US2620466A

US2620466A - Electromagnetic control device

Info

Publication number: US2620466A
Application number: US165345A
Authority: US
Inventors: Hagen Jerry
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1950-05-31
Filing date: 1950-05-31
Publication date: 1952-12-02
Anticipated expiration: 1969-12-02

Description

Dec. 2, 1952 J HAGEN 2,620,466

ELECTROMAGNETIC CONTROL DEVICE Filed ma 31, 1950 v Summer /5. JERRY HAGEN Gnomeg Patented Dec. 2, 1952 UNITED ELECTROMAGNETIC CONTROL DEVICE Application May 31, 1950, Serial No. 165,345

'7 Claims. (Cl. 323-94) My invention relates to electromagnetic type of control devices and particularly to devices of this general type having electrical signal outputs and employing magnetic fluids as a portion of a magnetic circuit.

The use of magnetic fluids in control devices is a relatively recent advancement in science which has heretofore been applied primarily to the field of clutches and similar devices wherein the magnetic properties of the magnetic fluid alone have been utilized. In the present invention not only the magnetic properties of the fluid are utilized but also its property of electrical conductivity. This new magnetic device comprises a magnetic core structure having a plurality of air gaps therein Within one of which is located a quantity of magnetic fluid. The fluid therein is connected in a series relationship with a load circuit supplied by a signal for energizing the same. A control or energizing winding on the core structure selectively and variably magnetizes the core structure and the fluid in the gap making it conductive to amplify, modulate, or otherwise modify the signal supplied to the load circuit.

It is therefore an object of this invention to provide a new and novel electromagnetic control device utilizing the variable resistance properties of a magnetic fluid for varying an electrical signal output of the device.

It is also an object of this invention to provide a device of the magnetic fluid type which is capable of modulating, amplifying or otherwise modifying electrical signals.

Another object of this invention is to provide in a device of this type a means for retaining the magnetic fluid in an air gap of a magnetic core structure.

A further object of this invention is to provide a device of this type with an improved means for holding the magnetic fluid distributed in the air gap of the magnetic core structure of the device.

till another object of this invention is to provide in a device of this type means for substantially eliminating residual magnetism in the core structure and its effect upon the magnetic fluid in the air gap.

It is further an object of this invention to provide in a device of this type a means for inserting a bias or saturating flux in the core structure of the evice to increase its sensitivity.

Theseand other objects of this invention will become apparent'from a reading of the attached description together with the drawings wherein:

Figure 1 is a schematic disclosure of the magnetic control device of the subject invention shown as a modulator for a D. C. signal in a load circuit connected to the device,

Figure 1A shows in section another arrangement of a container to be positioned in the air gap of the core structure of the device shown in Figure 1 the container positioning a magnetic fluid in the respective air gap of the core structure of the device,

Figures 2, 3 and 4 are schematic disclosures of the same magnetic control device utilizing difierent arrangements of controlling and load signals connected to the device, and

Figure 5 is another modification of the magnetic control device which discloses the use of a biasing magnet in the magnetic circuit of the device.

My invention, which is shown schematically in the drawings, comprises a magnetic core structure Ii] having a plurality of air gaps H, [2 therein. For simplicity, the core structure is shown as a pair of U-shaped core members [3 and M of magnetic material positioned with their bifurcated extremities in near abutting relationship to define the gaps ll, [2 therebetween. A frame 20 of nonmagnetic and nonelectrically conductive material holds the core members I3, [4 in assembled and spaced relationship. It is to be understood that this structure is intended to be illustrative only and that the shape and arrangement of the core members l3, l4 and the frame 28 together with the location of the gaps II and [2 may be varied within the scope of the teaching and operation of this device as will become apparent as this disclosure proceeds.

The core members l3, M at air gap H may be separated by a block of electrical insulating material, the block being indicated at 2!, which block will aid in the spacing of the core members and will also prohibit an electric circuit between the members at this point. However, the air gap H alone may be employed as an electrical insulator when the core members It, It are spaced apart by means of the frame 23.

Within gap i2 formed by core members it, it of core structure it is positioned a quantity of a magnetic fluid indicated at 23, the magnetic fluid being composed of a plurality of magnetic particles suspended in a liquid having an oil base. The fluid 23 may be positioned or held in gap l2 by any suitable means but the magnetic or iron particles Within the gap E2 must be the only electrical conductor across the gap between the core members I3, hi. I have found that containers such as is shown at 25 and 26 in Figure l and 1A respectively are highly advantageous for housing the magnetic fluid and spacingthe core members 23, Id.

