US2709727A - Snap switch - Google Patents

Description

May 31, 1955 H. M. DRESSEL SNAP SWITCH Filed May 13, 1952 IN V EN TOR. ///v,ey M DEE'S BY bridge.

United States Patent SNAP SWITCH Henry M. Dressel, St. Marys, Pa., assignor to Stackpole Carbon Company, St. Marys, Pa., a corporation of Pennsylvania Application May 13, 1952, Serial No. 287,514

8 Claims. (Cl. 200-67) This invention relates to electric snap switches of the bridging contact type, and more particularly to a double pole snap switch.

One of the problems in making switches for radio and television is to provide reliable switching in a very small space. This problem becomes greater when a double pole snap switch with two movable bridging members is involved, especially where the bridging members have to carry relatively high voltage and current. For proper operation, the bridging members must be electrically and mechanically independent of each other, so that they will be free to adjust themselves to the contacts that they Although the bridging members should press firmly against the contacts that they bridge, metal that is suitable for spring bridging members does not make the best contact material.

It is among the objects of this invention to provide a double pole snap switch which is very small, which has a simplified and space-saving construction, and in which the movable bridging members are stiff and are pressed against the fixed contacts by springs that do not carry any current.

In accordance with this invention, a pivot post projects from one side of an insulating base near its edge, and a pair of inner and outer contacts also are mounted on that side of the base. The outer contact is farther than the inner one from the post, and they preferably are spaced apart along a line radiating from the post. A trigger of special shape is oscillatably mounted on the post, and between the trigger and the base a switching arm also is oscillatably mounted on the post. A torsion spring connects the trigger with the arm for swinging the arm when the trigger is actuated. Carried by the arm, between it and the base, is a contact bridging bar. When the switch is open, the bar is located at one side of the outer contact. The bar is pressed toward the base by a leaf spring compressed between it and the arm. When the arm is swung across the base, it slides the bar part way across the top of the contacts so that the bar bridges them and the current flows through the bar. The switching arm preferably is provided with holes for receiving ears on the ends of the bar to connect the bar to the arm. This construction of switch is especially suitable for a small, double pole switch, wherein there are two pairs of contacts and two bridging bars.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which Fig. 1 is a plan view of my snap switch in off position; Fig. 2 is a similar view but in on position; Fig. 3 is a view of the outside of the base; Fig. 4 is a view similar to Fig. 1, but with the trigger and arm broken away; Fig. 5 is a vertical section taken on the line VV of Fig. 2; and Fig. 6 is a greatly enlarged isometric view of one of the bridging bars and its spring.

Referring to the drawings, an insulating base 1, which is more or less circular, has a small radially projecting portion 2, near which is mounted a pivot post 3 that extends upward from the base. The post has an integral ice collar that engages the upper surface of the base, while the lower end of the post is expanded below the base to rivet the post in place. Two pairs of fixed contacts 4 and 5 are mounted on the base. Each contact has a rounded head that rests on the base. As shown in Fig. 5, each contact extends down through the base and through a metal terminal 6, against which it is upset to hold the contact head and the terminal tightly against the opposite sides of the base. Each pair of contacts are spaced apart different distances from the pivot post, preferably along a line radiating from it, the two pairs of contacts being located along two different lines a few degrees apart, as shown in Fig. 4.

Mounted on the pivot post directly above its collar, for movement in a short are around the post, is a fan shape switching arm 7 made of insulating material. Also mounted on the pivot post in the same manner above the arm is a trigger 8 which has a U-shape body, the lower part of which engages the switching arm and the upper part of which engages the upset upper end of the post. The upper part of the trigger extends out over arm 7 and is provided with upright lugs 9 that are adapted to straddle a conventional actuating member that can be swung back and forth by the control shaft of a rheostat (not shown) to which the switch usually is attached. The movement of the trigger is limited by its lateral cars which strike the side wall 10 of the switch. The trigger is operatively connected to the switching arm by a torsion spring 11 of well-known form which, when the trigger is swung from one end of its path of movement to the other, snaps the arm in the opposite direction. The movement of the switching arm is limited by the side wall of the switch. The torsion spring presses the arm down toward the base.

The switch side wall 10 is formed from a band of metal which has been wrapped around the edge of the insulating base 1. The lower edge of this band is provided at its opposite ends with tongues 15 that are bent under the lower surface of the base, as shown in Fig. 3, and then up through a slot 16 in the base near a point on its edge diametrically opposite to projection 2. The upper ends of the tongues are bent down over the upper surface of the base to lock them and to hold the opposite ends of the metal band next to each other. The lower edge of the band also is provided with another pair of tongues 17 which extend through slots 18 in the base at opposite sides of its projection 2. Thus, no riveting of the side wall in place is required. Another advantage of using such a band is that the side wall can be deformed to conform to the periphery of the base, which therefore can be irregular and need extend outward at any given point no farther than absolutely necessary. Such an outward extension that is necessary is formed by projecting portion 2. The over-all size of the switch thus can be small enough to permit tongues 19 on the upper edge of the side wall to be fastened to a small rheostat.

