Gearwheel Cooling Layout Using Radial Inward Fluid Delivery

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Solution Overview

Problem

In electrically operated vehicles, the high rotational speeds of gearwheels in transmissions lead to inefficiencies in lubrication and cooling, as the cooling fluid is often thrown outward, preventing effective cooling of the gearwheels.

Innovation Solution

The cooling fluid is provided to the gear teeth from a radially inward position, utilizing centrifugal forces to press the fluid toward the inwardly facing surfaces during rotation, ensuring efficient cooling, especially at high speeds, through methods like spraying or dripping onto the radially inwardly facing surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If cooling fluid is provided from a radially outside position (cooling fluid bath or sump), then cooling is effective at low rotational speeds, but at high rotational speeds the cooling fluid is thrown outward and cooling efficiency deteriorates

Engineering Contradiction:
Improvegearwheel cooling efficiencyVSAvoidgearwheel rotational speed
Core Design Contradiction:
TemperatureVSSpeed

Solution Approach 1:

The patent inverts the conventional cooling fluid delivery approach by providing cooling fluid from a radially inside position rather than from outside. This inversion allows centrifugal force to press the cooling fluid outward toward the radially inwardly facing surfaces of the gear teeth, ensuring effective cooling even at high rotational speeds where conventional outward delivery would fail.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the delivery position parameter of the cooling fluid from radially outside to radially inside. This parameter change fundamentally alters how centrifugal force acts on the cooling fluid, transforming it from a harmful effect that throws fluid outward to a useful effect that presses fluid toward the gear tooth surfaces for effective cooling.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If cooling fluid is provided from above (dripping or spraying), then lubrication is simple and efficient, but cooling effectiveness deteriorates at high rotational speeds due to fluid being thrown outward

Engineering Contradiction:
Improvecooling system simplicityVSAvoidgearwheel cooling efficiency
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

Instead of providing cooling fluid from above or from outside, the patent inverts the delivery approach by providing fluid from radially inside positions. This inversion ensures that centrifugal force works in favor of delivering cooling fluid to the gear tooth surfaces rather than throwing it outward, maintaining cooling effectiveness at high speeds while preserving structural simplicity.

Inventive Principle:
Principle #13The other way round (Inversion)

3Productivity

If gearwheels rotate at high speeds (as in electrically operated vehicles), then propulsion efficiency is improved, but cooling and lubrication effectiveness deteriorates due to cooling fluid being thrown outward

Engineering Contradiction:
Improvevehicle propulsion efficiencyVSAvoidgearwheel cooling efficiency
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The patent changes the delivery position parameter of cooling fluid from conventional outside/above positions to radially inside positions. This parameter change enables the system to accommodate high rotational speeds characteristic of electrically operated vehicles by utilizing centrifugal force to press cooling fluid toward the gear tooth surfaces rather than allowing it to be thrown outward.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent inverts the conventional cooling fluid delivery direction by providing fluid from radially inside positions rather than from outside. This inversion transforms centrifugal force from a harmful effect at high speeds to a beneficial mechanism that ensures cooling fluid reaches the gear tooth surfaces, enabling effective cooling in high-speed electric vehicle applications.

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

This approach ensures effective cooling of gear teeth during meshing engagement, even at high rotational speeds, by directing the cooling fluid radially inwardly, where it is needed, thereby enhancing the cooling efficiency of the gearwheels.

Implementation Method 1

the cooling fluid is provided radially inside of the meshing gear teeth and is therefore pressed/forced toward the radially inwardly facing surface by centrifugal forces as the gearwheel rotates

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP3974682B1A gearwheel arrangement
Publication Date: 2024.06.26 VOLVO TRUCK CORP
  • EP3974682B1 patent drawingFigure 1~2
  • EP3974682B1 patent drawingFigure 3~4

AI summary

A gearwheel arrangement (1) for a transmission of a vehicle, comprising: - a gearwheel (2) configured to be rotatable about an axis of rotation (A), the gearwheel comprising a gearwheel body (3) and an annular gear tooth section (4) extending around the gearwheel body, the gear tooth section comprising a plurality of external gear teeth, wherein at least a part of the gear tooth section extends past a radially outer portion of the gearwheel body in an axial direction (A) of the gearwheel, so that at least one radially inwardly facing surface (5a, 5b) is provided opposite of the external gear teeth, - means for guiding cooling fluid toward the at least one radially inwardly facing surface so as to cool the gear tooth section during rotation of the gearwheel about the axis of rotation.