Patent ID: 12245604

DESCRIPTION OF EMBODIMENTS

General Preferred Embodiment

FIG.1shows a general preferred embodiment in schematic form of an oven1of a cooking appliance with a cooking chamber2for cooking food positioned therein via a chamber door (not shown inFIG.1). The oven1has a smoke generator (referred to hereinafter simply as “smoker”)3, providing the oven1with the ability to smoke food (hereinafter referred to as a “smoking function”). Preferably, a user using the oven1can select a smoke cycle (hereinafter referred to as a “smoking function”) to smoke the food in either a hot (or heated) state, a cold (or unheated) state, or at any temperature in between by setting a desired oven temperature in the known way. The smoker3when used in the oven1can enhance the smell, taste, and visual appearance of the food being cooked/smoked. The smoker3can be used as a standalone method of cooking, or it can be used in conjunction with other cooking functions, such as baking, heating or the like.

The smoker3in the preferred form includes a smoker compartment4in the bottom wall (floor/base)5a, or other wall5b, or the door of the oven1, an igniter6in the compartment4, and a fluid injector7. Smoker compartment4may be in the form of a fully or partially recessed (that is, not flush with the surrounding internal surface of the cooking chamber) cavity or fire box. An oven controller11is provided at a suitable position in/on or adjacent to the cooking appliance, and is connected to the igniter6in order to operate the igniter6. A removable/pivotable lid8(preferably vented) is provided over the compartment4to allow a user to access the compartment. A fluid pump (such as an air pump)9is provided at a suitable position in/on or adjacent to the cooking appliance for pumping combustion-enhancing fluid to smoker compartment4and is either fluidly coupled (for example via a rubber hose) to the fluid injector7, or is at least a part of the fluid injector7. Fluid pump9is also connected to oven controller11so that it can be activated to cause combustion-enhancing fluid to flow into smoker compartment4via fluid injector7.

Smoker compartment4may be formed as a recess in the inner surface of base wall5aof the oven1. Alternatively, the compartment4could be formed in an inner surface of another wall, such as a vertical or side wall5b, of the oven1, or even in the inner side of the oven door. Smoker compartment4could also be separately-formed and mounted in or on the base or wall or door of oven1. The fluid injector7and/or igniter6can be permanently fixed in the smoker compartment4or could alternatively be removable. The fluid injector7and fluid pump9are preferably an air injector and air pump, respectively, although other combustion-enhancing fluids may be pumped/injected. A discrete charge or volume of smoker fuel10, such as woodchips, wood pellets or other combustible fuel can be placed in smoker compartment4by a user. Igniter6is connected to oven controller11so that it can be energised on demand to ignite the smoker fuel10, and the fluid injector7provides fluid as instructed by oven controller11to promote and control combustion of the smoker fuel10. The fluid pump may be a simple on/off, fixed speed pump or may have the capability of delivering fluid at a desired, variable flow rate, as determined and instructed by oven controller11.

It is desirable that the fluid, such as air, promotes combustion without producing flames in order to generate smoke. Once air is pumped into smoker compartment4, the igniter6may be energised within smoker compartment4, initiating combustion of the fuel10provided therein and creating smoke. The generated smoke is then delivered/channeled from the smoker3to the oven chamber2in order to smoke food positioned therein. It is desirable to regulate the amount of air pumped into smoker compartment4—a sufficient amount/flow rate of air should be pumped into the compartment4so that there is controlled smouldering of the smoker fuel10. If too much air is pumped into the compartment4there is a risk of generating flames in compartment4which could reduce/eliminate the production of smoke. Flames within compartment4are, however, not a major safety concern because the oven door is closed (optionally, locked) during smoking and there is a limited supply of combustible fuel10such that any flames will eventually self-extinguish. The fluid injector7may include one or more components, some of which may be located at least partially within or which are at least partially installable within the smoker3, or may be integrated with the rest of oven1.

Preferred embodiments of the present invention will now be described with reference in particular toFIGS.2to4. In these preferred embodiments the oven is at least a part of a cooking appliance such as a freestanding cooker (or “range” or cookstove), or built-in wall oven that may be used in a domestic or commercial setting. The oven may be electrically powered, gas powered, or powered using some other suitable energy source. The invention is however also suitable for use in other cooking appliances such as outdoor barbeques or “grills” which incorporate a lid in place of the oven door referred to herein with regard to the oven embodiments, so that a cooking/smoking chamber is formed above a grilling surface when the lid is closed.

