A COOKING APPARATUS

Field of the Invention

The present invention relates to a system and method for controlling the temperature of a hotplate of a cooking

apparatus. The system and method of the present invention can have application, but by no means exclusive application, to public cooking facilities such those found in public parks and gardens .

Background of the Invention The temperature of a hotplate of most public cooking apparatuses is controlled using a timer based system in which a heater, arranged to heat the hotplate is operated for a predetermined period of time, typically less than the amount of time required to cook food, and after the elapsed time automatically switch off. The heater can be turned back on for the set time period of the timer by a user pressing a button.

In this way, the heater, for example a gas burner, heats the hotplate for a period such as 5 minutes, and then switches off to prevent the hotplate from getting too hot and from wasting fuel such as gas, or damaging the hotplate. This on, off, on again process can be repeated by manual operation until the food is cooked. Similarly in the situation in which the heater is an electric heating element, again the existing apparatus comprises a timer based system that operates to heat the hotplate for a period of time, e.g. 5 minutes, and then switches off after the elapsed period. To complete the cooking process the user can repeatedly press the operating button after each period. The existing operating systems provide a reliable means of preventing the heating element from burning out and from the hotplate becoming too hot during cooking. However, whilst the hotplate is not being heated, the food being cooked on the hotplate can be subjected to temperatures that are too low for cooking, which may not be sufficient to kill any germs

associated with the food and/or the hotplate and may cause the food to stew. This problem is exacerbated by users who are not familiar with operation of the hotplate, for example, users who are not aware that the hotplate has switched off.

On the other hand, heating the hotplate for periods of more than 5 minutes may result in the hotplate becoming too hot for cooking and the food being burnt.

There is therefore a need for an alternative system, method and apparatus for cooking.

Summary of the Invention

According to the present invention there is provided a system for controlling temperature of a hotplate of a cooking

apparatus, the system comprising:

a thermocouple proximate the hotplate and arranged to sense a temperature of the hotplate; and

a controller that controls a heater arranged to heat the hotplate to a selected temperature and to maintain the selected temperature of the hotplate based on the sensed temperature of the hotplate received from the thermocouple.

The system can be used in relation to any cooking apparatus but suitably the cooking apparatus including an indoor apparatus, but suitably, an outdoor cooking apparatus. In the case of an outdoor cooking apparatus, suitably the hotplate is adapted for being exposed to the ambient conditions, for example, the hotplate has a drainage port or sump that drains condensation, such as rain, from the hotplate. The drainage port or sump may also drain liquids such as oils and fats that are exuded from food being cooked on the hotplate.

In an embodiment, the controller may be arranged to cycle operation of the heater ON and OFF to maintain the hotplate at the selected temperature. When the sensed temperature goes above the selected temperature, the controller is arranged to turn the heater OFF. Conversely, when the sensed temperature is below the selected temperature, the controller is arranged to turn the heater ON, or cycle the heater ON and OFF. In one arrangement, the heater may include a gas burner, and the controller is arranged to cycle ON and OFF the gas supply to maintain the hotplate at the selected temperature. In another arrangement, the heater may include an electric heating element, and the controller is also arranged to cycle ON and OFF power to the heating element to maintain the hotplate at the selected temperature. The controller may control the cyclic operation of the heater ON and OFF over any period. The period over which the controller cycles the ON and OFF operation will be dependent on a number of factors including the ambient temperature, the mass and heat capacity of the hotplate, and the rate at which food on the hotplate absorbs heat. In any event, a gas burner can cycle ON and OFF over any period, say every 30 second. An electric heating element may cycle over any period, say every 90 seconds .

In an embodiment, the system further includes an indicator arranged to indicate that the hotplate has been heated to the selected temperature compared to the sensed temperature of the hotplate received from the thermocouple. In another embodiment, the indicator is further arranged to indicate that the hotplate has not been heated to the selected temperature and that the cooking apparatus is in a preheating mode of operation. The preheating mode of operation may be a mode in which the hotplate is in the process of being heated to the selected temperature. It is also possible that the indicator may indicate that the hotplate has exceeded the selected temperature. The user can then either decide whether to continue cooking on the hotplate or remove the food from the hotplate until the hotplate has cooled to the selected temperature. In one example, during the preheating mode, the controller may control the heater to cycle operation of the heater ON and OFF while the temperature of the hotplate is increasing to the selected temperature. In another example, during the preheating mode, the controller may control the heater so that the heater is continuously ON while the temperature of the hotplate is increasing to the selected temperature.

