Crowned Spline Joint for Landing Gear Drive Misalignment
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Solution Overview
Problem
Aircraft ground taxiing is inefficient due to high fuel consumption and brake wear, and existing systems are laborious and costly when main engine thrust is not feasible, necessitating a more effective drive system for aircraft landing gear wheels.
Innovation Solution
A drive system featuring a pinion gear, drive shaft, and a flexible interface with a crowned spline joint that allows tilting and translation, enabling the system to accommodate wheel axle deflections and deformations, thereby maintaining efficient operation and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rigid connection is used between the drive shaft and pinion gear, then the drive system structure is simple, but the system cannot accommodate wheel axle deflections and misalignment occurs
Solution Approach 1:
The patent applies a flexible interface comprising a crowned spline joint between the drive shaft and pinion gear. This flexible connection allows relative tilting and translation to accommodate wheel axle deflections while maintaining torque transmission, resolving the contradiction between adaptability and structural simplicity.
2Productivity
If main engines are used for ground taxiing, then propulsion is achieved, but fuel consumption increases and brake wear increases
Solution Approach 1:
The patent enables the aircraft to taxi itself using an electric motor-driven pinion gear system that directly drives the wheels, eliminating the need for engine thrust and external tow trucks. This self-service capability reduces fuel consumption and brake wear while maintaining ground mobility.
3Ease of operation
If a clutch is used to switch between free spin and motor drive modes, then wheel rotation control is achieved, but device complexity increases
Solution Approach 1:
The patent extracts the clutch mechanism from the drive system and replaces it with a crowned spline joint that passively accommodates misalignment through flexible tilting and translation. This eliminates the need for active clutch engagement while maintaining wheel rotation control capability.
4Power
If toothed pinion gear and ring gear are used for wheel drive, then torque transmission is efficient, but misalignment causes distortion and wear
Solution Approach 1:
The patent makes the connection between drive shaft and pinion gear dynamic and flexible through the crowned spline joint, allowing the pinion gear to tilt and translate relative to the drive shaft. This dynamic flexibility maintains proper gear meshing and prevents distortion while preserving torque transmission efficiency.
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 flexible interface reduces misalignment and distortion, enhancing the efficiency and durability of the drive system, reducing fuel consumption and brake wear, and allowing for autonomous taxiing without laborious tow truck operations.
Implementation Method 1
a flexible interface comprising a crowned spline joint between the drive shaft and the pinion gear to permit tilting of the pinion gear relative to the drive axis
Implementation Method 2
the crowned spline joint is also arranged to permit translation of the pinion gear along the drive axis
Data Source
AI summary
A drive system for an aircraft landing gear, the drive system comprising: a pinion gear; a drive shaft arranged to rotate the pinion gear about a drive axis; a driven gear arranged to mesh with the pinion gear to be rotatable by the pinion gear, the driven gear being connectable to a wheel of the landing gear to be capable of rotating the wheel about a wheel axis; and a flexible interface comprising a crowned spline joint between the drive shaft and the pinion gear. The crowned spline joint is arranged to permit tilting of the pinion gear relative to the drive axis. In some embodiments a first spline joint between the drive shaft and the pinion gear is arranged to permit tilting of the pinion gear relative to the drive axis; and a second spline joint is arranged to permit translation of the pinion gear along the drive axis relative to the drive shaft.