System for selectively controlling a flow of fluid and associated control method
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Solution Overview
Problem
Existing HVAC systems face challenges in achieving precise and flexible flow control between fluid circuits, often resulting in less precise control due to the limited angular displacement of 3-way or 6-way valves, which affects the differential pressure and installation flexibility.
Innovation Solution
A flow control system comprising a 3-way changeover valve, a control valve, and a flow sensor, with a controller that communicates with both to selectively direct fluid flow between circuits, allowing for more precise control by separating the functions of switching and flow regulation, and enabling higher differential pressure and installation flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a 3-way valve is used both for directing flow and controlling flow amount, then the device complexity is reduced, but the manufacturing precision and control precision deteriorate due to limited angular displacement
Solution Approach 1:
The patent divides the valve system into two separate functional components: a 3-way changeover valve for flow direction switching and a control valve for precise flow amount regulation. This segmentation allows each valve to be optimized for its specific function, with the control valve providing precise angular displacement control independent of the changeover valve's switching mechanism.
Solution Approach 2:
The 3-way changeover valve is designed to perform both flow direction switching and flow amount control through its shaft rotation mechanism. By making the changeover valve multi-functional, the system reduces the total number of components while maintaining control capability, though this compromises the precision compared to dedicated control valves.
2Device complexity
If a 3-way valve is used for both switching and flow regulation, then the device complexity is reduced, but the differential pressure capability deteriorates
Solution Approach 1:
The patent separates the high-pressure switching function (3-way changeover valve) from the flow regulation function (control valve). The changeover valve is designed to handle high differential pressures during switching, while the control valve operates under more stable pressure conditions for precise flow modulation.
Solution Approach 2:
The system dynamically manages pressure distribution by using the changeover valve's robust mechanical design to withstand high differential pressures during switching operations, while the control valve provides gradual pressure modulation for flow regulation, optimizing the overall pressure handling capability.
3Ease of manufacture
If the flow sensor is arranged downstream from the control valve, then the installation is simpler, but the measurement precision deteriorates due to flow disturbances
Solution Approach 1:
The flow sensor is positioned upstream from the control valve to measure the flow before it enters the valve. This preliminary measurement captures the undisturbed flow characteristics, allowing the control system to adjust the valve position based on accurate baseline flow data without being affected by downstream turbulence.
Solution Approach 2:
The patent introduces a straightening section or flow conditioner between the flow sensor and control valve to eliminate flow disturbances. This intermediary component ensures that the sensor measures representative flow conditions while still allowing practical installation downstream, bridging the gap between measurement accuracy and installation simplicity.
Data Source
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AI summary
Flow control system and method for selectively controlling and selectively limiting a flow of fluid in a circuit of a Heating, Ventilating and Air Conditioning HVAC system.