US1702073A - Variable inductance - Google Patents

Description

Feb. 12, 1929.

N. H. CLOUGH VARIABLE INDUCTANCE Filed June 27, 1925 INVENTOR NEWSOME HENRY CLDUGH By '4 TTORNEY Patented Feb. 12, 1929.

UNITED STATES PATENT OFFICE.

NEWSOME HENRY CLOUGH, OF CHELMSFORD, ENGLAND, ASSIGNOR T RADIO COB- ZPORA'IION OF AMERICA, A CORPORATION OF DELAWARE.

VARIABLE INDUCTANGE.

Application filed June 27, 1925, Serial No. 39,895, and in Great Britain July 4, 1924.

This invention relates to variable inductances or variometers.

According to this invention 1 provide an inductance coil with a shield which preferably takes the form of a split ring and with means for interconnecting two variable points on the shield, so that a variable length of the shield may be short-circuited. By this means a closed metallic loop is provided and its area is variable from zero to the area enclosed by the shield.

in one form of variometer l employ a cylindrical coil substantially enclosed in a shield formed of a metallic tube which is mounted coaxially with the coil, and 1 conmeet one end of the tube to a spindle which can rotate about the axis of the coil and tube and carries an arm or arms making rubbing contact with a surface or surfaces of the tube. 29 Thus by rotating the spindle, a variable length of the tube can be short-circuited and thus the inductance of the coil can be varied.

I may also employ a strip around the outside of the coil with means similar to those for short-circuiting a. portion of the tube for short-circuitiug a portion of the outer strip, or the strip may be arranged coaxially but not concentric with the coil.

Again, l may form the shield of a strip of foil which is wound upon a bobbin and has one end fixed relative to the coil, the bobbin being mounted on an arm which is rotatable about the axis of the coil, so that by turning the arm more or less of the :toil can be unwound from the bobbin.

A more clear and complete understanding of my invention will be had from the following detailed description of the various modifications thereof when read in connection with the accompanying drawings throughout which like reference numerals indicate like parts and in which;

Figure l is a rear elevation view of one form of my invention showing the split ring outside the coil.

Figure 2 is a sectional rear elevation of the same device shown in Figure 1.

Figure 3 is a modification or the arrangement shown in Figure 1 with a metal tube corresponding to the split ring in Figure 1,

Figure 4 is a part sectional rear elevation of the device shown in Figure 3,

Fl re 5 is a still further modification showing a metal foil to the split ring while,

Figure 6 is a rear elevation of the modification shown in Figure 5.

Referring in particular to the drawings one form of the invention is shown in Figs. 1 and 2 where the circular coil is indicated by numeral 1 through the center of which extends the shaft 8 adapted to support a split ring 2. The split ring 2 is supported out-- side the coil 1 from shaft 8 and bushing or tube 7' by a fixed arm 17. Mounted upon the shaft or spindle 8is a movable arm 18 carrying the brushes 19 which are adapted to contact with the split ring 2 and upon rotation of the shaft 8 by means of an actuating knob (not shown) to short-circuit a varying amount of the ring 2' whereby the efiective coil length is changed so as to give the desired inductance.

Figures 3 and 4 show a further modification in which the coil 1 is surrounded by a split metal tube 20 supported in any preferred manner from a shaft 8. Contact with one end of the tube, which may be, for example, copper, is maintained'through an arm or fixed member 21 carried by the shaft 8 and also carried by the shaft 8 is a rotatable arm or lever 22 adapted to carry brushes 28 which bear against and make contact with opposite sides of the metal tube 20. In a manner similar to the arrangements shown in Figs. l and 2, the coil may be short-circuited so as to give any desired inductance by rotating the arm 22 in either a clockwise or countor-clockwise direction.

Still another embodiment which my invention may assume is shown in Figs. 5 and 6 where the coil 1 is mounted on a support in the form of an insulating disk 30 which also provides a bearing for a shaft 8 as shown in Figure 6 merely for purposes of illustration as this coil may be mounted in any convenient manner. (larried by the support 30 is a fixed arm 24 which is adapted to support a thin metal foil 28 which may be fastened in any preferred means to this arm such as for example, by riveting. The arm 24 is mounted at one end of the coil and is bent to extend over the outer peripheryof the coil so that the metal foil 28 may surround the coil in a manner similar to that of the split ring 2' shown inFigs. i to 4. The shaft 8 which is rotatably mounted in the bearing of support 30, carries at the other end of the coil an arm 25 which in turn supports at the outer end thereof a pin 26 adapted to project across the outer periphery of the coil and to carry a bobbin 27. The metal foil 28 is secured to this bobbin and is adapted to be wound on the bobbin when shaft 8 is rotated in one direction and unwound therefrom when the shaft 8 is rotated in the opposite direction. The bobbin may be provided with an internal spring, not shown, so as to keep the foil at all times tight and may be held in any desired position by the friction of the arm upon the shaft. In this case, variances of inductance are ob tained by rotating the arm 25 so as to permit more or less of the metal foil 28 to surround the coil 1 and vary the effective coil length.

7 Having now described my invention I claim:

1. In a variable inductance, the combination of a coil, means for varying the inductance of said coil including a rotatable spindie within said coil, a fixed arm mounted upon said spindle at one side of said coil and extending beyond the periphery of said coil, a rotatable arm. extending beyond said coil P81 riphery mounted upon said spindle at the other side of said 001 a rotatable bobbin carried by said rotatablearm, and a sheet of metal foil fastened to said fixed arm and adapted to wind and unwind upon said bobbin.

2. In a variable inductance, the combination of a coil, means for varyin the inductance of the coil including a flexibde metal foil sheet adapted to be wrapped around the periphery of said coil, and means forwrappmg or unwrappin said metal sheet.

3. In a variable inductance, the combination of a coil, means for varying the inductance of said coil comprising a support mounted in said coil, a metal shield surrounding a periphery of said coil, a fixed member mounted on said support connected to one end of said shield, a movable member mounted on said support and a bobbin carried by said movable member and adapted to wind or unwind said shield when said movable member is moved.

nnwsonn HENRY OLOUGH.

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