Turbomachine Speed Reducer Scoops for Low-Speed Lubrication
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Solution Overview
Problem
Current speed reducers for turbomachines, particularly in aircraft, face challenges with lubrication at low-speed operations, such as during WindMilling, standstill, or start-up, where existing solutions like lubricant recovery devices are either ineffective or require complex and bulky mounting.
Innovation Solution
A lubricant recovery device with pivotable scoops integrated on the annular ring gear, which deploys at low speeds to collect and redistribute lubricant within the speed reducer, eliminating the need for additional pumps or generators, and retracts at high speeds to avoid interference with lubricant circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lubricant recovery device with fixed scoops is used, then high-speed lubrication is effective, but low-speed lubrication fails and the device is bulky
Solution Approach 1:
The scoop is designed to be movable rather than fixed, capable of pivoting between a retracted position and a deployed position. This dynamic configuration allows the recovery device to adapt its structure based on operating conditions, achieving both compactness at high speeds and effective lubrication at low speeds without requiring a bulky fixed structure
Solution Approach 2:
The device changes its operational parameters based on rotor speed. At high speeds, the scoop remains retracted to avoid interference with centrifugal lubricant circulation. At low speeds, the scoop deploys to actively recover and redistribute lubricant, thereby changing the system's behavior to match the operating conditions and maintain reliable lubrication across the full speed range
2Reliability
If auxiliary lubrication pumps are added, then low-speed lubrication is improved, but the mounting becomes complicated and bulky
Solution Approach 1:
The movable scoop enables the system to be self-sufficient across all operating conditions. By utilizing the existing centrifugal force mechanism and adding only a simple movable recovery element, the system automatically adapts to provide auxiliary lubrication at low speeds without requiring external pumps, generators, or complicated mounting infrastructure
Solution Approach 2:
The solution extracts only the essential function needed for low-speed lubrication from the complex pump system - the lubricant recovery and redistribution function - and implements it through a simple movable scoop that leverages the existing centrifugal circulation mechanism, thereby achieving the desired reliability without the mounting complexity of full pump systems
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
This solution provides effective lubrication during low-speed operations, simplifies the mounting and operation of the speed reducer, and adapts to various turbomachine conditions without cluttering, ensuring optimal lubrication and service life.
Implementation Method 1
a recovering pipe of lubricant discharged by centrifugation from the reducer
Data Source
AI summary
A speed reducer, particularly of an aircraft, includes a central sun gear mounted to rotate with a drive shaft about a rotation axis X, an annular ring gear coaxial with the X axis, and a plurality of planet gears arranged about the X axis and mounted to be movable on a planet carrier. The planet gears engages the sun gear and the annular ring gear, which extends around the planet gears. The speed reducer further includes a lubricant recovery device having a pipe for recovering lubricant discharged from the reducer by centrifuging. The recovery device has scoops mounted to pivot about a pivot axis P on a movable member of the speed reducer that rotates about the X axis between a deployed state and a rest state.