AU650101B2 - Electric machine - Google Patents

Description

AUSTRALIA

Patents Act 0 'COMPLETE SPECIFICATION

(ORIGINAL)

claiss Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: C. C S S

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Name(s) of Applicant(s): *5 C C S 50 S. S C

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*5 0 APPLICANT'S REF.: Yu1 1 LAA Address(es) of' Applicant(s): ~J.U 3012 -tt.

Janusz Zandler Andrzej Witkowski 5 3 9I SomeorVIl-e ?0~QCJ Actual Inventor(s):

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C C Address for Service is: PFILLMP, ORMONDE AND FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Strect Melbourne, Australia, 3000 Complete Specification for the invention entitled: ELECTRIC MACHINE The following statement, is a full description of this invention, including the best method of performing it known to applicant(s): P' 19/3/44 2 ELECTRIC MACHINE This invention relates to an electric machine and is applicable to an electric machine for operating as an electric synchronous motor or generator involving AC power. The invention is applicable to cylindrical, rotary type electric machines, and it will be convenient to hereinafter describe the invention in relation to that exemplary application. It is to be appreciated, however, that the invention is not limited to that application.

Most rotating electric motors and generators include an outer stationery structure (stator) and an inner rotatable structure (rotor), separated by an annular air gap. These structures form a magnetic circuit in which

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magnetic flux is produced, an electromagnetic force (emf) being generated by relative movement between the structures. In many machines, windings situated on the stator and rotor produce the necessary magnetic flux for generating the emf by having electrical circuits flow through them. In that regard, field windings on one structure produce the magnetic flux whilst the emf is generated in armature windings on the other structure.

Depending on whether the machine operates as a motor or generator, then external electric current will be provided to the armature windings to rotate the rotor or the rotor will be externally mechanically rotated, respectively, thereby generating the (back) emv in the armature windings. The location of those windings is usually selected depending on whether the machine is a DC or AC motor or generator (as will be well appreciated by those skilled in this art) so that, for e)ample in AC machines the field windings are on the ro'.or and the armature windings are on the stator.

As these machines convert mechanical energy into electrical energy, or vice-versa, \:hey have associated with them some input energy loss. Thil loss is dissipated in heat owing to I 2 R, core and friction losses in the machine, both under steady state and transient operating conditions. Core losses occur in tlhe yoke, core, tooth and end-winding regions of the magnetic circuit within a machine, including the stator and the rotor. I R and 3 eddy-current losses occur in the stator and rotor windings, and the rotor excitation power requirement in particular limits the construction of many machines. Load losses are caused by alternating leakage fluxes that appear, when the machine is loaded, in pole-faces and, end regions and rotor and stator slots. Mechanical windage and friction losses in, for example, the bearings, the slip rings and associated brush assemblies, also contribute to the input energy loss of an electric machine.

Whilst these prior machines can function generally satisfactorily, losses including those above result in a reduced efficiency and limited energy output, and are often of a complex construction providing attendant high production and maintenance costs.

L5 •It is an object of the present invention to provide a relatively simple and inexpensive, yet effective and oi efficient electric machine.

W• J thin b i mi, tL• .ie-h o provides an electromagnetic rotary machine includin/ a stationary structure having a housing and an armatu with armature windings mounted on the housing; and, rotary structure mounted in the housing for rotary mo ment on a rotation axis relative to the stationary ructure, the rotary structure having a rotor shaft e ending through the housing for rotation on the rotati n axis and a pair of rotor members carried on the rot shaft for rotation therewith, each rotor member ha ing a series of pole teeth, the pole teeth of the ro r members interdigitating in spaced relation with one other adjacent the armature, during use of the machine the pole teeth of each rotor member being magneticall homopolar with the pole teeth of each rotor member be' g of relatively opposite magnetic polarity, whereby J using the machine as a generator the rotor shaft is rotated with an external source of mechanical en gy, magnetic fields of the magnetised pole teeth inter cting with the adjacent armature to produce a voltage *n the armature windings and thereby provide a source/of electrical power in the a:'mature windings, and Sin sing the machine as a motor an electromagnetic field ,RAO

