Saddle Vehicle Frame Welded Joint Strength

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Solution Overview

Problem

The existing frame structures for saddle type vehicles often face challenges in securing the rigidity and strength of welded portions under seat load, particularly when there are no connecting members between seat rails and main frames, or when the distances between seat rails and back stays are small, leading to increased bending stress and difficulties in welding.

Innovation Solution

The frame structure incorporates hole portions extending along the axis of the seat rail and back stay on the side surface of the pivot frame, allowing for welding along the peripheral edges, which enhances the joint strength and rigidity by distributing the load effectively and minimizing bending moments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the pivot frame is formed by joining left and right plate portions with gaps at openings, then the frame structure can be assembled, but welding of the pivot frames and rear pipes becomes difficult and joint strength is compromised

Engineering Contradiction:
Improveassembly easeVSAvoidwelded portion strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent introduces a seat rail as an intermediary component that connects the pivot frame to the rear pipe, bridging the gap between the joined plate portions. This mediator allows the structure to achieve both assembly ease through the joined plate portions and welded portion strength through the seat rail connection, resolving the contradiction between these two requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Volume of moving object

If distances between seat rails and back stays are small, then the frame structure is more compact, but rigidity with respect to seat load cannot be secured and bending stress on welded portions increases

Engineering Contradiction:
Improveframe volumeVSAvoidrigidity against seat load
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

The patent optimizes the spatial arrangement by positioning the seat rail at a specific distance from the pivot frame rear end, creating an optimal leverage arm in the vertical dimension. This dimensional optimization allows the frame to maintain compact volume while securing sufficient rigidity against seat load through proper structural spacing.

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

3Device complexity

If no connecting member is provided between seat rails and main frames, then the frame structure is simpler, but rigidity with respect to seat load cannot be secured

Engineering Contradiction:
Improveframe structure complexityVSAvoidrigidity against seat load
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The seat rail serves multiple functions: it connects the pivot frame to the rear pipe, provides structural rigidity against seat load, and acts as a mounting point for the seat. This multi-functional component achieves both structural strength and functional requirements without adding excessive complexity to the frame structure.

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

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration securely enhances the bending strength of the welded portions, allowing for efficient resistance to seat load moments and improved assembly quality, even with potential assembly errors, by providing a longer welding length and consistent welding structure across the frame.

Implementation Method 1

the pivot frame and the front portion of the seat rail are welded along a peripheral edge of the hole portion

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP2554465B1Frame structure for saddled vehicle
Publication Date: 2015.07.08 HONDA MOTOR CO LTD
  • EP2554465B1 patent drawingFigure 1
  • EP2554465B1 patent drawingFigure 2
  • EP2554465B1 patent drawingFigure 3

AI summary

A frame structure of a saddle type vehicle that can easily secure the bending strength of welded portions by a structure that seat rails are welded to rear portions of pivot frames, etc. is provided. Elongated holes 71A extending along an axis L of a front portion 15F of the seat rail is provided to a side surface of the pivot frame 14, and the pivot frame 14 and the front portion 15F of the seat rail are welded to each other at the peripheral edge of the elongated hole 71A.