Fluid container and reductant supply system with such a fluid container
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Solution Overview
Problem
Existing heatable fluid containers for motor vehicles face challenges in preventing overheating, particularly when the contents are cold, which can lead to excessive temperature loads on the plastic material, and current solutions like PTC polymer heating elements are costly.
Innovation Solution
Incorporating a Polymeric Positive Temperature Coefficient (PPTC) element in series with a cost-effective metal resistance heating element, which drastically limits heating current at a critical temperature, acting as a self-resetting safety device to prevent overheating, and using a metal heating element with lamellar sections for enhanced heat transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PTC polymer heating element is used to prevent overheating, then overheating protection is achieved, but manufacturing costs increase significantly
Solution Approach 1:
The heating system is segmented into two distinct functional components: a metal resistance heating element for cost-effective heating and a PPTC element for safety protection. This segmentation allows each component to be optimized for its specific function while controlling overall costs.
Solution Approach 2:
The PPTC element acts as an intermediary safety device between the power source and the heating element. It monitors temperature conditions and automatically limits current when overheating is detected, providing protection without requiring the entire heating element to be expensive PTC polymer.
2Ease of manufacture
If a metal resistance heating element is used, then manufacturing costs are reduced, but overheating protection response time increases
Solution Approach 1:
The PPTC element provides self-service automatic protection without requiring external control systems. When the container wall temperature reaches the critical transition temperature, the PPTC element automatically increases its resistance and limits the heating current, providing fast-acting overheating protection.
Solution Approach 2:
The patent replaces complex mechanical or electronic temperature control systems with a simple electrical property change in the PPTC element. The automatic resistance change based on temperature eliminates the need for thermostats, sensors, and control circuits, achieving both cost reduction and fast response.
3Loss of time
If the container wall is heated quickly to thaw frozen contents, then thawing time is reduced, but the risk of overheating and plastic material damage increases
Solution Approach 1:
The PPTC element is pre-configured with a critical transition temperature that serves as a safety threshold. Before overheating can damage the plastic container wall, the PPTC element proactively detects the temperature approach and automatically limits the heating current, preventing the harmful overheating condition before it occurs.
Solution Approach 2:
The PPTC element provides automatic feedback control based on container wall temperature. As the temperature approaches the critical transition temperature during rapid heating, the PPTC element's resistance increases, reducing the heating current and preventing further temperature rise that could damage the plastic material.
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
This combination provides reliable and quick protection against overheating while reducing manufacturing costs, effectively preventing both container wall and urea solution overheating, and allowing for efficient thawing of frozen contents in a compact container volume.
Implementation Method 1
the container wall 2 is provided with a PPTC element 4 as protection against overheating, which element is connected in series with the at least one heating element3... with a heating to a critical transition temperature, typically changes its resistance by several orders of magnitude, thus drastically limiting the heating current
Implementation Method 2
a cost-effective metal resistance heating element is used as heating element... the advantages of favorable manufacturing costs of a metal resistance hearing element are combined with the quick response times of a PPTC element
Implementation Method 3
Polyamides, especially polyphthalamides, are an especially appropriate material for the container wall because, on the one hand, they are urea-resistant and, on the other hand, possess the required caloric conductivity and temperature stability
Data Source
AI summary
A fluid container for a motor vehicle, said container having a container wall which is made out of a plastic material and is provided with at least one metal resistance heating element. According to the invention the container wall is provided with at least one PPTC element as protection against overheating, said PPTC element being connected in series with the at least one heating element.