Power Operated Valve Fail-Safe Mechanism
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Solution Overview
Problem
Power-operated valves can remain in an open position during a power supply failure, leading to uncontrolled fluid flow until the power is restored, which is unsafe and inefficient.
Innovation Solution
A fail-safe mechanism is implemented using a mechanical or magnetic coupling to hold the actuator in a control position with power on and release it to move the valve member to a closed position when power is interrupted, utilizing a spring or magnetic attraction to ensure fluid flow shutdown, and re-setting the actuator upon power restoration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a power operated valve is used to control fluid flow, then the valve can be operated conveniently with power supply, but the valve remains in open position during power failure causing uncontrolled fluid flow
Solution Approach 1:
The valve is designed with a spring biasing mechanism that naturally keeps the valve in the closed position. The actuator must actively overcome this spring force to open the valve. During power failure, when the actuator cannot maintain position, the spring automatically returns the valve to the safe closed position, inverting the conventional approach where power is needed to maintain closure.
Solution Approach 2:
The spring is pre-loaded and positioned to exert closing force on the valve member before any operation is needed. This preliminary action ensures that in the event of power failure, the valve already has the mechanical advantage and stored energy required to automatically return to the closed position without requiring additional power or control systems.
2Reliability
If the actuator is held in control position by mechanical coupling, then the actuator can be reliably held during normal operation, but additional latch unit components increase device complexity
Solution Approach 1:
The latch unit is integrated with the actuator assembly, combining the holding function with the existing actuator structure. The catch element works in conjunction with the actuator's mechanical coupling, merging multiple functions (actuation, holding, and fail-safe positioning) into a unified mechanism rather than adding completely separate systems.
Solution Approach 2:
The latch unit is designed to automatically engage and disengage based on the actuator's position and power availability. During normal operation, the mechanical coupling automatically holds the actuator in the control position. Upon power failure, the spring force automatically causes the actuator to move, which automatically triggers the latch release mechanism, eliminating the need for external control or additional complex actuation systems.
3Reliability
If a spring biasing mechanism is used to hold the actuator, then the actuator can be automatically returned to closed position, but the spring occupies additional space and increases device complexity
Solution Approach 1:
The spring is positioned within the existing actuator housing and valve body structure, utilizing available internal spaces. The spring mechanism is integrated into the actuator assembly, with the spring housed within the actuator's cylindrical body or the valve body cavity, rather than requiring external mounting space.
Solution Approach 2:
The spring mechanism serves multiple functions: it provides the biasing force to keep the valve closed, stores potential energy for the fail-safe return action, and works in conjunction with the latch unit to provide automatic positioning. This multi-functionality reduces the need for separate dedicated components for each function, optimizing space utilization.
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
Ensures immediate shutdown of fluid flow during power failures, preventing waste and ensuring safety, while allowing controlled re-establishment of flow once power is restored, thus addressing the issue of uncontrolled fluid flow in power-operated valves.
Implementation Method 1
The biasing force is stored in the control position of the actuator and is released when the actuator is released
Implementation Method 2
The spring may be in an energised state when the actuator is held in the control position. Energy stored in the spring in the energised state may be employed when the actuator is released
Implementation Method 3
The fail-safe device may include a latch unit configured to create a magnetic attraction force to hold the actuator in the control position. The latch unit may include an electromagnet
Implementation Method 4
The latch unit may include an electromagnet. The actuator may be held in the control position by the electromagnet when the power supply is on
Data Source
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AI summary
A power operated valve 1 for controlling fluid flow is provided with a fail-safe device 3 responsive to failure of the power supply to the valve 1 to shut-off fluid flow. A valve member 13, 15, 13', 15' is coupled to a linear actuator 27, 27' for movement towards and away from a closed position for controlling fluid flow through the valve 1. The linear actuator 27, 27' is held in a control position by the fail-safe device 3 for normal operation of the valve 1 with the power supply "on". The fail-safe device 3 responds to failure of the power supply to release the linear actuator 27, 27'. When the linear actuator 27, 27' is released, energy stored in a spring 57, 57' while the linear actuator 27, 27' was held in the control position is released and biases the linear actuator 27, 27' away from the control position causing the valve member 13, 15, 13', 15' to move to the closed position to shut-off fluid flow.