US2992735A - Magnetic attractor - Google Patents

Description

July 18, 196.1 G. P. TROY MAGNETIC ATTRACTOR 2 Sheets-Sheet 1 Filed Nov. 20, 1957 LFEEZQT United This invention relates generally to magnetic attractors, and more specifically to an improved magnetic attractor having a permanent magnetic means incorporated therein.

Although the principles of the present invention may be included in various devices, a particularly useful application is made in magnetic separators, both of the grate type and of the rotating pulley type. Although the invention has been disclosed as being incorporated in a grate type separator, it is to be understood that the in vention may be used to advantage in other types of devices employing magnetic attraction means, such as, but not limited to, floor cleaners, road cleaners, sheet steel movers, and the like.

A particularly useful application is made in separators of the grate type which are installed in ducts for removing magnetic material from a wet or dry mixture passing therethrough. Such an arrangement may typically consist of a hopper below which is disposed a duct of any cross-sectional configuration, and across which duct are disposed one or more rows of magnets in such an arrangement that any material passing through the hopper also passes through the spaces between the magnetic bars of the grates. Thus since the grate is magnetic, the spaces between the elements thereof have a magnetic field, and any magnetic particles are attracted to the grate and retained there.

Magnetic bars used in separating or cleaning devices typically include an electromagnetic coil for inducing the field which radiates from the separator bar. Permanent magnets having their poles directed toward the periphery of the attractor bar have also been utilized These types of construction have an inherent common disadvantage in that discontinuities are created by the mere presence or inherent localization of magnetic poles.

The present invention contemplates the utilization of radially magnetized permanent magnets as a part of the magnetic attractor bar whereby a continuous magnetic field of one magnetic polarity is obtained at any point axially along the separator bar. In the various embodiments of this invention, other features are also included which are described more fully herein.

Accordingly, it is an object of the present invention to provide a magnetic bar having a peripherally uniform magnetic field emanating therefrom.

Another object of the present invention is to provide an improved magnetic separator for collecting magnetic particles from a material flowing therethrough.

Yet another object of the present invention is to provide a means for cleaning or removing attracted particles from a permanently magnetic attractor bar.

A still further object of the present invention is to provide an improved magnetic attractor element.

Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which several embodiments incorporating the principles of the present invention are shown by way of illustrative example.

On the drawings:

FIG. 1 is a fragmentary cross-sectional view of a magnetic grate separator, partly in elevation, and provided with a magnetic element in accordance with the principles of the present invention;

atcnt ice FIG. 2 is an enlarged fragmentary cross-sectional view taken along line 11-11 of FIG. 1;

FIG. 3 is an enlarged fragmentary cross-sectional view taken along line IIII1I of FIG. 2;

FIG. 4 is generally similar to FIG. 3, but includes a slight structural modification;

FIG. 5 is also generally similar to FIG. 3, but shows a still further structural modification thereto;

FIG. 6 is also similar to FIG. 3, but shows yet another structural modification;

FIG. 7 is a fragmentary cross-sectional view generally similar to FIG. 2, but of another embodiment of the instant invention;

FIG. 8 is also a fragmentary cross-sectional view illustinting a feature which may be incorporated in the structure of FIG. 7;

FIG. 9 is a still further fragmentary cross-sectional view generally similar to FIG. 2, but incorporating means for removing collected magnetic particles;

FIG. 10 discloses diagrammatically a manner in which several of the embodiments disclosed herein may be utilized.

As shown in the drawings:

The principles of this invention are particularly useful when embodied in a magnetic grate separator assembly such as is illustrated in FIG. 1, generally indicated by the numeral 10. The separator assembly 10 includes generally a housing 11, which supports a magnetic grate 12, which communicates with a hopper 13 for holding and directing the substance to be magnetically cleaned by the separator. The discharge portion of the housing 11 may communicate with a duct 14.

t is to be understood that the environment, with which the instant magnetic attractor bars which comprise the grate 12 have been illustrated, is exemplary and that the individual magnetic attractor bars may be constructed permanently installed, or for portable use in a great number of ways.

Referring now to FIG. 2, a fragmental portion of the grate assembly 12 is shown in detail. The grate 12 may include one or more spaced magnetic attractor bars 15, each having a permanent magnet field extending radially from the principal axis of the bars 15 and across the spaces 16 adjacent to the bars 15. Thus it will be seen that the magnetic particles in a material or substance flowing through the separator 10 come under the influence of such field and are attracted toward one of the bars 15.