In an embodiment, the indicator may be further arranged to indicate a selected length of time in which the controller is arranged to maintain the selected temperature of the hotplate. For example, the indicator may show either one or a combination of: i) the time elapsed since the temperature of the hotplate reached the selected temperature, or ii) the time remaining over which the hotplate will be held at the selected temperature. In an embodiment, the indicator may be further arranged to indicate that the controller is in a cooking mode of operation for the selected length of time. During the cooking mode, the controller may be controlling the heater to either: hold the temperature of the hotplate at the selected temperature, or allow the hotplate to cool to the selected temperature. During the cooking mode, the controller may control the heater to cycle operation of the heater ON and OFF to maintain the hotplate at the selected temperature. During cooking mode, the controller can cycle the heater ON and OFF to counter normal heat loss during operation.

In an embodiment, the indicator may include an audible means . In another embodiment, the indicator may include a visual means. For example, the indicator comprises a Light Emitting Diode (LED) that indicates that the hotplate has not yet been heated to the selected temperature by blinking ON and OFF, and indicates that the hotplate has reached the selected temperature by providing a continuous light. In another example, the LED changes colour to indicate the different states of the hotplate, e.g. a red LED indicates that the hotplate has not yet been heated to the selected temperature and a greed LED light indicates that the hotplate has reached the selected

temperature. In addition, the continuous light turns off when the selected length of time in which the controller is arranged to maintain the selected temperature of the hotplate has been reached. In another example, the audible means comprises a speaker that emits an intermittent beep whilst the hotplate is being heated; emits a single beep when the hotplate has reached the selected temperature, for example a short beep of say 0.25 seconds; and emits a continuous tone when the selected length of time to maintain the selected temperature has been reached, for example a longer beep of say 1 second.

In an embodiment, the system may include a first input device that is operable by a user for selecting the selected

temperature of the hotplate. The selected temperature may be any temperature or any temperature range. For example, the selected temperature may any temperature greater than 50°C, greater than 60°C, greater than 60°C, and so forth. The selected temperature may also be any temperature less than 250°C, and for instance be a temperature range from 80°C to 250°C, or any temperature range such as temperatures ranging from 80°C to 150°C and so forth. The selected temperature may also be a particular temperature, such as X°C and range of temperature above or below the particular temperature, such as X°C ± Y°C . The first input device may be arranged to allow the user to input the selected temperature at predetermined temperature intervals, for example, the intervals may be temperature increments of 1 or 2 or more degrees. In one example, the temperature intervals may be intervals that change by 5, 10, 15, 20, 25°C or 30°C. The input device may be adjusted by a user as desired during operation, for example, during the cooking mode. This allows the user to increase or decrease the selected temperature as desired and depending on rate at which the food is cooking on the hotplate.

Furthermore, the first input device is further operable for selecting a length of time in which the controller is arranged to control the heater to heat the hotplate. The first input device may be operated to control the heater to heat the hotplate for any time interval. For example, the first input device may be operated to select a length of time in increments of the multiples of seconds including 10 sec, 20 sec, 30 sec, 40 sec, 50 sec and increments of minutes. In one example, the first input device may be operated to select the length of the time in which the controller controls the heater to heat the hotplate in terms of a combination of the increments of less than one minute in combination with increments of greater than one minute. Step increases of say 10 to 20 minutes may also be employed .

To facilitate the selection of the selected temperature and the length of time the controller controls the heater during heating, the input device may include a selector, such as one or more dials with operating positions, a numeral key pad with digits 0 to 9 and/or switches, either one or a combination of UP and DOWN buttons, or a single modal button may be used.

In an embodiment, the system includes a second input device may have start/stop settings that are operable to command the controller to control the heater to heat the hotplate to the selected temperature and to maintain the selected temperature of the hotplate, and to command the controller to control the heater to stop heating the hotplate.

