Patent Application
20140311360
The present invention relates to ovens for preparing food and in particular to an oven that may be automatically switched between “closed-system” operation with moisture substantially sealed within the cooking volume and “open-system” operation with moisture vented out of the cooking volume.
High-end commercial ovens may provide for closed-system operation in which the oven volume is substantially sealed to retain heat and moisture and provide energy savings. Such closed-system operation is particularly desirable for “combination ovens” that may cook food using steam and fan driven (forced convection) hot air but is also useful in convection ovens (without steam) and rotisserie ovens.
In closed-system ovens, expanding steam and air is vented so that the cooking process is performed without significant pressurization. This venting may occur through a condenser where the steam is cooled before exiting to the outside air, reducing the heating and humidification of the kitchen environment. In one common condenser design, the steam is passed through a water bath which cools and condenses the steam. The temperature of the water bath is monitored and fresh, cool water is introduced into the water bath as the temperature rises. Excess water from the bath passes through an overflow into the building drain system.
Closed-system operation may be undesirable for the preparation of some foods, for example bread items where a crisp crust is desired. In such cases, open-system operation may be approximated, for example, by opening the oven door by a small amount during cooking to allow the exchange of steam and exterior air. This approach wastes energy, produces undesirable venting of steam and heat into the food preparation area, and may promote uneven cooking. Increased venting of a closed-system oven may also be obtained by manually bypassing or disabling the condenser.
The present invention provides a closed-system oven that may be electronically switched between open-system and closed-system operation through motorized dampers that integrated into the normal closed-system condenser design. Electric control of the dampers allows the oven to vary not simply between closed-system and open-system operation for a given cooking session, but to switch states over the course of cooking as well as to switch periodically between states to provide precise humidity control.
In one embodiment, the invention provides an oven having an insulated housing and a door to access a cooking volume and further having a heater communicating with the cooking volume to heat the cooking volume. A damper is positioned between the interior cooking volume and exterior atmosphere to be electronically actuable, according to a signal controlling an opening of the damper, to controllably allow water vapor flow between the interior cooking volume and exterior atmosphere. An electronic computer executing a program stored in memory operates to vary the signal to the damper according to user-entered data.
It is thus a feature of at least one embodiment of the invention to provide for an oven that may automatically switch between closed-system and open-system cooking modes based on user input to optimize the cooking process.
The user-entered data may, in one example, indicate a type of food being prepared.
It is thus a feature of at least one embodiment of the invention to permit proper control of the operating mode of the oven to be inferred from a food type.
In this case, the electronic computer may provide a data structure mapping a type of food to particular control data defining control of the damper suitable for cooking the type of food.
It is thus a feature of at least one embodiment of the invention to provide a flexible way of incorporating an additional dimension of oven control into existing control structures related, for example, to a set of predetermined recopies.
Alternatively, the user-entered data may indicate a desired humidity.
It is thus a feature of at least one embodiment of the invention to provide an oven offering sophisticated direct control of humidity.
The control data used to control the damper may define a duty cycle indicating a proportion between a time span when the signal controls the damper to open and a time span when the signal does not control the damper to open.
It is thus a feature of at least one embodiment of the invention to implement humidity control by switching between closed-system and open-system operation.
The damper may include a pressure-activated bypass allowing flow of water vapor between the cooking volume and the exterior atmosphere regardless of the signal when a predetermined pressure difference between the cooking volume and the exterior atmosphere is reached. In one embodiment the predetermined pressure level may be a pressure difference of less than one pound per square inch.
It is thus a feature of at least one embodiment of the invention to reduce the possibility of pressure extremes in the cooking volume such as may promote seal leakage or interfere with operation of the oven door.
The damper may include a flapper valve biased to a closed position by a biasing element and includes an electronically actuable finger controlled by the signal, where the flapper valve biasing may be overcome by either of the movement of the finger against the flapper valve or by a gas pressure difference across the flapper value.
