Abstract:
Halbach array electric motor with substantially contiguous electromagnetic cores, comprised of rotors and stators usually configured as permanent magnet and electromagnetic Halbach arrays respectively, wherein the enhanced magnetic forces of said Halbach arrays are focused between said rotors and stators.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation of Nonprovisional application Ser. No. 14/014,153 filed Aug. 29, 2013. The contents of U.S. Ser. No. 14/014,153 are expressly incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This inventive subject matter relates to electromagnetic devices such as electric motors and generators which employ Halbach arrays. This inventive subject matter further relates to novel Halbach array electric motors and devices with electromagnetic cores; Generally the purpose of implementing Halbach arrays in electric motors is to maximize efficiency, increase power or to reduce size and weight by harnessing the enhanced magnetic forces inherent in the Halbach effect. 
         [0004]    2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98. 
         [0005]    U.S. Pat. No. 8,513,849 including U.S. Pat. Nos. 8,183,731 and 7,352,096 are very similar, and discloses generators where permanent magnets are mounted on discs but spaced relatively far apart such that it is unlikely to provide a strong Halbach array effect. The electromagnets used are non-Halbach. None of the drawings in these patents depict a valid Halbach array sequence and therefore these devices likely cannot produce a Halbach effect. 
         [0006]    U.S. Pat. Nos. 6,906,446 and 6,858,962 are almost identical, and discloses a generator featuring a permanent magnet Halbach array on the stator, but the rotor is non-Halbach and therefore the rotor does not provide the advantages of the Halbach effect. 
         [0007]    U.S. Pat. No. 7,598,646 discloses a bicycle wheel equipped with a Halbach array, where the motive force for the bicycle wheel are two external arches comprised of electromagnets that are arranged in Halbach Array formation, on either side. However, the electromagnetic cores of these electromagnets are physically separated and this substantially negates the Halbach effect. Electromagnets configured as such will exhibit a severely disabled Halbach effect. 
         [0008]    U.S. Pat. No. 8,009,001 discloses a means of concentrating Halbach Arrays to create a ‘hyper’ Halbach using permanent magnet arrays. The invention of U.S. Pat. No. 8,009,001 does not disclose use of electromagnets in Halbach Array configuration. 
         [0009]    Launchpoint Technologies developed a closed electric hub motor for unmanned aerial vehicles (UAVs) that uses two backing plates equipped with permanent magnets in Halbach array sequence sandwiching a non-Halbach array stator that has three phase Litz wire winding. This reference does not disclose use of electromagnets in Halbach Array configuration. 
         [0010]    None of the devices of the prior art disclose use of electromagnets or electromagnets in Halbach Array sequence in which the Halbach effect is effectively harnessed such that enhancement and cancellation are comparable to the effects seen with prior art permanent magnets in Halbach Array sequence. 
       BRIEF SUMMARY OF THE INVENTION. 
       [0011]    The inventive subject matter of this disclosure describes novel Halbach array electromagnetic devices with electromagnetic cores in Halbach array sequence. These novel electromagnetic devices may also include permanent magnets in Halbach array in addition to at least one Halbach array of electromagnets. These devices further include configurations wherein enhanced magnetic forces of the Halbach arrays are paired. Applications include an in-wheel electric motor as one sample implementation thereof. Generally the goal of implementing Halbach arrays in electric motors is to maximize efficiency, increase power or to reduce size and weight by harnessing the enhanced magnetic forces inherent in the Halbach effect; otherwise an ordinary unenhanced motor would suffice. The embodiments disclosed herein utilize electromagnets arranged in Halbach Array configuration having magnetic flux conduits that provide substantial contiguity between adjacent electromagnetic cores in order to fully enable the Halbach effect and achieve increases in efficiency and power that have not been attained by prior art devices employing conventional electromagnets. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS. 
         [0012]      FIG. 1A  Cut-away view of dual Halbach array motor in an in-wheel embodiment with cylindrical rim. 
           [0013]      FIG. 1B  Cut-away view of dual Halbach array motor an in-wheel embodiment with cylindrical rim and stator with center-mounting. 
