[0001] The present invention relates to a water management system for a steam oven, a steam
oven, and a method for operating a water management system and/or a steam oven.
[0002] Steam ovens are a well-known category of appliances, dedicated to cooking purposes.
Steam ovens are existing, in a first variant, as solo steam appliances. In solo steam
appliances, exclusively pure steam cooking functions are available, as no heating
systems beside a steam generator are available. In a second variant, steam ovens are
existing as combi steam appliances. In combi steam appliances, steam can be used alone
for cooking, or combined with other heating systems, to merge the heating effect of
steam with the one of hot air.
[0003] To create steam there needs to be available a water supply of a water feeding system
which leads the water into the steam generation system.
[0004] When using steam ovens as available on the market, the users are asked to regularly
descale the steam generation system in order to remove the lime stone which is collected
in the steam generation system.
[0005] A descaling operation removes scale from the steam generation system. It removes,
for example, limescale, limestone, calcium and/or layers of oxides formed on the surfaces
of the steam generation system.
[0006] Some steam ovens are asking the user in the set-up process of the appliance to give
an indication on the water hardness level in order to define the right interval of
performing such a descaling procedure.
[0007] The majority of steam ovens as available on the market are equipped with a dedicated
descaling function of the steam generation system. The indication when such a descaling
process needs to be done is either defined in the user manual and it depends on the
user to perform it in time, or steam ovens are available which have an internal counter
in the software depending on the water hardness level which is defined by the user,
which tells the user when to perform such a descaling process.
[0008] In ovens as available on the market there is no feedback about the real water hardness
level and no feedback from the steam generator about the real quantity of lime stone
and thus the right time to perform such a descaling process can be just estimated.
This can result in a decreased steam generation performance and thus decreased food
quality or even in an accumulation of lime stone particles which could harm the steam
generation system including tubes and valves.
[0009] This invention is especially meant to provide an enhanced approach to the water management
in steam ovens. It is an object of the present invention to overcome the above drawbacks
and problems.
[0010] These problems are solved by the subject matter of the attached independent claims.
Preferred embodiments may be taken from the dependent claims.
[0011] The above described problems are advantageously solved by a water management system
for a steam oven according to claim 1, a steam oven according to claim 13, and a method
for operating a steam oven and/or a water management system according to claim 15.
[0012] According to claim 1, the invention relates to a water management system for a steam
oven, comprising
- a water softening system comprising a water inlet and a water outlet,
- wherein the water inlet is connected (or: connectable) to a water supply,
- wherein the water outlet is connected (or: connectable) to a steam generation system
of the steam oven,
- wherein the water softening system comprises water-hardness reduction means to reduce
a water hardness of a water stream,
- further comprising a or at least one sensor means for providing sensor values of the
water stream to an estimation unit and
- further comprising an estimation unit to estimate based on the sensor values whether
the water hardness of the water stream is within a predefined range.
[0013] In an embodiment, a first water stream, especially hard water or inlet water, from
the water supply flows or can flow through the water inlet and a second water stream,
especially soft water or softened water, for the steam generation system flows or
can flow through the water outlet. Preferably, the second water stream comprises softened
water compared to the first water stream.
[0014] Preferably, the water softening system comprises water-hardness reduction means to
reduce a first water hardness of a or the first water stream at the water inlet to
a second water hardness of a or the second water stream at the water outlet.
[0015] The sensor means can preferably be arranged at or near the water outlet and/or at
or near the water inlet for providing sensor values of the first water stream and/or
of the second water stream to the estimation unit.
[0016] Preferably, the estimation unit is configured to estimate based on the sensor values
whether the water hardness of the water stream, especially of the second water stream,
is within a predefined range and/or whether the water softening system shall be restored.
[0017] A water management system according to the invention therefore is especially a water
hardness management system, whereas also a sanitizing unit and a flood prevention
unit can preferably be included in the water management system.
[0018] Preferably, the water-hardness reduction means comprises or uses at least one or
more of ion exchange resins, phosphates dispensers and reverse osmosis systems, preferably
contained in at least one cartridge.
[0019] In an embodiment, the water-hardness reduction means and/or the at least one cartridge
can interact and/or deal with a total fixed amount of ions, especially of Ca and/or
Mg, corresponding to a total amount of water. Dealing with a total fixed amount of
Ca and/or Mg can especially mean exchanging the Ions, for example the Ca-Ions (Ca++;
Calcium-Ions) and/or the Mg-Ions (Mg++; Magnesium-Ions) against Na-Ions (Na+; Natrium-Ions)
and/or dispensing phosphates and/or pressing the water through a membrane.
[0020] Dealing with a total fixed amount of water preferably means that for this fixed amount
of water, the water hardness of the water stream is within the predefined range. The
total amount of water can preferably be variable depending on the hardness of the
water stream from the water supply.
[0021] Ion exchange resins can preferably be regenerated, for example by the use of Natrium
Chloride (NaCl) to recover their water-hardness reduction functionality. This proceeding
can be also used in water softening systems (water softneners) for dishwashers.
[0022] The estimation unit preferably estimates based on the sensor values whether the water
hardness of the, especially second, water stream is within a predefined range, wherein
the estimation unit preferably estimates based on the sensor values whether the water
hardness of the, especially second, water stream is below a predefined level, for
example below 3° F or below 7°F. Alternatively or in addition, a water hardness of
the, especially second, water stream within a predefined range can preferably mean
that the water hardness is above a predefined lower threshold and below a predefined
upper threshold.
[0023] Preferably, when the sensor means and/or the estimation unit estimates based on the
sensor values that the water hardness of the water stream, especially of the second
water stream, is not within the predefined range and/or that the water softening system
shall be restored, an expiration of the softening cartridge is identified and/or a
service operation is triggered, wherein the service operation is preferably either
a regeneration or a replacement of the at least one cartridge. In some embodiments,
a replacement of the at least one cartridge is or can be privileged.
