Valve Actuator Anti-Back Drive Assembly for Manual-Motor Decoupling
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Solution Overview
Problem
Conventional electric valve actuators face inefficiencies and safety issues due to the interdependence of the electric motor and hand wheel assembly, leading to operational inefficiencies and potential safety hazards during power failures or motor malfunctions.
Innovation Solution
The integration of 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 force transmission while preventing reverse rotation, thereby decoupling the motor and hand wheel operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the electric motor and hand wheel assembly are mechanically connected to allow independent operation, then operational flexibility is improved, but operational efficiency and component reliability deteriorate due to unintended rotation and back-driving
Solution Approach 1:
A one-way coupling mechanism is introduced as an intermediary between the electric motor and hand wheel assembly. This mechanism includes a drive train with a one-way clutch or overrunning clutch that allows torque transmission from the motor to the hand wheel during motor operation, but prevents reverse torque transmission when the hand wheel is manually operated, thereby eliminating back-driving while maintaining operational flexibility
Solution Approach 2:
The mechanical connection between the motor and hand wheel assembly is segmented into two distinct operational modes: motor-driven mode where the one-way clutch engages to transmit motor torque, and manual operation mode where the one-way clutch disengages to allow free hand wheel rotation. This segmentation allows each mode to function independently without interfering with the other, resolving the reliability issue while preserving versatility
2Reliability
If a locking assembly with high gear ratio is used to prevent motor from turning hand wheel, then prevention of unintended rotation is improved, but operational speed deteriorates
Solution Approach 1:
A one-way clutch is used as an intermediary device that selectively engages and disengages based on the direction of torque application. During motor operation, the clutch engages to prevent hand wheel rotation; during manual operation, the clutch disengages to allow free rotation. This eliminates the need for a high gear ratio locking mechanism, thereby maintaining operational speed while still preventing unintended rotation
Solution Approach 2:
The locking mechanism transitions from a static high gear ratio system to a dynamic one-way clutch system that automatically adapts its state based on operational conditions. The clutch dynamically engages when motor torque is applied and disengages when manual torque is applied, providing the necessary prevention of unintended rotation without compromising operational speed
3Reliability
If a clamping device is used to prevent hand wheel rotation, then prevention of unintended rotation is improved, but ease of operation deteriorates due to operator action requirements
Solution Approach 1:
The one-way clutch automatically performs the locking function without requiring operator intervention. When the motor drives the drive train, the clutch self-engages to prevent hand wheel rotation. When the operator manually rotates the hand wheel, the clutch self-disengages to allow rotation. This self-service mechanism eliminates the need for operator action to engage or disengage a clamping device, thereby maintaining ease of operation while ensuring reliable prevention of unintended rotation
4Reliability
If the gear train disengages with the hand wheel assembly when motor is energized, then prevention of back-driving is improved, but system complexity and risk of failure increase
Solution Approach 1:
A one-way clutch is introduced as a simple intermediary component within the gear train that provides automatic disengagement functionality. The clutch engages when motor torque is applied, effectively disconnecting the hand wheel assembly from the motor output. This simple mechanical component replaces complex multi-part disengagement mechanisms, thereby reducing overall system complexity while maintaining reliable prevention of back-driving
Solution Approach 2:
The one-way clutch extracts the back-driving prevention function from a complex multi-component disengagement system and implements it through a single, reliable mechanical component. This extraction simplifies the overall system architecture by removing unnecessary complexity while maintaining the essential function of preventing back-driving during 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
This solution enhances operational efficiency and safety by preventing unintended motor or hand wheel rotation, ensuring reliable valve operation and reducing occupational risks during power outages or system failures.
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 of the entire anti-back drive component
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.