Offset Bus Frame Profile for Stress Distribution and Weight Reduction

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Solution Overview

Problem

Current bus frames are heavy and costly due to the need for reinforcement at stressed areas, which increases weight and reduces passenger compartment space, and existing solutions either add weight or compromise structural integrity.

Innovation Solution

A longitudinal profile for the bus frame with offset faces for fixing the side and bottom walls, allowing for improved stress distribution and reduced material thickness, enabling a lighter, less expensive, and more robust frame design while increasing passenger compartment space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If reinforcement elements are added to the profile at lower corners to resist tensile, compressive and torsion stresses, then the mechanical strength is improved, but the weight and cost of the frame increase

Engineering Contradiction:
Improvemechanical strengthVSAvoidweight of frame
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The profile is divided into multiple faces (first face for bottom wall, second face for side wall) that are offset relative to each other. This segmentation allows each face to independently handle specific stress components, distributing the load more efficiently and reducing the need for additional reinforcement elements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention introduces an offset dimension between the first and second faces perpendicular to each other. This dimensional offset creates spatial separation of stress application points, allowing the profile to resist multi-axial stresses (tensile, compressive, torsion) simultaneously without requiring thicker walls or additional braces.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Strength

If the size or thickness of the profile is increased to improve mechanical strength, then the strength is improved, but the weight increases and the space available in the passenger compartment decreases

Engineering Contradiction:
Improvemechanical strengthVSAvoidpassenger compartment space
Core Design Contradiction:
StrengthVSVolume of moving object

Solution Approach 1:

By segmenting the profile into offset faces, the invention achieves high mechanical strength with a thinner overall profile thickness. The offset configuration allows the profile to maintain structural integrity while reducing material usage, thereby preserving passenger compartment volume.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each face of the profile is optimized for its specific function: the first face handles bottom wall connections and related stresses, while the second face handles side wall connections. This localized optimization allows the profile to achieve high strength-to-weight ratio without uniformly increasing thickness throughout the entire structure.

Inventive Principle:
Principle #3Local quality

3Strength

If reinforcement elements are added to the profile, then the mechanical strength is improved, but the production time and cost increase

Engineering Contradiction:
Improvemechanical strengthVSAvoidproduction time
Core Design Contradiction:
StrengthVSProductivity

Solution Approach 1:

The invention merges multiple stress-resistance functions into a single integrated profile design with offset faces. Instead of assembling separate reinforcement elements, the offset face configuration inherently provides resistance to tensile, compressive, and torsion stresses, simplifying manufacturing and reducing assembly time.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The offset profile design serves multiple functions simultaneously: it provides structural strength, resists multi-axial stresses, and maintains a compact form factor. This multi-functionality eliminates the need for separate reinforcement components, reducing both production complexity and time.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3377391B1Improved profile for the structure of a land vehicle for public passenger transport, structure, and vehicle comprising such a profile
Publication Date: 2020.01.08 BLUEBUS
  • EP3377391B1 patent drawingFigure 1a~1b
  • EP3377391B1 patent drawingFigure 2~3
  • EP3377391B1 patent drawingFigure 4

AI summary

The invention relates to a profile (100) for fixing a lower wall to a longitudinal side wall of a structure of a land vehicle for public passenger transport, with a closed cross-section, comprising: a first face (102) for fixing the lower wall; and a second face (104) for fixing the side wall; characterised in that one (102, 104) of said faces is offset in relation to the other (104, 102) of said faces in a direction perpendicular to said one face (102, 104), such that said other face (104, 102) ends before, and at a distance from, said one face (102, 104) in said perpendicular direction. The invention also relates to a structure comprising such a profile and to a land vehicle for public transport, particularly a road vehicle, and particularly an electric vehicle, comprising such a structure.