Variable Wire Diameter Coil Spring for Uniform Stress Distribution
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Solution Overview
Problem
Conventional methods for reducing the weight of compression coil springs in knee-action-type vehicle suspensions by varying wire diameters result in non-uniform stress distribution, leading to increased variations in stress distribution rather than achieving a uniform distribution.
Innovation Solution
A knee-action-type suspension design featuring a compression coil spring with a large-diameter wire portion near the pivot, a small-diameter wire portion far from the pivot, and a continuously varying wire diameter between them, along with specifically configured spring seats to manage stress distribution uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the wire diameter is reduced on the offset side or alternating portions are formed to uniform stress distribution, then the weight of the compression coil spring is reduced, but the stress distribution becomes more non-uniform depending on arm member position
Solution Approach 1:
The wire diameter is varied locally along the coil spring, with a larger diameter at the first end (near pivot) and smaller diameter at the second end (far from pivot). This local quality variation compensates for the non-uniform stress distribution caused by the offset load application point, achieving more uniform stress throughout the wire while reducing overall weight compared to a constant diameter spring.
Solution Approach 2:
The wire diameter parameter is changed continuously or in steps along the length of the coil spring. By transitioning from a constant diameter to a variable diameter design, the spring achieves optimized stress distribution across different loading conditions while maintaining weight reduction benefits.
2Ease of manufacture
If a constant wire diameter is used in the compression coil spring, then the manufacturing is simplified, but the stress distribution is non-uniform and weight cannot be optimized
Solution Approach 1:
The wire diameter is varied locally along the coil spring, with a larger diameter at the first end (near pivot) and smaller diameter at the second end (far from pivot). This local quality variation compensates for the non-uniform stress distribution caused by the offset load application point, achieving more uniform stress throughout the wire while reducing overall weight compared to a constant diameter spring.
Solution Approach 2:
The wire diameter parameter is changed continuously or in steps along the length of the coil spring. By transitioning from a constant diameter to a variable diameter design, the spring achieves optimized stress distribution across different loading conditions while maintaining weight reduction benefits.
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 design approximates a uniform stress distribution in the compression coil spring, reducing the weight of the suspension and contributing to overall vehicle weight reduction.
Implementation Method 1
a compression coil spring which is arranged between the lower spring seat and the upper spring seat, and urges the arm member downward in a compressed state
Data Source
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AI summary
A knee-action-type suspension (11) is provided with an arm member (20), a compression coil spring (21), and a shock absorber (24). The arm member (20) is supported in such a way that it is pivotable in the upward and downward directions by a pivot (31) provided on an arm mounting portion (30). The coil spring (21) is arranged between spring seats (22, 23). The coil spring (21) is extended and retracted between a full-rebound state and a full-bump state in accordance with the magnitude of a load applied to a vehicle body. A wire (40) of the coil spring (21) includes a large-diameter wire portion (40a), a small-diameter wire portion (40b), and a wire diameter varying portion (40c). The large-diameter wire portion (40a) is provided in a first portion (21a) of the coil spring (21), which is on the side near to the pivot (31). The small-diameter wire portion (40b) is provided in a second portion (21b) of the coil spring (21), which is on the side far from the pivot (31). A wire diameter (d1) of the large-diameter wire portion (40a) is greater than a wire diameter (d2) of the small-diameter wire portion (40b).