GB2536000A

GB2536000A - An electric liquid heating appliance

Info

Publication number: GB2536000A
Application number: GB1503451.5A
Authority: GB
Inventors: Kostka Pavel
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-03-01
Filing date: 2015-03-01
Publication date: 2016-09-07
Also published as: WO2016138968A1; GB201503451D0

Abstract

An electric liquid-heating appliance powered from mains electricity comprising a receptacle 102 configured for reception of a liquid, a heater 104 adapted for heating the liquid, and a controller 110 including a supercapacitor 112 chargeable from the mains electricity. The controller is configured to energize the heater either from the supercapacitor, from the mains electricity, or simultaneously from both sources. The supercapacitor can he configured to store energy in a range of 10 - 1000 W.h. The appliance can be an electric kettle with a supercapacitor configured to store energy in a range of 10-200 W.h The controller can be also configured to energize the heater adaptively according to the temperature of the heater. The appliance can also further comprise an agitator for agitation of the liquid to be heated.

Description

TITLE OF THE INVENTION

An Electric Liquid Heating Appliance

TECHNICAL FIELD

The present invention relates to the field of electric appliances arranged to heat liquids.

BACKGROUND OF THE INVENTION

Yamamura Teruhiko discloses in patent document JP2008281296 an electric cooker that includes a rechargeable battery. An electronic logic of the cooker allows to energize a heater, having a couple of heating elements, simultaneously from the battery and mains electricity Such configuration reduces time needed for heating. Significant obstacle of that approach lies in the fact that batteries have limited amount of charging cycles, typically not extending far beyond ones of thousands of cycles with a substantially deteriorating capacity curve. The cooker is typically used regularly several times a day. The limit in amount of charging cycles thus hinders commercialization of such solution. For instance, if the cooker was used 5 times a day, its battery couldn't sustain longer than approximately one year. That would not he acceptable for a cooker that costs above average in its category due to the cost of the battery and accompanying logic. Limited charging speed of nowadays batteries poses yet another problem as it can take an hour or even ones of hours before such battery is ready for a next heating cycle.

Despite of all these issues, any improvement in duration of common daily processes represents a commercially viable area. Thus, there remains a need for devices that would allow to accelerate these processes so that such devices are not only faster but also reliable enough for use over a sufficiently long period of time.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to an electric liquid heating appliance operable on mains electricity More particularly the appliance comprises a receptacle configured for reception of a liquid, a heater adapted for heating the liquid, and a controller including a supercapacitor chargeable from the mains electricity wherein the controller is configured to energize, in use, the heater from the supercapacitor.

According to one preferred configuration, the supercapacitor is configured to store energy in a range of I 0 -1000 W.h.

According to another preferred configuration, the controller is configured to energize the heater simultaneously from the supercapacitor and from the mains electricity.

The appliance can be an electric kettle having the supercapacitor configured to store energy in a range of 10 -200 W.h.

The appliance can further comprise a temperature sensor configured for measuring temperature of the heater and the controller can be configured to energize the heater adaptively according to the temperature of the heater.

The appliance can further comprise an agitator configured for agitating the liquid.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood from the following description given by way of example only, with reference to the accompanying figures.

Fig. 1 is a schematic view of an electric liquid-heating appliance according to the present invention. Fig. 2 is a block electric diagram of the appliance shown in Fig. 1.

Fig. 3 is a schematic view of an alternative appliance according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 is a schematic view of an electric liquid-heating appliance according to the present invention. The appliance comprises a receptacle 102, a heater 104, a controller 110 that includes a supercapacitor 112, a mains-power-supply connector 114, and a temperature sensor 116. The heater 104 comprises a heating element 106 and a heating element 108, implemented e.g. as resistive heating elements. The receptacle 102 is configured for reception of a liquid, i.e. it can be either user's fillable (so that a user can fill it with liquid e.g. from a tap) or the appliance can be attached to a liquid source, e.g. to a water pipe. The heater 104 is adapted for heating the liquid, i.e. it is for instance disposed at the bottom of the receptacle 102 so that it is soaked, in use, in the liquid as hinted in the Fig. 1. Alternatively, the heater 104 can he attached to a wall of the receptacle 102.

