Variable Diameter Friction Drive for Aircraft Landing Gear
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Autonomous taxiing systems for aircraft require high torque output, but compact, lightweight motors suitable for aircraft tend to have high-speed/low-torque outputs that are inadequate for driving aircraft wheels, and existing solutions introduce additional rotating components that can fail and cause retarding torque during takeoff.
Innovation Solution
A landing gear system with a drive assembly that includes a variable-diameter drive element and idler elements, which are disengaged when not in use to prevent rotation and re-engaged to transfer high-speed/low-torque input into low-speed/high-torque output to the wheels, using a biasing element and actuators to adjust the diameter and position of the idler elements for engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If compact, lightweight motors are used for aircraft landing gear, then weight is reduced, but torque output becomes insufficient for driving aircraft wheels
Solution Approach 1:
A friction drive system acts as an intermediary between the motor and the wheel, using a drive element with variable diameter and idler elements to multiply torque. The motor drives the variable-diameter drive element, which through friction contact with idler elements, transfers and amplifies torque to the wheel without requiring a large, heavy motor
Solution Approach 2:
The drive element's diameter is varied dynamically to change the mechanical advantage ratio. When the drive element increases its diameter, the system provides higher torque multiplication, enabling the compact motor to deliver sufficient torque for aircraft wheel drive
2Adaptability or versatility
If additional rotating components are added for autonomous taxiing, then drive capability is provided, but reliability decreases due to additional failure modes
Solution Approach 1:
The friction drive components are selectively disengaged from the wheel when not in use. The idler elements can be positioned away from the drive element and wheel, isolating them from the wheel rotation path. This removes potential failure modes during takeoff and landing while maintaining autonomous taxi capability when engaged
Solution Approach 2:
The drive assembly transitions dynamically between engaged and disengaged states. The variable-diameter drive element and movable idler elements allow the system to adapt its configuration, being connected when taxiing is needed and disconnected otherwise, minimizing the impact on reliability
3Productivity
If the drive assembly remains engaged with the wheel, then continuous drive capability is available, but wear increases and retarding torque occurs during non-taxi operations
Solution Approach 1:
The drive assembly operates periodically, being engaged only when autonomous taxiing is required and disengaged during other operations such as takeoff, landing, and ground maneuvers. This periodic engagement minimizes wear and eliminates retarding torque during non-taxi operations while maintaining drive availability when needed
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 system effectively isolates the drive assembly from the wheel during non-use, preventing unnecessary wear and rotation, and converts high-speed/low-torque input into the necessary low-speed/high-torque output for aircraft taxiing without introducing additional failure modes.
Implementation Method 1
The idler element frictionally engages the drive element to transfer rotation of the drive element to the wheel
Data Source
AI summary
A landing gear system includes a drive shaft extending through an axle. A wheel with a drive surface is rotatably coupled to the axle. A drive assembly, which has disengaged and engaged states, includes a drive element and an idler element. The drive element, which has an engagement feature, is coupled to the drive shaft for rotation about an axis. The engagement feature has first and second diameters when the drive assembly is in the disengaged and engaged states, respectively. The idler element is frictionally engaged with the engagement feature of the drive element to transfer rotation of the drive element to the wheel when the drive assembly is in the engaged state. The idler element is disengaged from at least one of the engagement feature of drive element and the wheel when the drive assembly is in the disengaged state.