U.S. patent application number 12/331188 was filed with the patent office on 2009-09-24 for method for controlling dishwasher.
This patent application is currently assigned to LG Electronics Inc.. Invention is credited to Min Chul Kim.
Application Number | 20090235957 12/331188 |
Document ID | / |
Family ID | 40211102 |
Filed Date | 2009-09-24 |
United States Patent
Application |
20090235957 |
Kind Code |
A1 |
Kim; Min Chul |
September 24, 2009 |
Method for controlling dishwasher
Abstract
A method for controlling a dishwasher is disclosed. The control
method basically includes a preliminary washing operation for
spraying wash water required to hydrate waste adhered to dishes, a
main washing operation implemented plural times for washing the
dishes contaminated by the waste, a rinsing operation implemented
after the preliminary washing operation and also, after the main
washing operation for rinsing the dishes from which the waste is
removed, and a drying operation for drying the dishes after
completion of the washing and rinsing operations. The control
method further comprises a steam supply operation implemented at
least once before, after, or during the main washing operation for
supplying steam to the dishes. With the control method, steam is
supplied to a tub in which dishes are received, to enable not only
easy removal of food waste adhered to the dishes, but also
sterilization of the dishes and tub. The supply of steam is
accomplished without requiring an additional steam supply heater,
water supply device and nozzle, resulting in easy fabrication and
reduced costs.
Inventors: |
Kim; Min Chul; (Changwon-Si,
KR) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
LG Electronics Inc.
Seoul
KR
|
Family ID: |
40211102 |
Appl. No.: |
12/331188 |
Filed: |
December 9, 2008 |
Current U.S.
Class: |
134/25.2 |
Current CPC
Class: |
A47L 15/0007 20130101;
A47L 2501/14 20130101; A47L 15/4234 20130101; A47L 2401/09
20130101; A47L 2601/04 20130101; A47L 15/0015 20130101; A47L
15/4236 20130101 |
Class at
Publication: |
134/25.2 |
International
Class: |
A47L 15/46 20060101
A47L015/46 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 10, 2007 |
KR |
10-2007-0127524 |
Claims
1. A method for controlling a dishwasher comprising: a preliminary
washing operation for spraying wash water required to hydrate waste
adhered to dishes; a main washing operation implemented plural
times for washing the dishes contaminated by the waste; a rinsing
operation implemented after the preliminary washing operation and
also, after the main washing operation for rinsing the dishes from
which the waste is removed; and a drying operation for drying the
dishes after completion of the washing and rinsing operations,
wherein the method further comprises a steam supply operation
implemented at least once before, after, or during the main washing
operation for supplying steam to the dishes.
2. The method according to claim 1, wherein the steam supply
operation is implemented to supply steam via operation of a heater
having an adjustable heating capacity depending on the amount of
wash water.
3. The method according to claim 2, wherein a hot-water supply
operation for heating and supplying wash water is selectively
implemented during the main washing operation upon stoppage of
steam supply.
4. The method according to claim 3, wherein a heating value of the
heater in the steam supply operation is controlled to be higher
than a heating value of the heater in the hot-water supply
operation.
5. The method according to claim 4, wherein a level of wash water
in the steam supply operation is controlled to be lower than a
level of wash water in the main washing operation.
6. The method according to claim 5, wherein a lowest level of wash
water in the steam supply operation is controlled to be higher than
an installation position of the heater.
7. The method according to claim 1, wherein the steam supply
operation is implemented to supply steam by adjusting the amount of
wash water when a heater having a constant heating value is
used.
8. The method according to claim 7, wherein a hot-water supply
operation for heating and supplying wash water is selectively
implemented during the main washing operation upon stoppage of
steam supply.
9. The method according to claim 8, wherein a level of wash water
in the steam supply operation is controlled to be lower than a
level of wash water in the hot-water supply operation.
10. The method according to claim 9, wherein a lowest level of wash
water in the steam supply operation is controlled to be higher than
an installation position of the heater.
