WO2007138274A1

WO2007138274A1 - Apparatus for applying accelerative force

Info

Publication number: WO2007138274A1
Application number: PCT/GB2007/001928
Authority: WO
Inventors: Rasoul Khorshidpour
Original assignee: Goodwin, Parvaneh
Priority date: 2006-05-26
Filing date: 2007-05-24
Publication date: 2007-12-06
Also published as: GB0610499D0

Abstract

An apparatus for use in producing accelerative forces comprises a fixed portion comprising a first ring-like structure (1) that supports a plurality of actuators spaced around its perimeter, each actuator comprising a generally C-shaped support frame that lies in a plane orthogonal to the ring-like support structure and orthogonal to the axis of the ring-like structure (1), each support frame carrying one or more magnets (11, 12,13, 14), and a rotating portion (2) comprising a second ring-like structure which is free to rotate around an axis and which supports a plurality of magnets 21 at spaced locations around the ring, each magnet (21) being supported on the ring-like member by a bearing such that it is free to rotate about an axis that is tangential to the ring. The two ring-like structures (1, 2) are supported relative to one another such that upon rotation of the second ring-like structure about its axis, the magnets (21) of that structure follow a path that passes through each of the actuators whereby the magnets of the actuators exert a force on the magnets (21) of the second ring-like structure which causes the magnets (21) to rotate about their axis.

Description

APPARATUS FOR APPLYING ACCELERATIVE FORCE

This invention relates to improvements in apparatus for producing an accelerative force, such as may be applied to a sample. It may have application in laboratories or in educational establishments.

Various devices are known for generating an accelerative force. One example of such a device is a centrifuge. A centrifuge is a piece of equipment that puts a sample in rotation around an axis in order to place the sample under a centrifugal force. This effect can be used to separate a fluid from a fluid or from a solid substance. Many different types are available. The faster the sample is spun the higher the force applied to the sample.

In other applications, devices may be used to provide a rotational force to equipment to accelerate the equipment, or to provide a retardation or braking effect. The electric motor (AC or DC) is an example of apparatus for such a purpose. It is not therefore always essential that such devices can provide a force to a sample. They can also be used as educational models to demonstrate physical principles.

An object of the present invention is to improve on the basic design of a device for producing an accelerative force.

According to a first aspect the invention provides an apparatus for use in producing accelerative forces, comprising: a fixed portion comprising a first ring-like structure that supports a plurality of actuators spaced around its perimeter, each actuator comprising a generally C-shaped support frame that lies in a plane orthogonal to the ring-like support structure and orthogonal to the axis of the ring-like structure; each support frame carrying one or magnets; a rotating portion comprising a second ring-like structure which is free to rotate around an axis and which supports a plurality of magnets at spaced locations around the ring, each magnet being supported on the ring-like member by a bearing such that it is free to rotate about an axis that is tangential to the ring; and in which the two ring-like structures are supported relative to one another such that upon rotation of the second ring-like structure about its axis, the magnets of that structure follow a path that passes through each of the actuators whereby the magnets of the actuators exert a force on the magnets of the second ring-like structure which causes the magnets to rotate about their axis.

The magnets may include a recess or container into which a sample can be placed. Alternatively, they may be attached to a carrier having a recess which can rotate with the magnets.

The invention may therefore provide, in one arrangement, apparatus for producing a rotational accelerational force either to a sample in a carrier or for educational purposes .

Each magnet of the second ring-like structure may be supported on a bearing formed from a pin that passes through a body of the magnet (or carrier attached thereto) and is supported in two stubs which project axially from the rotating ring-like member.

The magnet or its carrier may be weighted about the axis so that it prefers to rest in one orientation (with the heavy part vertically below the rotational axis) . The manner in which the magnets rotate as the second ring-like support rotates is dependent upon the location of the magnets on both the actuators and the sample carriers.

There may be at least 10 and preferably 12 or more actuators. There may be same number of magnets on the second ring-like structure. It is perhaps preferred that there are the same number of each so as to balance the forces on the ring-like members at all times.

Each actuator may support 4 magnets. They are preferably equispaced. These may extend inwardly from the C-shaped support towards its axial centre position. They may comprise 2 north poles adjacent one another and two south poles.

Each magnet of the second ring-like structure may comprise a single magnet having a north pole and a south pole on opposite sides of the axis of rotation.

The magnet (and any carrier attached to it) may fit within the actuator such that only a small air gap exists between the magnets of the carrier and the actuator. In other words, with a magnet located within an actuator and made to spin, the magnets would just skim past each other.

The operation of the device is best understood by drawing parallels with electric brushless permanent magnet motors. As a sample carrier enters an actuator the magnets on the carrier will attempt to align themselves with the magnets on the actuator by rotation. In other words, the North pole of the carrier will move towards the south pole of the actuator. This is the mechanism by which the carriers rotate. If the magnets of each actuator in turn around the ring are offset slightly clockwise then each time a carrier passes through it will be given a slight push clockwise to "follow" the actuator magnets.

