A radial gap motor/generator has a thin annular array of magnets mounted for rotation to a stator in a radially spaced relation to at least one thin annular induction structure fixed to a stationary stator may be air or liquid cooled. Further, the motor has at least radial gap between a magnetic core and the array and may include multiple gaps and multiple annular induction structures to increase the overall power density of the system.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to brushless rotary electrical motor/generator structures for producing an output voltage or mechanical power output in the form of rotational torque such as for use in rotating the wheel of a vehicle and propelling the vehicle; and more specifically, to a radial gap motor/generator wherein at least one thin annular array of magnets is mounted for rotation to a rotor in radially spaced relation to at least one thin annular induction structure fixedly arranged on a stationary stator. Even more particularly, the present invention is directed to a cooling arrangement or structure for transferring heat build-up and cooling the induction structure during operation of the motor/generator.

2. Description of Prior Art

In general, brushless electrical motors may be termed “axial gap” or “radial gap.” In each, magnets are mounted on a rotor and an induction structure, or electrical coils, are mounted on a stator. In the axial gap motor, the coils and magnets are in juxtaposed relation with one another on respective co-axial circles and in respective axially spaced planes. In the radial gap motor, the coils and magnets are in radially spaced juxtaposed relation with one another in respective co-axially disposed cylindrical planes.

Axial gap motors employing coil armatures and brush commutation have been in use since the late 1950's. In a conventional (brushed) DC motor, the brushes make mechanical contact with a set of electrical contacts on the rotor (called the commutator), forming an electrical circuit between the DC electrical source and the armature coil-windings. As the armature rotates on axis, the stationary brushes come into contact with different sections of the rotating commutator.

Brushless disc-type axial gap motors were later developed, employing rotating magnets, coil stators and electronic commutation. In such brushless motor, the electromagnets do not move; instead, the permanent magnets rotate and the armature remains static. This gets around the problem of how to transfer current to a moving armature.

The brushless axial gap motor offers several advantages over brushed DC motors, including higher efficiency and reliability, reduced noise, reduced maintenance, longer lifetime (no brush erosion), elimination of ionizing sparks from the commutator, and overall reduction of electromagnetic interference. The maximum power that can be applied to a brushless motor is exceptionally high, limited almost exclusively by heat, which can damage the coils and affect the strength of the magnets.

Accordingly, an arrangement for obviating the deleterious effects of heat and temperature build-up in the brushless motor during operation thereof would be desirable and is an object of this invention.

Brushless axial gap 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.

In view of the these disadvantages in the above-mentioned prior art, Kessinger et al. U.S. Pat. No. 5,744,896, issued Apr. 28, 1998, the specification of which is specifically incorporated herein in its entirety, discloses a motor which employs an axial gap magnetic structure wherein complementary faces of the stator and rotor are disposed in axially spaced relation and each receives, respectively, a flat array of coil winding segments and a flat array of permanent magnets, the segments and magnets of which being arranged in angularly spaced side-by-side relation and extending radially relative to the rotor axis of rotation. The coil winding segments are alike and each is generally trapezoidal and forms a ring shaped structure and the segments overlap with one another to form a thin planar electromagnetic structure. Electrical wires are wound about the coil structures and the longer legs (or sides) of the trapezoidal shape form the working portions of the coil windings.

Kessinger proposed that the individual coils making up a coil array be flat and rectangular in shape to form a thin disc coil array so as to maximize the electromotive interaction for a motor/generator of a given diameter and maximize the torque, which may be produced by a motor, or the voltage produced by a generator.

While believed useful for the purposes then desired, certain problems are believed to remain in an axial gap arrangement. During operation and rotation of the rotor, an outward radial shearing force is placed on the securement between the permanent magnets and the rotor face. Because of these forces and possible adverse effects of heat build up during continued use, the magnets may break free. Additional bonding material may be needed to overcome such situation, possibly resulting in increased cost and size of the structure.

Further, Kessinger proposes that the individual flat shaped rectangular coil structures closely abut one another and that individual coils be overmolded with a moldable material to form a suitable ring of suitable structural integrity and heat tolerance. However, such configuration suggests that some mechanism be provided to tolerate but not transfer heat from the coils during performance their electrical motor function.

Accordingly, an object of this invention is provision of a brushless radial gap motor/generator structure wherein the respective arrays of magnets and coil windings are separated by a radial gap, wherein to minimize the outer dimensions of the resulting structure.

An object of this invention is provision of a brushless radial gap motor/generator structure that effectively obviates adverse effects occasioned by rotation of the rotor.

