MULTI-LAYER PARALLEL PLANE INDUCTOR WITH FIELD CONTROL POCKETS

Abstract

A high current multi-layer parallel plane inductor is formed from a plurality of electrically conductive continuous layers folded back and forth to form a compact series inductor with each one of the plurality of electrically conductive layers having one or more layer pocket holes with layer edge notches forming one or more coil control pockets that generate a magnetic field pattern when alternating current is applied to the inductor.

Claims

1. A high current multi-layer parallel plane inductor comprising: a plurality of electrically conductive continuous layers folded back and forth and separated from each other by a separation gap height to form a compact series inductor, each one of the plurality of electrically conductive continuous layers having a layer height; and one or more coil control pockets, each one of the one or more coil control pockets formed from at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers, the at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers having a layer first edge notch or a layer second edge notch for selectively directing an alternating current supplied to each of the at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers to generate a magnetic field in each of the one or more coil control pockets, a magnetic field controlled by a configuration of the at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers forming each one of the one or more coil control pockets.

2. The high current multi-layer parallel plane inductor of claim 1 further comprising a first terminal inductor end manufactured as an integral feature to the end of a first layer of the high current multi-layer parallel plane inductor and a second terminal inductor end manufactured as an integral feature to the end of a final layer of the high current multi-layer parallel plane inductor.

3. The high current multi-layer parallel plane inductor of claim 1 wherein the pocket holes for alternating ones of the plurality of electrically conductive continuous layers have reversed the layer first edge notches and second edge notches.

4. The high current multi-layer parallel plane inductor of claim 1 wherein the at least one layer pocket hole comprises at least two layer pocket holes and the at least two layer pocket holes of each layer sequentially alternate between the layer first edge notch and the layer second edge notch for all of the plurality of electrically conductive continuous layers.

5. The high current multi-layer parallel plane inductor of claim 1 wherein the pocket holes for alternating one of the plurality of electrically conductive continuous layers have all the layer first edge notches in a first alternating layer and the layer second edge notches in a second alternating layer.

6. The high current multi-layer parallel plane inductor of claim 1 wherein the pocket holes forming at least one of the one or more coil control pockets is configured to produce a magnetic field when the alternating current is applied to the high current multi-layer parallel plane inductor.

7. The high current multi-layer parallel plane inductor of claim 1 wherein the pocket holes forming at least one of the one or more coil control pockets is configured to produce a sinusoidal-shaped magnetic field when the alternating current is applied to the multi-layer parallel plane inductor.

8. The high current multi-layer parallel plane inductor of claim 7 further comprising a load positioned at least partially within the sinusoidal-shaped magnetic field.

9. The high current multi-layer parallel plane inductor of claim 1 wherein the plurality of electrically conductive continuous layers are formed from a copper or a copper alloy.

10. The high current multi-layer parallel plane inductor of claim 1 wherein the layer height of at least one of the plurality of electrically conductive continuous layers is not equal to the layer height of a remainder of the plurality of electrically conductive continuous layers.

11. The high current multi-layer parallel plane inductor of claim 1 wherein the separation gap height between at least two of the plurality of electrically conductive continuous layers is different the separation distance between a remainder of the plurality of electrically conductive continuous layers.

12. The high current multi-layer parallel plane inductor of claim 1 further comprising a cooling apparatus externally enclosing the high current multi-layer parallel plane inductor.

13. The high current multi-layer parallel plane inductor of claim 12 wherein the cooling apparatus comprises: an exterior enclosure for containing the high current multi-layer parallel plane inductor and a cooling medium; a load passageway through the exterior enclosure for each one of the coil control pockets; and at least one cooling medium pump for circulating the cooling medium through the separation gap height between the plurality of electrically conductive continuous layers in the high current multi-layer parallel plane inductor.

14. The high current multi-layer parallel plane inductor of claim 12 wherein the cooling apparatus comprises: an exterior enclosure for containing the high current multi-layer parallel plane inductor encased in a magnesium oxide; and a load passageway through the exterior enclosure for each one of the coil control pockets and at least one through cooling medium passageway encased in the magnesium oxide.

15. A method of manufacturing a high current multi-layer parallel plane inductor comprising a plurality of electrically conductive continuous layers folded back and forth and separated from each other by a separation gap height to form a compact series inductor, each one of the plurality of electrically conductive layers having a layer height; and one or more coil control pockets, each one of the one or more coil pockets formed from at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers, the at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers having a layer first edge notch or a layer second edge notch for selectively directing an alternating current supplied to each of the at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers to generate a magnetic field in each of the one or more coil control pockets, the magnetic field controlled by a configuration of the at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers forming each one of the one or more coil control pockets, the method comprising: forming the plurality of electrically conductive continuous layers in a linear configuration from an electrically conductive solid block stock; forming the layer pockets and pocket side notches for each layer; and folding back and forth an inductor preform to produce the high current multi-layer parallel plane inductor.

