[0001] The present invention refers to a washing machine, in particular of the household
type, which is also adapted to carry out a cycle for drying the washload contained
therein.
[0002] It should be noticed that the term washing machine is used here to mean a clothes
drier, a clothes washer-drier or any other similar household appliance, such as in
particular a dishwasher.
[0003] Washing machines provided with a drying function for the washload contained in their
drum or vessel are well-known in the art. As described for instance in US-A-5 273
061, a condenser is arranged in the washing vessel of a dishwasher and a forced draught
of cooling ambient air is caused to flow therethrough. The water vapour that is present
in the washing vessel at the end of a rinsing phase performed with hot water condenses
on the outer walls of said condenser, thereby promoting drying of the washload items.
[0004] Solutions are also known, such as from instance from the disclosure in US-A-5 056
543, in which the hot moist air that is present in the washing vessel is circulated
directly through the condenser, where it therefore cools down and gives off its moisture
contents.
[0005] However, all this prior-art solutions tend to be undesirably complicated and expensive,
since they require, for drying the washload, the use of an appropriate condenser which
must usually be associated to auxiliary cooling media such as air or water.
[0006] A simpler and more advantageous solution is described in EP-A-0 800 786, in which
the top and the bottom of the washing vessel of a dishwasher are mutually connected
through a conduit running externally of the same vessel, so as to form a closed-loop
path along which the water vapour can therefore circulate as the washload is being
dried in the vessel. Such a solution enables the washload items to be dried in a homogeneous,
but not fully satisfactory manner.
[0007] It therefore is a purpose of the present invention to provide a washing machine provided
with an improved washload drying system that is capable of enabling the washload items
to be dried in a particularly effective manner, while avoiding to involve any substantial
complication from a construction point of view.
[0008] According to the present invention, such aim is reached in a washing machine with
an improved washload drying system embodying the features as recited in the appended
claims.
[0009] Anyway, characteristics and advantages of the present invention will become more
readily understood from the description that is given below by way of non-limiting
example with reference to the accompanying drawing, wherein such a drawing is shown
to schematically illustrate the main component parts of a preferred embodiment of
the washing machine according to the present invention.
[0010] With reference to the drawing, the washing machine is preferably an automatic dishwasher
that mainly comprises a washing vessel 1 provided on its lower portion with a sump
2 for collecting the water.
[0011] In a per sè known manner. the vessel 1 accomodates at least a rack 1 for supporting
the items (not shown) to be washed by means of water jets adapted to be ejected by
appropriate spraying means 4.
[0012] The dishwasher is of the type adapted to automatically perform selectable operation
cycles, of which at least one comprises a final washload rinsing phase carried out
with hot water (eg. water heated up to a temperature of approx. 70°C). At the end
of such a final rinse, water vapour is usually present in the washing vessel so that,
for the washload to be dried, such a water vapour must be eliminated or removed therefrom.
[0013] According to a feature of the present invention, the machine further comprises compressor
means 5 having at least an inlet 6 and at least an outlet 7. The inlet 6 is connected
to an upper aperture 8 of the washing vessel via a conduit 10. The outlet 7 is preferably
connected to a lower aperture 9 of the washing vessel via a conduit 11. The compressor
5 and the conduits 10, 11 are preferably arranged on the outside of the washing vessel
1.
[0014] The compressor 5 can be of any type adapted to suit the purpose. For instance, it
can be of a type which is readily available on the market with an appropriately and
advantageously limited power rating, low space requirements, and at reduced costs,
such as for example a Model 006LCD/30-5 compressor of ASF Thomas Industries GmbH,
traditionally used in a fully different area of application such as the one of inhalators.
[0015] In a preferred manner, the compressor 5 is of the type comprising a chamber 12 in
which a piston 13 is adapted to be actuated with a reciprocating motion by an electric
motor, or the like, controlled by the programme sequence control unit of the machine.
For reasons of greater simplicity, the motor and the programme sequence control unit
are not shown in the drawing. It shall anyway be appreciated that the compressor 5
can also be of a different type, such as for instance of the electromagnetic type
with the moving member oscillating with a reciprocating motion.
