Heatable Mirror Moulded Body with Encapsulated Heating Element
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Solution Overview
Problem
Existing methods for producing heatable molded bodies for exterior rear view mirrors, such as those using carbon fibers, result in incomplete embedding of fibers within the plastic, leading to electrical contact with the mirror glass and increased corrosion, necessitating frequent replacement.
Innovation Solution
A method involving a two-layer plastic structure where a conductive fiber fleece is encapsulated between two plastic layers, ensuring electrical insulation and complete embedding of the fibers, with the outer layer being reflective and scratch-resistant to prevent corrosion and enhance heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon fiber fleece is used as heating element in molded body, then heating function is achieved, but carbon fibers are not completely embedded in plastic leading to electrical contact with mirror glass and increased corrosion
Solution Approach 1:
The plastic material is divided into two separate layers: a first plastic layer that provides structural support and a second plastic layer that completely encapsulates the carbon fiber fleece. This segmentation ensures that the heating element is fully embedded while maintaining manufacturing feasibility, thereby preventing electrical contact between carbon fibers and mirror glass.
Solution Approach 2:
The carbon fiber fleece is nested within the second plastic layer, which itself is attached to the first plastic layer. This nested structure ensures complete embedding of the conductive fibers while maintaining a compact design, eliminating the corrosion issue caused by exposed fibers.
2Reliability
If two plastic layers are used to encapsulate fiber fleece, then electrical insulation is improved, but manufacturing process complexity increases
Solution Approach 1:
The molding process is segmented into two sequential injection steps: first injecting the structural plastic layer, then injecting the encapsulating plastic layer around the carbon fiber fleece. This segmentation allows each layer to be optimized for its specific function while maintaining a relatively simple overall process.
Solution Approach 2:
The first plastic layer is produced and positioned in the mold before the carbon fiber fleece is inserted and the second plastic layer is injected. This preliminary action ensures proper positioning and alignment, simplifying the overall manufacturing process while achieving complete electrical insulation.
3Temperature
If first plastic layer is made thin to improve thermal conduction, then heat transfer to mirror surface is enhanced, but structural rigidity may be compromised
Solution Approach 1:
The plastic structure is segmented into two layers with different thicknesses and functions: the first layer is made thin to maximize thermal conduction to the mirror surface, while the second layer provides the necessary structural support and encapsulation. This segmentation allows optimization of both heat transfer and structural properties.
Solution Approach 2:
The molded body uses a composite structure combining two different plastic materials with complementary properties: one material optimized for thermal conduction (thin first layer) and another for structural integrity (thicker second layer), achieving both rapid heating and adequate rigidity.
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 effectively prevents corrosion, enhances heat transfer for quicker heating, and maintains optical quality, resulting in a durable and long-lasting heatable mirror surface.
Implementation Method 1
a heating element that is designed as a fiber fleece that can be electrically contacted
Implementation Method 2
which results in improved heat transfer, which means that the mirror surface, for example, is heated more quickly
Data Source
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AI summary
The invention relates to a method for producing a heatable moulded body, in particular for exterior rearview mirrors, with a heating element which is formed as an electrically contactable nonwoven fabric (11). The object of the invention is to provide an improved method for producing a moulded body of the generic type and an improved moulded body. This object is achieved by creating or placing a first layer of plastic (10) in a mould, placing the nonwoven fabric (11) on this first layer of plastic (10) and subsequently applying a second layer of plastic (12) to the first layer of plastic (10) and the nonwoven fabric (11), the first and second layers of plastic (10, 12) electrically insulating the nonwoven fabric (11) completely apart from the electrical terminals (13).