Actuator Assembly For Toggle Switch

Abstract

Actuator assembly for snap action toggle switch has a rockerlike actuator member which is pivoted on a transverse axis. A roller mounted on the actuator member is adapted to be engaged for overcenter movement of the actuator at a point spaced from the pivot axis of the actuator member by a member on the end of the toggle lever having a curved outer surface resiliently biased into engagement with the roller. By the use of a pair of curved cooperating surfaces to cause overcenter movement, at least one of which is a roller, which contact each other intermediate their respective pivot mountings, a very unstable teaseproof mounting is provided.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to electrical switches and particularly to an actuator assembly for a snap action toggle switch which is teaseproof.

2. Description of the Prior Art

Electrical toggle switches having a spring-biased roller type of cam follower on the toggle lever have been used to cause a rocking movement of a pivoted actuator member having a cam surface thereon engageable with the roller to cause an overcenter movement of the actuator as shown in Landin U.S. Pat. No. 2,780,691 or Puccini U.S. Pat. No. 3,322,914. Since the pivot axes for the toggle lever and for the rocking actuator member in Landin U.S. Pat. No. 2,780,691 are both on one side of the point of contact between the roller and cam surface the actuator assembly would not be as unstable or resistant to teasing as would be an assembly wherein the respective roller and cam-contacting surfaces were intermediate the pivot points of the two pivoted members. Schellman U.S. Pat. No. 2,633,510 shows a roller in association with a contact member wherein the mounting for the roller is not pivoted but is mounted on one end of a spring. The roller member in Schellman would have no positive overcenter position since its wobbly spring mounting would cause its effective pivot point to shift with the changes in loading applied to the anchored end of the spring as it is bent.

SUMMARY

The toggle-type actuator assembly of the present invention includes a toggle lever pivotally mounted in the cover of a switch housing and a cradlelike actuator member pivotally rockable about an axis transverse of its length in a U-shaped support bracket affixed to the bottom of the switch housing. The ends of the actuator member may carry movable switch contacts which are adapted to contact fixed switch contacts in the housing. In a modified form of the invention, the ends of the cradlelike actuator member may be used to depress the pushbuttons of one or more switches affixed to the housing.

The actuator member is formed with a pair of upwardly extending trunnions which cradle and support the shaft of a roller mounted therein in such a manner that the axis of the roller is positioned parallel to the pivot axis of the actuator member and in a plane generally perpendicular to the general plane of the actuator which includes the pivot axis of the actuator. The roller on the actuator member is adapted to be engaged, to cause overcenter movement of the actuator member, by a spring-loaded cam member which is telescopically mounted within the toggle lever. The cam member on the toggle lever may be of various shapes such as, for example, a bullet-nosed member which is biased into contact with the roller at all times. When the cam member in the toggle lever is moved, by movement of the toggle lever, past a line connecting the actuator member pivot axis, and the roller pivot axis, it will cause an overcenter snap movement of the roller and actuator member about the actuator member pivot axis which will drive the actuator member to its opposite extreme position. Due to the presence of the roller member on the actuator, the mechanism is extremely teaseproof since the roller will roll as the cam member on the toggle lever is moved along its surface. By having the pivot axis for the actuator member and the pivot axis for the toggle lever positioned at points on opposite sides of the point of contact between the cam member and the roller member, the assembly is extremely unstable from the standpoint that it is almost impossible to tease as compared to having both pivot axes on the same side of the point of contact.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view of a switch housing incorporating the improved actuator assembly taken on the line 1-1 of FIG. 2, except that the working parts other than the toggle lever are left whole;

FIG. 2 is an end sectional view taken on the line 2-2 of FIG. 1;

FIG. 3 is an exploded view showing the relationship between the roller, the actuator member and the actuator member support bracket; and

FIG. 4 is a diagrammatical side view of a modified form of actuator assembly wherein the actuator member operates the pushbuttons for a plurality of switches rather than carrying self-contacts as in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1, the improved actuator assembly indicated generally at 10 is mounted in a switch housing indicated generally at 12 which supports a pair of fixed contacts 14, 16 which are respectively integrally fastened to external terminal members 18, 20. A common terminal element 22 is affixed to the housing and to a generally U-shaped bracket 24 therein by means of a rivet 26. The U-shaped bracket member 24 has a pair of inwardly projecting deformations 28 which comprise pivot centers adapted to be engaged by mating depressions 30 formed in the opposite sides of actuator member 32. Arranged centrally of the actuator member 32 and attached thereto is a cradle support bracket 34 having a pair of trunnions 36 which engage the shaft ends 38 of a roller member 40. Movable contact members 42, 44 are attached at opposite ends of the actuator member 32 for selective engagement with the fixed contact members 14, 16.

