Aquatic Propulsion Foil Articulation for Reduced Ankle Strain

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Solution Overview

Problem

Conventional fin devices cause ankle fatigue and strain due to excessive loading, and their propulsion efficiency is limited by foil dimensions that hinder walking when retracted.

Innovation Solution

An aquatic propulsion device with a first portion attached to the swimmer's leg and a second portion allowing rotational articulation of a foil, enabling a deployed configuration for swimming and a retracted configuration for walking, with the foil positioned forward to avoid hindering foot movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the foil is retracted rearwards towards the calf, then the ankle loading is reduced, but the foil size is constrained and propulsion efficiency deteriorates

Engineering Contradiction:

Improveankle loadingVSAvoidfoil surface area

Core Design Contradiction:

Object-affected harmful factorsVSArea of moving object

Solution Approach 1:

Instead of retracting the foil rearwards towards the calf as in conventional designs, this patent inverts the approach by positioning the rotation axis forward and allowing the foil to retract forwards towards the knee. This inversion resolves the contradiction by creating sufficient clearance for large foil surfaces while reducing ankle loading through the forward retraction position.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of operation

If the foil is positioned far from the rotation axis, then the opening for foot passage is enlarged improving walking, but the foil dimensions are limited reducing propulsion

Engineering Contradiction:

Improvewalking convenienceVSAvoidpropulsion force

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent repositions the rotation axis from the ankle area to the forward tibia region, creating a new spatial dimension for the mechanism. This dimensional change allows the foil to be positioned at an optimal distance from the rotation axis, providing both sufficient opening for foot passage during walking and adequate foil dimensions for effective propulsion.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If a large foil surface is used, then propulsion efficiency is improved, but the foil hinders walking motion when retracted

Engineering Contradiction:

Improvepropulsion efficiencyVSAvoidwalking motion

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The patent implements a dynamic retraction mechanism where the foil can rotate forwards towards the knee, creating a compact configuration that clears the foot path during walking. This dynamic positioning allows large foil surfaces to be used for propulsion while eliminating interference with walking motion through the forward retraction capability.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12390693B2Aquatic propulsion device

Publication Date: 2025.08.19 S C P PHORCYS DIVING

AI summary

An aquatic propulsion device to be worn by a swimmer includes a first portion to be securely attached to the leg of the swimmer, which includes a bearing part having an inner face shaped so as to bear on the tibia of the swimmer and an outer face opposite to the inner face; a second portion including a first foil and a foil support, the first foil being secured to the foil support and the foil support enabling rotational articulation of the second portion relative to the first portion according to a first axis so as to make the device alternately switch from a deployed configuration into a retracted configuration.