US3244850A - Segmented extended toroidal electrode and process of dielectric heating therewithin - Google Patents

Description

Aprll 5, 1966 J w. MANN ETAL 3,244,850

SEGMENTED EXTENDED TOROIDAL ELECTRODE AND PROCESS OF DIELECTRIC HEATING THEREWITHIN Filed June 5, 1963 ZN VE N T 0B 5 JULIUS W MHNN G302 GE FBUS'SELL m V? 02% a T TOBNEY' United States Patent Wash.

Filed June 3, 1963, Ser. No. 285,086 4 Claims. (Cl. 219-1041) Our invention relates to certain improvements in a process of heating dielectric material by the action of a high frequency alternating current field of force within electrode configurations of a unique type, design and style and consists in construction and arrangement hereinafter described and claimed in the steps hereinafter set forth.

The invention herein disclosed is a concept of dielectric high frequency heating which modifies and improves upon, in certain respects, the disclosures made by us in our Patent No. 2,856,296, issued October 14, 1958, on a Process Of Heating Dielectrics By Extended Toroidal Electrode.

While the disclosures in the above-mentioned patent which recited in its specification and claims a unique and new method of heating dielectric material within the convolutions of an extended toroidal electrode configuration, this invention involves a modification of the philosophy involved with reference to the standing wave patterns and modes resident on the respective toroidal electrode configurations and in the construction of the electrode configuration, which permits greater usefulness and flexibility.

If a toroid is divided at one point and the two ends thus provided are extended so that its axis of its configuration forms approximately a straight line rather than a circle, the toroid then is similar to a helix or wound coil but when connected to a high frequency alternating current generator in a manner described in our Patent No. 2,856,296, or other modifications thereof in our copending application on a Process and Apparatus for Heating Dielectrics in High Frequency Extended Toroidal Electrodes Configurations, Serial No. 271,410, filed April 8, 1963, the said extended toroid becomes in effect an electrode configuration within which dielectric materials may be heated by the high frequency alternating current field of force resident in standing wave modes upon the said extended toroid.

Commonly upon an extended toroidal electrode configuration there may be resident half, full or multiple half standing waves of RF energy at the frequency of the associated electronic generator which is the source of RF energy. We have previously described and claimed means by which half waves or multiples thereof may be made to stand upon such an extended toroidal electrode configuration and have previously described the fact that certain capacity and inductive relationships involving the length of the inductance means employed has finite bearing upon the free space wave length of the associated electronic generator. Also, previously we have described the action of the heating areas, termed K spots, the distribution of the electric and magnetic lines of force and the relationship of desirable standing wave modes to the convolutions of the extended toroid. While these were described in Patent No. 2,856,296, we refer again to the distribution of the electric and magnetic field lines of force in the illustration of FIGURE 3 in this patent. While this distribution mode of the respective lines of force represent two half standing waves resident on the extended toroidal electrode disclosed therein an electrode may be employed with equal satisfactory results when there is resident upon an extended toroidal electrode a quarter, a half wave, a full or multiple half Waves of 3,244,850 Eatented Apr. 5, 1966 high frequency alternating current energy. This can be accomplished physically by designing the confiurations of the toroid so that the inductance and capacity forms a resident for only that configuration of standing wave mode desired in the circumstance.

When using an extended toroidal electrode configuration of the type described in our Patent No. 2,856,296, certain disadvantages become apparent in its operation. For example: as a solid dielectric material, wood, milk, beer, etc., is inserted in one end of the extended toroidal electrode configuration having a full standing wave resident thereon, there is a tendency of the half standing wave on the end in which the load enters to absorb a substantially greater portion of the RF energy than is evidenced in the exit half on which a matching half wave of opposite instantaneous E field charge is resident. In the case of a single or double ender generator being the source of energy under such conditions, the loading of the electronic generator becomes somewhat non-uniform and the leading half wave first experiencing the load may absorb a greater percentage of the energy and load more quickly than the lagging half wave. In some instances, unstable and unwanted modes of wave propagation may thereby be introduced and instabilities created therefrom reflecting back into the operation of the electronic generator. The continuous type of toroid in the extended configuration form therefore is susceptible to some imbalance between two resident half standing waves. Introduction of unbalancing modes when using the continuous inductance type of extended toroidal electrode under certain loading conditions may reqire that adjustments be made during the course of loading and different adjustments during operation and still others upon termination and exit of the materials after passing through the coil.

