US1132016A - Means for forming zones of varying and variable strengths in magnetic fields. - Google Patents

Description

A. F. JOBKEL.

MEANS FOR FORMING ZONES 0F VARYING AND VARIABLE STRENGTHS IN MAGNETIC FIELDS.

APPLICATION FILED JAN. 24, 1912.

Patented Mar. 16, 1915.

' INVENTOR HucFsT -O WITNESSES ATTORNEYS net fields of gaps.

UNITED STATES PATENT OFFICE. I

AUGUST 1'. JOB, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOB OF ONE-HALF TO Ion G. BURNS, DANIEL BINGHAM, KATHERINE CRUMAY, THOMAS HIGGINS, AND H. P. aazzm, ALL OF PITTSBURGH, PENNSYLVANIA.

mus FOBIOBIING ZONES OE VABYING All?) VARIABLE STRENGTHS IN MAGNETIC FIELD Specification of Letters Patent.

Patented Mar. 16, 1915.

'lpplicatlon fled January 24, 1912. Serial No. 673,131.

To all whom it may concern:

Be it known that I, AUGUST F. JOBKE, a' citizen of the United States of America, residing at Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful improvements Means for Forming Zones of Varying an Variable Strengths in Magnetic Fields, (Case 1,) 'of which the following is a specification, reference being had therein to the accompanying drawing.

My invention rclates'to improvements in means for forming zones of varying and variable strengths in magnetic fields, relating more'particularly to the formation of the magnet poles which produce the mag- So far as I am aware, the only attempts which have been made to vary the field strength of a magnetic gap have embodied the idea of changing the distances between the pole pieces which form the ap, this difference or variation being provifed either b adjusting one or most of the pole pieces in directions toward and from each other,

7 by employing pole pieces adapted to divide the ma etic field into several fields each of the divided poles occupying a position to increase or diminish the distance between the two poles from each of the other divided poles, or to employ this latter idea with each of the divided poles adjustable to permit of variations in such distance.

Any arrangement which involves a change in the distance between opposing oles of a gap is disadvantageous for the ollowing reasons: Assuming, for example, the rovision of two opposing pole pieces, one involving a structure havinga plane flat, surface or face, with the other in the form of a'plurality of wedges, the ed s of the wedge form being spaoedat di erent distances from the flat face of the other pole, an example of which is shown in Figure 6 of the drawing, and to which reference may be had in connection with this discussion,

the showing therein made providing for three zones of varying strength. It should be noted that this particular form represents approximately the greatest value heretofore known in this special type of apparatus. As will be seen by reference to -posing poles, the advantage gained by said figure, the zone of greatest strength is that provided by the edge in closest proximlty to the opposite pole piece, while that on the right, being the greatest distance from the opposite pole piece provides the zone of least strength, the intermediate zone having a strength between the outer zones. As will be seen, each zone has its lines of force converging from the'flat pole face to the opposing edge, with the face occupied by each zone on the fiat face approximately the same width. As will be seen by the lines connecting the opposite poles, the field of greatest strength, has in accordance with the well known physical law that the greater I its, the greater will be the magnetic attraption, it being understood that where an angle of convergence is unduly increased, as by decreasing the distance between the opincrease in the angle of convergence will be overcome by an increase in stray flux, so that a loss in flux is provided with a resultant waste. On the contrary, however.

where the angle of convergence is decreased,

as by increasing the distance between the poles, the field is not only weakened in strength, but in addition, the lines of force will provide a difl'erent form ofrfield, the lines bulging owing to the re ellent action of similar polarity, the lines 0 force closely approaching exact parallelism and of almost uniform density, with a consequent result that there is no pull or attraction in either direction on a plane intersecting at right angles and centrally the space between two opposing poles, each of which is wedgeshaped with the edges in opposition to each other, such plane corresponding to the flat face of the lower pole in said figure, this attraction increasing from zero on that face to its maximum at the pole edge; where a structure of this type is used in magnetic ore separation, it will be readily un erstood that where the distance betweel. the poles is increased in this manner t e may result a condition where a strong 11 x will be provided but without any or but very little pull or attraction of ore particles near the flat face, thereby providing for but a very small efiiciency in the field. To decrease the strength of such field by increasing the distance would not only affect the particular gap in question, but also the other gaps or zones, in addition to requiring the employment of greater power. And where the zones are variable, as by adjustment of the pole pieces, toward each other as where for instance, the parts are carried by a rotating carrier, adjustment of any or all of the edges couldonly be had when the apparatus is at rest, so that where the structure is employed for magnetic,ore separation, adjustments can be had only under such rest condition; where, therefore, proper adjustment can only be obtained by testing the ore material passing through the zones it will be obvious that there is a large amount of time wasted due to the required stoppages of apparatus where the adjustment is not 'had at once.

