US3320379A

US3320379A - Snap action electrical switch

Info

Publication number: US3320379A
Application number: US486741A
Authority: US
Inventors: Robert D Franzene
Original assignee: Deltrol Corp
Current assignee: Deltrol Corp
Priority date: 1965-09-13
Filing date: 1965-09-13
Publication date: 1967-05-16
Anticipated expiration: 1984-05-16

Description

M y 3%? R. D. FRANZENE SNAP ACTION ELECTRICAL- SWITCH Filed Sept. 13, 1965 United States Patent 3,320,379 SNAP ACTION ELECTRICAL SWITCH Robert D. Franzene, Chicago, Ill., assignor to Deltrol Corp., Bellwood, 11]., a corporation of Delaware Filed Sept. 13, 1965, Ser. No. 486,741 7 Claims. (Cl. 20076) This invention relates to electric switches, and has more particular reference to improvements in snap acting switches.

In general, it is the object of this invention to provide an exceptionally simple and low cost but rugged electric switch, wherein snap action is achieved with a spring contactor blade that is driven lengthwise over a supporting surface between switch open and switch closed positions by an actuator that is constrained to rock about a fixed axis and has a direct overcenter type driving connection with the contactor blade whereby the latter yieldingly holds the actuator at limits of motion corresponding to the switch open and switch closed positions of the contactor.

According to this invention, the contactor is directly confined between said supporting surface and the actuator, the stationary contacts are located near the opposite ends -of the supporting surface and project above it for engagement by the opposite end portions of the cont-actor blade in the switch closed position thereof, the actuator holds the opposite endrportions of the contactor blade engaged with both stationary contacts in the switch closed position and in engagement with one stationary contact and the supporting surface in the switch open position and at all times exerts downward force on an intermediate portion of the blade so that the restoring force of the blade in either of-said positions thereof imposes a turning moment on the actuator to yieldingly hold it at its corresponding limit of motion.

In the arrangement described, the actuator has a cont actor driver which swings toward one or the other of the stationary contacts, past an intermediate dead center position at which it is closest to the supporting surface, and the tendency for the stress in the contactor to decrease as the driver recedes from the supporting surface is overcome by reason of the fact that the driver moves closer to contact surfaces on the stationary contacts that are at a level above the supporting surface as the actuator approaches either limit of its motion. Hence, the restoring force in the contactor blade can be employed to positively but yieldingly hold the actuator at both of its limits of motion, and the switch operates with the desired snap action as the driver is moved in either direction pastits dead center position.

It is also a purpose of this invention to provide an electric switch of the character described featuring a housing comprising a body with a cavity in one side thereof to receive the contactor and the actuator, a cover to close the cavity and retain the actuator and contactor therein, and wherein a pair of screws that hold the cover in place on the body extend through its cavity to also provide the stationary contacts for the switch. These screws have cylindrical contact surfaces which project slightly above the wall of the cavity that defines the supporting surface to make it easier for one end portion of the contactor blade to ride up onto its stationary contact from the supporting surface along which it slides during switch closing motion of the contactor.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawing illustrates one complete example of the physical embodiment of the invention, constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

FIGURE 1 is an elevational view of an electric switch constructed in accordance with this invention;

FIGURE 2 is a sectional view taken along the line 2-2 in FIGURE 1;

FIGURE 3 is a sectional view taken on the plane of the line 3-3 of FIGURE 2, looking into the open side of the switch body and illustrating the closed position of the switch;

FIGURE 4 is a view similar to FIGURE 3 but showing the open position of theswitch; and

FIGURE 5 is a perspective view of the contactor blade per se.

Referring now to the accompanying drawing, the switch of this invention comprises a housing 5 of insulating material and. consisting of a generally block-like body 6 and a flat rectangular cover 7 secured to one fiat side of the body by a pair of screws 10. A cavity 11 formed in the body contains the switch contactor 12 and the actuator 13 by which the contactor is moved toward and from a switch closed position. This cavity opens to the side of the body which is closed by the cover 7, audit has substantially uniform depth so that the bottom of the cavity is parallel to the underside of the cover. The contactor 12 is in the form of an elongated blade made from a length of flat spring stock, and it has opposite short and long arms 14 and 15, respectively, which project in opposite directions from an upstanding drive abutment 16 on the contactor. An intermediate portion of the contactor blade is deformed to provide the drive abutment, which has an inverted U- shape. In its free state, the opposite arms 14 and 15 of the contactor assume downwardly divergent positions such as seen best in FIGURE 5. i j

A substantially narrow, horizontally elon gated portion 17 of the body-cavity defines a compartment longer than the contactor blade and in which the latter is endwise slidably received. One wall of this compartment provides an upwardly facing supporting surface 18 over. which the contactor arms are fiatwise disposed, and alongwhich the contactor slides lengthwise between switch open'and switch closed positions. The stationary contacts 19 and 20 of the switch are located in this compartment, near the op posite ends thereof but with the contact 20 s pac'edslightly farther from its adjacent end of the compartment.