Container 25 which is shown in Figure 1 is formed of a plastic or insulating tube 2! into the ends of which copper or iron or other electrical or magnetic material end plates 28 are threaded. Tube 27 has a shoulder or ridge portion 32] on its inner surface which spaces the end plate 28 with respect to the tube 2 The magnetic fluid 23 is added to the container 25 before assembly of the plates 28 on the tube 21 is completed. The container is so positioned between the extremities of core members 13, I 3 forming the gap [2 that the end plates abut the core members and are in magnetic and electrical contact therewith. When iron is used as the material in the end plates 28, these end plates act as a mere continuation of the core members which abut the container 25. Copper or other electrical or nonmagnetic materials are used in the end plates 28 to cut down the eiiect of residual magnetism in the core structure H3 in a Well known manner.

Container 25 which is shown in Figure 1A is similar to the container 25 disclosed in Figure 1 and either may be substituted in the core structure IE shown in Figure 1 or in any of the core structures in the figures later to be described. The container 25 difi'ers from container 25 in that a plurality of layers of cloth 3| or other woven or fibrous nonmagnetic and nonelectrically conductive material is placed in the spacing or opening within the container and in contact with the magnetic fluid 23. This cloth or fabric acts as a wick and tends to distribute the magnetic fluid uniformly within the opening of the container 2% and between the end plates 28 thereof. Such an arrangement tends to guard against settling of the magnetic particles within the fluid which under ideal circumstances remains in suspension in the oil base at all times.

As noted above, the magnetic fluid 23 in gap 12 is also util zed as an electrical conductor connecting the core members 13, i l forming the gap in an electrical circuit 69 to be described below. Connected to the core members l3, Hl adjacent the air gap l2 are a pair of conductors 4i and 42 which lead to the electrical circuit 43 and which is adapted to be connected to an external load, this circuit also being adapted to be energized by a signal source of variable magnitude and phase as will become evident as this disclosure proceeds. In Figure 1, the load or electrical circuit 49 includes the magnetic fluid 23 in gap l2, conductor 6!, a wiper M of a potential divider apparatus the winding d of which is connected in a series relationship with a D. C. battery source it. This electrical load circuit is completed from winding d5 through a load resistor A! and conductor 32 to the fluid 23 in gap I2. A pair of output terminals 58 are connected across the load resistor i? to supply the external load (not shown) with the voltage drop across the resistor ll. Depending upon the type of load employed, the load resistor ll may or may not be included in the load circuit d0. Variations in the signal impressed on load circuit 43 may be had by Varying the position of wiper M on Winding &5.

It is also to be understood that where the core structure H3 is supplied With only one air gap then the conductors to the electrical circuit are to be placed directly in contact with the magnetic fluid, such as being located within the con- 4 tainer holding the same and electrically insulated from the core structure. In this manner the electric circuit can be only completed through the magnetic fluid.

The core structure ill also includes a con trolling winding 52 which winding is positioned on the core structure to be common to both of the magnetic members 53, is such that when the winding is energized the portions of the members 13, M adjacent gap 12 will be energized with opposite magnetic polarities. In Figure 1, an A. C. energizing source is adapted to be connected to the winding 52 which acts as a controlling or magnetizing winding for the core structure it. The alternating flux set up in core structure it] due to the energization of coil 52 from the A. C. source magnetizes the core members !3, I4 and hence the magnetic fluid 23 in gap I? with alternating magnetic polarities thereby causing the magnetic particles in the fluid to align and disalign with each reversed or alternation of current flow providing simultaneously an electrical conductor across the gap 12. As the particles in the fluid align under the influence of the magnetic field the resistance of the conductor formed thereby decreases permitting increased current flow in the load circuit ii! connected in series therewith. In this manner a chopped or pulsed or modulated direct cur rent signal will flow into the load circuit 69 and the voltage drop across the resistor M takes on a modulated wave form which will be impressed across the output terminals 53.

