US2132705A - Electrical treating apparatus, especially for sterilization - Google Patents

Description

Oct. 11, 1938. I F. 5. SMITH 2,132,705

ELECTRICAL TREATING APPARATUS, ESPECIALLY FOR STERILIZATION Filed Oct. 8, 1934 3 Sheqts-Sheet 1 INVENTOR flunklirz S. Smii/L ATTORNEYS Oct. 11, 1938. s, $M|TH 2,132,705

ELECTRICAL TREATING APPARATUS. ESPECIALLY FOR STERILIZATION Filed Oct. 8, 1934 3 Sheets-Sheet 2 lNV ENTOR Igzn/rlin )5. Smith ATTORNEYS F. 5. SMITH Oct. 11, 1938.

ELECTRICAL TREA'IING APPARATUS; ESPECIALLY FOR STERILIZATION Filed Oct. 8, 1954 3 Sheets-Sheet 3 Patented Oct. 1 1, 1938 CIALLY FOR S PATENT OFFICE TERILIZATI N ELECTRICAL TREATING APPARA'IgIS, ESPE- i Franklin S. Smi h. Application October 8,

26'Claims.

This invention relates to apparatus which is especially suited for electrically sterilizing particularly food products, such as grains, cereals, and the like, and for thereby achieving the destruction of insect life therein.

Oneof the objects of this invention is to pro-- vide a simple, practical and durable treating apparatus for use among other things in dependably destroying insect life, including the eggs, larvae and pupae thereof, or the like, particularly in food products, such as cereals, grains,

flour, and theJike. Another object is to provide an apparatus of the above-mentioned character in which the construction is greatly simplified, and in which expense of manufacture and maintenance may be materially reduced. Another object is to provide in an apparatus of the aboveme nti ned character, particularly one operating at rla ively high voltages, an electrode construction that will be simple, compact, inexpensive and, moreover, readily and inexpensively replaced. Another object is to provide, in an apparatus of the above-mentioned character, an efliciently and dependably acting electrode construction, and an arrangement of moving electrodes for improving the efficiency and action of the apparatus. Another object is to provide, in an apparatus of the above-mentioned character an inexpensive, reliable and efficient insulating mounting for certain of the electrodes. Another object is to provide an apparatus of the above-mentioned character that will be rugged in construction, dependable in action, and well adapted to meet certain peculiar conditions met with in practical use. Other, objects will be in part obvious or in part, pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described and the scope of the application of which will be indicated in the following claims.

- In the accompanying drawings, in which I have shown one of the various possible embodiments of my invention,

Figure 1 is a front elevation of the apparatus, certain parts of the housing proper being broken away to show certain features more clearly and certain of the latter being shown in vertical cross-section;

Figure 2 is a plan view as seen from the top in Figure 1;

Figure 3 is a front elevation, on a greatly enlarged scale,and partly in vertical section, of one New Haven, Conn. 1934, Serial No. '747,439 (Cl. 21-102) of the electrode structures and a preferred form of drive therefor, and

Figure 4 is a perspective view on an enlarged scale of a portion of the electrode construction.

Figure 5 is a view like that of Figure 1, though omitting certain parts, showing a modifled form of certain features of the construction.

Similar reference characters refer to similar parts throughout the several views of the drawings.

Referring now first to Figure 1 of the drawings,

' I have there shown a casing or housing generally indicated at H) within which certain parts of my apparatus are enclosed and by which certain other parts may be supported, the housing being' preferably built up of sheet metal and a suitable framework and being in general not unlike that disclosed in my co-pending application Serial N0. 627,291, filed August 2, 1932} issued on October 9, 1934, as Patent No. 1,975,805. Within this housing and suitably supported by any appropriate frame and positioned adjacent the extreme ends of the housing III, as viewed in Figure 1, are pairs of generally upright standards II and I 2 in which, at their upper ends, are rotatably supported drums l3 and I4, and about the drums l3-l4'extends a belt 15, made preferably of any suitable non-conducting material, such as conton, for example.

For example, standards I I at the left-hand end may support a shaft It by which in turn the drum I3 is supported for rotation, while standards l2 may be provided with bearing members l1, adjustable in a direction toward or away from the drum l3 by any suitable means, such as a handwheel l8 in threaded relation to the bearing blocks l1, and in the latter is carried a shaft I 9 by which the drum I4 is rotatably supported.

Any suitable means may be provided to drive the belt, illustratively a motor 20 connected to the drum l3 through any appropriate driving'connection diagrammatically indicated at 2|, thereby to drive drum I3 in counter-clockwise direction and thus to cause the upper side of the belt l5, by which the products to be sterilized are carried, in a direction from the right toward the left, as viewed in Figure 1.

For details of a possible form of mounting relative adjustment and drive of the drums l3 and I 4, reference may be made 'to my above-mentioned application. In the illustrative embodiment shown in Figure 1, it will be seen that the right-hand end or the product-receiving end of the belt 15 is at a lower' elevation than the lefthand or product-discharging end of the belt; this relation, however. is not essential or set forth by way of limitation but is preferable particularly where my apparatus is to be related to foodpackaging machines in order directly to receive therefrom the packaged products discharged, the discharge mechanisms of certain standard packaging machines being at times at a relatively low elevation to which the lower elevation of theproduct-receiving end of the belt II as just mentioned is thus better accommodated.

The upper portion of the frame or housing It, supports, in depending relation, a suitable insulating structure generally indicated in Figure 1 at 22 and it may include a lower ring member 23 from which a suitable number of structures 24 extend upwardly to be supported by the frame 10, preferably-for adjustment in an upnnd down direction, in any suitable manner, the construction of the insulating structure 22 and its mounting conveniently taking the form of that described in detail in my above-mentioned application.

