Indoor AC Drain Pan Structure for Unobstructed Natural Drainage

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Solution Overview

Problem

The existing drain pans in air-conditioning indoor units, made of foamed polystyrene beads, suffer from water leakage due to gaps between beads, and the use of a waterproof sheet with adhesive leads to adhesive mounds that obstruct drainage in natural drainage systems.

Innovation Solution

The design includes a drain pan with a socket mounting face and hole, a horizontal plate part, and a waterproof sheet covered with adhesive, where the top face of the edge portion of the horizontal plate part is positioned below the bottom face of the drain water collecting part, creating a step that prevents adhesive mounds and ensures effective drainage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a waterproof sheet with adhesive is used to prevent water leakage through bead gaps, then water leakage is prevented, but adhesive mounds are formed that obstruct natural drainage

Engineering Contradiction:
Improvewater leakage preventionVSAvoidnatural drainage function
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The drain pan is divided into a bead layer and a waterproof sheet layer, with the waterproof sheet segmented to have adhesive applied only at the peripheral edges rather than across the entire surface. This segmentation prevents adhesive mounds in the drainage area while maintaining waterproofing at the boundaries.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The adhesive application is localized to the peripheral edges of the waterproof sheet rather than being distributed uniformly. This local quality approach ensures waterproofing at the critical boundary areas where leakage occurs, while leaving the central drainage area free of adhesive obstructions.

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If foamed polystyrene beads are used to manufacture the drain pan, then manufacturing cost is reduced and moldability is improved, but water leakage occurs through gaps between beads

Engineering Contradiction:
Improvemoldability and costVSAvoidwater leakage prevention
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The drain pan combines foamed polystyrene beads with a synthetic resin waterproof sheet to create a composite structure. The bead layer provides the molded shape and cost benefits, while the waterproof sheet layer provides the necessary water tightness, combining the advantages of both materials.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

A thin waterproof sheet made of synthetic resin is introduced as a flexible barrier layer over the bead structure. This thin film effectively seals the gaps between beads without requiring changes to the bead manufacturing process, maintaining ease of manufacture while preventing water leakage.

Inventive Principle:
Principle #30Flexible shells and thin films

3Stability of the object's composition

If adhesive is applied to adhere the waterproof sheet to the drain pan body, then the waterproof sheet is securely fixed, but adhesive mounds are formed that block drain water flow

Engineering Contradiction:
Improvewaterproof sheet fixationVSAvoiddrain water flow
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The adhesive application area is segmented to be confined to the peripheral edges of the waterproof sheet, separating the fixation function from the drainage area. This ensures stable fixation of the waterproof sheet while preventing adhesive interference with water flow.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The peripheral edge region serves as an intermediary zone where the waterproof sheet meets the drain pan body. Adhesive is applied in this intermediate area to secure the waterproof sheet, while the central drainage area remains free of adhesive, allowing clear water flow path.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 enhances natural drainage by preventing adhesive blockages and maintaining efficient water flow, while also allowing for reduced adhesive usage in manufacturing.

Implementation Method 1

a waterproof sheet configured to cover an inner face and a bottom face of the drain pan body

Methodology Applied
Scientific EffectPhysical barrier (waterproof sheet):

Implementation Method 2

an adhesive that adheres the waterproof sheet to the drain pan body

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 3

when an air-conditioning indoor unit with a natural drainage system is used, such a mound may cause insufficient drainage of drain water

Methodology Applied
Scientific EffectGravity-driven flow: Gravitation

Data Source

PatentEP3647675B1Air conditioning indoor unit
Publication Date: 2023.04.05 MITSUBISHI ELECTRIC CORP
  • EP3647675B1 patent drawingFigure 1
  • EP3647675B1 patent drawingFigure 2~3
  • EP3647675B1 patent drawingFigure 4~5

AI summary

The air-conditioning indoor unit 100 includes: a cooler 21; and a drain pan 22 configured to receive drain water generated on a surface of the cooler 21 and drain the drain water to the outside. The drain pan 22 includes: a drain pan body 22a configured to receive the drain water, the drain pan body 22a including: a drain water collecting part 33 configured to gather the drain water; a socket mounting face 42 formed at a bottom face of the drain water collecting part 33; and a socket mounting hole 27 formed in an inner face 29 of the drain water collecting part 33 and in communication with the outside; a drain socket 34 including: a drain nozzle part 35 inserted into the socket mounting hole 27; and a horizontal plate part 41 placed on the socket mounting face 42; and a waterproof sheet 71 configured to cover an inner face and a bottom face of the drain pan body 22a; and an adhesive 72 that adheres the waterproof sheet 71 to the drain pan body 22a. A top face 41b of an edge portion 41a of the horizontal plate part 41 of the drain socket 34 is positioned below the bottom face 28 of the drain water collecting part 33.