Fig. 2 is a block electric diagram of the appliance shown in Fig. I. it comprises the connector 114, the temperature sensor 116, the heater 104 having the heating elements 106 and 108, and the controller 110. The controller 110, further comprises a step-down power supply 118, a constant current source 120, a control panel 122, a relay 124, a MOSFET-based switch 126 (metal-oxide-semiconductor field-effect transistor), a diode III, a microcontroller 128 and (numbered) wires 130, 132, 134, 136 and 138.

The supply 118 is a common step-down power supply -e.g. a switched-mode one. Current/voltage operating values of the supply 118 are chosen with regard to the capacity, maximal rated voltage, and desired time of charging of the supercapacitor 112, typically tens of volts and ones to tens of amperes. The constant current source 120 is an example of one of many ways how to charge the supercapacitor 112. It can be realized e.g. by LT®3741 circuit from Linear Technology'. The supercapacitor 112 can be of any type, e.g. a double-layer capacitor, pseudocapacitor or a hybrid-type of capacitor, preferably selected with regard to the power density -the higher, the better. The supercapacitor 112 can be internally composed of one or more supercapacitor modules connected in series, in parallel or as a combination thereof. As an example, BOOSTCAP ultracapacitor from Maxwell® Technologies or ULTIMO® Laminate cell from JSR Micro, Inc. (Sunnyvale, CA) can be used. Preferably, the supercapacitor 112 shall be configured to store energy in a range of 10 -1000 W.h (Watt hours) which corresponds to thermal energy needed for bringing roughly 100 ml -101 of cold water to the boil. For instance, three ULTIMO laminate cells CLQ2200, each having a capacity of 2200 F and maximal rated voltage 3.8 V, can together store energy up to 13.2 W.h.

Apart from the energy needed for heating the liquid, the supercapacitor shall be chosen for a particular appliance according to its weight. The energy-to-weight ratio of supercapacitors is approximately 10-15 W.h/kg. While it shall not he a problem for stationary appliances (e.g. a dish washer), it can pose a problem for a movable appliances. For instance, for an electric kettle (that is lifted when water is poured inside or outside), increase in weight of the appliance, due to the incorporation of the supercapacitor, can be a limiting factor (e.g. for elderly people). For such movable appliances, a supercapacitor capable of storing energy in a range of 10-200 W.h is more suitable.

The control panel 112 is a block of buttons that allow a user to start/stop a heating process and configure mode of the heating process. The panel 112 can be either implemented e.g. as a series of mechanical switches or alternatively as a more sophisticated display-equipped independent panel that communicates with the microcontroller 128 via e.g. 12C bus.

The microcontroller 128 can he for instance an AYR® Microcontroller from Atmel® Corporation, a PIC® from Microchip Technology Inc., etc. Resistance of the element 106 is adapted for the mains electricity (e.g. 230 V (Volts), 120 V, 100 V,...), while resistance of the element 108 shall be lower, typically below one ohm so that the element 108 can absorb significantly high discharge current from the supercapacitor 112. For instance, if a supercapacitor (e.g. composed of serial combination of supercapacitor modules) has a maximal rated voltage 38 V and maximal current equal to 100 A with a peak current up to 150 A, resistivity of the heating element 108 shall be in a range of 0.28-0.38 ohms Thickness of the wires interconnecting the supercapacitor 112 and the heating element 106 shall be chosen depending on the discharge current so that the wires do not heat up significantly.

The switch 126 can he e.g. implemented as an in-parallel-connected set of MOSFET switching transistors. On-state resistance of the switch 126 shall be at least two orders below the resistance of the element 108 (to prevent excessive heating of the switch). Transistors shall be chosen accordingly, for instance IR, Strong1RFET'm Power MOSFET with a typical on-state resistance between 1-2 nailliohms. The switch 126 can be alternatively implemented as a relay with corresponding rated current, e.g. if the appliance is constructed without any adaptive control (see below).

The element 108 can optionally comprise more sections (not shown). The switch 126 and the microcontroller 128 can be adapted for switching these sections according to immediate voltage value of the supercapacitor 112 during energizing of the element 108 so that the discharge-current rate of the supercapacitor 112 is stepwise constant (i.e. the lower voltage the capacitor has, the more sections are connected in parallel and thus the lower resistance the element 108 has).