The novelty of heat treating dielectric material in the type of electrode disclosed in our Patent No. 2,856,296, except as to some detailed and technical disadvantages herein set forth are now known since the issue of the above patent as it described numerous uses and the advantages accruing thereunder.

A co-pending application on a Process and Apparatus for Heating Dielectrics in High Frequency Extended Toroidal Electrodes Configurations, Serial No. 271,410, filed April 8, 1963, describes different types of configurations which make improvements on the types described in Patent No. 2,856,296 with particular emphasis on a non-continuous type of helical coil arrangement.

By the expedient of breaking the continuity of the inductance of the extended toroidal electrode configuration at each point of an occurrence of a voltage antinode (i.e., the high E field charged area of each half standing wave), resident upon an extended toroid configuration stability in the relationship of a half standing wave following has substantially improved. We term the breaking of the continuous inductance of the extended toroidal electrode segmenting. In other words it might be said that on one mode of an extended toroidal electrode configuration where there may be resident two continuously associated half standing waves of RF energy, such half standing waves are segmented by quarter wave increments, the inductance portion of the half wave in each half of the structure becoming two equivalent quarter wave inductances adjacent one to the other. The segmenting of the continuity of the inductance portion of the toroid in the region of the highest E field charge of a half standing wave contributes to the suppression of the propagation of unwanted and unstable modes of oscillation. The segmented type of extended toroidal electrode is not so susceptible to imbalance between two adjacent half standing waves resident upon an extended toroid as it is in the case of a continuous inductance type of extended toroidal configuration. Where high moisture content dielectric loads entering a segmented toroidal electrode at one end and progressively loses moisture as it travels along the axis of the convolutions of the toroid does not de-tune the second half wave portion to so marked a degree as does the entrance of such material to an extended toroidal electrode configuration havinga continuous inductance over a full or a half'wave of equivalent length. Further, the segmented type adjusts itself readily to changes in power input to a load. For example, dyed rayon threads run through the extended toroid in a direction parallel to the axis, which may form substantially a straight line, draws power from the associated high frequency generator in proportion to the rate at which moisture is available for evaporation from freshly dyed threads. Self adjustment of power in proportion to the need' of the load removes the necessity of having automatic compensating equipment readjust tuning upon loading, operation or unloading. Also in contrast to the non-segmented type of electrode configuration, the changes in the rate of power drawn from the generator upon the entrance and exit of dielectric loads reduces the necessity of monitoring and adjusting for changes of tuning controls. The segmented toroid shows evidence of greater stability of positioning in the region of the K spots or areas of highest dielectric heating as described in our Patent No. 2,599,850, issued June 10, 1952, on a Process of Controlling and Placing RF Heat in a Dielectric and also shown in our Patent No. 2,856,296, issued October 14, 1958 on a Process of'Heating Dielectrics by Extended Toroidal Electrode.

The stability of the segmented type of extended toroidal electrode improves the performance of a process for heatingv dielectric materials in a high frequency alternating field of force resident upon an extended toroidal electrode configuration wherein the axis of the convolutions of such extended toroidal electrode forms either a circular pattern or substantially a straight line. Adhesive lines such as in a finger end. joint between two abutting pieces of wood to be jointed together set rapidly in the segmented toroidal electrode and to a faster and a more efiicient degree than a similar adhesive line in materials run through an extended toroidal electrode wherein the convolutions form a continuous inductance length over the length which is the residence of a half, standing wave, or a full standing wave of RF energy.

Other objects and advantages will appear as the specification continues. The novel features of the invention will be set forth in the appended claims.

Drawing For a better understanding, of our invention, reference should be made to the accompanying drawing, forming part of this specification, in which:

FIGURE 1 ilustrates a segmented extended toroidal electrode configuration of the half wave type.

FIGURE 2 illustrates a dual half wave extended toroidal electrode configuration disposed adjacentto each other and in line so that dielectrics can be passed through both coils.

While we have shown only the preferred forms of our invention, it should be understood that various changes, or modifications, may be made within the scope of the annexed claims without departing from the spirit thereof.

