Dual-Spool Accessory Gearboxes With Interlink for Load Isolation

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Solution Overview

Problem

Dual spool turbine engines face challenges with large accessory gearboxes that compromise fan blade-off case load management, maintainability, and gearbox strength, particularly in electric and hybrid electric applications.

Innovation Solution

The implementation of two separate gearboxes, one for the high spool and one for the low spool, with optimized spur gear spacing and positional arrangements, allowing for modular assembly and independent oil and coolant systems, enhancing maintenance and reducing mass and case punch loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single large accessory gearbox is used to accommodate dual mechanical off takes, then all accessories can be integrated into one unit, but the gearbox mass and case punch loads increase, compromising fan blade-off case load management and gearbox strength

Engineering Contradiction:

Improveaccessory integrationVSAvoidgearbox strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The single large accessory gearbox is divided into two separate gearboxes: a high spool gearbox and a low spool gearbox. This segmentation reduces the mass and case punch loads on each individual gearbox, thereby improving fan blade-off case load management while maintaining the capability to accommodate all necessary accessories through the distributed configuration

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If a single large accessory gearbox is used, then accessories are integrated into one unit, but maintainability deteriorates due to increased complexity and size

Engineering Contradiction:

Improveaccessory integrationVSAvoidmaintainability

Core Design Contradiction:

Adaptability or versatilityVSEase of repair

Solution Approach 1:

By segmenting the accessory gearbox system into two smaller, independent gearboxes (high spool and low spool), each unit becomes simpler to maintain and repair. The reduced complexity and size of individual gearboxes improve accessibility for maintenance activities while maintaining full accessory functionality across the distributed system

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The low spool gearbox is extracted as a separate, independently maintainable unit from the traditional single gearbox configuration. This extraction allows the low spool gearbox to be removed and serviced independently without affecting the high spool gearbox, significantly improving maintainability

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If a single large accessory gearbox is used, then dual mechanical off takes are accommodated, but the gearbox mass increases, affecting overall system mass

Engineering Contradiction:

Improvedual mechanical off takes accommodationVSAvoidgearbox mass

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The accessory gearbox system is segmented into two separate units that share the load of accommodating dual mechanical off takes. This segmentation reduces the mass of each individual gearbox compared to a single large gearbox, thereby reducing overall system mass while maintaining the capability to accommodate both high and low spool mechanical off takes

Inventive Principle:

Principle #1Segmentation

4Adaptability or versatility

If a single large accessory gearbox is used, then all accessories are in one unit, but system reliability is reduced due to single point of failure

Engineering Contradiction:

Improveaccessory integrationVSAvoidsystem reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The accessory system is segmented into two independent gearbox units with separate oil and coolant systems. This segmentation creates operational independence between the high spool and low spool systems, eliminating single points of failure and improving overall system reliability, as a failure in one gearbox does not necessarily compromise the other

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The low spool gearbox and its associated oil and coolant systems are extracted as independent units from the traditional integrated gearbox design. This extraction creates physical and functional independence between the high and low spool systems, allowing one system to continue operating even if the other fails, thereby improving reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentEP4682363A1Gearbox arrangement for dual spool engine accessories

Publication Date: 2026.01.21 RTX CORP

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AI summary

A system (100; 200; 300) includes a turbine engine (110; 310), a low spool gearbox (130; 230; 330), a high spool gearbox (120; 320), and an interlink (328) mechanically coupling the low spool gearbox (130; 230; 330) to the high spool gearbox (120; 320). The turbine engine (110; 310) includes a low-pressure spool and a high-pressure spool. The low spool gearbox (130; 230; 330) is disposed within a core compartment (115) of the turbine engine (110; 310). The low spool gearbox (130; 230; 330) is configured to transfer mechanical power between the low-pressure spool and a first accessory. The high spool gearbox (120; 320) is disposed within the core compartment (115) of the turbine engine (110; 310). The high spool gearbox (120; 320) is configured to transfer mechanical power between the high-pressure spool and a second accessory.