EP0318265B1 - Temperatur emfindliche elektrische Schalter - Google Patents

Temperatur emfindliche elektrische Schalter Download PDF

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Publication number
EP0318265B1
EP0318265B1 EP19880311081 EP88311081A EP0318265B1 EP 0318265 B1 EP0318265 B1 EP 0318265B1 EP 19880311081 EP19880311081 EP 19880311081 EP 88311081 A EP88311081 A EP 88311081A EP 0318265 B1 EP0318265 B1 EP 0318265B1
Authority
EP
European Patent Office
Prior art keywords
switch
chassis
overcentre
bridge
thermally
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 - Lifetime
Application number
EP19880311081
Other languages
English (en)
French (fr)
Other versions
EP0318265A3 (en
EP0318265A2 (de
Inventor
Robert Andrew O'neill
Keith Fletcher
Terence James Collins Foster
Andrew Vincent Florentine
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
Priority claimed from GB878727412A external-priority patent/GB8727412D0/en
Priority claimed from GB888801438A external-priority patent/GB8801438D0/en
Priority claimed from GB888810506A external-priority patent/GB8810506D0/en
Application filed by Otter Controls Ltd filed Critical Otter Controls Ltd
Priority to AT88311081T priority Critical patent/ATE101452T1/de
Publication of EP0318265A2 publication Critical patent/EP0318265A2/de
Publication of EP0318265A3 publication Critical patent/EP0318265A3/en
Application granted granted Critical
Publication of EP0318265B1 publication Critical patent/EP0318265B1/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
    • 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
    • H01H3/00—Mechanisms for operating contacts
    • H01H3/32—Driving mechanisms, i.e. for transmitting driving force to the contacts
    • H01H3/46—Driving mechanisms, i.e. for transmitting driving force to the contacts using rod or lever linkage, e.g. toggle
    • H01H2003/466—Driving mechanisms, i.e. for transmitting driving force to the contacts using rod or lever linkage, e.g. toggle using a living hinge to connect the levers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H61/00—Electrothermal relays
    • H01H61/01—Details
    • H01H61/0107—Details making use of shape memory materials
    • H01H2061/0122—Two SMA actuators, e.g. one for closing or resetting contacts and one for opening them