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0 40 t w 4 With this object in mind, the present invention provides an electromagnetic rotary machine including: a stationary structure having a housing and an armature with armature windings mounted on the housing; and, a rotary structure mounted in the housing for rotary movement on a rotation axis relative to the stationary -structure, the rotary structure having a rotor shaft extending through the housing for rotation on the rotation axis, at least one mounting member on the rotor shaft and a pair of rotor members each mounted on the at least one mounting member for rotation with the rotor shaft, each rotor member having a series of pole teeth, the pole teeth of the rotor members interdigitating in spaced relation with one another adjacent the armature, and at least one magnetic device fixed to the stationary structure adjacent the rotor members and during use of the machine magnetises the pole teeth, the pole teeth of each rotor member being magnetically homopolar with the pole teeth of each rotor member being of relatively opposite magnetic polarity, whereby in using the machine as a generator the rotor shaft is rotated with an external source of mechanical energy, magnetic fields of the magnetised pole teeth interacting with the adjacent t* armature to produce a voltage in the armature windings and thereby provide a source of electrical power in the armature windings, and in using the machine as a motor an 25 electromagnetic field is produced in the armature windings 0 from an external source of electrical energy, the electromagnetic field interacting with the magnetic fields of the magnetised pole teeth to create forces that urge the rotor members to rotate, thereby rotating the rotor shaft to provide :,30 a source of mechanical power at the rotor shaft.

Preferably, the mounting member is composed of .5 non-ferromagnetic material so as to magnetically isolate the rotor members from one another and also the rotor shaft. A single mounting member is preferably provided. That member is .35 carried on the rotor shaft and each of the rotor members are mounted thereon. In one embodiment, the mounting member 00 includes a mounting flange affixed to the rotary shaft and projecting radially therefrom. The interdigitating pole teeth of each rotor member are connected to the mounting flange so

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4A as to mount the rotor members on the rotor shaft.

Preferably, each rotor member includes an annular body located coaxially and in radially spaced relation of the rotor shaft. Each rotor member body has an axial end region at which the respective pole teeth are provided. The rotor member bodies are preferably.- arranged along the rotor shaft with the axial end regions in end-to-end relation so that the pole teeth extend therefrom toward one another into their interdigitating relationship.

Preferably, a pair of the magnetic devices are fixad to the stationary structure adjacent respective rotor members.

These magnetic devices produce respective magnetic fields in which each of the rotor members lie and thereby magnetise the pole teeth. In at least c¢ne embodiment, each magnetic device includes an electromagnet positioned radially inwardly of the respective rotor member.

Preferably, the pole teeth of each rotor member are circumferentially spaced about the rotor shaft. Moreover, the pole teeth of each rotor member preferably interdigitate at least generally in an axial direction of the rotor shaft. The pole teeth of each rotor member are preferably axially elongate and interdigitate an axial extent which is at least substantially the axial length of the teeth.

Preferably, each pole tooth has a pole face arranged in 25 face-to-face relation with the armature, those pole faces being shaped so that, upon rotation of the rotor members, each pole face passes through an imaginary plane containing the rotation axis and extending radially therefrom to an else .increasingly and then decreasingly axial extent. The pole 0 faces of adjacent pole teeth are preferably relatively arranged so that, upon rotation of the rotor members, at least o one pole face is passing through the imaginary plane at any one time. In one embodiment, during at least part of the passage of each pole face through the imaginary plane, a pole face of an adjacent pole tooth is also passing through the o plane.

5 respective pole teeth are provided. The rotor er bodies are preferably arranged along the rotor ft with the axial end regions in end-to-end relati so that the pole teeth extend therefrom toward on nother into their interdigitating relationship.

Preferably, magnetic ices are fixed to the stationary structure ad' ent respective rotor members.

These magnetic drsvi produce respeutive magnetic fields in which each he rotor members lie and thereby induce magnetise e pole teeth. In at least one embodiment, each netic device includes an electromagnet positioned The housing preferably includes a pair of spaced apart end walls between which the rotor shaft extends.

