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WO1993001640A1 - Ameliorations concernant les dispositifs de securite reagissant a la chaleur - Google Patents

Ameliorations concernant les dispositifs de securite reagissant a la chaleur Download PDF

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Publication number
WO1993001640A1
WO1993001640A1 PCT/GB1992/001197 GB9201197W WO9301640A1 WO 1993001640 A1 WO1993001640 A1 WO 1993001640A1 GB 9201197 W GB9201197 W GB 9201197W WO 9301640 A1 WO9301640 A1 WO 9301640A1
Authority
WO
WIPO (PCT)
Prior art keywords
switch
thermally
responsive
combination
appliance
Prior art date
Application number
PCT/GB1992/001197
Other languages
English (en)
Inventor
Robert Andrew O'neill
Robert Henry Hadfield
Original Assignee
Otter Controls Limited
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 Limited filed Critical Otter Controls Limited
Priority to GB9326570A priority Critical patent/GB2273007B/en
Publication of WO1993001640A1 publication Critical patent/WO1993001640A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
    • H02H5/04—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature
    • H02H5/047—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature using a temperature responsive switch
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/12—Means for adjustment of "on" or "off" operating temperature
    • H01H37/14—Means for adjustment of "on" or "off" operating temperature by anticipatory electric heater
    • 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
    • H01H61/00—Electrothermal relays
    • H01H61/02—Electrothermal relays wherein the thermally-sensitive member is heated indirectly, e.g. resistively, inductively

