Dual Spool Differential Transmission for Accessory Speed Conditioning
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Solution Overview
Problem
Aircraft engine manufacturers face challenges in extracting accessory power from the low pressure spool due to the wide speed range and high torque at low speeds, which requires complex and large multi-speed or variable-speed transmissions to condition the output speed, limiting the efficiency and simplicity of the transmission systems.
Innovation Solution
A turbomachine dual spool transmission system with a dual spool differential and a transmission assembly that combines low and high pressure spool inputs into a combination output, providing a reduced speed range by selectively switching between two gear ratios, using a gear assembly with a ring gear, sun gear, and planetary gears, and a rotating clutch to manage the output speed and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-speed or variable-speed transmission is used to condition the low pressure spool output speed, then the accessory speed range can be maintained, but the transmission size and complexity increase due to high torque at low speed
Solution Approach 1:
The patent combines the low pressure spool and high pressure spool into a single dual spool differential system that outputs a merged speed range. This integration allows the system to leverage both spools' capabilities while avoiding the need for complex multi-speed transmissions, thereby reducing transmission complexity while maintaining accessory speed adaptability
Solution Approach 2:
The patent changes the operating parameters by using the high pressure spool to supplement the low pressure spool output. This parameter change enables the system to operate at higher speeds where torque requirements are reduced, allowing for a simpler transmission design while still meeting accessory speed requirements
2Power
If power is extracted from the low pressure spool, then accessory power can be obtained, but the wide speed range and high torque at low speed require complex transmissions
Solution Approach 1:
The patent merges power extraction from both the low pressure spool and high pressure spool through a dual spool differential system. This combination allows power to be extracted while maintaining a narrower, more manageable output speed range that reduces transmission complexity
Solution Approach 2:
The dual spool differential acts as an intermediary device between the two spools and the transmission system. It conditions the combined power output to produce a narrower speed range that is more suitable for driving accessories, thereby reducing the complexity of the downstream transmission
3Volume of moving object
If the low pressure spool speed range is reduced by combining with high pressure spool, then transmission size can be reduced, but the system complexity increases
Solution Approach 1:
The patent combines the low pressure spool and high pressure spool systems into an integrated dual spool differential arrangement. This merger achieves the dual benefit of reducing the output speed range (thereby reducing transmission size) while managing the added complexity through a unified system architecture that shares common components
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 system reduces the output speed range and torque, enabling the use of a simpler, smaller transmission that improves engine efficiency, reduces brake wear, and allows for more efficient power extraction from both spools, making it suitable for driving aircraft engine accessories with reduced complexity and size.
Implementation Method 1
a plurality of transmission planetary gears disposed between the transmission sun gear and the transmission ring gear and meshed with the transmission sun gear and the transmission ring gear
Data Source
AI summary
A turbomachine dual spool transmission system can include a transmission assembly configured to connect to a combination output of a dual spool differential at a transmission input to be driven by the combination output to turn a transmission output. The transmission assembly can be configured to provide a first output gear ratio in a first state and a second output gear ratio in a second state. The system can include the dual spool differential. The dual spool differential can include a gear assembly configured to combine a low pressure spool input and a high pressure spool input into a combination output to provide an output speed range smaller than a low pressure speed range alone.