Where N actuators are provided the magnets of the actuators may be offset from the magnets of an adjacent actuator by 360-N degrees. This will cause the carrier to rotate through one complete revolution on each turn of the ring-like support.

Of course, other alignments of actuator magnets can be provided. They may, for example by offset clockwise over half of the ring-like support and then anti-clockwise over the other half to cause the sample carrier to oscillate back and forth through 180 degrees as the ring-like support is rotated through a complete revolution.

The fixed portion and the rotating portion may be supported by a base portion. This may comprise a cradle having a base and two spaced upstanding arms. A spindle may connect the arms, supported in a bearing at each end where it passes through an arm. The spindle may pass through an opening in the fixed disk and the rotating disk. The rotating disk may be secured in place on the spindle. Each disk may be fixed to a respective arm by one or more bolts or rivets or other suitable fastener.

The magnets may each comprise permanent magnets. Alternatively the magnets of the fixed portion may comprise electro-magnets. It is also possible for the magnets of each sample carrier to comprise electromagnets. This may require one or more slip-rings to carry current to the rotating parts.

An advantage of providing electromagnets on the fixed part are that the polarity of the magnets can easily be altered. This could allow the behaviour of the apparatus to be modified in use, as the disk is rotating. The support brackets may be spaced around the disk as described or may in fact link up with the adjacent ones to form a continuous support structure having the form of a toroid. Of course, there will still be a need for a slit that permits entrance of the mount for the sample carriers to enter into the toroid.

The apparatus may include a surround which receives the fixed and rotating parts and which may be evacuated. This permits the rotating part to move within a vacuum, removing resistance that may otherwise be caused by the presence of air.

The rotating disk may be supported by one or more very low or near zero friction bearings . Together with the presence of a vacuum this will permit the disk, once spinning, to continue to spin under its own forces for a very long time.

The apparatus may be constructed from a variety of different materials. Metal is preferred, such as steel or brass, as they are hard wearing and easy to obtain and machine.

There will now be described, by way of example only, one embodiment of the present invention with reference to and as illustrated in the accompanying drawings of which:

Figure 1 is a computer generated isometric view of an apparatus in accordance with the present invention;

Figure 2 is a side cross sectional view of the apparatus of Figure 1; Figure 3 (a) is an end view of the apparatus of Figure 1 ;

Figure 3 (b) is a view of a magnet attached to a rotating ring of the apparatus;

Figure 4 is an exploded isometric view of the apparatus of Figure 1 showing clearly the fixed and rotating parts; and

Figure 5 is a diagram to assist in understanding of the relative orientation of the magnets of the 13 C-shaped brackets mounted on the fixed part of the apparatus of Figure 1.

In brief, the apparatus comprises two main parts 1 , 2 fixed to a U-shaped support bracket 3. Each part comprises a disk or ring shaped support. One support 10 is fixed and the other 20 is supported on an axle 22 so that it can rotate, with both discs 10, 20 aligned about the common axis and in close parallel arrangement. The rotating disc 20 carries a set of magnets or carriers 21 attached through a bearing 23 so they can rotate. The fixed disk 10 also carries a set of magnets 11, 12, 13, 14. The magnets on the fixed disk 10 exert a force on the magnets 21 on the rotating disk 20. This force can be arranged such the that magnets 21 rotate relative to their mounting on the rotating disk as that disk rotates .

In more detail the base portion 3 comprises a U-shaped cradle having a base 3a and two spaced upright arms 3b, 3c. A spindle axle 22 passes across the bracket between the two arms. It is supported on bearings 22a, 22b at each end which fit within holes in the arms that receive the ends of the spindle. The fixed part 1 comprises a supporting disk 10 that is fixed in an upright position to one upright 3b of the upright arms of the base portion 3 by one or more bolts 15. A hole in the centre of the disk is provided which is larger in diameter than the spindle 22 to ensure they do not contact one another and the disk 10 is aligned with the spindle passing through this hole.

Around an outer circumference of the disk 10 are a set of spaced holes 16. Each hole is the same distance from the central axis of the disk and equi-distant circumferentially from neighbouring holes. The holes receive bolts which engage in a C-shaped support ring 17. The rings 17 are fixed to their disc by the bolt such that the open section of the C (between the two opposing ends) faces away from the disk. Each C shaped support 17 is also aligned such that it lies in a plane that passes through the axis of the supporting disk. As shown in the figures 12 C-shaped brackets are provided. Together, the brackets 17 form portions of an imaginary annulus that extends around the outside of the disk passing through each bracket. As will become apparent this defines a path through which the set of magnets 21 can pass.

