US3598951A - Self-excited, self-tuning and self-loading generator in which the load is an inherent part of the tank circuit capacitance and inductance - Google Patents

Abstract

A self-excited, self-tuning and self-loading generator in which the load electrode is an inherent part of the capacity and inductance of the generator tank circuit. The generator is automatically, instantly, and steplessly self-tuning with respect to wide variations in load characteristics. A maximum power input to the load is maintained by the generator and this is in proportion to changes in the loss factor of the load. The generator cannot ''''spill,'''' i.e., detune from the load since the load is an inherent part of the tank circuit.

Description

United States Patent [72] inventor Julius W. Mann 9132 DeKoven Drive, S.W., Tacoma. Wash. 98499 (21 Appl. No. 848,656

[22] Filed Aug.8, 1969 [45! Patented Aug. 10. 197i [54] SELF-EXCITED, SELF-TUNING AND SELF- LOADING GENERATOR IN WHICH THE LOAD IS AN INIIIIRENT PART OF THE TANK CIRCUIT CAPACITANCE AND INDUCTANCE [56] References Cited UNITED STATES PATENTS 1,572,873 2/1926 Allcutt 2l9/l0.75 X 2,453,24! ll/l948 Mann etal i36/l95 2,494,716 l/l950 McMahon etal. 2l9/l0.8l X 2.506158 5/1950 Mann etal 219110.75 X 2,793,276 5/1957 Thompson 2l9/10.81 X

Primary Examiner-J. V. Truhc Assistant Examiner-L. H. Bender Attorney-William R. Piper 7 Claims, 9 Drawing Figs.

[52] U.S.Cl Zl9/l0.75, 2l9/l0,8l [51] lnt.Cl H05b5/00, HO5b9/O4 [S0] FieIdoISearch 2l9/lO.75, 10.8];331/168 Neutral Harrie SELF-EXCITED, SELF-TUNING AND SELF-LOADING GENERATOR IN WHICH THE LOAD IS AN INI'IERENT PART OF THE TANK CIRCUIT CAPACITANCE AND INDUCTANCE BACKGROUND OF THE INVENTION Field of the Invention U.S. Pat. No. 2,453,24] on a composite radio frequency inductance, on which I am ajoint inventor with George F. Russell, is shown as a preferred type of grid coupling sharing a common magnetic sink. Dielectrics could be treated in the gaps C1 and C2 of this patented circuitry configuration, but from a practical standpoint it would not be acceptable for industrial purposes because of a lack of means for controlling the power input to the load and also because of the physical restrictions in coupling to a more or less remote load. After much experimenting I have devised a circuitry configuration that makes the load a part of the tank circuit and this is a prime requisite. I make use ofa pair of condensers, commonly designated as series coupling capacities, and connect the work load, whether dielectric, inductive or radiative, to the output terminals of these series condensers. This completed the highfrequency circuitry configuration of the generator. The loads can be of various types such as solid, liquid or gaseous dielectrics or a mixture of these substances.

Summary of the Invention An object of my invention is to provide a high-frequency circuitry configuration in which the load electrode is an inherent part of the inductance and capacity of the generator tank circuit. A further object is to provide a generator that will automatically, instantly and steplessly be self-tuning with respect to wide variations in the load characteristics, and which will maintain maximum power input to the load in proportion to changes in the loss factor of the load. It is impossible for the generator to spill," i.e. detune from the load since the load is an inherent part of the tank circuit. The load electrodes may be designed not only for treating dielectrics, but they may be used for induction heating or performing as radiating antennae. Because of the simplicity of the circuit elements, the generator is exceptionally efficient. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a pair of Lecher wires terminating in an open circuit and conventionally termed a quarter wave line.

FIGS. 2 and 3 show an oscillatory inductance capacitance system of an equivalent electrical line length to that shown in FIG. 1.

FIG. 4 illustrates the use of conventional high vacuum triode oscillators in the inductance-capacitance circuitry of FIGS. 2 and 3.

FIG. 5 is a schematic showing of the completed circuitry with the work load connected to the output terminals of the series condensers which in turn function so as to make the work load an inherent part of the tank circuit capacitance and inductance.

FIG. 5A shows the optional addition of two parallel inductance loops schematically, these inductances making it possible to broaden the frequency response and frequency control of the load.