Definitions

  • the present invention generally concerns improvements relating to thermally-responsive controls and more particularly concerns controls for electrical apparatuses including domestic appliances such as washing machines, tumble driers, dishwashers and central heating or air conditioning apparatus and other industrial and business premises equipment where it is commonplace to protect the equipment against overheating by provision of thermal sensors at strategic locations within the equipment and arranging for the apparatus to be disabled or an alarm indication otherwise given in the event of a sensed over-temperature situation.
  • electrical apparatuses including domestic appliances such as washing machines, tumble driers, dishwashers and central heating or air conditioning apparatus and other industrial and business premises equipment where it is commonplace to protect the equipment against overheating by provision of thermal sensors at strategic locations within the equipment and arranging for the apparatus to be disabled or an alarm indication otherwise given in the event of a sensed over-temperature situation.
  • the principal object of the present invention is to enable the abovedescribed problem of conventional arrangements to be overcome or at least substantially reduced.
  • the present invention in one of its aspects provides a thermal relay comprising a thermally-responsive electrical switch having stable on and off conditions between which it can be operated manually, particularly for resetting the switch, and a heater associated with a thermally-responsive actuating element of the switch such as to cause the switch to adopt its off condition after a time delay following energization of the heater.
  • Such a thermal relay might for example be utilized in a situation where the operation of the heater is determined by an automatically resetting thermostatic switch located within an apparatus at a position which is inaccessible for manual resetting.
  • an overtemperature situation arising within the apparatus such as to cause the thermostatic switch to operate will result in the heater being energised so as to cause the thermally-responsive switch to go open circuit.
  • the apparatus will then remain inoperative until such time as the thermostatic switch cools and resets and the thermally-responsive switch is manually reset.
  • a plurality of thermostatic switches might be provided at different potential "hot spot" locations in the apparatus, such thermostatic switches being connected electrically in series.
  • the thermally-responsive switch can be located at any convenient position to be accessible for manual operation, and may advantageously be arranged such that its status is clearly visible and/or otherwise noticeable.
  • One such application is in domestic laundry equipment for example, where automatically resetting thermal cut-outs may be situated at the most advantageous positions within the apparatus without regard to the need to provide a manual reset facility.
  • a plurality of such thermal cut-outs may be connected in series, with the heating element connected overall in parallel with the series connected cut-outs, such that when any one of the cut-outs opens its contacts a voltage will be applied to the heating element so as to energize the same and, after a time delay, cause the thermally-responsive switch to operate.
  • the water heater, air heater, and all electric motors provided in the appliance may be individually protected by suitable auto-reset thermal cut-outs, and operation of any one of the thermal cut-outs would cause the thermally- responsive switch to operate, such switch typically constituting the main on/off switch of the apparatus.
  • the apparatus would be resettable simply by manual operation of the thermally-responsive switch after an appropriate cooling down period (and after correction of any fault condition) , the thermal capacity of the system, and particularly of the heater and the actuator of the thermally-responsive switch, ensuring that a suitable time delay occurs before the apparatus can be switched on again.
  • advantage might specifically be taken of the delay which occurs between energization of the heating element and consequent operation of the thermally-responsive switch.
  • the subject thermal relay might provide a timed switch-off in the event of the machine being left switched on overnight.
  • the heating element of the thermally-responsive switch might be connected in parallel with the contact thermostat which typically controls the temperature of the coffee pot heater plate.
  • the cycle time of this thermostat is typically of the order of 15 to 30 minutes and the temperature setting is typically somewhat above 100°C.
  • the thermostat normally operates if the coffee pot is removed, or is empty or nearly so.
  • the heating element associated with the thermally-responsive switch would be energized when the thermostat contacts open.
  • thermal relay of the described kind might for example comprise the protection of a number of zones in a convection heater to protect against partial blockage of the heater vents by clothes, or the protection of central heating boilers where thermal cut-outs may be required to be positioned at several inaccessible areas and the provision of a manual reset facility is conventionally difficult.
  • An advantageous form of thermally-responsive electrical switch that may be utilized in the practice of the present invention by modification to incorporate a heating element is described in our British Patent Specification No. GB 2212664A with reference to Figs. 3A to 3M or Figs. 9A and 9B. This switch is marketed by Otter Controls Ltd.
  • the biassing of a bimetallic switch actuator is adjustable by adjustment of a rotary cam and this adjustment can be utilized to determine the operating characteristics of the switch.
  • the present invention is not restricted to use of the Jl switch.
  • the present invention extends additionally to a thermal relay as defined hereinbefore in combination with one or more thermally-responsive or other switches arranged to determine the state of energization of the heating element, and also extends to an apparatus or appliance incorporating one or more such combinations.
  • Fig. 1 is a schematic circuit diagram illustrating a situation wherein potential hot spots in an appliance are protected by thermal cut-outs which determine the operation of a thermal relay according to the present invention
  • Fig. 2 is a perspective view of a thermally-responsive electrical switch in accordance with the teachings of British Patent Specification No. GB 2212664A aforementioned, the switch as is shown schematically having a heating element mounted proximate its bimetallic actuator;
  • Fig. 3 is an exploded perspective view of the switch of Fig. 2 from the opposite side thereof and illustrating an exemplary form of carrier for the heating element;
  • Fig. 4 is a perspective view similar to Fig. 3 but showing the heating element and carrier assembled with the switch; and Figs. 5A, 5B and 5C are schematic circuit diagrams illustrating the use of a thermally- responsive switch as described in our British Patent Application No. 9208264.3 (Serial No. ) in an arrangement according to the present invention.
