U.S. patent application number 14/479538 was filed with the patent office on 2015-03-26 for dishwasher with treatment-fluid generator, and method of operating such a dishwasher.
This patent application is currently assigned to ILLINOIS TOOL WORKS INC.. The applicant listed for this patent is Harald Disch, Klaus Padtberg. Invention is credited to Harald Disch, Klaus Padtberg.
Application Number | 20150083163 14/479538 |
Document ID | / |
Family ID | 52623572 |
Filed Date | 2015-03-26 |
United States Patent
Application |
20150083163 |
Kind Code |
A1 |
Padtberg; Klaus ; et
al. |
March 26, 2015 |
DISHWASHER WITH TREATMENT-FLUID GENERATOR, AND METHOD OF OPERATING
SUCH A DISHWASHER
Abstract
A dishwasher for crockery or utensils, which is designed as a
box-type dishwasher or as a conveyor dishwasher, wherein the
dishwasher (1) has at least one wash tank (12), for accommodating a
treatment fluid (20), and at least one final-rinse system, for
supplying a final-rinse fluid (42). In order for it to be possible
for expensive wash chemicals to be dispensed with for the most
part, the dishwasher (1) also has a treatment-fluid generator (100)
with at least one electrolysis device (109), wherein the
treatment-fluid generator (100) is, or can be, connected to the
wash tank (12) and is designed to supply an alkaline solution in
the wash tank (12) of the dishwasher (1) by electrolysis.
Inventors: |
Padtberg; Klaus; (Korbach,
DE) ; Disch; Harald; (Elzach, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Padtberg; Klaus
Disch; Harald |
Korbach
Elzach |
|
DE
DE |
|
|
Assignee: |
ILLINOIS TOOL WORKS INC.
Glenview
IL
|
Family ID: |
52623572 |
Appl. No.: |
14/479538 |
Filed: |
September 8, 2014 |
Current U.S.
Class: |
134/18 ; 134/56D;
134/95.1; 134/95.3 |
Current CPC
Class: |
A47L 2501/05 20130101;
A47L 15/0015 20130101; A47L 15/0018 20130101; A47L 15/4238
20130101; A47L 2401/03 20130101; A47L 2601/06 20130101; A47L
15/0078 20130101; A47L 2401/12 20130101; A47L 2501/16 20130101;
A47L 15/0057 20130101; A47L 2401/11 20130101 |
Class at
Publication: |
134/18 ;
134/95.1; 134/56.D; 134/95.3 |
International
Class: |
A47L 15/42 20060101
A47L015/42; A47L 15/00 20060101 A47L015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 24, 2013 |
DE |
10 2013 219 204.5 |
Claims
1. A dishwasher (1), which is designed as a box-type dishwasher or
as a conveyor dishwasher, wherein the dishwasher (1) has at least
one wash tank (12), for accommodating a treatment fluid (20), and
at least one final-rinse system, for supplying a final-rinse fluid
(42), characterized in that the dishwasher (1) also has a
treatment-fluid generator (100) with at least one electrolysis
device (109), wherein the treatment-fluid generator (100) is, or
can be, connected to the wash tank (12) and is designed to supply
an alkaline solution in the wash tank (12) of the dishwasher (1) by
electrolysis.
2. The dishwasher (1) as claimed in claim 1, wherein the
final-rinse system has a storage container (30), for accommodating
a final-rinse concentrate, and a multiplicity of final-rinse
nozzles (18), for spraying washware with a final-rinse fluid (42),
wherein the storage container (30) is, or can be, connected to the
wash tank (12) such that optionally the final-rinse concentrate
and/or the final-rinse fluid (42) can be metered out of the
final-rinse system into the wash tank (12).
3. The dishwasher (1) as claimed in claim 2, wherein the storage
container (30) is, or can be, connected directly to the wash tank
(12), and therefore it is an option for the final-rinse concentrate
to be metered directly into the wash tank (12).
4. The dishwasher (1) as claimed in claim 2, wherein the
final-rinse system has at least one boiler (40), which has a
fresh-water connection (50) and is, or can be, connected to the
final-rinse tank (30) for the supply of a final-rinse fluid (42),
and wherein, in addition, the boiler (40) is, or can be, connected
to the wash tank (12) such that it is an option for the final-rinse
fluid (42) to be metered out of the boiler (40) into the wash tank
(12).
