Particulate Matter Sensor Housing for Exhaust Filter Failure Detection

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Solution Overview

Problem

Conventional exhaust aftertreatment systems face challenges in detecting catastrophic failures of particulate filters, such as cracks or breaks, which allow large particles to pass through, leading to increased particulate matter emissions and difficulty in monitoring filter condition.

Innovation Solution

A PM sensor assembly is positioned downstream of the particulate filter, with a housing configured to redirect exhaust gas flow so that only large particles greater than a predetermined size range impact and accumulate on the sensor, causing a change in an electrical parameter that indicates filter failure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a PM sensor is positioned downstream of the particulate filter to detect filter failure, then the ability to detect catastrophic failures is improved, but the sensor accumulates large particles that reduce its lifespan

Engineering Contradiction:

Improvefilter failure detection capabilityVSAvoidsensor lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The housing is segmented into different flow paths: a first flow path allows exhaust gas to bypass the PM sensor, while a second flow path directs only large particles (greater than Greenfield gap size) to impact and accumulate on the sensor surface. This segmentation enables the sensor to detect filter failures without accumulating excessive particle loads that would reduce its lifespan.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The housing creates a localized flow redirection zone where the exhaust gas flow is split: most gas flows through the first path bypassing the sensor, while a portion flows through the second path where large particles are directed to impact the sensor. This local flow modification allows selective particle accumulation only where needed for detection, preserving overall sensor longevity.

Inventive Principle:

Principle #3Local quality

2Duration of action of stationary object

If the housing redirects exhaust gas flow to direct only large particles to the PM sensor, then particle accumulation on the sensor is reduced extending its lifespan, but the device complexity increases

Engineering Contradiction:

Improvesensor lifespanVSAvoidhousing flow redirection structure

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The housing structure serves multiple functions simultaneously: it protects the PM sensor, redirects exhaust gas flow, separates particles by size, and provides a mounting structure for the sensor. By making the housing multi-functional, the design avoids adding separate components for each function, thereby limiting the increase in device complexity while achieving particle size-selective accumulation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If existing accumulation-type PM sensors are used to reduce manufacturing and maintenance costs, then the cost is reduced, but the sensor accumulates all particles including small ones that reduce its lifespan

Engineering Contradiction:

Improvemanufacturing and maintenance costVSAvoidsensor lifespan

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The housing acts as an intermediary component between the exhaust gas stream and the PM sensor. It pre-processes the gas flow by redirecting it to allow most exhaust gas and small particles to bypass the sensor, while only directing large particles to the sensor surface. This intermediary function protects the simple, cost-effective accumulation-type sensor from excessive particle accumulation that would otherwise reduce its lifespan.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution effectively detects particulate filter failures by measuring changes in electrical parameters, reducing particle accumulation on the sensor and extending its lifespan, while allowing for the use of existing accumulation-type sensors to reduce manufacturing and maintenance costs.

Implementation Method 1

large particles having a second size larger than the predetermined size range impact the PM sensor

Methodology Applied

Scientific EffectImpaction: Impact Force

Implementation Method 2

The accumulation causes a change in an electrical parameter of the PM sensor indicating a failure of the particulate filter

Methodology Applied

Scientific EffectElectrical parameter change: Electrical Resistance

Data Source

PatentUS10641154B2Particulate matter sensor with engineered particle size cut-point

Publication Date: 2020.05.05 CUMMINS EMISSION SOLUTIONS INC

AI summary

An aftertreatment system comprises a particulate filter configured to filter PM possessing a predetermined, least effective size range included in an exhaust gas flowing through the aftertreatment system. A PM sensor assembly is positioned downstream of the particulate filter and includes a housing having an inlet, an outlet, a sidewall and defines an internal volume. A PM sensor is positioned within the internal volume. The housing is configured to redirect a flow of exhaust gas entering the PM sensor assembly around the PM sensor so that small particles included in the exhaust gas flow having a first size within or smaller than the predetermined size range are directed around the particulate matter sensor. Large particles having a second size larger than the predetermined size range impact the PM sensor. A controller is communicatively coupled to the PM sensor.