US2387089A - Snap action switch - Google Patents

Description

Oct, 16, 1945.

w. R. `PETEEzsoN ETAL 2,387,089

y SNAP ACTION SWITCH Filed Nov. 5, 1942 Patented Oct. 16, 1945 UNITED STATES PATENT OFFICE s SNAP ACTION 'SWITCH William R. Peterson,` Chicago, and Allen G. Ford, Oak Park, lll., assigner: .to Vapor Car Heating Company, Inc., Chicago, Iii., a corporation of New York Application November 5, 1942, Serial No.k464,580 8 Claims. (Cl. 20o-140) strips and at the same time maintain the desired sensitivityin operation.

Another object is to provide a novel arrangement and construction whereby the switch may be normally operated in one direction by a slowly moving actuating means and will return toits inixtal positionv by they resilient reaction of the pa s.

Another object of the invention is to provide a simpliiled structure which will be adapted to be actuated by a temperature responsive element and vto provide in this connection means for ad- Justment whereby the movable members of the switch'may be moved from one position to anl other at any desired temperature, the movable members being held by spring pressure in both their open and closed positions.

Other objects and advantages of the invention will be more apparent from the following detailed description ofv one preferred embodiment of the invention 'shown in the accompanying drawing.

In the drawing:

Fig. 1 is a view in elevation, drawn in full size scale, of one preferred form of switch, Aconstructed'in `accordance with this invention.

Pig. 2 is`an enlarged view, partly in section, along line 2-2 of Fig. 1 and illustrating the positions ofthe movable parts of the switch device when it is in its normally open position.

Fig. 3 is a fragmentary view of the lower portion of Fig. 2 illustrating the positions of the movable parts of the switch device when it is in its open position.

Fig. 4 is a bottom plan view of the structure `shown in Fig. 2, the said view being taken on line I-l of Fig. il.

Iiig. 5 is a view in perspective of one of the elements of the switch structure.

Fig. 6 is a view in perspective of the rocker member which ls adapted to be inserted between the inner and outer spring leaves of the member shown in Fig. 5; and

Fig. 'I is a further enlargement of a portion of the movable contact member shown in Fig. 2.

The invention as herein shown comprises a cylindrical cup shaped casing i0 adapted to be secured or mounted in any desired location. Such mounting-df the casing is facilitated" by the provision of an attaching bracket Il secured to the bottom of the casing. A switch panel i2 of suitable insulating material is formed to fit the upper 4end of the casing. Preferably the panel I2 rests upon oilsetshoulders i3 formed in the inner surface of the casing near the upper edge thereof, the panel being of such thickness that its upper surface lies flush with the upper edge of the said casing. A top plate i4 fits over the said panel with its outer edges resting upon the upper edges of the casing I0. The casing I 0, attaching bracket Il, switch panel I2 and top plate Il are clamped together in assembled relation by means of suitable screw bolts IS-IS which extend through the several members above mentioned. The reference numeral i6 designates the nuts threaded on the upper ends of the bolts i5.

The under-face of panel I2 is formed with downwardly extending lugs 1 -I8.- These lugs are preferably formed with further extensions |920 to which an arcuate shaped bridge member 2l is secured. A fixed contact 22 is centrally mounted on the bridge member. A terminal clip 23 for a line wire 2l is clamped to one end of said bridge member by means of an attaching screw 25.

Cooperating with the said fixed contact 22 is a movable contact 26 which is secured to one end of a flexible spring member, designated generally by the reference numeral 2l. The other end of said spring member is clamped by screws 28 to a lug '29 depending from the said switch panel. The switch member 2l is preferably,

though not necessarily, formed from a single strip of metal by punching therein a substantially U-shaped slot 20 to form, in effect, an innerl spring leaf 3| and an outer spring leaf 22. 'Ihe said outer leaf or contact carrying arm includes side members 33-22 which are relatively narrow so that they will be more flexible than the inner leaf or actuating -arm 3i. The side members 33 22 are bowed outwardly from the face of the strip, preferably downwardly, as shown at 34--24 so as to move the free end portions of vent undue buckling during the operation of the switch. The 'inner leaf ti is also preferably 4bent leaf, as indicated in Figs. 2, and 'I so that the end of the inner spring leaf 3| and the inner edge 31 of the free end of' the outer spring leaf 82. The rocker member may be formed from the metal removed from the wide portion of the U- shaped slot. The opposite ends of the rocker member are'bent to form angular flanges 38-33 which engage over the adjacent edges of the inner and outer spring leaves 3|-32. These edges of the spring leaves are notched, as shown at 39-40, to hold the rocker member in proper position.

