This invention relates to an electromagnetic assembly constructed of multiple, stacked layers, and to integrated heat mitigation techniques. The invention is especially suited to the assembly of micro-electromagnets and micro-solenoids.
According to a first aspect of the invention there is provided a multilayered electromagnetic assembly, the electromagnetic assembly comprising:
The ferromagnetic core may be fixed relative to the assembly, thereby functioning as an electromagnet, or moveable within the assembly, thereby functioning as a solenoid.
Typically, the cutaway portions, the core and the spiral configurations are substantially circular in plan view; although these may all be formed of other applicable shapes and geometric patterns.
The electromagnetic assembly may be modular and expandable, or manufactured in an integrated form.
According to a second aspect of the invention there is provided a multilayered electromagnetic assembly, the electromagnetic assembly comprising:
The ferromagnetic core may be fixed relative to the assembly, thereby functioning as an electromagnet, or moveable within the assembly, thereby functioning as a solenoid.
Preferably, the substrate layers further comprise at least one heat conducting portion provided thereon at a position common to some or all of the other substrate layers, the heat conducting portion passing through the substrate to provide a conducting surface on both sides of the layer, thereby enabling heat passing through the heat conducting layers to pass through the overlapping common heat conducting portions provided on each substrate layer.
Separate connections are consequently provided between layers for the electrical conduction and for the heat conduction, so that the electrical current always flows in a particular spiral orientation around the ferromagnetic core through the electrical contacts and heat generated may flow from within the assembly to radiating external surfaces on the outside of the assembly through the separate heat conducting portion pass through system.
The illustrations are intended to provide a general understanding of the concepts described and the structure of various embodiments, and they are not intended to serve as a complete description of all the elements and features of methods and systems that might make use of the structures or concepts described herein. Many other embodiments will be apparent to those of skill in the art upon reviewing the description. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. It should also be appreciated that the figures are merely representational, and are not be drawn to scale and certain proportions thereof may be exaggerated, while others may be minimized. Accordingly, the specification and drawings, together with any examples, are to be regarded in an illustrative rather than a restrictive sense and the specific form and arrangement of the features shown and described are not to be understood or interpreted as limiting on the invention.
In the figures, layer A is the top cover and layer J is the bottom cover. All of the layers A-J have a cutaway portion 20, through which a ferromagnetic core is positioned when all of the layers are stacked and assembled. The cutaway portion is typically 1-2 mm in diameter, but may be smaller or larger as appropriate. The primary layers providing the electromagnetic attributes of the electromagnet assembly are substantially planar substrate layers B, C, E, F, H and I; these substrate layers carry a spiral of insulated conductive material 22 (typically copper) formed in a substantially flat configuration between the outer edges of the substrate layers and the inner cutaway portion provided for the core, thereby forming a flattened radiating coil on the layer substrate. In the electromagnetic assembly shown, heat conducting layers 24 are also provided between certain substrate layers.
The layers are illustrated in a substantially square configuration, although it should be appreciated that any appropriate shape could be used, such as substantially circular, hexagonal, octagonal shapes or other entirely regular or irregular shapes. Equally, the spiral of conductive material 22 need not be substantially circular, and could be formed in triangular, square, hexagonal, octagonal or other cross-sectional patterns as appropriate. The substrate layers B, C, E, F, H and I are typically manufactured from silicon, polyester, polyimide, or some other similar substance upon which modern computer etching techniques can be used to imprint the spiral of conductive material 22. For example, the substrate laminate could be DuPont AP 9111 with AP9110 copper-clad polyimide film, with a cover insulation of DuPont LF0110 Acrylic adhesive on polyimide film. These layers also have heat conducting portions 26 provided at the corners of the layers and enveloping the holes 28 of the respective layers. The heat conducting portions shown are shaped in the illustrated manner simply to take advantage of the surface area available for this purpose. In addition to the holes provided at the corners of the substrate layers, small holes 30 are provided at key positions to enable connection of conductive material between the layers.
Although etching is described, other applicable means of securing or imprinting the spiraling conductive material 22 and/or the heat conducting portions 26. Such means may include laser or other techniques.
The assembled configuration of the electromagnetic assembly 10 is as follows (for the purposes this description, each layer has arbitrarily been designated with “a” for the top edge, “d” for the lower edge, and “b” and “c” for the side edges; with “b” being on the left and “c” on the right when looking in plan perspective at the etched surface of any substrate layer):
The ferromagnetic (magnetically active substance) core 50 is then positioned within the cylindrical cavity formed within the cutaway portions of the layers A-J and a current source can be applied to the cathode and anode. It should be evident that the stacked configuration of the spiral layers creates an effective coil around the core. Ferromagnetic substances include iron, Supermendur™, NuMetal™, Supermalloy™, and others. It should also be evident that the ferromagnetic core may be fixed relative to the assembly, thereby functioning as an electromagnet, or moveable within the assembly, thereby functioning as a solenoid.
In the illustrative example, three layers of spiral pairs have been provided, but this could be extended to many more pairs, or reduced to less pairs. Indeed, application of electrical current through the conductive spiral of a single etched substrate layer around a core will generate magnetic forces. In addition, the example described has back-to-back substrate layers carrying spirals to form pairs, but single substrate layers could be double-sided and have a spiral etched on both sides.
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In this manner a low-profile electromagnetic assembly is possible, either in a modular (expandable) or integrally manufactured device, which is capable of generating maximal magnetic fields without overheating and without cooling as such.
At this point in time, design specifics are somewhat limited by modern production methods, but as progressive miniaturization of devices and products continues, the potential for further reduced sizing is envisaged. For the purposes of illustration, where the substrate layer is 1 cm square and the central cutaway portion 20 for the core 50 is 1 mm in diameter, then that would allow for a spiral with an outer radius of just under 5 mm and an inner radius of just over 0.5 mm. With a spiral thickness of 0.0036 mm of conductor (1 oz. copper) and 0.0014 of insulation, this gives a turn thickness of 0.0050 mm. This would allow 900 turns around the core per spiral layer; or 9,000 turns total for a magnet of 5 spiral pairs.
The height of a 10 layer (three spiral pair substrate layer pairs, two heat conducting layers and two covers) electromagnet is less than 1 mm from top to bottom.
Different design ratios of size of the square layer, size of the hole, type of conductor material, size of conductor etched “wiring”, and distance between layers can be imagined, as can different types of spirals (square, triangular, other geometric shaped designs depending on the needs of the design and final shape desired) can be constructed as well, as well as different locations and techniques for placing the cathode and anode connections or layer-to-layer connections.
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20200126704 A1 | Apr 2020 | US |
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Child | 16723371 | US |