US3270573A

US3270573A - Snap action switch

Info

Publication number: US3270573A
Application number: US269113A
Authority: US
Inventors: Samuel H Schwartz
Original assignee: Dole Valve Co
Current assignee: Dole Valve Co
Priority date: 1963-03-29
Filing date: 1963-03-29
Publication date: 1966-09-06
Anticipated expiration: 1983-09-06

Description

Sept. 6, 1966 s. H. SCHWARTZ 3,270,573

SNAP ACTION SWI TCH Filed March 29, 1963 United States Patent '0 Illinois Filed Mar. 29, 1963, Ser. No. 269,113 9 Claims. (Cl. 74-97 This invention relates to snap action motion translation devices whereby the relatively slow movement of a first member will be transmitted at a given instant to a second member with a rapid and powerful stroke.

Snap action mechanisms have been in use for a number of years and have found particular utility in electrical switches.

The usual type of snap action switch mechanism comprises a frame having a short snap blade and an elongated snap lever pivotally mounted about the same axis on the frame. A compression spring interconnects the free end of the snap blade with the free end of the snap lever so that when the spring connection point on the snap blade is moved past the plane of the snap lever the lever will be urged in a direction opposite that of the blade with a rapid snap motion. If the mechanism is incorporated in an electrical switch the snap lever ordinarily constitutes the movable contact of the switch and is engageable in one or the other of its extreme positions with a stationary contact. Some times of course the snap lever engages different contacts at each end of its pivotal stroke in a double pole switch.

Oftentimes, for the sake of simplicity and inexpensive construction, the snap lever and snap blade are merely formed from a flexible material such as a thin metal and the ends thereof are rigidly secured to the frame support so that the lever and blade simply move in one direction or the other as the operator moves the blade to one side or the other of the lever but the result is the same as if their ends were actually pivoted on the supporting frame.

A significant drawback in such snap action mechanisms resides in the fact that very little force is exerted by the snap lever at that instant when the snap blade has just moved past the plane of the snap lever. In fact, little force is exerted by the lever until the free ends of the snap blade and snap lever have been moved apart a substantial distance. That is, in a conventional snap mechanism the main snap lever exerts a zero force at the beginning of its stroke which will build up as the lever moves following a sine curve approximately. This characteristic is not particularly disadvantageous when a snap action mechanism is employed in an electrical switch.

However, it has now been found desirable to employ snap action mechanisms in other environments for the purpose of carrying a considerable work load. For instance, it has been proposed that a mechanism of this type be employed to shift a motor drive belt back and forth on a two-speed sheave in an automatic dryer. Such an application requires a quick motion and an immediate application of a substantial force which must, of course, persist throughout the stroke of the snap lever.

The motion translation device which I have devised is effective to translate a slow pivotal stroke of the snap blade (which I hereafter refer to as an actuating lever) into a rapid pivotal snap lever (main lever) stroke. In addition, the motion translation device which I have devised has a very considerable snap lever power output because I have radically improved the leverage advantage between the snap blade and the snap lever.

The device which will hereafter be described with more particularity includes a snap blade or actuating lever and a snap lever or main lever as does the usual type of snap action mechanism. These members are each pivotally mounted on a frame, preferably about the same axis. An additional toggle element however is added to the mechanism and this toggle is pivotally mounted on the free end of the main lever. A compression spring interconnects the free end of the actuating lever with the toggle element so that when the spring connection point on the actuating lever is moved on one side or the other of the plane of the toggle element the toggle element will first be pivoted relative to the main lever and the main lever will then be pivoted by the action of the spring on the toggle element with respect to the frame.

The primary advantage achieved by construction of a device of this character is that the toggle element is first pivoted relative to the main lever without any substantial resistance to its movement and when the toggle element has been thus pivoted there is a considerable leverage advantage between the free end of the actuating lever and the free end of the toggle element. It is not until the actuating lever and the toggle element are thus disposed that any movement of the main lever is effected. Obviously, when the main lever does begin to move there is a considerable spring load applied to it to effect such movement and the power output of the mechanism is considerable.

