Interlocking segmented coil array
Disclosed is a Segmented Coil Array (“SCA”) for use in rotary electromotive devices, such as motors and generators, which employ multiple coils operating within an axial gap magnetic structure. Individual conductor coils have offset circumferentially extending portions so as to allow interlocking of adjacent coils radially extending portions to form a circular array in which all of the coils' working conductors, which are those in the axial magnetic field, can be oriented in the same plane. This construction allows minimum magnet gap spacing, thus, maximizing the available magnetic flux. The resulting SCA may easily be commuted as a three-phase motor, actuator, or generator. The invention also provides a structure whereby multiple coil arrays and associated magnetic rotors may be alternately stacked in layers so as to further increase the total coil working area within a motor or generator of a given diameter.
This present invention relates generally to electrical generator or motor structures and more specifically to brushless electromotive devices of the type which employ a flat coil array or structure operating within an axially-oriented magnetic field having flux lines mostly perpendicular to the working conductor portion of the coils. This may include disc or pancake rotary motors as well as linear motors having such flat coils and magnetic structure.
BACKGROUND OF THE INVENTIONMotors employing disc-shaped coil armatures and brush commutation have been in use since the late 1950's. Brushless disc-type motors were later developed, employing rotating magnets, coil stators and electronic commutation. Such motors have been used in large numbers in audio and video tape recorders and computer disc drives. In such a motor, a magnetic rotor disc with alternating North/South pole pieces rotates above and/or below a plane containing several flat, stator coils lying adjacent one another. Current flowing in the conductor wires of the coils interacts with the alternating magnetic flux lines of the disc, producing Lorentz forces perpendicular to the radially directed conductors and thus tangential to the axis of rotation. While current flows through the entire coil, only the radial extending portions of the conductors (called the working conductors) contribute torque to the rotor. See, for example, U.S. Pat. Nos. 3,988,024; 4,361,776; 4,371,801; and 5,146,144. A variation of this arrangement is known in which the circumferential portions (nonworking conductors) of the wire-wound coils overlap each other. See, for example, U.S. Pat. Nos. 4,068,143; 4,420,875; 4,551,645; and 4,743,813. While this arrangement allows closer packing of the working conductors, it also requires that the gap between the rotor's magnets and flux return be about twice as thick as would be required for a single thickness of a non-overlapping coil, thus reducing the magnetic flux density and thus reducing the motor's efficiency.
SUMMARY OF THE INVENTIONIn view of the well known disadvantages in the above-mentioned prior art, it is an object of the present invention to provide a novel coil structure which more efficiently provides electromotive interaction between these new coils and the magnets within a rotary motor or generator of the type having a generally flat, ring-shaped coil structure and employing an axial gap magnet structure, such as in disc or pancake motors, while minimizing the thickness of the coil and magnet flux gap. Specifically, the invention relates to the construction and shape of the individual coils making up a coil array (circular or arc-shaped arrangement of coils) so as to allow interlocking or overlapping of multiple coils to form a thin disc coil array having double the density of, but not significantly more thickness than, non-overlapping coil arrays. The radially extending conductor portions of each coil all lie in a first plane while the circumferentially extending portions of each coil's conductors lie above and below said first plane.
Another object of the present invention is to maximize the total length of the working conductors within a circular coil array by overlapping three adjacent coils, so as to maximize the electromotive interaction for a motor or generator of a given diameter. For any given device diameter, conductor cross-sectional area, and magnetic flux density, this technique maximizes the torque which may be produced by a motor, or the voltage produced by a generator.
Another object of the invention is to provide a mechanism whereby multiple coil arrays may be closely stacked with corresponding magnetic rotors in alternating layers so as to increase the total coil area within a motor or generator of a given diameter. This increased coil area allows increased interaction between coils and magnets, improving the power conversion with the motor or generator.
