Dual-Orifice Injector for Fine Mist Atomization
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Solution Overview
Problem
Existing exhaust gas aftertreatment systems face challenges in achieving a fine mist of reduction agents like ammonia or urea for efficient NOx reduction, as the size of droplets sprayed into the exhaust gas affects reaction efficiency, and current injectors struggle to maintain optimal pressure and flow control.
Innovation Solution
The injector system includes a needle and needle guide with a solenoid and biasing member to selectively control the open and closed positions, allowing fluid to exit through either the injection orifice or bypass opening, with a pressure regulating valve to manage pressure and flow, ensuring efficient atomization and reduced leakage for optimal spray characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pressure drop across the injector orifice is increased to decrease droplet size and achieve a finer mist, then the spray quality improves, but the force required for needle movement and potential leakage increases
Solution Approach 1:
The invention divides the fluid flow path into two separate openings: an injection orifice for spraying reduction agent into exhaust gas, and a bypass opening for allowing fluid to exit and return to reservoir. This segmentation allows the system to manage high pressure drop across the injection orifice for fine mist generation while providing a bypass path that reduces the overall force burden on the needle by allowing excess fluid to flow through the bypass opening instead of requiring the needle to completely control all fluid flow
Solution Approach 2:
The bypass opening acts as an intermediary path that mediates between the high-pressure injection orifice and the reservoir. It provides an alternative route for fluid flow that reduces the total force required for needle movement while maintaining the high pressure drop needed at the injection orifice for fine droplet atomization
2Device complexity
If a single opening is used for fluid exit, then the device structure is simpler, but the control precision over spray characteristics and pressure management is insufficient
Solution Approach 1:
The fluid exit path is segmented into two distinct openings with different functions: the injection orifice for controlled spray into exhaust gas with precise pressure management, and the bypass opening for excess fluid to return to reservoir. This segmentation enables precise pressure control at the injection orifice while providing a relief path through the bypass opening, achieving better pressure control precision without excessive complexity
Solution Approach 2:
The dual-opening design provides multi-functionality: the injection orifice serves for reduction agent delivery with fine atomization control, while the bypass opening serves for pressure regulation and fluid return. This multi-functionality allows the system to achieve precise pressure and flow control characteristics that would be difficult with a single opening
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 enables precise control over the spray of reduction agents, achieving a finer mist and increased atomization, enhancing the reaction efficiency with exhaust gases and reducing the force required for needle movement, thus improving NOx reduction in exhaust gas treatment systems.
Implementation Method 1
The injector may include a solenoid and biasing member to selectively move the needle between an open and a closed position
Implementation Method 2
The injector may include a solenoid and biasing member to selectively move the needle between an open and a closed position
Implementation Method 3
As the pressure drop across the injector orifice increases, the size of the droplets of the reduction agent generally decreases, and the injector sprays a finer mist of the reduction agent into the exhaust gas
Data Source
AI summary
An injector for an injection system is provided, including a first opening, a second opening, an open position and a closed position. The first opening is for spraying the fluid out of the injector, and the second opening is for allowing the fluid to exit the injector. When the injector is in the open position, the injector sprays the fluid from the first opening and the flow of the fluid to the second opening is substantially blocked. When the injector is in the closed position the injector allows the fluid to exit the injector from the second opening. The injector substantially blocks the spray of the fluid from the first opening when the injector is in the closed position.