Spur Gear Cooling Layout for Low-Friction Tooth Engagement

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Solution Overview

Problem

Existing spur gear designs face inefficiencies in cooling and friction reduction, primarily relying on inner housing cooling and lacking effective lubricant and coolant management, which leads to increased friction and energy losses.

Innovation Solution

The implementation of multiple openings in the inner housing for controlled introduction and exit of lubricant and coolant, combined with cooling devices that apply lubricant or coolant directly to gear surfaces and utilize tangential nozzles for efficient flow guidance, reduces friction and enhances cooling through direct contact cooling and heat transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If cooling is achieved primarily via the inner housing, then the structure is simple, but the cooling effectiveness is insufficient

Engineering Contradiction:
Improvecooling effectivenessVSAvoidcooling system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The cooling system is segmented into multiple independent cooling devices, each with its own nozzle system positioned at different locations around the gear transmission. This allows distributed cooling coverage without requiring a completely redesigned complex system, as each segment operates independently to cool specific zones.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A coolant fluid is introduced as an intermediary medium between the heat source (gears) and the environment. The coolant carries heat away from the gear surfaces through direct contact cooling, achieving effective temperature reduction without requiring complex thermal conduction paths through the housing.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If lubricant and coolant are introduced at multiple points, then cooling and lubrication effectiveness improve, but the device complexity increases

Engineering Contradiction:
Improveenergy efficiencyVSAvoidnumber of openings and cooling devices
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The cooling devices are designed to perform multiple functions simultaneously: they introduce coolant for cooling, deliver lubricant for lubrication, and manage fluid flow through the same nozzle systems and openings. This multi-functionality reduces the need for separate dedicated systems for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The cooling and lubrication systems are merged into a integrated fluid delivery system where coolant and lubricant are introduced through the same openings and nozzle structures. This combination achieves effective cooling and lubrication without requiring completely separate independent systems.

Inventive Principle:
Principle #5Merging (Combining)

3Loss of energy

If the annular gap between inner housing and spur gears is reduced, then friction losses decrease, but cooling effectiveness is compromised

Engineering Contradiction:
Improvefriction lossesVSAvoidcooling effectiveness
Core Design Contradiction:
Loss of energyVSTemperature

Solution Approach 1:

The system uses hydraulic principles by introducing coolant fluid directly into the annular gap between the inner housing and spur gears. The fluid flow dynamics create effective cooling through direct contact with gear surfaces while the controlled gap width optimizes both friction reduction and cooling performance.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 approach results in lower internal friction, improved energy efficiency, and effective cooling of spur gears, particularly during engagement, by managing lubricant and coolant flow to minimize turbulence and optimize heat dissipation.

Implementation Method 1

the cooling devices 20 are designed to apply lubricant and/or coolant 9 through the openings 13 to the toothing 5 of at least one of the spur gears 2

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

apply lubricant and/or coolant 9 through the openings 13 to the toothing 5

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 3

excess, heated coolant can escape from the inner housing

Methodology Applied
Scientific EffectHeat transfer: Convection

Implementation Method 4

at least one cooling device 20 is designed to introduce coolant 9 into the reach 6 of the toothing 5

Methodology Applied
Scientific EffectFluid flow:

Data Source

PatentEP4488544A1Spur gear transmission with cooling device
Publication Date: 2025.01.08 VOITH PATENT GMBH
  • EP4488544A1 patent drawingFigure 1~2
  • EP4488544A1 patent drawingFigure 3~4
  • EP4488544A1 patent drawingFigure 5

AI summary

Spur gear transmission 1, comprising at least two spur gears 2 which mesh with each other via a toothing 5, comprising at least one inner housing 10 which encloses at least a part of the spur gears 2 in the circumferential direction and in the direction of the axes of rotation 7, 8 by means of a shell wall 11, wherein an annular gap 12 is formed between the inner housing 10 and the spur gears 2, wherein the inner housing 10 has at least one opening 13, the inner housing 10 encloses at least the majority of the spur gears 2, and wherein the spur gear transmission 1 comprises a wiper device 30, wherein the wiper device 30 is arranged in the direction of rotation 40 in front of the engagement 6 of the spur gears 2, and is designed to receive lubricant or coolant 9 and air from the annular gap 11 and to discharge them from the inner housing 10 through the opening 13.