Diesel Particulate Filter Ash Load Correction

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Solution Overview

Problem

In diesel particulate filter exhaust gas aftertreatment systems, the influence of ash on differential pressure is not accurately accounted for in passive regeneration methods, leading to premature initiation of thermomanagement measures and unnecessary fuel consumption.

Innovation Solution

A method and device that measure and correct differential pressure by determining a lower differential pressure at a defined exhaust gas volumetric flow rate, assigning a correction factor to account for ash load, thereby optimizing regeneration timing and reducing unnecessary thermomanagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a predetermined reference value for differential pressure is used to initiate regeneration, then the regeneration process can be triggered based on simple measurement, but the ash load causes premature initiation of thermomanagement measures

Engineering Contradiction:

Improveregeneration initiation simplicityVSAvoidregeneration timing accuracy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent applies preliminary action by determining a correction factor for ash load before using it to adjust the differential pressure reference value. The ash load correction factor is calculated in advance based on operating parameters, and then this pre-calculated factor is used to modify the regeneration trigger threshold, preventing premature initiation while maintaining simple operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by continuously monitoring engine operating parameters (temperature, load, duration) and using this information to dynamically adjust the ash load correction factor. This feedback mechanism ensures the correction factor remains accurate over time, maintaining reliable regeneration timing despite varying operating conditions

Inventive Principle:

Principle #23Feedback

2Reliability

If thermomanagement measures are initiated frequently to ensure soot removal, then complete soot burnoff is achieved, but unnecessary fuel consumption increases

Engineering Contradiction:

Improvesoot removal completenessVSAvoidfuel consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces the mechanical/physical approach of frequent high-temperature thermomanagement with a computational method. By using mathematical models to calculate ash load correction factors and adjust the differential pressure reference, the system avoids unnecessary thermomanagement events, reducing fuel consumption while maintaining reliable soot removal when actually needed

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the differential pressure reference value is lowered to account for ash load, then premature regeneration is prevented, but the complexity of determining the corrected reference value increases

Engineering Contradiction:

Improveregeneration timing accuracyVSAvoidcorrection factor determination complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the differential pressure reference value based on calculated ash load correction factors. Instead of changing the physical structure or adding complex measurement systems, the solution changes the operational parameter (reference value) using computations based on readily available engine parameters, maintaining simplicity while improving accuracy

Inventive Principle:

Principle #35Parameter changes

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 approach provides a reliable and simple method to determine corrected differential pressure, preventing excessive thermomanagement and fuel consumption by accurately assessing soot load and ash influence, ensuring regeneration occurs only when necessary.

Implementation Method 1

diesel particulate filters can comprise a fine-pored structure—e.g., a ceramic structure or, as described in US 2007-151,231 A, a fine-pored woven steel structure—on the walls of which the soot particles are deposited

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Implementation Method 2

the soot particles are burned off at predetermined time intervals and/or after a predefinable trigger signal

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 3

the exhaust gas temperatures of the engine are sufficient under normal operating conditions to ensure the continuous removal of soot from the diesel particulate filter

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS9890684B2Method of operating an exhaust gas aftertreatment

Publication Date: 2018.02.13 ROLLS ROYCE SOLUTIONS GMBH

AI summary

A method and a device for operating an exhaust gas aftertreatment, wherein a diesel particulate filter is regenerated during the operation, in particular passively regenerated, wherein a corrected differential pressure is calculated from a current differential pressure across the diesel particulate filter at a current exhaust gas volumetric flow rate and with a current correction factor. The current correction factor is determined by determining a lower differential pressure in a predetermined time interval at a defined exhaust gas volumetric flow rate, in particular in a specified exhaust gas volumetric flow rate interval around the defined exhaust gas volumetric flow rate, and comparing the lower differential pressure with a specified current reference value and, depending thereon, calculating a new correction factor or retaining the previous correction factor as the current correction factor.