[0001] The present invention relates to pumps for dishwashers and the like, and in particular
to a double-delivery bidirectional pump in which the direction of rotation determines
through which delivery the water is delivered. Specific reference will be made in
the following to the application of said pump to a dishwasher, but it is clear that
what will be said can be adapted also to the use of the present pump in a washing
machine or other domestic appliance.
[0002] It is known that in modern dishwashers the user is often offered the possibility
of running a "half load", i.e. a washing cycle in which only one of the sprinklers
is used, or an "alternate" wash in which the two sprinklers are alternately supplied
thus allowing to extend the washing of the dishes in one of the two racks.
[0003] This type of program is usually obtained through a single-delivery washing pump and
a flow distribution valve controlled by the control unit of the machine to direct
the water flow to the upper or lower sprinkler. As an alternative, there may be provided
a double-delivery pump with two valves independently controlling the supply to the
two sprinklers.
[0004] Other valves may be provided to supply a hydraulic circuit for the periodical cleaning
of the dishwasher filters, or a short-length heating circuit to reduce the energy
waste during the water heat-up phase. In addition to the washing pump there is also
provided a draining pump to drain the water out of the tank at the end of the washing
cycle.
[0005] Clearly, the presence of one or more valves and of two pumps implies an increase
in the machine manufacturing cost, as well as a decrease in reliability since the
failure or clogging of a valve or a pump can jeopardize the correct machine operation.
[0006] Therefore the object of the present invention is to provide a pump which allows to
overcome said drawbacks. This object is achieved by means of a double-delivery pump
capable of handling two separate hydraulic circuits simply by reversing its direction
of rotation.
[0007] The main advantage of the pump according to the present invention is exactly that
of allowing to dispense with the valve(s) to control the supply to two different hydraulic
circuits, or that of combining the functions of washing pump and draining pump.
[0008] Another advantage of this pump stems from the fact that said functionality is achieved
through a very simple structure substantially without mobile members, with positive
results as to cost and reliability.
[0009] These and other advantages and characteristics of the pump according to the present
invention will be clear to those skilled in the art from the following detailed description
of two embodiments, with reference to the annexed drawings wherein:
Fig.1 is a vertical sectional view of the hydraulic group of the pump in a first embodiment;
Fig.2 is an exploded vertical sectional view of the members which make up the pump impeller;
Fig.3 is a vertical sectional view of the pump showing the path of the water flow when
the pump is driven counter-clockwise;
Fig.4 is a vertical sectional view of the hydraulic group taken along line A-A of fig.3;
Fig.5 is a vertical sectional view of the pump showing the path of the water flow when
the pump is driven clockwise;
Fig.6 is a vertical sectional view of the hydraulic group taken along line B-B of fig.5;
Fig.7 is a vertical sectional view of the pump in a second embodiment; and
Fig.8 is a horizontal sectional view of the hydraulic group taken along line C-C of fig.7.
[0010] Referring to figs.1-6 above, there is seen that the hydraulic group of the pump according
to the invention includes a housing, made up of an external half-shell coupled to
an internal half-shell, and an impeller rotatably arranged within said housing. More
specifically, the impeller is made up of three connected coaxial members, namely a
hub S provided with a blading C, an intermediate ring R also provided with a blading
A as well as with a peripheral rim B, and a cover ring T.
[0011] The external half-shell has a mouth K, connected to the supply duct, through which
the water enters a first external chamber E which ends at the top with a first delivery
duct H, and is separated by ring R from a second internal chamber F which ends at
the top with a second delivery duct J. The connection between the two chambers E,
F is achieved through the central opening of rings T, R in that along the periphery
rim B is introduced into a corresponding channel D so as to form a labyrinth seal
G.
[0012] The novel aspect of the present pump is the particular configuration of the impeller
and delivery ducts, which allows to obtain a "double" pump which can be driven alternately
in one direction or the other. In fact, as shown in figs.4 and 6, while blading C
of hub S has a counter-clockwise spiral shape and the relevant duct J of chamber F
is directed leftward, blading A of ring R has an opposite clockwise shape and the
relevant duct H of chamber E is directed rightward.
[0013] From the description above and referring in particular to figs.3 and 5, the simple
and reliable operation of the pump according to the invention is readily understood.
[0014] When motor M drives the impeller in the counter-clockwise direction (fig.3), the
incoming water flow W is captured only to a very small extent by blading A which is
designed for the clockwise rotation, whereby the water passes through ring R and is
pushed by blading C out through the delivery duct J, which for example is connected
to one of the sprinklers.
