Fibre-Reinforced Leaf Spring Progressive Stiffness
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Solution Overview
Problem
Existing leaf spring assemblies for motor vehicles do not easily accommodate progressive spring rates, making them difficult to produce and mount, and they do not effectively manage tensile and bending stresses under load, which affects driving comfort and stability.
Innovation Solution
A leaf spring assembly with fibre-reinforced plastics, featuring a first and second receiving device that securely holds the end portions in a non-displaceable manner, allowing pivotable support around a transverse axis, resulting in superimposed tensile and bending stresses that create a progressive spring characteristic, increasing stiffness with load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the leaf spring is designed with fixed end portions held in a non-displaceable way, then the spring rate becomes progressive and driving comfort is improved, but the device complexity increases due to the requirement for both moment-resistant and moment-free receiving devices
Solution Approach 1:
The receiving device is segmented into two distinct types: a first receiving device that provides moment-resistant support and a second receiving device that provides moment-free support. This segmentation allows the leaf spring to experience both bending and tensile stresses, creating a progressive spring rate that improves driving comfort while managing the complexity through functional differentiation.
Solution Approach 2:
Different portions of the leaf spring are given different support conditions: one end portion is held in a moment-resistant way while the other is held in a moment-free way. This local differentiation of support quality enables the spring to develop progressive characteristics by combining bending and tensile stress effects in specific regions.
2Manufacturing precision
If the end portions are held in a non-displaceable way, then the manufacturing precision is improved, but the ease of manufacture deteriorates due to the complex assembly requirements
Solution Approach 1:
The assembly is segmented into modular components: the leaf spring with its distinct end portions, the first receiving device for moment-resistant support, and the second receiving device for moment-free support. This segmentation allows each component to be manufactured and assembled independently, improving manufacturing precision while managing assembly complexity through standardization.
3Adaptability or versatility
If the leaf spring is subjected to both bending and tensile loads, then the progressive spring characteristic is achieved, but the stress distribution becomes more complex affecting the spring design
Solution Approach 1:
The leaf spring is designed with local quality variations where different portions experience different stress types: one end portion is designed to experience primarily bending stress while the other experiences tensile stress. This local differentiation of stress quality enables the progressive spring characteristic while managing the complexity of stress distribution through targeted design features.
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 assembly provides a progressive spring characteristic that enhances driving comfort and stability by increasing stiffness under load, ensuring effective stress distribution and easy production and mounting.
Implementation Method 1
a leaf spring of fibre-reinforced plastics for resiliently supporting a wheel carrier of the motor vehicle, wherein the leaf spring comprises a first end portion, a spring portion, a bendable portion and a second end portion
Implementation Method 2
the first end portion and the second end portion are held substantially in a non-displaceable way relative to one another... the leaf spring is subjected to tensile loads... superimposed on one another and, together, lead to a progressive spring characteristic
Data Source
AI summary
A leaf spring assembly for a wheel suspension of a motor vehicle comprises a leaf spring of fibre-reinforced plastics for resiliently supporting a wheel carrier of the motor vehicle. The leaf spring comprises a first end portion, a spring portion, a bendable portion and a second end portion. The leaf spring further comprises a first receiving device for supporting the first end portion and a second receiving device for supporting a second end portion. The first receiving device and the second receiving device are designed such that the first end portion and the second end portion are held in a non-displaceable way relative to one another. At least one of the first and second receiving devices are designed such that the respective associated end portion is supported in a moment-free way in the receiving device.