Cross-Flow Fan Layout for Surge-Resistant Indoor Airflow

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Solution Overview

Problem

Recent air-conditioning indoor machines face challenges in achieving higher surging proof stress and energy conservation while operating at lower rotational speeds and increased static pressure, with existing designs experiencing backflow and increased fan power.

Innovation Solution

The air-conditioning indoor machine incorporates a cross-flow fan with a specific arrangement of a stabilizer and rear guider, where the angles between the fan-referencing horizontal line and other lines satisfy certain relational expressions, optimizing airflow and reducing backflow, and positions the heat exchanger sections to enhance air flow and energy efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the cross-flow fan diameter is increased to achieve higher air volumes at lower rotational speeds, then energy conservation is improved, but surging proof stress deteriorates due to increased static pressure

Engineering Contradiction:
Improveenergy conservationVSAvoidsurging proof stress
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent optimizes geometric parameters of the stabilizer and rear guider (angles θa, θb, θ0) to change the airflow field characteristics, enabling the system to maintain both low rotational speed operation and high surging proof stress performance

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The stabilizer and rear guider act as intermediary components that mediate between the cross-flow fan and the airflow, controlling the airflow path to prevent backflow and surging while maintaining energy efficiency

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the stabilizer is positioned higher to improve structural stability, then stability is improved, but air flow from the lower part of the heat exchange section to the cross-flow fan is inhibited, increasing fan power

Engineering Contradiction:
Improvestructural stabilityVSAvoidfan power
Core Design Contradiction:
Stability of the object's compositionVSPower

Solution Approach 1:

The patent specifies precise angular parameters (θa - θ0) > 16° and (θb - θ0) < 26° to optimize the position of the stabilizer, achieving both structural stability and minimal airflow restriction

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent divides the stabilizer into a top part and a bottom part with a tongue part in between, creating a three-dimensional structure that provides stability while leaving space for airflow passage

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 arrangement improves surging proof stress and energy conservation by minimizing airflow loss and fan power, while allowing for increased air flow to the heat exchanger sections, resulting in a more efficient and energy-saving performance.

Implementation Method 1

The cross-flow fan has a plurality of blades aligned along the circumference, and generates an air flow

Methodology Applied
Scientific EffectFluid flow generation by rotating blades: Fan

Implementation Method 2

The interior of an indoor machine accommodates a heat exchanger for conducting heat exchange between a refrigerant and air

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentEP3088806B1Indoor air conditioner
Publication Date: 2018.04.18 DAIKIN INDUSTRIES LTD
  • EP3088806B1 patent drawingFigure 1
  • EP3088806B1 patent drawingFigure 2
  • EP3088806B1 patent drawingFigure 3

AI summary

To provide both surging proof stress and energy conservation properties in a wall-mounted air-conditioning indoor machine, a stabilizer (17), a rear guider (18), and a cross-flow fan (30) are arranged so that three expressions, (θa - θ0) &gt; 16°, 17° &lt; (θb - θ0) &lt; 26°, and θb ≥ θa, are satisfied by a reference angle (θ0) formed by a fan-referencing horizontal line (L1) and a scroll-referencing line (L2), a first angle (θa) formed by the fan-referencing horizontal line (L1) and a first straight line (SL1) connecting a fan center point (O) and a front-surface-side closest point (P7) of the stabilizer (17), and a second angle (θb) formed by the fan-referencing horizontal line (L1) and a second straight line (SL2) connecting the fan center point (O) and a back-surface-side closest point (P8) of the rear guider (18).