Accessory Gearbox Traction Drive for Variable Turbine Shaft Speeds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas turbine engine accessory drive systems face inefficiencies due to fixed gear ratios, which limit the ability to vary rotational speeds of accessory components relative to the turbine shafts, leading to suboptimal operation and increased fuel consumption.
Innovation Solution
A multispeed traction drive transmission system that includes a continuously variable transmission, allowing the output shaft to rotate within a defined range and varying its speed relative to the first towershaft, coupled with a second towershaft rotating at a higher speed, to efficiently drive accessory components like electric machines and hydraulic pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed gear ratios are used in the accessory drive system, then the structure is simple, but the rotational speed of accessory components cannot be varied relative to the turbine shafts, leading to suboptimal operation
Solution Approach 1:
The patent applies a multispeed transmission system that dynamically changes gear ratios between the turbine shafts and accessory components. This allows the rotational speed of accessories to be varied relative to the turbine shafts, resolving the contradiction between adaptability and complexity by introducing controlled dynamic adjustment capability.
Solution Approach 2:
The transmission system changes the gear ratio parameter between different operating conditions. By varying the gear ratio, the system optimizes the rotational speed match between turbine shafts and accessory components, improving operational efficiency while managing system complexity through parameter adjustment.
2Productivity
If accessory components operate at varying rotational speeds, then operational efficiency improves, but fuel consumption and engine gas temperature increase
Solution Approach 1:
The transmission system maintains continuous optimal speed matching between turbine shafts and accessory components throughout operation. By ensuring continuous useful action at optimized ratios, the system improves accessory efficiency without excessive energy loss, as the transmission is designed to minimize power losses while providing speed variation.
3Device complexity
If a single towershaft is used to drive all accessory components, then the device complexity is reduced, but the ability to optimize rotational speeds for different accessories is limited
Solution Approach 1:
The patent segments the drive system into multiple towershafts, each capable of independent speed control and optimized for specific accessory components. This segmentation allows different accessories to operate at their optimal speeds while managing overall system complexity through modular architecture.
Solution Approach 2:
The transmission system provides multi-functionality by enabling a single gearbox to serve multiple accessory components with different speed requirements. Through the multispeed transmission, one gearbox can optimize speeds for various accessories, reducing the need for separate gearboxes while maintaining speed optimization capability.
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 solution enables efficient operation of accessory components within a narrower range of rotational speeds, reducing idle thrust, engine gas temperature, and mission fuel burn, while ensuring adequate lubrication and maintaining performance across varying operational conditions.
Implementation Method 1
A gas turbine engine assembly includes a multispeed transmission coupled to a first turbine shaft of a gas turbine engine. The gas turbine engine assembly includes a first towershaft rotatably coupled to the first turbine shaft. The accessory drive gearbox includes a housing in which the first set of gears and a second set of gears are arranged.
Data Source
Figure 1~2
Figure 3
AI summary
A gas turbine engine assembly includes, among other things, a turbine section having first and second turbines mounted for rotation about a common rotational axis (X) within an engine static structure, first and second turbine shafts (40, 50) coaxial with one another and to which the first and second turbines are respectively operatively mounted, an accessory drive gearbox (60) a first towershaft (68; 70) interconnecting the accessory drive gearbox (60) and the first or second turbine shaft (40; 50), and a multispeed transmission interconnecting the accessory drive gearbox (60) and at least one accessory component.