[go: up one dir, main page]

WO1992012524A1 - Interrupteur electrique a sensibilite thermique - Google Patents

Interrupteur electrique a sensibilite thermique Download PDF

Info

Publication number
WO1992012524A1
WO1992012524A1 PCT/GB1992/000022 GB9200022W WO9212524A1 WO 1992012524 A1 WO1992012524 A1 WO 1992012524A1 GB 9200022 W GB9200022 W GB 9200022W WO 9212524 A1 WO9212524 A1 WO 9212524A1
Authority
WO
WIPO (PCT)
Prior art keywords
switch
ptcr
spring
terminal part
spring member
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.)
Ceased
Application number
PCT/GB1992/000022
Other languages
English (en)
Inventor
Paul Boundy
Christopher Laurence Partington
Mark Arthur Seddon
Adrian Mark Johnston
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.)
Otter Controls Ltd
Original Assignee
Otter Controls 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 Otter Controls Ltd filed Critical Otter Controls Ltd
Priority to EP92902253A priority Critical patent/EP0565577B1/fr
Priority to DE69212804T priority patent/DE69212804T2/de
Publication of WO1992012524A1 publication Critical patent/WO1992012524A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H77/00—Protective overload circuit-breaking switches operated by excess current and requiring separate action for resetting
    • H01H77/02—Protective overload circuit-breaking switches operated by excess current and requiring separate action for resetting in which the excess current itself provides the energy for opening the contacts, and having a separate reset mechanism
    • H01H77/04—Protective overload circuit-breaking switches operated by excess current and requiring separate action for resetting in which the excess current itself provides the energy for opening the contacts, and having a separate reset mechanism with electrothermal opening
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/50—Means for increasing contact pressure, preventing vibration of contacts, holding contacts together after engagement, or biasing contacts to the open position
    • H01H1/504—Means for increasing contact pressure, preventing vibration of contacts, holding contacts together after engagement, or biasing contacts to the open position by thermal means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
    • H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
    • 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
    • H01H11/0006—Apparatus or processes specially adapted for the manufacture of electric switches for converting electric switches
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
    • H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
    • H01H2037/5481—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting the bimetallic snap element being mounted on the contact spring
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
    • H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
    • H01H37/5409—Bistable switches; Resetting means

