US2515528A - Snap switch structure - Google Patents

Description

July 18, 1950 J. J. ROTHWELL 2,515,528

SNAP SWITCH STRUCTURE Filed Feb. 10, 1947 2 Sheets-Sheet 1 IN V EN TOR. .l g ml Rory WELL y 1950 J. J. ROTHWELL 2,515,528

SNAP SWITCH STRUCTURE Filed Feb. 10, 1947 2 Sheets-Sheet 2 Patented July 18, 1950 SNAP SWITCH STRUCTURE John J. Rothwell, Elkhart, Ind.,.assignor toPcnn Electric .Switch'Co Goshen, InL, a corporation of Iowa Application February 10, 1947, Serial No. 727,568

3 Claims. (01. 200-67) My-present invention relates to a snap switch structure which is adaptable to be used in connection with automatic switches such as those oner-ated by pressure (Jr-temperature.

One object .of -the invention is to provide a relatively. small butirugged switchstructure capable oflcarryingheavyl currents Witha minimumof contactltrouble. during a relatively long operating life tor the switch.

vAnotherlobjectris-vto provide a switch structure which is comparatively inexpensive to .manufacture .and involves a l minimum of operations for its-assembly.

Still another. objectis to proyide a switch structure whereinstationaryand movable contacts are provided, the .stationary'contact being resiliently mounted soas tominimize boimceland arcing oi the. contacts.

A further object :is to provide a i switch structure in which the movablecontact is biased to engage thenstationary contact with a pro-determined initial pressure, which pressure .does not reduce during the snap action period until a hammerbreakaction occurs for separating the movable .contactlfrom the stationary contact.

Still a further object is to provide atoggle spring connection between an actuating arm 1 and a -toggle arm, theltogglelarmhavihg a lost motion connection with the movable contact, which lost motion :can be (predetermined, the toggle springbeingadj ustably-mountedin a simplemam nor for vchanging the .toggle action as desired or required.

.Anadditionalobjectis to provide a toggle con-- nection between asingle actuating arm and a pair of toggle arms for a double break switch which is arranged .ior three point .coaction -between the ,actuatingarm and thetoggle arms.

Another additionallobj ect istoprovide a rugged base for the contact springs and the actuating arm, with the mountings'being such that erratic operation of the switch unit is .minimized.

A further-additional objectisto provideoa base so arranged that it can be mounted .with a single screw in a switch housing, thus lmaking the switch unit readily removable .for replacement or repair.

With these and other obj ectsjin v'ievcmy inven" tion consists in the construction, arrangementand combination of the various .parts of .my device whereby the objects contemplatedare attained .as

hereinafter more .lfully set iorth, pointed-out in my claims, and lillustrated in the accompanying drawings, in which:

Figure 1 is an exploded, perspective View of a switch structure embodying my present invention;

Figure 2 is a perspective view of the switch structure with the parts assembled;

Figure 3 is an enlarged sectional .view on the line 3-3 of Figure 1 showing a ,lost motion connectionbetween a contact arm and a to gle arm;

Figure 4 is an enlarged sectional view on the line 44 of Figure 2, showing the switch in closed position;

Figure 5 is a full scale side elevation showing the switch being moved toward open position and the toggle link approaching dead center;

Figure 6 is an enlarged sectional view .of the toggle link on dead center;

Figure 7 is a similar sectional view showing the link passing dead center and the lost motion between the toggle arm and the contact arm taken up during switch opening operation;

Figure 7a is a similar sectional view showing the link ready to pass dead center during switch closing operation;

Figure 8 is a side elevation showing the'switch in the open position; and v Figure 9 is an enlarged view showing the toggle link sectioned and in the position of Figure 8.

On the accompanying drawings, I have used the reference character B to'indicate abase which may be formed of molded insulating material. The base 13 base rectangular projection l0 and a screw receiving opening I2 for mounting purposes. Referring to Figure 4 the elements wand l2 permit the mounting of the base B by means of a single screw [4 threaded into a, bracket [6 extending from a, wall of a casing C. The casing C is provided with a rectangular opening 18 to receive the projection Ill. Due to their rectangular shapes, the projection II] and the opening 18 prevent any rotation of the switch structure about a horizontal axis extending from left to right in Figure l, and the screw Mprevents any rotation about a horizontal axis extending toward the observer. The single screw M thereby efiectively cooperates with the projection ID to rigidly mount the switch structure in the casing C.

