EP0000635B1 - Schnappfeder und Verfahren zu deren Herstellung - Google Patents

Schnappfeder und Verfahren zu deren Herstellung Download PDF

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Publication number
EP0000635B1
EP0000635B1 EP19780300146 EP78300146A EP0000635B1 EP 0000635 B1 EP0000635 B1 EP 0000635B1 EP 19780300146 EP19780300146 EP 19780300146 EP 78300146 A EP78300146 A EP 78300146A EP 0000635 B1 EP0000635 B1 EP 0000635B1
Authority
EP
European Patent Office
Prior art keywords
arms
contact element
blade
legs
base portion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19780300146
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English (en)
French (fr)
Other versions
EP0000635A1 (de
Inventor
Guglielmo Rossi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robertshaw US Holding Corp
Original Assignee
Ranco Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ranco Inc filed Critical Ranco Inc
Publication of EP0000635A1 publication Critical patent/EP0000635A1/de
Application granted granted Critical
Publication of EP0000635B1 publication Critical patent/EP0000635B1/de
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H5/00—Snap-action arrangements, i.e. in which during a single opening operation or a single closing operation energy is first stored and then released to produce or assist the contact movement
    • H01H5/04—Energy stored by deformation of elastic members
    • H01H5/18—Energy stored by deformation of elastic members by flexing of blade springs
    • H01H5/20—Energy stored by deformation of elastic members by flexing of blade springs single blade moved across dead-centre position