In addition, the second input device may be made operable when used with respect to a payment device such as a coin meter or bank card system associated with the system or the cooking apparatus (e.g. internal or external to the cooking apparatus) . For example, the second input device becomes operable when the required amount of money is paid using the coin meter or bank card system, and the input device is operated by the operator to command the controller to control the heater to heat the hotplate and use the cooking apparatus. When the system is in the stop mode, the second input device will remain inoperative until a user has paid the required amount of money to commence operation. In another example, the coin meter or card system is external to the cooking apparatus and information indicative of payment for use of the cooking apparatus is communicated to the controller over a network, such as the Internet. In any case, it is envisaged that the second input device is capable of multi-mode operation to start and stop heating the hotplate and for other uses, such as diagnostic and maintenance uses. For example, the second input device must be held in one mode of operation for approximately three seconds or more by the user before the controller controls the heater to stop heating the hotplate. In another mode of operation, the second input device may be held for three or more seconds by the user to operate the controller to control the heater to commence heating the hotplate.

In an embodiment, the above described first and second input devices and indicator are located on the cooking apparatus in a position readily accessible to the operator. For example, these controls are located proximate the hotplate for ease of use and visibility. In addition, these controls can be shielded using a hood to prevent oil splatter whilst cooking on the hotplate and screen the displays from direct sunlight. The second input device may include a stop/start button that is operable to command the controller to control the heater to heat. The first input device may also include a selector that is operable to select the selected temperature and/or the length of time of operation.

In an embodiment, the controller comprises a usage module arranged to record usage statistics of the heater. In an arrangement, the usage module is further arranged to communicate the usage statistics of the heater, and thus the cooking apparatus, over a network. For example, the network comprises the Internet and the usage statistics are accessible by a computing device connected to the Internet.

In an embodiment, the cooking apparatus comprises an outdoor barbeque. In another embodiment, the cooking apparatus comprises a barbeque suitable for indoor use.

The heater may be powered by any suitable means including electricity, gas or a combination thereof. Accordingly, the heater may be a gas burner, or an electric element, or a combination thereof. According to the present invention there is provided a cooking apparatus including:

a hotplate;

a thermocouple proximate the hotplate and arranged to sense a temperature of the hotplate;

a heater arranged to heat the hotplate; and

a controller arranged to control the heater to heat the hotplate to a selected temperature and to maintain the selected temperature of the hotplate based on the sensed temperature of the hotplate received from the thermocouple.

According to the present invention there is also provided a method of controlling temperature of a hotplate of a cooking apparatus, the method comprising:

receiving a temperature of the hotplate from a

thermocouple proximate the hotplate and arranged to sense a temperature of the hotplate; and

controlling a heater to heat the hotplate to a selected temperature and to maintain the selected temperature of the hotplate based on the sensed temperature of the hotplate received from the thermocouple. Controlling the heater to heat the hotplate may include a controller cycling operation of the heater between ON and OFF to maintain the selected temperature of the hotplate. In one example, the controller cycles operation of the heater between ON and OFF during a cooking mode in which the heater maintains the hotplate at the selected temperature, and retains the heater ON during a preheating mode in which the heater is raising the temperature of the hotplate to the cooking temperature. The method may also include making a monetary payment to a payment device associated with the cooking apparatus which enables a user to command that the heater heats the hotplate. Making the monetary payment enables a start/stop input device operable by the user to become operative, and thereby allows the user to command the controller to heat the hotplate via the start/stop input device.

According to another aspect of the present invention, there is provided computer program code which when executed implements the above described method.

According to another aspect of the present invention, there is provided a computer readable medium comprising the above program code .