Each of the magnetic devices are preferably fixed to a respective end wall and projects therefrom along the rotor shaft.

.The following description refers to a preferred embodiment of the electromagnetic rotary machine of the present invention. To facilitate an understanding of the invention, reference is made in the description to the accompanying drawing where the machine is illustrated in a side sectional view. It is to be understood that the 25 invention is not limited to the embodiment as hereinafter described and as illustrated.

Referring to the drawing there is generally shown rotary machine 1 having a cylinc'.rically-shaped outer stationary structure 2, and a core-shaped inner rotary .i structure 3. The rotary structure 3 is located within the stationary structure 2 and is rotatable on longitudinal rotation axis X.

The stationary structure 2 includes a housing 4 having open ended tubular casing 5, closed at the ends with spaced apart end walls 6,7.

The casing 5 is composed of ferromagnetic material, such as steel, whilst the end walls 6,7, are composed of non-ferromagnetic matdrial, such as aluminum.

Mounted within the housing 4 an armature 8 having core 9 on which armature windings 10 are mounted. The Q LUW 6 armature 8 is of conventional construction, with the core 9 being generally annular shaped in this embodiment, and coaxially aligned with the rotary structure 3 on the rotation axis X passing through the core 9. The armature core 9 is composed at least substantially entirely of ferromagnetic material. Moreover, the armature windings are arranged so as to extend generally parallel to the rotation axis X of the rotary structure 3.

The rotary structure 3 includes a ferromagnetic rotor shaft 11 extending along the rotation axis X through the housing 4. The rotor shaft extends into the end walls 6,7 and is journalled in bearings 12 n.ounted therein.

A pair of rotor members 13,14 are carried on the rotor shaft 11 for rotation therewith. Each rotor member 13,14 has a series of pole teeth 15,16, respectively. The pole teeth 15,16 of the rotor members 13,14, interdigitate with one another but are spaced apart so as to provide a continuous air gap 17 therebetween.

*Each of the pole teeth 15,16 has a pole face 18 arranged in face-to-face closely spaced relation with the armature 8, and defining air gap 19 therebetween. As will become more apparent hereinafter, the pole teeth 15,16 including the p-le faces 18, and the armature 8, including the armature windings 10, are constr.cted and arranged so 25 that, during use of the machine 1, a path of useful *e magnetic flux extends from the pole faces 18 of the pole teeth 15 or 16 of one rotor member 13 or 14, through the armature 8 and then to the oppositely polarised pole faces 18 of the pole teeth 16 or 15 of the other rotor member 14 or 13, respectively. In particular, the pole faces 18 are closely spaced apart from the armature 8 so that the air gap 19 is relatively small compared with the air gap 17 between the pole teeth 15,16. The air gap 17 between adjacent pole teeth 15,16 is selected so as to provide a path of relatively greater reluctance therebetween for the magnetic flux, enabling a greater p*oportion of magnetic flux created to become "useful" magretic flux by passing through the armature windings The appropriate dimensioning of the gaps 17 and 19 will be understood and appreciated by those skilled in the art of electric 7 machine construction.

Each rotor member 13,14 extends about the rotor shaft 11 and the pole teeth 15,16 of each rotor member 13,14 are circumferentially spaced about that shaft 11.

Moreover, the pole 'eeth 15,16 in'-erdigitate at least generally in an axial direction of the rotation axis X, although as will become more apparent hereinafter, those teeth 15,16 or at least the pole faces 18 may be angled or shaped in a circumferential direction. Thus, the pole teeth 15,16 extend generally parallel to the rotation axis X, with successive teeth 15,16 of each rotor member 13,3,4 being positioned side-by-side about the shaft 11.

The pole teeth 15,16 interdigitate an axial extent which is at least substantially the axial length of the teeth 15,16. Thus, the teeth 15,16 interdigitate substantially over their entire length but with the air gap 17 being maintained therebetween.

