Outdoor Unit Bottom Plate Drainage for Defrost Re-Freeze Prevention

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Solution Overview

Problem

The existing outdoor units of air conditioning devices face challenges in efficiently discharging drainage fluid from the outdoor heat exchanger during defrosting without compromising the strength of the bottom plate, as drainage holes formed away from the point of fluid generation risk freezing again before reaching the discharge points.

Innovation Solution

The outdoor unit features a bottom plate with expanded portions to mount the heat exchanger, including first drainage holes for efficient discharge and second smaller holes under the heat exchanger, ensuring prompt fluid discharge while maintaining structural integrity by concentrating drainage holes under the heat exchanger and forming them in a way that aligns with airflow patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If drainage holes are increased in area under the heat exchanger, then drainage fluid discharge efficiency is improved, but bottom plate strength is reduced

Engineering Contradiction:
Improvedrainage fluid discharge efficiencyVSAvoidbottom plate strength
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The drainage hole is divided into multiple segments (first drainage holes and second drainage holes) distributed across different locations under the heat exchanger. This segmentation allows the total drainage area to be increased while each individual hole remains small enough to maintain bottom plate strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different types of drainage holes are created at different locations: first drainage holes with larger area are positioned where drainage fluid flow is highest, while second drainage holes with smaller area are positioned at other locations. This local differentiation optimizes discharge efficiency while preserving structural integrity.

Inventive Principle:
Principle #3Local quality

2Device complexity

If drainage holes are positioned away from the point where drainage fluid is dropped, then bottom plate structure is simplified, but drainage fluid may freeze before reaching discharge points

Engineering Contradiction:
Improvebottom plate structureVSAvoiddrainage fluid discharge reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

Drainage holes are pre-positioned directly under the heat exchanger at the exact location where drainage fluid is dropped during defrosting. This preliminary positioning ensures that drainage fluid immediately enters the holes without traveling across the bottom plate, preventing re-freezing and ensuring reliable discharge.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2787289B1Outdoor machine for an air-conditioning device
Publication Date: 2016.04.06 DAIKIN INDUSTRIES LTD
  • EP2787289B1 patent drawingFigure 1
  • EP2787289B1 patent drawingFigure 2
  • EP2787289B1 patent drawingFigure 3

AI summary

An outdoor unit 2 of an air conditioning device 1 in which a heat exchanger 13 is arranged in a bottom plate 30 in a substantially rectangular parallelepiped shape casing 22 including a top plate 31, side plates 44, 54 and 55, and the bottom plate 30 is provided. The heat exchanger 13 is mounted on a plurality of expanded portions 60 formed in the bottom plate 30. A first drainage hole 63 through which a drainage fluid from the heat exchanger 13 is discharged to an exterior is formed in each of the expanded portions 60, and a second drainage hole 65 smaller than the first drainage hole 63 is formed in the bottom plate 30 under the heat exchanger 13 excluding the expanded portions 60.