Electric Field Mill Conductive Grease Shaft Grounding

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Solution Overview

Problem

Current Electric Field Mills (EFMs) face issues with durability and high power consumption due to frictional sliding contacts and analog demodulation, limiting their operational time and ability to measure high-frequency electric field changes.

Innovation Solution

The design incorporates a conductive grease shaft grounding mechanism for reduced friction, an electronically commutated motor for efficiency, and digital signal processing to minimize power usage, allowing for faster shaft rotation and higher-frequency measurements, along with remote wireless connectivity for data management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If frictional sliding contacts (carbon slugs, brushes, slip rings) are used to ground the rotor, then high-speed rotation is enabled, but periodic maintenance is required due to wear and power consumption increases

Engineering Contradiction:

Improverotation speedVSAvoidoperational duration without maintenance

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent replaces frictional sliding contacts with magnetic coupling between the rotor and stator. The rotor contains permanent magnets that magnetically couple with corresponding magnets in the stator, transmitting rotational motion without physical contact. This eliminates wear from friction while maintaining high-speed rotation capability, resolving the contradiction between speed and reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces magnetic fields as an intermediary between the rotor and stator to transmit rotational motion. The magnetic coupling acts as a non-contact mediator that transfers torque and rotational speed without requiring direct mechanical contact, thereby eliminating wear and the need for periodic maintenance while preserving high-speed operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If frictional sliding contacts are used to ground the rotor, then high-speed rotation is enabled, but mechanical resistance increases and power consumption increases

Engineering Contradiction:

Improverotation speedVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The patent replaces frictional sliding contacts with magnetic coupling to transmit rotational motion. By eliminating direct mechanical contact, the system removes the mechanical resistance and associated power losses from friction, thereby reducing power consumption while maintaining high-speed rotation capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Difficulty of detecting and measuring

If analog low pass filter demodulation is used, then signal demodulation is achieved, but detectable electric field frequency is reduced to 1 Hz or lower

Engineering Contradiction:

Improvesignal demodulationVSAvoiddetectable frequency

Core Design Contradiction:

Difficulty of detecting and measuringVSSpeed

Solution Approach 1:

The patent replaces analog low pass filter demodulation with digital signal processing. The system captures the raw modulated signal and uses digital algorithms to demodulate and extract the electric field information. This digital approach removes the frequency-limiting constraints of analog filtering, enabling accurate measurement of high-frequency electric field variations while maintaining effective signal demodulation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Difficulty of detecting and measuring

If analog circuitry is used for demodulation and amplitude extraction, then signal processing is achieved, but power consumption increases

Engineering Contradiction:

Improvesignal processingVSAvoidpower consumption

Core Design Contradiction:

Difficulty of detecting and measuringVSUse of energy by moving object

Solution Approach 1:

The patent replaces power-consuming analog circuitry with digital signal processing implemented in software or firmware. The microcontroller or processor performs demodulation, amplitude extraction, and other signal processing functions digitally, significantly reducing power consumption compared to dedicated analog circuits while maintaining or improving processing capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 results in a more durable, low-power EFM capable of measuring higher-frequency electric field changes with longer operational times and reduced power consumption, enabling more accurate and efficient data collection in distributed arrays.

Implementation Method 1

a bearing 116 attached to the housing and packed with electrically conductive grease 156. The bearing and conductive grease provide a low-impedance path to ground for the shaft and rotor

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The rotor having spaced-apart blades configured to alternately block and unblock sets of the sensor plates from sensing the electric field... the plates are alternately exposed and shielded three times for every rotation of the motor

Methodology Applied

Scientific EffectElectrostatic induction: Electrostatic Induction

Data Source

PatentUS11362604B2Compact, low-cost electric field mill

Publication Date: 2022.06.14 THE REGENTS OF THE UNIVERSITY OF COLORADO

AI summary

An electric field mill (EFM) incorporates a novel rotor and shaft grounding mechanism providing a low-impedance path to ground via a bearing packed with electrically conductive grease. A removable bearing washer allows for servicing. The EFM includes a data processing scheme built around a peak detection algorithm and moving much of the signal processing to digital processing. A GPS disciplined sampling clock and cellular connectivity allow for use and maintenance of arrays of widely scattered EFMs.