Undulated Torque-Limiting Shank Interface for High-RPM Reliability
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Solution Overview
Problem
Disposable torque-limiting devices for medical power tools fail to maintain torque specification at higher rotational speeds, leading to inadequate performance and reliability issues.
Innovation Solution
A torque-limiting mechanism comprising an upper shank component, a lower shank component, and a biasing element, with undulated torque-limiting interfaces that engage and disengage to maintain a predetermined torque limit, using materials like glass-filled polyetherimide resin for durability and resistance to sterilization, and incorporating a biasing element to apply compressive force for precise torque control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If disposable torque-limiting devices are used for medical power tools, then cost and ease of disposal are improved, but torque specification reliability deteriorates at higher rotational speeds
Solution Approach 1:
The torque-limiting mechanism uses dynamic engagement and disengagement of undulated interfaces between shank components. The undulations allow the mechanism to adapt to varying rotational speeds while maintaining torque control, enabling reliable performance at higher RPMs without requiring complex calibration systems.
Solution Approach 2:
The shank components are made from glass-filled polyetherimide resin, a composite material that provides enhanced durability, thermal stability, and mechanical strength. This material choice enables the disposable device to maintain torque specification reliability at high rotational speeds while remaining cost-effective for single-use applications.
2Productivity
If higher rotational speeds are used in medical power tools, then productivity is improved, but torque control precision deteriorates in traditional disposable devices
Solution Approach 1:
The undulated torque-limiting interfaces dynamically engage and disengage during rotation, creating a self-regulating mechanism that maintains precise torque control across a wide range of rotational speeds. The geometry of the undulations is designed to maintain consistent contact and force distribution regardless of RPM.
Solution Approach 2:
The mechanism changes the physical parameters of the torque-limiting interface through the undulated geometry, which modifies the contact mechanics and friction characteristics. This allows the device to maintain precise torque control at varying rotational speeds by leveraging the geometric properties of the undulations rather than relying on speed-dependent calibration.
3Measurement precision
If reusable torque-limiting drivers are used, then torque precision is improved, but maintenance complexity and sterilization requirements worsen
Solution Approach 1:
The invention creates a disposable torque-limiting mechanism that achieves torque precision comparable to reusable devices without requiring sterilization or recalibration. The glass-filled polyetherimide resin and robust undulated interface design ensure consistent performance throughout the single use, eliminating maintenance complexity while maintaining precision.
Solution Approach 2:
The torque-limiting mechanism is designed to be self-contained and self-regulating, with no moving parts requiring adjustment or sterilization. The undulated interfaces and biasing element work together to automatically maintain torque precision without user intervention, making the disposable device as reliable as reusable systems without the associated maintenance burden.
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 mechanism effectively limits torque at higher rotational speeds, maintaining performance over a large number of actuations while withstanding sterilization and cleaning processes, ensuring consistent torque delivery up to 6 N-m across various RPMs.
Implementation Method 1
a biasing element configured to apply compressive force along the axis to compress the first torque-limiting interface against the second torque-limiting interface
Implementation Method 2
The upper shank component and the lower shank component are configured to engage to rotate together when torque is applied to the lower shank component via the drive socket
Implementation Method 3
The upper shank component and the lower shank component are configured to disengage when a predetermined torque limit is exceeded
Data Source
Figure 1
Figure 2~3
Figure 4A~4F
AI summary
Torque-limiting mechanisms comprising an upper shank component with a torque-limiting interface, a lower shank component with a torque-limiting interface, and a biasing element. Torque -limiting interfaces having a plurality of undulations arranged around an axial bore or drive socket and separated by a plurality of transition regions, with each undulation having an upslope, a peak, and a downslope. The torque-lmiiting interfaces are configured to engage and disengage to provide torque transmission with predetermined torque limits at various rotational speeds and for amounts of actuations while remaining within a specified operational range.