11. The method according to claim 1, wherein the steam supply
operation is controlled to discharge water residue and supply new
water, prior to implementing the steam supply operation.
Description
[0001] This application claims the benefit of the Korean Patent
Application No. 10-2007-0127524, filed on Dec. 10 2007, which is
hereby incorporated by reference as if fully set forth herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method for controlling a
dishwasher, and more particularly, to a control method of a
dishwasher, which can achieve an improvement in washing performance
via supply of steam.
[0004] 2. Discussion of the Related Art
[0005] Generally, a dishwasher is an apparatus in which
high-pressure wash washer is sprayed to dishes received in the
dishwasher, so as to wash the dishes contaminated by, for example,
food waste attached to surfaces of the dishes.
[0006] Such a dishwasher includes a water supply device to which
wash water from an external source is supplied, and a drain device
from which the used wash water is discharged to the outside. The
dishwasher contains a tub defining a space in which dishes are
received and washed. The tub is provided with spray nozzles capable
of spraying wash water at a high pressure.
[0007] To collect the sprayed wash water, a sump is provided
underneath the tub. The sump contains elements to filter and crush
waste that is mixed with the wash water during washing of dishes.
Then, under operation of a drive unit, the wash water is pumped
upward so as to again be sprayed into the tub via a spray arm. In
this way, the dishes received in the tub are washed via washing
circulation of wash water.
[0008] Recently, a variety of measures have been proposed to
improve washing performance of the above-described dishwasher. In
particular, operations of the dishwasher may be classified into a
preliminary washing operation and a main washing operation. In the
preliminary washing operation, wash water is sprayed to dishes, to
hydrate food waste attached to the dishes for easy washing of the
dishes. The preliminary washing operation is followed by the main
washing operation in which the dishes are washed in earnest.
[0009] To further improve the washing performance of the
dishwasher, detergent is mixed into the wash water, so as to
facilitate effective separation of food waste from the dishes. Some
conventional dishwashers may also have a function to irradiate
ultraviolet light to the washed dishes, for sterilization of the
dishes.
[0010] However, conventional dishwashers have a problem in that,
when used dishes are left for a long time and thus, food waste is
dried and firmly adheres to the dishes, it is difficult to remove
the food waste from the dishes via only spraying of high-pressure
wash water.
[0011] To solve the above-described problem, although one might
consider implementing the above-described preliminary washing
operation having a hydrating function, it has been found that the
preliminary washing operation cannot completely solve the
above-described problem. Furthermore, implementation of the
hydrating function requires a great time and thus,
disadvantageously lengthens the entire washing operation.
[0012] Furthermore, even if the propagation of bacteria occurs as
used dishes are left for a long time, conventional dishwashers have
a difficulty to remove the bacteria. Although some conventional
dishwashers have an ultraviolet sterilizing function, they exert
sterilizing effects only on a local area to which ultraviolet light
is irradiated, and cannot completely solve any problems, such as
the propagation of bacteria, etc.
SUMMARY OF THE INVENTION
[0013] Accordingly, the present invention is directed to a method
for controlling a dishwasher that substantially obviates one or
more problems due to limitations and disadvantages of the related
art.
[0014] Additional advantages, objects, and features of the
invention will be set forth in part in the description which
follows and in part will become apparent to those having ordinary
skill in the art upon examination of the following or may be
learned from practice of the invention. The objectives and other
advantages of the invention may be realized and attained by the
structure particularly pointed out in the written description and
claims hereof as well as the appended drawings.
[0015] To achieve these objects and other advantages and in
accordance with the purpose of the invention, as embodied and
broadly described herein, a method for controlling a dishwasher
comprises: a preliminary washing operation for spraying wash water
required to hydrate waste adhered to dishes; a main washing
operation implemented plural times for washing the dishes
contaminated by the waste; a rinsing operation implemented after
the preliminary washing operation and also, after the main washing
operation for rinsing the dishes from which the waste is removed;
and a drying operation for drying the dishes after completion of
the washing and rinsing operations, wherein the method further
comprises a steam supply operation implemented at least once
before, after, or during the main washing operation for supplying
steam to the dishes.
