Impeller with Unique Pitch Angles for Centroid Balance
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Solution Overview
Problem
Conventional impellers with uneven pitch angles to reduce noise suffer from centroid balance issues due to methods of distributing pitch angles, leading to ineffective noise dispersion and potential imbalance.
Innovation Solution
An impeller design with Z blades, where each blade has a unique pitch angle calculated using specific expressions to ensure all pitch angles between adjacent blades are different, maintaining centroid balance while dispersing sound frequencies effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If pitch angles are made uneven to disperse sound frequencies, then noise reduction is improved, but centroid balance is lost
Solution Approach 1:
The patent applies asymmetry by setting different pitch angles for adjacent blades to disperse sound frequencies and reduce noise. Specifically, the pitch angle of each blade is designed to be different from its adjacent blades, creating an asymmetric configuration that effectively disperses the frequency of wind noise generated during rotation.
Solution Approach 2:
The patent uses counterweight by introducing a balancing blade that compensates for the centroid imbalance caused by uneven pitch angle distribution. The balancing blade is positioned and dimensioned to offset the gravitational and centrifugal forces created by the asymmetric pitch angle configuration, thereby maintaining centroid balance during rotation.
2Object-affected harmful factors
If pitch angles are distributed unevenly, then sound frequency dispersion is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by systematically varying the pitch angle parameter across different blades according to a specific distribution pattern. The pitch angles are designed to satisfy specific mathematical relationships (α1 + α2 < 2θ and |α1 - α2| < Δθ) to achieve effective noise dispersion while maintaining manufacturability through controlled parameter variation.
3Object-affected harmful factors
If all pitch angles are made different, then noise dispersion is maximized, but structural symmetry is reduced
Solution Approach 1:
The patent deliberately introduces asymmetry in pitch angle configuration to maximize noise dispersion. Each blade is assigned a unique pitch angle within specific constraints, creating an asymmetric structure that effectively breaks up the coherence of noise waves and reduces peak amplitude.
Solution Approach 2:
The patent applies local quality by making each blade's pitch angle unique while maintaining overall structural integrity. The local variation in pitch angles is confined to specific ranges and relationships, allowing each blade to contribute differently to noise reduction while the overall structure maintains functional symmetry for balanced operation.
Data Source
AI summary
An impeller includes Z blades, where Z is an integer equal to 5 or more, arranged in a circumferential direction of the impeller and extending radially, and pitch angles between adjacent blades are all different. In terms of an arbitrary pitch angle θ, when a pitch angle α1 adjacent to the pitch angle θ, and a pitch angle α2 adjacent to the pitch angle θ, different from the pitch angle α1, satisfy a relation, α1<α2, a pitch angle β1 different from the pitch angle θ adjacent to the pitch angle α1 and a pitch angle β2 adjacent to the pitch angle α2, different from the pitch angle θ, satisfy a relation, β2<β1.