WO2015147645A2

WO2015147645A2 - Electrical machine

Info

Publication number: WO2015147645A2
Application number: PCT/NL2015/050196
Authority: WO
Inventors: Hendrik Frederik SWITZER
Original assignee: Tornilo B.V.
Priority date: 2014-03-27
Filing date: 2015-03-27
Publication date: 2015-10-01
Also published as: NL2012514A; NL2012514B1; WO2015147645A3

Abstract

Electrical machine comprising a stator provided with electric wiring and a rotor with a rotatable axle and permanent magnets for providing a rotating magnetic field having magnetic field lines cooperating with said electric wiring of the stator, wherein the rotatable axle has two first discs mounted at opposite extremities of the axle, which first discs have a magnetic permeability sufficient to direct the magnetic field lines from the permanent magnets to the sides of the electric wiring of the stator, and that between said two first discs and the electric wiring of the stator two second discs are provided that are arranged with sectors of relatively high magnetic permeability that are alternated with sectors having relatively low magnetic permeability.

Description

Electrical machine

The invention relates to an electrical machine comprising a stator provided with electric wiring and a rotor with a rotatable axle provided with an outgoing shaft and permanent magnets for providing a magnetic field having magnetic field lines cooperating with said electric wiring of the stator.

Such an electrical machine is commonly known and is used as a generator for electrical energy or as an electrical motor. In both cases the magnetic field lines have to cooperate with the electric wiring to convert mechanical energy into electrical energy or vice versa. The conversion efficiency of prior art electrical machines is restricted; for instance a known generator only provides 70% energy at its electrical output for each unit of mechanical energy that is required to drive the generator.

US2012/0212085 discloses an axial-flux electric motor including a stator having a plurality of stator windings and a plurality of stator pole-pairs, the first rotor being configured to magnetically interact with the stator in an axial direction and being positioned on one side of the stator, and having a plurality of permanent magnets embedded thereon with a plurality of rotor pole-pairs, further a second rotor configured to magnetically interact with the stator in the axial direction, which second rotor is positioned on another side of the stator, and having a plurality of permanent magnets embedded thereon with a plurality of rotor pole-pairs, and a plurality of stationary ferromagnetic segments posi- tioned between the stator and the first rotor and between the stator and the second rotor, wherein the ferromagnetic segments are adapted to modulate the magnetic field of the permanent magnets in the axial direction.

In JP H07 264836 a magnetic field is formed by a permanent magnet and a pair of yokes, wherein a magnetic flux is caused to pass through one of a first current carrying part or a second current carrying part of a circular disk type conductor. In JP S56 91672 a rotating shaft is provided with an exciting winding, and an exciting anode is revolved by a mechanical force led from the outside. The rotation of the exciting anode causes changes of a magnetic flux to arise in an indiction magnetic pole. The changes of the magnetic flux cause DC electromotive forces to be generated in induction windings that are passed out through a rectifier.

US 3,906,267 discloses a DC brushless electric motor comprising a stator and a rotor. The rotor has two side cheeks arranged at the two sides of the stator in the axial direction, each having plural teeth of like polarity. The power winding comprises clusters of radially directed electrical conductors and the axis of each cluster is offset electrically by 180° from that of the preceding cluster. The clusters are connected so that two successive clusters are traversed by currents flowing in opposite directions.

WO2013/106919 discloses an electric apparatus comprising a stator having an array of coils positioned within its periphery and a first rotor having an array of magnet pairs positioned with its periphery. The first rotor has one face adjacent to the stator. A second rotor made of conductive material is positioned adjacent to another face of the first rotor. The coupling mechanism may be connected to the second rotor. The electric apparatus may be connected to an electric power source and act as a motor for driving a mechanical load attached to the coupling mechanism. The electric apparatus may alternatively be connected to an electric load, a turbine being attached to the coupling mechanism for generating electric power.