Definitions

  • This invention concerns improvements relating to thermally responsive electric switches for use for example in domestic electrical appliances such as fan heaters, toasters, cable reels etc. for switching off or substantially reducing the supply of power ro the appliance in an overtemperature situation.
  • the present invention in one of its aspects proposes to meet the above entioned requirement by provision of a switch comprising a moulded plastics body portion having first and second metal terminal parts encapsulated therein, the first metal terminal part serving additionally as a mounting for a first electrical contact cf the switch and the second metal terminal part serving additionally as a mounting for a cantilevered electrically-conductive springmember which carries at its free end a second electrical contact of the switch, said first and second electrical contacts being arranged to effect switching operations in operation of the switch, a bimetallic element being mounted on said spring member and being arranged to effect switch-operating movement thereof when it changes its state in response to a temperature change, and the moulded plastics body portion of the switch furthermore being formed to define a recess for accommodating a PTCR element in electrical and thermal contact with said second terminal part and a mounting for a push-fit conductor element adapted when fitted to serve as a retainer for holding said PTCR element in said recess under spring pressure and additionally to make
  • the moulded plastics body portion of the switch is generally rectangular in a preferred embodiment which will be described in detail hereinafter and defines spaced-apart end surfaces from which the first and second metal terminal parts project for enabling electrical connections to be made to the switch, an upper surface whereat the first terminal part cf the switch is exposed and has affixed thereto the first electrical contact (namely the fixed contact) cf the switch and whereat the second terminal part cf the switch is exposed and has affixed thereto said cantilevered spring member, an under surface whereat said recess is defined and exposes an under surface cf the second metal terminal part to contact by said PTCR element when fitted, whereat said mounting is provided for said push-fit conductor element, and whereat an under surface cf said first metal terminal part is exposed for being contacted by said conductor element when fitted, and two plain side surfaces.
  • the body portion of such a switch might be 20mm long, 5mm high and 7mm wide.
  • the cantilevered spring member conveniently comprises a leaf spring which advantageously may be attached to the second metal terminal part of the switch by means cf a rivet formed as an integral part cf the second metal terminal part.
  • the bimetallic element preferably is a dished snap-acting blade and may conveniently be mounted on top cf the cantilevered leaf spring by virtue of the leaf spring having released therefrom a pair of opposed attachment tabs between which the bimetallic blade is adapted to fit.
  • the push-fit conductor element may advantageously comprise a conductor spring formed of beryllium copper or stainless steel for example, and may advantageously be retained to the moulded plastics body portion by virtue of the conductor spring being formed with one or more X-shaped, H-shaped, star-shaped or otherwise shaped cut-outs adapted to fit tightly over one or more studs moulded integrally with the body portion of the switch, the cut-out(s) of the conductor spring being designed to make an interference fit ever the stud(s) and to dig into the stud(s) when put under load thereby ensuring that high spring forces are developed to hold the PTCR element immebile and ensure good electrical contact.
  • the present invention provides a thermally-responsive electrical switch comprising a bimetallic switch-actuating element and a spring member arranged to effect switching movements in response to movements of said bimetallic element, said spring member being bistable whereby in the absence of an alternative input a movement of said bimetallic element in response to a predetermined temperature change will be ineffective to effect a switching operation of said spring member.
  • the switch of the present invention can be configured as an auto-reset switch by omission of the PTCR element or as a PTCR switch by inclusion cf the PTCR element.
  • the switch can also readily be configured as a manual reset switch.
  • Figures 1A to IF illustrate the embodiment when configured as an auto-reset switch
  • Figs. 1A and IB being side elevation views
  • Fig. 1C being a bottom plan view
  • Fig. ID being a sectional side elevation view
  • Fig. 1 ⁇ being a top plan view
  • Fig. IF showing two different perspective views
  • Figures 2A to 2F illustrate the embodiment when configured as a PTCR switch
  • Fig. 1A showing a perspective view of the basic switch unit as viewed from the underside
  • Fig. 23 showing the unit with the PTCR element added
  • Fig. 2C showing the completed switch with the connecter spring affixed
  • Figs. 2D, 2E and 2F being views similar to Figs. 1C, ID and IE respectively;
  • Figures 3A to 3E illustrate a slightly modified form cf the embodiment configured as a manual reset switch
  • Figs. 3A and 3B showing plan and side elevation views of a bistable leaf spring that is provided in this switch configuration
  • Fig. 3C being a side elevation view cf the manual reset switch in condition where the bimetallic element of the switch has reset with falling temperature and yet the leaf spring remains in its "hot” position
  • Fig. 3D being a perspective showing (partly enlarged) of the form of a reset push rod cf the switch and the manner of its incorporation nto the switch
  • Fig. 3E being a cross-sectional view through the switch- in the plane of the push rod.
  • the switch comprises a moulded plastics body portion 20 having first and second metal terminal parts 1, 2 captured therein, the terminal parts projecting beyond the body portion 20 for enabling electrical 3 connection to be made to the switch.
  • the first terminal part 1 serves as a mounting for a fixed switch contact 3
  • the second terminal part 2 serves as a mounting for a cantilevered leaf spring 4 which is affixed to the terminal part 2 by means of an integrally-formed rivet and carries at its free end a moving switch contact 5 which is positioned to co ⁇ operate with the fixed contact 3.
  • the leaf spring 4 has opposed attachment tabs 6 released therefrom and a dished, snap-acting bimetallic blade 7 is received between the tabs and thereby attached to the leaf spring 4.
