Fiber-Reinforced Bending Spring With Variable Fiber Volume

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Solution Overview

Problem

Conventional flexible spring elements made of fiber-plastic composite materials face challenges in cost-effectiveness and adaptability to varying stresses, often resulting in oversized designs with excessive weight and manufacturing complexity.

Innovation Solution

The solution involves a flexible spring element with varying volume fractions of spiral spring fibers in functional layers, where the volume fraction is higher in longitudinal sections and lower in curvature sections, utilizing a matrix material removal layer to control fiber distribution and reduce material usage, and incorporating a distance expansion element in curved sections to enhance deformation resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the bending spring element is designed with a uniform thickness to withstand maximum tensile and compressive loads in curved sections, then the strength and reliability are improved, but the weight and material usage increase excessively in longitudinal sections where loads are significantly lower

Engineering Contradiction:
ImprovestrengthVSAvoidweight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent implements local quality by varying the thickness of the bending spring element along its length. The element has greater thickness in curved sections where tensile and compressive loads are highest, and reduced thickness in longitudinal sections where loads are significantly lower. This is achieved through a molding process that allows different thickness regions to be formed in a single operation, optimizing both strength and weight by matching material distribution to actual load requirements.

Inventive Principle:
Principle #3Local quality

2Reliability

If several bending spring elements are combined into a bending spring assembly to distribute loads, then the reliability and load distribution are improved, but the device complexity and manufacturing effort increase

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple functional elements into a single integrated bending spring element. By forming the element with varying thickness in one piece using a molding process, it achieves the load-distributing benefits of multiple elements while eliminating the complexity of assembly, fasteners, and alignment that would be required for separate components.

Inventive Principle:
Principle #5Merging (Combining)

3Weight of moving object

If the bending spring element has varying thickness to optimize weight, then the weight and material usage are reduced, but the manufacturing precision and production complexity increase

Engineering Contradiction:
ImproveweightVSAvoidmanufacturing precision
Core Design Contradiction:
Weight of moving objectVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by varying the thickness parameter of the bending spring element along its length. The molding process allows continuous or stepped variation of thickness to optimize weight while maintaining manufacturing feasibility. The process controls dimensional accuracy through standard molding techniques, avoiding the need for complex post-processing or assembly operations.

Inventive Principle:
Principle #35Parameter changes

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 approach allows for cost-effective production of high-quality flexible spring elements with optimized spring properties, reduced weight, and improved resistance to environmental conditions, while minimizing material expenditure and manufacturing effort.

Implementation Method 1

a functional layer section arranged in the curvature section facing outwards is subjected to tensile stress

Methodology Applied
Scientific EffectTensile stress: Tension

Implementation Method 2

a functional layer section opposite and facing inwards in the curvature section is subjected to compressive stress

Methodology Applied
Scientific EffectCompressive stress: Compression

Implementation Method 3

during a deflection of the bending spring element as intended

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4055297B1Bending spring element comprising a fibre reinforced material
Publication Date: 2023.12.13 DANTO INVENTION GMBH & CO KG
  • EP4055297B1 patent drawingFigure 1~3
  • EP4055297B1 patent drawingFigure 4
  • EP4055297B1 patent drawingFigure 5~6

AI summary

The invention relates to a flexible spring element (1) made of a fibre-reinforced plastics composite material (4, 23), a functional layer (2, 3) made of a fibre-reinforced plastics composite material (4) being located on each of two mutually opposite sides (9, 10) of a central plane of the flexible spring element (1). At least one matrix material discharge layer (17) extending parallel to the two functional layers (2, 3) and in a longitudinal direction (7) is arranged in at least one longitudinal portion (14) and has at least a fraction of discharge layer fibres (18) which are oriented differently from the longitudinal direction (7) of the flexible spring element (1). Within at least one curved portion (13) of the flexible spring element (1) a first volume fraction of flexible spring fibres (5) in the functional layers (2, 3) is smaller, preferably smaller by several % than a second volume fraction of flexible spring fibres (5) in the functional layers (2, 3) within the at least one longitudinal portion (14).