Hydraulically Driven Diaphragm Pump for Urea Injection
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Solution Overview
Problem
Existing exhaust gas aftertreatment systems for internal combustion engines face challenges with aggressive fluids like urea solutions, including crystallization issues, mechanical drive complexities, and inaccurate dosing due to direct mechanical or hydraulic drives, which affect the efficiency and reliability of nitrogen oxide reduction in diesel engines.
Innovation Solution
A hydraulically driven diaphragm pump with a magnetically actuated armature piston is used to deliver the urea solution, providing precise dosing and high pressure without direct contact between the aggressive medium and moving parts, simplifying the system with a single connecting line and eliminating the need for a return line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a piston pump is used to deliver urea solution, then the pump can provide high pressure, but the moving parts will jam or seize due to crystallization of solid substances when the fluid dries
Solution Approach 1:
A diaphragm is introduced as an intermediary element between the drive mechanism and the urea solution. The diaphragm is acted upon by a piston in a pressure chamber, which transmits force through the diaphragm to pump the urea solution without direct contact between the piston and the aggressive medium. This eliminates crystallization-related jamming while maintaining high delivery pressure capability.
2Device complexity
If a direct mechanical drive of a diaphragm by a lifting magnet is used, then the system structure is simplified, but comparatively high drive forces are required which can lead to inaccurate delivery rates
Solution Approach 1:
The patent employs a hydraulic principle where a piston in a pressure chamber acts upon the diaphragm through hydraulic fluid. This hydraulic drive mechanism transforms the piston's linear motion into diaphragm deformation more efficiently than direct magnetic lifting, reducing required drive forces while improving dosing accuracy through better force control and pressure balance.
3Measurement precision
If a hydraulically driven diaphragm pump is used with high delivery pressure, then the dosing accuracy is improved, but the system requires complex hydraulic reservoir and pressure balancing mechanisms
Solution Approach 1:
The patent combines the pressure chamber containing the hydraulic fluid with the diaphragm working chamber into a single integrated unit. The piston operates within this combined chamber, directly acting upon the diaphragm through the hydraulic fluid without requiring separate hydraulic reservoirs or complex external pressure balancing mechanisms. This integration maintains high dosing accuracy while significantly reducing system complexity.
4Device complexity
If a single connecting line is used from tank to nozzle, then the system simplicity is improved, but high pressure delivery requires more robust pump design
Solution Approach 1:
The hydraulic drive mechanism with piston and pressure chamber provides robust high-pressure delivery capability through fluid pressure transmission. The diaphragm acts as a flexible strength element that can withstand high pressures while the hydraulic fluid transmits force efficiently. This allows the use of a single connecting line with simplified system architecture while maintaining the necessary pump robustness for high-pressure operation.
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 solution ensures precise and reliable injection of the reducing agent into the exhaust gas, achieving high dosing accuracy and long service life of the pump components, while maintaining system simplicity and robustness suitable for vehicle installation.
Implementation Method 1
a lifting magnet with an armature piston (23) enclosed by a magnetic coil (26), by means of which the piston (23) can be driven at least in the direction of the membrane (7)
Implementation Method 2
a hydraulically driven diaphragm pump, which has a piston (15) that is longitudinally displaceable in the direction of the membrane (7) and that applies hydraulic fluid (6) to the membrane (7)
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The invention relates to a system (70) for the aftertreatment of an exhaust gas of an internal combustion engine with a reducing agent, comprising a tank (71) which contains the reducing agent, a catalytic converter (74) which is connected to an exhaust pipe (75) and which is traversed by exhaust gas, a nozzle (73) which opens out, upstream of the catalytic converter (74), into the exhaust pipe (75), wherein the tank (71) for the reducing agent is connected by means of a line (72) to the nozzle (73), and a metering pump which is arranged in the line (72) and which feeds the reducing agent under pressure from the tank (71) to the nozzle (73) in order to inject the reducing agent via the nozzle (73) into the exhaust pipe (75), wherein the metering pump is a hydraulically driven diaphragm pump (1) which has a piston which is longitudinally movable in the direction of the diaphragm (7) and which acts on the diaphragm (7) with hydraulic liquid (6), wherein the diaphragm pump (1) comprises a stroke magnet with an armature piston (24) which is surrounded by a magnet coil (26) and by means of which the piston (15) can be driven at least in the direction of the diaphragm (7).