  • the bimetal blade 7 is capable of adopting two different curvature states dependent upon its temperature, and in its "hot” condition as shown in Fig. 1A serves to lift the free end cf the leaf spring 4 and thereby open the switch contacts, and in its "cold” condition as shown in Fig. IB does not resist the natural tendency of the leaf spring 4 to hold the switch contacts closed.
  • a recess 8 providing access to the first terminal part 1
  • a recess 9 providing access to the second terminal part 2
  • a body portion which bridges the recesses S, 9 and has formed thereon a pair of studs 10.
  • the recess S is designed to receive a PTCR element 11 in the form of a small cylindrical pellet
  • the studs 10 are designed to receive a conductor spring 12 having generally H-shaped cut-outs
  • the spring 12 extends into.the recess 3 where it contacts the first terminal
  • the spring 12 thus constituting a conductor connecting the PTCR element 11 (which is itself in contact with the second terminal 2) to the first terminal 1.
  • the H-shaped cut-outs 13 in the conductor spring 12 are such that the tension that is developed in the spring when it is pushed ever the studs 10 causes the spring to bite into the studs so as to ensure proper firm location of the spring, with the PTCR element 11 held firmly in the recess 9 in good electrical contact with second terminal 2 and with good electrical contact made with first terminal 1.
  • the switch operates as an automatically resetting switch which opens its contacts at a predetermined temperature in a rising temperature situation and subsequently recloses the contacts at a second, lower, predetermined temperature as the bimetal cools.
  • the switch is reconfigured as a switch which will maintain its contacts open, once they have opened in a rising temperature situation, by virtue of heat developed in the PTCR element being conducted into the bimetal blade.
  • the PTCR element is normally short- circuited by the closed switch contacts so long as the switch is operating within its upper temperature limit, but carries current when the switch contacts open and experiences a rapid increase in resistance which dramatically reduces the current supply to the lead as soon as the switch contacts open.
  • the PTCR switch configuration can only be reset by switching off the power supply to the switch and its associated appliance and allowing time for the PTCR and bimetal to cool to its remake temperature.
  • a manual reset version cf the described switch could for example readily be configured by provision of a through hole in the body moulding of the switch, extending from a location intermediate the studs 10 on the rear of the body moulding through to a location on the front of the moulding underlying the leaf spring and bimetal blade assembly, and by provision of a push-rod in such through hole arranged so as when depressed to be capable of bearing upon the underside of the bimetal blade, an opening being provided in the leaf spring to allow the push-rod to access the bimetal.
  • the switch advantageously might be formed with a back-stop for limiting the contacts-opening movement of the leaf spring and/or cf the bimetal blade and, in keeping with the aim of enhanced versatility, such back ⁇ stop could be formed as a separate component, a plastics moulding for example, arranged to be clipped onto or otherwise detachably secured to the body moulding of the switch, though it could equally well be formed as an integral part of the body moulding.
  • a mechanical and manually-releasable latch may be provided for latching the leaf spring in its contacts open condition.
  • FIG. 3A and 3B show the form of the leaf spring 4 and it will be seen that the spring is generally rectangular with an elongate central cut-out 15 defining spaced-apart legs 16, and furthermore is tooled using a spherical punch in order to produce a domed region 17 in the area identified by the circle 13 in Fig. 3A and render the spring bistable in operation.
  • the amount of doming is controlled such that the inner edges of the twisted spring legs 16 do not protrude above the central pillar 19 of the switch body portion 20 when the spring is welded to the respective part of switch terminal 2, and such that the spring will generate the requisite contact pressure without being too stiff for the bimetal 7 to overcome.
  • FIG. 3D shows the switch body 20 configured to receive a push-rod 25 which is inserted into a complementarily profiled opening formed through the switch body before attachment of the leaf spring 4 and its actuating bimetal 7 to the switch.
  • the push-rod 25 is also shown in enlarged view in Fig. 3D and it will be seen to have a hemispherical groove 26 in one face which forms a guiding surface with the central pillar 19 when the push-rod is inserted into the switch body 20.
  • the push-rod additionally has an enlarged upper end cr head 27 which serves tc retain it in the switch and a pair of projecting abutments 28 are provided on the upper surface of this head 27 for contacting the inside edges of the legs 16 cf the leaf spring 4 in order to effect resetting of the switch.
  • the switch of the present invention is adapted to be configured selectively as an auto-reset switch, a manual reset switch, or a PTCR switch.
  • the bimetal and leaf spring characteristics can be varied so as selectively to accommodate different switching requirements, for example by use of a more or less resistive material for the leaf spring so as to render the switch more or less current sensitive, without requiring any change in the geometry cf the switch.
  • the invention provides a versatile switch design which enables the diverse requirements cf different applications to be satisfied by a single switch geometry which is designed to enable automatic manufacture and assembly of the various switch parts.
  • thermally-responsive electrical switch for use in domestic electrical appliances for switching off the electrical supply to the appliance in an over temperature situation is configured to be manufactured as an auto-reset switch, as a manual reset switch, or as a PTCR switch without significant manufacturing changes.
  • the switch body is moulded plastics and incorporation first and second terminal parts, one of which provides a cantilever mounting for a switching element which moves to effect switching operations between its free end and the other terminal part.
  • a bimetallic switch- actuating element is mounted en the switching element so as by its temperature-responsive movements to effect switch-operating movement of the switching element.
  • the switch body is configured to be capable of accepting a PTCR element which is retained by a conductor such that the PTCR element is placed in a current conducting path through the switch when the switch contacts are opened, the heat developed in the PTCR element then holding the condition cf the switch whilst substantially reducing the through current tc the switch 1 rod.

