Flexible Sealing Element for Plastic-Metal Tank Joints
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Solution Overview
Problem
Tanks for storing urea-water solutions used in motor vehicle exhaust gas cleaning systems face issues with freezing at low temperatures, requiring designs that withstand ice pressure and need heaters for melting, and must be resistant to the solution, with classic seals failing to provide a secure, fluid-tight seal due to thermal expansion differences between plastic and metal components.
Innovation Solution
A tank design featuring a plastic tank wall with a metal insert and a flexible sealing element that forms sealing surfaces independently of thermal expansion, ensuring a secure, fluid-tight connection despite relative displacements, using a sealing element like a membrane or hose sealing ring that compensates for thermal expansion and maintains contact over a wide temperature range, and incorporating a separate assembly means for mechanical fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal insert is used in a plastic tank wall, then the structural strength and thermal conductivity are improved, but thermal expansion differences cause relative displacements that compromise sealing reliability
Solution Approach 1:
The patent employs a flexible sealing element in the form of a membrane that can deform to accommodate relative displacements between the metal insert and plastic tank wall caused by thermal expansion differences. This flexible membrane maintains continuous sealing contact despite the differential thermal movement, resolving the contradiction between using metal for strength and maintaining sealing reliability.
Solution Approach 2:
The sealing element is designed with specific material parameters (flexibility, elastic modulus) that allow it to adapt to thermal expansion variations. The membrane's physical properties enable it to stretch and compress within a certain range, maintaining sealing effectiveness across different temperature conditions while the metal insert provides structural strength.
2Adaptability or versatility
If the tank operates over a wide temperature range, then the operational versatility is improved, but thermal expansion causes sealing surfaces to lose contact
Solution Approach 1:
The sealing system transitions from a static rigid seal to a dynamic flexible membrane that can adapt its shape and position in response to temperature changes. The membrane's ability to deform dynamically allows the tank to operate reliably across a wide temperature range from -50°C to +90°C while maintaining continuous sealing contact between the metal insert and tank wall.
3Manufacturing precision
If a rigid sealing element is used, then the manufacturing precision is improved, but the sealing element cannot compensate for thermal displacement
Solution Approach 1:
The patent replaces rigid sealing elements with a flexible membrane that combines manufacturable precision with thermal adaptability. The membrane can be manufactured with precise dimensions and material properties, then deployed to flexibly compensate for thermal displacements, achieving both manufacturing precision and thermal compensation capabilities.
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 design ensures a reliable, fluid-tight seal over a wide temperature range (-50 °C to +90 °C), preventing leakage and maintaining operational integrity by accommodating thermal expansion differences between plastic and metal components, allowing for efficient storage and delivery of urea-water solutions or other liquids.
Implementation Method 1
due to thermal expansion of the tank wall and the insert (at least in sections), relative displacements occur between the tank wall and the insert
Implementation Method 2
a flexible sealing element for the liquid-tight connection of the tank wall and the insert to one another
Data Source
AI summary
Tank for an operating liquid for a motor vehicle. Tank (1) for an operating liquid for a motor vehicle (2) with a tank wall (3) made of plastic, having an opening (4) and an insert (5), made of metal, arranged at the opening (4), and a flexible sealing element (6) for interconnecting, in a liquid-tight manner, the tank wall (3) and the insert (5), wherein, on account of thermal expansion of the tank wall (3) and of the insert (5), relative displacements (7) arise between the tank wall (3) and the insert (5) and the flexible sealing element (6) is configured such that sealing faces (8, 16) are formed both on the insert (5) and on the tank wall (3), against which faces the sealing element (6) bears independently of the relative displacements (7).