US2230720A

US2230720A - Snap action device

Info

Publication number: US2230720A
Application number: US278257A
Authority: US
Inventors: Samuel F Jarvis
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1939-06-09
Filing date: 1939-06-09
Publication date: 1941-02-04
Anticipated expiration: 1958-02-04
Also published as: GB536637A; DE730134C

Description

Feb. 4, 1941'. s. F; JARvls SNAP ACTION DEVICE Filed June 9, 1939 Inventor: 5am me! F`. Jarvis,

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Patented Feb. 4, l19.41

NPATENT OFFICE SNAP ACTION DEVICE Samuel F. Jarvis, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application June 9, 1939, Serial No. 278,257

Claims.

My invention relates to snap' action devices, more particularly to snap lswitches, snap valves and the like and has for its object a simple and reliable device of this character which has but few parts and which is inexpensive to manufacture.

In carrying out my invention I utilize a flat rectangular sheetor strip made of a suitable spring material such as bronze. This strip is preformed with a longitudinal bend along a transverse zone. It is causedto straighten with a snap action by depressing it on one side of the bend. When the pressure is removed, the strip snaps back to its longitudinally bent form.

For a more complete understanding of my invention,` reference should be hand to the accompanying drawing in which Fig. 1 is an elevation view with the casing in section of a manually operated switch embodying my invention; Fig. 2 is a plan view of the device shown in Fig. 1 with the cover removed; Fig. 3 is a sectional view taken along the line 3 3 of Fig. 1; Fig. 4 is a sectional view similar to Fig. 3 but showing the device in its snapped position; Fig. 5 is a fragmentary view in perspective of another form of the device.

Referring to the drawing', I have shown my invention in one form as applied to a push button operated switch. A snap action part or element of the device in the form shown consists of a at rectangular sheet or strip Ill made of a suitable spring metal such as bronze. In a typical device, a strip of bronze about of an inch Wide and ooo of an inchl thick was used.

The strip is bent longitudinally so as to give it a permanent set along a substantially straight zone or bend II `extending transversely of the strip. Thus the strip consists of two straight flat portions Illa and IIlb joined at an angle with each other by the bend I I.

To facilitate the snap action, the strip is mounted in a casing or base I3 having a longitudinal groove or depression I 4 in its bottom, and made of a suitable electrically insulating material such as a molded compound. The strip is secured at one end by screws I5 to the lbottom of the casing with the sides of one straight portion, as shown the portion IIlb, resting on the ledges I6 and I'I at each side of the depression I4 so as to be supported by the ledges against distortion downward in a direction substantially transverse to said bend. `The other portion Illa of the strip extends upward from the bend II.

A suitable button I8 is provided by means of which pressure can be conveniently applied to the strip. This button is shown being slidably secured in a cover I9 for the casing. The button furthermore is held by the cover in position to engage the portion IDb of the strip at a point at about its middle transversely of the strip, and 5 preferably, as shown spaced from but near the bend II. When pressure is removed from the button I8, or more specifically, when .the button is permitted to move upward a slight distance to its former position, the portion Illa snaps upward 10 back to its normal position shown in Fig. 1.

When the button is pressed downward, the portion Ib of the strip is bent into a transversely concave shape since the sides are supported by the ledges I6 and I1 in the direction of the pressure applied by the button.v More particularly, the sides are supported at opposite points the same distance from the bend as the point of application of pressure 'by the button. When suiicient pressure is applied the bendq II suddenly assumes this concave shape whereby the strip is straightened with a snap action, the portion Illa snapping downward to the position 2|] indicated by the dotted lines in Fig. 1. In this position, the longitudinal sides of the strip throughout its entire length come to rest on the ledges IIi and I'I as shown in Fig. 4.

