Trigger Brake and Roller Jamming for Low-Drag Shaft Braking
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Solution Overview
Problem
Current braking devices in aircraft actuator systems experience undesirable drag and are bulky due to the use of multiple static and dynamic friction plates, which increase the load on the power drive unit and are not suitable for limited space applications.
Innovation Solution
A brake device with a selectively operable trigger brake and roller jamming mechanism, utilizing a preloaded torsion spring and electro-mechanical actuator to stop the input shaft rotation by overcoming the preload, reducing the need for traditional friction plates and minimizing the device's size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple static and dynamic friction plates are used for braking, then braking effectiveness is improved, but device size and weight increase
Solution Approach 1:
The patent extracts and eliminates the traditional multiple friction plates from the braking system. Instead of using stacked friction plates, the invention employs a single friction element that contacts the input shaft directly, dramatically reducing the weight and complexity of the braking device while maintaining effective braking capability through the roller jamming mechanism.
Solution Approach 2:
The invention changes the fundamental operating parameters of the brake by using a roller jamming mechanism that converts rotational movement into axial movement of rollers, which then jam against the friction element. This parameter change allows effective braking with a single friction element rather than multiple plates, reducing weight while maintaining braking effectiveness.
2Reliability
If multiple static and dynamic friction plates are used for braking, then braking effectiveness is improved, but device complexity increases
Solution Approach 1:
The patent removes the complex multi-plate friction plate assembly and replaces it with a simplified mechanism consisting of a single friction element, a torsion spring, and a roller jamming mechanism. This extraction of unnecessary components dramatically reduces device complexity while preserving braking effectiveness.
Solution Approach 2:
The braking function is segmented into distinct operational phases: a trigger phase where the friction element engages to initiate braking, and a jamming phase where rollers engage to lock the system. This segmentation allows each component to be simpler and more specialized, reducing overall device complexity.
3Reliability
If traditional friction plates are used, then braking function is achieved, but drag on power drive unit increases
Solution Approach 1:
The patent employs a dynamic roller jamming mechanism that transitions from a disengaged state during normal operation to an engaged state during braking. The rollers are spring-loaded and only contact the friction element when braking is required, eliminating continuous drag on the power drive unit while maintaining braking readiness.
Solution Approach 2:
The torsion spring automatically returns the rollers to their disengaged position after braking, and the system self-regulates to minimize drag during non-braking operation. The friction element only contacts the input shaft when necessary, and the mechanism automatically resets without external intervention, reducing energy loss.
4Force
If brake components are arranged radially, then braking force is improved, but space envelope increases
Solution Approach 1:
The patent transitions from a radial braking force arrangement to an axial arrangement. The friction element contacts the input shaft axially, and the rollers move axially to engage the friction element. This dimensional change allows the brake to fit within a compact axial space envelope while maintaining effective braking force through the mechanical advantage of the roller jamming mechanism.
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 solution effectively reduces drag and size, allowing for efficient braking with minimal power absorption and compact design, suitable for applications in thin wing aircraft where space is limited.
Implementation Method 1
a preloaded torsion spring rotationally coupled to the input shaft but permitting a limited rotational movement between the trigger brake shaft and the input shaft
Implementation Method 2
a roller jamming mechanism operable upon the relative rotation between the trigger brake shaft and the input shaft exceeding a predetermined amount to stop rotation of the input shaft upon operation of the trigger brake
Implementation Method 3
a radial surface of the trigger brake shaft may be axially engageable with the static element to effect a frictional braking of the trigger brake shaft
Data Source
AI summary
A brake device for braking rotation of an input shaft includes a selectively operable trigger brake that includes: a static element; a trigger brake shaft mounted for rotational and axial movement relative to the static element and the input shaft; a preloaded torsion spring rotationally coupled to the input shaft but permitting a limited rotational movement between the trigger brake shaft and the input shaft; a roller jamming mechanism operable upon the relative rotation between the trigger brake shaft and the input shaft exceeding a predetermined amount to stop rotation of the input shaft upon operation of the trigger brake; and a brake actuator for selectively moving the trigger brake shaft into and out of engagement with a contact surface of the static element. Engagement of the contact surface of the static element and the trigger brake shaft overcomes the preload of the torsion spring.