EV Suspension Beam Joint Structure for Reliable Drive Shaft Support
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Solution Overview
Problem
Electric commercial vehicles require higher reliability and manufacturing efficiency in their suspension devices due to increased weight and loading, which is challenging with existing de Dion type suspension devices that use bolt-fastened saddles and axle beams, requiring precise alignment and increased manufacturing costs.
Innovation Solution
The suspension device incorporates hollow and beam members with projecting and recessed portions for enhanced joint strength and alignment accuracy, using a configuration of bolts arranged in specific patterns and shapes to improve contact pressure and stress resistance, and includes an integrally forged axle beam with thick support portions for increased reliability and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the saddles and the axle beam are manufactured as separate members and fastened by bolts, then the manufacturing cost is reduced, but the reliability of the joint surfaces deteriorates due to extremely large inputs affecting the joint portions
Solution Approach 1:
The invention introduces asymmetric joint surface structures including projecting portions and recessed portions that engage with each other. The projecting portion extends in the vehicle width direction and has a larger cross-sectional area than the recessed portion, creating an asymmetric geometry that improves stress distribution and joint reliability while maintaining separate member manufacturing
Solution Approach 2:
The invention applies local quality enhancement by providing reinforcing ribs on the joint surfaces of both the saddle and axle beam. These ribs are strategically positioned at high-stress areas to locally strengthen the joint portions without requiring complete redesign of the entire structure, thus maintaining cost-effectiveness while improving reliability
2Manufacturing precision
If high alignment accuracy at the joint surfaces is required to ensure reliability, then the manufacturing precision is improved, but the working efficiency in manufacturing deteriorates
Solution Approach 1:
The asymmetric projecting and recessed portions serve as self-aligning features during assembly. The geometry naturally guides the components into correct alignment, reducing the need for high-precision machining while maintaining reliable joint formation. This asymmetric design acts as a mechanical guide that compensates for normal manufacturing tolerances
Solution Approach 2:
The projecting and recessed portions are pre-formed as integral features during the manufacturing process of the saddle and axle beam. This preliminary formation of alignment features eliminates the need for separate alignment operations or adjustments during assembly, thereby improving manufacturing efficiency without sacrificing alignment accuracy
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A suspension device for electric vehicle, such as an electric commercial vehicle, which can further improve reliability and manufacturing efficiency, is provided. The suspension device for electric vehicle includes: a power transmission mechanism 4 to which a driving force of a motor 2 mounted on a vehicle is transmitted; and a pair of drive shafts 6L, 6R configured to transmit the driving force transmitted to the power transmission mechanism 4 to a pair of wheels 8L, 8R. The suspension device for electric vehicle further includes: a pair of hollow members 41L and 41R respectively connected to elastic bodies 16L and 16R configured to suspend a vehicle body of the vehicle, the pair of hollow members 41L and 41R each configured to house, in an internal space of the hollow member, part of an associated one of the pair of drive shafts 6L, 6R; and a beam member 31 joined to the pair of hollow members 41L and 41R by bolt fastening. At least one of a hollow member joint portion or a beam member joint portion has a projecting portion. The hollow member joint portion constitutes a side surface of each of the hollow members 41L and 41R, and the beam member joint portion constitutes a side surface of an end portion of the beam member 31. The other one of the hollow member joint portion or the beam member joint portion has a recessed portion.