WO1995019129A1 - Appareil de chauffage de l'eau - Google Patents

Appareil de chauffage de l'eau Download PDF

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Publication number
WO1995019129A1
WO1995019129A1 PCT/GB1995/000056 GB9500056W WO9519129A1 WO 1995019129 A1 WO1995019129 A1 WO 1995019129A1 GB 9500056 W GB9500056 W GB 9500056W WO 9519129 A1 WO9519129 A1 WO 9519129A1
Authority
WO
WIPO (PCT)
Prior art keywords
heater
head
water
immersion heater
temperature
Prior art date
Application number
PCT/GB1995/000056
Other languages
English (en)
Inventor
John Crawshaw Taylor
Paul Anthony Bottomley
Original Assignee
Strix 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 Strix Limited filed Critical Strix Limited
Priority to AU13901/95A priority Critical patent/AU1390195A/en
Priority to GB9615225A priority patent/GB2301226B/en
Publication of WO1995019129A1 publication Critical patent/WO1995019129A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
    • A47J27/00—Cooking-vessels
    • A47J27/21—Water-boiling vessels, e.g. kettles
    • A47J27/21008—Water-boiling vessels, e.g. kettles electrically heated
    • A47J27/21058—Control devices to avoid overheating, i.e. "dry" boiling, or to detect boiling of the water
    • A47J27/21083—Control devices to avoid overheating, i.e. "dry" boiling, or to detect boiling of the water with variable operating parameters, e.g. temperature or boiling period
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/72—Switches in which the opening movement and the closing movement of a contact are effected respectively by heating and cooling or vice versa
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/78—Heating arrangements specially adapted for immersion heating
    • H05B3/82—Fixedly-mounted immersion heaters

