Swirl Generator Guide Element for Exhaust Mixing
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Solution Overview
Problem
Existing mixing apparatuses for internal combustion engines are influenced by external exhaust gas flow and engine operating points, leading to asymmetrical flow distributions and unwanted deposits of reducing agents in the exhaust gas tract, resulting in inhomogeneous mixing and potential cold traps.
Innovation Solution
A swirl generating device with a guide element that imparts a tangentially directed exhaust gas flow, independent of external flow and engine operating conditions, to ensure uniform mixing of reducing agents with exhaust gas, preventing deposits by maintaining symmetry and reducing centrifuging forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a mixing pipe with perforation is used to generate spiral flow for promoting mixing, then the mixing of exhaust gas with reducing agent is improved, but the flow distribution becomes asymmetrical and reducing agent deposits form in flow-stabilized regions
Solution Approach 1:
The patent applies asymmetry by designing the guide element with an asymmetric cross-section (different heights on opposite sides) to deliberately create a specific flow pattern that compensates for asymmetric external influences, achieving symmetric flow conditions inside the mixing pipe despite asymmetric external flow incident on the pipe
Solution Approach 2:
The patent changes the geometric parameters of the guide element (its position, orientation, and cross-sectional dimensions) to optimize the flow distribution. By adjusting these parameters, the guide element can adapt to different operating conditions and maintain symmetric flow patterns that prevent reducing agent deposits
2Adaptability or versatility
If the mixing pipe geometry and external flow conditions vary with engine operating point, then the apparatus can adapt to different engine loads, but different and asymmetrical flow distributions form leading to deposits in flow-stabilized regions
Solution Approach 1:
The guide element's geometric parameters are designed to remain effective across a range of operating conditions. By carefully selecting the guide element's dimensions and position, the apparatus maintains reliable symmetric flow distribution and prevents deposits across different engine loads and operating points
3Productivity
If non-uniform flow through the mixing pipe occurs, then mixing efficiency is reduced, but inhomogeneous warming of the mixing pipe promotes cold wall regions that act as cold traps for the reducing agent
Solution Approach 1:
The guide element is designed to create homogeneous flow distribution throughout the mixing pipe, ensuring uniform warming of the pipe walls and eliminating cold wall regions that would otherwise act as cold traps for the reducing agent
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 solution achieves homogeneous mixing and evaporation of reducing agents, preventing deposits and ensuring consistent flow symmetry, which enhances the SCR catalysis process by maintaining uniform reducing agent distribution and reducing agent deposits.
Implementation Method 1
a guide element which is fitted adjacent to the exhaust-gas inlet opening and which at least partially covers the exhaust-gas inlet opening in a spaced-apart manner in the interior of the swirl generating device and which serves for imparting a flow direction to an exhaust-gas flow
Implementation Method 2
By means of the swirl generating device, which can also be referred to as swirl-imparting device or turbulence generating device, a swirl can be imparted to the exhaust gas or to an exhaust-gas flow
Implementation Method 3
a metering device which is arranged in an exhaust gas tract of the internal combustion engine and which is configured to generate a—preferably rotationally symmetrical—reducing agent spray jet by means of an injector
Implementation Method 4
achieves homogeneous mixing and evaporation of reducing agents
Data Source
AI summary
The present disclosure relates to an apparatus for adding a liquid reducing agent, preferably an aqueous urea solution, to the exhaust gas from an internal combustion engine. The apparatus according to the present disclosure comprises a dosing device arranged in an exhaust line of the internal combustion engine, which device is designed to generate a reducing agent spray by means of an injector. The apparatus furthermore comprises a swirl generator device, designed as a hollow body, preferably a hollow cylinder, about a longitudinal axis, which has a first end facing the injector and a second end facing away from the injector. The shell surface L of the swirl generator device, designed as a hollow body, furthermore comprises at least one exhaust inlet opening extending substantially in the longitudinal direction and a guide element, attached adjacent to the exhaust inlet opening and covering the exhaust inlet opening in the interior of the swirl generator device, at least in part at a distance, for deflecting an exhaust gas flow. According to the present disclosure, the guide element is closed in the direction of the first end of the swirl generator device, by means of a wall or connection to the shell surface, for example, and open in the direction of the second end of the swirl generator device. The present disclosure furthermore relates to a motor vehicle, preferably a utility vehicle, having a corresponding apparatus.