It is thus a feature of at least one embodiment of the invention to provide a damper that incorporates both electromechanical venting and pressure bypass in a single structure.
The damper may provide a first and second intake port and the signal received by the damper may operate to alternately control the damper to allow water vapor flow preferentially between the first intake port and the exterior atmosphere or to allow water vapor flow preferentially between the second intake port and the exterior atmosphere. The first intake port may communicate with the interior cooking volume directly and the second intake port may communicate with the interior cooking volume through a steam trap.
It is thus a feature of at least one embodiment of the invention to provide an automated damper system that may integrate with a steam trap of the type suitable for closed-system oven operation.
The oven may include a motorized fan generating at least two regions of relative high and low pressure within the interior cooking volume and the first damper may have a port receiving water vapor from the region of relative high pressure and expelling it to the exterior atmosphere. The oven may further include a second similar damper positioned between the interior cooking volume and exterior atmosphere having a port at the region of relative low pressure for drawing air from the exterior atmosphere into the interior cooking volume. The electronic computer may also provide the second signal to the second damper.
It is thus a feature of at least one embodiment of the invention to provide a fan-assisted “flow-through” venting system for rapid humidity reduction.
These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention.
a and 3b are a vertical elevational cross-sectional view and a perspective view of the exhaust damper of
a and 4b are figures similar to that of
Referring now to
The cooking volume 14 may be accessed through a door 16 connected by a hinge at one vertical side of the cooking volume 14. The door 16 may close over the cooking volume 14 during the cooking operation as held by a latch assembly 15 (visible on the door 16 only). In the closed position, the door 16 may substantially seal against the cooking volume 14 by compressing a gasket 17 surrounding an opening of the cooking volume 14 in the housing 12.
At one side of the cooking volume 14, the housing 12 may support a control panel 22 accessible by a user standing at a front of the oven 10. The control panel 22 may provide conventional electronic controls such as switches, buttons, a touchscreen or the like that may receive oven control data from the user as will be described below.
Referring now also to
Alternatively steam may be provided by a separate boiler 21 having a dedicated heater element 23 and communicating with the cooking volume 14.
Ovens of this type are commercially available from the Alto-Shaam Inc. of Menomonee Falls, Wisconsin and are described generally in U.S. Pat. No. 6,188,045 “Combination Oven with Three Stage Water Atomizer” hereby incorporated by reference.
Referring still to
In either case, the drainpipe 25 allows steam and water vapor to enter the condenser chamber 30 which provides a generally enclosed box whose upstanding sidewalls retain a pool of water having a water level 36. The lower end of the drainpipe 28 passing into the condenser chamber 30 stops above the bottom wall 33 and above a water level 36.
The condenser chamber 30 may in turn communicate generally with a first electronically controllable, exhaust damper 24 through either of a bypass port 26 or a condenser port 27 of the exhaust damper 24 passing through an upper wall of the condenser chamber 30. The motorized exhaust damper 24 communicates with an exhaust pipe 29 venting to the atmosphere outside of the housing. The exhaust damper 24 operates to determine through which of these ports (the bypass port 26 or condenser port 27) water vapor may pass in exiting the condenser chamber 30 through an exhaust pipe 29 to the outside atmosphere.
A second electronically controllable intake damper 32 is positioned with its exhaust port 34 near the fan 18 to permit outside air to be drawn into the cooking volume 14 from an intake pipe 35 extending to the external atmosphere outside the housing 12. In this regard, the exhaust port 34 of the intake damper 32 will be in a low-pressure region of the cooking volume 14 when the fan 18 is operating. Conversely, the drainpipe 25 feeding the ports 26 and 27 will be in a high-pressure region of the cooking volume 14 (when the fan 18 is operating) having a higher pressure than the low-pressure region. In this way when the motorized dampers 24 and 32 are open, air is actively drawn from the outer atmosphere into the cooking volume 14 through intake damper 32 and exhausted through drainpipe 25, condenser chamber 30, and exhaust damper 24. It will be appreciated generally, therefore, that closing the motorized intake damper 32 and motorized exhaust damper 24 allows the oven 10 to operate in a conventional closed-system state to provide for high humidity, low heat loss, and low flavor transfer. Conversely opening motorized dampers 24 and 32 allows the oven 10 to operate in an open state providing low humidity. It will be appreciated that the motorized dampers 24 and 32 may be operated cyclically to open and close to provide for gradations between these two operating point extremes.