Detailed description FIGURE 1 shows an extended toroidal electrode configuration of the half wave type wherein coil L composing convolutions with extremities galvanically connected at points 4 and 5 with a lead 6 that in turn isconnected to an associated means of generating alternating high frequency currents indicated generally at RF. The standing wave mode on this half wave toroidal electrode configuration is illustrated by the fact that dotted line 1 in arcuate form maximizes at the center of the coil. L,

marked E: and minimizes in its standing wave mode at the extremities of coil L, at i The distribution of the electric field of force in its standing wave mode is illustrated only. Not shown is the current component which may be considered out of phase with the electric field, component designated as e and shown by the, arcuate line 1.

It has been described in the earlier part of this specification that segmenting the coil L at the boundary area of the maximum e field charge efiectively separates the coil L into two quarter wave components and this galvanic disconnection of one of the convolutions at the approximate maximum point of e field charge is shown at S. in FIGURE 1.. The physical separation as between the inner convolutions separated at the point S may vary dependent upon the type of load, treated, the'total inductance and capacity relationship desired and the necessity of balancing the components of coil L to resonate at one half wave length to the basic frequency of the associated source of high frequency alternating current, or electronic generator. In this configuration the feed from the RF generator is through a bridle to the extremities of the coil L at 1' field points, namely those which have maximum current and'minimum voltage.

Not shown in FIGURE 1, is the compensating capacity to the surrounding boxv or container which may be varied at will to assist in the facility of tuning.

FIGURE 2 shows dual half wave extended toroidal electrode configurations adjacent to each other and in line to permit the passage through the convolutions of coils L and L of dielectric or other material for heat treatment. Shown in FIGURE 2 is the electric field distribution of dual half waves in a full standing wave system wherein on coil L there resides an electric field charged positive e+ while on its matching coil L resides a half standing wave of electric field charged e. While both of the electric field charges are shown on the tops of thecoils L and L respectively, it should be noted that one or the other usually is 90 out of phase or on the other side of the cycle to its matching mate.

The arcuate line 2 associated with coil L arches from a minimum at points i and i the galvanically connected extremities of coil L (the maximum current charge area) to an e+,, showing the maximum e field boundary area of the half standing wave associated with coil L Thev extremities 7' and 8, respectively, of coil L are connected by a bridle 11 to be the means of joining it to an associated means RF. in FIGURE 2, of generating high frequency alternating currents at a frequency of which coil L will resonate as a half wave. The segmentedportion of coil L is shown at S being illustrative of galvanic discontinuity in a convolution which finds itself at approximately the maximum e field boundaryarea on the electric field charge on coil L in its standing wave mode.

Arcuate dotted line 3 associated wth coil L arches from a minimum at extremities i and i of coil 1. which is the maximum current boundary area for the half standing wave on coil L to a maximum e field charge of. the opposite sign that is found at the same instantaneous moment on. coil L The, arcing or" the dotted line 3 from a minimum on either side to a maximum in the center designated ein. FIGURE 2, shows the standing wave mode distribution of the. electric field charge on coil L while the segmentation of the half wave extended toroidal electrode coil L is shown at S which illustrates. the galvanic discontinuity in a convolution of coil L and finds itself at the approximate maximum e field boundary area of the half standing wave mode resident on coil L The extremities 9 and 10 of coil L are connected by a bridle 12 to an associate means RE.

The invention should not be limited merely to illustrations shown and modes described as the half wave type shown in FIGURE 1 or to the full wave type shown in FIGURE 2, but may be composed of various com.-

aaaaeso binations of convolutions continuous or intermittent with bridles of different varities and kinds, one of which is illustrated in the drawing of FIGURE 2 in our Patent No. 2,856,296. Other configurations which are equally workable are shown in our co-pending application, Serial No. 271,410, describing means ofestablishing half or full wave modes on coils whose extremities are connected in differing ways or not extremity connected and arranged in differing patterns, but having characteristics with reference to field distributions in part or fully parallel to the standing wave field of force illustrated in our Patent No. 2,856,296.

Little further explanation need be spent on a description of the reasons for the improvement of performance of the segmented type extended toroid over the continuous inductance type or other configurations of the extended toroid. The segmentation of an extended toroidal electrode configuration has so markedly added to the efficient performance of dielectric high frequency heating processes in this general type of electrode configuration that there appears no comparison between it and the types previously described by us in our earlier disclosures.

