Transmission Housing Heating for Cold Operating Fluid Lubrication

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Solution Overview

Problem

Existing transmission systems in motor vehicles face challenges in efficiently dissipating heat without exceeding a safe heat output per unit area, which can impair the lubricating properties of the operating fluid, especially when the fluid is cold, leading to increased friction losses and wear.

Innovation Solution

The solution involves a heating element that indirectly transfers heat to the transmission housing, which then dissipates it to the operating medium through a larger coupling surface, utilizing a heat-conducting material with a higher thermal conductivity coefficient to distribute heat efficiently across the housing, thereby increasing the effective coupling surface area without the need for a large heating element.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a large heating element is used to deliver high heat output, then the heat output to the operating medium is improved, but the space required in the transmission housing increases

Engineering Contradiction:
Improveheat outputVSAvoidspace in transmission housing
Core Design Contradiction:
PowerVSVolume of stationary object

Solution Approach 1:

The housing serves as an intermediary heat transfer medium between the compact heating element and the operating medium. The heating element transfers heat to the housing through thermal conduction, and the housing distributes this heat to the operating medium through its extended coupling surface, thereby achieving high heat output with a compact heating element

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The solution transitions from direct heating (heating element directly contacting operating medium) to indirect heating through the housing, utilizing the housing's extended surface area in three-dimensional space to increase the effective heat transfer area without increasing the heating element size

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

2Productivity

If the heat output per area exceeds the predefined value, then rapid heating of the operating medium is achieved, but the lubricating properties of the operating medium are impaired

Engineering Contradiction:
Improveheating speedVSAvoidlubricating properties
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The heat transfer process is segmented into two distinct stages: first, the heating element transfers heat to the housing at high heat flux density; second, the housing distributes this heat to the operating medium at controlled heat flux density across its larger coupling surface, preventing local overheating and maintaining lubricating properties

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The housing acts as a thermal buffer and distributor, receiving concentrated heat from the heating element and redistributing it across a larger area to the operating medium, thereby controlling the heat output per unit area to preserve lubricating properties while achieving rapid overall heating

Inventive Principle:
Principle #24Intermediary (Mediator)

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 allows for a compact design that effectively manages heat dissipation, reducing friction losses and wear, while maintaining the lubricating properties of the operating fluid, and can handle higher heat outputs without exceeding safe temperature limits.

Implementation Method 1

the heating element for dissipating the thermal power to the housing by means of a first coupling surface (28)

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the housing (10) for dissipating the heat output to the equipment via a second coupling surface (29)... the housing is made from a first material with a housing part and has a heat-conducting element for distributing and/or conducting the heat output

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

a heat-conducting element for distributing and/or conducting the heat output, the heat-conducting element being formed from a second material which has a higher thermal conductivity coefficient than the first material

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

the heating element is present for dissipating the heat output to the housing (10) via a first coupling surface (28) and the housing (10) for dissipating the heat output to the equipment (11) via a second coupling surface (29)

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3519719B1Transmission with a heating element for indirectly heating an operating medium, and motor vehicle
Publication Date: 2021.08.18 AUDI AG
  • EP3519719B1 patent drawingFigure 1
  • EP3519719B1 patent drawingFigure 2
  • EP3519719B1 patent drawingFigure 3

AI summary

The invention relates to a transmission (1) for a motor vehicle, comprising a housing (10), which at least partly encloses at least one movable transmission part (30) and is filled with an operating medium (11) during a normal operation of the transmission (1), and comprising a heating element (20), which is designed to dispense a heat output in order to heat the operating medium (11). The aim of the invention is to increase a coupling surface for dispensing a heat output to the operating medium (11) in a simple manner. This is achieved in that the heating element (20) is designed to dispense the heat output to the housing (10) via a first coupling surface (28), and the housing (10) is designed to dispense the heat output to the operating medium (11) via a second coupling surface (29). In this manner, the heat output can be transmitted from the heating element (20) to the operating medium (11) in a significantly indirect manner via the housing (10).