Aircraft Control Surface Drive System Redundancy
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Solution Overview
Problem
Existing aircraft drive systems for control surfaces, such as flaps and slats, rely on mechanical coupling between adjacent surfaces, which limits redundancy and makes it difficult to detect failures or skewed control surfaces reliably.
Innovation Solution
A drive system utilizing a differential gear mechanism with rotary actuators and torque limiters, allowing for independent operation of control surfaces without mechanical coupling, enabling reliable failure detection and reduced load on components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical coupling between adjacent control surfaces is used, then redundancy is provided, but device complexity increases and failure detection becomes difficult
Solution Approach 1:
The drive system is segmented into multiple independent adjusting units, each with its own differential and rotary actuators. Each control surface is driven by its own adjusting unit rather than being mechanically coupled to adjacent surfaces, allowing independent operation and failure detection while maintaining redundancy through the differential mechanism's multiple load paths
Solution Approach 2:
The differential mechanism acts as an intermediary that distributes torque to multiple rotary actuators independently. This mediator allows each actuator to operate autonomously without direct mechanical coupling between control surfaces, yet maintains system redundancy through the differential's inherent load distribution capability
2Reliability
If mechanical coupling between adjacent flaps is provided, then redundancy is achieved, but differential flap setting function becomes impossible
Solution Approach 1:
Each flap is equipped with its own adjusting unit containing a differential and rotary actuators, enabling independent control of each flap. This segmentation allows differential flap settings where adjacent flaps can be positioned at different angles while maintaining redundancy through the differential mechanism
Solution Approach 2:
The system enables dynamic and flexible flap configurations by allowing each adjusting unit to operate independently. The differential mechanism dynamically distributes torque to achieve various flap positions, including differential settings where flaps are at different angles, adapting to different flight conditions
3Strength
If torque limiters are installed in load paths, then component load is reduced, but device complexity increases
Solution Approach 1:
The torque limiters are designed to automatically activate when predetermined torque thresholds are exceeded, without requiring external control systems. The load distribution mechanism self-regulates by redirecting loads away from failed components, and the torque limiters self-actuate to protect components, reducing the need for complex external monitoring and control systems
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 design enhances flight performance by eliminating the need for excessive load-bearing components and provides reliable detection of drive system failures, ensuring safe and efficient operation of control surfaces.
Implementation Method 1
The differential has at least one input means and two output means and is adapted for transferring torque from the at least one input means to the two output means
Implementation Method 2
If the adjustment lever comprises two load paths, the first load path may be connected to one of the output means and the second load path to the other output means
Data Source
Figure 1a~1b
Figure 2~3a
Figure 3b~3c
AI summary
A drive system (2) for driving control surfaces (10, 12) of an aircraft comprises at least one drive unit (4), at least one main shaft (6) connectable to the at least one drive unit (4) and at least two adjusting units (8) for each control surface (10, 12) to be driven. Each adjusting unit (8) comprises a differential (14), two rotary actuators (16) and an adjustment lever (18). The differential (14) has at least one input means and two output means and is adapted to transfer torque from the at least one input means to the two output means. The input means is connectable to the main shaft (6), the two rotary actuators (16) each have a rotation input means and a motion output means. The rotation input means is connectable to one of the output means (30) of the differential (14) each and the adjustment lever (18) is connected to the motion output means of both rotary actuators (16). Thereby two load paths are realized for each adjustment lever such that a mechanical connection between adjacent control surfaces is not necessary for maintaining a certain level of redundancy.