Integrated Torque Limiter No-Back Device for Aircraft Actuators
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Solution Overview
Problem
Aircraft actuator systems face challenges in preventing damage from excessive torque during jamming events, as existing systems require separate torque limiting and no-back devices, leading to inefficiencies and increased weight and cost.
Innovation Solution
An integrated torque limiter/no-back device is designed with a combined ball ramp system that transfers torque and engages a brake when a threshold is exceeded, providing both torque limiting and no-back functionality in a single, compact unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate torque limiting and no-back devices are used in aircraft actuators, then each function can be independently optimized, but the overall system weight increases and device complexity increases
Solution Approach 1:
The patent combines separate torque limiting and no-back devices into a single integrated device. The torque limiter includes a torque limiter shaft, torque limiter balls, and torque limiter ramps, while the no-back device includes a no-back shaft, no-back balls, and no-back ramps. These components are integrated within a unified structure that shares common elements such as the actuator input shaft and housing, thereby reducing overall weight while maintaining independent optimization of each function.
Solution Approach 2:
The integrated device performs multiple functions simultaneously: it limits excessive torque during jamming events through the torque limiter mechanism, prevents backdriving of the actuator through the no-back mechanism, and provides structural support as part of the actuator assembly. The shared components serve dual purposes, reducing the need for separate dedicated parts for each function.
2Reliability
If separate torque limiting and no-back devices are used in aircraft actuators, then each function can be independently optimized, but device complexity and cost increase
Solution Approach 1:
The patent integrates the torque limiting and no-back devices into a single unified structure. The torque limiter shaft and no-back shaft are positioned concentrically within the actuator housing, sharing common mounting points and structural support. This merging reduces the number of separate assemblies and simplifies the overall device architecture while maintaining independent optimization of each protective function.
3Reliability
If traditional torque limiting devices are used on actuator input shaft, then force limiting function is provided, but response time is delayed and precision is reduced
Solution Approach 1:
The patent extracts the torque limiting and no-back functions from the traditional input shaft location and positions them directly at the actuator output. The torque limiter balls and ramps are arranged to engage directly with the actuator output shaft, and the no-back balls are positioned to prevent backdriving at the output end. This extraction eliminates the delay associated with torque transmission through the gear train, enabling immediate response to jamming conditions or backdriving attempts.
Solution Approach 2:
The integrated device is pre-configured with torque limiter balls positioned on torque limiter ramps and no-back balls positioned on no-back ramps, ready to engage immediately when threshold conditions are reached. The geometric arrangement of the ramps and balls ensures that torque limiting and backdriving prevention occur instantly upon exceeding design thresholds, without requiring signal processing or active control delays.
4Reliability
If traditional torque limiting devices are used on actuator input shaft, then force limiting function is provided, but precision and efficiency of torque management are reduced
Solution Approach 1:
The patent extracts the torque management functions from the input shaft location and implements them directly at the actuator output. This positioning allows for more precise control of torque transmission because the torque limiter and no-back mechanisms directly sense and respond to actual output torque conditions rather than inferred input torque, eliminating errors introduced by gear train variations and inefficiencies.
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
This solution reduces weight and cost by eliminating redundant parts, enhances precision by faster no-back braking, and ensures efficient torque management, preventing damage to flight surfaces during jamming events.
Implementation Method 1
a first plurality of balls arranged between the input ramp and the combined ramp, the first plurality of balls configured to transfer torque between the input ramp and the combined ramp
Implementation Method 2
a second plurality of balls arranged between the combined ramp and the output ramp, the second plurality of balls configured to transfer torque between the combined ramp and the output ramp
Implementation Method 3
the output ramp to engage the brake
Data Source
AI summary
An integrated torque limiter/no-back device for use in an actuator with an input shaft, an output, and a gear reduction. The device includes an input ramp, an output ramp coupled to the gear reduction, a combined ramp disposed between the input ramp and the output ramp, a first plurality of balls arranged between the input ramp and the combined ramp, a second plurality of balls arranged between the combined ramp and the output ramp, a pin, and a brake. The pin extends from the input ramp to the combined ramp and coupled to the input shaft. The combined ramp, the output ramp, and the second plurality of balls therebetween are configured to operate as a torque limiter by causing the combined ramp and the output ramp to separate and the output ramp to engage the brake when the torque from the input shaft exceeds a torque threshold.