Overmolded Plastic Tank for Reducing Agent Storage
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Solution Overview
Problem
Existing tank devices for storing reducing agents in exhaust gas treatment systems face challenges in maintaining reliability and leaktightness, especially at low temperatures and in the presence of corrosive substances, and require costly fastening elements that can compromise leaktightness.
Innovation Solution
A tank device with a support element overmolded in a second plastic, coupled liquid-tight to the container wall, which includes sensor elements and electrical components, allowing for reliable and corrosion-resistant storage of reducing agents like urea solutions, without the need for penetrating fasteners, using polyethylene plastics with similar temperature coefficients to minimize thermal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If penetrating fastening elements are used to attach the support element to the container wall, then mechanical strength and positioning are improved, but leaktightness deteriorates due to tolerances and penetration holes
Solution Approach 1:
The patent replaces mechanical fastening elements (screws, clips, or other penetrating fasteners) with a chemical bonding system using adhesives. The adhesive is applied in the aperture of the container wall to bond the support element, creating a leaktight seal without penetration holes. This substitution eliminates the tolerance issues and leakage paths associated with mechanical fasteners while maintaining strong mechanical attachment.
2Object-affected harmful factors
If the support element is fully enclosed in the container, then protection from corrosive liquid medium is improved, but reliability deteriorates due to freezing damage at low temperatures
Solution Approach 1:
The patent applies local quality by selectively positioning the support element such that only the necessary portion is enclosed within the container while extending outside. This allows the sensor elements and electrical components to be exposed to ambient air (avoiding freezing damage) while still providing support functions within the container. The aperture serves as a localized interface that balances protection needs with temperature considerations.
3Reliability
If multiple fastening elements are used to secure the support element, then attachment reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces multiple mechanical fastening elements with a single adhesive bonding system. The adhesive is applied in the aperture to bond the support element, eliminating the need for multiple screws, clips, or other fasteners. This reduces device complexity, simplifies assembly, and lowers manufacturing costs while maintaining or improving attachment reliability through the leaktight seal.
4Ease of manufacture
If the container wall and support element are joined with penetrating fasteners, then assembly simplicity is improved, but leaktightness deteriorates due to tolerance accumulation
Solution Approach 1:
The patent replaces penetrating mechanical fasteners with an adhesive bonding system applied in the aperture. This substitution maintains assembly simplicity (the support element is still attached in a straightforward manner) while dramatically improving leaktightness by eliminating penetration holes and the tolerance accumulation that occurs with mechanical fasteners. The adhesive creates a continuous seal that prevents leakage paths.
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 long-lasting, reliable, and economical storage of reducing agents, maintaining leaktightness even under corrosive conditions and at low temperatures, with integrated sensors for accurate monitoring, and allows for easy replacement or addition of subassemblies.
Implementation Method 1
an overmolding (232) comprising a second plastic at least in a second contact area, which is coupled to the first contact area of the container wall in a substantially liquid-tight manner in the second contact area
Implementation Method 2
The reducing agent may have highly corrosive and/or chemically aggressive properties. A plastic joint between the first contact area and the second contact area can allow long-lived, reliable, liquid-tight coupling
Implementation Method 3
The first and the second plastic can be chosen so that the plastics have a similar temperature coefficient or a substantially identical temperature coefficient, thus ensuring that almost no thermal stresses occur in the coupling region
Data Source
AI summary
A tank device for storing a liquid medium for reducing pollutant levels in exhaust gases includes a container for storing the liquid medium, having a container wall, which is a first plastic at least in a first contact area. The tank device furthermore includes a support element, which is arranged in an aperture in the container wall and has an overmolding which is a second plastic at least in a second contact area. The second contact area is coupled to the first contact area of the container wall in a substantially liquid-tight manner.