Alternatively, a switched-mode converter, that would allow fully constant discharge of the supercapacitor I 12, can he also incorporated.

MODE OF OPERATION

Electrical appliances such as electric kettles, espresso machines, deep fryers, dishwashers, etc., all include in their working cycle a step in which a liquid is heated. Time needed for heating of the liquid is typically limited by a maximal mains-electricity density deliverable to the appliance (due to a circuit breaker). According to the present invention, the heating step can be accelerated by introduction a supercapacitor that is configured to energize a heater of such appliance.

Supercapacitor (also referred to as ultracapacitor), compared to a rechargeable battery, has very low internal resistance and can thus provide substantial current discharge rates. That means that the heater 104 can he energized from the supercapacitor 112 by a power density that exceeds not only a power density deliverable from the battery but also densities from the mains electricity (limited by a circuit breaker).

Equivalently a charging rate is primarily limited only by that resistance and a maximal temperature of the supercapacitor and the charging can be thus ten to hundred times faster than charging the battery. Yet another advantage of the supercapacitor lies in the amount of charge-discharge cycles, typically exceeding more than 100,000 cycles without any significant drop in their capacity.

Referring to the Figs. 1-2: The controller 110, shown as the block electric diagram in Fig. 2, uses the microcontroller 128 that controls particular electronic blocks. The step-down power supply 118 is connected to the mainspower-supply connector 114 and transforms mains-power-supply voltage to a lower voltage, typically between 5-48 V. The constant current source 120 is energized from the step-down power supply 118. Similarly, the microcontroller 128 is energized from the supply 118 via the wire 130. The supercapacitor 112 is chargeable from the mains electricity, particularly from the constant current source 120 that is powered from the supply 118, typically upon the end of the heating. Charging process of the supercapacitor 112 is triggered and controlled by the wire 132. Triggering can be either implemented e.g. as a MOSFET-based switch (similar to the switch 126) or it can be incorporated within the logic of the constant current source 120, e.g. as one input of a NAND (inverted AND) gate. The diode 111 avoids parasitic discharge of the supercapacitor 112 through the source 120. The wire 134, which acts as an analog sensing line, allows the microcontroller 128 to monitor the status of the charging, e.g. by a built-in analog-to-digital converter, and to interrupt it when the supercapacitor 112 is fully charged.

The MOSFET-based switch 126 allows to energize the heater 104, particularly the heating element 108, from the supercapacitor 112. That is controlled by the wire 136. The heater 104, particularly the heating element 106, is energized from the mains electricity that is connected to the element 106 through the relay 124 which is controlled by the microcontroller 128 via the wire 138. The temperature sensor 116 is configured for measuring temperature of the heater 104, particularly the heating element 108. It can be either directly in touch with the element 108 or in its close proximity, immersed in the liquid to be heated. That can provide an additional overheating protection to a normally-used bimetallic one. The microcontroller 128 can be configured to switch off the switch 126 in case of exceeding a maximal temperature limit, e g upon exceeding a maximal allowable temperature given by manufacturer of the heating element 108. The sensor 116 can be e.g a thermocouple. The sensor 116 is optional and can he alternatively omitted.

A user starts the heating process by pressing a button (not shown) on the control panel 122. Such trigger instructs the microprocessor 128 which subsequently energizes either one or both heating elements 106 and/or 108, depending on the mode of heating.

According to one aspect of the invention, the controller 112 can be configured to energize, in use, the heater 104, particularly the heating element 108 from the supercapacitor 112. That can be useful in case that energy needed for heating the liquid in the receptacle 102 is less or equal to the energy stored in the supercapacitor 112. For instance, for a small cup of instant coffee, approximately 100 ml (millilitres) of tap water is needed to be heated. Tap water is typically at 4°C and instant coffee shall be prepared with water at approximately 95° C. Thus, based on the specific heat capacity of water (4.18 J.g-t K-L)5 approximately 10.6 W.h of energy is necessary. if the supercapacitor 112 has energy stored higher than that amount, the water can be heated only therefrom. Heating the liquid (water in this case) only from the supercapacitor 112 can be faster, compared to a common heater energized from the mains electricity due to the high available discharge rate of the supercapacitor 112.

