Control Valve With Dual-Assembly Pressure Balancing for Flow Stability
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Solution Overview
Problem
Conventional electric regulating valves in HVAC systems are unstable due to pressure fluctuations, exhibit poor resistance to interference, and have low precision in heat or cold delivery, while existing Pressure Independent Control Valves (PICVs) face challenges with resistance and require high-power actuators or complex valve stem designs.
Innovation Solution
A control valve design incorporating a mechanical dynamic balancing mechanism that includes a first valve assembly for rotational flow rate presetting and regulation, and a second pressure difference balancing valve assembly to stabilize flow rates independently of system pressure, eliminating the need for a pressure-leading passage in the valve stem.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional electric regulating valve is used, then the structure is simple, but the flow rate is affected by pressure fluctuation resulting in poor stability and low regulation precision
Solution Approach 1:
The valve is divided into two independent assemblies: a first valve assembly for flow rate presetting and regulation, and a second pressure difference balancing valve assembly for stabilizing flow rates. This segmentation allows each assembly to perform its specific function independently, resolving the contradiction between stability and complexity by distributing functions across separate modular components.
Solution Approach 2:
A pressure difference balancing mechanism acts as an intermediary between the inlet and outlet passages, automatically compensating for pressure fluctuations. This intermediary mechanism balances the pressure effects on the valve plug, maintaining stable flow rate characteristics without requiring complex active control systems.
2Power
If existing PICVs with non-balancing design are used, then the structure is simple, but significant resistance occurs during operation requiring high-power actuators
Solution Approach 1:
The pressure difference balancing valve assembly enables the system to self-regulate by automatically balancing pressure effects on the valve plug during operation. This self-service mechanism eliminates the need for high-power actuators to overcome resistance, as the balancing mechanism naturally compensates for pressure fluctuations without requiring additional energy input.
3Manufacturing precision
If valve stem limiting is used for flow rate presetting, then the flow rate can be controlled, but the valve stem has both guiding and limiting actions increasing machining difficulty
Solution Approach 1:
The flow rate presetting function is separated from the valve stem by using a slider component that rotates within the valve seat to adjust the opening size. This segmentation removes the limiting function from the valve stem, allowing the stem to focus solely on guiding the valve plug, thereby simplifying machining requirements while maintaining precise flow rate control through the slider's rotational position.
4Volume of moving object
If the valve stem serves as a pressure-leading passage, then the structure is compact, but the flow-leading gap must be small increasing machining difficulty and reducing stability
Solution Approach 1:
The pressure-leading function is extracted from the valve stem and implemented through dedicated pressure-leading passages in the valve body and valve seat. This extraction allows the valve stem to maintain a larger, more stable diameter focused on guiding, while the pressure-leading passages are separately optimized for their specific function, eliminating the conflict between compactness and machining precision.
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 provides precise flow rate control, reduces system noise and vibration, and enhances the stability and longevity of the valve stem by automatically balancing pressure effects and eliminating the need for complex machining, resulting in improved system performance and reduced maintenance.
Implementation Method 1
a second valve assembly (130), disposed between the inlet passage (111) and the outlet passage (112), and separated in space from the first valve assembly (120), the second valve assembly (130) being a pressure difference balancing valve, capable of regulating a flow rate according to the difference between a first fluid pressure (P1) and a second fluid pressure (P2)
Data Source
AI summary
Various embodiments include a control valve comprising a first valve assembly between an inlet and an outlet. The first valve assembly comprises: a valve seat fixed relative to the valve body with an opening in a sidewall; a slider rotating inside the valve seat to block the opening, but stationary in an axial direction; a regulating valve plug with an opening at one end, surrounding the valve seat and movable in the axial direction to block the opening in the sidewall of the valve seat; and a first valve stem connected to the slider and to the regulating valve plug, the first valve stem having one end extending out of the valve body. A first overlap between the slider and the opening and a second overlap of the plug and the opening are changed by movement of the first valve stem.