           [0014]      FIG. 2A  Cut-away view of dual Halbach array motor an in-wheel embodiment with funnel-shaped inner rim. 
           [0015]      FIG. 3A  Orientation of Halbach array permanent magnets and Halbach array electromagnetic cores. 
           [0016]      FIG. 4A  An embodiment with a spoke-less alloy wheel. 
           [0017]      FIG. 5A  Detailed close-up view of the electromagnets with horizontal and vertical cores showing fork-like flux conduits extending from the horizontal cores to the vertical cores. 
           [0018]      FIG. 6A  Codes used for winding magnetic coils around the electromagnets. 
           [0019]      FIG. 7A  A dual Halbach array motor in an in-wheel embodiment with connections to a 3-phase motor controller. 
       
    
    
     REFERENCE NUMERALS IN DRAWINGS 
       [0000]    
       
           9  Magnetic surfaces 
           97  Vertical electromagnets in stator 
           99  Horizontal electromagnets in stator 
           101  Permanent magnets arranged in Halbach Array sequence (of the rotor) 
           102  Electromagnets arranged in Halbach Array sequence (of the stator) 
           103  Alloy wheel 
           104  Three-phase cables and optional Hall sensor cables from the stator 
           105  Stator mounting 
           204  Epoxy adhesive or filling 
           205  Alloy flanges 
           301  Orientation of Halbach array permanent magnets 
           302  Orientation of Halbach array electromagnets 
           303  Attachment point for the stator mounting 
           401  Thin section bearings 
           402  Bearing linkages and mounting points 
           403  Spoke-less alloy wheel 
           501  Magnetic coils 
           502  Vertical electromagnets of the stator 
           503  Horizontal electromagnets of the stator 
           504  Fork-like prongs on the horizontal cores 
       
     
       DETAILED DESCRIPTION OF THE INVENTION 
       [0040]    A first embodiment is disclosed having dual Halbach array arrangement in an in-wheel electric motor. The device is comprised of magnetic surfaces  9  which are further comprised of permanent magnets or electromagnets in Halbach array configurations. The dual Halbach array is comprised of permanent magnets arranged in Halbach array sequence  101 , paired with electromagnets with substantially contiguous cores, likewise arranged in Halbach array sequence  102 . Compared to ordinary permanent magnets or electromagnets with equal polar fields (i.e. 50% north pole and 50% south pole), in a Halbach array, the magnetic field on one side of the array is augmented or enhanced (the enhanced side) for example, to greater than 97%, while the opposite side (cancelled side) exhibits cancellation or reduction of the magnetic field to less than 3%. Analogously the enhanced side of a Halbach array sequence of electromagnets with substantially contiguous cores as shown may also be called the active side and the cancelled side may also be called the inactive side. However, the identity of active and inactive sides of a Halbach array sequence of electromagnets is not permanently fixed as in the case with permanent magnets arranged in Halbach array sequence. In some embodiments incorporating vertical and horizontal electromagnets with substantially contiguous cores arranged in Halbach array sequence, active and inactive sides may switch or interchange positions by reversing polarity of only the horizontal electromagnets. The terms, enhanced side, cancelled side, active side, and inactive sides, which are used in this written description, should be understood to conform to lexicography as defined immediately above. It should also be noted that what is meant by “substantial contiguity” is achieved by providing physical contact between adjacent electromagnet cores using magnetic flux conduits which physically connect adjacent cores to each other. The magnetic flux conduits may be configured as fork-like prongs, protrusions, or other suitable configurations. 