5. The dishwasher (1) as claimed in claim 2, wherein the
treatment-fluid generator (100) has a first metering pump (110),
for controlled metering of the alkaline solution into the wash tank
(12), and wherein the final-rinse system has a second metering pump
(38, 48), for controlled metering of the final-rinse concentrate
and/or of the final-rinse fluid into the wash tank (12).
6. The dishwasher (1) as claimed in claim 1, wherein the dishwasher
(1) has a control device which is, or can be, connected to the
first and second metering pumps (38, 48, 110) and is designed to
activate the first and second metering pumps (38, 48, 110) so as to
achieve a treatment fluid (20) with a pH value of at least 9, in
the wash tank (12).
7. The dishwasher (1) as claimed in claim 1, wherein the wash tank
(12) has at least one sensor means for measuring the pH value of
the treatment fluid (20) located in the wash tank (12).
8. The dishwasher (1) as claimed in claim 1, wherein the
treatment-fluid generator (100) is designed to supply an alkaline
solution with a pH value of 10 to 14, in particular of 11.5 to
13.
9. The dishwasher (1) as claimed in claim 1, wherein the
treatment-fluid generator (100) is also designed to generate an
acid solution which has a pH value of 1 to 7, in particular 2.5 to
6, and is suitable for disinfecting components of the dishwasher
(1) and/or for disinfecting washware.
10. The dishwasher (1) as claimed in claim 9, wherein the
dishwasher (1) has a control device which is designed to make a
selection between a first operating mode, for washing the washware
with treatment fluid (20) at a first temperature, and a second
operating mode, for washing the washware with treatment fluid (20)
at a second temperature, which is lower than the first temperature,
and wherein the control device is also designed to initiate an
operation for spraying the washware with the acid solution in the
second operating mode.
11. The dishwasher (1) as claimed in claim 1, wherein the
electrolysis device (109) of the treatment-fluid generator (100)
is, or can be, connected to a fresh-water connection (101), and to
an additive container (107), so that a starting solution can be
supplied for the electrolysis device (109).
12. The dishwasher (1) as claimed in claim 11, wherein the
dishwasher (1) has a water-treatment device with a salt container
for accommodating sodium chloride, and wherein the additive
container (107) is, or can be, connected to the salt container such
that sodium chloride from the salt container can be fed to the
additive container (107).
13. The dishwasher (1) as claimed in claim 12, wherein the additive
container (107) is designed as a salt container for accommodating
sodium chloride, wherein feeding fresh water into the additive
container (107) makes it possible to supply a salt solution, in
particular a saturated salt solution, which serves as a starting
solution for the electrolysis unit (109) or for supplying the
starting solution for the electrolysis device (109).
14. A method of operating a dishwasher (1) as claimed in claim 1,
wherein the method has the following steps: feeding fresh water
into a tank of the electrolysis unit and/or into a salt container
of the dishwasher (1); operating the electrolysis unit in order to
generate an alkaline solution from the fresh water fed to the tank
and/or salt container; feeding the alkaline solution into a wash
tank (12) of the dishwasher (1); and spraying washware with the
alkaline solution located in the wash tank (12).
15. The method as claimed in claim 14, wherein the method, prior to
the operation of spraying the washware, has the following steps:
supplying a final-rinse concentrate in a storage container (30) of
the dishwasher (1); and metering the final-rinse concentrate into
the alkaline solution located in the wash tank (12).
16. The method as claimed in claim 15, wherein the final-rinse
concentrate has at least one wash additive comprising complex
formers and/or surface-active substances and/or anti-foaming agents
and/or corrosion inhibitors.
17. The method as claimed in claim 14, wherein the electrolysis
unit is operated such that the alkaline solution has a pH value of
10 to 14, in particular of 11.5 to 13.
18. The method as claimed in claim 14, wherein sodium chloride is
metered into the fresh water, prior to the alkaline solution being
generated by the electrolysis unit, so as to achieve a common-salt
solution with a concentration of preferably 1 to 20 g/l, which
serves as a starting solution for the electrolysis unit, or to
achieve a saturated common-salt solution which provides a starting
solution for the electrolysis unit with a concentration of 1 to 20
g/l.
19. The method as claimed in claim 18, wherein the sodium chloride
can be removed from a water-treatment device of the dishwasher and
is metered into the fresh water.
