Speed Summing Gearbox for Turbine Engine Power Extraction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Modern airplane engines face inefficiencies in power extraction due to the high speed disparity between low and high pressure spools, necessitating specialized generators and increasing costs for electric power generation and accessory power.

Innovation Solution

A speed summing gearbox interconnects low and high pressure spools, allowing the low spool to drive a generator and increase its rotational speed, enabling the same part to be used for both spools and facilitating engine starting through a low pressure generator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If power is extracted from the high pressure spool to drive a generator, then electric power can be generated, but the efficiency drops to an unacceptable level when significant electric power is needed

Engineering Contradiction:

Improveelectric power generation efficiencyVSAvoidhigh pressure spool efficiency

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The patent combines the high pressure spool and low pressure spool through a speed summing gearbox to drive a single generator. This merging allows both spools to contribute power to the same generator, increasing overall power extraction efficiency while maintaining acceptable efficiency levels for both spools.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The generator is designed to be driven by both the high pressure spool and low pressure spool through the speed summing gearbox, making it a universal power source that can accept input from multiple spools with different speed ranges, thereby optimizing power extraction across the entire operating envelope.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Power

If power is extracted from the low pressure spool to meet electric power demand, then sufficient electric power can be generated, but generators must be specially designed for the wider speed range

Engineering Contradiction:

Improveelectric power outputVSAvoidgenerator design complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The speed summing gearbox acts as an intermediary between the low pressure spool and the generator, converting the wide speed range of the low pressure spool into a more manageable speed range for the generator. This mediator device allows the generator to operate within optimal speed parameters while still extracting power from the low pressure spool's wider speed range.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The speed summing gearbox transforms the speed parameter from the low pressure spool before it reaches the generator, converting a wide speed range input into a narrower, more suitable speed range for the generator, thereby simplifying generator design requirements.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If a speed summing gearbox is used to interconnect low and high pressure spools, then power extraction efficiency improves and the same generator can serve both spools, but the gearbox adds device complexity

Engineering Contradiction:

Improvepower extraction efficiencyVSAvoidgearbox structure

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The speed summing gearbox is designed to handle multiple functions: it combines power from both spools, adjusts speed ranges, and enables a single generator to serve both high and low pressure spools. This multi-functionality justifies the added complexity by eliminating the need for separate generators and improving overall system efficiency.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Adaptability or versatility

If the low pressure generator is used to start the engine, then starting capability is achieved, but the speed disparity between spools must be managed

Engineering Contradiction:

Improveengine starting capabilityVSAvoidspool speed disparity

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The speed summing gearbox serves as a mediator that enables the low pressure generator to function as a starter motor by managing the speed disparity between the low pressure spool and the high pressure spool during engine starting operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system allows the low pressure generator to operate in reverse mode as a starter motor, inverting its normal generation function. The speed summing gearbox facilitates this inversion by properly matching speeds between the low pressure spool and high pressure spool during the starting process.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS7882691B2High to low pressure spool summing gearbox for accessory power extraction and electric start

Publication Date: 2011.02.08 HAMILTON SUNDSTRAND CORP

AI summary

A turbine engine includes low and high pressure spools. A high power take-off shaft is coupled to the high spool. An auxiliary component, such as a generator, is configured to be driven by the high power take-off shaft at a first speed. The low spool, in part, drives the auxiliary component, for example, by interconnecting the high power take-off shaft to a lower power take-off shaft through a speed summing gearbox. The gearbox drives the auxiliary component and increases the rotational speed of the auxiliary component from the first speed to the second speed. The low power take-off shaft also drives another generator, in one example. The turbine engine can be started by the low pressure generator, for example, in response to a command from a controller, which transforms the generator into a starter motor.