Needless to say the breaking of the inductance component of the extended toroid at the lngh E field charged areas of a half standing wave resident upon the toroid, permits ease of adjustment and confines operations to a single mode which can readily be changed by the introduction of additional capacity in the form of the dielectric load itself or artificial externally applied capacitance without the fear of the standing wave taking on the condition of an unwanted mode.

We have disclosed in our co-pending application, Serial No. 271,410, the method of determining the length through the convolutions of the conducting materials used in this construction of a toroidal or an extended toroidal electrode configuration, whether it be the residence of a half, a full or multiples of half standing waves of RF energy. The formula disclosed for each half wave was the square root of 2 over 2 times the free space wave length equivalent of the operating frequency of the associated means of generating high frequency alternating current with which a particular configuration is associated. It has been pointed out also that if loads of a heavy or concentrated nature such as a tube of water, milk or beer being pasteurized is passed through the convolutions, then the length of the electrode through the convolutions might be reduced slightly from the formula figure, and on the other hand if the load be a very light one such as a damp web of string passed through the convolutions for drying, it would offer a lesser mass load and the length of the convolutions could be increased with stabilizing results. This variation falls, however, within the scope of the formula the square root of 2 times the free space wave length of the associated generator for a full wave electrode and stems from the fact that the load forms in effect a part of the electrode into which the generator looks, to see resonance. When the electrode is cut or adjusted with its load to resonate at the generator frequency, most effective heating and use of generator output is experienced.

In the types of electrodes described in our Patent No. 2,856,296 and the co-pending application, it is a major operation to take out a loop, or a convolution if a heavy load is to be treated, or to add one or more convolutions to the electrode when a light load is to be heated. A distinct advantage, therefore, of the segmented half wave sections lies in the ready adjustment which may be made in the spacing at the segmented or cut convolutions as between abutting ends of what might appear to the generator as two quarters wave helixes the common E field termination of which may be placed closer or farther away as the load dielectrically speaking is increased or decreased. Within reasonable limits the space between the cut or segmented ends of a convolution or the two thereby created interior end convolutions of a half wave configuration is non-critical. Except at the point of segmentation, the helix may preferably compose turns of reasonably consistent pitch, but this is not at all essential in convolution design, nor is strict circularity of helix convolution form essential.

The breaking of the inductance convolution at an E eld does not, however, change the fact that in the case of single half standing waves resident upon an extended toroid, alternate charges of 2+ and ecome to sit on and flow from the boundary area described as the voltage antinodal position of the respective half waves at the points of inductance discontinuity. Some Maxwellian coupling undoubtedly exists in the segmented toroid and adequately substitutes for galvanic continuity in the wave forms total requirement of inductance and capacity. The introduction of dielectric loads to be treated within the segmented toroidal electrode configurations causes no lapse of the segmented electrode configuration into unwanted and undesired modes which would rob the dielectric of the high frequency heating effect of the standing wave field of force;

We have found that by bridling the current antinodal extremities of each respective half wave with a connecting galvanic inductance to complete the resonance boundary for a desired frequency of a half standing wave, facilitates connecting the structure to the feed lines of an electronic generator associated therewith and this has been more fully explained in our co-pending application, Serial No. 271,410. Associating a second half standing wave helix with the first to complete a segmented full wave extended toroidal electrode and likewise bridling the current antinodal extremities of the second half waves residence area, permits easy connection at the i field to an electronic generator of a double ender variety; the bridled i field extremities of the first half standing wave toroid being connected to the one output side and the bridle of a second associated half standing wave extended toroidal configuration connected to the alternate output side of the double ender type generator. Half wave units may also be paralleled or seriesed with no galvanic connection at the point of their closest adjacency.

A generator of the type described as a double ender which may be connected to one or more half wave extended toroidal configurations is described and claimed in our Patents Nos. 2,599,850 and 2,777,022, issued respectively on May 2, 1950 and January 8, 1957, the latter patent being entitled Radio Circuit in Which the Vacuum Tube Fires for Each Alternate Positive Cycle of the Grid Swing. Connecting the electronic generator as described in FIGURE 3, for example of Patent No. 2,777,022 to a segmented extended toroidal electrode configuration can be accomplished by connecting plates 5B (of FIGURE 3, Patent No. 2,777,022) respectively to the bridles connecting the current antinodal areas of two associated half standing wave extended toroidal electrode units; the bridle connecting the first of an association of two such half standing wave extended toroidal electrode configurations to one of the 5B plates in the patent (outlet side) and the second bridle to the alternate 53 plate of the generator.