16. The method of claim 15 wherein the layer pockets and pocket side notches of each layer in the electrically conductive solid block stock is formed by a CNC machined and one or more tools selected from machine tools, die presses, water jets and wire electrical discharge machining to reveal the elements of the high current multi-layer parallel plane inductor.

17. A method of generating a sinusoidal-like magnetic field with a high current multi-layer parallel plane inductor comprising a plurality of electrically conductive continuous layers folded back and forth and separated from each other by a separation gap height to form a compact series inductor, each one of the plurality of electrically conductive layers having a layer height; and one or more coil control pockets, each one of the one or more coil pockets formed from at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers, the at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers having a layer first edge notch or a layer second edge notch for selectively directing an alternating current supplied to each of the at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers to generate a magnetic field in each of the one or more coil control pockets, the magnetic field controlled by a configuration of the at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers forming each one of the one or more coil control pockets.

18. The method of claim 17 further comprises interacting a load at least partially formed from electrically conductive material placed at least partially for interaction with the sinusoidal-like magnetic field in at least one of the coil control pockets to electromagnetically heat, heat treat or anneal the load.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The foregoing brief summary, as well as the following detailed description of the invention, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings exemplary forms of the invention that are presently preferred; however, the invention is not limited to the specific arrangements and instrumentalities disclosed in the following appended drawings.

[0019] FIG. 1 is a diagrammatic representation of a top plan view of one non-limiting embodiment of a high current multi-layer parallel plane inductor of the present invention laid out linearly in eight layers before the layers are folded back and forth from each other and with two pocket holes on each layer and one type of alternating pattern of first edge notch and second edge notch associated with the pocket holes in each layer.

[0020] FIG. 2 is a perspective view of one non-limiting example of a high current multi-layer parallel plane inductor of the present invention showing top, right side and front view of the inductor where the inductor includes two magnetic field control pockets A and B in the high current multi-layer parallel plane inductor of the present invention. A magnetic field control pocket is also referred to as a coil control pocket.

[0021] FIG. 3 is a top plan view of the multi-layer parallel plane inductor illustrated in FIG. 2.

[0022] FIG. 4 is an interior sectional cut A-A of the multi-layer parallel plane inductor illustrated in FIG. 2.

[0023] FIG. 5 is a front elevation plan view of the multi-layer parallel plane inductor in FIG. 2.

[0024] FIG. 6 is a left side elevation view of the multi-layer parallel plane inductor in FIG. 2 illustrating opposing inductor terminations T1 and T2 that in this non-limiting example where inductor termination T1 is formed as an integral part of first (top) layer L1 and inductor termination T2 is formed as an integral part of second (bottom) layer L8.

[0025] FIG. 7 illustrates with arrows direction of instantaneous alternating current flow in one direction when alternating current is applied to the inductor terminations T1 and T2 in FIG. 2.

[0026] FIG. 8(a) and FIG. 8(b) illustrate use of one type of sequential inductor layer edge notching patterns for layer pocket holes for a non-limiting example of a high current multi-layer parallel plane inductor of the present invention where the inductor includes two magnetic field control pockets A′ and B′ wherein the at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers comprises two pocket holes in each one of the plurality of electrically conductive continuous layers and the two pocket holes on each layer sequentially having alternating first edge (LE) notch and second edge (RE) notch.

[0027] FIG. 9(a) and FIG. 9(b) illustrate use of another type of sequential repetitive two-layer notching of the present invention. In this example sequential inductor layer edge notching patterns for layer pocket holes for a non-limiting example of a high current multi-layer parallel plane inductor of the present invention is where the inductor includes two magnetic field control pockets A and B wherein the at least one layer pocket hole in each one of the plurality of electrically conductive continuous layers comprises two pocket holes in each one of the plurality of electrically conductive continuous layers and the two pocket holes on each layer sequentially having alternating layers with the first layer L1 having first edge RE notches and the second layer L2 having second layer edge LE notches. That is Layer L1 notches are on the same edge side that is the RE side and Layer L2 notches are on opposing side LE.

[0028] FIG. 10 illustrates one example of a vortex of current at each pocket produced by the ladder-like current pattern between layers and the positioning of the pocket hole edge cuts between layers.