Definitions

  • This invention concerns improvements relating to thermally responsive actuators, and has particular though not exclusive application to the field of thermally responsive electric switches for use in electrically heated water boiling vessels such as kettles, jugs, urns, pans, laboratory equipment and the like for switching off or reducing the supply of power to an electric heating element of the vessel when water or another liquid boils in the vessel and the vapour generated impinges upon a thermally-responsive switch-actuating element.
  • a snap-acting bimetal blade for example, there are in total twelve components, namely a snap-acting bimetal blade, a blade retainer moulding, a push rod, an overcentre arrangement comprising a trip lever coupled to the bimetal via the push rod and a C-spring biassing the trip lever, lid, cover and chassis mouldings, and a pair of leaf springs with attached switch contacts.
  • a snap-acting bimetal blade namely a snap-acting bimetal blade, a blade retainer moulding, a push rod, an overcentre arrangement comprising a trip lever coupled to the bimetal via the push rod and a C-spring biassing the trip lever, lid, cover and chassis mouldings, and a pair of leaf springs with attached switch contacts.
  • element protector switches are also known which are adapted to switch off the supply of power to the heating element of the vessel in response to a sensed element overtemperature condition, caused for example by switching on the vessel with insufficient water in it or by allowing the vessel to boil dry. It has been known to provide element protectors and steam sensors as entirely separate units and it has also been known to provide combined element protector and steam sensing units. Furthermore, it has been known to provide element protector and steam sensing units such that the element protector may be used alone or alternatively may be combined with a steam sensor in which case a mechanical interconnection between the element protector and the steam sensor has enabled the steam sensor to operate the switching contacts within the element protector.
  • an element protector unit has comprised a bimetallic switch actuating element arranged to determine the condition of switch contacts within the unit through the intermediacy of a push-rod arrangement, and a steam sensor unit adapted for use with the element protector unit has comprised a further bimetallic switch actuating element arranged so as in use to be exposed to steam generated when water boils in an associated vessel and a lever arrangement for coupling the resulting movement of the steam sensor bimetal to the push-rod of the element protector unit for operating the switch contacts therein when the steam sensor unit is appropriately combined with the element protector unit.
  • One object of the present invention is to enable the provision of a new and improved thermally responsive switch actuator and thermally responsive switch which is of simplified construction as compared to the abovementioned prior art devices, is capable of automatic assembly and enables cost savings to be made.
  • Another object of the present invention is to enable the provision of a new and improved steam sensor for an electrically heated water boiling vessel, such steam sensor being flexibly utilizable with element protector switches in a variety of different ways providing enhanced freedom for vessel design.
  • a thermally responsive snap-acting bimetallic actuator mechanism for developing an operational movement in response to a temperature change
  • said actuator mechanism comprising a moulded plastics material chassis, a bimetal blade, and a moulded plastics trip lever, characterized in that the bimetal blade and the trip lever are pivotally mounted in series with each other between two spaced-apart opposed mounting defined in said chassis so as to define a sprung overcentre bridge which is movable with a snap-action between two stable positions on opposite sides of an intermediate unstable position, the trip lever having one end portion which defines one end of the overcentre bridge and is pivotally mounted with respect to said chassis at one of said mountings, the bimetal blade having one end portion which defines the other end of the overcentre bridge and is pivotally mounted with respect to said chassis at the other of said mountings, the bimetal blade and the trip lever each having another end portion whereat the trip lever and the bimetal blade pivotally engage each other at an intermediate location in the overcentre bridge, and an
  • an effective steam sensing device can be obtained by combining the bimetal mounting and overcentre trip-lever arrangement, which in the conventional devices aforementioned has required as many as seven separate components, into a module which comprises only three functional parts and can be configured as only two structural components.
  • a thermally responsive switch actuator embodying the present invention comprises a bimetal blade, a trip lever, and a chassis which supports the bimetal and the trip lever, the chassis providing spaced-apart mountings which are bridged by the bimetal blade and the trip-lever mounted in series with each other and defining a snap-acting overcentre arrangement the range of movement whereof is limited by abutment with the chassis at least in the cold condition of the bimetal and preferably also in the hot condition of the bimetal.
  • the overcentre bridge extending between the spaced-apart mountings in the chassis is constituted by one end of the bimetal being pivotally received in one of the chassis mountings and defining one end of the bridge, one end of the trip-lever being received in the other of the chassis mountings and defining the other end of the bridge, and the other ends of the bimetal and the trip-lever abutting each other generally intermediate the ends of the bridge.
  • the chassis further defines stops or abutments limiting the range of movement of the overcentre bridge in both directions, that is to say both the cold condition position and the hot condition position of the overcentre bridge are defined by the chassis, and also provides an abutment against which the bimetal may act to provide the actuating force for movement of the bridge between its two stable states, namely its cold state and its hot state.
  • the chassis in this embodiment also provides compliance to accommodate the change in the dimensions of the overcentre bridge between the spaced-apart bimetal and trip-lever mountings as the bridge moves between its two stable states, though this compliance could alternatively or additionally be provided by the trip-lever.
  • the compliant abilities of the chassis can be augmented or supplemented by use of a spring metal component supported in the chassis and in turn supporting one end of the bimetal.
  • the trip-lever could be formed integrally with the chassis moulding, with the result that a two-part switch actuator is obtained.
  • the trip lever might be pivotally mounted to the chassis moulding by means of an integral moulded hinge.
  • Plastics materials are well known which are suitable for the formation of such integrally moulded hinges, though it may be preferred, given that the moulding may be subjected to relatively high temperatures by virtue of the impingement of hot vapour thereon, to utilize a non-integral mounting arrangement which is not prejudiced by any reduction in the strength of the plastics material at elevated temperatures and enables stronger materials to be used which are not as well suited to the formation of integrally moulded hinges.
  • Polypropylene as is well known, is a material which can be formed into effective integral hinges but is weakened by exposure to high temperatures, and rather than using polypropylene it might accordingly be preferable instead to use a stronger material, such as glass filled nylon for example, and form the pivotal bimetal and trip-lever mountings as knife edge type mountings.
  • the switch actuator as above described thus has three functional parts, namely the bimetal, the trip-lever and the chassis, and can be formed in only two parts or as three.
  • the bimetal serves two functions, firstly it acts as a thermally active component providing the force which generates the action of the device in response to a change in temperature, and secondly it provides the spring force which operates the overcentre bridge and provides a bistable latch mechanism which, for example, could open and hold open switch contacts.
  • the trip-lever is moved by the action of the bimetal and may be used to transmit this movement to switch contacts, for example.
  • the chassis provides support for the bimetal and the trip-lever, providing a pivotal mounting for both components and allowing them to rotate through an angle limited by stops or abutments on the chassis, and also providing the compliance necessary to accommodate the movement of the overcentre bridge.