Definitions

  • This invention relates to apparatus for use in electric water heating vessels such as hot water jugs and kettles, and in particular to immersion heaters and control units for use therein.
  • Typical vessels of this type have a metal or plastics body within which the water is heated by means of an electric immersion heater.
  • immersion heaters generally comprise a heating element located within the water receiving portion of the vessel which is carried by a head adapted to be secured in a water tight manner in relation to an opening in a generally vertical wall of the water receiving portion.
  • the heating element is generally provided with so-called cold leads extending to the "dry" side of the head by means of which electrical connections are made to the immersion heater.
  • the element is bent into a tortuous shape in order to obtain a sufficient length and therefore an appropriate level of heat dissipation within the space available.
  • the exterior of the element is connected in good thermal contact with the head
  • This is the so-called "hot return” part of the immersion heater and its function is to allow a thermally operated control to be connected to the "dry" side of the head in order to provide switch-on-dry protection.
  • heat from the element is conducted to the head from the hot return and causes a thermally operated switch arranged in series with the element to disconnect the electrical supply.
  • GB- A-2204450 discloses a control having such a device in the form a plastics push rod extending from the unit and which in use abuts and is biased towards the heater head. The action of the heater head against the push rods causes the push rods to hold closed a pair of electrical contacts which are arranged in series with the heater element.
  • the plastics material is chosen such that in the event of serious overheating occurring, the push rod will start to melt, and as it does so the contacts will be allowed to open. It will be appreciated that the operation of this back-up device permanently disables the faulty control unit which must then be replaced.
  • an electric immersion heater assembly for use in water heating vessels, the heater having a head connected in good thermal contact with an element via a hot return, the element being in series electrical connection with a cycling thermally operated switch, and the switch having a thermally responsive actuator arranged in good thermal contact with the head and being adjustable to cycle at different temperatures.
  • the invention extends to a water heating vessel incorporating an immersion heater and switch in accordance with the first aspect of the invention.
  • thermally operated switch by appropriate adjustment of the thermally operated switch it is possible to employ such a heater in a water heating vessel in order to cause the water contained therein to simmer continuously, or to remain at some other predetermined temperature.
  • thermally responsive actuator in good thermal contact with the heater head, advantages are achieved as compared with locating an actuator against the vessel wall. Since water heating vessels often have walls formed of plastics materials, which are poor conductors of heat, there will be a delay between the water reaching a particular temperature and its being sensed by the actuator. In contrast, in the present invention, as the actuator is in good thermal contact with the metal heater head the actuator will be able to sense the water temperature more quickly and so the water may be kept at a more constant temperature.
  • a further advantage of the present invention is that controls with different operating characteristics may be provided.
  • the actuators it is only possible for the actuators to sense the water temperature, whereas in accordance with the invention, the operation of the switch may also, if desired, be adapted to more closely follow the heater temperature. This latter characteristic is particularly beneficial if it is desired to keep water as near to boiling as possible.
  • any water- temperature operated actuator it is not possible for any water- temperature operated actuator to be set to disable the power at a higher temperature than this. For practical purposes a slightly lower temperature than 100°C must be selected - otherwise a rolling boil may be established and the simmer control will not operate.
  • a temperature differential is required to allow the actuator (commonly a snap-acting bimetal) to cycle.
  • This differential may be 10 ⁇ C or as high as 20°C. It will therefore be appreciated that any system based upon the water temperature will lead to a maximum setting in which at some point in each cycle the water temperature will be 90°C or lower.
  • the cycling is also relatively slow, particularly when the vessel is full, as a consequence of the heat capacity of the volume of water being heated and cooled by 10°C or 20°C during each cycle.
  • thermally responsive actuator is arranged to sense the heater temperature. This is because the switch will cycle more quickly across the temperature differential of the actuator as a consequence of the heater having a lesser thermal capacity than the water in the vessel and because the disabling temperature of the heater can be above 100°C such that the average water temperature during cycling can be maintained closer to 100°C if desired.
  • the switch may be adjusted to cycle between 95°C and 105°C.
  • Such temperature variations of the heater head would result in a lesser fluctuation in water temperature about an average somewhere between 95°C and 100°C.
  • the water temperature lags behind heater temperature, and a more constant water temperature may be provided in the simmer mode.
  • this system of operation is equally applicable for other desired water temperatures.
  • the term "simmer control" is used herein to define this mode of operation, regardless of the water temperatures concerned.
  • One way to do this is to provide a non-cycling steam operated actuator in parallel with the thermally actuated switch controlled By the actuator. This will maintain the supply of current to the heater, regardless of the operation of the cycling switch until the water has boiled.
  • the actuator to sense the heater temperature in the manner just described.
  • scale will build up on the heater and this will have the effect of insulating the heater from the water, although it will not affect the flow of heat to the thermal actuator. This will result in the control switching off the heater at a lower water temperature than desired.