[0029] FIG. 11 illustrates one non-limiting example of a typical solenoidal magnetic field pattern in dashed lines when instantaneous alternating current is applied to a multi-layer parallel plane inductor of the present invention.

[0030] FIG. 12(a) and FIG. 12(b) illustrate two non-limiting examples of a cooling apparatus used with a multi-layer parallel plane inductor of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0031] One non-limiting embodiment of a high current multi-layer parallel plane inductor 10 of the present invention is illustrated in FIG. 2. The multi-layer parallel plane inductor is also referred to as a multi-layer parallel plane induction heating coil. The multi-layer parallel plane inductor is formed from electrically conductive continuous layers folded back and forth and separated from each other by a separation gap height S that can vary between layers. The thickness (height) of each electrically conductive layer L1 through L8 can also be variable for example as illustrated by layer heights H1 and H2 in FIG. 4. Further each layer can be constructed so that the separation gap height and the layer height varies along the length of a single layer. The variable dimensions are adjustable in manufacturing of the inductor and can be varied to match inductor performance requirements for a particular application, such as a required operational temperature profile and required electrical impedance. By way of example and not limitation, an inductor of the present inductor formed from solid electrically conductive material is suitable for use in “high current” applications up to at least 100 amperes in alternating current at 50 volts.

[0032] In one method of manufacturing a multi-layer parallel plane inductor of the present invention stock material of suitable electrically conductive material can be machined by a computer numerical control (CNC) mill or by waterjet and then folded back and forth over itself with material handling equipment known in the art including one or more tools selected from machine tools, die presses, water jets and wire electrical discharge machining to reveal the elements of the high current multi-layer parallel plane inductor to form the multiple layers of a single inductor of the present invention without requirements for inductor brazed joints. FIG. 1 is a diagrammatic representation of one example of the present invention prior to folding back and forth along fold regions F1 to F8. FIG. 8(a) illustrates one example of the resulting high current multi-layer parallel plane inductor 11 resulting after the folding back and forth step has been completed in FIG. 1.

[0033] Solid copper or copper alloy is one non-limiting example of an electrically conductive material suitable for the electrically conductive continuous layers of the present invention. By way of example and not limitation 4×4 copper bar 10 inches long is suitable for milling and/or water-jetting formation of the electrically conductive continuous layers in one embodiment of the invention.

[0034] Each electrically conductive layer of the plurality of electrically conductive layers has one or more sets of pocket holes that control both the magnetic coupling and the temperature profile in a straight, tapered or cylindrically-shaped orientation, or other shapes or orientations as required for a particular application and thus are referred to as coil control pockets or magnetic field control pockets.

[0035] Each pocket hole is split (or notched) exclusively at one selective side edge of the electromagnetically conductive layer to mimic in an inductor of the present invention the electric current and the magnetic flux distribution that is produced with a comparative solenoidal coil. The pocket hole in each layer commutes from left edge (LE) notches (or splits) to right edge (RE) notches (or splits) between consecutive electrically conductive layers. The surface area of each electrically conductive layer is adjusted to allow natural air cooling, natural water cooling or forced convection cooling depending on a particular application's cooling requirements. Any current created by capacitive coupling and the electrodynamic voltage difference between the top and bottom layers of an inductor of the present invention is coaxial with a magnitude dependent upon coupling distance; voltage; and material properties and the geometry of the inductor and load (workpiece) being heated in or around at least one of the coil control pockets.

[0036] Alternative configurations of layer pocket holes with edge notches are utilized in different embodiments of the invention. Common to the following alternatives is that pocket edge notches reverse layer side edges between two adjacent layers. That is, between two adjacent layers, pocket holes with layer right side edge (RE or first edge) notches and pocket holes with layer left side edge (LE or second edge) notches in the first of the two adjacent layers will have companion pocket holes with reversed layer left side edge notches and companion pocket holes with reversed layer right side edge notches in the second of the two adjacent layers. This reversed pairing of adjacent companion holes is followed with all companion pocket holes on all layers that form one of the coil control pockets.

[0037] Companion pocket holes refers to all of the pocket holes on all layers that form one coil control pocket. For example FIG. 1 represents the multi-layer parallel plane inductor in FIG. 8(a) where pocket holes P1A on layer L1, P2A on layer L2, P3A on layer L3, P4A on layer L4, P5A on layer L5, P6A on layer L6, P7A on layer L7, and P8A on layer L8 are the eight pocket holes on the eight layers that are all companion pocket holes that form coil control pocket A′ in FIG. 8(a).