OBJECTS OF THE INVENTION

Another object of the present invention is the provision of specially configured coil windings that overlap with one another and assemble to form a thin annular cylinder of a given diameter and substantially uniform thickness to provide electrical induction, and a cooling structure in the form of an array of angularly separated cooling pipes that nest within angular axially extending gaps formed by and between successive of the coil windings wherein to cool the coil winding segments during operation of the motor/generator, allow increased interaction between coils and magnets, and improve the power conversion with the motor or generator. The cooling pipes may comprise what are called heat pipes and are vapor phase heat transfer mechanisms that can transport large quantities of heat with a small difference in temperature between hotter and cooler interfaces. In connection with the radial gap motor according to this invention, the heat pipe can transport heat against gravity by an evaporation-condensation cycle.

A still further object of this invention is the provision of an electric drive system for a motor vehicle, which is drivingly connected to the inner rim of at least one, and if desired, the inner rims of each respective vehicle wheel, and which eliminates conventional chassis mounted power systems, drive trains and hub mounted wheel-axle power train systems.

SUMMARY OF THE INVENTION

In a preferred embodiment according to this invention there is provided an apparatus for propelling a vehicle, the vehicle including an axle and a wheel structure for mounting to the axle, the apparatus comprising: an electric motor for rotating the wheel and driving said vehicle, the motor configured for connection to an inner surface of said wheel structure and including a stationary member with a thin annular induction structure and adapted to be fixed to the axle, and a rotary member with a thin annular magnetic structure configured for securement to the wheel structure in a manner that the induction and magnetic structures are co-axially disposed, juxtaposed with one another, and radially spaced from one another, the induction structure including angularly offset first and second sets of first and second coil segments wherein each coil segment has two lateral side portions that extend axially and the coil segments overlap in a manner that the lateral side portions of each successive coil segment of the first set is overlapped, respectively, by the lateral side portions of the next preceding and succeeding coil segment of the second set, and each of the lateral side portions are angularly spaced and disposed in a common cylindrical plane.

Preferably, the induction structure is encircled by the magnet structure and a cooling structure is provided for cooling the induction structure, the cooling structure including a plurality of linear cooling/heat pipes, the pipes extending axially with a linear cooling/heat pipe being disposed in heat transfer relation between each successive pair of linear side portions.

Further, in another preferred embodiment according to this invention, a brushless radial gap DC motor comprises: a stator and a rotor mounted for co-axial rotation about the stator, a succession of rectangular shaped coil windings disposed around the stator in angularly spaced side-by-side overlapped relation with one another and in a manner to form a thin substantially continuous cylindrical induction structure, and a succession of permanent magnets disposed around the rotor in angularly spaced side-by-side relation and in a manner to form a thin substantially cylindrical magnetic structure, the mounting being such that the cylindrical magnetic and induction structures are juxtaposed in respective cylindrical planes and the structures separated by a single cylindrical annular gap.

In a still further embodiment hereof, a brushless radial gap DC motor has an induction structure comprising a succession or series of rectangularly-shaped coil windings disposed around a stator in angularly spaced side-by-side overlapping relation. This configuration forms a thin, substantially continuous cylindrical induction structure. The motor further includes a series or succession of permanent magnets disposed around both the outside and the inside diameters of the induction structure to form a dual-faced cylindrical magnetic structure.

The magnetic structure and the induction structure are mounted to the rotor and stator in juxtaposition in respective cylindrical places such that the structures are separated by two cylindrical gaps.

Preferably, the magnetic structure is in encircling relation about and around the induction structure and the coil windings comprise a succession of first coil winding segments that overlap a like succession of second coil winding segments.

In some applications, the motor structure is comprised of iron, for concentrating and directing magnetic flux. In other applications, and as an option for reducing weight, the DC motor structure is ironless or comprised of a magnetically permeable material.

Preferably, the brushless radial gap DC motor further comprises means for cooling and transferring heat build up in the succession of coil windings arising from electrical current passing through the coil windings and operation of the motor, the means for cooling including a plurality of cooling tubes or pipes interposed and nested relation between and in cooling relation with respective successive pairs of overlapping coil windings.

Preferably, the cooling pipes are configured as heat pipes that operate on the principle of the vapor phase transfer of heat from the coil windings. Removal of heat is achieved by changing the phase of a coolant in the heat pipe from a liquid into a vapor phase and routing the vapor to an area remote from the heated source, where it is cooled and converted back to a liquid.

Optionally, the cooling tubes or pipes may transfer heat from the coils to an ambient air or otherwise cooled suitable heat sink remote from the motor-stator, preferably off-site from an open or inner surface of the stator.