  • the thermal actuator such adjustment is, of course, limited and therefore with heavy scale it may become impossible to set the vessel to boil water.
  • the thermal actuator should be located in good thermal contact with a part of the head which is not significantly heated directly by the immersion heater. In the case of a standard immersion heater this means locating the actuator remote from the hot return, eg. towards the perifery of the head.
  • One way of doing this is to provide a surface on the heater head against which the actuator may abut.
  • a preferred arrangement takes advantage of the control mounting studs which are provided on standard immersion heater heads by arranging the actuator to sense the temperature of the head via one of these studs, preferably the upper one. Since the space around the studs is limited, it is preferred to provide a heat bridge to connect the stud to a remote actuator.
  • the thermally operated cycling switch may be provided in addition to conventional switch on dry apparatus, in which case it may be disabled by being short circuited. However, it is particularly preferred for the operations of simmer control and switch-on-dry protection to be combined. This is achieved by allowing the cycling thermally operated switch to be adjustable to a "boil" setting in which it does not cause the current to be disconnected from the immersion heater in normal operation. Thus, typically the actuator has a maximum setting which causes it to disconnect the current when the heater head reaches about 135°C. Such a temperature should only be reached when the vessel boils dry or is switched on with insufficient water in the vessel to cover the element.
  • the provision of the thermally responsive actuator in the region of the heater head has a still further advantage which relates to the convenience of producing water heating vessels. That is, it makes it possible to produce an integrated control unit which provides a simmer control.
  • an integrated control unit for use in a water heating vessel, the control unit having an insulating body arranged to be attached to a mounting location which is in thermal contact with part of an electric heater of the vessel, means for providing electrical connection to the cold leads of such a heater upon attachment, terminal pins for connection to a supply of electric current, and a thermally operated cycling switch arranged to control the flow of current between the pins and the heater, the switch having a thermally responsive actuator arranged to be in good thermal contact with said mounting location upon attachment of the control thereto and being adjustable to cycle at different temperatures.
  • the mounting location is preferably the heater head.
  • Alternative arrangements include "underfloor" systems in which the heater is secured in good thermal contact to the underside of a metal vessel base.
  • the mounting location may, for example, be a metal member located in good thermal contact with the heating element, other arrangements are possible.
  • connection and switch-on-dry protection facilities of known integrated controls, together with an additional simmer facility are provided within a single unit which may be connected directly to e.g. an immersion heater in a single operation.
  • an immersion heater in a single operation.
  • the control unit may also be arranged to provide one or more of the preferred features discussed above in respect of the first aspect of the invention.
  • the switch-on-dry facility may be separate from the simmer control, and the simmer control may be disabled by short circuiting it, it is possible to use the same switch to provide both functions.
  • the thermally operated switch should be adjusted so that it disconnects the current from the immersion heater at a head temperature which will only occur in the event of the vessel boiling dry or being switched on when dry.
  • the integrated control according to the second aspect of the invention may also provide other functions found in known controls.
  • a back-up protection system may be provided, for example using a meltable push rod holding a set of contacts closed against a bias spring, the push rod being arranged to be in thermal contact with the heater head.
  • the control may be provided or used in conjunction with a steam operated switch which serves to switch off the vessel when water is boiled. Such switches are well known in the art.
  • the cycling thermally operated switch may be electronic, possibly comprising a thermistor, but it is preferred to have an actuator in the form of a bimetal arranged to operate a set of contacts preferably operated via a snap-acting over-centre mechanism.
  • An adjusting mechanism is provided such that the amount of movement of the bimetal required to trip the mechanism can be varied. Many such mechanisms are known in adjustable cycling switches used in thermostats etc.
  • the presently preferred arrangement is to provide an over-centre switch mechanism having a movable pivot point. In this arrangement movement of the pivot point serves to vary the distance which the bimetal must move in order to cause the over-centre mechanism to change condition.
  • the over-centre mechanism may have a switch arm having a contact mounted at a first end for co-operation with a fixed contact, the second end of the switch arm being mounted on a support member and being displaceable therewith by the bimetal, there being provided at an intermediate portion of the switch arm a tongue which is held in compression and which is movable relative to the body of the switch arm.
  • the distal end of the tongue is located against a first pivot point on a tensile portion of a support member, the tensile portion being movable relative to the remainder of the support member.
  • the pivot point By moving the tensile portion relative to the support member, the pivot point is moved. By moving the pivot point towards the bimetal, the distance which the bimetal must move in order to cause the over-centre mechanism to operate is reduced and therefore the temperature required to operate the switch is also reduced. Likewise, moving the pivot point further from the bimetal increases the temperature at which the switch operates.
  • the pivot point may most conveniently be moved by providing an adjustment member arranged to move the tensile member on which the pivot is formed.
  • This may be provided in the form a threaded rod received within a threaded bore formed in the body of the control unit so that by turning the rod, the pivot point may move towards or away from the bimetal.
  • a camming arrangement may be preferred in certain circumstances since this may provide a greater linear movement for a given rotation of the rod.
