Abstract:
An electric beverage maker includes a lower, water boiling vessel, a funnel extending into the lower vessel and having an upper compartment for receiving a beverage, and an upper vessel mounted over the funnel to receive water which has passed up the funnel through the compartment, and from which the beverage is dispensed. The lower vessel is formed with an opening in its lower region, which is closed by a thick film electric heater. The heater is controlled by a control which operates to disable the heater until such time as the control is reset manually by a user.

Description:
This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in United Kingdom Patent Application No. 0103658.1 filed on 14 Feb. 2001. 
   BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention relates to electric beverage makers in general, and in particular but not exclusively to electric coffee makers. 
   2. Background Information 
   One traditional form of coffee maker is a so-called espresso maker which comprises a lower vessel in which water is heated, a funnel extending into the lower vessel and whose upper part holds coffee grounds, and an upper vessel mounted to the lower vessel and which receives heated water which has passed up the funnel and through the coffee grounds. In use, as water in the lower vessel is heated and boiled, it is forced under pressure up the funnel, through the coffee grounds and a strainer arranged on top of the coffee grounds into the upper vessel, from where it is poured. 
   Traditionally such coffee makers are of metal and have been heated by being placed on an electric or gas stove. More recently, however, it has been proposed, for example in PCT International Publication No. WO 00/45686, to heat the water in the lower vessel by an integrated electric heater. 
   DISCLOSURE OF THE INVENTION 
   The present invention seeks to provide an improved beverage maker of this kind. From a first aspect, therefore, the invention provides an electric beverage maker comprising a lower, water boiling vessel, a funnel extending into the lower vessel and having an upper compartment for receiving a beverage, and an upper vessel mounted over said funnel to receive liquid which has passed up said funnel through said compartment, and from which the beverage is dispensed, characterized in that said lower vessel is formed with an opening in its lower region, and in that an electric heater is mounted to close said opening thereby forming a heating base for the lower vessel. 
   Thus in accordance with the invention, manufacture of this type of beverage maker is facilitated by providing a heater which can be mounted to close an opening in the heating vessel wall. This is fundamentally different from prior art arrangements in which the heater has, in some way, been integrated in the base of the vessel. 
   The lower vessel may be metallic, but preferably it is of plastics. This is advantageous in that it considerably simplifies and reduces the cost of manufacture of the beverage maker, allowing the vessel to be molded. 
   Preferably, the lower vessel has side walls which extend down below the opening so as to form a skirt for shrouding the heater and any associated control. Again, this is a significant advantage over prior art arrangements in which separate shrouds are provided as it means that both the vessel and the shroud can be produced in a single molding operation. 
   Preferably the upper vessel is molded to further reduce manufacturing costs. 
   The heater which is arranged in the base of the lower, water heating, vessel may be of any convenient type, for example, a planar heater having heating means provided in, or on, its underside. Such means may comprise a sheathed electric heating element suitably secured to the heating plate, e.g. via a heat diffusion plate, or a cast element (i.e. a heater having a cast-in sheathed heating element). Preferably, however, the heater comprises a thick film printed element. 
   Preferably the heater is provided with an unheated region thereof which is arranged in use to lie directly beneath the funnel. This is advantageous in that it prevents water directly beneath the funnel from boiling while the bulk of the water is being heated to boiling. The Applicant has recognized that it is undesirable for water beneath the funnel to boil too early as this could cause steam to rise up the funnel and scald the beverage, such as coffee, before it is properly wetted. This applies equally for thick film heaters and for elements mounted under the base of a vessel. 
   The heater may be secured in the opening in the base of the lower vessel in any convenient manner. For example, the heater may be secured via a peripheral gripping channel, as described in PCT International Publication No. WO 96/18331. Preferably, however, the heater is provided with a peripheral flange which is urged upwardly to secure the heater in place. This is advantageous in that it acts to counteract pressure which is developed in the lower vessel during heating. 