FIG. 6 illustrates a parallel inductance loop spanning the series condensers shown in the circuitry configuration.

FIG. 7 shows an induction load applicator connected to the load condenser.

FIG. 8 represents a dipole radiator load termination.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In carrying out my invention I will set forth the evolutionary steps in arriving at my present circuitry configuration. FIG. I is a circuit diagram of a pair of Lecher wires terminating in an open circuit and conventionally termed a quarter wave line.

However, it should be kept in mind that, actually, fractional wave lengths cannot be propagated as such.

The Lecher wires 1 and 2 in FIG. 1 parallel each other and are short-circuited by a wire 3. The arcuate dotted lines 4 and 5, represent the sine wave distribution of voltage which sit" at the instant on the lines 1 and 2 in the form of a stationary wave on each wire propagated by some source of highfrequency energy such as a dip meter adjusted to match the fundamental resonant frequency of the Lecher line. I have indicated the state of the charge at the instant shown by the e+ on the line 1 and by the eon the line 2. An instant later the charges displace.

The solid arrow 6 represents an actual conduction current shown in the conventional manner, i.e. from plus to minus. The current antinode "I" centers on the axis 7 of the neutral plane, so designated in FIG. 1. The feathered arrow 8 indicates a virtual Maxwell current with its virtual antinode 1" also centered on the axis 7 of the neutral plane. This virtual current displacement current exhibits all of the properties of a real galvanic current. Note that the charge displaces from the positive side to the negative side by means of the metallic lines I, 2 and 3 and also spacially in the gap between 2+ and e. The above may be verified by means of a dip meter and standing wave on the line or wire I and the sine wave 5 is likewise a one-fourth full standing wave. A half standing wave spans the gap e-lto ethus completing a full standing wave.

In carrying out step one of the various evolutionary steps to arrive at my present novel electronic configuration, I replaced the open ended termination of the Lecher line, shown in FIG. I, with a lumped capacity equivalent to the stray capacity which, in a manner, had been amputated from the showing in FIG. 1. The result was an oscillatory inductance-capacity system of equivalent electrical line length as shown in FIGS. 2 and 3.

The oscillatory LC system of equivalent electrical line length to the Lecher wire shown in FIG. 1, is shown in FIG. 2. Here the parallel lines or wires 1, and I, are short circuited by the wire I0 and form the inductance portion "I." of the oscillatory LC system of FIG. 2. The lumped capacity is shown at C in FIG. 2. The arrow 11 represents an actual conduction current from the line I, to the line I; and the feathered arrow 12 indicates a virtual Maxwell current in the capacitance C. The current antinodes of the actual and virtual currents will center on the axis 13 of the neutral plane that lies between the two parallel lines I, and 1,.

In case the capacitance is to be variable, the series capacity shown at C1 and C2 in FIG. 3 is preferable to the single capacitance shown at C in FIG. 2 for the reason that a control linkage, not shown, may be attached to the stippled neutral portion of the metallic connector 20 between the series capacities CI and C2, which connection point will be at or near ground potential. The parallel wires I; and I of FIG. 3 are galvanically short circuited by the wire 21 and these three wires form the inductance portion L of the electronic configuration. The arrow 22 represents an actual conduction current from the line 1 to the line 1 while the feathered arrows 23 and 24 indicate the virtual Maxwell currents in the series condensers CI and C2. A neutral plane 25 lies midway between the parallel wires I and I and the current antinode of the actual current between the two wires will center on this plane.