Additional Preferred Embodiment

FIG.2shows a right side cross-sectional view of a cooking appliance such as a built-in wall oven12(which may be heated by gas and/or electricity) that comprises a smoker20according to the general embodiment described above. The oven12has a cooking chamber13for cooking food items14in the usual manner, such as by heating, (fan) baking, defrosting, grilling, or the like. Cooking chamber13is made up of upper, lower, rear and two side walls that are assembled together or formed in a rectangular prism or cuboid shape, as is well known, with all edges between adjacent walls sealed such as by welding or forming. The oven12has at least one primary heating source within chamber13such as an upper heating source15, a lower heating source16or a rear heating source (not shown). The oven12has a controller18that can monitor system conditions within the chamber13of oven12and can also control the operation of the oven12, including the smoker20. The controller18is configured to receive user-specified operational variables (including time and/or temperature for example) as control inputs that a user can provide via a user interface. The controller18is configured to automate (such as under software control) other operational variables not predetermined by the user (such as the operation of an oven fan, for example) as well as energising/de-energising components of the smoker in accordance with a preset/automatic or fully/partially user-adjustable/manual operating cycle.

The oven12has a chamber door17that closes an opening of chamber13with a seal compressed between the door and the perimeter of the chamber opening such that when the door is closed, the chamber is hermetically sealed under normal operating conditions. Chamber door17optionally has a door latch24for holding the door in its closed and sealed position to prevent (or at least minimise) loss of heat and/or smoke through the chamber door17. As mentioned previously, the door may be locked in its closed position during the smoking cycle by energising, via controller18, the latch to a locked orientation. The oven12also preferably has a Catalytic Smoke Eliminator (“CSE”)26(which may incorporate a heating element—not shown) and a venting fan28to help remove smoke from the gases exhausted, via a vent, from the chamber at any time before, during or after the smoking cycle. The heating element of the catalytic smoke eliminator26can be switched on/off, or its power output adjusted, by controller18. Similarly, venting fan28may be switched on or off, or its speed adjusted, by controller18. Venting fan28may also operate to cool electronic components of the cooking appliance, such as controller18.

Oven12, in addition to the primary cooking (grilling, baking etc.) heating source, such as heating elements or burners, has a smoker20that can be operated to produce smoke required for smoking food items14. The smoker20is shown in more detail inFIG.3(which shows a partial cross-section of the base31of the oven) and inFIG.4(which shows a plan view of the smoker20). The smoker20comprises a smoker compartment30that is formed as a recess in or is mounted within the base31of the oven. Preferably the smoker is located near the front of the oven chamber, adjacent chamber door17to enable access thereto by a user. In the embodiment shown the base31comprises an inner surface of the chamber (“chamber floor”)32, and an outer surface33of the oven12. Some non-limiting examples of how the compartment30may be formed in the base31of the oven12are:The compartment30may be a recess formed into the oven panel providing the base31of the oven12. Optionally, a liner, that may or may not be removable, may be located within the recess. The optional liner may be formed from metal such as steel or from another material having high heat and corrosion resistance.The compartment30may be a fire box that is suspended from the edges of a cut-out formed in the oven panel providing chamber floor32of the base31.

As previously mentioned, the smoker compartment could be formed within or inserted into or mounted on the oven chamber's base, a side wall of the oven chamber or the oven door. In any implementation, the top of the smoker compartment may be flush with the inner surface of the chamber or door, or it may be only partially recessed such that it sits proud of the surrounding inner chamber surface.

Preferably, compartment30is formed from or lined with stainless steel or other well-known material which has high temperature and corrosion resistance. For example, compartment30may be square-shaped in plan view with each side having a length of about 60 mm. The side walls and base of compartment30may be semi-cylindrical in shape with flat end walls at either axially-separated end. A removable or at least openable (such as pivoted/hinged) lid34may have slightly larger dimensions than the recess or opening of compartment30and is placed over compartment30. Lid34may couple to (such as connecting to or resting on) the base of the oven or to compartment30, such as to an upper rim of the compartment or its liner, if provided. Lid34closes the compartment's upper opening which is the sole, only or single opening via which combustible fuel may be introduced into, and combustion products may exit from, the compartment. Preferably a gasket or seal (not shown) is provided between the lid and base31(or compartment30or its liner). The removable lid34has one or more smoke regulation holes or vents35to regulate the flow of smoke from smoker compartment30into oven chamber13. The removable lid34is preferably made from stainless steel.

