US2163708A - Means for controlling electric circuits - Google Patents

Description

June 27, 1939.

Original Filed Jan. 50, 1935 K. E. SCHIMKUS ET AL MEANS FOR CONTROLLING ELECTRIC CIRCUITS 14 AM T 1 -29 22 23 24 12 25 25 10 g9 E7 141 I Patented June 27, 1939 UNITED STATES MEANS FOR. CONTROLLING ELECTRIC CIRCUITS Kurt E. Schimkus,

Detroit, Mich., and Willy Dumke, Chicago, Ill., assignors, by mesne assignments, to Hannah 0.

Mich.

Chereton, Detroit,

Application January 30, 1935, Serial No. 4,056 Renewed November 4, 1938 10 Claims. (Cl. 200-113) The invention relates to devices for increasing and decreasing the flow of current in electric circuits and has as its general aim the provision of a novel means which is simple, substantially free of mechanical noise, practically indestructible from operative causes, and has no moving parts requiring original or subsequent adjustment.

An object of the invention is to provide a novel device of the above class which is capable of producing regular pulsations of current and operates with low current loss and high efliciency.

Another object is to provide a device of this character which embodies novel means for effecting intermittent current pulsations through the recurrent conversion of a current conducting substance from one physical state in which it oflers relatively little resistance to current flow into another physical state in which current flow is substantially prevented and thereafter reconverting all or part of the substance to its original state.

A further object is to provide such a device which embodies means for effecting cycles of current pulsations including a conductive material capable of changing its physical state in response to the application of relatively little heat energy arranged to be interposed in the circuit and confined in part to produce a predetermined resistance to current flow, whereby to generate heat energy ample to cause a change in the physical state of said material at some point in the confined part thereof resulting in a break of the circuit, the circuit being partially or entirely reestablished immediately thereafter by the return of all or part of said material to its original physical state.

More specifically stated, an object of the invention resides in the provision of a device arranged to be connected in a circuit and including, as a current conducting medium, mercury or mercury amalgam in a container which embodies a constriction, in the nature of a capillary tube, of such predetermined dimensions as will, when the device is carrying the electrical energy for which it is intended, produce that degree of heat required to volatilize a small portion of the mercury in the constriction, whereupon the gaseous mercury interrupts the continuity of the metallic mercury and not only breaks the circuit but entirely stops or minimizes heat generation to permit condensation of all or part of the mercury vapor and partial or entire reestablishment of the circuit.

In conjunction with the foregoing, another object is to provide a novel device embodying means which provides for the expansion and contraction of the mercury or other conducting medium under temperature changes, both internal and external, which means in dimensions is correlated with those of the restricted tube to insure proper operation.

Another object is to provide a device of this character which is not affected by external shocks or vibrations and may be used in any position.

A further object is to provide a novel device in which failure of the device due to the introduction of extraneous matter, such as an air or 15 gas bubble in the constricted portion of the conducting medium, is not possible.

Stated more specifically, another object is to provide a device embodying a mercury container having a restricted tube opening into a sub- '0 stantially central point of the container, the quantity of mercury in the container being less than the amount required to fill it and more than that required to cover the end of the tube in all positions of the device and at the lowest temperature to which the device may be subjected.

Other objects and advantages will become apparent in the following description and from the accompanying drawing.

Application, Serial No. 179,893, filed'December so 15, 1937, in the name of Kurt E. Schimkus as a continuation hereof contains claims to the generic operating characteristics of the present invention and to those other novel features thereof which are not claimed herein. 3

In the drawing:

Figure 1 is a sectional view of a device embodying the features of the invention.

Fig. 2 is a similar view of such a device modifled in form for full-wave operation.

Figs. 3 and 4 are wiring diagrams of circuits showing respectively the manner in which the devices illustrated in Figs. 1 and 2 may be connected.