My present invention aims to not only overcome the objectionable features indicated above, but in addition to increase the efliciency of apparatus employing magnetic fields by making them more flexible and capable of uses heretofore not possible. For

tance. 1 am able to produce the results tion is employed in connection with magnetic ore separators: (1) The division of the field of a magnet pole into zones of difierent strengths for the separation of materials "of different permeability from each other. (2) The adjustment ofdifferent zones in the same field without altering the distance between opposed poles. (3) The adjustment of different zones in the same field by varying the reluctance of the individual paths. (4 A predetermination of the ratio of the different zones to one another. These may be considered as a few of the objects of the present invention.

Therefore, to these and other ends, the nature of which will be readily understood as the invention is hereinafter disclosed, my invention consists ,in the improved construction and combination of parts hereinafter fully described, illustrated in the accompanying drawings and particularly pointed out "in the appended claims.

In' the accompanying drawings, in which similar reference characters indicate similar parts in each of the viewsFig. 1 is a fragmentary view, partly in section, showing a magnetic field divided irhtozones, with .the upper pole in the form of a secondary magnet, the field being shown as provided with'three zones of different strengths. Fig. 2 is a similar view showing a modification of the idea, ,four zones being provided, both pole pieces being arranged in accordance withiny invention. Fig. 3 is a similar view, also. showing four zones and illustrating a indicated by the following, where the inven- .and'14' are secured to secondary magnet, the lower pole piece being shown as extending axially of a vertical magnet. Fig. 4 is a similar view, showing a different arrangement of the means for varying the strength of the gaps. Fig. 5 is a similar view, showing both pole pieces formed in accordance with my invention, this particular type providing for the greatest variance in gap strengths. Fig. 6 is a similar view illustrating a known form of 6 structure for producing the result. Fig. 7 is a view of a still further modification of my idea, the view also having illustrations for the purpose of showing comparisons with Fig. 6.

In a magnetic circuit having a constant magneto-motive force, the flux density depends on the total reluctance of the circuit traversed, every air gap representing a large reluctance relative to aniron-cireuit roportional to the length of the gap; 0 vionsly, therefore, variations in the length of the air gaps affect the flux density therein. As heretofore pointed out, however, variations in density provided by changing the length of the air gap between the poles, is disadvantageous, some of the reasons for which being heretofore set forth. To avoid these objections, I provide for retainingthe air gaps in a constant length by introducing an additional reluctance in the circuit at any point independent of such gap for the purpose of reducing the flux to the desired strength, on the principle that a. magnetic circuit can be shunted by an additional ath we of different reluctance, producing a stronger main path and weaker shunt-path and rendering it possible to provide more than one separatmg-gap. It is 01 1 this principle that base my invntion, and for convenience, I place allshunt-paths in the pole shoe of one or both "poles; in this manner, the shuntpaths are as short as possible and avoid a leakage of flux. This idea can be provided in many forms, a few of which are indicated in the drawings. For the purpose of explaining the invention, I will use, for example, the showing of Fig. 1, in which 10 represents a horizontal magnet with a vertically rising pole shoe 11 opposing an edge of a secondary magnet 12 located thereabove, Additional magnetic features or members 13 the shoe 11, as by bolting, these magnetic members being spaced from thefs hoe 11 and from each other, being in opposition to opposing edgesof the magnet -12, this form disclosing a structure providing three difl'erent zones, a-versin which, for the purpose of ill tration, haveshown a conveyer 16 such aslwouldbe provided in connection with magnetic ore separators. For convenience in interpreting the invention, I .have shown the several 2 '. poles 11, 13, and 14 as separated by insulation 15. This, however, is simply for the 13 the insulation of the electrical art beingunknown, so far as I am aware, in magnetic circuits. The insulation is intended to represent a suitable reluctance, whose permeability is unity, and this reluctance can be provided in any desired manner.