  • control member is arranged so that it may be easily adjusted by users of vessels in which the control is located either to change the desired water temperature or to override the simmer function in order to allow water to boil or to heat up quickly before the unit is reset to a simmering temperature.
  • control member in hard water areas, as a result of the element becoming covered in scale, it will become less effective over time and therefore a higher element temperature will be required for a given water temperature. Consequently, it will be necessary to make corresponding adjustments to the temperature at which the thermally operated cycling switch operates.
  • certain embodiments of the invention comprise an elongate bimetal extending beyond the outer circumference of the heater head. This is most easily achieved when a heat bridge is provided (as discussed above) . This is because it is necessary to provide a seal between the heater head and the vessel adjacent the control, and the heater bridge (eg. a collar) is suitable for spacing the bimetal from the seal.
  • trimetal which is a bimetal with an extra layer of high thermal conductivity material such as copper.
  • Fig. 1 is an exploded schematic perspective view of an immersion heater head and integrated control unit according to a first embodiment of the invention with certain portions removed for clarity;
  • Fig. 2 is a plan view of the immersion heater head and control with the main moulding of the control unit removed;
  • Figs. 3 and 4 are further perspective views of the head and control unit
  • Fig. 5 is an elevation, on an enlarged scale, of the system of Fig. 2 and viewed in the direction of the arrow shown in that figure,-
  • Fig. 6 is a schematic side elevation of the control unit and immersion heater
  • Fig. 7 is a graph illustrating the operation of the control unit and immersion heater
  • Fig. 8 is a perspective view of the rear of a control according to a second embodiment of the invention.
  • Fig. 9 is a perspective view of the front of the control of Fig. 8.
  • Fig. 10 is a plan view of the control of Fig. 8 with its cover removed to show the internal components
  • Fig. 11 is an exploded perspective view of the control of Fig. 8;
  • Fig. 12 is an exploded sectional view of part of the control of Fig. 8.
  • Fig. l there is illustrated an immersion heater of which only the head 1 and certain associated parts are shown, together with certain parts of the control unit. Projecting from the heater head 1 are the cold leads 2 and 3 of the heater element and fixing studs 4,5 and 6. The head is brazed to the element (not shown) in the usual manner.
  • the control unit has a main moulding 7 formed of thermoplastics material. It has apertures 8, 9 and 10 for receiving studs 4, 5 and 6 respectively and three further apertures 11, 12 and 13 for receiving pins 14, 15 and 16 which form the neutral, earth and line connections of a standard plug connector' (see Figs. 3 and 4) . A further aperture 17 is provided through which passes adjustment spindle 18 whose function will be discussed in detail below.
  • the main moulding 7 co- operates with base portion 18 (shown in Figs. 2 to 5) to close the control unit.
  • the control unit is attached to the heater head by means of screws or bolts which pass through apertures 8, 9 and 10 and are received in threaded bores in studs 4, 5 and 6.
  • the internal components of the apparatus will now be described. From Fig.
  • pin 16 abuts a contact on conducting strip 20 which forms a connection between it and cold lead 2.
  • the strip is flexible and is biased away'from pin 16 by means of a spring 21.
  • the strip is held against the terminal by means of a push rod 22 formed of low melting point plastics material.
  • the rod 22 passes through a hole in base portion 18 and abuts a convex portion 23 of the heater head. On the opposite side of this portion of the head is mounted the hot return.
  • the purpose of this arrangement is to provide a back-up protection system to disable the control unit in the event that it becomes seriously overheated. Should this occur, the push rod 22 will be seriously distorted or melted by the heat which will allow spring 21 to move strip 20 away from terminal 16, thereby disconnecting the line supply from the element.
  • the immersion heater and control unit assembly are both earthed by means of pin 15 which is connected via a conducting strip (not shown) to one of the studs 4, 5 or 6.
  • Neutral pin 14 is connected to cold lead 3 of the immersion heater via a thermally actuated switch assembly 30.
  • This assembly is actuated by a creep bimetal 34 which is attached at one end 34' to the heater head at or adjacent to the convex portion 23. The precise position of attachment may be varied; attaching it directly to convex portion 23 will lead to the assembly 30 being controlled almost entirely by the heat of the element via the hot return, whereas moving it further away will allow the temperature of water touching the other side of the heater head to have some influence on the operation.
  • the bimetal 34 is arranged such that its free end moves gradually away from the head 1 as it heats up.
  • a push rod 33 formed of an insulating material such as plastics.
  • the opposite end of the microswitch carrier 31 is provided with an aperture which provides an interference fit around neutral pin 14, thereby supporting it and providing an electrical connection.
  • the microswitch carrier 31 is formed of metal which is sufficiently flexible to allow the opposite end to be moved by the push rod as previously described.
  • a tongue 35 which is only connected to the remainder of the carrier at a small area near the neutral pin.
  • the tongue 35 is free to flex independently of the remaining portion of the carrier.
  • a hole 36 one edge 36' of which forms a knife edge pivot for the microswitch arm 32.
  • calibration screw 37 Abutting only a central portion of the tongue 35 is one end of calibration screw 37 which is threadedly and axially received within adjustment spindle 18.
  • the arrangement is such that relative rotation of the adjustment spindle 18 and calibration screw 37 serves to vary their combined length.
  • the adjustment spindle is provided with a helical portion 38 which is received within a corresponding portion of the main moulding so that the rotation of the adjustment spindle relative to the main moulding causes the spindle and calibration screw to move back and forth together.
