Silicone Layer Structure with Oleophobic-Hydrophobic Surface
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Solution Overview
Problem
Silicone-based casting compounds used in electrical machines are prone to swelling and mechanical property degradation when exposed to engine oils, leading to reduced strength and temperature resistance, which is problematic in electric motors that come into contact with gear oils.
Innovation Solution
A layer structure comprising a silicone layer with an oleophobic-hydrophobic surface is created by integrating a thermoplastic textile structure, where the silicone penetrates into the textile fibers or pores, forming a cohesive connection that enhances mechanical stability and prevents oil and moisture penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high proportions of filler (e.g., quartz particles) are added to increase thermal conductivity, then thermal conductivity is improved, but the material becomes more susceptible to oil absorption and swelling
Solution Approach 1:
The patent applies a composite material structure consisting of a silicone-based casting compound combined with a fluoropolymer coating layer. This composite approach allows the bulk material to maintain high thermal conductivity through filler content while the fluoropolymer surface layer provides oil resistance and prevents swelling, thus resolving the contradiction between thermal conductivity and oil resistance.
2Ease of manufacture
If silicone material is used for casting compounds, then ease of manufacture and processing tolerance are improved, but affinity towards hydrocarbons causes oil absorption and swelling
Solution Approach 1:
The fluoropolymer coating acts as an intermediary layer between the silicone casting compound and the hydrocarbon oil environment. This mediator layer maintains the advantages of silicone (ease of curing, processing tolerance) while blocking the harmful interaction between silicone and hydrocarbons, thereby preventing oil absorption and swelling.
3Reliability
If the casting compound is exposed to engine and transmission oils, then mechanical protection and electrical insulation are provided, but the casting compound swells and mechanical properties decrease
Solution Approach 1:
The fluoropolymer coating is applied in advance to create a protective barrier that prevents oil from contacting the silicone casting compound. This preliminary protective action stops the swelling process before it can occur, thereby maintaining the mechanical properties (strength and hardness) while still allowing the casting compound to provide electrical insulation and mechanical protection.
4Reliability
If a fluoroplastic mixture is sintered or melted to increase hydrolysis and oil resistance, then oil resistance is improved, but device complexity and manufacturing complexity increase
Solution Approach 1:
Instead of using complex sintering or melting processes with fluoroplastic mixtures, the patent employs a simpler fluoropolymer coating application method. This approach achieves the same oil resistance and hydrolysis resistance with a more straightforward, less complex manufacturing process, thereby reducing device complexity while maintaining reliability.
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 oleophobic-hydrophobic layer structure significantly increases the longevity and mechanical stability of the silicone layer, maintaining its properties while preventing chemical influences and oil absorption, thus ensuring the electrical machine's performance and durability.
Implementation Method 1
the cohesive connection is formed by penetration of the silicone of the first layer into the textile structure of the second layer
Implementation Method 2
an external second layer which is cohesively connected to the first layer and has an oleophobic-hydrophobic surface
Data Source
Figure 1A~1B
Figure 2A~5C
AI summary
The invention relates to a layer structure (30) based on silicone having an oleophobic-hydrophobic surface for coating, sealing, and/or connecting electric machines or parts thereof, comprising: i. a first layer (31) comprising a silicone; ii. a second layer (32), which is connected to the first layer in a bonded manner and which comprises a thermoplastic. According to the invention, the second layer (32) has a textile structure and the bonded connection is formed by the penetration of the silicone of the first layer (31) into the second layer (32). The invention further relates to an electric machine (10), comprising a stator (20) and a rotor (40), wherein the stator (20) and/or the rotor (40) comprises a winding (26) and/or permanent magnets (44), and wherein an oleophobic-hydrophobic layer structure (30, 50) according to one of claims 1 to 6 is arranged in the region of a winding (26) and/or in the region of an adhesive bond of the permanent magnets (44).