Claw-Type Anti-Rotation Threaded Rod for Injection Devices
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Solution Overview
Problem
Existing injection devices face issues with incorrect operation due to accidental retraction of the piston or threaded rod, leading to improper dosing and potential under or over-administration of substances.
Innovation Solution
A threaded rod with an anti-rotation element, such as a claw lock, is designed to prevent rotation and axial displacement once fully inserted, ensuring the rod remains in place without the need for additional holding devices, utilizing engagement elements and beveled surfaces for secure locking and easy release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a threaded rod is inserted into an injection device to displace substance, then the substance can be dispensed, but the threaded rod may be accidentally retracted or rotated leading to incorrect operation
Solution Approach 1:
The threaded rod is segmented into functional zones: a distal threaded portion for engagement with the stopper, a central smooth portion for unobstructed movement, and a proximal anti-rotation portion with claws or ribs. This segmentation allows each section to perform its specific function while collectively preventing accidental retraction through the anti-rotation elements that engage with counter-elements in the injection device housing.
Solution Approach 2:
Anti-rotation counter-elements (such as grooves, recesses, or engagement features) are introduced as intermediary structures in the injection device housing that work in conjunction with the anti-rotation elements on the threaded rod. These intermediary features create a mechanical interlock that prevents both rotation and accidental retraction, solving the reliability problem while maintaining relatively simple overall device architecture.
2Reliability
If additional holding devices are added to prevent retraction of the threaded rod, then reliability improves, but device complexity increases
Solution Approach 1:
The anti-rotation and retention functions are merged into the threaded rod itself through the integration of anti-rotation elements (claws, ribs, or protrusions) directly on the rod. These elements combine the securing function with the existing threaded rod structure, eliminating the need for separate holding devices or additional components while maintaining high reliability.
Solution Approach 2:
The threaded rod is designed with multi-functionality: it provides substance displacement through its threaded portion, prevents rotation through its anti-rotation elements, and prevents accidental retraction through the same anti-rotation elements engaging with counter-elements. This multi-functional design consolidates multiple securing functions into a single component, reducing overall device complexity while improving reliability.
Data Source
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AI summary
The invention relates to a threaded rod with an anti-rotation or claw-type securing means (5g) that can engage in mating anti-rotation elements (2g) or claws of the injection device, in order to prevent rotation of the threaded rod relative to the injection device.