WO1992022958A1

WO1992022958A1 - Permanent magnet turbine

Info

Publication number: WO1992022958A1
Application number: PCT/AU1992/000295
Authority: WO
Inventors: Peter Maximilian Stockl
Original assignee: Vakugo Pty. Limited
Priority date: 1991-06-18
Filing date: 1992-06-18
Publication date: 1992-12-23

Abstract

An apparatus is disclosed which comprises a motor deriving motive force from the interaction of magnetic fields. The apparatus includes a rotor magnet (1) and at least one stator magnet (4), wherein the rotor magnet (1) is moved in a circular path (2) and the stator magnet (4), mounted by means of a lever (14), is adapted to move toward or away from a point (5) on the path (2) of the rotor magnet in synchronization with approach to or departure from the point by the rotor magnet. In preferred forms, the levers are operated by electromagnets (18).

Description

Title: "PERMANENT MAGNET TURBINE"

TECHNICAL FIELD

This invention relates to a motor and, in particular, to a motor which derives at least part of its motive force from the interaction of magnetic fields BACKGROUND ART

Motors in which the motive force is derived from the interaction of magnetic fields are well known.

Most commonly such a motor has a rotor field which interacts with a stator field, at least one of the fields varying with time through the agency of an alternating current or switched direct current.

Linear electromotors are also known in which electromagnets are energised successively along a path. DISCLOSURE OF INVENTION

An object of the present invention is to provide a novel motor which, in preferred embodiments, is more efficient than known motors.

According to one aspect, the invention consists in apparatus comprising a first magnet constrained to move in a predetermined first path; a second magnet adapted to interact magnetically with the first magnet in the vicinity of a predetermined point on the first path, and means for moving the second magnet towards or away from said point in synchronization with approach to or departure from the point of the first magnet in a manner selected so that the magnetic interaction during said approach differs in magnitude from the magnetic interaction during said departure.

In a preferred embodiment, the magnetic interaction is one of repulsion and the magnetic repulsion during approach is less than the magnetic repulsion during departure. Preferably, the magnetic repulsion during approach is minimised.

According to a second aspect, the invention consists in apparatus comprising a rotor adapted for axial rotation about a first axis in a direction of rotation; a rotor magnet mounted to the rotor for movement in a circumferential path about the axis in said direction of rotation; a stator magnet mounted by means of a lever for movement towards or away from a point on the path; actuating means co-operating with the lever for movement of the stator magnet towards or away from the point in synchronization with approach to or departure from the point by the rotor magnet, the stator magnet being moved so as to exert a greater force on the rotor magnet during either departure or approach of the rotor magnet to the point so as to produce a net force on the rotor magnet in the direction of rotation.

Preferably, in an apparatus in accordance with the second aspect of the invention, the lever for mounting the stator magnet is a first order lever and means are included to minimise the effect of frictional forces.

Preferably also, the actuating means is an electromagnet. BRIEF DESCRIPTION OF DRAWINGS

Preferred embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

Figures 1A to 1C are diagrammatic representations of a system of magnets in accordance with the first aspect of the invention;

Figure 2 is a diagrammatic representation of a further system of magnets in accordance with the first aspect of the invention;

Figure 3 is a diagrammatic representation of a first embodiment of the second aspect of the invention shown in perspective;

Figure 4 shows the embodiment of Figure 3 in cross-section;

Figure 5 shows in cross-section a second embodiment employing electromagnets for movement of the stator magnets; and

Figure 6 shows a schematic diagram of a controller for use with the second embodiment of the invention.

BEST MODES FOR CARRYING OUT THE INVENTION

With reference to Figure 1A there is shown diagrammatically a first permanent magnet 1, constrained to move in a predetermined closed path 2 about an axis 3. A second magnet 4 is adapted to interact magnetically with first magnet 1 in the vicinity of a predetermined point 5 on the path 2. Magnets 1 and 4 are arranged with magnetic axes parallel but opposed as indicated by the labels N and S, for north-seeking and south-seeking poles respectively. In Figure 1A path 2 is circular and point 5 is defined at the intersection of a reference radial direction 6 with path 2. Initially, as first magnet 1 approaches point 5 (Figure IB), second magnet 4 is spaced at a distance therefrom. As magnet 1 passes point 5 (Figure IC), second magnet 4 is driven by means not illustrated in Figures 1A, IB and IC towards point 5 whereby repulsive forces between like poles of magnets 1 and 4 repel first magnet 1 and drive it away from point 5 as shown by the arrow 2' in Figure IC.