I have also designed the mechanism so that, in combination with a temperature sensitive power unit, it will be thermostatically actuable.

In view of the foregoing, it is a principal object of my invention to provide an improved motion translation device in which snap actuation of a lever can be effected and in which considerable force can be applied to the lever throughout its pivotal stroke.

Another object of my invention resides in the provision of a snap action motion translation mechanism in which the usual over-center spring acquires a considerable leverage advantage before effecting pivotal movement of the main lever.

Another object of my invention as directed to the provision of a thermostatically actuable snap action mechanism of the character above described.

These and other objects, features and advantages of my invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings, wherein:

FIGURE 1 is an exploded view of a thermostatically actuable motion translation device constructed in accordance with the principles of my invention;

FIGURE 2 is a diagrammatic representation of a motion translation device shown in a first position;

FIGURE 3 is a diagrammatic representation of the device illustrated in FIGURE 2 but showing the mechanism in a second position; and

FIGURE 4 is a diagrammatic representation of a different form of a motion translation device constructed in accordance with the principles of my invention.

Referring initially to FIGURE 1, a frame 10 is generally U-shaped in configuration and has a base wall 11 centrally apertured at 12 and a pair of spaced vertically extending legs 13 and #14. The base wall 11 rests on a diametrically enlarged collar 15 of a temperature sensitive power unit 16 which also has a temperature sensing portion 17, a power member guide '18, and a power member 19 mounted for axial movement within the guide 18 in a manner well understood by those skilled in this art.

The temperature sensitive power unit =16 is of the wellknown solid sfill type having a crystalline wax or a similar temperature sensitive substance within the temperature sensing portion 17 thereof and having a diaphragm extending across the interior of the unit where the collar '15 is so that thermal expansion of the wax with-in the sensing portion 17 will be transmitted through the diaphragm to the power member 19 abutting the diaphragm to effect extensible movement of the power member '19 relative to the guide 18.

Portions of the temperature sensitive power unit 16 are peened over the base wall 11 of the frame to rigidly secure the frame to the power unit.

An actuating lever 20 is somewhat T-shaped in configuration having a pair of outwardly extending wings 21 extending therefrom and having a nose 22 extending from the opposite end thereof. The lever is fiat and has a pair of projections 23 extending upwardly from the upper surface thereof.

The actuating lever 20 is pivotally mounted on the legs 13, 14 of the U-sh-aped frame 10 by the wings 21 which extend through coaxially aligned apertures 24 formed within reariwardly extending tabs 25 which, in turn, are formed integrally with the legs 13, 14 of the frame 10.

It will be observed that the under-surface of the actuating lever 20 rests on the outer free end of the power member 19 and that it is biased into engagement with the power member by a compression spring 26 which is interposed between the lever 20 and a pair of spring retaining fingers 27. The fingers 27 are formed integrally with the frame 10 and have downturned nibs 28 which assure that the spring 26 will be centered in its proper position. The upstanding nibs 23 on the lever 20 serve the same purpose for the lower end of the spring 26.

It will be observed that the wings 21 are of such a length that they extend completely through the tabs 25 and for a short distance past the outer surfaces thereof to provide a pivot for the main lever. The main lever 30 is also U-shaped in con-figuration and has an end Wall 3-1 and a pair of integral rearwardly extending spaced lugs 32, 33 which are apertures as at 34. The apertures 34 in the legs 32, 33 receive the outwardly extending end portions of the wings 21 so that the main lever 30 is pivotally mounted on the Wings 21 and hence about the same pivotal axis as the actuating lever 20.

A depending tab 35 is formed integrally with and extends from the end wall 31 of the main lever 30 and has an aperture 36 formed therein which serves as a connection point for any element which is to be operated by pivotal movement of the lever '30.