US 4,585,085 teaches an electric wheel drive for motor vehicles. Its electric motor is a homopolar multiple-air gap axial-field motor whose rotor replaces the wheeldrum and brake-disk of the vehicle, and whose stator replaces the brake-shoes, brake-pads, and brake splash shield plate of the vehicle.

W02006 / 030168 discloses a system comprising a wind powered homopolar generator having an annular magnet or electromagnet which produces a toroidal magnetic field and a con- ductive metal disk positioned in the magnetic field such that both the forward and return magnetic fields pass through the conductive disk. Electrical contacts are arranged in contact with the disk to collect the currents generated by the disk as it rotates through the magnetic field.

US2008/0100169 discloses a homopolar generator which comprises a plurality of stationary electrically conductive plates, a plurality of rotary magnetic plates, a drive device for effecting rotation of the rotary magnetic plates, and an electrical circuit assembly for extracting electrical current from the generator.

The invention aims to improve the conversion efficiency of the known electrical machine and to provide a feasible alternative for the known electrical machine.

The electrical machine of the invention has the features of one or more of the appended claims.

In a first aspect of the invention the electric wiring has parallel wires extending between a ground rail and a voltage rail of said electric wiring; the permanent magnets are arranged in the rotatable axle and magnetized in the axial direction with opposite poles at opposite extremities of the axle, and the rotatable axle has two first discs mounted at opposite extremities of the axle, which first discs direct the magnetic field lines from the permanent magnets to the sides of the electric wiring of the stator, and that between said two first discs and the electric wiring of the stator two second discs are rotatable journaled at opposite sides of the axle which are arranged with in comparison with each other sectors of relatively high magnetic permeability that are alternated with sectors having relatively low magnetic permeability .

Advantageously the machine includes drive means for driving the two second discs so as to rotate with reference to the axle. This can be done in several ways. In a first em- bodiment the drive means are embodied by a gear arranged between the shaft of the machine and the two second discs. In a second embodiment the drive means are embodied by an auxiliary electrical or mechanical drive for the two second discs. The energy that is required to drive the second discs that are positioned between the first discs and the electric wiring is surprisingly limited.

The machine according to the invention provides that the mere rotation of the two second discs induces already sufficient variation of the magnetic field lines crossing the electric wiring of the stator to result into appreciable electrical energy at the output of said electric wiring. This effect can be further enhanced by simultaneous rotation of the first discs from which the magnetic field lines emerge into the electric wiring.

In the electrical machine of the invention preferably not only the two second discs are rotatable, but advantageously both the two first discs and the two second discs are rotatable. Preferably the two first discs and the two second discs are rotatable in an opposite direction with respect to each other. This provides the largest variation with the highest frequency on the magnetic field lines that cross the electric wiring of the stator.

Best results are achieved when the two second discs have sectors of relatively in comparison with each other high magnetic permeability and sectors with relatively low magnetic permeability that are evenly distributed around a circle of 360°.

Although it may be possible to select other suitable materials, preferably the sectors of relatively high magnetic permeability predominantly comprise iron and the sectors of relatively low magnetic permeability predominantly comprise plastic .

It has been found advantageous that the two second discs have a larger diameter on its side directed to the electric wiring of the stator than on its opposite side directed to the first discs. This balances the forces that apply to the two second discs due to which their rotation can be effected relatively effortless.

The electrical machine of the invention is provided with electric wiring of the stator having approximately parallel wires that are perpendicular to the magnetic field lines and extend between a ground rail and a voltage rail of the electric wiring. This prevents the occurrence of bends and open spaces that are known from conventional coils, and thus limits the loss of conversion efficiency and arranges for optimal interference between the magnetic field lines and the electric wiring, therewith providing optimal transfer of energy. The electric wiring provided with this feature of the invention can be very dense which makes savings on copper possible. Also cooling of the wiring is better making it pos- sible to provide higher power machinery with the same material expenditure.

In one suitable embodiment of the electric machine of the invention the ground rail and the voltage rail of the electric wiring are circular and the approximate parallel electric wiring extends radially between said ground rail and voltage rail .