  • the circuitry of an electrically powered appliance 1 is protected by a plurality of series-connected, auto-reset thermal cut ⁇ outs 2 which can be of any convenient type such as a simple auto-reset bimetallic switch for example.
  • a thermally-responsive switch 3 is connected in series with the cut-outs 2 and a heating element 4 is connected in parallel with the cut-outs 2 and is arranged in heat transfer relationship with the thermally-responsive actuator of the switch 3.
  • the cut-outs 2 and switch 3 will all be in a contacts-closed condition and the heating element 4 will be short-circuited by the cut-outs 2.
  • the heating element 4 On the occurrence of a hot spot in the appliance such as to cause one or more of the cut ⁇ outs 2 to operate and adopt a contacts-open condition, the heating element 4 will be energized and will begin to heat the thermally-responsive switch 3 which, after a delay, will adopt its contacts-open condition. It will be noted that the appliance will continue to be powered via the heating element 4 after one or more of the cut-outs 2 have gone open circuit and until the switch 3 operates, but any such continued powering of the appliance will be at a reduced level and will be only temporary.
  • the thermally-responsive switch 3 having operated, its condition will be readily noticeable by virtue of its being provided with a conspicuous ON-OFF knob for example.
  • the appliance will then remain inoperative until such time as the one or more cut ⁇ outs 2 responsible for the shut-down of the appliance cool and reset and until the switch 3 is manually reset. If there is a fault condition in the appliance, then the reconnection of the appliance would once again cause a cut-out to operate thereby once again switching off the appliance, and this would be the case until the fault was corrected.
  • Figs. 2, 3 and 4 are perspective views of a modified form of the Jl switch which is described in GB 2212664A aforementioned, and a full understanding of the construction and operation of such a switch can be obtained by reading GB 2212664A.
  • the switch it is sufficient to describe the switch as comprising a plastics moulding 10 defining spaced- apart mountings for an overcentre arrangement consisting of a bimetal blade 11 and a trip lever 12, the bimetal blade 11 at its upper end (as viewed in Fig.
  • the bimetal 11 and trip lever 12 constitute a bridge which is movable overcentre between two stable positions defined by abutments provided in the moulding, and an extension of the trip lever 12 projects into a switch compartment of the moulding within which there is mounted a set of switch contacts arranged to be opened and closed in dependence upon the condition of the overcentre bridge.
  • a further portion 14 of the trip lever 12 serves as a convenient mounting for an on/off knob which not only provides for manual operation of the switch but also provides an indication of the status of the switch.
  • a heating element 4 which can take any convenient form, but may for example comprise a thin film resistor which may be mounted in a moulding (not shown) adapted to be fitted to the main switch moulding 10 and advantageously incorporating spring terminals whereby the resistor can be readily changed for one of a different heat output.
  • a heating element which can take any convenient form, but may for example comprise a thin film resistor which may be mounted in a moulding (not shown) adapted to be fitted to the main switch moulding 10 and advantageously incorporating spring terminals whereby the resistor can be readily changed for one of a different heat output.
  • the physical relationship between the heating element and the thermal actuator of the switch i.e. the bimetal
  • Fig. 3 shows the switch of Fig. 2 viewed from the opposite side and illustrates an exemplary form of carrier 20 adapted to receive therein a holder 25 for a thin film resistor and to be fitted onto the top of the switch (as viewed in the figures) so as to place the thin film resistor adjacent to the bimetal blade
  • the carrier 20 is constituted by a simple plastics moulding having a recess 21 for receiving the holder
  • the holder 25 is configured to fit over the top of the switch as shown in Fig. 4. As mentioned hereinabove, the holder 25 has spring terminals (not shown) for holding the thin film resistor, and these connect to terminal pins 26 for connection to electrical leads 27.
  • thermally-responsive control in which a thermally-responsive electrical switch is arranged at a location remote from the thermal source which is to be responsible for switch operation, a heating element which is controlled in dependence upon the condition of the thermal source being arranged to simulate to the thermally-responsive switch actuator the temperature change to which the control is required to respond.
  • the thermally-responsive electrical switch is capable of manual actuation, and a component of the switch provides a clear indication by virtue of its movement, position or state of the status of the switch contacts.
  • time delay between energization of the heating element and operation of the switch which may be substantially predetermined, and the duration of this time delay may be adjusted by setting the temperature at which the switch operates (for example by selection of the bimetal and/or of its biassing conditions in the described Jl switch) , and/or by selecting the power output of the heating element, and/or by selecting the heat transfer relationship between the heating element and the thermally-responsive switch actuator.
  • the switch described in GB 9208264.3 is a modified form of the Jl switch described in GB 2212664A with reference to Figs. 3A to 3M or Figs. 9A and 9B thereof, and as compared to the basic Jl switch this modification has an additional pair of switch contacts and a manually-operable selector which cooperates with the Jl trip lever and interacts furthermore with the additional switch contacts so as to accommodate the normal ON-OFF movements of the trip lever and additionally be capable of opening and closing the additional switch contacts.
  • the manually- operable selector of the thus modified Jl switch as described in GB 9208264.3 (Serial No.
  • a rocker switch having a central position in which one of the associated pairs of switch contacts is open irrespective of the condition of the other pair, a first alternative position in which only the abovementioned one of the pairs of switch contacts is closed while the other is open, and a second alternative position in which both pairs of switch contacts are closed, and these three positions are illustrated in Figs. 5A, 5B and 5C respectively where the abovementioned one pair of switch contacts is designated 51 and the other pair is designated 52.
  • the two switches 51 and 52 can be connected so as to determine the power supplies to two heating elements, for example, so that neither, only one or both of the elements are powered depending on the condition of the switch.
  • the two heating elements are designated 53 and 54 and might, for example, be differently powered heating elements of a laundry drier or a room heater, or might be boil and simmer elements of a beverage making machine.
  • such an appliance might be thermally protected by provision of one or more thermal cut-outs or PTC elements connected in series with the switch 51 (say, between the locations X and Y indicated in Figs.

