FIELD OF INVENTION

The present invention related to horizontal axis rotor axial flux miniature wind turbine, in particular axial flux miniature wind turbine with magnetically levitated horizontal axis rotor.

BACKGROUND ARTS

Current horizontal axis rotor, axial flux wind turbine typically uses bearings to support rotor. Drawback of current design is that it has bearing rotor contact friction, preventing wind turbine from generating power at very low wind speed. Therefore, problem to be solved is to eliminate rotor contact friction, so that invented wind turbine can generate power at very low wind speed with high efficiency.

DEFINITION OF TERMS

“Axial flux”: means the lines of magnetic flux that pass through the coils of wire, travel along the "axis" of the rotating motion.

“Rotor”: is a rotating component coupled to the rotor of axial flux wind turbine.

“Stator”: is a stationary component coupled to the support frame assembly of axial flux wind turbine. “Permanent magnet”: is a magnet that retains its magnetic properties in the absence of an inducing field or current.

“Air core coil”: is a type of insulated wire winding coil that has no ferrite core inside the coil. “Permanent magnet stator”: is a stator comprising a plate substrate and a plurality of permanent magnets mounted therein.

“Air core coils rotor”: is a rotor comprising a plate substrate with a plurality of air core coil mounted therein.

“Rotor solidity” is the ratio of total blade area to total swept area.

SUMMARY OF THE INVENTION

The following summary is provided to facilitate an understanding of some of the innovative features unique to the embodiments present and is not intended to be a full description. A full appreciation of the various aspects of the embodiments can be gained by taking the entire specifications, claims, drawings, and abstract as a whole.

SUBSTITUTE SHEET (RULE 26) It is the primary object of the present invention to provide horizontal axis rotor wind turbine that start to generate electrical power at minimum operating wind speed of at least 1.2m/s.

In order to achieve this primary object of having minimum operating wind speed of at least 1.2m/s, the present invention propose a novel design of magnetic levitation to the rotor, without the use of bearings to support the rotor as seen in prior arts which has significant bearing contact friction while operating at a very low wind speed. The magnetic levitation to the rotor is achieved by having ferromagnetic tapered tip members on both end portions of the rotor shaft, which attracted to the permanent magnets that are mounted on both windward side and leeward side of the support frame assembly. The magnetic levitation to the rotor shaft minimizes the rotating mechanical frictions to a near zero value. As such, a very low starting torque generated by a very low wind speed such as 1.2m/s that passing through the rotor blades is sufficient to rotate the rotor and electrical power is then generated.

It is another object of the present invention to increase the rotor rotational speed at very low wind speed, because the fact that generated electric power is proportional to the square of the rotor rotational speed. In order to increase the rotor rotational speed, the rotor structure needs to have a higher aerodynamic lift force and a lower moment of inertia. One way to reduce moment inertia is to use rotor components which have a lower density and weight. However, on the other hand, in order to ensure that the rotor structure can withstand strong wind without getting any damage, the selection of lower density rotor components need to have a high modulus of elasticity MOE and thus high stiffness.

It is another object of the present invention to increase the rotor solidity up to an optimum condition whereby the starting torque generated by wind speed of at least 1.2m/s enable rotor rotating that start producing electric power.

In order to achieve the objects just described, the present invention disposed the novel use of bamboo skin as rotor blades. The bamboo skin blades are characterized in high aerodynamic lift force, high stiffness and low material density.

The preferred embodiment of the present invention comprising two permanent magnet stators, an air core coils rotor coupled with a plurality of blades, a support frame assembly and two wires for external electrical output connection, wherein the rotor comprising electrically-conductive and ferromagnetic tapered tip members on both end portions, wherein the plurality of blades are made from bamboo skin, wherein the alternating current circuit generated out from the air core coils rotor is electrically connected to both electrically-conductive and ferromagnetic tapered tip member at the end portions of the rotor to the electrically-conductive permanent magnets that are mounted on the support frame assembly, and then connected to external circuit for direct current rectification and/or load via two wires.

These and other objectives of the present invention will become readily apparent upon further review of the following specifications and drawings.

