WO1996032733A1 - Thermoregulation pour cuves de chauffage de liquides - Google Patents

Thermoregulation pour cuves de chauffage de liquides Download PDF

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Publication number
WO1996032733A1
WO1996032733A1 PCT/GB1996/000877 GB9600877W WO9632733A1 WO 1996032733 A1 WO1996032733 A1 WO 1996032733A1 GB 9600877 W GB9600877 W GB 9600877W WO 9632733 A1 WO9632733 A1 WO 9632733A1
Authority
WO
WIPO (PCT)
Prior art keywords
thermally
responsive
sensor
sme
trip lever
Prior art date
Application number
PCT/GB1996/000877
Other languages
English (en)
Inventor
Robert Andrew O'neill
Stephen Roger Brook
Ian Geoffrey White
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 AU52843/96A priority Critical patent/AU5284396A/en
Publication of WO1996032733A1 publication Critical patent/WO1996032733A1/fr

Links

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
    • H01H37/323—Thermally-sensitive members making use of shape memory materials
    • 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
    • H01H2061/0115—Shape memory alloy [SMA] actuator formed by coil spring
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/04—Bases; Housings; Mountings

Definitions

  • This invention concerns improvements in or relating to thermal controls for liquid heating vessels and more particularly, though not exclusively, concerns controls for water boiling vessels such as electrically heated jugs and kettles for example in which the generation of steam when water boils in the vessel causes the control to operate so as, for example, to switch-off or reduce the supply of electrical power to the vessel and/or provide some other control indication.
  • Steam controls for water boiling vessels are well known per se and are likewise well known in combination with so-called element protector controls which are adapted to switch-off the supply of electrical power to the heating element of a liquid heating vessel in the event of a sensed element overtemperature condition caused for example by the vessel being switched on with insufficient or no water in the vessel or by the vessel, in the absence of a steam control or on failure of the steam control, being permitted to boil dry.
  • Known steam controls and element protector controls commonly make use of bimetal technology, with the thermally-responsive actuator of the control being constituted by a bimetal, commonly a snap-acting bimetal, which is arranged to change condition upon exposure to a predetermined temperature change, for example upon exposure to steam generated when water boils in the respective vessel.
  • Steam controls are also known in various different forms. Steam controls are known which incorporate a set of electrical switching contacts which have to be closed in order that electrical power can be supplied to the heating element of the vessel, and other steam controls are known which incorporate no switching contacts themselves but merely provide a mechanical switch-actuating movement which is transferred to a separate set of switching contacts, for example in an associated element protector control. It is known furthermore to associate the steam control of a water boiling vessel with a manually-operable ON-OFF control of the vessel, and it has further been proposed to provide an interlock between the base of a so-called cordless electric kettle and the kettle proper to ensure that the ON-OFF control cannot be in its ON condition when the kettle is not standing on its base.
  • Otter Controls Limited have pioneered the provision of steam controls and element protector controls in water boiling vessels, aided and abetted in their pursuit of excellence in recent times by competition from Strix Limited of the Isle-of-Man.
  • both Otter Controls and Strix who between them have the lion's share of the World's business in such controls, have employed bimetallic actuators to the exclusion of all other thermal actuators in their steam controls and element protector controls and the reason for this is that bimetallic actuators have consistently provided the best solution to the problems which arise in the design of such controls, namely the provision of reliable and repeated operation within predetermined temperature limits and over tens and perhaps hundreds of thousands of operations, and all at acceptable, cost.
  • the present invention represents, in one of its aspects, a departure from Otter Controls' bimetal technology in favour of shape memory metal technology.
  • Shape memory effect (SME) thermal actuators in the form of shape memory metal helical springs were at one time employed in steam controls for electric kettles, though not by Otter Controls, but proved to be unreliable and uncompetitive with bimetallic controls.
  • Titanium-Nickel SME alloys and more particularly Titanium-Nickel-Copper SME alloys, are available which enable a very small helical spring actuator to be designed which exhibits sufficient stroke (movement) with the development of sufficient force, is repeatably reliable in excess of 100,000 operations, and is price competitive on account of its relatively low material content.
  • a suitable helical spring SME actuator can be designed which has an inner diameter of 1.5mm and three coils which will give a 1 Newton force output at a stroke of 4mm. Because the actuator is a spring, it will generate proportionately higher forces at shorter strokes.
  • the SME actuator preferably in the form of a helical spring as aforesaid but possibly of alternative form, would be mounted forwards of the diaphragm, that is to say on the steam side of the diaphragm where it will be exposed to steam generated in the vessel when water boils.
