Rotatable Wave Washer Spring Mechanism for Compact Stiffness Tuning

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Solution Overview

Problem

In orthopedic devices such as orthoses and prostheses, there is a challenge in adapting a storage spring to varying energy requirements due to limited installation space, necessitating non-adjustable springs that must be specifically selected for each application, which limits flexibility and adaptability.

Innovation Solution

A spring device comprising at least two corrugated washers with a spring washer in between, allowing for stepless adjustment by rotating the washers, enabling variable spring deflection and energy storage without increasing the structural volume, achieved through the arrangement of multiple spring washers in series and a sinusoidal wave shape for optimal energy absorption and release.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a non-adjustable storage spring is selected to suit a specific application, then the device meets the specific energy requirements, but the adaptability to different applications and changing operating conditions is limited

Engineering Contradiction:
Improveadaptability to different applicationsVSAvoidcomplexity of spring selection and installation
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The spring device incorporates adjustable wave disks that can be rotated relative to each other to dynamically change the spring characteristics. This allows the same device to adapt to different energy requirements by adjusting the relative position of the wave disks, eliminating the need for selecting different fixed springs for different applications.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the physical parameters of the spring system by rotating the wave disks to different angular positions. This alters the effective spring length, stiffness, and energy storage capacity without changing the physical spring itself, enabling continuous adaptation to varying operational requirements.

Inventive Principle:
Principle #35Parameter changes

2Use of energy by moving object

If the spring stroke is increased to store more energy, then the energy storage capacity improves, but the installation volume increases

Engineering Contradiction:
Improveenergy storage capacityVSAvoidinstallation volume
Core Design Contradiction:
Use of energy by moving objectVSVolume of moving object

Solution Approach 1:

The invention utilizes the angular dimension by rotating the wave disks relative to each other. This allows the spring stroke and energy storage capacity to be adjusted in the rotational dimension without increasing the axial length or radial dimensions of the device, maintaining a compact installation volume while varying energy capacity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The wave disks are designed to be rotatable, allowing dynamic adjustment of the spring characteristics. This enables the same compact structure to provide variable energy storage capacity by changing the angular position, rather than requiring different physical sizes for different energy requirements.

Inventive Principle:
Principle #15Dynamics

3Use of energy by moving object

If multiple spring washers are arranged in series to increase energy storage, then the energy storage capacity improves, but the device complexity increases

Engineering Contradiction:
Improveenergy storage capacityVSAvoidcomplexity of spring assembly
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The invention merges multiple spring washers into a single integrated spring disk assembly between the wave disks. This combination provides increased energy storage capacity through the stacked spring elements while maintaining a simple, unified structure that does not increase device complexity, as the combined assembly functions as a single adjustable unit.

Inventive Principle:
Principle #5Merging (Combining)

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

This configuration allows for precise adjustment of spring stiffness and energy storage, accommodating different patient needs and activity levels without additional volume, ensuring efficient energy storage and release in a compact form.

Implementation Method 1

there are mechanical energy storage devices that store energy through elastic deformation. To release this energy, the device returns to its original shape; this is therefore an elastic deformation or reversible deformation.

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The wave disks are rotatably mounted relative to each other, and the spring disk is flat in an unloaded state and arranged between two rigid wave disks. The rotatable arrangement of the two wave disks, between which the at least one spring disk is located, allows for stepless adjustment to the respective application.

Methodology Applied
Scientific EffectMechanical conversion through wave geometry: Geometry

Data Source

PatentEP3707406B1Spring mechanism and hydraulic actuator
Publication Date: 2021.08.25 OTTO BOCK HEALTHCARE PROD GMBH
  • EP3707406B1 patent drawingFigure 1
  • EP3707406B1 patent drawingFigure 2
  • EP3707406B1 patent drawingFigure 3

AI summary

The invention relates to a spring mechanism comprising at least two wave washers (11, 12, 13) and at least one spring washer (20) between the wave washers (11, 12, 13), the wave washers (11, 12, 13) being mounted so as to be twistable relative to one another.