Ceiling AC Drain Pan Sensor Layout for Refrigerant Leak Detection

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Solution Overview

Problem

Conventional ceiling-mounted air conditioning units with refrigerant circuits face challenges in reliably detecting refrigerant leakage without continuously running the indoor fan, leading to increased energy consumption and compromised user comfort.

Innovation Solution

The placement of a refrigerant leakage detection sensor between the outer surface of the drain pan's inner circumferential rim and the inner surface of the bell mouth allows for efficient detection of refrigerant leaks, reducing obstacles and improving detection accuracy and reliability, while also facilitating easier maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the refrigerant gas sensor is positioned on the outer surface of the bell mouth to detect refrigerant leakage, then the detection range is extended, but the detection reliability deteriorates due to large distance and obstacles from the leakage position

Engineering Contradiction:

Improvedetection rangeVSAvoiddetection reliability

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The sensor positioning moves from a horizontal arrangement (on the bell mouth outer surface) to a vertical arrangement (between drain pan rim and bell mouth inner surface), utilizing the vertical dimension to achieve both extended detection range and maintained reliability by positioning the sensor in the path of refrigerant gas accumulation

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If the indoor fan is operated continuously to enable refrigerant leakage detection, then the detection reliability is improved, but the energy consumption increases

Engineering Contradiction:

Improvedetection reliabilityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The sensor is pre-positioned in the optimal location between the drain pan rim and bell mouth inner surface where refrigerant gas accumulates, enabling reliable detection without requiring the fan to be running. This preliminary positioning of the sensor eliminates the need for continuous fan operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses the natural accumulation of refrigerant gas in the vertical space between the drain pan and bell mouth to enable detection, rather than requiring external assistance from the fan. The refrigerant gas itself serves to bring the detection target to the sensor location

Inventive Principle:

Principle #25Self-service

3Ease of manufacture

If the refrigerant gas sensor is positioned far from the refrigerant circuit piping to avoid interference, then the sensor placement is simplified, but the detection accuracy deteriorates due to distance and obstacles

Engineering Contradiction:

Improvesensor placement simplicityVSAvoiddetection accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The solution transitions from horizontal placement (on bell mouth outer surface) to vertical placement (between drain pan rim and bell mouth inner surface), utilizing the vertical dimension to achieve both ease of placement and high detection accuracy by positioning the sensor in the refrigerant gas accumulation zone

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 configuration enhances the detection efficiency and reliability of refrigerant leaks, reduces energy consumption by avoiding continuous fan operation, and minimizes maintenance costs by simplifying access to the sensor.

Implementation Method 1

a refrigerant leakage detection sensor for detecting refrigerant leaking from the refrigerant circuit

Methodology Applied

Scientific EffectGas detection:

Implementation Method 2

a fan accommodated in the casing to draw air in the air inlet through the heat exchanger and out of the at least one air outlet

Methodology Applied

Scientific EffectPressure difference driven flow: Pressure Gradient

Implementation Method 3

a heat exchanger being part of the refrigerant circuit... to draw air in the air inlet through the heat exchanger

Methodology Applied

Scientific EffectHeat transfer:

Implementation Method 4

a drain pan in a bottom portion of the casing... so that water dropping from the heat exchanger accumulates in the drain pan

Methodology Applied

Scientific EffectGravity: Gravitation

Data Source

PatentUS12130033B2Ceiling-mounted air conditioning unit for a heat pump comprising a refrigerant circuit with a refrigerant leakage sensor

Publication Date: 2024.10.29 DAIKIN INDUSTRIES LTD

AI summary

A ceiling-mounted air conditioning indoor unit for a heat pump including a refrigerant circuit, the ceiling-mounted air conditioning indoor unit includes: a casing including an air inlet and an air outlet; a drain pan in a bottom portion of the casing; a heat exchanger in the refrigerant circuit that is disposed above the drain pan such that water dropping from the heat exchanger accumulates in the drain pan; a fan in the casing that draws air in from the air inlet, through the heat exchanger, and out of the air outlet; a bell mouth at the air inlet that guides the air drawn-in to the fan; a refrigerant leakage detection sensor that detects refrigerant leaking from the refrigerant circuit. The drain pan includes a first rim and a second rim.