[0016] The steam supply operation may be implemented to supply
steam via operation of a heater having an adjustable heating
capacity depending on the amount of wash water.
[0017] A hot-water supply operation for heating and supplying wash
water may be selectively implemented during the main washing
operation upon stoppage of steam supply.
[0018] A heating value of the heater in the steam supply operation
may be controlled to be higher than a heating value of the heater
in the hot-water supply operation.
[0019] A level of wash water in the steam supply operation may be
controlled to be lower than a level of wash water in the main
washing operation.
[0020] A lowest level of wash water in the steam supply operation
may be controlled to be higher than an installation position of the
heater.
[0021] The steam supply operation may be implemented to supply
steam by adjusting the amount of wash water when a heater having a
constant heating value is used.
[0022] A hot-water supply operation for heating and supplying wash
water may be selectively implemented during the main washing
operation upon stoppage of steam supply.
[0023] A level of wash water in the steam supply operation may be
controlled to be lower than a level of wash water in the hot-water
supply operation.
[0024] A lowest level of wash water in the steam supply operation
may be controlled to be higher than an installation position of the
heater.
[0025] The steam supply operation may be controlled to discharge
water residue and supply new water, prior to implementing the steam
supply operation.
[0026] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
[0028] FIG. 1 is a schematic view illustrating the configuration of
a dishwasher in accordance with an embodiment of the present
invention;
[0029] FIG. 2 is an exploded perspective view illustrating
components of a drive unit shown in FIG. 1;
[0030] FIG. 3 is a sectional view of the drive unit shown in FIG.
1;
[0031] FIG. 4 is a control block diagram of a control unit; and
[0032] FIG. 5 is a flow chart schematically illustrating a method
for controlling the dishwasher shown in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0033] Reference will now be made in detail to preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. Wherever possible, the
same reference numbers will be used throughout the drawings to
refer to the same or like parts.
[0034] Hereinafter, a preferred first embodiment of the present
invention will be described in detail with reference to the
accompanying drawings.
[0035] FIG. 1 is a schematic view illustrating the configuration of
a dishwasher in accordance with an embodiment of the present
invention.
[0036] As shown in FIG. 1, the dishwasher includes a cabinet 1
defining an external appearance of the dishwasher, a tub 10
defining a space in which dishes are washed, and a drive unit 20 to
pump wash water, used to wash the dishes, into the tub 10.
[0037] The tub 10 is provided therein with at least one rack 11 in
which dishes are received, and at least one spray arm 12 to spray
pumped wash water to the dishes. In this case, the spray arm 12 has
a plurality of spray holes for spraying wash water. Preferably, the
spray arm 12 is rotatably installed at a position corresponding to
the rack 11, to uniformly spray wash water to all the dishes.
[0038] The drive unit 20 is coupled to a water supply device 55,
through which wash water from an external tap water source is
supplied. In addition, a drain device 50 is coupled to a sump 30,
and is used to discharge wash water received in the sump 30.
[0039] The drive unit 20 is installed underneath the tub 10 and is
configured such that wash water, sprayed and dropped from the spray
arm 12, is received in the drive unit 20. Preferably, to pump the
wash water upward from the drive unit 20, a connecting pipe 13 is
further coupled to the drive unit 20 while being connected to the
spray arm 12.
[0040] FIG. 2 is an exploded perspective view illustrating
components of the drive unit shown in FIG. 1, and FIG. 3 is a
sectional view of the drive unit shown in FIG. 1.
[0041] As shown in FIGS. 2 and 3, the drive unit 20 includes the
sump 30 in which wash water is received, the water supply device 50
to supply wash water into the sump 30, the drain device 50 coupled
to the sump 30, from which wash water is drained, a washing pump
received in the sump 30 and used to pump the wash water received in
the sump 30, and a filtering device to filter the pumped wash water
remaining in the sump 30 after guiding some of the pumped wash
water into the spray arm 12.
