U.S. patent application number 10/473260 was filed with the patent office on 2005-01-27 for household apparatus using a liquid, comprising a purifying system of the type in which at least a substance must be removed form said liquid.
Invention is credited to Fiorini, Andrea, Gadini, Costanzo.
Application Number | 20050017114 10/473260 |
Document ID | / |
Family ID | 11458754 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050017114 |
Kind Code |
A1 |
Gadini, Costanzo ; et
al. |
January 27, 2005 |
Household apparatus using a liquid, comprising a purifying system
of the type in which at least a substance must be removed form said
liquid
Abstract
Household apparatus using a fluid, comprising a purifying system
in which at least a substance must be removed from at least a
portion of said fluid, said system comprising: an electrochemical,
electro-dialysis or electro-osmosis cell (20); collecting means
(P,S,AC) of said fluid; controlling means (SCE). According to the
invention, recycle means are provided (12,22,23,15,21,24), to
realize a substantially closed circuit and/or continuous
circulation of said fluid between the collecting means (P,S) and
said cell (20), until a preset purifying value of the fluid is
reached.
Inventors: |
Gadini, Costanzo; (Casale
Monferrato Al, IT) ; Fiorini, Andrea; (Monferrato Al,
IT) |
Correspondence
Address: |
LEVINE & MANDELBAUM
444 MADISON AVENUE
35TH FLOOR
NEW YORK
NY
10022
US
|
Family ID: |
11458754 |
Appl. No.: |
10/473260 |
Filed: |
October 23, 2003 |
PCT Filed: |
April 2, 2002 |
PCT NO: |
PCT/IB02/01018 |
Current U.S.
Class: |
242/375.1 |
Current CPC
Class: |
C02F 2201/4612 20130101;
C02F 1/469 20130101; C02F 2201/46115 20130101; B01D 61/54 20130101;
A47L 15/4229 20130101; C02F 1/4693 20130101; C02F 1/4698 20130101;
B01D 61/48 20130101; B01D 61/44 20130101 |
Class at
Publication: |
242/375.1 |
International
Class: |
B65H 075/48 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 2, 2001 |
IT |
TO2001A000314 |
Claims
1. A household apparatus using a fluid, comprising a purifying or
treatment system of the type in which at least a substance must be
removed from at least a portion of said fluid, in particular a
water softening system, said system comprising at least an
electrochemical, electro-dialysis or electro-osmosis cell, with a
positive electrode and a negative electrode, and at least a
permeable separation element, further comprising it provides: a
first type of separation element, of the ion exchange element type,
being permeable to at least a first substance to be removed from at
least a portion of said fluid, a second type of separation element,
of the ion exchange type, not being permeable to said first
substance and permeable to at least a second substance, a plurality
of channels delimited between said electrodes and/or said
separation elements, first collecting means of a portion of said
fluid from which said substance must be extracted or the fluid to
be purified, second collecting means of a portion of said fluid
provided to receive said first substance or the fluid to be
contaminated, means in association with at least said first and/or
second collecting means (P, S, AC) for detecting the features of at
least a part of the fluid, circulation means for obtaining a
substantially closed circuit and/or a continuous circulation of
said fluid between said collecting means and said channels of said
cell for purifying at least a part of the fluid, controlling means
comprising at least one electronic controller, and receiving
information from said means, for controlling at least said cell and
the fluid circulation until a preset purifying value of said fluid
is reached.
2. A household apparatus according to claim 1, wherein said means
in association with at least said first and/or second collecting
means for detecting the features of at least a part of the fluid,
comprise: first sensing means located in said first collecting
means for detecting the features of at least a part of the fluid,
and/or second sensing means located in said second collecting means
for detecting the features of at least a part of the fluid.
3. A household apparatus according to claim 1, wherein the flow
speed of the fluid in the said channels is changed by the control
means based on measurements performed according to predetermined
algorithms or data tables.
4. A household apparatus according to claim 1, wherein the said
water softening system is all or partly integrated in one device in
particular made of thermo-plastic material.
5. A household apparatus according to claim 3, wherein said first
collecting means are hydraulically connected upstream said cell,
being apt to receive the fluid to be purified before its flowing in
said cell.
6. A household apparatus according to claim 4, wherein said second
collecting means are hydraulically connected upstream said cell,
being apt to receive the fluid to be contaminated before its
flowing in said cell.
7. A household apparatus according to claim 3, comprising first
dosing or measuring means of the quantity or features of the fluid
to be purified being supplied to said first collecting means
(P).
8. A household apparatus according to claim 4, comprising second
dosing or measuring means of the quantity or features of said fluid
ontaminated being supplied to said second collecting means.
9. A household apparatus according to claims 3, wherein said
channels comprise: one or more first channels, in which said fluid
to be purified will flow, said first channels being delimited by a
first type of separating element and a second type of spearating
element; two or more second channels, in which a fluid will flow,
which is provided to receive said first substance to be removed
from the fluid to be purified flowing in the first channels, or
fluid to be contaminated, each one of said second channels being
delimited by a first type of separating element and a second type
of separating element or extending between one of said electrodes
and one of said separating elements.
10. A household apparatus according to claim 1 wherein said first
type of separating element is a cationic ion exchange membrane.
11. A household apparatus according to claim 1, wherein said second
type of separatin element is an anionic ion exchange membrane.
12. A household apparatus according to claim 9, wherein said first
collecting means are hydraulically connected to said first channels
and said second collecting means are hydraulically connected to
said second channels.
13. A household apparatus according to claim 12, comprising first
circulation means for obtaining said continuous circulation of said
fluid to be purified between said first collecting means and said
first channels.
14. A household apparatus according to claim 12, comprising second
circulation means for obtaining said continuous circulation of said
fluid to be contaminated between said second collecting means and
said second and/or third channels.
15. A household apparatus according to claim 13, wherein said
control means operate for activating said first circulating means
and/or said second circulation means concurrently to generation of
said electric field between said electrodes.
16. A household apparatus according to claim 1, wherein said
control means for reversing periodically the polarity of said
electrodes.
17. A household apparatus according to claim 9, wherein said
control means operate for reversing the functions of said first
collecting means and said second collecting means, so as to collect
said fluid to be contaminated in said first collecting means and
collect said fluid to be purified in said second collecting means,
and that the fluid to be contaminated is circulated in said first
channels and the fluid to be purified is circulated in said second
channels.
18. A household apparatus according to claim 4, wherein said
control means operate for changing the dosage of the amount of said
fluid to be contaminated in the respective collecting means,
depending on the initial contents of said first substance in the
inlet fluid to the household apparatus.
19. A household apparatus according to at claim 1, wherein said
control means operate for controlling and maintain the flow-rate of
the fluid at a preset value in the course of said continuous
circulation.
20. A household apparatus according to claims 1, wherein said
control means operate for controlling and change the flow-rate of
the fluid during said continuous circulation, in particular
according to preset or calculated values.
21. A household apparatus according to at claim 1, comprising
pre-treatment means of the fore its flowing in said cell.
22. A household apparatus according to claim 21, wherein said
pre-treatment means comprise filtering means and/or decanting means
of the fluid.
23. A household apparatus according to claim 22, wherein said
pre-treatment means comprise disinfecting means of the fluid.
24. A household apparatus according to claim 1, wherein said
control means operate for changing the conditions and/or duration
of said continuous circulation.
25. A household apparatus according to claims 3, wherein said
control means operate for using the same fluid to be contaminated
for a pluraltiy of purifying processes, or for the treatment
purposes of a plurality of amounts of fluid to be purified.
26. A household apparatus according to claim 1, wherein said
control means (SCE) operate for reversing the fluid flow in said
cell and/or obtain a counter-current washing of said channels
and/or said electrodes and said separating elements.
27. A household apparatus according to claim 1, wherein said
control means operate for changing the value of said voltage and/or
electric current.
28. A household apparatus according to claim 1, wherein said
control means operate for changing the supply procedures of said
electrodes in the frame of one same purifying process.
29. A household apparatus according to claim 1, comprising sensing
means for detecting the room temperature in proximity of said cell
and/or of the fluid to be purified, in order to change the
operating parameters of said cell.
30. A household apparatus according to claim 1, comprising sensing
means for detecting the features of said fluid, in particular its
"quantitative" features, such as flow-rate, pressure, level,
temperature, and/or its "qualitative" or chemical or
electrochemical features, such as conductivity, hardness degree,
acidity degree or pH.
31. A household apparatus according to claim 1, comprising an
additional and/or independent circulation circuit for a washing
solution or fluid of said electrodes or of said channels.
32. A household apparatus according to the claim 31, wherein the
second channels extending between one of said electrodes and one of
said separating elements are hydraulically connected to each other,
in particular in parallel.
33. A household apparatus according to claim 31, wherein the
separating elements, which delimit the second channels comprising
said electrodes are of the same type.
34. A household apparatus according to claim 1, wherein the
separating elements, which delimit the second channels comprising
said electrodes are of said first type, in particular cationic.
35. A household apparatus according to the 33, wherein the
separating elements, which delimit the second channels comprising
said electrodes are of the cationic type selective to univalent
ions.
36. A household apparatus according to claim 31, comprising means
for a likely topping up and/or replacement at regular intervals of
said washing solution or fluid of said electrodes or channels.
37. A household apparatus according to claim 1, comprising means
for changing the times and/or values of the electric voltage supply
of said electrodes depending on the conductivity degree of the
fluid, in order to reach said preset purification value.
38. A household apparatus according to claim 1, wherein said
control means operate for regulating the electric current
circulating in said cell and/or prevent an electric current
exceeding a preset limit.
