EP1498065B1

EP1498065B1 - Dishwasher with means for reducing the water and power consumption

Info

Publication number: EP1498065B1
Application number: EP03425389A
Authority: EP
Inventors: Ezio Gobbi
Original assignee: Bonferraro SpA
Current assignee: Bonferraro SpA
Priority date: 2003-07-16
Filing date: 2003-07-16
Publication date: 2005-11-02
Anticipated expiration: 2023-07-16
Also published as: DE60302143D1; ATE308267T1; DE60302143T2; ES2251674T3; EP1498065A1

Abstract

A dishwasher includes an electrovalve (W) controlling the entrance of water from the network, a water softening unit, a washing tank, a drain duct (D), a detergent distributor, a heating resistor (HR) and a microprocessor, in the washing tank there being provided two racks (R, R') side by side and a removable central dividing baffle (S) which performs the division of the tank into two independent sectors (T, T') each of which is provided with a collecting sump (J, J') with relevant filter and pressure switch (P, P'), a drain pump (DP; DP') and at least one sprinkler (L, L'). The feeding of the water coming from the softening unit takes place through a first deviating valve (VD) which directs the water to the respective supply ducts of the sectors (T, T') and the draining takes place through a connector (Y) which converges the drain ducts of the two sectors (T, T') into the drain duct (D), there also being provided a three-way manifold which receives water from the collecting sumps (J, J') through respective ducts (E, E') and conveys it to a single washing pump (WP) which feeds it to the sprinklers (L, L') through a second deviating valve (V) and relevant delivery ducts (H, H'), said manifold being provided with shutter means suitable to close the inlets of the ducts (E, E') coming from the collecting sumps (J, J'). In this way, when using one sector only the machine can actually operate at half load with a power and water saving close to 50%, and also in the full load operation it is possible to achieve a high water saving by transferring the water from one sector to the other for an alternate washing. <IMAGE>