Each rotor member 13,14 includes an annular body located coaxially of the rotor shaft 11. The rotor member bodies 20 are open ended and each has an axial end region 21 at which the pole teeth 15,16 of that rotor member 13,14 are provided. The bodies 20 are arranged along the rotor shaft 11 with their end regions 21 in end-to-end relation so that the teeth 15,16 extend therefrom toward one another into their interdigitating relationship.

The body 20 and pole teeth 15,16 of each rotor member 13,14 are formed integral with one another. Thus, the pole teeth 15,16 may be cut into or otherwise formed at the end region 21 of each rotor member 13,14. It should be appreciated that alteriative rotor member constructions are envisaged, including the connection or mounting of individual pole teeth 15,16 to the rotor member bodies The rotor members 13,14 are mounted on the rotation shaft 11 so as to be magnetically isolated therefrom, and from oni another. That is achieved through a non-ferrotmagnetic mounting means 22.

The mounting means 22 includes a mounting member 23 fixed on the rotor shaft 11 and to which the annular rotor members 13,14 are each mounted coaxially of and radially 8 spaced from the rotor shaft 11. A single mounting member 23 is provided in this embodiment, that member 23 being located between the interdigitating pole teeth 15,16 and the rotor shaft 11 so that the rotor members 13,14 are connected to the mounting member 23 through the pole teeth 15,16.

In this embodiment, the mounting member 23 is in the form of a mounting flange 24. The mounting flange 24 is fixed to the rotor shaft 11. Moreover, the mounting flange 24 has an outer peripheral surface 25 over which the pole teeth 15,16 extend and to which they are connected.

The mounting flange 24 is composed of any suitable non-ferromagnetic material, including non-ferromagnetic metal such as stainless steel or aluminium.

The pole teeth 15,16 are composed of ferromagnetic S material to enable their magnetisation. In this embodiment, each rotor member 13,14 including the pole teeth 15,16 is substantially entirely composed of ferromagnetic material. That material is steel in this embodiment.

The pole teeth 15,16 are shaped and sized, relative to the armature 8, so as to extend an axial length at least substantially equal to the kixial extent of the armature windings 10. Thus, the teeth 15,16 are positioned at least substantially entirely radially within and beneath the armature windings 1i, in this embodiment.

Moreover, the pole teeth 15,16 are shaped and sized so S* that their pitch is equal to that of the armature windings :38 10. In this embodiment, each rotor member 13,14 has 8 pole teeth, although it will be appreciated that other members may be provided.

The shape of the pole teeth 15,16 may vary according to the desired operating characteristics and performance of the machine 1. In particular, when operating as a generator, the pole teeth shape ma', vary in accordance with the desired wave form of current to be generated within the armature windings In this embodiment, the pole teeth 15,16 are shaped so that an imaginary radial plane coitaining the rotation 9 axis X, and passing through the windings 10, is progressively passed through by each tooth 15,16. That plane is passed by an increasingly and then decreasingly axial extent of each tooth 15,16, rether than a constant axial extent of each tool 15,16, in this embodiment.

Further, in this embodiment, adjacent pole teeth 15,16 from the two rotor members 13,14 are arranged in an overlapping relationship so that, at any one time, there is at least one pole tooth 15,16 passing through the imaginary plane; two teeth 15,16 may be passing through the plane at other times. In this way, a relatively smooth alternating current wave form may be generated in the armature windings In this particular embodiment (as shown), the pole teeth 15,16 and pole faces 18 are triangular shaped in plan. In another embodiment (not shown), the pole teeth 15,16 and pole faces 18 are rectangular or square shaped in plane, those teeth 15,16 being circumferentially angled relative to the rotor member bodies 20. These po1r teeth 15,16 generate a generally trian0gular or sinusoidal current wave form.

In an alternative emboidment (not shown), the teeth 15,16 are shaped so that an imaginary radial plane is cut by a constant, entire axial extent or length of each tooth 15,16 during its passage through the plane. Such teeth S* 15,16 could generate a more abruptly or sharply shaped alternating electromotive wave form.

In one particular embodiment (not shown), such pole S* teeth 15,16 are rectangular or squaze in plane shape and extend axially of the rotor member bodies 20. A square current wave form is generated with such teeth 15,16.