Molded in the base B is a'pair of terminal strips another pair of terminal strips 22. -One of each .is shown in Figure 4 and they are illustrated as having terminal screws 24 and 28 respectively threaded thereinto. .Another setof screws 24 and it is illustrated inFigure v1, and the second set of terminal strips 20 andv22 receivethe second set of screws as the switch illustrated is ior breaking both lines of a circuit.

The strips 20 and {22 as shown in Figure 4 extend through the base B and receive screws 28 and 38 respectively. The screws 28 extend through angle brackets 32 and through movable contact springs 34 for mounting them on a step 36 of the base B. The screws 38 extend through somewhat heavier contact springs 38 for mounting these strips on shoulders 48 of the base B. The contact springs 38 carry stationary contacts 42 and the springs 34 carry movable contacts 44 which are normally in engagement with each other as shown in Figure 4. The springs 38 and 34 are so bent that the engagement is positive and in the neighborhood of 35 grams on a switch contacts measurin about in diameter.

The contact springs 34 have terminal ends 46 formed at right angles thereto and these are perforated with rectangular openings. (See Figure 3.) A toggle lever 58 in the form of a thin strip of sheet metal extends through the opening 48 and is somewhat thinner than the width of the opening as shown to provide a certain amount of lost motion for a purpose which will herein-- after appear. This lost motion is predetermined by the relative width of the opening 48 and thickness of the lever 58.

The ends of the toggle levers 58 are reduced in width as indicated at 52 and 54, the reduced ends 52 extending through openings 58 in the angle brackets 32 and their shoulders bearing in pivot fashion against the an le brackets 32 opposing a toggle lever 14 as will appear later. The reduced ends 54 are the portions of the springs 58 that extend through the openings 48 as best shown in Figure 1.

An actuating arm 58 of resilient metal is provided having a slot 68 receiving a pair of screws 62 that are threaded into a boss 54 of the base B. The slot 68 permits longitudinal adjustment of the actuating arm 58.

The arm 58 has a pointed extension 86 seated in a socket 68 of a plunger 18. The plunger 18 is slidable in a central boss 12 of a T-shaped toggle link 14, which link has a pair of V seats 16. The V seats receive the reduced terminal ends 54 of the toggle levers 58 and the seats and ends are resiliently engaged with each other under the bias of a spring 18 received in a socket in the boss 12. The spring bears against the bottom of the socket and the plunger 18. The T-shape toggle link '14 permits the actuation of a pair of switches from a single actuating lever with a minimum of bindin and a maximum of efliciency in the balancing and even distribution of actuating forces from the single element to the two elements. This is particularly accomplished by having the socket 68 located on a line passing between the two sockets 16.

Practical operation In the operation of my switch structure, assuming the parts to be in the position of Figure 4, the contacts 42 and 44 are engaged with each other under the bias of the spring 34 to which is added the bias of the spring 18 because the toggle link 14 is tipped downwardly to the left in this figure. An actuating pin 88 is illustrated which may be driven by a temperature or pressure responsive device or by any motive power, and when this pin moves downwardly as to the position of Figure 5, it will align the toggle link 14 with the toggle lever 58. This reduces the bias of the spring '58 on the actuating lever 58 to zero but the pres sure of the spring 34 is still present, thereby insuring a flow of current that is not reduced due to lightening the contact pressure.

After the position of Figure 5 is reached, slightfurther movement will position the parts on dead center as shown in Figure 6 and further downward movement of the actuating pin 88 results in the toggle link 14 passing dead center. The spring 18 will immediately expand as to the position of Figure 7, causing the extension 54 of the actuating lever 58 to move from the lower side of the slot 48 to the upper side thereof. This lost motion permits momentum to be built up in the lever 58 so that when it hits the upper side of the slot as in Figure '7, it does so with a hammer-like blow that quickly separates the contact 44 from the contact 42 and the parts finally assume the position shown in Figures 8 and 9. The passage from the Figure 6 position through the Figure '7 position to the Figure 9 position is effected by expansion of the toggle spring 18, thus insuring quick and positive opening of the contacts, even though the actuating pin 88 may be advancing very slowly. Thus the are formed at the contacts is quickly quenched and contact life thereby maximized.