The half wave electrode may be fed from a single ender generator also, and so no limitation to the scope of our invention is intended by the use of a generator of a single style or type.

The segmented type of electrode helix herein described is novel, has not been previously disclosed in the state of the art, is useful and has commercial value. It permits ease in tuning a load, eliminates the necessity for external means of inductance adjustment and gives greater flexibility to the controls of the attached generator for loading. It relieves the necessity to make constant changes in inductance length, evens out balance problems in a double ender configuration and permits entry and exit of materials with less fear of spurious aaegaso 7 modes being introduced into the system and reflecting back to the generator.

We claim:

1. An extended toroidal electrode configuration having a plurality of convolutions on which the residence of two half standing waves of radio frequency energy are adapted to lie and (a) wherein the continuity forming the convolutions of the said extended toroidal electrode, the axis of which forms substantially a straight line, is galvanically dis-connected at the approximate area of the voltage antinodes of each of the two half standing waves of radio frequency energy resident upon the said full standing wave extended toroidal electrode configuration.

2. The process of heating dielectric materials within the convlutions of an extended toroidal electrode configuration whereupon reside two standing half Waves of radio frequency energy the axis of the iconvolutions of said extended toroidal electrode forming substantially a straight line;

(a) wherein the continuity of the conductor which forms the convolutions of the said extended toroidal electrode is segmented by galvanic discontinuity at the approximate maximum E field charged areas of each of the two saidhalf standing waves of radio frequency energy resident thereupon; and

('b) moving a dielectric within the convolutions for heating it.

3. An extended toroidal electrode configuration having 0 (a) a helix in two identicalparts, each being provided with a plurality of convolutions;

(h) each helix part has a half standing wave of high frequency energy resident thereon when both helix parts are connected to an RF generator; and

(c) wherein that convolution of each helix part closest approximating the position of a maximum E field charge area in each half standing wave, is galvanically disjoined; V g

(d) whereby the frequency of both half standing waves 8 on said helix parts will be the same frequency as that of the RF generator connected to, said helix parts and any dielectric moved through the convolutions of both helix parts willhave less tendency to change the frequency of the half standing Waves from that of said RF generator. I I,

4. The process of heatingdielectric materials within the convolutions of an extended toroidal electrode configuration whereupon reside two standing half waves of radio frequency energy the axis of the conv olutions of said extended toroidal electrode forming substantially a straight line; I r ,v

(a) wherein the-continuity of the conductor which forms the convolutions of the said extended toroidal electrode is segmented by galvanic discontinuity at the approximate maximum E field charged areas of each of the two said half standing waves of radio frequency energy resident thereupon; and

(b) placing a dielectric within the convolutions for heating it.

References Cited by the Examiner UNITED STATES PATENTS 1,572,873 2/1926 Allcutt 13-27 X 2,494,716 1/1950 McMahon et a1. 21981 X 2,495,399 1/1950 Wheeler 343--895 2,506,158 5/1950 Mann et al 21910.41 X 2,599,850 6/1952 Mann et 'al. 219-1041 2,752,472 6/1956 Emerson 2l9-10.79 2,788,426 4/1957 Thompson 21910.79 X 2,793,276 5/1957 Thompson 219 10.81 X 2,856,296 10/1958 Mann et a1. 2l9-10.79 X FOREIGN PATENTS 9,233 9/ 1927 Australia.

ANTHONY BARTI'S, Acting Primary Examiner.

RICHARD M. WOOD, Examiner.

40 L. H. BENDER, Assistant Exziniiner.

Claims (1)

1. AN EXTENDED TOROIDAL ELECTRODE CONFIGURATION HAVING A PLURALITY OF CONVOLUTIONS ON WHICH THE RESIDENCE OF TWO HALF STANDING WAVES OF RADIO FREQUENCY ENERGY ARE ADAPTED TO LIE AND (A) WHEREIN THE CONTINUITY FORMING THE CONVOLUTIONS OF THE SAID EXTENDED TOROIDAL ELECTRODE, THE AXIS OF WHICH FORMS SUBSTANTIALLY A STRAIGHT LINE, IS GALVANICALLY DISCONNECTED AT THE APPROXIMATE AREA OF THE VOLTAGE ANTINODES OF EACH OF THE TWO HALF STANDING

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