  • a suitable material such as a flame retardant plastics material, it could also be used to support the electrical components of a switch.
  • the bimetal blade need not be of any special configuration and does not itself have to be snap acting.
  • the bimetal is a flat rectangular blade of a grade suitable for the intended application of the actuator.
  • a corrosion (rust) resistant bimetal clearly would be preferred, and generally a high-flexivity, high yield strength, spring-grade bimetal might be preferred.
  • the bimetal requires no special forming or tooling and no subsequent stress relief or selection.
  • the dimensions of the bimetal also are not critical, enabling manufacturing tolerances to be readily accommodated without prejudicing the operational characteristics of the actuator.
  • the switch actuator as generally described in the foregoing can be utilized with the chassis fixedly mounted as a switch component and switch-operating movement developed by the trip-lever, and can alternatively be utilized with the trip-lever fixedly mounted and the chassis moving to develop the requisite switch operation.
  • the latter arrangement is particularly well suited to utilization in steam sensor switches for electric kettles and the like and where the chassis moulding or a part mounted thereon can conveniently be used as a reset knob.
  • switch actuators hereinafter described and switches embodying such switch actuators have the advantage over conventional switch actuators as hereinbefore described that they require only a minimum number of components which furthermore are more simple than those previously utilized.
  • the switches according to the invention are thus better suited to automatic assembly and can be cost advantageous. Furthermore, extended working life may be expected by utilization of appropriate materials and by virtue of the elimination of the high stress levels that are normally present in conventional bistable bimetal actuators and lead to fatigue failures of such actuators.
  • the switch actuators hereinafter described have no push rod and no gap between the bimetal and the moving switch parts, as is present in conventional switches, and thus avoid the conventional difficulty that resetting cannot be accomplished until the bimetal cools; with the switches hereinafter described there can be no set/reset temperature differential and resetting can be achieved without the necessity of waiting until the bimetal cools.
  • the steam sensor is configured as a switch actuator and does not itself have any switch contacts, and is arranged to be coupled by a Bowden cable or the like to the element protector device for operating a set of switch contacts provided therein.
  • a steam sensor module suitable for use with an electrically heated water boiling vessel for switching off the supply of electricity to the heating element of the vessel when water boils in the vessel and steam impinges upon a thermally sensitive element of the module.
  • the module comprises a main moulding 1, a lower leaf spring 2, an insulator 3, a switch actuator sub-assembly 4, an upper leaf spring 5, and a closure moulding 6.
  • the switch actuator sub-assembly 4 comprises a chassis moulding 7 having integrally formed therewith a trip-lever 8 which couples at one end to the chassis moulding via an integral hinge 9, and a rectangular bimetal blade 10.
  • the chassis moulding 7 defines a V-notch pivotal mounting 11 for one end of the bimetal blade 10 and the other end of the bimetal blade 10 lodges in a V-notch formed in the end of the trip-lever 8 that is remote from the hinge 9, the bimetal blade 10 and the trip-lever 8 thereby defining an overcentre arrangement bridging the spaced-apart V-notch mounting 11 and hinge 9.
  • the chassis moulding 7 is further formed with a member 12 defining a back stop for the trip-lever 8 in the cold condition of the bimetal, a member 13 defining a front stop for the trip-lever in the hot condition of the bimetal (this being the condition shown in Figure 1A), and a member 14 defining an abutment against which the bimetal works when it flexes under temperature change to move the overcentre bridge from its cold to its hot condition with a snap-action.
  • the main moulding 1 is formed with upper and lower chambers 15 and 16 respectively, the upper chamber 15 serving to accommodate the switch actuator assembly 4 and the lower chamber serving to accommodate the lower leaf spring 2 which carries a first switch contact, the insulator 3, and the upper leaf spring 5 which carries a co-operating second switch contact.
  • the switch is assembled by first introducing the lower leaf spring 2 into the lower chamber 16 of the main moulding 1 as shown in Figure 1C, then introducing the insulator 3 as shown in Figure 1D, then inserting the switch actuator sub-assembly 4 into the upper chamber 15 as shown in Figure 1E, then introducing the upper leaf spring 5 into the lower chamber 16 as shown in Figure 1F, and finally snap-fitting the closure moulding 6 into the lower chamber 16.
  • the main moulding 1 and the closure moulding 6 have formations which engage lugs 17 that are provided on opposite sides of the trip-lever 8 (only one can be seen in Figure 1A) and trap the switch actuator sub-assembly 4 so that the trip-lever cannot move but the remainder of the chassis moulding 7 can pivot about the hinge 9, and a post 18 is provided on the chassis moulding 7 (as can be seen most clearly in Figure 1E) and extends in the assembled switch between the contact carrying parts of the leaf spring 2 and 5.
  • a second embodiment of the present invention is shown therein and comprises a main switch moulding 20, a switch sub-assembly comprising two identical contact-carrying leaf springs 21 and 22 staked to an insulator 23, a switch actuator assembly 24 comprising a moulded plastics chassis 25 formed with an integral trip-lever 26 hingedly coupled thereto and a bimetal (not shown) mounted in the chassis moulding and defining with the trip-lever 26 an overcentre bridge arrangement as in the first described embodiment, and a lid 27 for the main moulding 20.
  • chassis moulding 25 in the second embodiment is different to that of the first embodiment, it is nonetheless functionally identical in so far as the operation of the overcentre bridge arrangement is concerned, and the arrangement and operation of the bridge arrangement in the second embodiment will not be further described herein. It is however to be noted that the chassis moulding 25 is formed with a switch-operating projection 128 the function of which will be described hereinafter.
  • the main moulding 20 is formed with a mounting chamber 28 for the switch sub-assembly which fits into the chamber 28 in the manner shown in Figure 2C, the insulator 23 having grooved portions 29 which engage in a slot 30 formed in the wall portion 31 of the main moulding which defines the chamber 28, and there being an upstand 32 formed on the main moulding 20 within the chamber 28 behind which lodges an ear portion 33 of the leaf spring 21.
  • the insertion of the switch sub-assembly into the chamber 28 of the main moulding 20 defines the contact carried by leaf spring 21 as the fixed switch contact of the switch and the contact carried by leaf spring 22 as the moving contact.
  • the trip-lever 26 of the chassis moulding 25 is formed with a pair of lugs 34 one of which can be seen in Figure 2A and the other being on the opposite side of the trip-lever.
  • the main moulding 20 has an aperture 35 on the rear wall thereof, and this aperture is designed to receive therein one of the lugs 34 of the trip-lever 26 when the chassis moulding 25 is fitted to the main moulding 20 in the manner shown in Figure 2D, the trip-lever 26 slotting into the slot 36 defined between the projecting portions 37 and 38 of the main moulding 20.
  • the trip lever 26 becomes fixedly mounted with respect to the main moulding 20 whilst the remainder of the chassis moulding 25 is free to pivot about its hinged coupling with the trip-lever 26.
  • the projection 128 on the back of the chassis moulding 25 extends into an aperture 39 in the wall 31 of the enclosure 28 of the main moulding and, by-passing the leaf spring 21, extends into contact with the ear 40 of leaf spring 22.
  • the cold condition position of the chassis moulding 25 is shown full line in Figure 2D and the position to which it moves in response to movement of the overcentre bridge into its hot condition is shown in phantom; it can be seen that in the hot position of the chassis moulding 25 the projection 128 pushes upon the leaf spring 22 and opens its carried contact from the contact on the leaf spring 21.
  • Figure 2E shows the lid 27 fitted onto the main moulding 20 and shows the position of the chassis moulding 25 in the contacts closed (cold) condition of the switch
