Straddled Vehicle Seat Frame Joint Strength and Assembly

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Solution Overview

Problem

Straddled vehicle seat frames made of pipes face challenges in securing sufficient strength at joints, particularly in split-type designs, where existing welding methods are inadequate for ensuring reliable strength while maintaining low manufacturing costs.

Innovation Solution

A straddled vehicle design featuring a seat frame structure with large-sized joints formed by welding pipes, where the joints are positioned to allow for easy alignment and attachment using detachable fasteners, and additional features like cross members and engaging portions facilitate easier assembly and enhanced security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the vehicle body frame is made of pipes joined by welding, then manufacturing cost is reduced, but the joints cannot reliably secure sufficient strength

Engineering Contradiction:
Improvemanufacturing costVSAvoidjoint strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The seat frame is divided into a front seat frame and a rear seat frame that can be detachably connected. This segmentation allows the use of fasteners instead of welding at the joint between front and rear seat frames, maintaining both low manufacturing cost and sufficient joint strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Fasteners are introduced as intermediary components to connect the front and rear seat frames. These fasteners serve as a mediator that transfers loads between the pipe structures while allowing for easy assembly and disassembly, resolving the contradiction between welding strength and manufacturing cost.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If the joints are made large to secure sufficient strength, then joint strength is improved, but the attachment process becomes more complex

Engineering Contradiction:
Improvejoint strengthVSAvoidattachment process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The joint design incorporates detachable fasteners that allow the connection between front and rear seat frames to be dynamically assembled and disassembled. This dynamic connection method achieves strong joints without permanent welding, simplifying the attachment process while maintaining strength.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The fasteners are designed with features that facilitate preliminary alignment and positioning of the seat frames before final tightening. This preliminary action ensures proper alignment and simplifies the overall attachment process while securing strong joints.

Inventive Principle:
Principle #10Preliminary action

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

The design effectively secures large strength at the joints between the front and rear seat frames, simplifies the attachment process, and enhances crime prevention by hiding fasteners, while allowing for easy replacement of passenger seats and unitary attachment of rear fenders and lamps.

Implementation Method 1

The left welded portion welds the left upper pipe and the left lower pipe. The right welded portion welds the right upper pipe and the right lower pipe.

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP3088284B1Straddled vehicle
Publication Date: 2017.08.16 YAMAHA MOTOR CO LTD
  • EP3088284B1 patent drawingFigure 1
  • EP3088284B1 patent drawingFigure 2
  • EP3088284B1 patent drawingFigure 3

AI summary

A left welded portion (27) welds a left upper pipe 23and a left lower pipe (25). A right welded portion (28) welds a right upper pipe (24) and a right lower pipe (26). A left front joint (31) is disposed forward of a front end of the left welded portion, and is welded to the left upper pipe and the left lower pipe. A right front joint (32) is disposed forward of a front end of the right welded portion, and is welded to the right upper pipe and the right lower pipe. A rear seat frame (22) includes a left rear joint (35) and a right rear joint (36). The left rear joint is joined to the left front joint. The right rear joint is joined to the right front joint. The left fastener (37) detachably fixes the left rear joint and the left front joint. The right fastener (38) detachably fixes the right rear joint and the right front joint.