Hybrid Steering Casing with Metallic Reinforcement

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Solution Overview

Problem

Current steering casings, typically made from aluminum alloys or reinforced plastics, face issues of weight, corrosion susceptibility, and manufacturing complexity due to dimensional precision requirements, while hybrid parts struggle with tooling and guidance in producing the hollow shape needed for steering casings.

Innovation Solution

A hybrid steering casing design featuring a U-section reinforcing element made of metallic or composite materials, coated with a polyamide plastic, which provides localized reinforcement and is manufactured using an overmolding process with specific holding fins and textured surfaces to ensure adhesion and precise geometry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If aluminum alloy casting is used for steering casing, then good mechanical strength is achieved, but weight increases and corrosion susceptibility occurs

Engineering Contradiction:
Improvemechanical strengthVSAvoidweight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent uses a composite structure combining a metallic reinforcing element (steel or aluminum alloy) with a thermoplastic material (polyamide, polypropylene, or polycarbonate). The metallic element provides the necessary mechanical strength and rigidity, while the thermoplastic material reduces overall weight and provides corrosion resistance. This composite approach resolves the contradiction by distributing structural requirements between materials with complementary properties.

Inventive Principle:
Principle #40Composite materials

2Strength

If aluminum alloy casting is used for steering casing, then good mechanical strength is achieved, but corrosion susceptibility occurs

Engineering Contradiction:
Improvemechanical strengthVSAvoidcorrosion susceptibility
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The composite structure combines a metallic reinforcing element with a thermoplastic material that provides corrosion resistance. The thermoplastic coating protects the metallic element from environmental corrosion while maintaining structural integrity. This resolves the contradiction by using materials with complementary properties - the metal provides strength and the plastic provides corrosion protection.

Inventive Principle:
Principle #40Composite materials

3Weight of moving object

If reinforced plastic material is used for steering casing, then weight is reduced, but rigidity decreases

Engineering Contradiction:
ImproveweightVSAvoidrigidity
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent creates a composite material system where a metallic reinforcing element (providing rigidity and strength) is combined with a thermoplastic material (providing weight reduction and corrosion resistance). The metallic element acts as an internal reinforcement skeleton, allowing the use of lighter thermoplastic materials while maintaining the required rigidity for steering application.

Inventive Principle:
Principle #40Composite materials

4Weight of moving object

If reinforced plastic material is used for steering casing, then weight is reduced, but manufacturing complexity increases due to reinforcement requirements

Engineering Contradiction:
ImproveweightVSAvoidmanufacturing complexity
Core Design Contradiction:
Weight of moving objectVSEase of manufacture

Solution Approach 1:

The metallic reinforcing element is manufactured separately as a pre-formed component with specific geometric shapes and reinforcement zones, then integrated with the thermoplastic material through co-molding or overmolding processes. This preliminary preparation of the reinforcement element simplifies the overall manufacturing process by allowing modular production and assembly, reducing the complexity of creating complex reinforced structures from scratch.

Inventive Principle:
Principle #10Preliminary action

5Shape

If hybrid part with overmolding is used for steering casing, then freedom of forms and rigidity are achieved, but tooling complexity increases

Engineering Contradiction:
Improvefreedom of formsVSAvoidtooling complexity
Core Design Contradiction:
ShapeVSDevice complexity

Solution Approach 1:

The hybrid steering casing is divided into two distinct components: a metallic reinforcing element and a thermoplastic material. Each component can be manufactured using optimized processes for its material properties, and then integrated through co-molding or overmolding. This segmentation allows for simplified tooling design compared to attempting to form the complete complex shape in a single step, as each component can be prepared separately before final integration.

Inventive Principle:
Principle #1Segmentation

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 solution results in a lightweight, corrosion-resistant, and cost-effective steering casing with improved rigidity and precise geometry, addressing the limitations of existing materials and manufacturing methods.

Implementation Method 1

The reinforcing element is covered with a mass of plastic material, which adheres to this element so as to obtain a one-piece steering casing

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP2441648B1Automobile steering gearbox with reinforcement element
Publication Date: 2013.09.04 JTEKT EUROPE SAS
  • EP2441648B1 patent drawingFigure 1~2
  • EP2441648B1 patent drawingFigure 3~5
  • EP2441648B1 patent drawingFigure 6~15

AI summary

The gearbox (1) has a reinforced structure placing and guiding a toothed rack. A pinion is engaged with the toothed rack. A push rod presses the pinion against the toothed rack. A U-shaped reinforcement element (6) is coated with a plastic mass (12). Regions (7) of the reinforcement element reinforce gearbox functional regions such as housing (2) of the pinion, housing of the push rod and/or fixing regions (4, 5) of the gearbox. The reinforcement element is made of a composite material or steel. An external surface of the reinforcement element is textured. The plastic mass comprises polyamide, polyamide 66, aromatic polyamide, polyphenylene sulfide (PPS), reinforced glass fiber and/or carbon. An independent claim is also included for a manufacturing method for a steering gearbox of a vehicle.