US2198474A - Electric switch - Google Patents

Description

April 23, 1940. w. CQQK 2,198,474

ELECTRIC SWITCH Filed June 9, 1937 L Invegtfi/r k eonar oo His Attorney Patented Apr. 23, 1940 UNITED STATES ELECTRIC SWITCH Leonard W. Cook, Bridgeport, Conn.,- asslgnor to General Electric Company, a corporation of New York Application June 9, 1931, Serial No. 147,295 4 4 Claims.

The present invention relates to electric switches.

The object of the invention is to provide an improved switch which is simple in structure, compact, reliable in operation, comprises few parts and is capable of being manufactured at low cost.

My improved switch is well adapted for use as a power switch for radio receiving sets and for being combined with a volume control, and it is this application of my invention which I have elected to specifically illustrate and describe. It is to be understood, however, that the invention is not limited to this use necessarily but may be used wherever found applicable.

For a consideration of what I believe to be novel and my invention, attention is directed to the following speciflcation and the claims appended thereto.

In the drawing, Fig. 1 is a perspective view of a combined power switch and volume control, the structure being shown partly in section; Fig. 2 is a perspective view of the switch as viewed from the front; Fig. 3 is a face view of the switch with its cover plate removed and showing the switch in open position; Fig. 4 is a view similar to Fig. 3

showing the switch in closed position; Fig. 5 is a longitudinal sectional view of the switch; Fig. 6 is a detail sectional view taken on line 5-5, Fig. 3; Fig. 'l is an exploded view showing the movable parts of the switch; Fig. 8 is a face view with the cover, removed of a modified form of switch, and Fig. 9 is a view similar to Fig. 8 of another modification.

Referring to the drawing, I indicates a combined power switch and volume control for a radio receiving set having a'noperating knob 2 by means of which shaft 3 is turned. The power switch is indicated at 4 and the resistance of the 40 potentiometer is indicated at 5. The shaft 3 has a wiper 5 which moves over the resistance 5 and a finger l which operates the power switch. In the position of the parts shown in Fig. 1, switch 4 is open and finger l rests against a stop 8 which limits turning movement of shaft 3 in an anti-clockwise direction. when knob 2 and shaft 3 are turned in a clockwise direction, finger I first acts to close switch 4 after which further movement of the shaft moves the wiper I over the resistance 5. i

The switch 4 is attached to the rear wall 9 of the structure by means of rivets or screws which pass through holes ill in the switch body and fasten into wall 9. In wall 9 is an opening ll through which project two curved angularly arranged ears l2 and III which are connected with the switch mechanism and which are engaged by the finger l to open and close the switch. Referring now to Figs. 2 to 7, the switch structure comprising a casing l4 of suitable insulating '5 material having a fiat back wall I5 and a surrounding side wall I 6 which defines with the back wall I5 a casing having a flat open face ll. The fiat open face is closed by a cover plate l8 of insulating material, the same being positioned on 10 the casing by spaced integral pins IS on face I! which enter openings in the plate I8. Plate I8 is provided with an opening 20 through which the ears I2 and I3 project. At one end, casing I4 is provided with walls which define V-shaped ll pivot notch 2| and at its other end, it is provided with walls which define a rounded pivot 22.

On one side of casing l4 are walls which define two spaced recesses 23 and 24 for the reception of stationary contacts 25. At the bottoms of re- 20 cesses 23 and 24 are openings 26 through which ears 21 on contacts 25 project. Contacts 25 comprise rectangular, slightly bowed pieces of metal of a size adapted to be wedged into recesses 23 and 24 and be held therein by the friction of the 25 pieces with the walls of the recesses. The inner ends of the contacts 25 shoulder against the inner surface of back wall l5 as shown in Fig. 6, the cars 21 projecting through the openings 25.

The slightly bowed construction of the contacts 25 permit them to yield somewhat in being pushed into the recesses and provide springiness for retaining them in the recesses. In the ears 21 are openings 28 in which lead wires may be connected.