39. A household apparatus according to claim 1, wherein said
control means are integrated with, or part of, or connected to the
control system of the household apparatus.
40. A household apparatus according to claim 1, wherein said
control means are programmed for actuating in a diversified manner
said purification or treatment system depending on the operating
cycles of the household apparatus.
41. A household apparatus according to claim 1, wherein said
control means are programmed for controlling the operation of all
actuating means or detecting means of the household apparatus.
42. A treatment or purification method of a fluid, realized in a
household apparatus, of the type in which at least a substance must
be removed from at least a portion of said fluid, in particular a
water softening method, where is provided the use of an
electrochemical, electro-dialysis or electro-osmosis cell, with a
positive electrode and a negative electrode, and at least a
permeable separation element, comprising: a first type of
separation element, of the ion exchange element type, being
permeable to at least a first substance to be removed from at least
a portion of said fluid, a second type of separation element, of
the ion exchange type, not being permeable to said first substance
and permeable to at least a second substance, a plurality of
channels delimited between said electrodes and/or said separation
elements, first collecting means of a portion of said fluid from
which said substance must be extracted or the fluid to be purified,
second collecting means of a portion of said fluid provide to
receive said first substance or the fluid to be contaminated, means
in association with at least said first and/or second collecting
means for detecting the features of at least a part of the fluid,
circulation means for obtaining a substantially closed circuit
and/or a continuous circulation of said fluid between said
collecting means and said channels of said cell for purifying at
least a part of the fluid, controlling means comprising at least
one electronic controller, and receiving information from said
means for controlling at least said cell and the fluid circulation
until a preset purifying value of said fluid is reached.
43. A method according to claim 42, wherein said means in
association with at least said first and/or second collecting means
for detecting the features of at least a part of the fluid,
comprise: first sensing means located in said first collecting
means for detecting the features of at least a part of the fluid,
and/or second sensing means located in said second collecting means
for detecting the features of at least a part of the fluid.
44. A method according to claim 42, comprising dosage and
collection in a first containers of a first quantity of said fluid
or fluid to be purified, from which said first substance must be
extracted.
45. A method according to claim 42, comprising dosage and
collection in a second container of a second quantity of said fluid
or fluid to be contaminated, to which said first substance has to
be added
46. A method according to claim 42, comprising detection of
features or of the purification value of the fluid treated by said
cell.
47. A method according to claim 42, wherein said fluid comes from a
water main connected to the household apparatus, said fluid being
in particular water.
48. A method according to claim 42, comprising detection of
features of the fluid supplied to said collecting means and/or to
said cell and/or of the inlet fluid to the household apparatus.
49. A method according to claims 45 wherein said second quantity of
fluid is calculated depending on the contents of said first
substance in said inlet fluid to the household apparatus and/or in
said fluid to be contaminated.
50. A method according to claim 42, wherein the fluid will not be
purified should the contents of said first substance in said
utilized fluid be lower than said preset purification value.
51. A method according to claims 44 wherein said fluid to be
purified and said fluid to be contaminated are pre-treated and/or
filtered and/or disinfected and/or decanted before flowing in said
cell or before the purification process.
52. A method according to claims 44 and wherein said fluid to be
purified is circulated in first channels of said cell and said
fluid to be contaminated is circulated in second channels of said
cell.
53. A method according to claim 42, wherein the fluid flow-rate
during said continuous circulation is constantly maintained at
preset values.
54. A method according to claim 42, wherein the fluid flow-rate
during said continuous circulation is changed.
55. A method according to claim 52, wherein said fluid flows
through said channels from the bottom upwards.
56. A method according to at least one of claim 42, wherein said
continous circulation is performed for a preset period of time.
57. A method according to claim 42, wherein the duration of said
continuous circulation is variable according to preset or
calculated values, in particular depending on the contents of said
substance in said inlet fluid.
58. A method according to claim 42, wherein said preset
purification value is variable in the frame of one same operation
cycle of the household apparatus, in particular according to the
function that said purified fluid has to perform during the
cycle.
59. A method according to claim 44, wherein the same fluid to be
contaminated is used for a plurality of purification processes,
i.e. for treatment purposes of a plurality of said first fluid
quantites.
60. A method according to claim 44, wherein upon reaching said
preset purification value, the purified fluid is conveyed to a tub
of the household apparatus, in particular for executing hot wash
steps.
61. A method according to claim 45, wherein the contaminated fluid
is discharged from the household apparatus without being utilized
by the latter.
62. A method according to claim 45, wherein the contaminated fluid
is utilized during an operation cycle of the household
apparatus.
63. A method according to claim 62, wherein the contaminated fluid
is conveyed to a tub of the household apparatus, in particular for
executing cold wash steps.
64. A method according to claim 42, comprising counter-current
washing of said channels and/or said electrodes.
65. A method according to claim 42, wherein said voltage and/or
current has a constant value.
66. A method according to claim 32, wherein said voltage and/or
current has a value.
67. A method according to claim 42, wherein the supply procedures
of said electrodes are changed in the frame of one same
purification process.
68. A method according to the claim 42, comprising polarity
reversal of said electrodes at regular intervals.
69. A method according to claim 68, wherein said polarity reversal
or a fixed time at the end of each single purification process.
70. A method according to the claim 68, comprising polarity
reversals during one same purification process.
71. A method according to claim 52, comprising functions reversal
of at least said first and second container (P,S), so as to collect
said fluid to be contaminated in said first container and collect
said fluid to be purified in said second container, and that the
fluid to be contaminated is circulated in said first channels and
the fluid to be purified is circulated in said second channels.
72. A method according to claim 42, wherein the times and/or the
values of the electric supply voltage of said electrodes are
variable depending on the conductivity degree of the fluid, in
order to reach said preset purification value.
73. A method according to claim 42, comprising suction of the gases
produced inside said cell.
74. A method according to claim 68, comprising detection of the
room temperature in proximity of said cell and/or of the fluid to
be purified, in order to change the operation parameters of said
cell.
75. A treatment or purification system of a fluid for household
apparatus, according to claim 1.
76. A control system for household apparatus, according to claim
1.
77. A control method for household apparatus, according to claim
42.
78. A purification or treatment system of a fluid, comprised in a
household apparatus, of the type in which at least a substance must
be removed from at least a portion of said fluid, in particular a
water softening system, said system comprising at least an
electrochemical, electro-dialysis or electro-osmosis cell, with a
positive electrode and a negative electrode, and at least a
permeable separation element, comprising: a first type of
separation element, of the ion exchange element type, being
permeable to at least a first substance to be removed from at least
a portion of said fluid, a second type of separation element, of
the ion exchange type, not being permeable to said first substance
and permeable to at least a second substance, a plurality of
channels delimited between said electrodes and/or said separation
elements, first collecting means of a portion of said fluid from
which said substance must be extracted or the fluid to be purified,
second collecting means of a portion of said fluid provide to
receive said first substance or the fluid to be contaminated, means
in association with at least said first and/or second collecting
means for detecting the features of at least a part of the fluid,
circulation means for obtaining a substantially closed circuit
and/or a continuous circulation of said fluid between said
collecting means and said channels of said cell for purifying at
least a part of the fluid, controlling means comprising at least
one electronic controller, and receiving information from said
means for controlling at least said cell and the fluid circulation
until a preset purifying value of said fluid is reached.
79. A treatment or purification system acacording to claim 78,
wherein said means in association with at least said first and/or
second collecting means for detecting the features of at least a
part of the fluid, comprise: first sensing means located in said
first collecting means for detecting the features of at least a
part of the fluid, and/or second sensing means located in said
second collecting means for detecting the features of at least a
part of the fluid.
Description
[0001] The present invention relates to a household apparatus using
a fluid, comprising a purifying system, in which at least a
substance must be removed from said fluid, in particular a water
softener system.
[0002] A system as above is described with reference to the FIGS.
1-3 of WO 00/64325. In this system an electro-deionising cell is
provided, which has two electrodes between which anionic and
cationic membranes type delimit a plurality of first and second
channels containing water softening resins; the water to be
softened flows in the first channels, whereas the water flowing in
the second channels will regenerate the above resins, i.e. receive
the ions causing calcareous formation, which is removed by the
resins from the water flowing in the first channels.
[0003] The solution described in WO 00/64325, though averagely
reliable, has some practical drawbacks of practical type, due to
the system operation.
[0004] In particular, the system described in WO 00/64325
substantially provides an "immediate" softening process, in the
sense that the water to be softened is treated as it is gradually
supplied from the water main, with simultaneous resins
regeneration.
[0005] A solution as above requires the use of a cell of
considerable dimensions due to the instantaneous treatment required
of a significant quantity of water; these big dimensions of the
cell make its housing difficult inside the tiny spaces available in
a household apparatus; a further problem related to the big
dimensions of the cell is that also the membranes and electrodes
used inside it will have significant dimensions, entailing a high
industrial manufacturing cost.
[0006] On the other hand, the use of an "immediate" softening and
regenerating system as described above, with a small cell, also
entails a proportional flow-rate reduction of a few litres per
hour.
[0007] This condition does not only request a much longer time for
filling the appliance tub, but abnormal operating conditions were
also noticed; in fact, the reduced flow-rate in the event of very
hard water will actually create particular chemical conditions
causing a high precipitation of the chemical compounds inside the
cell, such as a high acidity and/or basicity, which causing the
consequent permanent deterioration of the cell membranes in
time.
[0008] In this frame, it is the object of the present invention to
solve the above drawbacks and provide further new efficient
embodiments of a system for purifying a fluid used in a household
apparatus, in particular for water softening.
