US1754494A - Electric switch - Google Patents

Description

April 15, 1930. c, ANDERSON ET AL 1,754,494

' ELECTRIC SWITCH Filed March 26, 1927 3 Sheets-Sheet l kfsasse C. 05 077?,

April 15, 1930. c. A. ANDERSON El AL 1,

ELECTRIC SWITCH Filed March 26, 1927 3 Sheets-Sheet 2 Carl/ flnderaon 556 C 0550772 April 15, 1930- c. A. ANDERSON Er AL 1,754,494

ELECTRIC SWITCH UIIIIIIIIII frwanfof' Carlfl flndcrsorz, 5.56 61 0650777,

Patented Apr. 15, 1930 hdhdi area CARL A. ANDERSON AND JESSE C. 08130311, 013 ST. JCELFI'I, MICHIGAN, ASSIGNORS TO RELIANCE ELEVATOR COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLI- NOIS ELECTRIC SWITCH Application filed. March 26, 1927. Serial No. 178,722.

Our invention relates to devices for opening and closing electrical circuits, and more particularly to such devices where the circuit is opened under load. g

It is an object of this invention to provide a device of this character wherein the eX- cessive sparking due to breaking the circuit is materially reduced and wherein the damage to the contacts due to such sparking is substantially avoided.

Another object of our invention is to provide a circuit making and breaking device which will eliminate the uses of solid contacts such as the copper to copper or copper to carbon contacts and which will also eliminate the danger of the contacts freezing or locking in closed position due to the current welding them together. Various devices have been provided in an attempt to overcome the chiliculties encountered when an electrical circuit carrying acomparatively large current is broken. Contacts including copper as one electrode and carbon as another or a plurality of carbon electrodes have been used, but in each of these the contacts are rapidly worn away by the sparking and excessive heating when the circuit is broken. This makes it necessary to replace such contacts at frequent intervals, and in the case of the copper contacts the dang r of the contacts becoming so hot that hey melt and run together is always pr sent. To eliminate these difficulties, we rave provided a circuit closing device wherein condu ting fluid such as mercury is utilized for the electrodes or contacts and the circuit is made and broken by the contact and separation of two bodies of mercury, each of which. is normally completely insulated from the other and connected to one side of the line.

The principal object of this invention, therefore, is to provide a circuit closing device of this character wherein the circuit is broken, not by the separation of two solid contacts or a separation of the solid contact from a liquid contact, but by separating the two bodies of conducting liquid so as to eliminate all possibility of contacts freezing together.

A further object of this invention is to provide a device of this character wherein any iumber of circuits may be simultaneously opened and closed with a single movement of the switch operating mechanism. This. is accomplished in the present instance, by providing in a single controller drum a number of pairs of mercury contacts, each of which is entirely independent ofthe other in so far as electrical connection is concerned, but all of which move together as a unit.

Another object of the invention is to provide a alurality of bodies of mercury adapted to serve as electrodes within containers which are normally insulated from each other, but which by moving the mercury therein may be brought into electrical contact by causing the bodies of mercury to join each other through a port connecting the containers.

it is a further object of this invention to so construct and arrange the mercury containers and the connecting ports therebetween as to always insure that the contact between the two bodies of mercury will be made at a point which is open to the atmosphere so that upon breaking the contact any gas that may be discharged may readily escape without blowing the mercury outwardlyin small particles.

In carrying out the invention, we provide a plurality of the mercury contacts within containers that are arranged in a horizontal line and carried as a unit by means of a shaft which is supported upon suitable standards whereby the mercury may be shifted from one portion to another of the container to bring the same into contact through the va rious ports connecting the containers.

As shown, the device is applied to a reversing switch mechanism which is adapted for reversing motors by switching the leads thereto in a manner that is well known in the art. However, the device is not limited to such use, since it is obvious that the principle may equally well be applied to devices for changing the speed of motors or to a combination reversing switch and change speed device, and in various other places where it is necessary to provide means for opening and closing the circuit which carries a large amount of current.

-'phase induction motor (not shown).

1n the drawings:

Fig. 1 is a plan view showing the manner in which the terminals of the circuit are connected to the device;

Fig. 2 is a section on the line 22 of Fig. 1

Fig. 3 is a sectional view on the line 33 of F ig. 2'illustrating the construction of the mercury containers and the position of the mercury therein;

Fig. 4 is a similar section showing the container shifted to bring the body of mercury in position to make contact through the port connecting it with the next container;

Fig. 5 is a section on the line 5.5 of Fig. 4 illustrating the manner in which the circuit is closed over a three-wire system; and

Fig. 6 is an end view illustrating means for preventing too sudden reversal of the switch mechanism. I

Referring now in detail to the drawings, the numeral 10 represents a pair of angle irons whichserv'e as a support for the device. Projecting upwardly from this support are the standards 11', one of which is shown in Fig. 2, which serve as a support for the drum to permit the device to rock back and forth. This rocking action may be accomplished by hand or by any suitable power means. Any suitable stop means may be provided to limit the rocking movement, as in the device shown it is only necessary that it rock through an angle of 189,

In carrying out the invention, we provide a rotatable drum having a plurality of recessed castings 12,13, 14, 15, 16, 17 and 18, which are constructed of cast steel and may be coated with copper or other suitable material to provide a good contact surface, and these castings are separated by means of the insulating disks 19, 20,21, 22, 23 and 24, which together with the recesses in the castings make up the drum and complete containers for the bodies of mercury illustrated therein.