  • Figure 2F shows the device in its contacts open (hot) condition
  • Figure 2G is a side elevation view of the switch as shown in Figure 2F.
  • a reset knob could, if desired, be affixed to the upper part of the chassis moulding 25 where it extends out of the main moulding 20 for enabling manual resetting of the switch.
  • the trip-lever is integrally formed with the chassis moulding and coupled thereto by means of a plastics hinge portion.
  • this arrangement may not be preferred for certain applications and in the following an alternative embodiment will be described wherein the trip-lever is not integral with the chassis moulding.
  • the device shown therein comprises a steam sensing module which is designed to be plugged into an element protector unit, that is to say a unit for protecting the electrically powered heating element of a water boiling vessel from overheating, so as to convert the unit additionally into a steam sensing unit for automatically switching off the heating element when water boils within the vessel.
  • an element protector unit that is to say a unit for protecting the electrically powered heating element of a water boiling vessel from overheating, so as to convert the unit additionally into a steam sensing unit for automatically switching off the heating element when water boils within the vessel.
  • the steam sensing module of Figures 3A to 3M comprises a switch sub-assembly 40 shown in assembled condition in Figure 3B and consisting of two identical contact-carrying leaf springs 41 and 42 staked to an insulator 43 shown in Figure 3A, a main moulding 44 shown in perspective in Figure 3C, a trip-lever 45 shown in various stages of assembly with the main moulding 44 in the perspective views of Figures 3F, 3G and 3H, and a bimetal blade 46 shown in Figure 3H.
  • the main moulding 44 is formed with a chamber 47 which accommodates the assembled switch sub-assembly 40, the grooved parts 48 of the insulator 43 engaging with a slot 49 formed in the wall of the chamber (see Figure 3H) and a catch portion 50 of the insulator engaging with an aperture 51 formed in the main moulding 44 so as to lock the switch sub-assembly in position (see Figure 3E).
  • a wall portion 52 of the insulator 43 closes off the entrance to the chamber 47 and access to the interior of the chamber 47 is then provided only via the opening 53 defined in the chamber wall (see Figures 3C, 3D and 3F.
  • the opening 53 provides access to the chamber 47 for a projection formed on the trip-lever 45, such projection serving for applying switch-actuating movement from the trip-lever 45 to the switch sub-assembly 40.
  • a limb 54 extends from the main moulding 44 as shown in Figures 3C and 3D and is shaped to provide a knife edge pivotal mounting for the trip-lever 45 which, as can be seen in Figures 3F, 3G and 3H, has a part 55 adapted to be fitted over the limb 54 and to co-operate with the knife edge on the limb for pivotally mounting the trip-lever 45.
  • the trip-lever is adapted to be fitted onto the limb 54 of the main moulding 44 in the relative orientation of the two parts that is shown in Figure 3F and thereafter is rotating into the position shown in Figure 3G.
  • This rotation of the trip-lever 45 brings a peg 56 on the main moulding 44 into engagement with a groove 57 formed in the trip-lever so as to prevent the trip-lever from sliding off of the limb 54, and also causes the end of a projection 58 formed on the trip-lever (see Figure 3F) to enter the opening 53 providing access to the switch sub-assembly 40 housed within chamber 47 of the main moulding 44.
  • the trip-lever 45 has a V-notch mounting 59 formed therein for receiving one end of the bimetal blade 46 and an opposed V-notch mounting 60 for the other end of the bimetal blade 46 is provided on a part of the main moulding 44 and, with the trip-lever 45 rotated into the orientation relative to the main moulding 44 that is shown in Figure 3G, the bimetal 46 can be inserted into the two opposed V-notch mountings 59 and 60 as shown in Figure 3H. The assembly of the steam sensing module is then complete.
  • An upstand 61 on the trip-lever 45 merely comprises an attachment for a reset knob and has no other operational significance.
  • a post 62 (shown in Figure 3J) defines an abutment for the bimetal to work against when switching the overcentre bridge from its cold to its hot condition.
  • an element protection unit comprises a thermally-responsive switch arrangement which is adapted to be connected in series with the power supply line of an electrically powered heating element and serves to disconnect the heating element from the power supply line in the event of an overtemperature condition arising at the heating element, for example on account of the heating element being switched on when there is insufficient liquid in an associated vessel to absorb the heat output of the element or on account of the vessel being permitted to boil dry.
  • Exemplary element protection units are described in British Patent Specifications Nos.
  • an element protection unit commonly comprises live and neutral conductor leaf springs which contact the cold tails of a heating element when the protector unit is fitted to the head of the heating element and serve for conveying electrical power from power supply terminal pins of the element protection unit to the heating element, a switch arrangement in the neutral side at least of the power supply line to the heating element and comprising a leaf spring carrying a contact normally biassed into electrical engagement with a contact provided on a portion of the neutral conductor leaf spring and movable out of contact therewith for opening the switch, a push rod for applying switch-operating movement to such movable contact, and a bimetallic switch-actuating element which is arranged to be in close thermal contact with the heating element head plate when the element protection unit is coupled thereto and which, in response to the heating element temperature increasing above a predetermined normal level,
  • Element protection units are known which provide only a single level of protection, and other element protection units are known which provide a primary protection and an additional back-up or secondary protection operative in the event of failure of the primary protection.
  • the steam sensing device of the present invention can in principle be used with any kind of element protection unit, and the embodiment hereinafter described is particularly (though not exclusively) adapted for use with an element protection unit as described in our British Patent Specification No. 2194099 with reference to Figures 3A, 3B and 3C thereof so as to extend the element overtemperature sensing facility of the element protection unit to the provision also of steam sensing facilities.
  • the same element protection unit can therefore be associated with the heating elements of simple electric kettles, for example, and can also be used with fully automatic kettles which switch off when they boil.
  • the element protector as shown comprises a sub-assembly 20 (the same reference numerals will be used herein as are used in our British Patent Specification No. 2194099 to denote like parts) comprising a collapsible carrier 21, a bimetal blade 22 and a push rod 23, the sub-assembly 20 being adapted to locate in use of the element protector between the rear face of the heating element head 24 and the outer side of an inner moulding 25 of the element protector.
  • a sub-assembly 20 (the same reference numerals will be used herein as are used in our British Patent Specification No. 2194099 to denote like parts) comprising a collapsible carrier 21, a bimetal blade 22 and a push rod 23, the sub-assembly 20 being adapted to locate in use of the element protector between the rear face of the heating element head 24 and the outer side of an inner moulding 25 of the element protector.
  • the inner moulding 25 is adapted to co-operate with a main moulding 26 defining a socket inlet 27 for a kettle connector plug so as to define within the assembled control a chamber for accommodating the L,N and E terminal pins 28, 29 and 30 of the control and for accommodating a contact carrying live (L) connecting spring 31, a contact carrying live leaf spring 32, a neutral (N) connecting spring 33 and an earth (E) connecting spring 34.
  • the inner moulding 25 is adapted to be clipped to the main moulding 26 and has a pair of integrally-formed moulded spring clips 36 which co-operate with a pair of apertures 37 in the main moulding so that the inner moulding 25 makes a positive fit into the mouth of the main moulding 26 and is positively retained therein by the clips 36.
