GB2282009A

GB2282009A - Using magnetic drive permanent magnets

Info

Publication number: GB2282009A
Application number: GB9315284A
Authority: GB
Inventors: Gary Lewis
Original assignee: FLETCHER DEVELOPMENTS Ltd
Current assignee: FLETCHER DEVELOPMENTS Ltd
Priority date: 1993-07-23
Filing date: 1993-07-23
Publication date: 1995-03-22
Also published as: GB9315284D0

Abstract

A magnetic drive mechanism to be used in motors which comprises a first component 1 and a second component 2, in which the first component 1 includes a number of magnetic poles and the second component includes at least one drive magnet 4. The two components are arranged so that the drive magnet 4 of the second component 2 is movable along the magnetic pole sequence of the first component 1, and gearing 8 is provided so as to orientate the drive magnet 4 with respect to the poles of the first component 1. A linear machine is disclosed. <IMAGE>

Description

DRIVE MECHANISM The present invention relates to a magnetic drive mechanism to be used in motors.

According to the invention there is provided a magnetic drive mechanism comprising a first part and a second part, the first part including a number of magnetic poles arranged alternately and the second part having at least one movably mounted drive magnet, the two parts being connected so as to allow movement of the drive magnet along the magnetic pole sequence and the mechanism further including a gearing arranged to move the drive magnet periodically during the said movement in such a way that as this magnet passes over the sequence of magnetic poles of the first part its own poles always move into corresponding orientations with respect to corresponding poles of the first part.

The preferred arrangement is for at least the first component part to be a circular disc, the second component part being arranged to rotate with respect to it, the poles being arranged regularly as circular sectors in the circumferential direction of the first component.

With embodiments of the invention it is ensured that the magnetic forces of the poles on the or each drive magnet are repeated as it passes over each pole in turn. Hence once the moving component is started it will continue to rotate in the same direction.

The drive magnets are preferably arranged above the plane of the first component and rotatably arranged on the second component so as to rotate about an axis either parallel to this plane or perpendicular to it.

For a better understanding of the invention three embodiments will now be explained in greater detail with the aid of the Figures, in which Figs. 1A and lB show the two components of a first embodiment of the invention; Fig. 2 shows a second embodiment; Fig. 3 shows a third embodiment using shaftmounted drive magnets; and Figs. 4A-4C show a reciprocating embodiment.

Figs. 1A and 1B show the two main component parts of the drive mechanism respectively. The lower part 1 is a ten-pole magnetic disc, the poles being distributed evenly in the circumferential direction as shown. The disc 1 is here arranged in a stationary manner.

Fig. 1B shows the upper disc 2, here called the plate drive disc. This disc corresponds in size to the magnetic disc 1 and is mounted coaxially with it in a rotatable manner. The plate drive disc 2 carries a number of circumferentially distributed drive magnets 4 in the form of smaller discs; this number corresponds to the number of pole pairs on the magnetic disc 1, i.e. five. The drive magnets are arranged with their north-south axes facing parallel to the plane of the drive magnet 4.

Each drive magnet 4 is mounted rotatably on the drive disc 2, about an axis parallel to the main axis, via a suitable platform or base 5. A gearing arrangement, shown schematically in Fig. 1B, links the rotation of the magnets 4 to that of the plate drive disc in a manner explained below.

The purpose of the gearing is to synchronize the rotation of the drive magnets 4 with that of the plate drive disc 2 in such a way that, denoting the number of pairs of magnetic poles on the magnetic disc 1 by n, the drive magnets complete n revolutions about their axes, relative to the drive disc 2, every time the drive disc rotates once relative to the magnetic disc.

As a result each magnet 4 is always in the same orientation as it passes over corresponding points on the main disc poles 1. This is indicated by the three positions A, B and C of one drive magnet 4 at different stages of rotation shown in Fig 1A, discussed below.

In Fig. 1B there is a sun-and-planet gearing indicated at 8, the sun being fixed to the magnetic disc 1 and the planets to the drive disc 2. Hence as the drive disc rotates the outer ring 9 rotates at a somewhat higher speed, in turn driving the drive magnets 4 as required.

It will be seen that in position A the drive magnet 4 is being urged by the disc 1 in the anticlockwise direction. As it moves in this direction it takes with it the drive disc 2. This rotation of the drive disc causes the outer ring 9 to rotate, and the outer teeth of the ring then turn the bases 5 of the drive magnets. With the correct gear ratios the drive magnet 4 will assume the tangential position B by the time its axis is opposite the half-way point between the poles of the magnetic disc 1. In this position there is no circumferential force on the magnet 4, but its momentum keeps it going until it reaches position C in which the forces on it are again anticlockwise, and so on.