Preferably, the succession of permanent magnets is arranged in a Halbach array. In some applications, the magnets may be arranged into a standard N/S/N/S pole array.

Preferably, the coil windings comprise alternating sets of first and second coil segments, the segments being differently configured for nested interfitment with one another and each segment having an electrical conductor wire coiled about and into a generally rectangular ring shaped structure, wherein successive coil winding segments of the first set are juxtaposed and overlap with successive pairs of coil winding segments of the second set with the two sets being arranged to form the thin cylindrical annular induction structure.

In the arrangement, the longer sides of the rectangular shaped coil segments extend axially and the shorter ends extend circumferentially, the longer sides form a common cylindrical plane, and the overlapped sets of coil segments form a succession of axially extending angular recesses or gaps dimensioned to receive a respective of the cooling/heat pipes.

The means for cooling further includes a heat sink, the heat sink mounted to the stator and to at least one of the succession of cooling pipes. The cooling pipes extend axially, are disposed in the cylindrical plane defined by the coil segments, and nested in close proximity to a pair of the longer side portions of adjacent of the overlapped coil segments.

In an important option, the cooling/heat pipes are comprised of an electrically conductive material and shunted to provide a closed loop and serve not only in the heat transfer capacity. Further, by being in the same cylindrical plane defined by the longer axially extending legs of the coil segments, the heat pipes provide the generation of magnetic flux and electromotive force in the presence of the rotating magnetic (Halbach) array.

In some applications, the cooling pipes are in communication with one another, such as via a manifold, and form a single reservoir and fluid pump system to communicate cooling fluid to each of the cooling pipes and each of the succession of cooling pipes. According to this aspect of the invention, the fluid path may comprise a closed loop and an open loop.

In another preferred embodiment according to this invention there is provided a brushless DC motor, comprising:a. a stator having an outer surface and a cylindrical annular induction structure juxtaposed in encircling relation around the outer surface, the induction structure comprising first and second sets of wire wound coil segments disposed in respective cylindrical planes with successive coil segments of the first set being angularly offset from and juxtaposed with pairs of successive adjacent pairs of coil segments of the second set, the coil segments having a long dimension disposed axially and the overlapped portions forming a succession of angularly separated axial recesses,b. a rotor having a cylindrical inner surface and a cylindrical annular permanent magnet structure juxtaposed in encircling relation around the inner surface,c. means for mounting the rotor and stator to one another for relative coaxial rotation about a center axis and in a manner that a cylindrical annular radial gap separates the induction structure from the magnet structure, andd. a succession of cooling tubes or heat pipes, said tubes and heat pipes being nested, at least in part, in successive of the axial recesses for cooling heat build up in the coil segments.

Preferably, in these motors, the nested coil segments and cooling pipes/tubes are encapsulated in a heat transferring epoxy.

In another preferred embodiment according to this invention there is provided a brushless DC motor, comprising:a. a stator, said stator including a cylindrical induction structure,b. a rotor, said rotor including a cylindrical magnet structure,c. means for mounting the rotor to the stator for coaxial rotation relative thereto and relative to a common central axis of rotation thereof, said mounting spacing the magnet structure from the induction structure and in a manner that a thin uniform cylindrical annular radial gap is formed between the structures of the rotor and stator, andd. means for cooling the induction structure, said means for cooling including a succession of heat transferring cooling tubes or pipes being nested, at least in part, in angularly spaced relation in said induction structure.

Preferably, the means for cooling comprises a vapor phase tube, wherein said tube is linear and comprised of an electrically conductive material, such as copper or aluminum.

In yet another preferred embodiment according to this invention there is provided an improved brushless DC motor, the motor including a rotor mounted for rotation about a stator and an arrangement of electrical wire wound coils and permanent magnets that operate to convert electric current into mechanical power, the improvement comprising:a. said rotor and stator, respectively, including a cylindrical inner face and cylindrical outer face,b. means for mounting the rotor and stator in a manner that the inner and outer faces are centered in coaxial relation on a common central axis and separated by an annular gap and the inner face of said rotor is mounted for rotation relative to outer face of said stator,c. said wire wound coils include a first set of identically shaped first coil segments and a second set of identically shaped second coil segments, each said coil segment being generally thin, rectangular and ring shaped and including first and second side portions and first and second end portions, the side portions of each of the coil segments being substantially of the same length and forming a respective first plane and the end portions of the first set of coil segments extending at an acute angle from the side portions thereof and to the respective first plane, andd. means for mounting the wire wound coils around the outer face of the stator in a manner that the coil segments of each set are angularly spaced from one another and the coil segments of the first set are arranged in alternating and overlapping relation with the coil segments of the second set, the first and second side portions of the coil segments extending axially with their axes parallel to and centered on the axis of rotation and wherein the first and second side portions of each coil segment of the first set is overlapped with the second and first side portions, respectively, of the next succeeding and preceding coil segments of the second set, the end portions of each of the coil segments of the first set of coil segments enabling the coil segments to overlap and position the side portions in angularly spaced side by side relation.

