US2450924A - Electromagnetic switch - Google Patents

Description

Oct. 12, 1948'. w. E. STILWELL, JR

ELECTROMAGNETIC SWITCH 2 Sheets-Sheet 1 Original Filed Feb. 8, 1941 K/ 7/4 4 N N.

. D LEEEEE SHE 35252 INVENTOR Will m E.5ri|we||,Jn BY 9 v m 1 Oct 194$ w STILWELL, JR 2,450,924

' nwcwnopmnnnc swn'cu Original Filed Feb. 8, 1941 2 Shoots-Sheet 2 Low VOLTAGE SOURCE INVENTOR I .v f wanna ESTilWelLJr.

. BY 1;! ,i w ke HI TORNEY Patented a. 12, 1948 William E. Stilwell, Jr.,

to John Gincinnati, Ohio, B. Pierce Foundation, New York, N. Y.,

minor a corporation of New York Continuation of application semi No. February 8, 1941. This application 378,068, September 18, 1943, Serial No. 502,924

This invention relates to electromagnetic switches, and particularly to self-enclosed .remotely controlled magnetically operated switches. An object of the present invention is .to provide a self-enclosed low voltage magnetically operated switch which is designed to make and break elecly operated switch actuator element which is completely responsive to momentary energization.

Still a further object of the invention is to provide a switch device 01' the type hereinabove described wherein the high voltage circuit making and breaking stroke' is rapid and positive in action.

Another object of the invention is to provide a switch having the above characteristics, which includes means for making-and breaking the high voltage load circuit in one or more places.

Another object of the invention is to provide a low voltage magnetically operated switch-for high voltage load circuits wherein the low voltage magnetic actuator elements are electrically shielded and insulated from the high voltage contact elemen-ts, and wherein the device as a whole is electrically and mechanically shielded from harmful external forces and disturbances.

Another object of the invention is to provide improved means for accurately positioning and securing operating elements of the circuit breaker within a housing.

Still a further object of the invention is to pro- 2 Claims. (Cl. 175-337) means described herein and disclosed in the accompanying drawings. in which:

, vFig. 1 is a longitudinal sectional view of a switch linufactured according to the present invention; Fig. 2 is a section taken on lines 2-2 of Fig. 1;

Fig. 3 is a side elevation. partly in section showins the securement of the switch head to its supporting structure;

Fig. 4 is a sectional view, taken on lines 6-4 of Fig. l;

Fig. 5 is a plan view of the invention showing one method 01' installation in a standard electrical outlet box, with the low voltage switch actuator element projecting through one side of the box; Fig. 5 also illustrates schematically a wiring diagram for the controlling circuit.

Fig. 6 is a side elevation of the switch and outlet box of Fig. 5, with the outlet box portion in section; and

Fig. 7 is a plan view of the switch installed wholly within a standard electrical outlet box.

Referring to the drawings the invention comprises a switch l0 and a magnetically operated actuator ll associated therewith. The switch is adapted for remote control, from any desired plurality of stations 8. as diagrammatically shown in Fig. 5. The magnetic circuit of the actuator II is preferably woun'd for low voltage operation, thus placing the wiring from. the control stations to the actuator not under the requirements imposed upon high voltage systems by national electrical codes, and making possible substantial savings in weight and complexity of wiring and installation. The main switch contacts (usually high voltage) of switch iii are entirely electrically isolated from the magnetic actuator ii. and therefore may be designed for any electric service within code re-- quirements of installation.

The switch actuator ll includes a cylindrical body portion i2, preferably of steel or other magnetic material. A reduced diameter and fits into an aperture provided in an angle plate it; the housing may be secured to the angle plate I t by brazing or welding. A forwardly extendingleg i5 of the angle plate has a slotted end through which a screw or other fastening means may pass to secure the plate to the base of a standard outlet box as shown in Figs. 5 and 6.