The second step was the addition of means for self-exciting the circuit of FIG. 3. This is accomplished in the electronic configuration shown in FIG. 4. I incorporate two conventional high vacuum triode oscillators TI and T2 in the LC circuitry of FIG. 3, see FIG. 4. It is understood that other types of oscillatory devices can be substituted for the vacuum tube triodes, such as solid state or field effect tubes. The parallel wires 1, and I, of FIG. 3 are crossed, as shown by the wires 1 and 1,, of FIG. 4 and this is done to properly phase the grids with respect to the anodes in the triodes TI and T2. The particular type of inductance L1 illustrated in FIG. 4 is that on which a patent was granted, US. Pat. No. 2,453,24l, on a composite radio frequency inductance, of which I was a joint inventor with George F. Russell. The rectangularly-shaped stippled areas 30 and 31 that are connected to the wires leading from the anodes of the vacuum tubes T1 and T2, and are also connected to the series condensers C I and C2, represent low inductance connections in the condenser circuitry. It is well known that high-frequency displacement currents do not penetrate the surface of a conductor more than a small fraction of an inch. Hence, a low-impedance connection in the circuitry should expose a large area with respect to its cross section. A ribbon or strap of copper or aluminum is far superior to the same cross section in the form ofa wire that is circular in cross section. In FIG. 4 the rectangular stippled areas 30 and 31 represent a ribbon or a plate of copper or aluminum in lieu of a round wire. The ribbon form, besides minimizing the PR losses, also minimizes the inductance residing in the connections involved in the network of lumped capacities the latter as a whole comprising the tank capacity of the oscillator. Wires can be used under certain conditions, but the preferred structure makes use of ribbons or plates 30 and 31.

The system thus far developed as shown in FIG. 4, will oscillate at a frequency f, conforming tlo the formula where L is the inductance mcapacitance. It would be possible to treat dielectrics in the series condensers C1 and C2 of the electronic configuration shown in FIG. 4, but from a practical standpoint, it would not be acceptable for industrial purposes because of the lack of means to control the power input to the load and, further, because of the physical restrictions in coupling to a more or less remote load. Hence, something must be added to satisfy these requirements.

Step three. I found that a pair of condensers, commonly designated as series coupling capacities, fulfills the need. The work load, whether dielectric, inductive or radiative, may then be connected to the output terminals of the series condensers which also isolate the work from the high DC potentials. l have added these features to the high-frequency circuitry configuration of the generator which is schematically shown in FIG. and represents the essential circuitry.

Note in FIG. 5 that the capacity of the LC circuit is com posed of three condensers, i.e. the series coupling condensers C3 and C4, and the dielectric load condenser CL. The condensers C3 and C4 are variable condensers, while the condenser effect of the load condenser CL will vary according to the type of dielectric load received between the two plates P1 and P2 of this condenser. All these condensers C3, C4 and CL are connected in series and, in turn, this series of condensers is in parallel with the variable capacity Ct. Also note that the inductances 1,, and I and the composite inductance L] which span the capacity Ct are dominant factors for controlling the frequency and the frequency spread of the generator.

On the other hand, the capacity variation of any one of the series group of condensers C3, C4 and CL, produces comparatively little change in frequency. In this case, within certain limits, frequency may be restored to some desired constant value by means of varying the terminating capacity Ct up or down as the case may be. Frequency control is arrived at in this manner. The relatively narrow width of the stippled conducting straps l, and 1,, between the series output and the loadreceiving condenser CL, indicate that longer leads or connections to the load may be tolerated, yet the inductance should be kept to a minimum for optimum performance. The termination dielectric load receiving condenser CL in FIG. 5 is especially adaptable for loads such as solid, liquid or gaseous dielectrics, or a mixture of these substances.

Load control. The power input to the load may be controlled by varying the impedance of the series condensers C3 and C4 in FIG. 5. For instance, enlarging the spacing of the series condenser plates reduces their capacitance which results in a relative increase in impedance and this in turn curtails the energy input to the load. Vice versa, energy input to the load may be increased by reducing the spacing between the plates in the series condensers C3 and C4. It is obvious that the gaps between the plates of the condensers C3 and C4 can be increased to a degree which would reduce the energy input to the load condenser CL to practically zero. The voltage gradient in the load condenser approaches zero as the series condensers C3 and C4 approach zero capacity.

The introduction of parallel inductance in a given LC oscillatory system increases the fundamental frequency thereof. Inductances whose magnetic fields do not interact when connected in parallel result in an inductance value less than the least one in the group. Fundamentally, an oscillator, whether mechanical or electronic, involves two states of energy, potential and kinetic. Inductance, i.e. the magnetic field is the kinetic sink of energy and the capacitance, the "potential" sink of energy. The formula 1 f H LC involves the inductance L composing the kinetic sink of the oscillator.

