Vehicle Drive Unit Cooling Layout for Low-Speed High-Torque Heat Control

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Solution Overview

Problem

The existing drive device for vehicles lacks effective cooling optimization, leading to increased heat transfer from the motor to the power conversion unit during low-speed and high-torque conditions, which shortens the lifespan of electronic components due to excessive heat load.

Innovation Solution

A drive device configuration with a casing having separate chambers for the motor and power conversion unit, featuring a cooling system that adjusts the supply of a thermal transfer medium to the partition wall cooling route based on vehicle speed and torque, optimizing cooling performance by prioritizing cooling to critical components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the motor and power conversion unit are housed in the same casing with a partition wall, then the device structure is compact and integrated, but heat transfer from the motor to the power conversion unit increases during low-speed and high-torque conditions

Engineering Contradiction:
Improvedevice integrationVSAvoidheat transfer
Core Design Contradiction:
Volume of moving objectVSTemperature

Solution Approach 1:

The patent introduces a partition wall with cooling fins as an intermediary structure between the motor and power conversion unit. The fins act as a thermal interface that facilitates controlled heat transfer from the motor to the power conversion unit, which serves as a heat sink, thereby managing thermal loads while maintaining device integration.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent dynamically adjusts the cooling system parameters by varying the flow rate of the cooling medium through the partition wall cooling fins based on operating conditions (vehicle speed and torque). During low-speed high-torque conditions, increased cooling medium flow rate is supplied to enhance heat dissipation from the partition wall, preventing excessive heat transfer to the power conversion unit.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If cooling depends on wind from traveling, then the cooling system is simple and passive, but cooling effectiveness is insufficient during low-speed driving conditions

Engineering Contradiction:
Improvecooling system structureVSAvoidcooling effectiveness
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The patent utilizes the vehicle's own motion to drive the cooling system. The rotation of the wheels during vehicle travel drives the cooling medium circulation through the partition wall cooling fins, converting mechanical energy from vehicle motion into cooling effectiveness without requiring an additional active cooling mechanism.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The cooling system is designed to be dynamically responsive to vehicle operating conditions. The cooling medium flow rate through the partition wall automatically varies with vehicle speed and torque demands, ensuring adequate cooling during low-speed high-torque conditions while maintaining simplicity of the overall system structure.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If the partition wall is used for structural separation, then the device layout is simple, but heat dissipation from the motor is insufficient during high-torque conditions

Engineering Contradiction:
Improvepartition wall structureVSAvoidheat dissipation
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The partition wall is designed to serve multiple functions simultaneously: it provides structural separation between the motor and power conversion unit, acts as a heat transfer interface through integrated cooling fins, and serves as a flow guide for the cooling medium. This multi-functionality eliminates the need for separate cooling structures, maintaining structural simplicity while enhancing heat dissipation capability during high-torque conditions.

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

The solution effectively suppresses heat transfer and thermal load on the power conversion unit, improving the lifespan of electronic components and overall cooling efficiency by dynamically adjusting cooling resources based on vehicle speed and torque conditions.

Implementation Method 1

a cooling system that circulates a thermal transfer medium to at least one of the first chamber and the second chamber... the partition wall can be cooled. The amount of heat transferred from the motor to the power conversion unit can be suppressed

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP4480727A1Drive device for a vehicle
Publication Date: 2024.12.25 TOYOTA JIDOSHA KK
  • EP4480727A1 patent drawingFigure 1
  • EP4480727A1 patent drawingFigure 2~3
  • EP4480727A1 patent drawingFigure 4

AI summary

A device (1) includes: a motor (40); a gear unit (50); a power conversion unit (21); a casing (10) that includes a first chamber (11) and a second chamber (12) separated from each other by a partition wall; and a cooling system (60) that circulates a thermal transfer medium to at least one of the first chamber (11) and the second chamber (12), wherein the cooling system (60) includes a partition wall cooling route (62) that supplies the thermal transfer medium to the partition wall, and is configured such that a supply amount of the thermal transfer medium to the partition wall cooling route (62) is greater in a state in which vehicle speed of the vehicle is low and output torque of the motor (40) is high, as compared to a state in which the vehicle speed is high and the output torque is low.