   Preferably the heater is supported by the housing of an associated control. Most preferably, the arrangement is similar to that shown in FIGS. 1 to 7 of PCT International Publication No. WO 99/48331. These figures show the principle of operation of the Applicant&#39;s U36 and U38 series of controls and elements. In particular, a snap acting bimetallic actuator is biased lightly into contact with an associated heater and acts to lift a leaf-spring mounted contact from a corresponding contact provided on the heater in the event of the heater rising above a predetermined temperature. Such a heater/control combination may be used in a beverage maker of the present invention, as it will sense when the liquid in the lower vessel has been boiled away, and then operate to disconnect power to the heating element. 
   In the arrangement described in PCT International Publication WO 99/48331, the control cycles, i.e. it will reconnect power to the heater after the heater has cooled. In the present invention, however, it is preferable that once the control operates, it does not cycle, but rather disconnects the power until the control is reset by a user. Preferably, therefore, the control used in the appliance of the present invention comprises a thermally sensitive actuator which acts to open a set of contacts when the liquid in the lower vessel has been boiled away, and further comprises means for maintaining those contacts open until such time as reset by a user of the appliance. 
   This broad concept which will find application in all electric coffee makers of the kind described, so from a further aspect the invention provides an electric beverage maker comprising a lower, water boiling, vessel, a funnel extending into the lower vessel and having an upper compartment for receiving a beverage, an upper vessel mounted over said funnel to receive liquid which has passed up said funnel through said compartment and from which the beverage is dispensed, and electric heating means associated with said lower vessel for heating water in said lower vessel characterized in that said beverage maker further comprises a thermally sensitive control for disconnecting the electrical supply to said heater when the water in said lower vessel substantially boils away, and means for manually resetting said control to allow said heater to be re-energized. 
   It is also preferred in accordance with this aspect of the invention that the heater is provided with an unheated region arranged directly beneath the funnel. 
   The control need not take the particular form described above, and in a simple embodiment may comprise a separate thermostatic switch sensitive to the temperature of the heater or vessel base and which will operate when a predetermined temperature is reached. What is important is that the switch should not reset automatically, but should only be resettable by a user. 
   As described above, the control will usually comprise a thermally sensitive bimetallic actuator. In one embodiment of the invention, the actuator may be of the type which has a reset temperature which is significantly below normal ambient temperatures so that during normal use it will not reset automatically. A suitable mechanism may be provided to reset the mechanism manually when needed. 
   In another embodiment, the movable contact may be mounted on a bi-stable contact arm which, once it has been moved to its open position can only be returned to its closed position by a manual reset mechanism. 
   In a further embodiment, the movable contact may be latched open after operation of the bimetallic actuator, and a manual latch release mechanism be provided. 
   The latch may comprise a catch and a resilient latch member which engages the catch to latch the contact open. The catch may be fixed, but preferably it is associated with the movable contact. 
   Preferably the resilient latch member comprises an elongate leaf or wire spring, and the latch release mechanism comprises a release member for deflecting said resilient latch member out of engagement with said catch. With such arrangements, the release member is advantageously returned to its original position by the latch member thereby obviating the need for a separate return spring. 
   A lamp or other indicator may be provided which is illuminated either while the liquid is heating, or after the control has operated, thereby indicating that the beverage is ready. 
   The heating base of the lower vessel is preferably arranged to slope and the actuator of the control arranged at an upper part of the base. 
   These and other objects, features, and advantages of the present invention will become apparent in light of the detailed description of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Some preferred embodiments of the invention will now be described with reference to the accompanying drawings in which: 
       FIG. 1  shows a sectional view through a coffee making appliance in accordance with the invention. 
       FIG. 2  shows an exploded view of the components of the appliance of  FIG. 1 . 
       FIG. 3  shows an exploded view of the lower vessel of  FIGS. 1 and 2 . 
       FIG. 4  shows, schematically, the mounting arrangement and various operative components of the control of the appliance of  FIGS. 1 to 3 . 
       FIG. 5  shows the actuator and contact arrangement of  FIG. 4  in plan view. 
