US3223898A

US3223898A - Variable magnet

Info

Publication number: US3223898A
Application number: US194026A
Authority: US
Inventors: Ahmet K Bey
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-05-11
Filing date: 1962-05-11
Publication date: 1965-12-14
Anticipated expiration: 1982-12-14

Description

A. K. BEY

VARIABLE MAGNET Dec. 14, 1965 Filed May 11, 1962 INV EN TOR.

United States Patent 3,2233% VARIABLE MAGNET Ahmet K. Bey, Chicago, lll., assignor to Frances Budreck, Chicago, ill. Filed May 11, 1962, Ser. No. 194,026 3 Claims. (Cl. 317159) The present invention relates to variable magnets. Particularly it relates to magnetic apparatus adapted to adjust their ranges of magnetic intensity gradually between full strength and zero. Specifically, the invention relates to variable magnets in which the magnetic fields can be adjusted in intensity between zero and maximum strength without the use of electrical energy.

In designing various apparatus, the need often arises for a magnetic apparatus which is capable of providing a magnetic field of variable intensity. For example, lifting mechanisms which employ a magnetic field, normally require that the apparatus providing the magnetic field be controllable whereby magnetic materials can be either picked up or released. Similarly, in various magnetic latching apparatus, as the type used on refrigerator doors, it is desirable that the intensity of the magnetic field be controllable.

In addition to the types of apparatus indicated above, wherein the magnetic field is essentially either on or off, there exists a need for a magnetic means capable of providing a magnetic field which may be continuously varied in intensity over a range between the on and off limits. An exemplary use of an apparatus which is capable of providing a variable-intensity magnetic field is in controlling or focusing an electron beam as utilized in electronic systems.

In the past, electromagnets have been widely used to provide variable-intensity magnetic fields. That is, electromagnets, consisting of a coil of conductive wire wound upon a core of iron, provide a magnetic field which varies in accordance with the electrical current passed through the coil. As a result, the intensity of the magnetic field may be controlled by varying the magnitude of the electrical current passing through the coil. While electrom-agnets have wide application, these magnets are generally expensive to manufacture and design. Furthermore, electromagnets must be supplied with electrical energy during operation, and are generally quite large relative to the maximum intensity of the magnetic field provided. A need exists for an economical variable magnetic means of small physical size which is capable of producing a large magnetic intensity relative to its size.

One of the problems existent in prior art devices of the class described hereinafter has been that a certain amount of leakage of magnetic energy is present at the non-magnetic gaps when the devices are in off or nonmagnetic positions. It would appear, therefore, that such devices, although entirely useful in lifting and latching, are not best suited for use in connection with all sensitive electrical equipment because of possible interference resulting from the magnetic leakage. It is apparent that a need exists for a variable magnet which does not rely on electrical energy in which there is no leakage when the magnet is in the off position.

The present invention, in its more general form, comprises a permanent magnet, pole pieces which are secured on opposite sides of such permanent magnet, and another permanent magnet rotatable within said first magnet, whereby a magnetic field is provided in the nonmagnetic gap between the pole pieces which can be adjusted in intensity to vary over a range from maximum intensity to zero upon relative rotation of the permanent magnets through 180 degrees.

It is, therefore, an object of the invention to provide an improved variable magnet.

Another object of the invention is to provide a variable magnetic apparatus which may be economically designed and manufactured.

A further object of the invention is to provide a variable magnetic means which does not require a supply of electrical energy.

A still further object of the invention is to provide a variable :magnet which may be embodied in a physical structure of relatively small size.

Still another object of the invention is to provide, in a variable magnet, which does not require a supply of electrical energy, a magnetic field which can be completely cut off.

Other and further objects and advantages of the invention will become apparent from the following description and appended claims, reference being had to the accompanying drawings, and the numerals of reference thereon.

On the drawings:

FIG. 1 is an exploded view, in perspective, of one embodiment of the invention.

FIG. 2 is a longitudinal sectional view of the embodiment, taken on the line 22 of FIG. 4 and looking in the direction of the arrows.

FIG. 3 is a longitudinal sectional view of the embodiment, taken on the line 3-3 of FIG. 5 and looking in the direction of the arrows.

FIG. 4 is an end view of the device as seen from the bottom of FIG. 2.

FIG. 5 is an end view of the device as seen from the bottom of FIG. 3.