The combined length of the inner spring leaf 3i and the rocker member 3b are greater than the length of the side members 33 of the outer spring. 32. That is to say, they are greater than the distance from the xed end portion of the outer leaf to the point of its connection with the rocker member. Consequently, when the rocker member is inserted in its operative position, the bowed portions Sil-3d of the side members are expanded and therefore tensioned. The said bowed portions are always under some tension so that in one position of the movable switch the free' end of the spring leaf 32 is held resiliently against the under surface of lugs il-iil and when in closed position the contacts 22-2t are held -together by suicient resilient action to prevent rebound of the movable contact when it strikes the fixed contact and to-prevent displacement or separation of the contacts by normal vibration. A stop member 5| is secured to the lug 29 of the switch panel so as to engage the under surface of the inner spring leaf 3| and thereby limit the downward movement of this leaf. A terminal clip 42 for` line Wire 52a may be clamped in position by one of the screws It will be seen tha-t by applying force upwardly against the lower surface of the actuating arm, when the switch is in the .position indicated in Figs. 2 and '7, the force is transmitted through the rocker member 36 with a toggle like action while the free end of the spring 32l or contact carrying arm remains bearing against the bottom surface of the lugs I'|-|8. This pressure, therefore, spreads or expands the bowed portions 34-34 so as to elongate the spring-leaf 32 and provide the normal tension for resiliently holding the movable contact arm against the said stoplugs ||-I8. The application of increased upward pressure to the inner leaf 3| imparts upward movement thereto. When this upward movement. passes through a critical point or dead center, the tension in the bowed portions 34-34' will cause the contact carrying arm 32 to snap downwardly to the closing position .indicated in Fig, 3. 'Ihe said spring action of the portions `34---34 also impart a retracting or rearward movement to the said arm 32 `and therefore cause the movable contact 26 to engage the fixed contact 22 with a wiping action. Preferably the tension in the reinforced inner leaf or actuating arm 3| is suicient to return it to the normal position of Fig. 2 as the operating upward pressure thereon is relieved. During the relief of gradually return toward its lower position. When it again passes the critical or dead center y 2,387,089 downwardly atan angle to the plane of the outer position on its downward movement, the leaf spring 32'will snap upwardly to open the contacts of the switch.

It will be observed that the rocker member f engages the outer spring leaf in close relation to the contact 26 and stands at such angle as to transmit the desired contact pressure with a minimum linear tension on the operating parts.

It will also be observed that with the arrangement of the rocker member 36 herein shown, the

'Dlied to the inner leaf 3| bymeans of a tem.

perature responsive element d3. This member, in the present embodiment, is supported on a yoke .member M, the ends of which are secured to the top plate ll in any suitable manner. A rod d5 is secured to the lower portion of the bellows and extends through thetop plate it, the switch panel i2, and through an opening 4B in the inner spring'leaf 3|. `A coil spring Si surrounding the rod t5 is .interposed between the bottom portion of the bellows and the said top plate It of the casing. A knurled adjusting nut d8 of insulating material is threaded on the lower end of the rod 45 to bear against the lower surface of the inner spring leaf 3| of the switch. A relatively slight' contraction 0f the thermostatic bellows G3' from the position indicated in Fig. 2 will actuate the switch to close contacts 22-28. The return of the thermostatic bellows to the position indicated in Fig. 2 will permit the refiex movement of leaf 3i to operate the leaf 32 in a direction to open the contacts 22-28.

It will be observed that when the inner leafl 3| has been forced upwardly past the critical dead center position, its further upward movement is limited by reason of its contact with a boss 49 formed on the switch panel. Consequently, any further upward pressure exerted by the thermostatie bellows will not unduly flex the inner spring leaf 3|. However, during the operi-y ing, movement of the switch the thermostatic bellows 43 may expand beyond the position'of Fig. 2, in which event, the adjusting nut 48 will merely move downwardly from 4the spring leaf 3 l.

