EP0789373A1 - Electrischer Schalter - Google Patents

Electrischer Schalter Download PDF

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Publication number
EP0789373A1
EP0789373A1 EP97300686A EP97300686A EP0789373A1 EP 0789373 A1 EP0789373 A1 EP 0789373A1 EP 97300686 A EP97300686 A EP 97300686A EP 97300686 A EP97300686 A EP 97300686A EP 0789373 A1 EP0789373 A1 EP 0789373A1
Authority
EP
European Patent Office
Prior art keywords
plunger
housing
switch
leg
unstressed
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.)
Granted
Application number
EP97300686A
Other languages
English (en)
French (fr)
Other versions
EP0789373B1 (de
Inventor
Raymond Holmes
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.)
Johnson Electric International UK Ltd
Original Assignee
Saia Burgess Electronics Ltd
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 Saia Burgess Electronics Ltd filed Critical Saia Burgess Electronics Ltd
Publication of EP0789373A1 publication Critical patent/EP0789373A1/de
Application granted granted Critical
Publication of EP0789373B1 publication Critical patent/EP0789373B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H13/00—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch
    • H01H13/02—Details
    • H01H13/26—Snap-action arrangements depending upon deformation of elastic members
    • H01H13/36—Snap-action arrangements depending upon deformation of elastic members using flexing of blade springs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H11/00—Apparatus or processes specially adapted for the manufacture of electric switches
    • H01H2011/0081—Apparatus or processes specially adapted for the manufacture of electric switches using double shot moulding, e.g. for forming elastomeric sealing elements on form stable casing