To the angle plate It is secured the base I 8 of the switch body l0, said base being of insulation material, and carrying the high voltage terminal plates I! and therewith associated fixed contacts J8 of the main switch circuit. Cooperating with said fixed contacts are movable contacts 20, 20.

switch. and the small size to which the switch may be constructed, makes possible a variation in the manner in which, and in connection with which, the complete device may be installed in a standard electric outlet box. Figs. 5 and 6 show the switch so arranged with respect to an outlet box 24 that the high voltage part of switch ll is within the box for securement to the base plate thereof or through the base plate to the wall studding, whereas the low voltage switch actuator II and all of the low voltage wiring associated therewith is outside of the box. Such an arrangement is advantageous in an installation where the outlet box serves as a junction or several high voltage leads. the connecting and taping of which may take up a large portion of the volume of the box. The housing I2 of switch actuator H has an external diameter which permits it to be passed through one of the knock-out openings of the box.

As shown in Fig. 7. the entire switch assembly may be included within the confines of the outlet box if it is desired to protect the switch from plastering or other ceiling or wall finish during the construction of a building in which the system is used.

It is considered to be an important feature of the invention that it may be completely within an outlet box or so disposed with respect thereto that only the high voltage portion of the apparatus is positioned within the box, to maintain the independence in the high and low voltage wiring.

The member 2! is guided in its movement within base it by diametrical lateral extensions. see Fig. 4. Said member is secured to an end of a brass shaft 26, by means affording self-adjusta bility of the member, so that the movable and fixed contacts .will engage despite slight irregularities in the positioning thereof.

To the opposite end of the shaft 26 there is secured an overthrow spring or snap-acting member 21 held with its periphery in engagement with a sloping shoulder 28 of the housing l2. Said spring is desirably as described and claimed in my co-pending application Serial No. 441,382, filed May 1, 1942, which subsequently became abandoned, for Toggle springs.

The shaft 28 is guided in its longitudinal movement by passage through the aligned bores of two end stops or cores 30 and 3|, which receive the slidable shaft. The end stops are of steel or other magnetic material and are suitably positioned within the housing 12; it will be noted that a shouldered end of stop 30 rests against an inner end wall of housing i2, and that the flanged head of end stop II abuts a shoulder 32 provided within housing l2.

Disposed about the end stop ll is a solenoid coil 33, and about end stop 3! is a solenoid coil 34; when the coils are energized selectively through the wiring circuit (shown in dotted lines) the respective end stop of the energized 4 coil forms a pole of the magnetic system thereby created. Between said coils is disposed a metal annular member II, being 1 with the iron or steel housing i2, and positioned in the housing in engagement with a shoulder II formed therein. Said annular member 8| serves also to position the solenoid spools by the interfitting of shoulders 31 thereon into a groove on the respective sides of the annular member.

Secured to the shaft 20 is a magnetically responsive armature 38 having an outside diameter slightly less than the inner diameter of the annular member 35 to avoid a frictional contact of the armature and the core. It will be noted that the ends of the armature are conical, corresponding to the conical depressions of the respective end stops 3' and ii.

The magnetic fiux created by the respective energized solenoids passes through and is confined within the high permeability structure comprising the housing ii, the core members II (II), the annular member ll, and the armature 18, all of which are preferably of metals having high magnetic permeability. This construction assures a powerful pull on the armature 38 to insure immediate and strong response to the control circuit.

If desired, the positioning of the end stops within the housing is such that the permitted travel of the shaft 20 in either direction is less than the total extent of throw of the toggle spring 21 from one to the other of its positions of stability. In Fig. 1, showing the switch in open circuit position, the armature it has abutted against the end stop ll before the spring 21 has completed its full throw, whereupon said spring yieldingly holds the armature in engagement with the end stop. This is advantageous in avoiding hllm when the magnetic actuator II is employed with alternating current. Likewise the engagement of the armature I! with end stop 30 occurs before the spring has fully thrown to its other position of equilibrium so that said spring exerts a continuous pressure in the given direction. 'It will be understood that prior to the engagement of the armature with the end stop II,- the movable and fixed contacts of the switch II have come into engagement.