         [0041]      FIG. 1  shows one embodiment of the present invention with a dual Halbach array electric motor positioned in-wheel. This design can be made by modification of a common automotive alloy wheel  103 , and lining a section of the inner rim&#39;s circumference with permanent magnets arranged in a Halbach array sequence  101  to form a rotor. The permanent magnets are securely affixed onto the alloy wheel  103 , applying epoxy adhesive  204  to the surface and via alloy flanges  205  that are bolted, welded, or built into the alloy wheel. A stator is paired with the rotor, the stator comprised of electromagnets that are arranged in Halbach array sequence  102 , the electromagnet Halbach array having horizontal electromagnets  503  ( FIG. 5A ) adjacent to vertical electromagnets  502 . The horizontal electromagnets  503  are equipped with fork-like prongs that slip through gaps in the magnetic coils  501  of the adjacent vertical electromagnets. By establishing substantial contiguity between the electromagnetic cores, the transmission of magnetic flux between cores, which would normally be blocked by the energized coils, is maximized thereby enabling a strong Halbach array effect in the stator. 
         [0042]    The magnetic coils  501  of each vertical electromagnet  502  are wound according to the arrangement shown in  FIG. 6A . The same wiring instructions will also be used for the horizontal electromagnets  503 . There are many other wiring options such as Star/Wye, Delta, LRK, etc., and the choice substantially affects the characteristics, such as speed, peak torque, and current drawn, of the electric motor. For this first embodiment, the ‘star or wye’ winding for a brushless DC motor is used. 
         [0043]    There are three separate wiring phases, A, B, and C. Winding is clockwise if the letter is capitalized, and counter clockwise if the letter is in lower case in  FIG. 6A . For example, AaBbCc means: For Phase ‘A’/Wire  1 , wind the tooth/core  1  clockwise, then continue to tooth/core  2  and wind it counter clockwise. For Phase ‘B’/Wire  2 , wind the tooth/core  3  clockwise, then continue to tooth/core  4  and wind it counter clockwise. For Phase ‘C’/Wire  3 , wind tooth/core  5  clockwise, then continue to tooth/core  6  and wind it counter clockwise. This will continue until all the cores are properly wound. 
         [0044]    Once the cores are properly wound the three phase wires A, B, and C will be soldered together to complete the ‘star or wye’ winding scheme. Then the other end of the same combined three phase wires A, B, and C for both vertical  502  and horizontal  503  electromagnets will be separately connected to the A, B, and C terminals on the 3-phase motor controller shown in  FIG. 7A . 
         [0045]    Sensorless commutation using Texas Instruments™ InstaSpin™ controllers is used in this first embodiment. Hall sensors, while optional in this example, are recommended if a fine degree of control is required at low rotational speeds. 
         [0046]    One orientation of the Halbach array permanent magnets  301 , in relation to the orientation of the Halbach array electromagnets  302  can be found in  FIG. 3A , which shows the orientation for 32 Halbach array permanent magnets (essentially 16 primary poles on the outer ring), and the orientation of each of the 36 Halbach array electromagnetic cores (effectively 18 vertical primary electromagnetic cores on the inner ring). This Halbach array arrangement with arrays  301  and  302  oriented as shown can be described as having a dual Halbach array arrangement with facing paired enhanced sides. This configuration focuses all of the enhanced magnetic flux at the airgap (i.e. the space between the stator and rotor) to maximize power and efficiency.  FIG. 3A  also shows a variation of the first embodiment with the stator mounting having a central attachment point for the stator mounting  303 .  FIG. 3A  also shows the source of the detailed close up view of the electromagnets shown in  FIG. 5A . It should also be noted that for Halbach arrays arranged in a circular fashion in a rotor or stator, the “horizontal” magnets are oriented with magnetization essentially parallel to the circumference of the circle formed by the magnets. Because the outer edge of a circle cannot form a perfectly straight line, the directions of magnetization of the horizontal magnets are actually parallel to lines tangent to the circle. See for example, horizontal electromagnets  99  shown in the embodiment depicted in  FIG. 3A . The “vertical” magnets are arranged with magnetization pointing outward or inward along lines extending radially from the center of the circle as shown for electromagnets  97 . The terms, “horizontal” and “vertical” are therefore used as would be customary and would be familiar to a person of ordinary skill in the art and does not imply that the adjacent horizontal and vertical magnets are arranged with magnetization perfectly perpendicular to each other in but instead, substantially perpendicular according to the circular geometry of the device. For embodiments involving linear devices adjacent horizontal and vertical magnets would be arranged with magnetization perpendicular to each other. It should be further noted that ordinary electric motors in general use only vertically oriented permanent magnets and electromagnets.  FIG. 3A  illustrates horizontal and vertical permanent magnets and electromagnets oriented in Halbach array sequences. Vertical and horizontal electromagnets in Halbach array sequence are also shown in  FIG. 5A . 
