COMBINATION OVEN AND ASSOCIATED OVEN DELIME PROCESS

TECHNICAL FIELD

[0001]This application relates generally to ovens that utilize a steam generator to feed steam into an oven cavity and, more specifically, to combination ovens utilizing steam generators.

BACKGROUND

[0002]Combination ovens commonly include a cooking cavity with an associated heating device (e.g., resistive heating element(s) or combustion gas heat exchange tube(s)) and a steam generator to deliver steam into the cooking cavity. Oven cavities that encounter hard water during cooking or cleaning inevitably develop white residue and calcium buildup, impacting both the cavity and the steam generator. Even in ovens utilizing a steam generator, where there is no direct liquid water contact with the cavity, white residue can still form and accumulate inside the cavity during the steam process. This accumulation can lead to issues such as improper heating, clogged drains, excessive water usage, burnt heating elements, and the frequent replacement of components that interact with water, such as the cavity, steam generator, boiler, baffle or air deflector plates, impellers, wire racks, and rack guides.

[0003]In the past, deliming of the steam generator has been carried out, but neglected the deliming of the cavity. U.S. Pat. No. 8,080,766 discloses a steam oven system in which deliming of both a steam generator and a steam superheater take place. However, the cooking cavities are not delimed.

[0004]Accordingly, it would be desirable to provide an oven with a delime process that addresses both the steam generator and the cooking cavity.

SUMMARY

[0005]In one aspect, in an oven including a cooking cavity and a steam generator connected for delivering steam into the cooking cavity, a method of carrying out an oven delime operation comprising the steps of: delivering a delime chemical into the steam generator to produce a delime solution in the steam generator; and after the delime solution has been produced in the steam generator, draining the delime solution from the steam generator to a drain reservoir associated with the cooking cavity and subsequently recirculating the delime solution from the drain reservoir to the cooking cavity and back to the drain reservoir.

[0006]In another aspect, an oven includes a housing defining a cooking cavity, the cooking cavity accessible via a door that is movable between an open position and a closed position relative to the cooking cavity. A steam generator is connected for delivering steam into the cooking cavity. A delime chemical feed path into the steam generator and a water feed path into the steam generator are both provided. A drain reservoir is connected to the steam generator via a steam generator drain path, and the drain reservoir connected to the cooking cavity via a cooking cavity drain path. A circulation path is provided from the drain reservoir to the cooking cavity, with a wash pump located along the circulation path for delivering liquid from the drain reservoir to the cooking cavity during operation of the pump.

[0007]In a further aspect, an oven includes a housing defining a cooking cavity, the cooking cavity accessible via a door that is movable between an open position and a closed position relative to the cooking cavity. A steam generator is connected for delivering steam into the cooking cavity. A water feed path into the steam generator is provided. A drain reservoir is connected to the steam generator via a steam generator drain path, the drain reservoir connected to the cooking cavity via a cooking cavity drain path. A delime chemical feed path into at least one of the steam generator or the drain reservoir is provided. A circulation path is provided from the drain reservoir to the cooking cavity, with a wash pump located along the circulation path for delivering liquid from the drain reservoir to the cooking cavity during operation of the pump.

[0008]The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a schematic depiction of a combination oven; and

[0010]FIGS. 2-9 show an exemplary sequence of oven deliming.

DETAILED DESCRIPTION

[0011]Referring to FIG. 1, a schematic depiction of a combination oven 10 is shown. The combination oven includes a housing 12 defining a cooking cavity 12a, the cooking cavity accessible via a door 12b that is movable between an open position and a closed position relative to the cooking cavity. A steam generator 14 (e.g., tank with internal heating device 14a and water level probe 14b) is connected for delivering steam into the cooking cavity (e.g., via steam delivery path 16). The heating device 14a may be a resistive heating element or may be a heat exchange tube with a controllable a gas burner. A delime chemical feed path 18 into the steam generator and a water feed path 20 into the steam generator are both provided, with a chemical pump 18a along the feed path 18 (for controlling delivery of a delime chemical from a chemical source 18b) and a valve 20a positioned along the water feed path 20 for controlling deliver of water from a fresh water input 20b to the oven.

[0012]A drain reservoir 22 (e.g., drain box or drain tank) is connected to the steam generator via a steam generator drain path 24, and the drain reservoir 22 is connected to the cooking cavity 12a via a cooking cavity drain path 26. A valve 24a is located along the steam generator drain path 24. A circulation path 30 from the drain reservoir 22 to the cooking cavity 12a is provided, with a wash pump 30a located along the circulation path 30 for selective delivery of liquid from the drain reservoir 22 to the cooking cavity during operation of the wash pump 30a. One or more spray nozzles 30b may be provided for spraying the liquid into the cooking cavity 12a.