It will be noted that the containers 15, 16 and 17 are inreality double containers separated by a web so as to provide two bodies of mercury between the insulating disks adjacent thereto.

The shaft shown at the right end in Figs. 1 and 2 and designated by the numeral 25 is a hollow shaft through which the leads of the circuit may be inserted, and these leads, which are insulated in any well known manner, as shown in Fig. 1, pass through the insulating disks and are connected to the desired containers in a manner which will be presently explained. As illustrated, there are six of these leads showing a connection for a three- The lead 26 is a line lead, and is connected to the container 12. The lead 27, another line lead,

is connected to the container 15; and the lead 28, being the third line lead, is connected to the container Going now to the load or motor side, the lead 29 is connected to coning for the escaping of the tainer 13, lead 30 is connected to container 16, and lead 31 has a common connection to containers 14 and 18,.

Nowif it is desired to reverse the motor, assuming that circuit is completed between leads 2.6 and 29, the leads 27 and 31, and leads 28 and 30, it is only necessary to reverse the connection of two leads in order to reverse the motor. The connection just hereinbefore set forth is shown as made in Fig. 5, wherein the body of mercury as illustrated connects containers 12 and 13 so as to close circuit between conductors 26 and 29. and the mercury connects containers 15 and 14 so as to close circuit through 27 and 31, and the mercury containers 17 and 16 connect to close circuit between lines 28 and 29.

Now, if the mechanism is rotated through a half-turn so as to change the mercury from the position shown in Fig. 4, where it is in the lower recess 37 of the container, to the upper recess 38, connection will be made as before, between conductors 26 and 29 through the port 39, and connection is made between conductors 27 and 30 through the port 40, which is the reverse from the previous connection, and a third line connection is made between conductors 28 and 31 through the port 41, between containers 17 and 18. This reverses two of the leads and will eii'ect re- 'ersal of the motor in a well known manner.

It will be noted from the levelof mercury shown in Figs. 3 and 4 that even at the pointof full connection the ports connecting the various containers are not submerged in mercury. This is accomplished in filling the device with mercury by testing the level by means of the testing screw 42, which is removed, so that upon filling the containers up to the level of the screw opening at 42, a constant level may be obtained in all of the containers. Limiting the level in this manner prevents the submerging of the ports between the various containers and enables any gas which is given off to escape upwardly and outwardly through the channels 44 and 45 through a vent at 46, which, as shown, is closed by a screw, which may be entirely removed or may be slotted to provide an open- The path through which gas must pass in escaping will prevent the carrying of any particles of mercury therewith, and these particles will be trapped within the containers and returned to the main body of mercury upon returning thedevice to normal position, as shown at Fig. 3.

From the above description it will be apparent that the different bodies of mercury when the device is in the position shown in Fig. 3 are completely separated from each other by means of the insulating disks and that no contact will be made between the bodies until the device is tipped so that the mercury runs upwardly into the portions 37 ing of the mercury so that upon final breaking of the circuit the resistance has so in creased that very little sparking occurs. The entire making and breaking of the contacts is made from mercury to mercur and this eliminates any of the diiiiculties that have heretofore been encountered where contactwas made between a metallic solid electrode and a mercury body, which resulted in the solid contact being gradually eaten away due to the sparking and action of the mercury when vaporized under this sparking.

To provide for means to withdraw the mercury from the device, we provide each container at the bottom thereof with an opening, as shown in Fig. 3 at 47, which is normally closed by means of a screw, but which when removed permits the mercury to drain out and in this way to be withdrawn and renewed whenever desired, However, since the mercury is substantially entirely encased and is not deteriorated to any appreciable extent by the making'and breaking of the contact, it has been found to stand up for a very long period of time without any appreciable loss in quantity or without any serious deterioration. In fact, in a test of one of these devices wherein live pounds of mercury was used and the circuit was made and broken ten thousand times, with the circuit carrying about sixty amperes, the loss of mercury was so small that it was diificult to measure.

In order to prevent too sudden reversal of the switch so as to throw too heavy a strain upon the motor, we provide means for stopping the rotation of the device at too great a speed from one position to the other. This means, as shown, consists of a depending finger 4E9 carried by a collar on the end plate 51 of the device, and on the supports 10 is provided an upstanding plate 52 carrying a pivoted weight member 53 having the proJections at and 55 thereon. These projections support the pivoted arms 56 and 57, pivoted at one end to the plate 52 in such a manner that upon movement of the finger 49 over either the arm 56 or 51, the weight 53 is moved out or" normal resting position and pushes the other arm upwardly into the path of the finger 49, where it will remain until the member 53 is returned to normal position.

