Axial Drive Unit Cooling Layout for Compact Motor-Gear Packaging

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Solution Overview

Problem

Conventional driving devices have a large size due to the coolant flow path extending from the motor casing to the reduction gear part, which increases the overall dimensions.

Innovation Solution

The driving device is configured with a motor unit, gear unit, and electric unit arranged along an axial direction, with a cooling unit positioned between them, featuring overlapping parts and direct contact between units to minimize size, and utilizing a first and second flow path for heat mediums to cool the motor and electric components respectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the flow path extends from the motor casing to the reduction gear part, then the cooling function is achieved, but the size of the driving device becomes large

Engineering Contradiction:
Improvecooling functionVSAvoidsize of driving device
Core Design Contradiction:
TemperatureVSVolume of moving object

Solution Approach 1:

The patent merges the motor unit, gear unit, electric unit, and cooling unit into a compact integrated assembly where components are positioned adjacent to each other along the axial direction. The cooling unit is strategically positioned between the motor unit and electric unit, allowing shared cooling pathways and reducing overall device volume while maintaining effective cooling of all heat-generating components.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent transitions from a radial or lateral flow path configuration to an axial direction arrangement. By positioning units along the axial direction parallel to the motor rotation axis and utilizing overlapping configurations, the design exploits the axial dimension to reduce the radial footprint and overall device size while maintaining cooling effectiveness.

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

2Volume of moving object

If units are arranged along the axial direction with overlapping configuration, then the device size is reduced, but the structural complexity increases

Engineering Contradiction:
Improvedevice sizeVSAvoidstructural complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The patent divides the driving device into distinct functional units (motor unit, gear unit, electric unit, cooling unit) that can be independently designed and manufactured. These segmented units are then positioned adjacent to each other along the axial direction with overlapping configurations, reducing overall size while maintaining manufacturing simplicity through modular assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cooling unit serves multiple functions by being positioned between the motor unit and electric unit, providing cooling pathways for both components. This multi-functional positioning reduces the need for separate cooling systems for each unit, simplifying the overall structure while achieving compact dimensions.

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

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 reduces the overall size of the driving device, allowing for a more compact design and increased space in the vehicle compartment, while improving cooling efficiency and simplifying the cooling unit structure.

Implementation Method 1

The motor unit is configured to be cooled by a first heat medium

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a first flow path for supplying the first heat medium to the motor unit

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

The electric unit is configured to be cooled by a second heat medium

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

a second flow path for supplying the second heat medium to the electric unit

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP4633012A1Drive device
Publication Date: 2025.10.15 TOYOTA JIDOSHA KK
  • EP4633012A1 patent drawingFigure 1
  • EP4633012A1 patent drawingFigure 2
  • EP4633012A1 patent drawingFigure 3

AI summary

A motor unit incorporates a motor and is cooled by a first heat medium. A gear unit incorporates a gear mechanism mechanically connected to the motor. An electric unit incorporates a high-voltage component electrically connected to the motor, and is cooled by a second heat medium. A cooling unit includes a first flow path supplying the first heat medium to the motor unit, and a second flow path supplying the second heat medium to the electric unit. The respective units are arranged along an axial direction parallel to a rotation axis of the motor. When viewed along the axial direction, at least a part of the motor unit, at least a part of the gear unit, at least a part of the electric unit, and at least a part of the cooling unit overlap one another. The cooling unit is positioned between the motor unit and the electric unit.