Desirably, the present invention provides a relatively light-weight, high torque radial gap motor/generator that obviates the problems of overheating during operation. Importantly, the arrangement may be used with a variety of rotary electromotive devices.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings,FIGS. 1-9andFIG. 10, respectively, illustrate preferred embodiments of a brushless, ironless, synchronous, DC, single radial gap, electric motor or generator, according to this invention. As used herein, the apparatus of each embodiment is referred to as an electric motor, which produces mechanical power output in the form of rotational torque.

The electric motor of each embodiment includes a stator or stationary structure, a rotor mounted for rotation relative to the stator in a manner that a surface of the rotor is separated from a corresponding surface of the stator by a radial gap to form a cylindrical annular gap therebetween, a succession of permanent magnets, or annular magnet structure, is mounted to a surface of the rotor for rotation therewith and in juxtaposed relation with an electromagnetic induction structure mounted to a surface of the stator.

In the embodiments described herein, the rotor and magnet structure rotate about the induction structure disposed about the stator, the magnets being on an inner surface of the rotor and in encircling relation with the induction structure. In other applications, the magnet and induction structure could be reversed, with the stator and induction structure encircling the rotor and magnet structure, the stator and rotor mounted on a common axis, and the rotor mounted for rotation within the stator.

Further, the motor of each preferred embodiment includes a respective cooling arrangement for cooling the induction structure of the motor during operation thereof.

Depending on the application, the electric motor may be stationary or used to power and propel a wheeled vehicle, such as a motorcycle, motor vehicle, bus, golf carts, and the like. The conventional motor vehicle is propelled by the energy of an internal combustion engine being transmitted via a drive train to the axles and/or one or more wheel structures, whereby the drive train rotates the wheels.

In a preferred embodiment, according to this invention herein, the electric motor ofFIGS. 2-9is used to propel a motor vehicle in what may be referred to as a “motor-in-wheel” system. In this application, the internal combustion engine and drive train are eliminated and at least one wheel structure of the vehicle is mounted to the outer surface of the rotor.

Referring toFIG. 1, a motor vehicle is generally indicated by the reference number12and includes a chassis14having forward and rearward ends16and18, lateral sides20and22, and four respective wheel structures24connected to the chassis for rotation relative thereto by respective axle or power train structure.

A motor10according to this invention is fitted into a wheel structure24. The mounting of the motor10to the wheel structure is not shown as being understood by those skilled in the art. Additionally, a motor in wheel arrangement is described in U.S. Pat. No. 6,851,496, issued Feb. 8, 2005, to the Applicant herein, the disclosure of which is incorporated herein in its entirety.

In general, however, as will be described in greater detail herein below, the motor10includes a rotor34having an outer surface56band a stator32having a bearing sleeve50coaxial with the rotor. The outer surface is fitted to an inner surface of the wheel structure and the bearing sleeve50is fitted to the axle associated with the wheel structure.

The motor vehicle chassis14is suitably configured to mount an electrical power source in the form of a conventional DC battery26and a vehicle management controller28. The management controller28is in communication with an on board computer and is adapted to receive, compare, and send signals substantially simultaneously to a motor in wheel, and direct the battery to supply electrical energy as needed.

Supplying electricity to the DC motor10, according to this invention, and which will be described in detail, generates an electrical induction that operates on the poles of the magnet structure to generate an EMF that is tangent to the rotor, producing torque on the rotor, causing the rotor to turn and the wheel to rotate, thereby propelling the vehicle.

Referring toFIGS. 2 and 3, the first embodiment of a brushless DC electric motor10according to this invention includes a stationary member, or stator30, an annular electrically conductive induction structure32fixedly mounted about the stator, a rotating member, or rotor34, and a thin annular magnet structure in the form of an array of permanent magnets36fixedly mounted to the rotor34for rotation therewith. The rotor34and stator30are coaxial to one another and centered on a common central geometrical axis “A” and the rotor is mounted for rotation about the stator and the axis “A”. The magnet structure or array of permanent magnets36is in circumposed encircling relation with the induction structure32and the magnets and induction structure are radially separated from one another by a single, generally thin, uniform annular or radial gap “G”.

