Vehicle Inverter Cover Cooling Layout for Compact Drive Units

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Solution Overview

Problem

Existing vehicle drive devices face challenges in achieving compactness and efficient cooling of inverters due to surplus space and inadequate cooling performance, particularly with components like capacitors and semiconductor modules generating heat.

Innovation Solution

The inverter components are suspended on a cover with a integrated cooling unit, utilizing a coolant flow to enhance cooling efficiency and compact mounting, with the coolant paths designed to avoid interference with surrounding components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the inverter is installed on a partitioning wall with conventional layout, then the inverter can be mounted, but surplus space remains above the inverter and the height dimension expands due to overlayed components

Engineering Contradiction:
Improveinverter mounting space utilizationVSAvoidinverter component arrangement complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The patent transitions from a conventional planar layout to a three-dimensional suspended arrangement. The capacitor and semiconductor module are suspended from the cover in the vertical dimension, allowing efficient use of available space without expanding the inverter's footprint or height. This dimensional change resolves the contradiction by utilizing vertical space effectively while maintaining a compact overall structure.

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

Solution Approach 2:

The cover serves multiple functions: it encloses the inverter components and simultaneously serves as the mounting structure for suspending the capacitor and semiconductor module. The cooling unit is integrated with the cover, combining cooling functionality with the structural enclosure. This merging of functions reduces the number of separate components and simplifies the overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

2Volume of moving object

If capacitor and semiconductor module are overlayed in the up-down direction, then space is utilized, but the height dimension of the inverter expands

Engineering Contradiction:
Improveinverter component space utilizationVSAvoidinverter height dimension
Core Design Contradiction:
Volume of moving objectVSLength of stationary object

Solution Approach 1:

Instead of overlaying components in the up-down direction which increases height, the patent suspends them from the cover using vertical spacing. The capacitor and semiconductor module are positioned at different vertical levels but attached to the same horizontal plane (the cover), utilizing the vertical dimension for spacing rather than stacking. This approach maintains compact height while effectively using available volume.

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

3Temperature

If cooling unit is integrated with cover and positioned apart from motor unit, then cooling performance is enhanced through air-cooling effect, but device complexity increases

Engineering Contradiction:
Improveinverter component cooling performanceVSAvoidcooling unit integration complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The cooling unit is integrated with the cover, combining the cooling function with the structural enclosure. The cover serves as both the protective enclosure and the mounting structure for the cooling unit, eliminating the need for separate cooling housings or mounting brackets. This integration reduces device complexity while achieving enhanced cooling performance through the air-cooling effect from the separated positioning.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cover acts as an intermediary structure that houses the cooling unit and provides thermal management for the inverter components. By positioning the cooling unit on the cover rather than directly integrating it with the motor unit, the cover mediates the thermal management function while maintaining structural integrity and enabling air-cooling effects.

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 configuration allows for a compact inverter arrangement with enhanced cooling performance, reducing the overall size and ensuring effective temperature management of the inverter components.

Implementation Method 1

the components of the inverter can be cooled by a coolant flowing through a cooling unit integrated with a cover

Methodology Applied
Scientific EffectCooling: Cooling

Implementation Method 2

the cooling unit is apart from a motor unit which generates heat, the cooling unit is not heated by heat from the motor unit and also the air-cooling effect can be expected, therefore cooling performance can be enhanced

Methodology Applied
Scientific EffectAir-cooling effect: Convection

Data Source

PatentEP4412074B1Vehicle drive device
Publication Date: 2026.01.21 MITSUBISHI MOTORS CORP
  • EP4412074B1 patent drawingFigure 1
  • EP4412074B1 patent drawingFigure 2
  • EP4412074B1 patent drawingFigure 3

AI summary

A vehicle drive device (10) includes: a motor unit (1) that includes a motor for driving mounted on a vehicle and a gear mechanism that transmits torque of the motor to each of left and right wheels of the vehicle; and an inverter (4) that is arranged over the motor unit (1) and that includes a capacitor (5) smoothing electricity and a semiconductor module (6) including a plurality of switching elements, wherein the inverter (4) includes a tray unit (16) that accommodates the capacitor (5) and the semiconductor module (6), and a cover (15) that is in a flat-plate shape, is attached to the tray unit (16), and covers the capacitor (5) and the semiconductor module (6) from above the capacitor (5) and the semiconductor module (6), the cover(15) is integrated with a cooling unit (20) through which a coolant for cooling the inverter (4) flows, and the capacitor (5) and the semiconductor module (6) are attached to a lower surface (17) of the cover (15).