The ring-like member 23 carries, at substantially diametrically opposed points but in line with the direction in which the belt 15 extends, two brackets 25-26, preferably of metal, which in turn support in a manner-more clearly described hereinafter, rotating electrode structures S and T,\r espectively (Figure 1), thebrackets 2526 being suitably shaped or inclined, as indicated in- Figure 1, to maintain the axis of the rotating electrode structures S and T substantially normal to the plane of the product-carrying portion of the belt I5, such inclination or shape being necessitated by the above-mentioned inclination of the belt itself.

Since the electrode structures S and T are of substantial identity of construction, it will sufflee to describe one of them in detail and accordingly reference may now be made to Figure 3, in which one of the structures, more specifically the-structure S, is shown on an enlarged scale and also in vertical section.

Accordingly, I first provide a stud shaft 2 which is shaped to be received or gripped or otherwise suitably rigidly secured to the bracket 25, being held by the bracket so that its axis is normal to the plane of the product-carrying portion of the belt i5. The bracket itself is maintained at a high potential, illustratively a potential on the order of 150,000 volts, and preferably an alternating potential preferably of relatively high frequency, such as a frequency on the order of 640 cycles per second. Referring back to Figure 1, and as is more clearly described in my above-mentioned application, to which reference may be had for details, the housing I0 carries a transformer casing 28 within which is mounted a' high frequency transformer 29-30 whose low voltage winding 29 is provided with suitable high frequency energy as from an alternator 3|. One terminal of high voltage winding 30 is grounded to the casing 28, as at 32, and hence to the housing 10, and the other terminal is carried as by conductor 33 through the high voltage insulating terminal 34. Terminal 34 projects downwardly from the transformer casing 28 and is arranged within and is preferably concentric with insulating structure 22. Suitable conductors 35 are provided to carry this relative high potential to the brackets 25-26 and hence to the stud shafts held thereby and hence to the electrode structures S and T.

The insulating structure 22 thus dependably insulates'tliie' electrode structures S and T from otherwise shaped externally to be cylindrical and to have a flange 31. Resting against flange 31 and encompassing the rim portion 31 is the stator 38of a motor, preferably an alternating currentmotor and preferably an induction motor. Stator 38 is preferably made up of a suitable number of annular laminations as is clearly shown in Figure 3, the laminations being backed up by plates 38 and 38 I Stator 38 is held in position by a ring member 89 shaped to fit against-the upper side thereof so as to form a counterpart to the flange 31. Suitable screws 40 draw ring member 39 to the spider member 31, thereby securely clamping the stator 38 and its components together and securely holding them in place. W ,7

The stator 38 is appropriately slotted and carries interconnected coils to form a winding 4!. One terminal of winding 41 is attached to stator 38, as at 42, which is electrically connected to spider 31 and through it to stud shaft 21. The other terminal is connected to an insulated conductor 33, which extends through suitable channels in the spider member 31, hub member 31 and stud shaft 21, and is connected to one side of a low voltage source. As will be explained later, the other side of this low voltage source is grounded to stud shaft 21;

With the assemblage of the parts carried thus far and with stud 21 being provided with a threaded portion 21', a nut #54 is threaded onto this threaded portion, is driven home, and thus the spider 31 with its above-described parts, is clamped (specifically, its hub 31) with the inner race 36 between the stud shaft shoulder 21"- and the nut 64, and accordingly, with stud 21 I rigidly held in its bracket, stator 38 is likewise rigidly supported and held against rotation.

Mounted around stator 38 so as to coact therewith is a rotor 45 (Figure 3), made up of annular laminations and outer plates 15 and 05 of heavier construction and having its inner periphery provided with a squirrel cage winding 46. Its inner periphery is juxtaposed, with appropriate clearance, to the outer periphery of stator 38.

Rotor 45 is held in place by two rotatably supported casing members 41 and 48, the upper casing member 41 being counterbored as at 41 to provide a seat for the rotor 45. The lower casing member is provided with a ring-like portion 48 which fits against the under face of the rotor 45 and which, when screws 49 are threaded into the upper casing 41 acts to securely clamp the upper and lower housing portions 41 and 48 together and the rotor 45 therebetween.

The upper housing portion 41 is provided with an inner hub-like portion 41 flanged as at 41 to engage the under side of the outer race 36 of the bearing 36. The upper end of the inner hub-like portion is threaded, as at b1 to receive a nut 50 which securely clamps the outer race 36 against the flange 41, The nut 50 is shaped to overlap the shoulder 21' on the stud 21 so that, with a felt washer 5| interposed therebetween. a dust-proof seal is formed between the stud 21 and the rotatable housing portion 41.

The lower housing portion 48, instead of being apertured as the housing portion 41 is in order to receive the stud 21 therethrough, extends entirely across the lowermost end of the stud 21, but it is counterbored as at 4|! to have secured therein the outer race 52 of a combined radial and thrust anti-friction bearing 52 whose inner race 52 is fittedor secured to the stepped end portion 21 of the stud 21.

By this relation of the bearings 38 and 52, the housing 41-48, with its rotor 45, is dependably and reliably supported for free rotation about the axis of the stud 21 and the relation of the parts will be seen to be such that, with oneterminal of the winding 4| grounded as at 42 (already described above) there remains only the terminal or conductor 43 which need be connected appropriately to energize the winding 4| and thereby cause rotation of the housing 41-48.

