Round-to-Quadrangle Coil Spring for Nonlinear Load Response
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Solution Overview
Problem
Existing coil springs with nonlinear characteristics face challenges in reducing weight due to difficulties in processing wire rods with small diameters, leading to increased vehicle weight from dead coil portions that do not function as springs.
Innovation Solution
A coil spring design featuring a wire rod with a round section portion, a quadrangle section portion, and a variable section portion, where the quadrangle section portion has a smaller cross-sectional area than a square inscribed in a circle, allowing for easier processing and reduced weight by varying the cross-sectional area from circular to quadrangle, thereby achieving nonlinear characteristics without increasing vehicle weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the diameter of the wire rod is reduced to create a tapered portion for nonlinear characteristics, then the spring constant in the small load range is reduced, but the processing difficulty and cost increase significantly
Solution Approach 1:
The patent changes the cross-sectional shape parameter from circular to quadrangular, allowing the wire rod to achieve the desired small effective area without requiring extreme diameter reduction. This parameter change enables easier processing while maintaining the nonlinear spring characteristics through the variable cross-sectional area design.
2Force
If the number of turns of the tapered portion and small section portion is increased to reduce the spring constant, then the nonlinear characteristics are improved, but the weight of the vehicle increases due to more dead coil portions
Solution Approach 1:
The patent changes the cross-sectional area parameter of the wire rod to create a variable section portion with gradually decreasing area. This allows the spring to achieve the desired nonlinear characteristics and reduced spring constant without increasing the number of dead coil portions, thereby avoiding increased vehicle weight.
3Ease of manufacture
If a flat portion is formed in the wire rod to achieve nonlinear characteristics, then the processing is easier using ordinary rolling rolls, but the polar moment of inertia increases making weight reduction difficult
Solution Approach 1:
The patent uses a quadrangular cross-section which provides asymmetric geometry compared to circular sections. This asymmetric shape allows for easier processing similar to flat portions while maintaining a smaller polar moment of inertia, thus achieving both processing ease and weight reduction goals.
Solution Approach 2:
The patent changes the cross-sectional shape parameter to quadrangular with controlled width and thickness dimensions. By optimizing these parameters, the wire rod achieves easier processability comparable to flat portions while maintaining a smaller polar moment of inertia that enables weight reduction.
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 design results in a lightweight coil spring with nonlinear characteristics, reducing the polar moment of inertia and weight compared to conventional coil springs, while maintaining effective spring functionality across load ranges.
Implementation Method 1
a variable section portion, cross sections of which perpendicular to the longitudinal direction varies from circular to quadrangle and an area of the cross-section decreases
Implementation Method 2
When the coil spring is compressed to a predetermined length by a load, a gap exists between the coil portions of the effective spring part
Data Source
AI summary
According to one embodiment, a coil spring includes a wire rod with a first end and a second end. The wire rod includes a round section portion including a round first cross section perpendicular to a longitudinal direction of the wire rod, a quadrangle section portion including a quadrangle a second section perpendicular to the longitudinal direction, and a variable section portion formed between the round section portion and the quadrangle section portion of the wire rod. The cross section of the variable section portion varies from circular to quadrangle from the round section portion to the quadrangle section portion. The end turn part of the coil spring includes the quadrangle section portion. The width and thickness of the second cross-section are smaller than the diameter of the first cross-section. The area of the second cross section is smaller than the area of the square inscribed in the circle of diameter of the first cross section.