Dual Clutch Transmission for Constant-Speed Accessory Gearbox Drive
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Solution Overview
Problem
Current gas turbine engine architectures face challenges in power extraction, particularly from the low spool, which experiences wide rotational speeds, affecting accessory performance and overall engine efficiency, especially during idle conditions.
Innovation Solution
A power extraction system incorporating a low spool transmission and a dual clutch transmission coupled with a generator, along with a controller to manage gear ratios based on rotational speed, ensuring consistent power delivery and reducing idle thrust and exhaust temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power is extracted from the low spool, then the compressor operability is improved and overall engine performance is enhanced, but the wide range of rotational speeds of the low spool causes problems for accessories requiring constant speed
Solution Approach 1:
A dual clutch transmission system is introduced as an intermediary between the low spool and the generator. This transmission includes a first clutch coupling the low spool to a first transmission shaft, and a second clutch coupling the low spool to a second transmission shaft. The transmission enables speed conversion and provides a constant speed output to the generator while maintaining the variable speed input from the low spool, thus resolving the contradiction between power extraction benefits and speed consistency requirements.
Solution Approach 2:
The system changes the speed parameter from variable (low spool) to constant (generator input) through the dual clutch transmission mechanism. By using different gear ratios and clutch configurations, the transmission transforms the wide range of rotational speeds from the low spool into a narrow, constant speed range suitable for generator operation, while still allowing effective power extraction across different engine operating conditions.
2Reliability
If power is extracted from the high spool, then the low spool can maintain better operability, but excessive power extraction from the high spool reduces compressor operability particularly during idle conditions
Solution Approach 1:
The system dynamically switches between high spool and low spool power extraction based on engine operating conditions. A controller monitors engine parameters and commands clutch engagement/disengagement to select the appropriate power source. During idle conditions, the system can prioritize low spool extraction to maintain compressor operability, while during high power demand, it can utilize high spool extraction, thus dynamically optimizing the balance between power extraction and compressor performance.
3Speed
If a dual clutch transmission is used to maintain constant speed for accessories, then accessory performance is improved, but the device complexity increases
Solution Approach 1:
The transmission system is segmented into distinct functional modules: a first clutch assembly for coupling the low spool to a first transmission shaft, a second clutch assembly for coupling the low spool to a second transmission shaft, and a generator coupled to one of the shafts. This segmentation allows each component to perform its specific function independently, making the complex system more manageable, easier to maintain, and potentially more reliable despite the increased number of parts.
Data Source
AI summary
A power extraction system for a gas turbine engine may comprise a low spool transmission and a low spool accessory gearbox. The low spool accessory gearbox may comprise a generator and a dual clutch transmission. The dual clutch transmission may be coupled between the low spool transmission and the generator.