20. The method as claimed in claim 14, wherein an acid solution, in
particular hypochlorous acid, is generated at the same time as an
alkaline solution is generated, wherein at least some of the acid
solution is directed, for disinfecting purposes, into the treatment
chamber (10) of the dishwasher (1).
21. The method as claimed in claim 20, wherein the method,
following the step of spraying the washware with the alkaline
solution, also has a step for spraying the washware with the acid
solution.
Description
[0001] The present application relates in particular to a
commercial dishwasher for crockery or utensils and which is
designed as a box-type dishwasher or as a conveyor dishwasher.
[0002] Accordingly, the application relates to a dishwasher having
at least one wash tank, for accommodating a treatment fluid, and at
least one final-rinse system, for supplying a final-rinse fluid.
Such dishwashers are known from the prior art. Thus, in the case of
the conventional dishwashers, the treatment fluid located in the
wash tank is applied to the washware via spray nozzles. For
generating the treatment fluid, it is customary, in particular in
the context of commercial dishwashers, to use highly alkaline wash
agent. Use is likewise made of final-rinse agents in order to
assist in the self-drying of the crockery, to remove residues of
wash agent and to accentuate the shine of the crockery. For this
reason, a wide variety of products are available on the market from
innumerable manufacturers and distributors of wash chemicals, these
products, in some cases, being sold at very high prices.
[0003] High outlay in respect of transportation is also involved,
since these chemicals have to be constantly supplied to the user of
the dishwasher.
[0004] On the basis of the problem set out above, a dishwasher is
provided which generates at least a main component of the treatment
fluid itself. The dishwasher may also have reduced running
costs.
[0005] Accordingly, the dishwasher is characterized in that it has
a treatment-fluid generator with at least one electrolysis device.
The treatment-fluid generator here is, and/or can be, connected to
the wash tank and is designed to supply an alkaline solution in the
wash tank of the dishwasher by electrolysis.
[0006] The advantages of the subject dishwasher may include: for
example, the treatment-fluid generator makes it possible to
dispense with at least some of the numerous chemicals for
generating the treatment fluid. In particular the treatment-fluid
generator requires just a fresh-water connection in order to supply
a highly alkaline treatment fluid in the wash tank of the
dishwasher. This alkaline solution produced by electrolysis has a
cleaning action which is at least equivalent to the conventional
chemicals. Furthermore, the electrolysis uses up only a very small
amount of chemicals, for which reason the present dishwasher is
particularly advantageous to operate. Furthermore, the
treatment-fluid generator makes it possible to dispense with many
of the chemical substances, as a result of which outlay in respect
of transportation and ease of use are increased.
[0007] Thus, in a first realization of the dishwasher, provision is
made for the final-rinse system to have a storage container, for
accommodating a final-rinse concentrate, and a multiplicity of
final-rinse nozzles, for spraying washware with a final-rinse
fluid. Accordingly, the storage container is, or can be, connected
to the wash tank such that optionally the final-rinse concentrate
can be metered into the wash tank. According to this variant, the
final-rinse concentrate located in the storage container can be
used not just for generating a final-rinse liquid, which is used by
the final-rinse nozzles for spraying the washware; rather, at the
same time, the final-rinse concentrate can be metered, in the form
of a wash additive, into the alkaline solution located in the wash
tank, in order to generate a particularly effective treatment
fluid. This is advantageous in particular when the alkaline
solution generated by the treatment-fluid generator provides
insufficient dishwashing results and has to be regenerated. In this
case, this embodiment does not require additional chemicals to be
fed to the wash tank, since use can be made of the final-rinse
concentrate which is present anyway in the final-rinse system.
[0008] The final-rinse concentrate here may contain, for example,
specific substances from the complex-former groups of substances,
for reducing the water hardness and for assisting cleaning,
surface-active substances, for stabilizing emulsions and
dispersions, and anti-foaming agents, and possibly also corrosion
inhibitors.
[0009] The surface-active substances for stabilizing emulsions and
dispersions are preferably surfactants which are known from
dishwashing technology and can be gathered, for example, from US
Patent Publication No.20100108942 A1, paragraphs [0104] to [0132].
Of course, the surface-active substances of the final-rinse
concentrate are not restricted to the aforementioned groups of
substances.
