Solid Lubricant-Carrying Gear for Oil-Out Gearbox Lubrication
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Solution Overview
Problem
Conventional secondary lubrication systems in rotorcraft gearboxes are prone to failures and operator errors, and they require redundant systems to maintain lubrication during primary lubricant flow cessation, which is not always reliable.
Innovation Solution
A solid lubricant-carrying gear with a gear body and a solid lubricant body that melts at a temperature above the liquid lubricant, providing secondary lubrication via lubricant directing features, allowing the gearbox to operate without primary lubricant flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional secondary lubrication system with sensors and operator intervention is used, then lubrication can be provided during primary lubricant flow cessation, but the system is prone to failures and operator errors
Solution Approach 1:
The gear itself carries and provides secondary lubrication through integrated solid lubricant elements, eliminating the need for separate sensor-based control systems and operator intervention. The solid lubricant is automatically released when primary lubrication fails, making the system self-activating and more reliable.
Solution Approach 2:
The secondary lubrication function is merged directly into the gear structure by integrating solid lubricant elements within the gear body, combining the gear's mechanical function with its lubrication provision function, thereby reducing system complexity and eliminating separate control mechanisms.
2Reliability
If solid lubricant body melts at temperature above liquid lubricant, then secondary lubrication is provided when primary lubricant flow ceases, but the gear temperature must reach high levels to activate
Solution Approach 1:
The solid lubricant is designed to undergo a phase transition from solid to liquid at a specific melting point that is above the liquid lubricant's temperature. This phase change automatically activates secondary lubrication when the gear temperature rises due to friction or loss of primary lubrication, providing a reliable fail-safe mechanism.
Solution Approach 2:
The melting point of the solid lubricant is specifically selected to be higher than the operating temperature of the liquid lubricant, creating a temperature-based parameter change that triggers secondary lubrication activation only when needed, i.e., when primary lubrication fails and temperature rises.
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 solid lubricant-carrying gear system provides continuous lubrication to gear teeth, reducing the risk of mechanical failure and extending operational time during oil-out events without relying on sensors or operator intervention.
Implementation Method 1
a solid lubricant body that melts at a temperature above that of the liquid lubricant to provide second lubrication to the gear teeth
Data Source
AI summary
A solid lubricant-carrying gear which is lubricated by a liquid lubricant communicated to the gear by a primary lubrication system includes a gear body and a solid lubricant body. The gear body is arranged along a rotation axis and has a first surface, an axially opposite second surface, and an outward radial face extending about the rotation axis having gear teeth and lubricant directing features. The solid lubricant body is coupled to the gear body and includes a lubricant which melts at a melting temperature above that of the liquid lubricant to provide secondary lubrication to the gear via the lubricant directing features. Gearboxes, aircraft having transmissions employing solid lubricant-carrying gears, and methods of lubricating gears are also described.