US3131338A

US3131338A - Rotary solid dielectric variable condenser

Info

Publication number: US3131338A
Application number: US21065A
Authority: US
Inventors: James E Howell
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-04-08
Filing date: 1960-04-08
Publication date: 1964-04-28
Anticipated expiration: 1981-04-28

Description

April 28, 1964 J. E. HOWELL 3,131,338

ROTARY soun DIELECTRIC VARIABLE CONDENSER Filed April 8. 1960 FIG.2.

JAMES E. HOWELL.

IN VEN TOR.

United States Patent ()fiiice 3,131,338 Patented Apr. 28, 1964 3,131,338 RGTARY SQLED DIELECTREQ VARIABLE CONDENSER James E. Howell, Huntsvilie, Ala, assignor to the United States of America as represented by the Secretary of the Army Filed Apr. 8, 1960, Ser. No. 21,065 6 Claims. (Cl. 317-253) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

The present invention relates to a solid dielectric variable condenser wherein fluids such as air, moisture, etc., are excluded from the interior of the condenser. The exclusion of fluids from the electric field of a condenser is of importance where conditions are such that ionization of a fluid within the condenser may occur. This ionization of fluid in a condenser takes place much more readily when the potential across the condenser is relatively high, or when the fluid pressure and density is low, e.g., at high altitudes. Both of these conditions are present in guided missile operations where high power requirements with corresponding high voltages are necessary in missiles traveling at high altitudes. In such applications a condenser must be free of all external fluids and it also must be variable to facilitate minor adjustments.

It is therefore, an object of the present invention to provide a condenser which fulfills all of these requirements and fully overcomes the noted problem of ionization within the? condenser.

It is a further object of this invention to provide a solid dielectric variable condenser which excludes all fluids from its electric field.

A still further object of this invention is to provide a simple, inexpensive and practical condenser which is selectively variable and which will be eifective when atmospheric pressures and density is low and voltages are high.

Other objects and advantages of this invention will become apparent upon consideration of the following detailed description which when taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a plan view of an embodiment of this invention partially broken away to show the circular shape of the condenser.

FIGURE 2 is a view along line 22 of FIGURE 1.

FIGURE 3 is a view. similar to FIGURE 2 but showing the variable section of the condenser rotated 180.

FIGURE 4 is an exploded view of the interior elements of the condenser.

As shown in FIGURE 1, a condenser 12 having a circular shape is inclosed by a non-conductive low dielectric housing 14. However, in actual practice this nonconductive, low dielectric housing 14 may, if desired, be made an integral part of the structure or apparatus in which the condenser is utilized. In any event, the housing provides a convenient means for holding the interior elements of the condenser together and to electrically isolate the interior parts as will presently appear. Conductors 16 are used to supply potential to the electrically conductive members of the condenser and a screw means 17 affords adjustment of the condenser as will presently appear.

As shown in FIGURE 2, the metal

cylindrical members

18 and 24 are opposing plates of the condenser 12. Voltage is applied to the

cylinders

18 and 26 by means of corresponding conductors 16. As shown in FIGURES 1, 2 and 3, conductors 16 are secured in housing 14 and disposed in contact with

cylinders

18 and 20 to supply potential thereto. The

cylinders

18 and 20 are separated by a cylindrical member 22 of dielectric material of varying thickness and a member 32 of low dielectric insulating material. The

cylinders

18 and 20 are mounted for relative rotation and each cylinder is provided with areas in apposition movable in and out of registry across the dielectric member 22 for control of the capacitance.

In accordance with the teachings of the present invention the dielectric member 22 must be of varying thickness; however, this variance need not conform to the embodiment illustrated since any geometric variance of the lower surface 24 (FIGURE 4) of the dielectric member 22 will be operative so long as the upper surface 26 of dielectric member 22 is flush with the outer surface 28 of cylinder 18 and the outer surface 30 of insulating member 32. The upper surface 34 of cylinder 20 is so formed as to closely conform to and mate with the variance of the lower surface 24 on dielectric member 22.