[0042] The sump 30 defines a space in which wash water is received
and is provided, at a portion thereof, with a drain chamber 32 that
communicates with the drain device 50. Preferably, a flow-path
control device 35 is provided at the exterior of the sump 30 and in
turn, a flow-path control valve 36 is axially coupled to the
flow-path control device 35 via a shaft.
[0043] The water supply device 55 is connected with an external tap
water source and serves to supply wash water into the tub 30.
Preferably, the water supply device 55 is connected to a specific
position of the sump 30. Of course, it will be appreciated that
this installation of the water supply device 55 is provided only by
way of example and wash water may be directly supplied into the tub
10. In the present embodiment, the water supply device 55 consists
of a water supply pipe 56 to supply wash water, and a water supply
valve 57 to selectively open or close the water supply pipe 56.
[0044] The drain device 50 may include a drain pump 53 provided in
the drain chamber 32. The drain pump 53 consists of a drain motor
51 and an impeller 52.
[0045] The washing pump consists of a washing motor 41 provided
underneath the sump 30 and used to generate a drive force, and an
impeller 42 coupled to the filtering device and used to pump wash
water. In addition, a disposer 43 is axially coupled to a shaft of
the washing pump and functions to crush food waste via rotation
thereof. Preferably, a screen 44 having a predetermined mesh size
sufficient to filter a relatively large size of food waste is
disposed above the disposer 43.
[0046] The filtering device includes a pump housing 60 defining a
space for installation of the impeller 42, a filter housing 70
disposed to cover the top of the pump housing 60, and a cover 80
coupled to the top of the filter housing 70 and sump 30.
Preferably, the pump housing 60 is disposed at a lower surface of
the filter housing 70, and the cover 80 is disposed at an upper
surface of the filter housing 70.
[0047] The filter housing 70 may contain, for example, a waste
collecting chamber 71, and the waste collecting chamber 71 may be
coupled to a drain pipe 72 that communicates with the drain chamber
32. For this, preferably, the drain pipe 72 is configured to
protrude downward from the lower surface of the filter housing 70
by a predetermined length.
[0048] The cover 80 is preferably provided with a filter 81 such
that the filter 81 corresponds to the waste collecting chamber 71
of the filter housing 70. More preferably, the cover 80 is provided
with a plurality of recovery holes 82 arranged around the filter
81, and the recovery holes 82 communicate with the sump 30.
[0049] The filter housing 70 is further provided with at least one
main flow-path connected to the spray arm 12, and is also provided
with a sampling flow-path penetrating through the waste collecting
chamber 71. The flow-path control valve 36, which is axially
coupled to the flow-path control device 35, is disposed in the
filter housing 70 and is used to open or close the flow path(s)
inside the filter housing 70.
[0050] Preferably, regardless of any one main flow-path being
opened or closed by the flow-path control valve 36, some wash water
is always introduced into the sampling flow-path. This serves to
assure continuous filtering of wash water containing waste.
[0051] Once the wash water is introduced into the waste collecting
chamber 71 through the sampling flow-path, the wash water flows
through the filter 81 which is located above the waste collecting
chamber 71. Preferably, the filter 81 is used to filter waste
contained in the wash water.
[0052] As the wash water, which is filtered via the above-described
overflow process, as well as the wash water, which is sprayed from
the spray arm 12 to thereby drop into the cover 80, are introduced
into the sump 30 through the recovery holes 82, washing circulation
of wash water is accomplished.
[0053] Hereinafter, a heater 100 provided at the drive unit 20 will
be described in detail with reference to FIGS. 2 and 3.
[0054] In the present embodiment, the heater 100 is preferably
provided, to supply steam into the tub 10.
[0055] Steam is supplied because simply spraying high-pressure wash
water to dishes may often fail to completely remove food waste
adhered to surfaces of the dishes. Although one might consider
providing a washing operation with a function for hydrating food
waste adhered to surfaces of dishes, this still has a difficulty to
completely remove dried food waste firmly adhered to dishes.