[0038] FIG. 1 illustrates a non-limiting configuration with two pocket holes per layer with the pair of companion pocket holes for coil control pockets A′ and B′ on opposing layer side edges. For example for top layer L1 pocket hole P1A has edge notch PN1A on the left edge (LE) of layer L1 and pocket hole P1B has edge notch PN1B on the right edge (RE) of layer L1. On the next layer L2 below top layer L1 when layer L2 is folded at fold F1 under layer L1, pocket P2A with pocket notch PN2A is companion to pocket P1A on Layer 1 with edge notch PN1A. The configuration in FIG. 1 is the same configuration shown in FIG. 8(a) for layer L1 and layer L2 (layer L1 is removed in FIG. 8(b) to make layer L2 visible) respectively after the layers in FIG. 1 have been folded back and forth underneath each other to assemble multi-layer parallel plate inductor 11 in FIG. 8(a). This two layer (L1 and L2) edge notch pattern repeats for two layer pairs L3 and L4; L5 and L6; L7 and L8 to form each of the two separate coil control pockets designated A′ and B′ in FIG. 8(a).

[0039] FIG. 2 illustrates another non-limiting configuration with two pocket holes per layer with the pair of companion pocket holes on the same layer edge (RE) of layer L1 and the pair of companion pocket holes on the opposing adjacent layer opposing layer side edges. This two layer (L1 and L2) edge notch pattern repeats for two layer pairs L3 and L4; L5 and L6; L7 and L8 to form each of the two separate coil control pockets designated A and B in FIG. 2 and FIG. 9(a) wherein the pocket holes for alternating ones of the plurality of electrically conductive continuous layers have layer L1 with right edge notches in the first alternating layer and L2 layer second left edge notches in the second alternating layer.

[0040] The stack of electrically conductive layers folded back and forth and the orientation of the layer pocket hole with layer edge notches forming coil control pockets make it possible to retain the magnetic field performance of a solenoidal coil while significantly improving the precision, repeatability and rapid design adjustments during the design, construction and testing cycles of an induction heating coil of the present invention. When a multi-layer parallel plane inductor of the present invention is manufactured by CNC machining or water jetting the coil control pockets with layer pockets and layer edge notching with subsequent wire electrical discharge machining (EDM) can form the layers from a solid electrically conductive block of material. Additionally, unlike CNC traditional stepped or helical type machined type inductors no subsequent brazing operations are required to create water-cooled closures for the inductor. These subsequent brazing operations in the prior art create dimensional distortions that are detrimental to inductor performance.

[0041] Electrically conductive layers may be designed and fabricated individually but act in a group to achieve a localized and precise induction heat pattern. The design and fabrication of each electrically conductive layer is independent from the design and fabrication of the remainder of electrically conductive layers in the assembly forming a multi-layer parallel plane inductor of the present invention. Because of this feature, each electrically conductive layer can be designed according to the level of electric power performance and cooling that is necessary at that a specific electrically conductive layer of the inductor. Despite each electrically conductive layer being designed and fabricated individually and independently from the remaining electrically conductive layers in the present invention, when the inductor is assembled all of the electrically conductive layers are electrically connected in series to approximate but improve upon the magnetic field performance of a traditional helical solenoidal inductor.

[0042] The stacked electrically conductive layers of a multi-layer parallel plane inductor of the present invention mimic the thermal performance of a conventional heat exchanger. The design of each electrically conductive layer can be modified and adjusted according to the available cooling system capabilities. Each electrically conductive layer acts as a heat sink that makes possible the cooling of an assembled inductor by natural or forced convection, or conduction mechanisms.

[0043] A multi-layer parallel plane inductor of the present invention has advantages of fabrication and adjustments repeatability. The characteristic electrically conductive layered configuration of a multi-layer parallel plane inductor of the present invention facilitates construction and modification of the inductor since the dimension of each specific circular cut for a layer pocket and each specific layer edge cut from each layer can be achieved with precise machining processes and tools.

[0044] A multi-layer parallel plane inductor of the present invention has advantages of eliminating prior art tubing pipe size limit. The thickness of each electrically conductive layer is independent from the thickness of the remainder of the electrically conductive layers forming the inductor of the present invention and the thickness can be adjusted according to the level of electrical power and cooling that is needed at a specific layer without affecting the inductor's heating pattern.

[0045] A multi-layer inductor of the present invention has advantages of eliminating matching frequency limit for proper operation of the power supply with which the multi-layer parallel plane inductor coil is used. The design of a stacked coil of the present invention is not limited to a certain number of turns. Therefore, an inductor of the present invention significantly facilitates the matching process with a power supply without affecting the heating pattern and the electromagnetic performance of the inductor coil itself.

