Compact SCR Aftertreatment Layout for Urea Mixing and Evaporation

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Solution Overview

Problem

Existing aftertreatment devices require long urea mixture pipes to evaporate urea water, leading to protrusion from the engine main body and impaired mountability on vehicles.

Innovation Solution

Incorporating a mixer at the upstream end of the exhaust connection pipe within the aftertreatment device to promote mixing of exhaust gas and urea water, reducing the need for a lengthy pipe and allowing for a compact configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a long urea mixture pipe is used to evaporate urea water by exhaust gas heat, then the evaporation function is improved, but the device protrudes from the engine main body and mountability is impaired

Engineering Contradiction:

Improveurea water evaporationVSAvoidurea mixture pipe length

Core Design Contradiction:

TemperatureVSLength of stationary object

Solution Approach 1:

The urea mixture pipe is nested within the aftertreatment device housing, with the injection portion positioned inside the engine compartment. The exhaust connection pipe routes through the aftertreatment device structure, allowing the mixing and evaporation functions to be contained within a compact footprint that does not protrude from the engine main body.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The urea water injection portion is positioned in the vertical dimension within the engine compartment, injecting upward into the exhaust flow. The exhaust connection pipe utilizes the depth dimension of the aftertreatment device to accommodate the mixing length, transforming the problem from a horizontal protrusion issue to a vertical integration solution.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Quantity of substance

If the urea water injection portion protrudes from the engine main body, then the mixing space is increased, but the mountability on vehicles is impaired

Engineering Contradiction:

Improvemixing spaceVSAvoidmountability

Core Design Contradiction:

Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The mixing function is merged with the aftertreatment device housing structure. The exhaust connection pipe serves dual purposes as both the exhaust flow path and the urea water mixing chamber. The injection portion is integrated into the engine compartment mounting structure, combining multiple functions within a single compact assembly that maintains vehicle mountability.

Inventive Principle:

Principle #5Merging (Combining)

3Length of stationary object

If a compact configuration is used, then mountability is improved, but the mixing and evaporation of urea water becomes insufficient

Engineering Contradiction:

Improvedevice lengthVSAvoidurea water evaporation efficiency

Core Design Contradiction:

Length of stationary objectVSReliability

Solution Approach 1:

The exhaust gas flow continuously passes through the urea mixture pipe and SCR catalyst within the aftertreatment device, providing continuous heat for urea water evaporation. The compact design maintains sufficient residence time and thermal exposure by optimizing the flow path through the integrated mixing and catalytic reduction zones.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The exhaust connection pipe acts as an intermediary mixing chamber where urea water is introduced and mixed with exhaust gas before entering the SCR catalyst. This intermediate mixing zone ensures adequate evaporation and mixing occurs within the compact device, preparing the exhaust stream for effective catalytic reduction downstream.

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

The compact design effectively purifies exhaust gas while minimizing protrusion from the engine, enhancing mountability and reducing the device's overall size.

Implementation Method 1

a mixer arranged at an upstream end of the exhaust connection pipe in a flow direction of exhaust gas

Methodology Applied

Scientific EffectTurbulence: Turbulence

Implementation Method 2

the urea water is mixed with the exhaust gas while being evaporated by heat of the exhaust gas

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 3

evaporated by heat of the exhaust gas

Methodology Applied

Scientific EffectHeat transfer: Convection

Implementation Method 4

the exhaust gas mixed with the urea water passes through the SCR catalyst, and thus nitrogen oxides in the exhaust gas are reduced

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 5

nitrogen oxides in the exhaust gas are reduced

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentUS12454903B2Aftertreatment device and engine

Publication Date: 2025.10.28 YANMAR HLDG CO LTD

AI summary

Provided are an aftertreatment device capable of purifying exhaust gas with a compact configuration and an engine including the aftertreatment device. An aftertreatment device includes: a first case that is a DPF case; a second case that is an SCR case; an exhaust connection pipe that connects the first case and the second case; a mixer arranged at an upstream end of the exhaust connection pipe in a flow direction of exhaust gas; and a urea water injection portion that injects urea water into the mixer.