This connection or completion of the circuit of the motor (and this is, of course, true with re-' spect to the motors of all of the electrode structures S and T, for example) may be completed, if possible, reference now being made to Figure 1. In the transformer casing 28, carried by the housing I0, is mounted an insulation transformer 53-54; its primary winding 53 is connected to a suitable source 55 of commercially available alternating current energy, such as.a 110- or 220- volt, 60-cycle circuit. Its secondary winding 54 (the ratio of transformation can be unity) is insulated from the primary winding 53 for voltages on the order of those (150,000 volts, for example) which the transformer 29-30 supplies to the electrode structures S and T and one terminal of the secondary winding 54' may be connected, as by conductor 56, to the high voltage conductor 33; the latter, as already above described, carries the high potential to the electrode structures S and T and by this connection 56, conductor 33 also extends one side of the transformer winding 54 to the electrodestructures S and T, and by the ground connection 42 (Figure 3) of the motor winding 4|, thus connects the latter to one side of the transformer winding 54. The other terminal of transformer winding 54 is carried by conductor 51 out of the transformer casing 28 through the high voltage terminal construction 34 by way of the end terminal 58 thereof. In the terminal construction 34 conductor 51 and terminal 58 are insulated from the high voltage parts only for the voltage, say 110 or 220 volts, of the secondary winding 54 of the transformer 53-54. Conductors 43, (see also Fig. 3) emerging-from the stud shafts 21 of the electrode structures S and T, are connected to terminal 58, and though the motors themselves and their circuits are at this very high voltage, low voltage energy to the motors is supplied in a manner adequately safeguarding the low voltage supply circuit 53-54. In this manner, rotation at appropriate speeds of the electrode structures S and T may be achieved.

This electrode construction, for reasons, certain of which are later mentioned, is preferably made of sheet metal and may be given the shape about to be described in any suitable manner, such as, for example, by stamping or otherwise drawing or shaping out of sheet metal, or even by electro-deposition of a suitable metal onto an appropriately shaped form or mold; though, of

course, in accordance with certain other features of my invention, I may achieve certain other advantages by constructions other than sheet metal and may make it even solid, as by casting, so long as the external features of shape are retained.

Externally the electrode construction has an undulated lower surface like that indicated in Figures 1 and 3, but better shown in Figure 4, in which the annular electrode structure is generally indicated at 60 and has projecting downwardly therefrom individual electrode members 6|. Where the mean diameter of the annulus or circularly arranged electrodes 60 is on the order of 16" or 18" and the speed of rotation thereof on the-order of 2000 or 3000 R. P. M., the number of the individual electrodes 6| may be on the order of, 8. The individual electrodes 6|, though rounded somewhat and preferably free from sha p points, are of substantial radial dimension or thickness in the direction of a. radius, and each electrode member thus presents a; substantial surface area toward the belt l5 (Figure 1).- However, in the illustrative embodiment, this surface is of greater dimension in the direction of the radius than in the direction of the circumference of the circle about which the electrodes 6| are arranged. This area is indicated or defined roughly by A in Figure 4 (see also Figure 3 where the length and breadth of this area are indicated by the character A), and it is principally from his area that the discharge, that achieves sterilzation, emanates.

' Still referring to Figure 4, it will be seen that,

from this area A, each electrode 6| merges, by

appropriate curvatures, in four general directions. Firstly, there is a surface portion B (see also Figure 3) which is the leading edge as the electrode is rotated, which merges rather abruptly toward the plane of the annulus or base portion of the structure 60. Then there is a surface portion C (Figures 3 and 4) which defines the trailing portiimnofthe individual electrodes 6| and which merges quite gradually in a direction rearwardly of the surface portion A and toward the annulus or base portion of the structure 60. Then there are the lateral portions D and E (see Figure 3) which merge from the surface or area A into the base or annulus portion of the structure 68. The trailing merging portion C of one electrode 6| intersects the leading portion B of the'next succeeding electrode 6|, and at the intersection the surfaces are preferably curved somewhat to avoid too abrupt angles.

Furthermore, the trailing portion C is preferably shaped so that the cross-section along a radius of any electrode 6| gradually changes in shape from the shape indicated at F to a shape shown at G.

The lower housing portion 48 is provided with an annular flange 48 upon which are formed two downwardly extending ribs 48 and 48 The annulus or base portion of the electrode structure 60 (Figure 4) terminates in flanges 60 and 6|) (Figure 3) which are respectively received by ribs 48 and 48 in the recesses 48 and 48 Screws 62 detachably secure the electrode structure 60 in place.

Thereby the electrode structure 60 may be quickly secured in place and may be quickly replaced. Such replacement may be effected where practical conditions of use of the apparatus may require a change in the number of individual electrodes and more particularly where disintegration of the electrodes, due to long-continued emanation therefrom of the high voltage corona or disruptive dischargehas brought about inefflciency of action thereof or shape or action.

By providing individual electrodes somewhat blunt and of substantial active area (surface area A of- Figure- 4, for example) I am enabled to in- I 7 crease the capacity of the apparatus and otherbe more clearly set forth later, after certain other features of action and construction of the apparatus are described. Furthermore, the

shape thus given the individual electrodes 6| through which ionization more readily takes non-uniformity of wise to improve its action and operation, as will place and by which disturbance ofthe desired:

action would result. The unitary electrode member above described in detail is secured in the manner above set forth to the rotating member of the electrode structure S, where the motor is constructed to rotate the electrodes 6| in a clockwise direction, (Figure 2). The motor of electrode structure T isarranged to rotate in the reverse direction, namely, counter-clockwise, and

a similar but reversed electrode is provided. Slit is thus clear that in structures S and T, the portions B of the individual electrodes 5| are leading portions and portions C are the trailing portions.

