Electric heater for heating a substance in a motor vehicle
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Solution Overview
Problem
Existing electric heaters for heating liquids in vehicles face challenges in adequate insulation and temperature control, particularly when heating elements come into contact with liquids, risking material degradation and exceeding safe temperature limits.
Innovation Solution
A thin electric heater design using a metal sheet sandwiched between polymeric layers and PTC layers, ensuring insulation and temperature regulation, with the PTC layers being conductive ink, allowing direct contact with polymeric layers made of polypropylene for chemical compatibility and resistance to aqueous solutions like AdBlue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the heating element is made thin to improve heating efficiency, then heating effectiveness is improved, but insulation reliability deteriorates
Solution Approach 1:
The heating element is segmented into multiple functional layers: a metal sheet for heat generation, PTC layers for temperature control, and polymeric layers for insulation. This segmentation allows each layer to perform its specific function optimally while working together as an integrated thin structure that maintains both heating efficiency and insulation reliability.
Solution Approach 2:
The heating element uses composite material structure combining metal (for conductivity and heat generation), PTC material (for temperature regulation), and polymeric materials (for insulation and chemical resistance). This composite approach enables the thin structure to achieve multiple functions simultaneously: efficient heating, automatic temperature control, and reliable insulation against aqueous solutions.
2Productivity
If the heating element temperature is increased to improve heating performance, then heating effectiveness is improved, but material durability deteriorates
Solution Approach 1:
The PTC layer provides automatic feedback control for temperature regulation. As the heating element temperature increases, the PTC material's electrical resistance increases, automatically reducing the current and power input. This negative feedback mechanism prevents overheating and maintains temperature within safe limits, ensuring material durability while preserving heating effectiveness.
Solution Approach 2:
The system exploits the temperature-dependent parameter change of PTC material, where electrical resistance increases with temperature. This parameter change is utilized to automatically regulate heating temperature, preventing the heating element from exceeding maximum safe temperatures while maintaining efficient heating operation.
3Length of moving object
If polymeric layers are made thinner to reduce heater thickness, then device compactness is improved, but chemical resistance deteriorates
Solution Approach 1:
The polymeric layers are designed with specific local qualities: they are made from materials selected for their chemical compatibility with aqueous solutions like AdBlue, and are positioned strategically to provide insulation where chemical exposure occurs. The local material selection and positioning ensure adequate chemical resistance even with reduced thickness.
Solution Approach 2:
The invention uses thin polymeric films that are hermetically sealed to provide effective insulation between the heating element and the aqueous solution. These thin films maintain chemical resistance through proper material selection (polypropylene or similar chemically compatible materials) and hermetic sealing, achieving both compactness and reliability.
4Reliability
If a second metal sheet is added to improve insulation, then insulation effectiveness is improved, but device complexity increases
Solution Approach 1:
The single metal sheet is designed to perform multiple functions: it serves as the heating element for heat generation and simultaneously acts as an insulating barrier between the aqueous solution and the PTC layer. This multi-functionality eliminates the need for a second separate metal sheet, maintaining insulation effectiveness while reducing structural complexity.
Solution Approach 2:
The invention merges the heating function and insulation function into a single integrated metal sheet structure. The metal sheet combines both roles that would traditionally require separate components, thereby simplifying the overall structure while maintaining effective insulation between the solution and heating elements.
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 provides effective heating with temperature regulation, preventing overheating and material degradation, while being cost-effective and easily producible, suitable for heating substances like AdBlue in vehicles.
Implementation Method 1
at least one PTC layer (5), electrically conductive and having a positive temperature coefficient, which, at least partially, preferably partially, in particular only partially, coats the metal sheet (2)
Implementation Method 2
a metal sheet (2), or heating sheet, adapted to be connected to a source of electricity to generate heat when it is crossed by an electrical current
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An electric heater (1) for heating a substance, in particular for a tank for a system for reducing the environmental pollution of a motor vehicle; the electric heater (1) comprising - a metal sheet (2) adapted to generate heat when it is crossed by an electric current; - two polymeric layers (3, 4) between which the metal sheet (2) is arranged; - at least one PTC layer (5), having a positive temperature coefficient, which at least partially coats the metal sheet (2); wherein the two polymeric layers (3, 4) are hermetically sealed to each other, defining a casing which prevents the substance to be heated from coming into contact with the metal sheet (2); wherein said at least one PTC layer (5) has a thickness from 5 to 50 μm; wherein said metal sheet (2) is in contact, in particular directly in contact, with both the polymeric layers (3, 4).