       FIG. 6  illustrates, schematically, a first react mechanism. 
       FIG. 7  shows a second reset mechanism. 
       FIG. 8  shows a third reset mechanism. 
       FIG. 9  shows a further reset mechanism for use in an appliance in accordance with the invention. 
       FIG. 10  shows a yet further reset mechanism in accordance with the invention. 
       FIG. 11  shows a view of the underside of a thick film electric heater. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIGS. 1 to 3 , a coffee making appliance  2  in accordance with the invention comprises three main components: a lower, water boiling, vessel  4 , an upper beverage receiving vessel  6  and an intermediate funnel  8 . The upper and lower vessels  6 ,  4  are of a molded plastics construction, while the funnel is metallic. 
   The upper vessel  6  is provided with a skirt  10  provided with an inwardly facing screw thread  12  which engages with a complementary screw thread  14  provided on the upper neck  16  of the lower vessel  4 . The upper vessel  6  is also provided with an upwardly extending spout  18  with apertures  20  at its upper and through which boiled water enters the upper vessel  6 , as will be discussed further below. The upper vessel  4  is also provided with an inwardly facing flange  22  for receiving a seal  24 . As can be seen from  FIG. 1 , when assembled, the seal  24  is trapped between the flange  24  on the upper vessel  6  and the upper end  26  of the lower vessel  4 . 
   The funnel  8  is provided with a peripheral flange  28 , which rests upon the upper edge  26  of the lower vessel  4 . A strainer  30  is provided integrally in the funnel  8  for retaining a charge of coffee  32  and a removable filter plate  33  arranged on the top of the charge  32  to prevent grounds being carried into the upper vessel  6 . 
   The lower vessel  4  is provided with an inwardly extending flange  34  towards it lower end, the flange defining a opening  36  in the lower part of the vessel  4 . The wall of the lower vessel  4  extends downwardly below the flange  34  to form a skirt  38 . A heater  40  is mounted to close the opening  36 . A safety pressure valve (not shown) is provided in the wall of the lower vessel  4 . 
   The heater  40  is a thick film printed element, and is shown in greater detail in  FIG. 11 . As is known in the art, the heater  40  comprises a thick film resistive heating track  150 , laid on an insulating substrate  152  which is provided on a 0.8 mm thick stainless steel plate. The heating track  150  is terminated by a pair of low resistance contact portions  156 . It will also be noted, however, that the resistive track  150  is provided generally only around the periphery of the heating plate. This leaves an unheated area  158  in the center of the heater which is beneath the funnel  8 . 
   The heater  40  is associated with a control unit  42 . The control unit  42  is an adaptation of the Applicant&#39;s commercially available U36 control which is a thermally-sensitive overheat protection control normally used in kettles and which incorporates a 360° cordless connector  44  for engagement with a corresponding connector on a power base (not shown). The principles of operation of such a control are described in PCT International Publication WO 99/48331. 
   As can be seen from  FIG. 1 , the central, planar, part of the heater  40  is arranged to slope in one direction, in fact at about 3° to the horizontal. 
   As shown schematically in  FIG. 4 , the control  42  includes a molded control body  42 , which receives the heater  40 , clips (not shown) being provided around the inner periphery of the control molding  44  to hold the heater  40  in place on the control unit prior to its assembly into the appliance. The flange  34  of the vessel body  4  is provided with a number of bosses  46  which extend into bores  48  provided in the molding  44 , the peripheral flange  50  of the heater being scalloped in the region of these bores in order to allow for the passage of respective fixing screws  52 . A seal  54  is provided around the flange  50  of the heater, and when the control  42  and heater  40  are mounted to the vessel body  4  as a subassembly, the seal  54  is compressed against the flange  34  to make a water-tight seal around the heater  40  to prevent water entering the control  42 . 