The rotor members 13,14 are provided with passages 26 for cooling access into the rutary structure 3 to reduce over heating of the machine 1. Those passages 26 may be in the form of slots or grooves 27 in the rotor members 13,14. In this embodiment, the cooling slots 27 extend from an outer end region of the bodies 20 across the outer surface thereof to roots between the pole teeth 15,16. Those slots 27 of each rotor member 13,14 may be aligned with the pole teeth 15,16 of the other rotor 10 member 13,14 in order to direct the cooling air to those teeth 15,16 of the other rotor member 13,14.

Magnetising means 28 is provided for magnetising the pole teeth 15,16. This means 28 includes a separate magnetic device 29 associated with each respective rotor member 13,14 for magnetising the pole teeth 15,16 thereof.

The magnetic devices 29 are mounted inside the annular rotor members 13,14 radially inwardly of and adjacent the rotor member bodies 20 and pole teeth 15,16.

Moreover, the magnetic devices 29 are stationary, in machine use, so that the rotor shaft 11 and rotor members 13,14 rotate relative thereto durirg machine operation.

To that end, the magnetic devices 29 are fixed to the housing 4 and extend axially along the rotor shaft 11, through respective open ends of the rotor member bodies 20, so as to extend closely between the shaft 11 and rotor members 13,14. Relatively small air gaps 30 and 31 are provided between the magnetic devices 29, and the rotor members 13,14 and the rotor shaft 11, respectively. As a result, in use of the machine 1, a path of useful magnetic flux extends from one magnetic device 29 across air gap to the body 20 of one rotor member 13,14, across the air gap 19 to the armature 8, then again across the air gap 19 to the body 20 of the other rotor member 13,14 and finally across air gap 30 to the other magnetic device 29. A "return" magnetic flux path extends between the magnetic devices 29 via the air gap 31 and thB rotor shaft 11, but not the non-ferromagnetic mounting me'ns 22.

In this embodiment, each magnetic device 29 includes *38*i an electromagnet 32 energisable to produce the magnetic flux for magnetising the adjacent pole teeth 15,16. Each electromagnet 32 has a ferromagnetic core 33 carrying a series of electrical field windings 34. Each core 33 is fixed to the housing 4 at respective end walls 6,7 thereof, and extends coaxially closely between the rotor shaft 11 and respective rotor members 13,14. Each core 33 has a portion 35 closely spaced fro, the rotor shaft and respective rotor member body 20 and defining the air gaps 31 and 30 therebetween.

The field windings 34 are woind circumferentially 11 around the core 33 and are locateo at least partially beneath the respective pole teeth 15,26.

In this embodiment, each magnetic device 29 extends beneath the pole teeth 15,16 from immediately adjacent the mounting flange 24.

In order to oppositely polarise the pole teeth 15,16, the field windings 34 are oppositely wound in this embodime: t. The field windings 34 are energised with a DC electrical supply, in this embodiment. That supply may be external to the machine 1. Alternatively, the supply may be provided internally from the armature windings 10. In that case, at least when the machine operates as a generator, the rotor members 13,14 will be composed of a ferromagnetic material that causes th3 pole teeth 15,16 to o' retain a residual magnetism to enable initial self excitation of the armature windings 1

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In an alternative embodiment (not shown), each magnetic device 29 may be provided by a permanent magnet.

The machine 1 as described above may be used as a generator to convert mechanical energy into electrical energy, or as a motor to convert electrical esergy into mechanical energy, as will be well understood by those skilled in the relevant art. The machine will function as *4 a synchronous generator or motor, in this embodiment.

