Dual Bypass Filter Cascade for Gas Turbine Lubrication

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Solution Overview

Problem

Gas turbine engine lubrication systems face challenges in maintaining debris-free oil or lubricant supply due to clogging of fine and coarse mesh filters at low temperatures, which can lead to increased viscosity and blocked flow, necessitating a solution to ensure continuous lubricant delivery to bearing and gear systems.

Innovation Solution

A dual-filter system with fine and coarse mesh filters, where bypass valves activate when threshold pressures are reached, diverting the lubricant flow through bypass conduits to ensure uninterrupted supply to the engine components, utilizing a first bias mechanism for the fine filter and a second bias mechanism for the coarse filter, with the coarse filter bypass threshold pressure being greater than the fine filter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fine mesh filters are used to filter debris from lubricant, then lubricant purity is improved, but filter clogging occurs at low temperatures causing flow blockage

Engineering Contradiction:

Improvelubricant filtration effectivenessVSAvoidlubricant flow continuity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The filtration system is segmented into two independent filter stages: a coarse mesh filter (first filter) and a fine mesh filter (second filter). Each filter handles different particle sizes and has its own bypass valve, allowing selective bypassing based on which filter becomes blocked. This segmentation resolves the contradiction by enabling the system to maintain lubricant purity through the fine filter while ensuring flow continuity by bypassing only the blocked filter stage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Bypass valves act as intermediary components between the filter stages and the lubricant flow path. When a filter becomes blocked, the corresponding bypass valve opens to provide an alternative flow path around that specific filter, maintaining overall system functionality. This intermediary mechanism resolves the contradiction by allowing the system to switch between filtered and unfiltered flow paths based on filter condition.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If dual filter system with bypass valves is implemented, then lubricant flow continuity is improved, but device complexity increases

Engineering Contradiction:

Improvelubricant flow continuityVSAvoidfiltration system structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The fine mesh filter is nested within the coarse mesh filter structure, with the fine filter positioned inside the volume defined by the coarse filter. This nested arrangement consolidates two filter systems into a single integrated housing, reducing overall structural complexity while maintaining the dual-stage filtration functionality and associated bypass mechanisms.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The bypass conduits for both filters are merged into a common outlet path that combines flows from both filter stages and bypass paths. This merging of flow paths simplifies the overall system architecture by reducing the number of separate outlet connections and control mechanisms needed, while still maintaining flow continuity through either filter or bypass path.

Inventive Principle:

Principle #5Merging (Combining)

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

Ensures continuous and reliable lubricant filtration and delivery to gas turbine engine components by bypassing blocked filters, maintaining engine performance even at low temperatures, and preventing damage from debris accumulation.

Implementation Method 1

a fine mesh filter (224) disposed inside a chamber (202)... a coarse mesh filter (226) surrounding the fine mesh filter

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Implementation Method 2

a first bypass valve (240) responsive to a fine filter pressure... a second bypass valve (250) responsive to a coarse filter pressure

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentEP3786420B1Dual bypass filter cascade

Publication Date: 2023.06.14 RTX CORP

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Figure 2A
Figure 2B

AI summary

A filtration system (200) is disclosed. In various embodiments, the filtration system includes a fine mesh filter (224) configured for disposition within a chamber (202) and defining a first volume (228), the first volume in fluid communication with a main exit conduit (218); and a coarse mesh filter (226) configured for disposition within the chamber and at least partially surrounding the fine mesh filter, the coarse mesh filter and the fine mesh filter defining a second volume (230), the second volume in fluid communication with a first bypass valve (240), the coarse mesh filter and the chamber defining a third volume (232), the third volume in fluid communication with a second bypass valve (250).