  • Upstands are formed on the inner face of inner moulding 25 (that is the face that can be seen in Figure 4A) and co-operate with formations provided on the opposed face of the main moulding 26 (that is the face that can be seen in Figure 4B) for retaining the L,N and E terminal pins 28, 29 and 30 securely in the assembled control, the terminal pins extending through respective apertures provided within the socket inlet part 27 of the main moulding 26, and in similar fashion the live connecting spring 31, the live leaf spring 32 and the neutral connecting spring 33 are trapped between the inner moulding 25 and the main moulding 26 when the two are assembled together.
  • the earth connecting spring 34 is adapted to affix to the upstand 41 provided on the element head 24 when the element protector is fully assembled and is attached to the element head and, within the element protector, makes contact with the earth terminal pin 30.
  • the bimetallic blade 22 is generally rectangular with a central cut-out 42 of generally X-shaped configuration and is dished so as to be capable of moving with a snap action between two oppositely dished configurations, the X-shaped cut-out 42 ensuring a substantially greater operating movement at the centre of the bimetal than would be provided by a plain dished blade.
  • the bimetallic blade 22 is retained in the sub-assembly 20 by means of the engagement of the push rod 23 both with the central cut-out 42 of the blade 22 and with the collapsible carrier 21, the push rod 23 being adapted to be inserted into a guide passage 45 formed in the carrier 21 from the side thereof which can be seen in Figure 1A, but being incapable of passing completely through the guide passage 45, and having a nose portion adapted to be engaged in the centre of the cut-out 42 in the bimetal blade 22.
  • the position of the opposite, pusher end of the push rod 23 relative to the carrier 21 will be dependent upon whether the bimetal 22 is its hot or its cold state.
  • the carrier 21 is generally in the form of a four-legged table and has relatively large feet 46 for ensuring good thermal contact with the rear face of the heating element head 24 when the assembled element protector is affixed to the element head.
  • the bimetallic blade 22 seats at its corners on the ends of the four legs of the carrier, flush with the soles of the feet 46.
  • a pair of locating grooves 48 are provided in the carrier 21 and the inner moulding 25 is provided on its outer face with a pair of upstanding rails 49 adapted to slidingly engage in the grooves 48.
  • the carrier 21 On its upper surface, as shown in Figure 1A, the carrier 21 has four upstanding posts designed to project through an aperture provided in the inner moulding 25, there being two small posts 51 and two larger posts 52 and 53.
  • the heating element cold tails 54 and 55 (that is the terminal ends of the heating element proper) extend through apertures 56 and 57 provided in the inner moulding and contact the upper ends of the live connecting spring 31 and the neutral connecting spring 33 respectively, the upper end portions of the springs 31 and 33 being curved as shown for accommodating such contacts.
  • the heating element cold tails may be tipped with silver solder or may be provided with crimped ferrule terminations to enhance their connections with the leaf springs.
  • the lower end of the live connecting spring 31 extends across the aperture 50 of the inner moulding 25 and carries a contact which constitutes the "moving" contact of the switching contacts set of the element protector. This lower limb of the live connecting spring 31 is arranged to be abutted by the pusher end of the push rod 23 for moving the moving contact in response to switching of the bimetallic blade 22 into its "hot" condition from its normal "cold” condition.
  • the live leaf spring 32 is trapped between the inner and main mouldings 25 and 26 when the two are assembled together, and has a first, relatively-substantial limb 58 which extends across the aperture 50 formed in the inner moulding 25 and is contacted and urged away from the inner moulding 25 and towards the main moulding 26 by the large post 52 upstanding from the carrier 21, which causes the limb 58 of the live leaf spring 32 to be biassed into contact with the live terminal pin 28.
  • the live leaf spring 32 also has a second, less-substantial limb 59 which extends across the aperture 50 in the inner moulding 25 and carries at its free end a contact which cooperates with the "moving" contact provided on the live connecting spring 31 and constitutes the "fixed" contact of the switching contacts set.
  • the second limb 59 of the live leaf spring 32 is arranged to be contacted by the lowermost of the two small posts 51 provided on the carrier 21, such posts projecting through the aperture 50.
  • This contact between the lower post 51 and the limb 59 of the live leaf spring 32 establishes the position of the contact carried by the live leaf spring 31 (the "fixed” contact of the switching contacts set) relative to the carrier and thus relative to the push-rod, the bimetallic blade and the element head and establishes the position of the "fixed” contact relative to the element head irrespective of variations in the dimensions of the element head.
  • the neutral connecting spring 33 is trapped between the assembled mouldings 25 and 26 and has a relatively substantial limb 60 which extends across the aperture 50 and is butted by the post 53 on the carrier 21 into contact with the neutral terminal pin 29.
  • an element head overtemperature condition will normally cause bimetal 22 to snap to its hot configuration thereby causing the moving contact carried by live connecting spring 31 to be pushed away from the fixed contact carried by live leaf spring 32 by the push rod 23.
  • a secondary protection mode comes into operation when the temperature of the element head reaches such a high level as to cause the carrier 21 to collapse towards the element head by virtue of heat distortion of its legs under pressure from the spring parts 58 and 60 of the live and neutral leaf springs 32 and 33 respectively.
  • the collapse of the carrier 21 towards the element head 24 causes the leaf spring parts 58 and 60 to move out of contact with the live and neutral terminal pins 28 and 29 thereby disconnecting the heating element from its power supply.
  • Figure 5A shows a perspective view of a slightly modified form of the steam sensor main moulding 44 described hereinbefore with reference particularly to Figure 3C of the accompanying drawings, the principal modifications being the provision of a portion 100 for shielding the chamber 47 of the main moulding against the entry therein of steam condensate and the provision of an engaging portion 200 for positive engagement with an element protector.
  • the chamber 47 of the main moulding 44 is adapted to accommodate a switch sub-assembly 40 comprising contact-carrying leaf springs staked to an insulating body having a side wall portion 52 shaped to close off the entrance to the chamber 47 when the switch sub-assembly is fully engaged therein.
  • this lower part of the switch sub-assembly of the steam sensor is adapted to be plugged into a socket portion defined in an element protector as described with reference to Figures 4A and 4B hereof.
  • the main moulding 26 of the element protector is provided with an aperture 125 in its upper surface (see Figure 4A hereof) which provides access to the location within the element protector whereat, in use of the element protector on its own, that is to say without a steam sensor, the cold tail 55 of the heating element would contact the upper part of the neutral connecting spring 33.
  • FIG. 5C hereof which shows a modified form of the main moulding of the element protector
  • a structure 250 which is complementary to the engaging portion 200 of the steam sensor as shown in Figure 5B so that when the depending lower part of the switch sub-assembly 40 of the steam sensor is plugged into the aperture 125 in the top of the element protector the steam sensor will engage positively with the element protector as is shown in Figures 5D and 5E hereof.
  • the switch sub-assembly of the steam sensor is introduced between the cold tail 55 of the element head and the upper end of the neutral connecting spring 33 of the element protector whereby the steam sensor is placed electrically in series with the switching contacts set of the element protector.
  • the element protector may be used on its own in a variety of water boiling vessels exemplified in the drawing as a conventional kettle 301 and a jug type of vessel 302.
  • a steam sensor is shown plugged into the top of an element protector and the drawing schematically shows the combination assembled with the heating element of a conventional kettle 301 provided with an aperture for venting steam onto the steam sensor bimetal and alternatively assembled with the heating element of a jug type vessel 302 incorporating a steam duct for directing steam from the interior of the vessel to the location of the steam sensor where it is plugged into the element protector.