The induction structure32is in electrical circuit relation with the battery26and the control or operating member, which is shown herein as the management controller28.

The stator30comprises a generally cylindrical cup-shaped stator frame38, the stator frame including a cylindrical wall40that has outer and inner cylindrical surfaces40aand40b, respectively, centered on the central geometrical axis “A” and rearward and forward radial end walls42and44. The stepped radial end walls42and44are axially spaced, radially stepped mirror images of one another, and cooperate with the cylindrical wall40to form an outwardly opening channel46and an inwardly opening chamber48. The radial end walls42and44, respectively, terminate in radial outward ends42aand44a.

The rearward radial end wall42terminates in an inward radial end portion42bthat is configured to form both an annular outwardly opening channel50for receiving a roller bearing52and a cylindrical sleeve for mounting to a suitable stationary support, such as to the axle of the vehicle12when used in conjunction with the “motor-in-wheel” arrangement described hereinabove.

As will be described hereinbelow, the outwardly opening channel46is configured to receive the induction structure32, and at least in part, heat receiving elements of the motor cooling structure, and the chamber48is configured to house, at least in part, heat dissipating elements of the motor cooling structure.

The rotor34comprises a generally cylindrical cup-shaped rotor frame54, the rotor frame including a cylindrical wall56that has cylindrical inner and outer surfaces56aand56b, respectively, centered on the central geometrical axis “A”, axially spaced radial end walls58and60, which extend radially inwardly from the opposite axial ends of the cylindrical wall56and form the rearward and forward ends of the rotor frame, a pair of axially spaced radial walls62and64, which are disposed between the end walls58and60and extend radially inwardly from the inner surface56aof the cylindrical wall56, and radially inwardly opening channels66,68, and70. The rearward end wall58has an inward radial end portion58afixedly attached to the roller bearing52whereby to mount the rotor frame54to the stator frame38for coaxial rotation relative thereto and the axis “A”.

The inwardly opening channels66and70form annular recesses that receive the outer radial end portions42aand44aof the stepped rearward and forward end walls42and44of the stator frame38and coaxially center and align the inwardly opening channel68in encircling juxtaposed relation with the outwardly opening channel46of the stator frame38.

Preferably, as shown by the phantom lines inFIGS. 3 and 10, the rotor and stator walls60and44cooperate to form a bearing support52in a manner similar to that shown to the right, thereby forming a symmetrical stabilized support structure.

The annular array of permanent magnets36comprises a succession of separate permanent magnets that are disposed in side-by-side abutting relation to one another with the respective North and South poles of successive magnets being adjacent one another to form a continuous generally cylindrical thin magnet structure centered on the axis “A”. While many magnets are known and available, a preferred magnet is the Neodymium-Iron-Boron magnet, known for its providing high power in a small size.

Preferably, the permanent magnets are formed into what is termed a Halbach array. While the Halbach array will not be described in detail herein as being understood by those skilled in the art, the arrangement of permanent magnets increases the magnetic flux on one side of the device while reducing the flux to near zero on the other side.

Preferably, an elastomeric material “E” is used to bond and fixedly mount the permanent magnets and/or Halbach array against the inner surface56aof the cylindrical wall56of the rotor frame54.

Rotation of the rotor34operates to apply outward radial forces against the magnet structure36, forcing the array and respective magnets thereof radially outwardly and against the inner wall56aof the rotor, thereby obviating the development of axial shearing forces. Desirably, the positioning of the magnet structure against the inner surface of the rotor channel results in a less expensive elastomer being needed, less elastomer to position the magnets, and a reduction in the weight of the assembly formed.

As shown inFIG. 4, the induction structure32is comprised of a first set of coil segments72and a second set of coil segments74with the coil segments72and74of each set, respectively, being disposed, respectively, in the channel46of the stator frame38and in concentric first and second “cylindrical planes” coaxially centered with one another, the axis “A” and about the outer surface40aof the stator wall40. The coil segments72and74are generally rectangular and form a ring shaped structure having a central open area and include an electrical wire that is successively wound into the rectangular shape and in encircling relation with the central area.

The coil segments72and74of the first and second sets, respectively, are equiangularly spaced from one another in a manner that each coil segment of one set is radially spaced and angularly positioned in overlapping relation with a successive pair of coil segments of the other set. As shown inFIG. 4, for illustration, each segment72and74comprises an electrically conductive wire wound into the desired shape. The ends of the conductive wires are connectible in electrical circuit relation to the management controller28. The connection of the wire ends is not shown as being understood by one skilled in the art.