Smoker compartment30is surrounded by thermal insulation36which is conventionally provided within base31so that heat is retained in oven chamber13and/or smoker compartment30.

An air injector37is provided for the smoker20. The air injector37includes an air injector tube38disposed in the compartment30, preferably with its longitudinal extent in the plane of the axis of the semi-cylindrical side/base wall of the compartment30and about 10 mm above that wall. The air injector tube38may have a diameter of about 5 mm and extend in a cantilevered fashion (as shown inFIG.3) from an end wall of the smoker compartment30or it may be supported by the end walls of the compartment/liner at both of its longitudinally-separated ends. The air injector tube38is preferably formed from stainless steel with multiple openings39to allow injection of air (or other combustion-enhancing fluid) to smoker compartment30. Ideally, holes39are formed so that they direct air downwardly, that is, below horizontal.

Air injector37may also include an air pump41and an air tube40. Air tube40is coupled to the air injector tube38and passes through the base of the oven to the air pump41which is disposed at some suitable position in/on the oven. The air pump41is controlled by controller18(via a cable42) to provide air to the air injector37. The term “air injector” as used herein could refer only to the air injector tube38itself within smoker compartment30, or alternatively injector tube38and also the air tube40extending through the base31and/or the air pump41, depending on the context. Air injector37promotes initial ignition of combustible material positioned in the smoker compartment and also promotes ongoing burning of that material when or if necessary. In an alternative embodiment, the air injector37could be removable from the compartment such as by a coupling that enables detachment/reattachment from/to the air tube40.

At least part of an igniter43is also disposed in the smoker compartment30, extending in a cantilevered fashion from an end wall (or alternatively, fixed to both end walls) of the compartment30and positioned above injector tube38. In an alternative embodiment, the igniter43could be removable from the compartment30and from an electrical connection with the controller18via cable44. The igniter may have a diameter of about 10 mm and is preferably positioned with its longitudinal extent parallel to the injector tube38and about 10 mm above it. The igniter43(which may be referred to as a “heating element”) could be an electric igniter similar to those used in pellet-burning stoves which are usually a resistive element often encapsulated in a tubular ceramic casing, or any other kind of hot surface igniter known to a person skilled in the art, such as a heated coil element or surface heater. Controller18may be operated to control the igniter43to initiate and maintain combustion within the smoker compartment by suitably modulating its output power.

Controller18may be positioned at any suitable location in/on the cooking appliance. It could be the same controller that controls the general operation of the oven, or it could be a dedicated controller for the smoker. Alternatively, separate controllers could be used for the air pump41/air injector37and for igniter43.

Without limitation, depending on the arrangement of the smoker compartment30, igniter43and air injector38, the term “smoker” could refer to only the compartment30(adapted to receive the igniter and/or air injector), or to the smoker compartment in combination with the igniter and/or air injector, as context will determine. Controller18and/or the air pump41, and the electrical and air connections between them and the igniter and fluid injector might also be considered part of the smoker, as context will determine.

Usage

Use of smoker20in oven12will now be described with reference to an exemplary smoking procedure, as set out in steps50-57ofFIGS.5A and5B. The smoking procedure describes the steps taken by the user and oven to smoke food items. Step55of the smoking procedure set out inFIG.5Ais initiation of a smoke cycle, which comprises a series of actions (seeFIG.5B) that the controller18undertakes to operate the smoker20and other components of the oven12in order to carry out the smoking process in the oven. The smoke cycle is therefore a subset of steps that takes place within the overall smoking procedure. Controller18is configured to operate the smoker20and other components of the oven12according to the smoke cycle (step55). The following assumes that suitable smoker fuel has been pre-loaded into smoker compartment30.

