Spur Gear Radial Structure for Lightweight Load Distribution

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Solution Overview

Problem

Existing spur gears face a conflict between stability and material savings, particularly in automotive drive units where high mechanical stress is encountered, and existing designs struggle to achieve optimal stability while minimizing material usage.

Innovation Solution

The design incorporates a radial connection structure with a disc-shaped base body reinforced on one side with struts of two types: narrow and tall struts for tensile forces, and flat and wide struts for thrust forces, optimized for production by forming processes like forging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If the radial connection structure uses uniform struts for both tensile and thrust forces, then the design is simpler, but material savings are reduced and weight increases

Engineering Contradiction:
Improvematerial savingsVSAvoidstructural complexity
Core Design Contradiction:
Loss of substanceVSDevice complexity

Solution Approach 1:

The patent applies local quality by differentiating strut designs based on their functional requirements. Struts are classified into two types: those optimized for tensile forces (narrower cross-section) and those optimized for thrust forces (wider cross-section). This localized differentiation allows each strut to use only the material necessary for its specific function, achieving significant material savings while maintaining structural integrity.

Inventive Principle:
Principle #3Local quality

2Loss of substance

If the gear is made from plastic material with optimized shapes, then material savings and design flexibility are improved, but overall strength is extremely limited

Engineering Contradiction:
Improvematerial efficiencyVSAvoidoverall strength
Core Design Contradiction:
Loss of substanceVSStrength

Solution Approach 1:

The patent employs composite material construction by combining a disc-shaped base body made of metallic material (such as steel) with a radial connection structure that can be formed through forging. This composite approach leverages the high strength properties of metal for the load-critical components while allowing optimized geometries that reduce material usage, thereby achieving both strength and material efficiency.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If the radial connection structure is designed with asymmetric strut arrangements, then manufacturing by forging is enabled, but the design complexity increases

Engineering Contradiction:
Improveforging suitabilityVSAvoiddesign complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent implements asymmetry in the radial connection structure by arranging struts of different types (tensile-optimized and thrust-optimized) in non-uniform patterns around the base body. This asymmetric arrangement reflects the actual asymmetric distribution of tensile and thrust forces during gear operation, enabling optimized material placement that facilitates forging manufacturing while accurately representing the functional requirements.

Inventive Principle:
Principle #4Asymmetry

4Strength

If all struts are designed to handle both tensile and thrust forces, then the structure is more robust, but material usage increases and weight increases

Engineering Contradiction:
Improvestructural robustnessVSAvoidgear weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent applies segmentation by dividing the radial connection structure into distinct strut types with specialized functions. Instead of using uniform struts that must handle all force types, the structure is segmented into tensile-force-optimized struts and thrust-force-optimized struts. This segmentation allows each component to be minimized in mass while maintaining adequate strength for its specific function, reducing overall gear weight.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4055303B1Spur gear
Publication Date: 2025.06.04 VOLKSWAGEN AG
  • EP4055303B1 patent drawingFigure 1~2
  • EP4055303B1 patent drawingFigure 3~4
  • EP4055303B1 patent drawingFigure 5~7

AI summary

The invention relates to a spur gear (10), comprising - a radially outer, spur-cut gear rim (30), - a radially inner hub (20), and - a rotationally symmetrical radial connecting structure (40) which integrally connects the gear rim (30) to the hub (20), the radial connecting structure (40) having mutually spaced struts (44, 46), which extend between the hub (20) and the gear rim (30), and axial holes (48), which are situated between the struts (44, 46). The invention is distinguished in that the radial connecting structure (40) has a disc-shaped main body (42), through which the axial holes (48) pass and which has an axial front side and an axial rear side, with the struts (44, 46) being situated on the front side.