It should be noted, that in a preferred form of my invention, the bolts by means of which the magnetic members 13 and It are secured to the pole shoe 11 arelof -nonmagnetic material in order that aiiiron-circuit between these separated members is prevented, excepting under conditions presently described. i

As will .be readily understood, in this construction there are provided three paths for the flux to travel, the first being that between the shoe 11 and the opposing edge, this zone being of the greatest strength by reason of the fact that there is provided the smallest reluctance of thecircuit, vi.'z., the length of the gap between opposing poles; the second path is that provided between the member l3 and its opposing pole face of the secondary magnet 12; in this zone, the same amount of reluctance is provided in the separating gap (the space between the opposing poles) and additionally the reluctance provided by the spacing between the pole shoeell and the member L3, this increase in reluctance acting to decrease the strength of the zone. in question, without, however, art: footing the angle of convergence. of the lines of forcein the field or gap. The third zone provided bietweefn Ithe meraiaber 14 and hits 0. posie gee t esecon ry magnet as itg streii gth decreased from both of theother zones by reason of the fact that the flux path traverses both reluctance gaps 15 as well as the field gap. From the above, it will be seen that in each zone, the distance between the op ing pole faces is the some, providing simi ar angles of convergence in connection with each zone, as shown, for in stance, in 7, the zones, however, being oi diflerent strength with that of the pole shoe 11 which is integral with the magnet core, as the maximum, the zones decreasingin strength-proportionately to the amount of additional reluctance provided within the circuits. Obviously, the strength of the several zones can be readily determined by knowing the section. of the reluctance gaps between the separated members. However, the strength 0 any auxiliary zonecan be readily increased without afiecting the distance between the opposing poles of the fields by providing an iron-path between the members. This path may be formed in any suitable manner, any magnetic material bein; mpioyed and. b controlling the cram"- section. of the increase instrength can be readily controlled. For the p ose, the magnetic material may be in the orm of blocks, sheets, or even wires, the purpose being to provide a path of less reluctance than the reluctance gaps, through which path the flux flows more readily and thus increases .the st h of the circuit passing through the members. In Fig. 1 I have shown a member of thistype at 18. As will beobvious the strength ad ust'rng operation providiad by the member 18 can take place without afllecting the operation of the rator; and it will also be obvious that it will only be necessary to change the cross-sectional area of such member to vary the stnength, so that variations can be made for testing purposes while the ppa-ratns is in operation and proper strengt to produce the best results quickly obtained.

As will be obvious, this idea may be em- ?oyed in various forms of construction.

or instance, in Fig. 2 the secondary magnet is replaced by a similar construction to that shown at the bottom, the auxiliary members being of different cross-sectional size and obviously providing for a difi'erent cross-section of the reluctance gap. 1 This particular construction provides a greater variance in zone st engt than in the form shew-n. in Fig. L n this form, each zone beyond the inner one represented by the shoe 11 is subjected to, the reluctance of two spaces instead of but one as in the structure of F ig. 1, and in addition, the successive members and the spaces therebetween formmg the reluctance gaps are reduced by shortening thereby increasing the reluctance for the individual shunt circuit; in this figure I also show the application of the members 18 for the the zone strength.

In Fig. 3 I show a somewhat similar arrangement' in connection with a magnet havmg a vertical axis, the opposing pole being provided by a secondary magnet, as in Fig. 1. In this form, as in Fig. 2, the members are of .succesmwely decreased length to increase the reluctance. In this form, a slightly dillerentapplication of the bridg 111%. 18 1s shown, illustrating an- 0t er way in which the adjustment in the zone strength may be accurately made.

In Fig. 4, a diiferent arrangement of the sameddea. is provided, this arri ment givmg a smaller ratio at strength tween the strongest zone and the next than the second and third one, on account of the diflerent ratio of .reluctances between them. This arrangement may also be advantageously employed reason of the ability to-provide for finer adiustments infield strength, the dotted lines in the re-showin a difierent way in which the bridging mem rs may be purpose of adjusting),

employed, each of the auxiliary members being shown as magnetically connected to the pole member 11.