Landscapes

  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Control Of Resistance Heating (AREA)
  • Thermally Actuated Switches (AREA)

Abstract

Protection d'un appareil électrique (1) contre la surchauffe par plusieurs disjoncteurs (2) thermiques branchés en série, de type auto-réenclenchable, chacun de ces disjoncteurs étant installé dans l'appareil à proximité d'un point chaud potentiel. La protection est également assurée par un relais thermique comprenant un commutateur (3) bistable réagissant à la chaleur, branché sur la ligne d'alimentation principale de l'appareil, et un corps de chauffe (4) associé au commutateur et connecté de manière à entrer en fonction dans le cas où l'un quelconque des disjoncteurs crée un circuit ouvert. De ce fait le commutateur (3) réagissant à la chaleur entre en fonction, sous l'effet de la chaleur dégagée par le corps de chauffe (4), au terme d'un certain délai, en réponse à toute entrée en fonction d'un disjoncteur (2) du fait d'une surchauffe localisée. Les disjoncteurs (2) peuvent être situés en des points relativement inaccessibles de l'appareil puisqu'il n'est pas nécessaire d'y avoir accès pour les réenclencher manuellement, et le commutateur (3) réagissant à la chaleur peut être situé en un point immédiatement accessible. Cette disposition résout le problème de la nécessité du recours à un technicien lorsqu'un disjoncteur se met à sauter inopinément en réponse à des fluctuations, comme c'est couramment le cas avec des disjoncteurs du type non-réenclenchable automatiquement.
PCT/GB1992/001197 1991-07-02 1992-07-02 Ameliorations concernant les dispositifs de securite reagissant a la chaleur WO1993001640A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9326570A GB2273007B (en) 1991-07-02 1992-07-02 Improvements relating to thermally-responsive controls

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9114247.1 1991-07-02
GB919114247A GB9114247D0 (en) 1991-07-02 1991-07-02 Improvements relating to thermally-responsive controls

Publications (1)

Publication Number Publication Date
WO1993001640A1 true WO1993001640A1 (fr) 1993-01-21

Family

ID=10697665

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1992/001197 WO1993001640A1 (fr) 1991-07-02 1992-07-02 Ameliorations concernant les dispositifs de securite reagissant a la chaleur

Country Status (3)

Country Link
AU (1) AU2222692A (fr)
GB (2) GB9114247D0 (fr)
WO (1) WO1993001640A1 (fr)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5386100A (en) * 1992-10-30 1995-01-31 Black & Decker Inc. Control arrangement for immersion liquid heaters
GB2350232A (en) * 1999-05-17 2000-11-22 Otter Controls Ltd Low current switching device for an electrically heated water boiling vessel
EP1577918A2 (fr) 2004-03-20 2005-09-21 Hans Schneider Ensemble de détection de surchauffes se produisant localement
US7475698B2 (en) 2005-04-22 2009-01-13 Steelkor, L.L.C. Kitchenware washers and methods of manufacturing the same
US7527062B2 (en) 2001-02-15 2009-05-05 Steelkor, L.L.C. Kitchenware washers and methods of manufacturing the same
US7578305B2 (en) 2001-02-15 2009-08-25 Steelkor, L.L.C. Kitchenware washers and related methods
EP2117284A1 (fr) * 2008-03-17 2009-11-11 Martin Professional A/S Boucle de sécurité pour appareil d'éclairage
US9265400B2 (en) 2005-04-22 2016-02-23 Duke Manufacturing Co. Commercial kitchenware washers and related methods
GB2554913A (en) * 2016-10-13 2018-04-18 John Fletcher Adam Sensor apparatus for sending overheating
CN110311348A (zh) * 2019-08-08 2019-10-08 广东电网有限责任公司 多功能保护装置及电表箱