SUBSTITUTE SHEET (RULE 26) BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the subsequent detailed descriptions and accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and wherein;

FIG. 1 is a perspective view of an axial flux wind turbine 100 according to the preferred embodiment of the present invention;

FIG. 2 is an exploded view of an axial flux wind turbine 100 according to the preferred embodiment of the present invention;

FIG. 3 is a cross-sectional view taken along line S-S in FIG 1, of an axial flux wind turbine 100 according to the preferred embodiment of the present invention;

FIG. 4 is a perspective view of the rotor with the electrically-conductive and ferromagnetic tapered tip members mounted on both end portions of the rotor, of an axial flux wind turbine 100 according to the preferred embodiment of the present invention;

FIG. 5 is a perspective view of the air core coils rotor of an axial flux wind turbine 100 according to the preferred embodiment of the present invention;

FIG. 6 is a circuit diagram view of connection of conductive path from the coils in series to the electrically-conductive and ferromagnetic tapered tip members of the rotor, of an axial flux wind turbine 100 according to the preferred embodiment of the present invention.

FIG. 7 is a partial perspective view of the rotor shaft magnetically levitated by the two electrically-conductive permanent magnets mounted on the support frame assembly. As for illustration purpose, views of rotor plate substrate, air core coils, blades and support frame assembly are not shown

SUBSTITUTE SHEET (RULE 26) DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided, so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. The methods and examples provided herein are illustrative only, and not intended to be limiting.

FIG. 1 , FIG. 2 and FIG. 3 show a perspective view, an exploded view and a cross-sectional view respectively of a horizontal axis rotor axial flux wind turbine 100 according to the preferred embodiment of the present invention.

The horizontal axis rotor axial flux wind turbine 100 comprising a rotor shaft 110, two permanent magnet stators 120, an air core coils rotor 140 with a plurality of blades 145 coupled with, a support frame assembly 150 and two wires 155.

Fig. 4 shows a rotor shaft 110 according to the preferred embodiment 100 of the present invention. The rotor shaft 110 comprising an electrically-non-conductive rotor shaft body 111 and electrically-conductive and ferromagnetic tapered tip member 112 on both end portions. The shape of the electrically-conductive and ferromagnetic tapered tip member 112 on both end portions of the rotor shaft 110 may be cone, multi-angular pyramid, sphere, hemisphere or combinations thereof without limitation herein.

Fig. 5 shows an air core coils rotor 140 according to the preferred embodiment 100 of the present invention. The air core coils rotor 140 comprising a rotor shaft 110, a rotor plate substrate 141, a plurality of air core coil 142 circumferentially mounted on the rotor plate substrate 141, and a plurality of blades 145 coupled to the outer rim of rotor plate substrate 141. In the prototype of the preferred embodiment 100 of the present invention, for example, blades rotor diameter is 100mm. The plurality of air core coil 142 are connected in series. One end of the air core coil 142 lead of the series connected air core coils is coupled on the electrically-conductive and ferromagnetic tapered tip member 112, wherein the other end of the air core coil 142 lead of the series connected air core coil 142 is coupled on the other electrically-conductive and ferromagnetic tapered tip member 112 (not shown in Fig 5). The series connection of air core coil 142 to both electrically-conductive and ferromagnetic tapered tip member 112 can be understood by viewing on circuit diagram Fig. 6.

The electrical connections from the said electrically-conductive and ferromagnetic tapered tip members 112 of rotor shaft 110 is then further electrically connected to both of the electrically-

SUBSTITUTE SHEET (RULE 26) conductive permanent magnet 153 on both side of the support frame assembly 150, as can be seen in FIG. 3. The electrical connections from the said electrically-conductive permanent magnets 153 is then further electrically connected to external circuit for direct current rectification and/or load via both wires 155.

The air core coils rotor 140 is disposed in the air gap between the two permanent magnet stators 120. In the prototype of the preferred embodiment 100 of the present invention, for example, the rotor plate substrate 141 is made from non-magnetic and electrically-non-conductive material and has a thickness of 3mm, wherein each annular shape air core coil 142 having insulated copper wire diameter of 0.12mm, an outer annular diameter of 12mm, an inner annular diameter of 6mm and a thickness of 3mm. The plurality of air core coil 142 is two, correspond to eight permanent magnets 122 on the stator to generate same phase alternating current. However, the plurality of air core coil 142 may vary as long as the plurality of air core coil 142 are in same phase with relation to the plurality of permanent magnets 122.

