Suspension Coil Spring End Turn Insulating Sheet
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Solution Overview
Problem
Existing suspension coil springs in vehicles are prone to breaking due to rust and damage caused by foreign matter like sand getting stuck between the end turn portions and spring seats, with existing coatings being ineffective and costly, and heavy insulators increasing unsprung weight and accumulating debris.
Innovation Solution
A suspension coil spring with an insulating sheet made of rubber-elastic material attached to the lower end turn portion, specifically designed to prevent wear and damage by foreign matter, improving durability and reducing the risk of coil spring breakage, while also integrating a convex portion to adjust force line positions and reduce thickness for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating film of two-layer structure is formed on the coil spring to prevent rust from thrown-up pebbles, then rust resistance is improved, but the cost of coating increases and the coating provides little protection against sand trapped between the end turn portion and spring seat
Solution Approach 1:
The patent applies different protective measures to different parts of the coil spring. Specifically, a grease layer is applied locally to the end turn portions (first and second portions) that contact the spring seat, while a coating film is applied to other parts of the coil spring body. This localized approach provides targeted protection where it is most needed (against sand and foreign matter at contact points) while reducing overall coating material and cost.
Solution Approach 2:
The patent introduces grease as an intermediary substance between the end turn portions and the spring seat. This grease layer acts as a mediator that prevents direct contact between foreign matter (sand, dust) and the coil spring wire, thereby protecting against wear and corrosion without requiring expensive protective coatings on the entire spring.
2Reliability
If a block insulator is arranged on the spring seat to prevent end turn portion wear, then wear protection is improved, but unsprung weight becomes large and foreign matter accumulates on the insulator surface
Solution Approach 1:
The patent replaces the rigid block insulator with a thin film approach using grease coating on the end turn portions. This thin film provides the necessary protective function (preventing wear and corrosion from foreign matter) while maintaining flexibility and minimizing weight, avoiding the problems associated with heavy rigid insulators.
Solution Approach 2:
The grease layer serves as a consumable protective layer that can be easily reapplied. Instead of using a permanent heavy insulator, the grease provides temporary protection that is replenished as needed, offering a lightweight and cost-effective alternative to permanent insulating components.
3Reliability
If a tube made of synthetic resin with a slit is fitted to the end turn portion to prevent wear, then wear protection is improved, but the tube is compressed under large load causing load/deflection characteristics to vary and corrosive materials enter through the slit
Solution Approach 1:
The patent changes the protective approach from a rigid structural modification (fitted tube) to a material-based solution (grease coating). This parameter change allows the end turn portions to maintain their original structural integrity and load-bearing characteristics while providing protection through the grease layer, avoiding the compression and deformation issues of fitted tubes.
Solution Approach 2:
The patent uses a composite protective system combining grease (organic material) with the metal wire of the coil spring. This composite approach provides wear and corrosion protection without altering the structural properties of the wire, unlike the synthetic resin tube that caused deformation under load.
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 insulating sheet effectively prevents wear and damage from foreign matter, enhancing the coil spring's durability and reducing the risk of breakage, while minimizing weight and component count, thus improving the suspension mechanism's reliability and ease of assembly.
Implementation Method 1
an insulating sheet which is made of a material having rubber elasticity and is attached to a lower surface of the wire by adhesive bonding
Implementation Method 2
prevent wear and damage by foreign matter
Data Source
AI summary
An end turn portion of a coil spring includes a first portion, a second portion, and a third portion. The first portion is always in contact with a spring seat irrespective of the magnitude of a load applied to the coil spring. The second portion contacts the spring seat when the load applied to the coil spring is large, and is separated from the spring seat when the load is small. The third portion is always separated from the spring seat irrespective of the magnitude of the load. An insulating sheet made of a material having rubber elasticity is attached to a lower surface of a wire at the end turn portion by means of adhesive bonding. The insulating sheet is provided on a lower surface of a region including at least the second portion.