Foods and beverages: apparatus – Beverage – Infusors
Reexamination Certificate
2002-02-12
2003-06-17
Alexander, Reginald L. (Department: 1761)
Foods and beverages: apparatus
Beverage
Infusors
C099S292000, C099S303000
Reexamination Certificate
active
06578467
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to electrical beverage making appliances and in particular, but not exclusively to electric coffee makers.
A known type of coffee maker beverage type is known which comprises two chambers: a first chamber for receiving water to be heated; and a second chamber which is seated on top of the first chamber and which receives the coffee grounds. The second chamber is in fluid communication with the first chamber through a water transfer pipe which extends down from the second chamber into the first chamber. A separator arranged at the top of the water transfer tube allows water to flow into and out of the upper chamber while retaining the coffee grounds. In use, the liquid in the first chamber is heated externally, for example by a gas or spirit flame or an electric element arranged under the chamber. As water in the first chamber heats, the pressure in that chamber increases causing the water in the first chamber to rise up through the transfer pipe into the second chamber where it infuses with the coffee grounds. Eventually, the level of liquid in the first chamber falls below the bottom of the tube, and transfer of liquid stops. The heating is then discontinued and the first chamber then cools so that steam will begin to condense on the inside of the lower chamber. When it does so, a partial vacuum is created in the first chamber which causes infused beverage to be sucked back down the tube through the separator into the first chamber. When all the beverage has been sucked down into the first chamber, the second chamber can be removed and the beverage be served from the first chamber.
Such an appliance is disclosed in GB 1,332,656. In that appliance, an electric heating element or a gas flame is arranged under the first chamber and controlled by a thermally responsive actuator arranged in the second chamber. The actuator senses the temperature of the atmosphere in the second chamber and when it reaches a predetermined temperature either discontinues the electrical supply to the heating element or operates a valve in the gas supply to the gas flame.
One problem with the above arrangement is that it is difficult and expensive as the actuator is arranged remotely from the heating source which means that connections have to be made between the two. This results in unsightly and unnecessary housings or shrouds being provided in the apparatus and unnecessary expense. A further problem is that the heating of liquid in the first vessel is slow and inefficient and after the sensor has cut off the element considerable amounts of heat continue to flow from the heater into the apparatus.
DISCLOSURE OF THE INVENTION
The present invention seeks to overcome the above problems, and from a first aspect, therefore, provides a beverage maker comprising:
a first chamber;
a second chamber arranged on top of said first chamber;
a tube extending down from said second chamber into said first chamber for transferring liquid between the two chambers; wherein:
the base of said first chamber is provided with electric heating means and thermally responsive control means are provided associated with the said base so as to be responsive to the temperature of the heating means or a section of the base for interrupting the power supply to or reducing the heating output of the heating means.
Thus in accordance with the invention, the base of the first chamber is provided with electrical heating means and power to the heater is interrupted or the heating output thereof substantially reduced in response to the heater or a portion of the base reaching a predetermined temperature. This stops, or at least substantially reduces heating of the liquid in the lower chamber, so as to stop boiling. The first chamber then cools, water begins to condense on the wall of the first chamber and transfer of infused beverage from the second chamber will commence.
This arrangement allows the liquid in the first chamber to be heated efficiently, accurate control to be achieved and obviates the need for unsightly and cumbersome electrical connections between the first and second chambers.
The control means of the invention may be arranged to operate in one of a number of ways. In a first embodiment, the control means is configured and arranged so as to detect when a portion of the base of the first chamber boils dry, which indicates that a predetermined amount of the liquid in the first chamber has been transferred to the second chamber. This condition can easily be detected by a suitable thermal sensor in thermal contact with the base or the heater since in the absence of water which cools the base or heater, the temperature of the base or heater will rise very quickly.
In an arrangement as described above, preferably only a specified portion of the base or heater boils dry, such that water still covers the remainder of the base.
This may be achieved in a number of ways. For example the base or heater may be provided with a locally raised region which boils dry. This region could, for example be formed as a raised region of a heater plate such as is disclosed in Applicant's GB 2,316,847 to which reference can be made for further detail. A suitable sensor may then be arranged under the raised region which will become exposed in advance of the remainder of the base.
In an alternative arrangement, the base or heater of the first chamber may be generally planar, but arranged to slope such that a peripheral region thereof will become exposed and overheat as the liquid level in the first chamber drops as liquid is transferred to the second chamber. A suitable sensor may be arranged under that part of the base or heater.
Preferably, however, the base is provided with a region which is separated from the remainder of the region by a raised wall. Most preferably, the wall surrounds the entire heated region of the base. This wall forms a reservoir of water above the heater in the base, and it will be appreciated that the higher is this wall, the longer it will take for water within the reservoir to evaporate, and thus for the control to operate. This allows a mechanism by which the beverage infusion time can be varied since that is dependent upon how long the water remains in the second chamber. This is, in turn dependent upon maintaining the pressure in the first chamber, which in turn depends on the continued boiling of liquid in the first chamber. Thus in a preferred embodiment, the wall is adjustable in height to allow for adjustment of the beverage infusion time.
A further way in which the infusion time can be varied is by varying the power of the heating element. If the element is heats at low power, then it will take longer for the liquid in the reservoir to boil away, thereby maintaining the vapour pressure in the first chamber for a longer period, thereby keeping the hot water in the second chamber infusing for a longer period of time. Conversely, if the element heats at high power, then liquid in the reservoir will boil away more quickly, thereby reducing the infusion time. In one embodiment of the invention therefore, means may be provided for varying the power of the heating element. Means for achieving such a power variation will be readily conceivable by the skilled person and are thus not described in further detail here.
A yet further way in which the infusion time could be varied would be to have an additional heater which heats a portion of the base which would still be covered by water after the main heating element has been switched off. This element need not be particularly high power, say 50 W, but even at that low power it would generate sufficient vapour to maintain the vapour pressure in the first chamber. The additional heater could be switched off after a predetermined time to bring the infusion period to an end.
In the embodiments described above, the temperature of the base or heater can be sensed in any convenient manner. Preferably, however, the temperature is sensed using a thermomechanical sensor such as a bimetallic actuator arranged in good ther
Donnelly Vernon James
Taylor John Crawshaw
Alexander Reginald L.
McCormick Paulding & Huber LLP
Strix Limited
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