Suitably the ground rail and the voltage rail are spirals, thus providing that the optimal orientation of the approximately parallel wires can be maintained throughout the stator.

The invention will hereinafter be further elucidated with reference to an exemplary embodiment illustrated with reference to the drawing.

In the drawing:

-figure 1 shows an example of an electrical machine according to the invention;

-figure 2 shows a cross section through the rotor and stator of the electric machine of the invention;

-figure 3 provides a top view of one of the discs that are applied in the electric machine of the invention;

-figure 4 shows an example of radial electric wiring between a voltage rail and ground rail; and

-figure 5 shows an embodiment in which the voltage rail and ground rail are spirals.

Whenever in the figures the same reference numerals are applied, these numerals refer to the same parts.

With reference first to figure 1 an electrical machine 1 is shown comprising a stator 2 provided with electric wiring and a rotor 3 with a rotatable axle 4 in which are embedded permanent magnets for providing a magnetic field having magnetic field lines cooperating with the electric wiring of the stator 2. This can be more clearly seen in figure 2 which shows that the axle 4 is constituted by a series of connected magnets S-N-S-N providing opposite poles at opposite extremities of the axle 4. The axle 4 is in a manner common in the art provided with an outgoing shaft for connection to a mechanical load or drive. The manner in which this can be implemented is completely known to the skilled person and it is believed therefore that a detailed explanation with reference to a figure can be dispensed with. On the opposite extremities of the axle 4 two first discs 5, 5' are mounted, which first discs 5, 5' are magnetically permeable. The said first discs 5, direct the magnetic field lines from the permanent magnets S-N-S-N to the sides of the electric wiring 6 of the stator 2, wherein between said two first discs 5, 5' and the electric wiring 6 of the stator 2 two second discs 7, 7' are provided. Figure 3 shows that these second discs 7, 7' are arranged with sectors 8 of relatively high magnetic permeability that are alternated with sectors 9 having relatively low magnetic permeability. The terms 'relatively high' and 'relatively low' should be understood in comparison with each other.

Returning to figure 1 it is shown that the two second discs 7, 7' are rotatably provided on the axle 4 for which purpose a bearing 10 is provided. In the most preferred embodiment the two first discs 5, 5' and the two second discs 7, 7' are rotatable in an opposite direction with respect to each other, as is depicted with the arrows A and B. Driving the assemblies of the first discs 5, 5' and second discs 7, 7' can be provided by auxiliary drives as are exemplary shown and indicated with reference 11. It is however also possible to connect the first discs 5, 5' and/or the second discs 7, 7' with gears to the outgoing shaft of the axle 4. Providing such a gear to drivingly connect said shaft of the axle to either the first discs or to the second discs or to both the first discs and the second discs is completely known technol- ogy, and it is therefore not further shown or explained with reference to the drawing.

Figure 1 also depicts input and output connectors for cooling fluid indicated with reference 12 and 13 respec- tively. Further the figure shows electrical connectors 14.

Turning back to figure 3 it is shown that the two second discs 7, 7' have sectors 8 of relatively high magnetic permeability and sectors 9 with relatively low magnetic permeability that are evenly distributed around a circle of 360°. It can further be mentioned that the sectors 8 of relatively high magnetic permeability predominantly comprise iron and the sectors 9 of relatively low magnetic permeability predominantly comprise plastic.

Figure 2 shows a preferred embodiment in which the two second discs 7, 7' have a larger diameter on their side directed to the electric wiring 6 of the stator 2 than on their opposite sides directed to the first discs 5, 5'. This promotes an effective trajectory for the magnetic field lines from the first discs 5, 5' into the wiring 6 of the stator 2, and balances the forces that apply to the two second discs 7, 7' due to which their rotation can be effected relatively effortless .

In figure 4 it is shown that the electric wiring 6 of the stator 2 has approximately parallel wires 12 extending between a ground rail 13 and a voltage rail 14 of said electric wiring 6. Although not shown in figure 4, it is possible in certain embodiments to provide a straight ground rail and voltage rail. Figure 4 shows that the ground rail 13 and the voltage rail 14 are essentially circular and that the ap- proximate parallel electric wiring 12 extends radially between said ground rail 13 and voltage rail 14. The approximate parallel or radially extending wires 12 are preferably essentially perpendicular to the magnetic field lines originating from the permanent magnets.