  • a push-rod and/or an overcentre ON-OFF control arrangement might interact with the diaphragm to determine the status of electrical switch contacts as aforesaid provided in the control or to provide mechanical movement to be transmitted by appropriate means to a separate set of switching contacts.
  • the silicone rubber (or other material) diaphragm could be moulded integrally with the push-rod which would be sufficiently thick to be effectively rigid.
  • the push-rod could also extend both forwardly of the diaphragm, so as to provide a mounting for the SME actuator, and rearwardly of the diaphragm, for operating the switch contacts.
  • the push-rod could be separately formed and the diaphragm could be moulded around it by insert moulding, or the push-rod could be entirely separate from the diaphragm or could be a separate part but affixed to the diaphragm.
  • an ON-OFF control it might preferably be in the form of an overcentre spring mechanism which could be arranged to operate a pair of switching contacts.
  • the overcentre mechanism might comprise a trip lever moulding incorporating a pivot or fulcrum feature and a means of mounting a customer knob, and a spring, for example a C-spring.
  • the switching contacts may be operated by a projection from the trip lever, or by means of a separate push- rod co-operating with the trip lever.
  • the control should desirably be resistant to casual spillage of water over the trip lever, and the provision of a separate push-rod might facilitate this.
  • the trip lever and/or the customer knob may incorporate water shedding details and, in one embodiment which will hereinafter be described, the trip lever is furthermore mounted within a tubular housing or chimney separated from a contact-carrying portion of the control.
  • a feature extends from the lowest part of the trip lever and rises over an internal barrier for accessing the switching contacts, thereby ensuring that any water falling over the trip lever will pass through holes in the bottom of the tubular housing and cannot access the switching contacts.
  • the steam control comprises an enclosed switch body, and a trip lever is external to the switch body and has features which extend from its lowest parts and enter the switch body proper via holes in its underside to access both a push-rod associated with the diaphragm seal and the switching contacts.
  • This alternative arrangement makes it very difficult for any water accidentally to access electrical parts of the control and would allow a wider range of mounting attitudes before the water shedding would be compromised.
  • Figures 1A and IB show in exploded perspective view from opposite viewpoints the component parts of a first embodiment of the present invention
  • Figures 2A and 2B show top plan and cross- sectional views of the first embodiment to an enlarged scale, the cross-sectional view of Figure 2B being taken on the line A...A in Figure 2A, Figures 2C and 2D show front end and rear end perspective views of the first embodiment, and Figures 2E and 2H show top plan and side and end elevation views of the first embodiment;
  • Figures 3A and 3B show exploded perspective views from opposite viewpoints of a second embodiment of the present invention
  • Figures 4A to 4H are views of the second embodiment similar to the views of the first embodiment shown in Figures 2A to 2H.
  • Detailed Description of the Embodiments Referring first to Figures 1A and IB, the steam control shown therein is shown in its normal in use attitude in Figure 1A and is shown upside down in Figure IB.
  • the control has moulded plastics body parts 1 and 2 which fit together as is clearly shown in the drawings, a moulded plastics trip lever 3 , a C- spring 4, spring metal terminal parts 5 and 6 each of which is formed to define a receptacle for a spade terminal and, extending therefrom, a limb carrying a silver contact, a silicone rubber diaphragm 7 having an integrally-moulded push-rod 8 and an SME actuator 9 in the form of a helical spring.
  • the body part 1 has internal walls 10, 11, 12 and 13 which define a tubular passage or chimney 14. Edges at the ends of the walls 10 and 12 are V-notched at 15 to provide pivot points for fulcrums 16 that are provided extending outwardly at the base of the trip lever 3.
  • the trip lever 3 is inserted into the chimney 14 so that its top end protrudes from the upper side of the body part 1 and the fulcrums 16 engage in the pivot points 15.
  • the C-spring 4 is fitted between a V- groove 17 provided in the upper end of the trip lever 3 and a pair of V-grooves 18, 19 provided in the ends of upstands 20, 21 provided internally of the other body part 2, when the two body parts l and 2 are fitted together.
  • the top end of the trip lever 3 is thus able to be moved between stable forward and rearward positions, with a snap action, between an intermediate unstable condition.
  • An internal barrier 22 is provided in the body part 2 of the control, as may best be seen from the lower view in Figure 1A and from Figure 2B.
  • This barrier 22 defines behind it a region 23 within the control whereat the terminal parts 5 and 6 are received with their receptacles accessible via openings provided in the rear wall of each body part 1 and 2 and their spring metal limbs extending generally towards each other so that their silver contacts can co-operate in switching operations.
  • the terminal parts 5 and 6 are identical, thus avoiding the need to produce right-handed and left- handed parts.