Definitions

  • This invention relates to snap action switch blades.
  • a known snap-acting switch blade of the type to which the present invention relates is described in French Patent Specification FR A 2291598.
  • This type of blade is made of resilient sheet metal and comprises a base portion, an inwardly projecting tongue, an outwardly projecting tongue, two resilient legs projecting from opposite sides of the base portion and terminating beyond the inwardly projecting tongue, and a contact element interconnecting the two legs in a stressed condition in which the legs are drawn together, causing a dish deformation of the base portion, and prestressing the blade for snap movement of the contact element when an operating force is applied to one of the tongues while the end of the other tongue is anchored.
  • the outwardly projecting tongue which preferably terminates in a flat portion of enlarged width, is anchored to a fixed support.
  • the blade as a whole acts as a cantilever resisting elastically the operating force applied to the inwardly projecting tongue.
  • the elasticity of this mounting cantilever can be predetermined by appropriate choice of the length and width of the outwardly projecting tongue to predispose the blade for monostable or bistable snap movement according to the practical application for which the switch is intended.
  • An object of the present invention is to improve the damping qualities of the snap action switch blade of the aforesaid type by resisting elastically any tendency for 'contact bounce' to occur when the contact element engages a fixed contact upon snap-closure of a switch employing the switch blade.
  • the present invention provides a snap action switch blade of the aforesaid type which is characterised in that the two legs terminate in respective resilient arms which project laterally towards each other, the contact element being affixed to the laterally inner ends of the said arms, and in that the centre of the contact element, which in use of the blade is its area of contact, is spaced from the longitudinal centre line of the two resilient arms so that contact pressure exerted at the centre of the contact element causes torsional stress in the two arms.
  • the resilience of the two laterally inwardly projecting arms to which the contact element is affixed affords a degree of elasticity in the mounting of the contact element, which serves to resist and dampen any tendency for 'contact bounce' when the contact element closes upon a fixed contact in use of the switch blade.
  • the torsional stress which exists in the two laterally inwardly projecting arms carrying the contact element when the latter is held by the switch blade against a fixed switch contact tends to effect, upon contact separation, a wiping action between the two contacts breaking any welds which may tend to form in use of the switch blade.
  • This wiping action and the effective damping of any tendency to contact bounce may be enhanced by so dimensioning the switch blade that the two laterally inwardly projecting arms which carry the contact element are narrower in width than the two legs of the switch blade upon which the arms are formed.
  • a further practical advantage of the blade according to the invention is that the contact element interconnects the resilient arms at the outer ends of the two legs of the blade, serving both as an electrical contact and drawing the two arms together to stress the blade and predispose it for snap action. Since it is not necessary to affix a separate contact element to the blade, after deformation thereof and interconnection of the arms, the blade construction is simplified considerably and is therefore potentially economical in mass production.
  • the contact element of the switch blade should be of a material which can easily be welded to the arms of the switch blade, while presenting a suitable contact surface.
  • the contact element of the switch blade comprises a base portion which is affixed to the two laterally inwardly projecting arms and an electrically conductive contact layer which is deposited on, or bonded to, the base portion.
  • the contact element may conveniently be of square or rectangular shape, severed from a continuous strip, each contact element being formed with two raised parallel ribs on its base portion along which the contact element is welded to the arms of the blade.
  • the invention also comprehends a method of making the snap action switch blade herein defined, comprising stamping or otherwise forming a flat blank or resilient sheet metal with a base portion, inwardly and outwardly projecting tongues, two legs projecting from opposite sides of the base portion and extending generally parallel to the inwardly projecting tongue, terminating beyond the latter in respective arms which project laterally inwardly towards each other, the inner ends of the said arms being spaced from each other by a gap, anchoring the base portion of the blade blank while deforming the outer ends of the two legs laterally towards each other to reduce the gap between the arms and stress the blade, and affixing to the two arms a contact element which interconnects the arms and maintains the blade in its stressed condition.
  • the contact element would in practice preferably be affixed to the two arms by a welding operation, the steps of deforming the blade blank and welding the contact element in position being conveniently performed in an automatic sequence, using a suitable jig.
  • the two legs of the latter may be formed at their ends with laterally outwardly projecting lugs to which laterally inwardly directed forces are applied to deform the outer ends of the two legs laterally inwardly towards each other, prior to the affixing of the contact element to the laterally inwardly projecting arms carried by the legs.
  • the snap action switch blade shown in Figure 1 comprises a sheet of resilient sheet metal, for example beryllium copper having a thickness of 0.25 millimetre.
  • the blade is formed with a base portion 1, an inwardly projecting tongue 2, an outwardly projecting tongue 3, and two resilient legs 4, 5 projecting from opposite sides of the base portion 1, the legs 4, 5 being substantially parallel to each other and terminating beyond the end of the inwardly projecting tongue 3 in respective laterally inwardly projecting arms 6, 7.