Referring toFIGS. 4-8, the induction structure32and coil segments72and74are shown in greater detail. The coil segments72and74are similar but differ in shape in a manner to allow successive coil segments of one set to overlap with successive pairs of adjacent coil segments of the other set as well as to define equiangular axially extending gaps or recesses “S” to receive cooling structure needed to transfer heat from the coil segments during operation of the motor. The coil segments72are shown “blackened” for clarity to show overlapped fitment with the coil segments74.

The coil segment72is generally planar and includes two long legs or sides72aand72band two short legs or ends72cand72d, the respective pairs of legs being conjoined at right angles to one another to one another to form a rectangular ring shaped structure having a central opening73. The legs and sides are generally linear with the length of the short legs72cand72dbeing less than the length of the long sides72aand72b.

The coil segment74in plan is generally rectangular shaped and includes two long legs or sides74aand74b, two short legs or ends74cand74d, and extenders74eand74fthat conjoin the long sides to the ends74cand74dto form a ring shaped structure having a central opening73. The legs, sides, and extenders are generally linear with the length of the ends74cand74dbeing less than the length of the long sides74aand74band substantially the same length as the short ends72cand72d. The sides74aand74bform a first plane, the ends74cand74dform a second plane, and the extenders74eand74fare at an angle θ to the first plane and position the planes to be generally parallel to one another. In some applications, as shown inFIG. 6, the extenders are also at an acute angle “α” to the second plane.

The coil segments72and74are such that the lateral separation between the long sides72aand72bof the coil segment72and long sides74aand74bof the coil segment74are substantially the same.

Referring toFIG. 4, illustrating an assembly of the inductions structure32, the set of coil segments74are disposed about the stator surface40ain equiangularly spaced relation to one another with the short legs or ends74cand74dbeing proximate to the outer surface40aof the stator frame38, and the set of coil segments72are disposed above and about the coil segments74in equiangularly spaced relation to one another with the short and long legs thereof spaced from the short and long legs of the coil segments74. Importantly, lateral side portions of successive coil segments72of one set of coil segments are angularly offset with successive pairs of lateral side portions of adjacent coil segments74therebelow and which form the other set of coil segment.

Referring toFIGS. 5 and 6, when assembled to the stator frame38, the coil segments72and74are overlapped with the long sides of the coil segments72and74axially extending, in a common cylindrical plane centered on the axis of rotation “A” and forming a repeating equiangularly spaced sequence, such as72a,74b,74a,72b,72a,74b,74a, and so on. The lateral width of the coil segments is such that the overlapped long leg side portions divide the central open areas71and73of the coil segments72and74into three equiangular axial recesses “S” that receive cooling pipes to transfer heat from the coil segments during operation.

Referring toFIGS. 6 and 7, the angled extenders74eand74fat the opposite axial ends of the sides74aand74bof the coil segments74enable the opposite axial end portions of the coil segments72to be lowered about the corresponding axial end portions of adjacent coil segments74therebelow in manner that all of the long side legs are coplanar. This is important because while current flows through the entire coil winding of each coil segment, only the longer length sides72a,72b,74a, and74bcontribute torque to the rotor34. This overlapping arrangement provides a denser packing of the conductors, improves magnetic flux path, and concentrates the motor windings.

Depending on the application, the extenders may be disposed in planes that are perpendicular to the first plane (defined by the sides74aand74b) and the second plane (defined by the ends74cand74d).

Referring toFIG. 3andFIGS. 5-8and according to an important feature of this invention, a cooling structure76is provided for cooling the coil segments72and74during operation as illustrated, the cooling structure includes a plurality of angularly spaced axially extending pipe portions78and associated heat sinks80.

The heat sink80is specifically associated with a heat pipe and includes an elongated coolant vapor delivery pipe and wicked fluid return path82that, at least in part, extends through the cylindrical wall40of the stator frame38, is disposed in the chamber48, and has opposite ends thereof in operating communication with opposite respective ends of a cooling pipe78associated therewith to wick the cooling fluid from the heat sink to the cooling pipe and return heated coolant vapor to the associated heat sink. The fluid delivery pipe82is reversely bent to form a series of undulations and is disposed in the chamber38and, depending on the application, may be provided with a plurality of thin cooling fins84to further assist in heat transfer.

The pipe portions78extend from the stator frame and into the channel46, and extend axially between the radial walls42and44.

Important to the invention herein, the pipe portions are disposed in respective of the axial gaps “S” formed between successive of the longer side legs72a,74b,74a,72b,72a, and so on. The legs of the coil segments72and74are dimensioned such that each of the long legs is juxtaposed with and in close parallel proximity to a cooling pipe78.

