WO1996019035A1

WO1996019035A1 - Magnetic drive transmission and retardation systems

Info

Publication number: WO1996019035A1
Application number: PCT/AU1995/000852
Authority: WO
Inventors: Jeffrey Alan Muller; Ronald James Woodleigh
Original assignee: SUMMERCOVE Pty Ltd
Current assignee: SUMMERCOVE Pty Ltd
Priority date: 1994-12-15
Filing date: 1995-12-15
Publication date: 1996-06-20
Anticipated expiration: 1997-06-15
Also published as: AUPN008194A0

Abstract

A drive transmission system (10) including a driving body (11) of cylindrical form and a driven body (12) of cylindrical form. Each body (11, 12) is provided with a series of magnets (15, 20) about its periphery arranged in a spiral configuration. The magnets (15, 20) have common poles such that when the driving body (11) is rotated, drive is transmitted to the driven body (17) through the opposing effects of the magnets.

Description

MAGNETIC DRIVE TRANSMISSION AMD RETARDATION SYSTEMS Technical Field

This invention relates to magnetic drive transmission and retardation systems which employ fixed magnets and which in one aspect may be used for transmitting drive between components but which may also have other applications. Background Art

Common drive transmission mechanisms usually employ a plurality of mechanical elements which mechanically interengage to transmit drive between a drive device and a device to be driven. Transmission systems of this type include gear, belt or chain transmissions. A disadvantage of such systems is that they are subject to wear and therefore require regular maintenance. Wear arises because of friction which occurs between the moving parts of the mechanisms. Furthermore, such mechanisms particularly gear mechanisms are required to be regularly lubricated and for this purpose are often arranged within an oil-filled sealed housing. The sealed housing also protects the gears against ingress of dust or other materials which may damage the mechanism. Such gearing mechanisms require regular maintenance and replacement of the lubricating oil. Vehicle braking systems normally include a part, such as a drum or disc which rotates with a vehicle wheel and a braking pad which is moved into engagement with the wheel to retard its rotational movement. Such systems also require regular maintenance and replacement of the braking components due to wear. Summary of the Invention

The present invention aims to provide in one preferred aspect, a drive transmission system which eliminates or substantially reduces wear between intermeshing or interengaging parts and which therefore has advantages over the prior art. The present invention further aims to provide a drive transmission system which functions efficiently and which may be used in many

:rτ^,_ different motion transmission applications.

The present invention in a further aspect aims to provide a motion retardation system which reduces or substantially eliminates wear as encountered in conventional retardation systems such as conventional disc or drum braking systems.

In further aspects, the principles of the present invention may be applied to suspension and bearing systems. Other objects and advantages of the invention will become apparent from the following description.

The present invention thus provides in a first aspect a drive transmission system including a first driving part, a second driven part spaced from said driving part, said driving and driven parts supporting fixed magnet means, said magnet means cooperating such that movement of said driving part causes drive to be transmitted through magnetic forces to said driven part.

Preferably the poles of the magnet means are arranged such that said magnet means on the respective said driving and driven parts repel each other. The magnet means however may be such as to attract each other on the respective parts.

In one form, the driving part is rotatable and in the form of a body having an outer curved surface. The curved surface may be of cylindrical or conical or part conical form. The magnet means on the driving part may be arranged along the curved surface of the driving part. The magnet means suitably may be arranged to extend along a spiral track around the body or portion of the body of the driving part.

The driven part may also be in the form of a rotatable body having an outer curved surface which may comprise a cylindrical surface or conical or part conical form. The magnet means of the driven part may be arranged to extend along a spiral track around the outer surface of the body of the driven part. The spiral track on the driving part preferably has the same extent longitudinally and circumferentially as the spiral track on the driven part .

In a particularly preferred form, the magnet means or the driving and driven parts may comprise a plurality of fixed magnets which are arranged at spaced apart positions along the bodies of each part and which have common poles directed outwardly of the bodies. Thus for example the magnets of each body may have their North poles outermost. The magnets on each body are preferably equally spaced apart such that upon rotation of the bodies, respective magnets on each body are moved into register with each other.

In the above described configuration and where the bodies are of cylindrical form or have cylindrical surfaces, the axes of rotation of the driven and driving parts are substantially parallel and spaced apart such that the outer surface of the driving part is located adjacent to the outer surface of the driven part but with no contact therebetween. Where one or both bodies is of frustoconical form, the axes of rotation of the driving and driven parts may be arranged at an angle to each other to allow for an angle drive.