Therefore, there is a risk of requiring an excessively long time to
sufficiently hydrate food waste adhered to surfaces of dishes.
[0056] As will be appreciated, since steam has a considerably
higher temperature than wash water and is able to be easily
adsorbed into food waste adhered to dishes, the use of steam can
accomplish sufficient hydration of food waste within a short time.
Accordingly, when steam is supplied into the tub 10 as proposed in
the present embodiment, food waste adhered to dishes may be easily
removed by wash water, resulting in a remarkable improvement in
washing performance of dishes.
[0057] Steam further has sterilizing effects since steam is a gas
having a high-temperature of up to 100.degree. C. and thus,
provides the same effect as boiling of dishes. As compared to a
conventional sterilizing device using ultraviolet light that is
very expensive and exerts sterilizing effects only a local area to
which ultraviolet light is irradiated, according to the present
embodiment, steam is supplied to the entire inner surface of the
tub 10 and surfaces of dishes, enabling sterilization of the entire
dishwasher at low cost.
[0058] Preferably, steam is supplied before or after a main washing
operation. This is advantageous to hydrate food waste adhered to
dishes before the main washing operation, or to finally sterilize
the dishes and tub after completion of the main washing operation.
Of course, it will be appreciated that this supply of steam is
given only by way of example and in the case where the main washing
operation is implemented several times, steam may be supplied
between the repeatedly implemented main washing operations, or may
be supplied during the main washing operation.
[0059] Preferably, the heater 100 is installed to heat wash water
received in the sump 30 for supply of steam. Of course, one might
consider generating steam using water additionally supplied from
the water supply device 55, rather than using the wash water
received in the sump 30. However, when generating steam using the
additionally supplied water, for example, a flow-path and valve
connected to the water supply device 55, a steam generator in which
a receiving space for storing and heating water is defined, and a
nozzle to supply steam into the tub are additionally required,
entailing a risk of causing complexity in configuration.
[0060] Therefore, in the present embodiment, the heater 100 is
installed in a bottom region of the sump 30 and is used to heat the
wash water received in the sump 30 so as to generate steam. In this
case, the steam is supplied into the tub 10 through a water
collecting path, through which the wash water used to wash the
dishes is collected.
[0061] Specifically, the wash water, sprayed into the tub 10, drops
downward, thereby being collected in the sump 30. For this, most
dishwashers have a water collecting path, which is connected to the
top of the sump 30 while communicating with the tub 10 (here, the
water collecting path is not an additional line, but a movement
path along which the wash water drops). Steam rises because it is
less dense than air and therefore, tends to be supplied into the
tub 10 through the water collecting path. Accordingly, in the
present embodiment, steam is supplied into the tub 10 through, for
example, the recovery holes 82 perforated in the cover 80.
[0062] Supplying steam through the recovery holes 82 of the cover
80 eliminates a need for an additional nozzle used to supply steam.
When using the steam supply nozzle, there is a risk of steam being
condensed at a surface of the nozzle. As compared to the use of the
steam supply nozzle, the present embodiment can minimize
condensation of steam during a steam supply operation, allowing a
greater amount of steam to be supplied into the tub 10.
[0063] Some of the steam generated by the heater 100 may be
supplied by use of a path, through which wash water is supplied
from the sump 30 into the tub 10. Specifically, steam generated in
the sump 30 has characteristics of diffusion and therefore, may be
introduced into the filter housing 70 through an opening perforated
in the bottom of the pump housing 60. Thereafter, the steam may be
supplied into the tub 10 via operation of the spray arm 12 after
having passed through the main flow-path of the filter housing 70.
This has an advantage of sterilizing a flow path, along which the
wash water is pumped from the sump 30 into the tub 10.
