Complex Wave Spring for Constant Contact Force

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Solution Overview

Problem

Existing spring devices fail to provide a consistent contact force over varying distances and tolerances in electrical and thermal connections, risking damage to delicate components or inadequate coupling, especially in high current applications, and often require costly tools for insertion.

Innovation Solution

A complex wave spring with multiple wave portions arranged in a checker-board pattern, made of electrically conductive material, which maintains a relatively constant spring force over a wide range of compression distances by deforming to establish additional contact points, minimizing pressure and reducing the risk of single-point contacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional spring is used to provide contact force between electrical surfaces, then electrical contact is achieved, but the spring force varies greatly with distance causing single-point contact and high electrical contact resistance

Engineering Contradiction:
Improveelectrical contact stabilityVSAvoidspring force consistency
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The spring is divided into multiple wave portions (first wave portion, second wave portion, third wave portion) arranged in a checker-board pattern. Each wave portion independently contacts the electrical surfaces, distributing the contact force across multiple points rather than relying on a single contact point, thereby maintaining stable electrical contact despite variations in spring force with distance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spring transitions from a conventional single-layer structure to a multi-layer three-dimensional configuration with wave portions arranged in a checker-board pattern. This spatial arrangement ensures that as the spring compresses, multiple wave portions remain in contact with the electrical surfaces simultaneously, maintaining consistent contact force distribution across varying compression distances.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If high spring force is used to ensure adequate thermal and electrical contact, then contact resistance is reduced, but the force may damage delicate components such as integrated circuit dies

Engineering Contradiction:
Improvecontact resistanceVSAvoidcomponent damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The total contact force is segmented across multiple wave portions that contact the electrical surfaces at different locations. This distributes the pressure load, preventing concentration of force at any single point and reducing the risk of damaging delicate components while still achieving adequate overall contact force for low resistance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each wave portion is designed with specific geometric characteristics (amplitude, wavelength, curvature) that allow it to contact the electrical surfaces with optimized local pressure distribution. The checker-board arrangement ensures that adjacent wave portions have complementary contact characteristics, creating a balanced overall force distribution that protects components while maintaining electrical contact quality.

Inventive Principle:
Principle #3Local quality

3Reliability

If multiple fasteners or clamps are used to secure electrical connections, then connection stability is improved, but device complexity and assembly cost increase

Engineering Contradiction:
Improveconnection stabilityVSAvoidnumber of fasteners
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The spring combines multiple functions into a single component: it provides mechanical compression force, ensures electrical contact, and maintains thermal coupling. The multi-wave portion structure with checker-board arrangement integrates the functions of multiple fasteners and clamps into one element, eliminating the need for separate fastening components while maintaining connection stability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The spring is designed as a universal component that simultaneously achieves mechanical fastening, electrical connection, and thermal management. The multiple wave portions can be configured to contact different electrical surfaces, making the single spring device capable of securing multiple electrical connections without requiring distinct fasteners for each contact point.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Force

If a spring with high insertion force is used, then adequate contact pressure is achieved, but costly tools and insertion aids are required

Engineering Contradiction:
Improvecontact pressureVSAvoidinsertion ease
Core Design Contradiction:
ForceVSEase of operation

Solution Approach 1:

The spring exhibits dynamic mechanical characteristics through its multi-wave portion structure. During insertion, the wave portions progressively deform and make contact with the electrical surfaces in a controlled sequence, distributing the insertion force over a longer distance and reducing peak insertion force requirements while still achieving adequate final contact pressure.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The spring's mechanical parameters (wave amplitude, wavelength, material properties) are optimized to provide progressive deformation characteristics. This allows the spring to transition from a low-force insertion state to a high-force contact state, achieving adequate contact pressure without requiring excessively high insertion forces that would necessitate costly specialized tools.

Inventive Principle:
Principle #35Parameter changes

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 complex wave spring ensures stable, low-resistance electrical and thermal contacts across varying distances, reducing the risk of damage to components and eliminating the need for multiple fasteners, while maintaining a consistent force suitable for high current applications without requiring costly tools.

Implementation Method 1

When the spring is sufficiently compressed between the surfaces, the first node region, the first upward undulation and the first downward undulation cooperatively deform to establish at least one additional point of contact with at least one of the surfaces

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The spring is formed of electrically conductive material suitable for electrically coupling electrical contact surfaces when the spring is in contact therebetween

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

mechanically force the contact surfaces together in order to make intimate electrical, thermal, and/or mechanical contact with one another

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2538106B1Complex wave spring
Publication Date: 2019.04.17 DELPHI TECH IP LTD
  • EP2538106B1 patent drawingFigure 1
  • EP2538106B1 patent drawingFigure 2
  • EP2538106B1 patent drawingFigure 3

AI summary

A complex wave spring (100, 200), or Beer spring, for electrically coupling opposed electrical contact surfaces (312) or generating a relatively constant force. The spring (100, 200) includes a first wave portion (116, 216) shaped to define a first upward undulation (118, 218) and a first downward undulation (120, 220), and a second wave portion (122, 222) fixedly arranged relative to the first wave portion (116, 216). The second wave portion (122, 222) is shaped to define a second upward undulation (124, 224) proximate to the first downward undulation (120, 220), and a second downward undulation (126, 226) proximate to the first upward undulation (118, 218). The spring (100, 200) may be formed of electrically conductive material suitable for electrically coupling electrical contact surfaces (312, 412) when the spring (100, 200) is in contact between the surfaces (312). The complex spring (100, 200) provides unusually constant spring (100, 200) forces over a relatively wide range of compression distances.