MAGNETIC COUPLING AND METHOD

Abstract

A magnetic coupling apparatus, for transmitting drive from a driving member to a driven member, wherein the driving member has at least one first magnet and the driven member has a plurality of second magnets, and wherein the driving member and the driven member are arranged so that, as the driving member rotates, the at least one first magnet approaches one of the second magnets and thus exerts a force upon it which causes the driven member to rotate.

When motor is energised, driving member will rotate and bring a magnet towards a magnet, which will cause driven member to turn. As member reaches operating speed, the repeated repulsive kicks from magnets to magnets will synchronise the rotations. One member carries four magnets and an other member has eight magnets. The member with more magnets will rotate at half the speed of the other member.

Claims

1. A magnetic coupling apparatus, for transmitting drive from a driving member to a driven member, wherein the driving member has at least one first magnet and the driven member has one or more second magnets, and wherein the driving member and the driven member are arranged so that, as the driving member rotates, the at least one first magnet approaches one of the second magnets and thus exerts a force upon it which causes the driven member to rotate.

2. Apparatus according to claim 1, wherein the first and second magnets are arranged in use to become apposed, but not touch one another as the driven member rotates.

3. Apparatus according to claim 1, wherein poles of the first and second magnets are aligned to optimise the force.

4. Apparatus according to claim 1, wherein poles are aligned so that the force is repulsive.

5. Apparatus according to claim 1, wherein there is a plurality of first magnets arranged on the driving member.

6. Apparatus according to claim 1, wherein the magnets are arranged on the driving member and the driven member so that as the driving member rotates a succession of first magnets is brought into apposition to a succession of second magnets.

7. Apparatus according to claim 1, wherein the first and second sets of magnets may mesh.

8. Apparatus according to claim 1, wherein the first and second sets of magnets are arranged to remain in spaced circular loci as the driving member and driven member rotate.

9. Apparatus according to claim 1, wherein the driving member is arranged in use to be driven by a source of input power.

10. Apparatus according to claim 9, wherein the source of input power comprises electrical power or mechanical power.

11. Apparatus according to claim 1, wherein the driven member is connected to an output device.

12. Apparatus according to claim 11, wherein the output device comprises any of (but not limited to): a pump, a generator, a gear.

13. Apparatus according to claim 1, wherein the driving member comprises first magnets arranged around a periphery of the driving member at spaced locations.

14. Apparatus according to claim 1, wherein the driven member comprises second magnets arranged around a periphery of the driven member at spaced locations.

15. Apparatus according to claim 1, wherein the or each first magnets are arranged on the driving member so that their North-South axes are substantially parallel with an axis of rotation of the driving member.

16. Apparatus according to claim 1, wherein the second magnets are arranged on the driven member so that their North-South axes are substantially parallel with an axis of rotation of the driven member.

17. Apparatus according to claim 1, wherein the driving member comprises a shaft and a substantially planar body on which the magnets are mounted.

18. Apparatus according to claim 1, wherein the driven member comprises a shaft and a substantially planar body on which the magnets are mounted.

19. Apparatus according to claim 17, wherein the planar body comprises a disc-like or annular body.

20. Apparatus according to claim 17, wherein the magnets are arranged substantially normally with respect to their respective substantially planar bodies.

21. Apparatus according to claim 17, wherein the planar body of the driving member and the planar body of the driven member lie in a substantially common plane.

22. A method of making a magnetic coupling between a driving member and a driven member, the driving member having at least one first magnet and the driven member having one or more second magnets, wherein the method comprises arranging the driving member and the driven member so that, as the driving member rotates, the at least one first magnet approaches one of the second magnets and thus exerts a force upon it which causes the driven member to rotate.

23. A method according to claim 22, wherein the magnets are arranged on the driving member and the driven member so that as the driving member rotates a succession of first magnets is brought into apposition to a succession of second magnets.

24. A method according to claim 22 wherein the method includes powering the driving member by a source of input power comprising electrical power or mechanical power.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Preferred embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

[0077] FIG. 1 is a diagrammatic plan view of a first embodiment of the apparatus of the present disclosure;

[0078] FIG. 2 is a projected side elevation of the apparatus of FIG. 1;

[0079] FIG. 3 is a copy of FIG. 1 showing the driving engagement of the magnets in elliptical area A;

[0080] FIG. 4 is an enlargement of the elliptical area A, shown in FIG. 3;

[0081] FIG. 5 is a diagrammatic, plan view of a variation of the apparatus shown in FIG. 1 with an additional power take-off;

