Capacitive Condensate Level Sensing for Air Conditioner Drain Pump Control

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Solution Overview

Problem

Conventional air conditioners face issues with water level sensing devices malfunctioning due to foreign matter attachment and inability to accurately detect condensed water levels, leading to inefficient drainage pump operation.

Innovation Solution

A method using a water level sensing device with electrode pads that sense capacitance without direct contact with condensed water, allowing for accurate level detection and control of the drainage pump based on sensed capacitance, operating conditions, and dehumidification recommendations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a float-based water level sensing device directly contacts condensed water, then the device can sense the water level, but foreign matter attaches to the float causing malfunction

Engineering Contradiction:
Improvewater level detection accuracyVSAvoidsensing device reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent introduces an intermediary mechanism (capacitive sensing through electrode pads) that allows the sensing device to detect water level without direct contact. The electrode pads sense changes in capacitance caused by the presence of condensed water, acting as a mediator between the sensing system and the water, thereby preventing foreign matter attachment while maintaining detection accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical float-based sensing system with a capacitive sensing system using electrode pads. This substitution eliminates the mechanical components that are susceptible to foreign matter attachment, using electrical field-based detection instead, thereby improving reliability while maintaining measurement precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If the magnetic sensor only senses when float reaches predetermined height, then the device structure is simple, but it cannot detect water levels below the predetermined height

Engineering Contradiction:
Improvesensing device structureVSAvoidwater level detection range
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the water level sensing into multiple discrete detection points using separate electrode pads positioned at different heights. Each electrode pad can independently detect water level at its specific position, creating segmented detection zones that collectively provide comprehensive water level monitoring throughout the drainage tank.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-point detection approach to a distributed multi-point detection system. By placing electrode pads at different vertical positions, the system adds spatial dimensionality to the sensing capability, enabling detection across multiple water level thresholds rather than a single predetermined height.

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

3Measurement precision

If the drainage pump operates frequently to maintain low water level, then water level control is precise, but power consumption and noise increase

Engineering Contradiction:
Improvewater level control accuracyVSAvoiddrainage pump power consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent implements preliminary action by detecting water level accumulation trends in advance using multiple electrode pads. The controller monitors capacitance changes over time and predicts when the water level will reach critical thresholds, allowing the drainage pump to operate proactively before overflow occurs, rather than reactively responding to each level threshold.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent employs periodic action by implementing interval-based water level monitoring and pump operation. Instead of continuous pump operation, the system checks water levels at predetermined intervals using the electrode pads and operates the drainage pump periodically only when necessary, reducing overall power consumption and noise while maintaining adequate water level control.

Inventive Principle:
Principle #19Periodic action

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 approach prevents malfunctions, optimizes drainage pump operation, reduces noise and power consumption, and provides accurate sensing of condensed water levels and flow rates, enabling efficient drainage and dehumidification control.

Implementation Method 1

a plurality of electrode pads disposed in the water level sensing housing, in a state of not contacting the condensed water, for sensing capacitance of the condensed water

Methodology Applied
Scientific EffectCapacitance sensing: Capacitance

Data Source

PatentEP2985544B1Method of controlling air conditioner and air conditioner controlled thereby
Publication Date: 2020.02.19 LG ELECTRONICS INC
  • EP2985544B1 patent drawingFigure 1
  • EP2985544B1 patent drawingFigure 2
  • EP2985544B1 patent drawingFigure 3

AI summary

Disclosed is a method of controlling an air conditioner including a step of sensing the capacitance of condensed water through any one of a plurality of electrode pads to sense the level of the condensed water during cooling, and a step of operating a drainage pump based on the level of the condensed water sensed through any one of the electrode pads to drain the condensed water stored in the condensed water storage part. A water level detecting device of the air conditioner more accurately senses the level of condensed water based on the capacitance of the condensed water, thereby effectively controlling the drainage pump.