Reductant Dosing System Pressure Control
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Solution Overview
Problem
Existing reductant dosing systems for internal combustion engines face challenges with pressure pulsations and vaporization/boiling of reductant fluid at high altitudes and temperatures, leading to inaccurate dosing in larger diesel power systems.
Innovation Solution
A reductant dosing system that includes a reservoir connected to a reductant pump, a pressure regulator, and a compressed gas source, where the air supply control valve is linked to a controller to manage pressure and prevent boiling, ensuring accurate dosing by regulating the pressure of the reductant fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If pump speed is varied to control DEF pressure, then pressure control is attempted, but pressure pulsations occur that cannot be accurately controlled
Solution Approach 1:
The system dynamically adjusts pump operation based on real-time pressure feedback from the pressure sensor, transitioning between pumping and recirculation modes to maintain stable pressure without pulsations
Solution Approach 2:
A pressure sensor provides continuous feedback to the controller, which adjusts the pump and recirculation valve accordingly to maintain precise pressure control and eliminate pulsations
2Stress or pressure
If pump suction line pressure drop occurs at high altitudes and temperatures, then DEF delivery is affected, but vaporization or boiling of DEF occurs
Solution Approach 1:
The recirculation system preemptively maintains pressure in the suction line by recirculating DEF through the pump, preventing vaporization before it occurs during high-demand dosing operations
Solution Approach 2:
The system maintains pressure buildup in the suction line in advance of dosing events, ensuring liquid DEF is available at the pump inlet even under high altitude and temperature conditions
3Stress or pressure
If DEF is recirculated through the pump at all times, then pressure stability is improved, but unnecessary pump operation and energy consumption occur
Solution Approach 1:
The recirculation valve operates periodically based on pressure feedback, opening only when pressure drops below the threshold during dosing events rather than remaining open continuously
Solution Approach 2:
The system uses the dosing demand itself to trigger recirculation, allowing the natural pressure drop during injection to initiate the recirculation cycle without continuous active control
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 system effectively prevents boiling and vaporization of the reductant fluid, allowing for precise dosing and operation in high-altitude and high-temperature conditions, suitable for larger diesel power systems.
Implementation Method 1
pressurizing the reservoir with a compressed gas source that is fluidly connected to the reservoir through an air supply control valve
Data Source
AI summary
A reductant dosing system for an engine is disclosed. The disclosed reductant dosing system includes a reservoir of reductant fluid that is connected to an inlet of a reductant pump. The pump has an outlet that is fluidly connected to the reservoir, an inlet of a pressure regulator and an inlet of an injector. The pressure regulator includes a reductant pressure control valve that fluidly connects the outlet of the reductant pump to the reservoir when the reductant pressure control valve is in an open position. A compressed gas source is fluidly connected to an air supply control valve that fluidly connects the compressed gas source to the reservoir when the air supply control valve is in an open position. The air supply control valve also has a closed position and is shifted between the open and closed positions by a controller.