[0082] FIG. 6 is a diagrammatic plan view of a second embodiment of the apparatus of the present disclosure;

[0083] FIG. 7 is a diagrammatic side elevation of the apparatus shown in FIG. 6;

[0084] FIG. 8 is a diagrammatic plan view of a third embodiment of the apparatus of the present disclosure;

[0085] FIG. 9 is a diagrammatic side elevation of the apparatus shown in FIG. 8;

[0086] FIG. 10 is a diagrammatic plan view of a fourth embodiment of the apparatus of the present disclosure;

[0087] FIG. 11 is a diagrammatic side elevation of the apparatus shown in FIG. 10;

[0088] FIG. 10 is a diagrammatic, plan view of a fifth embodiment of the apparatus of the present disclosure;

[0089] FIG. 11 is a diagrammatic, side elevation of the apparatus shown in FIG. 10;

[0090] FIG. 12 is a diagrammatic, plan view of a sixth embodiment of the apparatus of the present disclosure;

[0091] FIG. 13 is a diagrammatic, side elevation of the apparatus shown in FIG. 12;

[0092] FIG. 14 is a diagrammatic, plan view of a seventh embodiment of the apparatus of the present disclosure; and

[0093] FIG. 15 is a diagrammatic, side elevation of the apparatus shown in FIG. 14;

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0094] In FIGS. 1-7 in the following description, like reference numerals are used for like components in different Figures and/or for different components fulfilling identical functions. In FIGS. 8-15, the same reference numerals are used but are increased by 100.

[0095] FIGS. 1 and 2 show a basic principle in accordance with embodiments of the present invention. Power is supplied 3 to motor 1, which drives member 2 rotationally 12. Mounted on driving member 2 are cylindrical bar magnets 5. Member 2 rotates 12 close to, but does not contact, driven member 7 (as shown) and a magnet 5 engages with a magnet 11 located at the circumferences of members 2 and 7 respectively. The driving member and driven member are broadly planar, more preferably circular, disk-like or annular bodies. All magnets 5 and 11 are mounted normally so that (for example) their N poles are close to members 2 and 7, i.e. at the upper ends of FIG. 2, and thus their S poles are at their distal ends. As shown (FIG. 2), members 2 and 7 are coplanar and thus magnets 5 and 11 are parallel to each other and approach with the two N poles adjacent and the two S poles adjacent so that a maximum repulsive force 14 (FIG. 4) is generated causing driven member 7 to rotate 13 away from each magnet 5. (The repulsive force is represented by double headed arrow 14 (FIG. 4).)

[0096] When motor 1 is energised, driving member 2 will rotate and bring a magnet 5 towards a magnet 11, which will cause driven member 7 to turn. As member 2 reaches operating speed, the repeated repulsive kicks 14 from magnets 5 to magnets 11 will synchronise the rotations 12 and 13; as member 2 carries four magnets 5 and member 7 has eight magnets 11, member 7 will rotate at half the speed of member 2. Member 7 drives an item 8, e.g. a pump, or a generatorthereby generating powervia shaft 9.

[0097] The gearing ratio between driving 2 and driven 7 members (FIG. 1) will depend on the relative numbers of magnets 5 and 11 respectively; typical ratios may be 2:1, 1:1 or 1:2, etc. in the FIG. 1 embodiment. As shown, the diameter of member 7 is greater than that of member 2 so the torque transmitted to shaft 9 will be greater than that in shaft 4.

[0098] FIG. 3 is a copy of FIG. 1 but with the area of the interaction of magnets 5 and 11 indicated by ellipse A. FIG. 4 is an enlargement of area of ellipse A. As shown, the separation distance 6A between magnets 5 and 11 in the forward direction of motion (12, 13) is much smaller than the separation distance 6B between magnet 5 and the following magnet 11 (i.e. in the reverse sense of rotation). The attractive or repulsive force between two magnets is essentially inversely proportion to the square of the separation distance. Thus, the forward force F.sub.A is essentially proportional to A.sup.2 and the reverse force F.sub.B is proportional to B.sup.2. As an example, to indicate the difference between F.sub.A and F.sub.B, one may scale off FIG. 4, where 6A is 18 mm and 6B is 47 mm. Thus F.sub.A/F.sub.B=(47/18).sup.2=6.818, i.e. F.sub.A is nearly 7 times stronger than F.sub.B. Hence, the vast majority of the net repulsive force 14, i.e. F.sub.AF.sub.B, is directed towards driving the forward (13) rotation of member 7. The relative distances 6A and 6B will depend on the power being transmitted through the gearing 2 and 7 and the speeds of rotation 12 and 13. Higher rotational speeds will result in more repulsive kicks per unit time and hence a smoother transmission as the net angular momentum in the rotating members 2, 7 increases.