[0015] Similarly, when motor M drives the impeller in the clockwise direction (fig.5), the
incoming water flow W is captured mostly by blading A, which is exactly designed for
the clockwise rotation, and is pushed out through the delivery duct H, which for example
is connected to the other sprinkler. The water passing through ring R is just a small
amount, and in any case blading C is designed for the counter-clockwise rotation and
therefore results ineffective.
[0016] The direction of rotation of the electric motor M and therefore of the impeller can
be controlled in various ways well known to a person skilled in the art. For example,
in the case of a nonsynchronous single-phase motor a switch may be provided to change
the sequence of supply to the windings to obtain the clockwise or counter-clockwise
rotation. This switch may be part of an electromechanical timer or it can be part
of an electronic board to achieve even more sophisticated functions, such as a slow
start at every reversal of the direction of rotation (to reduce the noise) or the
activation on the basis of the signals coming from sensors which detect the presence
of dishes to decide to which sprinkler the water flow must be directed.
[0017] As mentioned in the introductory portion, the two ducts H, J may obviously be connected
to two hydraulic circuits of any kind, not only to those of the upper and lower sprinkler.
Therefore the pump may act as washing pump when rotating in a first direction, supplying
both sprinklers, and the rotation in the opposite direction may serve to supply a
secondary hydraulic circuit for heating the water or for cleaning the filters.
[0018] In the same way it may act as draining pump when rotating in the opposite direction,
thus allowing to dispense with the draining pump. However in this case it is necessary
to separate the supply ducts entering the pump to prevent the dirt present in the
water already used for washing from re-entering the circuit.
[0019] To this purpose the hydraulic group may be modified as illustrated in figs.7 and
8, by providing an intermediate ring R' with a central opening U which is smaller
and shaped with a neck extending outward to which there is connected a supply duct
L separate from the duct connected to mouth K.
[0020] In this way the pump can take clean water for washing through a supply duct and dirty
water to be drained through the other duct, the mixing between the two chambers being
negligible.
[0021] It is clear that the above-described and illustrated embodiments of the pump according
to the invention are just examples susceptible of various modifications. In particular,
the exact shape of bladings A and C may be somewhat changed as long as they are designed
for rotation in the two opposite directions, and the same applies to the labyrinth
of seal G which may have a different configuration, e.g. by making it double. Moreover,
the direction of rotation may obviously be inverted with respect to what is depicted
in the figures, i.e. by designing the blades for the counter-clockwise rotation in
the external chamber and for the clockwise rotation in the internal chamber. Similarly,
the position of the delivery ducts may be changed along the periphery of the hydraulic
group (e.g. at the bottom or on a side) as long as the orientation remains consistent
with the direction of rotation of the blading in each chamber.
1. Double-delivery pump made up of an electric motor (M) and a hydraulic group including
an impeller driven into rotation by said motor (M) and arranged within a housing with
two delivery ducts (H, J) and a mouth (K) connected to a supply duct, characterized in that said impeller is made up of a hub (S) provided with a blading (C), an intermediate
ring (R; R') provided with a blading (A) and a peripheral rim (B), and a cover ring
(T), one of said bladings (A, C) having a spiral shape suitable for the clockwise
rotation of the impeller and the other for the counter-clockwise rotation, said housing
being divided by said intermediate ring (R; R') into an external chamber (E) with
a first delivery duct (H) and an internal chamber (F) with a second delivery duct
(J), said chambers (E, F) being separated along their periphery by a labyrinth seal
(G) consisting of said peripheral rim (B) introduced into a corresponding channel
(D), the orientation of said ducts (H, J) being consistent with the direction of rotation
of the blading (A, C) in each chamber (E, F) and the motor (M) being provided with
means for controlling its direction of rotation.
2. Double-delivery pump according to claim 1, characterized in that the ducts (H, J) are formed at the top of the respective chambers (E, F).
3. Double-delivery pump according to claim 1 or 2, characterized in that the motor (M) is a nonsynchronous single-phase motor and the means for controlling
its direction of rotation consist of a switch which changes the sequence of supply
to the windings.
4. Double-delivery pump according to one or more of the preceding claims, characterized in that the intermediate ring (R') has a central opening (U) shaped with a neck extending
outward to which there is connected a supply duct (L) for supplying water to the internal
chamber (F), said duct (L) being separate from the supply duct connected to the mouth
(K).
5. Dishwasher characterized in that it includes a double-delivery pump according to one or more of the preceding claims.