[0010] Depending on the washware which is to be treated and on the
degree of soiling thereof, increased foam formation may occur, in
certain circumstances, during operation of the dishwasher. In such
cases, it is particularly advantageous if the final-rinse
concentrate contains an anti-foaming agent. The anti-foaming
agents, also referred to as foam inhibitors or foam dampers, are
preferably biodegradable anti-foaming agents which are food-safe.
The anti-foaming agents here may be any which are known from the
prior art, e.g. natural fats, oils or fatty alcohols.
[0011] According to one aspect, the storage container is, or can
be, connected directly to the wash tank, and therefore it is an
option for the final-rinse concentrate to be metered directly into
the wash tank. As an alternative, or in addition, the final-rinse
system may have at least one boiler, which has a fresh-water
connection and is, or can be, connected to the final-rinse tank for
the supply of a final-rinse fluid, wherein said boiler is, or can
be, connected to the wash tank such that it is an option for the
final-rinse fluid (fresh water+final-rinse concentrate) generated
in the boiler to be metered out of the boiler into the wash tank.
Accordingly, the final-rinse concentrate used as wash additive
either can be metered directly out of the storage container into
the wash tank or can be directed, in the form of final-rinse fluid,
from the boiler into the wash tank. In the case of the final-rinse
concentrate being introduced directly into the wash tank, the
final-rinse concentrate is particularly straightforward to meter.
In contrast, if the final-rinse concentrate is introduced
indirectly via the boiler of the final-rinse system, it may prove
to be advantageous that conventional dishwashers can be retrofitted
in a straightforward manner. A further metering pump may possibly
also have to be provided for this purpose.
[0012] According to a further embodiment, the treatment-fluid
generator has a first metering pump, for controlled metering of the
alkaline solution into the wash tank. The final-rinse system also
has a second metering pump, for controlled metering of the
final-rinse concentrate and/or of the final-rinse fluid into the
wash tank. The metering pumps may thus be used to supply the
desired treatment fluid as a combination of the alkaline solution
and of the final-rinse concentrate, or of the final-rinse fluid, in
the wash tank.
[0013] In specific terms, the metering pumps may be set here so as
to achieve a treatment fluid with a pH value of at least 9, and
preferably at least 10, in the wash tank. This is made possible, in
particular, by a control device which is, or can be, connected to
the first and second metering pumps and is designed to activate the
first and second metering pumps. It is thus possible to generate,
via the control device, any desired mixing ratio between the
final-rinse concentrate and the alkaline solution of the
treatment-fluid generator.
[0014] In order for it to be possible to generate a feedback signal
for the control device, the wash tank may have at least one sensor
means for measuring the pH value of the treatment fluid located in
the wash tank. Accordingly, the sensor means is likewise connected
to the control device, and therefore the latter can draw
conclusions as to the pH value of the treatment fluid. It is thus
possible for the pH value of the treatment fluid to be regulated
continuously by the control device, with the aid of the two
metering pumps, throughout the dishwashing operation. Of course, it
is likewise conceivable for the sensor means also to be designed to
sense precisely the active-substance fractions within the treatment
fluid. It would thus be possible for the control device to obtain,
for example, information relating to the quantity of complex
formers currently located in the treatment fluid.
[0015] According to a further aspect, the treatment-fluid generator
is designed to supply an alkaline solution with a pH value of 10 to
14, in particular of 11.5 to 13. For this purpose, the electrolysis
device can operate, for example, in accordance with the principle
of producing an aqueous alkali-hydroxide solution. An alkaline
solution with such a high pH value of 10 to 14 has a particularly
high-level cleaning action.
[0016] In addition to generating the alkaline solution, the
treatment-fluid generator of the dishwasher may also be designed to
generate an acid solution which has a pH value of 1 to 7, in
particular of 2.5 to 6. The chlorine which is generated anyway
during the electrolysis can be used, for example, as an acid
solution for disinfecting the washware. It is conceivable, for this
purpose, for the dishwasher to have a further tank which is formed
for accommodating the acid solution, i.e. the disinfectant. The
disinfecting operation using the acid solution can take place, for
example, immediately prior to, or at the same time as, final
rinsing with fresh water, in order to guarantee that all the germs
are killed off
[0017] According to a further embodiment, the dishwasher has a
control device which is designed to make a selection between a
first operating mode, for washing the washware with treatment fluid
at a first temperature, and a second operating mode, for washing
the washware with a treatment fluid at a second temperature. The
second temperature may be, for example, lower than the first
temperature.