The cooking apparatus and method of the present invention may also include any one or a combination of the features of the system described herein. Brief Description of the Drawings

In order that the invention be more clearly ascertained, embodiments will now be described by way of example, with reference to the accompanying drawings, of which: Figure 1 is a schematic view of a system for controlling temperature of a hotplate of a cooking apparatus according to a preferred embodiment of the present invention; Figure 2 is a flowchart of a method of controlling temperature of a hotplate of a cooking apparatus according to a preferred embodiment of the present invention;

Figure 3 is an electrical diagram of the system of Figure 1 showing the heater as a gas burner; and

Figure 4 is an electrical diagram of the system of Figure 1 showing the heater as an electric heating element. Detailed Description

According to the preferred embodiment there is provided a system 10, as shown in Figure 1, for controlling temperature of a hotplate 14 of a cooking apparatus 12 such as an outdoor cooking apparatus. The system 10 comprises a thermocouple 16, proximate the hotplate 14, to sense a temperature of the hotplate 14. It will be appreciated by those persons skilled in the art that the thermocouple 16 may be attached to the hotplate 14 or located adjacent the hotplate 14 at a distance sufficient to sense the temperature of the hotplate 14. In any case, the thermocouple

16 is arranged to communicate the temperature of the hotplate 14 to a controller 18 which controls a heater 20 that heats the hotplate 14. The controller can be operated to control the heater heating the hotplate to a selected temperature, in which the heater initially increases the temperature of the hotplate from ambient temperature during a preheating mode and maintains the temperature of the hotplate at the selected temperature of the hotplate 14 in a cooking mode based on the received temperature of the hotplate 14 from the thermocouple 16.

Thus, for example, in the preheating mode, the hotplate 14 is heated by the heater 20 to a selected temperature of, say, 250°C, and maintained at this temperature for cooking food in the cooking mode. It will be appreciated by those persons skilled in the art that the selected cooking temperature of 250°C can be either preselected in the sense that it is fixed setting of the controller, or selected by a user who is using the cooking apparatus 12. That is, the selected temperature can be any cooking temperature (e.g. 150°C) up to a maximum temperature (e.g. 255°C) provided by the cooking apparatus 12. It is also possible that the length of time of either one or a combination of the preheating mode and/or the cooking mode may also be preselected in the sense that it is a fixed setting of the controller. Preselected settings of the controller relating to the selected temperature or the selected cooking time may be adjustable, for example, during maintenance of the cooking apparatus.

In the embodiment shown in Figure 1, the different modes of operation are indicated to the user of the cooking apparatus 12 via an indicator 22, in the form of an LED to emit a visual indication to the user of a change in status of the operating mode. In addition, the indictor 22 also comprises a speaker (not shown) to emit an audible indication of a change in status of the operating mode. As described, the LED, and the speaker, indicate that the hotplate has reached the selected temperature for cooking; that is, the preheating phase has been completed and the hotplate 14 is sterilised and at the desired temperature for cooking. For example, the hotplate 14 may be maintained at a minimum of 100°C for at least 4 minutes to kill any germs residing on the hotplate 14 as part of the preheating mode. In this case, the controller 18 gives instruction to the LED 22 to indicate to the user that the hotplate 14 is in the preheating mode and not yet ready to be used for cooking food by blinking. Once the 4 minutes have elapsed and the hotplate has reached the selected temperature, for example 250°C, the LED 22 indicates to the operator that the hotplate 14 is in the cooking mode by maintaining a constant light. As described, the light goes out when a preselected cooking time expires . Also as described, the speaker emits a beep to alert the operator that the cooking apparatus 12 has entered the preheat mode, entered the cooking mode, and has exited the cooking mode. Moreover, the speaker may emit a beep whenever the operational status of the cooking apparatus 12 changes. For example, the speaker may emit a beep in any one or a combination of the following situations:

• when the cooking apparatus 12 turns ON and enters the

preheat mode,

• when the cooking apparatus 12 enters the cooking mode from the preheat mode,

• when the designated cooking mode time expires,

• when an operator extend the cooking mode time,

• when the cooking apparatus 12 auto powers OFF,

• when the cooking apparatus 12 is powered OFF by the

operator, and

• if there is a fault with the cooking apparatus 12 (e.g. heating element failure) .

