Electronic Expansion Valve Superheat Control for Vehicle Air-Conditioning
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Solution Overview
Problem
Conventional vehicle air-conditioning systems with thermal expansion valves struggle to rapidly respond to changing conditions, leading to unstable superheat control, inefficiency, and increased costs due to liquid accumulation in non-working sides, especially in new energy vehicles with dual evaporators.
Innovation Solution
Implementing an electronic expansion valve controlled by real-time feedback from actual and preset superheat degrees, as well as feedforward information such as compressor and evaporator fan speed changes, to adjust the opening degree dynamically and smoothly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a thermal expansion valve is used as a throttling element in an electric compressor system, then the system structure is simple, but the valve cannot respond rapidly to rapid changes in compressor or evaporator fan working conditions, resulting in unstable superheat control
Solution Approach 1:
The patent replaces the purely mechanical thermal expansion valve with an electronic expansion valve that incorporates electronic sensors and control systems. The electronic expansion valve uses electronic signals to control the opening degree based on feedback from temperature and pressure sensors, enabling rapid response to changing working conditions while maintaining stable superheat control through electronic regulation rather than mechanical force alone
Solution Approach 2:
The patent implements a feedback control system where temperature sensors and pressure sensors continuously monitor the actual superheat degree and working conditions, and this information is fed back to the electronic expansion valve controller. The controller adjusts the opening degree in real-time based on the feedback signals, ensuring rapid response to changes and stable superheat control through closed-loop regulation
2Adaptability or versatility
If a thermal expansion valve is used in a double-evaporator type air-conditioning system, then the system can cool multiple components, but the valve cannot be fully shut off during operation, causing liquid accumulation in non-working sides and increasing system charge amount
Solution Approach 1:
The patent replaces the mechanical thermal expansion valve with an electronic expansion valve that can be precisely controlled through electronic signals. This enables the valve to be fully shut off or regulated to minimal opening when certain evaporators are not in use, preventing liquid accumulation in non-working sides while maintaining the ability to operate multiple evaporators selectively based on cooling demands
Solution Approach 2:
The patent implements dynamic control of the electronic expansion valve opening degree based on real-time working conditions and evaporator usage patterns. The system can dynamically adjust or completely close the valve for non-working evaporators, optimizing refrigerant distribution and reducing unnecessary liquid accumulation, thereby decreasing the overall system charge amount while maintaining adaptability for multi-evaporator operation
3Speed
If an electronic expansion valve is controlled only by superheat degree using PID control, then the control method is simple, but the response speed is slow and the system is easily overregulated due to rapid changes in vehicle air-conditioner working conditions
Solution Approach 1:
The patent applies feedforward control by detecting anticipated changes in working conditions (such as evaporator fan speed changes or compressor load variations) before they significantly affect the superheat degree. The control system proactively adjusts the electronic expansion valve opening in advance based on these detected trends, enabling faster response without waiting for superheat deviations to occur, thus improving response speed while maintaining controlled complexity
Solution Approach 2:
The patent enhances the basic PID feedback control by incorporating additional sensor feedback signals (such as evaporator fan speed, compressor operating parameters, and temperature trends) into the control algorithm. This multi-parameter feedback approach allows the system to respond more quickly and accurately to changing conditions while preventing overregulation through more informed control decisions, balancing improved response speed with manageable system complexity
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 fast and stable superheat control, improving comfort and efficiency by promptly responding to changing conditions and preventing liquid accumulation, thus reducing system charge and costs.
Implementation Method 1
an opening degree of the electronic expansion valve is controlled through a feed forward information of a compressor and/or an evaporator fan, an actual superheat degree and a preset superheat degree
Implementation Method 2
The liquid refrigerant is throttled and depressurized by the throttling element, and then enters into the evaporator to exchange heat, in the evaporator, with air outside the evaporator
Implementation Method 3
A gaseous refrigerant with high temperature and high pressure discharged from the compressor
Implementation Method 4
A gaseous refrigerant with high temperature and high pressure discharged from the compressor changes into a liquid refrigerant after being condensed by the condenser
Implementation Method 5
The liquid refrigerant is throttled and depressurized by the throttling element
Data Source
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AI summary
Disclosed are a method for controlling a degree of superheat of a vehicle air-conditioning system, and a vehicle air-conditioning system. The method comprises: acquiring an actual degree of superheat in real time, a preset degree of superheat and feed-forward information which influences the variation of the actual degree of superheat; and adjusting a degree of opening of an electronic expansion valve in real time according to the acquired actual degree of superheat, preset degree of superheat and feed-forward information,, so as to control the degree of superheat of the vehicle air-conditioning system.