   As shown schematically in  FIGS. 4 and 5 , the control comprises a thermally sensitive bimetallic actuator  60  mounted on one arm  62  of a generally U-shaped leaf spring member  64 . The other arm  66  of the member is provided at its free end with a contact  68  which makes electrical connection with a contact  72  provided on the heater  40 . The cross limb  74  of the member  64  is connected to one side of the electrical supply to the control, e.g. being connected to the line or neutral terminal of the connector  44 . A tongue  76  is upstanding from the arm  66  so as to underlie a peripheral region  78  of the actuator  60  whereby when the actuator operates it will push down the arm  66  and thereby open the set of contacts  70 ,  72 . 
   In a conventional kettle, the actuator  60  will detect overheating of the kettle, for example when it boils dry or it is turned on without any water in it. In the context of the present invention, however, boiling dry of the lower vessel  4  will indicate that all, or a substantial part of, the water has been evaporated from the lower vessel  4  and that the heater  40  can then be turned off. In fact, the actuator  60  is arranged under an upper part of the sloping heater  40  such that that part of the heater  40  becomes exposed before all the liquid has evaporated away. This is advantageous in helping ensure that the periphery of the heater  40  and the surrounding vessel body does not overheat. 
   The conventional U36 control is configured such that it will cycle, i.e. it will allow the contacts  70 ,  72  to reclose after the heater  40  has cooled. However, this is not desirable in the case of the present invention. Accordingly, a mechanism is provided whereby once the actuator  60  operates to open the contact  70 ,  72  the contacts will be held open. 
   A number of different mechanisms to achieve this are disclosed herein. In a first arrangement, shown in  FIG. 6 , the bimetallic actuator  60  is chosen such that it is a non-self resetting actuator, i.e. the actuator  60  will only revert to its original position (and thus allow re-energization of the appliance heater) after operation either when the temperature falls significantly below ambient temperature or when it is physically reset by a user. A reset mechanism suitable for this purpose is shown in  FIG. 6 . 
   In this embodiment, a reset plunger  80  is mounted in a bore  82  in the control molding  44 . The lower end  84  of the plunger  60  is angled and rests upon a spring loaded button  86  which extends through an aperture  88  in the side wall of the molding  44  and also through an aperture  90  in the skirt  38  of the lower vessel  4 . When it is desired to reset the control after it has operated (in which situation the components will assume the positions shown in phantom in  FIG. 6 ), the button  86  is pressed inwardly, causing the plunger  80  to move upwardly under a camming action so as to contact the periphery of the actuator  60  and so force it to return to its original configuration, thereby allowing the contacts  70 ,  72  to reclose. When the button  86  is released, it returns to its original position under the action of the spring  90  and the plunger  80  will return to its original position under its own weight. 
   An alternative mechanism is shown in  FIG. 7 . In this embodiment, the reset button  92  acts on a lever arm  94  which is pivotally mounted to the molding  44 . A spring  96  is arranged on a spigot  98  provided on the lever  94  to provide a return force on the button  92 . When the button  92  is pressed, the lever  94  will rotate anti-clockwise such that its free end  100  will engage the periphery of the actuator  60  in order to force it back towards its original position. 
   In a yet further embodiment, shown in  FIG. 8 , a spring loaded button  102  is provided with a cam surface  104  at its free end such that when the button  102  is pressed the upper most part of the cam surface  104  moves into contact with the periphery of the actuator  60  in order to reset it. 
   Other reset mechanisms are also envisaged. A further embodiment is shown schematically in  FIG. 9 . In this embodiment, the actuator  60  is, instead, a conventional auto-resetting actuator which will return to its original configuration after cooling to a temperature around or above ambient. In this arrangement, however, the end of the contact carrying arm  66  is provided with a latch  110  which, when the contacts  70 ,  72  are opened under the action of the actuator  60 , engages behind a catch  112  provided on the control molding  44  to retain the contacts  70 ,  72  open even after the actuator  60  has returned to its original configuration. When the spring loaded reset button  114  is pressed, the latch  110  is disengaged by the free end  116  of the button  114  bending the resilient arm  66  back to disengage the latch  110  from under the catch surface  102 , thereby allowing the contacts to return to their closed position. 