As will now be clear, the electrode structures 5- and T take' part in the determination of two treatment zones through which the product carried by the belt i5 is to be passed; coacting with the electrode structures S and T, but positioned on the other side (specifically, underneath) the path of travel of the products to be treated, are' coacting electrodes. In so far as certain features of my invention are concerned, these coacting electrodes preferably take the form about to be described, and since the electrode structures that coact with the structures S and '1, respectively, are of substantially identical construction, it will sumce to describe only one of them in detail and accordingly reference may now be made to Figures 1 and 2.

First it may be noted that, underneath the upper or product-carrying side of the belt it, I provide a suitable insulating structure which, illustratively, may comprise two side beams and 65 (Figures 1 and 2) made of any suitable dielectric material, such as laminated bakelite, supported at their respective ends, in any suitable manner, by the pairs of upright standards It and I2. These insulating beams 65-66 support, along their upper edges, a plate-like member 67, also of such insulating material, member 61 extending from drum It to drum l4, and providing a substantially fiat table-like support upon which the belt l5 rests and by which the belt is held against sagging, under its load of products subjected to treatment. Underneath the upper side of the belt 115 and in line with the slightly inclined axis of the electrode structure S and extending transversely of the frame or casing I0 is a cross-brace structure 68 preferably taking the form of an inverted U, having therefore two laterally spaced vertical legs 68 and 68'', joined at their upper ends by the cross-member 68, the latter extending above the lower or return side of the belt l5 and the legs 68*68' being each on one side of the return side of the belt IS. The legs li8 68 may be secured to the base portion of the frame or housing It in any suitable manner and the parts are so shaped or related that 9,188,705 -'the cross-member has the plane of its upper faceat right angles to the axis of the electrode "structure 8, being therefore slightly inclined to axis of the electrode structure S and of larger diameter (see Figure 1) than the maximum diameter of the electrode annulus 80 and fitted into that opening 61 is a. disk-like member generally indicated at 68, made ofquartz, pyrex, glass, or other suitable solid dielectric material, being provided with a downwardly ex tending peripheral flange 69 (see Figure l). Member 69 has-its upper surface alined with the upper sm'face of the belt-supporting plate member 61, forming in effect a continuation of the latter, and is held in that position by a'sleeve or tube-like solid dielectric support It! secured at its lower end, as at H, to the cross-part 68 of the cross-supporting structure ,68 above-described. The depending flange portion 69 of the disk-like member 69 interfits with the upper portion of the tubular dielectric support III, as by having the upper portion of the member 10 receivable within the depending flange portion 69, suitable stop means, such as a peripheral flange or bead l0 determining the extent of this interfitting 01' these parts and thus holding the By this construction, member 69 may be easily removed from the apparatus and replaced, as

by lifting the latter upwardly through the opening 61"} and thus disengaging it from its supporting insulating structure 10.

The solid dielectric member 69, of suitable thickness, provides a capacity or dielectric with the under side of which the rotating electrode structure coacts. This coacting electrode structure is preferably a rotating one and its axis of rotation is preferably coincident with the axis of rotation of the upper electrode structure S. Its preferred or illustrative embodiment includes a driving motor and housing construction, excepting for the flange portion 38, in substantial identity with the motor structure above described in connection with Figure 3 and which, it will be recalled, is embodied in the upper electrode structure or structures S and T.

Accordingly, referring to Figure l, where this rotating electrode structure coacting with the structure S is generally indicated by the reference character U, a similar but reversed rotating electrode structure, coacting with the upper electrode structure T, is indicated generally by the reference character V. Mounted upon the crosspart 68 of the cross-supporting structure 68 by the stud shaft 21 is a motor'construction like that of Figure 3. The motor housing 41-'48 extends upwardly from the cross-support 68, the stud or supporting shaft 21 extending downwardly into the latter and is anchored thereto in any suitable way. tion 48 (Figure 1) is uppermost and instead of the peripheral flange 48, as in Figure 3 (and as ,embodied in the structures S and T) the motor of the electrode structure U has one of its housing portions, such as the housing portion 48, provided with a peripheral flange 48 extending downwardly, thus to bring it into close proximity to the cross-part 68 and thus to increase the Accordingly, the housing por-' insulating support 12 (Figure 1), being secured thereto in any suitable manner, as by screws.

The insulating sleeve I2 is thus mounted for rotation (since the housing 41-48 of the motor rotates about the fixed stud 21) that is coincident with the axis of the upper electrode structure S and also coincident with the axis of the disk member 69 and its sleeve support 10.

The upper end of the rotating insulating sleeve 12 carries an annulus 13 which may be of metal .or of solid dielectric material and whose upper face, as viewed in Figure 1, is shaped like the under face of the flange 48 (Figure 3) of the a motor housing of the upper electrode structure S or T, being thereby recessed or otherwise shaped, as above described, to receive and have secured thereto, as by the screws 62 of Figure 3, an electrode annulus like the member 60 above described in connection with Figures 3 and 4, having therefore individual electrodes 6|, illustratively 8 in number and hence of the same number as those in the upper electrode structure S.

Two electrode annuli 60 are thus rotatably juxtaposed to each other, the one being associated with the electrode structure S and on one side of the path of travel of the product undergoing treatment and the other forming part of the electrode structure U and positioned on the other side of this path of travel. But where the structure S is rotated in clockwise direction, as viewed from above in Figure 1, the electrode structure U is preferably rotated in counterclockwise direction and hence preferably oppositely with respect to the structure S; accordingly, the unitary electrode annuli of these two structures are of identical shape particularly as tothe individual electrodes 6| thereof and their leading and trailing sides or surfaces.