The following is an explanation of each of the steps set out in the flow diagrams ofFIGS.5A and5B:Step50—The user places fuel in smoker compartment30.The fuel could be any variety of dried, natural untreated wood (pellets, chips, chunks, etc.). 15-25 g of wood pellets is a suitable amount of fuel for an oven capacity of between around 60 to 70 litres. The fuel will be adjacent to or in contact with the igniter43. The user then replaces the removable lid34over the compartment30and closes oven chamber door17.Step51—The user selects the smoke cycle on the user interface of the cooking appliance.Controller18then implements the various functions and/or operates the various components of the oven12to carry out smoking of the food items. The user may select or set a cooking/smoking time period and a smoking/cooking temperature, or these may be preset.Step52—Oven12commences with pre-heating.Controller18instructs oven12to commence pre-heating. Pre-heating is preferably carried out in a similar manner to how an oven is normally pre-heated before baking. The pre-heating temperature (for example, 115° C.) may be user-adjustable and set based on the food14that is being smoked. Controller18activates the catalytic smoke eliminator26by energising its heating element, if provided.Step53—Oven12continues with pre-heating.Once the oven reaches the set pre-heating temperature, controller18may continue with oven pre-heating until a predetermined pre-heating time period has expired. For example, the pre-heating period may be set to a value between 10 and 15 minutes; however, the length of time can be user-adjusted. Having a set period of time for the pre-heating period ensures that the catalytic smoke eliminator26will reach its required temperature for eliminating smoke. The cooking appliance then sounds an audible alarm and/or activates a visible alert such as by flashing a light on the user interface or displaying an appropriate message on a display screen to prompt the user to load food items14into the chamber13.Step54—The user loads food14into the chamber13.The food items14may, for example, be supported on wire racks to allow smoke to completely surround the food14. A drip tray may be placed beneath the food items14.Step55—The user initiates the smoke cycle.The user can, for example, press an appropriate button on the user interface of the cooking appliance to commence the smoke cycle. An exemplary smoke cycle as shown inFIG.5Bwill now be described according to steps55ato step55d:Step55a—The controller18activates the oven chamber door latch24, locking the chamber door closed.The latch is preferably electronically controlled by the controller18, however the latch24may also have a manual override that deactivates the latch24so that the user can manually open the chamber door.Step55b—Controller18activates igniter43to commence combustion of the fuel in smoker compartment30.Preferably at the same time, controller18operates air injector37to inject air into the compartment30at a predetermined high or maximum rate of supply. This stage of the smoke cycle may be set to last for between 2-3 minutes to ensure that combustion of the fuel has successfully started. The oven temperature is also adjusted to the preset cooking temperature set by the user. Fan28may also be activated to draw smoke from chamber13, through CSE26(removing smoke and the smoky smell therefrom) and into the environment around the cooking appliance.Step55c—Smoking begins.As the fuel begins to burn, smoke is produced within smoker compartment30and is released into chamber13via holes35in lid34. At the end of the ignition period the igniter may be de-energised (either turned off or its output power reduced) and air injector37may reduce the rate of supply of air to a lower or minimum value to simply sustain smouldering of the fuel. It is known that a fuel load of between around 20-25 g of Oak wood pellets will provide between 1.5-2 hours of smoking time. It is therefore expected that the fuel in the compartment30will be used up by the end of a 2 hour smoke cycle so that smoke production in the oven will have stopped. If the user-set cooking smoking period is less than this nominal period then controller18may inform the user, via the user interface, that a reduced fuel load should be added to container30.Step55d—Controller18deactivates the chamber door latch24.At the end of the cooking/smoking period set by the user, air injector37is preferably de-activated and the chamber door is unlocked so that the user may remove the smoked and cooked food items from the oven chamber. Alternatively, the controller may wait a short period of time after the end of the preset or user-set period to ensure that smoke generation has stopped, before allowing the door to be opened (particularly in cases where the preset/user-set smoking/cooking time is shorter than a predetermined theoretical maximum combustion period sustainable by the fuel volume of container30).Step56—The user removes food items14from oven chamber13.Food items14are smoked, and cooked, ready for serving.Step57—Once the user has completed smoking/cooking the food items, he or she may select an oven self-cleaning function on the user interface of the cooking appliance.Once the smoke cycle is complete, and no further smoking or cooking is required it is recommended to clean the oven12. The oven12preferably has a pyrolytic cleaning function—door latch24is activated to lock the door in a closed position and the temperature inside the chamber is elevated to a high temperature, preferably to a temperature in a range of 400-500° C., which reduces grease, smoke residue and food residue to ash. During the pyrolytic cleaning operation the CSE26and fan26may still be operated. Once the oven has cooled door latch24is released and the user may then remove the residual ash by vacuuming or sweeping away the ash from oven chamber13and smoker compartment30.
Additional Monitoring