Description

The present invention relates to dishwashing machines, and in particular to a dishwasher for domestic use provided with means for reducing the water and power consumption.
It is known that dishwashers for domestic use are provided with various arrangements for adapting them to the number and type of dishes to be washed, such as the setting of low-temperature, or energy-recovery, cycles or the feeding of one sprinkler only and so on. Regardless of the adopted solution, in known dishwashers the washing affects the whole tank and therefore the whole structure of the machine is heated through the contact with hot water, with the consequence that the actual energy saving with respect to the full load operation does not exceed 20%.
Moreover, given that the machine is sized for a certain maximum load, even when the half load cycle is selected the amount of water used remains substantially unchanged, and also this contributes to a waste of power and water.
Therefore the object of the present invention is to provide a dishwasher which overcomes the above-mentioned drawbacks.
This object is achieved by means of a dishwasher provided with means for dividing the washing tank into two sectors which can operate independently one of the other. Such dishwashers are known for example from DE 1628544A. Other advantageous features are disclosed in the dependent claims.
The main advantage of the dishwasher according to the present invention is exactly that of being able to actually operate at half load, heating only half of the machine and with a power and water saving close to 50%.
A second advantage of the present dishwasher is that of being able to use the same water load to wash alternately the dishes in the two sectors when the machine is at full load, thus achieving also in this case a water saving close to 50%.
A further advantage of this type of machine stems from the fact that when the tank is undivided and the operation is conventional, larger dishes can be loaded and it still achieves better washing results thanks to the plurality of sprinklers and filters.
These and other advantages and characteristics of the dishwasher according to the present invention will be clear to those skilled in the art from the following detailed description of an embodiment thereof, with reference to the annexed drawings wherein:
Fig.1 is a diagrammatic front view showing some essential elements of the present dishwasher and their connections;
Fig.2 is a view similar to the preceding one showing in detail a first embodiment of the system for the feed and transfer of water between the two sectors of the above-mentioned dishwasher;
Fig.3 is a view similar to the preceding one showing in detail a second embodiment of the system for the feed and transfer of water between the two sectors;
Fig.4 is an enlarged view of the connection manifold shown in fig.2; and
Fig.5 is an enlarged view of the connection manifold shown in fig.3.
Referring to Fig.1, there is seen that a dishwasher according to the invention conventionally includes a plurality of known elements: an electrovalve W controlling the entrance of water from the network, a meter F which measures the amount of water entering the machine, a unit for softening the water by means of decalcifying resins located in a container R, which includes a chamber A for the collection of water intended for the regeneration of said resins by means of a sodium chloride solution which is formed in a salt container S connected to container R through an electrovalve VR, and a drain duct D.
The novel aspect of the present dishwasher consists of a horizontally extending washing tank with two racks R, R' side by side rather than one on top of the other, and a removable central dividing baffle S which performs the division of the tank into two independent sectors T, T'.
In fact in each of the two sectors there is provided a collecting sump J and J' from which the water is drained through a drain pump DP and DP', a bottom sprinkler L and L' and possibly a top sprinkler U and U'. The feeding of the water coming from the common softening unit takes place through a deviating valve VD which directs the water to the respective supply ducts, and similarly the draining takes place through a connector Y which converges the drain ducts of the two sectors into the common drain duct D.
It is obvious that also other elements not illustrated in the figures are provided, such as temperature sensors, pressure switches, a microprocessor to control the operation of the machine and so on.
It should be noted that in the absence of the baffle S it would be possible to use a single rack, having a width equal to the tank width, which is capable of receiving particularly large dishes, i.e. having a side longer than 60 cm, which can not presently be washed in the domestic dishwashers available on the market.
Furthermore, the fact of having two smaller collecting sumps J, J' allows to provide the maximum filtering effectiveness and to optimize the used amount of water. In fact the two separate filters have a combined filtering surface greater than that of the single filter of a conventional dishwasher, and the smaller area of each sump allows for a greater inclination of the bottom which favours the flowing of the water towards the filter and therefore allows for a greater useful height of the sump.
The dishwasher door is preferably one but provided with two detergent/rinse aid distributors, one for each sector, so as to introduce the products only in the distributor corresponding to the sector to be used.
The dividing baffle S is designed so as to assure along the four sides a sufficient water tightness, but in order to make easier its introduction and removal into and from the tank there is not provided a forced coupling. In fact even possible leakages from one sector to the other in case of separate operation are not a problem, and upon the final drain of the cycle also the drain pump of the inoperative sector is activated for some seconds to drain out said possible leakages.
Moreover there is also provided a sensor for detecting the presence of baffle S which can be made in various known ways such as a microswitch in a vertical baffle seat, or a magnet mounted on the baffle which activates a reed sensor mounted on the tank or on the door. In this way the microprocessor will not accept the setting of separate cycles in the absence of baffle S and will give a relevant indication to the user, e.g. by lighting up a symbol on the display.
Referring now to figs.2 and 4, there is illustrated the first embodiment of the water feed and transfer system, which must take into account the problems which may arise when one of the two sumps J, J' is empty.
In fact, for space and cost reasons it is preferable to have only one washing pump WP which feeds both sectors, however this also implies that pump WP drains away the water from both sumps J, J'. If water is present in only one of the two sumps, there is the problem of the draining of air from the empty sump with negative consequences both on washing and noise.
It should be noted that this problem is present not only in the half load operation, i.e. when only one sector is used, but also in full load cycles with "alternate" washing, since during the transfer of water from one sector to the other the system has to be controlled so as to prevent at any time that air is drained from the empty sump.
In order to overcome these problems, pump WP is not directly connected in suction to the two sectors, whereas it is directly connected in delivery through a duct G, an electrovalve V which deviates the flow to one sector or the other and relevant delivery ducts H, H' which take the water to the sprinklers L, L' and U, U' (the upper portion of the hydraulic circuit being omitted in figs.2 and 3).
On the contrary, the ducts E, E' coming from sumps J, J' converge into a three-way manifold CA, from which a single duct F comes out to take the water to pump WP passing through a heating resistor HR. This manifold CA is that which allows to control the half load or alternate full load operation, by preventing the draining of air as described hereafter.
Inside the body of manifold CA there are arranged two shutters O and O', respectively at the inlets of ducts E and E', consisting of flaps secured to the manifold body and provided with integral hinges which are formed in practice by bending lines B, B'. Behind the shutters O, O' there are arranged nozzles N, N' which are oriented to emit water jets towards the respective shutters and are fed through respective tubes K, K' branching out from the above-mentioned delivery ducts H, H'.
The operation of the present dishwasher will now be described assuming to start with the washing in the left sector, the manifold of fig.4 being shown exactly in this state.
After loading a sufficient amount of water in sump J', the washing pump WP drains water through duct E' and manifold CA, in which shutter O does not resist the flow by bending along the bending line B, and finally duct F. The delivery of pump WP reaches the deviating electrovalve V, which is properly controlled to leave open the outlet towards duct H', thus feeding sprinkler L' (and U' if present) and, through duct K', reaches nozzle N' in manifold CA.
By taking into account the size of the elements, the depression in the suction duct and the pressure available in duct K' it is possible to define the size of nozzle N' such that it emits a water jet which, though losing part of its energy in the manifold chamber due to the water present therein, is capable of resisting the depression by pushing shutter O' against the inlet of duct E, connected to the empty sump J, so as to prevent the inflow of air.
After a certain interval, valve V is driven to a partial opening for the outflow of water towards duct H to take water through sprinkler L to the right sector, while decreasing at the same time the flow rate to sprinkler L'. In this phase the pressure on shutters O, O' generated by nozzles N, N' is not sufficient to overcome the suction depression, due to the increase in the outgoing flow rate of pump WP and the consequent decrease in ducts K and K', whereby both shutters are partially open but without any consequence in that water is present in both sumps.
As soon as the microprocessor detects the switching of the pressure switch P in sump J, adjusted on the level of "minimum water amount" for the feeding of the relevant sprinkler, it controls the progressive switching of the feeding and concludes it when the pressure switch P' in sump J' confirms that sump J' is almost empty.
Although the sealing of shutters O, O' is good, to the extent that even when the washing pump WP is at rest the static pressure of the water in the filled sump is sufficient to assure the sealing of the shutter on the depressed duct, yet it is possible to arrange on ducts E, E' respective cut-off valves C, C' driven by relevant actuators. This solution obviously implies a greater cost but it can be taken into consideration for a greater reliability of the system, thus prescinding from the behaviour of the shutters after a certain number of cycles and in particular if the half load function is often used always on the same side.
It should be noted that it is not possible to use valves C, C' to carry out also the control of the phases of the alternate washing in that the driving velocities required and the lack of "co-ordination" between the two valves would certainly give rise to problems, as experienced in the tests carried out by the applicant.
Referring now to figs.3 and 5, there is illustrated the second embodiment of the water feed and transfer system, which provides a simpler hydraulic circuit but requires at least one actuator.
In fact in this case manifold CA is replaced by a manifold CM including a shutter VS rotatable around an axis X under the action of an actuator M, the movement Z of said shutter VS taking it to close alternately the inlets of ducts E' and E.
As a consequence there is no more need of the ducts K, K' which in the first embodiment allowed an "automatic balancing" of the flows in manifold CA, however it is necessary to control properly the phase of the transfer from one sector to the other. In fact this is the most critical phase for this solution where it is required to control the opening of duct E by shutter VS: too early an opening would allow air from sump J to reach pump WP, whereas too late an opening would cause the complete emptying of sump J' with the same result.
In this regard it is preferable to use pressure switches P, P' of analogical type suitable to continuously detect the amount of water in the sumps, as well as a suitable control software. Moreover, the actuator M of manifold CM must be capable of moving shutter VS in a short time according to the commands from the microprocessor. In this solution it is obviously superfluous to provide further cut-off valves since the sealing is assured by the motorized manifold, in which at the end of the transfer the shutter VS closes duct E' (position in broken lines).
It is clear that the above-described and illustrated embodiment of the dishwasher according to the invention is just an example susceptible of various modifications. In particular, the number, shape and arrangement of the elements of each sector can be somewhat changed for example by providing further heating resistors, further sprinklers, a crockery tray above the rack and so on. Furthermore, the single door could be replaced by two individual doors, possibly mutually connectable, so as to make one sector completely independent of the other.