It is a feature of this invention thatthe stationary contacts are provided by cylindrical shanks on'"the same screws 10 that hold the cover in place on the body, and that they are disposed with their cylindrical contact surfaces facing upwardly for cooperation with the opposite end portions of the contactor blade, and projecting slightly above the level of the supporting surface 18 extending between them.

The contactor blade, of course, has a length sufficient to bridgingly engage the contact surfaces of both stationary contacts in the switch closed position thereof seen in FIG- URE 3. When it is moved bodily endwise to the right from its FIGURE 3 position, its short arm 14 slides off of the stationary contact 19 and down onto the supporting surface 18, while its opposite arm 15 remains slidingly engaged with the remaining stationary contact 20.

The cavity 11 also has a portion 21 that opens upwardly to the top of the body from a zone directly above the supporting surface 18 between the two stationary contacts 19 and 20, and which defines a compartment that accommodates the actuator 13. The actuator has a substantially cylindrical hub 22 of a size to loosely fit the width and depth of the compartment 21. A trunnion 23 formed integrally therewith and projecting from its underside into a bore 24 in the body serves to mount the actuator for rocking motion about a fixed horizontal axis above the supporting surface 18, and midway between the stationary contacts 19 and 20. A lever 25 projecting upwardly from the hub to the exterior of the body enables rocking motion to be manually imparted to the actuator between limits defined by the engagement of the sides of the lever with stop abutments 26 and 27 defined by the sides of the actuator compartment at its mouth.

Rocking motion of the actuator is translated into endwise sliding motion of the contactor blade through drive means on the actuator directly interengaged with the drive abutment 16 on the contactor. This drive means is here shown as a notch 28 in the periphery of the actuator hub, on the underside thereof, into which the drive abutment 16 on the contactor projects. The notch is proportioned to accommodate the drive abutment 16 during all rocking motion of the actuator between its limits of motion, and to also hold the contactor blade confined under stress between the underside of the actuator and the supporting surface 18 therebeneath.

Hence, while the arms 14 and 15 of the contactor tend to normally assume outwardly divergent positions such as seen in FIGURE 4, the actuator exerts downward force on the intermediate portion of the contactor blade and fiexes it toward the supporting surface 18 to an extent such that its arms 14 and 15 are held substantially coplanar regardless of whether the contactor is in bridging engagement with its stationary contacts as seen in FIGURE 3, or in its switch open position seen in FIGURE 4.

When the actuator is at its limit of motion defined by the stop abutment 27, its drive notch 28 faces toward the stationary contact 19 and its bottom is located to the left of a vertical plane containing the actuator axis. In this position, the actuator holds the contactor blade in its switch closed position at which its arms are pressed down onto the contact surfaces of the stationary contacts 19 and 20, and the restoring force of the contactor blade is translated into a turning moment on the actuator through the engagement of the drive abutment 16 with the bottom of the notch in the actuator, by which the actuator is firmly but yieldingly held in its switch closed limit of rocking motion. As shown in FIGURE 3, the contactor blade can be wholly supported by the stationary contacts in its switch closed position, with its entire length spaced above the supporting surface 18.

When the actuator is rocked in the counterclockwise direction to its opposite or switch open limit of motion seen in FIGURE 4, the drive notch 28 in its underside faces toward the stationary contact 20, and its bottom is located to the right of the vertical plane containing the actuator axis. At this position of the actuator, the contactor blade is held under stress thereby with its long arm 15 in engagement with the stationary contact 20 and its short arm 14 in engagement with an area of the supporting surface 18 spaced intermediate the contacts 19 and 20. Consequently, the restoring force of the blade causes the drive abutment thereon to push against the bottom of the notch in the actuator and exert force on the actuator tending to firmly but yieldingly hold it in its switch open a position.

