Replaceable Battery Pack Nut Coupling for Automated Maintenance
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Solution Overview
Problem
Conventional battery pack structures in electric vehicles face high maintenance costs due to the difficulty in replacing a welded battery mounting pipe nut when it becomes worn or damaged, requiring multiple nuts and bolts for replacement and manual detection of defects.
Innovation Solution
A coupling structure of a bolt and nut without welding, where a first nut with opposite screw threads is used externally and internally, and a second nut is fixed to the vehicle frame, allowing for easy replacement of the nut portion and detection of defects through tightening torque and number of turns analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a battery mounting pipe nut is welded to a vehicle body or chassis frame, then the connection strength is improved, but the ease of repair deteriorates because it is difficult to replace only the worn-out nut
Solution Approach 1:
The fastening system is segmented into multiple independent components: a first nut that can be replaced independently, a second nut that remains fixed to the vehicle frame, and a battery bolt. This segmentation allows the first nut to be replaced without replacing the entire fastening system or welding components together, thus maintaining ease of repair while ensuring connection strength through the remaining components.
2Ease of repair
If multiple nuts and bolts are provided for replacement, then the ease of repair is improved, but the device complexity increases
Solution Approach 1:
The first nut is extracted as a separate, replaceable component from the fastening system, while the second nut remains integrated with the vehicle frame. This extraction allows the worn-out first nut to be replaced independently without increasing overall system complexity, as the second nut and battery bolt remain in their original positions and configurations.
3Ease of repair
If a coupling structure of bolt and nut without welding is used, then the ease of repair is improved by enabling nut replacement, but the connection strength may deteriorate compared to welded structures
Solution Approach 1:
The first nut combines both internal and external screw threads, merging multiple fastening functions into a single component. The internal thread engages with the battery bolt while the external thread engages with the second nut, creating a combined fastening structure that maintains connection strength without requiring welding, thereby enabling easy replacement.
4Productivity
If automated battery pack replacement is implemented, then the productivity is improved, but the measurement precision requirement increases for detecting defects in bolts and nuts
Solution Approach 1:
The first nut is designed with an assembly/disassembly groove and opposing screw threads as preliminary structural features that facilitate automated detection and operation. The groove provides a defined interface for automated tools, while the opposing thread directions create predictable mechanical behavior that can be monitored for defects, enabling automated replacement systems to operate with high precision without manual inspection.
Data Source
AI summary
A vehicle battery pack case includes a battery bolt provided on a lateral side of a vehicle frame; a first nut provided outside the battery bolt, externally and internally formed with an internal screw thread and an external screw thread, of which tightening directions are opposite to each other, and tightened to the battery bolt through the internal screw thread; and a second nut provided outside the battery bolt and the first nut, and tightened to the first nut through the external screw thread formed on the first nut.