EP0187480A1 - Interrupteur sensible à la température - Google Patents

Interrupteur sensible à la température Download PDF

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Publication number
EP0187480A1
EP0187480A1 EP85308883A EP85308883A EP0187480A1 EP 0187480 A1 EP0187480 A1 EP 0187480A1 EP 85308883 A EP85308883 A EP 85308883A EP 85308883 A EP85308883 A EP 85308883A EP 0187480 A1 EP0187480 A1 EP 0187480A1
Authority
EP
European Patent Office
Prior art keywords
contact
housing
path
contact member
switch
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.)
Withdrawn
Application number
EP85308883A
Other languages
German (de)
English (en)
Inventor
Alan Murray
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.)
Elmwood Sensors Ltd
Elmwood Sensors Inc
Original Assignee
Elmwood Sensors Ltd
Elmwood Sensors 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 Elmwood Sensors Ltd, Elmwood Sensors Inc filed Critical Elmwood Sensors Ltd
Publication of EP0187480A1 publication Critical patent/EP0187480A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • H01H37/5427—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting encapsulated in sealed miniaturised housing

Definitions

  • This invention relates to temperature responsive switches and particularly to such switches in which a bimetallic disc or other temperature sensitive element displaces a contact arm to make or break electrical continuity.
  • switches find wide application in the automobile field and in a variety of domestic appliances. Despite the fact that high accuracy and electrical safety standards are usually demanded of the switches, it is often a commercial necessity that these switches be produced at low cost. Accordingly, it is an object of this invention to produce an improved temperature responsive switch which may be manufactured simply and at low cost.
  • the present invention consists in a temperature responsive switch comprising an electrically insulating housing formed in one piece and defining a straight contact path; a first unitary contact member having a terminal for external connection and a fixed contact; a second unitary contact member having a terminal for external connection and a contact arm carrying a movable fixed contact; and temperature sensitive means adapted to displace the contact arm at a predetermined temperature thereby to make or break electrical continuity between the said contacts, wherein the housing is provided with integral support formations such that the contact members may on assembly of the switch be slid into the housing in opposite senses along the contact path, engagement between said formations and the contact members preventing any substantial movement of the contact members orthogonally of the contact path, there being provided contact locking means acting after insertion of the contact members to hold the same against movement along the contact path.
  • the contact locking means comprises for each contact member an electrically insulating pin arranged to pass through aligned apertures in the contact member and housing respectively.
  • the second unitary contact member is formed by welding a sprung contact arm to a rigid terminal.
  • the temperature responsive switch shown in the drawings has an electrically insulating housing formed as a single injection moulding.
  • the housing comprises a flat base 12 from which are upstanding four support blocks 14 arranged generally at the corners of the base.
  • On two opposing sides of the base a wall 16 extends -between the two corresponding support blocks.
  • a straight contact path is defined between the support blocks; the contact path being marked XX in Figure 2.
  • Each support block 14 is undercut to form a groove 18, parallel to the contact path.
  • the housing base 12 has a central bore 20 which carries a freely movable transfer pin 22.
  • the housing base is formed with a recess 24 to accommodate a bimetallic disc 26. This disc cooperates with the transfer pin in the standard manner to move a contact arm, details of which will be given below.
  • the housing base 12 carries lateral flanges 28.
  • An aluminium cap 30 is secured to the housing, trapping the bimetallic disc, by means of ears 32 which are crimped over these lateral flanges.
  • the cap shown in the drawings includes a mounting stud 34 but it will be appreciated that the cap can if necessary be provided with apertures or indeed any other suitable mounting elements.
  • the illustrated switch has two contact members.
  • the first contact member comprises a terminal 36, of stainless steel or German silver, having at its outer end the shape and dimension of a standard spade terminal.
  • the terminal In a position overlying the end of the housing base 12, the terminal is provided with an oval aperture 38 which defines a transverse bending line 40. Inwardly of this oval aperture, the terminal has a circular aperture 42 the purpose of which will be described hereinafter.
  • the lateral edges of the terminal are thickened to provide mounting shoulders 44. Adjacent the innermost end, the terminal has a welded fixed contact 46 of silver/nickel alloy.
  • the second contact member comprises a terminal 36' with an oval aperture 38', a circular aperture 42' and mounting shoulders 44' which are substantially identical to those of the first terminal 36.
  • the second contact member differs from the first in that, in place of the fixed contact 46, there is welded a contact arm 48.
  • This contact arm is not formed of the copper beryllium alloy that is customary but is formed of a copper alloy DELCAN S18 which contains substantially no beryllium.
  • the contact arm has a welding portion 50 of reduced width; a central downward projection 52 which engages the transfer pin; longitudinal stiffening ridges 54, one each side of the projection 52 and a contact carrying portion 56 to the underside of which is welded a movable contact 58 of silver/nickel alloy.
  • the terminal 36' is formed at its inner end with two small ridges 60 running parallel to the contact path and spaced on each side of the centre line.
  • This arrangement is felt to be particularly advantageous in maximising the working life of the switch.
  • a crack appearing at the forward edge of each weld would not seriously affect the current carrying capability of the arm.
  • any crack would be expected to follow along the longitudinal edges of each weld so that, until the crack reached the rearward end of the welds, the switch should continue to operate within the defined characteristic.
  • the manner in which the two contact members are secured in the housing is substantially identical.
  • the two contact members are pushed into the housing in opposite senses along the contact path XX.
  • Each terminal engages within the grooves 18 formed in the support blocks and, with the contact members in the final position, the shoulders 42 cooperate as a tight fit with these grooves.
  • the upper face of the housing base 12 is formed with two longitudinally extending abutments 62 which are parallel to the contact path. In the fully inserted position, the innermost end of each terminal engages the ends of these abutments so providing a stop. It will be understood that the engagement of the housing base 12 and support blocks 14 with each contact member serves to prevent substantially any movement of the contact member orthogonally of the contact path.
  • a retaining pin 64 which passes through an aperture 66 in the housing base and through circular aperture 40 in the terminal.
  • Each retaining pin has a tapered free end 68 to facilitate insertion and a cylindrical head 70 which abuts against the lower face of the housing base.
  • the contact members may be bent about the bending line 40 to give the required terminal angle externally of the housing. Since switches are conventionally offered with a range of terminal angles, this feature of bending the terminals after assembly will substantially reduce the inventory that is required to be kept of any one terminal design. In this regard it will be apparent to the skilled man that the illustrated spade terminal is but one example. The inventory is further reduced by the fact that, until the point at which preparations are made for welding of the fixed contact 46 or contact arm 48, the terminals 36 and 36' are indistinguishable.
  • the described switch is felt to have considerable advantages over the conventional construction in which rivets are used both to mount the terminals in the housing and to secure the contact arm to the corresponding terminal. There are advantages both in assembly of the switch and in the subsequent operation. Since the two contact members are unitary, there is an overall reduction in components and a simplification in component handling. Assembly is further simplified by the fact that the two contact members may simply be slid into position and are immediately held against any movement orthogonally of the contact path. Preferably, a stop is provided in the housing, as in the described embodiment, so that the contact members are also held in a direction along the contact path, inwardly of the housing. The contact members are now in their final position and the electrical resistance between the terminals may be checked if thought necessary.
  • the retaining pins are inserted together with the transfer pin and bimetallic disc and the assembly is completed once the cap is crimped in position. It will be noted that the cap is the only component which is permanently deformed. Until the cap is added, the components may be disassembled if an inspection or testing operation reveals a flow.
  • the housing may be formed with formations other than the described-grooved support blocks for mounting the contact members. All that is required is formations that enable the contact members to be slid into the housing in opposite senses along the contact path and to be held by engagement with the housing against any movement orthogonally of the contact path.
  • an abutment or other stop is provided to prevent inward movement of the contact members.
  • the locking means which prevent withdrawal of the contact members along the contact line may take forms other than the described retaining pins. It may be arranged, for example, for the frictional engagement between the contact members and the housing to provide the required resistance to withdrawal of the terminals.
  • the contact members may for example be provided with "saw teeth" on the longitudinal edges. In another alternative, a form of snap action engagement may be provided between the contact member and the housing.
  • such locking means will.offer lower resistance to withdrawal of the terminals than retaining pins or other positive locking means but may'nevertheless be sufficient in certain applications.
  • the advantage of having retaining pins of electrically insulating material is that the pin heads may be left exposed in the completed switch assembly. In other words, the cap need not completely cover the retaining pins and this leads to a further reduction in component costs.

