Control method for air-conditioning system having electronic expansion valve
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Solution Overview
Problem
Air-conditioning systems using carbon dioxide as refrigerant face challenges in rapidly and effectively adjusting refrigerating pressure, especially during vehicle acceleration, leading to frequent activation of high pressure protection and physical pressure relief functions, which can degrade system performance and shorten compressor life.
Innovation Solution
A control method for air-conditioning systems that employs different depressurization measures based on pressure ranges, using PID adjustments and quick adjustments to manage refrigerant pressure, reducing the need for high pressure protection and physical pressure relief functions, and optimizing the operation of the electronic expansion valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PID adjustment is used to control refrigerating pressure, then pressure control precision is improved, but response speed is too slow to prevent frequent high pressure protection activation
Solution Approach 1:
The patent implements dynamic adjustment of the electronic expansion valve opening based on real-time pressure feedback. The system transitions from static PID parameters to dynamic control where the valve opening is continuously adjusted according to the current pressure state, enabling both precise control and rapid response to pressure changes during vehicle acceleration.
Solution Approach 2:
The patent employs a feedback mechanism where the actual refrigerating pressure is continuously monitored and compared with the target pressure. The difference (error signal) is fed back to the controller which adjusts the electronic expansion valve opening accordingly, creating a closed-loop control system that achieves both precision and speed in pressure regulation.
2Reliability
If high pressure protection function is frequently activated to prevent system damage, then system safety is improved, but compressor service life is reduced due to frequent start-stop cycles
Solution Approach 1:
The patent applies preliminary action by proactively adjusting the electronic expansion valve opening before the refrigerating pressure reaches the high pressure protection threshold. The controller predicts pressure trends and pre-adjusts the valve to prevent pressure spikes, thereby avoiding frequent activation of the high pressure protection function and reducing compressor start-stop cycles.
Solution Approach 2:
The patent implements beforehand cushioning by creating a buffer zone in pressure control. Instead of allowing pressure to reach the critical protection threshold, the system maintains pressure within a safer operating range through continuous valve adjustment, cushioning against the harmful effects of frequent protection activation and extending compressor life.
3Speed
If electronic expansion valve opening is increased to reduce refrigerating pressure, then pressure reduction speed is improved, but system stability deteriorates due to excessive pressure fluctuations
Solution Approach 1:
The patent applies partial action by adjusting the electronic expansion valve opening to an optimal degree rather than maximum opening. The controller calculates the precise valve opening needed to achieve pressure reduction without causing excessive fluctuations, using just the right amount of valve adjustment to balance speed and stability.
Solution Approach 2:
The patent utilizes parameter changes by dynamically modifying the electronic expansion valve opening parameter based on real-time pressure conditions. The controller adjusts the valve opening parameter continuously, changing it from a fixed value to a dynamic parameter that adapts to system conditions, enabling both rapid pressure reduction and stability maintenance.
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 method allows for secure, effective, and rapid adjustment of refrigerating pressure, minimizing the activation of high pressure protection and physical pressure relief functions, thus maintaining system performance and extending the service life of the compressor.
Implementation Method 1
The electronic expansion valve can adjust a flow rate of the refrigerant by adjusting an opening thereof, to further control the refrigerating pressure within an appropriate range
Implementation Method 2
a compressor, an air-cooled condenser, a water-cooled condenser, an electronic expansion valve, and an evaporator are connected and through which a refrigerant is circulated to operate a refrigeration cycle
Implementation Method 3
an air-cooled condenser for supplying air to the air-cooled condenser
Implementation Method 4
an air-cooled condenser, a water-cooled condenser, an electronic expansion valve, and an evaporator are connected and through which a refrigerant is circulated to operate a refrigeration cycle
Implementation Method 5
an evaporator are connected and through which a refrigerant is circulated to operate a refrigeration cycle
Data Source
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AI summary
A control method for an air-conditioning system is provided according to the present application, through which different pressure lowering measures can be respectively taken to lower a pressure timely when the pressure of the electronic expansion valve is within different ranges, to decrease a number of times of the air-conditioning system being forced to activate a high pressure protection function and even a physical pressure relief function, thereby facilitating maintaining working performances of the air-conditioning system, and prolonging a service life thereof.