one use. This eliminates the need for recalibration between uses while ensuring consistent torque delivery. The tool is packaged with each implant and is specifically designed according to the implant's specifications, guaranteeing precise torque application without requiring maintenance or recalibration.
2Reliability
If single use torque limiting tools are used, then recalibration is not needed, but a reliable torque limiting mechanism without bias members or washers is difficult to implement
Solution Approach 1:
The patent changes the material parameters of the gear prongs to achieve torque limiting. The prongs are made from a material with specific elastic properties that allow them to flex at a predetermined torque threshold. By adjusting the material's elastic modulus and the prong geometry, the torque limit is precisely controlled without requiring complex mechanical components like bias members or washers.
Solution Approach 2:
The patent replaces the traditional mechanical torque limiting system (using bias members, springs, or washers) with an elastic deformation mechanism. The gear prongs utilize elastic theory to limit torque through controlled flexing, substituting complex mechanical assemblies with a simpler elastic response that achieves the same torque limiting function.
3Force
If gear prongs with angular orientation are used, then torque transfer is achieved through prong contact, but the prongs must be precisely positioned to ensure proper engagement
Solution Approach 1:
The patent employs asymmetric gear prong design where the prongs have different orientations and geometries on opposing gears. This asymmetry ensures that the prongs engage at specific angles that maximize torque transfer while accommodating manufacturing tolerances. The angular orientation is deliberately designed to create a mechanical advantage that facilitates reliable engagement without requiring extremely tight positioning precision.
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 tool ensures precise and consistent torque application to secure orthopedic implants or bone plates, minimizing damage and movement, with the maximum torque limited by the mechanical properties of the prongs and material selection, eliminating the need for frequent recalibration.
Implementation Method 1
Torque is transferred between the gears when at least two of the opposing prongs are in physical contact therebetween
Implementation Method 2
either of the prongs of the opposing gears flex towards the respective gear surface, thereby enabling the opposing prongs to slide off the ramp surface
Data Source
AI summary
A torque limiting tool is described. The tool comprises a torque limiting mechanism that drives a shank about a rotational axis. The torque limiting mechanism comprises a plurality of opposed first and second gears having a plurality of outwardly extending first and second gear prongs. The plurality of first and second gear prongs extends outwardly at an inclined angle along an intermediate prong portion from a prong proximal end positioned along the disc sidewall surface to a prong distal portion. Each of the prong distal portions comprises a plateau portion that extends about parallel with the disc sidewall surface and resides at a distance away from the sidewall surface of the respective first and second discs. The mechanism is constructed such that toque is transferred therebetween when the respective intermediate portions of the opposed first and second prongs are in physical contact. When an upper torque limit is exceeded, either of the respective first and second prongs deflect, thus causing the other of the first or second prong to ride along the deflected ramp surface of the intermediate prong portion until the first and second prongs disengage.