US2258736A - Mercury interrupter - Google Patents

Description

Oct. 14, 1941. w s, BRlAN MERCURY INTERRUPTER Filed Nov. 19, 1938 3n vento1 1 7177127772 5: f1 mm M (Zttornegs Patented Oct. 14, 1941 2,258,736 MERCURY INTERRUPTER 'William S. Brian, Owensboro, Ky., assignoi' to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application November 19, 1938, Serial No. 241,383

3 Claims.

This invention relates to circuit interrupters and more specifically to means for automatically periodically interrupting current flow for changing current or voltage characteristics in direct current circuits.

There are of course many instances in which it is desired to operate devices from a direct current source which require different voltage or current than that available, or perhaps may require a pulsating uni-directional current instead necessary to provide a pulsating current.

voltage or current ratio of direct current.

one-half wave alternating current.

mechanical vibrating structure.

ing direct current for any use.

long life.

' cuit. However, as soon as the circuit is broken the source of heat ceases and the mercury vapor Thus, if we of a constant direct current flow. One illustracondenses to again recomplete the circuit which tion of such a condition or plurality of conditions may again immediately recycle. occurs in automotive vehicles where it is necesform a shell of insulating material, and place sary to supply many accessories such as clocks or therein a body of mercury, said shell having a radios with power from the storage battery hav form of an hour glass, the mercury within the ing a given potential or perhaps to provide powrestricted portion will upon a passage of a cerer for some of the essential operating parts of tain required current vaporize, thus breaking the the vehicle from said same battery such as, for circuit from one large pool of mercury to the example, the fuel pump in which instance it is other, but this will immediately recondense to reform the circuit and thus we have an auto- It is a basic fact that we cannot change the matic periodic circuit interrupter.

We With the above explanation and objects in can, however, by interrupting such a current, obmind, my invention will be better understood by tain a pulsating direct current which we can use reference to the following specification and in many instances exactly as we use alternating claims and illustrations in the accompanying current and it is for all practical purposes a drawing, in which:

With this Figure l is a vertical section through one of pulsating current we may change the current the interrupters of the above identified hour and voltage ratios as desired. These of course glass type. are known facts and various means have been Figure 2 is a vertical section through a modideveloped for periodically interrupting or breakfied form of the same type of interrupter. ing the current from a direct current source, one Figure 3 is a vertical section through an interof the better known devices being a vibrator such nally heated orifice type. as is used for power supply in an automotive ra- While these various types of interrupters are dio receiving set. These devices however utilize herein shown as comprising a glass outer envemechanical movement and are therefore subject lope, it is to be understood that any insulating to deterioration both of the switch points and the envelope may be used and it is only for illustrative purposes that these are shown as bein com- It is therefore an object of my invention to posed of glass and it is also only necessary in this provide means for automatically interrupting a type of interrupter to form the neck or orifice direct current to provide a more flexible pulsatportion of insulating material for operative pur-.

poses if it is desired to do so as the two end It is a further object of my invention to proportions act as a whole as electrodes in any .vide such a current interrupter as shall be subevent.

stantially insensitive to deterioration and have Referring now more specifically to Figure 1, an

outer shell 2 is shown whose vertical section is It is a further object of my invention to prosubstantially that of an hour glass providing an vide such a current interrupter as shall be very upper chamber 4 and a lower large chamber 6 simple in construction and relatively easy to having a restricted area or orifice 8 therebemanufacture and use.

When a certain material is utilized as a conductor of electric current, if this material is changed from one physical condition to another it frequently ceases to be a conductor, at least at tween. Two electrodes 10 and i2 are sealed into the upper and lower chambers respectively. There is also sealed within the lower chamber, the orifice and a portion of the upper chamber a body of mercury [4. Thus as a particular p0- the particular potential applied, and therefore tential is applied between H) and i2, current will a structure such as that flow through the body of mercury in the upper chamber, through the body of mercury in the orifice 8, and through the mercury in the lower chamber to complete the circuit between these electrodes.

Due to the passage of this current, however, the mercury in the orifice 8 is heated to such a point: that a small globule of mercury vapor is formed in this orifice which causes a separation of the two bodies oi mercury and thus a cessation of the current flowing between the two. This cessation however removes the source of heating and due to this and to the pressure of the mercury on the globule the same condenses reestablishing the circuit so that current may immediately pass and the device will go through the same cycle. The area of the orifice of course determines the range of potentials applied to the electrodes l and I 2 which will operate the device as desired.

If it is desired to operate on a lower potential or current flow there may be applied to the orifice a small heating device such as shown at H5 in- Figure 2 connected to a power supply which will raise the normal or ambient temperature of the mercury within the orifice and a smaller amount of heat will be required of the current flow to operate the device. Otherwise the device shown in Figure 2 is exactly the same as that shown in Figure 1.

The same results may be obtained by providing shown in Figure 3 in which there is provided an outer insulating shell l8 having an pool of mercury 22 up to a certain desired level. Extending down through the central portionof the upper cavity and through the orifice is a and the PR loss will provide additional .heat so that this heat will aid the heat due tothe series current in the mercury somewhat similar to the a restriction connecting orifice 20 and being sealed with a rod of glass or other insulating material 24 within which is sealed an electrode 26 of comparatively high resistance, said electrode extending from the lower end of the insulating member 24 as shown at 28 to form a contact with the mercury pool in the lower chamber. There is also sealed in the upper portion a second electrode 30 adapted to contact the mercury 22. The flow in this instance is from electrode 26, through tip 28, mercury pool 22, to electrode 30; It will be noted thatthe mercury in the restricted area 20 is again in series and will be heated as before; However in this instance we have the added heating effect due to the flow of current through the electrode 26 in the orifice for, as before stated, this is of substantially high resistant material action of the external Otherwise the operation is the same.

In order to design these interrupters to operate most satisfactorily on any given frequency band, the following factors should be considered: 1. Mercury pressure or height of column within the shell orcasing. 2. The operating temperature oi the mercury. 3. The cross sectional area of the orifice. thesesatisfactory results will be obtained combination with the external circuit.

I claim:

1. In a circuit interrupter, two mercury pools, means for restricting a body of-mercuryinterconnecting the two pools, means for applying a potential diflerence across the two pools to cause current now therethrough and through the restricted mercury portion to cause heating and vaporization of the mercury and additional means for heating the restricted portion of mercury comprising a member immersed in and insulated from the restricted portion of mercury-and having a comparatively high 1 R drop.

2. In a circuit interrupter, an insulating casing having a plurality of bulbous cavities therein and the same, mercury in each cavity and through the restriction to join the two larger bodies, an electrode terminating in each large body of mercury supported by the casing, one of said electrodes extending through the restricted portion, and means insulating the electrode within the restricted portion whereby no contact is made between the electrode and the mercury therein.

3. In a circuit interrupter, a casing, a plurality of pools of mercury supported thereby, a restricted portion interconnecting the pools, electrodes immersed in each pool supported by the casing whereby current is caused to flow through the mercury in the restricted area to heat and vaporize the same, one electrode extending through the restricted arating the electrode from the mercurywithin the restricted portion whereby the heat generated by the passage of current through the last named zation and interrupted operation.

- WILLIAM s. BRIAN.

heater shown in Figure 2.

By properly proportioning area, insulating means sep-'

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