Since L is under the square root radical in the above-mentioned formula, linear changes in L do not result in linear changes in frequency. Assume "c" in the above formula to remain constant, then doubling L" changes the ratio of L to C, and will result in slowing the frequency f by a factor of one over the square root of two, namely l/1.4l. Conversely, cutting the inductance to one-half will increase the frequency by a factor of 1.41. Thus, the introduction of parallel inductance 1 in FIG. 6, which parallels the inductances 50 and 51, provides a means for widening substantially the frequency range of the given oscillator of FIG. 5, changing the L,C ratio up or down.

In the circuitry of FIG. 5, the necessary connections between the various condensers introduced considerable inductance and this sets a ceiling on the frequency ofthe oscillator. The band spread is controlled by means of the variable capacities. Hence, a reduction of L in effect increases the dominance of C. This change in the L,C ratio broadens the control band spread.

Parallel inductance or inductances besides raising the frequency also functions to control within certain broad limits, the voltage gradient in the electromagnetic field of the work condenser CL, see FIG. 5, which is one of the series in the circuitry. This phenomenon may be explained as follows:

In a group of capacities connected in series the lesser one of the group will contain the highest voltage gradient. Hence, if the capacity of the work condenser of FIG. 5 should be large as compared to the series condensers its voltage gradient may be too low to impart much energy to the work load CL. The addition of one or more parallel inductances, such as the loops 40 and 40a in FIG. SA, connected across the strategic points 41 and 410 on the plate P1 and the points 42 and 42a on the plate P1, divides the capacity and such division may even result in the work condenser CL behaving as the least one of the series group. In this manner both frequency response band width and voltage gradient may be controlled within rather wide limits. Although I show only the condenser CL in FIG. 5A with the strategic points 41, 410 on the plate Pl and the points 42 and 420 on the plate P2, it is to be understood that the remainder of the circuitry of FIG. 5 becomes a part of FIG. 5A. It should be kept in mind that since the load capacity is inherent to the tank capacity, then loop 40 in FIG. 5 or loops 40 and 40a in FIG. 5A have the effect of reducing the inductance of the circuitry because of their parallel effect on the whole inherent inductance. The term "strategic points" will be explained hereinafter.

FIG. 6 is similar to FIG. 5 and as stated above shows the addition of the parallel inductance I schematically in the form of a series of loops. The inductance I, is so tailored and positioned as to produce the results described above. The adding of the parallel inductance 1, makes it possible to broaden the frequency response and the frequency control.

Balance In FIGS. 1 to 5 inclusive, a neutral plane is indicated by dotdash lines extending between charges of opposite polarity sitting as it were in stationary wave configuration. If the oscillatory circuitry is symmetrical, the field intensity on each side of the neutral plane will be in balance. Any unbalance will show on the plate current meters, not shown in FIG. 5, of the vacuum tubes T1 and T2. The balance of the electronic circuitry may be controlled by adjusting the relative spacing of the plates in the variable condensers Ct, C3 and C4.

Current antinodes Current antinodes may exist in one of two forms, real and virtual. A real current antinode is associated with a galvanic conductor and is more or less fixed with respect to an established wave length. A virtual current antinode exists in space and may drift more or less to suit changes in the sta' tionary wave patterns. A virtual current, i.e. a Maxwell displacement current in space exhibits all of the characteristics of a real current. A drifting current antinode is essential with respect to the automatic and stepless self-tuning operation of the generator.

Load "spill" Conventional generators, for the maximum transfer of energy from the generator to the load, require that the load be resonant to the generator frequency. If the load drifts off frequency, it detunes and the load spills." My self-tuning and self-loading generator cannot "spill" since the load is inherently a part of the oscillatory tank circuit.

Power supply My oscillatory circuitry is independent of the type of power supply. There are a number of power supplies which could be used to supply energy to the triodes of FIG. 6, such as an electrolytic cell or a battery of such cells, or a raw alternating current with a transformer. In the latter instance the triodes would function as half-wave rectifiers in addition to functioning as oscillators. A single phase full-wave rectifier using mercury vapor or solid state rectifiers could be used. Communications power supplies would require the addition of filters to smooth out the direct current output. My oscillatory circuit does not "care" what sort of power supply is used for exciting it. However, the power supply must suit the type of triode used. FIG. 6 indicates where the positive and negative ter minals of the power supply should be connected in this special case and this is regarded as a sufficient disclosure that some form of power supply is used.

