Valve Fail Safe Mechanism with Cocked Spring Locking
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Solution Overview
Problem
Electrically-actuated valve systems require significant drive power during normal operation due to the need to continuously engage fail safe mechanisms, and existing fail safe systems do not efficiently manage power disruptions to ensure safe valve positioning.
Innovation Solution
A fail safe mechanism comprising a segmented disk, a coupled disk, an energy storage member, and a locking assembly, where the energy storage member stores energy during normal operation and releases it to drive the valve to a fail safe position upon power disruption, allowing the valve to operate with reduced power requirements and ensuring safe positioning without continuous actuator engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fail safe mechanism is continuously engaged during normal operation, then the valve positioning reliability is improved, but the drive power consumption increases significantly
Solution Approach 1:
The energy storage member (spring) is pre-loaded during normal valve operation to store potential energy. This preliminary action allows the fail-safe mechanism to be ready for immediate action without requiring continuous power input, resolving the contradiction between reliability and power consumption.
Solution Approach 2:
The fail-safe mechanism uses the stored energy in the spring to automatically return the valve to its safe position upon power loss, without requiring external power or active control. This self-service capability ensures reliability while eliminating continuous power consumption.
2Reliability
If the energy storage member is engaged during normal operation, then the fail safe positioning capability is improved, but the actuator size and cost increase
Solution Approach 1:
The spring is pre-compressed or pre-loaded during normal operation to the extent needed for fail-safe positioning. This preliminary action ensures that the stored energy is sufficient to return the valve to its safe position without requiring an oversized actuator or complex energy storage system.
Solution Approach 2:
The mechanism changes the state of the spring between engaged (energy stored) and disengaged (energy released) configurations. By controlling when the spring is engaged versus when it operates independently, the system achieves fail-safe capability without requiring the actuator to continuously overcome spring forces, thus reducing actuator size and cost.
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 solution reduces drive power requirements during normal operation and ensures efficient and safe valve positioning by using stored energy to drive the valve to a fail safe position upon power disruption, enabling the use of smaller, less costly actuators and minimizing power consumption.
Implementation Method 1
The energy storage member is operably coupled to the segmented disk and the mounting plate. The energy storage member stores energy when the segmented disk is rotatably driven by the coupled disk toward a cocked position.
Data Source
AI summary
A fail safe mechanism having a return member, valve stem extension, energy storage member, and locking assembly. The valve stem extension is driven by an electrical actuator and configured to drive the return member in a first direction and to be driven by the return member in a second direction. The energy storage member is configured to store energy when the electrical actuator causes the valve stem extension to drive the return member in the first direction and to release the energy stored therein when a disruption of power causes the return member to drive the valve stem extension in the second direction. The locking assembly is configured to hold the return member in a cocked position such that the valve stem extension rotates with the valve independently of the return member and free of influence from the energy storage member while the power is applied to the electrical actuator.