While this specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is now regarded as the invention, it is believed that the broader aspects of the invention, as well as several of the features and advantages thereof, may be better understood by reference to the following detailed description of presently preferred embodiments of the invention when taken in connection with the accompanying drawings in which:
Referring now to the drawings and particularly to
As one example of a preferred embodiment,
A complete array of coils, affixed to each other and/or to a suitable structural material to form a coil platter (or an arc-shaped portion of the total coil platter) may be referred to as a Segmented Coil Array (“SCA”). A complete coil platter 50 is depicted in FIG. 5. (This particular illustration does not show the coil leads 34, 36 for clarity). This SCA platter 50 is composed of 48 individual coils 30 molded into an epoxy resin or other easily moldable material for support, which optionally may be further strengthened by also molding in layers of fiber reinforcing fabric. Since the inner 39 and outer 35 ends of each coil 30 lie in planes slightly above and below a first plane containing the working legs 37, the molded platter 50 has a thin center face 54 with a thicker inner rim 52 and outer Tim 56. Any other even numbers of coils other than 48 may also be used in an SCA, depending on the electrical or mechanical properties desired.
It has been discovered that for a given SCA diameter, the working length of the individual coils may be optimized for maximum torque production, in a motor, or voltage production, in a generator. This is done by making the coil working length 42% of the critical radius. This critical radius 58 is indicated in FIG. 5 and is defined as the distance from the center of the coil platter to the outermost points of the working length, before reaching the outer rim 56.
A cross section of a portion of the coil platter 50 of
In operation within a typical electromotive device, a circular coil platter 50 is exposed to an axially directed magnetic flux produced by a magnet rotor 11, i.e. flux perpendicular to the plane containing the coils' working lengths. One such way of providing this flux is illustrated in
As illustrated in
While the present invention has been described in terms more or less specific to preferred embodiments, it is expected that various alterations, modifications, or permutations thereof will be readily apparent to those skilled in the art. For example, the invention may be embodied in an electrical generator as well as a motor. Instead of a circular coil array, the coils of the invention may be formed into a linear array or a partial circle rather than a complete circular array. Therefore, it should be understood that the invention is not to be limited to the specific features shown or described, but it is intended that all equivalents be embraced within the spirit and scope of the invention as defined by the appended claims.
Claims
1. A segmented coil array for use in rotary electromotive devices with one or two magnet rotors, such as motors and generators, of the type which employ an axial gap magnetic structure, composed of an even multiple of individual wire-wound coils, each coil having substantially the same structure and size and comprising circumferentially extending base portions and radially extending side portions, the radially extending side portions and circumferentially extending base portions joined at their respective ends to define a generally trapezoidal shape: the coil array formed into a ring of partially overlapped alternating coils such that the radially extending side portions of each coil are coplanar.
2. The coil array of claim 1 wherein each individual coil has offsetting bends near each end of said radially extending side portions which cause the circumferentially extending base portions of the coil to lie outside the plane containing the radially extending side portions so as to allow partial overlapping of each coil by its two adjacent coils.
3. A segmented coil array, according to claim 2, in which each coil's circumferentially extending base portions and radially extending side portions define a space containing one radially extending portion from each of its two adjacent coils thereby doubling the density of the coil's working conductors.
4. The coil array of claim 1 wherein a plurality of the individual coils have offsetting bends near each end of said radially extending side portions which cause the circumferentially extending base portions of the coil to lie outside the plane containing the radially extending side portions so as to allow partial overlapping of each coil by at least two adjacent coils.
5. A segmented coil array, according to claim 1, in which the individual coils are over-molded with a moldable material to form a ring of suitable structural integrity and heat tolerance.
6. The segmented coil array of claim 5 in which the moldable material is epoxy.
7. The segmented coil array of claim 5 additionally comprising layers of fiber reinforcing fabric.
8. A segmented coil array, according to claim 1, herein the coils are oriented to form a linear array.
9. A segmented coil array, according to claim 1, wherein the coils are oriented to form a partial ring.
10. The coil array of claim 1 A segmented coil array for use in rotary electromotive devices with one or two magnet rotors, such as motors and generators, of the type which employ an axial gap magnetic structure, composed of an even multiple of individual wire-wound coils, each coil having substantially the same structure and size and comprising circumferentially extending base portions and radially extending side portions, the radially extending side portions and circumferentially extending base portions joined at their respective ends to define a generally trapezoidal shape: the coil array formed into a ring of partially overlapped alternating coils such that the radially extending side portions of each coil are coplanar, wherein the individual coils are formed such that the radially extending side portions of a coil have a smaller cross-sectional electrical conductor area than at least one of the circumferentially extending base portions.