While the invention is illustrated in Vone Lspecific embodiment it will be understood that the invention is not to be limited to the specific construction shown and described except insofar as specific -limitations appear in the appended claims.

We claim:

l. A snap action switch comprising a fixed contact, a movable contact for wiping engagement with said xed contact and including a contact supporting arm one end of which issupported in fixed position and the free end of which -1s transversely nexible and resiliently extensible f therefor having one end supported in fixed posi- .said operating pressure, the said inner leaf will 1 tion andthe other end movable^\from .one side to the other of the plane of said contact support- Ille arm, and a relatively sti rocker member hmgedly engaging the free .end portions of said contact supporting arm and said actuating arm: the combined lengths of the movable portion of said actuating arm and said rocker member belng greater than the distance between the fixed end portion of said contact supporting'arm and the point of its connection with said rocker member.

2. A snap action switch comprising a base f panel, a fixed contact, a movablecontact for wiping engagement with said fixed contact and including a leaf member one end of which is fixed to said panel and the free end of which is transversely flexible and resiliently extensible in the direction of its length, an actuating arm having an end secured to said panel with its free end adapted to move from one side to the other of the plane of said leaf, and a relatively rigid rocker member hingedly engaging the free end portions of said leaf and said actuating arm; the combined lengths of said arm and said rocker member being greater than the distance between the fixed end of said leaf and the point of its connection with said rocker member.

3. A snap action switch comprising a base panel, a fixed contact, a movable -contact for wiping engagement with said fixed contact and including a leaf member, one end of which is fixed to the panel and the free end of which is provided with portions bowed outwardly from a face of the leaf to provide lengthwise resilience adapted to effect said snap action and said wiping engagement, a resilient actuating arm havinggreater resilient force than said leaf and fixed at one end to said panel, an actuating arm having one end secured to said panel with its free end adapted to move from one side to the other of the plane of said leaf, and a relatively rigid rocker member hingedly engaging the free end portions of said leaf and said actuating arm; the combined lengths of said arm and said rocker member being greater than the distance between the flxed end of said leaf and the point of its connection with said rocker member whereby said leaf is tensioned in the direction of its length by movement of the actuating arm toward the face plane of the leaf.

4. A snap action switch comprising a base panel, a fixed contact, a movable contact for wiping engagement with said fixed contact andv l including a leaf member, one end of which is vide it with lengthwise resilience to eifect said x snap action and said wiping engagement, a resilient actuating arm having greater resilient force thansaid leaf secured to said panel adjacent the fixed end of said leaf with its free end adapted to move from one side to the other of the plane of said leaf, and a relatively rigid rocker member having an interlocked rocking engagement with the free end portions of said leaf and .said actuating arm; the combined length of said arm and said rocker member being greater than the distance between the fixed end of said leaf and the point of its connection with said rocker member.

5. A snap action switch comprising a fixed contact, a movable contact for wiping engagement with the fixed contact and including a metal strip having a 'U-shaped aperture therein defining outer and inner spring leaf portions, .the latter of which is bent to extend at an angle to the plane of the outer leaf portion, formed with pressed stiflening corrugations and adapted to be iiexed from one side to the other of the plane of said outer leaf and the side portions of the outer leaf defined by said aperture being formed with bowed portions to provide the outer leaf with lengthwise resilience adapted to effect said snap action and said wiping engagement, and a relatively stiff rocker member hingedly engaging the free ends of said inner and outer leaves; the length of said rocker member being such that the said inner and outer'leaf members are held normally under tension.

6. A snap action switch comprising a base panel, a fixed contact supported in spaced relation to said panel, a movable contact carried on a. flexible member and adapted to move into and out of engagement with the fixed contact with a wiping movement, said flexible member comprising a spring metal strip having a U- shaped aperture defining inner and outer spring leaves united at one end, the inner leaf being bent at an angle to the plane of the outer leaf and formed with reinforcing corrugations and adapted to be flexed from one side to the other of the plane of the outer leaf but is normally biased to a position at one side of the plane of the outer leaf, means for nxedly attaching the united ends of said leaves to said panel, stop means for limiting the movement of the inner leaf and for supporting itin its normal position,

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