Gas Turbine Engine With Continuously Variable Transmission

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Solution Overview

Problem

Gas turbine aircraft engines with single spool designs have limited power variability due to a restricted range of operational speeds, making them unsuitable for varying power delivery to propulsion loads, particularly in smaller aircraft applications.

Innovation Solution

A gas turbine aircraft engine with a compressor and turbine mounted on a common shaft, equipped with a continuously variable transmission (CVT) that allows for synchronous rotation and power transmission to a propulsion load, enabling continuous variation of the propulsion load's rotational speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single spool turbine engine is used with compressor and turbine on a common shaft, then the engine structure is simple and reliable, but the power variability range is limited

Engineering Contradiction:

Improveengine reliabilityVSAvoidpower variability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

A continuously variable transmission (CVT) is introduced as an intermediary component between the single spool turbine engine and the propulsion load. The CVT decouples the direct rotational connection, allowing the propulsion load to operate at varying speeds while the engine operates within its optimal narrow speed range, thus maintaining reliability while enabling power variability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The power transmission system is segmented into two independent rotational systems: the engine spool (compressor and turbine on common shaft) and the propulsion load shaft. This segmentation allows independent speed control of each system, with the CVT mediating between them, resolving the contradiction between structural simplicity and power variability.

Inventive Principle:

Principle #1Segmentation

2Use of energy by moving object

If the operational speed range of the turbine engine is kept narrow for efficiency, then the engine operates most efficiently, but the power delivered to the propulsion load cannot be varied

Engineering Contradiction:

Improveengine efficiencyVSAvoidpower variability

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The CVT acts as a mediator that allows the propulsion load speed to vary independently from the engine speed. The engine maintains its narrow optimal operational speed range for maximum efficiency, while the CVT transforms this constant-speed output into variable-speed propulsion power, resolving the contradiction between efficiency and power variability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system introduces dynamic speed transformation through the CVT, which continuously varies the rotational speed ratio between the engine shaft and propulsion load shaft. This dynamic adjustment allows the propulsion load to operate at varying speeds while the engine remains in its optimal efficiency range.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8181442B2Gas turbine aircraft engine with power variability

Publication Date: 2012.05.22 PRATT & WHITNEY CANADA CORP

AI summary

A gas turbine aircraft engine with power variability is provided. The gas turbine aircraft engine comprises a compressor and a turbine mounted on a common shaft, and, a continuously variable transmission coupled to the shaft for transmitting power to a propulsion load.