Fluid-Actuated Diaphragm Flow Control Valve
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Solution Overview
Problem
Conventional flow control valves face challenges in maintaining stable and repeatable flow rates due to temperature and pressure instabilities, mechanical precision limitations, and nonlinearity, leading to issues with particle generation, corrosion, and inadequate control over wide ranges of flow rates and pressures, particularly in applications requiring precise control and high accuracy.
Innovation Solution
The design employs a diaphragm control system where the pressure of a control fluid modulates the deflection of a metallic diaphragm relative to a valve seat, allowing for independent control of fluid flow resistance, enabling both manual and automated flow and pressure control, and utilizing a proportional-derivative control algorithm for precise adjustments, which avoids the need for permanent flow restrictors and minimizes particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a needle valve design is used to control small gaps for low flow rates, then flow control precision is improved, but needle wear and particle generation increase significantly
Solution Approach 1:
The patent replaces the mechanical needle-valve system with a fluid-actuated diaphragm system. Instead of using a mechanical needle to control the gap, a control fluid pressure acts on a diaphragm to deflect it and control the orifice gap. This substitution eliminates the mechanical contact and wear between moving parts, thereby preventing particle generation while maintaining precise flow control capability
Solution Approach 2:
The patent employs a control fluid (pneumatic or hydraulic system) to actuate the diaphragm and control the orifice gap. The control fluid pressure varies the diaphragm deflection, which in turn adjusts the gap between the diaphragm and valve seat. This fluid-based actuation mechanism provides precise control without mechanical wear, resolving the contradiction between precision and particle generation
2Ease of operation
If manual precision screw-based valves are used, then ease of operation is improved, but mechanical precision limitations and screw backlash reduce flow control accuracy
Solution Approach 1:
The patent replaces the manual precision screw mechanism with a fluid-actuated diaphragm system controlled by control fluid pressure. This eliminates screw backlash and mechanical precision limitations, as the diaphragm responds directly to pressure changes without mechanical play or wear, thereby improving flow control accuracy while maintaining operational simplicity through external control fluid supply
3Measurement precision
If the orifice gap is reduced to control low flow rates, then flow rate precision is improved, but nonlinearity and sensitivity to mechanical imperfections increase
Solution Approach 1:
The patent uses control fluid pressure acting on the diaphragm to control the orifice gap size. By varying the control fluid pressure, the system can precisely control the gap and thus the flow rate. The fluid pressure control provides a linear and predictable relationship between control input and flow output, reducing nonlinearity and sensitivity to mechanical imperfections compared to direct mechanical adjustment
4Speed
If actuator is immersed in fluid for direct control, then response speed is improved, but actuator corrosion and particle generation increase
Solution Approach 1:
The patent introduces a control fluid as an intermediary between the control system and the process fluid. The control fluid acts on the diaphragm to control the orifice gap without the actuator being directly exposed to the process fluid. This intermediary arrangement prevents corrosion and particle generation while maintaining fast response through direct fluid pressure control
Solution Approach 2:
The patent replaces direct mechanical actuation in the process fluid with fluid-actuated diaphragm control. The control mechanism is separated from the process fluid by the diaphragm, eliminating direct contact between the actuator and corrosive or particle-generating process conditions, thereby preventing corrosion and particle generation while maintaining responsive control
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 solution provides reliable, fast, and accurate control over a wide range of flow and pressure conditions, prevents particle generation, and ensures operation with corrosive and reactive fluids, while maintaining precision and stability across the entire flow and pressure range, including low and zero flow rates, and supports fail-safe operations.
Implementation Method 1
A deflection of the diaphragm in relation to the valve seat is responsive to a pressure of a control fluid in the diaphragm control space
Implementation Method 2
a metallic diaphragm disposed between a flow input and a flow output... A deflection of the diaphragm in relation to the valve seat
Data Source
AI summary
An apparatus is described for controlling a flow of a fluid therethrough while the apparatus is connected to a source of control fluid. The apparatus includes an input, a valve seat, a diaphragm, an output, and a diaphragm control space. The diaphragm control space is partially defined by the diaphragm, and includes a control fluid inlet and a control fluid outlet. The apparatus is operative to independently control a flow of control fluid into the diaphragm control space through the control fluid inlet and a flow of control fluid out of the diaphragm control space through the control fluid outlet. A deflection of the diaphragm in relation to the valve seat is responsive to a pressure of the control fluid in the diaphragm control space. The deflection of the diaphragm in relation to the valve seat is operative to control a fluidic flow resistance between the input and the output.