Flexible Drive Shaft Coupling for Aircraft Control Surfaces
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Solution Overview
Problem
Existing aircraft control surface movement apparatuses require a large force to overcome locking interactions at polygonal surfaces, making relative movement between actuators and flexible drive shafts inefficient.
Innovation Solution
A coupling assembly with rotatable balls interconnects the flexible drive shaft and actuator assembly, allowing for relative movement with reduced resistance, and includes a worm gear and ball nut assembly to manage excessive resistance by shifting the worm gear and engaging a brake assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polygonal coupling is used to connect the flexible drive shaft and actuator, then the connection is secure and stable, but a relatively large force is required to overcome the locking interaction at the polygonal surfaces for relative movement
Solution Approach 1:
The patent replaces the polygonal coupling with a spherical coupling mechanism. The flexible drive shaft is provided with a spherical coupling that can rotate relative to the actuator shaft, allowing smooth relative movement without the locking interactions characteristic of polygonal surfaces. This spherical geometry eliminates the need to overcome interlocking surfaces while maintaining secure connection.
Solution Approach 2:
The patent introduces a dynamic coupling mechanism where the spherical coupling can rotate and adapt its orientation. This dynamic capability allows the coupling to accommodate relative movement between the flexible drive shaft and actuator shaft through rotational motion, rather than requiring force to overcome static locking interactions at polygonal surfaces.
2Force
If a spherical coupling is used to allow relative movement between the flexible drive shaft and actuator, then the force required is reduced, but the device complexity increases due to additional components
Solution Approach 1:
The patent combines the coupling function with the flexible drive shaft itself by providing the spherical coupling directly on the flexible drive shaft. This integration reduces the number of separate components and simplifies the overall structure, while still achieving the desired relative movement capability with reduced force requirements.
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 enables efficient movement of aircraft control surfaces with reduced force requirements and accommodates axial movement of the worm gear, effectively managing resistance and maintaining operation.
Implementation Method 1
A plurality of balls interconnect the input and output members and are rotatable to accommodate relative movement between the input and output members
Implementation Method 2
includes a worm gear and ball nut assembly to manage excessive resistance by shifting the worm gear and engaging a brake assembly
Data Source
AI summary
An apparatus for use in moving a control surface during operation of an aircraft includes a flexible drive shaft to be connected with an actuator assembly by a coupling assembly. Operation of the actuator assembly operates a force transmission apparatus to move a control surface on an aircraft. The coupling assembly includes an input member connected with the flexible drive shaft and an output member which may be connected with the actuator assembly. A plurality of balls interconnect the input and output members and are rotatable to accommodate relative movement between the input and output members.