  • the SME element 9, operating via the diaphragm 7 and push-rod 8, provides for automatic movement of the trip lever 3 from its forward (ON) position to its rearward (OFF) position as will now be explained.
  • an integrally moulded rectangular formation 25 having a circular through-opening 26.
  • a complementary cut-out 27 is formed in the front end of the body part 1 so that the two body parts can be fitted closely together.
  • a recess 28 which is complementary to the formation 25, so that the formation 25 can be fitted snugly and sealingly into the recess 28, and a hollow, thin walled, circularly-cylindrical boss 29 is located centrally of the recess 28 and is dimensioned to fit snugly into the circular through-opening 26.
  • the push-rod 8 is moulded integrally with, and formed of the same material as, the silicone rubber diaphragm element 7 and has a part 8' which extends forwardly of the diaphragm proper and a part 8'' which extends rearwardly of the diaphragm proper, the diaphragm proper being constituted by the boss 29 and by an integrally-formed thin walled membrane 30 which connects the centre of push-rod 8 to the rearwardmost end of hollow boss 29.
  • This arrangement enables push-rod 8 to move without comprising the diaphragm sealing.
  • FIGs 1A and IB the diaphragm proper 29, 30 and the push-rod 8 are shown in their most rearward condition; the operating condition of these parts is shown in Figure 2B.
  • Body part 1 of the control has a forwardly- extending portion 31 which has a downwardly-extending part 32 having a circular opening 33 therein for supporting the forward end of push-rod 8 as is most clearly shown in Figure 2B.
  • the silicone rubber element 7 has a rectangular forward part 34 adapted to be sealingly received in a complementary opening in a vessel wall, and a portion 35 of the part 34 is hingedly attached for sealingly engaging the portion 31 of body part 1 which extends through the part 34, it being noted that a rib 36 is provided on the underside of hinged portion 35 for sealing engagement with a groove 37 formed in the part 34.
  • the rearward end of push-rod 8 co-operates with a portion 38 of the trip lever 3 for setting the trip lever into its rearward (OFF) condition when the SME actuator elongates in response to being heated by steam and, by reaction against portion 32 of the control body, drives the push-rod 8 rearwards.
  • the operation of the first embodiment described in the foregoing will be clear without need for further description.
  • the SME element 9 is subjected to impingement by steam from water boiling in an associated vessel and elongates in consequence, thereby driving push-rod 8 rearwardly so as to cause trip lever 3 to move to its rearwardly pivoted position where the finger 24 opens the switch contacts and, by virtue of the bistable nature of the trip lever movement, holds them open until the trip lever is manually reset.
  • the interior of the control is well sealed from steam impinging upon the SME element 9, and likewise the control is well protected against accidental spillage of water onto the trip lever, for example when the vessel is being filled.
  • the trip lever 3 is a bifurcated element which straddles the control from beneath and has parts which reach up into the control for co-operation with the rearward end of the push-rod and with the switching contacts.
  • the trip lever 3 has first and second side portions 3' and 3'' respectively which are bridged at their lower ends by a portion 3' ' ' which carries the finger 24 for operating the switch contacts and also carries an abutment 38 for co-operation with push-rod 3.
  • the control body part 1 has truncated V-shaped recesses 40 in its flanks and these serve to locate the side portions 3' and 3" of the trip lever and provide for pivotal movement of the same.
  • the bridge portion 3' ' ' of the trip lever has a pair of apertures 41 formed therein and the fulcrums or pivot points 16 which provide for pivotal mounting of the trip lever are provided adjacent these apertures 41.
  • the body part 1 of the control has a pair of upstands 42 which carry co ⁇ operating fulcrums or pivot points 15, the arrangement being such that the formations 15 on the upstands 42 engage with the complementary formations 16 on the trip lever 3 when the trip lever is assembled to the body part 1 by springing the upstands 42 through the apertures 41.
  • the C-spring 4 locates between V-groove 17 formed in the bridge portion 3' ' ' of the trip lever and V-groove 18 formed in the underside of the upper surface of body part 1.
  • the second embodiment differs from the first only in constructional details which are readily apparent from the accompanying drawings and require no further elaboration.
  • the second embodiment operates in the same manner as the first, but is to be preferred in that it provides greater protection of the electrical switching from accidental spillages and, correspondingly, enables a wider range of mounting attitudes before its water shedding advantages would be compromised.
  • the described embodiments are exemplary only and that modifications and variations are possible without departure from the spirit and scope of the invention.
  • the SME element in the described embodiment is preferably formed of a Titanium-Nickel-Copper alloy as aforesaid, such an alloy having desirable characteristics for a steam sensing application, it is within the wider ambit of the present invention that it be formed of an alternative material, particularly though not exclusively a Titanium-Nickel alloy, exhibiting appropriate characteristics.
  • the invention has been particularly described with reference to steam controls for water boiling vessels, the invention has wider application.