As shown in the embodiment illustrated, the electrically conductive cylindrical member 18 is mounted for r0 tation about its longitudinal axis in housing 14 and has a single stepped portion cut into its outer surface thereby forming a cylindrical member having a single stepped segment 35 projecting therefrom to provide a pair of outer parallel surfaces 36 and 38 thereon. This segmental projection may, if desired, be semi-circular in shape as shown.

The segmental insulating member 32 has an inner surface 40 as well as the outer surface 30 and is mounted to be carried by cylinder 18 for rotation therewith. The inner surface 40 is placed adjacent the outer surface 38 of cylinder 18. The outer surface 30 of member 32 then lies flush and in a plane with the outer surface 36 of cylinder 18 (FIGURES 2 and 3). This insulating member 32 may, if desired, be semi-circular but this shape may be varied just so long as it is shaped conformably to completely fill the stepped portion of cylinder 18.

The dielectric member 22 is mounted with its longitudinal axis coincident with the longitudinal axis of the member 18 and has an upper flat surface 26 and a lower surface 24. The upper surface 26 of dielectric member 22 lies adjacent to and in contact with the outer surface 30 of insulating member 32 and the outer surface 36 of cylinder 18. The lower surface 24 of dielectric member 22 may, if desired, have a stepped semi-circular or segmental projection therefrom to vary its thickness. This projection then provides two lower parallel surfaces 4-2 and 44.

The cylindrical electrically conductive member 20 is mounted for simultaneous rotation with the dielectric member 22 and has its upper surface 34 in conformably mating contact with tne lower surface 24 of dielectric member 22. The longitudinal axis of cylinder 20 is coincident with the longitudinal axis of dielectric member 22.

The cylinder 2i) may, if desired, have a stepped segmental or semi-circular portion projecting from the upper surface 34 to form two

parallel surfaces

46 and 48. These

surfaces

46 and 48 are disposed to lie adjacent to and in mating contact with the lower

parallel surfaces

42 and 44 respectively, of dielectric member 22.

Since most of the capacity of the condenser is produced by that portion of the metal cylinder 18 which is in contact with the dielectric member 22 and by the surface area of the metal cylinder 2% in contact with dielectric member 22 and directly opposite the contacting portion of cylinder 18, and since the capacity of a condenser varies inversely with the distance between its plates, the capacity of the condenser described herein is less when cylinder 18 and insulating block 32, rotatable with cylinder 18, are rotated out of registry from the position shown in FIGURE 2 to the position shown in FIGURE 3. The capacity of the condenser can therefore be continuously varied during the rotation of cylinder 18 and insulating block 32 between the maximum and minimum extreme positions indicated in FIGURES 2 and 3 respectively. The ratio of maximum to minimum capacity can be controlled by varying the thickness of the dielectric member 22; therefore, to change the capacitance of the condenser 12, the thickness of the dielectric member 22 must be decreased or increased accordingly.

Cylinder 18 and insulating member 32 can be rotated together by any convenient means. The screw means 17, shown in the drawing, is typical of many other means that can be used. Screw 17 is secured to cylinder 18. To rotate cylinder 18 and member 32 to a second position it is only necessary to rotate screw 17 with a force necessary to overcome the frictional resistance between cylinder 18, member 32 and housing 14. Because of the snug fit between the housing and interior elements of the condenser, the cylinder 18 and member 32 will remain in this second position until application of a further force which overcomes the frictional resistance between the inten'or elements of the condenser and the housing.

The plane where the outer surface 36 of cylinder 18 and the outer surface 30 of insulating member 32 come in contact with the upper surface 26 of dielectric member 22 defines a plane of relative movement. Thus, while cylinder 18 and member 32 are being rotated by screw 17, cylinder 20 and dielectric member 22 are retained in position by virtue of the snug fit and frictional resistance between housing 14 and cylinder 20 and member 22. If desired, screw 17 may be secured to cylinder 20 for rotation thereof and cylinder 18 and insulating member 32 can remain stationary while cylinder 20 and dielectric member 22 are rotated; however, the use of either alternative is encompassed by the inventive concept of the present invention.

Because the elements of the condenser as set forth herein fit snugly together and because it is solidly constructed there are no effective openings on the surfaces to be presented to the atmosphere; therefore, all air pockets in the condenser are eliminated even while its capacitance is being changed and the condenser will exclude any fluids which may affect proper operation of the condenser. The condenser of the present invention, therefore, is effective in any environment and under any atmospheric conditions.