The other side wall of casing 14 is provided with recesses similar to recesses 23 and 24. These recesses are not used in the switch shown in Figs. 2 to 7 inclusive. They may be used for example in cases where it is desired to provide a switch to control two circuits or where it is desired to provide a multiple break switch. This arrangement adapts casing l4 for various switch constructions as is explained more fully hereinafter. The movable parts of the switch comprise four elements, a leaf spring 29, a movable contact 30 5 of suitable conducting material, a contact carrier 3| of suitable insulating material and an actuator 32 comprising piece of metal bent on itself to provide a rounded pivot 33 having a groove 34 for the reception of one end'of leaf'spring 25 and the actuating ears l2 and I3. One end of leaf spring 29 is bent back on itself to provide a rounded end 35 which engages pivot notch 2| This provides a smooth bearing, thus reducing wear on the casing. The other end of leaf spring 56 29 engages loosely in groove 34 of rounded pivot 33 which pivot in turn engages the rounded pivot 22 at the end of easing 4. Movable contact 39 is attached to contact carrier 3|. This may be done conveniently by providing notches 36 in the side walls of carrier 3| adjacent one end and fastening the movable contact in these notches. The movable contact may be split at one'end as shown in Fig. 7 so that it may be assembled in the two notches 36 after which the split ends are squeezed together. This forms a simple and easy means for assembling the movable contact on the carrier and one which can be carried out at low cost. In the contact carrier at about the central portion is a diamond shaped opening 31 through which leaf spring 29 loosely extends. The contact carrier 3| is located in a transverse crosswise groove 38 in casing l4 and is adapted to move transversely therein, the ends of the contact carrier being located in notches 39 in the side walls of the casing.

Leaf spring 29 is slightly longer than the distance between pivot notch 2| and the end of groove 34 when pivot 33 is in position against the casing pivot point 22 which means that the leaf spring is bowed between its ends in either one direction or the other as shown in Figs 3 and 4. Movement of the spring and the carrier 3| toward the left as shown in Fig. 3 is limited by the engagement of the carrier with the end of notch 39; movement to the right is limited by movable contact 30 engaging the fixed contacts 25 as shown in Fig. 4. The tension of the bowed spring serves to hold the carrier in either of its extreme positions.

Preferably leaf spring 29 has a length about greater than the distance between the spring supports. Such a. length results in a rapid snap action of the switch and at the same time gives long spring life. However, the length of the spring may be less than 5% greater than the distance between the spring supports or it may be somewhat greater, depending on the characteristics of the spring and the particular application. Also, I find it preferable to locate the movable contact and its carrier within 30% of the one end of the spring and arrange the operating means so that it acts on the spring within 30% of the other end, thus leaving at least 40% of the middle portion of the spring free to flex back and forth to effect operation of the movable contact. This arrangement, I have found to give satisfactory results.

When movable contact 39 is in engagement with fixed contacts 24 and 25, it is held against them by the tension of the leaf spring, the fixed contacts being so located that the leaf spring cannot fully bow out. This maintains firm en gagement between the movable contact and the fixed contacts and when in this position, the leaf spring is flexed to some extent. When actuator 32 is moved, it flexes the portion of the leaf spring between pivot point 33 and slide 3| and during the initial movement of the actuator, this portion of the leaf spring is gradually flexed,

the movable contact 30 remaining in engagement with the fixed contacts 24 and 25. When the leaf spring moves across dead center, the spring moves the movable contact away from the fixed contacts with a quick snap action, thus effecting a quick break of the switch. During the initial movement of the actuator, only that portion of the leaf spring between pivot point 32 and slide 3| is fiexed but when the slide starts to move, the entire length of the spring comes into play to effect movement of the slide and separation of the contacts. In closing the switch, the operation is the same as that Just described except in the opposite direction. By this arrangement, I obtain a. construction wherein the contacts are quickly separated and wherein it is not possible to separate slightly the contacts and then permit them again to close, thus causing sparking between the contacts. When the switch is actuated, the contacts are always fully opened or closed with a snap action.

In Fig. 8, the switch is shown in open position.

To close the switch, the actuator is moved in a counter-clockwise direction this being effected in the particular arrangement shown by finger l engaging the inner surface of curved ear l2. As the actuator is turned, the end of leaf spring 29 is flexed toward the right and after being flexed a predetermined amount, it will snap over dead center and quickly move the contact carrier and contact from the position shown in Fig. 3 to the position shown in Fig. 4 in which the movable contact is in engagement with the fixed contacts. Tension of the leaf spring serves to hold the movable contact firmly in engagement with the fixed contacts. To open the switch, the actuator is turned in the opposite direction, it being turned, in the present instance, by finger 1 engaging the inner curved surface of ear I3. The arrangement is such that after the switch is closed by finger I, the finger can move past the end of ear l2 to permit further turning of the shaft 3.