With the switching arm 7 in its on position, as shown in Figs. 2, 4 and 5, it is provided above the contacts with rectangular holes 21 and 22. These holes receive the ears 23 and 24 on the opposite ends of contact bridging bars 25 extending radially of post 3. Each bar is long enough to span a pair of the fixed contacts 4 and 5 to connect them electrically. The outer holes 21 are elongated along lines radiating from the pivot post, to form slots. The cars 24 at the inner ends of the bars fit rather loosely in the inner set of holes 22, but the cars 23 at the outer ends of the bars are longer and extend entirely through slots 21 and above the arm. Their upper ends are provided with lateral projections 27 that overlie the arm at oppositesides. of the slots. These'projections prevent the bars from accidentally coming out of the arm, but do not prevent .ears 23 from moving up and u" down in the slots. in order to connect the bars with the arm, they have to be turned at right angles to their operative positions so that the projections on ears 23 can pass through the slots in the arm. Then the bars can be swung around and their cars 24 inserted in holes 22. Although the bars are rather loosely mounted in the arm so that they are free to move up and down and adjust themselves to the contacts, they are rigid or stiff in themselves and therefore can be made from metal, such as silver, best suited for electric contacts and for conducting electric current from one contact to another.

To assure good contact between the bridging bars and the fixed contacts on the base, each bar is continuously pressed toward the base by a separate leaf spring 30 between the bar and arm. Each spring preferably is a rectangular member that has its central portion engaging the central portion of a bar and that has its opposite ends inclined upward from the center of the spring to the overlying arm, against which they press. The opposite edges of the central portion of the spring are bent down to form lugs 31 that fit into notches 32 in the opposite edges of the bridging bar. These lugs and notches hold the sprin in position on the bar during assembly of the switch and its subsequent use.

When the trigger is actuated to swing switching arm 7 toward the opposite side of the switch, as shown in Fig. l, the bridging bars are moved laterally out of bridging position. The outer ends of the bars are slid completely off the outer contacts 4, but the distance that they have to be moved is reduced by providing the outer end portion of each bar with a lateral recess 33 that receives the edge of the adjacent contact. It is unnecessary for the inner ends of the bars to move completely out of engagement with inner contacts 5 at any time.

When the switching arm swings the bridging bars to on position, their inner ends slide part way across the inner contacts. At the same time, the outer ends of the bars are swung into engagement with the outer contacts and part way across them. Each pair of contacts therefore is bridged by one of the bars, which is pressed against those contacts by the leaf spring on the bar. Since the springs carry no current, they can be formed from the most desirable spring metal, such as brass.

The snap switch disclosed herein has been described, for the salte of convenience, as if one were looking down into it in Figs. 1, 2 and 4. Nevertheless, it should be understood that the switch may be mounted with its base 1 vertical or at the top of the unit. Many of the advantages of this switch also are applicable to a single pole switch.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what i now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A snap switch comprising an insulating base, a pivot post projecting from one side of the base near one edge, a pair of inner and outer contacts on said side of the base with the outer contact farther than the inner contact from said post, a trigger oscillatably mounted on the post, a switching arm oscillatably mounted on the post between the trigger and base, a torsion spring connecting the trigger with the arm and adapted to snap the arm back and forth across the base when the trigger is actuated, a contact bridging bar disposed loosely between the base and arm and carried by the latter with the opposite ends of the bar engaging the tops of said contacts while the switch is closed, said bar being located at one side of the outer contact when the switch is open, and a separate leaf spring compressed between the bar and arm and pressing the bar toward the base, said arm being adapted to slide the bar laterally part way across the Q. tops of both contacts to bridge them when the trigger is actuated to close the switch.

2. A snap switch comprising an insulating base, a pivot post projecting from one side of the base near one edge, a pair of inner and outer contacts on said side of the base with the outer contact farther than the inner contact from said post, a trigger oscillatably mounted on the post, a switching arm oscillatably mounted on the post between the trigger and base, a torsion spring connecting the trigger with the arm and adapted to snap the arm back and forth across the base when the trigger is actuated, a contact bridging bar disposed loosely between the base and arm and carried by the latter with the opposite ends of the bar engaging the tops of said contacts while the switch is closed, said bar always engaging the top of the inner contact but being located at one side of the outer contact when the switch is open, a separate leaf spring compressed between the bar and arm and pressing the bar toward the base, and means connecting the spring with the bar to hold them together, said arm being adapted to slide the bar laterally part way across the tops of both contacts to bridge them when the trigger is actuated to close the switch.

3. A snap switch comprising an insulating base, a pivot post projecting from one side of the base near one edge, a pair of inner and outer contacts on said side of the base with the outer contact farther than the inner contact from said post, a trigger oscillatably mounted on the post, a switching arm oscillatably mounted on the post between the trigger and base, a torsion spring connecting the trigger with the arm and adapted to snap the arm back and forth across the base when the trigger is actuated, a contact bridging bar disposed loosely between the base and arm and carried by the latter, said bar having one end always engaging the top of the inner contact, the opposite end of the bar being provided with a lateral recess spacing it from the outer contact when the switch is open, and a separate leaf spring compressed between the bar and arm and pressing the bar toward the base, said arm being adapted to slide the bar laterally part way across the tops of both contacts to bridge them when the trigger is actuated to close the switch.