Referring now more particularly to the drawings, the illustrated form of the distinctive variable magnet or magnetic apparatus comprises a solid permanently magnetized core 10 fabricated from preferably ferrite or other suitable materials, having high retentivity. The exterior form is preferably cylindrical to permit relative rotation of the core 10, for a reason that will hereinafter become apparent. The core 10 is magnetized transversely to the axis of rotation of the cylindrical form of said core, as illustrated in FIGS. 2, 3, 4, and 5. I have designated the polarity of the core 10, and of the sleeve or cylinder 11, which will hereinafter be described, by the letters N and S to designate, respectively, north and south.

A second permanent magnet is provided. The second permanent magnet may be fabricated from ferrite or other magnetic materials having high retentivity. The form of the second magnet is preferably cylindrical to provide a sleeve 11 for disposition about the magnet 10, in a manner that will permit relative rotation of the core 10 and the sleeve 11. The sleeve 11 is permanently magnetized so that the opposite poles are disposed transversely of the axis of rotation on which the form of the sleeve is generated. As previously indicated, the north and south poles are designated by appropriate letters in the drawings.

The internal diameter of the cylinder 11 is slightly larger than the external diameter of the core 10, whereby when the two permanent magnets are assembled, as illustrated in the drawings, a slight non-magnetic gap is provided between the exterior surface of the core 10 and the interior surface of the sleeve 11 which permits the parts to be relatively rotated with respect to each other. It will be appreciated, by having reference to the drawings, that magnetization of the core 10 and the sleeve 11 provides, in each thereof, a north polarity throughout the one-half of the contiguous mass of each, and a south polarity throughout the remaining contiguous mass, with the opposite (polarities arranged diametrically, rather than axially.

A curved pole plate 12, the interior radius of curvature of which is substantially the same as the radius of curvature of the exterior of sleeve 11, is rigidly secured to the sleeve 11 by suitable means, such as synthetic resin or the like, well known to those skilled in the art. The pole plate 12 is fabricated from a magnetizable material, such as steel or other ferrous material; and in the device illustrated, pole plate 12 is centeredvon the surface of the sleeve 11 within the north magnetic field, with the center of said .pole plate 12 disposed in a diametrically opposite position from a pole plate 13.

The pole plate 13 is preferably substantially in the same form as the pole plate 12 and preferably fabricated in a like manner therewith. It is secured on the surface of the sleeve 11 by any suitable means, such as a synthetic resin or the like, well known to those skilled in the art. The longitudinal axis of the interior surface of pole plate 13 is disposed along a line on the surface of the sleeve 11, in which there is the strongest south polarity. This arrangement, of course, centers the pole plate 13 in the south magnetic field, and

places pole plates

12 and 13 in diametrically opposite disposition. Accordingly, non-magnetic gaps areiprovided between the sides of the

pole plates

12 and 13 in the spaces designated by the numerals 14 and 15, in FIGS. 4 and 5..

When the core 10, the sleeve 11 and the

pole plates

12 and 13 are assembled as illustrated in FIGS. 2, 3, 4 and 5, a variable magnet or magnetic apparatus is provided. When the position of the component is as illustrated in FIGS. 2, and 4, the magnet is referred to as being On. That is, when the north magnetic area of the surface of core is directly under or is coincident with the north magnetic area of the inner surface of the sleeve 11, the south areas of the core 10 and of the sleeve 11 will be similarly disposed with respectto each other, to provide the maximum north and south magnetic fields, as illustrated in FIG. 2. By gradual relative rotation of the core 10 with respect to the sleeve 11, from the On position, the magnetic fields are diminished until, at 180 degree rotation from FIG. 2, the magnet is Off, as illustrated in FIG. 3, because the components are in a theoretic position of neutralization. The On and Off positions of the magnet are labeled on the drawings.

While the device described to this point is suitable for holding or latching purposes, the fact is that, even in the Off position, there is a slight magnetic leakage which would render the device or apparatus unsuitable for use with certain electrically actuated components understood by those skilled in the art. To completely stop all the magnetic leakage and achieve the effect theoretically available in FIG. 3, I provide a magnetic leakage stopper 16. The stopper 16 in the embodiment illustrated is discor plate-like in shape and is fabricated from a magnetizable material, such as soft iron or other ferrous material, having a low magnetic reluctance.

