Pneumatic Tubular Sheath for Helical Spring Corrosion Protection
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Solution Overview
Problem
Current anti-corrosion methods for automobile suspension springs, such as paint application, are ineffective due to chipping and friction, leading to premature wear and the need for oversized springs, which increases mass and reduces efficiency.
Innovation Solution
A process involving pneumatically expanding a tubular plastic sheath to cover a wire spring, creating a double thickness of sheath that grips the wire, providing enhanced corrosion protection without the mass penalties of oversized springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If paint is applied to protect suspension springs against corrosion, then corrosion protection is provided, but the paint coating chips and wears away rapidly, especially at end turns in contact with spring bearing cups
Solution Approach 1:
The patent applies a flexible plastic tubular sheath covering the spring wire instead of rigid paint coating. This flexible covering conforms to the spring's geometry and movement, preventing chipping and wear that plagues paint applications, especially at critical end turn areas contacting bearing cups.
Solution Approach 2:
The invention combines the metal spring wire with a plastic tubular sheath covering to create a composite structure. This composite approach leverages the strength of metal and the corrosion resistance and flexibility of plastic, providing superior and more durable corrosion protection compared to paint alone.
2Reliability
If spring wire diameter is increased to avoid premature breakage due to poor corrosion protection, then corrosion resistance is improved, but the mass of the spring increases
Solution Approach 1:
The flexible plastic tubular sheath provides corrosion protection without requiring increased wire diameter. The sheath acts as a protective barrier that maintains the original spring dimensions and mass while preventing corrosion that would otherwise necessitate oversizing the spring wire.
3Reliability
If a tubular sheath is expanded pneumatically to cover the wire spring, then corrosion protection is enhanced, but the process complexity increases
Solution Approach 1:
The patent uses pneumatic expansion to apply the tubular sheath to the spring wire. Compressed air is introduced to expand the sheath radially outward, causing it to grip the wire securely. This pneumatic application method is simpler than mechanical fastening systems while providing reliable attachment.
Solution Approach 2:
The sheath's elastic memory allows it to self-grip the wire after pneumatic expansion. Once expanded and then released, the sheath naturally contracts and clamps onto the wire without requiring additional fastening mechanisms, simplifying the overall application process.
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 method allows for the use of smaller diameter wire springs with improved corrosion resistance, reducing mass and extending the lifespan of suspension springs by maintaining anti-corrosion protection effectively.
Implementation Method 1
Compressed air is then ejected through tube 16, which causes expansion of sheath 14 and its progressive reversal.
Implementation Method 2
After the compressed air supply has been cut off, the sheath, which is naturally elastic, resumes its initial dimensions and grips the wire.
Data Source
Figure 1~5
AI summary
The method involves covering a wire (11) of a helical spring using a tubular plastic sheath (14) by dilating the sheath pneumatically for progressing the sheath along the wire, where the covering of the wire is carried out after conformation of the spring. The sheath is closed at an end (18), and engaged on a compressed air ejection tube (16) till the closed end of the sheath is near an orifice of the tube.