Connector Assembly ESD Protection via Ferrite Block

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Solution Overview

Problem

Passive motor-vehicle safety devices, such as airbags and safety belt pre-tensioners, can be inadvertently triggered by electrostatic discharges during connector coupling, leading to potential accidents due to unfiltered electrical signals and accumulated electric charges.

Innovation Solution

A connector system featuring a ferrite block and a third ground contact, combined with elastic strips and conductive metal contacts, effectively directs potential electric charges generated by electrostatic effects to ground, preventing squib activation during discharges by ensuring electrical continuity and preventing charge accumulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a ferrite block is used to filter electromagnetic interference, then electromagnetic signals are protected, but electrostatic discharges can still accumulate and trigger the squib

Engineering Contradiction:

Improveelectromagnetic interferenceVSAvoidsquib triggering reliability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent introduces a third contact as an intermediary ground path that is electrically connected to both the ferrite block and the squib body. This mediator provides a controlled discharge route for electrostatic charges, allowing them to be safely diverted to ground through the ferrite block without triggering the squib, thus resolving the contradiction between electromagnetic filtering and discharge protection

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful electrostatic discharge into a beneficial controlled current path by providing a dedicated ground connection through the third contact. The discharge energy is redirected through the ferrite block to ground, transforming the potentially dangerous uncontrolled discharge into a safe, filtered current path that protects rather than triggers the squib

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Ease of operation

If the airbag connector is coupled to the squib connector, then the safety device becomes operational, but electrostatic charge accumulation may occur during coupling

Engineering Contradiction:

Improveconnector couplingVSAvoidelectrostatic discharge

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent implements preliminary grounding action by establishing the third contact ground path before the actual signal contacts engage during connector coupling. This preliminary ground connection is made through the ferrite block, which provides a low-impedance path for electrostatic charges to discharge to ground before the main electrical connections are established, preventing charge accumulation during the coupling process

Inventive Principle:

Principle #10Preliminary action

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 solution effectively neutralizes electrostatic discharges, preventing untimely triggering of safety devices by ensuring that electric charges are safely dissipated, thereby enhancing the reliability and safety of passive motor-vehicle safety systems.

Implementation Method 1

electromagnetic interference is generated in frequency ranges that are generally well filtered by ferrites placed in an airbag connector connected to the electrical wires

Methodology Applied

Scientific EffectElectromagnetic interference filtering: Absorption (EM radiation)

Implementation Method 2

potential electric charge generated, for example, via electrostatic effects in the wires connecting the control device to the airbag connector may be transmitted to the squib body, which itself is connected to ground, by way of the ground contact of the squib, of the third contact and of the ferrite block

Methodology Applied

Scientific EffectElectrostatic discharge: Electrostatic Discharge

Implementation Method 3

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3790123A1Connection assembly for a passive safety device and that is protected against electrostatic discharges

Publication Date: 2021.03.10 APTIV TECHNOLOGIES AG

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AI summary

Squib-connection assembly for a motor-vehicle safety device. This connection assembly comprises a squib connector and an airbag connector (3). The airbag connector (3) comprises a casing (8) in which are housed a ferrite block (11), two female contacts (12) that are each respectively electrically connected to one male contact of the squib connector, and at least one third contact (20). The ferrite block (11) makes contact with at least one of the two female contacts (12) of the airbag connector (3). The third contact (20) makes contact, on the one hand, with the ferrite block (11) and, on the other hand, with a ground contact that is in electrical continuity with the ground of the vehicle.