11. The coil array of claim 1, wherein the multiple individual wire-wound coils A rotary electromotive device comprising two rotors, at least one of which comprises a magnet rotor, said two rotors sandwiching therebetween a segmented coil array to provide two axial magnetic gaps, said segmented coil array being composed of an even multiple of individual wire-wound coils, each coil having substantially the same structure and size and comprising circumferentially extending base portions and radially extending side portions, the radially extending side portions and circumferentially extending base portions joined at their respective ends to define a generally trapezoidal shape, the coil array being formed into a ring of partially overlapping alternating coils such that the radially extending side portions of each coil are coplanar, said coils being affixed to each other to form a coil platter, having a central axis and known inner and outer diameters, in which the radially extending coil portions are the working conductors, and the working length of said conductors is being approximately 42% of the distance between the central axis of the coil platter and the outer diameter of the coil's working length, thereby optimizing the array for maximum torque, when used as a motor, or voltage production, when used in a generator.
12. The coil array of claim 1, wherein the coil array is operably located in a rotary electromotive device, such as a motor or generator, the motor or generator having alternating layers of magnetic material to produce an axial gap magnetic structure, and further having several additional coil arrays arranged in layers of electromagnetic coil arrays which are stacked so as to further increase the total coil area within said electromotive device, each layer of coil structure operating in a separate axial magnetic flux gap formed by the layers of magnetic material.
13. The device of claim 12 wherein said magnetic material is a disc shaped permanent magnet rotor affixed to a rotatable shaft.
14. The device of claim 12 wherein said magnetic material is a disc shaped electromagnet rotor affixed to a rotatable shaft.
15. A segmented coil array for use in rotary electromotive devices, such as motors and generators, of the type which employ an axial gap magnetic structure, comprising an even multiple of identically shaped individual wire-wound coils, each coil comprising circumferentially extending base portions, and radially extending side portions joined at their respective ends to form a trapezoid shape, each side portion having offsetting bends at each end of said side portion adjacent to each base portion so that said base portions lie in a plane parallel to said side portions; the coil array formed by arranging a first set of coils into a ring with side portions being adjacent, and overlapping a second set of coils such that the radially extending side portions of each set of coils are all coplanar and the offsetting bends of alternate coils are oriented in different directions so that the base portion of the first set of coils are parallel to the base portions of the second set of coils.
16. A segmented coil array, according to claim 15, in which the individual coils are over-molded with a moldable material to form a ring of suitable structural integrity and heat tolerance.
17. The segmented coil array of claim 16 in which the moldable material is epoxy.
18. The segmented coil array of claim 15 additionally comprising layers of fiber reinforcing fabric.
19. The coil array of claim 15 A segmented coil array for use in rotary electromotive devices, such as motors and generators, of the type which employ an axial gap magnetic structure, comprising an even multiple of identically shaped individual wire-wound coils, each coil comprising circumferentially extending base portions, and radially extending side portions joined at their respective ends to form a trapezoid shape, each side portion having offsetting bends at each end of said side portion adjacent to each base portion so that said base portions lie in a plane parallel to said side portions; the coil array formed by arranging a first set of coils into a ring with side portions being adjacent, and overlapping a second set of coils such that the radially extending side portions of each set of coils are all coplanar and the offsetting bends of alternate coils are oriented in different directions so that the base portions of the first set of coils are parallel to the base portions of the second set of coils, wherein the individual coils are formed such that the radially extending side portions of a coil have a smaller cross-sectional electrical conductor area than at least one of the circumferentially extending base portions.
