GB1561582A

GB1561582A - Magnetic drivemeans

Info

Publication number: GB1561582A
Application number: GB18951/76A
Authority: GB
Original assignee: Blache L A
Current assignee: Blache L A
Priority date: 1977-05-09
Filing date: 1977-05-09
Publication date: 1980-02-27

Description

(54) IMPROVEMENTS IN OR RELATING TO MAGNETIC DRIVE MEANS (71) I, Louis ANDRE BLACHE, of 2C Bartholomew Villas, L.ondon NW5 2LL, a British subject, do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be perfcrmec;, to be particularly described in and by the following statement: The invention relates to magnetic drive means.

According to the invention, a magnetic drive means comprises a plurality of magnetic elements movable on a path to bring each of the magnet elements in succession to a given position, the magnet elements being so arranged that the polar orientatizan of each magnet element at the given position is angularly displaced from that of the precedmg magnet element thereat by less than 180 so as to transmit a rotational drive to a member located so as to be magnetically coupled with the successive magnet elements arriving at the position.

The invention also provides a magnetic drive means comprising a support rotatable about an axis and magnet means mounted on she support and extending around a circle centred on the axis, the polar orientaion of the magnet means at different positions around the circle making different angles with the radii at these positions whereby a magnetic member rotatable about a fixed axis parallel to and spaced from the axis and positioned to be magnetically coupled with the magnet means receives a rotatable drive when the support is rotated.

In a simple embodiment of the invention, a support carries a plurality of permanent magnets equally spaced around a circle and having their polar orientations with respect to the radii of the circle on which they lie progressively increased around the circle by equal increments. Rotation of the support about the centre of the circle by a suitable drive will effect rotation of any driven member which is positioned to be magnetically coupled with the permanent magnets. It will be evident that the nature of the rotation of the driven members is dependent on the spacing and orientation of the permanent magnets which can be selected to obtain a wide variety of output movements.

The invention is further explained in the following illustrative description in which reference is made to the accompanying drawing. In the drawing: Figure 1 is a fragmentary schematic side view partly in section of an apparatus including a magnetic drive means embodying the invention taken on the line I-I of figure 2; and Figure 2 is a schematic plan view of a drive member of the drive means of figure 1.

The apparatus illustrated comprises a frame arranged for the support of test tubes 1 the liquid contents of which are to be examined optically to determine changes in opacity. The frame and the arrangements for measuring opacity are mentioned only for explanation of the present invention and are not shown. To enable the optical observations to be carried out, it is necessary for the contents of the test tubes 1 to be stirred, and it is to the stirring arrangements that the present invention is applied.

Each of the test tubes 1 contains besides the liquid under test a stirrer 5 in the form of a small permanent magnet coated with a plastics material to prevent chemical interaction between the magnet and the liquid. Each magnetic stirrer 5 is free within the liquid in the test tube and is caused to rotate so as to effect stirring by a magnetic drive means in accordance with the invention.

The frame of the apparatus supports twelve test tubes 1 mounted upright in a circle. A horizontal plate 10 or other support of non-magnetic material underlies the lower ends of the test tubes 1 and is rotatable about a vertical axis on which the group of test tubes 1 is centred. The plate 10 can be rotated in any suitable way.

Conveniently as shown, the plate 10 is carried directly on the upright drive shaft of an electric motor 12 but if desired speed reduction or control means can be provided between the motor drive shaft and a driven second shaft with which the plate 10 rotates.

Magnetic means for imparting motion to the stirrers 5 is carried at the upper side of the plate 10, the magnetic means being distributed about a circle directly underlying the lower ends of the test tubes 1. As shown, the magnetic means comprises twelve permanent magnets 14 to 25, each bolted or otherwise fixedly secured to the plate 10. The magnets 14 to 25 are equally spaced around the circle on which they lie but each has a different orientation of its poles with respect to the radius of the circle passing through it. Thus the uppermost magnet 14 as shown in figure 2 has its poles aligned along the radius. The next adjacent magnet 15 to the right has its poles on a line turned through 30 in the clockwise direction relative to the radius passing through it, and the poles of the next magnet 16 are on a line turned through a further 30 , and so on, so that the magnet 25 to the left of the magnet 14 has its poles on a line turned 30 anticlockwise to the associated radius. As the plate 10 rotates, the magnet of each stirrer 5 will tend to align itself with the drive magnet which is for the time being underneath it, because of the attraction of unlike poles, so that as the plate 10 rotates through 360" each stirrer 5 is urged to rotate through 360".

A simple and convenient way of driving a plurality of stirrers from a single motor is thus provided.

The simple arrangement described and illustrated is capable of considerable modification and the invention is applicable to the drive of other things than stirrers. It will be evident that the number of drive and driven magnets need not correspond and that the apparatus can have two or more concentric arrays of drive and driven magnets. The driven member can be arranged to rotate at a speed which is a multiple of the drive member speed. The smaller the peripheral spacing of the drive magnets, the smoother will be the rotation of the driven magnet or magnets; an annular magnet with appropriate magnetization can provide an effectively continuous drive.

The invention also offers the possibility of obtaining from a steady rotation input an output of desired discontinuous form. The drive magnetization can be readily arranged, during each complete rotation thereof, to impart to the or each driven magnet a rotational movement which can include as desired any or all of variations of speed, interruptions of movement, and partial or complete reversals. Where the driye magnetization comprises discrete permanent magnets, the magnets can be mounted on a support in a manner facilitating adjustment of the orientation and/or angular spacing thereof.