Preferably the under side of the solid dielectric member 69 is provided with a concave groove 69 into which the rotating curved-surfaced upper ends of the electrodes 6| of the structure U virtually fit, the curvatures of the faces of the two parts being closely similar though there is provided adequate clearance to permit free rotation of the lower electrode structure relative to the dielectric member 69.

Energy to the motor of the structure U may be supplied as from the source 55 or it may be supplied from the same source that supplies energy to the motors of the structures S and T, and the circuit thereof, the same source being connected to the circuit of the motor of the other electrode structure V as diagrammatically indicated in Figure 1. One conductor 14 of this circuit is grounded to the cross-structure 68, to which *the studs 21 of the motors also are grounded and to which, therefore, the one terminal 42 (see also Figure 3) of the winding 4| is grounded or thereby connected; the other conductor of the circuit is connected to the resultant conductors 43, of the two motors of the structures U and V, conductors 43 being, as will now be clear, connected to the other terminal of the winding 4|.

As above noted, the lower electrode structure .V (Figure 1) is similar in construction to electrode structure U, the solid dielectric disk 69 and its insulating support 10 from the cross-structure 68 being, of course, duplicated. Where, however,

electrode structure T rotates in counter-clockwise direction, (Figure 2), the electrode structure V preferably rotates clockwise, and the electrode annulus 60 of the latter with its individual electrodes 6|, is in suchcase identical with the structure 60 of the upper electrode structure T.

There are thus provided two treatment zones, namely, one treatment zone between the structures S and U and another treatment zone between the structures T and V, the electrical circults of these two treatment zones being in parallel (in the above-described illustrative embodiment), the high potential portions thereof (the electrodes of structures S and T) being, as above described, connected to the high tension side of the high voltage winding 30 (Figure 1). The other side of the high voltage winding 30 is grounded as at 32 as already above described, and hence is grounded to the frame of the apparatus and to the sheet metal housing l0 thereof. In Figure 2 is shown the front wall Ill and the rear wall In of the housing It), these walls extending substantially vertically and being laterally spaced from the belt I5 (see Figure 2); they are, as above-mentioned, of metal and at ground potential. Extending substantially parallel to the rear wall Ill and spaced inwardly therefrom (Figure 2) is a plate 16 of metal and of substantial area (see Figure 1) and it is insulatingly supported from the frame or housing It) by any suitable insulating support diagrammatically indicated at 11 in Figure 2, the support being preferably provided with means, diagrammatically indicated at 18, whereby the spacing of the plate 16 from the rear wall 10 may be varied or changed at will.

A substantially similar plate 19 (Figure 2) extends parallel to the front wall in, being spaced inwardly therefrom and held by an insulating supporting and adjusting structure 80 and 8! substantially similar to the structures I1 and 18 above described;

Parts 16 and lil form an air condenser which is to complete the circuit of one of the treatment zones and parts 19 and Ill form an air condenser which is to complete the circuit of the other of the two treatment zones. The completion of these circuits may be achieved by capacitatively or conductively coupling the rotating electrode annulus of each of the lower rotating electrode structures U and V to one of the plates 16, 79.

Referring to Figure 1, I may provide at the upper end of the stationary insulating sleeve I0 of the electrode structure V in a suitable support 83 a suitable brush 82, yielding in and of itself, or yieldingly supported, and pressed against the conductive electrode annulus 60; a conductor 84 electrically connects the brush 82 and hence the electrode members SI of the structure V to the condenser plate 16. Such an arrangement is illustrative of how the rotating electrodes underneath the belt may be conductively connected to one side of the air condenser, such as the condenser 16-I0 (Figure 2).

As above noted, however, such a circuit may also be completed otherwise than conductively. For example, referring to Figure 1, the lower electrode structure U, may have mounted upon its insulating sleeve 10 and preferably upon the interior of the upper end thereof, a suitable electrode or electrodes spaced from the rotating electrode annulus B0, to form a capacity or short so as to be spaced from the electrode annulus 00 therein. The balls may be electrically interconnected in any suitable manner and are then, by conductor 88, connected to the condenser plate 18 of the condenser l0l0 With the circuits of the two treatment zones electrically completed, illustratively in the manner above described, and with the motors of the various upper and lower electrode structures set in motion, operating at a suitable speed, say a speed on the order of 2000 R. P. M., and rotating in the respective directions above described, there is produced, underneath the rotating electrode annulus of each of the upper structures 8 and T, an annulus of highly stressed air, the annulus of air being determined by the rotating electrodes 6| of the upper and lower electrode structures S and U on the one hand and T and V on the other hand (for the second treatment zone). This annulus, moreover, is of substantial dimension in a radial direction, being in eflect determined by the radial dimension of the surface portion or area A as was described above in connection with Figure 4. The shapes of the electrodes 6| contribute toward minimizing the eflects of rarefication of this annulus of stressed air, as above noted, while the rapidly changing relation between the eflective portion A of the electrodes iii of the upper structure 8 with respect not only to the surface portion or area A of the electrodes 6| of the lower structure U but also to the progressively receding or trailing portion C and the relatively steep portion B, and vice versa, brings about a thorough ionization of this annulus of air, the latter thereby breaking down and becoming conductive, appearing to the naked eye as a substantially solid annulus of corona-like discharge, being made up of a multitude of fine discharge streamers.

