US3661302A

US3661302A - Solids dispenser having magnetic valve in throat

Info

Publication number: US3661302A
Application number: US18892A
Authority: US
Inventors: David L Braun
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1970-03-12
Filing date: 1970-03-12
Publication date: 1972-05-09
Anticipated expiration: 1989-05-09

Abstract

A magnetic valve for controlling the flow of solids is provided. It consists essentially of an orifice feeding tube with a magnetizing coil surrounding it, so that lines of force of the coil are generated axially of the throat and a spindle fitting into the throat of the tube and having its geometrical axis parallel with the direction of flow through the tube and a magnetic axis at right angles thereto. In addition an antibridging and anti-loading device is provided above the spindle to prevent bridging of the orifice at that point by packing of the dry powder and packing of powder against the spindle.

Description

nited Stats 15] 3,66L3fi2 ram 145] May 9, W72

[54] SOLIDS DHSIPENSER HAVING 3,495,620 2/1970 Raimondi et al"... ..251/65 x MAGNETIC VALVE IN TOM 3,308,925 3/1967 Alfredeen ..198/41 [72] Inventor: David L. Braun, Lake Elmo, Minn. Primary Examiner stanley H Tonberg [73] Assignee: Minnesota Mining and Manufacturing Attorney-Kinney, Alexander, Sell, Steldt & De La Hunt Company, Saint Paul, Minn. 22 Filed: Mar. 12, 1970 [57] ABSTRACT [21 1 App] NOJ 18 892 A magnetic valve for controlling the flow of solids is provided.

It consists essentially of an orifice feeding tube with a magnetizing coil surrounding it, so that lines of force of the coil are U.S. generated axially of the throat and a indle fitting into the [51] Int. Cl. ..GOlf 11/00 throat of the tube and having 5 geometrical axis parallel with [58] Field of Search ..222/76, 564, 196, 199,226; the direction of flow through the tube and a magnetic axis at 251/141 65; 259/180 46; 98/41 right angles thereto. In addition an anti-bridging and anti-loading device is provided above the spindle to prevent bridging of [56] References Cited the orifice at that point by packing of the dry powder and UNITED STATES PATENTS packing Of powder against the spindle.

3,081,009 3/1963 Cooper ..222/564 X 8 Claims, 7 Drawing Figures l7? 72 /7 115N595! NS 5 #5115 MN: us}: Ms:

. 7.3 N5 N5 N5 N5 NSlNSlN 5 N5 A 1 c 1 196 w W IJZ PATENTEDMAY 9 I972 3,661,302

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DAV/D L. BPAUN /0/ BY 1 M K QQW F104 A 7' TORNE KS SOLIDS DISPENSER HAVING MAGNETIC VALVE IN THROAT This invention relates to a magnetically operated valve. In particular this invention relates to a magnetic valve comprising a spindle magnetized at right angles to its geometrical axis in the orifice of a supply tube surrounded by a magnetizing coil. This invention further relates to a device which is positioned above such valving means to prevent packing of powder and blockage of the valving means.

Magnetically activated valves of the art appear to operate either as a pivotally supported butterfly valve in the stream which is flipped by application of magnetic forces or as a plunger type which is raised by application of a magnetic field as in a solenoid. Suitable illustrations for the former type are provided in U.S. Pat. Nos. 3,120,943 and 3,206,160 and for devices of the latter type in U.S. Pat. Nos. 3,200,997; 3,204,832; 339,808 and 2,526,735. Both types offer disadvantages in their structures in that considerable mechanical connections and linkages may be necessary for the operation thereof.

It is an object of this invention to provide a magnetically actuated valve adapted for the dispensing of powdered materials. Other objects will become evident hereinafter.

In accordance with these and other objects of the invention a magnetic valving device has been produced in which a spindle resting in the throat ofa feeder tube is agitated by application of pulsating magnetic fields induced by an external coil. Agitation takes place as a tilting motion because the spindle has its magnetic axis, that is, the direction of the north and south poles, at right angles to its geometrical axis or plane of symmetry. The axis or plane of symmetry of the spindle or other device normally coincides with that of the feeder tube in the absence of imposed magnetic field. Tilting under an imposed magnetic field is accompanied by more or less ofa nutational rotation when the spindle is free and has an axis of symmetry. It is .within the scope of the invention that the feeder tube may be elongated so that the spindle also is elongated and has a plane of symmetry. For particular purposes other shapes of tube and spindle may be adopted but fall within the scope of this invention provided that the relative relationships of magnetic axis and axis or plane of geometrical symmetry are maintained.