20. The coil array of claim 15, wherein the multiple A segmented coil array for use in rotary electromotive devices, such as motors and generators, of the type which employ an axial gap magnetic structure, comprising an even multiple of identically shaped individual wire-wound coils, each coil comprising circumferentially extending base portions, and radially extending side portions joined at their respective ends to form a trapezoid shape, each side portion having offsetting bends at each end of said side portion adjacent to each base portion so that said base portions lie in a plane parallel to said side portions; the coil array being formed by arranging a first set of coils into a ring with side portions being adjacent, and overlapping a second set of coils such that the radially extending side portions of each set of coils are all coplanar and the offsetting bends of alternate coils are oriented in different directions so that the base portions of the first set of coils are parallel to the base portions of the second set of coils and slightly above and below the co-planar radially extending side portions, the individual wire-wound coils being affixed to each other to form a coil platter, having a central axis and known inner and outer diameters, in which the radially extending side portions include a working length, and the working length is approximately 42% of the distance between the central axis of the coil platter and the outer diameter of the coil's working length, thereby optimizing the array for maximum torque, when used in a motor, or voltage production, when used in a generator.
21. In a method of manufacturing a stator for an axial gap electrical machine, the steps comprising
- spiral winding a flat ribbon conductor into a plurality of coils having radially extending sides and circumferential ends in substantially the same structure and size around a central void;
- forming at least one portion of the plurality of spiral wound coils to offset their circumferential ends from their radially extending sides by machining the radially extending sides of said at least one portion of coils to provide said offset of their circumferential ends; and
- arranging the coils into a circumferentially extending stator with their radially extending sides lying generally coplanar by overlapping said at least one portion of coils in the arrangement with their radially extending side portions lying in the central voids of the remaining portion of the unformed coils and with their offset circumferential ends overlapping the circumferential ends of the remaining portion of the unformed coils.
22. A segmented coil array for use in rotary electromotive devices of the type which employ an axial gap magnetic structure, composed of a plurality of individually wound coils comprised of flat ribbon conductor, each coil comprising circumferentially extending base portions and radially extending side portions, the radially extending side portions and circumferentially extending base portions being joined at their respective ends to define a generally trapezoidal shape; a portion of individually wound coils being machined to offset their circumferentially extending base portions from their radially extending side portions, the coil array being formed into a ring of partially overlapped alternating coils such that the radially extending side portions of each coil are coplanar.
23. The coil array of claim 22, wherein the individual coils are formed such that the circumferentially extending base portions of a coil have a larger cross-sectional area than one of the radially extending side portions.
24. The coil array of claim 22 wherein at least one circumferentially extending base portion has less electrical resistance than the radially extending side portions.
25. The coil array of claim 22 wherein each individual coil has offsets near each end of said radially extending side portions which cause the circumferentially extending base portions of the coil to lie outside the plane containing the radially extending side portions so as to allow partial overlapping of each coil by its two adjacent coils.
26. A coil array, according to claim 25, in which each coil's circumferentially extending base portions and radially extending side portions define a space containing one radially extending portion from each of its two adjacent coils thereby doubling the density of the coil's working conductors.
27. A coil array, according to claim 22, in which the individual coils are over-molded with a moldable material to form a coil platter with structural integrity and heat tolerance.
28. The coil array of claim 27 in which the moldable material is epoxy.
29. The coil array of claim 27 comprising at least one layer of fiber reinforcing fabric incorporated in the coil platter.
30. The coil array of claim 22, wherein the multiple individual wound coils are affixed to each other form a coil platter, having a central axis and known inner and outer diameters, in which the radially extending coil portions are the working conductors, and the working length of said conductors is approximately 42% of the distance between the central axis of the coil platter and the outer diameter of the coil's working length.
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Type: Grant
Filed: Apr 28, 2000
Date of Patent: Jan 24, 2006
Assignee: Kinetic Art & Technology Corporation (Greenville, IN)
Inventors: Roy Lee Kessinger, Jr. (Greenville, IN), Paul Anthony Stahura (South Bend, IN), Paul Eric Receveur (New Albany, IN), Karl David Dockstader (Prospect, KY)
Primary Examiner: Karl E. Tamai
Attorney: Brinks Hofer Gilson & Lione
Application Number: 09/561,826
International Classification: H02K 1/22 (20060101); H02K 3/04 (20060101);