  • the calibration screw 37 abuts the tongue portion of microswitch carrier 31 this causes the tongue to move in a corresponding manner, thereby moving the pivot formed by the edge 36' of hole 36 towards or away from the bimetal 34.
  • microswitch arm 32 As discussed previously, push rod 33 is connected to microswitch arm 32 as well as microswitch carrier 31.
  • the arrangement is such that the microswitch arm and the microswitch carrier lie generally parallel to each other.
  • the microswitch arm is also formed of a flexible metal and is shorter than the microswitch carrier so as not to foul neutral pin 14. * It is provided at its free end with an electrical contact 39 which cooperates with a further, fixed, contact 40 which is in electrical connection with cold lead 3 via conducting strip.
  • the microswitch arm 32 is free to move towards or away from microswitch carrier 31 in order to make or break electrical connection between contacts 39 and 40.
  • Microswitch arm 32 itself has a tongue 41 in its central region which is connected to the remaining portion of the microswitch arm by a small region adjacent contact 39.
  • the free end of the tongue is adapted to locate against edge 36' of hole 36 and pivot thereagainst.
  • the arrangement is such that tongue 41 is in compression and tongue 35 is in tension.
  • the microswitch arm 32 and microswitch carrier 31 form an over-centre mechanism.
  • the over-centre mechanism operates by snap action to move contact 39 away from contact 40.
  • the position of the pivot point is varied by the use of adjustment spindle 18.
  • the distance which bimetal 34 must move in order to actuate the mechanism may be varied.
  • the distance moved by the end of the bimetal is, of course, dependent upon its temperature and therefore turning adjustment spindle 18 has the effect of varying temperature at which the contacts are disconnected from each other. Movement of the end of bimetal 34 back towards the head 1 which will occur as the bimetal cools down will, in turn, cause the contacts 39 and 40 to close thereby reconnecting neutral pin 14 to the cold lead.3.
  • the operation of the immersion heater and control unit will now be briefly described in the context of an electric water heating jug in which they may be mounted in a conventional manner.
  • the adjustment spindle 18 will be arranged to be accessible to the user via an opening in the outer shell of the jug.
  • the jug is connected to the electric mains supply using a conventional plug and lead.
  • adjustment spindle 18 When it is desired to keep the water within the jug simmering, or at a lower constant temperature, adjustment spindle 18 is turned clockwise to an appropriate position. Assuming that it is desired to cause the water to simmer at between 80° and 90 ⁇ C (for example for use in coffee making) the adjustment spindle is set accordingly and the jug is switched on. The water will rise in temperature and eventually stabilise within the desired range. In fact, since the heater head tends to increase in temperature more quickly than the water within the jug, it is likely that the microswitch will disconnect the element briefly one or more times before the desired temperature is reached.
  • Fig. 7 illustrates the temperatures of the water and the hot return when water is heated up in the simmer mode.
  • the thermally operated switch assembly has been adjusted to break connection between contacts 39 and 40 when the hot return reaches 100 ⁇ C and to remake connection when temperature of the hot return reduces to 80 ⁇ C.
  • the first time the element reached 100 ⁇ C the water temperature has not yet reached the desired temperature of 90°C. However, subsequently the water temperature oscillates between 80 and 90" as desired. Because the water has a much greater thermal capacity than the heater element, the water temperature varies by only 10 ⁇ C, whereas there is a 20 ⁇ C temperature differential between the break and remake temperatures of the control apparatus.
  • a considerably more consistent water temperature may be achieved.
  • FIG 8 which illustrates the rear of the control 50
  • apertures 51, 52 and 53 are provided for receiving the mounting studs of a typical immersion heater.
  • Neutral 54, earth 55 and line 56 pins project from the rear of the control in the standard configuration for connection to a normal socket assembly.
  • two terminals 57 and 58 which permit connection to an external steam operated control, and a control knob 9 whose function will be described below.
  • the opposite side of the control is illustrated in Figure 9.
  • the body of the control is formed from a main moulding 61 and a cover 63.
  • the cover is stepped midway along its length so that the lower part 62 of the cover, which, in use, abuts the heater head is flush with the top of the main moulding 61, and the upper part 63 is recessed.
  • the lower part of the cover has apertures 51', 52' and 53' which are aligned with those on the rear of the control for receiving the heater studs.
  • apertures 88,89 are provided for reserving the cold tanks of the heater.
  • Mounted on the face of the lower cover part is a disk shaped bimetal 64 which, in use, is held against a projecting portion of the heater head in order to provide good thermal contact therewith.
  • the bimetal is arranged to open a set of contacts located within the control by removal of a small push rod (not shown) to disconnect the supply current from the heater in the event of overheating, for example as a result of a vessel being switched on- whilst dry.
  • a dry switch on (DSO) bimetal is well known in the art.
  • a thermal fuse in the form of a meltable pin 65. As the control is clamped against a heater head, this pin is pressed into the body of the control, against the force of a biasing spring, and thereby holds a set of contacts closed.
  • the upper stud receiving opening of 51' in cover 62 is enlarged in order to accommodate one end of a creep bimetal 66 which is located around a copper collar 68.
  • the collar 68 is aligned with aperture 51 in the main moulding such that when the control 8 is mounted to heater head, the collar surrounds the upper stud of the heater and is pressed against the heater head.
  • two projections 69 which are formed integrally with the main moulding 61. They serve to locate and secure the bimetal 66 and the collar 68.
  • a conductive strip 70 extends towards the stud receiving aperture 53. Its distal end is provided with a screw receiving hole 53"so that when the control is mounted to a heater head, the conductive strip 70 is clamped against the respective heater stud by a mounting screw, thereby providing a secure earth connection.
