Vehicle Air Conditioning Blower Projections for Burble Noise Reduction
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Solution Overview
Problem
Existing vehicle air conditioning apparatuses fail to effectively reduce noise caused by burble, which is a result of air flow separation and whirl formation in enlarged air channels, leading to aerodynamic noise.
Innovation Solution
Incorporating a cylindrical portion with an enlarged section featuring a projecting wall that includes plate-shaped projections inwardly directed within the air channel, where the projections intersect the air flow direction, and a tapered shape to prevent whirl flow formation and enhance condensed water drainage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cross-sectional area of the air channel is enlarged, then the air flow capacity is improved, but burble and whirl flow are generated causing noise
Solution Approach 1:
The patent applies preliminary action by providing projections on the inner wall surface of the enlarged portion before the air flow separates and forms burble. These projections pre-adjust the air velocity distribution and guide the air flow to attach to the wall surface, preventing the formation of whirl flow and noise before they can occur.
Solution Approach 2:
The patent applies local quality by providing projections only at specific locations within the enlarged portion where air flow separation is most likely to occur. The projections are strategically positioned to locally modify the air velocity distribution and prevent burble formation, rather than uniformly modifying the entire air channel.
2Object-generated harmful factors
If projections are provided on the inner wall surface to adjust air velocity distribution, then noise is reduced, but the structure becomes more complex
Solution Approach 1:
The patent applies parameter changes by carefully optimizing the geometric parameters of the projections, including their size, shape, spacing, and position. By adjusting these parameters, the patent achieves effective noise reduction while keeping the projection structure simple and easy to manufacture, avoiding excessive structural complexity.
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 solution significantly reduces noise generated by burble and improves condensed water drainage efficiency by preventing whirl flow and optimizing air flow distribution, as confirmed by CFD analysis.
Implementation Method 1
burble which is an air flow separated from an inner wall surface of a case is generated. The burble forms a whirl flow
Implementation Method 2
A technology for reducing an aerodynamic sound generating by air turbulence by providing a plurality of projections on the wall surface of the air channel is disclosed
Implementation Method 3
the cylindrical portion has a tapered shape whereof a cross-sectional area is increased gradually toward the downstream side
Data Source
Figure 1
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Figure 4~5
AI summary
A vehicle air conditioning apparatus in which a noise caused by burble is reduced is provided. The vehicle air conditioning apparatus 1 includes: a case 10 having an air channel 11 in an interior thereof; a blower configured to supply blown air to the air channel 11, the case 10 includes a cylindrical portion 12 and an enlarged portion continued from the cylindrical portion 12 on a downstream side and having a cross-sectional area larger than a cross-sectional area of the cylindrical portion 12, the enlarged portion includes a projecting wall 14 having a wall surface projecting outward of the air channel 11, the projecting wall 14 includes at least one projection 15 projecting inward of the air channel 11, and a top portion of the projection 15 is in contact with a side surface of an virtual cylinder 16, which is formed by extending the inner wall surface of the cylindrical portion in the virtually extended toward the downstream, or is provided on the projecting wall side with respect to the side surface of the virtual cylinder 16.