As illustrated in Figure 2, there may be two second magnets 4, 4' each moving in concert with the other towards point 5. Because second magnets 4, 4' do not approach close to first magnet 1 until magnet 1 is near or at point 5, the force of repulsion between like magnetic poles of magnets 1 and 4 and magnets 1 and 4' drives magnet 1 away from point 5.

With reference to Figures 3 and 4 there is shown a first embodiment of an apparatus in accordance with the second aspect of the invention, the apparatus comprising a rotor, having a central portion 10, lower portion 11 and an upper portion 12. Rotor portions 10, 11 and 12 are mounted to a shaft 13 and rotate together with respect to stators 16 and 17. A plurality of first magnets 1 are mounted radially to rotor portion 10, angularly spaced at a predetermined radial distance from the axis of shaft 13. Each magnet 1 has a magnetic axis extending generally parallel to shaft 13, with, for example, the north-seeking pole uppermost.

Upper stator 17 is provided with a plurality of second magnets 4, angularly spaced with magnetic axes extending in a direction generally parallel to the axis of rotor shaft 13 and intersecting the circular path along which rotor magnets 1 move as the rotor rotates. However, the magnetic axes of the stator magnets oppose those of the rotor magnets, for example with the south-seeking pole uppermost.

A plurality of second magnets 4' is associated with lower stator 11, each upper stator magnet 4 having a corresponding magnet 4' with which it forms a magnet pair. Each upper stator magnet 4 is disposed so that at its lower end (that is, the end closest the rotor magnets), it is of like polarity to the uppermost pole of the rotor magnets and repels the upper end of the closest adjacent rotor magnet. Likewise, each lower stator magnet 4 is disposed so that at its upper end it is of like polarity to the lowermost pole of the rotor magnets and repels the lower end of a rotor magnet.

Magnets 1 are each fixedly associated with rotor portion 10. Magnets 4, 4', are, however, mounted to levers 14 which pivot at fulcrum 15 whereby magnets 4 and 4" are movable in a direction towards or away from the circular path 2 through which magnets 1 move as the rotor rotates. In this embodiment, the radially inward end of each lever 14 is driven upwardly or downwardly by a cam profile (not illustrated) associated with rotor portions 11, 12 in such a manner that as each rotor magnet 1 passes a stator magnet pair 4, 4", the stator magnets of the pair are driven together. The rotor magnet is thus "squeezed" by the repulsive forces from the stator magnets 4, 4' and is driven away from the stator magnet pair. The stator magnets are then moved apart by the cam via levers 14. The process repeats as successive rotor magnets 1 approach the point of intersection of the common magnetic axis of a given stator magnet pair and the circular path of the rotor magnets.

Although in the first embodiment described above, the stator magnets are moved by cam-driven levers, the levers may be driven synchronously with rotation of the rotor by other means. Figure 5 shows a second embodiment in which the levers 14 are moved by electromagnets 18 sequentially energized and de-energized by means (not shown) timed by a photocell scanning an optical disk associated with the rotor shaft 13. Alternatively, other synchronizing means, for example a segmented contact plate may be used. The stator magnets are attached by suitable means to the ends 20 of the levers 1 . Rotor magnets are attached by threaded elements 19 to the rotor 10. Upper and lower stators 17 and 16 are fixedly attached to the housing (not shown) of the apparatus. Although the stator magnets move in synchronization with the rotor, the movement is desirably non-symmetrical with respect to passage of the rotor magnet past a stator magnet pair.

With a conventional electric motor, the rotor magnetic poles typically move in a circular path and the stator magnets are typically fixed in position with respect to the circular path. Either or both of the rotor and/or the stator magnets are electromagnets energised by currents and the energising currents are switched or otherwise varied to produce a rotating magnetic field which acts to rotate the rotor in a predetermined direction. In the present invention, variation in the stator field is achieved by moving the stator magnets.

Accordingly, the currents driving the electromagnets are selected to best achieve the non-symmetrical movement of the stator magnets with respect to the rotor magnets. Further, in the most efficient embodiments, efforts are made to recover at least some of the energy stored in the electromagnet coils during energisation.

It will also be understood that although in the embodiments described above, the stator magnets are shown as repelling the rotor magnets, in other embodiments of the invention the stator magnets may attract the rotor magnets during approach and then move apart to reduce the attraction as the rotor magnet departs.

Figure 6 shows a schematic diagram of a controller for use with the second embodiment, that is, where the levers 14 are operated by electromagnets.

