EV Battery Bracket Rigidity Ratio for Vibration Control
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Solution Overview
Problem
In electric motor vehicles, the vertical misalignment of the floor frame and battery unit connection points leads to difficulties in firm attachment, resulting in potential weight increase and vibration noise issues, particularly in the intermediate frequency band around 125 Hz.
Innovation Solution
The electric motor vehicle employs a rigidity ratio (Rb/Rf) of 0.1 or greater for the attachment of the battery unit to the floor frame, using a horizontal attaching bracket positioned below the floor frame with a spacer, which allows for proper connection while minimizing weight increase and suppressing vibration noises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery unit is directly fastened to the floor frame, then the attachment is simple and firm, but weight increase and vibration noises occur in the intermediate frequency band
Solution Approach 1:
A rubber sheet is introduced as an intermediary element between the battery unit and the floor frame. This rubber sheet serves as a vibration isolator that reduces vibration noises and harmful factors in the intermediate frequency band while maintaining attachment firmness. The rubber material absorbs and dampens vibrations, preventing them from being transmitted to the vehicle body.
2Ease of manufacture
If the connection portions are vertically aligned, then direct fastening is easy, but misalignment occurs due to design constraints
Solution Approach 1:
The attachment structure is designed to accommodate vertical misalignment by changing the geometric parameters of the connection system. The L-shaped bracket and adjustable positioning allow the connection to tolerate vertical distance variations while maintaining proper fastening. This parameter flexibility resolves the conflict between manufacturing ease and alignment precision.
3Strength
If the rigidity of the attachment structure is increased, then the attachment firmness is improved, but weight increase occurs
Solution Approach 1:
A rubber sheet is used instead of a rigid structural element for vibration isolation. This flexible film approach provides the necessary vibration damping and isolation properties without adding significant weight. The rubber material achieves the required flexibility and cushioning while maintaining a lightweight profile, thus resolving the contradiction between strength and weight.
Data Source
AI summary
A battery unit which stores plural battery modules therein is attached to respective lower faces of a pair of floor frames at its both sides. The battery unit comprises an attaching bracket which protrudes substantially horizontally from the battery case and is positioned just below the lower face of the floor frame with a distance therebetween. A specified rigidity ratio is set for an attachment portion of the battery unit to the floor frame, and the attaching bracket is attached to the lower face of the floor frame via an intermediate part such that the above-described rigidity ratio is 0.1 or greater.