  • the base portion 1, the tongues 2, 3 the legs 4, 5 and the arms 6, 7 are all formed integrally with each other from a single resilient metal sheet.
  • the two laterally inwardly projecting arms 6, 7 are interconnected by a contact element 8 which is welded to the two arms 6, 7, interconnecting them in a stressed condition in which the arms are drawn together, causing stressing of the two legs 4, 5 and resulting in a slight dished deformation of the base portion, as illustrated in Figure 1.
  • the outwardly projecting tongue 2 terminates in a flat integral mounting tab 9 of greater width than the remainder of the tongue 2, the tab 9 having two holes 10 by means of which it can be anchored firmly to a fixed support, so that the entire blade projects cantilever-fashion from this support.
  • the switch blade When mounted in this way, and prestressed for snap action as described above, the switch blade is predisposed to effect snap movement of the contact element 8 relative to the fixed blade support and, therefore, relative to a fixed switch contact (not shown) when an operating force is applied to the end of the inwardly projecting tongue 3.
  • the tongue 3 may be formed with a raised protuberance 11 near its free end, forming a well defined surface for engagement by a switch operating member (not shown) which applies an operating force indicated by the arrow P in Figure 1.
  • the switch blade can be designed so as to be monostable or bistable in operation.
  • the switch blade reverts to its original stressed condition when the operating force P is removed or falls below a further threshold value.
  • the application of the operating force P causes snap movement of the contact element 8 into engagement with a fixed contact (not shown) of a switch, and the subsequent release of the force P results in snap opening of the switch contacts.
  • the blade can be predisposed for bistable operation, whereby, once having undergone snap deformation from its original stressed condition ( Figure 1) it assumes a stable condition with the opposite dished deformation to that shown in Figure 1.
  • the flexural elasticity of the two legs 4, 5 and the arms 6, 7 serves to enhance the snap movement of the contact element 8 carried thereby by virtue of the inertia of the relatively massive contact element 8: before the instant of contact separation the legs 4, 5 and the arms 6, 7 will bend elastically, releasing their stored energy when the contact element 8 "unsticks" to cause rapid movement of the contact element 8 relative to the fixed contact.
  • Figure 2 shows a flat sheet metal blank stamped in a single piece from resilient conductive material such as, for example beryllium copper sheet.
  • the legs 4, 5 are parallel to each other and to the central inwardly projecting tongue 3, and the outwardly projecting tongue 2 is coplanar with the inner tongue 3.
  • the two laterally inwardly projecting arms 6, 7 at the ends of the legs 4, 5 are also coplanar, and terminate in respective edges 13, 14 which converge towards the base portion 1 and which are separated by a suitable gap to allow the subsequent prestressing of the blade.
  • the edges 13, 14 converge at an angle of approximately 6°.
  • the two laterally inwardly projecting arms 6, 7 terminate in end portions 15, 16 of enlarged width, the two arms 6, 7 themselves in this embodiment being narrower in width than the respective legs 4, 5 which carry them.
  • Two shallow outwardly projecting rounded lugs 17, 18 are formed at the ends of the respective legs 4, 5 adjoining the arms 6, 7.
  • the blade blank After stamping the blade blank shown in Figure 2 and deforming the central inwardly projecting tongue 3 to form the raised protuberance 11, the blade blank is placed in a jig with the flat tab 9 anchored in a fixed support or clamp forming part of a jig which includes pneumatically operated pistons which act upon the external lugs 17, 18 of the blank to deform the legs 4, 5 inwardly towards each other, closing or substantially closing the gap between the edges 13, 14.
  • the pistons may be arranged to bring the edges 13, 14 into edge to edge abutment with each other, or alternatively may incorporate stops to reduce the size of the gap between the edges 13, 14 by a predetermined amount only.
  • the contact element 8 is of bimetal construction, having a base layer of suitable material capable of being welded to the blade blank.
  • the contact element is formed with two raised parallel ridges 19, 20 ( Figure 3).
  • the ridges 19, 20 are pressed into contact with the respective end portions 15, 16 of the blade blank upon assembly of the blade, and after inward deformation of the arms 6 and 7 towards each other the contact element 8 is welded to the end portions along the ridges 19, 20 by the passage of a suitable welding current between the contact element 8 and the blade itself, thereby securing the contact element 8 to the arms 6 and 7 and interconnecting the latter in a stressed condition of the blade.
  • Superimposed upon the base layer of the contact element 8 is a contact layer of silver cadmium oxide, or some other suitable conductive material.
  • the contact element 8 may conveniently be cut from a continuous strip of the aforesaid bimetal, extruded with the raised ridges 19, 20 extending longitudinally, the strip being cut transversely of the ridges to form the contact element 8, without any subsequent finishing operation being necessary.
  • Such torsional deformation serves to absorb the kinetic energy of the contact element 8 upon closure of the switch contacts, acting in a shock-absorbing capacity and minimising the tendency for contact bounce to occur.
  • the torsional deformation and therefore the shock absorbing effect will be proportional to the kinetic energy to be absorbed.
  • the torsional deformation of the arms 6, 7 also has the effect of imparting a slight twisting action to the contact element 8 about a transverse axis parallel to the axis X-X of the arms 6, 7, resulting in a rocking or wiping movement of the contact element 8 upon the fixed contact prior to separation of the contacts and serving to break any welds between the contacts.
  • the contact element 8 in the switch blade of Figures 4 and 5 is on the opposite face of the blade from the contact element 8 in the embodiment of Figure 1: either position may be adopted for the contact element according to the switch requirement.

