Windshield Coating Layers for Solar Heat and Deicing Control
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Solution Overview
Problem
Existing windshield coatings for electric deicing and defogging systems face challenges in balancing low resistivity for efficient heating with high resistivity for safety and solar heat gain control, leading to inefficiencies and potential safety hazards.
Innovation Solution
A multi-layered coating system comprising a high reflectivity, low-emissivity (Low-E) coating and a higher resistance coating, with the latter having a resistance between 10 ohms/sq to 60 ohms/sq, is applied to windshields to optimize resistivity and solar heat gain control, using materials like Indium Tin Oxide (ITO), Fluorine-doped Tin Oxide (FTO), or Carbon Nanotubes (CNTs) for efficient heating and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low resistivity coatings (e.g., Triple Silver MSVD) are used to reduce UV light transmission and improve solar heat control, then solar heat gain control is improved, but heating efficiency for deicing deteriorates due to insufficient heat generation
Solution Approach 1:
The patent divides the coating system into multiple functional layers: a Low-E coating layer for solar heat control and a separate higher resistance heating coating layer for deicing. This segmentation allows each layer to perform its specialized function without compromising the other, resolving the contradiction between solar heat control and heating efficiency
Solution Approach 2:
The patent employs composite coating structures combining different materials with complementary properties - silver-based Low-E coatings for solar reflection and transparent conductive coatings (ITO, FTO, CNTs) for efficient resistive heating. This composite approach enables simultaneous achievement of solar heat gain control and effective deicing heating
2Productivity
If higher resistance coatings (e.g., ITO, FTO, CNTs) are used to improve heating efficiency for deicing, then heating efficiency is improved, but solar heat gain control deteriorates due to higher total solar transmission
Solution Approach 1:
The patent separates solar control functions and heating functions into distinct coating layers, allowing the Low-E layer to handle solar reflection while the heating coating layer handles resistive heating, thus resolving the trade-off between heating efficiency and solar heat control
Solution Approach 2:
The multi-layer coating system achieves multi-functionality by combining solar control capabilities (via Low-E coating) and deicing heating capabilities (via higher resistance coating) in a single integrated windshield structure, eliminating the need to choose between conflicting single-function coatings
3Illumination intensity
If low resistivity coatings are used to maintain high visible light transmission, then visibility is improved, but safety deteriorates due to excessive current draw and potential electrical hazards
Solution Approach 1:
The patent applies different resistivity characteristics to different functional requirements: the Low-E coating maintains high conductivity for visibility and solar control, while the separate heating coating provides higher resistance for safe, controlled heat generation during deicing operations
Solution Approach 2:
The higher resistance heating coating acts as an intermediary between the electrical system and the Low-E coating, providing controlled resistive heating that prevents excessive current draw while maintaining the optical properties of the Low-E layer for visibility and solar control
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 system effectively generates heat for deicing and defogging while maintaining high solar reflectivity, reducing energy consumption, and ensuring safety by evenly distributing electrical current, thus enhancing vehicle comfort and safety.
Implementation Method 1
The electric surface deicing and defogging systems operate on the principle of resistive heating and leverage the conductive properties of the coatings or films. The coatings applied to windshields have preferred resistivities that create resistance to the electrical current flowing through them, thereby generating heat.
Implementation Method 2
These coatings are thin, metallic layers applied to glass that minimize the transmission of ultraviolet and infrared light while preserving high levels of visible light transmission. By reflecting a significant portion of the incoming solar radiation, these coatings help maintain cooler cabin temperatures
Implementation Method 3
silver (Ag) based low-emissivity (Low-E) coatings provide a total solar transmission (TTS) value of 40% approximately for the triple-layered silver. These coatings minimize the transmission of ultraviolet and infrared light
Data Source
AI summary
Systems, methods, and devices for resistivity and solar transmitting optimization of surfaces for de-icing and defogging are provided. The multi-layered system for deicing and defogging of surfaces comprises a high reflectivity, low-emissivity (Low-E) coating aimed at controlling solar heat gain; and a higher resistance coating having a resistance higher than the high reflectivity, low-emissivity (Low-E) coating, the higher resistance coating configured to receive electricity for generating heat to facilitate deicing and defogging.