Cone Brake No-Back Assembly with Gain Reduction Spring
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Solution Overview
Problem
Aircraft actuators without no-backs may experience back-drive when the drive line torque shaft fails, leading to unwanted displacement of aircraft surfaces, compromising aircraft control.
Innovation Solution
A no-back assembly with radially outward discs, brakes, and springs that prevent rotation in a no-back condition, coupled with a gain reduction spring to minimize dynamic loading and enhance operational stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a no-back assembly is added to prevent back-drive, then aircraft control reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple brake assemblies into a single no-back assembly that integrates two cone brakes with shared components (housing, springs, pins). This merging approach provides redundant braking capability for reliable back-drive prevention while reducing overall complexity compared to separate brake systems.
Solution Approach 2:
The no-back assembly is segmented into modular components including two independent brake assemblies, each with its own disc, brake, and spring mechanism. This segmentation allows for simplified manufacturing, easier maintenance, and reliable operation where each segment can function independently to prevent back-drive.
2Reliability
If spring force is increased to improve braking reliability, then frictional force increases, but dynamic loading and vibration increase
Solution Approach 1:
The patent uses two springs instead of one, providing partial action from each spring to achieve the required total braking force. This distribution of spring force reduces dynamic loading and vibration compared to a single high-force spring, while maintaining reliable braking through the combined effect of both springs.
Solution Approach 2:
The patent optimizes spring parameters including wire diameter, mean coil diameter, and number of active coils to achieve the desired balance between braking force and dynamic loading reduction. By carefully selecting these parameters, the system maintains reliable braking while minimizing vibration and noise generation.
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
Effectively prevents unwanted displacement of aircraft surfaces by creating a sufficient frictional force to counteract torque imbalances, ensuring aircraft control and reducing vibration and noise through optimized mechanical compliance.
Implementation Method 1
the spring configured to urge the first brake toward the first disc to prevent the first disc from rotating when in the no-back condition
Implementation Method 2
the gain reduction spring biases the piston against the first side of pin, wherein a second side of the pin is biased against a retaining ring of the housing
Data Source
AI summary
A no-back assembly includes a first disc coupled to a first shaft and arranged radially outward of the first shaft. Also included is a first brake arranged radially outward of the first disc. Further included is a spring adjacent the first brake. Yet further included is a second disc coupled to a second shaft and arranged radially outward of the second shaft. Also included is a second brake arranged radially outward of the second disc. Further included is at least one pin operatively coupling the first brake and the second brake to a housing of the no-back assembly, a gain reduction spring disposed within a recess of the housing, and a piston disposed in contact with the gain reduction spring and a first side of the pin, wherein the gain reduction spring biases the piston against the first side of pin, wherein the pin is biased against the housing.