While the invention is susceptible of various 45 modifications and alternative constructions, we have shown in the drawing and will herein describe in detail the preferred embodiment, but it is to be understood that we do not thereby intend to limit the invention to the specific form 50 disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

Briefly stated, the features of the present inu vention are attained by utilizing the property of certain current conducting substances, of which metallic mercury is an excellent example, to change the physical condition or state thereof, when subjected to heat, temporarily to another physical state in which the substance is either non-conductive or offers such high resistance to current flow as to be substantially non-conductive. With such a substance, and knowing in advance the average current values to be normally encountered by the device, the substance may be arranged to impart a substantially fixed resistance to current flow of such value that the heat energy derived thereby will cause the conversion of a minute but suflicient quantity of said substance to its non-conductive condition to break the circuit and either entirely interrupt or decidedly decrease the current flow. Following the break the production of heat energy entirely or in large part ceases and the substance which has changed its physical state reverts entirely or in substantial part to its original state and reestablishes the circuit. This constitutes one complete operating cycle. In operation the cyclic frequency may be exceedingly high and is entirely independent of mechanical or like limitations. Preferably the predetermined fixed resistance is obtained by forming the substance to provide a current path which is of predetermined dimensions.

The device thus functions to translate the direct current output of a source of electrical supply into a pulsating current, in which the actual current values vary at a predetermined frequency between maximum and minimum values. In certain instances, and depending upon the selection of the material which undergoes the change of state and also depending upon the electrical characteristics of the associated circuit, the current flow may be entirely interrupted at the conclusion of each heating phase, and all of the converted material may revert to its original state during the cooling phase. In other instances, the heating phase may produce only a partial interruption of the current fiow and the cooling phase may result in only a partial reconversion of the material. In'either event, however, the changes of state are accompanied by and result in periodic variations of the current between well defined maximum and minimum values, and in the illustrated embodiments of the invention, these variations are abrupt and sharp. Throughout the following description and in the appended claims, accordingly, terms such as make, break, interrupt, recondense, reestablish, revert, reconversion, increase, decrease and the like are used in a generic and relative sense. In the claims also, the term normal" current is utilized to refer to the increased value of current which flows through the substance at the conclusion of each cooling phase, or at the conclusion of each partial or entire reconversion of the substance to its original state, which normal value of current again initiates the conversion of the substance to its relatively non-conducting state.

Referring more particularly to the illustrative forms of structure shown in the drawing, what may be termed a pulsator interrupter is shown in Fig. 1. Hereinafter mercury or mercury amalgam will be considered as exemplary of a suitable substance, the changes in the physical states thereof being from a normal fluid state to a gaseous state, followed by condensation to the fluid state. In the description and in the claims. the term mercury is used in a sense generic to both mercury and mercury amalgam. The device shown in Fig. 1 comprises two mercury containers I!) which may be of any suitable size and shape but are preferably in the form of hollow substantially spherical members. These containers are spaced apart and are connected by a tubular member ll having a bore l2 oppositely communicating with the interior of each container. Where the device is intended to handle electrical currents of relatively low value, the containers and the tube may well be fashioned of glass, such as that known commercially as Pyrex. For higher values a stronger material,may be necessary.

The bore is filled with mercury and the containers are nearly filled as shown, the mercury body being indicated at l3. Connection of the device in an electric circuit so that the mercury in the bore I2 is included in the circuit and may be established by a terminal l4 sealed, as at l5, in each container wall and contacting the body of mercury in each container.

Since in the transmission of electrical energy resistance is inversely proportional to the size of the conductor, the fixed resistance of the mercury may be advantageously predetermined and permanently maintained by properly dimensioning the bore l2. For currents of low potential, such as those drawn from a storage battery, I

the bore is quite restricted and the tubular members may be in the nature of a capillary tube wherein the bore diameter is a fraction of a millimeter.

Moreover the length of the bore must be properly calculated apparently because of the fact that the mercury vapor produced whenthe change of physical state occurs has substantially greater volume than the fluid mercury. In capillary tubes or like small diametered bores, the resistance to fluid flow therethrough is relatively great. Hence, if the bore is excessively long the gaseous mercury cannot readily overcome the flow resistance offered with the result that the circuit may not be broken or is not broken sharply and regularly. Conversely, if the bore is too short, expansion of the created gas may cause a greater separation of the mercury column than is necessary to break the circuit. In this case a permanent break in the circuit may result by failure of the broken ends of the column to reunite or an undesirable delay in closing the circuit occurs due to the lag in the flow of the material caused by the resistance to flow. It is, therefore, desirable to predetermine the length of the bore to obtain that intermediate length wherein the circuit is broken sharply, regularly and in which the relationships are so balanced that substantially the initial conversion of mercury from the fluid to the gaseous state will "break the circuit, immediately followed by a reconversion of gas to fluid which closes the broken circuit. When the relationships are of this nature the device is exceeedingly sensitive, will start at once upon closing the circuit and will operate at a relatively high frequency.

