Tapered Dilator Shaft With Variable Helical Angles
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Solution Overview
Problem
Existing dilators face challenges in achieving sufficient thrust and expansion of penetration-holes in the digestive tract due to increased resistance, often resulting in incomplete expansion.
Innovation Solution
A dilator design featuring a shaft with a smaller distal end diameter and a spirally-arranged protruding portion with varying angles of inclination along its length, combined with a grip part, to facilitate smooth expansion and reduce unnecessary rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional dilator design is used, then the structure is simple, but the thrust is insufficient and the penetration-hole cannot be sufficiently expanded
Solution Approach 1:
The dilator shaft is divided into multiple sections with different outer diameters (first section with larger diameter, second section with smaller diameter) and the protruding portion is segmented into multiple helical turns. This segmentation allows each section to perform its specific function: the first section provides initial engagement and the second section provides expansion force, while the segmented helical structure enables progressive engagement and reduces unnecessary rotation.
Solution Approach 2:
Different sections of the shaft have different outer diameters and the protruding portion has varying pitch and helical angles at different locations. The first section has a larger outer diameter for stable insertion, while the second section has a smaller outer diameter for better engagement. The helical protruding portion has different pitch values at different axial positions, creating local variations in engagement characteristics to optimize both thrust generation and rotation control.
2Reliability
If the dilator is pushed into the penetration-hole, then expansion occurs, but unnecessary rotation happens and expansion is incomplete
Solution Approach 1:
The helical protruding portion creates a dynamic engagement mechanism where the tilted helical turns engage with the penetration-hole walls progressively. As the dilator is pushed forward, the helical structure naturally converts linear motion into rotational engagement, but the specific helical geometry and pitch variation ensure that the engagement is controlled and prevents unnecessary rotation while maintaining forward progression for complete expansion.
Solution Approach 2:
The pitch of the helical protruding portion is varied at different axial positions, creating different engagement characteristics along the shaft length. The pitch changes from the first section to the second section, optimizing the engagement force at each location. This parameter variation ensures that the dilator maintains proper engagement angle and prevents unnecessary rotation while achieving complete expansion of the penetration-hole.
3Force
If a uniform helical protruding portion is used, then the structure is simple, but the thrust is insufficient at the tapered part
Solution Approach 1:
The helical protruding portion has different pitch values at different axial positions, with the pitch being optimized for the tapered section. The pitch is smaller in the region corresponding to the tapered part to increase engagement density and thrust generation capability. This local variation in pitch creates stronger engagement forces at the critical tapered section where expansion is needed, while maintaining simpler geometry in other regions.
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 design enhances the ability to widen penetration-holes efficiently by minimizing rotation and improving flexibility and torquability, ensuring complete expansion of the penetration-hole.
Implementation Method 1
the tapered part experiences an increased resistance when being pushed into a penetration-hole or constricted part
Implementation Method 2
A spirally-arranged protruding portion that protrudes toward an exterior is provided on an outer peripheral face of the shaft
Data Source
AI summary
A dilator includes a shaft in a hollow shape whose distal end has a smaller outer diameter than the proximal end, and a connector on the proximal end of the shaft. A spirally-arranged protruding portion on an outer peripheral face of the shaft has gaps between neighboring sections along an axis of the shaft. The shaft has a first location and a second location located closer to the distal end than the first location and having an outer diameter smaller than at the first location. The spirally-arranged protruding portion has, with respect to the axis, an angle of inclination that is larger at the second location than at the first location.