Accumulator Weir for Precise DEF Dosing
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Solution Overview
Problem
Existing exhaust treatment systems for internal combustion engines face challenges in accurately and efficiently delivering diesel exhaust fluid (DEF) to the mixing zone, particularly due to the distance from the reservoir, leading to issues with pump power and accuracy in fluid discharge.
Innovation Solution
An accumulator system is introduced, featuring a container with a vent to maintain atmospheric pressure, an inlet portion for receiving DEF, and an outlet portion with a weir that separates and controls the flow of DEF, allowing for precise dosing and recirculation of DEF between the accumulator and bulk tank, ensuring accurate and efficient delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a larger pump is used to pump DEF from the reservoir to the mixing zone over a long distance, then the pumping capability is improved, but the accuracy and fine adjustment of the volume of DEF discharged deteriorates
Solution Approach 1:
The system is divided into two separate pumping functions: a transfer pump that moves DEF from the reservoir to the accumulator (providing power for long-distance transport), and a dosing pump that withdraws DEF from the accumulator to the mixing zone (providing accurate volume control). This segmentation allows each pump to be optimized for its specific function without compromise.
Solution Approach 2:
The accumulator serves as an intermediary component between the transfer pump and the dosing pump. It receives DEF from the transfer pump and supplies it to the dosing pump, decoupling the two pumping operations. This intermediary allows the dosing pump to operate independently with high precision while the transfer pump handles the bulk transport requirement.
2Length of moving object
If a pump is positioned far from the reservoir to deliver DEF to the mixing zone, then the delivery distance is improved, but the pump power requirement increases
Solution Approach 1:
The pumping function is segmented into two stages: the transfer pump handles the long-distance transport from the reservoir to the accumulator, and the dosing pump handles the short-distance delivery from the accumulator to the mixing zone. This segmentation reduces the overall energy requirement by breaking the long-distance transport into manageable segments with different power requirements.
Solution Approach 2:
The accumulator acts as an intermediary that receives DEF close to the reservoir (minimizing the distance the dosing pump must travel) and supplies it to the mixing zone. This positioning of the accumulator as an intermediate storage point reduces the delivery distance for the dosing pump and optimizes the overall energy efficiency of the system.
3Measurement precision
If the accumulator uses a weir to separate inlet and outlet portions, then the flow control precision is improved, but the device complexity increases
Solution Approach 1:
The weir structure enables the accumulator to self-regulate the flow of DEF from the inlet portion to the outlet portion based on the fluid level. When the DEF level rises above the weir crest, it automatically flows into the outlet portion, providing passive flow control without requiring additional active components or complex control mechanisms.
Solution Approach 2:
The system utilizes hydraulic principles through the weir structure to control fluid flow. The weir creates a hydraulic control mechanism where the flow rate is automatically adjusted based on the fluid level in the inlet portion, providing precise flow control through passive hydraulic action rather than mechanical or electronic controls.
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 accumulator system enhances the accuracy of the dosing pump by maintaining atmospheric pressure, preventing pressure or vacuum disruptions, and allows for precise control of DEF flow, ensuring consistent and efficient delivery even under varying engine loads, reducing the risk of fluid freezing during cold conditions.
Implementation Method 1
a vent between the container and the atmosphere... maintaining atmospheric pressure, preventing pressure or vacuum disruptions
Implementation Method 2
an inlet portion of the container for receiving exhaust treatment fluid... an outlet portion configured to receive exhaust treatment fluid from the inlet portion... means for separating the inlet portion and the outlet portion and permitting exhaust treatment fluid in the inlet portion to flow into the outlet portion
Data Source
AI summary
In accordance with one aspect of the present disclosure, an accumulator is provided for an engine exhaust treatment system. The accumulator includes a container, an inlet portion for receiving exhaust treatment fluid, a conduit in communication with the inlet portion of the container to withdraw exhaust treatment fluid from the inlet portion, and an outlet portion configured to receive exhaust treatment fluid from the inlet portion and having an outlet for discharging exhaust treatment fluid. The accumulator includes a weir separating the inlet portion and the outlet portion that permits exhaust treatment fluid in the inlet portion to flow into the outlet portion.