Particulate Matter Sensor Water Drainage and Cracking Prevention

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Solution Overview

Problem

Particulate matter detection apparatuses face issues with water-induced cracking and contamination due to pollutants in exhaust gases, leading to detection errors and functional deterioration.

Innovation Solution

A particulate matter detection apparatus with a heater and temperature controllers to maintain the element portion within specific temperature ranges, preventing water-induced cracking and contamination by using thermophoresis and the Leidenfrost effect to repel water and pollutants.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the element portion is heated to a high temperature to repel water droplets, then water-induced cracking is prevented, but pollutants in the condensed water adhere to the element portion causing contamination

Engineering Contradiction:

Improveprevention of water-induced crackingVSAvoidpollutant contamination

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary water drainage by heating the element portion to a first temperature (100-200°C) before the main combustion process. This preliminary heating evaporates condensed water containing pollutants, preventing them from adhering to the element portion surface, and then the system proceeds to the combustion process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The heating process is divided into distinct periodic stages: a first heating period for water drainage at a controlled first temperature, followed by a second heating period for combustion at a higher second temperature. This periodic temperature control allows the system to achieve both water removal and pollutant prevention.

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If the element portion is heated to remove accumulated particulate matter by combustion, then detection accuracy is maintained, but water droplets covering the element portion cause cracking

Engineering Contradiction:

Improveparticulate matter detection accuracyVSAvoidelement portion structural integrity

Core Design Contradiction:

Measurement precisionVSStrength

Solution Approach 1:

Before performing combustion to remove accumulated particulate matter, the system preliminarily heats the element portion to evaporate water droplets. This preliminary water removal prevents thermal shock and structural cracking that would occur if combustion heating were applied directly to a water-covered element portion.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements a periodic heating cycle consisting of a water drainage phase at a lower temperature followed by a combustion phase at a higher temperature. This staged periodic heating allows safe removal of water first, then safe combustion of particulate matter without structural damage.

Inventive Principle:

Principle #19Periodic action

3Object-affected harmful factors

If the engine operation is stopped before particulate matter combustion, then water drainage can occur, but detection errors increase due to changes in PM state on the element portion

Engineering Contradiction:

Improvewater drainage completionVSAvoidparticulate matter detection accuracy

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The system performs preliminary water drainage heating before combustion, ensuring water is removed while the engine is still operating and PM state is stable. This preliminary action separates the water removal function from the combustion function, allowing both to be performed optimally without stopping engine operation.

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

Prevents water-induced cracking and contamination of the element portion, ensuring accurate particulate matter detection and extending the apparatus's durability by maintaining the element portion in a water-repellent temperature range after water drainage.

Implementation Method 1

a heater which heats the element portion

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

enables water adhered onto the element portion to be repelled

Methodology Applied

Scientific EffectThermophoresis: Thermophoresis

Implementation Method 3

enables water adhered onto the element portion to be repelled using the heater

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS10794811B2Particulate matter detection apparatus that mitigates water collection

Publication Date: 2020.10.06 DENSO CORP

AI summary

An apparatus which detects particulate matter is provided. This apparatus estimates a volume of water inside an exhaust passage using estimation sections. When an estimated volume of water is larger than a water drainage threshold, an element portion is heated using a heater by the first temperature range controller, in a temperature range which resists water-induced cracking independent of a volume of water droplets. If the estimated volume of water is less than a water drainage threshold, the water drainage determination section determines that the water drainage of the exhaust passage is completed. Additionally, if it is estimated that the water drainage is completed, the element portion is heated by a second temperature controller at temperature lower than a starting temperature of combustion of particulate matter and in order to repel water adhered onto the element portion in a water-repellent temperature range for a predetermined period.