Ring Gear Alignment Control for Reduction Gearbox Misalignment

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Solution Overview

Problem

Gearboxes in aircraft engines, particularly reduction gearboxes, add weight and complexity, and misalignment issues can lead to gear tooth wear and bearing stress, affecting efficiency and specific fuel consumption.

Innovation Solution

A ring gear positional alignment system with a system controller, actuator, and sensor is used to adjust the position of ring gears within the reduction gearbox, mitigating misalignment by rotating the first ring gear relative to the second ring gear based on sensor feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a reduction gearbox is used to reduce turbine rotational speed and increase torque, then the propeller can be driven at appropriate speed, but the gearbox adds weight and complexity to the engine

Engineering Contradiction:

Improvepropeller rotational speedVSAvoidgearbox structure complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent makes the ring gear position adjustable rather than fixed, allowing dynamic adaptation to manufacturing tolerances and operational conditions. The ring gear can be rotated to different angular positions using actuators, enabling the system to optimize its performance and reduce misalignment effects during operation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements a feedback control system using sensors to detect ring gear misalignment and a controller to actuate the positioning mechanism. This closed-loop system continuously monitors and corrects ring gear position, reducing gear tooth wear and improving efficiency by compensating for misalignment in real-time.

Inventive Principle:

Principle #23Feedback

2Productivity

If ring gears are manufactured and assembled, then the gearbox can operate, but manufacturing tolerances cause misalignment between ring gears leading to gear tooth wear and bearing stress

Engineering Contradiction:

Improvegearbox operational capabilityVSAvoidring gear alignment precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent performs preliminary positioning of the ring gear during assembly or before operation begins. The system determines the optimal angular position of the ring gear to minimize misalignment effects, and pre-positions it accordingly using the actuator mechanism, preventing wear issues before they occur during normal operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the angular position parameter of the ring gear to optimize alignment. By rotating the ring gear to a specific angle that compensates for manufacturing tolerances in the planet gears and other components, the system achieves better meshing conditions and reduces stress on gear teeth and bearings.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If misalignment between ring gears occurs, then the gearbox can still function, but gear tooth wear and bearing stress increase affecting efficiency and fuel consumption

Engineering Contradiction:

Improvegearbox functional operationVSAvoidspecific fuel consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent converts the harmful effect of manufacturing tolerances and misalignment into a benefit by using sensors to detect the misalignment condition and actuators to actively compensate for it. The system transforms the potential harm of fixed misalignment into an opportunity for dynamic correction, improving efficiency and reducing energy losses.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentEP4579105A1Method and system for mitigating ring gear misalignment within a reduction gearbox

Publication Date: 2025.07.02 PRATT & WHITNEY CANADA CORP

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AI summary

A reduction gearbox is provided that includes a sun gear (46), planet gear assemblies (48), first and second ring gears (50B), and a ring gear positional alignment system (92). Each planet gear assembly (48) includes a main gear and first and second lateral gears coupled to one another. The ring gear positional alignment system includes a system controller (94), a ring gear actuator (96), and a sensor (98). The ring gear actuator (96) is engaged with the first ring gear (50B) and is configured to rotate the first ring gear (50B) relative to the second ring gear. The system controller (94) is in communication with the sensor (98), the ring gear actuator (96), and a non-transitory memory storing instructions. The instructions when executed cause the system controller (94) to receive and process signals from the sensor (98) relating to the position of the first ring gear (50B), and control the ring gear actuator (96) to selectively position the first ring gear (50B) using the signals from the sensor (98).