Figure 5 depicts that the ground rail 13 and the voltage rail 14 are spirals. This is a very beneficial embodiment for implementing the electric machine of figure 1 and figure 2 in which the electric wiring 6 of the stator 2 must extends along the entire length of the machine between the two second discs 7, 7'.

Although the invention has been discussed in the foregoing with reference to an exemplary embodiment of the apparatus of the invention, the invention is not restricted to this particular embodiment which can be varied in many ways without departing from the gist of the invention. The discussed exemplary embodiment shall therefore not be used to construe the appended claims strictly in accordance

therewith. On the contrary the embodiment is merely intended to explain the wording of the appended claims without intent to limit the claims to this exemplary embodiment. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using this exemplary embodiment.

Claims

1. Electrical machine (1) comprising a stator (2) provided with electric wiring (6) and a rotor (3) with a ro- tatable axle (4) provided with an outgoing shaft and permanent magnets (S-N-S-N) for providing a magnetic field having magnetic field lines cooperating with said electric wiring (6) of the stator (2), characterized in that the electric wiring (6) has parallel wires extending between a ground rail (13) and a voltage rail (14) of said electric wiring, that the permanent magnets are arranged in the rotatable axle (4) and magnetized in the axial direction with opposite poles at opposite extremities of the axle (4), and that the rotatable axle (4) has two first discs (5, 5') mounted at said opposite extremities of the axle (4), which first discs (5, 5') direct the magnetic field lines from the permanent magnets in the axle (4) to the sides of the electric wiring (6) of the stator (2), and that between said two first discs (5, 5') and the electric wiring (6) of the stator (2) two second discs (7, 7') are rotatable journaled at opposite sides of the axle (4) which are arranged with in comparison with each other sectors (8) of relatively high magnetic permeability that are alternated with sectors (9) having relatively low magnetic permeability .

2. Electrical machine according to claim 1, characterized in that it includes drive means for driving the two second discs (7, 7') so as to rotate with reference to the axle (4) .

3. Electrical machine according to claim 2, characterized in that the drive means are embodied by a gear arranged between a shaft of the machine and the two second discs (7, 7') .

4. Electrical machine according to claim 2, characterized in that the drive means are embodied by an auxiliary electrical or mechanical drive (11) for the two second discs (7, 7') .

5. Electrical machine according to any one of the previous claims 1 - 4, characterized in that the two first discs (5, 5') and the two second discs (7, 7') are rotatable in an opposite direction with respect to each other.

6. Electrical machine according to any one of the previous claims 1 - 5, characterized in that the two second discs (7, 7') have sectors (8) of in comparison with each other relatively high magnetic permeability and sectors (9) with relatively low magnetic permeability that are evenly distributed around a circle of 360°.

7. Electrical machine according to any one of the previous claims 1 - 6, characterized in that the sectors (8) of relatively high magnetic permeability predominantly comprise iron and the sectors (9) of relatively low magnetic permeability predominantly comprise plastic.

8. Electrical machine according to any one of the previous claims 1 - 7, characterized in that the two second discs (7, 7') have a larger diameter on their side directed to the electric wiring (6) of the stator (2) than on their opposite sides directed to the first discs (5, 5') .

9. Electrical machine according to any one of the previous claims 1 - 8, characterized in that the parallel wires (12) of the electric wiring (6) of the stator (2) are perpendicular to the magnetic field lines.

10. Electrical machine according to claim 9, charac— terized in that the ground rail (13) and the voltage rail

(14) are circular and the approximate parallel electric wiring (12) extends radially between said ground rail (13) and voltage rail (14) .

11. Electrical machine according to claim 9 or 10, characterized in that the ground rail (13) and the voltage rail (14) are spirals.