[0099] Though an electrical motor 1 is shown (FIG. 2) as the power source, diesel engines or air motors, etc. are equally applicable. Similarly, the output 8 could drive any appropriate item, e.g. a pump, generator or item of robotic equipment, etc. FIG. 5 shows how the arrangement in FIG. 1 may be used to drive a further rotary output. Here driven magnets 11 become the driver, engaging with magnets 17 on member 19, causing rotation 21 about axis 18. The output 19 may be a rotary device (not shown), or a further power output 20. Though an axial input drive 4 (FIG. 1) is taught, a circumferential input drive (not shown but similar to members 17-21) is equally possible.

[0100] FIGS. 6 and 7 show a second variation of the basic principle of the invention in which driving 2 and driven 7 members, with their magnets 5 and 11, are doubled up and shown as 2 and 7, and their magnets 5 and 11, respectively. This arrangement should increase the power transmitting capability of the gearing.

[0101] FIGS. 8 and 9 show the principle of the invention where the magnets 105 and 111 pass close to each other without touching, as opposed to inter-engaging (FIGS. 1-7). As before power is supplied 103 to motor 100, which drives member 102 rotationally 112. This was an early trial of the principle with only two magnets 105 and 111 respectively on driving 102 and driven 107 members. Member 102 rotates 112 close to, but clear of, driven member 107, as shown 106, and a magnet 105 engages with a magnet 111 located close to the circumference of member 107. As before, all magnets 105 and 111 are mounted normally so that (for example) their N poles are close to members 102 and 107 and thus their S poles are at their distal ends.

[0102] As shown (FIG. 9), members 102 and 107 are coplanar and thus magnets 105 and 111 are parallel to each other and approach with the two N poles adjacent and the two S poles adjacent so that a maximum repulsive force 114 (FIG. 9) is generated causing driven member 107 to rotate 113 away from each magnet 105. (The repulsive force is represented by double headed arrow 114.) If member 107 is rotating when power 103 is supplied to motor 100, the two rotations 112 and 113 will synchronise and each magnet 105 will approach 106 and administer a repulsive kick 114 to a magnet 111 as they pass. Member 107 drives pump 108 via shaft 109 but may equally drive a generator to produce electrical power.

[0103] An advantage of this close passing arrangement is that slippage can occur between driving 102 and driven 107 members, e.g. if the load on the driven member 107 becomes excessive. This will protect motor 100 from damage due to being stalled.

[0104] As both driving 102 and driven 107 members (FIG. 8) respectively carry only two magnets 105 and 111, each will rotate 112, 113 at the same speed though in opposite senses. Depending on the initial speed of rotation of driven wheel 107 before power is supplied to motor 100, the ratio of rotational speeds may be 2:1, 1:1 or 1:2, etc. in the FIG. 8 representation. As shown, the diameter of member 107 is greater than that of member 102 so the torque transmitted to shaft 109 will be greater than that in shaft 104.

[0105] FIGS. 10 and 11 show a variation of the arrangement of FIGS. 8 and 9 in which driving member 102 is located parallel to, but below, the plane of the driven member 107. Spacers 115 maintain the close 106, but non-contact, abutting alignment of pluralities of magnets 105 and 111. As shown, magnets are mounted normally on members 102 and 107 respectively, again with the N and S poles directly abutting. This arrangement is more compact than that shown in FIGS. 8 and 9 but the principle of operation is the same and the same reference numerals are used.

[0106] FIGS. 12 and 13 show a further variation of the principle of the invention, but with a second power take off via member 116, driven by the interaction of pluralities of magnets 111 and 117, to axle 118 and a robotic item 119 (alternatively a generator) and output 120. As before, a single input 103 is used but provides two different outputs 109 and 119. All three members 102, 107 and 116 are coplanar.

[0107] Embodiments of the present disclosure may be adapted, as required, by changing the relative diameters of members 102, 107 and 116 and numbers of magnets in each plurality. A plurality of second takes off 116-120 may be provided, as required; in this way the apparatus of the present disclosure could simultaneously drive a number of different robotic systems, e.g. on a space craft. In FIG. 12, a two-stage power take off is taught and has been achieved in practice. However, motor 100 has to be powerful enough to provide the input force to drive the combination of the two magnetic repulsions 105-111 and 111-117 to produce useful outputs 109, 119.

