Asymmetric Impeller Blade Spacing for Dryer Noise Reduction
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Solution Overview
Problem
Conventional impeller assemblies in dryer appliances experience a spike in sound power level due to a consistent frequency as blades pass the cut-off edge between the volute and transition member, leading to noise issues.
Innovation Solution
The impeller assembly features a hub with a plurality of blades, where each pair defines unequal gaps along the circumferential direction, and the gap lengths are repeated sequentially, disrupting the consistent frequency and reducing sound power levels by optimizing the blade placement and clearance with the cut-off edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional impeller blades are arranged with equal spacing, then the impeller structure is simple and easy to manufacture, but a spike in sound power level occurs due to consistent frequency as blades pass the cut-off edge
Solution Approach 1:
The patent applies asymmetry by arranging impeller blades with unequal spacing, specifically positioning at least one blade at an asymmetric angle relative to the cut-off edge between the volute and transition member. This asymmetric arrangement disrupts the consistent frequency pattern that causes sound power level spikes, while maintaining manufacturing feasibility through defined angular positions.
2Productivity
If impeller blades are positioned to optimize air flow, then drying efficiency is improved, but sound power level increases due to blade interaction with the cut-off edge
Solution Approach 1:
The patent applies local quality by differentiating the angular positioning of specific blades relative to the cut-off edge. At least one blade is positioned at an asymmetric angle while others may maintain symmetric or different asymmetric positions. This localized variation in blade positioning optimizes air flow through specific regions while disrupting noise-generating frequency patterns at the cut-off edge interaction zone.
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 effectively reduces the spike in sound power level during operation, resulting in a quieter and more efficient impeller assembly while maintaining acceptable noise levels and efficiency.
Implementation Method 1
an impeller defining an axial direction, a radial direction, and a circumferential direction. The impeller is rotatable about the axial direction and is positioned within the volute of the housing... The impeller is in mechanical communication with the motor and is rotatable with the motor in order to urge a flow of air from the volute to the transition member
Data Source
AI summary
An impeller assembly including a housing and an impeller is provided. The impeller is positioned within a volute of the housing and includes a hub and a plurality of blades. The plurality of blades are spaced about the hub along a circumferential direction of the impeller. The plurality of blades include a first pair of blades and a second pair blades. The first pair blades defines a first gap along the circumferential direction at a radially outer portion, and the second pair blades defines a second gap along the circumferential direction at a radially outer portion. The first gap is unequal to the second gap in order to reduce an amount of noise generated by the impeller assembly.