Ground Connection Sharp Edges Penetrate Insulating Coating

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Solution Overview

Problem

Existing electric fuel pumps face challenges in achieving low-resistance or low-impedance contact-making due to the presence of an electrically insulating anticorrosion coating on the pump housing, which hinders electromagnetic compatibility.

Innovation Solution

The first contact portion of the ground connection is designed with sharp edges and protrusions to penetrate the insulating layer, featuring tabs with tooth-like or sawtooth edges for multiple contact points, ensuring a low-impedance connection by directly contacting the pump housing material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the pump housing is provided with an electrically insulating anticorrosion coating, then corrosion protection is improved, but electrical contact resistance increases

Engineering Contradiction:

Improvecorrosion protectionVSAvoidelectrical contact resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The contact portion is given a different surface property (sharp edges) than the rest of the terminal cap, allowing it to locally penetrate the insulating coating while the rest of the housing maintains its protective coating. This creates localized electrical contact through the coating without compromising the overall corrosion protection.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of trying to make the insulating coating conductive or removing it, the invention inverts the approach by having the contact portion actively penetrate through the coating to reach the conductive housing beneath. The sharp-edged contact portion essentially reverses the insulation function locally to achieve electrical contact.

Inventive Principle:

Principle #13The other way round (Inversion)

2Stability of the object's composition

If the first contact portion is pressed against the pump housing with contact pressure, then contact stability is improved, but electrical contact resistance remains high due to the insulating coating

Engineering Contradiction:

Improvecontact stabilityVSAvoidelectrical contact resistance

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The invention changes the geometric parameter of the contact portion by providing sharp edges, which fundamentally alters how contact is made. Instead of broad surface contact that slides on the coating, the sharp edges concentrate force to penetrate the coating and establish conductive contact with the housing.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the first contact portion is made with sharp edges to penetrate the insulating layer, then electrical contact resistance decreases, but manufacturing complexity increases

Engineering Contradiction:

Improveelectrical contact resistanceVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Only the contact portion requires sharp edges, not the entire terminal cap. This localized requirement minimizes the impact on manufacturing complexity while achieving the desired electrical contact performance through the insulating coating.

Inventive Principle:

Principle #3Local quality

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 achieves reliable and low-impedance ground contact-making, meeting electromagnetic compatibility requirements while maintaining economic production costs.

Implementation Method 1

the first contact portion is in sharp-edged fashion such that upon insertion into the pump housing, it locally penetrates an electrically insulating layer embodied on the pump housing

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Data Source

PatentUS7927113B2Pumping assembly with a grounding connection having sharp edges to bite into an insulating layer of the pump housing

Publication Date: 2011.04.19 ROBERT BOSCH GMBH

AI summary

Electric fuel pumps are already known with a pump housing and a ground terminal, which is provided on a terminal cover, for making contact with an electrical ground, in which the pump housing and the ground terminal are connected to one another via a ground connection, which has a first contact section for making contact with the pump housing and a second contact section for making contact with the ground terminal. The first contact section is provided on the outer circumference of a terminal cover and, after installation, is pressed with a contact pressure against the inner face of the pump housing. Since the inner face of the pump housing has increasingly been provided with an electrically insulating anticorrosion coating, however, when the terminal cover is pressed into the pump housing, touching contact with the pump housing does take place which is usually also electrically conductive, but as a result of the electrically insulating coating has a high electrical resistance. In the case of the conveying assembly according to the invention, the impedance of the contact-making is reduced. The invention provides that the first contact section is designed to have sharp edges in such a way that, when it is pushed into the pump housing, it passes locally through an electrically insulating layer formed on the pump housing.