It should be observed that the actuator imposes maximum stress upon the contactor blade when the drive notch 28 in the underside of the actuator hub is at a dead center position with its bottom closest to the supporting surface 18 and intersected by a vertical plane containing the actuator axis. The drive notch recedes from the surface 18 as it is moved in either direction out of this dead center position, and ordinarily this would tend to progressively and objectionably relieve stress on the contactor blade as it approaches its switch open and switch closed positions. This tendency is substantially overcome in the switch of this invention, due to the fact that the contact surfaces of the stationary contacts 19 and 20 project above the level of the supporting surface 18. Thus. as the contactor blade is shifted to the right from its switch closed position and approaches its switch open position seen in FIGURE 4, its drive abutment 16 moves progressively closer to the stationary contact 20 upon which the long arm 15 of the blade is supported and is lifted slightly by said stationary contact to more or less offset any reduction in stress caused by the recession of the bottom of the notch 28 from the supporting surface 18.

Similarly, as the contactor blade is shifted to the left from its switch open position toward its switch closed position seen in FIGURE 3, the short arm 14 of the blade slides along the supporting surface 18 and rides up onto the elevated surface of the stationary contact 19, to thus lift up the drive abutment 16 on the blade and maintain it properly stressed. The extremity of the short arm 14 of the contactor blade is bent up slightly, as at 30, to enable it to readily slide up onto the contact surface of its stationary contact.

With the construction described, the restoring force of the contactor blade is utilized to achieve a highly desirable snap action by which the actuator is more or less snapped to and heldin either limit of motion thereof after it has been manually moved half way out of its other limit of motion.

Also, the cover holding screws 10 which provide the stationary contacts also afford switch terminals to which wire leads can be connected in the manner indicated in FIGURES l and 2. A lug 32 on the bottom of the body can have a threaded hole to receive a junction screw (not shown), and apertured mounting lugs 33 can be formed on the opposite ends of the body to facilitate attachment of the switch to a suitable support.

The cover 7, of course, holds the contactor and the actuator in place within the body cavity, and the whole assembly is secured by the two cover screws 10 which provide the switch terminals and the stationary contacts.

From the foregoing description, together with the accompanying drawings, it will be readily apparent to those skilled in the art that this invention achieves an unprecedented degree of simplicity in an electrical snap acting switch featuring a bodily movable contactor blade.

What is claimed as my invention is:

1. An electric switch having a housing of electrical insulating material with an elongated upwardly facing substantially fiat supporting surface that extends lengthwise between a pair of stationary contacts in its interior, at a level adjacent to but .below the contact surfaces of said contacts, a resiliently flexible contactor blade which is movable lengthwise over the supporting surface between switch open and switch closed positions, and an actuator drivingly connected with the contactor for moving the same to said positions thereof in consequence of movement of the actuator between defined limits corresponding to said positions, wherein the improvement comprises:

(A) means mounting the actuator on the housing for pivotal motion about a fixed axis which is disposed 1) transverse but substantially parallel to said supporting surface, (2) and over a zone of said surface intermediate the stationary contacts;

(B) means fixed with respect to the actuator providing contactor drive means which faces toward said supporting surface and which moves bodily with the actuator arcuately across said intermediate zone of the supporting surface from a position at either side of said zone thereof during pivotal movement of the actuator between its limits of motion;

(C) said contactor blade having (1) a first arm at all times engaged with one stationary contact,

(2) a second arm cooperable with the other stationary contact,

(3) and a part intermediate and connecting said arms and positively and directly interengaged with said drivemeans'to constrain the contactor to move in unison with the contactor and thereby provide said driving connection therebetween;

(D) said second contactor arm bearing upon the supporting surface in spaced relation to said other stationary contact in the switch open position of the contactor, and being movable off of the supporting surface and onto said other stationary contact in consequence of actuation of the contactor to its switch closed position;

(E) and said drive means cooperating with said part on the contactor to flex the latter toward the supporting surface and thereby maintain the contactor arms so stressed that in each of its switch open and switch closed positions the restoring force in the contactor arms exerts a turning moment of substantial magnitude upon the actuator through the drive means thereon to positively but yieldingly hold the actuator at its corresponding limit of motion.

2. The switch of claim 1 wherein said drive means comprises a notch in the actuator opening toward the supporting surface; and wherein said part of the contactor comprises an upwardly deformed driving abutment integral with said arms of the contactor blade and having a rounded end engaging in said notch in the actuator.

