Cross-Flow Fan Outlet Structure for Compact Air Conditioner Indoor Units
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Solution Overview
Problem
Increasing the outer diameter of the impeller in a cross-flow fan to reduce power consumption and noise is hindered by the need to maintain the height dimension of the indoor unit, which can decrease the blow-out flow path and affect performance.
Innovation Solution
The indoor unit design includes a cross-flow fan with a blow-out flow path formed by walls that project out of the outlet, increasing the cross-sectional area downward, and a movement mechanism to switch between projected and stored states, maintaining performance and aesthetics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the outer diameter of the impeller is increased to reduce power consumption and noise, then power consumption and noise are reduced, but the blow-out flow path region is decreased and performance deteriorates
Solution Approach 1:
The patent extends the blow-out flow path in the vertical direction by having the lower wall project out of the outlet, compensating for the reduced horizontal space caused by the larger impeller diameter. This dimensional extension maintains sufficient diffuser length and flow path area despite the space constraints, resolving the contradiction between larger impeller size and maintained performance.
2Use of energy by moving object
If the outer diameter of the impeller is increased to reduce power consumption and noise, then power consumption and noise are reduced, but the height dimension of the indoor unit must be increased which hinders installation
Solution Approach 1:
Instead of increasing the height dimension of the indoor unit main body, the patent utilizes the outlet direction as an alternative dimension to extend the blow-out flow path. The lower wall projects out of the outlet, effectively using the horizontal outlet space to compensate for the larger impeller, thereby avoiding height increase and maintaining ease of installation.
3Reliability
If the blow-out flow path is extended to maintain performance with larger impeller, then performance is maintained, but air flow resistance increases and backflow occurs causing surging
Solution Approach 1:
The patent applies different wall configurations at different locations of the blow-out flow path. The lower wall projects out of the outlet to extend the flow path and reduce resistance, while the upper wall is positioned to restrict upward flow and prevent backflow. This localized differentiation of wall functions resolves the contradiction between extending the flow path for performance and preventing backflow.
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 design reduces power consumption and noise while preventing surging and maintaining air volume and pressure, even with a larger impeller diameter, by extending the blow-out flow path and restricting backflow.
Implementation Method 1
The heat exchanger performs heat exchange on air drawn in from the inlet
Implementation Method 2
The cross-flow fan is configured to blow out air, which has undergone heat exchange performed by the heat exchanger, from the outlet
Data Source
AI summary
This indoor unit of an air conditioner includes an indoor unit main body having an inlet and an outlet; a heat exchanger; and a cross-flow fan configured to blow out air, which has undergone heat exchange by the heat exchanger. The cross-flow fan has a blow-out flow path that is configured such that a cross-sectional area gradually increases downward, with the blow-out flow path guiding blown-out air to the outlet. When a distance in the lower wall from an intersection, where a tangent inscribing a tongue of the cross-flow fan orthogonally intersects the lower wall, to a lower end of the indoor unit main body is referred to as distance L, a ratio (L/D) of the distance L to outer diameter D of an impeller of the cross-flow fan is less than 0.05. At least part of the blow-out flow path is formed to project out of the outlet at least when air conditioning operation is performed.