Definitions

  • This invention relates to electric switches, and more particularly to snap-action electric switches.
  • the snap-action mechanism commonly comprises a thin leaf spring having three parallel legs.
  • the centre leg is longitudinally stressed, the free rear end thereof being urged into pivotal engagement with a fixed anchor member.
  • the rear ends of the two outer legs are fixed against upward and downward movement, while the fronts of the three legs are integral with one another and carry upper and lower contact members.
  • said plunger On depression of the plunger, said plunger engages the outer legs at points intermediate the fixed anchor member and the rear of the spring, continued depression of the plunger moving the outer legs downwardly below the line of action between the free end of the centre leg and the contact members whereby snap-action of the contact members from an upper position to a lower position occurs to alter the conditions of associated electric circuits.
  • the outer two legs of the leaf spring are longitudinally stressed with the free rear ends thereof being urged into pivotal engagement with a fixed anchor member.
  • the rear end of the centre leg is fixed against upward and downward movement, and again the front ends of the three legs are integral with one another and carry upper and lower contact members.
  • Actuation of the mechanism is achieved substantially as detailed above, except that the plunger engages the centre leg which is displaced downwardly relative to the two outer legs until snap-action occurs.
  • the plunger is conventionally guided by co-operation with the housing for axial sliding movement therein, for example by a co-operating tongue and groove arrangement, and actuation of the snap-action mechanism occurs when the plunger reaches a precise and predetermined axially displaced position within the housing.
  • the invention is particularly concerned with the problem of overtravel in very small, so-called ultraminiature switches where space is at a premium.
  • an electric switch in particular an ultraminiature electric switch, including a snap-action mechanism of the aforementioned leaf spring type and capable of accommodating longer overtravel than heretofore in a relatively simple and economical manner without the necessity for substantial additional components to be incorporated in the switch.
  • a snap-action electric switch including a housing, an operating plunger linearly movable relative to said housing, and a snap-action mechanism movable by said plunger between a rest position and a displaced position, the mechanism comprising a thin leaf spring having three substantially parallel legs the integral one ends of which constitute a contact member, at least one of said legs being longitudinally stressed such that, on movement of the or each unstressed leg beyond an overcentre position by the plunger, the contact member snaps from its rest position to a displaced position, characterised in that the other end of the or each unstressed leg is mounted to be movable with the operating plunger such that said overcentre position of the or each unstressed leg is achieved by bodily movement of the other end of the or each unstressed leg from a rest position to a displaced position, the plunger co-operating with guide means within the housing to ensure linear movement of the plunger and the other end of the or each unstressed leg.
  • the switch further includes resilient means, for example a compression spring, reacting between the operating plunger and the housing to urge the operating plunger towards its rest position.
  • resilient means for example a compression spring
  • the mechanisms associated with depression of the operating plunger of snap-action electric switches commonly comprise linear or rotary cams, levers and the like which apply substantial side loads to the plunger.
  • the guide means within the housing must therefore be such as to be capable of withstanding these substantial side loads.
  • the electric switch includes a hollow operating plunger and the guide means comprises a fixed pin member upstanding within the housing, the operating plunger being located on, for guided movement along, said pin member.
  • the electric switch includes an anchor terminal fixedly mounted therein, said terminal having an anchor portion within the housing against which the free end of the or each stressed leg of the leaf spring is urged for pivotal engagement therewith, and a terminal portion projecting from the housing, the pin member being integrally formed with said anchor terminal.
  • the operating plunger may comprise a plunger portion one end extent of which projects from the housing and in the hollow other end extent of which is fixedly received a hollow sleeve portion, said sleeve portion being located on, for guided linear movement along, said pin member.
  • the sleeve portion is an interference fit within the hollow other end extent of the plunger portion.
  • the guide means may comprise one or more walls upstanding within the housing and integrally formed therewith to define a hollow interior to receive therein said plunger.
  • the operating plunger may comprise a plunger portion one end extent of which projects from the housing, the other end extent of which is fixedly located within a hollow sleeve portion, said sleeve portion being located in, for guided linear movement along, the hollow interior of the guide means.
  • the other end extent of the plunger portion is an interference fit within the sleeve portion.
  • the illustrated switch is of relatively conventional construction in its lower and intermediate regions, comprising a moulded base portion 2, typically of glass-filled polyamide, in which are encapsulated an anchor terminal 4, a bottom contact terminal 6 and a top contact terminal 8, said terminals respectively including, above the base portion 2, an anchor portion 10, a bottom contact 12 and a top contact 14.
  • the anchor portion 10 has a notched face for the mounting thereto of a snap-action mechanism indicated generally at 16 and which will be described in more detail below but which includes contact members 18', 18" movable between a first position engaging the contact 14 and a second position engaging the contact 12 thereby to alter the electrical condition of the switch.
  • a snap-action mechanism indicated generally at 16 and which will be described in more detail below but which includes contact members 18', 18" movable between a first position engaging the contact 14 and a second position engaging the contact 12 thereby to alter the electrical condition of the switch.
  • the body of the switch is completed by a lid portion 20 manufactured in accordance with the method detailed in our European patent application no. 93309160.5.
  • the lid portion 20 is injection moulded from a glass-filled polyamide and includes an aperture therethrough in which is located an operating plunger 22 of the same material.
  • a peripheral seal 26 extends around the bottom edge of the lid portion 20 to react between the lid portion 20 and the base portion 2, the seal 26 being of the same thermoplastic elastomer material as the cowl 24, being integrally moulded with said cowl 24 and being integrally bonded to the lower edge of the lid portion 20 to provide a sealed housing for the switch.
  • lid portion 20, the plunger 22, the cowl 24 and the peripheral seal 26 constitute a single component, thus facilitating handling and assembly of the switch.
  • the snap-action mechanism 16 comprises a thin leaf spring including three parallel legs 28, 30, 32 the rear ends of the outer ones 30, 32 of which are interconnected as seen in dotted lines in Fig. 3.
  • the central leg 28 has a free rear end, while the front ends of all three legs are integral with each other and carry upper and lower contact members 18', 18".
  • the aforementioned plunger 22 includes a hollow inner member 34 which is an interference fit in the hollow interior of said plunger 22 to be movable therewith, while an upstanding guide pin 36 is integrally formed with the anchor terminal 4 within the housing to receive thereon the inner member 34, linear movement of the plunger 22 and the inner member 34 as a unit between their rest and displaced positions therefore being positively guided by said guide pin 36.
  • a compression spring 38 reacts between the base portion 2 of the housing and the undersurface of the inner member 34 to bias the plunger 22 towards its rest position shown in Fig. 1.
  • the interconnected rear ends of the legs 30, 32 are fixedly secured to the inner member 34 by means of overmoulding the inner member 34 onto said rear ends of the legs 30,32, thereby combining these two components into a single component for ease of handling.
  • the interconnected rear ends of the legs 30,32 may be received in a groove or the like formed in the inner member 34 to be pivotally mounted on side member 34.
  • the free end of the central leg 28 is urged into pivotal engagement with the notch in the face of the anchor portion 10 of the anchor terminal 4 whereby said central leg 28 is longitudinally stressed as shown in Fig. 1.
  • the snap-action mechanism is such as to adopt the first stable position shown in Fig. 1 in which the contact member 18' engages the top contact 14 thereby completing the electric circuit between terminals 4 and 8.
  • Fig. 2 illustrates the position of the plunger 22 after maximum overtravel - in the case of a sealed ultraminiature switch the plunger of which can move 2.0 mm, overtravel may be 1.3 mm.
  • a metal guide pin 36 within the housing for guiding the downward linear movement of the plunger 22 enables the switch to withstand substantial side loads typically applied to the plunger 22 by actuating mechanisms in the form of linear or rotary cams and the like.
  • actuating mechanisms can be such as to impose side loads on the plunger which are of sufficiently high values that guide pins such as 36 in Fig. 1 to 3 are unable to withstand the forces thereon.
  • Figs. 4 to 6 illustrate an alternative switch to that of Figs. 1 to 3 and incorporating a plunger guide arrangement capable of withstanding these higher forces.
  • plunger 22, inner member 34 and guide pin 36 are replaced by an alternative arrangement.
  • the anchor terminal 4 does not include a guide pin integrally formed therewith. Instead, upstanding support walls 40,42 are integrally formed within the housing to define a substantially cylindrical interior thereto to guide the plunger arrangement as will be detailed below.
  • the wall 40 is of generally semi-circular transverse section, while the wall 42 is of arcuate cross-section as best seen in Fig. 6 whereby there are two slots between the walls 40 and 42 for passage therethrough of the legs 30,32 of the leaf spring.
  • the operating plunger 22 includes a downwardly depending pin portion 44 which is an interference fit in the hollow interior of a sleeve portion 46 which is shaped to be a close sliding fit in the hollow interior defined by the walls 40,42.
  • the rear ends of the legs 30,32 are fixedly secured to the sleeve portion 46 by means of overmoulding, thereby integrating the leaf spring 16 and the sleeve portion 46 for ease of handling.
  • the interconnected rear ends of the legs 30,32 may be received in a groove or the like formed in the sleeve portion 46 to be pivotally mounted on said sleeve portion 46.
  • any non-axial forces applied to the plunger 22 by external actuating mechanisms are absorbed by the support walls 40,42, which further ensure that the plunger 22 and sleeve portion 46 undergo the desired sliding linear movement within the housing 2 to actuate the snap action mechanism 16.
  • the wall 42 is itself reinforced by the anchor portion 10 of the terminal 4.
  • the two outer legs of the leaf spring may be stressed with the rear end of the central leg attached to, to be moved by, the plunger 22/inner member 34, while, in the embodiment of Figs. 1 to 3, the guide pin 36 may be other than part of the anchor terminal 4, and may be of plastic or other suitable material.
  • the guide pin 36 may be other than part of the anchor terminal 4, and may be of plastic or other suitable material.