As a generator, the rotor shaft 11 is caused to rotate with an external source of mnchanical energy. An external DC electrical power supply i.ay be provided to the field windings 34 from the outset of machine operation, in order to magnetise portion 35 of the ferromagnetic core 33 38*e: and thus pole teeth 15,16. Alternatively, the pole teeth 15,16 may be constructed to have a retained residual magnetism so that the pole teeth 15,16 produces a sufficient magnetic field for initial excitation of the armature windings The magnetic fields produced by the pole teeth 15,16 interact with the armature windings 10 to produce a voltage in the windings 10. As a result, a current is generated in the windings 10 which -an be conducted away as a source of electrical energy. Where the pole teeth 15,16 initially self excite the arnature windings 10, a 12 small regulated proportion of the electrical energy conducted from the windings 10 can be supplied as an internal DC electrical power supply to the field windings 34.

As a motor, an external source of electrical energy is conducted to the armature windings 10 which produce an electromagnetic field in those windings 10. That electromagnetic field interacts with the magnetic fields produced at the pole teeth 15,16, creating forces that urge the rotor members 13,14 to rotate about the rotation axis X. That in turn causes the rotor shaft 11 to rotate and thereby providing a source of mechanical energy.

Finally, it is to be appreciated that various modifications and/or alterations may be made to the machine without departing from the ambit of the present invention as defined in the claims appended hereto.

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Claims (15)

1. An electromagnetic rotary machine including: a stationary structure having a housing and an armature with armature windings mounted on the housing; and, a rotary structure mounted in the housing for rotary movement on a rotation axis relative to the-stationary structure, the rotary structure having a rotor shaft extending through the housing for rotation on the rotation axis, at least one mounting member on the rotor shaft and a pair of rotor members each mounted on the at least one mounting member for rotation with the rotor shaft, each rotor member having a series of pole teeth, the pole teeth of the rotor members interdigitating in spaced relation with one another adjacent the armature, and at least one magnetic device fixed to the stationary structure adjacent the rotor members and during use of the machine magnetises the pole teeth, the pole teeth of each rotor member being magnetically homopolar with the pole teeth of each rotor member being of relatively opposite magnetic polarity, whereby in using the machine as a generator the rotor shaft is rotated 20 with an external source of mechanical energy, magnetic fields of the magnetised pole teeth interacting with the adjacent armature to produce a voltage in the armature windings and thereby provide a source of electrical power in the armature windings, and in using the machine as a motor an electromagnetic field is produced in the armature windings from an external source of electrical energy, the electromagnetic field interacting with the magnetic fields of the magnetise, pole teeth to create forces that urge the rotor members to rotate, thereby rotating the rotor shaft to provide **030 a source of mechanical power at the rotor shaft.

2. A rotary machine as claimed in claim 1, wherein the 0* mounting member is composed of non-ferromagnetic material so as to magnetically isolate the rotor members from one another.

3. A rotary machine as claimed in claim 1 or 2, wherein a .35 single mounting member is provided, the mounting member being carried on the rotor shaft and each of the rotor members being mounted thereon.

4. A rotary machine as claimed in claim 3, wherein the 1, mounting member includes a mounting flange affixed to the 14 rotary shaft and projecting radially therefrom, the interdigitating pole teeth of each rotor member being connected to the mounting flange thereby mounting the rotor members on the rotor shaft.

5. A rotary machine as claimed in any preceding claim, wherein the rotor members are of at least substantially identical construction and carried on the shaft in axially spaced apart and facing relation.

6. A rotary machine as claimed in any preceding claim, wherein each rotor member includes an annular body located coaxially and in radially spaced relation of the rotor shaft, each rotor member body having an axial end region at which the respective pole teeth are provided, the rotor member bodies being arranged along the rotor shaft with the axial end regions in end-to-end relation so that the pole teeth extend therefrom toward one another into their interdigitating relationship.

7. A rotary machine as claimed in any preceding claim, wherein a pair of the magnetic devices are fixed to the 4.6620 stationary structure adjacent respective rotor members, the magnetic devices creating respective magnetic fields in which 6: 6 each of the rotor members lie and thereby inducing magnetic polarity at the pole teeth.