[0018] The control device is preferably designed to initiate an
operation for spraying the washware with the acid solution in the
second operating mode. It is thus possible to realize the situation
where the dishwasher initiates follow-up cleaning (i.e.
disinfection) of the washware only when the washware has been
cleaned at a lowered temperature. For example, the first
temperature may be a dishwashing temperature of approximately 80
degrees Celsius, whereas the second temperature is approximately 60
degrees Celsius or less. Accordingly, the acid solution is used
merely during operation at low temperatures, as a result of which
it is possible to cut back on energy and time, since disinfection
using the acid solution is not absolutely necessary in the hot
operating mode.
[0019] As an alternative to the aforementioned embodiments, the
chlorine which is produced during the electrolysis process can also
be disposed of by way of an outlet valve.
[0020] According to a further realization of the dishwasher, the
electrolysis device of the treatment-fluid generator is, or can be,
connected to a fresh-water connection, and to an additive
container, so that a starting solution can be supplied for the
electrolysis device. Accordingly, it is possible to generate, in
the electrolysis device, a starting solution which has a higher
level of conductivity than fresh water.
[0021] According to a particularly advantageous variant, the
dishwasher has a water-treatment device with a salt container for
accommodating sodium chloride. The additive container of the
treatment-fluid generator here is, or can be, connected to the salt
container such that sodium chloride from the salt container of the
water-treatment device can be fed to the additive container.
[0022] It should be mentioned in this connection that, in practice,
virtually every conventional dishwasher has a water-treatment
device. This is designed to adjust the properties of the fresh
water as best as possible to the subsequent dishwashing process.
The water-treatment device therefore frequently contains water
filters and also a salt container. The salt container serves, in
particular, to meter sodium chloride into the fresh water, in order
for the water-treatment device to be regenerated if required.
[0023] According to the aforementioned embodiment, it is thus
possible for the additive container of the treatment-fluid
generator to be fed with sodium chloride from the salt container
which is located in any case in the water-treatment device.
Accordingly, there is no need for any further additive to be fed to
the dishwasher. As an alternative, it is even conceivable, for this
purpose, for the additive container to be designed in as a salt
container of the water-treatment device and to be arranged between
the fresh-water connection and the electrolysis device such that a
common-salt solution can be fed, as starting solution, to the
electrolysis device.
[0024] As already indicated, the additive container may be a salt
container which is designed for accommodating sodium chloride and
is, or can be, connected to the electrolysis device such that the
starting solution results in a common-salt solution with a
concentration of 1 to 20 g/l, preferably 3 to 10 g/l, and in
particular 5 g/l. In particular the electrolysis of a common-salt
solution gives rise to sodium hydroxide, which can be used as an
alkaline solution for generating the treatment fluid. Also achieved
is a hypochlorous acid, which can be used as an acid solution for
disinfecting the washware. In particular, the electrolysis of the
common-salt solution proceeds in accordance with the following
reaction equations:
[0025] Cathode reaction:
4H.sub.2O-->2H.sub.3O+2OH.sup.- Dissociation of the water
2H.sub.3O+2e.sup.--->H.sub.2+2H.sub.2O Cathode reaction
2H.sub.2O+2e.sup.--->H.sub.2+2OH.sup.- Overall reaction in the
cathode space
Anode reaction:
2Cl.sup.--->Cl.sub.2+2e.sup.- Anode reaction
2NaCl-->2Na.sup.++Cl.sub.2+2e.sup.- Overall reaction in the
anode space
Overall reaction:
2NaCl+2 H.sub.2O-->2NaOH+Cl.sub.2+H.sub.2
[0026] In another aspect, a method of operating a dishwasher
involves a step for feeding fresh water into a tank of the
electrolysis device, whereupon the electrolysis device is operated
in order to generate an alkaline solution from the fresh water
located in the tank and added salt (NaCl). This takes place in
particular by the analyte generated at the anode being divided off
from the catholyte generated at the cathode. The catholyte
generated at the cathode is then pumped, as an alkaline solution,
out of the tank of the electrolysis device into the wash tank of
the dishwasher. In order to clean the washware, the latter is
sprayed with the alkaline solution located in the wash tank, said
solution serving as the treatment fluid.
[0027] Of course, the method of generation of the alkaline solution
allows many of the conventionally used chemicals to be dispensed
with. This not only cuts back on costs, but also reduces the outlay
in respect of transportation.
