Aircraft Torque Tube Spline Coupling for Wing Flex Alignment

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Solution Overview

Problem

Existing torque tube assemblies in aircraft high lift devices face issues with large rotational envelopes, bolt loosening, and structural integrity due to wing flexing, which affects the alignment and strain on the torque tube assemblies.

Innovation Solution

The use of spline couplings with retainer mechanisms in torque tube assemblies allows for axial and angular movement, reducing strain and force on the assembly, and provides a more compact design with fewer fasteners, while preventing disconnection and corrosion through grease retainer systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If bolted flanges or plates are used to couple torque tube to pinion gear or GRA, then the connection is secure, but the rotational envelope becomes large requiring more space

Engineering Contradiction:

Improveconnection securityVSAvoidspace requirement

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The coupling mechanism is divided into modular components: a spline coupling with multiple splines, a drive shaft with corresponding splines, and a retainer. This segmentation allows for a more compact design compared to traditional bolted flanges while maintaining secure connection through the distributed spline engagement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The retainer is designed to be movable along the drive shaft, allowing dynamic adjustment to accommodate wing flexing and alignment changes. This dynamic capability enables the coupling to adapt to varying operational conditions while maintaining a compact footprint.

Inventive Principle:

Principle #15Dynamics

2Strength

If traditional coupling methods are used, then the connection is rigid, but bolts can loosen reducing structural integrity

Engineering Contradiction:

Improvestructural integrityVSAvoidbolt loosening resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The traditional bolted mechanical connection is replaced with a spline-based mechanical engagement system. The splines on the spline coupling engage with corresponding splines on the drive shaft, creating a rigid connection that distributes loads across multiple contact points, eliminating the loosening issue inherent in bolted connections.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The retainer provides a rigid connection through the spline engagement while maintaining the ability to move axially along the drive shaft. This allows the connection to remain rigid against rotational and lateral forces while accommodating axial movements due to wing flexing, preventing the loosening that occurs in fixed rigid connections.

Inventive Principle:

Principle #15Dynamics

3Power

If fixed alignment coupling is used, then torque transfer is efficient, but additional forces and strain occur due to wing flexing

Engineering Contradiction:

Improvetorque transfer efficiencyVSAvoidstrain on torque tube

Core Design Contradiction:

PowerVSForce

Solution Approach 1:

The retainer is designed to move axially along the drive shaft, enabling the coupling to dynamically adjust its position in response to wing flexing. This movement maintains optimal alignment and torque transfer efficiency while absorbing the additional forces and strains generated by wing flexing, preventing these forces from being transmitted to the torque tube.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The retainer acts as an intermediary element between the rigid spline engagement and the flexible wing structure. It provides a stable mechanical connection for torque transfer while serving as a movable interface that accommodates wing flexing, thereby protecting the torque tube from excessive forces.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Ease of manufacture

If compact design with fewer fasteners is used, then installation is easier, but risk of disconnection increases

Engineering Contradiction:

Improveinstallation easeVSAvoiddisconnection prevention

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The retainer is designed with a movable capability along the drive shaft that allows it to be easily installed and removed, simplifying assembly and maintenance operations. Simultaneously, when in its operational position, it provides robust mechanical engagement through the spline system that prevents disconnection under load.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The coupling system is segmented into distinct components (spline coupling, drive shaft, retainer) that can be assembled separately and then easily connected. This modular approach simplifies installation while the interlocking spline features ensure that once assembled, the connection is secure and resistant to disconnection.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11060566B2Apparatus and methods for rigging a torque tube assembly in an aircraft

Publication Date: 2021.07.13 THE BOEING CO

AI summary

A torque tube assembly includes a torque tube and a spline coupling coupled to an end of the torque tube. The spline coupling has an opening to receive a spline gear on a drive shaft of an aircraft high lift device. The torque tube assembly also includes a retainer coupled to the spline coupling. The retainer blocks at least a portion of the opening in the spline coupling to prevent the spline coupling from being moved off of the spline gear on the drive shaft.