The diameter of the disc or plate 16 is sufliciently large to bridge the gap formed between the core 10 and the sleeve 11, as illustrated in FIGS. 2 and 3, to thereby short out the magnetic leakage which occurs when the components of the instant device are in the positions illustrated in FIGS. 3 and 5. However, it will be appreciated that the stopper 16 must be free from contact with both of the

pole plates

12 and 13; and to that end, in the instant embodiment, the diameter of the stopper 16 is smaller than the external diameter of the cylinder or sleeve 11. In practice, the leakage stopper 16 is secured to the top of the sleeve 11 by means, such as a synthetic resin, well known to those skilled in the art.

For greatest effect, in the variable magnet herein described, I have found that it is preferable if the mass of the core 10 is greater than the mass of the sleeve or cylinder 11. Preferably, the mass of the core 10 should even be greater than the combined mass of the sleeve 11 and the

pole plates

12 and 13.

It will be appreciated that between the On and Off positions shown, respectively, in FIGS. 2 and 3, a magnetic field of any selected intensity is available by suitable relative positioning of the core 10 and the sleeve 11.

As many changes or substitutions could be made in the above described construction, and as many apparently Widely different embodiments of the invention within the scope of the claims could be constructed without departing from the scope and spirit thereof, it is intended that all matter contained in the accompanying specification shall be interpreted as being illustrative and not in a limiting sense.

I claim:

1. A variable magnetic device comprising a permanently magnetized sleeve having its poles located on opposite sides of the longitudinal axis thereof, a permanently magnetized core within said sleeve having its poles located on opposite sides of its longitudinal axis, a pole piece overlying and affixed to the south pole of the sleeve and another pole piece overlying and affixed to the north pole of the sleeve, each of said pole pieces extending beyond one end of the sleeve, said core and sleeve being relatively rotatable and said pole pieces being rotatable with the sleeve whereby the intensity of the magnetic field of the device may be selectively varied over a Wide range by modifying the relative disposition of the poles of the core and the poles of the sleeve.

2. The magnetic device of claim 1 including a disc of magnetizable material overlying the ends of the core and sleeve to arrest magnetic leakage therebetween with said disc being secured to the end of the sleeve and spaced from the end of the core.

3. A variable magnetic device comprising a permanently magnetized sleeve having its poles located on opposite sides of the longitudinal axis thereof, a permanently magnetized core within said sleeve having its poles located on opposite sides of its longitudinal axis, a pole piece overlying and aflixed to the south pole of the sleeve and another pole piece overlying and affixed to the north pole of the sleeve, said core and sleeve being relatively rotatable and said pole pieces being rotatable with the sleeve whereby the intensity of the magnetic field of the device may be selectively varied over a wide range by modifying the relative disposition of the poles of the core and the poles of the sleeve.

References Cited by the Examiner UNITED STATES PATENTS 2,268,011 12/1941 Beechlyn 317-459 2,287,286 6/1942 Bing et a1 317l59 2,471,067 5/1949 Hitchcock 317l59 2,722,617 11/1955 Cluwen et a1. 317201 X 2,793,552 5/1957 Clark 317-159 X 2,972,485 2/1961 Ferchland 317-459 FOREIGN PATENTS 23,156 4/1949 Finland. 881,702 7/1953 Germany.

JOHN F. BURNS, Primary Examiner.

JOHN P. WILDMAN, LARAMIE E. ASKIN,

Examiners.

Claims

3. A VARIABLE MAGNETIC DEVICE COMPRISING A PERMANENTLY MAGNETIZED SLEEVE HAVING ITS POLES LOCATED ON OPPOSITE SIDES OF THE LONGITUDINAL AXIS THEREOF, A PERMANENTLY MAGNETIZED CORE WITHIN SAID SLEEVE HAVING ITS POLES LOCATED ON OPPOSITE SIDES OF ITS LONGITUDINAL AXIS, A POLE PIECE OVERLYING AND AFFIXED TO THE SOUTH POLE OF THE SLEEVE AND ANOTHER POLE PIECE OVERLYING AND AFFIXED TO THE NORTH POLE OF THE SLEEVE, SAID CORE AND SLEEVE BEING RELATIVELY ROTATABLE AND SAID POLE PIECES BEING ROTATABLE WITH THE SLEEVE WHEREBY THE INTENSITY OF THE MAGNETIC FIELD OF THE DEVICE MAY BE SELECTIVELY VARIED OVER A WIDE RANGE BY MODIFYING THE RELATIVE DISPOSITION OF THE POLES OF THE CORE AND THE POLES OF THE SLEEVE.