The aspects of the disclosed embodiments relate to a magnetic coupling apparatus and to a method for creating such a coupling.
It is known that like magnetic poles repel, i.e. N↔N or S↔S, and, if the magnets are located at the circumferences of two essentially circular members, such that pairs of magnets inter-engage, rotation of one of the members will cause the other to rotate, according to basic gearing principles. An important aspect of this principle is that the engagement of the two members can result in a non-contact gear transmission. This is critical where risk of contamination from lubricants might occur or noise levels need to be minimised.
An additional advantage is that the circumferential magnets may directly inter-engage (like conventional gear teeth); this allows a direct drive transmission. Alternatively, the engagement of the magnets may be by passing closely past each other (without actual inter-engagement); this allows the driving member to continue operating even if the driven member is prevented from turning, i.e. it protects the mechanism from damage.
The aspects of the disclosed embodiments are defined in the attached independent claims, to which reference should now be made. Further, preferred features may be found in the sub-claims appended thereto.
According to a first aspect of the present disclosure there is provided 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.
The first and second magnets are preferably arranged in use to become apposed, but not touch one another, as the driven member rotates.
In a preferred arrangement, the poles of the first and second magnets are aligned to optimise the force.
Preferably the poles are aligned so that the force is repulsive.
In a preferred arrangement there is a plurality of first magnets arranged on the driving member, and preferably a plurality of second magnets arranged on the driven member.
The magnets are preferably 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. The first and second sets of magnets may mesh. Alternatively, the first and second sets of magnets may be arranged to remain in spaced circular loci as the driving member and driven member rotate.
The driving member may be arranged in use to be driven by a source of input power. The source of input power may comprise any of (but not limited to): electrical power, mechanical power.
The driven member may be connected to an output device. The output device may comprise any of (but not limited to): a pump, a generator, a gear.
The driving member may comprise first magnets arranged around a periphery of the driving member, preferably at spaced locations and more preferably at substantially equally spaced locations.
The driven member may comprise second magnets arranged around a periphery of the driven member, preferably at spaced locations and more preferably at substantially equally spaced locations.
The or each first magnets are preferably arranged on the driving member so that their North-South axes are substantially parallel with an axis of rotation of the driving member.
The second magnets are preferably arranged on the driven member so that their North-South axes are substantially parallel with an axis of rotation of the driven member.
In a preferred arrangement the driving member comprises a shaft and a substantially planar body on which the magnets are mounted.
The driven member may comprise a shaft and a substantially planar body on which the magnets are mounted.
The planar body may comprise a substantially circular, more preferably disc-like or annular body.
Preferably the magnets are arranged substantially normally with respect to their respective substantially planar bodies.
In a preferred arrangement the planar body of the driving member and the planar body of the driven member lie in a substantially common plane.
According to a second aspect of the present disclosure there is provided 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.
The magnets are preferably 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. The first and second sets of magnets may mesh. Alternatively, the first and second sets of magnets may be arranged to remain in spaced circular loci as the driving member and driven member rotate.
Preferably the method includes powering the driving member by a source of input power, which may comprise any of (but not limited to): electrical power, mechanical power.
Preferably the method includes connecting the driven member to an output device. The output device may comprise any of (but not limited to): a pump, a generator, a gear.
In accordance with a further aspect of the present disclosure, there is provided a magnetic coupling apparatus comprising:
Driving and driven members are preferably aligned so that, when rotating, the magnets in one plurality will pass magnets in the other plurality in a manner in which both their North and/or South seeking poles essentially abut in close proximity, i.e. N-to-N and/or S-to-S. Preferably they do not touch each other so that each one of the plurality of magnets fast with the driving member provides in turn a repulsive force with one of the plurality of magnets fast with the driven member. Accordingly, the magnets on the driving member impart a succession of repulsive forces (pushes) to the magnets on the driven member, thus causing it to rotate in an essentially smooth manner. This provides a drive to the output member.
Preferably the mutual engagement of a driving magnet in the plurality of driving magnets has limited circumferential freedom of movement in its engagement with a driven magnet in the plurality of driven magnets. More preferably, the separation distance between said driving and driven magnets in a forward direction of rotation is less than the separation distance between said driving magnet and the next driven magnet in a reverse direction of rotation.
The source of input power may be electrical in nature.
Alternatively, or in addition, the source of input power may be mechanical in nature.
The magnets may be permanent magnets.
Alternatively, or in addition the magnets may be electromagnets.
The electromagnets may be energised for only a predetermined part of the angular rotation of the driving and/or driven member.
Each magnet of the pluralities of magnets fast with both driving and driven members may be aligned normally to the common plane of rotation of both driving and driven members.
Each magnet of the pluralities of magnets fast with both driving and driven members may be aligned normally to the plane of rotation of the respective driving or driven members and these planes of rotation may be parallel to but offset from each other.
The magnets of the plurality on the driving member may abut in close proximity, but not touch the magnets of the plurality on the driven member in a manner in which the axes of each abutting pair of magnets are essentially parallel to each other.
The driving and driven members may be essentially planar and circular and/or may have circular parts and the magnets may be located normally to the plane of rotation and at/near the circumferences.
Each magnet of the plurality of magnets fast with both driving and driven members may be mounted so that the same pole, e.g. the North-seeking pole, is at the end of the magnet in contact with either the driving or driven member and hence the other pole, i.e. the South seeking pole, is at the distal end of the magnet remote from the common plane of rotation.
The apparatus may comprise a gearing transmission.
Alternatively, or additionally, the apparatus may comprise a power generator and/or a power convertor.
The output member may include a rotational drive means. Alternatively, or in addition, the output member may comprise an electrical power generator.
In a preferred arrangement there is a plurality of output members.