Landscapes

  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Thermally Actuated Switches (AREA)

Abstract

Un interrupteur électrique à sensibilité thermique, destiné à être utilisé dans des appareils électroménagers afin d'interrompre l'alimentation de courant de l'appareil dans une situation de surchauffe, est conçu pour être fabriqué sous forme d'un interrupteur à réenclenchement automatique, à réenclenchement manuel ou à coefficient de température positive de résistance (CTPR) sans nécessiter de modifications de fabrication importantes. Le corps (20) de l'interrupteur est en matière plastique moulée et comprend une première et une seconde bornes (1, 2), dont l'une sert à monter en porte-à-faux un élément de contact (4) qui se déplace de manière à effectuer des opérations de coupure entre son extrémité libre et l'autre partie en forme de borne. Un élément bimétallique (7) d'actionnement d'interrupteur est monté sur l'élément (4) de contact de façon à actionner, par l'intermédiaire de ses mouvements sensibles à la température, le mouvement d'actionnement de coupure de l'élément de contact. Le corps (20) de l'interrupteur est configuré de façon à pouvoir accepter un élément à CTPR (11) retenu par un conducteur (12) de telle manière que l'élément à CTPR (11) est placé dans une trajectoire de conduction de courant traversant l'interrupteur lorsque les contacts sont ouverts, la chaleur développée dans l'élément CTPR (11) maintenant alors la position de l'interrupteur tout en réduisant sensiblement le courant traversant jusqu'à la charge de contact. En omettant l'élément à CTPR, un interrupteur à réenclenchement automatique est obtenu et, lorsqu'on choisit les caractéristiques de l'élément bimétallique et/ou lorsqu'on agence l'élément interrupteur de manière qu'il soit bistable, une variante à réenclenchement manuel de l'interrupteur peut être obtenue.
PCT/GB1992/000022 1991-01-04 1992-01-06 Interrupteur electrique a sensibilite thermique Ceased WO1992012524A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP92902253A EP0565577B1 (fr) 1991-01-04 1992-01-06 Interrupteur electrique a sensibilite thermique
DE69212804T DE69212804T2 (de) 1991-01-04 1992-01-06 Wärmeempfindlicher elektrischer schalter

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9100186.7 1991-01-04
GB919100186A GB9100186D0 (en) 1991-01-04 1991-01-04 Improvements relating to thermally responsive electric switches

Publications (1)

Publication Number Publication Date
WO1992012524A1 true WO1992012524A1 (fr) 1992-07-23

Family

ID=10687988

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1992/000022 Ceased WO1992012524A1 (fr) 1991-01-04 1992-01-06 Interrupteur electrique a sensibilite thermique

Country Status (6)

