Telescopic Strut Eccentric Sleeve Adjustment Mechanism
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Solution Overview
Problem
Existing telescopic struts for external fixators are difficult to adjust in length and lack a simple method for fine adjustments, making it challenging to achieve quick length changes and dynamization for fracture/fusion site healing.
Innovation Solution
A telescopic strut design featuring an axially extending rod with circumferential grooves, a tube with holes and a pin, and a sleeve with eccentric bore, along with a coupling element and adjustment system, allowing for quick length adjustment and fine tuning through ball engagement and rotation, enabling micro-motion for healing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional telescopic strut designs are used, then the structure is relatively simple, but the length adjustment is difficult and time-consuming
Solution Approach 1:
The strut incorporates a telescopic mechanism with a rod that can extend and retract within a tube, allowing dynamic length adjustment. The rod features circumferential grooves that engage with balls in the tube, enabling smooth telescopic motion while maintaining structural integrity during length changes.
Solution Approach 2:
The adjustment mechanism is divided into discrete components: the rod with circumferential grooves, balls positioned at specific intervals within the tube, and a sleeve with an eccentric bore. This segmentation allows for stepwise length adjustments by engaging different ball positions, making the adjustment process systematic and controllable.
2Measurement precision
If traditional adjustment mechanisms are used, then the structure is simpler, but fine adjustments of strut length are not possible
Solution Approach 1:
The sleeve with eccentric bore provides a dynamic locking mechanism that can engage with balls at different positions along the rod. By rotating the sleeve to different angular positions, fine adjustments of the strut length are achieved, allowing precise control over the extension distance.
Solution Approach 2:
The circumferential grooves on the rod create discrete engagement positions for the balls, providing tactile and positional feedback during adjustment. This feedback mechanism ensures that the strut settles at precise, predetermined length intervals, enabling accurate length control.
3Productivity
If quick length change is implemented, then adjustment speed improves, but control over final length precision may be compromised
Solution Approach 1:
The balls are pre-positioned at specific intervals along the tube, and the circumferential grooves on the rod are预先 formed at predetermined positions. This preliminary arrangement allows for rapid engagement at correct positions without requiring manual measurement or alignment during the adjustment process.
Solution Approach 2:
The telescopic mechanism is designed to self-lock when the rod is extended or retracted, as the balls automatically engage with the circumferential grooves at the appropriate positions. This self-service feature eliminates the need for additional locking operations, maintaining both speed and precision.
Data Source
AI summary
A telescopic strut for use with an external fixator comprising an axially extending rod; an axially extending tube moveably recurring the rod for varying the length of the rod and tube combination along a longitudinal axis; the tube having first and second ends, the second end having a pin extending therethrough; a locking system mounted on the tube first end for adjusting the position of the rod in the tube and fixing the length of the rod and tube combination; a coupling element having a tubular sleeve with a threaded outer surface mounted on an outer surface of the second end of the tube, the sleeve having two diametrically opposed slots receiving the pin and an adjustment element threadably mounted on the sleeve outer surface for axial movement along the axis, the adjustment element having a surface contacting the pin to limit the movement of the pin in the slots.