[0024] Preferably, the at least one cartridge is dimensioned to expire at around 2 years,
after 2 years or after more than 2 years. Preferably, for oven applications, a relatively
low amount of water is needed for the water stream.
[0025] The first water stream preferably corresponds to hard water or inlet water of the
water softening system. The second water stream preferably corresponds to soft water
or outlet water of the water softening system. Therefore, preferably, water of the
first water stream enters the water softening system at the water inlet, is softened
within the water softening system and then leaves the water softening system at the
water outlet as second water stream. Water softening is preferably achieved using
softening active matter, especially lime softening and/or ionexchange resins.
[0026] The water hardness (or: water hardness level) is preferably determined by the concentration
of mineral content in the water, especially by the concentration of ions and/or of
multivalent cations. More preferably, the water hardness is determined by the sum
of the molar concentrations of Ca
2+ and Mg
2+. The sum can be expressed in mol/L or mmol/L units. Various alternative units preferably
represent an equivalent mass of calcium oxide (CaO) or calcium carbonate (CaCO
3) that, when dissolved in a unit volume of pure water, would result in the same total
molar concentration of Mg
2+ and Ca
2+.
[0027] Water hardness is often not expressed as a molar concentration, but rather in various
units, such as degrees of general hardness (dGH or °dH), parts per million (ppm, mg/L
or American degrees) or French degrees (°fH, °f or °F). Parts per million (ppm) is
usually defined as 1 mg/L CaCO
3. It is equivalent to mg/L without chemical compound specified. A degree of General
Hardness (dGH, °dH or deutsche Härte) is defined as 10 mg/L CaO or 17.848 ppm. A French
degree (°fH or °f or °F) is defined as 10 mg/L CaCO
3, equivalent to 10 ppm. The abbreviation "L" (or: "l") preferably corresponds to "liter".
The unit mg /L (or: mg/l) preferably corresponds to mg/L CaCO
3 or to mg/L CaO.
[0028] Hard water is preferably water with a high concentration of mineral content and/or
water which comes from the water tap or a water feeding system. More preferably, hard
water can be water which contains more than 120 ppm or 6.75 dGH or 6.75 °dH or 67.5
mg/L CaO.
[0029] Preferably, hard water can be at least one of more of moderately hard water, hard
water, very hard water and/or extremely hard water. Possible, especially predetermined,
ranges for the water hardness of especially hard water can between 7°F and more than
32°F, between 4°dH and more than 18°dH and/or between 70 and more than 320 mg/L especially
of CaCO
3, respectively. Possible ranges for moderately hard water are between 4°dH and 8°dH
or between 70 and 140 mg/L CaCO
3, respectively. Possible ranges for hard water can also be between 8°dH and 13°dH
or between 140 and 220 mg/L CaCO
3, respectively. Possible ranges for very hard water are between 13°dH and 18°dH or
between 220 and 320 mg/L CaCO
3, respectively. Possible ranges for extremely hard water are above 18°dH or above
320 mg/L CaCO
3, respectively.
[0030] Soft water is preferably water with a low concentration of mineral content and/or
water after a treatment by the water softening system. More preferably, soft water
can be water which contains less than 60 ppm or 3.37 dGH or 3.37 °dH or 33.7 mg/L
CaO. Possible ranges for soft water are between 0°F and 7°F, between 0°dH and 4°dH
and/or between 0 and 70 mg/L especially of CaCO
3, respectively.
[0031] The following table shows the classifications, thresholds, ranges and/or hardness
levels for soft water, moderately hard water, hard water, very hard water and extremely
hard water. A predefined range of the water hardness of the water stream can preferably
be at least one of the following ranges and/or a combination thereof.
Classification |
Water Hardness in mg/L |
Water Hardness in °dH |
Water Hardness in °F |
Soft |
0-70 |
0-4 |
0-7 |
Moderately hard |
70-140 |
4-8 |
7-14 |
Hard |
140-220 |
8-13 |
14-22 |
Very hard |
220-320 |
13-18 |
22-32 |
Extremely hard |
>320 |
>18 |
>32 |
[0032] Preferably, a predefined range of the water hardness of the water stream is one of
or a combination of the above defined ranges. A predefined range of the water hardness
of the water stream therefore may be for example, a range between 0°F and 7°F and/or
0°dH and 4°dH and/or between 0 and 70 mg/L especially of CaCO
3.
[0033] Preferably, the water management system avoids a descaling operation of the steam
generation system of the steam oven. Preferably, the water management system integrates
a self-diagnosing, regeneration free, water softening system into the steam oven.
[0034] The water management system can also prevent the need to deal with chemicals to perform
the descaling operation of the steam generation system. Preferably, the water management
system eliminates downtime of the steam oven due to a descaling operation.
[0035] Furthermore, the water management system can improve the efficiency of the steam
generation system by eliminating the steady process of limestone accumulation and
subsequent removal.
[0036] The water softening system can be integrated into the steam oven or can be externally
to the steam oven. In an embodiment, the water softening system is adapted and/or
connected to the water supply. The water supply can be a water tap and/or a water
tank and/or a fixed water connection and/or a water pipe and/or a fixed or removable
drawer and/or a water feeding system.
[0037] The water supply for the steam oven and/or the water softening system can preferably
be set up as a fixed water tank of the oven which needs to be filled using an additional
water jar. Furthermore or as an alternative, the water supply for the steam oven can
preferably be set up as an extractable water tank which can be extracted from the
oven and filled directly on a water tap. Furthermore, the water supply for the steam
oven can preferably be set up as a fixed water connection to the water supply system
of the house, for example to a water tap.
[0038] The water management system is preferably dimensioned to keep the, especially second,
water stream below a water hardness target for a defined amount of supplied water,
in order to cover a predefined steam oven usage time, more preferably the whole lifetime
of the oven.
[0039] In addition, the water management system can provide long term duration of the steam
oven, preferably life long duration without service and/or descaling.