3. A snap switch having walls defining a housing of electrical insulating material, an actuator movable between defined limits, a resiliently flexible contactor blade having an overcenter driving connection with the actuator and confined between it and an elongated substantially fiat upwardly facing surface on one of said walls, the contactor being movable lengthwise bodily over said wall surface toward and from bridging engagement with a pair of stationary cont-acts having contact surfaces that project above lengthwise spaced portions of said wall surface, wherein the improvement comprises:

(A) means pivotally mounting the actuator on the housing over a zone of said wall surface intermediate the stationary contacts, for pivotal motion about a fixed axis transverse to said wall surface;

(B) drive means on the actuator movable therewith from a position at one side of said zone and facing one of the contacts at one limit of the actuator, to a position at the other side of said zone and facing the other contact at the other limit of the actuator, past a dead center position directly over and adjacent to said intermediate Zone and at which dead center position the drive means is closest to said wall surface;

(C) the contactor having (1) opposite end portions which are respectively cooperable with the stationary contacts,

(2) a part thereon intermediate its ends cooperating with the drive means on the actuator to provide said overcenter driving connection between the contactor and actuator and so engaged with said drive means that the contactor is at all times stressed toward said wall surface and is constrained to slide endwise over said wall surface in consequence of pivoting of the actuator from one limit of motion to the other, between a switch open position at which the opposite end portions of the contactor bridgingly engage the contact surface of one stationary contact and a portion of said wall surface intermediate and spaced from both stationary contacts, and a switch closed position at which both end portions of the contactor bear upon the contact surfaces of their respective stationary contacts,

(D) and the restoring force of the contactor blade exerting a turning moment upon the actuator through said drive means thereon at each limit of motion of the actuator whereby the latter is yieldingly held at its limits of motion by the contactor blade.

4. The'snap switch of claim 3, wherein one end portion of the contactor blade is at all times engaged with its stationary contact and slides back and forth upon the contact surface thereof during switch opening and switch closing motion of the contactor; and wherein the other end portion of the contactor slides olf of the contact surface of its respective stationary contact, down onto said housing wall surface, and hasits extremity bent upwardly so that it can more easily slide up onto its contact surface during switch closing motion of the contactor.

5. An electric switch of the type having a resilient contactor movable back and forth between switch open and switch closed positions, a pivoted actuator which has an overcenter driving connection with the contactor utilizing the resilience of the latter to yieldingly hold the actuator in defined positions corresponding to said positions of the contactor, and a housing for the switch including a body having a cavity opening to one side thereof and a cover secured to said side of the body in spaced relation to the bottom of the cavity and closing the latter, wherein the improvement comprises:

(A) an elongated substantially fiat upwardly facing supporting surface provided by one side wall portion of the cavity and extending lengthwise along the inner side of the cover;

(B) stationary contacts comprising a pair of screws that pass through the cover and into the body to hold the cover in place thereon, said screws extending crosswise of the supporting surface at opposite sides of a medial zone thereof and having cylindrical contact surfaces which project above the level of the supporting surface and lie in a plane parallel thereto;

(C) means mounting the actuator on the body for pivotal motion about a fixed axis parallel to but crosswise of the supporting surface and over said medial zone thereof;

(D) contactor drive means on the underside of the actuator movable back and forth therewith toward the opposite ends of said surface, to opposite sides of its medial zone and past a dead center position under the actuator pivot axis and at which the contactor drive means is closest to said surface;

(E) the contactor comprising an elongated spring blade beneath the actuator and lengthwise overlying the supporting surface, said blade being slidable endwise from a switch closed position bridgingly engaging the contact surfaces of the stationary contacts to a switch open position at which one end portion of the blade is disengaged from its adjacent stationary contact and the opposite end portions of the blade are in bridging engagement with the contact surface of the other stationary contact and with the supporting surface;

(F) and a part on the medial portion of the contactor blade drivingly engaged with the contactor drive means to provide said overcenter driving connection and upon which the actuator exerts downward force to hold the blade stressed toward the supporting surface, whereby the restoring force in the blade acts upon the actuator to yieldingly hold the same in each of said positions thereof.

6. The electric switch of claim 5, further characterized by the following:

(A) that said cavity also defines a communicating actuator compartment in the body, which opens upwardly to the top of the body and laterally to said side of the body;

(B) that the body has a bore which opens to said compartment and has its axis normal to the cover;

(C) that the actuator has a trunnion thereon received in said bore to mount the actuator for rocking motion toward and from switch closed and switch open positions, and also has an operating lever projecting upwardly from the compartment to the exterior of the body to facilitate manual movement of the actuator; (D) and that said cover overlies and holds the actuator and the contactor in place within the housing. 7. The electric switch of claim 5, wherein the contactor drive means comprises a notch in the underside of the actuator, and the contactor has an upwardly deformed abutment thereon which is drivingly engaged in said notch and through which the restoring force of the contactor blade is translated into turning moments on the actuator whereby the actuator is yieldingly held at each of its said positions by the contactor.

