EV Battery Pack Bracket Layout for Retreating Subframe Loads
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Solution Overview
Problem
In electric vehicles with a battery pack disposed under the floor, the rear end of the subframe can retreat during a frontal collision, potentially interfering with the battery pack, and existing measures to prevent this are limited in effectively distributing and managing the load to protect the battery.
Innovation Solution
A vehicle design where the load from the front subframe is distributed to the front side frames and the large-sized bottom wall of the battery pack, using a system of bolts and brackets that transmit the load to the battery pack's bottom wall, including a buckling portion to absorb and manage loads, and a rib to enhance structural strength, ensuring the battery is protected from the retreating subframe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the rear end of the subframe is allowed to retreat during frontal collision, then the battery pack can be avoided from direct impact, but the subframe may interfere with the battery pack and compromise battery protection
Solution Approach 1:
A load transmission structure comprising brackets and bolts is introduced as an intermediary between the subframe and battery pack. The brackets are attached to both the subframe and battery pack, with bolts securing the brackets to the battery pack. This intermediary structure transmits the retreating load from the subframe to the battery pack in a controlled manner, allowing the subframe to retreat while maintaining reliable connection and protecting the battery from uncontrolled interference.
2Object-affected harmful factors
If the subframe is prevented from retreating by rigid fastening, then battery protection is improved, but the collision load cannot be effectively distributed and may cause structural damage
Solution Approach 1:
The load transmission system is segmented into multiple components: brackets attached to the subframe, bolts securing the brackets to the battery pack, and the battery pack bottom wall itself. This segmentation allows the collision load to be distributed across multiple attachment points and structural elements, preventing concentration of stress at a single point while maintaining overall structural integrity and battery protection.
Solution Approach 2:
The battery pack bottom wall is designed with specific local structural characteristics to handle the transmitted loads. The bottom wall serves as a load-bearing surface that receives and distributes forces from the bracket-bolt attachments. This local structural optimization ensures that the bottom wall can effectively transmit collision loads to the battery pack structure without compromising overall strength.
3Object-affected harmful factors
If a complex fastening system is used to securely attach the subframe to the battery pack, then protection is improved, but device complexity increases
Solution Approach 1:
The brackets serve multiple functions simultaneously: they attach the subframe to the battery pack, transmit collision loads from the subframe to the battery pack, and maintain the proper spatial relationship between the subframe and battery pack during normal operation and collision events. This multi-functionality reduces the need for separate dedicated components for each function, simplifying the overall system while maintaining effective protection.
Data Source
AI summary
A vehicle includes: a front side frame; a front subframe; a first fixing portion fixing the front subframe and the front side frame with a first bolt; a battery pack; a first bracket coupling the battery pack and the front side frame; a second fixing portion fixing the first bracket to the front side frame with a second bolt; and a third fixing portion fixing the first bracket to the battery pack with a third bolt, wherein the battery pack includes: a bottom wall, and a front wall, the second fixing portion is provided with a contact surface at a position facing the first fixing portion, the third fixing portion is provided at a front end of the bottom wall of the battery pack, and the first bracket includes a first load transmitting portion that is fixed to the second fixing portion and the third fixing portion.