Summary l. The circuit configuration evolves from a simple two wire one-fourth wave Lecher line.

2. The load electrode is an inherent part of the inductance and capacity of the generating tank circuit. Making the load a part of the tank circuit does away with tricky intermediate tuned line lengths and coupled circuits.

3. The generator automatically, instantly and steplessly is self-tuning with respect to wide variations in load characteristics. 4. The generator also maintains automatically, instantly and steplessly maximum power input to the load in proportion to changes in the loss factor of the load.

5. The generator cannot spill" the load since the load is an inherent part of the tank circuit.

6. The load electrodes may be designed for treating dielec tries, for induction heating or as radiating antennae.

7. Because of the simplicity of the circuit elements, the generator is exceptionally efficient. This electronic configuration has been applied to large generators with very exciting results. It even appears that interfering radiation has been reduced very considerably as compared to using standard circuit configurations.

FIG. 5 shows by dotted lines a parallel inductive loop 40 connecting the plates P] and P2 of the load-receiving condenser CL. This loop may be added to raise the frequency of the load and also affects the frequency of the whole to some extent. More than one such inductive loop may be installed if need be as already indicated in FIG. 5A.

A variety of stray field configurations may be substituted for the load condenser CL. In FIG. 7 l illustrate an induction heating applicator Li, which is connected to the plates of the variable load condenser CL.

FIG. 8 represents a dipole radiator load termination D1 and D2 connected to the variable series condensers C3 and C4. This is one means for radiating energy into space for communications and remote control devices using radio waves. Wires may be for ribbon and plate-type interconnections between capacities which compose the capacity of the oscillator provided that their electrical line lengths are relatively short with respect to the wave length of the oscillator.

I have provided a self-excited high frequency oscillator circuit configuration in which the load, whether dielectric, inductive or radiative is an inherent part of the tank capacitance and inductance resulting in a self-tuning, self-loading generator that adjusts automatically and steplessly to changes in the loss factor of the load and/or electrical line length in the circuitry.

An experiment was carried out with the circuitry of FIG. 5 including the plurality of parallel loop inductances 40 and 40a of FIG. 5A, these inductances being connected to the plates PI and P2 of the load condenser CL. The two opposing plates of the load condenser were made 32 feet long and planks 2 inches thick by 12 inches long were fed continuously in the directions of their lengths and along the lengths of the plates P1 and P2. The abutting ends of adjacent planks were finger jointed and an adhesive was applied between the joints which could be set by passing through the field of force existing between the plates.

The continuous flow of planks between the plates presented an unusually long and large work capacity and one which was on the border line with respect to the generator circuitry shown in US. Pat. No. 2,506,158, issued May 2, 1950, on a simple standing wave radio circuit, of which I was a joint inventor with George F. Russell. The new circuitry disclosed in this application was used with astonishing efficiency and simplicity in adapting to changes in load configurations. Different stock was used, including planks of 2 inches by 4 inches; 1 inch by 4 inches; 2 inches by 6 inches; l inch by 6 inches; as well as the 2 inch by 12 inch stock. The experiment using the long electrode plates PI and P2 with the parallel inductance control 1,, of FIG. 6 brought out vividly the importance of this control built into the unique circuitry where the load is an inherent part of the tank. The new circuitry also enables the tackling ofjobs that up to date were impossible to handle with the circuitry of U.S. Pat. No. 2,506,158. The lamination of the huge beams is now possible.

The term strategic points means the selection of points of connection which will orient and result in a configuration whereby inductance or inductances cannot interact with neighboring inductances with respect to their magnetic fields. This is in fact the very definition of parallel inductance. In actual practice, especially ifa work electrode is a complex structure, such strategic connection points may require a cut and try approach to obtain optimum performance.

Iclaim:

I. In combination:

a. an inductance-capacitance self-excited oscillatory circuit including a pair of vacuum tubes, a load condenser, a pair of series output condensers, a lead connecting an anode of one tube with one of the series condensers and placing it in series with one of the plates of the load condenser, and another lead connecting an anode of the other tube with the other series condenser and placing it in series with the other load condenser plate whereby all three condensers are in series with each other; and

b. said oscillatory circuit also including a variable capacity connected in parallel with the pair of series condensers and the load condenser.

