System and method for draining water from a steam oven

(54) Title: SYSTEM AND METHOD FOR WATER DRAINAGE FROM A STEAM OVEN (30) Unionist Priority: 03/05/2005 us 11 / 120,408 (71) Depositor (s): Whirlpool Corporation (US) (72) Inventor (s): Malcolm Reay (74) Attorney: Dannemann, Siemsen, Bigler & Ipanema Moreira (57) Abstract: SYSTEM AND METHOD FOR WATER DRAINAGE FROM A STEAM OVEN. The present invention relates to a domestic oven comprising a cooking cavity and a steam generator for introducing steam into the cooking cavity. The oven also comprises a temperature sensor that senses a parameter representative of a water temperature in the steam generator, and the parameter is used to determine whether the water temperature is suitable for drainage. A flow controller operationally coupled to the temperature sensor is fluidly coupled to a steam generator drain and controls the drainage of water from the steam generator depending on whether the water temperature is suitable for drainage.

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Descriptive Report of the Invention Patent for SYSTEM AND METHOD FOR WATER DRAINAGE FROM A STEAM OVEN.

Background of the Invention

Field of the Invention

The present invention relates to a steam oven with a system and method for draining water having a drainage temperature from a steam generator to a domestic oven.

Description of the Related Art

Steam ovens typically comprise a heating system, such as a conventional oven, for heating a cooking cavity and a steam system for generating water vapor and for introducing steam into the cooking cavity at in order to facilitate the roasting process. Water can be supplied to the steam system from a main water supply or through a user through a user accessible water inlet. In the latter case, the inlet can be adapted to receive water directly poured out by the user or to be combined with a portable vessel that stores a water supply. The water introduced into the steam oven can be stored in an internal water tank upstream of the steam generator and supplied to the steam generator as needed. An example of a commonly used steam generator is a boiler having a chamber that holds water, which submerges an evaporation element, such as, for example, a resistive heating element. The evaporating element heats the water in the chamber to its boiling point in order to convert the water into steam for introduction into the cooking cavity.

Some steam ovens also include a drainage system in order to drain water from the steam system. The drainage system directs unused water to a main water drain or to a user accessible drainage vessel. The steam feature can be used to maintain the oven and to empty unused water when the steam system is used only occasionally. Drainage systems are also useful for the passage of descaling agents through the steam system in order to remove the hard mineral coating that tends to form on the internal surfaces of the steam generator. When the drainage system is used to drain water from the steam generator into a vessel accessible to a user, the water in the steam generator can potentially be at a temperature high enough to injure a person, especially if the steam system has recently been used. During the drainage process, the cold water in the water tank can drain with the hot water from the steam generator and, in this way, reduce the temperature of the hot water; however, the temperature of the mixture may, however, be higher than desirable for safe drainage. Therefore, it is desirable to prevent water drainage at an inadequate temperature from a steam system.

Summary of the Invention

A domestic oven according to one embodiment of the present invention comprises a housing that defines a cooking cavity, a steam generator having an inlet for receiving water, a drain, and a steam outlet operationally connected to the cooking cavity of in order to introduce steam into the cooking cavity, a temperature sensor that senses a parameter representative of a water temperature in the steam generator in order to determine if the water temperature in the steam generator is suitable for drainage, and a controller operationally coupled to the temperature sensor and fluidly coupled to the drain in order to control the drainage of water from the steam generator based on the determination of whether the water temperature is suitable for drainage.

The water temperature can be suitable for drainage when the sensed parameter is less than a predetermined limit.

The sensed parameter can be the water temperature. The temperature sensor can directly contact the water in order to sense the parameter. The temperature sensor can be located on the steam generator. The temperature sensor can directly contact the water in the steam generator in order to sense the parameter.

The flow controller can comprise a pump. The flow controller may comprise a valve.

The domestic oven may further comprise a drainage vessel having an inlet fluidly coupled to the steam generator drain, through which the drainage vessel receives drain water from the steam generator via the flow controller. The drain vessel can be removably mounted in the oven.

The domestic oven may also comprise a water reservoir upstream of the steam generator and fluidly coupled to the steam generator inlet in order to supply water to the steam generator. The water reservoir can be fluidly coupled to the steam generator through a direct fluid connection through which water from the water reservoir flows through gravity to the steam generator and drains with the water from the steam generator when the water temperature is suitable for drainage.

