US3218545A - Mechanical saturable reactor - Google Patents

Description

Nov. 16, 1965 A. E. FLANDERS ETAL 3,213,545

MECHANICAL SATURABLE REACTOR 3 Sheets-Sheet 1 Filed Nov. 16. 1961 INVENTORS ANDREW E. FLANDERS 8:

JOSEPH MONTNER ATTORNEY Nov. 16, 1965 A. E. FLANDERS ETAL 3,213,545

MECHANICAL SATURABLE REACTQR Filed Nov. 16, 1961 3 Sheets-Sheet 3 INVENTORS ANDREW E. FLANDERS a JOSEPH MONTNER BY 9 a.

A RNEY United States Patent 3,218,545 MECHANICAL SATURABLE REACTOR Andrew E. Flanders, 257 Hickory Ave., Pomona, Calif., and i losepl1 Montner, 9242 Andasol Ave., Northridge, Cali Filed Nov. 16, 1961, Ser. No. 152,865 8 Claims. (Cl. 323-90) This application is a continuation-in-part of application Serial No. 639,332, filed February 11, 1957, now abandoned, similarly entitled, and assigned to the assignee of this application.

This invention relates generally to mechanical saturable reactors for use in electrical signal control or as electromechanical transducers; more particularly, it relates to a mechanical saturable reactor wherein an output voltage is varied according to the rotational position of a rotor.

Heretofore, various electromechanical and other transducers, together with their associated amplifiers, have generally been used to drive the control windings of conventional saturable reactors. Rheostats and variable autotransformers have also been used to control the power delivered to a load. Such devices introduce contact and resolution problems. Variable auto-transformers produce shorted-turn circulating currents.

Circuit control devices of the prior art have also employed sliding electrical contacts, which are characterized by such contact problems as noise, sparking, pitting, wear, and chatter under adverse environmental conditions. In electromechanical transducer applications, mechanical movements have been detected by various types of transducers, including otentiometers, and the responsive electrical voltage is fed to a grid of a vacuum tube. As is well known, vacuum tubes introduce a high probability of failure. Conventional wire wound or carbon potentiometers and inductive potentiometers do not of themselves provide high power output or wide power range.

In contrast with the prior art, the mechanical saturable reactor of the present invention inherently provides wide power range. It does not necessarily require vacuum tubes or similar amplifying components. It is not subject to contact and resolution problems and does not have shorted-turn circulating currents. It does not require the use of rheostats or transformers in delivering power to a load, but delivers it directly to the load.

Saturable reactors of the prior art used for voltage control have employed controllable D.C. sources for varying the magnetization of cores around which are disposed coils connecting an AC. source to its load. In the case of the present invention, control is accomplished mechanically and no D.C. source nor means for varying D.C. control current is required.

It is therefore an object of the present invention to provide an improved saturable reactor which does not require a variable D.C. magnetization source.

It is an object of the present invention to provide a circuit control device which is free of problems associated with sliding electrical contacts, such as noise, sparking, pitting, poor resolution, and wear.

It is an object of this invention to provide a mechanical saturable reactor wherein mechanical movement is translated directly into useful electrical output.

It is another object of the present invention to provide a mechanical saturable reactor :having linear and nonlinear response for selective operation.

It is another object of this invention to provide a mechanical reactor wherein the effective core cross-sectional area of a magnet core and the saturation flux density therein are selectively variable and control a useful electrical output.

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It is a further object of this invention to provide a sensitive circuit control device of simple design, which is composed entirely of passive elements; which occupies a minimum of space, and which is inexpensive to fabricate.

It is a further object of the present invention to provide a mechanical saturable reactor which is dependable and relatively trouble-free under adverse service conditions.

Other objects and features of the present invention will become apparent to those skilled in the art from a con sideration of the following description, the appended claims, and the accompanying drawings in which:

FIGURE 1 is a perspective view of a preferred embodiment of a mechanical saturable reactor according to the present invention;

FIGURE 2 is a perspective view, partially in section, of a modified mechanical saturable reactor according to the present invention;

FIGURE 3 is a perspective view, partially in section, of a third embodiment of the present invention;

FIGURE 4 is a graphical representation showing core magnetization as a function of magnetizing force under certain conditions;

FIGURE 5 is a graphical representation showing certain load voltages as function of the angular disposition of the rotor of a mechanical saturable reactor of this invention;

FIGURE 6 is a schematic diagram of the electrical circuitry of the embodiment of the present invention shown in FIGURE 1; and

FIGURES 7 and 8 are schematic diagrams showing exemplary circuits with which the device of the present invention may be utilized.