[0028] In addition to the aforementioned steps, prior to the
operation of spraying the washware, the method may have a step for
supplying a final-rinse concentrate in a storage container of the
dishwasher, wherein the final-rinse concentrate is metered, if
required, into the alkaline solution located in the wash tank, in
order to generate a treatment fluid with even better cleaning
properties. The final-rinse concentrate here may have at least one
wash additive comprising complex formers and/or surface-active
substances and/or anti-foaming agents and/or corrosion inhibitors.
Accordingly, these wash additives, which are often present in
conventional final-rinse concentrates, need not be provided in the
treatment-fluid generator. Rather, the final-rinse system, which is
required in any case, can be used in order to feed the wash
additive.
[0029] According to a further realization of the method, an
additive for accelerating the dissociation of the fresh water can
be added to the fresh water prior to the alkaline solution being
generated by the electrolysis device. This additive may be, in
particular, sodium chloride, which is metered into the fresh water
so as to achieve a common-salt solution with a concentration of 1
to 20 g/l, preferably of 3 to 10 g/l, in particular 5 g/l. It is
conceivable, of course, to use any additive which, following the
electrolysis, results in an aqueous alkali-hydroxide solution,
which can then be used as the treatment fluid.
[0030] If the additive used is sodium chloride, this can
advantageously be removed from a water-treatment device of the
dishwasher and metered into the fresh water. This means that the
dishwashing salt which is often used anyway in dishwashers can be
used not just for water-softening purposes, but also as an additive
in order to allow the electrolysis in the treatment-fluid
generator.
[0031] The method may also have a step for generating an acid
solution from the fresh water located in the tank of the
electrolysis device. The step for generating the acid solution
takes place, in particular, at the same time as the step for
generating the alkaline solution, that is to say as a further
product of the electrolysis within the treatment-fluid generator.
The resulting acid solution is applied to the washware preferably
following the operation of spraying the washware with the alkaline
solution and prior to, or during, final rinsing with fresh water.
This allows the washware to be disinfected in a straightforward
manner.
[0032] The dishwasher will be explained in more detail hereinbelow
with reference to the embodiments illustrated in the drawings, in
which:
[0033] FIG. 1 shows a schematic illustration of a first embodiment
of the dishwasher;
[0034] FIG. 2 shows a schematic illustration of a second embodiment
of the dishwasher; and
[0035] FIG. 3 shows a schematic illustration of an exemplary
embodiment of the treatment-fluid generator.
[0036] The following detailed description of the figures provides
like or equivalent components with like designations.
[0037] The illustration according to FIG. 1 illustrates a first
exemplary embodiment of the dishwasher 1. It should be pointed out
that this dishwasher merely has the components which are required
for understanding. The dishwasher 1 is, in particular, a commercial
dishwasher for crockery or utensils and is designed as a box-type
dishwasher. Of course, it is likewise possible for the dishwasher 1
to be designed as a conveyor dishwasher. The modifications in
design which are necessary for this purpose are, of course, known
to a person skilled in the art.
[0038] The dishwasher 1 illustrated in FIG. 1 has a treatment
chamber 10 with an associated wash tank 12. The wash tank 12 serves
for accommodating a treatment fluid 20, which can be delivered to a
multiplicity of wash nozzles 16 via a wash pump 14. The wash
nozzles 16 are located, in particular according to the embodiment
illustrated, in the upper and lower regions of the treatment
chamber 10. They are connected to the wash tank 12 via a wash line
15. Since the wash tank 12 is located in the lower region of the
treatment chamber 10, this allows the treatment fluid to be
recirculated once the washware has been sprayed.
[0039] The dishwasher 1 shown also has at least one final-rinse
system for supplying a final-rinse fluid. The final-rinse system,
in the embodiment illustrated, comprises a storage container 30,
which contains a final-rinse concentrate. As can be seen from FIG.
1, the storage container 30 of the final-rinse system is connected
to a boiler 40 via a fluid line 32. The boiler 40 has a fresh-water
connection 50, via which fresh water (e.g. mains water) can be
introduced into the boiler 40. The fresh water located in the
boiler 40 is heated by a heating device 41 and mixed with the
final-rinse concentrate from the storage container 30. For this
purpose, the final-rinse concentrate is delivered to the boiler 40
from the storage container 30 by way of a metering pump 31. The
final-rinse fluid, produced from a combination of fresh water and
final-rinse concentrate, can be delivered to a multiplicity of
final-rinse nozzles 18 via a final-rinse pump 43 and the associated
final-rinse lines 44. In a manner similar to the wash nozzles 16,
it is also the case that the final-rinse nozzles 18 are located in
the interior of the treatment chamber 10 of the dishwasher 1.
