[0001] The present invention relates to dishwashers, and in particular to a dishwasher with
an improved drying system and a relevant operating cycle.
[0002] It is known that the operating cycle of a dishwasher usually includes a final drying
step intended to make the dishes ready for use as soon as they are extracted from
the dishwasher, and to this purpose the dishwasher is provided with a drying system
that can be made in various more or less sophisticated ways. The most advanced systems
include members outside the wash tank, such as devices for capturing, condensing or
discharging vapor, with possible heating of the air reintroduced into the tank.
[0003] However, these known drying systems have the drawback of causing an "indirect" drying,
in the sense that they act by decreasing the relative humidity of the air contained
in the tank to allow the subsequent evaporation of the water clinging to the dishes.
This implies long drying times and a high power consumption for heating the air reintroduced
into the tank.
[0004] Furthermore, in order to reduce the power consumption, the latest developments in
the field of dishwashers have led to a decrease in rinse temperatures and this enhances
the above-mentioned drawback, which therefore partially cancels the reduction in consumption
achieved by decreasing the rinse temperatures.
[0005] Therefore the object of the present invention is to provide a dishwasher which overcomes
the above-mentioned drawbacks.
[0006] This object is achieved by means of a dishwasher provided with a bottom sprinkler
including members suitable to generate an air stream, as well as driving means suitable
to rotate said bottom sprinkler during the drying step.
[0007] The main advantage of the drying system of the present dishwasher is that of acting
directly on the dishes, in particular those located in the bottom rack, by generating
an air stream that "spreads" the water drops present on the dishes favoring their
evaporation.
[0008] A second advantage stemming from this air stream is the creation of convective motions
that take the vapor contained in the air more into contact with the tank walls favoring
its condensation, since the tank walls provide a heat exchange greater than the dishes.
[0009] Still a further advantage of the present dishwasher stems from the fact that the
auxiliary members of the drying system are few, simple and inexpensive, so as to improve
the drying performance with a minimum increase in cost and without negatively affecting
reliability.
[0010] 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 front perspective view, with some portions removed, of a dishwasher provided
with an improved drying system according to the present invention;
Fig.2 is an enlarged detail of the dishwasher of Fig.1;
Figs.3 and 4 are views similar to the preceding one, with some portions removed;
Fig.5 is a detail further enlarged of Fig.2; and
Figs.6 and 7 are bottom views showing the activation and deactivation of the bottom sprinkler
driving mechanism.
[0011] Referring to figures 1 and 2, there is seen that a dishwasher according to the present
invention conventionally includes a pair of revolving sprinklers S, S' respectively
arranged on the bottom B of the wash tank and under the top rack R (the bottom rack
is not shown).
[0012] It should be noted that although specific reference is made to the conventional structure
of a dishwasher with stacked racks, what is being said is also readily applicable
to a horizontal dishwasher with racks side by side comprising two sprinklers on the
tank bottom that can both be provided with the auxiliary members of the drying system,
which are arranged partly under the tank bottom B and partly above it.
[0013] As shown in the enlarged detail of Fig.2, the novel members arranged above the tank
bottom B include a mobile arm A carrying a drive gear G suitable to engage a toothed
wheel T integral with the bottom sprinkler S, which is provided with a pair of blade-shaped
profiles P arranged along opposite sides of its two arms.
[0014] When arm A is in the rest position illustrated in Fig. 2, and therefore gear G does
not engage the toothed wheel T, sprinkler S operates in the conventional way revolving
under the effect of the reaction to the water jets ejected through nozzles N, since
it is mounted idle on the tube connecting it to the wash pump.
[0015] As shown in Fig.3, where arm A and the tank bottom B are omitted, the other novel
members of the drying system secured under the tank bottom B include a mounting support
essentially consisting of a plate H with a cylinder J perpendicular thereto and whose
top projects through the tank bottom B. Under plate H there are secured a mechanism
for moving arm A, that will be better described further on, and an electric motor
M whose drive shaft D projects at the top of the support through said cylinder J and
carries an end gear E.
[0016] It should be noted that arm A rotates with respect to the mounting support thanks
to a vertical cylindrical portion slidably inserted in cylinder J, i.e. arm A has
a vertical cross-section that is substantially L-shaped.
[0017] The enlarged detail of Fig.4, where the cover of arm A and the tank bottom B are
omitted, clearly shows how the end gear E engages a first gear F arranged inside arm
A, and in turn said first gear F is connected to the drive gear G of arm A through
a kinematic chain K comprising a plurality of other gears.
