US1972291A - Mercury switch - Google Patents

Description

Sept. 4, 1934.

P. K. CRAMBLET MERCURY SWITCH Filed Feb. '23, i926 INVENTOR. Bea/.1, ff. CFAMBLZEY.

Patented Sept. 4, 1934 1,972,291 MERCURY swl'ron Paul K. Cramblet, Milwaukee, Wis'.,,assignor, by

mesne assignments, to ,Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application February 23, 1926, Serial 19 Claims. (Cl.200--1 52)' This invention relates to improvements in switches, and more particularly to those of the type known in the art as mercury switches.

Switches of this type comprise a hermetically 5 sealed envelope of glass, electrodes sealed therein and a body of mercury movable in the envelope so that in one position of the latter the circuit through the electrodes is completed, whereas when tilted or otherwise moved into a position in which the mercury may flow out of engagement with the electrodes, the circuit is broken. Generally speakLng, there are two types of these switches now in general use, one employing an envelope of soft glass, such as the lead or lime varieties, with the electrodes suspended therein and in such position that they are bridged by the body of mercury when the tube is moved into a certain position. In this type of mercury switch the arcing both at the make and the break of the circuit has a pronounced deteriorating eifect upon the electrodes, as is well known, this action on the electrodes affecting them to such extent that the life of the switch is materially shortened. In the other type of switch referred to the envelope is made of quartz or hard glass, such as Pyrex or the like which, as is well known, is substantially unaffected by the heat of the arc. .In this type of switch, therefore, owing to the hard glass envelope, the electrodes and mercury may be so arranged that a mercury make and break directly on the surface of the envelope may be utilized, the electrodes in these switches being usually arranged in wells or the like formed in the envelope, or so positioned relative to one another that each of them is at all times immersed in mercury so that all of the arcing which occurs occurs directly between mercury and mercury as the tube is tilted or otherwise moved to make and break the circuit. As is well known, a mercury to mercury-make and break is desirable for a number of reasons. Chief among these is the fact that in such a switch the electrodes are not subjected to deteriorating influences of any kind. Then, too, thearcing is less in a mercury to mercury make and break, as is well known. Furthermore, any arcing which does occur in a switch of this type merely results in a volatilization of a minute portion of the mercury at the'point of contact which immediately condenses upon quenching of the arc and flows .back into the main body again. Despite the many advantages incident, to the utilization of a mercury to mercury contact in switches of this character,they have not come into general use principally because of the cost of the, hard glass and the difficulties encountered in hermetically sea1--.

ing'the leading-in wires or electrodes into an envelope made of such glass. r

One of the objects of the present invention, therefore, is to provide a mercury to mercury make and break in a switch of the soft glass envelope type whereby the various disadvantages inherent in-the use of a hard glass envelope may be overcome without sacrificing any of the advantages of such a construction.

With the foregoing in mind, the invention con- 05 templates a mercury'switch comprising a hermetically sealed envelope of any usual or ordinary soft glass composition heretofore employed, electrodes projecting into said envelope and hermetically sealed therein, a body oi mercury movable in said envelope to perform the circuit making and breaking function, together with means for entrapping a portion of the body of mercury in the vicinity of one of the electrodes and maintaining such portion of mercury in contact therewith both when the main body of mercury is in and out of circuit making position, thus ensuring a mercury to mercury make and break upon operation of the switch and complete protection for the electrodes against the deteriorating influences of the arc.

Other objects and advantages of the invention will be apparent to those skilled in the art from a reading of the following specification taken in connection with the accompanying drawing, wherein three forms of the invention are illustrated.

In the drawing:

Figure 1 is a sectional view, taken through a switch constructed in accordance with the present invention and in circuit making position;

Fig. 2 is a sectional-view taken on the line 22 of Fig. 1;

Fig. 3'is a sectional view, similar to Fig. 1, illustrating a slightly different form of switch of the type contemplated by the present invention; and

Fig. 4 is a longitudinal, sectional view of a third form of the invention.