Referring to the drawings, a preferred embodiment of the present invention is shown in FIGURE 1 as including a coil or winding 11 wound in conventional manner around a generally C-shaped core member 12 of magnetizable material, confronting pole portions 13 and 14 of which define a nonmagnetic gap. The end portions of the nonmagnetic gap, defined by parallel confronting faces of pole portions 13 and 14, are occupied by nonmagnetic spacers 16 and 17, as shown. The central major portion of the nonmagnetic gap has a generally circular configuration defined by curved surfaces 18 and 19 of pole portions 13 and 14. Magnetic rotor 21, having a cylindrical configuration complemental with this circular gap configuration, is mounted on shaft 22 for rotation in the gap. AC. voltage is applied across coil 11 by generator 23 to produce magnetic flux in core 12. Shaft 22 may be rotated manually or it may be rotated continuously by motor 25. The rotational position of shaft 22 may be made responsive to an external mechanical position or movement for control or measurement purposes.

In the embodiment shown in FIGURE 1, rotor 21 is preferably constructed of anisotropic material. The material may be one of the grain-oriented iron alloys known by such trade names as Silectron, Hipersil, Trancor, Corosil, Deltamax, Permeron, Permenorm, Orthonol, or Orthonik. This material may be of the type disclosed in the patents to Holst et al., Number 2,147,791, issued February 21, 1939 and to Bitter, Number 2,046,717, issued July 7, 1936. The magnetization characteristics of such materials vary with angular position in a magnetic path. For a given magnetizing force, a rotor of such material will accommodate or hold differing maximum amounts of flux depending upon its rotational position. The flux density required to saturate the rotor magnetically will thus vary with angular displacement. The graphical representation of FIGURE 4 shows magnetization curves for different angles of rotation. For example, at zero degrees, herein defined as the rotor position which places the direction of greatest magnetization of rotor 21 in alignment with the magnetic path through the core and the nonmagnetic gap, a flux density of more than 15 kilogauss is produced by a magnetizing force of 1.0 oersted. At a position 20 removed from the direction of greatest magnetization, a flux density of approximately 13 kilogauss is produced by the same magnetizing force, and at 45, the flux density with the same magnetizing force is only 10 kilogauss.

Rotation of rotor 21 varies the effective cross-sectional area of the metallic magnetic path for the magnetic flux produced in core 12. That is, with the anisotropic material so oriented that the direction of greatest magnetization of the rotor is aligned with the magnetic path through the core, the effective cross-sectional area for magnetic conduction is the greatest. As rotor 12 is rotated from this zero position, the effective cross-sectional area is progressively reduced until the anisotropic material is oriented approximately 45 to 90 from the position of maximum magnetization.

Rotation of rotor 21 varies the voltage across winding 11. This voltage, which is the voltage the coil can hold or absorb, is governed by the basic relation where E is the RMS voltage across winding or inductor 11, F is the frequency of the AC. line voltage, N is the number of turns of winding 11, A is the effective crosssectional area of rotor 21, and B is the flux density in core 12.

Reduction of the effective cross-sectional area of the core or rotor and consequent reduction of flux density in core 12 reduces the voltage across coil 11. Rotation of rotor 21 changes its effective cross-sectional area, producing changes in the flux in the core. When the rotor is in its zero" position, as hereinbefore defined, it presents maximum effective cross-sectional area to flux in core 12 and exhibits maximum flux density capacity; hence, the voltage across coil 11 will be greatest. As rotor 21 is rotated from this position, the effective cross-sectional area of the core is progressively reduced and the flux density in core 12 is accordingly reduced. The voltage across coil 11 is thereby reduced, in accordance with the above equation. It is assumed in the foregoing discussion that the magnetizing force (in oersteds) is constant throughout rotation of rotor 21.

