Suction Pump Dosing Arrangement for Urea Freezing Protection
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Solution Overview
Problem
Existing dosing systems for self-igniting internal combustion engines face challenges in preventing damage from freezing urea-water solutions, particularly at low temperatures, and are prone to failure and high costs due to the use of 4/2-way valves for aeration and emptying.
Innovation Solution
A dosing arrangement utilizing a suction pump for aeration and emptying, which reduces the need for high delivery pressure and eliminates the need for expensive 4/2-way valves, ensuring cost-effective and reliable operation, including improved filling at higher altitudes and optimized overrun protection and reverse suction functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 4/2-way valve is integrated into the dosing system to enable aeration and emptying, then the dosing system can prevent damage from freezing urea-water solution, but the device complexity and cost increase significantly
Solution Approach 1:
The patent extracts the aeration and emptying functions from the complex 4/2-way valve system and implements them separately using a simple suction pump connected to the pressure line. This separates the freezing protection function from the main dosing function, reducing overall system complexity while maintaining reliability.
Solution Approach 2:
The suction pump serves multiple functions: it aerates the dosing system to prevent freezing, empties remaining urea solution, and can operate at different altitudes. This multi-functional approach replaces the specialized 4/2-way valve, reducing device complexity while maintaining or improving reliability.
2Reliability
If a 4/2-way valve is used for aeration and emptying, then the dosing system can operate reliably at low temperatures, but the manufacturing cost increases
Solution Approach 1:
The patent replaces the expensive 4/2-way valve with a relatively inexpensive suction pump. The suction pump is a simpler, more cost-effective component that achieves the same freezing protection function, significantly reducing manufacturing costs while maintaining reliability.
3Productivity
If the suction pump delivers reducing agent at high altitudes, then the system can be filled with AdBlue, but air must first be pumped out of the system
Solution Approach 1:
The patent implements a venting phase before the filling phase. The suction pump first removes air from the system by pumping it out through the exhaust, then subsequently fills the system with AdBlue. This preliminary action of air removal ensures successful filling at high altitudes where ambient pressure is lower.
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 provides a cost-effective and reliable dosing system that prevents damage from freezing urea-water solutions, reduces the risk of malfunction, and ensures efficient filling and venting at higher altitudes, enhancing overall system performance and reliability.
Implementation Method 1
the suction pump (8) switches on so that the dosing module (13) and furthermore the fluid-carrying lines are emptied by the suction pump (8)
Implementation Method 2
urea-water solution has the property of freezing at low temperatures and increasing its volume by around 11%
Implementation Method 3
increasing its volume by around 11%
Data Source
Figure 1
AI summary
The invention relates to a dosing arrangement (3, 30) for a liquid exhaust gas after-treatment medium for the after-treatment of the exhaust gas from an internal combustion engine having an exhaust gas system, particularly for a urea-water solution, having a delivery pump (7) and a dosing module (13), wherein the delivery pump (7) is connected to a suction line (23) for drawing in the exhaust gas after-treatment medium from a tank (1); the delivery pump (7) and the dosing module (13) are connected to one another via a pressure line (25) and the exhaust gas after-treatment medium can be fed to the exhaust gas system via the dosing module (13); a recirculation pump (8) connected on the suction side to the dosing module (13) is provided; and the exhaust gas after-treatment medium pumped by the recirculation pump (8) can be returned on the high-pressure side via a line, which is not the same as the suction line (23), to the tank, enabling the lines (23, 25) to be flushed with the exhaust gas after-treatment medium as necessary. The invention further relates to a corresponding method for dosing.