In Figure 6 a three terminal regulator 100 supplies a suitable voltage for the controller components. A single chip microcontroller 101 executes a program in EPROM 102, a parallel output port 103 of the microcontroller being latched 104 to provide an address bus 105. 'Power-on Reset* signals generated by resistor capacitor networks 110, 111 reset the microcontroller and a parallel interface chip 112 respectively, when power is applied to the circuit. In addition a reset switch 106 allows the microcontroller to be reset manually.

The parallel interface chip drives up to 24 electromagnets (not shown) through buffers 120 and a connector 121. In use the program causes the electromagnets to be pulsed sequentially, operating the levers 14 to which the stator magnets 4, 4* are mounted. The microcontroller is able to monitor the speed and direction of the motor via a pair of slotted optical switches 122, 123 detecting revolutions of a perforated disk (now shown) on the shaft 13 of the motor. The inputs from the optical switches to a second port 124 of the microcontroller are polled in order to synchronise the electromagnet pulses to a reference position of the motor shaft and to determine the speed of the motor rotation relative to the microcontroller clock as determined by quartz crystal 125.

The port 124 which allows sensing of the optical switch outputs also allows sensing of three momentary push button switches 126-128. These switches provide on/off 126 control of the motor by instructing the microcontroller to start or stop pulsing the electromagnets; and to vary the speed up 127 or down 128 by increasing or decreasing the rate of pulsing. In yet another embodiment, levers 14 and fulcrum 15 of Figure 3 are replaced with shafts 14 mounted for axial rotation via bearings 15. In that case, second magnets 4 rotate anti-clockwise about the shafts while magnets 4' rotate clockwise about the shafts for an anti-clockwise rotation of rotor 10. In this embodiment, magnets 4 and 4' do not rotate at a constant velocity, but are adapted to accelerate so as to magnetically "squeeze" the rotor magnet as it passes therebetween and then to decelerate.

It will be understood that the first magnets or the second magnets, or both first and second magnets, may be electromagnets, in which case they may be energized by AC, DC, or pulsed currents, or may be permanent magnets.

As will be apparent to those skilled in the art from the teaching hereof, the invention may be embodied in other forms without departing from the inventive concept herein disclosed. In preferred forms, a combination of permanent and electromagnets is employed. INDUSTRIAL APPLICABILITY

In preferred forms the motor of the invention is suitable for use as a high torque prime mover.

Claims

CLAIMS : -

1. Apparatus comprising a first magnet constrained to move in a predetermined first path; a second magnet adapted to interact magnetically with the first magnet in the vicinity of a predetermined point on the first path, characterised in that means are provided for moving the second magnet toward or away from said point in synchronisation with approach to or departure from the point of the first magnet in a manner selected so that the magnetic interaction during said approach differs in magnitude from the magnetic interaction during said departure.

2. Apparatus as claimed in claim 1, wherein the magnetic interaction is one of repulsion, characterised in that the magnetic repulsion during approach is less than the magnetic repulsion during departure.

3. Apparatus comprising a rotor adapted for axial rotation about a first axis in a direction of rotation; a rotor magnet mounted to the rotor for movement in a circumferential path about the axis in said direction of rotation; a stator magnet mounted by means of a lever for movement toward or away from a point on the path, characterised in that actuating means is provided for co-operating with the lever for movement of the stator magnet toward or away from the point in synchronisation with approach to or departure from the point by the rotor magnet, the stator magnet being moved so as to exert a greater force on the rotor magnet during either departure or approach of the rotor magnet to the point so as to produce a net force on the rotor magnet in the direction of rotation.

4. Apparatus as claimed in claim 3, wherein the lever for mounting the stator magnet is a first order lever and means are included to minimise the effect of frictional forces.

5. Apparatus as claimed in claim 3 or claim 4, wherein the actuating means is an electromagnet.

6. Apparatus as claimed in claim 3, further including a plurality of angularly spaced stator magnets mounted by means of levers, wherein actuating means are provided for movement of each stator magnet toward or away from a corresponding point on the path of the rotor magnet in synchronisation with approach to or departure from said corresponding point by said rotor magnet.

7. Apparatus as claimed in claim 6, further including a like plurality of secondary stator magnets, wherein each of said secondary stator magnets is disposed such that the path of the rotor passes in between a stator magnet and a corresponding secondary stator magnet, said actuating means providing for complementary movement of both said stator magnet and said corresponding secondary stator magnet toward or away from said corresponding point.

8. Apparatus as claimed in claim 6, wherein said movement toward said corresponding point and said movement away from said point are non-symmetrical with respect to rotation of the rotor magnet past the point.

9. Apparatus as claimed in claim 6, wherein said actuating means includes a like plurality of electromagnets, said electromagnets being sequentially activated and each electromagnet causing movement of a corresponding stator magnet.