Where the diameter of the driving part is greater than the diameter of the driven part, the circumferential spacing of the spiral tracks of the magnets on each part is substantially the same, such that the driving part has a whole number multiple of the number of spiral tracks on the driven part. Rotation of the driving part will thus result in rotation of the driven part at the whole number multiple relative to the motion of the driven part. This provides a step-up drive transmission

Where the driven part is greater in diameter than the driving part, the spiral tracks on the driven part are arranged at a whole number multiple of the tracks on the driving part. Rotation of the driving part thus provides in this form a rotation of the driven part at a fraction of the rotation of the driving part. This results in a step- down drive transmission.

A drive transmission of the above described form, may be used in any application where drive is required to be transmitted between two rotatable parts such as to replace a gearing system in a vehicle or other mechanism. In an alternative embodiment of the invention, the driving and driven part may be of circular disc-like form and the magnets on each part are arranged on a common radial plane or planes and at the same circumferential spacing. Again where the driven and driving parts are of different ratios, a step up or step down transmission results.

In an application for retardation purposes, a similar principle may be employed, except in this instance, retardation of movement may be achieved by opposing or attractive forces of fixed magnets. In one retardation application, for example in a disc brake application, a brake disc may be provided with a series of circumferentially spaced apart magnets having common poles on one side of the disc and the brake "pad" for cooperation with the disc may comprise a further magnet which may be mounted for movement towards and away from the disc and the magnets thereon. Movement of the pad towards the disc will place its magnet or magnets adjacent to the magnets on the disc to thereby, through the opposing or attracting magnetic forces generated between the magnets, retard the motion of the disc.

In a further aspect, the present invention may be applied to linear motion wherein a plurality of magnets may be arranged at spaced apart positions along a track of travel and a travelling device supported for movement along the track, the travelling device including magnet means to co-operate with the magnets along the line to effect movement along the line through repelling magnetic forces and in addition support the travelling device above the track. In yet a further aspect, the present invention provides a suspension arrangement employing the principle of opposing magnetic forces for suspending one body relative to another body without mechanical contact therebetween. In this application, the system may be applied as a bearing arrangement for supporting a shaft, the bearing arrangement including a housing provided with a series of magnets having common poles directed inwardly and the shaft being magnetised with the same pole or having a further series of magnets spaced therearound of the same pole. The repulsion effects between the magnets on the housing and on the shaft will support the shaft centrally in the housing for rotation without contact between the shaft and housing.

The magnets used in the above described systems may be of any form but suitably comprise rare earth magnets.

Brief Description of the Drawings In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein:-

Fig. 1 illustrates schematically in perspective view a first form of transmission system according to the present invention;

Fig. 2 is a schematic sectional view illustrating the principle of the transmission system of Fig. 1;

Fig. 3 is a side view showing the arrangement of magnets on the driving and driven components of the system of Fig. 1;

Fig. 4 is an end view showing an alternative form of transmission system according to the invention; Fig. 5 is a side view of the system of Fig. 4; Fig. 6 illustrates an alternative form of transmission system according to the invention;

Fig. 7 illustrates schematically a typical transmission system incorporating the principles of the invention; Fig. 8 illustrates a further application of the invention to braking;

Fig. 9 illustrates schematically an application of the invention to linear motors; and Fig. 10 illustrates schematically an application of the invention to bearing. Detailed Description of the Embodiments

Referring to the drawings and firstly to Figs. 1 to 3, there is illustrated a transmission system 10 according to the present invention, comprising in this instance a first drive drum 11 of substantially cylindrical form and mounted for rotation about an axis 12. The drum 11 is adapted to be driven by any motive source such as an electric motor 13. The cylindrical surface 14 of the drum 11 is provided with a plurality of spaced magnets 15 which are arranged along a spiral path 16 extending about the axis 12 of the drum 11 which thus extends longitudinally and circumferentially of the drum 11 from one end to the other.

