Closed-Section Side Rail Reinforcement for Higher Bending Rigidity

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Solution Overview

Problem

Existing solutions for reducing choppy ride in vehicle bodies, such as enlarging side rail sectional shape or increasing steel plate thickness, result in increased weight and manufacturing costs, which are undesirable.

Innovation Solution

A side rail with a closed-section polygonal structure featuring base members and reinforcement plate members with greater thickness, joined by laser welding, enhances bending rigidity without enlarging the sectional shape or adding weight, and allows for effective antirust coating application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the sectional shape of the side rail is enlarged to enhance bending rigidity, then the choppy ride is reduced, but the space required for arranging the side rail increases

Engineering Contradiction:
Improvebending rigidityVSAvoidspace for arranging side rail
Core Design Contradiction:
StrengthVSArea of stationary object

Solution Approach 1:

The patent applies local quality by positioning reinforcement plate members with greater plate thickness specifically at corner portions of the side rail's closed-section structure. This localized reinforcement enhances bending rigidity where it is most needed (at the corners which are critical for structural stiffness) without requiring enlargement of the entire side rail sectional shape, thus resolving the contradiction between strength improvement and space consumption.

Inventive Principle:
Principle #3Local quality

2Strength

If the plate thickness of the entire steel plate configuring the side rail is increased to enhance bending rigidity, then the choppy ride is reduced, but the weight of the vehicle body increases greatly

Engineering Contradiction:
Improvebending rigidityVSAvoidweight of vehicle body
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

Instead of uniformly increasing plate thickness across the entire side rail, the patent applies local quality by using reinforcement plate members with greater plate thickness only at specific corner portions. This localized approach provides the necessary bending rigidity enhancement to reduce choppy ride while minimizing the overall weight increase of the vehicle body.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The side rail structure is segmented into base members and separate reinforcement plate members. This segmentation allows the reinforcement to be applied only where structurally necessary (at corner portions), rather than requiring uniform thickening of the entire side rail, thus achieving bending rigidity improvement with minimal weight penalty.

Inventive Principle:
Principle #1Segmentation

3Strength

If reinforcements are laid on and welded to the inner surfaces of the side rail to enhance bending rigidity, then the choppy ride is reduced, but the weight of the vehicle body increases greatly

Engineering Contradiction:
Improvebending rigidityVSAvoidweight of vehicle body
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent employs local quality by placing reinforcement plate members with greater plate thickness specifically at corner portions rather than applying reinforcements across the entire inner surface. This targeted approach achieves the necessary bending rigidity enhancement to reduce choppy ride while minimizing the weight increase that would result from comprehensive reinforcement.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The reinforcement strategy is segmented to apply thick plate members only at critical corner portions rather than uniformly across the entire side rail structure. This segmentation enables bending rigidity improvement with minimal additional weight.

Inventive Principle:
Principle #1Segmentation

4Strength

If the cab mount structure is improved to suppress vibrations from being transmitted to the cabin, then the choppy ride is reduced, but the weight of the vehicle body or manufacturing cost increases greatly

Engineering Contradiction:
Improvevibration dampingVSAvoidweight of vehicle body
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent employs curvature by configuring the side rail with a closed-section structure featuring corner portions and applying reinforcement plate members at these corners. This curved/geometric reinforcement approach enhances the structural rigidity and vibration damping capability of the side rail itself, providing an alternative to heavy cab mount structures for suppressing vibrations transmitted to the cabin.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 effectively reduces choppy ride without increasing vehicle body weight or manufacturing costs, while ensuring high antirust protection by minimizing welding spatters and oxided scales.

Implementation Method 1

the base members and the reinforcement plate members are joined to each other by laser welding

Methodology Applied
Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentEP3470304B1Side rail and manufacturing method for side rail
Publication Date: 2021.08.04 TOYOTA JIDOSHA KK
  • EP3470304B1 patent drawingFigure 1
  • EP3470304B1 patent drawingFigure 2~3B
  • EP3470304B1 patent drawingFigure 4A~4B

AI summary

A side rail (2) includes a reinforcement region (D) having a closed-section structure by base members (23, 26) and reinforcement plate members (24, 25, 27, 28) having a greater plate thickness than a plate thickness of the base members (23, 26). In the reinforcement region (D), in a state in which the reinforcement plate members (24, 25, 27, 28) are fitted in fitting portions (23a, 23b, 26a, 26b) provided at positions corresponding to respective corner portions (21d, 21e, 22d, 22e) in the base members (23, 26), the base members (23, 26) and the reinforcement plate members (24, 25, 27, 28) are joined to each other by laser welding.