Valve Actuator Self-Lock Mechanism With Low-Friction Roller Release
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Solution Overview
Problem
Existing self-lock mechanisms for butterfly valves create unnecessary friction and increase the size and power consumption of actuator motors, leading to heat and wear issues, while also requiring current to maintain the valve position when the motor is off, and fail to prevent valve rotation by torque from fluid or sealing contact.
Innovation Solution
A self-lock mechanism using rollers separated by a spring or wing, activated and deactivated by the motor, which allows rotation from one side while preventing it from the other, and automatically engages or disengages based on motor torque, reducing friction and power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a friction brake or gear with high friction is used to prevent valve rotation, then the valve can be kept in position without power, but the motor size must be increased and power efficiency decreases
Solution Approach 1:
A pawl mechanism is introduced as an intermediary between the motor shaft and the valve connection. This pawl selectively engages with ratchet teeth to prevent rotation in one direction while allowing rotation in the other direction, eliminating the need for high-friction brakes and reducing motor size requirements
Solution Approach 2:
The friction-based braking system is replaced with a mechanical locking system using pawls and ratchet teeth. This substitution eliminates continuous friction losses while maintaining the ability to hold position without power, improving overall system efficiency
2Reliability
If a friction brake is used to prevent valve movement, then the valve remains stationary when powered off, but heat and wear increase due to continuous friction
Solution Approach 1:
The pawl-ratchet mechanism acts as an intermediary that provides mechanical locking without continuous friction. The pawl engages with ratchet teeth only when needed to prevent back-rotation, eliminating continuous friction-induced heat and wear while maintaining position stability
Solution Approach 2:
The harmful continuous friction element is extracted from the system by replacing it with a selective engagement mechanism. The pawl only contacts the ratchet teeth when rotation in the wrong direction is attempted, removing the source of continuous heat and wear generation
3Reliability
If an irreversible lock is used between gear and motor, then the valve can be locked in position, but unnecessary friction increases and motor size must be increased
Solution Approach 1:
The pawl-ratchet mechanism employs asymmetric geometry where the pawl easily engages with the ratchet teeth in one direction but allows free rotation in the opposite direction. This asymmetric design provides selective locking that prevents energy loss only when needed, rather than creating continuous friction
Solution Approach 2:
The pawl serves as an intermediary element that selectively transmits or blocks torque based on rotation direction. It allows torque transmission in the driving direction while blocking reverse torque, eliminating unnecessary friction losses while maintaining position stability
4Reliability
If the motor must produce torque to keep the valve in position, then the valve remains stable, but current must flow continuously through the motor
Solution Approach 1:
The system uses the motor's own rotation to automatically engage the pawl with the ratchet teeth, creating a self-locking mechanism. Once engaged, the mechanical lock maintains position without requiring continuous motor current, allowing the motor to enter standby mode with minimal or zero power consumption
Solution Approach 2:
The pawl-ratchet mechanism serves as an intermediary that decouples the motor from the load when positioning is required. The mechanical lock takes over the position-holding function, allowing the motor to stop drawing current while maintaining valve position through pure mechanical means
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 mechanism effectively prevents valve rotation by torque from fluid or sealing contact when the motor is off, reduces friction and power consumption, and maintains the valve position without continuous motor current, enhancing reliability and efficiency.
Implementation Method 1
A self lock mechanism for rotating actuators... comprising of one or more sets of rollers separated by a spring... which will press one of the rollers in each set against the wall of the housing and causing a locking effect
Implementation Method 2
press one of the rollers in each set against the wall of the housing and causing a locking effect if the mechanism is attempted to be twisted from the valve side
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3~4
AI summary
This publication relates to a self lock mechanism (100) for rotating actuators, which allow rotation form one side while deny rotation from the other side. The mechanism (100) comprising one or more sets of rollers (113) possibly separated by a spring means (114, 118) and arranged between a housing (101) and a valve connection part (102). The valve connection (102) may be configured with a shape which will press one of the rollers (113) in each set against the inner surface of the housing (101) wall and cause locking if the mechanism is attempted twisted from the valve side. Further the mechanism is provided with a motor connection part (105) configured so that it will press the rollers (113) out of locking position and release the locking before the motor connection part (105) makes contact with the valve connection part (102) and start transferring torque. If a spring (114, 118) is provided between the rollers (113), the spring (114, 118) may have a stiffness and a length so as to provides a force which is sufficient for keeping the rollers (113) in position but not sufficient to cause considerable friction between rollers (113) and housing (101), and thereby allow a motor to rotate the gear trough the self lock mechanism (100) with relatively small torque and power losses in the self lock mechanism (100). In lieu of the springs (114, 118), the rollers (113) may be separated and kept in place by a wing (117) on the valve connection part (102).