The corona discharge impinges upon the belt or upon the dielectric disk member 69, the latter forming with the lower end (as viewed in Figure 1) of the corona discharge a capacity or condenser whose effective action is concentrated and controlled by the rotating electrodes of the lower structure U. The flow of energy in the circuits of the treatment zones is controlled or limited not only by that condenser action but also by the condensers |il|ll and 16l0 (Figure 2). These condensers in particular are dimensioned and proportioned, particularly as to the air dielectric therein, so that they may individually stand the maximum voltage of the system (on the order of 150,000 volts) without complete breakdown or rupture; this latter action in particular insures that the breakdown or discharge in the treatment zone or zones is of the character above described and may be considered only as local rupture, as distinguished from a complete sparkover or disruptive discharge.

This action is particularly important where the products to be treated are packaged products, such as cereals, flour, and the like, for I am thereby enabled, particularly as is more clearly described in my above-mentioned copending application, to insure against puncturing of the cardboard or likev material of the cartons or packages of the products and to make certain that such materials function as dielectrics or capacitances in the treatment zone without interfering with the desired uniform ionization of the air or air spaces within the package or carton itself. Thus, the corona-like discharge is produced within the carton or package, and insect life, which is of extremely low permittivity, and

in fact is of relatively high conductivity, is sought out by the discharge and thus destroyed.

The treatment zone between the structures T and V is directionally opposite in action from the action of the treatment zone between the structures S and T, all with respect to the path of travel of the products undergoing treatment, as determined by the conveyor belt I5; this is important particularly where packaged products are subjected totreatment, overcoming in a dependable and more eflicient way the effects of the vertical side and end walls of the packages in so far as the latter cause deflection of the corona discharge or cause the latter to be absent on those interior sides of said side walls away from which the rotating electrodes would otherwise tend to sweep the discharge. But the provision of two successively acting treatment zones having the above-described structural features is and lower electrodes of the second treatment zone rotate in the same direction, when viewed from above, but in a direction opposite from the direction of rotation of the electrodes of the first treatment zone. And hence I have disclosed, as illustrative of how such contingencies may be met in practice, two treatment zones in which the actions may be reversed with respect to the path of travel of the products undergoing treatment.

Where, however, the upper and lower electrodes of the treatment zone have shapes like those above described and rotate in opposite directions, when viewed from above (Figure l), I achieve excellent results by the use of only one treatment zone, inasmuch as the shapes of the electrodes and the opposite directions of rotation or movement thereof achieve such a peculiar and divergent action, though concentrated within the above described annulus, that the eflfects of the vertical walls of a package tending to deflect or retract the discharge are'substantially mutually overcome by the oppositely moving individual electrodes. For example, where a vertical wall of a package tends to deflect or refract the streamer or streamers of discharge emanating from one electrode member SI of the upper electrode structure S because that member moves in one direction, the action is counteracted by a momentary coacting member SI of the lower electrode structure U, moving in the opposite direction and tending to overcome or correct the just-mentioned tendency of deflection or refraction. V

Should the electrode members SI of any of the rotating electrode annuli 60 become pitted or worn or deteriorated (particularly those of structures S and T), so as to have impaired the sterilizing action, the electrode annulus 60 may be easily removed and replaced. Furthermore, should the material undergoing treatment require a change in the number or shape of the electrode members til, the electrode annuli 60, whether in an upper electrode structure or in a lower electrode structure, may be easily removed and replaced. Furthermore, the electrode annuli are light in weight, do not add to the bulk electrical action. For example, the upper eiec-" trode structures 8 and T are readily and quickly raised or lowered, while maintaining proper parallelism with respect to the inclined belt ii; the air condensers Hi-4|) (Figure 2) and IQ-I may be easily varied to meet diflerent electrical conditions met with in practice; and thus a wide range of adaptability to various requirements or characteristics of the products undergoing treatment may be met.

As above noted, the lower or return side of the belt I passes through or between the legs of the inverted U-shaped cross-supports 68 which support the respective lower electrode structures U and V. To one of the cross-sup-,

ports 68, the left-hand one, for example, as viewed in Figure 1, I pivot as by a link 90 a curved shoe SI of appropriate weight, having a width substantially like that of the belt l5; shoe 9i rests against the upper face of the under or return side of the belt l5, insures that the latter clears the lower electrode structure and related parts, and maintains appropriate tautness of the belt to achieve its desired action in conveying the products through the treatment zone or zones.

Adjacent the drum i3 (Figure 1) I provide a support 92, preferably of spring material, carrying at its end a scraper or brush 93 that extends across the face of the drum I3, thereby to keep the face of the drum clean and free from dust, particularly flour dust, and the like. The brush 93 scrapes any such material off the drum and adjacent the drum I4 I mount a brush or scraper 94 bearing against the upper face of the under side of the belt l5 and extending diagonally with respect to the latter, thereby to clean off the inside face of the belt and remove therefrom dust, flour, cereals, or like foreign matters and thereby insure that the under face of the belt that is carried over drum i4 and particularly along the belt supports 61-69-69 is likewise free from foreign matter. Thus, the initial and intended characteristics of each treatment zone are held free from interference or change and dependable continuity of operation and action is achieved.

In the embodiment above described, the action of the condenser lil--Ill in the circuit of one treatment zone and of the condenser 'Hi--lll (Figure 2) in the circuit of the other treatment zone as well as the constructions thereof have been described. In accordance with certain other features of my invention, I prefer to embody that condenser construction in the form better shown in Figure 5, in which the apparatus and arrangement are substantially the same as that of Figure 1 excepting for this condenser arrangement.

