US2789172A

US2789172A - Snap-acting switch mechanisms

Info

Publication number: US2789172A
Application number: US357518A
Authority: US
Inventors: Happe Reynold
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1953-05-26
Filing date: 1953-05-26
Publication date: 1957-04-16
Anticipated expiration: 1974-04-16

Description

April 16,. 1957 R. HAPPE 2,789,172

SNAP-ACTING SWITCH MECHANISMS 2 Sheets-Sheet 1 Filed May 26, 1953 April 16, 1957 R. HAPPE SNAP-ACTING SWITCH MECHANISMS 2 Sheets-Sheet 2 Filed May 26, 1955 m. w n m nolo? Hajnlve ATTORNEY United States Patent SNAP-ACTIN G SWITCH MECHANISMS Reynold Happe, Pittstown, N. J., assigner to The Singer Manufacturing Company, Elizabeth, N. J., n corporation of New Jersey Application May 26, 1953, Serial No. 357,518

Claims. (Cl. 20G- 67) This invention relates to an electric switch mechanism and more particularly to one which provides a positive snap action responsive to small actuating pressure.

An important object of this invention is `to provide a switch having minimum dimensions relative lto its current-carrying capacity.

Another object of this invention is to provide a switch which has substantial contact movement responsive to minimum actuator movement.

A further object of this invention is to provide a sensitive snap-action mechanism for a switch which effects, during normal operation, a substantial contact wipe.

A still further object of .this invention is to provide a pressure-sensitive switch which is characterized by having one of its dimensions relatively very small, which creates a generally thin wafer shape for the entire unit.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations, and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

lIn the drawings:

Fig. l is an open plan view of a snap acting electric switch embodying my invention and showing one extreme position of the parts.

Fig. 2 is an open plan view similar to Fig. l but showing the other extreme position of the parts.

Fig. 3 is a longitudinal section partly in elevation taken on line 3-3 of Fig. 1 and includes the cover.

Fig. 4 is a partially disassembled view of the primary components of the switch of Fig. l.

lFig. 5 is a detailed View showing a pivotal connection used in the switch of Fig. l.

Pig. 6 is a perspective view showing the general external appearance of the switch of Fig. l.

Referring now to Fig. 1, a narrow, flexible band 10 made of at spring stock, preferably of beryllium copper alloy, is secured -to a single support 11 which, in turn, is secured to an insulation base 12. The band 10 -is bent to form two spaced-

apart limbs

13 and 14 which extend `generally in -the same direction from the stationary support 11. The limb 14 is relatively short and straight, while the other limb 13 is longer, bowed and positioned so that its free end 15 extends beyond and overhangs the free end 16 of the shorter limb 14. A straight link 17 -is substantially stiffer than the resilient limbs 13 and l14 and, as seen best in Fig. 4, is formed at each end with reduced

shouldered portions

18 and 19, which are adapted to t within

cooperating apertures

20 and 21 in the

limbs

13 and 14 respectively. These elements are shown assembled in Fig. 5. In this manner, the link 17 is suspended between and pivotally connected to each of the free ends of the

limbs

13 and 14, and the length and configuration of the limbs is such that the link 17 is always under compression between said free ends;

vIn the preferred embodiment shown in Fig. l, the support 11 to which the band 10 is secured as by rivet 29, is bent to form a U-shaped element having one limb 30 extending through the wall of the base 12 to provide a soldering lug; and the other limb 31 is received in an internal recess 32.

The bowed limb 13 terminates in -a sharply-bent contact arm portion 22 to which may be secured a double contact button 23. This constitutes the movable contact which is coniined to operate between two

spacedapart conducting iingers

24 and 25 which are each secured 4to the insulation base 12 and extend Ythrough the wall thereof to form external soldering lugs. These tingers are provided with contact buttons 26 and 27 respectively, and constitute the stationary contacts which may be connected into external circuits, as desired.

lI1: will be seen in Fig. 4, which shows the

limbs

13 and 14 in their normal unstressed condition, that the span distance between the

free ends

15 and 16 lthereof is less than the seated length of the link 17, so that the link, when it is Iinserted to complete the loop, as in Fig. 5, must be under compression. The amount of compression in the link 17 depends upon its position relative to the

limbs

13 and 14, and there is a position of maximum compression indicated by the dotted lines in Pig. 1. This is an unstable condition and slight further counterclockwise angular movement of the link 17 reverses the force acting on the bowed limb causing it and Ithe movable contact 23 to move witha snap action to its yother engaging position, with the stationary contact 27 as shown in Fig. 2. The limb 14 is formed so that, normally, it biases the link 17 to one side of its unstable position, as shown by fthe full lines in Fig. l. This corresponds to stable closure of the

contacts

23 and 26. A headed pin 28 of insulation material is mounted for endwise movement in an -apertured portion 33 of a wal-l of the base 12 and imparts movement to the limb 14 to swing the link 17 to and through its intermediate unstable posi-tion shown dotted, whence it snaps to the second stable position shown in Fig. 2, in which case the contacts 23 and 27 are closed. Upon release of the pin 2S, the biasing force supplied by the limb 14 returns the switch to its normal position.