In the circuit shown in FIGURE 6, where coil 11 is serially connected between generator 23 and load 24, changes in voltage across coil 11 produce inverse changes in the voltage across load 24, because the load voltage represents the difference between the generator voltage and the voltages held or absorbed by the coil. FIGURE 5 shows the voltage 15,, across load 24 as a function of the angle of rotation of rotor 21. Voltage E is determined by three factors, the angular position of rotor 21, the low flux density permeability of core 12 and rotor 21, and the small air gap between core and rotor. In FIGURE 5, E the voltage drop across load 24, represents the summation of the curves reresented by E and E E represents the voltage output across the load as a function of the angle of rotation of rotor 21, as developed from the B-H magnetization curve relationships shown in FIGURE 4. E represents the combined effect of the small air gap and low fiux density permeability. With a uniform air gap a certain maximum inductive reactance is established, and thus a finite minimum output voltage appears at the load. Because the low level flux density permeability varies slightly with changing angle, the E curve is shown with a slight slope.

By way of example, and not by way of limitation, the Curve E of FIGURE specifically represents the voltage across a load of 60 ohms produced by a saturable reactor (the B-H curves of which are shown in FIGURE 4) connected to a 100 volt, 60 cycle, AC. voltage source. It is obvious that the minimum and maximum amplitudes of this curve and its slope at different points are matters of design and that they will vary according to such design factors as the particular reactor material selected and the circuit components utilized. As shown in FIG- URE 5, load voltage E decreases from 120 to 180 (60 to 0") of rotor rotation and increases from 0 to 60 of rotation. Although not shown in FIGURE 5, this voltage drops somewhat between 60 and of rotation and increases from 90 to declining again from to of rotation, all in accordance with the magnetization curves of FIGURE 4.

Referring to FIGURE 2 of the drawings, there is shown a second embodiment of the present invention wherein 2 rotors 21 and 21a are mounted on a common shaft 22. Rotor 21 is disposed in the nonmagnetic gap defined by a first magnetic core 12, and rotor 21a is correspondingly disposed in the nonmagnetic gap defined by a second magnetic core 12a. The rotors are angularly so disposed with relation to each other on shaft 22 that their respective direction of maximum magnetization are disposed at a relative angle of somewhat less than 90. Dual electrical outputs may be produced. In order to minimize the reluctance of the nonmagnetic gaps between rotors and cores, the spaces between the rotors and the pole portions of the cores may be filled with powdered iron lubricated with silicon oil. In order to retain the fluid within the air gaps and within the device shown in FIGURE 2, a slightly cupped pressure plate 29, constructed of nylon or Teflon, is employed.

Referring to FIGURE 3, there is shown a third embodiment of the mechanical saturable reactor of the present invention, wherein a rotor 21b has the configuration of a frustrum of a cone and wherein a cam 31 is mounted with rotor 21!) on shaft 22, as shown, so that it rides over projection 32 on frame 33. The nonmagnetic gap defined by core 12 has a configuration adapted to accommodate rotor 21b. This configuration facilitates reduction of the air gap between core 12 and rotor 21b by permitting the rotor to seat in the pole portions of core 12. This minimizes the reluctance between core and rotor. Cam 31 provides means for axial movement of rotor 21b simultaneously with its rotation. The axial movement permits linear insertion or withdrawal of the rotor into or out of the nonmagnetic gap of core 12. Obviously, the rate of withdrawal in relation to rotational speed is a matter of design. It will be observed that in the case of this embodiment both the effective cross-sectional area and the actual physical cross-sectional area of the rotor in the gap may be varied to vary the value of A in the basic equation hereinbefore set forth. By varying the rate of withdrawal or insertion of rotor 21b from or into the nonmagnetic gap and by simultaneously varying the rotational position of rotor 21b, the curve representing load voltage as a function of rotational position of the rotor may be made linear or nonlinear depending upon the design of cam 31. Curve E in FIGURE 5 represents such a linear curve and is produced by linear withdrawal of the rotor from the core. Curve E represents the voltage across the load which is produced by simultaneous rotor withdrawal and orientation change when an air gap of 1 mil or less was varied only slightly by means of cam 31.