In Figure 2 is shown another embodiment of the invention utilizing the same core structure Ill as that employed in connection with Figure l and discussed above. For simplicity the details of the core structure it and the frame 26 which positions the same are omitted in the discussion and inthe drawings but it is to be understood that they are to be included with this embodiment. In Figure 2 there is shown the core members I3, I4 With the air gaps H and i2 formed therebetween, the controlling Winding 52 mounted on the core structure It and the container 25 positioned in air gap I2 to house the magnetic fluid 23. This embodiment utilizes a somewhat difierent type of D. C. signal supply which is adapted to be connected to the load circuit as and in series with the fluid 23 in gap l2. This D. C. signal source comprises a bridge type of supply which includes a tapped resistor 55 conadapted to be connected to an A. C. source but a half wave rectifier 69 is included in this energization circuit to modify the controlling current in a manner to be later described. 'The pulsed A. C. supplied to the energizing winding due to the half wave rectifier 69 causes a pulsed unidirectional flux flow in the magnetic core structure It] and variable unidirectional magnetic polarities across the gap I2. This pulsed magnetization similarly magnetizes the particles in the magnetic fluid 23 to make and break the load circuit at the air gap E2. The output across the load resistor 41 or at the terminals 59 will thereby be .a modulated D. C. .of the same frequency as the frequency .of the AC. input to coil-52.

The disclosure of Figure .3 also employs the same magnetic core struc'tureas that .shown in the device of Figure :1,.hence the details of that portion of the circuit will .be :ornittedhere. The load circuit 10 connected in series with gap [2 and across the load terminals 50 is substantially the same as the load circuit 40 employed in connection with Figure 2 except that the signal source is energized by an alternating current source of power. Similarly the energizing or controlling winding 52-onthe core structure It) is adapted to be energized bya selectivel variable D.-C. source of power. Theoutput of this'circuit is an amplification of the A. C. supply or signal impressed on the load circuit 4'8 depending upon the variation in magnitude'of .the energizing currentsupplied to winding:52.

In Figure 4 there is shown another embodiment of this device in which the core structure is similar to the embodiments described above. For this reason the details of the core structure are omitted here. acts as a mixer or modifier of alternating load signals. The load resistor 4'1 and magnetic fluid 23 are connected in series with an alternating current source of power omitting any bridge arrangement. put circuit which includes the conductor 4! connected to the alternating source, core member 13, the magnetic fluid 23 in gap l2, core member l4, conductor 42, and load resistor 41 to a ground connection 6! for the return side of the A. C.

source. The output terminals or load terminals 50 are as before connected across the load resistor 4! but the load resistor 41 may be omitted if desired. The alternating signal impressed on this load circuit 80 and across the resistor 4? will be modified by the frequency of the A. C. supply energizing coil 52 mounted on core structure ill. As is apparent from the drawing, the alternating magnetization of core structure due to the magnetization of the magnetic particles of fluid 23 makes or breaks the electrical conductor formed at the air gap 12 permitting current to flow in the load circuit 89 only during periods when the load circuit is completed.

The disclosure of Figure is another embodiment substantially the same as that disclosed in Figure 2 employing a bridge type D. C. signal load circuit 40 and a rectified controlling input to the winding 52 mounted on core structure ill. of Figure 2 in that it includes a U-shaped permanent magnet 65 the extremities of which are positioned adjacent the core members l3, l4 bridging the gap ii in which the magnetic fluid 23 is located. A magnetic flux created by the permanent magnet 65 overcomes the initial permeability of the magnetic circuit formed by core structure It and magnetic fluid 23 tending to saturate this portion of the magnetic circuit and increase the sensitivity of the device. The pulsating current flow in coil 52 is in such a direction as to be additive with the permanent magnet flux in aligning the particles of the magnetic fluid. The permanent magnet also serves an additional purpose in that its strength is chosen to keep the magnetic particles partially aligned in the air gap l2 thereby aiding in keeping the particles distributed in the air gap and in suspension in the fluid.

Magnet 65 further operates in the same man- This particular embodiment This arrangement provides an out- This disclosure Varies from the disclosure ner as rectifier 60 in'that its unidirectional flux aids and opposes the alternating flux from an unrectified .-A. C. input to coil 52 such that .the load current willh'avethe same .frequencyas the controlling input signal. Therefore magnet may sometimes be used to replacerectifler B0.