Referring to
As shown in
A variation on this design is shown in U.S. patent application Ser. No. 13/306,687 filed Nov. 29, 2011, entitled “Grease Handling Apparatus for Closed-system Oven” assigned to the same assignee as the present invention and hereby incorporated by reference.
Importantly, the internal volume of the condenser chamber 30 is divided by a vertical baffle plate 40 extending down from an upper wall of the condenser chamber 30 below the water level 32 but above the bottom of the condenser chamber 30. This baffle plate 40 provides two distinct paths of water vapor flow from the cooking volume 14 depending on a state of operation of the exhaust damper 24. In a first path, water vapor passing into the condenser chamber 30 through the drainpipe 25 may pass out of a bypass port 26 without flowing through the water. Alternatively, in a second path, water vapor passing into the condenser chamber 30 through drainpipe 25 may flow through the water and beneath the vertical baffle plate 40 to condense any steam in that flow. This latter path introduces some back pressure resulting from a resistance to gas flow through the water and therefore tends to retain moisture within the cooking volume 14 while providing a release of excess pressure only.
Accordingly, the state of operation of the exhaust damper 24 may provide either a low resistance direct venting of the cooking volume 14 to the outside atmosphere (as will be used for open-state operation) or a higher resistance in direct venting of the cooking volume 14 through the water of the condenser chamber 30 (as will be used for closed-state operation).
Referring now to
A gearmotor 61 having motor leads 62 receiving control signals from the controller board 37 may drive a hub 64 extending into the manifold 50 having diametrically opposed radially extending fingers 66 attached to rotate with the hub 64. In one direction of rotation, indicated by an arrow in
The gearmotor 61 may have a cam 67 communicating with a limit switch 68 or other sensor allowing the controller board 37 to accurately control the finger 66 to stop motion with the valve plate 54 alternately at an open and closed position corresponding to an open and closed system state of the oven as will be further described.
Referring now to
Referring now to
Referring now to
The control strategies 94 of the data structure 92 define an opening or closing of motorized dampers 24 and 32 according to a cooking schedule desired for cooking the food indicated by the icons 90. In simple cases, both motorized dampers 24 and 32 will be fully open or fully closed during an entire cooking cycle according to the control strategy 94; however, more complicated control strategies may change the state of the dampers 24 and 32 in tandem during the cooking process, for example, to begin with a high humidity cooking process and end with the low humidity cooking process.
Alternatively, the control panel 22 may present a humidity control 96 to the user, for example, providing for a bar display between zero and 100 percent humidity whose setting may be moved by a swiping gesture on a touchscreen or the like. This user-input humidity value may be provided to a procedural control function 98 operating on the controller board 37 which opens and closes the dampers 24 and 32 according to the desired humidity value.
Referring to
Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context.
When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
References to “a control board” and “a processor” can be understood to include one or more microprocessors that can communicate in a stand-alone and/or a distributed environment(s), and can thus be configured to communicate via wired or wireless communications with other processors, where such one or more processor can be configured to operate on one or more processor-controlled devices that can be similar or different devices. Furthermore, references to memory, unless otherwise specified, can include one or more processor-readable and accessible memory elements and/or components that can be internal to the processor-controlled device, external to the processor-controlled device, and can be accessed via a wired or wireless network.
It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications are hereby incorporated herein by reference in their entireties.