FIGURES 7 and 8 show illustrative circuit arrangements for control circuitry with which the mechanical saturable reactor of the present invention may be utilized.

In FIGURE 7 the output voltage from the saturable reactor is rectified through D.C. bridge 26 to provide bias for magnetic amplifier 27 which supplies voltage to load 24. In FIGURE 8 energy source 23 excites the divergent balanced network to provide a positive or negative D.C. output between terminals 35 and 36 or to provide a push-pull D.C. output at terminals 34, 35, and 36. The embodiment of the present invention shown in FIGURE 2 is adapted for use in this circuit. The

'output supplied to one mixing resistor will increase with one direction of rotation while the output to the other mixing resistor will decrease. The net effect is increased voltage output of one polarity with rotation in a given direction. Upon rotation in the opposite direction, a decrease in output of the original polarity or an increase in output of the opposite polarity occurs. In this embodiment, nonmagnetic spacers 28 are provided in order properly to constrain the flux in cores 12 and 12a.

Those versed in the art will realize that the mechanical saturable reactor of the present invention is adapted for many diversified and useful applications. For example, as shown schematically in FIGURE 1, it is adapted for use in connection with a high power acoustical warning device (siren). A high frequency carrier voltage is supplied to the coil 11 of a saturable reactor, the coil being in series with speaker 37, and rotor 21 is rotated continuously by motor 25 to modulate the output to the speaker. A simple direct device having very few components is thus provided. The device of the present invention is also adapted to function as an electromechanical transducer to provide linear or nonlinear outputs or combinations of both. It may be used for tuning an inductor over a narrow range or, with proper filtering, it may be utilized in the production of musical tones.

While certain .preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims:

What we claim is:

1. A mechanical saturable reactor comprising an electromagnetic core having a pair of confronting pole portions defining a constant air gap, a coil wound around said core, a rotor of grain-oriented anisotropic material having a rectangular hysteresis loop which will saturate in different angular positions mounted for rotation Within said air gap, said rotor having a circular configuration, means for increasing the permeability of the Portion of said air gap not occupied by said rotor comprising small magnetic particles and silicon oil within said gap, and sealing means for retaining said particles and said oil within said gap.

2. In an alternating voltage circuit having an alternating voltage source and electrical means connected across said source constituting a load, a voltage control device comprising a core of magnetizable material having a pair of pole portions defining a constant nonmagnetic gap, a rotor of rectangular hysteresis loop magnetic material having preferred directions of magnetization positioned within said air gap and complemental therewith, whereby said rotor will saturate in different angular positions, a coil wound around said core and connected in circuit with said alternating voltage source and said load, the number of turns of said coil being such as to produce rotor saturation during each half cycle of the alternating voltage, and means for turning said rotor to determine the instant during each such half cycle at which said rotor becomes saturated to govern the voltage maintained across said winding.

3. For use in an alternating voltage circuit having an alternating voltage source and electrical means connected across said source constituting a load, a voltage control device comprising a circularly shaped rotor having preferred directions of magnetization, whereby it will saturate in different angular positions, a core of magnetizable material having pole portions defining a constant air gap, said pole portions having curved confronting surfaces corresponding with the shape of said rotor, a coil wound around said core and connected in circuit with said alternating voltage source and said load, the number of turns of said coil being so related to the alternating voltage frequency as to produce rotor saturation during each half cycle of the alternating voltage, and means for turning said rotor to determine the instant during each such half cycle at which said rotor becomes saturated to govern the voltage drop across said winding.

4. For use in an alternating voltage circuit having an alternating voltage source and electrical means connected across said source constituting a load, a voltage control device comprising a core of magnetically saturable material having a constant air gap therein, a cylindrical element of magnetic material having preferred directions of magnetization supported within said air gap for rotational movement, whereby it will saturate in different angular positions, an alternating voltage winding wound around said core and connected in circuit with said alternating voltage source and said load, the number of turns of said coil being such as to produce rotor saturation during each half cycle of the alternating voltage, and mechanical means for selective rotational positioning of said element to determine the instant during each half cycle of the alternating voltage where the rotor becomes magnetically saturated to control the voltage maintained across said winding in accordance with the basic relation 1.4 lE=21rFNAB X10- where E is the RMS equivalent of the average voltage across said Winding, F is the frequency of the alternating voltage, N is said number of coil turns, A is the effective cross-sectional area of said element, and B is the flux density in said core.