8. A rotary machine as claimed in claim 7, when appended to !5 claim 4 or any claim appended thereto, wherein a pair of the magnetic devices are provided and spaced axially apart along the rotor shaft one on each side of the single mounting flange. 91 A rotary machine as claimed in claim 7 or 8, wherein each magnetic device includes an electromagnet positioned ?0 radially inwardly of the respective rotor member. A rotary machine as claimed in claim 9, wherein each electromagnet includes an annular ferromagnetic core mounted to the housing so as to surround the rotor shaft and extend coaxially of the respective rotor member, and a field winding extending circumferentially about the ferromagnetic core.

11. A rotary machine as claimed in claim 10 when appended to claim 6, wherein the annular core of each electromagnet includes a portion shaped and sized so as to be in closely spaced relation with both the rotor shaft and the respective 15 rotor member body.

12. A rotary machine as claimed in any one of claims 7 to wherein the housing includes a pair of spaced apart end walls between which the rotor shaft extends, and each of the magnetic devices are fixed to a respective end wall and projects therefrom along the rotor shaft.

13. A rotary machine as claimed in any preceding claim, wherein the pole teeth of each rotor member are circumferentially spaced about the rotor shaft and the pole teeth of each rotor member interdigitate at least generally in an axial direction of the rotor shaft.

14. A rotary machine as claimed in claim 13, wherein the pole teeth of each rotor member are axially elongate and interdigitate an axial extent which is at least substantially the axial length of the teeth. A rotary machine as claimed in claim 13 or 14, wherein each pole tooth has a pole face arranged in face-to-face relation with the armature, the pole faces being shaped so that, upon rotation of the rotor members, each pole face passes through an imaginary plane containing the rotation axis and extending radially therefrom to an increasingly and then decreasingly axial extent.

16. A rotary machine as claimed in claim 15, wherein the pole faces of adjacent pole teeth are relatively arranged so .000.25 that, upon rotation of the rotor members, at least one pole face is passing through the imaginary plane at any one time.

17. A rotary machine as claimed in claim 16, wherein the pole faces of adjacent pole teeth are arranged in an overlapping relationship so that, during at least part of the ?0 passage of each pole face through the imaginary plane, a pole face of an adjacent pole tooth is also passing through the S plane.

18. A rotary machine as claimed in any one of claims 15 to 17 wherein the pole teeth and pole faces are triangular shaped in plan. S. 19. A rotary machine as claimed in any preceding claim, wherein the armature has armature windings arranged to extend generally parallel to the rotation axis of the rotary shaft. 16 An electromagnetic rotary machine substantially as hereinbefore described with reference to what is shown in the accompanying drawings. DATED: 23 March, 1994 PHILLIPS ORMONDE FITZPATRICK Attorneys for: ZANDLER WITOCK ENGINEERING PTY. LTD. 0562E *6 a0 3 0 KW ABSTRACT An electromagnetic rotary machine for operating as an electric motor or generator. The machine (1) includes a stationary structure having a housing (4) and an armature with armature windings (10) mounted on the housing A rotary structure is mounted in the housing for rotary movement on a rotation axis (X) relative to the stationary structure The rotary structure has a rotor shaft (11) extending through the housing for rotation on the rotation axis and a pair of rotor members (13,14) carried on the rotor shaft (11) for rotation therewith. Each rotor member (13,14) has a series of pole teeth (15,16) and the pole teeth (15,16) interdigitate in spaced relation with one another adjacent the armature During use of the machine (1) the pole teeth (15,16) of each rotor member (13,14) are magnetically homopolar, with the pole teeth (15,16) of each rotor member (13,14) being of relatively opposite magnetic polarity. In using the machine as a generator, the rotor shaft (11) is rotated with an S O, external source of mechanical energy, magnetic fields of e'l. the magnetised pole teeth (15,16) interacting with the adjacent armature to produce a voltage in the armature So windings (10) and thereby provide a source of electrical power in the armature windings In using the machine as a motor, an electromagnetic field is produced in U. t S" the armature windings (10) from an external source of electrical energy, and the electromagnetic field interacts with the magnetic fields of the mA:gnetised pole teeth (15,16) to create forces that urge the rotor members (13,14) to rotate, thereby rotating the rotor shaft (11) to provide a source of mechanical po',er at the rotor shaft (11).