Coaxial Urea Fluid Line Layout for Uniform SCR Refilling Flow
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Solution Overview
Problem
Existing motor vehicle fluid lines for SCR catalytic converter systems experience non-uniform flow and the formation of eddies or bubbles when refilling urea solutions, which can disrupt the uniform supply of urea to the SCR system.
Innovation Solution
A motor vehicle fluid line comprising a fluid-carrying outer line and inner line, both made of plastics material, connected via a spin welded or laser welded connector, ensuring uniform flow by minimizing non-uniform flow conditions, particularly in the region of the connecting branches, and allowing for heating to prevent urea freezing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single inner duct pipe is used to conduct urea solution to the connector, then the structure is simple, but eddies and bubbles occur in the flow during refilling, disrupting uniform flow
Solution Approach 1:
The pipe is divided into an outer line and an inner line that are fluid-carrying elements. The inner line is received within the outer line over at least part of the length, creating separate flow paths. This segmentation eliminates eddies and bubbles during refilling by providing distinct channels for urea solution flow from the connector to the metering device, thereby maintaining flow uniformity while managing complexity.
2Ease of manufacture
If the pipe structure is simplified to a single duct, then manufacturing is easier, but non-uniform flow conditions occur in the connector region
Solution Approach 1:
The pipe comprises an outer line and an inner line as separate manufacturable components. The inner line is received within the outer line over at least part of the length L, allowing each component to be manufactured with standard precision while achieving superior flow uniformity when assembled. This segmentation enables controlled flow distribution to the connector's first and second connecting branches.
3Reliability
If heating is applied to prevent urea freezing, then reliability is improved, but energy consumption increases
Solution Approach 1:
The system utilizes the exothermic crystallization property of urea by changing its thermal state parameters. When urea solution crystallizes, it releases heat that can be utilized to maintain temperature and prevent freezing in the pipe and connector. This parameter change approach provides passive heating to improve reliability while minimizing active energy consumption for heating.
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 a highly uniform flow of urea solutions, preventing eddies and bubbles, maintaining the reliability of the SCR catalytic converter system by ensuring consistent urea supply and preventing freezing, while allowing for efficient heating of the fluid line.
Implementation Method 1
the outer line and/or the inner line is/are connected to the connector by means of a spin welded connection
Implementation Method 2
by means of a laser welded connection
Implementation Method 3
allowing for heating to prevent urea freezing
Data Source
AI summary
A motor vehicle fluid line for conducting at least one fluid medium, in particular for conducting urea solutions for SCR catalytic converter systems, at least one fluid-carrying pipe and at least one fluid-carrying connector that is connected to the pipe being provided. The pipe comprises a fluid-carrying outer line and a fluid-carrying inner line that is received in the outer line over at least part of its length L. The connector comprises a first connecting branch that is in fluid communication with the outer line, and comprises a second connecting branch that is in fluid communication with the inner line.