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  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Cookers (AREA)
  • Switch Cases, Indication, And Locking (AREA)

Abstract

Cette invention concerne une commande de détecteur de vapeur destinée à un appareil électroménager électrique servant à faire bouillir de l'eau, cette commande comportant un actionneur sensible à la chaleur ayant la forme d'une hélice de matière à effet de mémoire de forme (SME) constituée d'un alliage titane-nickel-cuivre. L'actionneur développe une force élevée et produit un mouvement notable par rapport à ce que l'on obtiendrait avec un bilame et il permet d'obtenir une commande de détecteur de vapeur hermétique dont les contacts de commutation sont logés à l'intérieur d'une partie du corps de la commande et sont isolés du détecteur à effet de mémoire de forme (SME), qui se trouve à l'extérieur de cette partie du corps de la commande, par un joint d'étanchéité à diaphragme constitué de caoutchouc de silicone, ledit joint d'étanchéité à diaphragme possédant un poussoir moulé d'une pièce qui sert de support pour l'hélice à effet de mémoire de forme (SME) du côté humide du diaphragme où se trouve la vapeur et sert à actionner les contacts de commutation du coté sec par l'intermédiaire d'un levier de déclenchement bistable.
PCT/GB1996/000877 1995-04-10 1996-04-10 Thermoregulation pour cuves de chauffage de liquides WO1996032733A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU52843/96A AU5284396A (en) 1995-04-10 1996-04-10 Thermal control for liquid heating vessels

