Spring Zone Contact Element for Thermal Stress Relief

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Solution Overview

Problem

Actuating devices in vehicle applications, such as those in internal combustion engines, face challenges with thermally induced stresses affecting the electrical contact between circuit boards and metal structures, leading to mechanical stress and reduced durability due to thermal expansion.

Innovation Solution

A circuit board with a contact element featuring a wavy or spirally bent spring zone that absorbs relative movements between the circuit board and metal structure, reducing mechanical stress on electrical contacts and enhancing thermal stability by allowing elastic deformation without plastic deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a rigid electrical connection is used between the circuit board and metal structure, then electrical contact is established, but thermal expansion causes mechanical stress and reduces durability

Engineering Contradiction:
Improvedurability of electrical contactVSAvoidmechanical stress on electrical contacts
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The contact element changes its physical state by incorporating a spring zone that can elastically deform, transitioning from a rigid connection to a flexible one that can accommodate thermal expansion and contraction without generating excessive mechanical stress

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The contact element is designed with a spring zone that can dynamically adapt its shape through elastic deformation, allowing it to absorb relative movements between the circuit board and metal structure caused by thermal expansion while maintaining continuous electrical contact

Inventive Principle:
Principle #15Dynamics

2Reliability

If the circuit board and metal structure are directly connected, then electrical contact is achieved, but thermal expansion leads to plastic deformation and contact failure

Engineering Contradiction:
Improveelectrical contact stabilityVSAvoidresistance to plastic deformation
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The spring zone is designed in advance to absorb and cushion the thermal expansion forces before they can cause plastic deformation or contact failure, providing a buffer that protects the electrical connection throughout the entire temperature cycle

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Stability of the object's composition

If a flexible spring zone is introduced to absorb thermal movements, then thermal stability is improved, but device complexity increases

Engineering Contradiction:
Improvethermal stability of electrical connectionVSAvoidstructure of contact element
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The contact element merges multiple functions into a single integrated component: electrical conduction, mechanical connection, and thermal movement absorption are all achieved through one element rather than requiring separate components for each function

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The spring zone is designed as a flexible, thin-walled structure that can elastically deform to accommodate thermal expansion while maintaining electrical conductivity, providing a simple yet effective solution that doesn't require complex mechanisms

Inventive Principle:
Principle #30Flexible shells and thin films

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 solution significantly improves the durability of the electrical contact between the circuit board and metal structure, enabling the actuating device to withstand various load and temperature changes without incurring high mechanical loads, thus enhancing the overall stability and longevity of the actuating device.

Implementation Method 1

This spring zone is bent, in particular in a wave-like and/or spiral shape, and absorbs the relative movements between the circuit board contact zone and the metal structure contact zone in a spring-like manner

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

Since the respective spring zone is only stressed within its elastic range by the spring-elastic deformations, all deformations that typically occur are reversible

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2683035B1Circuit board, actuating device, and method of manufacturing
Publication Date: 2019.09.04 MAHLE INT GMBH
  • EP2683035B1 patent drawingFigure 1
  • EP2683035B1 patent drawingFigure 2~3
  • EP2683035B1 patent drawingFigure 4~5

AI summary

The device has a position sensor mechanism including a printed circuit board (PCB) (18), which carries a position sensor and is electrically contacted with a metal structure (20) i.e. punching scrap, by a contact element (24). The metal structure is partially embedded in plastic of a housing. The contact element includes a corrugated, curved spring zone (27) between a PCB contact zone (25) and a metal structure contact zone (26). The spring zone resiliently receives relative movements between the PCB and metal structure contact zones. An independent claim is also included for a method for manufacturing a PCB for a control device.