Preferably, and referring toFIG. 8, an epoxy bonding material “E” is disposed within the channel46to fix the coil segments72and74of the induction structure32and the pipe portions78of the cooling structure relative to one another and to the channel46of the stator frame. Preferably, the epoxy has good heat transfer properties to rapidly and uniformly effectuate transfer of heat build-up from the coil segments to the pipe portions.

Further, referring toFIGS. 7-8, the dotted lines indicate the epoxy “E” that is used to fix the coil segments and pipe portions relative to one another. Further, inFIG. 6, the reference numbers R1, R2, and R3, respectively, refer to a radius extending from the axis “A” to the cylindrical outer surface40aof the stator channel46, the “cylindrical plane” formed by the long sides74aand74bof the succession of respective coil segments74, and the “cylindrical plane” formed by the long sides72aand72bof the succession of respective coil segments72and74.

According to this invention, and referring toFIG. 10, the cooling structure76preferably comprises a heat pipe178, which comprises a hermetically sealed hollow tube180and includes a working fluid and a wick structure (not shown). As known in the art, the heat pipe is a vapor phase heat transfer mechanism that can transport large quantities of heat with a very small difference in temperature between hotter and colder interfaces. Inside the heat pipe, at the hot interface, formed by the body of epoxy heated by the coil segments, the fluid turns to vapor and the gas naturally flows and condenses on the cold interface. The liquid falls or is moved by capillary action back to the hot interface to evaporate again and repeat the cycle. To enhance heat transfer, as an option, cooling fans181may be provided.

Preferably, and according to this invention, the heat pipe is comprised of a thermo-conductive material such as copper, or possibly aluminum. The electrically conductive copper material of the pipe portions extend substantially the entire length of the long sides of the coil segments and cooperate to further develop magnetic flux, tangential EMF forces, and axial force to the rotor. The heat pipe thus forms a continuous loop whereby the additional forces and flux created thereby opposes the magnetic field generated by the magnet structure to create a magnetic cushion between the rotor and the stator on which the rotor rotates. This same cushion effect can be achieved with a loop of conductive material regardless of it functioning as a heat pipe.

In applications employing a circulatory liquid cooling system, and referring toFIG. 10, the heat sinks are in communication with one another via a manifold200, which in turn is in communication with a single reservoir and a secondary fluid pumping system and cooling device such as a radiator.

Referring now toFIG. 11, there is depicted therein a further embodiment hereof, generally, denoted at210. According to this embodiment, a rotor212has a pair of magnets214,216mounted therein. An induction structure218such as that described hereinabove is disposed intermediate the magnets214,216. Thus, a first cylindrical annular gap220is defined between the magnet214and the induction structure218and a second gap222is defined between the magnet216and the induction structure218, as shown. The magnets and induction structure are juxtaposed in respective cylindrical planes and are separated by the cylindrical annular or radial gap.

A heat pipe224is mounted to a stator226in the manner described hereinabove and is in fluid communication with the induction structure, again, as described above. Bearings228,230are, also, provided.

InFIG. 12, there is shown a modified dual gap motor310. Here, a manifold312, for circulating cooling fluid, e.g. a cooling liquid, is in fluid communication with the induction structure314. In all other respects this embodiment is the same as that ofFIG. 11.

Referring now toFIGS. 13 and 14there is depicted therein a further embodiment of the present invention. According to this embodiment, there is provided a multiple gap motor, generally, denoted at410.

According to this embodiment there is provided a motor411which comprises a rotor412and a stator414which are arrayed in a substantially circular manner, as shown.

Disposed about the circumference of the motor are a plurality of inner ring magnets416and a plurality of outer ring magnets418. The inner ring magnets and outer ring magnets are axially displaced by a sufficient distance to accommodate a coil assembly or induction structure420therebetween.

The coil assembly420is disposed between the inner ring magnets and the outer ring magnets, as shown. The coil assembly comprises a core422. The core422comprises a magnetic material such as iron or the like.

Windings424are disposed about the core422. The windings are preferably copper windings although other conductive materials may possibly be used such as aluminum, silver, carbon fiber or the like. The windings may be of any suitable construction from conventional wound wire of different cross sections for general application, to film coil and printed circuit windings for more specialized motor applications. Similarly, the windings themselves may take any suitable configuration such as non-overlapping, overlapping, layered, etc.

As shown in the drawing a first inner gap426is provided between the inner ring magnets and the coil assembly. Similarly, a second gap427is provided between the outer ring magnets and the coil assembly.

