Localized Gear Oil Heating for Torque Transmission Loss Reduction

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Solution Overview

Problem

Existing torque transmission devices in motor vehicles experience significant friction and splashing losses due to the interaction between lubricating oil and gear wheels, which are not efficiently addressed by current heating methods that aim to warm the entire oil sump rather than targeting the specific areas of contact.

Innovation Solution

The integration of surface heaters directly into the oil flow on gear wheels, allowing heat generated to be carried by the forced flow of meshing gears, thereby reducing friction and splashing losses without the need for a pump, and using components with good thermal conductivity for even heat distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If heating elements are arranged around transmission shafts to heat the entire oil sump, then the transmission oil is heated to reduce friction and splashing losses, but the heating is inefficient and energy-consuming because it heats the entire oil volume rather than targeting the specific oil flow areas

Engineering Contradiction:
Improveenergy consumption for heatingVSAvoidheating efficiency
Core Design Contradiction:
Loss of energyVSProductivity

Solution Approach 1:

The heating elements are positioned to heat only the specific local areas where oil flows over the gear wheels, rather than heating the entire oil sump. This localized heating approach reduces energy consumption while maintaining effectiveness in reducing friction and splashing losses.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The heating elements are arranged in a specific spatial configuration that targets the oil flow paths directly, changing from a volumetric heating approach (heating the entire sump) to a targeted surface heating approach along the gear wheel peripheries where oil naturally flows.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Loss of energy

If the entire oil sump is heated, then friction and splashing losses are reduced, but the thermal efficiency is low because the heated oil has a relatively large volume compared to the actual oiling flow area

Engineering Contradiction:
Improvefriction and splashing lossesVSAvoidthermal efficiency
Core Design Contradiction:
Loss of energyVSUse of energy by moving object

Solution Approach 1:

Heating is applied specifically to the oil flow paths along the gear wheel peripheries, targeting only the oil that actually contacts the gears. This eliminates waste of thermal energy on heating large volumes of oil that do not participate in lubrication, thereby improving thermal efficiency while still reducing friction and splashing losses.

Inventive Principle:
Principle #3Local quality

3Temperature

If heating elements are placed in the oil sump, then the transmission oil temperature increases, but the heating is not rapid enough because the heat must diffuse through the entire oil volume

Engineering Contradiction:
Improvetransmission oil temperatureVSAvoidheating speed
Core Design Contradiction:
TemperatureVSSpeed

Solution Approach 1:

The heating elements are positioned to heat the oil along the gear wheel peripheries where oil naturally flows, creating a concentrated heating zone rather than attempting to heat the entire sump volume. This approach rapidly increases the temperature of the actual oiling flow, achieving faster heating speeds.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

4Reliability

If conventional heating devices are used to heat the entire oil sump, then the transmission oil is warmed to improve lubrication, but the construction is complex and the energy consumption is high

Engineering Contradiction:
Improvelubrication qualityVSAvoidheating system construction
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The heating system uses simple heating elements positioned to target only the critical oil flow paths, eliminating the need for complex heating systems that would be required to heat the entire sump uniformly. This localized approach maintains reliable lubrication while simplifying the overall device construction.

Inventive Principle:
Principle #3Local quality

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 effectively and rapidly reduces friction and splashing losses by heating the oil flow directly on the transmission elements, improving thermal efficiency and reducing energy consumption compared to prior art methods.

Implementation Method 1

due to the onset of forced flow of the meshing gears in the oil, the heat generated by the heating elements is carried along

Methodology Applied
Scientific EffectForced Convection: Forced Convection

Implementation Method 2

the heat generated by the heating elements is carried along. No pump is required for heat transport. Furthermore, the actual area of the oiling flow, which is responsible for the splashing losses, can be heated in a targeted, highly efficient and fast manner

Methodology Applied
Scientific EffectConduction (thermal): Conduction (thermal)

Implementation Method 3

Due to the thermal increase in the oil in the area of the gear wheel, splashing losses are reduced. This means that the thin, low-viscosity oil is now also carried in a targeted manner via the teeth on the gear wheel connections

Methodology Applied
Scientific EffectViscosimetry:

Data Source

PatentEP3172462B1Device for conditioning the lubricating oil of a torque transmission device
Publication Date: 2020.09.23 AUDI AG
  • EP3172462B1 patent drawingFigure 1
  • EP3172462B1 patent drawingFigure 2
  • EP3172462B1 patent drawingFigure 3

AI summary

The invention relates to a device for conditioning the lubricating oil of a torque transmission device for motor vehicles, in particular for gear trains, in which device the lubricating oil is heated, at least temporarily, in its cold state by means of heating elements, in order to reduce friction losses and/or churning losses in the torque-transmitting gear-train elements. To achieve an improved reduction in the losses in the cold-operation range, according to the invention, at least one heating element (26; 28; 46) is arranged directly in the lubricating flow of the gear-train elements (16; 50).