In the alternative version shown in Fig. 2A the drive disc 20 is smaller than the magnetic disc, although it is again mounted rotatably about the central axis. The drive magnets 24 have their northsouth axes in a tangential plane and are mounted rotatably this time about horizontal radial axes and are connected to a central armature 26. The gearing, which is not shown, ensures that the drive magnets 24 turn over by one half-revolution as they rotate about the central axis from a north pole to a south pole and vice versa.

Fig. 3 illustrates a further variation in which there are only two drive magnets 34 and they are mounted on a shaft 30 rather than a disc. The north south axis of the poles of the magnets 34 is as in Fig.

2 oriented tangentially to the axis of the disc 1. The shaft 30 is connected by gearing 38 so that it rotates about its own axis by half a turn as the shaft 230 rotates about the disc axis.

This invention has been described with reference to rotary arrangements, but it is clear that it could also be applied to linear constructions, using a rackand-pinion gearing for instance to correlate the rotation of a drive magnet with a fixed series of magnetic pole pairs. Also, the alternating movement of the drive magnets has been described in terms of rotation, but a reciprocatory movement would also be possible.

Such a reciprocating version of the invention is shown in Figs. 4A-C. Figs. 4A and 4B, views in elevation, show the two drive magnets 44 on a crankshaft 40. Gears 42, shown only schematically, are arranged so that the drive magnets rotate about vertical axes at the same time as they travel up and down on the cranks. The axis of the crankshaft 40 is connected by further gears to the rotation of the plate drive disc 1 so that each drive magnet 44 is in its lowered position every time it passes over a pole of the drive disc 1, as shown in Fig. 4C, and in the corresponding orientation. In this embodiment the drive magnet 44 is lowered towards each pole of one polarity, and is then rotated a half-turn before descending over the adjacent pole of the other polarity. This gives the same directional force in each case. In a simpler arrangement, however, the crankshaft could rotate at only half the speed so that the drive magnets 44 would be lowered over, say, only the north poles, keeping its orientation.

Claims

Claims:

1. A magnetic drive mechanism comprising a first part and a second part, the first part including a number of magnetic poles arranged alternately and the second part having at least one movably mounted drive magnet, the two parts being connected so as to allow movement of. the drive magnet along the magnetic pole sequence and the mechanism further including a gearing arranged to move the drive magnet periodically during the said movement in such a way that as this magnet passes over the sequence of magnetic poles of the first part its own poles always move into corresponding orientations with respect to corresponding poles of the first part.

2. A magnetic drive mechanism according to claim 1 in which the said corresponding orientations are such that there is a net force tending to rotate the second part with respect to the first part.

3. A magnetic drive mechanism according to claim 1 or 2 in which the first part is constructed as a circular disc.

4. A magnetic drive mechanism according to claim 3 in which the poles are arranged regularly as circular sectors in the circumferential direction of the first part.

5. A magnetic drive mechanism according to claim 3 or 4 in which the or each drive magnet is arranged above the plane of the first part and is rotatably arranged on the second part so as to rotate about an axis parallel to this plane.

6. A magnetic drive mechanism according to claim 3 to 4 in which the or each drive magnet is arranged above the plane of the first part and is rotatably arranged on the second part so as to rotate about an axis perpendicular to this plane.

7. A magnetic drive mechanism according to any preceding claim in which the first part is a ten-pole magnetic disc.

8. A magnetic drive mechanism according to any preceding claim in which the number of drive magnets on the second part corresponds to the number of pole pairs of the first part.

9. A magnetic drive mechanism according to any one of claims 1 to 7 in which there are two drive magnets on the second part.

10. A magnetic drive mechanism according to any preceding claim in which the or each drive magnet is mounted on a disc.

11. A magnetic drive mechanism according to any one of claims 1 to 9 in which the or each drive magnet is mounted on a shaft.

12. A magnetic drive mechanism according to claim 1 in which the or each drive magnet is arranged on a crank shaft such that the or each drive magnet is able to rotate about a vertical axis and travel up and down.

13. A magnetic drive mechanism substantially as described herein with reference to the accompanying Figures 1 to 3, or the accompanying Figure 4.