Aircraft Engine Gearbox With Selectable Direct and Speed-Change Drive
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Solution Overview
Problem
Gas turbine engines face inefficiencies in power transmission due to fixed gear ratios that may not be optimal for all flight conditions, limiting adaptability and performance.
Innovation Solution
A gearbox system with a gear assembly, brake, and blocking member that allows for selective configuration between direct drive and speed change modes, enabling adjustable rotational speed ratios between input and output shafts through planet gears and a carrier, facilitating optimal power transmission based on flight conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed gear ratio is used in the gearbox, then the structure is simple and reliable, but the adaptability to different flight conditions deteriorates
Solution Approach 1:
The patent applies the dynamics principle by making the gearbox configuration changeable between direct drive and speed change modes. The brake and blocking member enable dynamic reconfiguration of the planetary gear system, allowing the gearbox to adapt its transmission ratio based on flight conditions while maintaining structural reliability through well-defined mechanical states.
2Adaptability or versatility
If a variable gear ratio system is implemented, then the adaptability to different flight conditions is improved, but the device complexity increases
Solution Approach 1:
The patent applies the universality principle by designing a planetary gear system that can perform multiple functions: direct drive mode for high efficiency and speed change mode for optimized torque/speed ratios. The same planetary gears, carrier, and housing structure serve both functions, reducing overall system complexity compared to having separate gearboxes for each mode.
Solution Approach 2:
The patent uses the brake and blocking member as intermediary elements that control the engagement state of the planetary gears. These intermediaries enable smooth transitions between direct drive and speed change modes by selectively restraining or allowing planet gear rotation, simplifying the control mechanism while achieving variable ratio functionality.
3Speed
If the brake impedes rotation of the intermediate component, then speed change ratio is achieved, but the direct drive capability is lost
Solution Approach 1:
The patent applies the dynamics principle by making the brake's engagement state changeable. The brake can be selectively activated to impede carrier rotation for speed change, or released to allow free rotation for direct drive mode. This dynamic control of the brake's restraining action enables the system to switch between different operational modes, achieving both speed variation and drive flexibility.
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
Enables flexible power transmission by allowing the gearbox to switch between direct drive and speed change configurations, optimizing rotational speed ratios to enhance engine performance across various flight conditions, thereby improving efficiency and adaptability.
Implementation Method 1
a brake configured to selectively impede rotation of the intermediate component
Implementation Method 2
a blocking member configured to selectively impede rotation of the planet gears about the central axes
Implementation Method 3
first and second gears in driving engagement through planet gears
Data Source
AI summary
A gearbox for an aircraft engine including first and second gears in driving engagement through planet gears supported by a carrier. Selective application of a brake and a blocking member permit operation in a speed change configuration and a direct drive configuration.