Numerous objects and advantages of myinvention have been set .forth above .in the foregoing description together with details of structure and function of the inventioniand the novel features thereof are pointed .out in the appended claims. These disclosures, however, are intended to be illustrative only and Imay make changes in details (especially in matter of shape, size vandarrangement of parts) within the principle of the invention to the full extentindicated by the broad generalmeaning of the terms in which the appended claims are expressed.

I claimas my invention:

1. In a device of the class describeda magnetic core structure having a pair of fixed air gaps therein, a container of electrically insulating material having electrically conductive end plates positioned in one of said air gaps :with said end plates abutting said core structure a plurality of magnetic particles suspended in a fluid and positioned in said-container, means included .in said container adapted to hold said magnetic particles in a dispersed relationship, electrical circuit means adapted to be energized from an adjustable source of power and including an output circuit, said electrical circuit means being connected in series'with said one of said air gaps, andmeans for magnetizing said magnetic core structure such that portions of said structure on either side of said one ofsaid air gaps are polarized with magnetic polarities of varying magnitudes.

2. In a device of the class described, a magnetic core structure having a pair of fixed air gaps therein, a container of electrically insulatin material having electrically conductive end plates positioned in one of said air gaps with said end plates abutting said core structure, a plurality of layers of nonmagnetic and nonelectrically conductive fibrous material positioned in said container, a plurality of magnetic particles suspended in a fluid and positioned in said container being held in a dispersed relationship by said fibrous means, electrical circuit means adapted to be energized from an adjustable source of power and including an output circuit, said electrical circuit means being connected in series with said one of said air gaps and means for magnetizing said magnetic core structure such that portions of said structure on either side of said one of said air gaps are polarized with magnetic polarities of varying magnitudes.

3. In a device of the class described, a magnetic core structure having a plurality of fixed air gaps therein, a plurality of magnetic particles suspended in a fluid and positioned in one of said air gaps, electrical circuit means connected in a series relationship with said one of said air gaps and having output terminals adapted to be connected to an external load, means mounted on said core structure for magnetizing said core structure such that portions of said structure on either side of said one of said air gaps are polarized with magnetic polarities of varying magnitudes, and a magnetic biasing means of predetermined polarity and magnitude positioned adjacent said portions of said core structure forming said one of said air gaps.

4. In a device of the class described, a magnetic core structure having a plurality of fixed air gaps therein, a plurality of magnetic particles suspended in a fluid and positioned in one of said air gaps, electrical circuit means connected in serie relationship with said one of said air gaps and having output terminals adapted to be connected to an external load, means mounted on said core structure for magnetizing said core structure such that portions of said structure on either side of said one of said air gaps are polarized with magnetic polarities of varying magnitudes, and a U-shaped permanent magnet of fixed polarity and magnitude positioned adjacent said portions of said core structure forming said one of said air gaps.

5. In a device of the class described, a magnetic core structure having a plurality of fixed air gaps therein, a plurality of magnetic particles suspended in a fluid and positioned in one of said air gaps, electrical circuit means connected in a series relationship with said one of said air gaps and having output terminals adapted to be connected to an external load, means mounted on said core structure for magnetizing said core structure such that portions abutting said portion of said core structure ad- 5 jacent said one of said air gaps.

6. In a device of the class described, a magnetic core structure having at least one air gap therein, a plurality of magnetic particles suspended in a fluid positioned in said air gap, electrical circuit means including an output resistor adapted to be energized from an adjustable source of power, said circuit being connected to said magnetic particles in said air gap, means mounted on said core structure adapted to energize said core structure and thereby magnetize said particles in said air gap, and a magnetic biasing means of predetermined polarity and magnitude positioned adjacent to portions of said core structure forming said air gap.

7. In a device of the class described, a magnetic core structure having a pair of air gaps therein, a container of electrically insulating material having electrically conductive end plates positioned in one of said air gaps with said end plates abutting said core structure, a plurality of magnetic particles suspended in a fluid and positioned in said container, electric circuit means adapted to be energized from an adjustable source of power and including an output circuit, said electrical circuit means being connected in series with said one of said air gaps, winding means mounted on said core structure adapted to be energized by a rectified alternating current signal, and a U-shaped permanent magnet of fixed plurality and magnitude positioned adjacent said portions of said core structure forming said one of said air gaps.

JERRY HAGEN.

REFERENCES CITEB The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 774,922 Troy Nov. 15, 1904 2,500,953 Libman Mar. 21, 1950