Twisted Leaf Spring Contact With Symmetrical Stiffness

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Solution Overview

Problem

Existing spring contacts for sliding contacts, particularly in motors and dynamos, face challenges with precise installation tolerances and high costs due to the use of precious metals, which limits their mechanical properties and increases construction complexity.

Innovation Solution

A spring contact design featuring a conductive, non-precious metal spring carrier with symmetrical stiffness, where the contact pieces are made of noble metals or alloys, allowing for easier installation and reduced material costs by decoupling the elastic and contact-making properties between the spring carrier and contact pieces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If precious metals or precious metal alloys are used for the entire spring contact to prevent passivation and ensure continuous conductive connection, then reliability is improved, but cost increases and mechanical properties deteriorate

Engineering Contradiction:

Improvecontinuous conductive connectionVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The spring contact is divided into two functional segments: the spring carrier (providing mechanical elasticity) and the contact piece (providing electrical conductivity and corrosion resistance). This segmentation allows each component to be optimized independently, using non-precious metal for the spring carrier and precious metal only for the contact piece, thereby reducing overall cost while maintaining reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Precious metal material is applied locally only to the contact piece where electrical conductivity and corrosion resistance are critical, rather than throughout the entire spring contact. This localized application of premium material reduces cost while ensuring the specific functional requirements are met at the contact interface.

Inventive Principle:

Principle #3Local quality

2Reliability

If precious metals or precious metal alloys are used for the entire spring contact to prevent passivation, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvecontinuous conductive connectionVSAvoidconstruction complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The precious metal is extracted from the entire spring contact structure and concentrated only in the contact piece where it is most needed. This extraction simplifies the overall construction by eliminating the need for precious metal throughout the spring carrier, reducing material complexity and manufacturing steps.

Inventive Principle:

Principle #2Taking out (Extraction)

3Force

If leaf springs are installed in exact position to ensure sufficiently strong contact, then contact force is improved, but installation tolerance decreases

Engineering Contradiction:

Improvecontact forceVSAvoidinstallation tolerance

Core Design Contradiction:

ForceVSManufacturing precision

Solution Approach 1:

The spring carrier is designed with inherent elasticity and symmetrical regional rigidity, allowing it to dynamically adapt to installation variations. The symmetrical rigidity distribution enables the spring to self-adjust and maintain adequate contact force even when installation position deviates from the ideal, thereby increasing installation tolerance while preserving sufficient contact force.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The spring carrier's rigidity parameters are specifically engineered with symmetrical regional distribution, creating a stiffness profile that compensates for installation position variations. This parameter optimization allows the spring to maintain consistent contact force across a wider range of installation positions.

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

This design enables greater installation tolerance and cost-effectiveness by using less expensive materials, allowing for the use of previously unsuitable precious metal alloys with favorable wear resistance, ensuring a long-lasting, highly conductive contact.

Implementation Method 1

the spring carrier being a twisted leaf spring lying in the plane perpendicular to the torsion axis has a symmetric stiffness relative to at least a portion of the twisted leaf spring

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP2755287B1Contact piece containing precious metal on a spring support with a rotationally symmetrical bending moment

Publication Date: 2015.07.29 HERAEUS DEUTSCHLAND GMBH & CO KG

Figure 1~2
Figure 3~4

AI summary

The invention relates to a spring contact for a sliding contact with a connection area (24) and at least one contact area comprising an extended spring element and a precious metal, wherein the spring contact comprises a conductive spring carrier (1, 11, 21, 31) and at least one contact piece (2, 12, 22, 32), wherein the spring carrier (1, 11, 21, 31) has a substantially symmetrical, region-specific stiffness in a plane perpendicular to the extended extent of the spring carrier (1, 11, 21, 31) and is made of a conductive, substantially precious-metal-free material. According to the invention, the spring carrier (1, 11, 21, 31) is a twisted leaf spring which has a symmetrical stiffness in the plane perpendicular to the axis of torsion with respect to at least one region of the twisted leaf spring.