Centrifugal Blower Casing with Logarithmic Volute for Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Centrifugal type blowers in air conditioning systems for vehicles face challenges in reducing noise generated by air impingement against the nose part while maintaining casing size limitations, as existing designs struggle to further minimize noise levels.
Innovation Solution
The design incorporates a centrifugal-type multiblade fan with a casing featuring an involuted shape, where the distance from the fan center to the side wall part increases logarithmically from the volute start to the end, with a second distance that initially exceeds and then matches the first distance, reducing noise by adjusting the air passage cross-sectional area in a logarithmic spiral manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the size of the casing from the outer edge of the fan to the side wall part at the nose part is increased, then the noise generated by air impingement against the nose part is reduced, but the amount of air blown is decreased
Solution Approach 1:
The patent applies local quality by creating different radial distance characteristics at different locations of the side wall part. Specifically, the radial distance from the fan center to the side wall part is made larger at the nose part region (first region) compared to other regions, while maintaining the overall casing size. This localized modification reduces air impingement noise at the nose part without significantly affecting the overall air flow capacity, thus resolving the contradiction between noise reduction and air blown amount.
2Object-affected harmful factors
If the casing size is increased to reduce noise, then the noise is reduced, but the casing upsizing is limited
Solution Approach 1:
The patent implements local quality by concentrating the noise-reducing feature (larger radial distance) specifically at the nose part region where air impingement occurs, while maintaining compact dimensions in other regions. The side wall part is designed with a first region (nose part) having a larger radial distance from the fan center, while other regions maintain smaller radial distances, thus reducing noise without requiring overall casing upsizing.
Solution Approach 2:
The patent applies dimensionality change by modifying the radial distance dimension specifically at the nose part region. Instead of increasing the overall casing volume, the design creates a localized dimensional change in the radial direction at the critical noise-generating area, achieving noise reduction through spatial reconfiguration rather than overall size increase.
3Object-affected harmful factors
If the air passage cross-sectional area changes suddenly, then the noise is reduced, but the air flow performance deteriorates
Solution Approach 1:
The patent applies curvature by designing the air passage with a smooth, gradual change in cross-sectional area rather than abrupt transitions. The side wall part is configured to provide a gradual increase in radial distance from the fan center toward the nose part, creating a curved, smooth transition in the air passage geometry. This curved design allows for progressive noise reduction while maintaining smooth air flow and preventing performance deterioration.
Solution Approach 2:
The patent implements preliminary action by gradually preparing the air passage cross-sectional area change from the beginning of the air passage toward the nose part. The radial distance is progressively increased rather than suddenly changed, allowing the air flow to adapt smoothly to the changing geometry. This gradual preliminary change prevents sudden flow separation and maintains air flow performance while achieving noise reduction.
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 noise from air impingement against the nose part while maintaining a balanced air flow, preventing performance deterioration due to sudden cross-sectional area changes, and alleviates casing upsizing constraints.
Implementation Method 1
a centrifugal-type multiblade fan (4) having a plurality of blades (21) around the rotatable shaft (2)
Implementation Method 2
The casing (5) has an involuted shape and accommodates the fan (4). The casing (5) includes a volute start part (7) and a volute end part (8) of the involuted shape
Data Source
AI summary
A centrifugal-type blower includes a shaft, a fan, and a casing. The casing includes an inlet, an air passage, and a side wall part. A first distance from a center of the fan to the wall part at an inlet side end portion in a radial direction of the fan gradually increases from a volute start part to a volute end part. A second distance from the center to the wall part at any position thereof from an intermediate position to a counter-inlet side end portion in the radial direction is larger than the first distance within a first range. The second distance gradually decreases from the volute start part to a predetermined position. The second distance has the same length as the first distance within a second range.