Valve Plunger Shielding for Stable Low-Force Flow Control
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Solution Overview
Problem
Mass Flow Controllers (MFCs) face challenges in maintaining a consistent fluid flow rate due to flow-induced forces that cause oscillatory behavior, particularly when using low-force valves, as these forces can dominate the force balance and lead to instability in valve operation.
Innovation Solution
A valve assembly design that incorporates shields within the tubing channel to maintain consistent fluid streamlines beneath the plunger, thereby minimizing or eliminating flow-induced forces, which are achieved by using a shield that can be coupled or suspended beneath the plunger and extends into the tubing channel, guiding fluid flow and preventing stagnation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low-force valves are used to minimize power consumption, then power consumption is reduced, but flow-induced forces cause oscillatory behavior and control instability
Solution Approach 1:
A streamlined element (intermediary component) is introduced between the fluid flow and the valve plunger. This element modifies the flow pattern to eliminate oscillatory forces while allowing the low-force valve to maintain stable control. The streamlined element acts as a mediator that transforms the harmful oscillating flow into a stable flow pattern.
Solution Approach 2:
The harmful oscillatory flow-induced forces are extracted or removed from the system by introducing the streamlined element. This element effectively takes out the destabilizing forces from the force balance equation, leaving only the controllable actuator forces and stable fluid forces.
2Device complexity
If simplified control systems are used with low-force valves, then device complexity is reduced, but maintaining acceptable operational standards becomes challenging
Solution Approach 1:
The streamlined element enables the valve system to self-regulate by passively modifying the flow pattern. The streamlined shape automatically stabilizes the flow without requiring active control intervention, allowing the simplified control system to maintain acceptable operational standards through the passive hydrodynamic stabilization provided by the streamlined element.
3Productivity
If fluid flow rate is increased to improve productivity, then output increases, but flow-induced forces become more significant and worsen oscillatory behavior
Solution Approach 1:
The streamlined element changes the flow parameters (velocity distribution, pressure distribution) in the region around the valve plunger. By modifying these flow parameters through its streamlined geometry, the element ensures that even at increased flow rates, the flow-induced forces remain stable and do not generate oscillations.
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 introduction of shields stabilizes the fluid flow rate by reducing oscillations and maintaining a consistent force balance, ensuring reliable operation of MFCs even with limited actuator force, thereby enhancing the precision and reliability of fluid flow control.
Implementation Method 1
maintain consistent fluid streamlines beneath the plunger, thereby minimizing or eliminating flow-induced forces
Data Source
AI summary
A valve assembly used to control fluid flow rate. The valve assembly comprises a valve plunger and a shield. The valve plunger forces fluid having a flow rate to flow between an inlet and an outlet in response to an applied actuator force. The actuator force is applied to a first side and the fluid is applied to a second side of the valve plunger. The shield minimizes or eliminates a destabilizing force caused by static pressure, created by fluid interaction on the second side. The shield is either coupled to, formed in, or suspended from underneath the valve plunger and extends a length into the outlet. The valve assembly further comprises an orifice between the inlet and the outlet wherein the orifice comprises at least one planar surface and at least one non-planar surface. The shield shields a section of the second side from the fluid.