According to another aspect of the invention, the controller 110 can be configured to energize the heater 104, particularly the heating elements 106 and 108, simultaneously from the supercapacitor 112 and from the mains electricity. That combination provides highest power density combining high supercapacitor discharge rate and the power density from the mains electricity.

Appropriate heating mode can be configured e.g. on the control panel 122. Alternatively, the appliance can have incorporated an automatic measuring system, e.g. a liquid-weighting scale, and the microcontroller 128 can decide on the appropriate heating mode upon an immediate weight of the liquid in the receptacle 102.

The microcontroller 128 can also decide to energize the heater 104, particularly the heating element 106, only from the mains electricity, e.g. in the case that a user triggers another heating cycle too early after the end of a previous cycle when the capacitor 112 is still not charged.

According to yet another aspect of the invention, the controller 110 can use the sensor 116 for an adaptive control of the heating process, particularly to measure the temperature of the heater 104 and energize the heater 104 adaptively according to the temperature of the heater 104. For instance, the heating element 108 can be energized by a maximum available current from the supercapacitor 112 till a maximal allowed temperature (measured by the sensor 116) of the element 106 is reached. The controller can then maintain the element 106 at that temperature or close to it by variable switching of the switch I 26 according to immediate temperature of the element 106.

The controller I 10 can he alternatively implemented without the microcontroller 128. In such configuration, the control panel 122 can be replaced by e.g. a mechanical multi-position switch that can connect the mains electricity to the heating element 108 and the supercapacitor 112 to the heating element 106. Charging of the supercapacitor 112 can be driven e.g. by an operational amplifier with a Zener-voltage reference corresponding to the maximal allowed voltage of the supercapacitor 112.

DESCRIPTION AND OPERATION OF ALTERNATIVE EMBODIMENT

Fig. 3 shows an alternative appliance based on the Fig. I. The appliance further comprises an agitator 140. The agitator 140 comprises a stirrer 142 and an electric motor 144. The agitator 140 is configured for agitating the liquid, e.g. it is configured inside the receptacle 102 close to its bottom (the bottom is not specifically numbered). Agitation is controlled by a controller 1110. The controller 1110 is based on the controller 110 and it further comprises a switch (not shown) that controls the motor 144. In use, the motor 144 rotates the stirrer 142. The stirrer 142 agitates the liquid and speeds so up heat distribution from the heater 104 to the liquid. The agitation also suppresses local boiling of the liquid at the boundary of the liquid and the surface of the heater 104. Such agitation is important e.g. for a more rapid heating of oil in a deep fryer since too high temperature of the heater can locally over burn the oil upon exceeding its decomposition temperature. The agitator 140 can be implemented alternatively as a circulation pump.

Particular features disclosed in above-mentioned illustrative embodiments can be freely combined. Similarly, many variations and modifications of them are possible which remain within the concept, scope, and spirit of the disclosed embodiments, and these variations would become clear to those of ordinary skill in the art after perusal of this application. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the disclosed embodiments are not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims. Indefinite article "a" or "an" carries the meaning of "one or more" in open-ended claims containing the transitional phrase "comprising".

Unless the meaning is clearly to the contrary, all ranges set forth herein are deemed to be inclusive of the endpoints.

Claims

CLAIMS1. A liquid heating appliance powered from mains electricity, comprising: a receptacle configured for reception of a liquid; a heater adapted for healing the liquid; and a controller including a supercapacitor chargeable from the mains electricity, the controller is configured to energize, in use, the heater from the supercapacitor.
2. The appliance according to the claim 1, wherein the supercapacitor is configured to store energy in a range of 10 -1000 W.h.
3. The appliance according to the claim 1, wherein the controller is configured to energize the heater simultaneously from the supercapacitor and from the mains electricity.
4. The appliance according to the claim 1, wherein the appliance is an electric kettle and the supercapacitor is configured to store energy in a range of 10-200 W.h.
5. The appliance according to the claim 1, wherein the appliance further comprises a temperature sensor configured for measuring temperature of the heater and the controller is configured to energize the heater adaptively according to the temperature of the heater.
6. The appliance according to the claim 1, further comprising an agitator configured for agitating the liquid.