Since the break of the mercury column is the result of change in the physical state of mercury caused by the flow of electrical energy, the average values of the electrical current which is to be interrupted by the device will determine the dimensions of the bore. Generally stated the dimensions will increase as the values of the electrical current increase. As a particular example of "dimensions which have been found satisfactory in a device for producing pulsating current from a storage battery in a circuit adapted to energize the primary winding of a transformer, the restricted tube may have an approximate diameter of twenty-two one-hundredths of a millimeter and a length of approximately three and eight-tenths centimeters.

Another factor to be considered is the quantity of mercury in the containers i0 since an opposing force is thereby imposed upon each end of the mercury column in the bore, which force will also affect the sensitivity of the device in operation. Consequently the quantity of fluid in the containers will, if not held within predetermined maximum and minimum limits, have substantally the same efiect as a bore i2 which is too long or too short. The quantity of fluid, in general, increases as the dimensions of the bore l2 increase. In the present instance the mercury in the containers l0 nearly but not quite fills the containers, the bubbles of air or other gas It in each container being particularly provided to allow for the expansion and contraction of the mercury as temperature variations occur not only externally but internally as the device passes between inoperative and operative conditions. Such expansion introduces another factor to be considered since the pressure of the gas in the bubbles i6 increases as the mercury expands and thus imposes additional force on the mercury column in the bore which acts thereon in the same manner as does the quantity of the mercury.

However, once the several factors to be taken into consideration are known it is not difficult to determine the dimensional relationships of the several parts in the fluid confining system of a device intended for operation in connection with current of a known average value. In the specific illustration of container dimensions, a sphere of approximately one and nine-tenths centimeters has been found suitable in connection with a restricted tube of the dimensions above mentioned.

Unless, in a device of this character, some means is provided for preventing the entrance of a bubble of extraneous gas, such as air, from the bubbles iii, the device can be used satisfactorily only in a substantially horizontal position, due to the permanent interruption of the mercury column by the entrance of such a bubble. To this end the present invention embodies means whereby no foreign matter of any kind can enter and become lodged in the bore I2. Thus, as shown, each end of the tubular member ii is extended through the wall of the associated container ID to a point which is substantially centrally thereof so that the ends of the bore are located approximately on the center points of the containers. The ends of the tubular member ii are preferably rounded, as indicated at IT, to avoid trapping air bubbles on the ends as the mercury is introduced into the containers through the filling openings, shown in sealed condition at l8. With this arrangement of parts, and with the containers properly dimensioned, the quantity of mercury in the containers will be more than ample to cover the exposed ends of the bore i2 regardless of the position of the device. Hence, air bubbles, or indeed any foreign matter, such as minute particles of oxide of mercury, cannot possibly enter the bore.

It has been found that the union between the tubular member and each container is stronger and the mercury is better supported if the wall portions of the containers about the tubular member are turned inwardly, as shown, to form a smooth junction. Moreover, to lessen electrical resistance externally of the bore i2 the I terminals H are extended to points immediately adjacent to the bore ends.

The device shown in Fig.1 is intended primarily to be used for controlling the simplest type of circuit, such as a circuit for effecting energization of a transformer by a pulsating current. In Fig. 2 a device is shown for controlling a circuit which includes two branches, such as a circuit by which energization of a transformer by current alternating in direction is eflected. The construction of the latter device, as well as the correlation and relationship of the parts thereof, is substantially the same as that shown in Fig. 1, as is indicated by the use of the same reference numerals. However, in this form, the tubular member i I is interrupted between its ends and the interrupted ends communicate with opposite sides of an intermediate contact chamber ll. The casing forming this chamber is preferably smaller than the containers in and is filled with El mercury. At one side a terminal 20 extends through the casing wall to a point intermediate the opposed ends of the interrupted bore i2. In this device the operation is the same as in the first device except that two restricted bores are as provided for controlling the branch circuits. Since it is practically impossible to balance the bore branches exactly, the initial breaking of the circuit will occur in one or the other of the bores, after which the circuit through the other I bore will be broken while the first circuit is being reestablished. Consequently this form of device will be effective to make and break" branch circuits in alternation.

