Actuated Valve Assembly With Fixed Orifice for Stable Flow Rate
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Solution Overview
Problem
Conventional actuated valves experience flow rate variations due to changes in fluid pressure, temperature, and mechanical deformations, leading to inconsistent output and system downtime, particularly in applications requiring precise and consistent flow rates, such as semiconductor wafer processing.
Innovation Solution
The implementation of an actuated valve assembly with a fixed orifice restriction and a stroke adjustment mechanism, which limits the valve element's movement to adjust the seat annulus flow coefficient or area, maintaining a specific ratio with the orifice flow coefficient or area, thereby minimizing flow deviations and ensuring consistent flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional actuated valve is used to control fluid flow, then the valve can be actuated to a desired flow setting, but the flow rate is subject to variations due to pressure changes, temperature changes, deformation of valve components, and resistance to actuation
Solution Approach 1:
The valve flow path is segmented into two distinct flow restrictions: a fixed orifice restriction and a variable seat annulus flow area. This segmentation allows the fixed orifice to provide a stable reference flow path while the variable seat annulus provides flow control capability, thereby reducing overall flow rate variations
Solution Approach 2:
The invention changes the parameter of flow restriction from a single variable component to a combination of a fixed orifice and a variable seat annulus. By maintaining a specific ratio between the fixed orifice flow coefficient and the maximum seat annulus flow coefficient (between 0.2:1 and 0.5:1), the system achieves more stable flow characteristics while retaining actuation capability
2Quantity of substance
If the valve element is allowed to move freely between closed and open positions, then the valve can provide maximum flow capacity, but flow deviations occur due to valve drift and shift
Solution Approach 1:
The fixed orifice restriction acts as an intermediary element that mediates between the variable seat annulus flow area and the outlet. This intermediary provides a stable flow reference that compensates for variations in the seat annulus flow area caused by valve drift and shift, thereby improving flow rate precision while maintaining adequate flow capacity
Solution Approach 2:
The invention introduces a fixed orifice with a specific flow coefficient ratio (0.2:1 to 0.5:1 relative to maximum seat annulus flow coefficient) to change the overall flow characteristics. This parameter change ensures that the fixed orifice provides sufficient flow capacity while its fixed nature eliminates drift and shift issues
3Productivity
If multiple systems operating in parallel use identical valves, then system consistency is expected, but flow output variations cause systems to not meet required specifications
Solution Approach 1:
By segmenting the flow control into a fixed orifice component and a variable seat annulus component, the invention ensures that the fixed orifice provides a consistent reference flow path across multiple valves. This segmentation reduces unit-to-unit variations in flow output, improving system output consistency and specification compliance
Data Source
AI summary
An actuated valve assembly includes a valve body (110) having a valve seat (112) disposed between inlet (111) and outlet (113) passages, and a fixed orifice (115) restriction provided in at least one of the inlet and outlet passages, a valve element (120) assembled with the valve body and axially movable between a closed position and an open position, and an actuator (130) assembled with the valve body and connected with the valve element for axial movement of the valve element between the closed and open positions. A ratio of the maximum seat annulus flow coefficient associated with the valve seat and valve element to an orifice flow coefficient associated with the fixed orifice restriction is between about 2:1 and about 8:1.