EP1810606A1

EP1810606A1 - Dishwasher with a removable water softener

Info

Publication number: EP1810606A1
Application number: EP06100730A
Authority: EP
Inventors: Marco Signa; Biernatowski Lukasz; Stefano Tavolazzi
Original assignee: Whirlpool Corp
Current assignee: Whirlpool Corp
Priority date: 2006-01-23
Filing date: 2006-01-23
Publication date: 2007-07-25

Abstract

A dishwasher (10) comprises a water inlet system and a water spray system (11) inside a tub. The water inlet system comprises a removable water softener (32) in the form of a cartridge (32b) placed outside the tub so that the user can easily remove and dispose it.

Description

The present invention relates to a dishwasher comprising a water inlet system and a water spray system inside a tub.
It is well known that domestic dishwashers are provided with a water softener that comprises a regenerator for such water softener. This latter is basically a container with a bed of ion-exchanging resins in order to remove the calcium ions from water and replacing them with sodium ions. The regenerator comprises a salt dissolving container linked to the above resin container by means of tubes and valves. All this assembly is quite complex and bulky, therefore leading to some constraints in the dimensions of the tub, and it is expensive as well. Moreover, it is necessary to provide regeneration cycles of the resin (depending on the water hardness) and a periodic loading of salt (NaCl) in the regenerator.
In the last years detergent producers have put on the market new compositions in which the rinse-aid and the softener are included in a single tablet. These new products (usually called 3-in-1 or 4-in-1 tablets) have rendered superfluous in some cases the use of the assembly softener/regenerator, particularly in regions where the water hardness is low. In other regions, where water hardness is medium or high, the use of the above tablets only do not guarantee good performances in term of washing and/or rinsing, since the chemicals contained in the tablets for softening water cannot cope with the full water hardness. In such cases the use of the water softener device (and therefore of its regenerator) has to be adjusted according to the actual water hardness (and to the peculiar tablet used), and this adjustment has the positive consequence of making intervals for regeneration longer. On the other hand it is clear that in these cases the full potential of the softening and regeneration device is not exploited, and sometime (with low water hardness) such device is completely idle.
An object of the present invention is to provide a dishwasher which is economical and which does not present the above problems.
Such object is reached thanks to the technical features listed in the appended claims.
The present invention can be used in all dishwashers but is particularly adapted to be used in the so-called compact dishwashers, that can be located on a kitchen worktop or integrated in a sink and where the inlet of a salt-dissolving container of a regenerator cannot be easily placed in such compact product. Such kinds of dishwashers have also the problem of placing all the components in a limited space, and therefore the dimensional problem of a traditional softener/regenerator is even more stringent. By replacing the traditional combination of softener and regenerator with a disposable water softening filter, it is possible to reduce the space for the dishwasher components (allowing an increase of the volume of the washing chamber or tub) and to have the softener only as an optional component in case the user chooses to adopt the 3-in-1 tablet (when the water hardness is not high). With the term "disposable" we mean an easy removal and replacement of the water softening system, independently on the possible regeneration of the filter itself. When the water hardness is high, the combination of 3-in-1 tablets and of the disposable water softener makes the replacement interval of the softener cartridge sufficiently long in order to reduce the overall cost per washing cycle. If the user chooses to use the usual detergent (and not the 3-in-1 tablets), a diverter valve in the water inlet system (which bypasses the water softener in predetermined phases of the washing and rinsing cycle) allows to reduce the time interval for replacing the removable softener. Moreover the dishwasher can be sold in certain regions (in which water has low hardness) without the disposable water softening filter, informing the user that a 3-in-1 tablet detergent is preferred (and giving to the user the possibility to buy the water softener cartridge separately from the dishwasher if he prefers to use the traditional detergent). Another advantage of the dishwasher according to the invention is that it does not release salt and chlorine ions into the environment (contrary to what happens for usual dishwashers during resin regeneration). The removable softener acts as a sort of filter for calcium ions, and it prevents removal of all the scale, leaving the optimum amount for best performances. It prevents also etching effect on glasses. The removable softener can be made as a cartridge easily mounted in the dishwasher, for instance by means of a bayonet type fastener. The cartridges can be stored for a long period of time, being not igroscopic (contrary to the limited storage period of regenerating salt). The removable softener according to the invention is much easier to replace than filling salt inside its reservoir. It also leaves tub interior clean, making useless the traditional salt dispenser cap.
Other features and advantages of a dishwasher according to the present invention will be clear from the following detailed description, with reference to the attached drawings in which:

figure 1 is a perspective view of an in-sink dishwasher according to the invention;
figure 2 is a bottom view of the dishwasher of figure 1; and
figure 3 is a perspective view of the dishwasher of figure 1, in which the sink and the cover of the dishwasher components have been removed and with a schematic of the water softening circuit.