The transmission system 11 further includes a driven part 17 which includes a second drum 18 of generally cylindrical form which also includes on the surface 19 of the drum 18, a series of magnets 16 arranged along a spiral path 21 about the axis 22 of the drum 18 and thus extending longitudinally and circumferentially of the drum 16. The axis 22 is parallel to the axis 12, the axes 12 and 22 being spaced apart such that the surfaces 14 and 19 of the drums 11 and 18 lie adjacent to each other at 23 which is adjacent to a plane containing their axis 12 and 22 however the surfaces of the drums 11 and 18 are not touching. The magnets 15 and 20 on each drum 14 and 18 are spaced apart substantially the same distance along their respective spiral tracks. The driven drum 18 may be coupled to any device to which transmission of motion is required from the driving drum 11. The driven drum 18 may be larger or smaller in diameter than the driving drum 11, depending upon whether a step-up or step-down transmission is required between the drums 11 and 17. The drums 11 and 17, however, may also be of the same diameter where a one to one transmission ratio is required. Each drum may include one or more spiral tracks of magnets, however, where more than one track of magnets is provided on each drum, the circumferential spacing of the tracks on one drum is substantially the same as the circumferential spacing between tracks on the other drum. This will ensure co- operation between the respective magnets 15 and 20 on the respective drums 14 and 19. The exposed poles of the magnets 15 and 20 are also the same on each drum, such that when respective magnets on each drum approach each other, a repulsive force is generated. For example all magnets 15 and 20 may have their North poles exposed or radially outermost.

In use, when drive is transmitted to the drum 11 to cause rotation thereof, each magnet 15 on the track 16 of the driving drum 11 will move in turn into register with the respective magnets 20 on the driven drum 19. This will cause, through the repulsive effects of the respective common pole of the magnets 15 and 20, rotation of the driven drum 17 in the opposite direction and thus drive to be transmitted thereto from the driving drum 11. As rotation occurs, the respective magnets 15 and 20 in turn along the spiral tracks 16 and 21 on each drum 11 and 17 will come into register and effect a repulsive force between the drums 11 and 17 to maintain the rotation motion. Where the last magnets 15 and 20 along the tracks come into register, the first magnets 15 and 20 along the next spiral track will be moved into register to maintain the rotary motion between the drums. For this purpose, the last magnets in each track are preferably substantially longitudinally aligned with the first magnets of the next track so as to maintain the continuos repulsive forces between the magnets 15 and 20 on respective drums 11 and 18.

Figs. 4 and 5 illustrates an alternative embodiment of the invention which employs the principles of the invention described with reference to Figs. 1 to 3. The system 25 in this embodiment includes a first driving disc 26 and a second driven disc 27 arranged for rotation about an axis parallel to the axis of the driving disc 26.

SuESTiTJTE ε ^{■ "} r - ^" The driving disc 26 is provided with a plurality of spaced magnets 28 about or adjacent to its circumference, the magnets 28 being in this embodiment of disc-like form with opposite faces being the North and South poles respectively. The magnets 28 also in this embodiment are arranged at a forty-five degree spacing and also have their faces angled to the outer circumference of the disc 26, preferably at forty five degrees to the tangent. The magnets 28 however have common poles facing outwardly. The driven disc 27 is of a similar configuration including a plurality of magnets 29 adjacent its circumference, the magnets in this instance being at a ninety degree spacing. The magnets 29 have the same poles facing outwardly as the magnets 28 and are also angled to the circumference of the disc 27. The magnets 28 and 29 when moved into register with each other will thus repel.

This embodiment functions in a similar manner to that described above in that as the drive disc 26 rotates, the repulsive forces generated between the magnets 28 and 29 will cause the driven disc 27 to rotate in opposite directions with each magnet 28 and 29 moving with this rotation into alignment in the respective discs 26 and 29 to maintain the repulsive forces.

The driving disc 26 may be coupled to any driving means either directly or indirectly and the driven disc 27 may be coupled to any load to be driven.

In the embodiments described, the axes of rotation of the driving and driven parts are substantially parallel. In the embodiment of Fig. 6 however, the axes 30 and 31 of rotation of the driving and driven parts 32 and 33 respectively, are angled to each other by forming the bodies of the driving and/or driven parts as frustoconical bodies on which the respective magnets are mounted. One of the bodies only may be of frustonconical form whilst the other body may be cylindrical. This arrangement allows for an angle drive between shafts without the use of gearing.

Fig. 7 illustrates an application of the invention to a multiple driving system 34 where a single driven drum 35 is provided surrounded by a four driving drums 36 of larger diameter each coupled through a belt 37 to a drive motor 38 and each having their outer surfaces adjacent to the outer surface of the drum 35. As in the previous embodiments, the driving and driven drums 36 and 35 are provided with a series of magnets. At any one time however, the magnets on the driven drum 35 are in register with magnets on the four driving drums 36. This arrangement provides for increased power transmission from the driving to driven drums.

In alternative arrangement shown in dotted outline in Fig. 7, the driven drum 35 may be coupled to the drive motor 38 through a belt. Drive transmitted to the drum 35 will thus cause simultaneous rotation of the four drums 36 which become the driven drums. Of course any number of driving and driven drums may be used in combination to suit the application.