A T-shaped toggle 40 is fiat and has a pair of outwardly extending wings 41 which are received within arcuately shaped apertures 42 formed with-in the legs 32, 33 of the main lever 30. The toggle has forwardly and rearwardly extending

noses

43 and 44 formed integrally therewith and the nose 43 is loosely fitted within an aperture 45 formed in the end wall 31 of the main lever 30 to center the toggle between the legs 32, 33 of the main lever. A knife edge bearing surface 46 is formed on the toggle element on each side of the nose 43 and is cooperable with a V- groove formed on the inner face of the end Wall 31 to pivotally mount the toggle element relative to the main lever 30.

A compression spring 47 interconnects the toggle 40 and the actuating lever 20 and is coiled about the

noses

44 and 22 on these two elements respectively.

A plurality of nibs 48 are tormed integrally with and extend outwardly from the legs 13, 314 of the U-shaped frame 10 and are positioned in the path of a pivotal movement of the main lever 30 to provide a means for limiting the degree of pivotal movement of that lever.

'It will be observed from a consideration of FIGURE 1 in connection with the diagrammatic representations of FIGURES 2 and 3 that when the spring connection point A of the actuating lever 20 is moved above the plane of toggle in that figure, the toggle element will be snapped rapidly from the full line position to the broken line position shown therein. There is of course no substantial resistance to such pivotal movement of the toggle element relative to the main lever 30.

It will be understood of course that the broken line position of the mechanism shown in FIGURE 2 is not an at-rest position and has been illustrated for clarity of description only. As soon as the toggle element has been moved to the broken line position of FIGURE 2 the spring will then act through the toggle element to pivot the main lever 30 relative to the frame 10. It will be observed however that the spring 4 7 has a considerable leverage advantage when such pivotal movement of the lever 30 is in'itated. It is primarily this feature of applicants device which constitutes such improvement over the prior known motion translation mechanisms.

Conversely, if the various parts of the mechanism are initially in the position shown in FIGURE 3, then movement of the spring connection point A above the plane of the toggle element will act first to pivot the toggle element upiwardly sothat it lies above the plane of the snap lever and then snap actuation of the lever itself will be effected.

The embodiment of the invention shown diagrammatically in FIGURE 4 has been included in this disclosure for the purpose of illustrating that the actuating element 20 need not be positioned so as to face in the same direction as the 'main lever 30 with respect to the frame 10. On the contrary, the lever might Iface rearwardly of the frame 10 but the principle of operation is, of course, substantially the same as that which has been heretofore described.

It will be understood that these embodiments of my invention have been illustrated and described for illustrative purposes only and various modifications and varia tions in my invention may be effected without departing from the spirit and scope of the novel concepts there-0t.

I claim as my invention:

1. A motion translation device comprising:

a frame,

an actuating lever and a main lever both pivotally connected to said frame and having free ends extending outwardly from said frame,

a toggle pivotally connected to the free end of said main lever and having a free end positionable on each side of a straight line intersecting the pivotal axes of said main lever and toggle,

means limiting the degree of pivotal movement of said toggle relative to said main lever and said main lever relative to said frame,

resilient means interconnecting the "free ends of said toggle and said actuating lever,

and means for positioning the free end of said actuating lever on each side of a line intersecting the spring connection point on said toggle and the pivotal axis of the toggle irrespective of the pivoted position of said toggle and irrespective of the pivoted position of said main lever.

2. A motion translation device comprising:

a frame,

a flat actuating lever and a flat main lever both pivotally connected to said frame and having free ends extending outwardly from said frame,

a flat toggle pivotally connected to the free end of said main lever and'h-aving a free end positionable on each side of the plane of said main lever,

means limiting the degree of pivotal movement of said toggle relative to said main lever and of said main lever relative to said frame,

a compression spring interconnecting the free ends of said toggle and said actuating lever,

and means for positioning the free end of said actuating lever on each side of the plane of said toggle irrespective of the pivoted position of said main lever.

3. A motion translation device comprising:

a vertically extending frame,

an actuating lever and a main lever pivotally connected to said frame and having free ends extending outwardly from said frame on the same side thereof,

a compression spring interconnecting the free ends of said toggle and said actuating lever, and means for positioning the free end of said actuating lever on each side of a line intersecting the spring connection point on said toggle and the pivotal axis thereof irrespective of the pivoted position of said main lever.

