Rotary Actuator Friction Lock for Fail-Fix Position Holding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Actuator assemblies in turbo machines experience undesired movement and operational failures due to loss of input signal or pressure, leading to uncommanded changes in vane angle, which can cause stalls or surges, and existing fail-safe systems are heavy and complex.
Innovation Solution
A rotary actuator assembly with a fail fix system that includes a stop collar or servo piston keyed into a surrounding body, a spring to maintain load, and a friction mechanism to prevent rotation of the output shaft upon loss of signal, using a control valve to balance loads and engage the friction mechanism to mitigate undesired movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fail-safe mechanism is added to prevent undesired movement after actuator failure, then reliability is improved, but device complexity increases
Solution Approach 1:
The fail-safe friction mechanism is integrated directly into the actuator assembly, merging the fail-safe function with the existing actuator structure. This eliminates the need for separate external fail-safe components and reduces overall system complexity while maintaining reliability.
Solution Approach 2:
The spring-loaded friction mechanism automatically engages when control pressure is lost, providing self-activating fail-safe protection without requiring external sensors, controllers, or additional actuation systems. The mechanism serves itself by using the loss of control pressure as the triggering condition.
2Reliability
If a fail-safe mechanism is added to prevent undesired movement after actuator failure, then reliability is improved, but weight increases
Solution Approach 1:
The fail-safe friction mechanism is integrated directly into the actuator assembly, merging the fail-safe function with the existing actuator structure. This eliminates the need for separate external fail-safe components and reduces overall system complexity while maintaining reliability.
Solution Approach 2:
The spring-loaded friction mechanism automatically engages when control pressure is lost, providing self-activating fail-safe protection without requiring external sensors, controllers, or additional actuation systems. The mechanism serves itself by using the loss of control pressure as the triggering condition.
3Reliability
If multiple separate components are used for fail-safe protection, then reliability is improved, but ease of manufacture decreases
Solution Approach 1:
The fail-safe friction mechanism is integrated directly into the actuator assembly, merging the fail-safe function with the existing actuator structure. This eliminates the need for separate external fail-safe components and reduces overall system complexity while maintaining reliability.
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 system effectively prevents undesired movement of the actuator system following control signal failure, maintaining the last commanded position and reducing the risk of turbo machine stalls or surges, while also reducing weight and complexity compared to existing systems.
Implementation Method 1
a spring (126) to maintain a load on the first end (123) of the servo piston (124)
Implementation Method 2
a friction mechanism (122) coupled to the second end (125) of the servo piston (124) to prevent rotation of the input drive assembly (130)
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
An actuator assembly (90) including a fail-fix system is provided. The actuator assembly (90) includes an output shaft (110), an input drive assembly (130), and a piston assembly (120). The piston assembly (120) includes a body (115) surrounding a piston (124) moveable within the body (115). The body (115) defines a first end (123) and a second end (125) opposite thereof between which the piston (124) is moveable within the body (115). The piston assembly (120) includes a spring (126) disposed at the first end (123) between the body (115) and the piston (124). The piston assembly (120) includes a friction mechanism (122) disposed at the second end (125) of the piston (124) opposite of the first end (123). An adjustable area (135) is defined within the body (115) between the second end (125) of the piston (124) and the input drive assembly (130).