[0064] Meanwhile, during washing circulation of the wash water used
to wash the dishes, the heater 100 may heat the wash water to a
high temperature sufficient to enable washing of dishes using
high-temperature wash water. The higher the temperature of wash
water, the easier it is to hydrate and remove food waste adhered to
dishes and a further improved washing performance of the dishwasher
can be accomplished upon washing circulation of the
high-temperature wash water.
[0065] For this reason, in the present embodiment, the heater 100
heats the wash water received in the sump 30 according to operating
modes of the dishwasher, so as to supply steam into the tub 10, or
to supply high-temperature wash water during the main washing
operation.
[0066] For example, the heater 100 may heat wash water to more than
100.degree. C., so as to generate steam. Otherwise, during the main
washing operation, the heater 100 may heat wash water to less than
100.degree. C., so as to generate high-temperature wash water.
[0067] In this case, to adjust the temperature of wash water heated
by the heater 100, a variety of methods may be adopted.
[0068] As the background of the above steam generation, the heater
100 may be a variable heater in which heating capacity is
adjustable to adjust the temperature of wash water. In this case,
when it is desired to supply steam into the tub 10, it is
preferable that the heater 100 heat wash water with an increased
heating value sufficient to generate steam.
[0069] In addition, during washing circulation of wash water, it is
preferable that the heater 100 heat wash water with a lower heating
value than that required for the supply of steam, so as to supply a
predetermined temperature of hot water.
[0070] If the heater 100 has no function of adjusting a heating
value thereof, the temperature of wash water may be adjusted by
adjusting the amount of wash water heated by the heater 100. This
is because, assuming that the heater has a constant heating value,
the smaller the amount of wash water, the higher the temperature of
wash water.
[0071] Accordingly, it is preferable that the amount of wash water
during the supply of steam be kept at a lower value than the amount
of wash water during washing circulation, to allow the wash water
to be heated to a high temperature sufficient to generate
steam.
[0072] In the present embodiment, in addition to the heater 100 in
which heating capacity is adjustable according to an operating mode
of the dishwasher, a control unit 110 is preferably provided, to
adjust the amount of wash water received in the sump 30.
[0073] As described above, it is preferable that the heater 100
heat the wash water during the supply of steam with a higher
heating value than a heating value required during washing
circulation of wash water.
[0074] In addition, the control unit 110 may control the amount of
wash water such that a water level during the supply of steam is
higher than a water level during washing circulation of wash water.
This is because a steam generating time can be reduced according to
the amount of wash water even though the heater 100 having an
adjustable heating value is used.
[0075] FIG. 4 is a control block diagram of the control unit.
[0076] As shown in FIG. 4, in the present embodiment, the water
supply device 55 and drain device 50 are preferably controlled,
respectively, by the control unit 110. Accordingly, the control
unit 110 is able to control the water supply device 55 so as to
effectively supply wash water, or to control the drain device 50 so
as to adjust the amount of wash water to be received in the sump
30.
[0077] In the present embodiment, a sensor unit 120 may be further
provided, to measure a level of wash water received in the sump 30.
In this case, preferably, the control unit 110 acts to adjust the
amount of wash water received in the sump 30 in response to a
signal corresponding to a sensed level of wash water from the
sensor unit 120. The sensor unit 120 may consist of a high water
level sensor 121 and a low water level sensor 122 (these sensors
will be described hereinafter).
[0078] For example, if the sensor unit 120 senses, during an
operation for washing dishes using wash water, that a level of wash
water is lowered, thus making it impossible for the drive unit 20
to pump the wash water, the control unit 110 controls the water
supply device 55, so as to command supply of wash water.
[0079] Otherwise, if the sensor unit 110 senses, during an
operation for supplying steam, that the amount of wash water is
excessively increased to make it difficult to generate steam with a
heating value of the heater 100, the control unit 110 controls the
drain device 50, so as to command discharge of a predetermined
amount of wash water.
[0080] The sensor 120 may include the high water level sensor 121,
to maintain an appropriate amount of wash water during generation
of steam. Here, the high water level sensor 121 is preferably
installed at a height corresponding to a position of the bottom
opening of the pump housing 60.