Referring more in detail to the drawing, and first to the form of the invention illustrated in Figs. 1 and 2 thereof, the switch comprises a container or envelope, 10 which, as already pointed out, may be formed of soft glass such as the lead and lime varieties. This envelope is substantially capsule shape provided at its opposite ends with lateral protuberances 11 through the crowns of which the leading-in wires 12 and 13 extend into the interior of the envelope. These leading-in wires may be of the usual copperclad type and are hermetically sealed in the wall of the envelope as at 14 at their points of projection therethrough. The electrodes 15 and 16 arepreferably formed of some wire which is not affected by the mercury, such, for instance, as iron, nickel, tungsten, or the like. These electrode wires 15 and 16 are welded as at 17 and 18 to the leading-in wires 12 and 13 immediately inwardly of 'the seals 14. The movable body of mercury in the envelope bears reference character 19 and,.as willbe observed, in one position, or in other words, the position shown in Fig. 1 of the drawing, this mercury completes the circuit between the electrodes, whereas, as will be observed, upon tilting or oscillation of the envelope into an opposite or reverse position, the mercury will flow to the other end of the envelope, thus interrupting the circuit. The envelope of these switches is generally-filledwith an inert gas such as hydrogen in order to avoid chemical action and to assist in suppressing the arcing which results in prolonging the life of the switch.

Thus far, the switch described is much the same as switches heretofore developed and which are at the present time .in rather general use, and in which the make and break occurs directly between the electrodes and the mercury resulting in, the deteriorating effects above pointed out.-

To overcomethe disadvantages inherent in this type of switch heretofore constructed andto, in reality, transform the same into a mercury to mercury make and break type of switch, it is proposed, according to the present invention, to provide means for constantly, maintaining a portion of mercury around one of the electrodes regardless of the movement of the main body of mercury. In the drawing, this means is shown in the form of a cuplike element 20 having an elongated apertured sleeve or neck 21 formed integrally therewith or welded thereto and through which the electrode 15 extends downwardly into cup 20. This cuplike element 20 may be formed either of quartz or some of the various so-called hard glass compositions so as to render it unaffected by any arcing which may occur. The

e1ectrode,-of course, need not be sealed in the neck 21, it having been found sufiicient to merely pinch or press it around the electrode into gripping or holding position, or in other words, just sufliciently to provide for the supporting of the cup from the electrode substantially as shown. It has been found, in practice, advantageous to tilt the cup slightly so that the open end thereof inclines slightly with reference to the longitudinal axis of the envelope, and it has also been found advantageous to form the openingin the cup of elongated, oval shape substantially as shown in Fig. 2, as this'has proved topre'sent a better contacting surface of mercury at the mouth of the cup at which point the make and break occurs. As will be observed, a portion of the mercury is entrapped in the cup 20 through-, out all operations of the switch and thus inercury is maintained in contact with the electrode 15 at this point. The electrode 16 preferably extends downwardly to a point near the lower wallof the envelope and then forwardly along such wall, as shown, this electrode being in the main body of the mercury for all operations -of the switch. As already explained, the make and break occurs at the mouth of the-cup 20, or to be more exact, over the lower lip of the mouth, and occurs between the mercury in the cupand the main body of mercury as it flows towards or away from the cup, depending upon the direction of oscillation.

. In the switch illustrated in Figure 3, the cup shown'at 30 is reversed, as compared with the cup mounting in Fig. 1, but in other respects is substantially the same as the switch shown in Fig. 1, both in construction and operation, the

mercury to mercury make and break feature being preserved. In Fig. 4, the leading-in wire 40 enters the envelope through the crown of a protuberance or well 41 formed in the lower wall of the envelope and at such point as enables the electrode 42 to be materially shortened as. compared to the corresponding electrodes in Figs. 1 and 3, for instance. This modification is proposed for the handling of higher current values, where it is desirableto have the electrodes as short as possible so as to avoid excessive heating, such as would occur with the use of an elec-'- trode of appreciable length. In other respects, the switch shown in Fig. 4' is substantially the same, both in construction and operation, as that shown in Fig. 3.

From the foregoing it will be understoodthat through the utilization of means for entrapping a portion of the body of mercury and holding such portion in constant contact with one of the electrodes, that a switch has been provided wherein a mercury to mercury make and break is utilized and the resultant advantages thereof obtained, .while still employing the ordinary soft glass envelope. It will be further observed that in the particular construction and arrangement described and illustrated herein, the electrode 15 "is shielded entirely from contact with the mercury except at its lower end which dips into the cup. Thus, the possibility of a so-called splash contact upon oscillation of the envelope is provided against, the only contact possible being between the main body of mercury and that entrapped irr the cup 20 and at the mouth of the cup which, as already explained, is formed of quartz or of hard glass so as to be unaffected by any arcing which may occur.

