Multispeed Spool Generator Transmission for Wide RPM Matching
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Solution Overview
Problem
Conventional turbomachines face limitations in utilizing the low pressure spool for driving accessories like generators due to its large speed range, leading to potential stall-out at low RPM and inefficient energy distribution.
Innovation Solution
A low speed spool multispeed transmission system with a gear system that includes multiple gear states and a controller, allowing the low pressure spool to drive accessories by converting input speed to a predetermined output speed range (7200 RPM to 16000 RPM) through a combination of planetary gears, band brakes, and overrunning clutches, enabling efficient operation across a wide speed range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the low pressure spool is used to drive accessories directly, then the speed range is large, but the generator may stall out at low RPM and operate inefficiently
Solution Approach 1:
The patent applies parameter changes by using a variable frequency generator whose operating parameters (frequency and voltage) can be dynamically adjusted. This allows the generator to operate efficiently across the wide speed range of the low pressure spool without stalling, as the electrical output parameters are modified to match the varying mechanical input speed.
Solution Approach 2:
The patent implements dynamics by introducing a control system that dynamically adjusts the generator's operating characteristics in real-time based on the spool speed. This dynamic control prevents stall-out conditions by ensuring the generator operates within its optimal range even as the input speed varies widely.
2Device complexity
If the high pressure spool drives all accessories, then the system is simple, but the low pressure spool capacity is underutilized and energy distribution is inefficient
Solution Approach 1:
The patent applies segmentation by dividing the accessory drive function between two spools. The low pressure spool drives the generator through a dedicated transmission system, while the high pressure spool handles other accessories. This segmentation balances the load across both spools, improving overall energy distribution efficiency.
Solution Approach 2:
The patent implements multi-functionality by enabling the low pressure spool to serve dual purposes: driving the generator and potentially driving other accessories through the transmission system. This utilizes the previously underutilized low pressure spool capacity, improving energy distribution efficiency.
3Reliability
If a transmission system is added to convert low pressure spool speed, then the generator operation is efficient, but the device complexity increases
Solution Approach 1:
The patent introduces a transmission system as an intermediary between the low pressure spool and the generator. This intermediary converts the wide speed range of the spool to the appropriate operating range for the generator, ensuring efficient operation while isolating the complexity within a dedicated subsystem.
Data Source
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AI summary
A low speed spool multispeed transmission (100) includes an input shaft (101) configured to connect to a low pressure spool gearbox, a gear system (103) connected to the input shaft (101) and configured to convert an input speed (101) of the input shaft to an output speed within a predetermined speed range, wherein the gear system (103) includes a plurality of gear states to change the ratio between the input speed and the output speed, and an output shaft (105) connected to the gear system (103) to be rotated by the gear system (103) at the output speed, the output shaft (105) configured to connect to a generator. The input shaft (101) and the output shaft (105) can be coaxial.