Failsafe Valve Actuator Clutch for Low-Power Position Holding
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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 force both to move and hold the valve against the bias, especially in applications requiring fast shutdown to a safe condition.
Innovation Solution
A failsafe valve actuator with a clutch mechanism that includes an externally threaded drive shaft and a concentrically arranged clutch with internally threaded shells, allowing for rotational movement to be converted into axial movement to hold the valve in position using less power, and automatically returning to a failsafe position when de-energized, reducing the need for continuous motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a biasing mechanism is used to automatically return the valve to failsafe position, then the valve can automatically return to failsafe position when power is removed, but the power source has to provide excessive force to both move and hold the valve against the bias, leading to excessive energy consumption and increased risk of motor burnout
Solution Approach 1:
The system is divided into two independent functional components: a biasing mechanism for automatic failsafe return and a clutch mechanism for power-efficient position holding. The clutch disengages during failsafe operation, segmenting the load requirements so the motor only provides force during positioning, not during holding or failsafe operations.
Solution Approach 2:
The clutch acts as an intermediary mechanism between the motor and the valve. It selectively engages to transmit motor force during positioning operations and disengages during failsafe operations, mediating the force transmission to eliminate the need for continuous motor power and excessive force provision.
2Stability of the object's composition
If the power source continuously provides force to hold the valve against the biasing mechanism, then the valve position is maintained, but this increases energy consumption and the risk of motor burnout due to continuous current draw
Solution Approach 1:
The clutch mechanism dynamically engages and disengages based on operational requirements. During normal operation, it engages to maintain valve position without continuous motor power. During failsafe conditions or power loss, it automatically disengages, allowing dynamic adaptation that reduces energy loss while maintaining position stability when needed.
Solution Approach 2:
The biasing mechanism serves itself by automatically returning the valve to failsafe position without requiring continuous motor intervention. The clutch mechanism self-regulates engagement based on load conditions, allowing the system to maintain stability through the biasing mechanism's inherent capability rather than continuous external power input.
3Ease of operation
If the shaft needs to be driven in the reverse direction to close the valve, then the valve can be controlled bidirectionally, but this is not failsafe and may not be suitable for applications requiring fast shutdown to safe condition
Solution Approach 1:
Instead of using bidirectional motor control to achieve failsafe operation, the system inverts the approach by using a unidirectional biasing mechanism that automatically returns the valve to failsafe position. The clutch mechanism is designed to disengage in one direction (failsafe direction), allowing the biasing mechanism to dominate and provide rapid failsafe operation without requiring reverse motor operation.
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 significantly reduces power consumption, enabling efficient and rapid valve actuation while ensuring a reliable failsafe mechanism, minimizing energy usage and preventing motor burnout, thus enhancing operational safety and efficiency.
Implementation Method 1
a drive shaft bias member arranged to axially bias the drive shaft into a failsafe position
Implementation Method 2
a clutch actuator coupled to the clutch and arranged to move the clutch between an engaged position and a disengaged position
Implementation Method 3
the drive shaft comprising an externally threaded portion extending along at least a portion of the length of the drive shaft
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
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.