Aircraft Gearbox Lubrication Layout for Cooler Failure Isolation
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Solution Overview
Problem
Rotary aircraft gearboxes face lubricant loss issues, leading to potential failure and loss of momentum or lift, which can result in unplanned landings, as existing lubrication systems lack effective fault detection and adaptive distribution mechanisms.
Innovation Solution
A lubrication system comprising multiple gearboxes and lubricant coolers connected by fluid passages, with a fault isolating hydraulic control system and electronic controller that adjusts flow paths and rates to maintain lubrication in case of component failure or abnormal operating conditions, ensuring continued flight operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single lubricant cooler and single fluid passage system is used, then the system is simpler and lighter, but the gearbox is vulnerable to lubricant loss and failure when the cooler or passage malfunctions
Solution Approach 1:
The lubrication system is divided into two independent lubricant coolers (first and second coolers) with separate fluid passages for each gearbox. This segmentation ensures that if one cooler or its associated passages fail, the other cooler can continue to provide lubrication, thereby improving reliability without requiring a completely redundant system for both gearboxes.
Solution Approach 2:
Each gearbox is equipped with its own dedicated lubricant cooler and fluid passages, creating localized lubrication systems. The first gearbox has a first cooler with first passages, while the second gearbox has a second cooler with second passages. This local quality approach isolates failures to specific regions, preventing system-wide lubrication failure.
2Duration of action of moving object
If auxiliary reservoirs and additional equipment are added to ensure continued flight operations during lubricant loss, then the aircraft can maintain flight longer, but the aircraft weight increases
Solution Approach 1:
The system incorporates dynamic flow control capabilities through the fluid passages that can redirect lubricant flow based on system conditions. When one cooler becomes inoperative, the system can dynamically reroute lubricant through alternative passages to extend operational time without requiring additional reservoirs, thereby avoiding the weight penalty of auxiliary equipment.
Solution Approach 2:
Each lubricant cooler is designed to be able to serve both of its associated gearboxes. The first cooler can lubricate the first gearbox through first passages or the second gearbox through second passages, and vice versa. This multi-functionality allows the system to extend operational duration during failures without adding dedicated backup reservoirs, as the existing coolers can be repurposed.
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 manages lubricant distribution and flow to prevent gearbox failure, allowing the aircraft to maintain flight even in scenarios of lubricant loss, thereby reducing the risk of unplanned landings and extending operational time without additional weight from auxiliary reservoirs or equipment.
Implementation Method 1
a first lubricant cooler positioned external the first and second internal cavities, the first lubricant cooler configured to hold lubricant, a second lubricant cooler positioned external the first and second internal cavities, the second lubricant cooler configured to hold lubricant
Implementation Method 2
a plurality of fluid passages fluidly connecting the first lubricant cooler and second lubricant coolers to each of the first gearbox and the second gearbox
Implementation Method 3
the gearbox will include a lubrication system that distributes a lubricant onto various components. Loss of lubricant could result in a failure of the gearbox
Data Source
Figure 1
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Figure 2B
AI summary
A lubricant system includes a first gearbox defining a first internal cavity, a second gearbox defining a second internal cavity, a first lubricant cooler positioned external the first and second internal cavities, a second lubricant cooler positioned external the first and second internal cavities, and a plurality of fluid passages fluidly connecting the first lubricant cooler and second lubricant coolers to each of the first gearbox and the second gearbox. The first lubricant cooler and the second lubricant cooler are configured to hold lubricant. The fluid passages include a first main fluid passage fluidly connecting the first lubricant cooler to the first gearbox, a second main fluid passage fluidly connecting the second lubricant cooler to the second gearbox, a first auxiliary passage fluidly connecting the first lubricant cooler to the second gearbox, and a second auxiliary passage fluidly connecting the second lubricant cooler to the first gearbox.