Redundant Engine Reduction Gearboxes for Lubrication-Loss Torque Transfer
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Solution Overview
Problem
Current rotorcraft drive systems are prone to failures due to single component failures and loss of lubrication, leading to reduced safety and reliability, with high-speed gearing systems being particularly susceptible to torque transmission disruptions in lubrication loss scenarios.
Innovation Solution
The implementation of a redundant engine reduction gear system with self-contained, separate gearboxes connected via clutches to the main rotor gearbox, featuring a one-piece shaft with integral couplings and anti-flail protection, along with a flexible coupling and independent lubrication systems to minimize maintenance and enhance survivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If prior art gearboxes use external oil coolers and pressurized oil leak paths, then cooling capability is improved, but system complexity and potential failure points increase
Solution Approach 1:
The patent combines the oil cooler function directly into the gearbox housing structure, eliminating the need for separate external oil coolers. The housing itself serves as the cooling mechanism, reducing system complexity while maintaining thermal management capability.
Solution Approach 2:
The gearbox design uses its own operational components (housing, lubrication system) to provide cooling functionality without requiring external auxiliary systems. The pressurized oil leak paths are eliminated in favor of self-contained thermal management within the gearbox structure.
2Productivity
If high-speed gearing systems are used in rotorcraft, then power transmission efficiency is improved, but susceptibility to torque transmission disruption in loss-of-lubrication scenarios increases
Solution Approach 1:
The patent divides the drive system into separate, isolated gearbox units rather than using a single integrated high-speed gearbox. This segmentation allows one gearbox to fail without compromising the other, maintaining torque transmission capability even when one unit experiences lubrication loss or mechanical failure.
Solution Approach 2:
The redundant gearbox configuration provides a pre-established backup system that can immediately take over torque transmission if one gearbox fails. This beforehand cushioning ensures continuous operational capability without requiring complex real-time detection or switching mechanisms.
3Device complexity
If a single gearbox or shaft failure occurs, then system simplicity is maintained, but overall drive system reliability decreases
Solution Approach 1:
The drive system is segmented into multiple independent gearbox units rather than relying on a single gearbox. This segmentation creates redundancy where failure of one unit does not propagate to other units, improving overall system reliability while maintaining relatively simple individual unit designs.
Solution Approach 2:
Each gearbox unit is designed with localized independence, having its own lubrication, cooling, and structural characteristics. This local quality ensures that failures remain contained to individual units rather than affecting the entire drive system, achieving reliability improvement without requiring complex inter-unit interactions.
Data Source
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AI summary
An engine reduction gear system includes at least two self-contained, independent engine reduction gearboxes (202a, 202b), each capable of connecting to an aircraft engine. Each of the engine reduction gearboxes (202a, 202b) provides redundant, reduced speed to a main rotor gearbox (208) via a shaft (206a, 206b).