With reference to the drawings, with 10 it is indicated an in-sink dishwasher having a main sink 10a and an auxiliary sink 10b placed side by side and supported by the same frame 10c. The dishwasher 10 is adapted to be mounted in a cutout of a worktop of a kitchen piece of furniture (not shown), as all the other types of in-sink dishwashers. In the main sink 10a a removable rotating spray arm 11 is mounted and a rack 12 can be removably inserted when the sink has to be used as the tub of the dishwasher (closed by a lid 14). Under the main sink 10a a wash module 16 is installed, containing the components of the dishwasher.
Such components are shown in figures 2 and 3 and comprise a sump 18, a membrane switch 20 for controlling water level in the tub 10a, an inlet valve 22, a control platform 24, a rinse-aid dispenser 26, a motor pump heater 28, a discharge pump 30 and a water softener 32.
The water from the main is fed to the inlet valve 22 controlled by the platform 24. From the valve 22 the water flows in the water softening filter 32 and then in tube 34 towards a first air gap 36, and then, through a tube 38, in the tub/sink 10a. The inlet valve 22 can be not just an on-off valve, but can also be a diverter valve for feeding water to the water softener 32 trough an inlet tube 40. From the softener 32, soft water flows in a tube 42 towards a second air gap 44 and then, through a tube 46, in the tub/sink 10a. Depending on the configuration of the inlet and diverter valve 22, the incoming "hard" water can be fed directly into the tub 10a or it can be softened by passing it through the water softener 32. This latter presents a base portion 32a fixed to the frame 10c of the dishwasher 10 and a cartridge removable portion 32b containing the resin pellets. The cartridge portion 32b is placed on a side of the main sink 10a, under the bottom of the auxiliary sink 10b. It can be easily removed and replaced by the user by simply opening a door (not shown) provided in the piece of furniture supporting the dishwasher 10. Once the cartridge 32b is removed and not replaced by a new one, a spring loaded closure assures that if the valve 22 drives water through the pipe 40, there will be no water leakage from the system (and of course there will be no softening action on the incoming water). It is not necessary to describe in detail such closure system since it is already known for instance from water filters of refrigerators or the like.
The control platform drives the valve 22 in order to feed softened water to the tub 10a only when is strictly necessary, for instance in the main wash phase and in the final rinse.
The water inlet system may include a water hardness sensor for providing the control platform 24 with a signal indicative of the actual water hardness, and therefore for adjusting the amount of water passing through the softener 32 accordingly. The control platform 24 may also receive an input signal (for instance through a button on the user interface of the dishwasher) concerning the use of a 3-in1 or similar composition, and it can further adjust the amount of water that is needed to be softened. Moreover, the water softener 32 may include a sensor for providing the control platform 24 with a signal indicative of the exhaustion of the cartridge 32b. In this case the user is alerted and informed when the cartridge has to be replaced.
Even if the above description is focused on an in-sink dishwasher, it is clear that the same technical principle can be applied to every kind of domestic dishwasher, particularly in case the overall cost of the appliance has to be kept low in order to render it more appealing to a potential customer.

Claims

Dishwasher comprising a water inlet system (22, 34, 38) and a water spray system (11) inside a tub (10a, 14), characterised in that the water inlet system comprises a removable water softener (32, 32b).
Dishwasher according to claim 1, characterised in that the removable water softener is a cartridge (32b) placed outside the tub (10a, 14).
Dishwasher according to claim 1 or 2, characterised in that upstream the removable water softener (32, 32a), the water inlet system comprises a valve (22) for bypassing the softener (32).
Dishwasher according to claim 3, characterised in that the valve (22) is controlled by a central process unit (24) of the dishwasher (10) on the basis of the water hardness and/or of the programme selected by the user.
Dishwasher according to any of the preceding claims, of the type where a closable sink (10a) of a kitchen furniture has the function of a tub, characterised in that the removable water softener (32, 32a, 32b) is placed substantially on a external side of the sink (10a).
Dishwasher according to claim 4, characterised in that the water inlet system comprises a water hardness sensor for providing the central process unit (24) with a signal on which the amount of water to be passed through the softener (32) can be adjusted by driving the valve (22).
Dishwasher according to any of the preceding claims, characterised in that the removable water softener (32, 32b) is provided with a sensor for providing a signal indicative of the exhaustion of the softener (32).