By this construction, if the device is rotated from one circuit closing position rapidly to normal position and presses down one of the arms 56 or 57, the other arm will prevent its passing onward until a sufiicient time lag has occurred to give the weight 53 a chance to return to normal position, and this prevents a sudden swing from one set of contacts to the other to make a sudden reversal of the motor.

The disks and containers making up the device are held together by the bolts 58, 59, 60 and 61, which pass longitudinally through the disks outside of the containers, as shown clearly in Figs. 3 and 4c and press the end plates 51 and 62 tightly against the insulating disks so that the containers are clamped rigidly therebetween.

As shown in Fig. 2, the castings are oifset below the axis of rotation of the drum, when in normal position. The eifect of this is to place the center of gravity of the device in such a position as to always cause the drum to return to neutral or open circuit position when the means for holding it in either extreme position is released.

This structure makes a simple contact de-- vice which will not become disarranged under service conditions and which may be readily accessible for any repairs necessary to the leads or for the withdrawal ofthe mercury from the containers.

While we have shown one form which our 'nvention may take, we wish it to be distinctly understood that we do not intend to limit ourselves to the exact details shown and described, but that we intend to include as part of our invention all such modifications as come within the scope of the claims.

lVe have found that, in actual use of this device, the mercury contact bodies do not heat up as much as the conductors under a con tinuous load. This is due to the fact that when the circuit is closed the length of the mercury through which current passes is very small while the cross-sectional area is quite large in comparison. Also, the device is so constructed as to permit any hot gases given off in opening circuit to escape, and this aids in keeping the device cool. The metal castings are also good heat conductors and serve to rapidlydissipate any heat due to the current.

Having thus described our invention, what we claim and desire to secure by Letters Patent ofthe United States is:

1. A device of the character described comprising a plurality of plates having recesses in the side faces thereof, insulating disks separating said plates and covering said recesses, bodies of mercury in said recesses normally insulated from each other by said disks, means for connecting said bodies of mercury to electric circuits, certain of said disks bein provided with ports therethrough connecting the adjacent recesses, said ports being normally spaced from the mercury in said recesses, and means for changing the relative position of sa1d mercury and said recesses to hung the ad acent bodies thereof into contact through said ports.

2. A device of the character described comprising a plurality of metallic plates having recesses in the side faces thereof, insulating disks separating said plates and covering said recesses, bodies of mercury in said recesses normally insulated from each other by said disks, terminals on said plates for connect ing said bodies of mercury to electric circuits, certain of said disks being provided with ports therethrough connecting the adjacent recesses, said ports being normally spaced fromthe mercury insaid recesses, and means for changingthe relative position of said mercury and said recesses to bring the adjao'e'nt bodies thereof into contact through said ports.

3. A device of the character described comprising a drum mounted to rock on a horizontal axis, said drum having a plurality of transversely extending compartments therein, each compartment having one wall thereof formed of insulating material and separating it from the nextadjacent compartmei c, said compartments being partially filled with mercury, wiring terminals carried by said drum and electrically connected to the mercury in said compartments, certain of said insulating walls having ports therethrough offset with respeot'to the axis of rotation of said drum and normally above the level of mercury therein, and said drum being rockable about its axis to bring the mercury in certain pairs of said compartments into engagement through said ports, the center of gravity of said drum being spaced from the axis of rotation thereof and spaced from said ports so that the drum when free will move said ports above the level of the mercury in said drum.

4. An electric circuit controlling device comprising a drum having a plurality of compartments therein, said compartments belng partly filled with mercury, insulating means separating said compartments, said drum being adapted for connection'to a suitable rocking means to shift the mercury in said compartments, said insulating means being apertured to provide means for bringing the mercury in different compartments into contact in one position of said drum, said drum having its center of 'ravity olfset relative to its rocking axis so as to rest in a position holding the apertured portion of said insulating means above the level of mercury in said compartments upon release of said rocking means.

5. An electric circuit controlling device comprising a drum having a plurality of com partments therein said compartments being partly filled with mercury, insulating means separating said compartments, said drum being mounted for rocking movementto shift tliemercury in said compartments, said inm'ercury, one of said partitions having an aperture at one side of said axis and another of said partitions having an aperture on the opposite side of said axis, said drum having a weighted portion normally holding said drum in position to prevent contact between adjacent bodies of mercury through either of said apertures, said drum being rockable about its axis in either directionto bring mercury in the adjacent compartments into contact through said apertures.

'i. A device of the character described comprising a drum pivoted about a substantially horizontal axis, a plurality of transversely extending compartments in said drum, insulating partitions between said compartments, saidcompartments being partly filled with mercury, one of said partitions having an aperture at one side of said axis and another of said partitions having an aperture on the opposite-side of said axis, said drum having a weighted portion normally holding said drum in position to prevent contact between adjacentbodies of mercury through either of said apertures, said drum being rockable about its axis in either direction to bring mercury in the adjacent compartments into contact through said apertures, and means automatically operating to prevent a sudden rocking of said drum from position closing contact through one aperture to position closing contact through the other aperture.

In witness whereof, we hereunto subscribe our names this 7th day of March A. D. 1927.

CARL A. ANDERSON. JESSE C. OSBORN.

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