The precise relationship of the travel of shaft 28 and the position of end stops l0 and ll is established by means of the respective shoulders of the housing It, as previously described.

To maintain the annular member 38 and the end stop ii in engagement with the respective shoulders of the housing l2, and also accurately to position the spring 21, there is employed an insulating end cap or spider lll formed with a rim II and a plurality of spaced legs II, the latter straddling the spoked portions of the spring 21 as shown in Fig. 2. The ends of the legs I! rest upon the surface of'the end stop ll and hold the end stop in position against the shoulder 32, and,

through the intervening solenoid ll, holds annular member 35 against the shoulder 3'. spring 21 is confined by means of a washer 43,

against the rim ll of the spider II. The spider 40 therefore serves as means to maintain the various operating elements of the switch in proper relationship one with the other.

To confine the spider ll in its position, there may be employed a metallic cap 44, the rim of which rests upon the cap ll, and is held in position by beading or fianging an end of the housing I! about the circumference of the cap, as shown in Fig. 1.

The solenoid spools, the annular member, and

The

end stop 3| are suitably slotted to accommodate the wiring from the solenoids 33 and 34; passages 45 through the leg portions of spider 48 are channels through which the wires may be run.

Whereas I have described my invention by ref erence to specific forms thereof, it will be under-- stood that many changes and modifications may be made provided they do not depart'from the scope of the claims.

I claim: I

1. Electromagnetic means, comprising a magnetic shell formed with a plurality of concentric bores of successively smaller diameters, the line of demarcation between successive bores being of the nature of angular shoulders, magnetic end stop means and an intermediate magnetic annular member positioned within said shell by engagement with said shoulders, an armature slidably positioned within said annular member for operation between said end stops, a snap spring operatively associated with said armature, and cap means disposed within said shell and bearing against said snap spring and said end stop means to maintain the positioning thereof within said shell.

2. Switch actuator means, comprising a tubular casing, electromagnetic coremeans disposed within said casing, a-n armature mounted for reciprocal movement between said electromagnetic core means, a snap spring having a rim portion supported peripherally by said casing and a spoked center portion operatively associated with said armature for maintaining the armature resiliently at either of its extremes of reciprocal movement, cap means having a rim engageable with the rim of said snap spring to maintain the support thereof by said casing and leg means straddling the spoked portion of said snap spring and engageable with said electromagnetic core means to maintain the positioning thereof within the casing, and means for securing the cap means within said casing.

WILLIAM E. STILWELL, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES EATENTS Number Name Date 267,711 Peck et a1. Nov. 21, 1882 519,662 Carpenter May 8, 1894 728,752 Naphthaly et al. May 18, 1903 773,120 Christmas Oct. 25, 1904 773,122 Christmas Oct. 25, 1904 814,322 Perkins Mar; 6, 1906 995,448 Achard Apr. 19, 1910 1,164,475 Croston Dec. 14, 1915 1,275,766 Schoenwolf Aug. 13, 1918 1,434,637 Tuck Nov. 7, 1922 1,485,750 Wolfe et ai. Mar. 4, 1924 1,571,401 Erickson Feb. 2, 1928 1,733,085 Thomas Got. 22, 1929 1,861,046 Bower May 31, 1932 1,891,540 Howard Dec. 20, 1932 1,891,541 Howard Dec. 20, 1932 1,983,740 Deary Dec. 11, 1934 2,151,213 Kelley Mar. 21, 1939 2,174,868 Coffeen Oct. 3, 1939 2,258,586 Glassing Oct. 14, 1941 2,284,891 Hartig June 2, 1942 2,313,379 Wood Mar. 9, 1948 2,360,666 Fish Oct. 17, 1944

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