Dual-Spool Differential Gear Assembly for Accessory Speed Conditioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft engine manufacturers face challenges in extracting accessory power from the low pressure spool due to differences in optimum speed ratios between accessories and the low pressure spool, leading to high torque at low speeds, which complicates the design of conventional multi-speed or variable-speed transmissions.
Innovation Solution
A turbomachine dual spool differential gear assembly that combines low pressure spool and high pressure spool inputs to produce a reduced output speed range, utilizing a ring gear, sun gear, and planetary gears to achieve a 3.6:1 output speed range, reducing torque and simplifying transmission design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power is extracted from the low pressure spool to meet accessory power requirements, then accessory power needs are satisfied, but the wide speed range of the low pressure spool creates high torque at low speed and requires complex speed conditioning
Solution Approach 1:
The patent combines the low pressure spool and high pressure spool into a single dual-spool transmission system. The high pressure spool is integrated with the low pressure spool through a common transmission path, allowing power from both spools to contribute to accessory drive. This merging eliminates the need for separate transmission systems for each spool and reduces overall complexity while maintaining the ability to meet accessory power requirements across the full operating range.
Solution Approach 2:
The dual-spool transmission system serves multiple functions: it conditions speed for accessories, manages torque across the wide low pressure spool range, and enables power extraction from both spools. The single transmission system handles both speed conditioning and torque management tasks that would otherwise require separate systems, reducing complexity while maintaining versatility.
2Speed
If a multi-speed or variable-speed transmission is used to condition the low pressure spool output speed, then accessory speed requirements are met, but the transmission size increases due to high torque at low speed
Solution Approach 1:
By merging the high pressure spool power path with the low pressure spool transmission system, the patent creates a combined power source that reduces the torque burden on the transmission at any given moment. The high pressure spool contributes power during low speed conditions, effectively sharing the torque load and allowing for a more compact transmission design that still meets accessory speed requirements.
Solution Approach 2:
The system changes the effective torque parameter by introducing high pressure spool power contribution. This parameter change allows the transmission to operate with reduced torque demands across the speed range, enabling a more compact design. The high pressure spool power effectively modifies the torque profile that the transmission must handle.
3Adaptability or versatility
If the low pressure spool operates at wide speed range, then engine operating flexibility is maintained, but torque conditioning becomes more difficult with very high torque at low speed
Solution Approach 1:
The patent merges the high pressure spool power contribution with the low pressure spool operation. This combination allows the system to maintain the wide operating range of the low pressure spool while using high pressure spool power to offset and reduce the torque demands at low speed conditions, making torque conditioning more manageable across the full operating range.
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 solution reduces the output speed range by 50% and torque by 38% at minimum speed, improving engine efficiency, stability, and reducing brake wear, while allowing for more efficient high pressure spool operation and lower idle speed.
Implementation Method 1
a plurality of planetary gears disposed between the sun gear and the ring gear and meshed with the sun gear and the ring gear. The planetary gears can be rotationally connected to a carrier.
Data Source
AI summary
A turbomachine 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 spool speed range alone. The gear assembly can include a ring gear, a sun gear, and a plurality of planetary gears disposed between the sun gear and the ring gear and meshed with the sun gear and the ring gear. The planetary gears can be rotationally connected to a carrier.