Gearbox Oil Cooling Assembly with Direct-Drive Impeller

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Solution Overview

Problem

Rotary-wing aircraft gearboxes face challenges in compactly packaging heat dissipating components while maintaining efficiency and reliability, as existing solutions often lead to elevated gearbox temperatures and increased complexity due to internal exhaust air and shaft-driven power systems.

Innovation Solution

A gearbox oil cooling assembly with a concentrically positioned heat exchanger, impeller, and exhaust duct, axially stacked about a drive shaft, which routes oil through internal tubes and uses airflow to cool the oil, eliminating the need for belts and pulleys, and expelling heated air externally.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If external oil hoses are used to transfer hot and cooled oil between gearbox and heat exchanger, then oil cooling function is achieved, but system complexity and potential reliability issues increase

Engineering Contradiction:
Improvegearbox oil temperatureVSAvoidsystem complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent integrates the oil cooling function directly into the gearbox housing by incorporating the heat exchanger and oil passages within the housing structure itself, eliminating the need for external oil hoses and separate cooling components. This merging of functions reduces system complexity while maintaining effective oil cooling.

Inventive Principle:
Principle #5Merging (Combining)

2Speed

If shaft-driven power through belts and pulleys is used to rotate impeller, then impeller rotation is achieved, but device complexity increases

Engineering Contradiction:
Improveimpeller rotation speedVSAvoiddevice complexity
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the intermediate belt and pulley components from the power transmission system. Instead of using shaft-driven power through belts and pulleys, the impeller is directly coupled to the turbine output drive shaft, simplifying the device while maintaining impeller rotation capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The impeller is directly coupled to the turbine output drive shaft, merging the power transmission function directly into the impeller assembly. This direct coupling eliminates the need for separate belts and pulleys, reducing device complexity while achieving the required impeller rotation.

Inventive Principle:
Principle #5Merging (Combining)

3Object-generated harmful factors

If heated exhaust air is exhausted internally in vicinity of gearbox, then exhaust disposal is achieved, but gearbox operates at elevated temperature

Engineering Contradiction:
Improveheated exhaust airVSAvoidgearbox operating temperature
Core Design Contradiction:
Object-generated harmful factorsVSTemperature

Solution Approach 1:

The patent extracts the heat exchanger and exhaust duct system from the internal gearbox environment and positions it externally. The heat exchanger is mounted on the gearbox exterior with exhaust ducts directing heated air away from the gearbox, thereby disposing of harmful heat without elevating gearbox operating temperature.

Inventive Principle:
Principle #2Taking out (Extraction)

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

This configuration enables efficient oil cooling in a compact space, reducing gearbox temperature and complexity, enhancing reliability by direct-drive impeller rotation and short, internal oil transfer tubes, while expelling heated air externally to minimize re-heating.

Implementation Method 1

a heat exchanger to receive and cool an oil from the gearbox

Methodology Applied
Scientific EffectHeat transfer: Heat Exchanger

Implementation Method 2

an airflow is facilitated with the impeller and used to cool the heat exchanger

Methodology Applied
Scientific EffectForced convection: Forced Convection

Data Source

PatentEP3194791B1Gearbox oil cooling assembly
Publication Date: 2020.01.08 SIKORSKY AIRCRAFT CORP
  • EP3194791B1 patent drawingFigure 1
  • EP3194791B1 patent drawingFigure 2
  • EP3194791B1 patent drawingFigure 3

AI summary

A gearbox oil cooling assembly for a gearbox driving a drive shaft having a drive shaft coupling. The assembly includes a heat exchanger to receive and cool an oil from the gearbox and having an inlet. Also included is an impeller axially disposed between the heat exchanger and the drive shaft coupling, wherein the impeller is operatively coupled to, and rotated by, the drive shaft operatively coupled to the drive shaft coupling. Further included is an exhaust duct operatively coupled to the heat exchanger and disposed radially outwardly around the impeller and defining an airflow pathway through which air passes through the inlet, the impeller and through the exhaust duct according to the rotation of the impeller to cool the oil in the heat exchanger.