The entire rotor-assembly is rotatably mounted to a stator frame428for rotation therearound. The stator frame428is secured to the coil assembly or induction structure via a bolt assembly430which projects through suitable apertures in the stator frame and into the core422.

A plurality of bearings434are circumferentially disposed about the core422and windings424which are attached to the stator frame that together constitute the stator assembly to enable the rotor to rotate thereabout.

The rotor-stator motor assembly hereof can be deployed in connection with the motor and wheel drive system as shown in U.S. Pat. Nos. 6,948,578 and 6,851,496, the disclosures of which are hereby incorporated by reference.

In this regard and referring now toFIG. 15there is shown the mounting of the present motor to a shaft that is used to orbit the motor and wheel assemblies as described in the aforementioned U.S. patents. The stator assembly428is secured to a bracket or steering knuckle440through suitable mounting means to secure the motor thereto. The steering knuckle mounted is disposed for orbiting motion or action in a well known conventional manner and is powered through a linear actuator442, as disclosed in the aforementioned U.S. patents.

Referring now toFIGS. 16-18there is depicted therein a further embodiment of the present invention. According to this embodiment the electric motor/generator is of modular construction. As shown, the motor/generator, generally, denoted at510includes a stator512which comprises a shell or frame514. A rotor516including a frame518is rotationally mounted to the stator in well know manner.

The rotor516is mounted for rotational movement about the stator by the use of bearings520.

As shown, the stator514houses an induction structure522which, preferably, comprises a plurality of substantially C-shaped cores524. Each core is fabricated, preferably, from iron or other suitable material. A plurality of windings,525similar to those described hereinabove, is disposed about the core and cooperates therewith to define as induction structure527.

As a C-shaped structure, a gap526is provided between opposed ends or legs of the “C”, as shown. Disposed within the gap or opening is a magnet528. The magnet is mounted to the rotor via suitable means such as an annular ring532which is integrally formed with the frame518and projects laterally interiorly therefrom and into the interior of the “C” as shown.

The magnet528may be bonded to the shape523through the use of an epoxy or other suitable adhesive or other suitable means.

As shown inFIG. 18each of the modules are equilaterally circumferentially disposed within the stator frame and are secured thereto through suitable mounting means via bolts or the like (not shown). When functioning as a motor, the rotor is driven via a driver (not shown) to cause the rotor516to rotate on the bearings520. As a generator, as the magnets rotate, they create electricity at the induction structure which is drawn through the lead wires connected to the coil windings.

By being constructed in a modular manner the weight of the motor. Generation is greatly reduced along with concomitant reduction in cost.

It should be noted that the utilization of a dual radial gap enables an increase in magnetic flux density that is acted upon by the induced magnetic field created by passing current through the coils to produce the force that results in the rotational motion of the rotor. It is to be appreciated that a plurality of coil assemblies and magnets, i.e. two or more, can be used herein with plural gaps to further increase the magnetic flux density.

Although the present invention has been defined in terms of an automobile or other vehicle, it is to be noted that the present invention can be used with respect to rotationally powered devices such as wheelchairs, marine environments, aviation and, when employed as a generator, for power generation such as in windmills.

Depending on the application, the pipes and heat sinks80and the manifold200may be air cooled, and the cooling enhanced by provision of cooling fins.

In this fluid-cooling system, while not shown, a fluid pumping system is provided to pump cooling fluid in a circulatory manner to each of the cooling pipes and/or into the manifold to pump cooling fluid to each of the succession of cooling pipes. According to this aspect of the invention, the fluid path may comprise a closed loop and an open loop.

It should be noted, although not shown, that in some applications it may be possible to reduce the weight of the motor by eliminating the iron core and by having the coils wound around a spool with an air core fixed in position in an armature frame and subsequently attached to the stator frame.

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.

As a generator, and as shown inFIG. 13it is possible that the number of windings around each of the core segments may vary. For example, there may be X number of windings around one coil segment and Y number of windings around another coil segment each connected to its own electric circuit. In such an arrangement a first group of windings is wound around the outboard pole of the core which a second group of windings is wound around the inboard pole. Although the number of wire turns within each individual grouping is identical, the coil groupings differ in the number of wire turns within the individual coils in the first grouping are different than those in the second. The two individual groupings of coils produce two separate distinct voltages, when the generator rotor is rotated relative to the stator. The difference between the two voltages unique to each of the separate circuits is a function of the difference between the numbers of wire turns wound within the individual coils in each grouping. The grouping with the greater number of turns within its coils will produce a current at a higher voltage than the grouping with the lower number turns. In this manner, various voltages may be drawn off from the device when functioning as a generator.

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.