Expansion Valve Closure Sensing in Air Conditioning Control
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Solution Overview
Problem
Existing air conditioning apparatuses face challenges in precisely determining when the expansion valve reaches a fully closed state, leading to potential cessation of refrigerant flow and impaired air-cooling operations, especially when refrigerant temperatures are high, due to unclear temperature changes.
Innovation Solution
The apparatus employs a controller with liquid-side and gas-side temperature sensors to detect refrigerant temperatures and pressure sensors to determine the evaporation temperature, using these readings to set threshold conditions for precise closed-valve sensing, including multiple conditions to account for varying refrigerant states and ambient temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the expansion valve opening degree is controlled to reach fully closed state based on temperature change detection, then the refrigerant flow rate regulation range is expanded to low opening degree, but the closed-valve sensing precision deteriorates when refrigerant temperature is high
Solution Approach 1:
The patent changes the detection parameter from simple temperature change to a composite parameter combining temperature difference (between inlet and outlet of expansion valve) and refrigerant temperature. This allows the system to maintain closed-valve sensing precision across different refrigerant temperature conditions while keeping the expansion valve regulation range extended to low opening degrees.
Solution Approach 2:
The patent introduces an intermediary detection mechanism that measures both the temperature difference across the expansion valve and the refrigerant temperature itself. This intermediary information serves as a mediator to accurately determine valve closure state even when direct temperature change detection fails at high temperatures.
2Adaptability or versatility
If the expansion valve reaches fully closed state, then the refrigerant flow rate is reduced to expand control range, but the air-cooling operation reliability deteriorates due to potential refrigerant flow cessation
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the temperature difference and refrigerant temperature, compares them against predetermined conditions, and adjusts the expansion valve opening degree accordingly. This feedback loop prevents the valve from reaching full closure and ensures refrigerant flow continues, maintaining air-cooling operation reliability while expanding the control range.
Solution Approach 2:
The patent takes preliminary action by detecting the tendency toward valve closure through temperature difference and temperature monitoring before the valve actually reaches the fully closed state. This allows the controller to preemptively adjust the valve opening degree to prevent refrigerant flow cessation, thereby maintaining system reliability.
3Device complexity
If the temperature of refrigerant in outlet of expansion valve is used for closed-valve sensing, then the sensing method is simple, but the sensing precision deteriorates when refrigerant temperature is high due to unclear temperature change
Solution Approach 1:
The patent changes the sensing parameters from a single temperature measurement to two parameters: the temperature difference across the expansion valve and the refrigerant temperature. This parameter change maintains relatively simple sensing implementation while significantly improving closed-valve sensing precision across all temperature conditions.
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 enables more accurate closed-valve sensing, preventing refrigerant flow cessation and ensuring reliable air-cooling operations even when refrigerant evaporation temperatures are high, by using a combination of temperature and pressure-based conditions.
Implementation Method 1
a liquid-side temperature sensor to detect the refrigerant temperature in an inlet or an intermediate part of the indoor heat exchanger
Implementation Method 2
a gas-side temperature sensor to detect the refrigerant temperature in an outlet of the indoor heat exchanger
Implementation Method 3
an intake pressure sensor to detect refrigerant pressure in an intake side of the compressor
Implementation Method 4
refrigerant is circulated sequentially through the compressor, the outdoor heat exchanger, the expansion valve, and the indoor heat exchanger
Data Source
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AI summary
In an air conditioning apparatus (1), an expansion valve (41a-41c) is determined to be in a fully closed state when a refrigerant temperature in an outlet of an indoor heat exchanger (42a-42c) as detected by a gas-side temperature sensor (46a-46c), and a refrigerant temperature in an inlet or an intermediate part of the indoor heat exchanger (42a-42c) as detected by a liquid-side temperature sensor (45a-45c) satisfy a closed-valve condition in relation to a refrigerant evaporation temperature obtained by converting a refrigerant pressure in an intake side of a compressor (21) as detected by an intake pressure sensor (29) to a refrigerant saturation temperature, and in relation to an air temperature of an air-conditioned space cooled by the indoor heat exchanger (42a-42c), the air temperature being detected by an indoor temperature sensor (47a-47c).