Referring now to Fig. 8, there is illustrated an application of the invention to a motion retarding system, in this case a disc brake system 39. The system 39 includes a disc 40 which is coupled to, for example, a vehicle wheel and which is provided with a plurality of spaced magnets 41 about its circumference. The magnets 41 have common poles exposed or facing outwardly. A retarding device 42 is mounted for movement toward and away from the disc 40 by any suitable actuating means such as an hydraulic actuating cylinder 43. The device 42 includes a fixed magnet 44. The magnet 44 suitably has its pole adjacent to the disc 40 opposite to the exposed poles of the magnets 41. Thus when the magnet 44 is moved towards the disc 40, the attractive forces between the magnets 41 and magnet 44 will retard the motion of the disc 40 and thus the wheel to which it is mounted to effect a braking action. Movement of the magnet 44 away from the disc 40 will release that retardation and braking effect. This principle may also be applied to drum type brakes where the magnets may be located about the surface of a drum to cooperate with a "braking" magnet moved towards and away from the drum.

Fig. 9 illustrates the application of the invention to a linear motor 45 comprising a plurality of magnets 46 arranged at spaced apart positions along a track 47. The magnets 46 have common poles facing upwardly. A travelling device 48 is arranged for movement along the track 47 and includes a further magnet 49 having its pole adjacent to the track 47 the same as the exposed (upper) poles of the magnets 46. The travelling device 48 will thus be supported above the track 47 by magnetic repulsion between the magnets 49 and 46. The magnets may also be configured to cause the device 48 to be impelled along the tracks again through repulsive force of the magnets.

Referring now to Fig. 10, there is illustrated a bearing system 50 according to the invention including in this case a housing 51 of annular form which supports a series of spaced magnets 52 on its inner side, the magnets 52 having common poles facing inwardly. A shaft 53 extends into the housing 51 and either is magnetised to have the same pole as the exposed poles of the magnets 52 or is itself provided with a series of spaced magnets 54. The poles of the magnets 52 and 54 are the same so that the repulsive force between the magnets supports the shaft 53 in suspension without mechanical contact. The principles of the present invention may be applied to many situations requiring drive transmission or drive retardation as well as suspension applications other than those described. In addition, whilst the principles of the invention are particularly suited for use with fixed magnets arranged such that common poles face and repel each other, in some situation, the poles of the magnets may arranged such that the poles attract each other. For example in the embodiments of Figs. 1 to 7, the magnets on the respective driving and driven parts may be arranged such that their poles attract. For example, the magnets 15 on the driving drum 11 may have their north poles exposed whilst the magnets 20 on the driven drum 17 may have their south poles exposed. Transmission of drive between the drving drum 11 and driven drum 11 will still occur through magnetic attraction rather than magnetic repulsion.

Whilst the above has been given by way of illustrative embodiment of the invention, all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.

Claims

1. A drive transmission system including a first driving part, a second driven part spaced from said driving part, said driving and driven parts supporting fixed magnet means, said magnet means cooperating such that movement of said driving part causes drive to be transmitted through magnetic forces to said driven part.

2. A drive transmission system according to Claim 1 wherein the poles of said magnet means being arranged such that said magnet means on the respective said driving and driven parts repel each other.

3. A drive transmission system according to Claim 2 wherein said driving part comprises a body having an outer curved surface.

4. A drive transmission system according to Claim 3 wherein said curved surface is of cylindrical or conical form.

5. A drive transmission system according to Claim 4 wherein said magnet means on said driving part extend along a spiral track around the body or portion of the body of said driving part.

6. A drive transmission system according to Claim 5 wherein said magnet means comprises a plurality of magnets.

7. A drive transmission system according to Claim 5 wherein said driven part comprises a body having an outer curved surface.

8. A drive transmission system according to Claim 7 wherein said magnet means of said driven part extend along a spiral track around the outer surface of the body of the driven part.

9. A drive transmission system according to Claim 8 wherein said spiral track on said driving part has the same extent longitudinally and circumferentially as the spiral track on the driven part.

10. A drive transmission system according to Claim 9 wherein said magnet means comprises a plurality of magnets.

11. A drive transmission system according to Claim 10 wherein said magnets on the respective said driving and driven parts are arranged at substantially the same spacing along their respective spiral tracks.

12. A drive transmission system according to Claim 1 wherein said driving and driven parts are of disc like form and wherein said magnet means comprise magnets arranged at spaced apart circumferential positions around the respective said discs.