  • a further conductive s ⁇ rip 71 which is in the form of a leaf spring is connected to live terminal 56.
  • the distal end of this strip is provided with a silvered contact 72 which is biased upwardly by the strip against a further contact 73 located on the lower side of a rigid conductive strip 74.
  • This strip is formed integrally with fixed contact carrier 75 which is part of the thermostat arrangement 90 which will be discussed below.
  • the strip 71 has a portion 71' on which the end of the push rod associated with the DSO bimetal may abut. Normally the biasing of this strip maintains contacts 72 and 73 closed, but in the event of over heating, the DSO bimetal will depress the push rod against portion 71' and thereby open the contacts 72,73.
  • thermostat arrangement is a further conductive leaf spring 77 having a cold tail contact portion 78 which is aligned with cold tail aperture 88 so that in use the cold tail contact 78 is biased against the respective cold tail of a heater.
  • a further conductive strip 79 is connected neutral terminal 54 and has a silvered contact 80 towards its distal end. This is biased upwardly against a further contact 81 on conductive leaf spring 82.
  • the central part of the leaf spring 82 is connected to main moulding 61 by means of pips 83 and its distal end forms the second cold tail contact 84 which is biased upwardly in alignment with cold tail aperture 89.
  • the strip 79 and leaf spring 82 form the connection between the neutral pin and the second cold tail of the heater.
  • Contacts 80 and 81 form part of the one shot protection system of the control.
  • a projection from the spring (not shown) which biases meltable pin 65 extends underneath leaf spring 82 such that when the spring is extended, conductor 82 is lifted away from conductor 79.
  • contacts 80 and 81 will remain open. It will be appreciated that if the pin 65 melts, as a result of serious overheating, this spring will be released and contacts 80 and 81 will be allowed to open, thereby permanently disconnecting a supply of current from the heater.
  • the assembly of the thermostat arrangement 90 is best understood from Figures 11 and 12.
  • the -eree bimetal 66 is mounted on collar 68. Since, in use, the collar is held around the upper stud of a heater and pressed against the heater head, this collar provides good thermal conductivity between the heater and the bimetal.
  • the bimetal may comprise a third payer of a high conductivity metal such as copper, thereby forming a "trimetal".
  • a push rod 92 which passes through an opening 93 in the upper part of cover 63. The other end of the push rod is received within an opening in a microswitch 94 located within the main moulding of the device.
  • microswitch 94 is attached to the main moulding 61 by means of a metal rivet 95 which passes through the cover and the main moulding. That end is also attached to an annular portion 91 of conductive strip 77 and thus the microswitch is directly connected to cold tail contact 78. A further portion of the conductive strip 77 extends beyond the rivet and into an opening 96 in the main moulding to form steam control terminal 58.
  • the rivet also passes through fixed contact carrier 75 and a ceramic spacer 97 which insulates the contact carrier 75 from the microswitch 94.
  • one end of the contact carrier 75 leads, via the DSO contacts 72,73 to the line terminal 56.
  • Two portions of the fixed contact carrier extend beyond the rivet, one of hese 98 is received within opening 99 in the main body and forms the second steam control terminal 57 and the other portion extends in the same direction as the microswitch and has on its lower face a silvered contact 100 which cooperates with a contact 101 on the microswitch. It will be appreciated from the foregoing that contacts 100 and 101 control the supply of current from line terminal 56 to cold tail contact 78.
  • the microswitch 94 is formed from a single conductive strip which is folded at its distal end to form two parallel parts: 102 which is held in place by the rivet, and 103 on which the movable contact 101 is mounted. Tongues 104,105 are formed in parts 102 and 103 respectively. Tongue 105, which is in compression, is engaged with tongue 104, thereby holding tongue 104 in tension.
  • the arrangement is such that if a pivot point is provided behind tongue 104 and the upper part of the microswitch is moved in the direction of the pivot point, whilst the pivot point prevents movement of tongue 104, at a certain point the movable contact 101 will be forced to snap away from fixed contact 100.
  • the movement of the upper part of the microswitch is caused by bending of creep bimetal 66 acting via push rod 92.
  • the pivot point is provided by the end of a grub screw 106 which is threadedly received within an insert 107 in the main moulding.
  • the distal end of the grub screw is tightly threadedly received within the adjustment spindle 59' which forms part of control knob 59.
  • the grub screw is caused to move towards or away from the microswitch 102, thereby varying the distance which the creep bimetal 60 must move in order to cause the contacts 100,101 to open in the manner previously described.
  • control 80 will be incorperated into an electrical water heating kettle or jug in the known manner by clamping it against the head of an immersion heater. A seal will be provided around the opening through which the heater is mounted in order to prevent leakage of water.
  • the water will start to cool down, which will cause the bimetal to straighten to the point where the contacts 100 and 101 snap closed again, and then the heater will be reenergised.
  • the heater will continue to cycle on and off in this manner, thereby maintaining the water at the desired temperature.
  • the position of the grub screw 106 relative to the adjustment spindle 59' may be preset when the vessel is manufactured in order to give a desired range of available temperature settings. It is envisaged that the maximum setting would be one which would allow a rolling boil.
  • a steam operated control across terminals 57 and 58.
  • Such a control would provide a non-cycling switch in parallel to the thermostat arrangement 90.
  • the jug or kettle could be set first to boil water and then to simmer or maintain the water at a lower temperature. This may be particularly useful in areas where the available water should be boiled before it is drunk.
  • the DSO bimetal In the event of overheating, the DSO bimetal will operate in the well known manner. In the event that this fails, the thermal fuse arrangement will permanently disable the control, again in a well known manner.