The coupling between the power source and the driving member may be either via an axial connection or may be via the driving member's circumference.
The coupling between the driven member and the output member may be via an axial connection or via the driven member's circumference.
The mutual engagement of the driving and driven magnets is preferably by inter-engagement in a manner similar to that of the inter-engagement of the teeth on gearwheels.
The inter-engagement of the driving and driven magnets may be on a one-to-one basis with no provision for slippage between the driving and driven members.
Alternatively, the mutual engagement of the driving and driven members may be by passing in close proximity without direct inter-engagement.
The passing in close proximity may allow for a degree of slippage between the driving and driven members.
The mutual engagement of the driving and driven members preferably provides anon-contact gear ratio or speed change.
The numbers of magnets in either/each plurality and/or relative diameters of the driving and driven members may determine the rotational gear ratio and/or speed change of the apparatus.
The spacing of the magnets in either/both pluralities and/or relative diameters of the driving and driven members may determine the torque transmission capabilities of the apparatus.
The spacing of the magnets in either/both pluralities may permit rotational self-starting of the driven member when power is supplied to the driving member.
In accordance with another aspect, the present disclosure includes a method of providing a magnetic coupling comprising the steps of:
Driving and driven members are preferably aligned so that, when rotating, the magnets in one plurality will pass magnets in the other plurality in a manner in which both their North and/or South seeking poles essentially abut in close proximity, i.e. N-to-N and/or S-to-S. Preferably they do not touch each other so that each one of the plurality of magnets fast with the driving member provides in turn a repulsive force with one of the plurality of magnets fast with the driven member. Accordingly the magnets on the driving member impart a succession of repulsive forces (pushes) to the magnets on the driven member, thus causing it to rotate in an essentially smooth manner. This provides a drive to the output member.
Preferably the mutual engagement of a driving magnet in the plurality of driving magnets has limited circumferential freedom of movement in its engagement with a driven magnet in the plurality of driven magnets. More preferably the separation distance between said driving and driven magnets in a forward direction of rotation is less than the separation distance between said driving magnet and the next driven magnet in a reverse direction of rotation.
The method may comprise a method of providing a gearing transmission.
Alternatively, or additionally, the method may comprise a method of power generation and/or of power conversion.
Where the magnets pass in close proximity but do not inter-engage, the driven member may be caused to rotate before power is supplied to the power source.
The driving and driven members may automatically synchronise their rotational speeds once both are rotating.
The driven member may synchronise at the same, or at a different, rotational speed to that of the driving member according to the number of magnets in each of the pluralities and the initial speed to which the driven member is caused to rotate.
Providing power to the driving member may be arranged to cause the driven member to commence rotation and synchronise itself with the driving member. Accordingly, the apparatus may be self-starting.
The one or more electromagnets may be energised for only a predetermined rotational solid angle of the driving and/or driven members corresponding to the close-proximity abutting of each pair of magnets.
In a preferred arrangement, a magnet on the rotatable driving member engages with, but does not contact, a magnet on the rotatable driven member. The engagement may involve a degree of circumferential freedom of movement so that the separation distance between a magnet on the driving member and a magnet on the driven member in the forward sense of rotation may be less than that between said magnet on the driving member and the following magnet on the driven member in the reverse sense of rotation.
Both driving and driven members are preferably planar and preferably essentially circular, and/or have circular circumferential parts, with a plurality of permanent magnets arranged spaced uniformly around their circumferences or circumferential parts. The two members may be arranged to rotate in a common plane. The magnets are preferably arranged in the substantially the same sense and substantially parallel to each other so that when a magnet in the one plurality approaches a magnet in the other plurality, the two North seeking poles are preferably adjacent and the two South seeking poles are also preferably adjacent, thus causing a doubly repulsive force to be generated.
The form of mutual engagement of the magnets on the driving and driven members may be either inter-engageinter-engagement, like that of gear teeth, or via passing close to each other but not touching.
If the driving member is caused to rotate, the passage of each magnet in its plurality will give a repulsive ‘kick’ to one of the plurality of magnets on the driven member causing it to move away. As the magnets in each plurality are spaced apart, driving and driven magnets will approach each other consecutively and undergo sequential repulsive kicks so that the driven member will continue to rotate until the two members turn synchronously. Where driving and driven members do not inter-engage but pass in close proximity, the driven member may be started rotating before power is supplied to the driving member. The driven member may be used as an output, driving an item of equipment either via an axial connection or via a further circumferential repulsive magnetic drive, such as just described. An advantageous feature is the non-contact nature of the magnetic drive. This may allow the apparatus to be used to transmit drive and/or power through an isolating barrier.
The invention may include any combination of the features or limitations referred to herein, except such a combination of features as are mutually exclusive, or mutually inconsistent.
Preferred embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:
In
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 generator—thereby generating power—via shaft 9.
The gearing ratio between driving 2 and driven 7 members (
Though an electrical motor 1 is shown (
As shown (
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.
As both driving 102 and driven 107 members (
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
In
With the arrangements shown in
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 (½mv2, where v is the velocity). During the conversion, part of the potential energy will be lost due to friction and air resistance.
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=KM1M2/d2, where F is the force (attractive or repulsive), K is a constant, M1 and M2 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.
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.
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.
In the apparatus shown in
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.
Electromagnets may have a marginal advantage over permanent magnets in that the magnetism may not be energised until the rotation 12, 13 (
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.
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.
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.
Number | Date | Country | Kind |
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1703452.1 | Mar 2017 | GB | national |
1721117.8 | Dec 2017 | GB | national |
1800156.0 | Jan 2018 | GB | national |
Filing Document | Filing Date | Country | Kind |
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PCT/GB2018/050494 | 2/27/2018 | WO | 00 |