Country Link
EP (1) EP0565577B1 (fr)
AU (1) AU1159392A (fr)
DE (1) DE69212804T2 (fr)
ES (1) ES2090603T3 (fr)
GB (1) GB9100186D0 (fr)
WO (1) WO1992012524A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4053859A (en) * 1975-10-03 1977-10-11 Inter Control, Herman Kohler Elektrik Gmbh & Co Kg Temperature sensitive switch
DE3104827A1 (de) * 1981-02-11 1982-08-19 Limitor AG, 8022 Zürich "bimetalltemperaturschalter"
DE8617033U1 (de) * 1986-06-26 1986-08-14 Temtech-Temperatur-Technik Hans-Peter Bojer, 7530 Pforzheim Bimetallschalter
AT383696B (de) * 1982-03-03 1987-08-10 Electrovac Thermischer schalter
EP0376660A2 (fr) * 1988-12-28 1990-07-04 Otter Controls Limited Interrupteurs thermiques

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4053859A (en) * 1975-10-03 1977-10-11 Inter Control, Herman Kohler Elektrik Gmbh & Co Kg Temperature sensitive switch
DE3104827A1 (de) * 1981-02-11 1982-08-19 Limitor AG, 8022 Zürich "bimetalltemperaturschalter"
AT383696B (de) * 1982-03-03 1987-08-10 Electrovac Thermischer schalter
DE8617033U1 (de) * 1986-06-26 1986-08-14 Temtech-Temperatur-Technik Hans-Peter Bojer, 7530 Pforzheim Bimetallschalter
EP0376660A2 (fr) * 1988-12-28 1990-07-04 Otter Controls Limited Interrupteurs thermiques

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SIEMENS-ZEITSCHRIFT, Vol. 51, No. 1, 1977, ERLANGEN, D. ENGSTLER, "Scheiben Aus Thermobimetall", pages 53-59. *

Also Published As

Publication number Publication date
EP0565577A1 (fr) 1993-10-20
ES2090603T3 (es) 1996-10-16
GB9100186D0 (en) 1991-02-20
EP0565577B1 (fr) 1996-08-14
AU1159392A (en) 1992-08-17
DE69212804T2 (de) 1997-02-20
DE69212804D1 (de) 1996-09-19

Similar Documents

Publication Publication Date Title
US5367279A (en) Overcurrent protection device
RU2553280C2 (ru) Миниатюрный предохранительный выключатель
US4733033A (en) Molded case circuit breaker contact arrangement including a spring clip contact arm retainer
US5796327A (en) Thermally responsive electrical switches
US5847638A (en) Thermal circuit protector and switch
US5929742A (en) Trip-free, manual reset thermostat
EP0202939A2 (fr) Eléments de chauffage électrique à immersion et dispositifs de commande pour ces éléments
JP4339750B2 (ja) 手動復帰型サーモスタット
US5982269A (en) Electric switch and thermal protector
EP0105879A1 (fr) Commutateur thermique.
US5703560A (en) Thermostat with one-piece reset mechanism and contact assembly
GB2252674A (en) Thermally responsive electrical switches
US3256413A (en) Wafer thin thermostat
EP0565577B1 (fr) Interrupteur electrique a sensibilite thermique
US4075594A (en) Thermostat with reset arm
US2892910A (en) Electric motor circuit breaker or protector
EP1072048B1 (fr) Ameliorations relatives aux commandes de temperature d'elements chauffants electriques
EP1278226B1 (fr) Disjoncteur de protection à déclenchement manuel
US2664480A (en) Circuit breaker
US3946352A (en) Thermally responsive switch
US4001751A (en) Non-resettable thermostat
US4633211A (en) Electrical switch construction and method of making the same
EP0376660A2 (fr) Interrupteurs thermiques
US3197594A (en) Thermo-sensitive switch plug
US4736514A (en) Method of making electrical switch

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU CA GB JP US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IT LU MC NL SE

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
WWE Wipo information: entry into national phase

Ref document number: 1992902253

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 1992902253

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: CA

WWG Wipo information: grant in national office

Ref document number: 1992902253

Country of ref document: EP