In returning from the Figure 9 position to the Figure 4 position as the actuating pin 88 moves: upwardly the arm 58 being biased upwardly fol-- lows it until the parts reach the position shown in Figure 7a. This is just before dead center and it will be noted that the elements 58 and 14' are inclined slightly upward at their adjacent ends. It will be remembered that the spring 34 is biased downwardly and therefore it has a tendency to pull the elements 58 and 14 across this dead center beginning at about the position shown in Figure 7a. In other words the upward force of the toggle is balanced by the downward force of the spring 34 at this point so that slight further movement causes the toggle to be propelled across dead center and onward under'the action of the toggle link to the closed position of Figure 4. This causes the actuating leaf 58 to be driven to the bottom of the opening 48 by the expanding toggle link and results in closure of the contacts. Such closure is in fact a hammermake of the circuit without any bouncing whatever of the contacts. Any tendency to bounce as the position of Figure 4 is again reached may result in the lever 58 bouncing away from the lower side of the opening 48, but if this happens, the predetermined pressure of the contact spring 34 keeps the contacts themselves engaged so that there is no opening of the circuit itself and consequently any arcing at the contacts upon a circuit making operation is entirely eliminated. The movement of the parts from the position illustrated in Figure 7a to the position illustrated in Figure 4 occurs with snap action because the downward force of the spring 34 moves the lever 58 and the toggle link past the dead center position.

Due to the construction and operation as described the switch structure is capable of carrying very heavy current, yet has a relatively long contact life, and can be used for motors of relatively great horsepower or other apparatus requiring considerable current.

Some changes may be made in the construction and arrangement of the parts of my device without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim as my invention:

1, In switch structure of the character disclosed, a base, a pair of contacts supported thereby, a pair of contact springs mounted on said base and carrying contacts normally engaged with said first contact under the bias of said contact springs, an actuating arm, a pair of toggle arms pivoted at one end and having lost motion connections with said contact springs adjacent their other ends, an expanding toggle link between said actuating arms and said toggle arms, said toggle link being T-shaped and having a pair of seats for the pair of toggle arms and a single seat for said expanding toggle link located on a line between said pair of seats, said single seat coacting with said actuating arm.

2. A switch structure comprising, a base, a pair of stationary contact springs and a pair of movable contact springs mounted thereon and carrying contacts for engagement with each other, an actuating arm, a pair of toggle arms pivoted at one end and avi g o t motion connections adjacent their other end with said movable contact spring, an expanding toggle link between said actuating arm and said toggle arms, toggle link having a, pair of seats for the pair of toggle levers and a single seat for the actuating arm, said single seat being located on a, line passing between said pair of seats.

3. In a switch structure, a base of insulating material having a pair of steps, terminal strips each having one end on one of said steps, said strips extending through said base to the opposite side, terminal screws on said opposite side threaded into said terminal strips, stationary contact springs on one of said steps, movable contact springs on the other said steps locating said springs at different elevations in respect to said base, contacts carried by said springs and normally engaged with each other under predetermined pressure, brackets on one of said steps having openings therein, toggle levers having reduced extensions providing shoulders, said brackets being perforated to receive said extensions with said shoulders against the brackets, said movable contact springs having openings, said toggle levers extending therethrough, said openings being wider than the thickness of the toggle levers to provide lost motion, an actuating arm, a pointed extension carried thereby, and a T-shaped expansible toggle link interposed between said pointed extension and said last ends of said toggle levers with its arms engaging said ends and the outer end of its leg engaging said pointed extension.

JOHN J. ROTHWELL.

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

UNITED STATES PATENTS Number Name Date 2,144,120 Parks Jan. 17, 1939 2,228,523 Johnson Jan. 14, 1941 2,232,243 Judson Feb. 18, 1941 2,318,734 Baak May 11, 1943 2,321,834 Marco et a1. June 15, 1943 2,338,365 Thorpe et a1 Jan. 4, 1944 2,414,778 Tratsch Jan. 21, 1947 2,418,068 Cornelius Mar. 25, 1947 2,449,086 Price Sept. 14, 1948 2,487,374 Riche et a1. Nov. 8, 1949

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