Rolling Diaphragm Flow Valve for Stable HVAC Pressure Drop
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Solution Overview
Problem
Current pressure independent control valves in HVAC systems face challenges in maintaining consistent pressure and temperature differentials across piping systems due to fluctuations in fluid supply pressure, which affects the efficiency and stability of fluid flow control.
Innovation Solution
A control valve design incorporating a bulbous closing element secured to a valve stem, an everting sleeve or diaphragm, and a pilot valve controlled by a computer system to manage pressure or temperature differentials, allowing the valve to throttle flow effectively by porting high-pressure fluid and utilizing a spring for eversion and reversion of the diaphragm to control the bulbous closing element's position against the valve seat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a flat diaphragm directly attached to the closing element is used, then the valve structure is simple, but the control precision and stability are insufficient
Solution Approach 1:
The valve is divided into a main valve and a pilot valve, with the pilot valve controlling the main valve through fluid pressure. This segmentation allows the pilot valve to provide precise control signals while the main valve handles the primary flow control, improving overall control precision without requiring the entire valve structure to be overly complex.
Solution Approach 2:
The pilot valve is integrated within the main valve body, with the pilot valve's closing element positioned inside the main valve's flow path. This nested configuration allows the smaller pilot valve to control the larger main valve in a compact arrangement, achieving precise control without proportionally increasing external dimensions.
2Reliability
If typical valve discs and valve seats are used, then the valve design is conventional and easy to manufacture, but the valve cannot effectively maintain constant pressure differential across fluctuating supply pressures
Solution Approach 1:
The pilot valve senses the downstream pressure and uses this feedback to adjust the main valve opening. When downstream pressure changes, the pilot valve responds by adjusting the fluid pressure acting on the main valve's closing element, thereby maintaining a constant pressure differential across the main valve despite fluctuations in supply pressure.
Solution Approach 2:
Fluid pressure acts as an intermediary between the pilot valve and the main valve closing element. The pilot valve controls the pressure of fluid that then acts on the main valve's diaphragm and closing element, translating small pilot valve movements into appropriate main valve positioning to maintain stable pressure differential.
3Volume of moving object
If the valve uses a compact disc-shaped design with integrated components, then the valve occupies less space, but the complexity of integrating all components increases
Solution Approach 1:
The pilot valve and main valve are merged into a single integrated valve body, with shared components such as the valve seat and sealing surfaces. The pilot valve's closing element and the main valve's closing element are integrated in the same flow path, reducing the number of separate components and simplifying assembly while maintaining compact dimensions.
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
The solution ensures precise control of fluid flow by maintaining constant pressure or temperature differentials across the valve and associated piping systems, enhancing the stability and efficiency of HVAC system operations.
Implementation Method 1
a spring configured to force the everting sleeve or rolling diaphragm to evert
Implementation Method 2
pressure is applied to the rolling diaphragm, on the side of the diaphragm opposite the bulbous closing element and the seat
Data Source
AI summary
A flow control valve including a main valve and a pilot valve for controlling a piston of the main valve. The valve maybe controlled through a control system based upon measured pressures or temperatures in a system supplied or controlled by the valve. The valve may be operated as a pressure independent control valve, using pressure measurement from a supply line and exit line or return line of a hydronic HVAC system as inputs to the control system, which is operable to maintain a constant pressure drop across the system, or the valve may be operated as a temperature independent control valve, using temperature measurements from a supply line and exit line or return line of a hydronic HVAC system as inputs to the control system which is operable to maintain a constant temperature drop across the system.