[0009] In order to reach this purpose, it is the object of the
present invention to provide a household apparatus using a fluid,
comprising a purifying system in which at least a substance must be
removed from said fluid, in particular a water softener system,
incorporating the features of the annexed claims, which form an
integral part of the present description.
[0010] Further objects, features and advantages of the present
invention will become apparent from the following detailed
description and annexed drawings, which are supplied by way of non
limiting example, wherein:
[0011] FIG. 1 shows the basic diagram of a first possible
embodiment of a water softening system according to the present
invention, for non limiting application to a washing machine, in a
first operating condition;
[0012] FIG. 2 shows a detail of the system of FIG. 1;
[0013] FIG. 3 shows the system of FIG. 1 in a second operating
condition;
[0014] FIG. 4 shows the system of FIG. 1 in a third operating
condition;
[0015] FIG. 5 shows the system of FIG. 1 in a fourth operating
condition;
[0016] FIG. 6 shows a first possible embodiment of the system of
FIG. 1;
[0017] FIG. 7 shows a second possible embodiment of the system of
1;
[0018] FIG. 8 shows a third a possible embodiment of the system of
FIG. 1.
[0019] In FIG. 1, reference 1 indicates schematically a treatment
container or washing tub of a washing machine according to the
present invention, comprising a system for treating or purifying a
fluid, of the type in which at least a substance should be removed
from at least a portion of the fluid; in the example, the above
system is provided for reducing water hardness.
[0020] The washing machine represented is a standard dishwasher,
with wash fluid sprayers arranged in the washing tub 1, consisting
of two common rotary sprayer arms 2 and 3; reference 4 indicates a
common washing or circulation pump, for sucking the wash fluid from
the bottom of the tub 1 and convey it through an appropriate duct 5
to the arms 2 and 3.
[0021] Reference 6 indicates a common discharge pump, for
discharging the fluid used in the tub; to this purpose, the pump
outlet 6 is connected to a suitable discharge hose 7.
[0022] Reference 8 indicates a water intake duct from a household
water main, on which an inlet valve 9 is provided; the valve 9 is a
common valve controlled by the machine control system,
schematically represented with SCE in FIG. 2, ensuring clean water
intake for washing within the times and according to appropriate
procedures; on the duct 8 may be fitted sensing means,
schematically indicated with MS, being apt to detect some operating
parameters of the inlet water, such as water flow-rate, pressure,
conductivity or resistivity, temperature, hardness degree, acidity
degree or pH of the water, etc.
[0023] The duct 8, downstream of the valve 9, has a so-called
air-break or backflow device indicated with AB; downstream of the
air-break AB, the duct 8 branches off in two separate ducts 8A and
8B, which feed a first tank P and a second tank S, respectively.
Along the above ducts 8A and 8B, upstream the inlets of the tanks P
and S, respective common valves 10 and 11 are provided, which are
controlled by the machine control system.
[0024] The tanks P and S comprise each one appropriate sensing
means; the sensors indicate with SP1 and SS1 are provided for
detecting "quantitative" features of the water in the tanks P and
S, such as flow-rate, pressure, level, temperature, etc., whereas
the sensors SP2 and SS2 are provided for detecting "qualitative" or
electrochemical features of the water in the tanks P and S, such as
conductivity or resistivity, hardness degree, acidity degree or pH,
etc.
[0025] The tank P has a first outlet P1, in communication with the
suction branch of a commonly known pump 12 controlled by the
machine control system, and a second outlet P2, in communication
with a water inlet duct 13 into the tub 1 of the machine; a common
valve 14 controlled by the machine control system, operates on this
outlet P2 of the tank P; the tank P also comprises a suitable
filter indicated with PF in line with the outlet P1.
[0026] It should be noticed how the lower section of the tank P is
in the form of a "trap", e.g. with a portion of reduced section;
the outlet P2 allows water downflow substantially from the lowest
point of the tank P, whereas the outlet P1 allows water downf low
substantially above the trap portion previously mentioned; the
function of this special lower section configuration of the tank P
will be further described.
[0027] Also the tank S has two outlets, the first one indicated
with S1 communicating with the suction branch of a common pump 15
controlled by the machine control system; the second outlet of the
tank S indicated with S2 communicating with the above water inlet
duct 13 to the tub 1 of the machine; a common valve 16 controlled
by the machine control system operates on the outlet S2 of the tank
S; also the tank S comprises a suitable filter indicated with SF in
line with the outlet S1; also the lower section of the tank S is in
the form of a "trap" so that the outlet S2 allows water downflow
substantially from the lower point of the tank S, whereas the
outlet S1 allows water downflow substantially above the trap
portion for the purposes to be further described.
[0028] It should be noticed how the various valves of the above
system are electric and normally closed types; therefore, for the
purposes of this description, they are assumed in their closed
condition, save when otherwise specified.
[0029] Reference 20 indicates a decalcifier or softener device in
its whole of the type electrochemical or electro-dialysis or
electro-osmosis cell, which has two inlet ducts 21 and 23 in its
lower section and two outlet ducts 22 and 24 in its upper
section.
[0030] The inlet duct 21 is hydraulically connected to the delivery
branch of the pump 15, whereas the inlet duct 23 is hydraulically
connected to the delivery branch of the pump 12; the outlet duct 22
is hydraulically connected to the tank S or duct 8B in a location
downstream the valve 10; the outlet duct 24, vice-versa, is
hydraulically connected to the tank P or duct 8A in a location
downstream the valve 11.
[0031] The decalcifier 20 may comprise appropriate sensing means,
not represented in the figures, for detecting "quantitative" and/or
"qualitative" operating parameters, such as the flow-rate,
pressure, conductivity or resistivity, temperature, hardness
degree, acidity degree or pH of the water flowing in and out of the
decalcifier 20, etc.
[0032] FIG. 2 is showing schematically the decalcifier 20 more in
detail, which comprises a body 20A, e.g. made from thermoplastic
material.
[0033] Inside the body 20A, respective electrodes are arranged on
both lengthwise ends, in particular a positive electrode or anode
20B and a negative electrode or cathode 20C. By mere way of example
the electrodes 20B and 20C can be made from titanium and have a
platinum coating or other noble metal oxides (such as ruthenium or
iridium).
[0034] Appropriate ion exchange membranes of common type are
arranged between the anode 20B and cathode 20C, for delimiting a
set of channels inside the body 20A. In particular, reference 20D
indicates permeable membranes to the anions, i.e. the ions having
one or more negative electric charges, which migrate towards an
anode during an electro-dialysis process or anyway owing to an
electric current or voltage; reference 20E, on the contrary,
indicates permeable membranes to the cations, i.e. the ions having
one or more positive electric charges, which migrate towards a
cathode during electro-dialysis or owing to an electric current or
voltage.
[0035] As it will be noticed, the membranes 20D are alternated to
the membranes 20E, for delimiting inside the body 20A:
[0036] two "electrodes channels", indicate with CE1 and CE2,
extending in the non limiting example of FIG. 2 between the anode
20B and a membrane 20D, and between the cathode 20C and a membrane
20E, respectively;
[0037] at least a "concentrate channel" CC, delimited by a membrane
20E and a membrane 20D; in the example two channels CC are
provided;
[0038] at least a "purifying channel", indicates with CP, extending
between a membrane 20D and a membrane 20E; the example provides
three channels CP.
[0039] In the non limiting example of FIG. 2, the electrodes
channels CE1 and CE2 and the concentrate channels CC are
interconnected in parallel to the inlet duct 21 and outlet duct 22
both at their lower and upper ends, respectively, whereas the
purifying channels CP are connected in parallel to the inlet duct
23 and outlet duct 24 both at their lower end and upper ends,
respectively.
[0040] Operation of the dishwashing machine described above is as
follows.
[0041] FIG. 1 illustrates a condition of water inlet from the water
main; this step may be for example the first water inlet step
provided by a standard wash cycle of the machine incorporating the
invention.
[0042] To this purpose, the machine control system, schematically
indicated with SCE in FIG. 2, will open the valves 9, 10 and 11,
keep the valves 14 and 16 closed and maintain the pumps 12 and 15
deactivated; so, the water come from the water main can flow in the
duct 8, overcome the air-break AB and flow then to the tanks P and
S through the ducts 8A and 8B.
[0043] It should be noticed how the water portion unable to cross
the air-break AB is commonly conveyed inside into the tub 1; this
water will not be softened, but it is quite a small quantity and
such not to affect the washing quality negatively; anyway, in
alternative, the water unable to overcome the air-break AB may be
commonly conveyed to one of the tanks P or S.
[0044] The valves 9, 10 and 11 are closed after filling the tanks P
and S with enough water for the purposes to be further described;
it should be noticed how water dosage in the tanks P and S and the
relevant closure of the valves 9-11 can be obtained through any
common technique; as said, each tank P and S can be fitted with
respective level sensing means (e.g. pertaining to SS1 and SP1),
such as a floating sensor, a pressuremeter or preferably a turbine
flowmeter, of common make and operation.
[0045] When filling the tanks P e S, the control system also
provides for controlling the water features through the sensors
SS2, SP2, which are apt to detect water conductivity or resistivity
and/or hardness and/or acidity or pH, etc., establishing
automatically the quantity of water required and whether it should
be softened or discharged directly from the tanks P and/or S into
the washing tub.
[0046] In particular, the quantity of water to be filled in the
tank S is automatically changed by the control system
proportionally to the hardness of the water to be treated, i.e. of
the water coming from the inlet of the duct 8.
