Exhaust Aftertreatment Pressure Line Defect Detection

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Solution Overview

Problem

Existing methods for monitoring exhaust aftertreatment systems, particularly particulate filters, are unreliable in detecting defects in pressure lines due to issues like leaks or damage, which affect the accuracy of pressure difference measurements and filter control.

Innovation Solution

A method that records a second pressure difference between a sampling point and the environment to detect defects in pressure lines, using criteria such as a pressure difference close to zero, lack of change in pressure difference with operating state changes, or an abnormal ratio between first and second pressure differences, allowing for reliable and distortion-free diagnostics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pressure difference sensors are used to monitor particulate filters, then the load state of the particle filter can be concluded and regeneration can be controlled, but the measurement is affected by defects in the pressure lines such as deterioration, holes, or cracks

Engineering Contradiction:

Improvereliability of particulate filter monitoringVSAvoidprecision of pressure difference measurement

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces a second pressure difference measurement as an intermediary diagnostic tool. This additional measurement serves as a mediator to detect pressure line defects without interfering with the primary first pressure difference measurement used for particulate filter monitoring. The second measurement acts as a separate diagnostic channel that identifies defects in the pressure lines, allowing the system to distinguish between actual filter load changes and measurement errors caused by pressure line deterioration.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If vibration amplitude methods are used to detect pressure line defects, then some deterioration can be detected, but the method is not reliable enough for accurate defect detection

Engineering Contradiction:

Improveprecision of defect detectionVSAvoidreliability of defect detection

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the mechanical vibration-based detection method with a pressure-based diagnostic approach. Instead of relying on mechanical vibrations to detect pressure line defects, the system uses pressure difference measurements to identify defects. This substitution provides more reliable and accurate defect detection because pressure measurements directly reflect the functional state of the pressure lines rather than indirect mechanical vibrations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a second pressure difference measurement is added to detect pressure line defects, then defect detection reliability improves, but the device complexity increases

Engineering Contradiction:

Improvereliability of pressure line defect detectionVSAvoidcomplexity of monitoring system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies multi-functionality by enabling the pressure difference sensor to serve dual purposes: the first pressure difference measurement monitors particulate filter load state, while the second pressure difference measurement detects pressure line defects. This universal approach allows a single sensor system to perform multiple diagnostic functions, improving reliability without requiring completely separate monitoring systems for each function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the defect detection function with the existing particulate filter monitoring system. Instead of creating a separate defect detection system, the second pressure difference measurement is integrated into the existing monitoring infrastructure. This merging approach allows the system to perform both filter monitoring and defect detection using a unified diagnostic framework, reducing overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

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

Enables reliable detection of defects in pressure lines, particularly those downstream of the particulate filter, improving the accuracy of particulate filter load state monitoring and regeneration control, especially during specific engine operating conditions.

Implementation Method 1

Differential pressure sensors are used to monitor these exhaust aftertreatment systems, especially the particulate filters. Such a pressure difference sensor determines a pressure difference between a first sampling point and a second sampling point.

Methodology Applied

Scientific EffectPressure difference measurement: Pressure Gradient

Implementation Method 2

A second pressure difference between the second sampling point and the environment is recorded to monitor the pressure line. A defect, in particular of the pressure line, is detected based on said second pressure difference.

Methodology Applied

Scientific EffectPressure difference measurement: Pressure Gradient

Data Source

PatentUS11286836B2Method for monitoring an exhaust aftertreatment system of a combustion engine

Publication Date: 2022.03.29 ROBERT BOSCH GMBH

AI summary

A method is described for monitoring an exhaust aftertreatment system of a combustion engine, with a pressure difference sensor that captures a first pressure difference between a first sampling point and a second sampling point. A second pressure difference between the second sampling point and the environment is captured. A defect is detected based on the second pressure difference.