US1668731A - Electromagnetically-operated switch - Google Patents

Description

May 8, 1928. 1,668,731

G. PERRY ELECTROMAGNETIGALLY OPERATED SWITCH Filed July 12. 1920 2 Sheets-Sheet 1 1 12 1 ZZ f l -66 Zfi a -20 P Z &

May 8, 1928. 1,668,731 G. E. PERRY ELECTROMAGNETICALLY OPERATED SWITC H il ly 12. 1920 2 Sheets-Sheet 2 Patented May 8, 1928 UNITED STATES GEORGE ELLIOT FERRY, OF CHICAGO, ILLINOIS,

ASSIGNOR, BY MESNE ASSIG-N MEN TS,

TO UNIVERSAL SIGNAL CORPORATION, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

ELECTROMAGNETICALLY-OPERATED SWITCH.

Application filed July 12, 1920. Serial No. 395,514.

electromagnetinetically operated switches for intermittent-- vention will appear from scale, taken on line 3-3 of ly or periodically completing and interrupting an electric circuit.

It is often desirable to cause a comparatively slow intermittent or periodic completion and interruption of an electric circult, such for example as an electric lamp circuit, to cause the flashing of the lamp or the periodic operation of other electrical ap-- paratus. The circuit should be quickly opened and closed to prevent undue arcing, although there is a prolonged interval between its operations.

One of the objects of this invention is to provide an improved automatically operated electro-magnetic switch.

Another object is to provide a switch which automatically and quickly opens and closes at comparatively long intervals.

Another object is to provide an electromagnetic switch which is adequately enclosed and protected for-severe service.

Another object is to provide a switch which is eflicient and reliable.

Another object isto provide an improved switch which may be readily installed and removed.

Another object is to provide an improved switch mechanism.

Another object is to provide a switch particularly adapted for isolated installations such asstreet, highway and railway signals.

Another object is to provide a switch which will operate on an exceedingly small amount 01 current.

Another object is to provide a switch which will require a minimum of attention to give proper service over long periods of continuous use.

Other objects and advantages of the inthe following description and claims.

An embodiment of the invention is illustrated in the accompanying drawings, wherem:

Fig. 1 is a vertical, through the switch.

Fig. 2 is a horizontal 22 of Fig. 1.

Fig. 3 is a horizontal section, on a larger Fig. l.

longitudinal section section taken on line Fig. 4 is a vertical section of the switch mechanism taken on line of Fig. 3, with the switch open.

Fig. 5 is a similar closed.

Fig. 6 is a side elevation of the switch mechanism, and

Fig. 7 is a diagram oi connections showing one use of the switch.

The electromagnetic switch comprises, in general, a tight, rigid casing, which encloses an electromagnet having an energizing winding, a circuit interrupting switch mechanism providing abrupt opening and closing of the circuit controlled thereby, mechanism for causing comparatively long in tervals between operations of the switch, and terminals projecting from the casing for ready and convenient connection and disconnection. I

The casing is formed of a closed piece of pipe 10 of suitable metal, threaded at its open end to receive a threaded metal ring 11. The open end of the pipe is closed by disc 12, held against the edge of the pipe by the ii'lturned flange of ring 11. Disc 12 is made of suitable insulating material, such as fiber, and serves to assist in supporting and insulating three terminals 13, I l and 15.

The electro-magnet is provided with a magnetic core 18 in the form of a cylindrical rod. Core i8 has its lower end reduced and inserted into the end of and secured to a non-magnetic metal tube 19. Secured to the upper end of core 18 is a ring shaped magnetic head 2O. A ring shaped magnetic head 21 is also secured to the lower end of core 18. 'Wound upon the spool formed by core 18 and heads 20 and 21 is an energizing coil or winding Fiber washers 23 separate the winding from the magnetic heads 20 and section with the switch Non-magnetic tube 19 and the opening through head 21 form a chamber in which is slidably mounted a plunger armature 25. Armature 25 is provided with a small axial opening 26 therethrough and has a non-magnetic disc 27 at the top thereof. Disc 27 also has an axial hole therethrough and serves to prevent the armature from freezing to the end of core 18 when attracted thereagainst.

