Aircraft Propulsion Gear Assembly for Selective Rotor Power Split

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Solution Overview

Problem

Existing aircraft propulsion systems face challenges in efficiently distributing power between different rotors to achieve both horizontal propulsion and vertical lift capabilities, particularly in transitioning between flight modes.

Innovation Solution

Aircraft propulsion system assemblies with gear systems, lock devices, and brakes that allow selective locking and unlocking of carrier and ring gear rotations, enabling mode-specific power distribution to rotors for horizontal and vertical propulsion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If power is distributed to both rotors simultaneously, then both horizontal and vertical propulsion are achieved, but power availability for each direction is reduced

Engineering Contradiction:
Improvepropulsion mode flexibilityVSAvoidpower availability per rotor
Core Design Contradiction:
Adaptability or versatilityVSPower

Solution Approach 1:

The patent implements dynamic power distribution through a gear system with selectable engagement states. The gear mechanism allows the system to transition between different power distribution modes: (1) both rotors receiving power for combined horizontal and vertical propulsion, (2) only the first rotor receiving power for horizontal propulsion, and (3) only the second rotor receiving power for vertical propulsion. This dynamic reconfiguration of the power transmission path enables full power availability to the active rotor(s) while maintaining operational flexibility across different flight modes.

Inventive Principle:
Principle #15Dynamics

2Power

If one rotor is stopped to enhance power for the other rotor, then power availability is improved, but rotor lubrication and damage prevention become problematic

Engineering Contradiction:
Improvepower availability to active rotorVSAvoid rotor protection during idle
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent introduces an intermediary mechanism in the form of a gear system that decouples the power transmission path from the rotors. When one rotor needs to remain stationary for protection while the other receives full power, the gear mechanism acts as an intermediary that allows the active rotor to receive complete power while the idle rotor remains disengaged. The gear system's selectable engagement states enable this selective power routing, and the mechanical design inherently protects idle rotors from damage by preventing power transmission to them during single-rotor operation modes.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If a complex gear system is added for selective power distribution, then power distribution flexibility is improved, but device complexity increases

Engineering Contradiction:
Improvepower distribution controlVSAvoidgear system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the power transmission system into distinct, modular components: a first gear system for controlling power to the first rotor, a second gear system for controlling power to the second rotor, and a carrier connecting them. Each gear system can be independently engaged or disengaged, allowing selective power distribution. This segmentation enables complex power distribution control through relatively simple, modular gear mechanisms rather than a single complex system, making the overall device more manageable and maintainable.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4715178A2Selective power distribution for an aircraft propulsion system
Publication Date: 2026.03.25 RTX CORP
  • EP4715178A2 patent drawingFigure 1
  • EP4715178A2 patent drawingFigure 2
  • EP4715178A2 patent drawingFigure 3A

AI summary

An assembly is provided for an aircraft propulsion system. This assembly includes a carrier (90), a first gear system (86), a second gear system (88) and a lock device (106). The first gear system (88) includes a sun gear (92), a first ring gear (94) and a plurality of first intermediate gears (96) between and meshed with the sun gear (92) and the first ring gear (94). Each of the first intermediate gears (96) is rotatably mounted to the carrier (90). The second gear system (88) includes a second ring gear (102) and a plurality of second intermediate gears (104) meshed with the second ring gear (102). Each of the second intermediate gears (104) is rotatably mounted to the carrier (90). The lock device (106) is configured to lock rotation of the carrier (90) about an axis (28) during a first mode. The lock device (106) is configured to unlock rotation of the carrier (90) about the axis (28) during a second mode.