[0046] When a multi-layer inductor of the present invention is energized, at one instant in time, alternating current travels from first end inductor terminal T1 to the second end inductor terminal T2 through each layer and follows a ladder-like pattern as indicated by the arrows in FIG. 7 using the embodiment of inductor 10 in FIG. 2 as an example. The ladder-like current pattern makes possible the change in direction of the electric current from left to right and viceversa for each layer as shown in FIG. 7. The inductor 10 in FIG. 2 has terminals T1 and T2 integrally formed with the first layer and the final layer respectively to facilitation connection to external circuit conductors such as cabling or buswork. Alternatively in some embodiments of the invention as shown in FIG. 8(a) separate inductor terminals may be connected to the ends of the first and final layers.

[0047] On the other hand in the example of the invention shown in the drawings, the direction of current at each single layer is changed between up and down and the opposite way around each of the layer pockets on a layer by interchanging the position of the layer edge notch for adjacent pockets on a layer. For example, in FIG. 8(a) as indicated by the arrows, first layer L1 current from terminal T1 travels from left to right down around layer L1 first pocket P1A with upper (layer left edge LE) pocket notch and then right to left up around layer L1 second pocket P1B with lower (layer right edge RE) pocket notch. In this example, in FIG. 8(b) (with layer L1 removed) the next layer L2 current travels from right to left down around L2 first pocket P2B with upper (layer left edge LE) pocket notch and then left to right up around layer L2 second pocket P2A with lower (layer right edge RE) pocket notch as it is shown in FIG. 8(b). This two-layer pattern of pockets and associated pocket edge cuts (notches) follow until terminal T2 connected to the left end of final inductor layer L8 is reached.

[0048] From the point of view of a load (workpiece) placed at least partially inside one of the coil control pockets when alternating current is supplied to an inductor of the present invention, the overall current motion and direction produced by the ladder-like current pattern between layers and the positioning of the pocket hole edge cuts (notches) between layers generates a vortex of current (92a through 92h for coil control pocket A′ and 94a through 94h for coil control pocket B′) at each pocket as illustrated in FIG. 10 for one example of the invention.

[0049] The linkage of magnetic flux that is generated by each one of the currents in the vortex produces the magnetic field distribution 96 that is shown by with dotted lines in FIG. 11 within and around coil control pockets A′ and B′ where the overall final distribution of the magnetic flux linkage between layers resembles the magnetic field dispersion that is produced by a solenoidal coil as illustrated in FIG. 11.

[0050] FIG. 12(a) illustrates one non-limiting method of cooling a high current multi-layer parallel plane inductor of the present invention by external cooling. A multi-layer parallel plane inductor of the present invention (for example inductor 10 or 11) is fixtured within sealed cooling enclosure 22. Suitable cooling medium such as water or oil can be contained within cooling enclosure 22 with the cooling system being either self-contained or a recirculating system. Arrows in FIG. 12(a) represent one preferable but not limiting direction of cooling medium through the high current multi-layer parallel plane inductor. The separation gaps between layers of the inductor provides a passthrough for the cooling medium to cool the layers. Quartz or other types of suitable enclosed passages 20a and 20b are used as load (workpiece) transport containers through coil control pockets (for example A or A′ and B or B′) without contact to the cooling medium since the entry and exit openings of the tubes are located outside of the top and bottom of the sealed cooling enclosure. The tubes or other types of workpiece transport apparatus may be any material that is suitably transparent to electromagnetic energy and the thermal environment.

[0051] Opposing ends of the inductor electrical terminals T1 and T2 can be isolated from the environment exterior to the cooling enclosure by a watertight seal through which power conductors can be connected to inductor terminals T1 and T2.

[0052] FIG. 12(b) illustrates an alternative method of cooling a high current multi-layer parallel plane inductor of the present invention by external cooling. The multi-layer parallel plane inductor of the present invention (for example inductor 10 or 11) is fixtured within sealed cooling enclosure 23 with a magnesium oxide composition encasing a multi-layer parallel plane inductor of the present invention inside the cooling enclosure. Cooling passages 24 (14 total in this example) provide a path for a cooling medium to flow through the sealed cooling enclosure 23 with load (workpieces) passing through quartz tubes 20c and 20d that may be configured similarly to the enclosed passages 20a and 20b in FIG. 12(a).

[0053] The present invention has been described in terms of preferred examples and embodiments. Equivalents, alternatives and modifications, aside from those expressly stated, are possible and within the scope of the invention. Those skilled in the art, having the benefit of the teachings of this specification, may make modifications thereto without departing from the scope of the invention.