Ribbed Plastic Control Arm Structure for Stable Mass Production

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Solution Overview

Problem

Chassis components for motor vehicles, particularly wishbones, face challenges in achieving high dimensional stability and favorable pricing for mass production due to issues with thick-wall injection molding, which often results in deformations, voids, and increased costs.

Innovation Solution

A chassis component design featuring a core part made of fiber-reinforced plastic with a three-dimensional structure of thin ribs, encapsulated by an outer shell of fiber-reinforced plastic, produced through a two-stage hybrid injection molding process, ensuring high dimensional stability and reduced stress concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If thick-wall injection molding is used to produce chassis components, then structural integrity is improved, but deformations and voids occur reducing manufacturing precision

Engineering Contradiction:
Improvestructural integrityVSAvoiddimensional stability
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The chassis component is divided into a core part and an outer shell produced in two separate injection molding stages. The core part provides structural integrity while the outer shell encases it to prevent deformations and voids, resolving the contradiction between strength and manufacturing precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The core part is produced first with a ribbed structure that pre-establishes the load-bearing framework. The outer shell is then molded around this core, preventing defects before they can form, thereby achieving both structural integrity and dimensional stability.

Inventive Principle:
Principle #10Preliminary action

2Strength

If thick-wall injection molding is used for chassis components, then structural integrity is improved, but production costs increase

Engineering Contradiction:
Improvestructural integrityVSAvoidproduction cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

By segmenting the component into core and shell produced in two stages, the process eliminates defects associated with thick-wall molding, reducing scrap rates and rework costs while maintaining structural integrity, thereby improving ease of manufacture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The wall thickness parameter is changed from uniform thick-wall to variable thickness with thin ribs in the core and encasing outer shell. This parameter change enables successful injection molding without the deformations and voids that increase production costs.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If uniform wall thickness is used in injection molded components, then manufacturing simplicity is improved, but stress concentrations increase reducing reliability

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidstress concentration
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The core part features thin ribs with varying thicknesses optimized for specific load paths, while the outer shell provides uniform encasement. This local quality variation reduces stress concentrations in critical areas while maintaining manufacturing feasibility.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The component uses a composite structure combining the ribbed core part made of fiber-reinforced plastic with the encasing outer shell. This composite construction distributes stresses more evenly, reducing stress concentrations while maintaining ease of manufacture through injection molding.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3936354B1Chassis component for a motor vehicle
Publication Date: 2023.08.30 AUTOTECH ENG SL
  • EP3936354B1 patent drawingFigure 1
  • EP3936354B1 patent drawingFigure 2
  • EP3936354B1 patent drawingFigure 3

AI summary

The invention relates to a chassis component for a motor vehicle, in particular a control arm, comprising a core part (2) having at least one first connection point (4) and at least one second connection point (5, 6), and an outer shell (3) made of plastic, preferably fiber-reinforced plastic, which partially or completely encloses the core part (2). To further develop such a component so that it can be mass-produced with high dimensional stability and a favorable component price, the invention provides that the core part (2) is made of plastic and has a three-dimensional structure with a plurality of wall-shaped and/or pin-shaped ribs (2.1), wherein at least 60%, preferably at least 95%, of the ribs (2.1) each have a thickness of a maximum of 5 mm, and wherein the outer shell (3) encloses the ribs (2.1). Furthermore, a method for manufacturing such a chassis component is described.