Fluid Injection Mixer with Vanes and Impingement Floor
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Solution Overview
Problem
Existing mixers for fluid injection systems in internal combustion engines, such as those using Selective Catalytic Reduction (SCR), face issues with reductant condensation on cool walls, premature injector wear, and inadequate mixing due to their downstream location and design, which can lead to reduced emission effectiveness and increased maintenance costs.
Innovation Solution
The proposed mixer design includes an impingement floor and side walls with shelves and vanes that promote mixing, positioned upstream of the reductant injector to prevent deposition on cool surfaces and enhance mixing efficiency, and can accommodate multiple injectors with adjustable geometry to accommodate varying spray patterns and sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mixer is positioned downstream of the injector, then the additive mixing is improved, but the additive can be injected against cool walls causing condensation and deposits
Solution Approach 1:
The mixer is positioned upstream of the injector to pre-mix the exhaust gas and create optimal flow conditions before the additive is injected. This preliminary mixing action prevents the additive from being injected directly against cool walls, thereby preventing condensation and deposits while maintaining effective mixing.
Solution Approach 2:
The mixer acts as an intermediary device that conditions the exhaust gas flow before the additive injection. By creating a controlled flow pattern and temperature distribution in the mixing chamber, it mediates between the hot exhaust gas and the cool walls, preventing direct contact between additive and cool surfaces.
2Reliability
If the annular flange is used to engage the exhaust duct, then the mixer is secured in place, but it creates an obstruction for additive deposition
Solution Approach 1:
The flange is removed from the mixer design entirely. Instead of using a flange to secure the mixer to the exhaust duct, the invention uses a diffuser outlet that flows directly into the exhaust duct without requiring a separate securing component, thereby eliminating the source of additive deposition.
Solution Approach 2:
The diffuser outlet serves multiple functions: it secures the mixer to the exhaust duct through its integration with the duct geometry, creates a smooth flow transition, and eliminates obstructions that would cause additive deposition. This multi-functional design replaces the traditional flange-based securing method.
3Device complexity
If the mixer is designed for a single additive injector, then the structure is simplified, but it cannot accommodate multiple injectors
Solution Approach 1:
The mixer is designed with a universal geometry that can accommodate both single and multiple additive injectors. The mixing chamber and flow patterns are configured to handle variable injection configurations, allowing the same mixer design to be used across different system configurations without requiring modifications.
Solution Approach 2:
The mixer incorporates adjustable or reconfigurable elements that allow it to adapt to different injector configurations. The flow channels and mixing surfaces can be optimized for various numbers and positions of injectors, enabling dynamic adaptation to different system requirements while maintaining a relatively simple overall structure.
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 design effectively inhibits reductant deposition on exhaust duct surfaces, reduces wear, and improves mixing efficiency, ensuring thorough reductant distribution and enhanced emission reduction capabilities, suitable for both single and multiple injector systems.
Implementation Method 1
The at least one shelf may have a plurality of vanes protruding toward and away from the impingement floor that promote mixing of an injected fluid
Data Source
AI summary
A mixer is disclosed for use in a fluid injection system. The mixer may have an impingement floor oriented generally perpendicular to an intended fluid injection direction and generally parallel with a flow direction. The mixer may also have a first side wall connected along a lengthwise edge of the impingement floor and generally parallel with the flow direction, and a second side wall connected along an opposing lengthwise edge of the impingement floor and generally parallel with the flow direction. The mixer may further have at least one shelf extending between the first and second side walls and generally parallel with the flow direction. The at least one shelf may have a plurality of vanes protruding toward and away from the impingement floor that promotes mixing of an injected fluid.