Solenoid Fluid Injector Thermal Barrier Interface
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Solution Overview
Problem
Existing reductant delivery systems for SCR technologies face challenges in handling urea solutions, including freezing in cold climates, boiling during diesel particulate filter regeneration, and the need for air-assisted delivery, which can lead to system damage and inefficient fluid management.
Innovation Solution
A reductant delivery unit with a solenoid fluid injector integrated into the exhaust gas flow path, featuring a thermal barrier interface and a controller for managing fluid temperature and pressure to prevent freezing and boiling, and capable of delivering urea solution directly into the exhaust gas flow path without air assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fluid injector is directly coupled to the exhaust gas flow path for efficient urea solution delivery, then the productivity and reliability of SCR system is improved, but the injector body is exposed to high temperatures causing urea solution freezing and boiling
Solution Approach 1:
A thermally insulating interface is introduced as an intermediary between the fluid injector body and the exhaust gas flow path. This interface comprises a thermal barrier layer that mediates the thermal interaction, allowing the injector to deliver urea solution efficiently while protecting it from direct high-temperature exposure that would cause freezing and boiling
Solution Approach 2:
The interface is segmented into multiple functional layers including an outer layer in contact with exhaust gases, an intermediate thermal barrier layer, and an inner layer protecting the injector body. This segmentation allows each layer to perform its specific function: heat transfer from exhaust, thermal insulation, and protector
2Ease of operation
If air assistance is used to deliver urea solution to the exhaust, then the atomization and mixing efficiency is improved, but the system complexity increases and risk of system damage from contaminants
Solution Approach 1:
The air assistance system is extracted and removed from the delivery mechanism. Instead of using compressed air for atomization and delivery, the system relies on the natural momentum of the urea solution injection combined with the exhaust gas flow to achieve proper atomization and mixing, eliminating the complex air compression and delivery infrastructure
Solution Approach 2:
The urea solution injection system is designed to be self-sufficient, using its own injection momentum and the exhaust gas flow field to achieve atomization and mixing without external air assistance. The injector nozzle geometry is optimized to create effective spray patterns using only the fluid pressure and exhaust gas dynamics
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 ensures reliable urea solution delivery, prevents freezing and boiling, and reduces the risk of system damage by maintaining optimal fluid conditions, enhancing the efficiency and durability of the SCR system.
Implementation Method 1
The interface defines a thermal barrier constructed and arranged to decouple the body of the fluid injector from exposure to heat in the exhaust gas flow path
Implementation Method 2
a solenoid fluid injector constructed and arranged to be associated with an exhaust gas flow path
Implementation Method 3
The urea solution is delivered to the hot exhaust stream and is transformed into ammonia in the exhaust after undergoing thermolysis, or thermal decomposition, into ammonia and isocyanic acid
Implementation Method 4
The isocyanic acid then undergoes a hydrolysis with the water present in the exhaust and is transformed into ammonia and carbon dioxide
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A reductant delivery unit (10) is provided for selective catalytic reduction (SCR) after-treatment for vehicles. The unit includes a solenoid fluid injector (10) constructed and arranged to be associated with an exhaust gas flow path (14) upstream of a SCR catalytic converter (17). The fluid injector has a fluid inlet (13) and a fluid outlet (15) with the fluid inlet being constructed and arranged to receive a source of urea solution and the fluid outlet being constructed and arranged to communicate directly with the exhaust flow path so as to control injection of urea solution into the exhaust gas flow path. An interface (24) is constructed and arranged to couple the fluid injector to the gas flow path. The interface defines a thermal barrier constructed and arranged to decoupled a body of the injector from exposure to heat in the exhaust gas flow path. The solenoid fluid injector (12) further comprising a thermal compensation assembly in communication with the inlet (13) and constructed and arranged to accommodate expansion of the urea solution upon freezing thereof.