[0108] In FIGS. 8-13, the pluralities have shown only two driving 105 and two driven 111 magnets; this has been to teach the principle of the present disclosure in a clear logical way. One method of increasing the transmitted power is shown in FIGS. 14 and 15, where the plurality of driving magnets 105A is used in pairs in a specially modified member 102A. Here, the pairs of magnets 105A will give magnet 111A a double kick as each passes i.e. increasing the torque transmission. Additionally (FIG. 15), each magnet 105A and 111A is doubled up. Here the repulsive force, as magnets 105A and 111A pass, is potentially greater than that in the FIGS. 8-13 representations.

[0109] With the arrangements shown in FIGS. 8-15, it may occasionally happen that driven member 107 will not begin to rotate when driving member 102 is started. Under these circumstances, if driven member 107 is turning 113 before motor 101 is started, members 102 and 107 will automatically synchronise.

[0110] It is known that energy may be converted from one form to another. For example, a mass at a high point will have potential energy (mgh, where m is the mass, g is the acceleration due to gravity and h is the height) and, if it is allowed to roll down a hill, it will convert a part of this into kinetic energy (mv.sup.2, where v is the velocity). During the conversion, part of the potential energy will be lost due to friction and air resistance.

[0111] In a similar way, if two like magnetic poles are brought towards each other a repulsive force is generated between them. Defining this force precisely can be complicated due to the physical size and shape of the magnets but it may be approximated to an inverse square relationship, i.e. F=KM.sub.1M.sub.2/d.sup.2, where F is the force (attractive or repulsive), K is a constant, M.sub.1 and M.sub.2 are the strengths of the two magnets and d is the separation distance. From this equation, it will be noted that the force increases rapidly as the separation distance decreases. This property may be used to convert a part of the magnetic potential energy into another form of energy.

[0112] The input power source and the repulsive forces between permanent magnets in the pluralities of magnets combine to produce the power in the output member.

[0113] When operated as described, some of the magnetic potential energy will be converted into the output energy, i.e. either rotational kinetic or electrical energy.

[0114] In the apparatus shown in FIG. 2, input 3 and output 10 electrical power was measured and independently verified. The output power is a function of the product of the number of magnets on the driven member 7 and its speed of rotation 13. The greater the number of magnets 11 on member 7, the smoother will be its rotation 13. Additionally, more magnets will increase the mass and hence the momentum of the member 7 and so give a more uniform power output 10.

[0115] The description above has been written on the basis of permanent, essentially bar, magnets and, while magnets, including rare earth elements, are very powerful, the invention is equally applicable to electromagnets. In this case, commutators (not shown) would be provided coaxially with some/all of axles 4, 9, 18, 104, 109 & 118 and power to energise the electromagnets, i.e. the equivalents to 5, 11, 17, 105, 111 &117 would be supplied for only the appropriate proximity, solid, rotational angles of members 2, 7, 16, 102, 107 & 116.

[0116] Electromagnets may have a marginal advantage over permanent magnets in that the magnetism may not be energised until the rotation 12, 13 (FIGS. 1-7) and 112, 113 (FIGS. 8-15) has reached the point of closest proximity of magnets 5 and 11, thus eliminating the small reverse kick (F.sub.B, 6B {FIG. 4}) as magnets approach prior to the strong forward kick (F.sub.A, 6A) at and after closest proximity as they move away from each other. Combinations of bar magnets and electromagnets are equally possible on the same, or different, driving and/or driven members.

[0117] The skilled person will understand the principle of the disclosed embodiments and its many practical applications, such as gear transmission, power generation or D.C. voltage conversion, all falling within the scope of the disclosed embodiments. However, one important aspect is the non-contact nature of the power transmission. Lubrication of geared systems is a problem in space as the lubricants tend both to evaporate and migrate over surfaces away from the contact areas. Thus, a non-contact means of mechanical power transmission will have advantages in satellites, etc. and other robotic equipment, e.g. as used in nuclear decommissioning. It may also be useful where drive and/or power is to be transmitted through an isolating barrier.

[0118] In the above-described embodiments the magnets on the driving and driven members are arranged to repel one another. It will be apparent to the skilled person that the magnets could be arranged for attraction, with suitable adjustment as necessary, whilst remaining within the scope of the invention.

[0119] Whilst endeavouring in the foregoing specification to draw attention to those features of the disclosed embodiments believed to be of particular importance, it should be understood that the applicant claims protection in respect of any patentable feature or combination of features referred to herein, and/or shown in the drawings, whether or not particular emphasis has been placed thereon.