4. A snap switch comprising an insulating base, a pivot post projecting from one side of the base near one edge, a pair of inner and outer contacts on said side of the base with the outer contact farther than the inner contact from said post, a trigger oscillatably mounted on the post, a switching arm oscillatably mounted on the post between the trigger and base, a torsion spring connecting the trigger with the arm and adapted to snap the arm back and forth across the base when the trigger is actuated, a contact bridging bar disposed loosely between the base and arm and carried by the latter, said bar being located at one side of the outer contact when the switch is open, a separate leaf spring extending lengthwise of the bar having its central portion engaging the center of the top of the bar, the end portions of the spring being inclined toward and pressing against said arm to press the bar toward the base, and means connecting the spring with the bar to hold them together, said arm being adapted to slide the bar laterally part way across the tops of both contacts to bridge them when the trigger is actuated to close the switch.

5. A snap switch comprising an insulating base, a pivot post projecting from one side of the base near one edge, a pair of inner and outer contacts on said side of the base with the outer contact farther than the inner contact from said post, a trigger oscillatably mounted on the post, a switching arm oscillatably mounted on the post between the trigger and base, a torsion spring connecting the trigger with the arm and adapted to snap the arm back and forth across the base when the trigger is actuated, acontact bridging bar disposed loosely between the base and arm and carried by the latter, said bar being located at one side of the outer contact when the switch is open and having notches in the opposite edges of its central portion, and a leaf spring compressed between the bar and arm and pressing the bar toward the base, the central portion of the spring having lugs bent into said bar notches to hold the spring in position, said arm being adapted to slide the bar laterally part way across the tops of both contacts to bridge them when the trigger is actuated to close the switch.

6. A snap switch comprising an insulating base, a pivot post projecting from one side of the base near one edge, a pair of inner and outer contacts on said side of the base with the outer contact farther than the inner contact from said post, a trigger oscillatably mounted on the post, a switching arm oscillatably mounted on the post between the trigger and base, a torsion spring conmeeting the trigger with the arm and adapted to snap the arm back and forth across the base when the trigger is actuated, a contact bridging bar disposed between the base and arm and provided at its opposite ends with ears extending away from the base, said arm being provided with holes slidably receiving said ears to connect the bar to the arm, said bar being located at one side of the outer contact when the switch is open, and a leaf spring compressed between the bar and arm and pressing the bar toward the base, the upper end of the ear adjacent the outer contact being provided with a projection overlying the arm and holding the outer end of the bar away from the base when the switch is open, said arm being adapted to slide the bar laterally part way across the tops of both contacts to bridge them when the trigger is actuated to close the switch.

7. A snap switch comprising an insulating base, a pivot post projecting from one side of the base, a pair of inner and outer contacts on said side of the base with the outer contact farther than the inner contact from said post, a switching arm mounted on the post, a contact bridging bar disposed between the base and arm and provided at its opposite ends with ears extending away from the base, said arm being provided with inner and outer holes each close to one of said contacts slid ably receiving said ears to connect the bar to the arm, the hole adjacent the outer contact being a slot extending toward said post, the ear in said slot being disposed transversely thereof and having lateral projections at its outer end overlying said arm at opposite sides of the slot, the combined width of said projections and the ear between them being less than the length of the slot, and said bar being located at one side of the outer contact when the switch is open.

8. A double pole snap switch comprising an insulating base, a pivot post projecting from one side of the base near one edge, two laterally spaced pairs of contacts on said side of the base, each pair having an inner and an outer contact spaced apart along a line radiating from said post, a trigger oscillatably mounted on the post, a switching arm oscillatably mounted on the post between the trigger and base, a torsion spring connecting the trigger with the arm and adapted to snap the arm back and forth across the base when the trigger is actuated, a pair of laterally spaced contact bridging bars disposed loosely between the base and arm, each bar engaging the tops of a different pair of contacts when the switch is closed and being provided at its opposite ends with ears extending away from the base, said arm being provided with holes slidabiy receiving said ears to connect the bars to the arm, and a leaf spring compressed between each bar and the arm and pressing the bar against the contacts engaged by it, the central portion of each bar being provided with notches in its edges and being engaged by the central portion of one of said springs, the central portion of each spring having lugs at its opposite edges bent into the notches of the bar it engages, the end portions of the springs being inclined toward and pressing against the arm, and said arm being adapted to slide the outer ends of the bars laterally away from the outer contacts when the trigger is actuated to open the switch.

References Cited in the file of this patent UNITED STATES PATENTS 2,030,657 Schellenger Feb. 11, 1936 2,127,608 Manley Aug. 23, 1938 2,177,284 Schellenger Oct. 24, 1939 2,186,638 Hall Jan. 9, 1940 2,580,105 Krumreich Dec. 25, 1951 FOREIGN PATENTS 565,859 Great Britain Nov. 30, 1944 605,246 Great Britain July 19, 1948

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