In Fig. 8 is shown a modification of the invention wherein a double break switch is provided. In this case, the contact carrier 3|, corresponding to the contact carrier 3| of Figs. 2 to 7, is provided with two movable contacts 30, and fixed contacts are provided on each side of the casing body. At 40 is a strip of insulating material for separating the left hand contact 25 from the leaf spring. Otherwise, the arrangement shown in Fig. 8 may be the same as that shown in Figs. 2 to '7.

In Fig. 9 is shown a modification wherein the switch controls two circuits. In this case, the contact carrier 3|? is provided with two movable contacts adapted to engage fixed contacts 25' on opposite sides of the casing. Otherwise, the construction shown in Fig. 9 may be the same as that shown in Figs. 2 to 7. The operation of the arrangement shown in Fig. 9 is obvious from an inspection of the construction.

By the above-described arrangement, it will be seen that I have provided a switch which is simple in structure and comprises few parts. To assemble the fixed contacts in the casing, it is necessary merely to slip them into the grooves 23 and 24. This may be quickly and easily done. And it will be noted that the ears to which the wires are connected are extensions on these fixed contacts and form a part of them. As a result, the contacts and ears can be readily stamped from sheet material and require but little forming.

The actuator is formed from a single piece of metal and provides, in addition to providing the actuating ears for the switch, a seat for one end of the leaf spring and a pivot for engagement with the casing. The contact carrier and movable contact comprise two simple parts, one a rectangular piece of metal and the other a rectangular piece of insulating material. These parts are connected to the leaf spring by merely extending the leaf spring through an opening in the contact carrier. These parts are not required to be nicely fitted so that precision work is not necessary.

To assemble the switch, after the movable contact has been attached to the contact carrier, it is necessary merely to slip leaf spring 29 through opening 31 in the contact carrier, place its end in groove 34 of the actuator and then insert the parts in casing II. This can be quickly and easily done.

By providing the casing so as to hold fixed contacts at both sides, a single form of body member may be adapted readily for different switch combinations.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A switch comprising a casing, a fixed contact in the casing, walls in the casing which define two opposed pivot points, a combined pivot member and actuator resting against one of said pivot points, a leaf spring which at one end engages said actuator and at the other end engages said other pivot point, a movable contact carried by the leaf spring adapted to engage said fixed contact upon flexing of said spring, means for guiding the movable contact and means carried by said pivot member for flexing said spring.

2. A switch comprising a casing having walls at opposite ends which define pivots, and recesses on one side, stationary contacts held in the recesses, a transverse groove in the casing, a sliding carrier in said groove, a movable contact on the carrier for bridging the stationary contacts, a pivot member engaging one of said pivots having walls which define a groove, 2. leaf spring which extends through an opening in the carrier and has one end resting in said groove and the other end engaging said other in the casing, a pivot member in one of said notched portions, a leaf spring having one end located in a groove in the pivot member and the other end located in the other notched por tion, said spring being of a length such that it is normally flexed, a contact carried by the spring for engagement with the fixed contacts, a cover plate for the open side of the casing, and an actuating ear forming a part of the pivot member and projecting beyond the cover plate for flexing the spring to actuate the switch.

4. A switch comprising a casing having an open face and walls at opposite ends which define pivots, fixed contact means carried by said casing, a transverse groove in the casing, a sliding carrier disposed in the groove and having an opening therein and having means cooperating with said fixed contact means for controlling an electric circuit, a pivot member engaging one of said pivots having walls which define a groove, a leaf spring extending through the opening in said carrier havingone end resting in said groove and the other end engaging the other pivot, said spring being of a length such that it is normally flexed, a cover plate for the open face of said casing and itself having an opening therein, and oppositely disposed actuating ears forming part I of said pivot member and extending through the opening in said cover plate for flexing the spring to actuate the switch.

LEONARD W. COOK.

Images