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9507386A GB2299859B (en) 1995-04-10 1995-04-10 Thermally responsive steam sensor device
GB9507386.2 1995-04-10

Publications (1)

Publication Number Publication Date
WO1996032733A1 true WO1996032733A1 (fr) 1996-10-17

Family

ID=10772819

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1996/000877 WO1996032733A1 (fr) 1995-04-10 1996-04-10 Thermoregulation pour cuves de chauffage de liquides

Country Status (3)

Country Link
AU (1) AU5284396A (fr)
GB (2) GB2334822B (fr)
WO (1) WO1996032733A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10352929B2 (en) 2003-08-06 2019-07-16 Senomyx, Inc. T1R hetero-oligomeric taste receptors, cell lines that express said receptors, and taste compounds

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2320277B (en) * 1996-12-09 2001-10-10 Univ Brunel Improvements relating to product disassembly

Citations (5)

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US3594674A (en) * 1969-08-13 1971-07-20 Robertshaw Controls Co Temperature-responsive control devcies adjustably responsive to various operating temperatures
GB1566231A (en) * 1978-04-11 1980-04-30 Standard Telephones Cables Ltd Overcurrent cutout
EP0037215A1 (fr) * 1980-04-01 1981-10-07 Pifco Limited Dispositif de commande de température pour appareil à chauffage électrique
GB2174548A (en) * 1985-04-11 1986-11-05 Nittan Co Ltd Combination heat-sensing fire detector
WO1991006357A1 (fr) * 1989-10-31 1991-05-16 Le Bozec Et Gautier Indicateur de colmatage

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US3882439A (en) * 1973-11-05 1975-05-06 Robertshaw Controls Co Thermal responsive switch device
US4020442A (en) * 1974-03-08 1977-04-26 Hochiki Corporation Composite-type heat-system fire sensing device
JPS54112429A (en) * 1977-10-27 1979-09-03 Delta Metals Res Fan unit
DE2759251B2 (de) * 1977-12-31 1981-04-23 Behr-Thomson Dehnstoffregler Gmbh, 7014 Kornwestheim Zweistufen-Temperaturschalter
GB2023818B (en) * 1978-05-31 1983-02-09 Delta Materials Research Ltd Temperature-respnive actuating-elements
US4408178A (en) * 1982-07-12 1983-10-04 The Singer Company Thermostatic switch
US4532490A (en) * 1983-05-23 1985-07-30 Pappas Phillip M Fail safe high limit control
DE3801583C1 (fr) * 1988-01-21 1989-08-03 Abc-Elektrogeraete Volz, Gmbh & Co, 7312 Kirchheim, De
GB8818646D0 (en) * 1988-08-05 1988-09-07 Strix Ltd Thermally-responsive actuators & electrical controls incorporating such actuators

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3594674A (en) * 1969-08-13 1971-07-20 Robertshaw Controls Co Temperature-responsive control devcies adjustably responsive to various operating temperatures
GB1566231A (en) * 1978-04-11 1980-04-30 Standard Telephones Cables Ltd Overcurrent cutout
EP0037215A1 (fr) * 1980-04-01 1981-10-07 Pifco Limited Dispositif de commande de température pour appareil à chauffage électrique
GB2174548A (en) * 1985-04-11 1986-11-05 Nittan Co Ltd Combination heat-sensing fire detector
WO1991006357A1 (fr) * 1989-10-31 1991-05-16 Le Bozec Et Gautier Indicateur de colmatage

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10352929B2 (en) 2003-08-06 2019-07-16 Senomyx, Inc. T1R hetero-oligomeric taste receptors, cell lines that express said receptors, and taste compounds

Also Published As

Publication number Publication date
GB9507386D0 (en) 1995-05-31
GB2299859B (en) 1999-07-28
GB2334822A (en) 1999-09-01
GB2299859A (en) 1996-10-16
GB9907818D0 (en) 1999-06-02
GB2334822B (en) 1999-10-20
AU5284396A (en) 1996-10-30

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