Metallic Insert with PE Coating for Liquid Additive Heating
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Solution Overview
Problem
Exhaust-gas treatment devices face challenges with the freezing of liquid additives like urea-water solutions at low temperatures and the need for effective heating, as well as the incompatibility of these additives with conventional tank materials, leading to leakage issues due to thermal expansion differences between metal and plastic components.
Innovation Solution
A device with a metallic insert coated with polyethylene, allowing for a durable and leak-tight connection between metal and plastic, utilizing high-density polyethylene or polypropylene structures injection-molded onto the polyethylene coating, which provides thermal conductivity and resistance to the liquid additive, while compensating for thermal expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a metallic insert is used in a plastic tank for liquid additive, then thermal conductivity is improved for effective heating, but leakage occurs due to thermal expansion differences between metal and plastic
Solution Approach 1:
A plastics coating layer is applied to the metallic insert to serve as an intermediary between the metal and the plastic tank wall. This coating compensates for thermal expansion differences and prevents leakage, while the metal core maintains thermal conductivity for heating the liquid additive.
Solution Approach 2:
The solution combines metal (for thermal conductivity) with plastics coating and injection-moulded plastic structures (for chemical resistance and thermal expansion compatibility), creating a composite structure that integrates the advantages of both materials while mitigating their disadvantages.
2Reliability
If plastic tanks are used for liquid additive storage, then resistance to liquid additive is improved, but heating effectiveness is reduced due to low thermal conductivity
Solution Approach 1:
Instead of making the entire tank from metal, only specific local areas (the insert) are made from metal to provide heating functionality, while the rest of the tank remains plastic to maintain chemical resistance. The plastics coating on the metal insert ensures chemical resistance at the heating zone.
Solution Approach 2:
The hybrid structure combines plastic tank walls (chemical resistant) with a metal insert (thermally conductive), creating a composite system that achieves both chemical resistance and effective heating capabilities.
3Temperature
If metal components are used for heating, then thermal conductivity is improved, but compatibility with liquid additive is worsened due to aggressiveness of the additive
Solution Approach 1:
The plastics coating on the metallic insert acts as a protective intermediary barrier between the aggressive liquid additive and the metal surface, preventing corrosion and chemical reactions while allowing thermal conduction to occur through the coating layer.
Solution Approach 2:
The combination of metal core with plastics coating creates a composite structure where the metal provides thermal conductivity and the plastics layer provides chemical resistance to the aggressive liquid additive.
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
Ensures effective heating and secure, leak-tight connections between metal and plastic components, maintaining thermal conductivity and preventing air gaps, thus ensuring reliable operation even at low temperatures and reducing the risk of additive leakage.
Implementation Method 1
Metallic inserts or housings for devices for supplying liquid additive have proven to be particularly advantageous, because metal generally exhibits relatively high thermal conductivity
Implementation Method 2
it is often only possible for relatively small components composed of metal to be inserted in fluid-tight fashion into a tank wall composed of plastic. This appears to be the case because the absolute thermal expansions that occur are then not as great
Data Source
AI summary
A device for providing a liquid additive, including at least one metallic insert, which is coated, at least in sections, with a plastic coating made of polyethylene (PE). At least one plastic structure made of a high-density polyethylene (HD-PE) or polypropylene (PP) is sprayed onto the plastic coating.