Expansion Valve Control for Stable Air Conditioner Heating
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Solution Overview
Problem
The existing air conditioner systems face instability and liquid backflow issues due to the uniform set opening of the electronic expansion valve for heating, which leads to refrigerant suction shortages and operational instability when the compressor's rotation speed changes.
Innovation Solution
An air conditioner with a refrigerant circuit that includes an expansion valve control unit to adjust the set opening of the electronic expansion valve for heating based on the compressor's rotation speed, using a target value correction control unit to manage supercooling and superheating degrees independently, preventing liquid backflow and refrigerant shortages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electronic expansion valve for heating is opened to a set opening or larger to secure refrigerant suction when the compressor operates at high speed, then the refrigerant suction amount is sufficient, but when the compressor speed decreases, the valve takes time to restrict to the necessary opening, causing liquid back flow and operational instability
Solution Approach 1:
The patent applies dynamics by making the set opening of the electronic expansion valve for heating variable rather than fixed. The control unit dynamically adjusts the set opening based on the compressor's rotation speed, ensuring the valve opening is optimized for each operating condition. This prevents both refrigerant shortage at high speeds and liquid back flow at low speeds, resolving the contradiction between maintaining sufficient refrigerant supply and ensuring operational stability.
Solution Approach 2:
The patent implements feedback control where the control unit continuously monitors the compressor's rotation speed and adjusts the set opening of the electronic expansion valve for heating accordingly. This closed-loop feedback mechanism ensures that the valve opening always corresponds to the current operating conditions, preventing liquid back flow while maintaining adequate refrigerant suction across varying compressor speeds.
2Reliability
If the electronic expansion valve for heating is excessively restricted to prevent liquid back flow, then operational stability improves, but the refrigerant suction amount becomes insufficient, especially at high compressor speeds
Solution Approach 1:
The patent resolves this contradiction by dynamically adjusting the set opening of the electronic expansion valve for heating based on compressor rotation speed. At high speeds, the set opening is increased to ensure sufficient refrigerant suction, while at low speeds, it is decreased to prevent liquid back flow. This dynamic adjustment ensures both adequate refrigerant supply and operational stability across all operating conditions.
Solution Approach 2:
The patent applies parameter changes by varying the set opening parameter of the electronic expansion valve for heating according to the compressor's rotation speed parameter. This coordinated parameter adjustment ensures that the valve opening is optimized for each operating condition, simultaneously preventing liquid back flow and maintaining sufficient refrigerant suction without requiring excessive restriction.
3Device complexity
If the set opening of the electronic expansion valve for heating is kept uniform, then the control system is simple, but it cannot adapt to varying compressor speeds, causing liquid back flow or refrigerant shortage
Solution Approach 1:
The patent applies dynamics by transitioning from a static, uniform set opening to a dynamic, variable set opening that adapts to compressor rotation speed. The control unit automatically adjusts the set opening based on real-time speed information, enabling the system to adapt to varying operating conditions without requiring complex manual intervention or multiple fixed valves, thus maintaining reasonable system complexity while significantly improving operational stability.
Solution Approach 2:
The patent implements parameter changes by making the set opening parameter of the electronic expansion valve for heating variable based on compressor rotation speed. This single parameter adjustment enables the system to adapt to different operating conditions, preventing both liquid back flow and refrigerant shortage while maintaining a relatively simple control architecture that leverages existing speed sensing capabilities.
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 improves operational stability and performance by dynamically adjusting the electronic expansion valve openings according to compressor speed, preventing liquid backflow and refrigerant shortages, and maintaining optimal supercooling and superheating degrees.
Implementation Method 1
controls a refrigerant superheating degree of an exit of the heat source side heat exchanger by the electronic expansion valve for heating
Implementation Method 2
controls a refrigerant supercooling degree of an exit of the use side heat exchanger by the electronic expansion valve for cooling
Implementation Method 3
a heat source side heat exchanger
Implementation Method 4
a use side heat exchanger for heating an indoor air with the refrigerant by the use side heat exchanger
Implementation Method 5
a refrigerant compressor
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An air conditioner 1 includes a refrigerant circuit including a refrigerant compressor 11, a heat source side heat exchanger 12, an electronic expansion valve for heating 17, an electronic expansion valve for cooling 16, and a use side heat exchanger 13 and an expansion valve control unit 50 for controlling a refrigerant superheating degree of an exit of the heat source side heat exchanger by the electronic expansion valve for heating and controlling a refrigerant supercooling degree of an exit of the use side heat exchanger by the electronic expansion valve for cooling at the time of a heating cycle for heating the use side with a refrigerant by the use side heat exchanger. The expansion valve control unit 50 includes a target value correction control unit 53 which gradually lowers a target supercooling degree of the electronic expansion valve for cooling when the opening of the electronic expansion valve for heating is equal to or larger than the set opening and a set opening correction control unit 54 which corrects the set opening of the electronic expansion valve for heating in the target value correction control unit according to the rotation speed of the refrigerant compressor.