Reducing Agent Delivery Device Compensation Element
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Solution Overview
Problem
SCR systems for exhaust gas cleaning in vehicles face issues with reducing agents freezing at low temperatures, leading to volume expansion that can damage components due to increased pressure, and existing solutions for volume compensation are not cost-effective or safe.
Innovation Solution
A delivery device with a compensation element that reduces volume during negative pressure and increases volume during overpressure, using a membrane or prestressed surface to manage pressure changes, preventing additional reducing agent from being sucked in during cooling and allowing controlled expansion during freezing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reducing agent line is made flexible to compensate for volume expansion during freezing, then the system can withstand ice pressure, but the device complexity increases and cost-effectiveness decreases
Solution Approach 1:
The reducing agent line is divided into a rigid section and a flexible section. The rigid section maintains structural stability during normal operation, while the flexible section specifically handles volume compensation during freezing. This segmentation allows each part to be optimized for its specific function, reducing overall complexity compared to making the entire line flexible.
Solution Approach 2:
The flexible properties are applied locally only to the section of the reducing agent line that requires volume compensation during freezing, rather than making the entire line flexible. This localized application of flexibility maintains structural integrity where needed while providing compensation where required, improving cost-effectiveness and reducing unnecessary complexity.
2Quantity of substance
If additional reducing agent is sucked into the delivery device during cooling to compensate for volume reduction, then the delivery device remains filled, but the pressure increase during subsequent freezing causes greater damage
Solution Approach 1:
The flow obstacle is pre-positioned in the reducing agent line to prevent additional reducing agent from being sucked into the delivery device during cooling. This preliminary preventive measure ensures that when freezing occurs, there is less reducing agent available to create excessive ice pressure, thereby reducing potential damage without compromising the necessary filling level.
3Reliability
If the delivery device is designed to be elastic to allow volume expansion, then freezing damage is prevented, but energy consumption increases due to unnecessary elastic expansion during pressure increases
Solution Approach 1:
The delivery device is segmented into rigid and flexible portions. The rigid portion maintains structural stability during normal pressure operations, eliminating unnecessary elastic expansion and associated energy consumption. The flexible portion is specifically designed to handle volume changes during freezing events, providing damage prevention only when needed.
Solution Approach 2:
The reducing agent line transitions from a purely elastic design to a dynamic hybrid design that adjusts its properties based on operating conditions. During normal operation, the rigid section maintains structural integrity without unnecessary deformation. During freezing, the flexible section activates to accommodate volume expansion, optimizing both energy efficiency and damage prevention.
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 device maintains consistent reducing agent pressure, preventing damage from ice pressure and reducing energy consumption, while ensuring the system behaves rigidly during normal operation to ensure safe and energy-efficient delivery.
Implementation Method 1
the at least one first compensation element being suitable for reducing the total volume in the event of a negative pressure in the conveying device
Implementation Method 2
the reducing agent can freeze at low ambient temperatures or as a result of cooling effects as a result of convection. An aqueous urea-water solution typically freezes at temperatures below -11 C. Due to the increase in volume due to the phase transition of the reducing agent from liquid to solid
Data Source
Figure 1~2
Figure 3~6
Figure 7~10
AI summary
The invention relates to a delivery device (1) for delivering liquid reducing agent having at least one first compensation element (4), wherein the delivery device (1) comprises at least one reducing agent tank (2) for delivering, guiding, and injecting a reducing agent, a delivery unit (6) and a reducing agent line (7), and an injection unit (8), together comprising a total volume (9) that can be filled with reducing agent, wherein the at least one first compensation element (4) is suitable for shrinking the total volume (9) in case of a vacuum in the delivery device (1).