Claims

Dishwasher including an electrovalve (W) controlling the entrance of water from the network, a water softening unit, a washing tank, a drain duct (D), a detergent distributor, a heating resistor (HR) and a microprocessor, characterized in that in said washing tank there are provided two racks (R, R') side by side and a removable central dividing baffle (S) which performs the division of the tank into two independent sectors (T, T') each of which is provided with a collecting sump (J, J') with relevant filter and pressure switch (P, P'), a drain pump (DP; DP') and at least one sprinkler (L, L'), the feeding of the water coming from said softening unit taking place through a first deviating valve (VD) which directs the water to the respective supply ducts of said sectors (T, T') and the draining taking place through a connector (Y) which converges the drain ducts of the two sectors (T, T') into said drain duct (D), there also being provided a three-way manifold which receives water from said collecting sumps (J, J') through respective ducts (E, E') and conveys it to a single washing pump (WP) which feeds it to the sprinklers (L, L') through a second deviating valve (V) and relevant delivery ducts (H, H'), said manifold being provided with shutter means suitable to close the inlets of said ducts (E, E') coming from the collecting sumps (J, J').
Dishwasher according to claim 1, characterized in that the washing tank is closed by a single door provided with two detergent/rinse aid distributors, one at each sector (T, T').
Dishwasher according to claim 1, characterized in that each sector (T, T') is closed by a relevant door provided with a detergent/rinse aid distributor.
Dishwasher according to claim 3, characterized in that the two doors are mutually connectable.
Dishwasher according to one or more of the preceding claims, characterized in that the dividing baffle (S) is mounted in the tank through a coupling suitable to assure along the four sides an adequate water tightness while allowing for a smooth introduction and removal thereof.
Dishwasher according to one or more of the preceding claims, characterized in that it includes a sensor for detecting the presence of the dividing baffle (S).
Dishwasher according to claim 6, characterized in that the sensor for detecting the presence of the baffle (S) consists of a magnet mounted on the baffle (S) so as to activate a reed sensor mounted on the tank or on the door.
Dishwasher according to one or more of the preceding claims, characterized in that the manifold (CA) includes shutters consisting of flaps (O, O') secured to the body of the manifold (CA) and provided with integral hinges formed by bending lines (B, B'), behind said flaps (O, O') there being arranged nozzles (N, N') which are oriented to emit water jets towards the respective shutters and are fed through respective tubes (K, K') branching out from the delivery ducts (H, H').
Dishwasher according to one or more of claims 1 to 7, characterized in that the manifold (CM) includes a shutter (VS) rotatable around an axis (X) under the action of an actuator (M), the movement (Z) of said shutter (VS) taking it to close alternately the inlets of the ducts (E, E') coming from the sumps (J, J').
Dishwasher according to claim 9, characterized in that the pressure switches (P, P') are of the analogical type suitable to continuously detect the amount of water in the sumps (J, J').