An insulated cover-plate 34, removably secured to th base 12 by screws 35-35, completes the assembly enclosing the operative switch parts and serves to retain the

elements

24, 25 and 30 in their proper predetermined positions in the wall slots to insure precise opera-tion of the switch. It will be noted that these elements are formed with notched portions which engage with cooperating lugs in the slot portions to prevent lateral displacement.

EIt will also be noted that neither end of the link 17 is tied to a stationary pivot and, indeed, the link is allowed considerable freedom of endwise movement due to the resiliency in that direction provided by the bowed portion of the limb 13. This structural relation results in substantial wiping action between the contacts during normal operation of the switch which provides a continual cleaning of the contact surfaces and the automatic maintenance of minimum contact resistance and maximum useful life.

As a matter of fact, the exceptional wiping action of this switch makes it ordinarily unnecessary to use special precious metal contact material such as would normally be used in the

contact buttons

23, 26 and 27, thus decreasing substantially the manufacturing cost of the switch without sacrifice of its good operating characteristics. It will also be noted that, except for Ithe face-to-face contacts themselves, the current path through the switch is entirely solid and continuous, and is not Vbroken up by any of the joints of ythe usual pivoted elements which would contribute their resistance to the path and thus unduly limit the current-carrying 'capacity of the switch. Y

It is also evident that the .basic mechanism of this switch .need be substantially no wider than the narrow ba-nd. `10 from which the

limbs

13 and 14 are made. This is `due to the overhanging, .in-line construction which eliminates the paralleled side-by-side spring elements which characterize many of the prior-art snap switches. As a result,'the general overall shape of the switch `takes on -the form of a .thin wafer as seen best in -F-ig. 6, and which .is a Very adaptable form and Vone which may readily be sandwiched vin-between existing equipment.

.Alfurther characteristic `feature of this construction permits the movable contact -23 to be moved in a direction precisely the opposite from that of the actuator pin 28 which imparts the movement.

Viewed in vits -broadest sense, the switch mechanism of thegpresent invention comprises a closed, articulated loop supported at but one point `and comprising a U-shaped resilient leaf springr having ylimbs of unequal length Withxa substantially stiff link pivotally secured Vbetween the :free ends Vof said limbs and held in com pressiontherebetween.

l.Having thus set `forth the nature of the invention, what I claim herein is:

1. In a snap-'acting switch, a single support, a spring supported thereby -intermediate'its ends and bent to form two spaced-apart limbs of equal width and unequal length extending generally in the same direction from the support, a link pivotally supportedin compression between the free ends of said limbs, the longer one of said limbs being bowed and formed at the end with a bent portion forming a movable electrical contact arm, two jspaced tixed contacts, the shorter one of said limbs being selectively movable-to impart la snap-action movement in said lmovable -contact arm between the positions thereof limited by said !fiXed contacts.

.2. In Y-afsnap-aoting switch, a single support, a single constant width `leaf spring supported vthereby'intermediate its yends land bent to form'two spaced Vapart limbs extending generally in the same ydirection from the support, a .link vpivotally connected to and held .in compression between 'the free ends of said limbs, an actuator'V in operative connection with one of Vsaid limbs, said other limb being formed with -a bent terminal portion form-l ing a movable electrical contact, and two, spaced, stationary Ycontacts defining `stable Ypositionswbetween which said movable contact operates responsive to-movement of said actuator.

3. In an electric switch, an insulated base, a conducting support secured to saidbase, a single piece of spring conducting material -of constant width secured to `said support and formed into two limbs which extend in the same general direction from said support and terminate in free ends, a relatively stiff link element held suspended between said freefends in a pivotal connection therewith, a contact -arm formed asV an extension of one of said limbs, spaced contacts secured `to said base and engageable by said contact arm, and manual means Yfor moving said `other limb to `impart snap-action to said -rst limb and to said Contact arm. Y

4. In a snapy switch, an insulated chaise, a support secured to said base, a single, flat, resilient leaf spring yof constant width 'bent `to 4form a generally U-shaped member secured to said support adjacent the bend and positioned with its longitudinal axis parallel to said base, one limb being generally straight Vand short, the other limb Ybeing bowed, 4longer and extending more remotely from 'said support Vthan .the free end of said first limb, a substantially stiliV 'link .pivotally secured Vto and held Yin compression between Vthe free ends of said Ylimbs tofform a closed lloop with a single support, said Ybowed limb being formed with a terminal bend'providin'g 4a Contact arm, and two spaced conducting 'fingers secured .to said base lbetween which lingers said contact arm Vmoves to make and break contact therewith in response to lienure o'f said iir'stliinb.V

5. In a snap-switch mechanism, a closed Yloop supported lat one Apoint and comprising a generally U-shaped resilient leaf spring of constant width 'having one limb longer than the other, the longer limb being bowed and bent at its free end to form a contact arm, a substantially stitl:` link pivotally secured between the free end of -said shorter 'limb `and the bend of said longer limb .and lheld in Ycompression therebetween by the normal spring .of the parts, two, spaced conducting elements forming stationary contacts between which said contact .arm moves, and an actua-tor -for iiexing said shorter limb to impart snap-action to said longer limb and to said contact arm.

References Cited in the file of this patent UNIT-ED STATES PATENTS n Y `Holmes va Mar. 9, 1943V Hobbs Mar. t23,. lf954