Actuator Drag Brake Assembly for Emergency Decoupling
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Solution Overview
Problem
Mechanical linear actuators in aeronautical applications often require separate emergency systems that occupy additional space and hardware, which is not integrated with the normal drive configuration, posing a risk due to potential failures that can lead to catastrophic consequences.
Innovation Solution
An actuator assembly with an integrated emergency backup system that includes an electro-mechanical drive system and a gas generator, where pressurized gas automatically decouples the actuation member from the release member during an emergency, allowing the actuator to move to a predetermined position and mechanically lock in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate emergency systems are provided to override the mechanical linear drive system, then reliability is improved, but device complexity and space requirements increase
Solution Approach 1:
The emergency backup system is merged with the normal drive configuration by integrating the drag brake assembly into the existing actuator housing. The drag brake rack is integrated with the actuation tube, and the pinion gear shares the same rotational axis as the ball screw. This consolidation provides emergency functionality without requiring separate assemblies, reducing overall system complexity while maintaining reliability.
Solution Approach 2:
The drag brake assembly serves multiple functions: it provides emergency backup braking capability, controls extension speed during emergency operation, and can be activated automatically or manually. The same mechanical components (pinion gear, rack, brake shoes) serve both normal operation speed control and emergency backup functions, eliminating the need for dedicated emergency-only hardware.
2Reliability
If separate emergency systems are provided, then reliability is improved, but the amount of hardware and space required increases
Solution Approach 1:
The drag brake pinion gear is nested concentrically around the ball screw, sharing the same rotational axis. The drag brake rack is nested within the actuator housing and integrated with the actuation tube. This nested arrangement allows emergency backup components to occupy the same spatial envelope as the normal drive system, minimizing additional volume requirements while providing redundant functionality.
3Productivity
If the actuator extends rapidly during emergency operation, then productivity is improved, but harmful factors increase due to uncontrolled movement
Solution Approach 1:
The drag brake assembly provides continuous speed control during emergency extension by maintaining constant frictional contact between the brake shoes and pinion gear. This continuous braking action prevents uncontrolled rapid movement while still allowing the actuator to extend at a controlled rate, eliminating the harmful effects of uncontrolled motion while preserving the productivity benefit of emergency 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 integrated emergency backup system ensures safe and reliable operation by automatically decoupling the actuator components during failures, allowing for full extension and locking of critical systems like landing gear, even if failures occur during normal operation, without the need for additional space or hardware.
Implementation Method 1
The drag brake assembly may include a drag brake pinion, a drag brake rack, and one or more drag brakes configured to engage the drag brake pinion
Data Source
AI summary
An actuator assembly includes an actuation member, a release member, and a source of pressurized gas, wherein during a normal mode of operation, the actuation member and the release member are engaged to move in unison, and wherein during an emergency mode of operation, pressurized gas automatically decouples the actuation member from the release member to move separately. In accordance with yet other aspects of the disclosure, an electro-mechanical actuator includes an electro-mechanical drive system and an integrated backup system operated by a gas generator, wherein when the backup system is activated, the electro-mechanical drive system is decoupled and the actuator moves to a predetermined position and mechanically locks in place.