The domestic oven may further comprise an indicator that communicates with at least one of the water temperature condition in the steam generator and an operational condition of the flow controller. The indicator can communicate both the water temperature condition in the steam generator and the operational condition of the flow controller.

A method according to another embodiment of the present invention for draining water from a steam generator from a domestic oven comprising a housing that defines a cooking cavity, the steam generator operatively connected to the cooking cavity in order to introduce steam in the cooking cavity, the method comprises sensing a parameter representative of a water temperature in the steam generator, determining whether the water temperature is suitable for drainage, and draining the water from the steam generator when the water temperature is determined suitable for drainage.

The determination of whether the water temperature is suitable for drainage may include comparing the parameter to a predetermined limit. The parameter can be the water temperature.

The drainage of water may include the performance of a flow controller downstream of the steam generator.

The method may further comprise the communication of at least one of a water temperature condition in the steam generator and an operational condition of the flow controller. The performance of the flow controller can comprise the operation of a pump. The performance of the flow controller may include opening a valve.

The method may further comprise draining water from a water reservoir that supplies water to the steam generator while draining water from the steam generator.

Draining water may comprise draining water into a drainage vessel. The method may also include removing the drain vessel from the oven.

Brief Description of Drawings

In the drawings:

Figure 1 is a perspective view of an exemplary domestic stove, according to an embodiment of the present invention.

Figure 2 is a schematic view of a steam system for the oven of Figure 1 and having a steam generator and a drain for draining water from the steam generator according to an embodiment of the present invention.

Figure 3 is a schematic view of a control system for the oven of Figure 1, according to an embodiment of the present invention.

Figure 4 is a schematic view of a steam system for the oven of Figure 1 and having a steam generator and a drain for draining water from the steam generator, according to an alternative embodiment of the present invention.

Detailed Description of the Preferred Mode

With reference now to the figures, Figure 1 illustrates an exemplary automatic home oven 10 comprising a cabinet 12 with an open face housing 14 having a pair of spaced side walls

16, 18 connected by a top wall 20, a bottom wall 22, and a rear wall 24 so as to define an open-faced cooking cavity 26. A pivotable door 28 on a hinge 30 selectively closes the cavity 26, as well known in the furnace art. When door 28 is in the open position, a user can access cavity 26, door 28 in the closed position at the same time prevents access to cavity 26 and seals cavity 26 against the external environment. The oven 10 shown in the figures is a built-in oven, however, it is within the scope of the present invention that the oven is an independent oven.

The oven 10 further comprises a console 32 with a control panel 34 accessible to the user in order to enter the desired cooking parameters, such as temperature and time, from the manual cooking programs or in order to select the automated cooking programs. The control panel 34 communicates with a controller 36 located in cabinet 12. Controller 36 can be a proportional integral derivative controller (PID) or any other suitable controller, as is well known in the art of automatic furnaces. Controller 36 stores data, such as standard cooking parameters, manual input cooking parameters, and automated cooking programs, receives input from the control panel 34, and sends an output to the control panel. control 34 in order to display an oven 10 condition or otherwise communicate with the user. The condition of the oven 10 can be communicated through an indicator 35, which is shown in the mode illustrated as a video screen. Other exemplary indicators 35 include indicator lights and audible alarms. In addition, console 32 includes a drain switch 38, which will be described in more detail below.

With continued reference to Figure 1, oven 10 comprises a heating system 40 having an upper heating element 42, commonly referred to as a boiler, and a lower heating element 44. Figure 1 shows the lower heating element 44 as being mounted just above the bottom wall of cooking cavity 22; however, it is within the scope of the present invention that the lower heating element 44 is hidden or mounted under the bottom wall 22. In addition, the upper and lower heating elements 42, 44 can be mounted on the side walls 16, 18 cavity

26, as presented in US Patent No. 6,545,251 to Allera et al., Which is incorporated in this document as a reference in its entirety. The heating system 40 according to the illustrated embodiment further comprises a convection fan 46 which circulates air and steam, when present, within cavity 26. The convection fan 46 can be any suitable fan and can be mounted at any suitable location in cavity 26, such as, for example, on the rear wall 24. The particular type of heating system is not a closed issue to the present invention; the heating system 40 shown and described in this document is for illustrative purposes only and is not intended in any way to limit the present invention.

