Flange-Mounted Ring Gear Heat Dissipation
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Solution Overview
Problem
Current rotorcraft drive systems are prone to failures due to single component failures, loss of lubrication, and high-speed gearing issues, which can lead to reduced flight performance and safety concerns, necessitating improved redundancy, maintenance minimization, and lubrication management.
Innovation Solution
The design incorporates dual engine reduction gearboxes isolated from the main rotor gearbox via freewheeling clutches, separate accessory gearboxes, and a ring gear with a circumferential flange protruding into ambient air for enhanced cooling, along with compartmentalized lubrication systems and low-speed overhung planetary gears to reduce heat generation and maintain torque transmission in lubrication loss scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ring gear is enclosed within the gearbox housing, then the gearbox is protected from external contaminants, but heat accumulation occurs reducing reliability
Solution Approach 1:
The ring gear is segmented from the enclosed gearbox housing by providing it with an external mounting structure that extends outside the housing. This segmentation allows the ring gear to be thermally isolated from the enclosed gearbox environment, enabling passive cooling through ambient air while maintaining the protective enclosure for other gearbox components.
Solution Approach 2:
The ring gear is positioned in a different spatial dimension relative to the gearbox housing - specifically, it extends externally beyond the housing boundaries. This dimensional repositioning allows the ring gear to access ambient air for cooling while other gearbox components remain protected within the enclosed housing, effectively solving the heat accumulation problem without compromising protection.
2Device complexity
If single load path components are used in the drive system, then device complexity is reduced, but system reliability decreases due to single point failures
Solution Approach 1:
The drive system is segmented into multiple independent load paths, with the ring gear forming one such path that can operate independently. This segmentation creates redundancy where the ring gear can carry torque even if other gearbox components fail, thereby improving reliability without significantly increasing overall system complexity.
Solution Approach 2:
The invention changes the operational parameter of the ring gear from a purely internal gearbox component to an external mounted component with direct ambient air exposure. This parameter change enables the ring gear to function as an independent torque transmission path with passive cooling, providing redundancy and improving reliability while maintaining manageable system complexity.
3Temperature
If the ring gear is mounted externally on the housing, then heat dissipation to ambient air is improved, but protection from contaminants is reduced
Solution Approach 1:
The ring gear is segmented from the enclosed gearbox housing and mounted externally on the housing surface. This segmentation allows the ring gear to be exposed to ambient air for effective heat dissipation while the main gearbox housing remains enclosed to protect other components from contaminants. The ring gear's external mounting position enables thermal management without compromising the protective enclosure.
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 configuration enhances rotorcraft drive system survivability by minimizing single path components, maximizing redundancy, reducing maintenance needs, and ensuring continued torque transmission even in high-speed gear failures or lubrication losses, thereby improving safety and operational reliability.
Implementation Method 1
the ring gear is cooled by convection of heat away from the ring gear to the ambient air outside the ring gear
Implementation Method 2
the ring gear is cooled by conduction of heat away from the ring gear through the first housing or the second housing or a combination thereof
Data Source
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AI summary
A ring gear (428) includes a ring (504) having one or more sets of inwardly facing teeth (506), a circumferential flange (432) extending outward from the ring (504), and the flange (432) is mounted between a first housing and a second housing. In addition, the flange (432) protrudes into an ambient air outside the first housing and second housing.