[0040] In an advantageous embodiment, the water management system is intended to treat a
predefined amount of water in the, especially first, water stream, wherein the steam
generation system is able to handle a predefined amount of minerals as residual hardness
of the second water stream, so that the oven is able to run a predefined number of
steam cycles.
[0041] In a specific embodiment, the water management system can be intended to treat a
predefined amount of 500 to 800 1, especially 750 1, of water in the, especially first,
water stream, wherein the steam generation system is able to handle a predefined amount
of approximately 15 g to 21 g minerals as residual hardness of the, especially second,
water stream, so that the steam oven is able to run a predefined number of 400 to
600 steam cycles, preferably with a maximum water consumption of each cycle of 11
and/or applying a safety factor of 1 to 1,5.
[0042] Preferably, the residual hardness shall be dimensioned to leave behind an concentration
of mineral content in the water that the system and/or the oven can handle without
impairment and/or damage. In the above mentioned or in another embodiment, the water
management system can be intended to provide the, especially second, water stream,
preferably softened water, with a water hardness below 3° F or below 7° F and/or 3
mg/l or 7 mg/l of Ca-CO
3 to the steam generation system.
[0043] Preferably, the water management system is capable to handle different levels of
water hardness of the first water stream, preferably automatically or by a calibration
process performed during the installation of the steam oven.
[0044] In an advantageous embodiment, the sensor means comprises a water hardness sensor
means and/or a volume counter and/or a flow measurement unit. The sensor means can
further include, in an embodiment, a flow rate sensor and/or a water detection means
and/or a water volume counter. The sensor means or a part of it is preferably placed
in an area where water could flow in case of failures or uncontrolled water supply.
Therefore, preferably uncontrolled water supply can be avoided.
[0045] In an embodiment, preferably for a first class of sensor means, the sensor means
perform and/or can perform a direct measurement of the water hardness. Such a sensor
means can preferably directly measure the water hardness, preferably at the water
outlet, immediately identify when the water softening system ceases or reduces its
performance, and preferably indicate the need for restoration or regeneration of the
water softening system. Examples for such sensor means are conductivity sensor means,
optical sensor means or capacitive sensor means. An advantage of such sensor means
may be the direct feedback on the final outflow water hardness at the water outlet,
regardless of possible contingencies like, for example, water hardness fluctuations,
mechanical failures and/or defective components of the system.
[0046] In a further embodiment, preferably for a second class of sensor means, the sensor
means perform and/or can perform a total cumulative water amount calculation of the
water stream, for example by volumetric counters or flow meters. Based on the second
class of sensor means, the estimation unit can preferably determine and/or indicate
softening system expiration by assuming the hardness of the water at the water inlet
constant, while the maximum amount of water the water softening system can treat is
preferably predetermined. Even though the second class of sensors can be blind to
contingencies like, for example, water hardness fluctuations, mechanical failures
and/or defective components of the system, the second class of sensors is normally
easier to integrate and can be more economical.
[0047] The first and second classes of sensors, for the purpose of the invention, can work
alone, or can be combined as a sensor means to ensure or enable double check of the
water hardness, for example.
[0048] In an embodiment, preferably for a third class of sensor means, the sensor means
measures and/or can measure water spillage and/or perform leakage detection via threshold
conductivity sensors or floater based sensors. Also this third class of sensors, for
the purpose of the invention, can work alone, or can be also be combined in a sensor
means with one or more of the first and second class to ensure or enable double check.
[0049] The first category of sensors is preferably put downstream the water softening system,
for example at or near the water outlet. The first category of sensors preferably
monitors the supposedly softened water. The second category can preferably be placed
before or after the water softening system, for example at or near the water inlet
and/or at or near the water outlet, as the water flow is at least essentially the
same.
[0050] The water management system can comprise a flood prevention system, especially an
integrated anti-flooding system. Flood prevention means can be common practice, for
example, for built-in ovens, and can be even mandatory for high-end ovens.
[0051] Preferably, the flood prevention system is intended to stop the first water steam
after a continuous flow of a determined amount of litres of water.
[0052] In an embodiment, the flood prevention system comprises a valve for blocking the
water supply.
[0053] The flood prevention system can be connected to the sensor means, wherein the sensor
means especially comprises a water detection means and/or a volume counter, so that
the valve can be closed upon water detection and/or uncontrolled water supply.
[0054] Preferably, the flood prevention system comprises at least two means: a first means,
preferably a or the sensor means, to detect anomalies related to the water supply,
and a second means, preferably a valve, more preferably an electric valve, to stop
water flow from the water inlet in case of such anomalies.
[0055] The second class of sensor means can preferably be used to replace the third class
of sensor means. Preferably, the, especially second class of, sensor means is integrating
at least two functions, for example a flood prevention system as well as a water hardness
determination or estimation.
[0056] Preferably, the water softening system upon reach of a predefined overall amount
of water and/or upon exceeding a predefined threshold for the water hardness can or
shall be restored. Preferably, the water softening system contains a disposable cartridge
containing the softening material, especially the softening active matter. The disposable
cartridge is a preferred means to reduce a first water hardness of the first water
stream at the water inlet to a second water hardness of the second water stream at
the water outlet.
[0057] The water softening system can be restored preferably by changing or renewing the
disposable cartridge containing the softening material, especially the softening active
matter. The softening material, especially the softening active matter, preferably
converts hard water into soft water.
[0058] The water softening system can be intended to provide an indication to the user that
the softening system must be restored and/or to prevent the steam oven to generate
steam until the softening function has been restored, to avoid processing water with
excess of hardness and resulting limestone layer creation.
[0059] Preferably, the water softening system is providing an automatic system to detect
and to preferably communicate to the user when the softening effectiveness is over
or falls below a predefined level.
[0060] In an advantageous embodiment, the water softening system comprises a means to understand
when the target or predefined overall amount of water has been reached, to avoid a
supply of water exceeding a water hardness threshold to the steam generation system.
