Asymmetric Diverging Cone Injector Adaptor for DEF Mixing
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Solution Overview
Problem
Exhaust systems face challenges in providing de-NOx capability, minimizing diesel exhaust fluid (DEF) deposit formation, and ensuring sufficient NH3 mixing before the initial catalyst, particularly due to varying packaging space constraints.
Innovation Solution
An injector adaptor with a body forming an asymmetric diverging cone shape is implemented downstream of the turbocharger, featuring a larger outlet area than the inlet area, which accommodates a DEF injector and includes a mixer to facilitate efficient DEF injection and mixing with exhaust gases, thereby reducing back-pressure and enhancing NH3 distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a DEF injector is placed downstream of the turbocharger in close proximity, then de-NOx capability is improved, but system back-pressure increases
Solution Approach 1:
The exhaust system is segmented into distinct functional zones: the turbocharger outlet, the DEF injection zone within the adaptor, the mixing zone in the diverging cone, and the outlet to the aftertreatment catalyst. This segmentation allows optimized flow paths for each function, reducing overall back-pressure while maintaining de-NOx effectiveness.
Solution Approach 2:
The adaptor body employs an asymmetric diverging cone shape that expands in the radial dimension while flowing exhaust axially. This dimensional transition creates a mixing chamber that reduces flow velocity and promotes thorough DEF-exhaust mixing without creating excessive back-pressure, as the area expansion occurs perpendicular to the main flow direction.
2Volume of moving object
If packaging space is reduced, then system compactness is improved, but ability to provide sufficient NH3 mixing before catalyst deteriorates
Solution Approach 1:
The adaptor merges multiple functions into a single component: it serves as the mounting structure for the DEF injector, provides the asymmetric diverging cone mixing chamber, and acts as the transition piece to the aftertreatment catalyst. This consolidation achieves sufficient NH3 mixing within a compact volume by integrating injection, mixing, and flow transition functions.
Solution Approach 2:
The asymmetric diverging cone creates localized regions with different flow characteristics: a high-velocity region near the turbocharger outlet for rapid DEF vaporization, and a lower-velocity expanding region for thorough mixing. This local variation in flow quality ensures adequate mixing within limited space by optimizing conditions in each zone.
3Stability of the object's composition
If DEF injector is placed close to turbocharger outlet, then mixing efficiency is improved, but risk of DEF deposit formation increases
Solution Approach 1:
The asymmetric diverging cone geometry creates a controlled pressure gradient and flow velocity distribution that changes parameters along the flow path. The expanding section reduces flow velocity and increases residence time, ensuring complete DEF vaporization and mixing before the exhaust cools to temperatures where deposits would form, thus preventing deposits while maintaining mixing efficiency.
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 effectively provides de-NOx capability, minimizes DEF deposit formation, and ensures sufficient NH3 mixing, achieving NOx reduction from 0.4 g/kw-hr to 0.04 g/kw-hr while maintaining system performance across different packaging configurations.
Implementation Method 1
The body of the injector adaptor can be in the form of an asymmetric diverging cone... The second straight line can be at an acute angle relative to the first straight line
Data Source
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AI summary
Systems, apparatuses, assemblies, and methods for diesel exhaust fluid (DEF) dosing includes a body (264) defining an injector adaptor inlet (265) and an injector adaptor outlet (266); and an injector mount or interface (268) extending from the body (264). The injector mount (268) is between the first and second ends of the injector adaptor (224). The injector adaptor outlet (266) defines an area greater than an area of the injector adaptor inlet (265). In a side view of the injector adaptor (224), at a bottom side of the body (264), a first straight line extends along the body (264) from the injector adaptor inlet (265) to the injector adaptor outlet (266), and at a top side of the body (264) opposite the bottom side, a second straight line extends along the body from the injector adaptor inlet (265) to the injector adaptor outlet (266). The second straight line is at an acute angle relative to the first straight line.