SCR Urea Deposit Model Adaptation Using Ammonia Measurement

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Solution Overview

Problem

Existing urea deposit models in aftertreatment systems of vehicles are inaccurate, leading to improper triggering of urea deposit regeneration, which can cause clogging and inefficient fuel consumption.

Innovation Solution

A method and system for adapting a urea deposit build-up model by determining ammonia levels, heating the catalytic reduction device to sublime urea deposits, and calculating the amount of converted NOx to accurately estimate urea deposits, thereby adjusting the model to reflect the actual deposit levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a urea deposit model is used to estimate urea deposits in the aftertreatment system, then regeneration can be triggered to remove deposits, but the model accuracy is insufficient leading to improper regeneration triggering

Engineering Contradiction:

Improveregeneration triggering accuracyVSAvoidurea deposit estimation accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces the indirect mechanical/mathematical modeling approach with a direct chemical measurement approach. By heating the catalytic reduction device to sublime urea deposits and measuring the resulting ammonia concentration, the system directly quantifies actual urea deposit amounts rather than relying on model estimates, thereby resolving the contradiction between reliable regeneration triggering and precise deposit measurement.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If regeneration is triggered frequently to prevent urea deposit clogging, then the risk of clogging is reduced, but fuel consumption increases

Engineering Contradiction:

Improveclogging riskVSAvoidfuel consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent implements a feedback mechanism where the measured ammonia concentration from sublimed urea deposits is used to adapt and refine the urea deposit model. This creates a closed-loop system that continuously improves measurement accuracy, allowing regeneration to be triggered only when actually needed rather than on fixed schedules, thus reducing unnecessary fuel consumption while maintaining protection against clogging.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the operational parameters of the catalytic reduction device by heating it to specific temperatures above the sublimation point of urea deposits. This temperature parameter change enables the conversion of solid urea deposits into gaseous ammonia for measurement, providing an accurate basis for determining when regeneration is truly necessary and avoiding premature or unnecessary regeneration events that would waste fuel.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If the catalytic reduction device is heated to sublime urea deposits for accurate measurement, then urea deposit amount can be precisely determined, but energy is consumed during the measurement process

Engineering Contradiction:

Improveurea deposit measurement accuracyVSAvoidheating energy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies multi-functionality to the catalytic reduction device by using it for both its primary function of nitrogen oxide reduction and as a measurement chamber for quantifying urea deposits. The same heating mechanism used for thermal management and regeneration processes is utilized to sublime deposits for measurement purposes. This eliminates the need for separate measurement equipment and reduces overall energy consumption by consolidating functions within a single device.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 precise urea deposit regeneration only when needed, improving fuel efficiency and reducing the risk of clogging by accurately estimating and adapting the urea deposit model.

Implementation Method 1

heating the catalytic reduction device to above a threshold temperature to sublime urea deposits in the catalytic reduction device to thereby produce ammonia

Methodology Applied

Scientific EffectSublimation: Sublimation

Data Source

PatentEP4279715B1Adaption of a urea deposit model value

Publication Date: 2026.02.25 VOLVO TRUCK CORP

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AI summary

The invention relates to a method for adapting a urea deposit build up model used for estimating an amount of urea deposits in an aftertreatment system of a vehicle (1) comprising a catalytic reduction device (306). The invention also relates to an exhaust aftertreatment system, a vehicle comprising such a system, a computer program, a computer readable medium and a control unit (100) configured to perform the method.