Referring then to Figure 5, and particularly to the treatment zone formed by the coacting structures S and W, it is first to be noted that the motor of the electrode structure W is physically at ground potential, being grounded through the inverted U-shaped support 68. I prefer to form the upwardly extending portion of the motor casing or housing, or to cover the latter by a sheetmetal closure, as is indicated at I00. Thus it provides an upwardly directed plate-like memher or surface llll, substantially horizontal, with peripherally extending edge portions i0 I a that are of appropriately large radius of curvature. Thereby I form one grounded plate or plate electrode of an air condenser, the other plate or plates of which are constituted of one or more disk-like members i02-lil3, spaced above the grounded plate member iill, and of substantially the same diameter as the latter. ranged cc axially or concentrically with the sleevelike insulating support 12, the upper plates being supported in and insulated by the latter.. These supports take any appropriate form, such as radially extending supports lllhwhich may be metallic and which are suiflcient in number about the periphery of the plate member or members and staggered with respect to each other to provide long leakage paths along the insulating sleeve support 12. The staggered arrangement provides that no two supports I04 engage the member 12 in an element of the cylinder thereof.

These plates, thus supported in the member 12, form the air condenser that functions in the circuit of the structures S and W, a similar arrangement being provided in the insulating sleeve of the lower electrode structure X of the structures X and '1' that form the other treatment zone; these air condensers being proportioned electrically to function as do the air condensers of Figure 2.

The uppermost plate is suitably coupled electrically to the electrode members 60, preferably, however, by way of a ball I05 carried by the uppermost plate I03 and positioned in close proximity to the annulus which supports the electrode stucture This forms a capacitive coupling like that described above in connection with Figure 2, both of these couplings, however, being proportioned to function virtually as spark gaps.

With these parts functioning as spark gaps, I make certain that corona production and hence the action in the treatment zone takes place at a higher point on the voltage wave and hence at a higher average voltage than would otherwise be the case, the spark gap or gaps being proportioned to require the impressing thereon of a voltage in excess of a critical voltage such that the eifective current flow in the circuit or circuits and hence corona production commences and takes place at the above-mentioned higher point on the voltage wave.

The arrangement of Figure 5, moreover, achieves highly desirable compactness mechanically.

The term undulated surface has been used in its broad sense in the specification and claims to designate a generally smooth wave-like surface such as the discharge surface of the electrode members.

Thus, it will be seen that there has been provided in this invention an apparatus in which the various objects above noted, together with many. thoroughly practical advantages are successfully achieved. The apparatus will be seen to be of a thoroughly practical character, relatively simple in its mechanical arrangement and construction, electrically of high eiiiciency of action, and in general of inexpensive but of thoroughly practical and reliable construction and arrangement. Moreover, it will be seen that there has been provided an apparatus well adapted dependably to meet the varying conditions of hard practical use.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings, is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In electrical treating apparatus of the type All of the plates are arwherein a product to be treated is positioned within a; treatment zone and subjected to discharges resulting from impressing a high potential upon electrode structure. in combination. an electric discharge circuit comprising two opposed rotatable electrode means connected to a suitable source of potential through means forminga condenser incapable of breaking down at the voltage of said source, said electrodes having discharge members or substantially the same number and of substantially similar efl'ective shape, means for conveying a product to be treated through the space between said opposed electrode means, said electrode means rotating about axes extending in the same direction but normal to the path of travel of the product to be treated, and means for rotating said opposed electrode means at substantially the same speed.

2. An apparatus like that of claim 1 in which the opposed electrode means are each substantially annular in shape and are metallic and in which the discharge members thereon are formed by a plurality 'of circumferentially spaced protrusions for controlling the discharge therebetween.

3. An apparatus like that of claim 1 in which one of the electrode means is connected directly to one side of the high potential source and in which the other is carried by a rotating member of insulating material. 7

4. An apparatus like that of claim 1 in which one of the electrode means is connected directly to one side of said source of potential, the other of said electrode means being carried by a rotating member of insulating material which is in the form of a hollow cylinder, the electrode means being mounted at one end of the latter, and the rotating means being connected to the other end of the latter.

5. An apparatus like that of claim 1 in which the two electrode means are driven respectively by two electric motors from a source of electrical energy, there being an insulation transformer in the circuit of one motor for insulating said source of energy therefrom and the circuit of the motor of the other electrode being insulated by a cylindrical solid dielectric means forming the driving connection between that electrode and its motor.

6. An apparatus like that of claim 1 in which the opposed electrode means are rotated in opposite directions.

7. An electrical discharge electrode and drive therefor comprising, in combination, a rotatable support having annular recesses and an annular unitary electrode structure'having a plurality of protrusions in one direction along the axis and ring-like means exposed in the other direction of the axis for coaction with said annular recesses. I

8. An electrode structure of thin sheetlike metal and annular in form, being substantially U-shaped in cross-section, the vertical height of the U of the said cross-section progressively varying throughout repeated intervals to provide a plurality of electrode protrusions of substantial dimension in a radial direction, substantially abrupt at their leading ends and gradually curving and diminishing along their trailing ends.

9. In electrical treating apparatus of the type wherein a product to be treated is positioned within a treatment zone and subjected to discharges resulting from impressing a high potential upon electrode structure, in combination, vertically spaced electrode means in circuit with a source of high potential and with a capacitance; a conveyor belt having one'side thereoi' passing between said spaced electrode means, a disk-like member of solid dielectric material interposed between said belt side and the electrode means underneath it, and means substantially sleeve-like in form and made of solid dielectric material !or supporting said disk-like member.

- 10. An apparatus like that of claim 9 in which the sleeve-like support is supported by an inverted U-shaped structure between the arms of which the lower side of said belt passes.

11. An apparatus like that of claim 9 inwhich the lower electrode means is rotatable and is driven by a sleeve-like insulating member substantially coaxial with and within said sleevelike support.