In illustration of circuits embodying these dea vices and in description of an environment in which these devices have been found particularly suitable, Figs. 3 and 4 show circuits employed in converting low voltage direct current from a storage battery into high voltage direct current for (l supplying the B circuit of a radio receiving set with current having a proper potential. Such circuits are used largely in the so-called 8" battery eliminator devices employed in motor vehicle installations of radio receiving sets.

Fig. 3 shows the device in the capacity of a pulsator. Thus, one terminal i4 is connected through lead 2! with one side of a storage battery 22 which in turn is connected by lead 23 and interposed control switch 24 with one end of the primary winding 25 of a step-up transformer 2G. The other end of the primary winding is connected by lead 21 with the other terminal II. This circuit is effective to energize the primary winding intermittently and always in the same direction, which pulsating current is however reflected as an alternating current in the transformer secondary winding. A condenser 28 is connected across the device by leads 2! to the leads 2| and 21 and serves to tune the circuit and reduce the slight electrical noise resulting from the operation of the device. The condenser 28 also appears to affect or control the frequency of the device.

To complete the circuit any suitable means for rectifying the current from the secondary winding 30 may be employed, such as a thermionic valve 32. Herein one end of the secondary winding'is connected by lead 3i with the plate element 33 of. such a valve, while the cathode ele- 7| ment 34 is connected with an output lead 35 to one side of a suitable filter system, generally designated 36. The other end of the secondary winding is connected by lead 31 with the other side of said system. A condenser 38 may be connected by leads 38 across the leads 3| and 31 from the secondary winding. The valve has a heating filament 39 connected by leads 39 directly with the battery 22, although the switch 24 is interposed.

In operation, closing of the switch 24 produces a current flow through the interrupting device, the resistance to which flow almost instantly heats the mercury in the bore and causes a small 5 part of the mercury to volatilize. This change of state through the increased volume occupied by the gas breaks the circuit and immediately thereafter condensation of the gas reestablishes" the circuit. Repetition of this cycle of operation at a high frequency is effective to energize the primary winding intermittently and produce an alternating current of high voltage in the secondary winding which is rectified to an intermittent direct current by the valve 32, and smoothed into 5 a substantially even direct current by the filter system for delivery to the proper terminals of a radio receiving set.

With the circuit shown in Fig. 4 energy from a storage battery is translated into pulsating components successively opposite in direction. Thus, the end terminals l4 from the device are connected through leads 40 with the ends of primary winding 4|, condensers 42 of proper value being connected in series across the leads 40 by 35 leads 43. The intermediate or third terminal 20 of the device is connected by lead 44 with the lead 43 between condensers 42 and with a control switch 45 which, in turn, is connected with one side of the battery 46, the other side of which is connected with an intermediate or center tap" 4'! from the primary winding. Each end of the secondary winding 48 is, in this system, connected through a lead 49 with a plate element 50 of a thermionic valve 5| of the full-wave type. 45 A cathode element 52 cooperatively related to said plate elements is connected with an output lead 53 to a suitable filter system which may be of the type shown in Fig. 3 and is generally represented by the first condenser. A heating filament 54 is connected independently with the battery through leads 55 and a condenser 56 is connected across the secondary winding by leads 51.

The operation of this system is substantially 55 the same as that of the circuit illustrated in Fig. 3. However, in this system the alternate making and breaking of the circuits in the opposite branches of the bore is effective to energize first one and then the other section of the 60 primary winding, the current flow being in opposite directions. Proper adjustment of the values of the condensers 42 may be employed to synchronize the current pulsations in the two branches of the bores. The resulting alternating current in- 5 duced in the secondary winding is rectified, filtered and substantially direct current of high potential is delivered to the receiving set. This system is probably more eiiicient than the first described system,

From the foregoing it will be evident that a novel circuit controlling means has been provided which is unusually simple in construction. The device occupies a closed container. Hence the substance therein is not subject to oxidation or v 15 other chemical changes and will remain in its original condition indefinitely. The device is emcient since the only current loss is the result of the relatively low resistance offered by the substance imposed in the circuit. The only change caused by the current flow is one of physical state and the substance, therefore, is not expended or in any manner affected deleteriously by operation. There are no moving parts in the present device, hence accurate adjustment is not required. Upon determination of the proper correlation of dimensions and quantity of substance for a current of average values quantity production of uniform devices may be easily obtained. In addition, the device may be used in any position and under practically all operating conditions without injury thereto or impaired performance. As a result of these several advantageous features devices embodying the present invention are exceedingly practical, eflicient, adaptable for many uses and may be economically manufactured.