  • Figure 6C shows an alternative option whereby the steam sensor can be located spaced apart from the element protector and coupled thereto by means of an appropriate connecting lead having at one end thereof a plug type connector adapted to be plugged into the top of the element protector and at the other end thereof a socket type connector adapted to receive the plug type end portion of the steam sensor switch sub-assembly.
  • FIG. 7 Yet another way in which a steam sensor embodying the present invention can be utilized with the element protector is described with reference to Figures 7 and 8 of the accompanying drawings.
  • the element protector shown is a modification of the element protector illustrated in Figures 5A and 5B of the accompanying drawings and similar or common parts bear the same reference numerals as are used in Figures 5A and 5B.
  • the view of the element protector shown in Figure 7 is a view into the open face of the main moulding 26 with the contact carrying live connecting spring 31, the contact carrying line leaf spring 32, and the neutral connecting spring 33 assembled with the main moulding.
  • the heating element cold tails butt against the upper parts of the leaf springs 31 and 33, that is to say the parts which are shown uppermost in Figure 7 of the accompanying drawings, and the parts 58 and 60 of the leaf springs 32 and 33 respectively are urged into contact with the live and neutral terminal pins by the action of the posts 52 and 53 provided on the rear of the collapsible carrier.
  • the contacts provided on the leaf springs 31 and 32 are closed so as to permit current flow through the heating element, but in an element overtemperature condition, caused for example by the vessel being switched on empty, the lower part of leaf spring 31 is pushed by the push rod mounted in the collapsible carrier, pursuant to operation of the bimetal, so as to open the normally closed contacts. If the element overtemperature condition persists, for example on account of the contacts welding together, then a secondary protection will come into play when the collapsible carrier begins to melt thereby releasing the connections made between the leaf springs 32 and 33 and the power supply terminal pins.
  • the leaf spring 31 has a portion 311 which acts as a torsion arm enabling rotation of the portion 312 which carries the contact, and an abutment portion 313 is provided which cooperates with a movable slider 314 to determine the position in the element protector of the contact carried by the leaf spring 31.
  • This arrangement is schematically illustrated in Figure 8 and it will be appreciated from Figure 8 that when slider 314 is in its forward position, it abuts portion 313 of leaf spring 31 and causes a rotation of the portion 312 about torsion arm portion 311 thereby bringing the contact carried at the lowermost end of leaf spring 31 into a position for contacting the contact carried by leaf spring 32.
  • slider 314 is in its rearward position (as shown in Figure 8) however, the contact carried by leaf spring 31 does not make contact with the contact carried by leaf spring 32.
  • the slider 314 is mounted within a coupling member 315 for reciprocatory movement therein, and the coupling member is adapted to be plugged into an opening provided for the purpose in the top of the element protector and to make a snap fit therein.
  • the movement of the slider 314 within the coupling member 315 is determined by the steam sensor as described hereinafter such that when the steam sensor operates in response to the generation of steam when water boils within the vessel the slider is withdrawn to its rearward position thereby permitting the contacts to break and switching off the heating element.
  • the steam sensor comprises a moulding 44 formed with a limb 54 which provides a knife edge pivotal mounting for one end of a trip lever 45, and the other end of the trip lever 45 has a V-notch mounting for receiving one end of a bimetal blade 46, the other end of the bimetal blade 46 being received in an opposed V-notch formed in a spring metal reinforcing part 320 captured in the moulding 44 behind the post 321.
  • the bimetal 46 and trip lever 45 together constitute an articulated member which is movable with a snap action between two stable conditions upon exposure of the bimetal to an appropriate high temperature, namely the temperature of steam generated when water boils in an associated vessel.
  • the trip lever 45 is secured to one end of the core wire of a Bowden cable 325 and the corresponding end of the outer sheath of the cable is secured to the moulding 44.
  • the core wire is connected to the slider 314 and the outer sheath is connected to the coupling member 315.
  • the contact carried by the lower end of leaf spring 32 is thus a "fixed” contact and the contact carried by the lower end of leaf spring 31 is a "movable” contact the position of which is dependent upon both the condition of the steam sensor and the condition of the element protector.
  • This arrangement is exemplary only and it could alternatively be arranged, for example that both contacts were “movable” with the position of one contact determined by the steam sensor and the position of the other contact determined by the element protector. It could furthermore be arranged that separate sets of switching contacts were provided in the element protector, one to be controlled by the element protector per se and the other to be controlled by the steam sensor per se.
  • the element protector could, for example, be designed such that when used with an electrical input from the steam sensor (in the manner described herein with reference to Figures 5A to 5E for example) a dummy coupling member 315 is plugged into the element protector to bias the contact spring 31 into an appropriate position.
  • one end of the bimetal blade 46 is received in a V-notch formed in a spring metal reinforcing part 320 captured in the moulding 44 behind the post 321. It would be preferable to avoid use of the spring metal reinforcing part 320 but, on account of difficulties that we have encountered in finding a plastics material for the moulding 44 which will provide a compliance mounting for the bimetal without also being subject to mechanical creepage as it ages, the provision of the spring metal part 320 has provided an elegant solution to the problem of providing a compliant mounting for the bimetal.
  • a steam sensing switch or a device suitable for use in or as a steam sensing switch, which has various advantages.
  • the form of the device allows for free access of steam to the bimetal before operation which permits rapid response of the device, and, in some of the described embodiments, will allow obstruction to the passage of steam after operation which permits the device to be reset more readily than with existing devices.
  • the described embodiments utilize a low number of component parts, as compared to conventional devices, and, even in those embodiments such as that of Figures 3A to 3M for example which employ relatively complex mouldings, are of simple construction leading to the promise of more readily achieved automatic assembly, and furthermore promise to be effective and efficient in long term operation by virtue inter alia of the elimination of the high stress levels that are normally present in conventional bistable bimetallic actuators and can lead to fatigue failure.
  • the abutment 14 and/or the members 12,13 defining back and front stops for the trip lever could be adjustable, for example by use of set screws in appropriate positions or by use of separately moulded and adjustably positionable click-fit moulding parts.
  • a one piece moulding is advantageous from the viewpoint of simplicity and calibration by bimetal characteristics selection is perfectly feasible, but it is to be well understood that the invention extends to alternative means of achieving calibration.
  • the invention as described provides steam sensor and element protection units which can be used individually if required, and also can be combined together with the steam sensor plugging into the element protector or with an electrical lead or a mechanical movement transmitting device such as a Bowden cable operatively interconnecting the two.
  • the steam sensor and the element protector each takes a specific form, the invention is capable of wider application and not only could various modifications be made to the embodiments described without departing from the scope of the invention, but also different forms of steam sensor and element protector units could be adapted to couple together in accordance with the teachings hereof.

