Disposable Torque-Limiting Driver With Hybrid Clutch Assembly
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Solution Overview
Problem
Current disposable torque-limiting drivers in the medical industry face challenges in imparting high torques required for larger applications, as they are traditionally limited to low torque values and lack reliability, necessitating the development of a more robust and reliable disposable solution.
Innovation Solution
A fortified clutch assembly torque-limiting driver with a hybrid plastic-metal gear system that engages and disengages at a predetermined torque limit, utilizing hardened 440c stainless steel gear rings and a coil spring mechanism to maintain drive connection and ensure precise torque delivery, capable of withstanding forces up to 120 inch-pounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If disposable drivers are used for low torque applications, then they can be discarded after use without recalibration or sterilization, but they cannot reliably impart high torques required for larger applications
Solution Approach 1:
The clutch assembly uses a hybrid construction combining metal components (spring, shaft, nut) with plastic components (cylindrical shanks, gear rings) to achieve both high torque capacity and disposable reliability. The metal spring provides elastic force for torque limitation, while the hardened plastic gear rings transmit high torque through gear engagement, creating a composite structure that overcomes the limitations of single-material designs.
Solution Approach 2:
The clutch assembly employs curved gear rings with interlocking teeth that engage through rotational motion. The gear rings feature curved profiles that allow smooth torque transmission and disengagement at predetermined torque limits, enabling reliable high-torque delivery through geometric curvature rather than linear mechanical connections.
2Force
If reusable drivers are used, then they can impart high torque, but they require constant recalibration and sterilization
Solution Approach 1:
The clutch assembly is designed as a disposable device that can reliably impart high torque (up to 120 inch-pounds) for a single use and then is discarded. This eliminates the need for recalibration and sterilization procedures required by reusable drivers, while maintaining the high torque capacity through robust metal-plastic construction and pre-calibrated spring mechanisms.
3Force
If piecemeal drivetrain systems are used to gear-up torque, then greater torque can be achieved, but the number of part-to-part transitions increases
Solution Approach 1:
The clutch assembly integrates multiple functions into a single unified structure: the metal spring provides torque limitation, the plastic cylindrical shanks provide structural support, and the gear rings provide torque multiplication and transmission. This merged design achieves high torque output (120 inch-pounds) through a single integrated clutch assembly rather than multiple separate drivetrain components, reducing part-to-part transitions while maintaining torque capacity.
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 solution provides a reliable and precise torque delivery system capable of maintaining torque levels of at least 12 Newton-meters over multiple actuations, reducing the need for recalibration and sterilization, and enhancing the durability and efficiency of disposable torque-limiting drivers for higher torque applications.
Implementation Method 1
a coil spring between the upper cylindrical shank and the nut, wherein the spring is configured to apply a force across the upper cylindrical shank and the lower cylindrical shank
Implementation Method 2
the gear ring of the upper cylindrical shank and the gear ring of the lower cylindrical shank engage for relative rotation, and wherein the gear rings disengage when a predetermined torque limit is exceeded
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A torque-limiting device which may include a shaft extending axially through a clutch assembly and a spring to connect to a nut. The upper and lower shanks may be under a force from the spring and further configured to selectively engage within a predetermined torque limit and disengage at above the predetermined torque limit. Accordingly, the shaft may receive torque up to the predetermined limit as provided by a user operating a handle of the torque-limiting device. The torque-limiting device may be disposable, reusable, economical, and have high torque capabilities.