[0016] In a preferred manner, the inlet 6 and the outlet 7 of the compressor are associated
to respective non-return valves 14, 15. Furthermore, the inlet 6 has preferably a
cross-section area that is larger than the one of the outlet 7.
[0017] As it will be explained in greater detail further on, the vessel 1, the compressor
5 and the conduits 10, 11 practically form a drying system, preferably, but not necessarily
or exclusively in a closed-loop configuration, along which the water vapour that develops
in the washing vessel is therefore capable of being circulated in a single direction,
as this is shown by the arrows in the drawing.
[0018] Upon conclusion of the above mentioned final rinsing phase, the compressor 5 is adapted
to be driven in view of performing a drying phase in the manner described below.
[0019] During the suction stroke of the piston 13 (rightwards in the drawing), the compressor
5 takes in water vapour from the washing vessel 1 via the conduit 10 and the valve
14 which opens in order to enable the water vapour to enter the chamber 12.
[0020] During the compression stroke of the piston 13 (leftwards in the drawing), the water
vapour so taken in by the compressor is compressed in the chamber 12 and caused to
escape through the valve 15 which opens accordingly. Such a compression of the water
vapour causes the latter to substantially condense.
[0021] It therefore clearly emerges that such an operation of the compressor 5 during the
drying phase enables the water vapour to be effectively eliminated, while the resulting
condensate is conveyed along the outlet conduit 11. In the preferred case in which
said conduit 11 is connected to the lower aperture 9 of the vessel, as already indicated
earlier in this description, the condensate is capable of collecting in the sump 2
for being then discharged in a per sè known manner.
[0022] Fully apparent is at this point also the constructional and operational simplicity
of the machine according to the present invention which (as this has been verified
also experimentally) is able to dry the washload items contained in its vessel 1 in
a particularly quick, complete and effective manner.
[0023] The performance of the drying system can be further enhanced by arranging at least
a portion of the chamber 12 of the compressor in a heat-exchange relation with the
ambient on the outside of the washing vessel 1, wherein said ambient is at a temperature
T0 (eg. 25°C) that is substantially lower than the temperature T (approx.70°C) prevailing
inside the vessel at the beginning of the drying phase. In fact, the compression of
the water vapour inside the chamber 12 of the compressor causes also the temperature
thereof to correspondingly increase up to a value T1 > T > T0, wherein such a temperature
T1 may for instance have a value of approx. 80°C.
[0024] As a result, the greater temperature difference T1 - T0 between the compressed water
vapour and the ambient outside the compressor enables the water vapour to be more
effectively cooled down, thereby promoting its condensation.
[0025] It will be appreciated that the above described washing machine can undergo a number
of modifications without departing from the scope of the present invention.
1. Washing machine comprising a washing vessel in which water vapour is present at the
beginning of a drying phase of the washload items accomodated in the same vessel,
characterized in that it further comprises compressor means (5) having a chamber (12)
with at least an inlet (6) and at least an outlet (7) that are connected to an aperture
(8) of the washing vessel (1) and an outlet conduit (11), respectively, said compressor
means being adapted to take in the water vapour from the vessel through said inlet
(6), to compress the so taken-in water vapour in order to cause it to substantially
condense, and to convey it towards said outlet conduit (11).
2. Washing machine according to claim 1, characterized in that said outlet conduit (11)
communicates with a further aperture (9) of the vessel so that said vessel (1), the
compressor means (5) and said conduits (10, 11) form a closed-loop drying system along
which said water vapour is capable of being circulated, the resulting condensate collecting
into the vessel.
3. Washing machine according to claim 2, characterized in that said inlet (6) and said
outlet (7) of the compressor means (5) are associated to respective non-return valves
(14, 15) so that the water vapour is circulated in said closed-loop circuit in a single
direction only.
4. Washing machine according to claim 1, characterized in that the inlet (6) of said
chamber (12) of the compressor means (5) has a larger cross-section area than the
outlet (7) of the same chamber.
5. Washing machine according to claim 1, characterized in that said chamber (12) of the
compressor means (5) is at least partially in a heat-exchange relation with the ambient
on the outside of the washing vessel (1) so as to promote the condensation of the
water vapour being compressed inside the same chamber.