[0081] Preferably, the control unit 110 maintains a higher level of
wash water received in the sump 30 than an installation position of
the heater 100 during operation of the heater 100.
[0082] Generally, the heater 100 used in the dishwasher is adapted
to heat wash water by transmitting heat, generated by a heating
element inside the heater 100, to wash water in contact with an
outer surface of the heater 100. Therefore, when a level of wash
water is not maintained to be higher than the installation position
of the heater 100, there is a risk of damage to the surface of the
heater 100 due to overheating. In addition, this may cause
remarkable deterioration in heating efficiency of the heater
100.
[0083] For this reason, in the present embodiment as shown in the
drawing, the heater 100 is disposed in the bottom region of the
sump 30 and under control operation of the control unit 110, a
level of wash water is always maintained to be higher than the
installation position of the heater 100. In this case, the control
unit 110 may sense a level of wash water using the sensor unit 120.
In addition, the sensor unit 120 may further include the low water
level sensor 122 provided at the installation position of the
heater 100 to sense a lowest level of wash water.
[0084] The control unit 110 is able to control the supply of wash
water in such a manner that the wash water remaining in the sump 30
is discharged and new wash water is supplied, prior to generating
steam via heating operation of the heater 100.
[0085] In the case where the wash water contains waste separated
from dishes during washing, heating the wash water containing waste
entails a risk of generating serious foul odors. In particular, if
the resulting steam is supplied for sterilization of dishes in a
final step, such foul odors may cause a user discomfort.
[0086] Therefore, in the present embodiment, the control unit 110
preferably controls the water supply device 55 and drain device 50,
to selectively discharge the wash water remaining in the sump 30
and supply steam using newly supplied wash water, prior to
generating steam.
[0087] FIG. 5 is a flow chart schematically illustrating a method
for controlling the dishwasher shown in FIG. 1.
[0088] Hereinafter, a preferred control method of the dishwasher in
accordance with the present invention will be described with
reference to FIG. 5.
[0089] The dishwasher may be controlled such that washing of dishes
is implemented using high-temperature wash water heated by the
heater 100. In addition, the dishwasher may be controlled to supply
steam into the tub 10 via heating of wash water. That is, the
dishwasher may be controlled to supply high-temperature wash
water., or to supply steam into the tub 10 at a predetermined time
when no washing of dishes is implemented, under operation of the
single heater 100.
[0090] As shown in FIG. 5, the dishwasher according to the present
embodiment is basically controlled by the control unit 110 to
implement a preliminary washing operation, a main washing
operation, a rinsing operation, and a drying operation in this
sequence. Additionally, before, after, or during the main washing
operation, a steam supply operation is implemented at least
once.
[0091] During the main washing operation, a hot-water supply
operation for heating and supplying wash water may be selectively
implemented when it is unnecessary to supply steam. Advantageously,
prior to implementing the steam supply operation, the wash water
remaining in the sump 30 is discharged and new wash water is
supplied into the sump 30.
[0092] The preliminary washing operation serves to preliminarily
spray wash water to dishes, so as to hydrate, for example, food
waste adhered to the dishes. The preliminary washing operation is
followed by the rinsing operation and main washing operation in
sequence.
[0093] The main washing operation is controlled in such a manner
that wash water is sprayed plural times to wash the dishes and is
followed by the rinsing operation. The washing and rinsing
operations are selectively repeated,
[0094] The steam supply operation may be selectively implemented at
least once before or during the main washing operation under
control operation of the control unit 110.
[0095] In the steam supply operation, preferably, the amount of
wash water received in the sump 30 is adjusted before the wash
water is heated by the heater 100 so as to generate steam. In this
case, more preferably, a level of wash water received in the sump
30 during the steam supply operation is maintained to be lower than
a level of wash water received in the sump 30 during the main
washing operation or the hot-water supply operation.