   In a further, similar, arrangement shown in  FIG. 10 , the end  120  of the contact carrying arm  122  is provided with a depending catch  124 . The lower edge  126  of the catch  124  is sloped, as shown. 
   A wire spring  128  which is fixed in the control housing  130  at one end  132  extends across the control housing  130  below the sloped edge  126  of the catch  124 . The other end  134  of the spring  128  is free to deflect. 
   A button  140  extends through the wall  142  of the control housing  130  and has a free end  144  which in its rest position is abutted by the spring  128 . 
   When the bimetallic actuator  146  operates it will move contact arm  122  downwardly causing the sloping edge  126  of the catch  124  to engage the spring  128  and push it to one side until the contact arm  122  has fully deflected, whereupon the spring  128  will move back under its own resilience to engage the catch  124  thereby preventing the contact arm  122  returning to its rest position even after the bimetallic actuator  146  has reset. To reset the contact arm  122 , the button  140  must be pressed in to deflect the spring  128  out of the catch  124 . After it has disengaged, the spring  128  will act to return the button to its rest position. 
   Operation of an appliance in accordance with the invention will now briefly be described. Firstly, a desired volume of water is placed in the lower vessel  4 . This volume can be pre-measured or gauged from volumetric marks (not shown) provided on the inside of the vessel wall. 
   The funnel  8  is then filled with coffee grounds  32  (or other foodstuffs) until it is level with the rim and the strainer filter plate  34  used to tamp down the coffee. It is then rested on the top of the grounds  32 . If desired, a false floor can be placed in the funnel  8  before filling to take up some of the volume, whereby the amount of coffee or other foodstuff can be varied in order to vary the strength or the volume of the beverage produced. 
   The funnel  8  is then placed in position on the lower vessel  4  and the upper vessel  6 , which carries the seal  22 , then screwed onto the upper end  16  of the lower vessel  4  so as to seal the lower vessel  4 . The whole appliance is then placed on its power base (not shown) and the reset button  86  etc pressed to supply power to the heater  40 . 
   The water in the lower vessel  4  is then heated to a point where steam vapor is generated which creates a pressure in the lower vessel  4 . This forces the water from the lower vessel  4  up through the funnel  8 , through the coffee grounds  32 , where it infuses with the coffee, up the spout  18  and out of the apertures  20  formed in the spout  18  of the upper vessel  6 . By virtue of the unheated area  158  beneath the funnel  8 , water directly below the funnel  8  does not boil during the bulk water heat-up phase. This prevents the coffee grounds  32  being scalded by steam until properly wet. This improves the flavor of the brewed coffee. 
   Once the majority of the water has been pushed out of the lower vessel  4  through the funnel  8 , the temperature of the heater  40  will begin to rise, and this rise will be detected by the actuator  60  of the control  42 . In particular, the actuator  60  of the control will operate to open the contact  70 ,  72  thereby disconnecting the power supply to the heater  40  when the area of the heater  40  under which it is arranged boils dry. The contact  70 ,  72  are then maintained open by one of the various mechanisms described in  FIGS. 6 to 10  in order to stop the heater  40  re-energizing. 
   The appliance can then be lifted and the beverage dispensed from the upper vessel  6 , whereafter the upper vessel  6  may be unscrewed from the lower vessel  4 , the funnel  8  removed and the appliance cleaned. The process will then be repeated to prepare a new beverage, the act of pressing the reset button  86  allowing the contacts  70 ,  72  to reclose in order to supply power once more to the heater  36 . 
   It will be appreciated that various modifications can be made to the preferred embodiments of the invention described above without departing from the scope of the invention. For example, controls other than those specifically described may be used, so long as they detect overheating of the heated base vessel. Furthermore, other latching mechanisms may be envisaged for holding open the contacts of a control upon operation. Furthermore, the invention is not limited to the use of thick film printed elements, but can be used with electric heating elements suitably mounted under the base of the vessel. Also, the appliance need not be cordless, as shown and the appliance may be adapted to make other beverages such as soup. 
   Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the invention.