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB607813A (en) * 1946-02-12 1948-09-06 Metals & Controls Corp Electrical protective apparatus for energy translating devices
DE1129606B (de) * 1961-07-27 1962-05-17 Stotz Kontakt Gmbh Schutzschaltung fuer elektrische Geraete
GB1009886A (en) * 1961-02-11 1965-11-17 John Archer Improvements in or relating to electric heating devices
DE2253619A1 (de) * 1972-11-02 1974-05-16 Diehl Fa Leistungsregler fuer elektrische kochplatten
US4337450A (en) * 1980-06-09 1982-06-29 Eaton Corporation Remote control electro-thermal actuator switch
DE3129043A1 (de) * 1981-07-23 1983-02-03 Robert 4800 Bielefeld Stahlschmidt "schaltanordnung fuer elektrische maschinen"
WO1987004560A1 (fr) * 1986-01-16 1987-07-30 Limitor Ag Coupe-circuit de securite
EP0318265A2 (fr) * 1987-11-23 1989-05-31 Otter Controls Limited Commutateurs électriques thermosensive

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB607813A (en) * 1946-02-12 1948-09-06 Metals & Controls Corp Electrical protective apparatus for energy translating devices
GB1009886A (en) * 1961-02-11 1965-11-17 John Archer Improvements in or relating to electric heating devices
DE1129606B (de) * 1961-07-27 1962-05-17 Stotz Kontakt Gmbh Schutzschaltung fuer elektrische Geraete
DE2253619A1 (de) * 1972-11-02 1974-05-16 Diehl Fa Leistungsregler fuer elektrische kochplatten
US4337450A (en) * 1980-06-09 1982-06-29 Eaton Corporation Remote control electro-thermal actuator switch
DE3129043A1 (de) * 1981-07-23 1983-02-03 Robert 4800 Bielefeld Stahlschmidt "schaltanordnung fuer elektrische maschinen"
WO1987004560A1 (fr) * 1986-01-16 1987-07-30 Limitor Ag Coupe-circuit de securite
EP0318265A2 (fr) * 1987-11-23 1989-05-31 Otter Controls Limited Commutateurs électriques thermosensive

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5386100A (en) * 1992-10-30 1995-01-31 Black & Decker Inc. Control arrangement for immersion liquid heaters
GB2350232A (en) * 1999-05-17 2000-11-22 Otter Controls Ltd Low current switching device for an electrically heated water boiling vessel
GB2350232B (en) * 1999-05-17 2003-02-19 Otter Controls Ltd Improvements relating to controls for water boiling vessels
US7527062B2 (en) 2001-02-15 2009-05-05 Steelkor, L.L.C. Kitchenware washers and methods of manufacturing the same
US7578305B2 (en) 2001-02-15 2009-08-25 Steelkor, L.L.C. Kitchenware washers and related methods
EP1577918A2 (fr) 2004-03-20 2005-09-21 Hans Schneider Ensemble de détection de surchauffes se produisant localement
EP1577918A3 (fr) * 2004-03-20 2007-08-01 Hans Schneider Ensemble de détection de surchauffes se produisant localement
US7475698B2 (en) 2005-04-22 2009-01-13 Steelkor, L.L.C. Kitchenware washers and methods of manufacturing the same
US9265400B2 (en) 2005-04-22 2016-02-23 Duke Manufacturing Co. Commercial kitchenware washers and related methods
EP2117284A1 (fr) * 2008-03-17 2009-11-11 Martin Professional A/S Boucle de sécurité pour appareil d'éclairage
CN101430080B (zh) * 2008-03-17 2011-04-06 马田专业公司 用于电灯器具的保险回路
US7990673B2 (en) 2008-03-17 2011-08-02 Martin Professional A/S Safety loop for a light fixture
EP2326150A3 (fr) * 2008-03-17 2011-12-21 Martin Professional A/S Boucle de sécurité pour appareil d'éclairage
GB2554913A (en) * 2016-10-13 2018-04-18 John Fletcher Adam Sensor apparatus for sending overheating
CN110311348A (zh) * 2019-08-08 2019-10-08 广东电网有限责任公司 多功能保护装置及电表箱

Also Published As

Publication number Publication date
GB2273007A (en) 1994-06-01
GB9326570D0 (en) 1994-03-16
GB2273007B (en) 1995-11-08
GB9114247D0 (en) 1991-08-21
AU2222692A (en) 1993-02-11

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