US1658013A - Mercury switch - Google Patents

Description

Jan. 31, 1928. 1,658,013

R. W. ARMSTRONG ET AL MERCURY SWITCH Filed Dec. 9

ag/nu WWMM "enemies Jen. a1, 1928.

UNITED STATES "ltdtdllii PATENT OFFICE.

navluonn w. nnius'raoive niun IRA n. MQGABE, or orIIoneo, ItmnoIs; sari) Amu- 'STRONG,ASSIGJZIOR Tl) THE ILLINOIS.

UOZNTAGT CGMPANY, A CORPORATION OF MERCURY swrrcrr.

Application filed December 16, 1922. Serial No. 60'?,303.

The present invention has for its object to improve in certain respects small mercury switches that have heretofore already been brought to a comparatively high state of periection. 'ihe mostpractical form of this kind of a switch is one in which a small body oft mercury is contained in a sealed glass tube having within the same terminals connected to suitable leadein wires, which a terminals are adapted to be connected together by the mercury when the tube is laid on its side and tipped to the proper angle. l.hrough "the use of an inert gas in the tube and properly purified iron terminals, switches of this kind are now enabled to handle currents as great as 10 amperes at 110 volts. Naturally, during the making and breaking of the comparatively heavy cur rents, strong arcs are produced within the switches. invention 'is to produce a simple and novel proportioning of the parts of such mercury switches that no arcs that can be formed during the making and breaking of the normal currents can have any injurious effect or even reduce the sensitiveness of action where sensitiveness is required.

The various features of novelty whereby our invention is characterized will hereinafter be pointed out with particularity in the claims; but, -for a fullunderstanding of our invention and of its objects and advantages, reference may be had to the following detailed description taken in connection with 3; the accompanying drawing, wherein:

Figure 1 is an elevation of a single-circuit or one-way switch arranged in accordance with our invention;

Fig. 2 is longitudinal central section through the switch shown in Fig. 1, on a somewhat larger scale, in its closed position;

li ig. 3 is a view similar to Fig. 1 showing a double-circuit or two-way switch embodying ourinvention;

Fig. 4 is aview, on an enlarged scale, of a fragment of theconnection between a terminal of one of the switches with the corresponding conductor or cable; and

Fig. 5 is a sectiontalren on line 5-5 of Fig. 4-.

Referring to Figs. 1 and 2 of the drawing, 1 represents a glass tube closed at the cndsand sealed and containing a small body of mercury 2. Near one end of the tube,

One of the objects of the present and within the same, are two terminals 3 and a, spaced apart in the direction of the length of the tube. The terminals are preferably in the form oi small blocks of iron i'astened to the inner ends of suitable leading-in wires 5 and 6 that pass through the wall of the tube. Thus the terminals may be said to project inwardly from one side of the tube towards the opposite side, from which latter side, however, they are spaced apart. The tube is preferably filled with hydrogen, an inert gas, or any gas which will not react with the mercury or the terminals 111 a way to decrease the eiliciency of the switch, although this constitutes no part of the present invention. The parts are so proportioned that when the tube is held with its long axis inclined slightly to the horizontal, with the leading-in wires at the top, the mercury will either lie in the end remote from the tern'iinals, as shown in Fig. 1, or in the end containing theterminals, as shown in Fig. 2; electrical connection between the two terminals being interrupted in the first position, while in the second positron the two terminals are electrically connected together.

Generally speaking, all that we have here tofore described is old, our invention consisting of refinements which we shall now describe.

hen the switch is tilted from the positron shown in Fig- 1 to that shown in Fig. it the mercury engages the farthest terminal 4t before it does the other terminal, the current will ump across the gap between the underlying mercury and the terminal 3 as soon as this gap becomes small enough. In other words, the current will flash from the terminal 3 to the mercury and, where the current is comparatively heavy, the eftect of the flash into the middle of the body of mercury sometimes causesa division of the mercury into two bodies and allows the flash or are to strike against the underlying glass. Even ii 110- further harm should comb from the action just described it would at least result in a failure of the switch to function in the mostetlicient manner at the instant when it should function, because the flash and partial or total separation of the mercury into two bodies would momentarily delaythe completion 0:1? the circuit which is closed by the switch. l/Ve have also found (ill that at times when the switch moves from the closed position. or. Fig 2 to the open position of Fig. 1 a globule 0t mercury remains, at least momentarily, to bridge the gap between the two terminals, so that the circuit is not broken as promptly as it should be. 7

Ve have discovered that the objections just mentioned can be overcome by a simple proportioning of parts which will insure that contact will always be made first at the terminal and will always be broken last at this terminal. We therefore form the terminal l with a blunt rounded end and the. terminal 3 with a tapered or pointed end, and locate the terminalfi somewhat closer to, what may be termed the bottom side o'f the tube than we do the terminal 4:. The result is that when the switch is tipped from the'position shown in Fig. 1 to the other position, even though very slowly, the mercury must touch the. pointed end of the one terminal before it is possible for it to reach the other terminal. Because of the e of thepointed terminal it oli'ers little eslstancet o the movement of the mercury tl'aveling-past it to the other terminal, and therefore the mercury retains its momentum as it approaches the second terminal. As soon. as the mercury comes close enough to the second terminal an arc may form between the mercury and the terminal; but the force of the arc is. opposed by the entire body or mercury inmotion and the movement of the mercury will therefore not be perceptibly checked and there will be no delay in completing the circuit. On the other hand, the same arc, if powerful enough, extending. between the first terminal 51min point perhaps midway between the .ends ot'the body of mercury, would break the body otmercurv in two and drive the parts away from each other, so as not only to delay thefcoinpletion. of. the circuit but also to exposev the glass to the action of the arc. l lz'l' en the switch tipsback towards its open position the mercury does notadhere to the p(' inted .terminal as it does to a rounded terminal. Therefore, by makin the terminal t bluntand rounded, the merci: will adhere to the latter asthe switch swings toward. its openposition, but is'pe'rmitted by the pointed terminal to stretch itse'lt into an attenuated form until finally the effect of gravity willfbe suliicient to break the mercury away fromthe rounded contact by a quick snap action; the tube being long, enough to permit the break to occur betore the mercury strikes theiend of the tube remote from the terminals. Furthermore, the rapidity of theb'reak is not dependent upon the speed at which the tube is tilted, but the break is always effected, instantaneously, The effect just described is made even more pronounced by reason of the fact that the arcing is alarea of the latter until the break comes.