[0047] Should the water have a hardness exceeding preset limits, it
will have to rest for a certain time, e.g. a few minutes, during
which the likely impurities in the water can decant and deposit in
the lower areas of the tanks P and S having the form of a trap;
these impurities may be sand, iron rests or rust, etc., and are
illustrated in FIG. 1 by the circles with a larger diameter in the
lower section of the tanks P and S (whereas the circles with a
smaller diameter represent the cations, such as calcium and
magnesium, i.e. those ions with a positive electric charge causing
calcareous production).
[0048] Once "decanting" time is over, the machine control system
supplies the pumps 12 and 15.
[0049] Thus, the water in the tank P will flow through the duct 23
into the purifying channels CP of the decalcifier 20 and return to
the tank P through the duct 24, due to the closed valve 11; the
same applies for the water in the tank S, which will flow through
the duct 21 into the electrodes channels CE1 and CE2 and
concentrate channels CC of the decalcifier 20 and return to the
tank S through the duct 22, due to the closed valve 10.
[0050] The flow speed in the internal channels of the decalcifier
is preferably maintained constant at a predetermined value; in
alternative, the flow speed value can be calculated from time to
time by the control system based on measurements performed
according to predetermined algorithms or predefined data tables;
this speed may also change, i a controlled way (steps), during the
various cycle steps of the treatment; in this frame, the control
system will be programmed to change the speed of the pumps 12
and/or 15 or change the flow speed operating on respective
proportional valves or variable flow-rate controllers.
[0051] It should be noticed how the water sucked from the tanks P
and S and sent to the decalcifier 10 is filtered by the filters PF
and SF before being conveyed to the decalcifier 20; the arrangement
of the filters PF and SF, through which the water from the main is
not flowing through immediately (this water being subject to
preventive "decanting"), ensures a minor clogging risk; this risk
is further reduced by the filters PF and SF having significant
dimensions in the available space in the tanks P and S and by the
fact that likely impurities are deposited on the bottom of the
tanks themselves, as previously explained; moreover, suitable means
not represented may be provided in line with the ducts P1 and S1,
such as labyrinth paths being apt to prevent a "eddy" or suction of
the decanted material.
[0052] Simultaneously to the activation of the pumps 12 and 15, the
control system SCE of the machine will supply direct electric
voltage between the anode 20B and cathode 20C of the decalcifier
20.
[0053] Thus, the electric current going through the decalcifier 20
induces the migration of the calcium and magnesium cations
contained in the water flowing in the purifying channels CP,
towards the cathode 20C, through the permeable membranes to the
cations 20E; whereas due to the electric current the anions will
migrate towards the anode 20B, through the permeable membranes to
the anions 20D.
[0054] In this situation, illustrated in the FIGS. 2 and 3, the
permeable membranes to the cations 20E hinder the anions from
migrating towards the anode 20B and the permeable membranes to the
anions 20D hinder the cations from migrating towards the cathode
20C. Therefore this process leads to a progressive reduction of
cations concentration inside the channels CP; in particular, for
the purposes of the present invention, the calcium and magnesium
cations in the purifying channels CP will gradually transfer into
the concentrate channels CC and channel CE2 of the cathode 20C.
[0055] Therefore, as it will be noticed, according to the present
invention, the electrochemical or electro-dialysis softening
process is obtained with water ricirculation inside the decalcifier
20; this to establish a progressive hardness reduction of the water
contained in the tank P, flowing in the channels CP and,
conversely, cause a progressive hardness increment of the water in
the tank S, which flows in the channels CE1, CE2 and CC.
[0056] According to the above embodiment, water inlets 21 and 23 in
the decalcifier 20 are preferably located in its lower section, so
that the water will flow through the various inner channels CE1,
CE2, CC and CP from the bottom upwards.
[0057] It should also be considered how the above decalcification
may cause gas production (hydrogen, oxygen, and so on), e.g. in
line with the electrodes 20B and 20C; as a result, should the above
channels be supplied from the top downwards, gas stagnation or gas
"bags" may form in the ricirculation hydraulic circuit, being
capable of affecting system operation negatively. The suggested
solution, i.e. water flowing through the various inner channels
CE1, CE2, CC and CP from the bottom upwards, will prevent such a
drawback; moreover, it is preferable to have the flows in the
various channels P and S in the same circulation direction, i.e.
not counter-current.
[0058] The softening process, and consequently water circulation
between the tanks P and S and the decalcifier 20, can be timed,
i.e. for a preset time, or its duration can be programmed for a
certain number of water passes through the decalcifier 20.
[0059] Advantageously, this time or preset number of passes can
change depending on the hardness degree of the inlet water to the
machine, being detected e.g. by the sensing means MS.
[0060] In this frame, should for instance the hardness degree of
the inlet water to the duct 8 measured through the sensing means
MS, be higher than a preset threshold but of limited value, the
machine control system programmed to that purpose will submit the
water to a time or number of softening passes relatively low,
vice-versa, should hardness be high, then the water treatment time
would be longer; anyway, in the above example the treatment will
continue until the control system detects through the sensing means
SS2, SP2 that the preset or calculated value has been reached.
[0061] The machine control system can also be advantageously
programmed to avoid execution of the softening process, should the
hardness degree of the inlet water measured by the sensing means MS
be low enough or below a preset value.
[0062] According to an advantageous embodiment of the present
invention, duration of the softening process with continuous
ricirculation may depend on the achievement of a determined degree
of water softening; in other words, according to this approach,
water ricirculation and consequently the softening process will go
on until the appropriate sensing means SP, inside the tank P, will
detect a water hardness reduction below a threshold preset or
calculated by the control system.
[0063] The control system SCE comprises at least a microprocessor
or micro-controller, and appropriate memory means, such as RAM,
ROM, PROM, EPROM, EEPROM, etc. These memory means are provided in
particular for containing data tables and/or elaboration programs
for detecting and/or calculating said measurement values or
reference limits, in order to operate the appropriate system
actuators (valves, pumps, etc.).
[0064] Moreover, the washing machine can be fitted with visual
means, such as LED or LCD, and/or data input means, such as
push-buttons or a keyboard, for the machine installer and/or user
to verify and/or modify at least a few operating parameters.
[0065] The above control system may either be integrated or pertain
to the control system of the household apparatus, or operate as an
independent control system interacting with the control system of
the household apparatus, receiving and/or transmitting information
or control signals.
[0066] In addition, the final hardness threshold may be
advantageously changed within one same operation cycle of the
washing machine, according to the function of the softened water
during the cycle itself. In other words, the machine control system
can be programmed for water treatment, by means of the decalcifier
20 and tanks P and S, following a different procedure according to
the wash cycle step to be executed: for instance, a higher residual
hardness of the water used for a pre-wash or intermediate rinse
will be accepted compared to the hardness degree of the water being
used for a strict wash step or final rinse.
[0067] Thus, time can be further saved for both the treatment and
total operation cycle of the washing machine, as well as also for
the quantity of water required in the waste tank S.
[0068] As mentioned above, the quantity of water required in the
tank S, for correct operation without precipitations due to
excessive concentration, depends on the quantity of waste substance
actually removed from the water contained in the tank P.
[0069] In the instance of a water treatment for the purposes of a
pre-wash, intermediate rinse or low temperature cycle, or anyway
any time a higher residual hardness than for the other cycle steps
is assumed acceptable, the quantity of waste removed will be
smaller and consequently also the water contained in the tank S can
be less.
[0070] As previously explained, the quantity of water to be filled
in the tank S is automatically changed by the control system
proportionally to the hardness of the water to be treated, i.e. in
the instance of a high hardness of the water to be treated, a
higher quantity of water will be filled in the tank S, so as to
avoid an excessive concentration of calcium or other waste
elements, with a consequent precipitation and clogging risk.
Vice-versa, in the instance of a low hardness of the water to be
treated, a smaller quantity of fluid will be filled in the tank S,
with a consequent water saving; in fact, filling an equal quantity
of water in the tank P, the quantity of water filled in the tank S
will be different, but such to fulfil the functions without any
waste excess and without the risk to have an final waste product
excessively concentrated.
[0071] At any rate, when the decalcifying process is terminated,
the control system will stop electric voltage supply between the
electrodes 20B and 20C and power supply to the circulation pumps 12
and 15; as a result, the tank P will contain purified or softened
water, whereas the tank S contains water with an incremented ions
contents (cations and anions), also with calcium and magnesium
cations contributing to hardness production.
[0072] As it will be noticed, the above hydraulic system is so
designed that at least the various channels of the decalcifier 20
are practically always filled with water, as illustrated in FIG. 4,
also after shutting off the pumps 12 and 15; thus, a certain
quantity of water remains inside the decalcifier 20 also during its
rest or inactive steps, warranting the immersion of the membranes
20D and 20E in the water, or just maintaining them humid to avoid
their drying up and deterioration; in the example illustrated in
the figures, this purpose is obtained through a special
configuration and arrangement of the inlet ducts 21 and 23 with
respect to the outlet ducts 22 and 24, the first ones actually
providing a siphon effect (on the other hand, the same purpose may
be obtained using any other known technique, such as providing
suitable valves on the above inlet/outlet ducts).
[0073] At the end of the softening process described above, the
control system of the machine will instruct the valve 14 to
open.
[0074] As a result, the water contained in the tank P can flow into
the duct 13, and from it to the washing tub 1 of the machine, as
illustrated in FIG. 4; it is noticed that the first portion of this
water reaching the tub 1 has the impurities eventually deposited on
the bottom of the tank P, which will be trapped by a further
filtering system of the apparatus or anyway prove ineffective for
the typical dishwasher operation.
