Positive Locking Fastener Cap for Vibration-Resistant Torque Retention
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Solution Overview
Problem
Existing mechanical fasteners with positive locking mechanisms face issues with loosening due to vibrations, and existing solutions like locking wires do not sufficiently prevent looseness, requiring re-tightening and potential loss of nominal torque.
Innovation Solution
A cap design that engages with a nut and receives a pin, featuring a locking portion with pairs of through openings arranged symmetrically, allowing movement and alignment with a screw's radial hole to lock the fastener, ensuring alignment regardless of the nut's position without altering the nominal tightening torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If re-tightening is performed to enable pin insertion, then pin insertion becomes possible, but the nut is no longer tightened to nominal torque causing torque loss
Solution Approach 1:
The cap and its through openings are pre-designed and pre-positioned to ensure automatic alignment with the radial hole regardless of nut position. This preliminary design eliminates the need for re-tightening actions, allowing pin insertion to proceed without compromising the nominal torque already applied to the fastener.
2Reliability
If multiple pairs of openings are provided in the locking portion, then alignment probability increases, but the device complexity increases
Solution Approach 1:
Instead of increasing the number of opening pairs, the solution optimizes the angular sector φ of each opening and their angular distribution. By carefully calculating these parameters based on the nut's angular period θ and the desired reliability level, the invention achieves reliable alignment guarantee with minimal opening pairs, thus avoiding excessive device complexity.
Data Source
AI summary
The invention relates to a positive locking fastener comprising: a screw (1) having a radial hole (120) at a threaded portion (12); a nut (2) having a tightening portion (21); a cap (3); and a pin (4). The cap has a locking portion (31) intended to cover the threaded portion and a blocking portion (30) intended to engage with a tightening portion of the nut.The blocking portion comprises at least one pair of diametrically opposed openings (32) suitable for allowing a pair of openings to be aligned with the radial hole, in order to allow the pin to be inserted and thus lock the fastening regardless of the relative position of the nut with respect to the screw. The invention also relates to a method for implementing the fastener according to the invention.