12. In electrical treating apparatus of the type wherein a product to be treated is positioned within a treatment zone and subjected to discharges resulting from impressing a high potential upon electrode structure, in combination, an electric discharge circuit comprising two opposed electrode means connected to a suitable source of potential through means forming a condenser incapable of breaking down at the voltage of said source, and means for supporting a product to be treated in the space between said electrode means, one of said electrode means being supported by a hollow solid dielectric structure and said condenser-forming means comprising plate members supported within said hollow structure.

13. In electrical treating apparatus of the type wherein a product to be treated is positioned within a treatment zone and subjected to discharges resulting from impressing a high potential upon electrode structure, in combination, an electric discharge circuit comprising two opposed electrode means connected to a suitable source of potential through means forming a condenser incapable of breaking down at the voltage of said source, and means for supporting a product to be treated in the space between said electrode means, one of said electrode means being rotatable, a rotating member, solid dielectric means connecting said rotatable electrode means to said rotating member, said condenserforming means comprising plate members supported by said solid dielectric means.

14. In electrical treating apparatus of the type wherein a product to be treated is positioned within a treatment zone and subjected to discharges resulting from impressing a high potential upon electrode structure, in combination,

- an electric discharge circuit comprising two opposed electrode means connected to a suitable source of potential through means forming a condenser incapable of breaking down at the voltage of said source, and means for supporting a product to be treated in the space between said electrode means, one of said electrode means being-rotatable, an electric motor, a tube-like insulating means for insulatingly connecting said motor to said rotatable electrode means, said condenser-forming means comprising plate means within said tube-like insulating means.

15. An apparatus like that of claim 13 in which the rotating member is a motor physically connected to one side of said source and is shaped to form part of said condenser-forming means.

16; In electrical treating apparatus of the type wherein a product to be treated is positioned within a treatment zone and subjected to discharges resulting from impressing a high potential upon electrode structure, in combination, an electric discharge circuit comprising two opposed electrode means connected to a suitable source of potential through means forming a condenser incapable of breaking down at the voltage of said source, means for supporting a product to be treated in the space between said electrode means, and a spark gap in said circuit in series with said condenser.

1'7. An electrode structure comprising an annulus including spaced electrode protrusions along an end face thereof, the cross-section of said annulus varying progressively throughout the armate length of each electrode protrusion whereby each of the latter terminates substantially abruptly at its one end and gradually curves and diminishes therefrom to merge at its other end into said annulus.

18. A sheet metal electrode comprising an annulus having an inner cylindrical face, an outer cylindrical face and an end face which has protrusions formed thereon, each of said protrusions having one face which is in a plane containing the axis of said annulus and faces which are extensions of said inner and outer cylindrical faces.

19. A sheet metal electrode comprising an annulus having an inner cylindrical face, an outer cylindrical face and an end face which has protrusions formed thereon, each of said protrusions having one face which is in a plane containing the axis of said annulus, faces which are extensions of said inner and outer cylindrical faces and a face which extends in an arcuate direction with respect to said annulus;

20. A sheet metal electrode comprising an annulus having an inner cylindrical face, an outer cylindrical face and an end face which has protrusions formed thereon, each of said protrusions having one face which is in a plane containing the axis of said annulus, faces which are extensions of said inner and outer cylindrical faces and a face which extends in an arcuate direction with respect to said annulus, said faces being joined by rounded edge portions. v

21. In treating apparatus, an electrode comprising an annulus having protrusions along one face thereof, each of said protrusions having one face having a steep slope in a circumferential direction and another face which has a gentle slope in a circumferential direction.

22. In electrical treating apparatus of the type wherein a product to be treated is subjected to a discharge resulting from impressing a high potential across two electrode structures, the combination of, an annular electrode mounted to rotate about its axis and having an undulated discharge surface.

23. In electrical treating apparatus, the combination of, an undulated electrode structure which includes a discharge surface, a cooperating electrode structure having spaced portions which act as cooperating discharge surfaces, and means to move said undulated electrode so as to vary the potential gradient within the discharge zone.

24. In electrical treating apparatus of the type wherein a product to be treated is subjected to a discharge resulting from impressing a high potential across two electrode structures,, the combination of, two opposed electrode structures, one of said electrode structures including an element which has an undulated discharge surface and is rotatable so as to move the various portions of the discharge surface thereof toward and away from a cooperating surface'of the'other of said opposed electrode structures.

25. In electrical treating apparatus of the type wherein a product to be treated is positioned within a treatment zone and a high potential is impressed across two electrode structures upon the opposite sides of said treatment zone, the combination of, an annular electrode mounted to rotate about a fixed axis, a second electrode spaced from said annular electrode and adapted to cooperate therewith to form a zone for the treatment of materials, a solid dielectric means so mounted that a portion thereof will be between the active discharge surfaces of said electrodes at all times regardless of the relative movement of said electrodes, a high potential condenser, a source of high potential having one side electrically connected to one of said electrodes and the other side connected to one side of said condenser, and a coupling condenser connecting the other side of said high potential condenser to said second electrode.

26. i In electrical treating apparatus of the type wherein a product to be treated is positioned within a treatment zone and a high potential is impressed across two electrode structures upon the opposite sides of said treatment zone, the combination of, an annular electrode mounted to rotate about a fixed axis, a second electrode spaced from said annular electrode and adapted to cooperate therewith to form a zone for the treatment of materials, a solid dielectric means so mounted that a portion thereof will be between the active discharge surfaces of said electrodes at all times regardless of the relative movement of said electrodes, a high potential condenser, a source of high potential having one side electrically connected to one of said electrodes and the other side connected to one side of said condenser, and a brush connecting the other side of said high potential condenser to said second electrode.

FRANKLIN S. SMITH.

Images