It will also be observed that the point of make and break, namely in the mouth of.the cup 20, is sufliciently removed from the adjacent wall of the envelope to prevent any injurious or rupturing effect upon the softer glass composing said envelope. a

It will thus be apparent to those skilled in the art that, through the employment of means in association with oneof the electrodes for maintaining that electrode in constant contact with a portion'of the mercury, and the use of quartz or hard glass in the formation of such means, a

mercury switch employing the ordinary soft glass envelope maybe used to secure a mercury to mercury make and break and all of the advantages incident to such a switch without the costliness or the vmany disadvantages inherent in the mercuryto mercury make and break hard glass envelope type-of switch heretofore employed in the securing of these results. The invention, therefore, is chiefly characterized by the provision of constant mercury coverings for the electrodes in a soft glass envelope and the confining of the make and break area, or arcing zone, to a point removed from the walls of said envelope.

'It is intended, therefore, that the invention be broadly interpreted as, of course, it may take many forms other than those illustrated and described, and is subject to many changes and modifications without departing from the spirit or scope thereof. I Therefora'it is' not desired to of shocks and stresses between the envelope and limit or restrict the same except where limitations may appear in the appended claims.

The invention claimed is: t

1. A switch of the character described comprising an envelopeof soft glass, electrodes sealed therein, a body of mercury movable within said envelope, and means for producing a mercury to mercury make and break intermediate said electrodes upon oscillation of said envelope including a hard glass mercury containing element separate from theenvelope and fixedly supported upon the envelope in spaced relation thereto and confining the make and break area or arcing zone to a'point removed from the walls of said -envelope.

2. A switch of the class described comprising an outer hermetically sealed envelope, a movable body of mercury therein, electrodes for making contact with said mercury, and means for causing said mercury to separate and reunite at a point intermediate said electrodes and removed from the walls of said envelope upon bodily movement of said switch, said means being in the form of a cuplike element fixedly suspended from one of said electrodes out of contact with the walls of said envelope and serving to maintain a portion of said mercury in constant engagement with said electrode to thereby ensure a mercury to mercury contact at the mouth of said cup upon operation of said switch.

3. The combination with a switch comprising a soft glass envelope, and a movable body of mercury and electrodes sealed therein, of means for effecting separation of said body of mercury at a point intermediate said electrodes and removed from the walls of said envelope upon operation of said switch, said means comprising an element of arc resisting material fixedly supported within but out of contact with said envelope.

4. The combination with a switch comprising a soft glass envelope, and a movable body of mercury and electrodes sealed therein, of means for effecting separation of said body of-mercury at a point intermediate said electrodes and removed from the walls of said envelope upon operation of said switch, said means comprising an 'element'separate from, fixed within but out of contact with said envelope, said element being of a substance capable of withstanding high temperatures and rapid temperature fluctuations.

' 5. The combination with an electrical contactor comprising a glass envelope, cooperating electrodes sealed therein, and a body of mercury movable therein, of a cuplike element surrounding one of said electrodes and adapted to maintain a portion of said mercury in contact therewith irrespective of the movements of the main body of mercury, said cuplike element having a sleeve through which its associated electrode extends and-by which it is supported from said electrode.

6. The combination with a mercury switch comprising an envelope, electrodes and a movable body of mercury sealed therein, of means associated with one of said electrodes for entrapping a portion of said mercury and holding the same 1 arcing'to a zone removed from. the walls of said envelope whereby the envelope is protected against the action of arcing and the transmission mouth of said cup, the mouth of said cup being slightly inclined and elongated transversely with respect to the longitudinal axis of said envelope.

8. A switch of the character described comprising a soft glass envelope, electrodesjand a body of mercury sealed therein, a cuplike element formed of a substance substantially unaffected by high temperatures or rapid temperature fluctuations and suspended in said envelope from one of said electrodes and out of contact with the walls of said envelope whereby upon operation of said switch an alternating mercury to mercury completion and interruption of the circuit is obtained at the mouth of said cup, said cuplikeelement housing the free end of said electrode and being provided with an elongated extension surrounding and'protecting the remainder of said electrode.

