Rotary Valve Stem Canal for Low-Hysteresis Flow Control
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Solution Overview
Problem
Conventional fluid flow control valves are complex with many moving parts, leading to wear and increased hysteresis, which results in inaccurate and unreliable control of fluid flow over time and multiple cycles.
Innovation Solution
A simplified valve stem design for a fluid flow control valve, featuring a valve stem head with a continuous peripheral wall, a canal formed by opposing walls that extend circumferentially, and a second fluid inlet and outlet, allowing for precise modulation of fluid flow through variable restriction based on rotational position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional valve designs with multiple moving parts are used, then the valve can achieve fluid flow control, but the valve experiences increased wear and hysteresis over time leading to drift from desired position
Solution Approach 1:
The patent removes the traditional valve seat and disc assembly from conventional valve designs. Instead, it uses a valve stem with a canal that rotates within the valve body to directly control fluid flow. This extraction of unnecessary components reduces the number of moving parts and eliminates wear between the valve seat and disc, thereby improving reliability and reducing hysteresis.
Solution Approach 2:
The valve stem is segmented into distinct functional zones: an elongate arm for actuation, a head with a canal for flow control, and outer surface portions that provide variable restriction. This segmentation allows each part to perform its specific function efficiently, reducing overall complexity while maintaining control capability.
2Measurement precision
If conventional valve designs are used, then fluid flow control is achieved, but hysteresis increases over time resulting in wide range of possible actual flow rates at a given set point
Solution Approach 1:
The patent replaces the traditional mechanical valve seat and disc system with a rotational canal system. The canal in the valve stem head rotates to align with or away from the fluid passage, controlling flow without mechanical contact between sealing surfaces. This substitution eliminates the hysteresis and wear associated with conventional mechanical valve operations, maintaining precision over extended operational lifespans.
3Reliability
If simplified valve stem design is used, then wear and hysteresis are reduced, but fluid flow modulation capability must be maintained
Solution Approach 1:
The valve stem head features a canal with specific local geometric properties that enable precise flow modulation. The canal's shape, position, and orientation are optimized to provide variable restriction as it rotates. This local quality enhancement ensures that despite the simplified overall design, the valve maintains excellent fluid flow modulation capability while improving durability.
Data Source
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AI summary
A valve stem for use in a fluid flow control valve having a valve body configured to receive a portion of the valve stem and to enable the valve stem to selectively rotate within the valve body between a fully-open position, where fluid is permitted to flow through the fluid flow control valve, and a fully-closed position, where fluid is prevented from flowing through the fluid flow control valve. The valve stem includes an elongate valve stem arm having a first end and a second end and a valve stem head integrally formed with and fixedly attached to the second end of the valve stem arm. The valve stem head includes a fluid inlet formed in the valve stem head, and a fluid outlet formed in the valve stem head, and a fluid passage that directs fluid from the fluid inlet, through the valve stem, and out of the fluid outlet.