It will thus be evident that the invention can be embodied in a variety of ways to provide a magnetic drive or transmission which is at once simple and extremely flexible.

WHAT I CLAIM IS: 1. A magnetic drive means comprising a plurality of magnetic elements movable on a path to bring each of the magnetic elements in succession to a given position, the magnet elements being so arranged that the polar orientation of each magnet element at the given position is angularly displaced from that of the preceding magnet element thereat by less than 1800 so as to transmit a rotational drive to a member located so as to be magnetically coupled with the successive magnet elements arriving at the position.

2. A magnetic drive means as claimed in claim 1 in which the magnet elements are arranged to be moved around a circular path, the polar orientation of each magnet element being in the plane of the path.

3. A magnetic drive means comprising a support rotatable about an axis around a circle centred on the axis, the polar orientation of the magnet means at different positions around the circle making different angles with the radii at these positions whereby a magnetic member rotatable about a fixed axis parallel to and spaced from the axis and positioned to be magnetically coupled with the magnet means receives a rotatable drive when the support is rotated.

4. A magnetic drive means as claimed in claim 1, 2 or 3 arranged to effect continuous rotation of the member.

5. A magnetic drive means as claimed in claim 1, 2, 3 or 4 arranged to effect unidirectional rotation of the member.

6. A magnetic drive means as claimed in claim 1 in which the magnet elements comprise permanent magnets carried on a support rotatable about an axis at positions equally spaced around a circle concentric with the axis.

7. A magnetic drive means as claimed in claim 3 in which the magnet means comprises a plurality of magnets secured to the support at positiones equally spaced around the circle.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. circle. A horizontal plate 10 or other support of non-magnetic material underlies the lower ends of the test tubes 1 and is rotatable about a vertical axis on which the group of test tubes 1 is centred. The plate 10 can be rotated in any suitable way. Conveniently as shown, the plate 10 is carried directly on the upright drive shaft of an electric motor 12 but if desired speed reduction or control means can be provided between the motor drive shaft and a driven second shaft with which the plate 10 rotates. Magnetic means for imparting motion to the stirrers 5 is carried at the upper side of the plate 10, the magnetic means being distributed about a circle directly underlying the lower ends of the test tubes 1. As shown, the magnetic means comprises twelve permanent magnets 14 to 25, each bolted or otherwise fixedly secured to the plate 10. The magnets 14 to 25 are equally spaced around the circle on which they lie but each has a different orientation of its poles with respect to the radius of the circle passing through it. Thus the uppermost magnet 14 as shown in figure 2 has its poles aligned along the radius. The next adjacent magnet 15 to the right has its poles on a line turned through 30 in the clockwise direction relative to the radius passing through it, and the poles of the next magnet 16 are on a line turned through a further 30 , and so on, so that the magnet 25 to the left of the magnet 14 has its poles on a line turned 30 anticlockwise to the associated radius. As the plate 10 rotates, the magnet of each stirrer 5 will tend to align itself with the drive magnet which is for the time being underneath it, because of the attraction of unlike poles, so that as the plate 10 rotates through 360" each stirrer 5 is urged to rotate through 360". A simple and convenient way of driving a plurality of stirrers from a single motor is thus provided. The simple arrangement described and illustrated is capable of considerable modification and the invention is applicable to the drive of other things than stirrers. It will be evident that the number of drive and driven magnets need not correspond and that the apparatus can have two or more concentric arrays of drive and driven magnets. The driven member can be arranged to rotate at a speed which is a multiple of the drive member speed. The smaller the peripheral spacing of the drive magnets, the smoother will be the rotation of the driven magnet or magnets; an annular magnet with appropriate magnetization can provide an effectively continuous drive. The invention also offers the possibility of obtaining from a steady rotation input an output of desired discontinuous form. The drive magnetization can be readily arranged, during each complete rotation thereof, to impart to the or each driven magnet a rotational movement which can include as desired any or all of variations of speed, interruptions of movement, and partial or complete reversals. Where the driye magnetization comprises discrete permanent magnets, the magnets can be mounted on a support in a manner facilitating adjustment of the orientation and/or angular spacing thereof. It will thus be evident that the invention can be embodied in a variety of ways to provide a magnetic drive or transmission which is at once simple and extremely flexible. WHAT I CLAIM IS:

1. A magnetic drive means comprising a plurality of magnetic elements movable on a path to bring each of the magnetic elements in succession to a given position, the magnet elements being so arranged that the polar orientation of each magnet element at the given position is angularly displaced from that of the preceding magnet element thereat by less than 1800 so as to transmit a rotational drive to a member located so as to be magnetically coupled with the successive magnet elements arriving at the position.

8. A magnetic drive means as claimed in

claim 6 or 7 having three or more of the magnets and in which the angles between the iines extending between the poles of the magnets and the radii of the support bisetting these lines increase successively around the circle by equal amounts.

9. A magnetic drive means as claimed in claim 6, 7 or 8 in which the magnets are mounted on the support in a manner facilitating adjustment of the orientation and joy angular spacing thereof.

10. A magnetic drive means as claimed in claim 6, 7, 8 or 9, in which the axis about which the support is rotatable is a vertical axis and in which a frame is arranged to mount a plurality of test tubes in generally upright positions with the lower ends thereof over the circle, whereby magnetic stirrers suspended in liquid in the test tubes are magnetically rotatable by the rotation of the support.

11. A magnetic drive means substantially as herein described with reference to the accompanying drawings.