llhereil'ore, l'recause oil the unique conditions just described in the malrinu and breaking or the circuit, the current-carrying capacity of our improved switch is very much greater than in previous switches ol this u'eiurral type. due to the fact that the arci upon making and breaking the circuit is reduced to a minimum and is undcr control. and the i ""her fact that when the circuit is complete and current 'l'lowingr, the cll'cctivc portion of the circuit within the switch is always or large crossscctional area.

Since the mercury cannot adhere to the pointed tern'iinal because oi the shape ot the latter, and further because it docs not become coated with a film 01 n'iel'cury, all danger oi? having a globulc of mercury remain bridged between the two terminals upon the tilting of the switch to its open position, is avoided.

instead of having a singrlocircuit controlled by a switch we may of course control a plurality of circuits; Fig. 3 llustralinu a two-way switch, or one controllimi; two cir cuits one of which is always closed when the other is open, and vice versa. The tube 8 contains the QlOlllllG of mercury and. in addition to the tcrn'iinals 3 and la one end. has a sin'iilar set fl and 10 at the other end. The two rounded or blunt terminals arrthe two that are farthest apart, while the pointed terminals lie bctwruzn the other two. 'lfherelorc, whcnercr the cjlobulc ol mercury is moving toward either end oi the tube For the purpose o'li conneclilur lopjclhcr thc lcrmiuals in lhat end, it will always one 33clirstwith the poin'lcll turninal, which s s ill dead, so that the force ol :1 llosh will be opposed by the weight andv momcutum ol 'hc entire body oi mercury ll such a llush finally comes between the roundcd l'crminal and the body of mercury, which is the only point at which it can come.

In Figs i and 5 wehave illust 'ated one of the connections between a leading-in wire and the corresponding terminal. ill reprcsenting a braided tubular conductor into which the end of the leading-in wire is litted. lhe men'iber 11. as shown is made up of two concentric'tuhes or sleeves, but the number of such tubes or sleeves will depend upon the service to which the comluctor is to be put. The conductor is covered with suitable insulating material 12 of any usual or suitable type, which will not intcr'lcre with the flexibility ot the conductor.

neaaoie it While we have illustrated and described with particularity only a single preferred form of our invention, with a slight modification, we do not desire to be limited to the exact structural details thus illustrated and described; but intend to cover all forms and arrangements which come within the terms employed in the definitions of our 1nvention constituting the appended claims.

We claim:

1. A mercury switchincluding a body of mercury and two terminals adapted to be brought successively into Contact with said mercury and to be disengaged therefrom in the reverse order, that terminal which is the first to make contact with and the last to break contact with the mercury being, pointed at the end and the other terminal being blunt at the end.

2. In combination, a receptacle, a body of mercury in said receptacle, two terminals proiecting downwardly in said receptacle and adapted to be brought successively into contact with and to be connected together by the mercury when the receptacle is tipped from one predetermined position into another predetermined position, that terminal whicl'i is thelirst to make contact with the mercury when the receptacle is so tipped being pointed at the lower endand the other terminal being blunt at the lower end.

3. In combination, a receptacle, a body of mercury in said receptacle, two terminals projecting downwardly in said receptacle and adapted to be brought successively into contact with and to be connected together by the mercury when the receptacle is tipped from one predetermined position into another predetermined position, that terminal which is the first to make contact with the mercury when the receptacle is so tipped being pointed at the lower end and being spaced apart from the bottom of the receptacle a lesser distance than the other terminal.

4.. In combination, a receptacle, a'body of mercury in saidreceptacle, two termiterminal which is the first to make contact with the mercury when the receptacle is so tipped being pointed at the lower end, the other terminal having a blunt, rounded lower end, and the rounded terminal being spaced apart from the bottom of the receptacle a distance greater than the distance between the other terminal and the bottom of the receptacle.

5. In combination, a sealed tube; two terininals, spaced apart in the direction of the length of the tube, projecting from one side of the tube near one end thereof partly across the tube, the terminal nearest said end of the tube being shorter and having a blunter end than the other terminal; and a small body of mercury in the tube adapted to connect said terminals together when the tube is held in a predetermined position and to lie out of contact with both terminals when the tube is held in another position.

6. In combination, a sealed tube; two tori'ninals, spaced apart in the direction of the length of the tube, projecting from one side of the tube near one end thereof and partly across the same, the terminal nearest said end of the tube being shorter than the other terminal so as to be spaced apart from the opposite side of the tube a greater distance than said other terminal; and a small body of electrical conducting fluid in the tube adapted to connect said terminals together when the tube is held in a predetermined position and to lie out of contact with both terminals when the tube is held in another position. v

In testimony whereof, we sign this spccilication.

RAYMOND "W. AltlilSllTRONG. IRA E. MGCABE.

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