Respiration Therapy Fan Impeller Cutouts for Inertia Reduction

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Solution Overview

Problem

Respiration therapy appliances with conventional fans generate noise and require abrupt speed adjustments, which can be annoying and inefficient.

Innovation Solution

A respiration therapy appliance with a fan impeller featuring a support disk and blade elements, where cutouts are strategically placed to reduce mass moment of inertia, allowing for smoother speed adjustments and quieter operation at lower rotational speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a conventional fan impeller is used, then the structure is simple and easy to manufacture, but the mass moment of inertia is high causing noise and abrupt speed adjustments

Engineering Contradiction:

ImprovenoiseVSAvoidmass moment of inertia

Core Design Contradiction:

Object-affected harmful factorsVSWeight of moving object

Solution Approach 1:

Material is extracted from the impeller body by creating cutouts in the support disk and/or blade elements. This removes unnecessary mass from regions that do not contribute to the primary airflow generation function, thereby reducing the mass moment of inertia and noise while preserving the essential structural integrity and aerodynamic performance of the impeller.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The impeller is designed with a porous or hollow structure through the incorporation of cutouts. This creates a lightweight construction that reduces mass moment of inertia without completely compromising structural strength. The porous design allows material removal in non-critical areas while maintaining the necessary rigidity for noise reduction and smooth speed adjustment.

Inventive Principle:

Principle #31Porous materials

2Ease of operation

If the impeller mass is reduced through cutouts, then speed adjustment becomes smoother and quieter, but manufacturing complexity increases

Engineering Contradiction:

Improvespeed adjustment smoothnessVSAvoidmanufacturing complexity

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The impeller design segments the support disk and blade elements by introducing cutouts that divide the continuous structure into separate regions. This segmentation reduces the overall mass moment of inertia, enabling smoother acceleration and deceleration. The segmented design is integrated into the molding process, making it manufacturable as a single piece without requiring complex post-assembly operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The design modifies geometric parameters of the impeller by introducing cutouts with specific shapes, sizes, and positions. These parameter changes optimize the mass distribution to reduce the mass moment of inertia while maintaining structural integrity. The cutout parameters are designed to be compatible with standard molding processes, balancing manufacturing feasibility with performance improvement.

Inventive Principle:

Principle #35Parameter changes

3Speed

If cutouts are added to reduce inertia, then the impeller can operate at lower speeds, but the structural integrity may be compromised

Engineering Contradiction:

Improverotational speedVSAvoidstructural integrity

Core Design Contradiction:

SpeedVSStrength

Solution Approach 1:

The cutouts are strategically positioned in regions of the support disk and blade elements where material removal has minimal impact on overall structural integrity. The design maintains adequate material thickness in critical load-bearing areas while removing mass from less critical regions. This local quality approach allows the impeller to operate at lower speeds with reduced inertia while preserving sufficient strength for safe operation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The cutouts are designed with curved or rounded edges rather than sharp corners to reduce stress concentration points. This curvature approach distributes mechanical stresses more evenly across the impeller structure, maintaining structural integrity despite material removal. The curved design also improves aerodynamic flow patterns, supporting efficient operation at reduced rotational speeds.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 results in a lighter, quieter, and more efficient fan impeller that can operate at lower speeds with improved airflow generation, reducing noise and enhancing therapy efficacy.

Implementation Method 1

the blade elements and/or the support disk (16) have at least one cutout (17)... the fan impeller has a particularly low inertia, such that the speed of rotation of the fan impeller can be adjusted particularly smoothly and with little expenditure in terms of power

Methodology Applied

Scientific EffectMass moment of inertia reduction: Moment of Inertia

Implementation Method 2

a fan for generating a respiratory air flow... a plurality of blade elements 4 which are arranged with their base 15 on the support disk 16 and starting from the hub extend in a radial direction to their blade tip 22

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentUS11925755B2Impeller with reduced mass inertia for a respiration therapy appliance

Publication Date: 2024.03.12 LOWENSTEIN MEDICAL TECH SA

AI summary

A respiration therapy appliance having a fan for generating a respiratory air flow for carrying out respiration therapy. The fan comprises at least one rotatable fan impeller having a plurality of blade elements which are arranged on a support disk. The blade elements and/or the support disk have at least one cutout.