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  • Thermally Actuated Switches (AREA)

Abstract

L'invention concerne un thermoplongeur électrique et un dispositif de commande intégré (50) pour une bouilloire ou un broc électrique comportant un élément bimétallique ou trimétallique (60) de fuite . Ce dernier est placé en contact thermique avec la tête du thermoplongeur via une collerette de cuivre (68) placée autour de la tige du thermoplongeur. L'élément bimétallique ou trimétallique agit sur un microinterrupteur à action rapide (94) qui commande un ensemble de contacts (100, 101) en série avec le thermoplongeur. Ce microinterrupteur (94) coopère avec un point de pivotement qui peut se déplacer au moyen d'une poignée de commande (59) afin de faire varier la température de l'eau à laquelle les contacts sont ouverts. Le microinterrupteur est placé pour fermer les contacts lorsque la température de l'eau tombe à une valeur inférieure à cette température de sorte que le cycle du thermoplongeur se poursuit.
PCT/GB1995/000056 1994-01-13 1995-01-12 Appareil de chauffage de l'eau WO1995019129A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU13901/95A AU1390195A (en) 1994-01-13 1995-01-12 Water heating apparatus
GB9615225A GB2301226B (en) 1994-01-13 1995-01-12 Control units for water heating apparatus

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9400543A GB9400543D0 (en) 1994-01-13 1994-01-13 Water heating apparatus
GB9400543.6 1994-01-13

Publications (1)

Publication Number Publication Date
WO1995019129A1 true WO1995019129A1 (fr) 1995-07-20

Family

ID=10748717

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1995/000056 WO1995019129A1 (fr) 1994-01-13 1995-01-12 Appareil de chauffage de l'eau

Country Status (4)

Country Link
AU (1) AU1390195A (fr)
GB (2) GB9400543D0 (fr)
WO (1) WO1995019129A1 (fr)
ZA (1) ZA95259B (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2307602A (en) * 1995-11-27 1997-05-28 Otter Controls Ltd Mounting protection control and connector of appliance heater
WO1997024966A2 (fr) * 1996-01-11 1997-07-17 Delta Theta Limited Bouilloire de menage
GB2327180A (en) * 1997-07-15 1999-01-20 Andrew Nicholas Graham Electric kettle to selectively heat or boil water
RU188756U1 (ru) * 2018-11-26 2019-04-23 Дмитрий Сергеевич ХВАЛЕНСКИЙ Электрический самовар
CN109864576A (zh) * 2017-12-04 2019-06-11 九阳股份有限公司 电水壶
RU198388U1 (ru) * 2019-12-03 2020-07-02 Общество с ограниченной ответственностью "ПластМет" Электрический самовар