[0061] Preferably, the water softening system and/or the water management system provides
a direct measurement of the water hardness. More preferably, the sensor means comprises
a water hardness sensor in order to perform a direct measurement of the water hardness,
which can be installed downstream the softening system.
[0062] As an alternative or in addition, the water softening system and/or the water management
system can provide an indirect measurement or estimation of the remaining autonomy
of the water softening system, especially whether the second water stream is within
a predefined range of water hardness and/or whether the water softening system shall
be restored.
[0063] For the indirect measurement or estimation of the remaining autonomy of the softening
system and/or the water hardness of the, especially second, water stream, the sensor
means preferably comprises a volumetric counter buffering the total amount of water
treated by the water softening system and provided to the steam generation system.
[0064] The water softening system can also comprise a sanitizing unit, which can be integrated
into the water softening system and/or into the oven. Preferably, the sanitizing unit
comprises means to prevent microbial proliferation over the life span of the oven.
[0065] The sanitizing unit can comprise antimicrobial additives in the materials constituting
the components in contact with the water and/or sanitizing agent dispensers.
[0066] According to claim 13, the invention relates to a steam oven with a water management
system according to the invention.
[0067] In an embodiment, the steam oven can be a solo steam appliance, wherein exclusively
pure steam cooking functions are available, as no heating systems beside the steam
generation system are available. As an alternative, the steam oven can also be a combi
steam appliance, wherein steam can be used alone for cooking, or combined with other
heating systems, to merge the heating effect of steam with other heating systems.
Heating systems can be convection heating and/or hot air and/or upper heat and/or
lower heat.
[0068] The steam oven can preferably be an electric and/or domestic oven and/or a household
oven.
[0069] The steam oven can preferably be a built-in oven, a stand-alone-oven, a high-end
oven, a low class oven or a mid-range oven.
[0070] The steam oven can preferably comprise one or more of the following: a housing, an
oven cavity, an oven door with a handle or grip, a convection heating unit in combination
with a convection fan and/or an air baffle, an upper heating unit, a lower heating
unit and a fan for sucking air out of the cavity through a suction hole.
[0071] Preferably, the steam oven comprises one or more of the following: a steam generation
system with a pipe to submit steam into the oven cavity, an oven control unit with
an estimation unit and a flood prevention unit, an operating panel for operating the
oven as well as items to be cooked arranged on a baking tray.
[0072] According to claim 15, the invention also relates to a method for operating a water
management system and/or a steam oven, especially according to one of the preceding
claims, comprising
- a water softening system comprising a water inlet and a water outlet,
- wherein the water inlet is connected or connectable to a water supply,
- wherein the water outlet is connected or connectable to a steam generation system
of the steam oven,
wherein the method comprises the following steps:
- reducing, by means of the water softening system, a water hardness of the water stream,
- providing, by sensor means sensor values of the water stream to an estimation unit
and
- estimating by means of the estimation unit, based on the sensor values, whether the
water hardness is within a predefined range.
[0073] In an embodiment, a first water stream, especially hard water or inlet water, flows
or can flow from the water supply through the water inlet and a second water stream,
especially softened water, for the steam generation system flows or can flow through
the water outlet.
[0074] Preferably, the method further comprises the following step: reducing, by means of
the water softening system, a first water hardness of the first water stream at the
water inlet to a second water hardness of the second water stream at the water outlet,
[0075] The method can further comprise preferably the following step: providing, by sensor
means at the water outlet and/or at the water inlet, sensor values of the first water
stream and/or of the second water stream to an estimation unit.
[0076] Preferably, the method further comprises the following step: estimating by means
of the estimation unit, based on the sensor values, whether the water hardness is
within a predefined range and/or whether the water softening system shall be restored.
[0077] The present invention will be described in further detail with reference to the drawing
from which further features, embodiments and advantages may be taken, and in which:
- FIG 1
- shows a system for a water management system and a steam oven according to an embodiment
of the invention.
[0078] FIG 1 shows an embodiment of the invention which is further described in the following.
FIG. 1 shows a steam oven 2 as an electric domestic oven. The oven 2 comprises an
oven cavity 90 which is arranged within a housing 91. At the front side, the oven
cavity 90 is delimited by an oven door 46 with a handle or grip 45.
[0079] The oven 2 further comprises, at the back side of the cavity 90, a convection heating
unit 42 in combination with a convection fan 44 and an air baffle 48.
[0080] The oven 2 further comprises a not shown upper heating unit, a lower heating unit
47 and a fan 50 for sucking air out of the cavity 90 through a suction hole 53 as
input and an output channel 52 as an output.
[0081] The oven 2 further comprises a steam generation system 70 with a pipe 71 to submit
steam into the oven cavity 90. An oven control unit 30 provides control functions
for the oven. The oven control unit 30 comprises an estimation unit 31 and a flood
prevention unit 33. The oven 2 further comprises an operating panel 51 at its front
side above the door for operating the oven 2. Within the cavity 90, items to be cooked
94 are arranged on a baking tray 93.
[0082] FIG 1 further shows a water management system 1 for the steam oven 2. The water management
system 1 comprises a water softening system 20. The water softening system 20 comprises
a water inlet 22 and a water outlet 23. The water inlet 22 is connected or connectable
to a water supply 61.
[0083] The water outlet 23 is connected or connectable to the steam generation system 70
of the steam oven 2. A first water stream 11, especially hard water or inlet water,
from the water supply 61 flows or can flow through the water inlet 22. A second water
stream 12, especially soft water or softened water, for the steam generation system
70 flows or can flow through the water outlet 23.
[0084] The following table shows the classifications, thresholds, ranges and hardness levels
for soft water, moderately hard water, hard water, very hard water and extremely hard
water. A predefined range of the water hardness of the water stream 11, 12 can be
at least one of the following ranges and/or a combination thereof.