Landscapes

  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Thermally Actuated Switches (AREA)
EP85308883A 1984-12-05 1985-12-05 Interrupteur sensible à la température Withdrawn EP0187480A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8430698 1984-12-05
GB8430698 1984-12-05

Publications (1)

Publication Number Publication Date
EP0187480A1 true EP0187480A1 (fr) 1986-07-16

Family

ID=10570726

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85308883A Withdrawn EP0187480A1 (fr) 1984-12-05 1985-12-05 Interrupteur sensible à la température

Country Status (1)

Country Link
EP (1) EP0187480A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0559517A1 (fr) * 1992-03-04 1993-09-08 Frisquet S.A. Thermostat à réarmement automatique

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3537052A (en) * 1969-02-13 1970-10-27 Therm O Disc Inc Thermostat
FR2437055A1 (fr) * 1978-09-22 1980-04-18 Texas Instruments Italia Spa Perfectionnement apporte a des thermostats, notamment du type a plusieurs temperatures d'intervention
DE2905149A1 (de) * 1979-02-10 1980-08-21 Microtherm Gmbh Klein-thermoschalter
US4368451A (en) * 1981-08-20 1983-01-11 Bucheister Henry C Thermostatic switch
EP0103792A2 (fr) * 1982-09-16 1984-03-28 Peter Hofsäss Dispositif pour commuter une connexion électrique en fonction du courant et/ou de la température
US4504814A (en) * 1982-03-30 1985-03-12 U.S. Philips Corporation Housing for a bimetallic thermal switch

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3537052A (en) * 1969-02-13 1970-10-27 Therm O Disc Inc Thermostat
FR2437055A1 (fr) * 1978-09-22 1980-04-18 Texas Instruments Italia Spa Perfectionnement apporte a des thermostats, notamment du type a plusieurs temperatures d'intervention
DE2905149A1 (de) * 1979-02-10 1980-08-21 Microtherm Gmbh Klein-thermoschalter
US4368451A (en) * 1981-08-20 1983-01-11 Bucheister Henry C Thermostatic switch
US4504814A (en) * 1982-03-30 1985-03-12 U.S. Philips Corporation Housing for a bimetallic thermal switch
EP0103792A2 (fr) * 1982-09-16 1984-03-28 Peter Hofsäss Dispositif pour commuter une connexion électrique en fonction du courant et/ou de la température

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0559517A1 (fr) * 1992-03-04 1993-09-08 Frisquet S.A. Thermostat à réarmement automatique
FR2688340A1 (fr) * 1992-03-04 1993-09-10 Frisquet Sa Thermostat a rearmement automatique.

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Inventor name: MURRAY, ALAN