A toggle lever 48 for operating the switch is pivotally mounted in the switch cover member indicated generally at 50. The cover member 50 comprises an upper plate member 52 having upwardly extending spherically shaped deformations 54 for engaging a spherical surface 56 formed on the toggle lever. Attached to the upper plate member 52 is a lower plate member 58 having downwardly extending spherically shaped deformed portions 60 adapted to engage the lower portion of the spherical surface 56 on the toggle lever 48. In order to maintain a firm mounting for the spherical portion 56 of the toggle lever 48 in plates 52, 58, a strip of resilient material 62 such as rubber is positioned between the plates 52 and 58 to permit the spherical deformations 54 and 60 to be maintained in slight compressive relationship with the toggle lever. The layers 52, 58 and 62 of the cover 50 may be held together by means such as rivets 64. Mounted in telescopic relationship with the toggle lever 48 is a bullet-nosed fiber cam member 70 including a conical cam surface 72 terminating at its end in a spherical tip portion 74.

In operation of the actuator assembly, the toggle lever is pivoted from its solid line position shown in FIG. 1 to the second dotted position shown. During this movement, the cam member 70 is moved upwardly against the force of spring 76 as cam surface 72 moves upwardly along the surface of roller 40. Since the roller 40 has its shaft mounted in trunnions 36, it is free to rotate as cam surfaces 72 and 74 move over it with very little friction being produced to counteract the movement of toggle lever 48. Furthermore, the lifting of the cam member 70 against the force of spring 76 will increase the force exerted on the roller 40 and the actuator 32 which in turn will tend to increase the force with which movable contact 42 bears on fixed contact 14. This increased force on the contacts will be released instantaneously and the movable contact 44 will be snapped into engagement with fixed contact 16 as the point of tangency between cam tip 74 and roller 40 passes through the point a on the roller. Point a is the overcenter point at which the point of tangency is in line with the line b which passes through the axis of the actuator pivot 28 and the roller shaft 38. By insuring that the contact force does not drop off during a switching operation, the switch can provide long operational life without arcing.

By mounting roller 40, as shown in FIG. 1, so that the axis of its support shaft 38 and its point of tangency a with the cam surface 74 is intermediate the pivot point for the toggle lever 48 and the actuator pivot point 28, the cam member 70 and the roller 40 are in an extremely unstable relationship to each other as cam tip 74 approaches the line b at which the actuator member 32 will snap overcenter. This unstable situation is enhanced by the fact that the cam member 70 is at its extreme upward position at this time so that it exerts the most spring force on the roller. Furthermore, since each of the surfaces 74 and 40 are curved and in rolling contact as they pass line b, there is no sliding friction present to impede the snap action of the actuator member 32 as would be the case if the respective contacting members were in sliding rather than rolling relationship.

In FIG. 4, the actuator assembly of the invention is diagrammatically shown in association with a pair of pushbutton switches 80, 82 having pushbuttons 84, 86 respectively, for operating the electrical contacts within them. Since certain users of switches specify that the axis of the toggle lever point to the contacts which are closed (a condition not met by the embodiment of FIG. 1 wherein pivot axis 28 is below, rather than above the axis of roller shaft 38), it should be noted that the embodiment of FIG. 4 wherein the actuator member 32' merely actuates other switches rather than carrying contacts could be used since the switches 80, 82 can readily be obtained with contacts which are either in a normally open or a normally closed position.

Claims

I claim:

1. In an actuator assembly for making and breaking the contacts of an electric switch having a housing, a toggle lever member pivoted in the housing and an actuator member pivoted in the housing and engageable by the toggle lever to cause the switch contacts to be moved relative to each other, the improvement comprising: pivot means mounted in said housing for supporting said actuator member, at least one roller mounted on said actuator member for rotational movement about an axis thereon spaced at a fixed distance from the axis of said pivot means for said actuator member, the axis of the roller being positioned intermediate a cooperating member for engaging the roller and the axis of the actuator member pivot means, said cooperating member being resiliently biased into engagement with said actuator member and mounted for movement on the toggle lever in the direction of the length of the toggle lever, said cooperating member having a generally conical shape terminating in a generally spherically shaped apex tip which is resiliently biased into continuous rolling engagement with said roller on said actuator member and adapted to rock said actuator in one direction or the other as it moves past a point on said at least one roller which is in line with the axis of the roller and the axis of said pivot means.

2. An actuator assembly as defined in claim 1 wherein said actuator member comprises a rocking plate carrying a contact at at least one of its ends, said contact on said rocking plate being movable into and out of engagement with a fixed contact mounted in the housing.

3. An actuator assembly as defined in claim 2 wherein said rocking plate has contacts on each of its ends adapted to be brought into alternate engagement with a pair of cooperating fixed contacts in the housing.

4. An actuator assembly as defined in claim 3 wherein the rocking plane is mounted within a U-shaped bracket member having a pair of inwardly projecting spherical deformations defining pivot centers which are engaged by mating depressions formed on opposite sides of the actuator member.