We claim as our invention:

1. A circuit controlling device comprising in combination a container having a restricted bore opening into the body of the container, a contact terminal having a portion exposed within the body of the container, the container being completely filled by a quantity of mercury and by a free gas bubble, so as to allow for expansion and contraction of the mercury, the quantity of the mercury being sufiicient to cover the end of the bore and engage the terminal in any posi tion of the device.

2. A circuit controlling device comprising in combination a container having a restricted bore opening into the body of the container, a contact terminal having a portion projecting into the container to a point adjacent the end of the bore, the container being completely filled by a quantity of mercury and by a free gas bubble, so as to allow for expansion and contraction of the mercury, the quantity of the mercury being sufficient to cover the end of the bore and engage the terminal in any position of the device.

3. A circuit controlling device of the character described comprising, in combination, a casing having a passageway therein of restricted size and a hollow chamber communicating therewith, said passageway being filled and said chamber partially filled with mercury, the end of said passageway being spaced inwardly from the wall of said chamber so as to prevent the entrance of bubbles from said chamber into said passageway in all positions of the casing, and means for establishing an electrical circuit through the mercury in said casing.

4. A circuit controlling device comprising, in combination, spaced containers, means connecting said containers having a passage therein of restricted size communicating with the interior of said containers near the centers thereof, mercury in said passage and containers in such quantity as will fill the passage and cover the ends thereof in any position of the device, and means establishing electrical contact with the mercury in each container.

5. A circuit controlling device of the character described comprising, in combination, a casing having a passageway therein of restricted size and a hollow chamber communicating therewith, said passageway being filled and said chamber partially filled with mercury, the remainder of said chamber being occupied by a free gas bubble, the junction of said passageway and said chamber being located to prevent the entrance of said bubble from said chamber into said passageway in all positions or the casing, and means for establishing an electrical circuit through said mercury.

6. A circuit controlling device comprising, in combination, a container filled in partwith mercury and in part with a gas bubble, a mercury filled tube of restricted dimensions connected with the container to provide a continuous mercury body, means for preventing interruption of the continuity of said mercury body by movement of said bubble into a position adjacent the mouth of said tube, and means for passing current through the mercury in said tube.

7. A circuit controlling device comprising, in combination, a container filled with mercury and a freely movable gas bubble, a mercury filled tube of restricted internal dimensions connected with the container to provide a continuous mercury body, and means for passing current through the mercury body, said container and tube having a point where the mercury in one joins the mercury in the other inaccessibly located with respect to the movable bubble whereby in no position of the device can the bubble interrupt the flow of current.

8. A circuit controlling device comprising, in combination, a pair of containers each filled in part with mercury and in part with a freely movable gas bubble, a mercury filled tube of restricted internal dimensions extending between said containers to provide a continuous mercury body, electrical connections for passing current from one container to the other through the mercury in said tube, and means for preventing movement of the gas bubble in either container into a position in which said bubble may interrupt the current flow between the mercury in a container and the tube.

9. A circuit controlling device of the character described comprising, in combination, a casing having a passageway therein of restricted size and a hollow chamber communicating therewith, said passageway being filled and said chamber partially filled with electrically conducting liquid material, the remainder of said chamber being occupied by a free gas bubble, the junction of said passageway and said chamber being located to prevent the entrance of said bubble from said chamber into said passageway in all positions of the casing, and means for establishing an electrical circuit through said material.

10. A circuit controlling device of the character described comprising, in combination, a casing having a passageway therein of restricted size and a hollow chamber communicating therewith, said passageway being filled and said cham ber partially filled with electrically conducting liquid material having the property of changing upon being heated to a relatively non-conducting state, the remainder of said chamber being occupied by a free gas bubble, the junction of said passageway and said chamber being located to prevent the entrance of said bubble from said chamber into said passageway in all positions of the casing, and means for passing an electric current through said material so as to eflect said change of state of at least a part of said material in said passageway.

KURT E. SCHIMKUS. WILLY DUMKE.

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