Conductive Particle Sensor Layout for Compact Oil Pan Detection

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Solution Overview

Problem

Existing sensors for detecting conductive particles in lubricating oil are large in size and cannot be accommodated in small-volume oil pans, and their detection gaps cannot be reduced without compromising sensitivity, making them unsuitable for compact mechanical devices like smaller speed reducers.

Innovation Solution

The sensor design includes electrodes arranged in a circumferential or axial direction with insulating attracting portions along the outer peripheral surface, allowing for a reduced size without compromising detection sensitivity by attracting conductive particles to cause a short circuit between electrodes, thereby changing electrical resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electrodes are arranged next to each other in the circumferential direction to detect metal powder, then detection sensitivity is improved, but sensor size increases making it incompatible with small-volume oil pans

Engineering Contradiction:
Improvedetection sensitivityVSAvoidsensor size
Core Design Contradiction:
Measurement precisionVSVolume of moving object

Solution Approach 1:

The invention transitions from a conventional radial arrangement of electrodes to an axial arrangement where electrodes extend in the axial direction rather than the radial direction. This dimensional change allows the sensor to maintain detection sensitivity while reducing the radial size, enabling accommodation in small-volume oil pans.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The sensor is divided into multiple electrode pairs arranged axially, with each pair contributing to detection sensitivity. By segmenting the detection function across multiple axial positions, the sensor achieves high sensitivity without requiring large radial dimensions.

Inventive Principle:
Principle #1Segmentation

2Volume of moving object

If the gap between electrodes is reduced to minimize sensor size, then sensor compactness is improved, but initial abrasion powder causes erroneous operation

Engineering Contradiction:
Improvesensor sizeVSAvoidoperational reliability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The sensor includes a preliminary detection phase where initial abrasion powder is detected and accounted for before normal operation begins. This preliminary action allows the system to distinguish between initial wear particles and particles indicating actual failure, preventing erroneous operations while maintaining compact dimensions.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The sensor incorporates feedback mechanisms that monitor the detection signal over time and compare it against threshold values. This feedback allows the system to adapt to initial abrasion conditions and maintain reliable operation with reduced gap sizes by dynamically adjusting detection criteria.

Inventive Principle:
Principle #23Feedback

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 sensor achieves a compact size while maintaining high operational reliability and sensitivity, enabling accurate failure prediction in mechanical devices by detecting conductive particles in lubricating oil.

Implementation Method 1

an attracting portion arranged in the gap, wherein the attracting portion has an outer peripheral surface made of an insulating material, and conductive particles are attracted to the outer peripheral surface of the attracting portion

Methodology Applied
Scientific EffectMagnetic attraction: Magnetism

Implementation Method 2

a short circuit is caused in the circumferential direction between the first electrode and the second electrode, resulting in a change in electrical resistance between the first electrode and the second electrode

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3839504B1sensor
Publication Date: 2026.03.04 NABTESCO CORP
  • EP3839504B1 patent drawingFigure 1
  • EP3839504B1 patent drawingFigure 2~3
  • EP3839504B1 patent drawingFigure 4~6B

AI summary

A sensor includes a first electrode, a second electrode arranged relative to the first electrode with a gap being provided therebetween, a sensor body having the first and second electrodes arranged therein, and a catching portion arranged in the gap and having an outer peripheral surface made of an insulating material Electric connection is established along the outer peripheral surface via conductive particles gathering to the catching portion.