Shaft Grounding Ring with Deformable Discharge Tabs

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Solution Overview

Problem

Existing shaft grounding solutions, such as those with conductive filaments or wave grounding rings, face challenges in efficiently dissipating frequency-variable interference voltages from electric motors, leading to bearing damage and EMC issues, and are often complex and costly to produce, with difficulties in adapting to changes in shaft rotation direction.

Innovation Solution

A shaft grounding ring with an elastically deformable discharge body featuring tab-shaped sections of varying lengths, which increase the contact surface area and ensure uniform voltage dissipation, allowing for better long-term discharge of induced voltages and improved durability, while being cost-effective and simple to manufacture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conductive filaments are used in shaft grounding rings, then electrical charge dissipation is achieved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvecharge dissipationVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The discharge body is segmented into multiple tab-shaped sections of different lengths that project radially inward. These sections are arranged circumferentially to create multiple contact tracks on the shaft, replacing the filament structure with a simplified monolithic design that maintains charge dissipation functionality while reducing manufacturing complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention extracts the essential function of charge dissipation from the complex filament structure and implements it through a simplified disc-shaped discharge body with tab sections. The core functionality is preserved while eliminating the need for separate filament components and their associated complex assembly processes

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If conductive filaments are used in shaft grounding rings, then charge dissipation is achieved, but adaptability to rotation direction changes is reduced

Engineering Contradiction:
Improvecharge dissipationVSAvoidrotation direction adaptability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The tab sections are designed to be elastically deformable, allowing them to dynamically adapt to changes in shaft rotation direction. The elastic properties enable the sections to flex and maintain contact with the shaft surface regardless of rotation direction, providing inherent adaptability without mechanical adjustment

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If single-length discharge sections are used, then manufacturing is simple, but contact area and voltage dissipation efficiency are reduced

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidvoltage dissipation efficiency
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The discharge body features tab sections with locally varied lengths, where each section's length is optimized for its specific position and function. This local quality variation increases the total contact area and creates multiple contact tracks on the shaft, enhancing voltage dissipation efficiency while remaining manufacturable through standard forming processes

Inventive Principle:
Principle #3Local quality

4Reliability

If sections of different lengths are evenly distributed, then uniform voltage dissipation is achieved, but manufacturing precision requirements increase

Engineering Contradiction:
Improveuniform voltage dissipationVSAvoidsection distribution precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The tab sections are designed with asymmetric length variations, where sections alternate between longer and shorter lengths in a predetermined pattern. This asymmetric design creates uniform voltage dissipation across the discharge body by ensuring even distribution of contact pressure and current density, while the patterned arrangement simplifies manufacturing by providing clear positioning guidelines

Inventive Principle:
Principle #4Asymmetry

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 provides enhanced voltage discharge efficiency, reduced abrasion, and longer component durability by increasing the contact surface area and allowing for uniform voltage dissipation, while being cost-effective and adaptable to changes in shaft rotation direction.

Implementation Method 1

A shaft grounding ring (1) with an elastically deformable discharge body (10) featuring tab-shaped sections (16, 17) of varying lengths

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The shaft grounding ring can be used to dissipate electrical charges or voltages from the motor shaft (1)

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3468013B1Shaft grounding ring and discharge body for a shaft grounding ring
Publication Date: 2021.01.13 KACO GMBH & CO KG
  • EP3468013B1 patent drawingFigure 1
  • EP3468013B1 patent drawingFigure 2
  • EP3468013B1 patent drawingFigure 3

AI summary

The shaft grounding ring serves to dissipate induced voltages or electrical charges from a first machine element to a second machine element. The shaft grounding ring has a housing made of electrically conductive material, which is electrically connected to one machine element and is in electrically conductive contact with at least one annular discharge body. It consists at least partially of an electrically conductive material and is in electrically conductive contact with the other machine element. The discharge body has an annular section (14) from which elastically deformable, tab-shaped sections (16, 17) of different lengths project. In the installed position of the shaft grounding ring, these differently sized sections (16, 17) form different contact patterns on the shaft. This significantly increases the contact area between the discharge body and the shaft, resulting in particularly good dissipation of the voltages or charges.Cargo is guaranteed.