The system 10 shown in Figure 1 further comprises a start/stop button 24 operable to command the controller 18 to control the heater 20 to heat the hotplate 14. That is, the button 24 is operable to enter the preheating mode to heat the hotplate 14 to the selected temperature, and to enter the cooking mode to maintain the selected temperature of the hotplate 14 whilst cooking. Also, the button 24, as described, can be depressed for, say, three seconds to command the controller 18 to control the heater 22 to stop heating the hotplate 14. In addition, it will be appreciated by those persons skilled in the art that the start/stop button 24 can be used to command the controller 18 to perform other functions, such as performing diagnostic tests on the system 10, selecting the length of time for the cooking mode, and for selecting the cooking temperature of the hotplate 14. Alternatively, or additionally, the cooking apparatus 12 comprises a control panel 25 comprising a selection means or other input device, such as a dial, to select the cooking temperature of the hotplate 14 and/or the cooking time for which the hotplate 14 is maintained at the selected temperature in the cooking mode. In any case, it can be seen from Figure 1 that the controls are located proximate the hotplate 14 for ease of operation by the operator. Also, the control panel 25 may comprise an LCD display

indicating remaining cooking time, time elapsed since turning the apparatus on, preheat time, instantaneous hotplate

temperature from the thermocouple 16, battery voltage for the controller 18, etc, to the user.

It will be appreciated by those persons skilled in the art that the controller 18 requires power to operate. In an embodiment, the controller 18 is powered by mains power i.e. 240VAC, when used with respect to an electric heating element, or, in another embodiment, the controller 18 is powered by a low voltage source, suitably a 12VDC source such as a battery which can be charged via a solar panel (not shown) . In the latter case, battery information can be displayed on the LCD display 25 to the operator of the cooking apparatus 12.

An electrical diagram showing an embodiment of the system 10, where the heater comprises a gas burner, is shown in Figure 3. In this embodiment, the controller Ml is a Programmable Logic Controller (PLC) preloaded with software to control the gas burner via operation of gas valve solenoids Rl and a spark module M2. That is, in use, the controller Ml receives temperature information from a thermocouple Tl and start/stop information from a start/stop button SI to control the spark module M2, via the communication bus CI, to control the temperature of a hotplate of a cooking apparatus.

Power is supplied to the controller Ml via a 12VDC power supply, of the type described above, which is connected to the

controller Ml via a connector C2. As described, a battery for supplying power can be charged using a solar charging unit PI . The controller Ml is arranged to cycle ON and OFF the gas burner via operation of the spark module M2 to heat the hotplate in the preheating mode and to maintain a selected temperature of the hotplate in the cooking mode. This is achieved by activating the gas valve solenoids Rl to stop gas supply to the gas burner when the temperature from the thermocouple Tl reaches or exceeds the selected temperature of the hotplate. The controller Ml then reactivates the gas valve solenoids Rl to reopen the gas supply to the gas burner and ignites the gas using an ignite electrode M3 controller by the spark module M2 when the temperature from the thermocouple Tl drops below the selected temperature. It will be appreciated by those skilled in the art that the controller Ml gives instructions to the spark module M2 to switch ON and OFF the gas supply based on the sensed temperature from the thermocouple Tl falling within a

predetermined tolerance value, such as 10°C, of the selected temperature. In addition, the spark module M2 comprises as a flame detector M4 to detect if the ignite electrode M3 has ignited the gas supply.

In another embodiment, the heater is an electric heating element as shown in the electrical diagram illustrated by Figure 4. In this Figure, the controller Ml is also a PLC preloaded with software to control temperature of the hotplate, but, in this case, a solid state relay Rl operates a heating element El cyclically by switching it ON and OFF as described above to maintain the selected temperature of the hotplate based on the sensed temperature of the hotplate from the thermocouple Tl . In addition, a thermostat S2 is used to sense the temperature of the hotplate to provide redundancy for the thermocouple Tl to prevent the heating element El from overheating the hotplate and from burning out.

Also, it can be seen from Figures 3 and 4 that the operating mode of the cooking apparatus, such as the preheating or cooking modes as described, is indicated to the user via indicator LI, shown in the form of an LED. With reference to Figure 2, there is shown a flow chart of a method 26 of controlling temperature of a hotplate of a cooking apparatus comprising the steps of receiving 28 a temperature of the hotplate from a thermocouple proximate the hotplate, the thermocouple being arranged to sense a temperature of the hotplate, and controlling 30 the heater to heat the hotplate to a selected temperature and to maintain the selected temperature of the hotplate based on the sensed temperature of the hotplate received from the thermocouple.

It will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invention.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word

"comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.