[0040] Finally, it can be seen from FIG. 1 that the dishwasher 1
also has a treatment-fluid generator 100, which is illustrated
merely as a "black box" in the schematic illustration. The
treatment-fluid generator 100 has at least one electrolysis device
(see FIG. 3) and is, or can be, connected to the wash tank 12 of
the dishwasher 1. The treatment-fluid generator 100 is designed to
supply an alkaline solution in the wash tank 12 of the dishwasher 1
by electrolysis. There is therefore no need for the dishwasher 1 to
use additional chemicals in order to generate the treatment
fluid.
[0041] The treatment-fluid generator 100 used for this purpose is
illustrated schematically in FIG. 3. It has at least one
fresh-water connection 101, which is connected to the electrolysis
device 109 via a control valve 102. The fresh water located in the
electrolysis device 109 is divided into an alkaline solution and an
acid solution by virtue of an electric voltage being applied to
appropriate electrodes. The alkaline solution, which forms at the
cathode of the electrolysis device 109, can then be delivered into
the wash tank 12 of the dishwasher 1, via the fluid line 111, with
the aid of a metering pump 110.
[0042] It should be noted here that the treatment-fluid generator
100 may be located either within the housing (not illustrated) of
the dishwasher 1 or outside the same. It is thus conceivable, for
example, for conventional dishwashers to be retrofitted, by the
provision of an external treatment-fluid generator.
[0043] In addition to the fresh-water connection 101 and the
electrolysis device 109, the treatment-fluid generator 100 may
have, for example, a filter 103, a water-treatment element 105 and
an additive container 107. The units 103, 105 and 107, each
illustrated as a "black box" in FIG. 3, serve, in particular, to
influence the composition of the alkaline solution formed by the
electrolysis device. It is also possible to use the additive
container 107 to supply a starting solution with a higher reaction
speed for the electrolysis device 109.
[0044] For example, it is possible here for the additive container
107 to be designed as a salt container for accommodating sodium
chloride and to be connected, or connectable, to the electrolysis
device 109 such that the starting solution located in the
electrolysis device 109 results in a common-salt solution with a
concentration of 1 to 20 g/l, preferably of 3 to 10 g/1 and in
particular 5 g/l. Using common-salt solution as the starting
solution for the electrolysis gives rise to the alkaline solution
sodium hydroxide (NaOH), which can be fed directly to the wash tank
12 via the discharge line 111.
[0045] Also produced is a hypochlorous acid (HClO), which can be
used as an acid solution for disinfecting the washware. For this
purpose, the acid solution may be connected to the wash nozzles 16
and/or final-rinse nozzles 18 directly for example via a second
discharge line 112. As an alternative, or in addition, it is also
possible to provide an outflow line 113, or the second discharge
line 112 may have an outflow line 113, via which the acid solution
can optionally be disposed of (cf. FIG. 3).
[0046] As already indicated, dishwashers usually already have a
water-treatment device with a salt container, in order to reduce,
for example, the hardness of the fresh water. Accordingly, it is
also conceivable, according to a variant which is not illustrated,
for the fresh-water connection 101, the control valve 102, the
filter 103, the water-treatment element 105 and the additive
container 107 of the treatment-fluid generator 100 to be formed by
the water-treatment installation which is present in any case. In
specific terms, it is particularly advantageous here to use the
salt container as additive container 107 and to connect the same,
consequently, to the electrolysis unit 109 of the treatment-fluid
generator 100. As an alternative, it is also possible for the
additive container 107 to be connected, or connectable, to the salt
container of the water-treatment device via a delivery line, in
order to feed sodium chloride as additive.
[0047] The dishwasher 1 also has a control device (not illustrated)
which is, or can be, connected to the metering pump 110 and is
designed to activate the metering pump 110 so as to achieve a
treatment fluid with a pH value of at least 10 in the wash
tank.