[0013]A valve 32a is located along a drain path 32 from the drain reservoir, which drain path 32 leads to a drain outlet 32b of the oven.

[0014]The cooking cavity 12a includes a heating device 34, in the form of a heat exchange tube or tubes with associated controllable gas burner(s) or in the form of one or more resistive heating elements, within the cooking cavity, and an air mover (e.g. fan/impeller with associated motor) 36 within the cooking cavity.

[0015]A controller 100 is configured for controlling operation of the valves 20a, 24a, 32a, the wash pump 30a, the chemical feed pump 18a, the heating device 34 and the air mover 36. The controller 100 is also connected to receive input from the probe 14b and can control the heating device 14a (e.g., a heat exchange tube with associated controllable gas burner, or a resistive heating element). As used herein, the term controller is intended to broadly encompass any circuit (e.g., solid state, application specific integrated circuit (ASIC), an electronic circuit, a combinational logic circuit, a field programmable gate array (FPGA)), processor(s) (e.g., shared, dedicated, or group - including hardware or software that executes code), software, firmware and/or other components, or a combination of some or all of the above, that carries out the control functions of the machine or the control functions of any component thereof.

[0016]The controller 100 is configured for operation in one or more cooking modes. For example, in a convection cooking mode, the controller may control the heating device 34 to achieve a desired cooking temperature (e.g., from 150° F. to 400° F. or higher, such as 500° F.) in the cavity 12a without operating the steam generator 14 to produce steam. In a steam cooking mode the controller may operate the steam generator 14 to produce steam that is delivered into the cavity 12a without adding heat via the heating device 34 In a combination mode the controller may control both the heating device 34 to add heat and the steam generator 14 to add steam. The oven may include one or more temperature sensors, humidity sensors and vent paths to achieve desired cooking conditions.

[0017]The controller 100 is also configured for operation in at least one oven delime mode. The sequence of FIGS. 2-9 depicts one example of a delime sequence carried out by the controller 100 in an oven delime mode.

[0018]In FIG. 2, valve 20a is opened to fill the steam generator to a set fill level indicated by the probe 14b. Once the water reaches the set fill level, the valve 20a is closed. Per FIG. 3, the chemical pump 18a is then turned on to deliver delime chemical into the steam generator for mixing with the water to create a delime solution and the pump 18a is then turned off. The delime chemical effectively mixes with the water and remains in the steam generator for a short time period (e.g., at least 3 seconds, such as 5 seconds or more).

[0019]After the set time period elapses, per FIG. 4, valve 24a is opened to drain the delime solution from the steam generator 14 into the drain reservoir 22. Once all the water has been drained from the steam generator, the valve 24a is closed and, per FIG. 5, the wash pump 30a is turned on, and the air mover 36 is operated to move air. Delime solution from the drain box is thereby pumped into the cavity 12a and recirculated for a specific cavity deliming time period (e.g., at least 2 minutes, such as at least 5 minutes or at least 8 minutes). The air mover 36 generates airflow inside the cavity 12a, helping to evenly distribute the delime solution across the cavity walls.

[0020]After the cavity deliming time period is complete, per FIG. 6, the wash pump is turned off, and the delime solution which has collected in the drain reservoir is drained from the machine by opening the valve 32a until all of the deliming solution is drained. After the deliming solution is drained, per FIG. 7, the valve 32a is closed and the valve 20a is opened to deliver fresh water into the steam generator 14, and valve 24a is also open at this time to deliver the fresh water to the drain reservoir. This fresh water delivery may be carried out for a specified reservoir fill time period (e.g., a predetermined time period that is sufficient to fill the drain reservoir to a desired level), after which, per FIG. 8, both valves 20a and 24a are closed and the wash pump 30a turned on to circulate the water to the cavity for rinsing of the cavity for a specified rinsing time period (e.g., at least 2 minutes, such as at least 5 minutes or at least 8 minutes). Air mover 36 may also be operated during the rinsing water recirculation.

[0021]After the rinsing time period, per FIG. 9, the wash pump 30a is turned off, and valve 32a is opened to send the rinse water to the drain outlet 32b. After sending the rinse water to the drain outlet, the valve 32a is closed, and the cavity heating device 34 will be turned on for a specific drying time to dry the cavity. After this drying time, the delime sequence is completed and the oven is then ready to be used for cooking.

[0022]It is to be clearly understood that the above description is intended by way of illustration and example only, is not intended to be taken by way of limitation, and that other changes and modifications are possible. For example, in embodiments, the delime chemical feed path 18 could feed into the drain reservoir or an additional delime chemical feed path into the drain reservoir could be provided.