Referring now to both FIGURES 2 and 3, each of the magnetic attractor bars 15 includes a plurality of permanent magnets 17 and 18, here illustrated as being ceramic magnets of generally annular configuration. As shown by FIGURE 3, each magnet has a circular central aperture and a circular perimeter, thus defining a generally annular construction. Referring to FIG. 5, it will be noted that the outer configuration of the magnet as well as the inner configuration may be of any desired shape, and therefore the term annular as used herein, is not to be limited to precisely circular configurations. The body of the permanent magnets 17 and 18 may comprise any suitable permanently magnetic material. However, the instant structure is particularly well adapted for the use of high coercive materials such as barium ferrite ceramic magnet material.

Each of the magnets 17 and 18 are magnetized radially having one magnetic polarity adjacent to the perimeter 19 and an opposite magnetic polarity adjacent to the inner periphery 20. Thus as shown in FIG. 3, :north magnetic polarity is present continuously around the entire perimeter 19, while south magnetic polarity is present continuously along the opening through the magnet. Of course in the magnet 17, the polarity is reversed.

When the magnets 17 and 18 comprise ceramic mate rial, it is frequently necessary from a manufacturing standpoint to build up what is operatively a single magnet from a plurality of magnetic components. Thus as shown in FIG. 2., each of the bars 15 includes three magnets or magnetic portions, each portion comprising a plurality of individual annular magnets 17 or 18. The build-up thus illustrated is axial in character. As shown in FIG. 4, the build-up may also be angular in character, wherein individual sectors 21 are jointly disposed to define operatively a single annular permanent magnet. Thus it can be seen that the magnet 22 is substantially identical to the magnet 18. Thus the various groups of elemental magnets may be considered operatively as being individual magnets, generally indicated at 23-28 respectively.

Intermediate the various magnets 23-25 and 2628, there are disposed a plurality of non-magnetic spacers 29 which preferably have an axial length greater than the diameter of the magnets 2328. Extending through each of the bars 15 is a supporting mandrel 30 which preferably comprises highly permeable magnetic material. The bars 30 serve as a support for the individual elemental magnets l7, l8, and for the spacers 29. Thus the mandrel 30 may be secured in any convenient manner to the housing 11, for example by extending therethrough as at 31 and receiving a large headed screw 32 through the housing 11. The specific mode of attachment illustrated at 31 and 32 is exemplary and the invention is not to be limited to this specific manner of attachment. It will be noted that the mandrel 3d bridges the magnetic poles which extend to the opening defined by the inner periphery 20, and thus comprises part of a magnetic circuit between the various magnets 2325 and 26-23. Of course, the mandrel 3% may be made of non-magnetic materials if their use as a part of the magnetic circuit is not required in a particular embodiment.

Surrounding the various magnets and the spacers 29, there is disposed a tubular means or member 33. As in the case of the mandrel, the tubular member 33 is preferably magnetic, particularly if it is desired to be used as part of the magnetic circuit. The thickness of the member 33 has been somewhat exaggerated for purposes of clarity especially when magnetic material is utilized. Otherwise, the tube may be of non-magnetic material. The tube 33 may be adapted at its end or elsewhere for providing the support for the magnetic bars 15 in place of the means 31 and 32 associated with the mandrel 30. While the tube 33 may be of generally circular configuration, it may also be of any other sectional configuration where such configuration is of advantage. Thus FIGURE discloses a structure wherein the tube 34 is of square or angular configuration, while FIGURE 6 discloses a tube 36 of generally tear-shaped configuration. The upper portion of each of these structures is triangular with an apex of the triangle pointing upwardly. When shaped tubes are utilized, the magnets therein may also be shaped, such as the magnet 37 in FIG. 5, or a magnet such as 17 or 18 may be used as shown in FIG. 6.

Since the magnetic polarity extends around the entire periphery of the various magnets, it is not necessary to rotationally or angularly orient adjacent magnets. However, when a shaped tube, such as 34 or 36 is used, it may be desirable to use a shaped or non-circular mandrel 38 as shown in FIG. 5, cooperating with a similarly shaped opening in the magnet, for precluding a rotation between the various portions of the attractor bar assembly 15.

When the elemental magnets 22 comprise a plurality of sectors 21, the tubular member 33 may be used to hold them in position with respect to each other, as shown in FIG. 4. If the tubular member be omitted, as shown in FIG. 7, and further if it be desired to utilize spacers, the magnetic sectors 21 of FIG. 4 may be held together in the manner indicated in FIG. 8, wherein a spacer 40 is used to hold together various sectors 4144 as by a tubular projection 45 on the ends of the spacer 40 each of which coacts with suitably shaped end portions of the sectors.