In Fig. 5 I show an arrangement which permits of an extreme difference in strength of the several zones, the reluctance between the same being increased to approximately their largest values. In this form, the sha es of the auxiliary members or poles is made so that their faces retain their most advantageous form, while the material in rear of the faces is cut awa to increase the reluctance of the spaces, t us -a high efficiency is insured for every one of the gaps at their greatest difierence in strength. This form is probably of the greatest advantage, by reason 0 the fact that it affords the maximum range, and by the use of bridge memberscan be readily adjusted to increase the strength of the zones, it be ing understood, of course, that this arrangement does not provide for a decrease in the zone strength excepting by affecting the strength of the entire magnet as by reducing the number of ampere-turns.

Fig. 7 shows still another form in which this operation can be provided, this view being presented more particularly as showing one way, in which to comfiare the efi'ect to the effect produced by a di erent type of apparatus.

From the above, it will be readily understood that in'each type, the length of the gapsis the same for each of the zones of any particular field; consequently, as shown in Fig. 7, the angles of convergence are similar in each zone, the only difference bemg in the zonal strength. Where a structure of this type is employed in magnetic ore separation, each zone becomes a separating (gap and the ore conveyer intersects at substantiall the same distances from the poles in eac zone. Obviously, since the angles of convergence are the same in all of the zones the action of the circuits will be the same in each zone excepting for the strength of the zone, and as this strength is controllable as indicated, it will be obvious that a cI ean-cut separation will be provided. 1

While my invention is primarily intended. for use in connection with magnetic ore separation, and I have. disclosesd it mainly in connection with such use, I believe the invention-to be of broaderscope and suitable for other purposes, however, and I therefore desire it to be understood that no specific application which may h ve been herein made shall be held toexclu e other applications of the same general idea embodied herein, the structural and operative characteristics of which are the equlvalents "of those herein set forth, even though such apparatus may be utilized "in different relations o fiect a specifically different result.

reluctance of the magnetic circuit.

3. Means for formin zones of varying strengths in magnetic fields with substantially constant length of the zonal gap and including a field pole element having a mem: ber cooperating to provide a maximum zone stren h and a magnetic member spaced there rom to increase the reluctance of the circuit through the second member.

4. Means for formin zones of varying strengths in magnetic elds with substantially constant length of the zonal gap and includin a field pole element having a plurality 0 members, the faces of which are positioned to cofiperate in roviding'separate gaps of equal length, t e members being spaced apart to provide increasing re luctance to the magnetic circuit passing through the members.

5. Means for forming zones of varying strengths in magnetic elds with substantially constant length of the zonalgap and includin a field pole element having a plurality 0 members, the faces of which are positioned to cooperate in providing separategaps of equal length, the members being spaced apart to provide increasings reluctance to the magnetic circuit pa ing through the members, said members being normally" out of magnetic contact.

6. Means for forming1 zones of varying strengths in magnetic elds with "substantially constant length of the zonal gap and includin a field pole element having a p urality 0 members, the faces of which a positioned to cooperate 1n providing separategaps of equal, length, the members being spaced apart provide increasing re-' luctance to the magnetic circuit passing through the members, said members being normally out of magnetic contact, and independent bridge members adapted to connect two or more members magnetically to adjust the zone stren h.

8. In a magnetic eld, means for establishing a magnetic circuit with a zonal g of substantially constant length, and mea s for varying the strength of the gap independent of its length by varying the circuit reluctance.

9. In a magnetic field, means including opposing pole elements 'for establishing a magnetic circuit with a plurality of zonal gaps, and means for varying the strength of the zones relatively to each other by altering the reluctance between zones in a pole element.

10. In a magnetic field means including 20 opposing pole elements or establishing a magnetic circuit with a plurality of zonal gaps, and means for varyin the strength of the zones relatively to eac other by altering the reluctance between zones in each 26 of the pole elements.

In testimony whereof I aflix my signature in the presence of two witnesses. 7

AUGUST F. J OBKE.

Witnesses:

MAX H. SBOLOVITZ, HORACE G. SEI'rz.

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