Each C-shaped support bracket 17 is provided with four magnets 11 , 12, 13, 14 that extend from the support towards the centre of the C-shaped bracket. The magnets extend inwardly for about half way from the support 17 to the centre so that they do not contact one another. The magnets are spaced 90 degrees apart so that they form two opposing pairs. Each magnet 11, 12, 13, 14 of an opposing pair has its south pole facing the centre and the other its north pole. Therefore, working round the bracket the magnet poles facing the centre are North, South, North and then South. The rotating part 2 is shown in detail in Figure 2. This comprises a disk 20 of approximately the same diameter as the fixed disk 10. Instead of being fixed to the base portion it is journaled to the spindle 22 such that it is in register with the fixed disk 10. The journalled fastening may comprise an interference fit between a hole at the centre of the disk and a grub screw which ensures they are prevented from relative rotation. The disk 20 can therefore spin as the spindle 22 is rotated. This may be by a motor (not shown) attached to one end of the spindle.

Around a circumference of the disk 20 are a set of holes. These have the same radial spacing as the holes in the fixed disk but rather than supporting C-shaped brackets 17 they support sample carriers as will be described. The carriers project from the side of the disk facing the fixed disk and are located within the imaginary annular path defined by the C- shaped brackets.

Each sample carrier comprises a magnet 21 that is supported on a pin that projects from each end of the magnet to pass through holes in two support stubs that project from the rotating disk 20. The axis of the pin is aligned such that it is tangential to the circumference of the disk that passes through the holes in the disk. The magnet can therefore spin about the axis defined by this pin as well as the magnet rotating as the disk rotates.

The magnet 21 that projects equally from each side of the axis of rotation defined by its support pin. Thus one North pole protrudes from one side and the south from the other.

The two disks 10, 20 are aligned with each other so that the magnet 21 are located within the centre of the support 17, including its magnet and weight is sized such that it fits snugly within the magnets of the support brackets and can rotate without interfering physically. As will be appreciated the magnets 11, 12, 13, 14 in the C-shaped brackets 17 will exert a magnetic force on the magnets 21 as they pass through the C-shaped bracket upon rotation of the rotating disk 20. By careful placing of the magnets on the C-shaped brackets, the sample carrier can be made to rotate about its axis as the disk rotates causing it to follow a helical path.

The location of the magnets 11, 12, 13, 14 in this embodiment is shown in Figure 5. As can be seen, the magnets are aligned such that the sample carrier magnet 21 is caused to rotate through one complete revolution about its axis for each complete revolution of the rotating disk 20.

Claims

1. An apparatus for use in producing accelerative forces, comprising: a fixed portion comprising a first ring-like structure that supports a plurality of actuators spaced around its perimeter, each actuator comprising a generally C-shaped support frame that lies in a plane orthogonal to the ring-like support structure and orthogonal to the axis of the ring-like structure; each support frame carrying one or magnets; a rotating portion comprising a second ring-like structure which is free to rotate around an axis and which supports a plurality of magnets at spaced locations around the ring, each magnet being supported on the ring-like member by a bearing such that it is free to rotate about an axis that is tangential to the ring; and in which the two ring-like structures are supported relative to one another such that upon rotation of the second ring-like structure about its axis, the magnets of that structure follow a path that passes through each of the actuators whereby the magnets of the actuators exert a force on the magnets of the second ring-like structure which causes the magnets to rotate about their axis.

2. Apparatus according to claim 1 in which the magnets include a recess or container into which a sample can be placed.

3. Apparatus according to claim 1 or claim 2 in which each magnet of the second ring-like structure is supported on a bearing formed from a pin that passes through a body of the magnet or carrier attached thereto and is supported in two stubs which project axially from the rotating ring-like member.

4. The apparatus according to any preceding claim in which the magnet or its carrier is weighted about an axis so that it prefers to rest in one orientation.

5. The apparatus of any preceding claim in which there are at least 10 or 12 or more actuators.

6. The apparatus of any preceding claim in which there are the same number of magnets on the second ring-like structure as there are on the first.

7. The apparatus of any preceding claim in which each actuator supports 4 magnets.

8. The apparatus of any preceding claim in which the magnets extend inwardly from the C-shaped support towards its axial centre position.

9. The apparatus of any preceding claim in which each magnet of the second ring-like structure comprises a single magnet having a north pole and a south pole on opposite sides of the axis of rotation.

10. The apparatus of claim 9 in which the magnet fits within the actuator such that only a small air gap exists between the magnets of the carrier and the actuator.

11. The apparatus of any preceding claim in which the fixed portion and the rotating portion are supported by a base portion.

12. The apparatus of claim 11 in which the base portion comprises a cradle having a base and two spaced upstanding arms, and a spindle which connect the arms, supported in a bearing at each end where it passes through an arm, the spindle further passing through an opening in the fixed disk and the rotating disk with the rotating disk being secured in place on the spindle.

13. The apparatus of any preceding claim in which the magnets each comprise permanent magnets .

14. The apparatus of any preceding claim which includes a surround which receives the fixed and rotating parts and which defines a space which can be evacuated of air to permits the rotating part to move within a vacuum.