Air Conditioner Multi-Mode Temperature Detection Using Single Sensor

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional air conditioners face reliability issues due to improper temperature detection during high-load cooling and heating operations, leading to potential compressor loss, and require additional sensors that increase costs.

Innovation Solution

An air conditioner design where a temperature detecting means for evaporation completion in the auxiliary heat exchanger also detects condensation temperature in heating and evaporation temperature in cooling, positioned downstream of the auxiliary heat exchanger, allowing for proper temperature determination and avoiding unstable operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If additional sensors are provided to detect condensation temperature in heating operation and/or evaporation temperature in cooling operation, then temperature detection accuracy is improved, but device cost increases

Engineering Contradiction:
Improvetemperature detection accuracyVSAvoidsensor quantity and cost
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements universality by designing a single temperature sensor that performs multiple detection functions across different operational modes. The same sensor detects evaporation completion during dehumidification, condensation temperature during heating, and evaporation temperature during cooling. This multi-functional approach eliminates the need for separate sensors for each function, thereby reducing device complexity and cost while maintaining comprehensive temperature monitoring capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the functions of multiple potential sensors into a single temperature detection device. By combining evaporation completion detection, condensation temperature detection, and evaporation temperature detection into one sensor system, the patent reduces the total number of components required. This consolidation achieves the same comprehensive temperature monitoring function that would otherwise require multiple separate sensors, thereby reducing cost and simplifying the device.

Inventive Principle:
Principle #5Merging (Combining)

2Measurement precision

If the sensor detects temperature near the auxiliary heat exchanger outlet, then evaporation completion is detected, but liquid may be sucked by the compressor during heating operation due to subcooling

Engineering Contradiction:
Improveevaporation completion detectionVSAvoidcompressor reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent applies dynamics by adaptively interpreting sensor readings based on operational mode. During heating operations, the system dynamically adjusts its understanding of the temperature signal to account for subcooling effects, recognizing that the detected temperature will be lower than actual condensation temperature. This dynamic interpretation prevents erroneous control actions that could lead to liquid suction by the compressor, thereby maintaining reliability while preserving evaporation completion detection capability.

Inventive Principle:
Principle #15Dynamics

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 solution enables accurate temperature detection, preventing compressor loss and reducing costs by utilizing a single sensor for multiple temperature readings, while enlarging the evaporation region of the auxiliary heat exchanger.

Implementation Method 1

A temperature detecting means for detecting completion of the evaporation of the liquid refrigerant in the auxiliary heat exchanger is disposed downstream of the auxiliary heat exchanger

Methodology Applied
Scientific EffectTemperature detection:

Implementation Method 2

the auxiliary heat exchanger includes an evaporation region where the liquid refrigerant evaporates

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

a refrigerant evaporates only in the auxiliary heat exchanger to locally perform dehumidification

Methodology Applied
Scientific EffectHeat absorption:

Implementation Method 4

an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are connected to one another

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 5

an expansion valve, and an indoor heat exchanger are connected to one another

Methodology Applied
Scientific EffectPressure reduction: Pressure Drop

Data Source

PatentEP2857768B1Air conditioner
Publication Date: 2020.08.26 DAIKIN INDUSTRIES LTD
  • EP2857768B1 patent drawingFigure 1
  • EP2857768B1 patent drawingFigure 2
  • EP2857768B1 patent drawingFigure 3

AI summary

In addition to a sensor for detecting the completion of the evaporation of a liquid refrigerant, there is a need to provide a sensor for detecting a condensation temperature in a heating operation and/or an evaporation temperature in the cooling operation. In an air conditioner of the present invention, an indoor heat exchanger includes an auxiliary heat exchanger 20 and a main heat exchanger 21 disposed leeward from the auxiliary heat exchanger 20. In an operation in a predetermined dehumidification operation mode, a liquid refrigerant supplied to the auxiliary heat exchanger 20 all evaporates midway in the auxiliary heat exchanger 20. Therefore, only an upstream partial area in the auxiliary heat exchanger 20 is an evaporation region, while an area downstream of the evaporation region in the auxiliary heat exchanger 20 is a superheat region. Further, an indoor heat exchanger temperature sensor 32 is disposed leeward from the superheat region of the auxiliary heat exchanger 20 and in or in the vicinity of a middle portion of the indoor heat exchanger.