Coil Spring End Turns With Varying Wire Diameter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In suspension coil springs, foreign matter like sand can enter the space between the end turn portions and spring seats, leading to corrosion and potential breakage, and existing multi-layered coatings and shot peening methods may not adequately address these issues, especially requiring different apparatuses for varying projection energies.
Innovation Solution
A compression coil spring with varying wire diameters in the end turn portions and effective portions, ensuring that certain portions are always in contact with the spring seats, reducing the likelihood of foreign matter entry and wear, regardless of coating or surface treatment applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the end turn portion is separated from the spring seat according to load, then the coil spring can function properly with variable contact, but foreign matter such as sand can enter between the end turn portion and spring seat causing corrosion and breakage
Solution Approach 1:
The patent applies different wire diameters to different portions of the end turn. Specifically, the wire diameter in the second portion (which contacts the spring seat) is made larger than in the first portion. This local variation in geometry prevents foreign matter from entering the contact interface while maintaining proper suspension function through controlled separation and contact.
2Strength
If shot peening with large projection energy is applied for surface treatment, then surface hardness is improved, but it requires specialized equipment and increases manufacturing complexity
Solution Approach 1:
The patent changes the geometric parameters of the end turn, specifically varying the wire diameter along the end turn portion. This geometric modification provides the necessary durability and resistance to foreign matter entry without requiring complex surface treatment processes or specialized equipment, thereby avoiding increased manufacturing complexity.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A suspension coil spring includes a lower end turn portion (42), an upper end turn portion (44), and a helical effective portion (45) formed between the end turn portions (42, 44). The lower end turn portion (42) includes a first portion (42a) which contacts a lower spring seat irrespective of a load, and a second portion (42b) which contacts the lower spring seat or is separated from the same according to the load. The wire diameter of the second portion (42b) is greater than that of the first portion (42a) and an average wire diameter of the effective portion (45). The upper end turn portion (44) includes a third portion (44a) which contacts an upper spring seat irrespective of a load, and a fourth portion (44b) which contacts the upper spring seat or is separated from the same according to the load. The wire diameter of the fourth portion (44b) is greater that of the third portion (44a) and the average wire diameter of the effective portion (45).