Injector Spray Protector for Exhaust Urea Mixing
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Solution Overview
Problem
In compact exhaust systems, larger droplet size dosers fail to adequately transform urea into ammonia due to increased sensitivity to recirculation flow, leading to deposit formation and operational issues such as non-uniform ammonia distribution, pressure drop, and higher emissions during diesel particulate filter regeneration.
Innovation Solution
The implementation of an injector assembly with a spray protector that extends axially beyond the planar area to protect the spray from recirculating flow, ensuring effective mixing of urea with exhaust gases and preventing deposit formation by directing the spray in a manner that aligns with the exhaust gas flow within a cone-shaped injector housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If smaller droplet size dosers are used to enhance urea transformation efficiency, then ammonia transformation efficiency is improved, but sensitivity to recirculation flow increases causing deposit formation
Solution Approach 1:
A spray protector is introduced as an intermediary component between the injector and the recirculation zone. The spray protector shields the urea spray from the harmful recirculation flow, preventing deposit formation while allowing the beneficial small droplet size to maintain high ammonia transformation efficiency.
Solution Approach 2:
The spray protector is positioned to preemptively block the recirculation flow before it can interact with the urea spray. By establishing this protective barrier in advance, the system prevents the harmful interaction that would otherwise cause deposit formation on mixer walls.
2Area of stationary object
If smaller droplet size dosers are used, then surface contact area increases improving transformation, but spray sensitivity to recirculation flow increases
Solution Approach 1:
The spray protector serves as a protective intermediary that isolates the sensitive fine spray from the disruptive recirculation flow. This allows the spray to maintain its stability and reliability while preserving the high surface contact area benefits of small droplet size.
3Volume of stationary object
If compact exhaust system configuration is implemented, then system volume is reduced, but adequate urea transformation cannot be achieved
Solution Approach 1:
The spray protector is nested within the existing compact exhaust system structure, integrating seamlessly into the available space. This allows the system to maintain its compact volume while adding the functional capability to protect the spray and achieve adequate urea transformation.
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 configuration enhances ammonia transformation efficiency, reduces deposit formation, and maintains uniform ammonia distribution, thereby improving the operational performance and reducing emissions in compact exhaust systems.
Implementation Method 1
Typically, an area located at a tip of the doser has a vortex of recirculating flow
Implementation Method 2
A spray protector extends axially from the injector mount to break the planar area
Implementation Method 3
The exhaust system includes a mixer positioned upstream of the SCR catalyst and mixes engine exhaust gases and products of urea transformation
Data Source
AI summary
A vehicle exhaust system includes an injector assembly having an injector mount configured to mount an injector to an exhaust component. The injector mount includes a spray opening surrounding a spray axis. An injector housing extends from an inlet end that receives exhaust gases to an outlet end. The inlet end defines a planar area that is transverse to the spray axis. A spray protector extends axially from the injector mount to break the planar area. A vehicle exhaust component assembly comprising a mixer with the injector assembly and a method for injecting a fluid into an exhaust component using the injector assembly are also disclosed.