Folding Wing Hinge Spline Coupling for Load Isolation
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Solution Overview
Problem
Current folding wing hinge designs for aircraft fail to effectively isolate flight loads between the fixed and folding wing portions, leading to inefficient load distribution and potential structural stress during folding and unfolding operations.
Innovation Solution
The proposed folding wing hinge incorporates a hinge pin with a crowned tooth surface and an input fitting spline, coupled with a spline coupling member, allowing for relative movement and forming universal joints to isolate flight loads through a load path that passes through hinge pin bushings, thereby distributing loads efficiently and reducing structural stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a folding wing hinge design is used to enable wing portion movement, then the wingspan can be adjusted for aerodynamic efficiency, but flight loads are not effectively isolated between fixed and folding wing portions leading to structural stress
Solution Approach 1:
The hinge assembly is segmented into distinct functional components: a hinge pin with external spline, an input fitting with internal spline, and a spline coupling member. This segmentation allows independent optimization of each component for its specific function while collectively achieving both movement capability and load isolation.
Solution Approach 2:
The spline coupling member acts as an intermediary element between the hinge pin and input fitting. It transmits torque while allowing relative axial movement, and works in conjunction with the crowned tooth surfaces to form universal joints that provide both motion freedom and load path isolation through the hinge pin bushings.
2Strength
If a rigid coupling is used between hinge pin and input fitting, then structural strength is improved, but the ability to isolate flight loads and reduce structural stress is reduced
Solution Approach 1:
The coupling between the hinge pin and input fitting is made dynamic rather than rigid. The spline coupling member with crowned tooth surfaces allows the hinge pin to move axially relative to the input fitting while maintaining torque transmission. This dynamic coupling enables the system to adapt to load variations and isolate flight loads through the hinge pin bushings, reducing structural stress.
Solution Approach 2:
The crowned tooth surfaces on the splines enable parameter changes in the coupling characteristics. The curvature of the tooth surfaces allows for controlled relative movement and load distribution, transforming the coupling from a fixed rigid connection to a flexible connection that can accommodate movement while maintaining strength and isolating loads.
3Reliability
If crowned tooth surfaces with universal joints are implemented, then load isolation and movement capability are improved, but device complexity increases
Solution Approach 1:
The spline coupling member with crowned tooth surfaces serves multiple functions simultaneously: it transmits torque, allows relative axial movement, and forms universal joints with both the hinge pin and input fitting. This multi-functionality reduces the need for separate components, thereby managing complexity while achieving load isolation and movement capability.
Solution Approach 2:
The spline coupling member is nested within the hinge pin and input fitting assembly. The external spline of the hinge pin engages with the internal straight-sided spline of the coupling member, which in turn engages with the external spline of the input fitting. This nested arrangement integrates multiple functional elements into a compact structure, managing complexity through efficient spatial organization.
Data Source
Figure 1
Figure 2A
Figure 2B~2C
AI summary
There is described A folding wing hinge (210) for a wing (102) having a fixed wing portion (204)and a folding wing portion (202), the folding wing hinge (210) comprising: a hinge pin (600) including a hinge pin spline (700) and having a first longitudinal axis (790); an input fitting (610) coupled to one of the fixed wing portion (204) and the folding wing portion (202), the input fitting (610) including an input fitting spline (705, 705A) and a second longitudinal axis (791); and a spline coupling member (620) having a coupling spline configured to couple with the hinge pin spline (700) and the input fitting spline (705, 705A) so that the first longitudinal axis (790) is moveable relative to the second longitudinal axis (791) by a first predetermined amount of movement; wherein the hinge pin spline (700) is an external spline (809) having teeth (800) with a crowned tooth surface and the coupling spline (710) includes a first mating spline portion (710) having an internal straight-sided spline; and wherein one of: a) the input fitting spline (705) is an external spline (709) having teeth (770) with a crowned tooth surface and the coupling spline (710) includes a second mating spline portion (712A) having an internal straight-sided spline, wherein the respective crowned tooth surfaces of each of the hinge pin spline and the input fitting spline form respective universal joints with the coupling spline; and b) the input fitting spline (705A) is an internal straight-sided spline and the coupling spline (710) includes a second mating spline portion (712A) having teeth with a crowned tooth surface, wherein respective crowned tooth surfaces of the hinge pin spline and tooth surfaces of the input fitting spline form respective universal joints with the coupling spline (710).