Power Unit Suspension Layout for Balanced Inertia and Low Vibration
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Solution Overview
Problem
Existing suspension structures for power units in electric vehicles face challenges such as space restrictions in the vehicle front-rear direction, unbalanced inertia axes leading to vibration and noise, and potential interference during collisions, particularly due to the arrangement of differential gears and transaxles.
Innovation Solution
A suspension structure where the transaxle is centered in the vehicle width direction, with the motor and other unit-forming members arranged above it, allowing for parallel alignment with the vehicle width axis, minimizing space requirements and reducing vibration and noise, while also positioning the transaxle to minimize collision interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the differential gear is arranged at a position apart from the center portion in the vehicle width direction, then the torque steer can be eliminated, but another member such as an intermediate shaft is required
Solution Approach 1:
The patent applies asymmetry by intentionally offsetting the differential gear from the vehicle centerline toward one side. This asymmetric arrangement eliminates torque steer by aligning the differential gear axis with the steering axis, while the patent compensates for the space requirement by arranging the motor and other components on the opposite side, achieving balance without requiring an intermediate shaft
2Reliability
If the power unit is suspended from the vehicle body using related-art suspension structure, then the power unit can be supported, but a large space in the vehicle front-rear direction is required
Solution Approach 1:
The patent transitions from a conventional longitudinal suspension arrangement to a transverse suspension arrangement where the motor and other components are suspended side-by-side in the vehicle width direction rather than front-to-rear. This dimensional change in component layout significantly reduces the space required in the vehicle front-rear direction while maintaining reliable power unit support
3Reliability
If the principal axis of inertia of the power unit is inclined with respect to the vehicle width direction axis, then the power unit can be suspended, but the axis of inertia in unit roll direction cannot be balanced
Solution Approach 1:
The patent uses asymmetric arrangement of components where the motor is positioned on one side of the transaxle and other components are positioned on the opposite side. This asymmetric layout is specifically designed to align the principal axis of inertia with the vehicle width direction, achieving balance in the unit roll direction and eliminating vibration and noise
Data Source
AI summary
A suspension structure for a power unit is configured to suspend a power unit including a motor, a transaxle, and a power control unit. In the suspension structure for a power unit, the transaxle is arranged in a substantially center portion in a vehicle width direction, the motor is arranged at a position on an upper side with respect to the transaxle, and on one side in the vehicle width direction, and the power control unit is arranged at a position on the upper side with respect to the transaxle, and on an opposite side of the motor. In the suspension structure for a power unit, the motor and the power control unit are suspended on a principal axis of inertia substantially parallel with an axis in the vehicle width direction.