Classification |
Hardness in mg/L |
Hardness in °dH |
Hardness in °F |
Soft |
0-70 |
0-4 |
0-7 |
Moderately hard |
70-140 |
4-8 |
7-14 |
Hard |
140-220 |
8-13 |
14-22 |
Very hard |
220-320 |
13-18 |
22-32 |
Extremely hard |
>320 |
>18 |
>32 |
[0085] A predefined range of the water hardness of the water stream 11, 12 can be one of
or a combination of the above defined ranges. A predefined range of the water hardness
of the water stream 11, 12 therefore may be for example, a range between 0°F and 7°F
and/or 0°dH and 4°dH and/or between 0 and 70 mg/L CaCO
3 (calcium carbonate).
[0086] Hard water can be at least one of more of moderately hard water, hard water, very
hard water and/or extremely hard water. Possible ranges for hard water can between
7°F and more than 32°F, between 4°dH and more than 18°dH and/or between 70 and more
than 320 mg/L CaCO
3, respectively. Possible ranges for moderately hard water are between 4°dH and 8°dH
or between 70 and 140 mg/L CaCO
3, respectively. Possible ranges for hard water can also be between 8°dH and 13°dH
or between 140 and 220 mg/L CaCO
3, respectively. Possible ranges for very hard water are between 13°dH and 18°dH or
between 220 and 320 mg/L CaCO
3, respectively. Possible ranges for extremely hard water are above 18°dH or above
320 mg/L CaCO
3, respectively.
[0087] Soft water is preferably water with a low concentration of mineral content and/or
water after a treatment by the water softening system 20. More preferably, soft water
can be water which contains less than 60 ppm or 3.37 dGH or 3.37 °dH or 33.7 mg/L
CaO. Possible ranges for soft water are between 0°F and 7°F, between 0°dH and 4°dH
and/or between 0 and 70 mg/L CaCO
3, respectively.
[0088] The water softening system 20 comprises means to reduce a first water hardness of
the first water stream 11 at the water inlet 22 to a second water hardness of the
second water stream 12 at the water outlet 23.
[0089] An advantageous way to reduce a first water hardness of the first water stream 11
at the water inlet 22 to a second water hardness of the second water stream 12 at
the water outlet 23 is the use of ion exchange resins, phosphates dispensers and/or
reverse osmosis systems as water-hardness reduction means, preferably contained in
one or more cartridges 24.
[0090] Such cartridges 24 can deal or interact with a total fixed amount of ions, especially
Ca and Mg, corresponding to a total amount of water.
[0091] Dealing or interacting with the water stream, especially with a total fixed amount
of Ca and/or Mg, can especially comprise exchanging the Ions by a ion exchanger. For
example, the Ca-Ions (Ca++; Calcium-Ions) and/or the Mg-Ions (Mg++; Magnesium-Ions)
can be exchanged against Na-Ions (Na+; Natrium-Ions). As an alternative or in addition,
dealing or interacting can comprise dispensing phosphates in a phosphates dispenser
and/or pressing the water through a membrane in a reverse osmosis system.
[0092] Dealing with a total fixed amount of water preferably means that for this fixed amount
of water, the water hardness of the water stream is within the predefined range. The
total amount of water can preferably be variable depending on the hardness of the
water stream from the water supply at the water inlet 22.
[0093] The ion exchange resins can be regenerated, as also used in dishwasher water softneners,
which are regenerated by Natrium Chloride (NaCl) to recover the water softening functionality.
[0094] When the sensor means 80 and/or the estimation unit 31 identifies an expiration of
the softening cartridge 24, a service operation is triggered, which can be either
a regeneration or a replacement of the cartridge 24 or its content. For oven applications,
due to relatively low amount of water needed, the replacement of the cartridge 24
can be privileged, especially when the cartridge 24 is dimensioned in such a way that
the water softening capabilities last for around 2 years or longer.
[0095] FIG 1 further shows sensor means 80 at the water outlet 23 for providing sensor values
of the second water stream 12 to the estimation unit 31, for example by means of a
first transmission line 32 or a radio transmission. As an alternative or in addition,
but not shown, the sensor means 80 can also be arranged partly or entirely at the
water inlet 22 for providing sensor values of the first water stream 11 to the estimation
unit 31.
[0096] The sensor means 80 can comprise at least or more sensors of the following three
classes, which will be described in the following.
[0097] The water softening system 20 can provide a direct measurement, preferably a water
hardness sensor, installed downstream the softening system at the second water stream
12 within the sensor means 80. In addition or as an alternative, the water softening
system 20 can also provide an indirect measurement or determination, for example a
volumetric counter buffering the total amount of water treated by the softening system
20 and provided to the steam generation system 70.
[0098] The sensor means 80 can comprise a first class of sensors. In this case, the sensor
means can perform a direct measurement of the water hardness. Such sensor means can
directly measure the water hardness, preferably at the water outlet 23, immediately
identify when the water softening system 20 ceases or reduces its performance, and
preferably indicate the need for restoration or regeneration. Examples for such sensor
means 80 are conductivity sensor means, optical sensor means or capacitive sensor
means. An advantage of such sensor means 80 is or may be the direct feedback on the
final outflow water hardness at the water outlet 23, regardless of possible contingencies
like, for example, water hardness fluctuations, mechanical failures and/or defective
components of the water softening system 20.
[0099] Furthermore, the sensor means 80 can comprise a second class of sensors. In this
case, the sensor means 80 can perform a total cumulative water amount calculation
of the water stream 11,12, for example by volumetric counters or flow meters. Based
on the second class of sensor means 80, the estimation unit 31 can preferably determine
and/or indicate an expiration of the softening system 20 by assuming the hardness
of the water at the water inlet 22 constant, while the maximum amount of water the
water softening system 20 can treat is predetermined. Even though the second class
of sensors can be blind to contingencies like, for example, water hardness fluctuations,
mechanical failures and/or defective components of the water softening system 20,
the second class of sensors is normally easier to integrate and can be more economical.