In conjunction with the smoking procedure (steps50-57), it may be desirable to also monitor air temperature in, and/or exiting from, the oven chamber13. For example, air temperature at the chamber vent, downstream of the catalytic smoke eliminator26, provides an indicator of smoke “density”. The air temperature downstream of the CSE26increases with an increased amount of smoke, and conversely, the air temperature decreases as the amount of smoke reduces towards the end of the smoke cycle. Accordingly, controller18may also receive data from a temperature probe (not shown) in the oven vent downstream of the CSE26and determine that the fuel has been consumed from a drop in detected temperature (for example, a drop below a threshold temperature that may be at a fixed or percentage offset from the preset or user-set oven temperature). As an alternative, it may be determined that the fuel has been consumed by transmitting light through the gases in the oven chamber, in a similar manner to a domestic or industrial smoke detector so that the presence or level of smoke in the chamber can be determined. The determination that the fuel has been exhausted can be relayed to the user via the user interface so that the user may have the option to add further fuel and carry out ignition step55bonce more to continue smoking (the controller will of course need to de-energise and then re-energise the door latch24to enable access to the oven chamber). When it is determined that smoke generation has ended, for example by detecting a temperature drop downstream of the CSE26, even though the end of the user-set smoking/cooking period has not yet been reached, controller18may de-activate air injector37.

Monitoring the air temperature within smoker compartment30also provides insights into the burn condition within compartment30. Accordingly, the controller18may use the output of a smoker compartment temperature probe (not shown) to detect and monitor smoker compartment temperature while the igniter is not energised. A high temperature may indicate that combustion has been initiated and a drop in temperature may indicate that fuel is nearly exhausted or that combustion has been completed. However, a drop in temperature may also indicate that fuel still exists within compartment30but that a lack of oxygen is suffocating combustion within container30. In such a case the flow rate of air from air injector37may be increased to ensure that combustion continues until the smoker compartment temperature reaches a desirable, higher value at which point the flow rate of air injector37can again be reduced. In this way, the speed of air pump41can be adjusted to achieve an optimal burn of the fuel within smoker compartment30. If required, igniter43could also be re-energised for a predetermined time period (another 2-3 minutes, for example), with or without a change in air flow rate. A smoker compartment temperature probe may also enable detection of “flare-ups” of flames within the compartment causing a sudden increase in temperature. Detected undesirable flare-ups can be reduced to desirable smouldering combustion by reducing or cutting air supply to smoker compartment30by turning air pump41down/off (and optionally, by reducing or stopping smoke extraction by appropriately controlling fan28).

Advantages

Advantages identified in the preferred embodiments of the invention will now be discussed. Alternative embodiments of the present invention may also have one or more of these advantages.There is a convenience in not having to store the smoker20as a separate unit—it is built into the oven of the cooking appliance.The user does not need to make any connections related to the smoker20when setting up or installing the cooking appliance or when it is being used to smoke food items.The compartment30and lid34are cleaned along with the chamber13during the cooking appliance's pyrolytic cleaning process.It is easy for the user to load fuel into the smoker compartment30by simply opening chamber door17and lifting lid34.Smoke soil and smoke smell are completely contained inside the oven12and so there is no contamination of the surroundings of the cooking appliance, such as a domestic kitchen inside the user's house.Smoke production can be monitored by sensors connected to the smoker20and/or oven12so that combustion can be automatically monitored/controlled.Because the smoker20is formed in a recess or opening in the oven base31, the risk of a user accidentally destabilising the smoker20(by tipping, knocking or bumping—which conventional smokers are susceptible of) is therefore eliminated, particularly as access to the smoker compartment30is restricted by door latch24.The injection of air into smoker compartment30enhances the ignition of the fuel and ensures smoke generation is quickly and well established from the start of the smoke cycle.A steady supply of air in smoker compartment30throughout the smoke cycle is ensured to provide continuous burning of the fuel during the smoking/cooking period. A steady supply of smoke is therefore generated.Injection of air ensures that all of the fuel is exhausted by the end of the cooking/smoking period to thereby provide a “clean burn” at the end of the smoke cycle, avoiding smoke generation at the end of the nominal 1.5-2 hour smoking/cooking period so that once the oven chamber door17is opened, smoke will not escape into the cooking appliance's surroundings.The smoke regulation holes35in compartment lid34ensure a controlled flow of smoke out of the smoker compartment (aided by incoming air from air injector37) and into oven chamber13.As the smoker compartment30and air pump41are integrated into oven12, the oven can monitor and control the flow of air into the compartment30to detect flame flare-ups during the smoke cycle and act to dampen them.