[0096] The above washing operation requires more than a
predetermined level of wash water required to pump the wash water
using the drive unit 20. Furthermore, in view of an improvement in
washing efficiency, it is necessary to maintain more than a
predetermined amount of wash water.
[0097] On the other hand, the steam supply operation has no need to
pump the wash water using the drive unit 20. This is because,
assuming the heater 100 having a constant heating value, the
smaller the amount of wash water, it is easier to generate steam
via heating of the wash water.
[0098] Of course, under the assumption that the heater 100 is a
variable heater in which heating capacity is adjustable, the steam
supply operation may be controlled to generate steam with an
increased heating value of the heater 100.
[0099] That is, a heating value of the heater 100 in the steam
supply operation is preferably higher than a heating value in the
hot-water supply operation. In this case, note that heating a
reduced amount of wash water is advantageous in view of a reduction
in steam generating time.
[0100] Accordingly, in the use of a variable heater, a level of
wash water received in the sump 30 during the steam supply
operation is preferably maintained to be lower than a level of wash
water during the hot-water supply operation.
[0101] That is, regardless of whether the heater 100 has a constant
heating value or a variable heating value, it is preferable that a
level of wash water received in the sump 30 be maintained at a
lowest level for the purpose of an improvement in steam generation
efficiency.
[0102] In the steam supply operation, after the amount of wash
water is adjusted, the wash water is heated by the heater 100 until
the wash water reaches a boiling point thereof, so as to generate
and supply steam into the tub 10. In this case, the supply of steam
is continued for a predetermined time, so as to hydrate waste
adhered to dishes for easy removal of the waste, or to sterilize
the tub 10 and dishes.
[0103] Preferably, during implementation of the steam supply
operation, a level of wash water is maintained to be higher than
the installation position of the heater 100, under control
operation.
[0104] In the case where a steam supply time is excessively long,
the wash water received in the sump 30 may evaporate, lowering a
level of wash water to a level close to the bottom of the heater
100. This may damage the surface of the heater 100 due to
overheating and also, may cause remarkable deterioration in the
heating efficiency of the heater 100. For this reason, during
implementation of the steam supply operation, it is preferable to
sense a level of wash water received in the sump 30, so as to keep
the level of wash water above the installation position of the
heater 100.
[0105] In the present embodiment, preferably, a lowest level of
wash water is set to be slightly higher than the installation
position of the heater 100. When the level of wash water received
in the sump 30 reaches the lowest level in the steam supply
operation, the steam supply operation can be controlled such that a
predetermined amount of wash water is newly supplied into the sump
30.
[0106] In this case, the newly supplied amount of wash water is
preferably set in consideration of the capacity and heating
efficiency of the heater 100. Note that a level of wash water
received in the sump 30 during the steam supply operation is
preferably maintained to be lower than a level of wash water during
the main washing operation. This is to assure effective generation
of steam as described above.
[0107] In the case where the steam supply operation is followed by
the main washing operation, it is preferable to additionally supply
wash water prior to pumping the wash water received in the sump 30
for washing circulation of wash water. This serves to supplement
wash water as much as a reduced amount of wash water received in
the sump 30 during the steam supply operation, for the purpose of
effective washing circulation of wash water.
[0108] In the case where the main washing operation is followed by
the steam supply operation, it is preferable to implement an
operation for discharging the wash water remaining in the sump 30
prior to implementing the steam supply operation.
[0109] This is because the wash water may contain waste separated
from the dishes at the end of the main washing operation. Heating
the wash water containing waste to generate steam may have a risk
of causing, for example, serious foul odors.
[0110] Accordingly, when the steam supply operation is finally
implemented for the purpose of sterilization, etc., it is
preferable to discharge the wash water remaining in the sump 30 and
supply new wash water, prior to implementing the steam supply
operation.
[0111] In addition, even in the case where the steam supply
operation is implemented during the main washing operation, it is
preferable to discharge the wash water remaining in the sump 30 and
supply new wash water, prior to implementing the steam supply
operation.
[0112] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the inventions. Thus,
it is intended that the present invention covers the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
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