[0100] The first and second classes of sensors, for the purpose of the invention, can work
alone, or can be combined as a sensor means 80 to ensure double check of the water
hardness, for example.
[0101] The sensor means 80 can further comprise a third class of sensors. In this case,
the sensor means 80 can measure water spillage and perform leakage detection via threshold
conductivity sensors or floater based sensors. Also this third class of sensors can
work alone as a sensor means 80, or can be also be combined with one or more of the
first and second class to ensure double check of the water hardness, for example.
[0102] The first class of sensors can be put downstream the water softening system 20, for
example at or near the water outlet 23. The first class of sensors can monitor the
supposedly softened water. The second class can be placed before or after the water
softening system 20, for example at or near the water inlet 22 or at or near the water
outlet 23, as the water flow is at least essentially the same.
[0103] FIG 1 also shows the estimation unit 31 which estimates based on the sensor values
whether the water hardness is within a predefined range or below a predefined level.
In addition, the estimation unit 31 can also estimate based on the sensor values whether
the water softening system 20 shall be restored.
[0104] The water management system 1 avoids a descaling operation of the steam generation
system 70 of the steam oven 2. It is possible to integrate the water softening system
20 as a self-diagnosing and regeneration free means into the steam oven 2.
[0105] Therefore, the water management system 1 prevents the need to deal with chemicals
to perform the descaling operation of the steam generation system 70. In addition,
the water management system eliminates downtime of the steam oven 2 due to a descaling
operation, as no descaling operation is necessary.
[0106] The water management system 1 also improves the efficiency of the steam generation
system 70 by eliminating the steady process of limestone accumulation and subsequent
removal.
[0107] The water softening system 20 is in FIG 1 externally to the steam oven 2. Alternatively
and not shown, the water softening system 20 can be also integrated into the steam
oven 2.
[0108] The water softening system 20 is adapted and connected to the water supply 61. The
water supply 61 can be a water tap and/or a fixed or removable drawer and/or a fixed
water connection.
[0109] The water supply 61 for the steam oven 2 can be set up as a fixed water tank which
needs to be filled using an additional water jar. As a first alternative, the water
supply 61 for the steam oven 2 can also be set up as an extractable water tank which
can be extracted from the oven and filled directly on the water tap. As a second alternative,
the water supply 61 for the steam oven 2 can also be set up as a fixed water connection
to the water supply system of the house, for example to a water tap.
[0110] The water management system 1 is dimensioned to keep the second water stream 12 below
a water hardness target for a defined amount of supplied water, in order to cover
a certain and/or predefined steam oven usage time, preferably the whole lifetime of
the oven 2. The water management system 1 can provide long term duration of the steam
generation system 70, preferably life long duration without service.
[0111] The water management system 1 is intended to treat a predefined amount of water in
the first water stream 11, wherein the steam generation system 70 is able to handle
a predefined amount of minerals as residual hardness of the second water stream 12,
so that the oven is able to run a predefined number of steam cycles.
[0112] As a non-limiting example, the water management system can be intended to treat a
predefined amount of 500 1 to 800 1 of water in the first water stream 11. The steam
generation system 70 can be able to handle a predefined amount of approximately 15
g to 21 g of minerals as residual hardness of the second water stream 12. Therefore,
in the example, the steam oven 2 is able to run a predefined number of 400 to 600
steam cycles with a maximum water consumption of each cycle of 11 and applying a safety
factor of 1,5.
[0113] The water management system 1, in an embodiment, is intended to provide the second
water stream 12, preferably softened water, with a water hardness below 3° F or below
7° F and/or corresponding to 3 mg/l or 7 mg/l of CaCO
3 to the steam generation system.
[0114] The water management system 1 is also capable to handle different levels of water
hardness of the first water stream 11. This handling can be performed automatically
or by a calibration process performed during the installation of the steam oven 2.
[0115] The sensor means 80 as part of the water management system 1 comprises or can comprise
a water hardness sensor means and/or a volume counter and/or a flow measurement unit.
The sensor means can be placed in an area where water could flow in case of failures
or uncontrolled water supply.
[0116] The water management system 1 comprises a flood prevention unit 33, especially an
integrated anti-flooding system. The flood prevention unit is intended to stop the
first water steam 11 after a continuous flow of a determined amount of litres of water.
The flood prevention unit 33 controls a valve 60 for blocking the water supply 61
by means of a second transmission line 34 or a radio transmission.
[0117] The flood prevention unit 33 is connected to the sensor means 80. The sensor means
can comprise a water detection means and/or a volume counter, so that the valve 60
can be closed upon water detection and/or uncontrolled water supply.
[0118] Upon reach of a predefined overall amount of water, the water softening system 20
can be restored. The water softening system 20 can be restored by changing or renewing
the disposable cartridge 24 containing the softening material, especially the softening
active matter. Restoring can be performed by changing the disposable cartridge 24
which contains the softening active matter.
[0119] The water softening system 20 can provide an indication to the user that the softening
system 20 must be restored and/or to prevent the steam oven to generate steam until
the softening function has been restored, to avoid processing water with excess of
hardness and resulting limestone layer creation. Examples of such an indication to
the user are an optical and/or acoustical signalling.
[0120] The water softening system 20 is providing an estimation unit 31 to detect and to
preferably communicate to the user when the softening effectiveness is over or falls
below a predefined level.
[0121] The estimation unit 31 estimates when the target or predefined overall amount of
water of the water softening system 20 has been reached, to avoid a supply of water
exceeding a water hardness threshold to the steam generation system 70.
[0122] The water softening system 20 can also comprise a sanitizing unit 21, which can be
integrated into the water softening system 20. The sanitizing unit 21 comprises means
to prevent microbial proliferation over the life span of the system and antimicrobial
additives in the materials constituting the components in contact with the water and/or
sanitizing agent dispensers.
[0123] The features of the present invention disclosed in the description, the claims, and/or
the figure may both separately and in any combination thereof be material for realizing
the invention in various forms thereof.