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

Claims (20)

  1. Auf Wärme ansprechender Bimetall-Schnappbetätigungsmechanismus zum Entwickeln einer Betätigungsbewegung in Abhängigkeit von einer Temperaturänderung, wobei der genannte Betätigungsmechanismus einen Rahmen (7; 25; 44) aus abgeformtem Kunststoffmaterial, eine Bimetallzunge (10; 46) und einen Auslösehebel (8; 26; 45) aus geformtem Kunststoff aufweist, dadurch gekennzeichnet, daß die Bimetallzunge und der Auslösehebel schwenkbar in gegenseitiger Reihenanordnung zwischen zwei mit Abstand angeordneten, gegenüberliegenden Halterungen (9, 11; 54, 60) angebracht sind, die im genannten Rahmen so festgelegt sind, daß eine abgefederte Überspringverbindung gebildet ist, die durch einen Schnappvorgang zwischen zwei stabilen Lagen auf den gegenüberliegenden Seiten einer unstabilen Zwischenlage beweglich ist, wobei der Auslösehebel (8; 26; 45) einen Endabschnitt aufweist, der ein Ende der Überspringverbindung bildet und schwenkbar hinsichtlich des genannten Rahmens an der einen der genannten Halterungen (9; 54) angebracht ist, die Bimetallzunge (10; 46) einen Endabschnitt aufweist, der das andere Ende der Überspringverbindung bildet und schwenkbar hinsichtlich des genannten Rahmens an der anderen der genannten Halterungen (11; 60) angebracht ist, die Bimetallzungen (10; 46) und der Auslösehebel (8; 26; 45) jeweils einen anderen Endabschnitt aufweisen, an dem der Auslösehebel und die Bimetallzunge schwenkbar ineinander an einer Mittellage der Überspringverbindung eingreifen, und ein Anschlag (14; 62) im Rahmen (7; 25; 44) vorgesehen ist, gegen welchen die Bimetallzunge (10; 46) bei ihrer Entwicklung der Kraft einwirkt, die erforderlich ist, um die Überspringverbindung zu veranlassen, sich zwischen ihren beiden stabilen Lagen zu bewegen, und wobei die Anordnung der genannten Überspringverbindung hierdurch so ist, daß in Abhängigkeit von einer vorbestimmten Temperaturänderung der Bitmetallstreifen (10; 46) selbst die Federkraft erzeugen wird, die erforderlich ist, um die Überspringverbindung zu veranlassen, sich mit einem Schnappvorgang über die Mitte hinaus zu bewegen, und eine solche Überspringbewegung der Verbindung die relative Schwenkbewegung zwischen dem Auslösehebel (8; 26; 45) und dem Rahmen (7; 25; 44) nach sich zieht, welche die Arbeitsbewegung der Betätigungseinrichtung bilden.
  2. Auf Wärme ansprechende Bimetall-Schnappbetätigungseinrichtung nach Anspruch 1, worin der genannte Anschlag (14; 62) einstellbar ist.
  3. Auf Wärme ansprechende Bimetall-Schnappbetätigungseinrichtung nach Anspruch 1 oder 2, worin der Rahmen (7) aus geformtem Kunststoffmaterial Anschlagabschnitte (12, 13) aufweist, die jeweils vorbestimmte, stabile Lagen des genannten Auslösehebels (8) für den kalten Zustand und warmen Zustand relativ zum genannten Rahmen (7) festlegen, wobei die Betätigungseinrichtung hierdurch in vorbestimmter Weise bistabil ist.
  4. Auf Wärme ansprechende Bimetall-Schnappbetätigungseinrichtung nach Anspruch 1, 2 oder 3, worin jener Endabschnitt der Bitmetallzunge (46), der in Schwenkeingriff mit dem Auslösehebel (45) steht, schwenkbar in einer V-Kerbe (59) aufgenommen ist, die am Ende des Auslösehebels an der genannten Zwischenlage in der Überspringverbindung ausgebildet ist.
  5. Auf Wärme ansprechende Bimetall-Schnappbetätigungseinrichtung nach irgendeinem der vorangehenden Ansprüche, worin der genannte eine Endabschnitt der Bimetallzunge (10) in einer Schwenkhalterung (11) mit einer V-Kerbe im Rahmen (7) aufgenommen ist.
  6. Auf Wärme ansprechende Bimetall-Schnappbetätigungseinrichtung nach irgendeinem der vorangehenden Ansprüche, worin der Auslösehebel (8; 26) aus geformtem Kunststoffmaterial einstückig mit dem genannten Rahmen (7; 25) aus geformtem Kunststoffmaterial ausgebildet ist und schwenkbar hieran mittels eines einstückig geformten, flexiblen Kunststoffmaterial-Scharnierabschnitts angebracht ist.
  7. Auf Wärme ansprechende Bimetall-Schnappbetätigungseinrichtung nach irgendeinem der Ansprüche 1 bis 5, worin der Auslösehebel (45) aus geformtem Kunststoffmaterial und der Rahmen (44) aus geformtem Kunststoffmaterial mittels einer Messerschneidenkupplung (54, 55) schwenkbar aneinander angebracht sind.
  8. Auf Wärme ansprechende Bimetall-Schnappbetätigungseinrichtung nach irgendeinem der vorangehenden Ansprüche, worin die Anordnung der Überspringverbindung in den beiden genannten, mit Abstand angeordneten, gegenüberliegenden Halterungen (9, 11; 54, 60) nachgiebig ist, um die Überspringbewegung der Überspringverbindung aufzunehmen.
  9. Auf Wärme ansprechende Bimetall-Schnappbetätigungseinrichtung nach Anspruch 8, worin die erforderliche Nachgiebigkeit mindestens teilweise dank des Kunststoffmaterials des genannten Rahmens (7; 25) vorgesehen ist, das eine geeignete, inhärente Flexibilität aufweist.
  10. Auf Wärme ansprechende Bimetall-Schnappbetätigungseinrichtung nach Anspruch 8, worin die erforderliche Nachgiebigkeit dank der Tatsache vorgesehen ist, daß eine der genannten Halterungen von einem nachgiebigen Federmetallelement (320) im genannten Rahmen (44) gebildet ist.
  11. Auf Wärme ansprechende Bimetall-Schnappbetätigungseinrichtung nach irgendeinem der vorangehenden Ansprüche, worin die Bimetallzunge (10; 46) der Überspringverbindung nicht ihrerseits selbst eine Schnappwirkung aufweist und eine einfache, rechteckige Bimetallzunge umfaßt.
  12. Elektrischer Schalter, der in Kombination eine auf Wärme ansprechende Bimetall-Schnappbetätigungseinrichtung nach irgendeinem der vorangehenden Ansprüche sowie elektrische Schalterbestandteile (2, 5; 21, 22; 41, 42) aufweist, wobei die Kombination so getroffen ist, daß die Lage der Überspringverbindung der Betätigungseinrichtung den Zustand der elektrischen Schalterbestandteile bestimmt.
  13. Elektrischer Schalter nach Anspruch 12, worin der genannte Rahmen (44) aus geformtem Kunststoffmaterial ein erstes Abteil zur Aufnahme der genannten Überspringverbindung und ein zweites Abteil (47) zur Aufnahme einer Schalter-Unterbaugruppe (40) aufweist, die die genannten Schalterbestandteile (41, 42) umfaßt, wobei eine solche Anordnung getroffen ist, daß dann, wenn die genannte Überspringverbindung und die genannte Schalter-Unterbaugruppe in den genannten Abteilen eingebaut sind, der Auslösehebel (45) der Verbindung mit der genannten Schalter-Unterbaugruppe (40) zur Schalterbetätigung zusammenwirkt.
  14. Elektrischer Schalter nach Anspruch 13, worin der Auslösehebel (45) mit einem Schalterbetätigungsabschnitt (58) ausgebildet ist, der sich in das genannte zweite Abteil (47) hinein erstreckt und zur Zusammenwirkung mit der Schalter-Unterbaugruppe (40) zur Betätigung des Schalters angeordnet ist.
  15. Elektrischer Schalter nach Anspruch 13 oder 14, der einen elektrischen Anschlußabschnitt (40) umfaßt, der dazu eingerichtet ist, mit einem komplementären Anschluß nach Art eines Steckers und einer Steckdose zusammenzuwirken, wobei Schalteranschlüsse (41, 42) im genannten Anschlußabschnitt vorgesehen sind, die dazu eingerichtet sind, elektrische Verbindungen mit dem genannten komplementären Anschluß herzustellen.
  16. Elektrischer Schalter nach Anspruch 15, worin der elektrische Anschlußabschnitt (40) des Schalters als Einsteckabschnitt ausgebildet ist, der dazu eingerichtet ist, in einer komplementären Steckfassung aufgenommen zu werden.
  17. Elektrischer Schalter nach Anspruch 15 oder 16, der eingerichtet ist zur Verwendung als ein Dampffühler zusammen mit einem elektrisch beheizten Wasserkochgefäß, und worin der genannte elektrische Anschlußabschnitt (40) zur Zusammenwirkung mit einem komplementären Anschluß (125) eines Elementenschutzes des Gefäßes eingerichtet ist, der vorgesehen ist, um die Stromversorgung zum Gefäß-Heizelement im Fall eines gemessenen Element-Übertemperaturzustandes auszuschalten, wobei die Wirkung der Verbindung des elektrischen Anschlußabschnitts des Dampffühlers mit dem komplementären Anschluß des Elementschutzes so angeordnet ist, daß der elektrischen Schaltkreis des Dampffühlers in eine Stromversorgungsleitung eingeschleift wird, die sich durch den Elementenschutz erstreckt.
  18. Elektrisch beheiztes Wasserkochgefäß mit einem elektrischen Schalter nach irgendeinem der Ansprüche 12 bis 16, der betrieblich dessen mit elektrischem Strom versorgten Heizelement zugeordnet ist.
  19. Elektrisch beheiztes Wasserkochgefäß nach Anspruch 18, wobei der genannte elektrische Schalter dazu eingerichtet ist, als Dampffühler zu arbeiten, um die Versorgung elektrischen Stroms zum Heizelement des Gefäßes zu beenden, wenn Wasser im Gefäß kocht.
  20. Elektrisch beheiztes Wasserkochgefäß nach Anspruch 19, worin ein Elementenschutz dem Heizelement des Gefäßes zugeordnet ist, um die Versorgung elektrischen Stromes zu diesem im Fall des Überhitzens des elektrischen Heizelementes auszuschalten.
EP19880311081 1987-11-23 1988-11-23 Temperatur emfindliche elektrische Schalter Expired - Lifetime EP0318265B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88311081T ATE101452T1 (de) 1987-11-23 1988-11-23 Temperatur emfindliche elektrische schalter.

