Locking Fastener With Spring Clip Pawl Prevents Vibration Loosening
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Solution Overview
Problem
Conventional nuts are prone to loosening due to vibrations, leading to safety concerns in applications like axle nuts, where increased friction solutions often require higher torque and are unpredictable, making it difficult to achieve precise longitudinal force.
Innovation Solution
A locking fastener with a spring clip and pawl mechanism that automatically locks when a wrench is removed and unlocks when engaged, using ratchet teeth and a retainer to provide positive locking without increasing torque requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If friction enhancement features (large pressure face, protrusions, adhesive) are added to prevent nut loosening, then resistance to loosening is improved, but torque required to tighten the nut increases and becomes unpredictable
Solution Approach 1:
The locking function is segmented from the fastening function. The retainer with ratchet teeth provides the locking mechanism that prevents loosening, while the nut itself maintains its standard threading and torque characteristics. This segmentation allows the locking feature to be added without increasing the torque required to tighten the nut.
Solution Approach 2:
The retainer acts as an intermediary component between the nut and the shaft. It provides the locking function through ratchet teeth engagement while allowing the nut to maintain its normal torque-to-force relationship. The spring clip with pawl mechanism serves as another intermediary that enables automatic locking without affecting the tightening torque.
2Reliability
If friction enhancement features are added to prevent nut loosening, then resistance to loosening is improved, but the torque translation to longitudinal force becomes unpredictable
Solution Approach 1:
By segmenting the locking function into a separate retainer component with ratchet teeth, the predictable torque-to-force relationship of the nut is preserved. The locking action occurs through the retainer's mechanical engagement rather than through friction modification, ensuring that torque translation remains precise and predictable.
3Reliability
If a positive locking feature is added to prevent nut loosening, then reliability under vibration is improved, but device complexity increases
Solution Approach 1:
The spring clip with pawl mechanism provides self-service automatic locking. When the nut is tightened, the spring clip automatically engages the retainer's ratchet teeth to lock the assembly. When the nut is loosened, the spring clip automatically disengages. This self-service mechanism reduces the need for additional complex locking components.
Solution Approach 2:
The spring clip introduces dynamic elements to the otherwise static fastening system. The spring-loaded pawl can automatically engage and disengage based on the rotational direction of the nut, providing adaptive locking without requiring complex mechanical structures.
4Ease of manufacture
If conventional nut designs are used, then ease of manufacture is maintained, but the nut loosens under vibration
Solution Approach 1:
The locking function is segmented into a separate retainer component that can be manufactured independently using standard stamping or forming processes. This segmentation allows each component to be manufactured using conventional, cost-effective methods while providing enhanced locking capability.
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 locking fastener effectively prevents nut loosening under vibration while maintaining predictable torque translation, ensuring robust and precise retention of wheel bearings, enhancing safety and control in vehicle applications.
Implementation Method 1
a torsional section that pushes the arm to bias the pawl against the retainer
Data Source
AI summary
A locking fastener is provided that may be automatically unlocked and locked by sliding a wrench onto the nut and removing the wrench. The fastener includes a biased arm extending outward from a wrench bearing surface that presses against a pawl. The pawl includes ratchet teeth that engage ratchet teeth of a retainer to lock the fastener. The fastener is unlocked by compressing the arm with a wrench.