High Temperature Electromagnetic Actuator Using Ceramic Insulated Windings
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Solution Overview
Problem
Existing high temperature electromagnetic actuators face challenges in maintaining performance and safety when operating above 650°C due to issues with eddy currents and flux shaping, particularly in applications like turbine engines and combustion engines, where permanent magnets are not viable.
Innovation Solution
The development of a high temperature electromagnetic actuator using a magnetic circuit made of high temperature soft ferromagnetic materials like cobalt alloys and windings insulated with ceramic or mica, allowing for operation beyond 650°C, with nickel clad copper conductors and ceramic coated wires, and position returning members to maintain gap and return position effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electromagnetic actuators with permanent magnets are used, then they can provide sufficient magnetic force at normal temperatures, but they cannot operate in high temperature environments above 650°C
Solution Approach 1:
The patent changes the material parameters of the magnetic circuit from conventional ferromagnetic materials to high-temperature ferromagnetic materials (such as cobalt-based alloys like Hiperco 50, Mu-metal, or amorphous metal alloys) that maintain their magnetic properties at temperatures above 650°C. This parameter change enables the actuator to operate reliably in high-temperature environments where conventional actuators would fail.
Solution Approach 2:
The patent employs composite material structures including high-temperature ferromagnetic materials combined with specialized insulation materials (ceramic coatings, mica insulation) and protective coatings. The magnetic circuit uses composite constructions such as stacked laminated sheets of high-temperature ferromagnetic material to maintain performance while managing thermal and magnetic field characteristics.
2Temperature
If high temperature ferromagnetic materials are used in the magnetic circuit, then the actuator can operate above 650°C, but eddy currents increase causing energy loss and reduced efficiency
Solution Approach 1:
The patent divides the magnetic circuit into stacked laminated sheets or segments of high-temperature ferromagnetic material. These segmented structures are electrically insulated from each other through lamination, which breaks the continuous conductive path and significantly reduces eddy current losses while maintaining the magnetic circuit's functionality at high temperatures.
Solution Approach 2:
The patent introduces intermediary insulation layers (such as ceramic coatings, oxide layers, or varnish) between the laminated sheets of high-temperature ferromagnetic material. These intermediary layers act as electrical barriers that prevent eddy current formation while allowing magnetic flux to pass through, thus reducing energy loss without compromising the high-temperature operating capability.
3Power
If conducting wires are used for electromagnetic coils, then they can generate sufficient magnetic field, but insulation fails at high temperatures leading to short circuits
Solution Approach 1:
The patent uses composite insulation materials such as ceramic coatings (alumina, magnesia), mica sheets, or high-temperature polymer coatings on the conducting wires. These composite materials provide both electrical insulation and thermal stability, allowing the coils to generate strong magnetic fields while maintaining insulation integrity at temperatures above 650°C.
Solution Approach 2:
The patent employs sacrificial protective coatings or insulation layers that can degrade or be replaced if necessary, allowing the core conducting wires to remain intact. This approach uses readily replaceable insulation materials that protect the expensive wire conductors from thermal damage.
4Temperature
If permanent magnets are replaced with electromagnetic coils, then the actuator can operate at high temperatures, but the device complexity and current requirements increase
Solution Approach 1:
The patent extracts the permanent magnet component from the magnetic circuit and replaces it with electromagnetic coils wound around high-temperature ferromagnetic material. This extraction eliminates the temperature limitation of permanent magnets while using the high-temperature ferromagnetic material to concentrate and guide the magnetic field, thereby reducing the overall complexity compared to using large, complex high-temperature magnet assemblies.
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 solution enables actuators to provide high force density and dynamic performance at temperatures exceeding 650°C, with reduced leakage flux and simple assembly, capable of handling high temperature environments without continuous current requirements.
Implementation Method 1
magnetic circuit made of high temperature soft ferromagnetic materials like cobalt alloys
Implementation Method 2
windings insulated with ceramic or mica, allowing for operation beyond 650°C
Implementation Method 3
Application of a current to a winding surrounding a permanent magnet. Application of a current causes the magnet to move
Data Source
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AI summary
An electromagnetic actuator (100) includes a magnetic circuit (101) that includes a stationary core having a first leg, a second leg and a connecting leg that connects the first and second legs, the stationary core (102) being formed of a high temperature ferromagnetic material, and an armature (104) formed of the high temperature ferromagnetic material. The actuator also includes one or more position returning members (110) disposed between the stationary core and the armature and a first winding (108) surrounding the first leg, the first winding being formed a metal wire with ceramic insulation.