4. A motion translation device constructed in accordance with claim 1 wherein said levers are pivoted on said frame about the same axis.

5. A motion translation device comprising:

a frame,

an actuating lever pivotally connected to said frame and 'having a free end extending outwardly therefrom,

a U-shaped main lever having a pair of spaced legs pivotally connected to said frame about the pivotal axis of said actuating lever and having a free end extending outwardly therefrom,

a toggle pivotally connected to the free end of said main lever and having a free end disposed between the said legs of said main lever and positionable on each side of a straight line intersecting the pivotal axes of said main lever and said toggle,

and means for positioning the free end of said actuating lever on each side of a line intersecting the spring connection point on said toggle and the pivotal axis of the toggle irrespective of the pivoted position of said main lever.

6. A motion translation device constructed in accordance with claim 5 wherein said actuating lever is also positioned between the said legs of said main lever and extends outwardly from said frame in the same general direction as said main lever.

7. A motion translation device constructed in accordance with claim 5 wherein the means for limiting the degree of pivotal movement of said toggle relative to said main lever comprises at least one wing extending outwardly from said toggle and an associated arcuately shaped wing-receiving aperture formed in a leg of said U-shaped main leve-r.

'8. A motion translation device constructed in accordance with claim 5 wherein the means for limiting the degree of pivotal movement of said main lever relative to said frame comprises a pair of projections formed integrally with said 'frame and positioned in the path of pivotal movement of at least one leg of said main lever.

'9. A motion translation device constructed in accordance with claim '5 wherein the means for limiting the degree of pivotal movement of said toggle relative to said main lever comprises at least one wing formed integrally with and extending from said toggle and at least one cooperating arcuately shaped aperture formed within one leg of said main lever for receiving said toggle and wherein the means for limiting the degree of pivotal movement of said main lever relative to said frame comprises a pair of nibs formed integrally with and extending from said frame in the path of pivotal movement of at least one 'leg of said main lever.

References Cited by the Examiner UNITED STATES PATENTS 1,375,247 4/ 1921 Behrens 74-97 2,241,981 5/1941 Cerny 7497 X 2,334,007 1'1/1943- Hutt 20067 2,614,186 10/ 1952 Sutton et a1 7497 X 2,761,029 8/1956 Peabody 7497 X 3,001,401 9/1961 Vernet et al. 733-58 3,112,382 11/1963 Baker 200- X LOUIS R. PRINCE, Primary Examiner. D. M. YASICH, Assistant Examiner.

Claims

1. MOTION TRANSLATION DEVICE COMPRISING: A FRAME, AN ACTUATING LEVER AND A MAIN LEVER BOTH PIVOTALLY CONNECTED TO SAID FRAME AND HAVING FREE ENDS EXTENDING OUTWARDLY FROM SAID FRAME, A TOGGLE PIVOTALLY CONNECTED TO THE FREE END OF SAID MAIN LEVER AND HAVING A FREE END POSITIONABLE ON EACH SIDE OF A STRAIGHT LINE INTERSECTING THE PIVOTAL AXES OF SAID MAIN LEVER AND TOGGLE, MEANS LIMITING THE DEGREE OF PIVOTAL MOVEMENT OF SAID TOGGLE RELATIVE TO SAID MAIN LEVER AND SAID MAIN LEVER RELATIVE TO SAID FRAME, RESILIENT MEANS INTERCONNECTING THE FREE ENDS OF SAID TOGGLE AND SAID ACTUATING LEVER, AND MEANS FOR POSITIONING THE FREE END OF SAID ACTUATING LEVER ON EACH SIDE OF A LINE INTERSECTING THE SPRING CONNECTION POINT ON SAID TOGGLE AND THE PIVOTAL AXIS OF THE TOGGLE IRRESPECTIVE OF THE PIVOTED POSITION OF SAID TOGGLE AND IRRESPECTIVE OF THE PIVOTED POSITION OF SAID MAIN LEVER.