Latched Failsafe Valve Module With Isolated Spring Coupling
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Solution Overview
Problem
Existing valve actuation systems face challenges in efficiently and reliably moving valves to a safe position during emergencies, particularly due to stress cycling of springs and the need for oversized actuators and valves to handle spring force, leading to complex and inefficient designs.
Innovation Solution
A failsafe module with a coupling mechanism that includes an intermediate member and an energy storage device, where the energy storage device is isolated from the coupling between the input and output members when the latch mechanism is engaged, allowing the actuator to be rated only for the maximum torque requirement and preventing stress cycling of the energy storage device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring is permanently coupled to both the output of the actuator and the input of the valve, then the valve can be actuated to a safe position on power loss, but the spring puts heavy stress through the actuator and must be stress-cycled with each valve operation
Solution Approach 1:
The coupling mechanism is divided into separate functional components: an intermediate member that receives actuator input, an energy storage device (spring) that provides failsafe force, and a latch mechanism that controls engagement. This segmentation allows the actuator to only drive the intermediate member without directly承受 spring stress, while the spring independently provides the failsafe function.
Solution Approach 2:
The intermediate member acts as a mediator between the actuator and the spring/valve system. It receives rotational input from the actuator and transfers it to the latch mechanism, which then controls the engagement of the spring with the valve. This intermediary prevents direct stress transmission from the spring to the actuator.
2Force
If the spring is sized to provide sufficient force when fully compressed, then the valve can be actuated against maximum spring load, but the actuator and valve components must be oversized to handle the extra load
Solution Approach 1:
The system transitions from a static direct-coupling arrangement to a dynamic staged-engagement system. The latch mechanism allows the spring to engage gradually as the intermediate member rotates, enabling the spring to be fully compressed and provide maximum force without requiring the actuator to continuously withstand that full load throughout the valve operation cycle.
3Reliability
If the energy storage device is directly coupled to the input and output members, then it can provide immediate failsafe action, but it undergoes stress cycling during each valve operation reducing its lifespan
Solution Approach 1:
The spring is pre-compressed and held in an energized state by the latch mechanism during normal valve operations. The latch remains engaged, preventing the spring from stress-cycling. Only in the event of a failsafe condition does the latch release, allowing the pre-stored energy to immediately actuate the valve to its safe position without the spring having undergone operational stress cycles.
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 design enhances the reliability and efficiency of valve actuation by isolating the energy storage device from the coupling, reducing the load on the actuator and valve, and ensuring the valve can move to a safe position during emergencies without overstressing components.
Implementation Method 1
an energy storage device acting between the output member and the intermediate member, such that movement of the intermediate member relative to the output member from the first position to the second position energises the energy storage device, and wherein the energy storage device, the output member, and the intermediate member are engaged such that a release of energy from the energy storage device drives the output member to the predetermined position
Data Source
AI summary
A failsafe module comprising an input member (310), an output member (312), and a coupling mechanism for coupling the input member to the output member. The coupling mechanism comprises an intermediate member (316a) movable relative to the output member to energise an energy storage device and a latch mechanism (318, 320) to hold the energy storage device in an energised state. When the latch mechanism is engaged, the input and output members are coupled together and the energy storage device is held in an energised state and isolated from the coupling between the input and output members. When the latch mechanism is released, the energy storage device can release its energy to drive the output member to a predetermined position.