2. The combination as set forth in claim 1: and in which a. a parallel inductance spans said series condensers for widening substantially the frequency range of the oscillatory circuit.

In a self-excited oscillator:

a tank circuit including an inductance and a capacitance; and

a load circuit including an inductance and a load condenser, the load condenser forming a part of a series of condensers that are parallel with said tank capacitance and form a seriesparallel capacitance that is spanned by the tank inductance, the tank inductance and the load inductance having a composite center portion whereby the load capacitance of the load circuit becomes an inherent part of the inductance and capacitance of the tank circuit and the tank circuit is automatically, instantly and steplessly sell tuned with respect to wide variations in the load characteristics and is self-loading without spilling the load.

The combination as set forth in claim 3: and in which said series condensers are variable for widening substantially the frequency range of the oscillator for changing the LC ratio up or down.

The combination as set forth in claim 3: and in which said load capacitance includes two load electrodes with at least one parallel inductive loop interconnecting said load electrodes for raising the frequency of the load. The combination as set forth in claim 5: and in which a. a plurality of parallel inductive loops are connected across strategic points of said load electrodes for dividing the capacity of the load electrodes and permit both the frequency response band width and the voltage gradient to be controlled within rather wide limits.

7. In a self-excited oscillator: a. a tank circuit composed of an inductance and a capacitance;

b. a load condenser designed for heating and/or treating dielectric systems, said load condenser being connected in a series of, at least three, condensers to form a series group which in turn is connected in parallel with said dominant tank condenser so that the resulting series parallel group of condensers constitute the total lumped capacitance of the oscillators tank, and said lumped capacitance spans the dominant inductive electrical line length of said tank inductance in which configuration the load becomes an inherent part of the oscillators tank resulting in a self-excited oscillator which adjusts automatically, instantly and steplessly self-tuning with respect to wide variations in load loss factor and dielectric constant without spilling the load.

Claims (7)

1. In combination: a. an inductance-capacitance self-excited oscillatory circuit including a pair of vacuum tubes, a load condenser, a pair of series output condensers, a lead connecting an anode of one tube with one of the series condensers and placing it in series with one of the plates of the load condenser, and another lead connecting an anode of the other tube with the other series condenser and placing it in series with the other load condenser plate whereby all three condensers are in series with each other; and b. said oscillatory circuit also including a variable capacity connected in parallel with the pair of series condensers and the load condenser.

2. The combination as set forth in claim 1: and in which a. a parallel inductance spans said series condensers for widening substantially the frequency range of the oscillatory circuit.

3. In a self-excited oscillator: a. a tank circuit including an inductance and a capacitance; and b. a load circuit including an inductance and a load condenser, the load condenser forming a part of a series of condensers that are parallel with said tank capacitance and form a series-parallel capacitance that is spanned by the tank inductance, the tank inductance and the load inductance having a composite center portion c. whereby the load capacitance of the load circuit becomes an inherent part of the inductance and capacitance of the tank circuit and the tank circuit is automatically, instantly and steplessly self-tuned with respect to wide variations in the load characteristics and is self-loading without spilling the load.

4. The combination as set forth in claim 3: and in which a. said series condensers are variable for widening substantially the frequency range of the oscillator for changing the LC ratio up or down.

5. The combination as set forth in claim 3: and in which a. said load capacitance includes two load electrodes with at least one parallel inductive loop interconnecting said load electrodes for raising the frequency of the load.

6. The combination as set forth in claim 5: and in which a. a plurality of parallel inductive loops are connected across strategic points of said load electrodes for dividing the capacity of the load electrodes and permit botH the frequency response band width and the voltage gradient to be controlled within rather wide limits.

7. In a self-excited oscillator: a. a tank circuit composed of an inductance and a capacitance; b. a load condenser designed for heating and/or treating dielectric systems, said load condenser being connected in a series of, at least three, condensers to form a series group which in turn is connected in parallel with said dominant tank condenser so that the resulting series parallel group of condensers constitute the total lumped capacitance of the oscillator''s tank, and said lumped capacitance spans the dominant inductive electrical line length of said tank inductance in which configuration the load becomes an inherent part of the oscillator''s tank resulting in a self-excited oscillator which adjusts automatically, instantly and steplessly self-tuning with respect to wide variations in load loss factor and dielectric constant without spilling the load.

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