         [0047]    The entire set of electromagnets arranged in Halbach array sequence (i.e. the stator)  102  including the full length of the three-phase cables and optional Hall sensor cables from the stator  104  will generally be coated several times with insulating and waterproofing polymers and water phobic solutions similar to that offered by Liquipel™ and HzO™. 
         [0048]    The completed Halbach array stator  102  is then placed on a stator mounting  105  that is shaped to match the inner rim of the alloy wheel  103 , which is then affixed via the stator assembly&#39;s attachment point  303  to the vehicle&#39;s front or rear suspension system, typically at the steering knuckle assembly or hub carrier. The attachment for the stator mounting is offset more towards the vehicle&#39;s body so that a conventional brake rotor and caliper and suspension system can still be used. The same attachment point can be positioned closer to the body of the car to accommodate the brake rotors and calipers, as shown in  FIG. 1A  for an alloy wheel  103  with a cylindrical rim and  FIG. 2A  for an alloy wheel  103  with a funnel shaped rim. If the brakes are positioned inboard, attachment point for the stator  303  will be at the center of the rim width, as shown in  FIG. 1B . This configuration will decrease unsprung weight and to improve handling even further. 
         [0049]    Another embodiment variation is made by using thin section bearings  401  mounted along the inner rim of a spoke less alloy wheel  403 . These thin section bearings  401  are joined via linkages that also serve as mounting points  402  for the vehicle&#39;s suspension system. The permanent magnets of the rotor  101  are then positioned between the outer rings  407  of the thin section bearings  401 , and the electromagnets of the stator  102  are positioned between the inner rings  409  of the thin section bearings  401 , as shown in  FIG. 4A . Equivalent alternatives to thin section bearings may be used varying with design. These would include but are not limited to hydrostatic, hydrodynamic, magnetic, rolling contact bearings, sleeves, journals, sliding faces or paired grooves which may be lined with or fabricated from ceramic or other low friction materials. Brakes similar to that made by Brembo™ for use on large sports bikes are not shown in the diagram for the sake of clarity. 
         [0050]    Another embodiment for the present invention can be made by simply to inverting the configuration of the first embodiment using a contiguous core electromagnetic Halbach array as the outer stator, and a permanent magnet Halbach array as the inner rotor. Likewise, aside from the preceding outward and inward radial embodiments, another example is for the Halbach stator to project its force axially, which will then be paired with an axially-oriented permanent magnet Halbach array in the rotor. 
         [0051]    Yet another embodiment is adapted for connection to an AC motor controller rather than DC. The wiring of the electromagnetic cores (which are still configured as Halbach arrays) will be changed to near- 90  degree phases to achieve fields that are near sinusoidal (and near cosusoidal), to create a three-phase synchronous AC contiguous core Halbach array electric motor. 
         [0052]    An interesting embodiment of the present invention is to fully harness both sides of the contiguous core Halbach array electromagnet (i.e. a stator), since this can easily be done by separately wiring the vertical and horizontal Halbach array electromagnets&#39; phases to dual channel motor controllers, or multiple controllers working simultaneously via a bus or signal network. As an example, by sandwiching the stator between two concentric permanent magnet rotors (which are Halbach arrays) and by connecting armatures to both rotors, alternating vertical movement can be provided while radially rotating in either direction, with a considerable speed and torque. These external and internal Halbach rotors, if not interconnected can also be made to function independently albeit sequentially, uniquely controlled via a single Halbach stator. These novel configurations open up a multitude of possibilities for new applications or devices in the field of pumps, transmissions, clutches, couplings, drill heads, robotics, etc.