Double Subframes with Isolation Couplings for EV NVH
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Solution Overview
Problem
Electric vehicles produce high-frequency vibrations that negatively impact noise, vibration, and harshness (NVH) characteristics, requiring redesign of vehicle subsystems to maintain crash safety and modularity while accommodating electric powertrains and batteries.
Innovation Solution
A double subframe system with an inner subframe coupled to the powertrain via isolation couplings and an outer subframe coupled to the vehicle frame, where the outer subframe partially surrounds the inner subframe and is also connected to the vehicle frame via isolation couplings, effectively damping vibrations and improving NVH characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If electric powertrain is directly coupled to the vehicle frame, then structural simplicity is maintained, but high-frequency vibrations negatively impact NVH characteristics
Solution Approach 1:
The subframe is divided into an inner subframe and an outer subframe as separate components. The inner subframe is coupled to the powertrain while the outer subframe is coupled to the vehicle frame, allowing each component to be optimized independently for its specific function while managing vibrations through the isolation couplings between them.
Solution Approach 2:
Isolation couplings are introduced as intermediary elements between the inner subframe and the outer subframe. These couplings act as mediators that dampen high-frequency vibrations transmitted from the powertrain to the vehicle frame, reducing NVH impacts while maintaining structural connectivity.
2Object-affected harmful factors
If isolation couplings are added between subframes, then vibrations are damped, but device complexity increases
Solution Approach 1:
The isolation couplings serve multiple functions simultaneously: they mechanically connect the inner and outer subframes, dampen high-frequency vibrations, and maintain structural integrity. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in overall device complexity while achieving vibration damping.
3Object-affected harmful factors
If double subframe structure is used, then NVH characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The double subframe structure is segmented into modular inner and outer subframes that can be manufactured separately using standard fabrication processes. This segmentation allows each subframe to be optimized for its specific manufacturing requirements and assembled together with isolation couplings, simplifying the overall manufacturing process compared to creating a single complex integrated structure.
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 double subframe system significantly reduces vibrations from the electric powertrain, enhancing the NVH performance of electric vehicles by isolating the powertrain's vibrations from the vehicle frame, thus improving the overall driving experience.
Implementation Method 1
the first coupling to damp vibrations of the powertrain transmitted to the frame via the second subframe
Data Source
AI summary
Double subframes with isolation couplings are disclosed herein. An example vehicle disclosed herein includes a powertrain, a frame, a first subframe coupled to the powertrain via a first isolation coupling, and a second subframe coupled at least partially around the first subframe, the second subframe coupled to the frame.