In addition to the heating system, oven 10 comprises a steam system 50, shown schematically in Figure 2, in order to generate steam and introduce steam into cavity 26 through a steam inlet 52 formed, for example, on the outer wall 24 of the housing 14, as shown in Figure 1. With particular reference to Figure 2, water is supplied to the steam system 50 from a supply vessel 54, which can be removably mounted in oven 10. An exemplary supply vessel and an exemplary furnace supply assembly in the furnace are presented in Wanted File No. US20040233, entitled

Steam Oven with Fluid Supply and Drain Vessel, and deposited concurrently with this order, this document being incorporated by reference in its entirety. The supply vessel 54 is fluidly connected to the inlet 56 of a water reservoir 58 through a first fluid conduit 60. The water fluid from the supply vessel 54 to the water reservoir 58 is controlled by a water reservoir valve 62 disposed between the supply vessel 54 and the water reservoir 58, as, for example, in the first conduit of fluid 60. The operation of the water reservoir valve 62 is responsive to a water level signal that is emitted from a water level sensor 64, associated with the water reservoir 58, in order to detect a water level in the reservoir water level 58. When the water level sensor 64 detects that the water reservoir 58 is substantially full, the water reservoir valve 62 closes in order to prevent the water reservoir 58 from overflowing.

The water reservoir 58 has an outlet 66 fluidly connected to an inlet 68 of the steam generator 70 through a second fluid conduit 72. The inlet 68 leads to a chamber 74 that maintains a supply of water provided from the water supply vessel 54 via water reservoir 58. According to the illustrated embodiment, chamber 74 is positioned adjacent to water reservoir 58 in such a way that water flows from water reservoir 58 to chamber 74 under gravity, and the water level in chamber 74 is equal to the level of water in the water tank 58. As a result of this configuration, the water level sensor 58 also indirectly detects the water level in the steam generator 70. The water in chamber 74 is heated by an evaporation element 76, such as, for example, a resistance heater, at least at the boiling point of the water so that the water converts to steam, which leaves chamber 74 in a steam outlet 78 for insertion into cooking cavity 26 via inlet 52.

The steam generator 70 further comprises a temperature sensor 80 in order to sense a parameter representative of a water temperature in the chamber 74, which may include direct or indirect sensing of the water temperature in the chamber. Direct sensing includes direct sensing of water. Indirect sensing includes sensing the temperature of an item, such as, for example, the chamber wall, having a known or determinable relationship with the water temperature. The temperature sensor 80 can be positioned in any suitable location in order to sense the parameter. For example, temperature sensor 80 can be mounted on steam generator 70 in direct contact with water in chamber 74, embedded in a wall of steam generator 70 in order to surround and protect temperature sensor 80, or fixed to an outer surface of the steam generator 70. In addition, the temperature sensor 80 can be mounted outside the steam generator 70, as, for example, at a location downstream of the steam generator 70, as will be described in more detail below. Temperature sensor 80 can be any suitable type of sensor, including, but not limited to, thermoelectric cells, ceramic thermistors, metallic resistance temperature devices (RTDs), and infrared temperature measurement devices.

Water can escape from the steam generator 70 through a drain 82 fluidly coupled to a drain vessel 84 through a third fluid conduit 86. Since the water reservoir 58 is fluidly coupled to the generator steam 70, any water present in water reservoir 58 will drain with water from steam generator 70. The drain vessel 84 can be removably mounted in the oven 10, and an exemplary drain vessel, and an exemplary assembly of the drain vessel in the oven are shown in the above-mentioned patent application. Optionally, oven 10 can include a vessel sensor (not shown) in order to detect the presence of the drain vessel 84 to ensure that the drain vessel 84 is positioned to receive the drained water from the steam generator 70, as presented in the aforementioned patent application. The flow of water from the steam generator 70 to the drain vessel 84 is controlled by a flow controller, shown in the embodiment illustrated as a pump 88, disposed between the steam generator 70 and the drain vessel 84, as, for example , in the third fluid conduit 86. The pump 88 moves the water from the chamber 74 to the drain vessel 84 after the actuation of the drain switch 38 mentioned above by the user.

As shown schematically in Figure 3, the drain switch 38 is operationally coupled to controller 36, which, in turn, is operationally coupled to flow controller 88. In addition, controller 36 communicates with the vessel sensor (not shown), so present that controller 36 does not activate flow controller 88 unless the vessel sensor detects the presence of the drain vessel 84. Therefore, flow controller 88 cannot drain water from steam generator 70 unless drain vessel 84 is mounted in oven 10.

