Fail-Safe Piston Assembly for Fluid Valves
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Solution Overview
Problem
Existing fluid valves, particularly those using electric actuators, face challenges in achieving precise control and fail-safe mechanisms without increasing complexity, cost, and space requirements, as they often rely on secondary valves upstream to prevent fluid flow during power failures.
Innovation Solution
The integration of a fail-safe apparatus within the valve apparatus using a piston assembly with a control fluid system that selectively couples and decouples the electric actuator and flow control member, allowing the fail-safe mechanism to operate independently during power failures, eliminating the need for a secondary valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fail-safe system with a secondary valve upstream is used to prevent fluid flow during power failures, then safety during fail conditions is improved, but device complexity increases
Solution Approach 1:
The patent combines the fail-safe mechanism directly into the valve body by integrating a piston assembly with a control fluid chamber. The piston assembly includes a valve plug that can be moved between open and closed positions by control fluid pressure, eliminating the need for a separate secondary upstream valve. This merging of functions achieves fail-safe operation while reducing overall system complexity.
Solution Approach 2:
The valve apparatus performs multiple functions within a single integrated structure: it provides normal fluid flow control through the valve plug and simultaneously provides fail-safe operation through the same piston assembly. The control fluid system serves both to actuate the valve during normal operation and to provide automatic fail-safe closing when control fluid pressure is lost, making the system multi-functional without requiring additional components.
2Reliability
If a fail-safe system with a secondary valve upstream is used to prevent fluid flow during power failures, then safety during fail conditions is improved, but costs increase
Solution Approach 1:
The patent combines the fail-safe mechanism directly into the valve body by integrating a piston assembly with a control fluid chamber. The piston assembly includes a valve plug that can be moved between open and closed positions by control fluid pressure, eliminating the need for a separate secondary upstream valve. This merging of functions achieves fail-safe operation while reducing overall system complexity.
3Reliability
If a fail-safe system with a secondary valve upstream is used to prevent fluid flow during power failures, then safety during fail conditions is improved, but space requirements increase
Solution Approach 1:
The patent combines the fail-safe mechanism directly into the valve body by integrating a piston assembly with a control fluid chamber. The piston assembly includes a valve plug that can be moved between open and closed positions by control fluid pressure, eliminating the need for a separate secondary upstream valve. This merging of functions achieves fail-safe operation while reducing overall system complexity.
4Measurement precision
If an electric controller is used to precisely control fluid flow through the valve, then flow control precision is improved, but complexity during fail conditions increases
Solution Approach 1:
The patent introduces control fluid as an intermediary between the electric controller and the valve plug. The electric controller precisely controls valve flow by modulating control fluid pressure, which then actuates the piston assembly. This intermediary approach allows precise electric control while maintaining mechanical fail-safe operation, as the control fluid system provides both precise actuation and automatic fail-safe closing when pressure is lost.
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 precise control and a fail-safe mechanism without the need for additional upstream valves, reducing complexity and cost while ensuring safe operation during power failures by using a control fluid to manage the piston assembly and flow control member.
Implementation Method 1
When the chamber is pressurized with the control fluid, the control fluid imparts a force to the first and second portions to frictionally couple the first and second portions
Implementation Method 2
when at least some of the control fluid is vented or removed (e.g., during a fail condition), the first portion of the piston is operatively decoupled from the second portion of the piston
Data Source
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AI summary
Fail-safe apparatus for use with fluid valves are disclosed herein. An example fail-safe apparatus includes a first piston (342), a second piston (344) movably coupled relative to the first piston, and a fluid chamber (346) between the first and second pistons to receive a con¬ trol fluid. The control fluid is to operatively couple the first and second pistons when the control fluid is provided in the fluid chamber. The first piston is operatively decoupled from the second piston when at least some of the control fluid is removed from the fluid chamber.