While the button I8 must be arranged, for effective snap action, to engage the strip at a point near the bend II, I have found that much more effective snap action is obtained when the force is applied a short distance from the bend as shown in the drawing. For example, in a typical device having a' strip made of bronze spring material about ve-thousandths of an inch (.005) thick and three-fourths of an inch wide, pressure applied about one-fourth of an inch (ly) from the bend gave a vigorous snap action. Moreover, the movable end of the strip moved only a small amount before the snap action occurred. When pressure was applied directly on the bend II, however, the movable end moved considerably before the snapaction occurred, much less force was required, and the snap action was much less vigorous. Apparently when the force is applied a short distance from the bend, energy is stored in the material by depression of the portion Ib, this energy being released suddenly in effecting the snap action.

One advantage of this device is that very little movement of the button I8 is required after it engages the strip to cause the strip to snap. In a typical device, a movement of about 1A00 of `an inch was required. This precision, while inherent in the device, depends of course to a great 55 -to assure that the movable contact is not disengaged from the stationary contact by any slow preliminary movement of the end of the strip preceding its snap action, the stationary contact 23 is mounted in such a position that it holds the end of the strip depressed to such a point as to give this sudden snap action. Thus it the stationary contact were removed, the strip, as shown in Fig. 1, would assume the dotted line position 24. With the movable end depressed as indicated by the full line position, the movable contact disengages the stationary/contact with a sna'p action and without preliminary slow movement. This furthermore provides for a denite contact pressure between the contacts. Another terminal 25 at the other end of the casing extends into the casing under the end of the strip which is secured to the casing the strip being secured to the casing and to the terminal 25 by the screws I5.

As shown in Fig. 5, the strip 26 is inverted with respect to its support 21 as compared with Fig. 1, the movable end 26a extending downward. Pressure applied by suitable button 28 causes this end to snap upward.

It will be understood that various switchingarrangements as well as various mechanisms can be operated by the strip. Thus the movable end may carry a bridging contact or 'may operate a movable contact between spaced stationary contacts.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto, since many modifications may be made and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

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

1. A snap action device comprising a rectangular strip of thin spring material provided with at least two flat portions joined at an angle with each other by a transverse zone constituting a bend, a support to which one end of said strip is secured, said support being provided with a groove extending lengthwise of said strip dened by ledges engaged by the sides of one portion of said strip, theother portion of said strip extending at an angle with said support, and means for applying a force to said rst portion of said strip at a point spaced from said bend thereby to depress said rst portion transversely and cause said bend to assume a curved form whereby said strip straightens with a snap action.

2.. A snap action device comprising a substantially ilat sheetof spring material permanently bent along a substantially straight zone forming a bend into two substantially at portions, and means for applying a force to one of said portions at a point spaced from said bend thereby to deform said lportion in a direction parallel with said bend and cause said bend suddenly to assume a curved form and said sheet to straighten with a snap action.

3. A snap action device comprising a strip of spring material permanently bent longitudinally along a transverse zone forming a bend into two substantially at portions, means for supporting opposite sides of one of said portions, and means for 4applying a force to said portion at a. point spaced from said bend thereby to deform said 'portion transversely and cause said strip to straighten with a snap action.

.4. A snap action device comprising a flat rectangular strip of spring material permanently bent longitudinally along a straight transverse zone forming a bend into two straight ilat portions, supporting means for said'strip engaging points on opposite sides of one of said portions a predetermined distance from said bend and securing said points in at least one direction, and means for applying a force to said portion in said direction at a point between said points of support transversely central of said portion and spaced by said predetermined distance from said bend thereby to deform said portion transversely and cause said bend suddenly to assume a curved form and said strip to straighten with a snap action.

5. A snap-action device comprising a strip of spring material bent longitudinally along a transverse zone forming a bend into two substantially ilat portions at an angle with each other, a sup-v port to which one end of said strip is secured provided with ledges engaged by the sides of the adjacent portion of said strip, and means for applyinga force at a point spaced a predetermined distance from said bend, said force biasing said portion against said ledges thereby to deform said portion transversely and cause said bend suddenly to assume a curved form and said strip to straighten with a snap action.

' 'SAMUEL F. JARvrs.

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