Failsafe Valve Actuator Clutch for Low-Power Return
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Solution Overview
Problem
Existing valve actuators with biasing mechanisms require excessive energy to maintain the valve position, leading to inefficiency and increased risk of motor burnout, as they need to provide the force to move and hold the valve against the biasing mechanism until power is turned off.
Innovation Solution
A failsafe valve actuator design featuring a drive shaft with an externally threaded portion, a clutch with a partial internal thread, and a clutch actuator that engages and disengages to transfer rotational movement into axial movement, allowing the drive shaft to automatically return to a failsafe position when power is lost, reducing the need for continuous energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a biasing mechanism is used to automatically return the valve to a failsafe position, then the valve can automatically return to a safe position when power is lost, but the power source has to provide excessive force to move and hold the valve against the biasing mechanism
Solution Approach 1:
A clutch mechanism acts as an intermediary between the drive shaft and the biasing mechanism. When engaged, the clutch allows the drive shaft to be held in position without requiring continuous power. When disengaged, the biasing mechanism can freely move the drive shaft to the failsafe position. This mediator eliminates the need for continuous power application while maintaining positioning capability.
Solution Approach 2:
The system dynamically switches between two states: engaged (where the clutch connects the drive shaft to the biasing mechanism for positioning) and disengaged (where the biasing mechanism freely returns the shaft to failsafe). This dynamic operation allows the system to achieve both precise positioning and automatic failsafe recovery without continuous power consumption.
2Stability of the object's composition
If continuous power is applied to hold the valve position against the biasing mechanism, then the valve position is maintained, but the risk of motor burnout increases due to excessive current draw
Solution Approach 1:
The clutch serves as a mechanical intermediary that decouples the motor from the biasing mechanism when engagement is not required. This allows the motor to remain stationary and avoid continuous current draw, while the clutch mechanically maintains the drive shaft position through the biasing mechanism without requiring motor power.
Solution Approach 2:
The biasing mechanism serves itself by automatically returning the drive shaft to the failsafe position when the clutch is disengaged, without requiring motor intervention. The motor only provides power during transient positioning operations, not during continuous holding, thereby eliminating the risk of burnout from continuous operation.
3Ease of operation
If the drive shaft is driven in reverse direction to close the valve, then the valve can be controlled bidirectionally, but the mechanism is not failsafe and cannot provide fast shutdown
Solution Approach 1:
Instead of using bidirectional motor control to open and close the valve, the system inverts the approach: the motor only drives the valve in one direction (opening), while closing is achieved passively through the biasing mechanism when the clutch disengages. This inversion enables fast, automatic shutdown without requiring reverse motor operation.
Solution Approach 2:
The reverse driving function is extracted from the motor and transferred to the biasing mechanism. The motor retains only the opening function, while the biasing mechanism handles the closing function, enabling fast automatic shutdown when power is removed or the clutch is disengaged.
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 reduces power consumption and enhances efficiency by allowing the valve to quickly return to a failsafe position without requiring energy to drive it back, thus minimizing the risk of motor burnout and improving system safety during emergency shutdowns.
Implementation Method 1
a drive shaft bias member arranged to axially bias the drive shaft into a failsafe position
Implementation Method 2
threaded engagement between the thread of the drive shaft and clutch transfers rotational movement of the drive shaft by the drive mechanism into axial movement of the drive shaft
Data Source
AI summary
The present invention relates to a failsafe valve actuator (10) comprising a drive mechanism (12), a drive shaft (42) having a clutch (50) arranged adjacent to a threaded portion (44) of the drive shaft (42), and a clutch actuator (52) coupled to the clutch (50) and arranged to move the clutch (50) between an engaged position in which the clutch (50) engages with the threaded portion (44) of the drive shaft (42) and a disengaged position in which the clutch (50) is disengaged from the drive shaft (42). In response to energisation of the clutch actuator (52) the clutch (50) is moved to the engaged position such that threaded engagement between the drive shaft (42) and clutch (50) transfers rotational movement of the drive shaft (42) by the drive mechanism (12) into axial movement of the drive shaft (42) and holds the drive shaft (42) against a drive shaft bias member when the drive mechanism is inactive. Movement of the clutch (50) to the disengaged position, causes the drive (12) shaft bias member to automatically return the drive shaft (42) to the failsafe position.