EV Power Unit Suspension Layout for Balanced Inertia and Compact Packaging

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Solution Overview

Problem

Existing suspension structures for electric vehicle power units face challenges in balancing the power unit, requiring large space and leading to vibration, noise, and reduced durability due to unbalanced inertia axes and torque steer, especially when a differential gear is positioned off-center.

Innovation Solution

The power unit is suspended with the transaxle at the vehicle's center, motor on one side, and other components on the opposite side, all aligned parallel to the vehicle width axis, minimizing front-rear space and balancing inertia, with mounts and reaction force members to stabilize the unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the power unit is suspended using related-art suspension structures with the differential gear positioned off-center, then the vehicle body can be designed based on internal combustion engine vehicles, but torque steer occurs and large space is required in the vehicle front-rear direction

Engineering Contradiction:

Improvecompatibility with existing vehicle body designsVSAvoidspace required in vehicle front-rear direction

Core Design Contradiction:

Adaptability or versatilityVSLength of moving object

Solution Approach 1:

The patent positions the differential gear at the center of the vehicle width direction while arranging the motor and other components asymmetrically on the upper side. This central positioning of the differential gear eliminates torque steer while the asymmetric arrangement of other components optimizes space utilization in the front-rear direction.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent transitions from suspending components along the vehicle front-rear direction to arranging them on the upper side with the differential gear at the center. This dimensional reorganization reduces the required space in the front-rear direction while maintaining structural integrity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If the power unit is suspended with the differential gear off-center, then the vehicle body structure can be simplified, but the principal axis of inertia becomes inclined and causes unbalance in unit roll direction

Engineering Contradiction:

Improvevehicle body structure complexityVSAvoidbalance of power unit in unit roll direction

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The patent positions the differential gear at the center while arranging other components asymmetrically on the upper side. This configuration aligns the principal axis of inertia parallel to the vehicle width direction, achieving balance in the unit roll direction while maintaining structural simplicity.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent uses the asymmetric arrangement of the motor and other components on the upper side to counterbalance the central differential gear, achieving proper weight distribution and inertial balance without increasing structural complexity.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

3Volume of stationary object

If the power unit is suspended with unbalanced inertia axes, then the arrangement space can be reduced, but large vibration and noise occur and durability is reduced

Engineering Contradiction:

Improvearrangement space of power unitVSAvoidvibration and noise

Core Design Contradiction:

Volume of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent achieves proper balance by positioning the differential gear at the center and arranging other components asymmetrically on the upper side. This configuration aligns the principal axis of inertia parallel to the vehicle width direction, eliminating vibration and noise caused by unbalanced inertia while maintaining compact arrangement space.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentEP3967534B1Electrical vehicle with a power unit comprising a suspension structure

Publication Date: 2026.01.07 SUZUKI MOTOR CORP

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AI summary

Provided is a suspension structure for a power unit capable of suspending a power unit in a well-balanced manner while downsizing, in a vehicle front-rear direction, a space required for suspending the power unit. A suspension structure (10) for a power unit is configured to suspend a power unit (20) including a motor (24), a transaxle (22), and a power control unit (26) . In the suspension structure (10) for a power unit, the transaxle (22) is arranged in a substantially center portion in a vehicle width direction, the motor (24) is arranged at a position on an upper side with respect to the transaxle (22), and on one side in the vehicle width direction, and the power control unit (26) is arranged at a position on the upper side with respect to the transaxle, and on an opposite side of the motor (24). In the suspension structure (10) for a power unit, the motor (24) and the power control unit (26) are suspended on a principal axis of inertia (X) substantially parallel with an axis in the vehicle width direction.