In the preferred embodiment 100 of the present invention, for example, each of the two permanent magnet stators 120 comprising a stator plate substrate 121 and a plurality of permanent magnets 122 circumferentially mounted thereon and also disposed in N-S-N arrangement. One of the permanent magnet stators 120 is coupled on the windward side support frame member 151, the other permanent magnet stator 120 is coupled on the leeward side support frame member 152. The two permanent magnet stators 120 are spaced apart from one another by an air gap, wherein the north pole of a permanent magnet 122 on one of the permanent magnet stator 120 is facing a south pole of a permanent magnet 122 on the other permanent magnet stator 120 and vice versa.

In the prototype of the preferred embodiment 100 of the present invention, for example, the stator plate substrate 121 is made from an electrically-non-conductive, non-ferromagnetic material which is light in weight. The stator plate substrate 121 has a diameter of 32mm and a thickness of 3mm, the permanent magnet 122 is neodymium type, disc-shape and has a diameter of 6mm and a thickness of 3mm, and the air gap between two permanent magnet stators 120 is 5mm.

The number of permanent magnets 122 mounted on each stator plate substrate 121 is eight, correspond to two air core coil 142 on air core coils rotor 140 for generating alternating current of same phase by each air core coil 142, upon rotating and cutting through magnetic field. However, the plurality of permanent magnet 122 may vary as long as the plurality of permanent magnet 122 are in same phase correspond to the plurality of air core coil 142.

Fig. 1 and Fig. 3 show a support frame assembly 150 that providing magnetic levitation to the rotor shaft 110 and also fixing two permanent magnet stators 120, according to the preferred embodiment 100 of the present invention. The support frame assembly 150 comprising a windward side support frame member 151 with an electrically-conductive permanent magnet 153 mounted and a leeward side support frame member 152 with an electrically-conductive permanent magnet 153 mounted. In the prototype of the preferred embodiment 100 of the present invention, for example, a

SUBSTITUTE SHEET (RULE 26) plurality of fasteners 154 may be used for fastening both windward side and leeward side support frame member 151, 152 together as a support frame assembly 150. However, the fixing of the support frame assembly 150 from both windward side support frame member 151 and leeward side support frame member 152 can be also other methods of fixing, instead of fastening with a plurality of fasteners as given as example in the prototype of the preferred embodiments 100 of the present invention.

The electrically-conductive and ferromagnetic tapered tip members 112 on both end portions of the rotor shaft 110 are attracted to the electrically-conductive permanent magnets 153 mounted on both windward side and leeward side support frame member 151, 152 as illustrated in Fig. 3 and Fig. 7, with a single point of contact. The electrically-conductive and ferromagnetic tapered tip member 112 must coincide with the axis of the two electrically-conductive permanent magnets 153 mounted on windward side and leeward side support frame members 151, 152, in order to achieve magnetic levitation to the rotor shaft 110 with a near zero rotational friction value. With a near zero rotational friction value, a very low starting torque produced by a very low wind speed, such as 1.2m/s, is sufficient to rotate the rotor shaft 110 that coupled with an air core coils rotor 140 and a plurality of blades 145 and start to generate electrical power.

Although disc-shape permanent magnets 122 are shown in the preferred embodiment 100 of the present invention as example, shape of permanent magnet 122 may be also in arc, trapezoidal, rectangular or any other suitable shape, though not shown in the drawing.

Fig. 1, 2, 3 show a nose cone 160 may be coupled on the windward side support frame member 151, providing a streamline wind directly flow through blades, instead of hitting on stator plate substrate 121 area which may cause turbulent and affecting performance of the present invention, if without nose cone in used.

Although annular shape air core coil 142 which are easy to be manufactured and winding are shown in the prototype of the preferred embodiment 100 of the present invention, for example, shape of air core coil 142 may be also in arc, trapezoidal, rectangular or any other suitable shape, though not shown in the drawing.

In the preferred embodiment 100 of the present invention and according to the dimensions and specifications provided in the example, the prototype of the present invention generates electrical power from wind speed as low as 1.2m/s. Typically, human walking speed is 1.4m/s. By holding the present invention during walking and without any ambient wind, the walking induced wind is sufficient for the present invention to generate power.

Finally, the forgoing examples are not intended to limit the scope of the invention disclosed herein, which is set forth in the following claims. In particular, various equivalents and substitutions will be recognized by those of ordinary skill in the art in view of the foregoing disclosure, and these are contemplated to be within the scope of the invention disclosed herein.

SUBSTITUTE SHEET (RULE 26)