[0018] Adequate sealing means, such as O-rings or the like, are obviously located between
arm A and cylinder J, as well as at the point where shaft D enters arm A.
[0019] In the light of the description above and with reference also to figures 5 to 7,
the simple and effective operation of the drying system of the dishwasher according
to the present invention will be readily understood.
[0020] As shown in Fig.5, when arm A is rotated towards sprinkler S at the end of the wash
cycle, the drive gear G engages the toothed wheel T whereby motor M can set into rotation
sprinkler S through the above-described members D, E, F, K, G and T. In particular,
as indicated by the arrows, sprinkler S is rotated such that profiles P are on the
leading edge and therefore can operate with the maximum aerodynamic efficiency (said
direction may coincide or not with the revolving direction of sprinkler S during the
wash step).
[0021] In this way, the bottom sprinkler S acts in practice as the rotor of a fan generating
a vertical air stream that significantly improves the drying performance of the dishwasher,
as explained in the introductory portion. At the end of the drying step, gear G is
disengaged from the toothed wheel T by returning arm A to the rest position, whereby
sprinkler S is again free to revolve idle on its vertical axis.
[0022] It should be noted that the period of activation of the auxiliary members of the
drying system must not necessarily coincide with the duration of the drying step,
and it is also possible to provide more than one period of activation during said
step.
[0023] A possible mechanism for moving arm A between the rest position and the work position
is illustrated in figures 6 and 7, where there is seen a linear actuator X fixed under
plate H, with the stem Y of said actuator X connected to a screw Z screwed into the
vertical cylinder of arm A through a slot L formed in cylinder J. On the same screw
Z there is also secured a first end of a return spring C whose second end is fixed
under plate H.
[0024] In this way, when actuator X is powered its stem Y is extended and screw Z rotates
arm A to the work position, whereby motor M can rotate sprinkler S, whereas when actuator
X is switched off the return spring C causes the rotation of arm A to the rest position,
disengaging the drive gear G, and the retraction of stem Y.
[0025] 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 exact shape and arrangement of the auxiliary members of the drying
system could be changed according to specific manufacturing needs, e.g. by using a
different type of actuator to move arm A or a different kinematic chain to connect
motor M to sprinkler S (e.g. two pulleys and a belt).
[0026] Similarly, sprinkler S could have members suitable to generate an air stream that
are different from the above-illustrated profiles P and possibly integrated in the
sprinkler itself, that could be shaped like a fan rotor.
1. Dishwasher provided with a drying system and comprising at least one revolving sprinkler
(S) arranged on the wash tank bottom (B), characterized in that said revolving sprinkler (S) includes members suitable to generate an air stream
and said drying system includes driving means suitable to rotate said revolving sprinkler
(S) during the drying step.
2. Dishwasher according to claim 1, characterized in that the sprinkler (S) is provided with a pair of blade-shaped profiles (P) arranged along
opposite sides of its two arms.
3. Dishwasher according to claim 2, characterized in that the driving means are suitable to rotate the revolving sprinkler (S) in such a direction
that the blade-shaped profiles (P) are on the leading edge.
4. Dishwasher according to claim 1, characterized in that the sprinkler (S) is shaped like a fan rotor.
5. Dishwasher according to any of the preceding claims, characterized in that the driving means suitable to rotate the sprinkler (S) include an arm (A), mobile
between a rest position and a work position, carrying a drive gear (G) suitable to
engage a toothed wheel (T) integral with the sprinkler (S), said drive gear (G) receiving
the motion from an electric motor (M) through a kinematic chain located in said arm
(A).
6. Dishwasher according to the preceding claim, characterized in that the mechanism for moving the arm (A) between the rest position and the work position
includes a linear actuator (X) whose stem (Y) is connected to a member (Z) secured
on the arm (A) in such a way as to take the arm (A) to the work position when said
linear actuator (X) is powered, as well as a return spring (C) also connected to said
member (Z) secured on the arm (A) in such a way as to return the arm (A) to the rest
position when said linear actuator (X) is switched off.
7. Operating cycle for a dishwasher according to any of the preceding claims, comprising
a drying step, characterized in that said drying step includes at least one period of activation of the driving means
suitable to rotate the revolving sprinkler (S).
8. Operating cycle according to the preceding claim, characterized in that the period of activation substantially coincides with the duration of the drying
step.