5. For use in an alternating voltage circuit having a voltage source and electrical means connected across said source constituting a load, a voltage control device comprising a core of magnetic material having an air gap therein, a member of magnetic material having preferred directions of magnetization supported for rotation within said air gap and arranged for translational movement with respect thereto, an alternating voltage winding wound around said core and connected in circuit with said voltage source and said load, means for rotating said member to produce voltage variations across said Winding, and means for producing translational displacement of said member to modify said voltage variations.

6. For use in an alternating voltage circuit having a voltage source and electrical means connected across said source constituting a load, a voltage control device comprising a core of magnetic material having an air gap therein, a member of magnetic material having preferred directions of magnetization supported for rotation within said air gap and arranged for translational movement with respect thereto, an alternating voltage winding wound around said core and connected in circuit with said voltage source and said load, means for rotating said member to produce voltage variations across said Winding, and means for effecting linear voltage variations by predetermined translational displacements of said member.

7. A high power acoustical generating system comprising a high frequency carrier source, a speaker, and a mechanical saturable reactor serially connected thereto, said reactor comprising a magnetic core having pole portions defining an air gap, a coil wound around said core, a rotor of anisotropic material saturable in different angular positions and mounted for rotation within said air gap, and means for continually rotating said rotor.

8. A mechanical saturable reactor comprising a first magnetic core having pole portions defining a first air gap, a first coil wound around said first core, a first rotor of anisotropic material Within said first air gap, a second magnetic core having pole portions defining a second air gap, a second coil wound around said second core, a second rotor of anisotropic material within said second air gap, said second core being so positioned relative to said first core that both said rotors are in axial alignment, a common shaft connecting said rotors for rotational movement, and nonmagnetic spacers between said cores, coils and rotors to constrain flux in said first core and in said second core.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Thomson 336-135 X Hellmund 323-90 X Clough 323-89 Bitter 148-111 Bozorth et a1. 148-120 Wilkinson 340-384 Candy 336-135 8 6/1951 Scharschu 336-218 X 4/1954 Schwig 323-89 10/1956 Side 336-135 X 10/1957 Akeley 310-162 9/ 1959 Bozorth 336-218 FOREIGN PATENTS 5/ 1941 Germany.

LLOYD MCCOLLUM, Primary Examiner.

Claims (1)

1. 2. IN AN ALTERNATING VOLTAGE CIRCUIT HAVING AN ALTERNATING VOLTAGE SOURCE AND ELECTRICAL MEANS CONNECTED ACROSS SAID SOURCE CONSTITUTING A LOAD, A VOLTAGE CONTROL DEVICE COMPRISING A CORE OF MAGNETIZABLE MATERIAL HAVING A PAIR OF POLE PORTIONS DEFINING A CONSTANT NONMAGNETIC GAP, A ROTOR OF RECTANGULAR HYSTERESIS LOOP MAGNETIC MATERIAL HAVING PREFERRED DIRECTIONS OF MAGNETIZATION POSITIONED WITHIN SAID AIR GAP AND COMPLEMENTAL THEREWITH, WHEREBY SAID ROTOR WILL SATURATE IN DIFFERENT ANGULAR POSITIONS, A COIL WOUND AROUND SAID CORE AND CONNECTED IN CIRCUIT WITH SAID ALTERNATING VOLTAGE SOURCE AND SAID LOAD, THE NUMBER OF TURNS OF SAID COIL BEING SUCH AS TO PRODUCE ROTOR SATURATION DURING EACH HALF CYCLE OF THE ALTERNATING VOLTAGE, AND MEANS FOR TURNING SAID ROTOR TO DETERMINE THE INSTANT DURING EACH SUCH HALF CYCLE AT WHICH SAID ROTOR BECOMES SATURATED TO GOVERN THE VOLTAGE MAINTAINED ACROSS SAID WINDING.

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