References Cited by the Examiner UNITED STATES PATENTS Dessinger 200-76 Hickman.

Bonnaire 200-166 Gluck 200-16 ROBERT K. SCHAEFER, Primary Examiner.

m D. SMITH, Assistant Examiner.

Claims

1. AN ELECTRIC SWITCH HAVING A HOUSING OF ELECTRICAL INSULATING MATERIAL WITH AN ELONGATED UPWARDLY FACING SUBSTANTIALLY FLAT SUPPORTING SURFACE THAT EXTENDS LENGTHWISE BETWEEN A PAIR OF STATIONARY CONTACTS IN ITS INTERIOR, AT A LEVEL ADJACENT TO BUT BELOW THE CONTACT SURFACES OF SAID CONTACTS, A RESILIENTLY FLEXIBLE CONTACTOR BLADE WHICH IS MOVABLE LENGTHWISE OVER THE SUPPORTING SURFACE BETWEEN SWITCH OPEN AND SWITCH CLOSED POSITIONS, AND AN ACTUATOR DRIVINGLY CONNECTED WITH THE CONTACTOR FOR MOVING THE SAME TO SAID POSITIONS THEREOF IN CONSEQUENCE OF MOVEMENT OF THE ACTUATOR BETWEEN DEFINED LIMITS CORRESPONDING TO SAID POSITIONS, WHEREIN THE IMPROVEMENT COMPRISES: (A) MEANS MOUNTING THE ACTUATOR ON THE HOUSING FOR PIVOTAL MOTION ABOUT A FIXED AXIS WHICH IS DISPOSED (1) TRANSVERSE BUT SUBSTANTIALLY PARALLEL TO SAID SUPPORTING SURFACE, (2) AND OVER A ZONE OF SAID SURFACE INTERMEDIATE THE STATIONARY CONTACTS; (B) MEANS FIXED WITH RESPECT TO THE ACTUATOR PROVIDING CONTACTOR DRIVE MEANS WHICH FACES TOWARD SAID SUPPORTING SURFACE AND WHICH MOVES BODILY WITH THE ACTUATOR ARCUATELY ACROSS SAID INTERMEDIATE ZONE OF THE SUPPORTING SURFACE FROM A POSITION AT EITHER SIDE OF SAID ZONE THEREOF DURING PIVOTAL MOVEMENT OF THE ACTUATOR BETWEEN ITS LIMITS OF MOTION; (C) SAID CONTACTOR BLADE HAVING (1) A FIRST ARM AT ALL TIMES ENGAGED WITH ONE STATIONARY CONTACT, (2) A SECOND ARM COOPERABLE WITH THE OTHER STATIONARY CONTACT, (3) AND A PART INTERMEDIATE AND CONNECTING SAID ARMS AND POSITIVELY AND DIRECTLY INTERENGAGED WITH SAID DRIVE MEANS TO CONSTRAIN THE CONTACTOR TO MOVE IN UNISON WITH THE CONTACTOR AND THEREBY PROVIDE SAID DRIVING CONNECTION THEREBETWEEN; (D) SAID SECOND CONTACTOR ARM BEARING UPON THE SUPPORTING SURFACE IN SPACED RELATION TO SAID OTHER STATIONARY CONTACT IN THE SWITCH OPEN POSITION OF THE CONTACTOR, AND BEING MOVABLE OFF OF THE SUPPORTING SURFACE AND ONTO SAID OTHER STATIONARY CONTACT IN CONSEQUENCE OF ACTUATION OF THE CONTACTOR TO ITS SWITCH CLOSED POSITION; (E) AND SAID DRIVE MEANS COOPERATING WITH SAID PART ON THE CONTACTOR TO FLEX THE LATTER TOWARD THE SUPPORTING SURFACE AND THEREBY MAINTAIN THE CONTACTOR ARMS SO STRESSED THAT IN EACH OF ITS SWITCH OPEN AND SWITCH CLOSED POSITIONS THE RESTORING FORCE IN THE CONTACTOR ARMS EXERTS A TURNING MOMENT OF SUBSTANTIAL MAGNITUDE UPON THE ACTOR THROUGH THE DRIVE MEAND THEREON TO POSITIVELY BUT YIELDINGLY HOLD THE ACTUATOR AT ITS CORRESPONDING LIMIT OF MOTION.