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2363908B (en) * 1997-11-28 2002-03-06 Otter Controls Ltd Improvements relating to thermally-responsive actuators
CN1274269C (zh) * 2003-12-11 2006-09-13 邵志成 温控开关、电热水壶及无绳电热水壶
GB2422770A (en) * 2005-02-08 2006-08-09 Chow Hung Electric boiler

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2507050A1 (fr) * 1981-05-28 1982-12-03 Ti Russell Hobbs Ltd Corps de chauffe electriques a immersion et appareils chauffe-liquides contenant de tels corps de chauffe
EP0202939A2 (fr) * 1985-05-22 1986-11-26 Otter Controls Limited Eléments de chauffage électrique à immersion et dispositifs de commande pour ces éléments
GB2220547A (en) * 1988-07-06 1990-01-10 Strix Ltd Electric immersion heaters
EP0380369A1 (fr) * 1989-01-26 1990-08-01 Otter Controls Limited Commande pour éléments chauffants à alimentation électrique
EP0510863A2 (fr) * 1991-04-22 1992-10-28 Otter Controls Limited Commande pour appareils de chauffage d'eau
EP0528656A1 (fr) * 1991-08-12 1993-02-24 Strix Limited Bouillaires
EP0624998A1 (fr) * 1993-05-11 1994-11-17 CANDY S.p.A. Dispositif de sécurité pour éléments de chauffage dans les appareils domestiques où la température est régulée

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2507050A1 (fr) * 1981-05-28 1982-12-03 Ti Russell Hobbs Ltd Corps de chauffe electriques a immersion et appareils chauffe-liquides contenant de tels corps de chauffe
EP0202939A2 (fr) * 1985-05-22 1986-11-26 Otter Controls Limited Eléments de chauffage électrique à immersion et dispositifs de commande pour ces éléments
GB2220547A (en) * 1988-07-06 1990-01-10 Strix Ltd Electric immersion heaters
EP0380369A1 (fr) * 1989-01-26 1990-08-01 Otter Controls Limited Commande pour éléments chauffants à alimentation électrique
EP0510863A2 (fr) * 1991-04-22 1992-10-28 Otter Controls Limited Commande pour appareils de chauffage d'eau
EP0528656A1 (fr) * 1991-08-12 1993-02-24 Strix Limited Bouillaires
EP0624998A1 (fr) * 1993-05-11 1994-11-17 CANDY S.p.A. Dispositif de sécurité pour éléments de chauffage dans les appareils domestiques où la température est régulée

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2307602A (en) * 1995-11-27 1997-05-28 Otter Controls Ltd Mounting protection control and connector of appliance heater
GB2307602B (en) * 1995-11-27 2000-07-12 Otter Controls Ltd Improvements relating to electrically powered liquid heating appliances and controls therefor
WO1997024966A2 (fr) * 1996-01-11 1997-07-17 Delta Theta Limited Bouilloire de menage
WO1997024966A3 (fr) * 1996-01-11 1997-09-12 Delta Theta Ltd Bouilloire de menage
GB2327180A (en) * 1997-07-15 1999-01-20 Andrew Nicholas Graham Electric kettle to selectively heat or boil water
CN109864576A (zh) * 2017-12-04 2019-06-11 九阳股份有限公司 电水壶
CN109864576B (zh) * 2017-12-04 2021-02-02 九阳股份有限公司 电水壶
RU188756U1 (ru) * 2018-11-26 2019-04-23 Дмитрий Сергеевич ХВАЛЕНСКИЙ Электрический самовар
RU198388U1 (ru) * 2019-12-03 2020-07-02 Общество с ограниченной ответственностью "ПластМет" Электрический самовар

Also Published As

Publication number Publication date
GB9615225D0 (en) 1996-09-04
GB2301226B (en) 1998-04-22
AU1390195A (en) 1995-08-01
ZA95259B (en) 1996-07-15
GB9400543D0 (en) 1994-03-09
GB2301226A (en) 1996-11-27

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