Where no spacer or tube is used, a tubular clamp such as 46 may be used for this purpose.

Referring now to FIG. 7, a structure is shown wherein the tube 33 is omitted, and wherein a pair of annular permanent magnets 40 and 41 are mounted directly on the mandrel 30. It will be noted that the magnets 40 and 41 are magnetized radially so that there is only one magnetic polarity along the periphery or perimeter thereof. It will also be noted that the specific polarity is reversed in the magnet 41 as compared to the magnet 40.

The embodiments or variations shown in FIGS. 1-8 thus each include a mandrel such as 30 supporting a radially magnetized permanent magnet. When adjacent magnetic bars have opposite polarities directly laterally adjacent to each other, the space therebetween is subjected to a relatively intense field for attracting the particles. Furthermore, when the magnet is annular so that there is a continuous pole face, or so that magnetic flux emanates continuously around the periphery of the magnet, particles may be attracted to any portion thereof.

When particles are attracted to the surface at a point which faces the direction from which the relative flow is coming, the particles adhere directly to said surface at such point. This point may be intermediate the spaced magnetic bars. However, when relative flow therebetween continues, there is a tendency for the flowing substance to brush or rub the collected particles away from the point to which they were initially attracted. In other structures, this tendency removes some of the collected particles from the point of magnetic influence, whereby they are undesirably released. However, in the instant structure, any flow which tends to move the magnetic particles to the leeward or lower side produces no such effect, because such particles remain continuously under the influence of the magnet, by which they are retained.

To intensify the magnetic force, the mandrel 3% may be made of magnetic material so that the reluctance between the poles which are directed to the opening or aperture in the magnets is reduced. Where ceramic magnet material is used, no. spacers are necessary. However, if magnet materials which permit axial shift of flux are used, then a spacer such as shown in FIG. 8 is advantageous, in order to insure that there is a portion adjacent to the magnetic bar in which the magnetic flux may extend from the magnet, for example, from the magnetic sector 41 to the sector 43.

Since it is frequently impractical to produce ceramic magnets as any substantial size, it has been described how a multiplicity of elements may be used. In order that the flux from. one of these magnet elements may be allowed to shift to be effective from a region adjacent to another magnet element, the tubular member 33 is disposed adjacent to the peripheral poles to produce such a shift. The tubular member 33 also serves to mechanically and chemically shield the interior components of the magnetic bar 15.

Referring to FIG. 2, it is desirable that the magnetic flux lines extend from the magnet 23, into the space 16, adjacent to the spacer 29, and into the magnet 24. In order that this may be assured, the tubular member 33 may be made of non-magnetic material. However, in the event that both the shift feature above referred to and the feature of flux lines extending into the space 16 are desired, it is then preferable that the tubular member 33 be made of highly permeable magnetic material having a relatively small cross-section, whereby the portion of the tubular member 33 which is adjacent to the spacer 29 is magnetically saturated by the relatively strong magnets 23-25 and 26-28. Thus preferably, a relatively small fraction of the magnetic flux passes through the tubular member 33 adjacent to the spacers 29. Thus the tubular member 33 serves as a desirable part of the magnetic circuit adjacent to the magnets, and serves as a leakage path adjacent to the spacer. Obviously, a compound tubular member may be provided wherein the portion adjacent to the magnets is magnetically permeable and the portion adjacent to the spacer is not.

Referring now to FIG. 9, there is shown a structure identical to that of FIG. 2 except that the spacer 29 comprises more than mere non-magnetic material. In FIG. 9, the mandrel 50 comprises magnetic material about which is received one or more electromagnetic coils 51.

The coils 51 are provided with leads which extend outwardly from the magnetic bar, and which may be routed in any convenient manner. At each end of the magnetic coil 51, there is disposed an annular magnet 52 and 53, each of the magnets 52 and 5-3 having radial magnetization with only one magnetic polarity at its outer periphery, the polarity of the magnets at the opposite ends of the coil 51 being opposite to each other at their respective outer surfaces. The coils are not normally energized, andthe magnetic bar operates in a manner already described herein.

