Blower Unit Air Guide Plate Noise Reduction
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Solution Overview
Problem
Portable, handheld blower units with electric drive motors experience noise pollution due to axial noise excitation from the blower, which is not effectively mitigated by existing designs.
Innovation Solution
An air guide plate with external dimensions greater than the intake opening is positioned in front of the intake opening, deflecting intake air by at least 90° and forming a gap that reduces noise emissions by reflecting sound waves back into the receiving space, while an air supply channel with a deflection angle of up to 180° provides a large air intake surface, and a sound-insulating lining on the air guide cone further reduces noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an air guide plate with external dimensions greater than the intake opening is positioned in front of the intake opening, then noise emissions are reduced by reflecting sound waves back into the receiving space, but the device complexity increases
Solution Approach 1:
The air guide plate serves as an intermediary element positioned between the external environment and the intake opening. It reflects sound waves back into the receiving space while allowing air intake through the circumferential gap, thereby mediating between noise reduction requirements and air supply needs without requiring complex active noise control systems
Solution Approach 2:
The air guide plate extends in the axial direction beyond the intake opening plane, utilizing the third dimension (axial depth) to create sound wave reflection paths. By positioning the plate at a specific axial distance and extending it radially beyond the intake opening diameter, it creates a three-dimensional sound reflection geometry that reduces noise without blocking air intake
2Object-affected harmful factors
If the air guide plate is positioned at an axial distance in front of the intake opening with external dimensions greater than the intake opening, then a large air intake surface is provided reducing intake noise, but the gap for air supply becomes more complex to design
Solution Approach 1:
The air intake function is segmented into two distinct paths: (1) the circumferential gap between the air guide plate and housing providing primary air supply, and (2) the deflected air path through the receiving space providing secondary air intake. This segmentation allows each path to be optimized independently for noise reduction while maintaining adequate air supply
3Object-affected harmful factors
If intake air is deflected through a deflection angle of at least 90° by the air guide plate, then noise emissions are reduced, but the air flow path becomes more complex
Solution Approach 1:
The air guide plate employs curved or angled surfaces that gradually deflect the air flow through 90° or more, rather than using sharp edges or abrupt changes. This curved deflection path reduces turbulence and flow separation, maintaining smooth air flow while achieving the noise reduction benefit of deflecting air away from the intake opening
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 significantly reduces operating noise emissions by deflecting and absorbing sound waves, creating a larger air intake surface and incorporating sound insulation, thereby minimizing noise pollution.
Implementation Method 1
the noise emissions of the axial blower are reflected in the direction of the receiving space by the air guide plate
Implementation Method 2
the entering intake air has to be deflected through a deflection angle of at least 90°
Implementation Method 3
a sound-insulating lining on the air guide cone further reduces noise
Data Source
AI summary
A blower unit for a portable handheld blower apparatus has a housing section and a tubular receiving space, formed in the housing section, with a first axial end and a second axial end and with a longitudinal center axis. Arranged in the receiving space of the housing section is an axial blower for generating a blower air flow, the axial blower being driven by a drive motor. The receiving space has an intake opening at its first axial end and a discharge opening at its second axial end. In order to reduce operating noise, an air guide plate is arranged at an axial distance in front of the intake opening, the air guide plate having external dimensions that are greater than the external dimensions of the intake opening. An annular gap that supplies intake air is formed between the air guide plate and an outer periphery of the housing section.