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
GB8727412 1987-11-23
GB878727412A GB8727412D0 (en) 1987-11-23 1987-11-23 Thermally responsive electric switches
GB888801438A GB8801438D0 (en) 1988-01-22 1988-01-22 Improvements relating to thermally-responsive electric switches
GB8801438 1988-01-22
GB888810506A GB8810506D0 (en) 1988-05-04 1988-05-04 Improvements relating to thermally-responsive electric switches
GB8810506 1988-05-04

Publications (3)

Publication Number Publication Date
EP0318265A2 EP0318265A2 (de) 1989-05-31
EP0318265A3 EP0318265A3 (en) 1989-10-18
EP0318265B1 true EP0318265B1 (de) 1994-02-09

Family

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EP19880311081 Expired - Lifetime EP0318265B1 (de) 1987-11-23 1988-11-23 Temperatur emfindliche elektrische Schalter

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EP (1) EP0318265B1 (de)
AU (1) AU634927B2 (de)
DE (1) DE3887734T2 (de)
GB (1) GB2212664B (de)
HK (3) HK171095A (de)
NZ (1) NZ227060A (de)

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GB2235257B (en) * 1989-08-24 1993-08-25 Otter Controls Ltd Improvements relating to thermally responsive electric switches
GB9101028D0 (en) * 1991-01-17 1991-02-27 Strix Ltd Liquid boiling vessels
GB9114247D0 (en) * 1991-07-02 1991-08-21 Otter Controls Ltd Improvements relating to thermally-responsive controls
GB2315161B (en) * 1996-07-10 2000-10-11 Otter Controls Ltd Improvements relating to thermally responsive electric switches
GB9710096D0 (en) 1997-05-19 1997-07-09 Otter Controls Ltd Improvements relating to electrical heating elements
GB2333901B (en) 1997-09-25 2000-06-14 Otter Controls Ltd Improvements relating to electrically heated water boiling vessels
GB2363908B (en) * 1997-11-28 2002-03-06 Otter Controls Ltd Improvements relating to thermally-responsive actuators
GB9816645D0 (en) 1998-07-30 1998-09-30 Otter Controls Ltd Improvements relating to electrically heated water boiling vessels
GB2378818B (en) 1999-02-11 2003-06-11 Otter Controls Ltd Improvements relating to control of electric heating elements
GB0316037D0 (en) * 2003-07-08 2003-08-13 Otter Controls Ltd Improvements relating to thermal control units

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GB8502170D0 (en) * 1985-01-29 1985-02-27 Strix Ltd Thermally-sensitive controls

Also Published As

Publication number Publication date
EP0318265A3 (en) 1989-10-18
AU617379B2 (en) 1991-11-28
HK171195A (en) 1995-11-17
DE3887734D1 (de) 1994-03-24
EP0318265A2 (de) 1989-05-31
HK171095A (en) 1995-11-17
AU1059892A (en) 1992-04-16
GB2212664B (en) 1992-07-08
AU2581288A (en) 1989-05-25
AU634927B2 (en) 1993-03-04
HK176995A (en) 1995-12-01
DE3887734T2 (de) 1994-05-19
GB8827340D0 (en) 1988-12-29
NZ227060A (en) 1991-03-26
GB2212664A (en) 1989-07-26

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