Landscapes

  • Manufacture Of Switches (AREA)

Claims (8)

1. Eine auf Schnappbewegung beruhende Schalterplatte aus Federblech, bestehend aus einem Fuss (1), einer nach innen vorstehenden Zunge (3), einer nach aussen vorstehenden Zunge (2), zwei federnden, von gegenüberliegenden Seiten des Fusses hervorstehenden und über der innen vorstehenden Zunge (3) hinaus endenden Seitengliedern (4, 5), und einem die Seitenglieder (4, 5) unter Spannung zusammenhaltenden Anschlussbestandteil (8), wobei die Seitenglieder (4, 5) zueinander hingezogen werden, derart, dass der Fuss leicht gebogen und die Platte zur Schnappbewegung des Anschlussbestandteils (8) beim Belasten einer der Zungen vorgespannt wird, während die andere Zunge geankert ist, dadurch gekennzeichnet, dass, die beiden Seitenglieder (4, 5) in je einen gefederten Endbestandteil (6, 7) auslaufen, die seitlich auf den anderen Endbestandteil zu verlaufen, wobei der Anschlussbestandteil (8) an der seitlich inneren Enden der benannten Endbestandteile (6, 7) befestigt ist und dadurch, dass der Mittelpunkt des Anschlussbestandteils (8), der bei Benutzung der Platte die Anschlussfläche bildet, von der Längsmittellinie der beiden gefederten Endbestandteile (6, 7) abgelegen ist, so dass der auf den Mittelpunkt des Anschlussbestandteils (8) ausgeübte Schliessdruck zu einer Drehbeanspruchung in den beiden Endbestandteilen (6, 7) führt.
2. Eine Schalterplatte gemäss Anspruch 1, wobei die beiden seitlich nach innen vorstehenden Endbestandteile (6, 7) an ihrem Ende, wo der Anschlussbestandteil (8) befestigt ist, erweitert dimensioniert sind.
3. Eine Schalterplatte gemäss Anspruch 2, wobei die beiden seitlich nach innen vorstehenden Endbestandteile (6, 7), breitenweise schmäler sind als die beiden Seitenglieder (4, 5) der Schalterplatte, die in die benannten Endbestandteile (6, 7) auslaufen.
4. Eine Schalterplatte gemäss irgendeinem der vorangehenden Ansprüche, wobei der Anschlussbestandteil aus einem an den beiden seitlich nach innen vorstehenden Endbestandteilen (6, 7) befestigten Fuss und einer die Elektrizität leitenden, auf den Fuss aufgetragenen oder aufgehafteten Kontaktschicht besteht.
5. Ein Verfahren zur Herstellung der in Anspruch 1 bezeichneten, auf Schnappbewegung beruhenden Schalterplatte, bestehend aus dem Stanzen oder der anderweitigen Fertigung eines flachen Federblechrohlings mit einem Fuss (1), nach innen und aussen vorstehenden Zungen (3, 2) zwei sich gegenüberliegenden Seiten des Fusses (1) und in Grossen Ganzen parallel zu der nach innen vorstehenden Zunge (3) verlaufenden Seitengliedern (4, 5), welche über die Zunge hinaus in je einen sich seitlich nach innen gegeneinander vorstehenden Endbestandteil (6, 7) verlaufen, wobei die inneren Enden der besagten Endbestandteile (6, 7) voneinander durch einen Abstand getrennt sind, so dass die äusseren Enden der beiden Seitenglieder (4, 5) seitlich gegeneinander verzogen werden, um den Abstand zwischen den Endbestandteilen (6, 7) zu verringern und die Platte unter Spannung zu setzen, und an den anliegenden Enden der beiden Endbestandteile (6, 7) ein Anschlussbestandteil (8) befestigt wird, der die Endbestandteile (6, 7) miteinander verbindet und die Platte unter Spannung hält.
6. Ein Verfahren gemäss Anspruch 6, worin der Anschlussbestandteil (8) an den beiden Endbestandteilen (6, 7) durch Schweissen befestigt wird.
7. Ein Verfahren gemäss Anspruch 7, worin der Anschlussbestandteil (8) auf einem Fusse zwei erhabene Grate (19, 20) besitzt, die während der Verschweissens mit den beiden Endbestandteilen (6, 7) in Berührung gebracht werden, so dass das Schweissen länge der beiden Grate stattfindet.
8. Ein Verfahren gemäss irgendeinem der Ansprüche 5 bis 7, worin die beiden Seitenglieder (4, 5) des Plattenrohlings mit seitlich nach aussen vorstehenden Ansätzen (17, 18) versehen sind, die seitlich nach innen gerichteten Kräften unterworfen werden, um die äusseren Enden der beiden Seitenglieder seitlich gegeneinander zu verziehen.
EP19780300146 1977-07-15 1978-07-12 Schnappfeder und Verfahren zu deren Herstellung Expired EP0000635B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB2988977 1977-07-15
GB2988977 1977-07-15

Publications (2)

Publication Number Publication Date
EP0000635A1 EP0000635A1 (de) 1979-02-07
EP0000635B1 true EP0000635B1 (de) 1981-07-29

Family

ID=10298829

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EP19780300146 Expired EP0000635B1 (de) 1977-07-15 1978-07-12 Schnappfeder und Verfahren zu deren Herstellung

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EP (1) EP0000635B1 (de)
DE (1) DE2860881D1 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4278855A (en) * 1979-03-13 1981-07-14 Ranco Incorporated Snap action switch
US4796355A (en) * 1987-09-15 1989-01-10 B/K Patent Development, Inc. Snap action devices and methods and apparatus for making same
US5771169A (en) * 1996-08-29 1998-06-23 Case Corporation Site-specific harvest statistics analyzer
CN103187213B (zh) * 2011-12-29 2015-03-25 上海良信电器股份有限公司 热过载继电器的动作机构

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2805297A (en) * 1954-04-05 1957-09-03 Guardian Electric Mfg Co Snap switch mechanism
BE543796A (de) * 1955-06-07 1900-01-01
CH496311A (de) * 1970-03-25 1970-09-15 Adolf Feller Ag Fabrik Elek Sc Elektrischer Steuerschalter
SE411693B (sv) * 1974-11-16 1980-01-28 Ranco Inc Elektriskt kontaktelement med sneppverkan

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Publication number Publication date
DE2860881D1 (en) 1981-10-29
EP0000635A1 (de) 1979-02-07

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