The south pole of the magnet 33 acts to induce a north pole immediately adjacent thereto and within the mandrel 50. Likewise the north pole of the magnet 53 acts to induce a south pole in the mandrel 50 directly adjacent thereto. Accordingly, it is seen that the mandrel 50 has a north pole induced at the left end and a south pole induced at the center as shown in FIG. 9. The coil 51 is so wound and an electric potential is intermittently applied thereto that the polarity induced thereby in the mandrel 50 is opposite to that just described. Accordingly, the coil 51 serves as a switch or a gate for the flux normally in the mandrel 50 which so weakens the efliciency of the magnetic circuit that any magnetic particles collected against the tubular member 33 are thereby released or dropped.

In this structure, it is particularly advantageous to utilize ceramic magnets, because while the energization of the coil 51 eifectively cancels or knocks down the field of flux emanating from the ceramic magnets 52 and 53, such magnets are not thereby demagnetized. Accordingly, when the current in the coils 51 is interrupted, the original flux distribution is resumed without diminution for further collecting of magnetic particles. As in the earlier example, it can be seen that the tubular portion 3-3 which lies adjacent to the coils S1 is an optional feature. However, if included, the strength of the magnets 52 and 53 must be such as to more than saturate the portion of the tubular member adjacent to the coils 51 whereby additional flux find a path through the air and attract particles to the magnetic bar.

It will thus be seen that an improved magnetic attractor bar has been provided wherein the bar may be used in a stationary fashion such as shown in FIG. 1, or supported in another device by bearings 55 for rotation. If the structure of 9 be supported as shown in FIG. 10, the use of conventional slip rings enables a continuous connection to the coils 51; however, if the rotation of the device can be interrupted for cleaning, such slip rings are unnecessary and a non rotating electrical connection may be temporarily made to the coils 51 of the magnetic bar.

Although various minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon, all such embodiments as reasonably and properly come the scope of my contribution to the art.

I claim as my invention:

*1. A magnetic particle attractor bar comprising in combination: a pair of groups of axially spaced annular ceramic permanent magnets having radially extending poles having radially extending fields, the periphery of one of said groups of magnets having a polarity opposite to that of the other of said groups of magnets; a nonmagnetic spacer member disposed intermediate said groups of magnets; and magnetic means extending through said magnets for securing them together and intensifyingly forming part of a magnetic flux circuit between said groups; said non-magnetic spacer including a coil disposed about said magnetic securing means for selectively inducing opposite flux therein, whereby any particles attracted by said permanent magnets are released.

2. A magnetic particle attractor bar comprising in combination: an annular electromagnet having a magnetically permeable core extending axially therethrough; and a number, including one, of annular ceramic permanent magnets axially received on said core at each end of said electromagnet, said permanent magnets at each of said ends having radial magnetization with a radially extending field of only one peripheral polarit said peripheral polarities being opposite to each other and to said electrm magnet at opposite ends of said electromagnet; said permanent magnets having a field strength suflicient to pass a leakage flux therebetween exteriorly of said electromagnet between points of opposite peripheral polarity.

3. A magnetic separator for separating magnetic particles from a substance, comprising in combination: a housing; at least one tubular member disposed in said housing for contacting the substance, said tubular member having a shaped section a portion of which is niangular against which portion the substance impinges for easing the relative movement between the substance and the member; and a magnetic bar having a field of a single peripheral polarity received in said member, said magnetic field being directed radially of the bar through said triangular-shaped section to the substance.

4. A magnetic particle attractor bar assembly comprising in combination: an annular electromagnet having a magnetically permeable core extending axially therethrough; and a number, including one, of annular ceramic permanent magnets axially received on said core remotely from said electromagnet; said permanent magnets having a generally exposed outer perimeter and each having radial magnetization with a radially outwardly extending field of only one peripheral polarity for attracting particles thereto and having only an opposite magnetic polarity extending in a radially inward direction toward said core, said magnets inducing a magnetic flux in said core in one axial direction, said electromagnet when energized inducing a magnetic flux in said core in the opposite direction, and being of such strength as to neutralize said radially outwardly extending field of said permanent magnets so that any particles that are attracted thereby to said permanent magnets are released.

References Cited in the file of this patent UNITED STATES PATENTS 1,291,534 Johnston Jan. 14, 1919 2,648,434 Russell Aug. 11, 1953 2,678,729 Spodig May 18, 1954 2,707,557 Spodig May 3, 1955 2,733,812 Hofi Feb. 7, 1956 2,822,089 Woodrufi Feb. 4, 1958 FOREIGN PATENTS 509,747 Italy Ian. 17, 1955

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