Gearbox Sealed Vent Apparatus for Uphill Oil Management

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Solution Overview

Problem

Gas turbine engines with uphill vent configurations are at risk of alternator flooding due to oil leakage, as existing designs rely on downhill venting to prevent oil from entering internal components.

Innovation Solution

A sealed vent apparatus for the gearbox, featuring an annular first and second seal element, a vent tube, and a drain channel, which prevents oil from leaking back into the alternator by directing spent oil radially inward and ensuring effective drainage, independent of vent flow direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the vent line extends in an uphill direction, then the vent can exit the alternator in any direction including uphill, but the alternator is at risk of flooding with oil

Engineering Contradiction:

Improvevent direction flexibilityVSAvoidoil flooding risk

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

A seal assembly is introduced as an intermediary component between the drive shaft and the alternator interior. This seal assembly includes a first seal element on the drive shaft and a second seal element in the end wall that contact each other to form a sealing interface, preventing oil from the vent line from leaking into the alternator interior while allowing the vent to extend in any direction

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sealing function is segmented into two separate seal elements: a first seal element mounted to the drive shaft and a second seal element mounted to the end wall. This segmentation allows each seal element to be optimized for its specific location and function, with the first seal element preventing oil from traveling along the drive shaft and the second seal element providing additional sealing at the wall interface

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If the vent line extends in a downhill direction, then oil leakage is intrinsically limited, but the vent configuration is restricted

Engineering Contradiction:

Improveoil flooding preventionVSAvoidvent configuration flexibility

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The seal assembly acts as an intermediary that decouples the vent direction from oil leakage prevention. By placing seals at the interface between the drive shaft and alternator interior, the system no longer relies on gravitational drainage (downhill venting) to prevent oil flooding, allowing the vent to be configured in any direction including uphill

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If seal elements are added to prevent oil leakage, then alternator flooding is prevented, but device complexity increases

Engineering Contradiction:

Improveoil leakage preventionVSAvoidseal assembly complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The sealing function is divided into two separate seal elements positioned at different locations: the first seal element on the drive shaft and the second seal element in the end wall. This segmentation allows for simpler individual components that are easier to manufacture and install compared to a single complex seal, while collectively providing comprehensive oil leakage prevention

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of trying to prevent oil leakage through the vent line itself or relying on vent direction, the invention inverts the approach by placing seals at the source of potential leakage (the drive shaft interface) and using the seal wear interface to actively prevent oil from entering the alternator interior

Inventive Principle:

Principle #13The other way round (Inversion)

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 sealed vent apparatus effectively prevents alternator flooding and maintains sump pressurization system performance, allowing the overboard tube to extend in any direction, including uphill, without compromising functionality.

Implementation Method 1

an annular second seal element mounted to the case and contacting the first seal element so as to define a sealing interface

Methodology Applied

Scientific EffectSealing interface:

Implementation Method 2

the sidewall of the case incorporates an oil nozzle oriented to discharge oil radially inward into the interior space of the case, towards the first and second seal elements

Methodology Applied

Scientific EffectRadial discharge:

Implementation Method 3

the at least one drain channel is formed in the stator of the alternator... interconnecting the interior spaces of the case and the gearbox

Methodology Applied

Scientific EffectGravitational drainage: Gravitation

Data Source

PatentUS9890846B2Gearbox with sealed accessory vent

Publication Date: 2018.02.13 GENERAL ELECTRIC CO

AI summary

A gearbox vent apparatus includes: a gearbox; an accessory contained in a case mounted to the gearbox such than an interior space of the case communicates with an interior space of the gearbox, wherein the case includes a sidewall and an endwall, a hollow drive shaft mounted for rotation inside the case; an annular first seal element mounted to the drive shaft; an annular second seal element mounted to the case and contacting the first seal element so as to define a sealing interface; and a vent tube having a forward end coupled to the endwall in fluid communication with the drive shaft.