Dual-Chamber Pump for Precision Urea Dosing
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Solution Overview
Problem
Existing systems for reducing NOx emissions in internal combustion engines, such as SCR systems, require high precision in measuring out reducing chemicals like urea, with inaccuracies leading to reduced efficiency or catalyst damage.
Innovation Solution
A pump with dual pumping chambers and a transfer valve, actuator group, and precision valves ensures accurate fluid measurement and transfer, preventing over- or under-dosing, and maintaining efficiency even for high volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pumping chamber is used, then the device complexity is reduced, but the measurement precision deteriorates for high volumes
Solution Approach 1:
The pump is divided into two separate pumping chambers (first pumping chamber and second pumping chamber) that operate in sequence. The fluid is first pumped into the first chamber, then transferred to the second chamber through a transfer valve. This segmentation allows for more precise measurement of high fluid volumes by dividing the measurement process into two stages, achieving measurement precision better than 5% even for high volumes.
2Productivity
If high pumping speed is achieved, then the productivity is improved, but the measurement precision deteriorates
Solution Approach 1:
The pump operates through periodic cycles involving sequential opening and closing of three valves (first inlet valve, transfer valve, and outlet valve) coordinated by an actuator group. During each cycle, the piston moves between extreme positions to alternately fill the first pumping chamber, transfer fluid to the second chamber, and discharge the fluid. This periodic valve actuation enables both high pumping speed and precise measurement by controlling fluid flow in discrete, measurable increments.
Solution Approach 2:
The dual-chamber design with coordinated valve actuation enables continuous fluid delivery without interruption. While one chamber is being filled, the other is being discharged, and the transfer valve seamlessly connects the two chambers. This continuous operation maintains high productivity while the precise valve control ensures measurement accuracy throughout the continuous flow process.
3Measurement precision
If precision valves and actuator group are added, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The actuator group serves multiple functions simultaneously: it actuates the first inlet valve, the transfer valve, and the outlet valve in the correct sequence; it drives the piston between extreme positions; and it coordinates the timing of all valve operations. This multi-functional actuator reduces the need for separate control mechanisms for each valve, thereby improving measurement precision through coordinated control while limiting the increase in device complexity.
Data Source
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AI summary
A pump for measuring out a fluid comprises a first and a second pumping chamber, which comprise an inlet valve and an outlet valve, respectively, moving between an opened configuration and a closed configuration; the pump further comprises a transfer valve interposed between the first and second pumping chambers and being movable between an opened configuration and a closed configuration for respectively permitting or preventing the flow of a fluid, an comprises as well an actuator group configured to mediate the passage of each valve from the closed configuration to the opened configuration and promotes a pumping of the fluid from the first to the second pumping chamber.