Reagent Dosing System Using Secondary Vessel Pressurization
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Solution Overview
Problem
Existing SCR dosing systems face issues with high additional parts costs, complex and expensive pump requirements, and the need for additional coolers or purge features, which complicate installation and operation.
Innovation Solution
A reagent dosing system that uses air pressure to pressurize a secondary volume of reagent in a separate vessel, eliminating the need for a pressure-resistant tank and additional coolers, and incorporating a flexible separating member and one-way valve to manage reagent flow and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooler is added to the coolant system to cool urea, then the urea can be prevented from reaching boiling point, but the parts cost increases and installation becomes more difficult
Solution Approach 1:
The patent extracts the urea cooling function from the main coolant system by introducing a separate secondary coolant circuit dedicated solely to cooling the urea reagent. This secondary circuit operates independently with its own coolant flow path, allowing effective urea temperature control without requiring modifications to the primary engine coolant system or adding complex cooling components to the existing system.
Solution Approach 2:
The coolant system is segmented into two separate circuits: the primary engine coolant system and the secondary urea cooling system. This segmentation allows each system to be optimized independently - the primary system maintains engine temperature while the secondary system specifically cools the urea reagent, avoiding the need for a single complex integrated cooling system.
2Stress or pressure
If a pump is used to directly pressurise urea, then the boiling point of urea is increased, but the pump becomes complex and expensive and must be robust enough to accommodate frozen urea pressures
Solution Approach 1:
The patent introduces an intermediary substance (secondary coolant) that indirectly pressurizes the urea reagent by controlling its temperature. Instead of using a mechanical pump to directly pressurize the urea, the system uses thermal management as an intermediary mechanism - cooling the urea prevents vapor lock and maintains proper pressure without requiring complex pressure-resistant pumping equipment.
Solution Approach 2:
The patent replaces the mechanical pressurization system (pump) with a thermal management system (secondary coolant circuit). By substituting mechanical force with thermal control, the system achieves proper urea pressure and flow without requiring complex, expensive, and robust pressure-resistant pumping equipment that would be needed to handle frozen urea conditions.
3Device complexity
If a secondary vessel with smaller reagent volume is used, then the pressurisation system becomes simpler, but the reagent supply capacity is reduced
Solution Approach 1:
The patent ensures continuous reagent supply by implementing a refill mechanism where the secondary vessel is automatically replenished from the main urea tank. The system maintains continuous operation by transferring urea from the main storage tank to the secondary pressurized vessel as needed, ensuring that the smaller secondary vessel does not limit overall reagent supply capacity while keeping the pressurization system simple.
Solution Approach 2:
The system performs preliminary action by pre-cooling and pre-pressurizing the urea in the secondary vessel before it is needed for dosing. The secondary coolant circuit is already in place and actively cooling the urea in the secondary vessel, and the pressurization is maintained ready for immediate dosing operation, eliminating delays and ensuring continuous supply capability.
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 solution provides a simple, cost-effective system that maintains reagent pressure without freezing issues, allows for efficient dosing and leak detection, and is compatible with existing vehicle systems without major modifications.
Implementation Method 1
A flexible separating member may be located within the secondary vessel, to separate a volume of air and the secondary volume of reagent; wherein the volume of air is pressurised by the source of air pressure, thereby to apply a force to the flexible separating member and thereby cause pressurisation of the secondary volume of reagent.
Implementation Method 2
the volume of air is pressurised by the source of air pressure, thereby to apply a force to the flexible separating member and thereby cause pressurisation of the secondary volume of reagent
Implementation Method 3
A one-way valve may be provided to prevent a leak flow of reagent from the secondary volume to the main supply.
Implementation Method 4
During the refill cycle, the air pump may vent air from the volume of air, thereby causing the flexible separating member to move to a static position and create a vacuum in the secondary volume of reagent, thereby causing reagent to be drawn into the secondary volume from the main supply.
Data Source
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AI summary
A pressurising means for a reagent dosing system (102) such as a urea dosing SCR system, wherein either the main reagent tank (112) is pressurised by a source of air pressure (114), or wherein a secondary vessel (130), containing a smaller volume of reagent, is pressurised by a source of air pressure (140), such as the vehicle expansion tank, wherein the secondary vessel (130) may include a flexible separating diaphragm (136) to separate a volume of air (138) from the secondary volume of urea (134).