[0048] As already indicated, the final-rinse system has a storage
container 30 for accommodating a final-rinse concentrate, wherein
the final-rinse concentrate is used to supply the multiplicity of
final-rinse nozzles 16 with the final-rinse fluid 42 generated in
the boiler 40. At the same time, it is possible for the storage
container 30 to be connected, or connectable, to the wash tank 12
such that it is an option for the final-rinse concentrate and/or
the final-rinse fluid to be metered out of the final-rinse system
into the wash tank 12.
[0049] According to the embodiment illustrated in FIG. 1, this
takes place, in particular, by way of a direct connection between
the storage container 30 and the wash tank 12. For this purpose,
the storage container 30 has a second fluid line 36, which is
connected directly to the wash tank 12. A metering pump 38 is
located within the second fluid line 36, and can likewise be
operated via the aforementioned control device (not illustrated).
This makes it an option for the final-rinse concentrate located in
the storage container 30 to be fed to the wash tank 12 of the
dishwasher 1. Accordingly, the treatment fluid 20 located in the
wash tank 12 is a combination of the final-rinse concentrate and of
the alkaline solution from the treatment-fluid generator 100.
[0050] The final-rinse concentrate functions as a wash additive
comprising complex formers and/or surface-active substances and/or
anti-foaming agents and/or corrosion inhibitors. Reference is also
made in this connection to the aforementioned exemplary embodiments
of the wash additives.
[0051] In respect of the second exemplary embodiment of the
dishwasher 1, this exemplary embodiment being illustrated in FIG.
2, it should be mentioned that provision may also be made, as an
alternative, for the final-rinse fluid generated in the boiler 40
to be introduced into the wash tank 12 via a second discharge line
46 of the boiler 40. Accordingly, according to the second
embodiment, the final-rinse concentrate is not supplied directly
into the wash tank 12; rather, the final-rinse fluid 42 consisting
of the final-rinse concentrate and the fresh water is metered into
the treatment fluid 20. A metering pump 48 is once again provided
for this purpose, and this one can likewise be controlled via the
control unit (not illustrated). According to this embodiment, the
treatment fluid 20 is a combination of the alkaline solution and
the final-rinse fluid supplied in the boiler 40.
[0052] In summary, all that remains to be said is that the control
device of the dishwasher 1 is connected to the respective metering
pumps 31, 38, 48 and 110, and is designed to activate the same, so
as to achieve a treatment fluid 20 with a pH value of at least 9,
and preferably at least 10, in the wash tank 12. This provides a
treatment fluid 20 with an optimum cleaning behavior. The wash tank
12 may also have at least one sensor means (not illustrated in the
drawings) for measuring the pH value of the treatment fluid located
in the wash tank 12. This sensor means is, of course, likewise
connected to the control device, in order to allow conclusions to
be drawn as to the pH value of the treatment fluid 20. Should the
pH value be below a predetermined desired value of, for example, at
least 9, then the control device will feed alkaline solution from
the treatment-fluid generator 100 repeatedly to the wash tank
12.
[0053] The treatment-fluid generator is also designed to supply an
alkaline solution with a pH value of 10 to 14, in particular 11.5
to 13. In contrast, the acid solution supplied by the
treatment-fluid generator 100 should have a pH value of 1 to 7, in
particular 2.5 to 6.
[0054] According to a further embodiment, the control device also
has the task of making a selection between a first operating mode,
for washing the washware with treatment fluid 20 at a first
temperature, and a second operating mode, for washing the washware
with treatment fluid 20 at a second temperature. The second
temperature here is preferably lower than the first temperature,
wherein the control device is designed to initiate an operation for
spraying the washware with the acid solution in the second, colder
operating mode. The second operating mode is based on the finding
that the dishwashing result with the alkaline solution from the
treatment-fluid generator 100 at low temperatures is not always
sufficient. For this reason, the acid solution, which is generated
anyway, is applied as disinfectant once the washware has been
cleaned. If the treatment fluid has a first, higher temperature of
approximately 80 degrees Celsius, then subsequent disinfection of
the washware is not absolutely necessary. In this case, the control
device is designed to operate the dishwasher in a first operating
mode, which does not provide for the follow-up cleaning with the
acid solution.
[0055] The present application is not restricted to the features
and combinations illustrated in the drawings. In particular it
should be pointed out that the dishwasher need not be designed, as
illustrated in the figures, as a box-type dishwasher. It may, of
course, also be designed as a conveyor dishwasher.
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