9. In a mercury switch,a soft'glass envelope, electrodes and mercury sealed therein, and means fixed within said envelope andout of contact therewith for producing a mercury to mercury make and break intermediate said electrodes and confining the same to a location removed from the walls of said envelope.

11. A mercury switch of the character described including an outer hermetically sealed envelope and means for producing a mercury to mercury make and break within said envelope and within an arcing zone located at a point'removed from the walls of said envelope and including a protective element constituted of a substance substantially unafiected by high temperatures or rapid temperature fluctuations, said protective element being located within the outer envelope and affording an arcing surface spaced from the outer envelope, and a support for said protective element intermediate the protective element and the outer envelope and serving to maintain the protective element substantially fixed and out of contact with the outer envelope,

while minimizing the transmission of shocks and stresses between the protective element and the outer envelope.

12. A mercury switch of the character described comprising an outer hermetically sealed envelope, a movable body of mercury therein, electrodes for making contact for said mercury and means for producing a mercury .make and break intermediate said electrodes upon bodily movement of said envelope and including a mercury containing element separate from and out of contact with the outer envelopeand fixedly supported with with the tube and the other terminal.

respect thereto, said mercury containing element being of with one of said electrodes whereby to maintain a portion of the mercury in constant contact with its associated electrode and to confine the arcing zone to a point on its surface and removed from the. walls of the, outer envelope whereby to protect the outer envelope and to minimize the transmissionof shocks and stresses between the outer envelope and the hard glass mercury containing element. a v

13. A mercury switch device comprising an enclosing glass envelope, an inert gas filling, a mercury pool, two electrodes sealed through the wall of the enclosing glass envelope, one of said electrodes interiorly supporting a refractory element independent of said enclosing glass envelope, said refractory element being shaped so as to provide means therein when the device is in operating position for retaining about one of said electrodes a part of the mercury as a stationary pool, the remainder of the mercury being retained adjacent the other electrode a movable mercury pool, the flow of which is directed to the said stationary pool of mercury upon applying to the device a tilting motion in' one direction, and means for definitely effecting the separation of said movable pool of mercury from said stationary pool of mercury upon returning the device to the original position subsequent to said tilting motion.

14. A liquid contact switch comprising a sealed tube containing a quantity of electrical conducting fluid with two electric terminals sealed and supported one above the other in one end thereof and a cup of insulating material therein wholly supported by one terminal and having one terminal entering the interior thereof.

15. A liquid contact switch comprising a sealed tube containing a quantity of electrical conducting fluid with lead-in wires supported and sealed in one end thereof, said lead-in wires projecting as terminals within the tube, amp of in sulating material engaged by one terminal and supported at an angle to the axis of the tube thereby so that the cup is slightly tilted in the direction of the opposite end free from contact 16. A liquid contact switch comprising av sealed tube containing a quantity of electrical conducthard glass composition, and associated rate from the container said container, a

separating said terminal from ing fluid with two electric terminals sealedand supported one abovethe other in one end thereof, and a cup of insulating material therein supported by one of said terminals independent of' said tube, one of said terminals entering the interior of the cup.

17. In a mercury switch, the combination with a sealed container, of a refractory. member sepaand supported independently thereof comprising a body having a cavity to holda mercury pool positioned at one end of mercury body below the edge of said cavity, an electrical conductorin contact with said mercury body, and another electrical conductor in contact with said pool whereby, when the container is tilted, the mercury body is, united with said pool at a point located remotely from the walls of said container -to electrically connect said conductors. 18. The combination with a liquid contact switch of the enclosed type having electrodes and a movable body of mercury to bridge said electrodes upon a tilting of said switch, of means associated with one of the electrodes for entrapping a portion of the mercury and holding the same in contact therewith to insure a mercuryto-mercury make and break upon operation of theswitch, said means being formed ofa substance substantially unaffected by high temperatures or rapid temperature fluctuations and supenvelope, and a refractory member surrounding 1 the terminal of said electrode and supported in fixed relation thereto out of contact and direct connection with the walls of said envelope and serving to entrap a portion of said mercury and hold the same in constant contact with said terminal to thereby insure; a mercury-to-mercury make and break of said circuit over the surface of said refractory member upon operation of said switch.

- 7 PAUL K. CRAMBLET.

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