Dual-Direction Windmill Pump for Reverse-Rotation Lubrication

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Solution Overview

Problem

Gas turbine engine lubrication systems face challenges in ensuring consistent lubricant supply to geared architectures during both normal operation and windmilling conditions, where the fan shaft reverses direction, potentially damaging the lubrication system if not properly managed.

Innovation Solution

A lubrication system with an input gear train that includes a primary and reverse gear train, utilizing a sprag clutch design for selective coupling, ensures lubricant supply to journal bearings regardless of the shaft's rotational direction, using a gear pump driven by both forward and reverse rotations to maintain lubricant flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single-direction gear pump is used, then lubrication is effective during normal forward operation, but the system fails during windmilling when the fan shaft rotates in reverse

Engineering Contradiction:

Improvelubrication reliabilityVSAvoidadaptability to rotation direction

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The gear pump is segmented into two independent single-direction gear pumps (forward pump and reverse pump), each capable of pumping lubricant in one direction. This segmentation allows each pump to be optimized for its specific rotational direction while collectively providing bidirectional lubrication capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dual-direction gear pump assembly serves multiple functions: it pumps lubricant during forward rotation via the forward pump, pumps lubricant during reverse rotation via the reverse pump, and can operate with either pump independently or both simultaneously. This multi-functionality ensures reliable lubrication regardless of rotation direction.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a dual-direction gear pump is implemented, then lubrication is maintained during both forward and reverse rotations, but the device complexity increases

Engineering Contradiction:

Improvelubrication continuityVSAvoidpump system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Two single-direction gear pumps are merged into a single dual-direction pump assembly that operates as one integrated lubrication system. The forward and reverse pumps share common lubricant supply and delivery pathways, allowing them to function independently or simultaneously while maintaining a unified system architecture.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system automatically selects which pump operates based on the rotation direction without requiring external control mechanisms. The mechanical design itself determines pump activation, eliminating the need for complex control systems, valves, or sensors to manage bidirectional operation.

Inventive Principle:

Principle #25Self-service

3Device complexity

If conventional single-direction lubrication is used, then the system is simple, but windmilling in reverse direction causes damage to the lubrication system

Engineering Contradiction:

Improvepump system simplicityVSAvoidreverse rotation damage

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The reverse rotation, which would normally be harmful to a single-direction pump, is converted into a beneficial operating condition for the reverse pump. The windmilling reverse rotation now drives the reverse pump to deliver lubricant, transforming a potentially damaging condition into a useful lubrication source.

Inventive Principle:

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

Solution Approach 2:

The system is designed with preliminary protective measures by incorporating the reverse pump that prevents damage during reverse rotation. Instead of trying to prevent reverse rotation or its effects, the design anticipates reverse operation and provides a dedicated pump to handle it, eliminating the harmful effect before it can occur.

Inventive Principle:

Principle #9Preliminary anti-action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system effectively prolongs the operational life of geared architectures by ensuring continuous lubrication during both normal operation and windmilling conditions, preventing damage from reverse rotations and maintaining optimal performance.

Implementation Method 1

sprag clutch design for selective coupling

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

using a gear pump driven by both forward and reverse rotations to maintain lubricant flow

Methodology Applied

Scientific EffectGear pumping: Pump

Data Source

PatentEP3578780B1Dual direction windmill pump for geared turbofan engines

Publication Date: 2023.08.02 RTX CORP

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AI summary

A lubrication system (200) may comprise a shaft including a shaft gear (302), a pump (202) configured to supply a flow of lubricant to a component benefiting from lubrication and an input gear train (300) coupled to the shaft gear (302) and configured to drive the gear pump (202) with a unidirectional rotation in response to a forward rotation and an reverse rotation of the shaft gear (302). The input gear train (300) may comprise a primary gear (210) coupled to a common shaft (212). The input gear train (300) may further comprise a forward shaft (218) and a forward gear (220) about the common shaft (212), wherein the forward gear (220) is coupled to the forward shaft (218).