Valve Actuator Anti-Back Drive Assembly for Handwheel Lockout
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Solution Overview
Problem
Conventional electric valve actuators face inefficiencies and safety issues due to the interdependence of the drive device and hand wheel assembly, leading to operational hazards and reduced performance, as they can drive each other, causing uncontrollable spinning and safety risks during power failures or malfunctions.
Innovation Solution
Incorporating anti-back drive components that selectively prevent rotation of the hand wheel assembly and drive device, using a mechanism with rollers and springs arranged in channels to allow unidirectional rotation, ensuring the drive device does not turn the hand wheel and vice versa, thereby preventing unwanted operation and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the drive device and hand wheel assembly are mechanically connected to allow independent operation, then operational versatility is improved, but uncontrollable spinning and safety risks occur when one drives the other
Solution Approach 1:
A one-way clutch mechanism is introduced as an intermediary component between the drive device and hand wheel assembly. This mediator allows unidirectional force transmission while blocking reverse transmission, preventing the harmful back-driving effect while maintaining the mechanical connection for versatile operation.
Solution Approach 2:
The mechanical connection between the drive device and hand wheel assembly is segmented into two separate functional paths: one allowing drive device to hand wheel transmission, and another allowing hand wheel to valve transmission. The one-way clutch creates this segmentation by permitting rotation in one direction while blocking it in the opposite direction.
2Object-affected harmful factors
If a locking assembly with high gear ratio is used to prevent motor from turning hand wheel, then back drive prevention is improved, but operational speed is reduced
Solution Approach 1:
The one-way clutch acts as a smart intermediary that selectively engages only when reverse rotation is detected. During normal manual operation, it remains disengaged, providing no resistance to rotation and maintaining full operational speed. When back-drive attempts occur, it engages to block the reverse motion, thus preventing back drive without sacrificing speed.
3Object-affected harmful factors
If a clamping device is used to lock hand wheel, then back drive prevention is improved, but ease of operation is reduced due to operator action required
Solution Approach 1:
The one-way clutch is a self-activating device that automatically engages and disengages based on the direction of rotation, without requiring any operator intervention. When the motor attempts to drive the hand wheel in reverse, the clutch self-activates to block the motion. During normal manual operation, it remains passive and does not interfere, thus maintaining ease of operation while providing automatic back-drive prevention.
4Object-affected harmful factors
If the gear train is designed to disengage from hand wheel when motor is energized, then back drive prevention is improved, but reliability is reduced due to high risk of failure
Solution Approach 1:
The one-way clutch provides a passive, mechanically simple intermediary solution that relies on centrifugal force and geometry rather than complex control systems. This simplicity reduces the number of failure points and eliminates the need for sensors, controllers, and complex disengagement mechanisms, thereby significantly improving reliability while still effectively preventing back-drive.
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 anti-back drive components effectively prevent the drive device and hand wheel assembly from interfering with each other's operation, enhancing operational efficiency, safety, and reducing occupational risks by ensuring controlled valve operation during power failures or malfunctions.
Implementation Method 1
the springs are arranged between a surface of the unlocking device and a surface of the locking device. When the locking device rotates about its axis, the shape and angular orientation of the channels of the locking device force the springs away from the axis, which pushes the pins into the channels of the unlocking device to generate friction that prevents rotation
Implementation Method 2
the shape and angular orientation of the channels of the unlocking device moves the springs toward the axis to a position relative to the channels of the locking device such that the rollers can rotate in place without leaving the channels of the locking device, which allows the entire anti-back drive component to rotate
Data Source
AI summary
Valve systems include a valve and a valve actuator assembly for operating the valve. The valve actuator assembly includes a drive device and a hand wheel assembly that can independently be used to cause movement of the valve. An anti-back drive component is coupled to the output of the drive device, the hand wheel assembly, or both. The anti-back drive component includes a locking device and an unlocking device, each with respective protrusions that cooperate to define cavities that house pairs of springs and rollers. The shape and orientation of the cavities allows for rotation of the rollers in the cavities and the anti-back drive component by rotating the unlocking device, while preventing rotation of the rollers and the anti-back drive component via rotation of the locking device to selectively prevent rotation of the output of the drive device, hand wheel assembly, or both.