Positive Lock Nut Assembly for Precise Torque and Anti-Backout
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Solution Overview
Problem
Current locking fastener systems are expensive, difficult to install, prone to damage, and have limited reuse and torque consistency, with existing resilient inserts like Vespel™ being costly and limited in application, and existing alternatives facing issues with vibration and temperature variability.
Innovation Solution
A positive torque locked nut and fastener system utilizing a helical wire insert with external and internal threads, combined with a longitudinally serrated lock nut and cap, which allows for precise torque application and resistance to backing out, enabling improved locking and maintainability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resilient inserts like Vespel™ are used for locking fasteners, then locking torque is provided, but the inserts are expensive, easily damaged during installation, and cannot be reused
Solution Approach 1:
The patent replaces expensive, proprietary resilient inserts with a disposable castellated cap and locking insert assembly that can be easily installed and discarded. The cap is crimped onto the nut body, creating a low-cost, non-reusable component that eliminates the need for expensive Vespel™ inserts while maintaining locking functionality.
Solution Approach 2:
The patent changes the material and structural parameters from resilient polymer inserts to a metal castellated cap with defined crenellations. This parameter change transforms the locking mechanism from relying on elastic deformation to relying on precise geometric alignment and mechanical engagement, improving ease of installation and reducing cost.
2Reliability
If castellated caps with crenellations are used for positive locking, then shaft position is locked, but the fastener cannot maintain specified torque tolerance under vibration and temperature variations
Solution Approach 1:
The patent merges the castellated cap with the locking insert to form an integrated assembly. The locking insert is received within the cap, combining the position-locking function of the castellations with the torque-maintaining function of the locking insert, thereby achieving both shaft position locking and torque tolerance under vibration and temperature variations.
Solution Approach 2:
The locking insert acts as an intermediary between the castellated cap and the shaft. It receives the cap's locking action and translates it into precise torque application on the shaft, ensuring that the specified torque tolerance is maintained even when the fastener is subjected to vibration and temperature variations.
3Reliability
If proprietary Vespel™ material is used, then locking insert approval is obtained, but substitution by third-party alternatives is not permitted, increasing cost
Solution Approach 1:
The patent creates a universal locking mechanism using standard metal castellated caps and locking inserts that can serve multiple functions and applications. The design does not rely on proprietary polymer materials, allowing third-party manufacturers to produce compatible components, thereby increasing material substitution flexibility while maintaining OEM approval through standardized designs.
4Reliability
If resilient inserts are used, then locking torque is achieved, but the number of insertion and removal cycles within specified limits is limited
Solution Approach 1:
The patent accepts that the castellated cap and locking insert assembly is disposable rather than reusable. By designing a low-cost metal cap that can be easily crimped and installed, the system enables multiple insertion and removal cycles without the degradation issues that limit resilient polymer inserts, effectively extending the functional cycle life through replaceability rather than durability.
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 system provides a cost-effective, durable, and reliable locking mechanism with improved torque consistency and maintainability, capable of withstanding various environmental conditions, reducing the need for expensive proprietary materials and enhancing assembly processes.
Implementation Method 1
the helical wire insert resisting the backing out of the driven insert with a torque greater that the given torque for driving the threaded shaft into the helical wire insert
Implementation Method 2
the exterior of the fastener nut longitudinally serrated to accept a compatibly longitudinally serrated castellated cap
Data Source
AI summary
A combination positive locking and prevailing torque fastener system including a fastener nut, a helical wire insert, a nut cap, and a shaft. The nut cap is longitudinally movable from an engaged position to a disengaged position such that in the engaged position the fastener nut and the nut cap are rotationally locked, and in the disengaged position the nut cap rotates independent of the fastener nut.