Indicator 35 is also operationally coupled to controller 36, which, in turn, is operationally coupled to temperature sensor 80. When the parameter sensed by temperature sensor 80 indicates that the water temperature in the steam generator 70 is not adequate10 for drainage (that is, the water temperature is too high), controller 36 prevents the flow controller 88 from acting and thus draining water from steam generator 70. Simultaneously, controller 36 instructs indicator 35 to execute a signal, such as a visual or audio signal, to indicate to the user about at least one of the water temperature condition or a condition flow controller operating. For example, the sign may indicate that the water temperature is not suitable for drainage or that the flow controller 88 is preventing the flow of water from the steam generator 70 to the drain vessel 84. On the other hand, when the parameter sensed by the temperature sensor 80 indicates that the water temperature in the steam generator 70 is suitable for drainage, the controller 36 acts the flow controller 88 in the sense of draining the water from the steam generator 70. Simultaneously, controller 36 can instruct indicator 35 to execute a signal, such as a visual or audio signal, to indicate to the user about at least one of the water temperature or operational conditions. flow controller. For example, the sign may indicate that the water temperature is suitable for drainage or that the flow controller 88 is draining water from the steam generator 70 to the drain vessel 84. As a result of the signal, the user knows that the water is being drained from the steam generator 70.

The water level sensor 64 and the reservoir valve 62 of the steam system 50 are operationally coupled to the controller 36, as schematically illustrated in Figure 3, in order to control the flow of water to the water reservoir 58, as previously described . Controller 36 also instructs steam system 50 to activate or deactivate evaporation element 76 and provides instructions regarding the desired water temperature in steam system 50, which can be monitored by temperature sensor 80 in order to achieve a desired relative humidity in cavity 26.

Figure 3 also schematically illustrates the heating system 40 as being operationally coupled to the controller 36. Controller 36 instructs heating system 40 to activate or deactivate the upper heating element 44, the lower heating element 46, and the convection fan 48, all together, or individually, or in groups, and provides instructions with with respect to the desired temperature of cavity 26 and the speed at which the heating system 40 heats cavity 26 according to a selected cooking cycle.

In operation, a user who wants to bake a food product in oven 10 with steam provides water in the steam system 50, for example, through supply vessel 54. Water from supply vessel 54 flows into the water reservoir 58 through the first fluid conduit 60. Water flows through the water reservoir valve 62 and into the water reservoir 58 through the inlet 56 until the water in the upper vessel 54 runs out or until the water level sensor 64 detects that the water reservoir 58 is substantially full, at which point the reservoir valve 62 assumes a closed condition in order to prevent water from flowing from the supply vessel 54 to the needle reservoir 58 through the inlet 56. When water flows into water reservoir 58, water also flows into chamber 74 of steam generator 70 via the second fluid conduit 72 so that the water level in steam generator 70 is the same as in the water reservoir water 58, as described above. When the steam system 50 has a sufficient amount of water, as detected by the water level sensor 64, the controller 36 can execute a desired automatic or manual cooking cycle, as input by a user through the control panel 32 of the console 34.

In order to drain the water from the steam generator 70, the user assembles the drain vessel 84 in the oven 10, and the vessel sensor detects the presence of the drain vessel 84 and sends a signal to the controller 36 so that the controller flow controller 88 can be operated, as described above. In addition, the temperature sensor 80 senses the parameter representative of the water temperature in the steam generator 70 and sends a signal representative of the parameter to the controller 36. Controller 36 compares the parameter to a predetermined limit in order to determine whether the water temperature is suitable for drainage. According to one modality, the parameter can be the current water temperature in the steam generator, and the limit can be a maximum acceptable temperature for draining water, which turns out to be a water temperature above which the water is hot enough to make it unsafe to remove the water for the user in case the user contacts the hot water or is otherwise exposed to the heat of the hot water, such as in the event of a leak. A water temperature suitable for drainage corresponds to temperatures below the maximum acceptable temperature for water drainage, and the limit for setting a water temperature suitable for drainage can be determined empirically. An exemplary limit is about 50 ° C (122 ° F). For safety reasons, the amount of water in the water reservoir 58 that drains with the water from the steam generator 70 can be considered insignificant when determining the limit.

