Cross-Flow Fan Air Passage Restriction for Stable, Low-Noise Airflow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing air conditioners with cross flow fans face issues with unstable air flow and noise due to dust accumulation and side wall resistance, which are not adequately addressed by previous solutions that use protrusions and two-stage level differences, as these methods do not completely eliminate turbulence and noise.
Innovation Solution
The air conditioner incorporates a restricting section at the corner of the air passage wall with a gradually enlarged cross-sectional shape, minimizing the enlargement ratio of the air passage sectional area from the upstream to the downstream side, using a smooth restricting surface to stabilize air flow and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the air passage sectional area is expanded from upstream to downstream to improve air blowing efficiency, then the air blowing efficiency is improved, but the air flow becomes unstable and noise increases due to side wall resistance
Solution Approach 1:
The patent applies local quality by providing a restricting section only at the corner sections of the side walls in the downstream area, rather than uniformly restricting the entire air passage. This localized restriction stabilizes air flow near the side walls where instability occurs, while maintaining the overall expansion of the air passage for efficient air blowing.
Solution Approach 2:
The restricting section is formed with a smooth curved surface instead of sharp edges, and the cross-sectional shape is gradually enlarged from upstream to downstream. This curved design eliminates turbulent flow caused by sharp corners while still restricting the air passage sectional area to stabilize air flow.
2Object-generated harmful factors
If protrusions are provided at the side walls to smooth peeled flow, then noise is reduced, but turbulent flow is generated at the corner sections and air flow instability remains
Solution Approach 1:
The restricting section is formed with a smooth curved surface that gradually enlarges from upstream to downstream, eliminating sharp corners that generate turbulent flow. This curved design smoothly guides air flow while restricting the passage area, thereby reducing noise and stabilizing air flow simultaneously.
Solution Approach 2:
The patent changes the geometric parameters of the air passage by providing a restricting section that gradually enlarges the cross-sectional shape from upstream to downstream. This gradual parameter change smooths air flow transitions and eliminates turbulent flow at corner sections.
3Productivity
If the air passage sectional area is significantly expanded to reduce air-blowing resistance, then air blowing efficiency improves, but static pressure near side walls decreases causing reverse air flow and noise
Solution Approach 1:
The restricting section is provided only at the corner sections of the side walls rather than uniformly throughout the air passage. This localized restriction maintains static pressure near the side walls to prevent reverse air flow, while allowing the overall air passage to expand for efficient air blowing.
Solution Approach 2:
The patent applies partial action by providing restriction only where needed (at the corner sections) rather than throughout the entire air passage. This partial restriction is sufficient to stabilize air flow and maintain static pressure, while minimizing impact on overall air blowing efficiency.
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 stabilizes air flow near the side walls, increases static pressure, and minimizes air-blowing resistance, effectively reducing noise and maintaining air blowing efficiency.
Implementation Method 1
a restricting section that is provided at a corner section of a side wall of the air passage wall... and having a shape by which, in the downstream area of the cross flow fan, the air passage sectional area expanding from the upstream side to the downstream side is restricted so as to reduce an enlargement ratio of the air passage sectional area
Implementation Method 2
the restricting section has a smooth restricting surface crossing the corner section of the rectangular cross-section of the air passage
Implementation Method 3
the cross-sectional shape of the restricting surface is set to be gradually enlarged from the upstream side to the downstream side of the air flow
Data Source
AI summary
An air conditioner includes: an air passage extending from a suction port to a blowout port, a heat exchanger at the upstream side of the air passage, a cross flow fan in the air passage on the downstream side of the heat exchanger, and an air passage wall provided in a downstream area of the cross flow fan to reach the blowout port. A restricting section that restricts an air passage sectional area is provided at a corner section of the side wall of the air passage wall. The restricting section has a shape by which the air passage sectional area has a rectangular cross section expanding from the upstream side to the downstream side and is restricted to reduce an enlargement ratio of the air passage sectional area. Further, the restricting section has a smooth restricting surface crossing the corner section of the cross section of the air passage.