Magnetic head 21, which may be made in two sections, has the lower end of its axial opening enlarged and within this enlargement fits a non-magnetic piston head 30. The lower end of armature is provided with a reduced extension 31 terminating in V a slightly enlarged disc 32. Piston head,

is suitably secured to armature 25 at the beginning of the reduced extension. An opening 33 extends radially through armature 25 from opening 26 just above piston head 30. The chamber above armature 25 and piston head 30 is vented through the armature by openings 26 and The lower end of opening 26 is provided with a valve Consisting of a small metal disc 34. Disc 34 is notched on opposite sides and is retained in position adjacent the lower end of opening 26 in armature 25 by means of a U-shaped stop The legs of stop are suitably secured in disc 32 of the armature and lie in the notches of valve 34. If desired, disc 32 may be provided with a slight annular projection around the rim of opening 26 to form a seat for the valve.

The armature and piston head form with the chamber in the lower end of the electromagnet, a'fiuid pressure chamber which acts as a dash-pot to retard the downward movement of the armature when the electro-magnet is de-energized. V

When the armature is in its lowermost po sition and the electro-magnet is energized, the flux passes upwardly through core 18, then radially outward through upper head 20, downwardly through casing 10, radially inward through lower head 21, upwardly through plunger armature 25 and across the air-gap between armature 25 and core 18 back into the core. The magnetic circuit is thus comparatively closed, being'composed largelyof magnetic materiah lVhen the armature rises, the armature and piston head force the air in the chamber out through openings 26' and 33 past valve 34. The pressure of the compression forces valve 34 from'its seat allowing the ready escape of air. When the magnet is deenergized with the armature in its uppermost position, the armature begins to fall. Air tends to rush into the chamber above armature 25 and piston head 30 through openings 26 and 33. However, the pres sure of the air outside of the chamber forces valve 34 against its seat which closes the air passage into the chamber. This restricts the flow of air into the chamber, the only passage therefor being around the outside of piston head 30 which has a sliding fit with the inside wall of the enlarged portion of the chamber, and materially retards the downward gravity forced movement of the armature. The movement of the armature is thus comparatively rapid in its upward course and comparatively slow in its downward travel.

The switch mechanismis mounted upon a supporting base formed of a disc 40 of insulating material such as fiber. Disc40 is secured to the lower end of the magnet by screws 41 which pass through spacing sleeves 42. Spacing sleeves 42 may be made of suitable material such as fiber. Two of these sleeves may serve as insulating ducts through which pass conductors 43 and 44 from terminals l3 and 14 respectively.

Mounted upon the inner side of disc 40 are three small metal posts 45, 46 and 47. Each of these posts is provided with a circumferential groove near its top. A metal plate 48, having a pair of openings whose edges lie within the grooves in posts and 46, is pivotally mounted upon posts 45 and 46. Plate 48 has secured thereto a small insulating block 49. Block 49 has secured to its underside an adjusting plate 50. Plate 50 is formed with a small. flexible tongue 51. Disc 32, on the end of armature 25, is loosely positioned between platev 48 and tongue 51 so that the plate and block 49, although unconnected with the armature, are pivotally oscillated thereby as the armature moves up and down.

A spring 55, which may be made of any suitablespring metal, has at one end a hole 56 which fits over the end of post 47. The edge of hole 56 lies in the groove in post 47. Intermediate its ends, spring is provided with a curved portion 57 so that the spring does not interfere with the armature. The opposite end of spring 55 is bent into a loop 58, the end of which lies ina notch 59 in plate 48. One face of spring 55 near the end of loop 58 has a small notch 60 which embraces the rear edge of the notch in plate 48, providing a flexible and readily separated coupling thcrebetween. Spring 55 biases plate 48 to either of its extreme positions shown in Figs. '4 and 5. When the plate is actuated by the movement of the armature,

the armature'acts against the force ofspring 55 until the plate passes its mid position or dead center. Thereupon the spring forces the plate to its extreme position with a quick snap action, independently of and unretarded by the armature. i

Disc 40 carries a bracket having a pair of upstanding ears or lugs 66. Lugs 66 are provided with small depressions in which are seated the ends of a pair of pivot pins 67. Pins 67 are carried by an arm 68. Se-

cured to arm 68 are a pair of flexible switch clips 69. Clips 69 form the movable contact of the switch mechanism.