[0075] The crockery are then washed according to the known
procedures, through the pump 4, the circuit 5 and the sprayer arms
2 and 3, followed by a discharge of the fluid utilized in the tub 1
activating the pump 6.
[0076] To this purpose the control system SCE is obviously
programmed for supervising the typical operation of a washing
machine, i.e. controlling water intake in the tub, as explained
above, water heating through a common heater if required,
activating the washing or circulation pump 4, activating the
discharge pump 6, dispensing the washing agents and/or rinse
additives, and so on.
[0077] Once the above discharge is over, the control system of the
machine will request a new water intake from the water main, for
performing the second stage of the wash cycle.
[0078] In a non limiting example of the operation cycle, the
control system of the machine will instruct the valves 9 and 11 to
open, while the valves 14 and 16, as well as the valve 10 remain
closed; during this step both pumps 12 and 15 are deactivated.
[0079] Thus, the water from the water main can flow through the
duct 8, overcome the air-break AB and further to the tank P through
the duct 8A; it should be noticed that the water used for softening
purposes in the previous cycle step is contained in the tank S.
[0080] When the tank P is filled with the required quantity of
water, the valves 9 and 11 are closed, and the water supplied in
the tank P allowed to "decant" as described above; thereafter the
control system of the machine will activate the pumps 12 and
15.
[0081] Again, through the duct 23 the water in the tank P flowing
in the purifying channels CP and returned to the tank P through the
duct 24 due to the valve 11 being closed; the water in the tank S
flowing through the duct 21 in the electrodes channels CE1 and CE2
and in the concentrate channels CC, and will finally return to the
tank S through the duct 22 due to the valve 10 being closed.
[0082] Following activation of the pumps 12 and 15, the control
system SCE of the machine will simultaneously supply direct
electric voltage between the anode 20B and the cathode 20C of the
decalcifier 20, for obtaining water softening contained in the tank
P according to the procedures described above.
[0083] This softening process under constant ricirculation causes a
gradual hardness reduction of the water of the tank P flowing in
the channels CP; through the same process, on the other hand, is
obtained a further gradual hardness increase of the water of the
tank S flowing in the channels CE1, CE2 and CC.
[0084] When the softening process is ended, the control system will
stop supply of the above electric voltage between the electrodes
20B and 20C and power supply to the circulation pumps 12 and 15;
therefore, the tank P will contain softened water, whereas the
water in the tank S is further loaded with calcium and magnesium
cations.
[0085] The control system of the machine provides then to open the
valve 14 so that the water of the tank P can flow in the duct 13
and reach the tub 1 of the machine; crockery washing will be
executed as per the previous step according to common
procedures.
[0086] The same water intake and softening process as previously
described, is repeated for all the steps provided by the wash
cycle.
[0087] From the above it is clear how according to the suggested
solution, the same water originally supplied in the tank S is used
for performing several softening steps of the water gradually
supplied in the tank P; the solution according to the invention
will ensure a substantial reduction of the waste water from the
softening process.
[0088] In alternative, the tank S may be emptied and filled again
with the water from the main, with each emptying and filling cycle
of the tank P; in this instance the quantity of water supplied
every time to the tank S will be less compared to the example
previously described, but capable of receiving the substances
removed from the fluid contained in the tank P, without any
excessive concentration or precipitations.
[0089] The water contained in the tank S, and used in the softening
processes occurring during the various water supplies from the
water main, can be discharged from the machine at the end of the
wash cycle. According to this embodiment, the control system of the
machine is programmed for instructing the opening of the valve 16
after the discharge following the last step provided by the wash
cycle; so the contents of the tank S can flow through the duct 13
to the tub 1 as illustrated in FIG. 5 and be discharged through the
discharge pump 6.
[0090] A further advantageous embodiment of the invention, on the
other hand, the water contained in the tank S may be maintained
inside the tank itself or inside the washing tub at the end of a
wash cycle, for its further use during a subsequent utilization of
the apparatus or a step of the subsequent wash cycle.
[0091] According to this embodiment, the contents of the tank S may
actually be utilized for executing determined steps provided by a
wash cycle, provided these steps can accept water with a high
hardness degree, such as cycle steps executed with cold water or
water having a lower temperature compared to the threshold of
limestone precipitation (typically, the limestone contained in the
water does not precipitate at temperatures below about 57.degree.
C.). The following is an example of this application.
[0092] It is assumed to be at the start of a subsequent utilization
of the apparatus, i.e. at the start of a wash cycle, with the tank
P being empty and the tank S filled with water, as previously
described (i.e. water used in the previous wash cycle for a
softening process, and having an increased contents of ions or
anyway waste substances).
[0093] After starting a wash cycle, the control system of the
machine opens the valve 16; the contents of the tank S is conveyed
to the washing tub 1 for executing the first cold wash step. As
said, this first step or pre-wash, can be executed using the water
contained in the tank S in spite of its high concentration of
dissolved calcium and magnesium salts from the softening process
previously described; this considering, as said, that,
[0094] this pre-wash step is executed with cold water,
[0095] limestone precipitates only above a certain fluid
temperature threshold,
[0096] pre-wash steps are substantially provided for removing most
of the soil on the crockery mainly mechanically way through the
action of the water jets.
[0097] Once the tank S has been discharged, the valve 16 will close
and the machine execute the cold pre-wash step (should more water
in the tub be eventually required, it may be supplied directly from
the water main).
[0098] The control system of the machine activates the opening of
the valves 9, 10 and 11 simultaneously with the execution of this
pre-wash step, to let fresh water flow to the tanks P and S; once
the required quantity of water has been supplied to these tanks and
the above valves have been closed, the control system of the
machine activates the pumps 12 and 15 as well as voltage supply
between the electrodes 20B and 20C for water softening, as
previously described.
[0099] Once the pre-wash step is over, the fluid in the washing tub
1 will be discharged through the pump 6; subsequently, considering
that also the softening process or water treatment in the tank P is
over, the water contained in that tank will be conveyed to the
washing tub for the second step of the wash cycle, whereas the
water contained in the tank S is kept for subsequent softening
cycles.
[0100] The wash cycle will go on according to the procedures
previously described and reach its starting condition again at the
end, i.e. with the tank P empty and the tank S full, where the
contents of the latter can be utilized for a subsequent operation
of the apparatus, i.e. for a subsequent wash cycle.
[0101] As it will be noticed, according to the suggested
embodiment, also the water enriched with ions or anyway waste
matter, such as calcium and magnesium cations from the softening
process is not discarded; on the contrary, it can be advantageously
utilized for the execution of a step in a subsequent wash
cycle.
[0102] A possible re-use of the waste water from the tank S is also
due to a relatively low ions concentration of the fluid, in
particular compared to the concentration of the water discharge of
commonly known ions exchange softeners, which utilize a water and
sodium chloride solution, or brine for resins regeneration.
[0103] By way of non limiting example, considering a treatment of
water with a hardness of 140 French degrees and a ratio of about
1:3 from the water contained in the tank S to the water contained
in the tank P, respectively, the maximum concentration of the waste
product according to the invention is in the order of a few
thousands p.p.m. (parts per million) of solids dissolved for
total.
[0104] In the instance of classic brine, vice-versa, concentration
is in the order of a few hundreds of thousands p.p.m. (e.g. 10%
brine.fwdarw.100.000 p.p.m; minimum value for resins regeneration);
even considering a subsequent dilution of about 0,2 litres of
regenerating brine in as many 1,5-2 litres wash water of the
resins, concentration of the waste water would anyway be of a few
tents of thousands p.p.m.
[0105] However, in a further possible embodiment, nothing will
hinder using the contents of the tank S for executing an operative
step of the same cycle in which the ions enriched water, of which
the tank S, has been produced.
[0106] A wash cycle is assumed by way of example, in which the last
two steps consist of a cold rinse and a hot rinse.
[0107] In this instance, before starting the above cold rinse, the
tank S is full and the tank P is empty; the control system of the
machine provides to execute a water intake from the water main for
filling the tank P according to the above procedures; subsequently,
the water contained in the tank P will be softened through the
decalcifier 20, as previously described
[0108] Once the softening process is ended, the contents of the
tank S can be conveyed to the tub 1 for executing the cold rinse
step, which will end with the discharge of the rinse fluid in the
sewage system through the pump 6 and hose 7; following this
discharge, the water contained in the tank P will be conveyed to
the tub 1 where it is heated for the hot rinse step, also ending
with the relevant discharge of the rinse fluid in the sewage
system.
[0109] Therefore, also in this instance the water contained in the
tank S can be used for executing a wash cycle step without being
wasted, and at cycle end both the tanks P and S will be empty.
[0110] Alternatively, in the above example, the contents of the
tank S may be conveyed immediately to the tub 1, supplying both the
tank P and tank S with fresh water from the main; thus, the above
cold rinse step can be executed simultaneously with the softening
operations, saving time.
[0111] FIG. 6 shows schematically a possible embodiment of the
present invention; in this figure the same reference numbers of the
previous figures are used for indicating technical equivalent
elements.
[0112] In the embodiment of FIG. 6, the valves 10 and 11 of the
previous figures are replaced by three-way valves or deviators 10A
and 11A, each one of them with:
[0113] a first way X, connected to the relevant duct 8B or 8A,
acting as the valve inlet;
[0114] a second way Y, connected to the relevant tank inlet S or P,
acting as the valve outlet;
[0115] a third way Z, connected to the relevant outlet duct 22 or
24 of the decalcifier 20, acting alternatively as the valve inlet
or outlet, as further described.
[0116] Moreover, in the example of FIG. 6 the pumps 12 and 15 have
not a tight sealed impeller (as usual in the instance of some
discharge pumps for washing machines).