In another embodiment of the invention the spindle is elastically supported, for example, on a pedicel or stem. The amplitude of motion is restricted but sizes of passageways can be controlled to pass large or small amounts of solids and adjustments can be made for different flow characteristics.

Valves of the invention are especially suitable for dispensing of solids from a hopper or other supply and for controlling feed of solids to another container.

The spindle is easily constructed by building up the spindle from layers of a magnetically impregnated plastic material made as described in US. Pat. No. 2,999,275. An alternative but magnetically and electrically less efficient procedure is to embed a suitable bar magnet in a molded polymeric body. The spindle may be given a protective coating of inert material where desired and when the coating or embedding resin are sufficiently thick the bar magnet exerts only an insignificant effect on magnetic materials although it is acted upon by a magnetic field.

In conjunction with the feeding of the dry powders by the free spindle embodiment, there is a tendency for the powders to bridge over an opening to which they feed unless the opening is of very large dimensions. Even rather large openings can become bridged by powder under certain conditions. In many cases a powder may rest so heavily on the spindle as to clamp its movement. In order to achieve the greatest efficiency in operation of certain magnetic valves of the invention and to prevent the jamming of dry powders against them with inactivation thereof, it is found that an anti-bridging device is conveniently inserted in the flow channel of the apparatus. Such a device is designed so that dry powder resting on it is subjected to differential vectorial forces such that there is no tendency for the powder to bridge over. This is conveniently attained by providing arc segments of openings such that forces applied above them would tend to prevent bridging.

Having described this invention very broadly it is now more particularly described by reference to the accompanying figures wherein:

FIG. 1 showsin cross section a valving device with antibridging attachment as herein described in cross section view with extraneous portions of the hopper and feed lines broken away;

FIG. 2 shows a view looking down on the top of the device of FIG. 1;

FIG. 3 and 4 shows details of the spindle of FIG. 1 and FIG. 5 shows the side view of the anti-bridging device of FIGS. 1 and 2;

FIG. 6 shows an elongated valving device and FIG. 7 shows a valving device in which the spindle and antibridging device are elastically supported.

Referring again to the figures, spindle 101 is shown resting in throat 105 and anti-bridging device 103 resting in throat 107 of the feeding tube 109. Attached to the feed tube 109 by any convenient means are hopper 110 which is only partially shown because it may be of any desired conventional design and exit tube 111 which also may be of any desired design. The tube 109 is provided with a magnetic coil 122 which surrounds it at least over the zone in which magnetic spindle 101 is positioned. The leads for magnetic coil 122 enter the apparatus through terminal box shown only in FIG. 2.

In FIG. 1 magnetic spindle 101 is shown in its resting position at I and in broken lines at II in the position it assumes when a current is passed through coil 122. This change of position can be effected at any rate which is desired and depending upon the dimensions employed will permit greater or less amounts of the solid material to pass at each cycle. The rate of addition of solid is therefore readily controlled by applying alternating current or pulsing direct current through the coil 122. When the spindle has an geometrical axis of symmetry as shown and is unattached there is some nutational rotation. From FIGS. 3 and 4 it will be seen that spindle 101 is made up of a number of layers having north and south poles on opposite faces. This is essentially a composition of magnetic particles such as barium ferrite embedded in a suitable plastic as described in US. Pat. No. 2,999,275. Sheets of the magnetic material will adhere merely from their magnetic forces but preferably they are cemented together or adhered together by suitable adhesives. In any event the characteristic features of the spindle is that it has a magnetic axis which runs at right angles to the geometrical axis which in present illustrations are vertical. It is not essential that the top be domed in any particular fashion although for some purposes there are some advantages to having it slightly conical so that it tends to direct the flow of powder downward instead of merely being pressed against it when raised by the magnetic forces. The dimensions of the tube 109 and the spindle 101 are varied depending upon the approximate rates of flow for which it is to be used. It will be recognized that the dispensing of magnetic materials, such for example, as magnetite, Fe O is not possible through a device in which the magnet of the spindle can act upon it. For such purposes a very thick embediment is suitable. For a vast number of cases dealing with organic powders such the feeding devices of the invention are extremely convenient. For example, in dispensing food stuffs, condiments, soap powders, etc. For purposes of providing extreme cleanliness the spindle may be coated with other plastics or enamels of one sort or another to prevent abrasion or con tamination of the powders being used. All such variations are within the scope of the invention.