Landscapes

  • Push-Button Switches (AREA)
EP19970300686 1996-02-06 1997-02-04 Electrischer Schalter Expired - Lifetime EP0789373B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9602320.5A GB9602320D0 (en) 1996-02-06 1996-02-06 Electric switch
GB9602320 1996-02-06

Publications (2)

Publication Number Publication Date
EP0789373A1 true EP0789373A1 (de) 1997-08-13
EP0789373B1 EP0789373B1 (de) 2000-06-07

Family

ID=10788156

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19970300686 Expired - Lifetime EP0789373B1 (de) 1996-02-06 1997-02-04 Electrischer Schalter

Country Status (3)

Country Link
EP (1) EP0789373B1 (de)
DE (1) DE69702216T2 (de)
GB (1) GB9602320D0 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1533822A1 (de) * 2003-11-20 2005-05-25 Crouzet Automatismes Mikroschalter mit Funktionsänderung anhand der Blattfeder
US6998555B2 (en) 2003-11-20 2006-02-14 Crouzet Automatismes Miniswitch

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102014005433A1 (de) * 2014-02-15 2015-08-20 Johnson Electric Germany GmbH & Co. KG Mikroschalter mit einem aus Schalterbasis und Schalterdeckel ausgebildeten Gehäuse

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2479313A (en) * 1947-07-29 1949-08-16 Gen Electric Column spring switch
US2533671A (en) * 1948-04-13 1950-12-12 Acro Mfg Co Method and means for mounting snap action switch blades
DE1879992U (de) * 1958-10-28 1963-10-03 Vedder Gmbh Geb Kleinstschalter mit als schnappfeder ausgebildetem beweglichem kontaktorgan.
US3336449A (en) * 1965-01-27 1967-08-15 Plessey Uk Ltd Snap action switch mechanism with improved movable contact assembly
CH453461A (de) * 1964-06-13 1968-06-14 Gustav Giersiepen Fa Elektrischer Wippenschalter

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2479313A (en) * 1947-07-29 1949-08-16 Gen Electric Column spring switch
US2533671A (en) * 1948-04-13 1950-12-12 Acro Mfg Co Method and means for mounting snap action switch blades
DE1879992U (de) * 1958-10-28 1963-10-03 Vedder Gmbh Geb Kleinstschalter mit als schnappfeder ausgebildetem beweglichem kontaktorgan.
CH453461A (de) * 1964-06-13 1968-06-14 Gustav Giersiepen Fa Elektrischer Wippenschalter
US3336449A (en) * 1965-01-27 1967-08-15 Plessey Uk Ltd Snap action switch mechanism with improved movable contact assembly

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1533822A1 (de) * 2003-11-20 2005-05-25 Crouzet Automatismes Mikroschalter mit Funktionsänderung anhand der Blattfeder
FR2862808A1 (fr) * 2003-11-20 2005-05-27 Crouzet Automatismes Minirupteur avec differenciation par la lame
US6998555B2 (en) 2003-11-20 2006-02-14 Crouzet Automatismes Miniswitch
CN100456404C (zh) * 2003-11-20 2009-01-28 克劳齐特自动公司 小型开关

Also Published As

Publication number Publication date
GB9602320D0 (en) 1996-04-03
DE69702216T2 (de) 2001-03-01
DE69702216D1 (de) 2000-07-13
EP0789373B1 (de) 2000-06-07

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