The fixed contact of the switch mechanism comprises a blade 70 projecting upwardly" from a support 71, which is mounted upon disc 40. 'When the switch is closed, clips 69 engage and press upon opposite sides of blade 70, as shown in Fig. 5. The closing of the switch is accomplished by a wiping action which insures the removal of dirt and the making of a good electrical contact. When the switch is opened, clips 69 are separated from and lie above blade 7 0 as shown in Figs. 1, 4 and 6. Clips 69 are moved to open and closed position by plate 48 through a yoke 72 carried by arm 68 and which is bifurcated to fit over and loosely embrace the upper and lower sides of block 49.

Fig. 7 shows diagrammatically a system of connections for causing the intermittent or periodic flashing of an electric lamp. The lamp L is connected to terminals 14 and 15. Terminal 15 is also connected to one terminal of winding 22. Terminal 14 is also connected to fixed contact 69 and the other terminal of winding 22. A source of current such as a battery B is connected to terminals 13 and 15.

The operation of the switch in connection with the system chosen for illustration is follows:

With the connections as shown in Fig. 7 the switch is closed. Current flows from positive battery to terminal 15. There the current divides, part flowing through winding 22 and part through lamp L illuminating the same. The current then reunites and passes through movable contact 69 and fixed contact 70 back to terminal 13 and then to negative battery The current through winding 22 energizes core 18 which attracts armature 25. Armature 25 rises against the force of gravity. unhampered by any of the switch contact mechanism and therefore without load at the beginning of its travel. After a short range of unrestricted travel its disc 32 engages plate 48, and the plate is pivotally rocked about its axis, initially by the armature and subsequently after a predetermined travel by spring independently of the armature. Plate 48 carries block 49 upwardly and when the block strikes the upper fork of yoke 72, arm 68 and clips 69 are moved about their common axis through pivot pin 67. WVhen plate 48 passes the mid point of its movement, spring 55 snaps the plate to its extreme position and clips 69 and blade 70 are quickly separated. After the armature has moved plate 48 just past the mid point the Work of opening the switch is taken up by spring 55 which, because of the fact that the armature is unconnected from any part of the contact mechanism, is unhampered by the armature.

The breaking of the contact between clips 69 and blade 70 opens the circuit through both winding 22 and lamp L. The lamp is extinguished and core 18 is de-energized.

The de-energization of core 18 allows gravity to return armature 25 to its lowermost position. This movement, however, is comparatively slow due to the action of valve 13 as hereinbefore described. After the armature falls to the point where disc 32 engages tongue 51, plate 48 and block 49 are rocked in the reverse direction to open the switch. WVhen the lower fork of yoke 72 is engaged by block 49, the switch starts to close and after plate 48 passes its mid position, the action of spring 55, unhampered by the armature, causes the closure to take place with a quick snap action. The closure of the switch again completes the circuit, the lamp is again illuminated and winding 22 is again energized. This automatic periodic opening and closing of the switch and circuit continues until the main circuit from the battery is opened by a suitable manual switch.

The electromagnet and switch mechanism, being housed in a rigid, strong weatherproof casing, is well protected against damage and admirably adapted for use in isolated places. The relative time the switch is open and closed may be varied to suit conditions by adjusting the closure of valve 34 and by bending tongue 51. Ordinarily good results may be obtained by making the time the switch is closed and the lamp is illumi nated considerably less than the period the switch is open and the lamp is dark.

Having described my invention what I claim as new and desire to secure by Letters Patent is z- 1. An electromagnetic switch having an electromagnet, a movable armature therefor, pressure controlling means for retarding the movement of the armature in one direction, switch mechanism opening and closing with a snap action and actuated by the armature to initiate both operations, a tight metal casing housing and supporting the electromagnet armature and switch mechanism, and terminals projecting from the casing.

2. A switch comprising a cylindrical metal casing, an electromagnet fitting snugly with in said casing, and having a chamber at one end, a plunger armature fitting within the chamber, a valve for closing the chamber and retarding the movement of the armature in one direction, a support carried by the electromagnet, switch contacts carried upon said support, and a spring tensioned lever system cooperating with the armature and the contacts to open and close the same with a snap action.

In testimony whereof I hereunto subscribe my name.

GEORGE ELLIOT PERRY.

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