The anti-bridging filler 103 will be seen to be of basically conical shape as shown in FIG. 5 with square arms 90 apart on which it rests within the throat 107. The spaces between the two conical parts and the wall of the tube provide the arcuate channels for passage of dry materials to the feeding valve mechanism below.

Numerous variations on the particular details here shown will be apparent to those skilled in the art including making the supply tube opening as elongated to give a curtain of powder, oval, round, square, etc. An elongated device is shown partially in FIG. 6 in which the body 150 is of non magnetic metal such as aluminum with coils 122, outlet 152, elongated spindle 160 which has a plane of symmetry and is composed of layers of plastic impregnated magnetic sheeting as shown at 162 and by the designation of edges as N" and The method of attachment to a supply hopper is not shown as the trough as shown serves as a hopper for cases where the capacity is adequate.

FIG. 7 shows an embodiment of the invention in which an annular magnetic bridging device 175 is attached to the walls of body 170 by elastic connections 177 at a level within coil 172. Body 170 is of non-magnetic metal such as aluminum.

In addition in FIG. 7, valve 180 is provided below throat 179 of body 170 and surrounded by coil 173. Valve 180 is adjustable on support 186 by screw 182 and locking unit 184. Support 186 is a spider support occupying only a portion of the cross sectional area of tube 188. The stand on which valve 180 is supported is threaded as shown through at the lower portion and is mounted thereon by a short elastic section 190 shown as rubber. Adjustment of the height of valve 180 will be seen to vary the angle a between the outer rim of valve 180 and the narrowest part of throat 170. This angle is adjusted so that it is slightly less than the angle of repose of the solid material being dispensed and so that the solid is not dispensed until the valve is activated by pouring current through coil 173.

It will be seen that the magnetic axes of bridging device 175 and valve 180 are at right angles to the geometrical axis ofthe device of FIG. 7 and the magnetic axis of valve 160 of FIG. 6 is at right angles to the plane of symmetry of the device of that Figure.

It will be recognized that increasing the intensity of magnetic fields as by increasing the applied voltage, will increase the displacement of the ferromagnetic device or spindle acted upon. By suitable choice of frequencies, resonances can be achieved which give increased efficiency.

What is claimed is:

1. In a solid dispensing or feeding device, magnetic valving means comprising the combination of tube having a throat with walls and a magnetizing coil therearound with a ferromagnetic spindle in said throat having a plane or axis of geometrical symmetry longitudinal of said throat and a magnetic axis at right angles to said axis of geometrical symmetry.

2. A magnetic valving means according to claim 1 wherein the spindle is free from attachment to the walls ofthe throat in which it is placed.

3. A magnetic valving means according to claim 1 wherein the spindle is elastically mounted.

4. A magnetic valving means according to claim 3 wherein the spindle is supported at the base.

5. A magnetic valving means according to claim 1 wherein the tube is of elongated cross section.

6. A magnetic valving means according to claim 1 wherein the tube is of essentially circular cross section.

7. In a solid dispensing or feeding device according to claim 1, the combination ofa ferromagnetic axis in the plane of the annulus elastically attached to the walls of the throat and a magnetizing coil therearound adapted for applying alternating or pulsing direct current through said coil.

8. In a solid dispensing or feeding device according to claim 1 a filler for reducing bridging and loading of the valving means situated above the throat of the feeding tube, said filler having upper and lower conical surfaces and arms spaced apart projecting therefrom providing supports between successive arcuate passageways for the downward passage of dry solids.

Claims

2. A magnetic valving means according to claim 1 wherein the spindle is free from attachment to the walls of the throat in which it is placed.

7. In a solid dispensing or feeding device according to claim 1, the combination of a ferromagnetic axis in the plane of the annulus elastically attached to the walls of the throat and a magnetizing coil therearound adapted for applying alternating or pulsing direct current through said coil.