Fiber-Reinforced Resin Shock Absorber Attachment Rigidity

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Solution Overview

Problem

Straddled vehicles with fiber-reinforced resin vehicle body frames face challenges in achieving sufficient rigidity in the cross-frame part that supports the rear cushion, particularly due to the material's weakness under compressive stress.

Innovation Solution

The design incorporates a shock-absorber attachment part with a cylindrical shape formed from fiber-reinforced resin, featuring extension of resin-made side-face parts to distribute tensile stress when the shock absorber contracts, enhancing the rigidity by supporting the attachment surface and dispersing forces across the tube part.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the vehicle body frame is manufactured using fiber-reinforced resin, then weight reduction and manufacturing efficiency are improved, but rigidity of the cross-frame part supporting the rear cushion deteriorates

Engineering Contradiction:
Improvevehicle body frame weightVSAvoidrigidity of cross-frame part
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent applies local quality by creating a reinforced structure specifically at the cross-frame part where the rear cushion is supported. The reinforcement structure includes additional ribs or thickened sections localized at the cushion support area, while other parts of the fiber-reinforced resin frame maintain their original lightweight design. This allows the cross-frame part to achieve metal-level rigidity while the overall frame retains weight reduction benefits.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining fiber-reinforced resin with additional reinforcing elements such as metal inserts, carbon fiber layers, or structural ribs made from high-strength materials. This composite approach creates a hybrid structure that leverages the weight advantage of fiber-reinforced resin while incorporating the rigidity of stronger materials at critical load-bearing locations.

Inventive Principle:
Principle #40Composite materials

2Strength

If the cross-frame part is reinforced to improve rigidity, then strength is improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improverigidity of shock-absorber attachment partVSAvoidstructure complexity of cross-frame part
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent merges the reinforcement structure with the cross-frame part itself, integrating the reinforcing ribs or thickened sections as integral parts of the molded fiber-reinforced resin component. This eliminates the need for separate reinforcement pieces and reduces assembly steps, thereby improving rigidity while minimizing increases in device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent incorporates reinforcement features directly into the molding process of the fiber-reinforced resin cross-frame part. By pre-forming the reinforced structure during manufacturing rather than adding it later, the patent achieves the desired rigidity without requiring post-manufacturing assembly operations, thus avoiding complexity increases.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3536590B1Straddled vehicle
Publication Date: 2021.05.05 YAMAHA MOTOR CO LTD
  • EP3536590B1 patent drawingFigure 1
  • EP3536590B1 patent drawingFigure 2
  • EP3536590B1 patent drawingFigure 3

AI summary

An object of the present invention is to provide a straddled vehicle which can improve rigidity of a shock-absorber attachment part that includes a portion formed of fiber-reinforced resin. The straddled vehicle according to the present invention includes a shock-absorber attachment part that is connected to a main-member body part and that has an attachment surface to which an upper end part of a shock absorber is attached. The shock-absorber attachment part includes: a resin-made attachment surface part which includes an attachment surface to which the upper end part of the shock absorber is attached, and which is formed of a fiber-reinforced resin in which resin is reinforced with fiber; a resin-made left side-face part constituting a left side-face part that, as seen in the vehicle-body frontward direction or backward direction, extends from the attachment surface in the vehicle-body downward direction to a location further leftward in the vehicle-body left-right direction than the center in the vehicle-body left-right direction of the attachment surface, and which includes a left-side-face-part supported part that is connected to the main-member body part, and is formed of a fiber-reinforced resin in which resin is reinforced with fiber; and a resin-made right side-face part constituting a right side-face part that, as seen in the vehicle-body frontward direction or backward direction, extends from the attachment surface in the vehicle-body downward direction to a location further rightward in the vehicle-body left-right direction than the center in the vehicle-body left-right direction of the attachment surface, and which includes a right-side-face-part supported part that is connected to the main-member body part, and is formed of a fiber-reinforced resin in which resin is reinforced with fiber.