Active Valve Regulates Reducing Agent Flow in SCR Systems
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Solution Overview
Problem
Existing reducing agent dosing systems for internal combustion engines experience high flow velocities and uncontrolled delivery due to the short delivery stroke of diaphragm or piston pumps, leading to nozzle overloading and undesired dosing.
Innovation Solution
Incorporating an active valve with a flexible diaphragm in the pressure line of the dosing system, which opens during pressurization and closes automatically when the pump stroke is completed, to regulate counter-pressure and prevent excess delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a diaphragm pump or piston pump is used to deliver the reducing agent, then the reducing agent can be delivered from the tank, but the pump delivers its stroke volume in a very short interval causing high flow rate and uncontrolled dosing
Solution Approach 1:
The valve is pre-positioned in the pressure line between the pump and nozzle. Before the pump delivers the reducing agent, the valve is already in place to control and regulate the flow, preventing the short-interval surge from causing uncontrolled dosing. The valve opens in response to pump pressurization to allow controlled flow through the dosing line.
Solution Approach 2:
The valve acts as an intermediary component between the pump and the nozzle. It mediates the high-flow pulse from the pump by opening and closing in response to pressure changes, transforming the intermittent high-speed delivery into a more controlled flow that maintains dosing accuracy while preserving productivity.
2Productivity
If the pump delivers reducing agent in short intervals, then delivery efficiency is maintained, but pulsations create intermittent loading of the atomizing nozzle causing overloading at low delivery rates
Solution Approach 1:
The valve is pre-positioned to intercept the pump output before it reaches the nozzle. When the pump creates pressure pulsations, the valve responds by opening to allow flow and closing when pressure drops, smoothing out the intermittent loading effects on the nozzle and preventing overloading conditions.
Solution Approach 2:
The valve operates with inherent feedback from the pressure line - it opens when pump-generated pressure builds up and closes when pressure drops after delivery. This automatic feedback mechanism stabilizes the nozzle loading by matching valve opening/closing cycles to the actual delivery rate, preventing overloading while maintaining delivery efficiency.
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 stabilizes the flow velocity and prevents overloading of the nozzle, ensuring precise and controlled delivery of the reducing agent, improving dosing accuracy and reducing the dependency on nozzle and tank position geometries.
Implementation Method 1
wenn dort eine Pressurisierung durch das vom Reduktionsmittel pumpmittel gelieferten Reduktionsmittel erfolgt, dann die Öffnung in den Ventilen aufmacht und ein Überlaufführung in einem Auslauf des Ventils in Richtung einer Dosierungslinie zu einer Düse
Implementation Method 2
durch welche das Reduktionsmittel in den Abgasstrom eingebracht und durch Komprimiertesluft atomisiert wird
Data Source
AI summary
The invention relates to a reducing agent dosing system for injecting a reducing agent into the exhaust-gas flow of an internal combustion engine for selective catalytic reduction, wherein the dosing system can be or is connected to a reducing agent tank (1) from which reducing agent is extracted and delivered by means of a reducing agent pump (2), wherein there is a compressed air supply (3) and at least one nozzle (4) is provided which is connected to the pressure line (11) of the reducing agent pump (2) and via which the reducing agent is introduced into the exhaust-gas flow and atomized by means of compressed air, wherein the pressure line (11) of the reducing agent pump (2) issues via an inlet (6) into a valve (5) which, when it is subjected to pressure by reducing agent delivered by the reducing agent pump (2), opens up the inlet (6) to the valve (5) and an overflow duct to an outlet (7) of the valve to a dosing line (12) to the nozzle (4).