[0117] Operation of the machine schematically illustrated in FIG. 6
is as follows.
[0118] When supplying the water from the main, the control system
causes the valve 9 to open, whereas both valves 10A and 11A are
controlled for their inlet water from the relevant X way flow out
through the Y way only.
[0119] Thus, water can reach the tanks S and P, which are filled
with water for the purposes described above, i.e.
[0120] softening process through the decalcifier 20, with water
ricirculation through the pumps 12 and 15;
[0121] use of the softened water in the tank P for the execution of
the relevant wash cycle steps;
[0122] direct discharge of the water with incremented hardness from
the tank S in the sewage system, or its use for executing at least
a wash cycle step.
[0123] In the suggested embodiment, the control system of the
machine is programmed for obtaining a counter-current wash both of
the electrolytic cell forming the decalcifier 20 and of the filters
SF and/or PF.
[0124] Accordingly, at a time when both the tanks P and S are
empty, the control system of the machine will provide to:
[0125] open the valve 9;
[0126] control the valves 10A and 11A for their inlet water from
the relevant X way flow out through the relevant Z way only;
[0127] eventually open the valves 16 and 14 (water may remain in
the tanks for subsequent steps).
[0128] Thus, the inlet water flow can reach inside the decalcifier
20 through its outlet ducts 22 or 24 and flow counter-current in
the various channels CE1, CE2, CC and CP; water can then flow out
of the decalcifier through its inlet ducts 21 and 23, flow in the
pumps 15 and 12, then reach the tanks S and P, hitting the filters
FS and FP counter-current; due to the valves 14 and 16 being open,
the water containing likely impurities to be removed
counter-current from the filters FS and FP can further reach the
washing tub 1 for discharge from it through the pump 6.
[0129] Dosage of the water used for the above counter-current
washing of the decalcifier 20 and filters FS and FP can be timed
(opening the valves 9, 10A, 11A, 14 and 16 for a preset time) or
using a common turbine flow-meter; at any rate, this quantity of
water is a small one and the above counter-current washing will
take place with small frequency to avoid that the likely impurities
contained in the water from the main may cause any risks for the
system (e.g. the counter-current washing may be executed once each
wash cycle or once every "n" wash cycles of the machine).
[0130] Moreover, in a further possible embodiment, the pumps 12 and
15 may also be directional pumps, i.e. with the motor capable of
inverting the rotary direction of the relevant impeller; in this
event, by the opportunity of the above counter-current wash step
the control system will operate the pumps with a rotary direction
opposite to the direction for water circulation during
softening.
[0131] On the other hand, a self-cleaning pre-filtering system for
the water supply from the main (such as mechanical, magnetic or
electromagnetic), may be advantageously provided instead of or in
addition to the filters PF and/or SF, upstream the tanks P and
S.
[0132] FIG. 7 shows schematically another possible embodiment of
the present invention; it should be noticed that also in this
figure the reference numbers of FIGS. 1-5 are used for indicating
technical equivalent elements.
[0133] The embodiment of FIG. 7 provides a collecting tank AC
upstream the valve 16, having an outlet communicating with the
water inlet duct 13 to the tub 1; a solenoid valve 17 of common
type and operation is provided on this outlet of the tank AC,
controlled by the control system of the machine.
[0134] In main line, operation of the machine illustrated in FIG. 7
is alike the one previously described with reference to the FIGS.
1-5; the only difference being that when emptying the tank S, the
water contained in it is not discharged directly in the tub, but is
collected in the tank AC; therefore, in main line, in opening
condition of the valve 16, the valve 17 will remain closed.
[0135] The tank AC may be provided for instance in those cases
where the maximum quantity of water that can be contained in the
tank S is not enough for executing a wash cycle step. By way of a
specific example, it is assumed to have both tanks S and P empty at
the end of a wash cycle, whereas the tank AC is full.
[0136] At the beginning of the following wash cycle, the tanks P
and S are filled with new water according to the procedures
previously described; therefore, the water supplied from time to
time in the tank P is softened and is used for executing the
various wash steps, whereas the water initially supplied to the
tank S is used for softening the water utilized in the course of
such steps.
[0137] Before the last cold rinse of the cycle, the tank S will be
full, the tank AC will be full and the tank P empty.
[0138] Now, the control system of the machine can open the valves
16 and 17: both the water contained in the tank AC and in the tank
S can be discharged in the tub so as to have a sufficient quantity
of water for executing the cold rinse step.
[0139] During execution of the cold rinse, the control system will
provide for a new filling of the tanks P and S, and softening of
the water contained in the tank P. When the cold rinse and said
softening are over, the contents of the tank S is discharged in the
tank AC, which is filled again; the contents of the tank P,
vice-versa, is discharged in the tub 1 for the final hot rinse
step. Therefore, at cycle end the program is back to its starting
conditions, i.e. empty tanks P and S and full tank AC.
[0140] Obviously, the above description relates to an application
example of the storing tank AC; it is clear for the man skilled in
the art that other operating and capacity combinations are possible
to the tanks S and AC.
[0141] As previously described, in a preferred embodiment, the
quantity of water to be supplied to the tank S is calculated
depending on the hardness degree of the water main, measured by the
special means MS and/or SP2 and/or SS2; in other words, greater is
the hardness degree of the water from the main supplied by the duct
8, the quantity of water supplied to tank S will be greater.
[0142] This approach is useful also in the event of a very hard
water supply from the main, in order to avoid a concentration
excess of calcium and magnesium cations in the water of the tank S.
In other terms, greater is the hardness of the water from the main,
the quantity of calcium and magnesium cations released by the water
of the tank P to the water of the tank S following subsequent
softening processes, will be greater.
[0143] This progressive concentration increase of the calcium and
magnesium cations may cause the "saturation" of the water in the
tank S, i.e. a capacity loss of the water to receive further
cations leading to calcareous formation and making further
softening processes useless after the "saturation" has been
reached.
[0144] Therefore, in this frame, the quantity of water to be filled
in the tank S will be established by the control system of the
machine, right in order to avoid the above "saturation" following
the softening processes to be made using that water.
[0145] For the same reason it is also clear how the solution
comprising calculation of the quantity of water to be filled in the
tank S depending on the hardness degree of the water main is useful
also in order to avoid an excessive water waste, when its initial
hardness is relatively low.
[0146] Therefore, from the above it can be guessed how the quantity
of water that can be filled in the tank S is not a fixed one, but
may be variable; in this frame, the provision of a storing tank
like the one previously indicated with AC can be quite useful,
right for the evens where the quantity of water filled in the tank
S is not enough for the execution of a wash cycle step.
[0147] FIG. 8 is illustrating a further possible embodiment of the
present invention, according to which an independent circulation
circuit is provided for a wash solution of the electrodes 20B and
20C of the decalcifier 20, in particular a closed circuit not
requiring a supply from the water main; also in this figure the
reference numbers of the previous figures are used for indicating
technical equivalent elements.
[0148] In the embodiment represented in this figure, the channels
of the electrodes CE1 and CE2 are connected to each other in
parallel and separately with respect to the channel CC, by means of
an inlet header 30A and an outlet header 30B.
[0149] Reference 31 indicates a pump like the ones previously
indicated with 12 and 15, delivery of which is in communication
with the header 30A through a duct 32; the suction branch of the
pump 31, vice-versa, is connected to the outlet header 30B through
a duct 33; a tank 34 can be provided along the duct 33.
[0150] According to the suggested implementation, the above closed
circuit consisting of the channels CE1 and CE2, ducts 32 and 33,
headers 30A and 30B, and pump 31, is provided for circulating a
washing fluid of the electrodes in the channels CE1 and CE2, e.g.
water.
[0151] Moreover, in the embodiment represented in FIG. 8, the
decalcifier 20 provides cationic membranes in line with both the
electrodes channels; in other terms, the decalcifier 20 of FIG. 8
is delimiting:
[0152] two channels of the electrodes CE1 and CE2, extending
substantially from the anode 20B and a cations permeable membrane
to the cathode 20C and from the cathode 20C and a cations permeable
membrane, respectively (in the previous figures, both electrodes
channels CE1 and CE2 are extending on the contrary from the anode
20B and an anionic membrane 20D and from the cathode 20C and a
cationic membrane 20E, respectively);
[0153] at least a "concentrate channel" CC, delimited by a membrane
20E and a membrane 20D; in the represented example three channels
CC are provided;
[0154] at least to "purifying channels", indicated with CP,
extending from a membrane 20D and a membrane 20E; in the
represented example, three channels CP are provided.
[0155] In the suggested implementation, the softening process
occurs substantially with the same procedures previously described,
but adding activation of the pump 31, which causes circulation of
the above wash fluid of the electrodes 20B and 20C in the relevant
closed circuit.
[0156] Thus, during the softening process, some calcium and
magnesium cations migrate in the channel CE2, representing the
negative electrode, from the adjacent channel CP, going through the
cationic membrane separating said channels from each other; thus,
the wash fluid is enriched with these cations.
[0157] Subsequently, during circulation of this fluid through the
pump 31, the calcium and magnesium cations themselves will reach
the channel CE1, representing the positive electrode; as a result,
the cations themselves will be induced to migrate, due to the
electrolytic effect, in the channel CC adjacent to the channel CE1,
going through the cationic membrane separating said channels from
each other; thus, the above calcium and magnesium cations are
removed from the wash fluid of the electrodes, which flow in the
water of the tank S ricirculated by the pump 15.
