Vehicle Seat Core Structure for Shrinkage-Resistant Frame Integration

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Solution Overview

Problem

The integration of a frame member with an expanded bead article in seat core materials for automobile seats often results in deformation and dimension accuracy issues due to differing shrinkage ratios, and existing solutions compromise unity and strength.

Innovation Solution

A seat core material design featuring a thermoplastic resin expanded bead article with a frame member embedded in its peripheral edge, including a front frame, rear frame, and side frames interconnected by slits that allow for curved or bent continuous parts outside the side frames, which mitigate shrinkage and maintain structural unity and strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If polyurethane foam is used as seat core material, then comfort and support are provided, but the material becomes brittle and cracks after prolonged use

Engineering Contradiction:
Improveservice life of seatVSAvoidresistance to cracking
Core Design Contradiction:
Duration of action of stationary objectVSStrength

Solution Approach 1:

The patent applies composite materials by combining polyurethane foam with a fabric layer impregnated with polyvinylidene fluoride (PVDF) binder and latex adhesive. This composite structure integrates the comfort properties of foam with the crack-resistant properties of the fabric-binder composite, resolving the contradiction between initial comfort and long-term durability against cracking

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the chemical and physical parameters of the seat core material by incorporating PVDF binder (5-20 parts by weight) and latex adhesive (5-20 parts by weight) into the fabric layer. These parameter changes transform the material properties to resist brittleness and cracking while maintaining the foam's comfort characteristics over extended service life

Inventive Principle:
Principle #35Parameter changes

2Strength

If fabric is added to prevent cracking, then durability is improved, but the material becomes harder and less comfortable

Engineering Contradiction:
Improveresistance to crackingVSAvoidcomfort of seat
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent applies local quality by placing the fabric layer with PVDF binder specifically at the surface where cracking occurs, while the underlying polyurethane foam maintains its soft, comfortable properties. This localized reinforcement prevents cracking at the surface without making the entire seat core hard and uncomfortable

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The composite structure of fabric impregnated with PVDF binder and latex adhesive, combined with polyurethane foam, creates a multi-layer material system where each layer performs its specific function: the fabric-binder layer provides crack resistance while the foam layer provides comfort, thus resolving the contradiction between durability and comfort

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If conventional materials are used, then manufacturing is simple, but environmental pollution occurs during production and disposal

Engineering Contradiction:
Improvesimplicity of productionVSAvoidenvironmental pollution
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent changes the material composition parameters by substituting conventional polyolefin-based materials with polyvinylidene fluoride (PVDF) binder and latex adhesive. This parameter change results in materials that are biodegradable and environmentally friendly, reducing pollution during production and disposal while maintaining ease of manufacturing through standard textile impregnation processes

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent adopts biodegradable materials (PVDF and latex) that can be disposed of without causing long-term environmental pollution. These materials allow the seat to be manufactured simply and disposed of responsibly, resolving the contradiction between manufacturing simplicity and environmental harm from conventional non-biodegradable materials

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 suppresses deformation and ensures high dimension accuracy while maintaining a sense of unity and strength in the seat core material, even during handling and attachment to a vehicle body.

Implementation Method 1

The expanded bead article generally causes molding shrinkage after in-mold molding, and thus the shape of the expanded bead article becomes stable with smaller dimensions than the metal mold dimensions

Methodology Applied
Scientific EffectShrinkage: Thermal Contraction

Data Source

PatentEP3583869B1Seat core material
Publication Date: 2025.01.08 JSP CORP
  • EP3583869B1 patent drawingFigure 1
  • EP3583869B1 patent drawingFigure 2
  • EP3583869B1 patent drawingFigure 3(A)~3(C)

AI summary

A seat core material of the present invention is a seat core material for vehicle including a thermoplastic resin expanded bead article and a frame member embedded in a peripheral edge portion of the expanded bead article. The frame member includes a front frame part, a rear frame part, and two side frame parts interconnecting the front frame part and the rear frame part. Slits crossing the two side frame parts are formed along a longitudinal direction with continuous parts left intact outside the side frame parts on both ends of the expanded bead article. The slit penetrates or does not penetrate the expanded bead article in a thickness direction. The continuous parts are formed in a curved shape or a bent shape. Accordingly, it is possible to provide a seat core material excellent in a sense of unity between a frame member and a expanded bead article and a strength desired for the expanded bead article in which the expanded bead article becomes less deformed even when the frame member is embedded in and integrated with the foamed article compact and the expanded bead article is very excellent in dimension accuracy.