List of reference numerals
[0124]
- 1
- water management system
- 2
- steam oven
- 11
- first water stream
- 12
- second water stream
- 20
- water softening system
- 21
- sanitizing unit
- 22
- water inlet
- 23
- water outlet
- 24
- cartridge
- 30
- oven control unit
- 31
- estimation unit
- 32
- first transmission line
- 33
- flood prevention unit
- 34
- second transmission line
- 42
- convection heating unit
- 44
- convection fan
- 45
- handle or grip
- 46
- oven door
- 47
- lower heating unit
- 48
- air baffle
- 50
- fan
- 51
- operating panel
- 52
- output channel
- 53
- suction hole
- 60
- valve
- 61
- water supply
- 70
- steam generation system
- 71
- pipe
- 80
- sensor means
- 90
- oven cavity
- 91
- housing
- 92
- items to be cooked
- 93
- baking tray
1. Water management system (1) for a steam oven (2), comprising
- a water softening system (20) comprising a water inlet (22) and a water outlet (23),
- wherein the water inlet (22) is connected to a water supply (61),
- wherein the water outlet (23) is connected to a steam generation system (70) of
the steam oven (2),
- wherein the water softening system (20) comprises water-hardness reduction means
(24) to reduce a water hardness of a water stream (11, 12),
- further comprising sensor means (80) for providing sensor values of the water stream
(11, 12) to an estimation unit (31) and
- further comprising an estimation unit (31) to estimate based on the sensor values
whether the water hardness of the water stream (11, 12) is within a predefined range.
2. Water management system (1) according to claim 1,
- wherein a first water stream (11), especially hard water or inlet water, from the
water supply (61) can flow through the water inlet (22) and a second water stream
(12), especially soft or softened water, for the steam generation system (70) can
flow through the water outlet (23) and/or
- wherein the estimation unit (31) is configured to estimate based on the sensor values
whether the water hardness of the water stream (12), especially of the second water
stream (12), is within a predefined range and/or whether the water softening system
(20) shall be restored and/or
- wherein hard water is preferably at least one of more of moderately hard water,
hard water, very hard water and/or extremely hard water, wherein a predefined range
of the water hardness, especially for hard water, is or can be between 7°F and more
than 32°F, between 4°dH and more than 18°dH and/or between 70 and more than 320 mg/L
CaCO3, respectively and/or
- wherein soft water or softened water is preferably water with a low concentration
of mineral content and/or water after a treatment by the water softening system (20),
wherein more preferably, soft water is or can be water which contains less than 60
ppm or 3.37 dGH or 3.37 °dH or 33.7 mg/L CaO, wherein a predefined range is or can
be, especially for soft water, between 0°F and 7°F, between 0°dH and 4°dH and/or between
0 and 70 mg/L CaCO3, respectively.
3. Water management system (1) according to claim 1 or 2,
- wherein the water softening system (20) comprises water-hardness reduction means
(24) to reduce a first water hardness of the first water stream (11) at the water
inlet (22) to a second water hardness of the second water stream (12) at the water
outlet (23) and/or
- wherein the water-hardness reduction means (24) comprise or use at least one of
ion exchange resins, phosphates dispensers and reverse osmosis systems, preferably
contained in at least one cartridge and/or
- wherein the water-hardness reduction means (24) and/or the at least one cartridge
can deal or interact with, especially absorb and/or exchange, a total fixed amount
of ions, especially Ca and/or Mg, corresponding to a total or predetermined amount
of water.
4. Water management system (1) according to claim 1, wherein the water management system
a) avoids a descaling operation of the steam generation system (70) and/or integrates
the water softening system (20) as a self-diagnosing and regeneration free means into
the steam oven (2) and/or
b) prevents the need to deal with chemicals to perform a descaling operation of the
steam generation system (70) and/or
c) eliminates downtime of the steam oven (2) due to a descaling operation and/or
d) improves the efficiency of the steam generation system (70) by eliminating the
steady process of limestone accumulation and subsequent removal.
5. Water management system (1) according to claim 1 or 2,
wherein
a) the water softening system (20) is integrated into the steam oven (2) or externally
to the steam oven (2) and/or
b) the water softening system (20) is adapted and/or connected to the water supply
(61) and/or
c) the water supply (61) is a water tap and/or a water pipe and/or a fixed water connection
and/or a water tank and/or a fixed or removable drawer, wherein the water supply (61)
is preferably
c1) a fixed water tank within the steam oven (2) which needs to be filled using an
additional water jar and/or
c2) an extractable water tank which can be extracted from the steam oven (2) and filled
directly on a water tap and/or
c3) a fixed water connection to the water supply system of the house, for example
to a water tap.
6. Water management system (1) according to one of the preceding claims, wherein the
water management system is
a) dimensioned to keep the, especially second, water stream (12) below a water hardness
target for a defined amount of supplied water, in order to cover a predefined steam
oven usage time, preferably the whole lifetime of the steam oven (2), and/or
b) providing long term duration of the steam oven, preferably life long duration without
service and/or
c) intended to treat a predefined amount, preferably 500 1 to 800 1, of water in the
water stream (11), wherein the steam generation system (70) is able to handle a predefined
amount of minerals, preferably approximately 15 g to 21 g, as residual hardness of
the, especially second, water stream (12), so that the steam oven is able to run a
predefined number, preferably 400 to 600, of steam cycles, preferably with a maximum
water consumption of each cycle of 11 and/or applying a safety factor of 1 to 1,5,
and/or
c) intended to provide the, especially second, water stream (12), preferably softened
water, within a predefined range of water hardness or with a predefined water hardness,
preferably below 3° F or 7° F or between 0°F and 7°F and/or corresponding to 3 mg/l
or 7 mg/l of CaCO3 to the steam generation system (70) and/or
d) capable to handle different levels of water hardness of the, especially first,
water stream (11), preferably automatically or by a calibration process performed
during the installation of the steam oven (2).