[0158] Therefore, the above solution prevents an excessive
concentration of calcium and magnesium cations in the closed
circuit of the electrodes wash fluid, without requiring a
replacement of that fluid; as a result, also the quantity of water
in the circuit of the tank S can be smaller compared to the
embodiments of the FIGS. 1-7.
[0159] In a further implementation, the cationic membranes in line
with the electrodes channels CE1 and CE2 are preferably selective
type to the monovalent ions, i.e. apt to hinder bivalent ions such
as calcium and magnesium to go by to said electrodes channels;
thus, in spite of power conduction being slightly affected, the
risk of said bivalent ions (calcium, magnesium, etc.) depositing
inside the electrodes channels is further avoided.
[0160] However, these monovalent cationic membranes allow
circulation of ions, such as hydrogen ions, sodium ions, etc.,
warranting a suitable power circulation between the electrodes CE1
and CE2.
[0161] According to the implementation of FIG. 8, a system can be
advantageously provided for a likely periodic topping up and/or
replacement of the electrodes wash fluid in the closed circuit,
since a small portion of it goes lost due to gas formation
(hydrogen, oxygen, etc.) on the electrodes, due to the electrolytic
process; this top-up and/or replacement system is preferably of
automatic type, and according to procedures being clear for the man
skilled in the art; for instance an hydraulic circuit (not
represented) like the circuits 8B, 10 or 8A, 11 may be provided,
being apt for water intake from the line 8 to the tank 34.
[0162] The control system SCE controling the softening system is
preferably an electronic type, based on the use of a microprocessor
or micro-controller, and fitted with appropriate memory means being
apt to store the operation program of the system itself and the
relevant operating parameters. On the other hand, nothing will
hinder implementing the invention with an electromechanical or
hybrid control system type (i.e. partly electromechanical and
partly electronic).
[0163] As previously mentioned, the control system of the machine
described in the figures is preferably apt to establish the
hardness of the water from the water main arriving from the duct 8,
in order to decide whether to perform the softening process or
supply the water from the main directly to the tub 1, without
treating it through the decalcifier 20.
[0164] As already mentioned above, the control system is also
preferably programmed for calculating the quantity of water
required for optimal operation of the decalcifier 20 based on the
measured hardness of the water from the main and its proportional
supply to the circuit of the tank S, without excessive wastage and
saturation risks. However, nothing will hinder supplying the tank S
with a fixed quantity of water (such to fill the tank S
completely), the contents of which is no longer discharged at every
utilization of the dishwashing machine, but only when salts
concentration in the water pertaining to the tank S becomes
excessive (i.e. after repeated cycles of the dishwasher).
[0165] The last functional feature may be advantageous when a
slight hard water from the main (e.g. 10.degree. F.) has to be
treated and the minimum quantity of water actually required for the
channels CC and eventually CE1 and CE2 (FIGS. 1-7) of the
decalcifier 20 is smaller. In this operating condition, i.e.
slightly hard water, the minimum quantity of water required for
filling the hydraulic circuit alone consisting of pump, hoses and
decalcifier 20 (with minimum level in the tank S), may be by far
higher than the quantity actually required for softening just one
operating cycle of the household apparatus; in this situation, in
fact, concentration of the ions transferred from the circuit of the
tank P to the water of the tank S will be clearly lower than the
saturation and/or precipitation threshold.
[0166] Both systems (proportional or fixed water supply) can in any
case co-exist, under the management of the control system SCE, duly
programmed to that purpose. In such an instance, the control system
may e.g. provide for automatic selection of:
[0167] a first operating procedure, for "slightly hard" water from
the main, with a filled tank S, but utilized for several actuations
of the dishwashing machine, or
[0168] a second operating procedure, for "medium/very hard" water,
with the tank S filled proportionally to the water hardness of the
water main and discharged at any utilization of the machine.
[0169] As to power supply of the electrodes 20B and 20B, the
control system of the machine is preferably programmed for
utilizing predetermined voltage and/or current values, in
particular in order to avoid damaging risks of the membranes inside
the decalcifier 20 over the whole operating field, both for very
high hardness (e.g. over 140.degree. F.) and low hardness (e.g.
10.degree. F.).
[0170] To this purpose, the control system can use a constant
voltage or current feeder set on one preset value, e.g. calculated
on the minimum hardness value according to known formulae, being
anyway apt to warrant the above operation all over the hardness
field.
[0171] In another embodiment, the control circuit may change the
voltage and/or electric current to the electrodes proportionally to
the hardness and/or conductivity of the water of the tanks P and/or
S, by changing it either continuously, or by preset steps, during
the whole softening process; in this instance the use of
predetermined data tables may be provided (e.g. hardness/current
links), contained in special non volatile memories and elaborated
by a microprocessor or micro-controller circuit controlling and
changing also the supplying circuit of the electrodes 20B and
20C.
[0172] Preferably, the control system is programmed in any case to
avoid circulation of a current exceeding a first preset upper limit
in the decalcifier 20 (referred to the maximum current per square
meter or measurement unit of a ion exchange membrane), in
particular when the decalcifier itself is starting softening
operations and both the hardness and electric conductivity values
are high.
[0173] The control system is also preferably apt to avoid
circulation of a current exceeding a second preset lower limit in
the decalcifier 20 (e.g. depending on the decalcifier type and/or
operating parameters), in particular when the decalcifier is at the
end of the softening operations and the hardness has reached the
desired value.
[0174] The control system may also be programmed for diversifying
the supply procedures of the electrodes 20B and 20C within one same
softening process; according to an advantageous embodiment, for
instance, the control system can provide a first supply procedure
for a first treatment step, and a second supply procedure for a
second treatment step, in order to avoid a precipitation risk of
the compounds determining water hardness and/or a damaging risk of
the membranes.
[0175] By way of example, in the first step of the softening
process the electrodes 20B and 20C are supplied with a first
voltage (e.g. 20 Vdv or DV) corresponding to a first high current
(e.g. over 2A or Ampere), up to a preset conductivity value (e.g.
700 .varies.S or microSiemens); now, the electrodes 20B and 20C are
supplied with a second voltage, lower of the previous (e.g. 14Vdc),
corresponding to a second lower current (e.g. about 0,5 A).
[0176] The above increase of the initial voltage and/or current
value is also intended to speed up water treatment, in particular
in case of a high water hardness; this feature allows a reduction
or anyway not to affect negatively the total cycle time of the
washing machine. It should be noticed how the performances and
water treatment times in the decalcifier 20 considerably depend on
the size of the latter (i.e. on the total area of its membranes),
which must be considerably limited for cost reasons. In main line,
a way for improving the performance of the decalcifier 20 would be
to increase the circulating electric current; however, to avoid
damaging risks to the membranes, certain limits cannot be exceed as
explained above.
[0177] On the other hand, another parameter substantially affecting
a possible increase of the above current is the water flow-rate
circulating in the decalcifier 20; in other terms, the higher the
flow-rate, the greater the electric current that may be circulated
between the electrodes 20B and 20C, without risks.
[0178] Back to the previous example, the limit current of 0,5 A may
be established for a precise conductivity value and a precise
flow-rate value; however, the flow-rate is bound to the features of
the circulation pumps and structure of the decalcifier 20, which
should preferably warrant an appropriate through section to avoid
introducing load losses in the system. The decalcifier 20, on the
other hand, should preferably have channels (CP,CC) very thin (e.g.
0,6 to 1,2 mm at the most) between a membrane and the other, in
order to warrant a good current flow, without exceeding in electric
voltage (in view of the specification limits for household
apparatuses).
[0179] Therefore, the above control values must be established
based on the hydraulic features of the system, in particular of the
circulation pumps and likely loss charges introduced by the
structure of the decalcifier 20.
[0180] Therefore, the regulation of the voltage or electric current
supplied to the electrodes 20B and 20C may be performed depending
on the water flow-rate to the channels CE1, CE2 and CC, on one
hand, and on the water flow-rate to the channels CP, on the other;
however, nothing will hinder providing regulating means of the
water flow-rates (e.g. variable flow-rate pumps or proportional
valves), keeping constant the value of the supply voltage to the
electrodes 20B and 20C.
[0181] Also in this instance, changing the flow-rate in the
hydraulic system of the softening system is performed by the
control system, according to measured and/or preset and/or
calculated parameters, for operation optimisation.
[0182] Finally, the control system according to the invention is
preferably programmed to periodically realize a polarity reversal
of the electrodes provided in the electrolytic cell of the
decalcifier 20, as an automatic cleaning means of the membranes for
removing any deposits.
[0183] In a possible embodiment, said polarity reversal may occur
for a fixed time at the end of each softening process (e.g.
equalling 10% of the total treatment time); in these conditions the
water is softened and cleaned in the channels CP where the membrane
surfaces may become encrusted, whereas in the ducts CE1, CE2 and CC
the water has an enriched contents of calcium and magnesium
cations.
[0184] Other operating procedures may also be provided, such as
more polarity reversals during the whole softening process,
according to fixed or variable times based on continuous hardness
measurements of the water from the main, of the water pertaining to
the tank S and of the water pertaining to the tank P, said
measurements being performed through the means MS, SS2 and SP2.
[0185] With reference to the above polarity reversal of the
electrodes 20B and 20C, the softening system may also be conceived
for alternating the functions of the tanks S and P.
[0186] As previously noticed, the tank P is provided in normal
conditions for containing the water to be softened and the tank S
for the waste water of the softening process; however, according to
the suggested implementation, the above polarity reversal of the
electrodes can be provided not just for a portion alone of a
softening process, but rather for its whole duration.
[0187] According to this preferred embodiment for application of
the invention, a few examples previously illustrated are included
and linked separately for simplicity's sake, adding also a reversal
of the hydraulic circuits and/or relevant functions to the above
polarity reversal.