Then, the user activates the drain switch 38 to try to activate the flow controller 88 in order to drain the water from the steam generator drain 82 to the drain vessel 84 via the third fluid conduit 86. If the controller 36 determines that the water temperature is suitable for drainage, as, for example, by determining that the parameter is less than the limit, then flow controller 88 is activated for water drainage. As previously presented, once the water reservoir 58 is fluidly coupled to the steam generator 70, any water present in the water reservoir 58 will drain with the water from the steam generator 70. During the drainage process, the Indicator 35 can optionally communicate a signal to the user, as described above, so that the user knows that water is draining from the steam generator 70. However, if controller 36 determines that the water temperature is not suitable for drainage, as, for example, by determining that the parameter is greater than the limit, in this case controller 36 prevents the water from draining the generator. steam 70 by preventing flow controller 88 from being activated. Indicator 35 communicates a signal, as described above, to the user so that the user knows that the water temperature is not suitable for drainage and that the water is not being drained from the steam generator 70. The user can wait for a period of time for the water in the steam generator 70 to cool and then make another attempt to drain the water.

A steam system 50 according to another embodiment of the present invention is illustrated in Figure 4, in which elements similar to those of the steam system of the first embodiment 50 are identified with the same reference numerals. The steam system 50 of the present embodiment is substantially identical to the steam system 50 of the previous embodiment, with the exception that the temperature sensor 80 is positioned in the third fluid conduit 86 downstream of the steam generator 70, and the temperature controller The flow is in the form of a drain valve 88. The temperature sensor 80 located downstream of the steam generator 70 senses the representative parameter of the water temperature in the steam generator 70. Before the flow controller 88 acts to drain the water, the water in the third fluid conduit 86 upstream of the closed flow controller 88 is at a temperature equal to or less than the water temperature in the steam generator 70. If there is a temperature differential between the water in the steam generator 70 and the water in the third fluid conduit 86, the controller 36 can meet this known differential by determining when the water in the steam generator 70 is suitable for drainage.

The flow controller 88 can be in the form of a drain valve, as shown in Figure 4, when the drain vessel 84 is arranged in a location, such as a location vertically below drain 82, which does not require assistance of a pump to move the water from the steam generator 70 to the drain vessel 84. Drain valve 88 is operable between a closed condition, in which water cannot flow through drain valve 88 to drain vessel 84, and an open condition, in which water can flow through drain valve 88 to the drain vessel 84. The flow controller 88 in the form of the drain valve is operationally coupled to the controller 36 and, in this way, the temperature sensor 80 in the same way as previously described for the flow controller in the form of a pump. Thus, controller 36 prevents the opening of drain valve 88 when the water temperature is not suitable for drainage, as described above.

Although the oven according to the present invention has been described above and shown in the figures with respect to the illustrative modalities, it is within the scope of the present invention to modify certain aspects of the steam system. For example, the supply vessel and the drain vessel can be configured as a single vessel, as described in the aforementioned patent application. In addition, water can be supplied to the steam system in a different way than through the supply vessel. For example, the water tank can be connected to the main water supply, and the water supply system can include a pressure regulator in order to control the pressure of the water entering the steam system. In the steam system, the internal reservoir can be integrated with the chamber in the steam generator in such a way that the water in the vessel is supplied directly to the steam generator. When the steam system comprises the water reservoir, the steam system may include a valve positioned between the water reservoir and the steam generator in order to control the flow of water to the steam generator. In addition, the steam generator can be any suitable system capable of converting water to steam for introduction into the cavity or capable of introducing water into the cavity which turns into steam in the cavity and is not limited to the system shown schematically in the figures.

Although the present invention has been specifically described with respect to certain specific modalities thereof, it should be understood that these are for the purpose of illustration and not limitation, and that the scope of the appended claims must be constructed in such a broad way as the prior art will allow.

Reference Listing

- oven

- cabinet

- accommodation

- side wall

- side wall

- top wall

- background wall

- rear wall

- cooking cavity 28 - door 30 - hinge 32 - console

- control panel

- indicator

- controller

- drain switch 40 - heating system 42 - upper heating element 44 - lower heating element 46 - convection fan

- steam system

- steam inlet

- supply vessel 56 - water reservoir inlet 58 - water reservoir 60 - first fluid conduit 62 - water reservoir valve 64 - water level sensor 66 - water reservoir outlet 68 - steam generator inlet 70 - steam generator

- second fluid line 74 - chamber

- evaporation element 78 - steam outlet 80 - temperature sensor 82 - drain

- drainage vessel

- third fluid conduit 88 - flow controller * w) 9

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