7. Water management system (1) according to one of the preceding claims,
- wherein the sensor means (80) are at the water outlet (23) and/or at the water inlet
(22) for providing sensor values of the, especially first, water stream (11) and/or
of the, especially second, water stream (12) to an estimation unit (31) and/or
- wherein the sensor means (80) comprises a water hardness sensor means and/or a volume
counter and/or a flow measurement unit, wherein the sensor means is preferably placed
in an area where water could flow in case of failures or uncontrolled water supply
and/or
- wherein the sensor means (80) preferably comprises a first class of sensor means,
wherein the sensor means is preferably configured to perform a direct measurement
of the water hardness, more preferably conductivity sensor means, optical sensor means
and/or capacitive sensor means and/or
- wherein the sensor means (80) preferably comprises a second class of sensor means,
wherein the sensor means is preferably configured to perform a total cumulative water
amount calculation of the water stream, for example by volumetric counters or flow
meters and/or
- wherein the sensor means (80) preferably comprises a third class of sensor means,
wherein the sensor means is preferably configured to measure water spillage and/or
perform leakage detection, especially via threshold conductivity sensors or floater
based sensors.
8. Water management system (1) according to one of the preceding claims, wherein the
water management system comprises a flood prevention unit (33), especially an integrated
anti-flooding system, wherein preferably the flood prevention unit
a) is intended to stop the, especially first, water steam (11) after a continuous
flow of a determined amount of litres of water and/or
b) controls a valve (60) for blocking the water supply (61) and/or
c) is connected to the sensor means (80), wherein the sensor means especially comprises
a water detection means and/or a volume counter, so that the valve can be closed upon
water detection and/or uncontrolled water supply.
9. Water management system (1) according to one of the preceding claims, wherein the
water softening system
a) upon reach of a predefined overall amount of water and/or upon exceeding a predefined
threshold for the water hardness can be restored, preferably by changing a disposable
cartridge (24) containing softening material, especially softening active matter,
and/or
b) is intended to provide an indication to the user that the softening system (20)
must be restored and/or to prevent the steam generation system to generate steam until
the softening function has been restored, to avoid processing water with an excess
of hardness and resulting limestone layer creation.
10. Water management system (1) according to one of the preceding claims, wherein the
estimation unit (31)
a) detects and preferably communicates to the user when the softening effectiveness
of the water softening system is over or falls below a predefined level and/or
b) estimates when the target or predefined overall amount of water for the water softening
system has been reached, to avoid a supply of water exceeding a water hardness threshold
to the steam generation system (70).
11. Water management system (1) according to one of the preceding claims, wherein the
softening system provides
a) a direct measurement of the water hardness, preferably a water hardness sensor,
installed downstream the water softening system (20) and/or
b) an indirect measurement or determination of the water hardness, preferably a volumetric
counter buffering the total amount of water treated by the water softening system
(20) and provided to the steam generation system (70).
12. Water management system (1) according to one of the preceding claims, wherein the
water softening system comprises an especially integrated sanitizing unit (21), wherein
preferably the sanitizing unit comprises
a) means to prevent microbial proliferation over the life span of the steam oven and/or
b) antimicrobial additives in the materials constituting the components in contact
with the water and/or
c) sanitizing agent dispensers.
13. Steam oven with a water management system according to one of the preceding claims,
wherein preferably
a) the steam oven is a solo steam appliance, wherein only pure steam cooking functions
are available, as no heating systems beside the steam generation system are available
or
b) wherein the steam oven is a combi steam appliance, wherein steam can be used alone
for cooking, or combined with other heating systems, to merge the heating effect of
steam with other heating systems, especially with hot air and/or upper heat and/or
lower heat.
14. Steam oven (2) according to claim 13, wherein the steam oven is an electric domestic
oven comprising one or more of the following: a housing (91), an oven cavity (90),
an oven door (46) with a handle or grip (45), a convection heating unit (42) in combination
with a convection fan (44) and/or an air baffle (48), an upper heating unit, a lower
heating unit (47), a fan (50) for sucking air out of the cavity (90) through a suction
hole (53), a steam generation system (70) with a pipe (71) to submit steam into the
oven cavity (90), an oven control unit (30) with the estimation unit (31) and a flood
prevention unit (33), an operating panel (51) for operating the oven as well as items
to be cooked (92) arranged on a baking tray (93).
15. Method for operating a water management system and/or a steam oven, especially according
to one of the preceding claims, comprising
- a water softening system (20) comprising a water inlet (22) and a water outlet (23),
- wherein the water inlet (22) is connected or connectable to a water supply (61),
- wherein the water outlet (23) is connected or connectable to a steam generation
system (70) of the steam oven (2), wherein the method comprises the following steps:
- reducing, by means of the water softening system (20), a water hardness of the water
stream (11, 12),
- providing, by sensor means (80), sensor values of the water stream (11, 12) to an
estimation unit (31) and
- estimating, by means of the estimation unit (31), based on the sensor values whether
the water hardness is within a predefined range.
16. Method for operating a water management system and/or a steam oven according to claim
15,
- wherein a first water stream (11), especially hard water or inlet water, can flow
from the water supply (61) through the water inlet (22) and a second water stream
(12), especially softened water, for the steam generation system (70) can flow through
the water outlet (23) and/or
- wherein the method further comprises the following step: reducing, by means of the
water softening system (20), a first water hardness of the first water stream (11)
at the water inlet (22) to a second water hardness of the second water stream (12)
at the water outlet (23).
17. Method for operating a water management system and/or a steam oven according to claim
15 or 16, wherein the method further comprises the following step or steps:
- providing, by sensor means (80) at the water outlet (23) and/or at the water inlet
(22), sensor values of the first water stream (11) and/or of the second water stream
(12) to an estimation unit (31) and
- estimating by means of the estimation unit (31), based on the sensor values whether
the water hardness is within a predefined range and/or whether the water softening
system (20) shall be restored.