Although certain specific embodiments have been disclosed and described it will be readily apparent to those skilled in the art that other modifications can be made, such as changing the configuration of the cylinders, the dielectric member and the insulating member, it being only essential that the parts fit snugly together. Therefore, this application should be taken in an illustrative rather than in a limiting sense with the realization that these modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A solid dielectric variable condenser comprising a first electrically conductive member disposed for rotation about its longitudinal axis and having a single stepped portion cut into its outer surface, a segmental insulating member mounted for rotation with said first member and conformably shaped to completely fill said stepped portion and have its outer surface lie flush with the outer surface of said first member, a dielectric of varying thickness including upper and lower surfaces and disposed with its upper surface in contact with the outer surfaces of said first member and said insulating member, a second cylindrical electrically conductive member including an upper surface disposed adjacent to said lower surface of said dielectric, means for selectively rotating said first member and said insulating member relative to said dielectric and said second member, means for providing electric potential to said first and second members, means electrically isolating said first and second members and holding said first member and said insulating member for rotation relative to said dielectric and said second member.

2. A condenser as set forth in claim 1 wherein said electrically isolating and holding means is a housing in which said first member, said insulating member, said dielectric and said second member are all aligned along their longitudinal axis.

3. A solid dielectric variable condenser comprising a first cylindrical electrically conductive member disposed for rotation about its longitudinal axis and having a single stepped semi-circular portion projecting therefrom to provide a pair of outer parallel surfaces thereon, a semicircular insulating member mounted for rotation with said first member including outer and inner surfaces and having its inner surface adjacent to and in contact with one of said outer parallel surfaces of said first member and having its outer surface flush with the other said outer parallel surface of said first member, a cylindrical dielectric of varying thickness including upper and lower surfaces said upper surface in contact with said outer surfaces of said first member and said insulating member, a second electrically conducting member including an upper surface disposed adjacent said lower surface of said dielectric, means supplying an electric potential to said first and second members, means electrically isolating said first and second members and holding said first member and said insulating member for rotation relative to said dielectric member and said second member.

4. A solid dielectric variable condenser as set forth in claim 3 wherein said cylindrical dielectric has a stepped semi-circular portion projecting therefrom to form a pair of lower parallel surfaces thereon.

5. The condenser as set forth in claim 4 wherein said second cylindrical electrically conducting member has a stepped semi-circular portion projecting therefrom to form a pair of upper parallel surfaces thereon, said upper parallel surfaces in contact with said lower parallel surfaces of said insulating member.

6. A solid dielectric variable condenser comprising a pair of relatively rotatable capacitor plates disposed for electrical connection to corresponding conductors, a dielectric member of varying thickness disposed between said plates, an insulating member adjacent said first plate and mounted for rotation therewith, each of said plates provided with areas in apposition movable in and out of registry across said dielectric and said insulating member responsive to the relative rotation of said plates for control of the capacitance.

References Cited in the file of this patent UNITED STATES PATENTS 1,553,971 Apostol Sept. 15, 1925 2,748,328 Font May 29, 1956 2,913,644 Bleazey Nov. 17, 1959 FOREIGN PATENTS 452,573 Great Britain Aug. 25, 1936 764,965 Germany June 8, 1954

Claims

6. A SOLID DIELECTRIC VARIABLE CONDENSER COMPRISING A PAIR OF RELATIVELY ROTATABLE CAPACITOR PLATES DISPOSED FOR ELECTRICAL CONNECTION TO CORRESPONDING CONDUCTORS, A DIELECTRIC MEMBER OF VARYING THICKNESS DISPOSED BETWEEN SAID PLATES, AN INSULATING MEMBER ADJACENT SAID FIRST PLATES AND MOUNTED FOR ROTATION THEREWITH, EACH OF SAID PLATES PROVIDED WITH AREAS IN APPOSITION MOVABLE IN AND OUT OF REGISTRY ACROSS SAID DIELECTRIC AND SAID INSULATING MEMBER RESPONSIVE TO THE RELATIVE ROTATION OF SAID PLATES FOR CONTROL OF THE CAPACITANCE.