[0188] According to the suggested embodiment, a softening process
as previously described, with the electrode 20B representing the
anode, the electrode 20C the cathode, the tank P collects the water
to be softened and the tank S collects the water in which the
cations of the water of the tank P are migrating, will be followed
by a softening process with reversed polarity and reversed chambers
CC e CP, where the electrode 20B is the cathode, the electrode 20C
the anode, the tank S collects the water to be softened and the
tank P collects the water in which the cations of the water of the
tank S are migrating.
[0189] In this process, after filling the tanks P and S and a
subsequent "decanting" time, the control system of the machine
activates the pumps 12 and 15.
[0190] Thus, the water in the tank P will flow through the duct 23
in the channels CP of the decalcifier 20 and since the valve 11 is
closed, back to the tank P through the duct 24; the same applies
for the water in the tank S, which will flow through the duct 21 in
the channels of the electrodes CE1 and CE2 and in the channels CC
of the decalcifier 20 and since the valve 10 is closed, back to the
tank S through the duct 22.
[0191] Simultaneously to the activation of the pumps 12 and 15, the
control system SCE of the machine will supply direct voltage
between the electrode 20B presently acting as the cathode and the
electrode 20C presently acting as the anode.
[0192] Thus, the electric current through the decalcifier 20
induces the migration of the calcium and magnesium cations, of the
water flowing in the channels CC, to the electrode 20B, through the
cations permeable membranes 20E; vice-versa, the anions will
migrate by virtue of the electric current to the electrode 20C
through the anions permeable membranes 20D.
[0193] Therefore, the cations permeable membranes 20E hinder the
anions from migrating to the electrode 20C and the anions permeable
membranes 20D hinder the cations from migrating to the electrode
20B. This process will lead to a gradual reduction of the cations
concentration inside the channels CC; in particular, for the
purposes of the present invention, the calcium and magnesium
cations in the channels CC are gradually transferred in the
channels CP and in the channel CE1 of the electrode 20B.
[0194] As it will be noticed, also in this instance the
electrochemical softening process or by electro-dialysis is
obtained with water ricirculation inside the decalcifier 20, so as
to cause a gradual hardness reduction of the water contained in the
tank S, flowing in the channels CC, CE1 and CE2 and, conversely,
cause a progressive hardness increase of the water contained in the
tank P flowing in the channels CP.
[0195] At the end of the above softening process, the control
system of the machine will open the valve 16.
[0196] So that, the water contained in the tank S can flow through
the duct 13 to the tub 1 of the machine. The washing of the
crockery is then executed with that water according to common
procedures through the pump 4, circuit 5 and spraying arms 2 and 3;
then the wash fluid is discharged from the tub 1 activating the
pump 6.
[0197] Once discharge is over, the control system of the machine
provides for a new water intake from the water main for executing
the second wash cycle step. The waste water in the tank P can be
utilized for new softening processes, or discharged in the sewage
system or used for wash steps where the use of water with enriched
contents of calcium and magnesium is acceptable, as previously
described.
[0198] In the embodiment suggested, the removal of the deposits or
scaling is favoured by the fact that the flow of the ions and/or
electric current reversal occurs for an extended time, for the
whole time of the softening cycle rather than for a fraction of
it,
[0199] but also the fact that in the chambers with the above
deposits, which correspond to the channels with circulation of salt
enriched water, in the subsequent cycle will be flow the water to
be softened, which is more "cleaner" and suitable to facilitate the
"dissolution" or migration of the deposits.
[0200] It is clear, in this frame, that the operating cycle
sequence of the decalcifier 20 with normal and reversed polarity
will be established depending on the wash cycle steps to be
executed; the same applies for the capacity of the tanks P and
S.
[0201] By way of non limiting example, in a first operating cycle
of the machine, the tank P will contain the water to be softened,
whereas the tank S will contain the water being apt to receive the
ions extracted from the circuit of the tank P; in a second
operating cycle of the machine, the tank S will contain the water
to be softened and the tank P the water being apt to receive the
ions extracted from the circuit of the tank S, and so on
alternating the above cycles.
[0202] The control system is also apt to store appropriate data
related to the last cycle executed, such as the direction of the
electric polarity and/or definition of the tank containing the
softened water, so that the operating conditions may be reversed in
a subsequent wash cycle, days later or after extended periods of
time.
[0203] Finally, it should be noticed how the cell 20 according to
the invention besides its softening capability, i.e. removing the
calcium and magnesium ions causing water hardness, also has a
deionising capacity to purify the fluid treated by all the ions
contained in the solution, such as sodium, potassium, chlorides,
nitrates, etc.
[0204] Evaluation of the amount of ions in a solution is provided
by conductivity, through which all the ions in the solution can be
measured. For instance, waters with the same hardness can have
different conductivity values between them; i.e. a water with a
hardness of 100.degree. F. and no sodium can have a conductivity of
2 mS; another water with a hardness of 100.degree. F. and rich of
sodium will have a conductivity of 3 mS (i.e. a difference of one
mS due to the sodium in the solution). Therefore, it is obvious how
conductivity (intended as the amount of ions) is directly affecting
the electric current flowing through the cell 20: the higher the
quantity of ions, the higher the amount of electric current flowing
between the electrodes, with equal potential difference or voltage
applied.
[0205] Therefore, it is also clear how the times and/or values of
the voltage supplied to the electrodes CE1 and CE2, as required for
reaching a satisfactory preset softening value, to which the water
is considered softened enough, may be different according to the
initial conductivity degree of the water to be treated.
[0206] From the above description the features of the present
invention are clear and also its advantages will be clear.
[0207] Obviously many other changes are possible for the man
skilled in the art to the household apparatus utilizing a fluid,
comprising a purifying system in which a substance must be removed
from said fluid, in particular a water softening system previously
described by way of example, without departing from the novelty
principles of the innovative idea.
[0208] For instance, dosage of the water for crockery washing to be
introduced in the tub 1 can be theoretically obtained through a set
of sequential filling and discharge operations of the tank P or S,
in which case the capacity of the tank may equal a fraction or
portion of the total amount of water required for executing a wash
step in the tub.
[0209] According to an advantageous embodiment of the invention,
the above water filling and softening systems or a portion of them,
may be all or partly integrated in one device; for instance, in
this frame, the air-break AB, the tanks S and P, the likely tanks
AC and/or 31, the decalcifier 20, and the various valves and pumps
described above, along with their relevant associated elements
(sensors, ducts, and so on) may be integrated in one or more units,
e.g. made from thermoplastic material, and assembled inside the
machine cabinet on at least one side of the tub 1.
[0210] The previous means indicated with 12 and 15 may consist of
two single pumps, but nothing will hinder the use of a single
common pump with two impellers; analogous considerations obviously
also apply for the embodiment of FIG. 8, where the means 12, 15 and
31 may consist of one single pump with three impellers.
[0211] A further implementation would be the electrolytic cell 20
fitted with gas sucking and/or collecting means (i.e. hydrogen and
oxygen) for subsequent utilization (such as disinfection,
blanching, etc.) and/or appropriate discharge or abatement.
[0212] According to a further implementation, water filling of one
of the tanks S and/or P may eventually be obtained by overflowing
the other tank with obvious procedures for the man skilled in the
art.
[0213] In the embodiment of FIG. 8, the wash fluid of the
electrodes 20B and 20C may consist of a solution comprising most
soluble anion salts; therefore, in this frame, a nitrates aqueous
solution would be advantageous (such as NaNO.sub.3, KNO.sub.3,
etc.) for ensuring a good conductivity of the solution circulating
over the electrodes, avoiding a chemical combination (e.g.
precipitation) with the cations extracted from the water.
[0214] Another possible embodiment of the invention provides the
use of ions exchange softening resins, in particular cationic
resins, at least inside the channels CP of the decalcifier 20, for
further improving the water softening process.
[0215] Obviously, in this case, for the reasons previously
explained and following application of the above voltage and/or
current between the electrodes 20B and 20C, the calcium and
magnesium cations entrapped by these resins would be led to migrate
in the channels CC and CE2, and provide for regeneration of the
resin efficiency.
[0216] The membranes 20D and 20E may be replaced by appropriate
anionic and cationic resin layers, respectively.
[0217] According to a further implementation, sensing means are
provided being apt to detect the room temperature in proximity of
the decalcifier 20, or directly of the water through the sensors MS
and/or SS2 and/or SP2, in order to change the operating parameters
of the decalcifier 20 depending on such temperature; in main line,
in fact, the higher water temperature, the faster the softening
process.
[0218] According to a further possible implementation, means are
provided, such as an UV lamp not represented, being apt to
disinfect the inlet water from the duct 8 and/or the water filled
in the tanks P, S, 34, in particular in order to avoid such
drawbacks as deposits on the membranes due to a bacterial action;
in this frame, at least a portion of the ducts and/or tanks on
which said UV lamp operates are manufactured from a suitable
transparent material.
[0219] Continuous fluid circulation between the collecting means P
and S and the ducts CP, CE1, CE2, CC of the cell 20 may be ensured
by means of any common technique, i.e. not only with pumps, but
e.g. also with Venturi systems type.
[0220] The purifying system according to the invention has been
previously described with specific reference to water softening,
but it is clear that this system may also find application for
different treatments of the fluid used in a household apparatus;
for instance, the system fitted with membranes of appropriate
features may be utilized for separating the washing agents or soil
from the water previously used for a washing.
[0221] The various systems or implementations previously described,
or portions of them, may obviously be used in different
combinations with each other.
* * * * *