Laundry washing and drying machine with improved heater

A laundry washing machine includes a wash tub, a basket for receiving laundry and mounted for rotation within the wash tub, a recirculating duct extending from the bottom of the wash tub to an upper portion thereof, and a pump for recirculating the washing liquid through the duct from the bottom of the wash tub to the upper portion thereof. A housing is attached to the top of the wash tub to define a chamber, and the duct extends into the housing such that the washing liquid pumped by the pump through the duct is discharged into the chamber. Heater elements are located within the chamber to thereby heat the washing liquid discharged into the chamber. The interior of the chamber communicates with the interior of the wash tub through an overflow weir. The machine further may include an air drying circuit whereby air is recirculated through an air duct by means of a fan from the bottom of the wash tub to the chamber, wherein the recirculated air is heated by the heating elements.

BACKGROUND OF THE INVENTION 
The present invention relates to an electric laundry washing machine, 
particularly for domestic use, wherein a wash liquor or washing liquid is 
caused to recirculate through the wash tub to wet the laundry therein to 
carry out a washing operation with considerable savings in use of water, 
detergent and energy. 
A laundry washing machine of this general principle would also adapt to 
perform the traditional washing cycles by soaking the laundry as described 
in European Patent Application No. 0,146,719. Such washing machine 
includes a wash tub with a basket receiving laundry and mounted for 
rotation within the wash tub, and a container or sump is connected to the 
lower portion or bottom of the wash tub and collects therefrom the washing 
liquid which is to be recirculated back to an upper portion of the wash 
tub. Within the container or sump are located electrical resistor heaters 
for heating the washing liquid. A pump then withdraws the thus heated 
washing liquid from the container or sump and passes it through a conduit 
or duct that leads into the upper portion of the wash tub to thereby 
discharge the heated washing liquid into the wash tub to wet the laundry 
within the perforated basket spinning within the wash tub. 
This known washing machine, although functionally correct, can be improved 
structurally with regard to the hydraulic circuit thereof, and also can be 
supplemented conveniently with a drying circuit so as to provide for a 
more complete processing of the laundry. Indeed, the positioning of the 
container or sump for collection of the washing liquid in the lower part 
of the machine results in assembly problems, given the necessary limited 
space available due to the small and standardized dimensions of domestic 
washing machines. Furthermore, filtering devices and controls are 
necessary in order to prevent lint and mineral deposits that are damaging 
to the electrical resistor heaters from being accumulated in the container 
or sump. Accordingly, it would preferably to position the collecting 
container or sump at the upper part of the washing machine. Indeed, a 
solution of this general type was proposed in 1910 in German Pat. No. 
234,908. However, in such known arrangement, the container or tank for 
collecting and heating the washing liquid is provided externally of the 
washing machine, and the washing liquid passes therethrough from top to 
bottom, reentering the tub through a hollow shaft of the basket. 
In addition to the complex and bulky construction of this machine, which 
indeed is not feasible with regard to domestic washing machines, this 
arrangement has additional inherent and serious disadvantages. Indeed, a 
heavy consumption of energy is necessary in order to sufficiently heat the 
water flowing continuously through the collecting container or tank, 
unless closure valves are provided between the collecting tank and the 
wash tub. Furthermore, the hydraulic pressure losses along the connecting 
pipes between the collecting tank and the wash tub reduce substantially 
the efficiency of the jets of washing liquid issuing from sprinklers 
disposed along the jacket of the basket containing the laundry. Finally, 
this known machine does not provide any capability of drying the laundry. 
More recently, there have become known machines of the combined washing and 
drying type wherein laundry is not only washed, but also is dried. 
However, in such known machines, washing is effected in a traditional 
manner with the soaking of the clothes, and the washing and drying 
circuits usually are separated, except for the possible use of water from 
the water supply main also being employed for condensing water vapor 
resulting from the drying operation. Hence, machines of this type are 
complex structurally and are not economical from an operational point of 
view. One such machine is disclosed in U.S. Pat. No. 4,154,003. The recent 
development of recirculation-type laundry washing machines, in which 
heating elements are disposed externally of the wash tub, affords the 
possibility of the advantageous construction of a combined appliance for 
washing and drying of laundry. 
SUMMARY OF THE INVENTION 
With the above discussion in mind, it is an object of the present invention 
to provide a laundry washing machine of the above type but wherein heating 
of the washing liquid is achieved in an improved manner. 
It is a further object of the present invention to provide such a laundry 
washing machine of improved design and construction and which is capable 
of more efficient operation than known machines. 
It is a yet further object of the present invention to provide such a 
laundry washing machine which also may be modified to enable the machine 
to also dry laundry. 
These and other objects of the present invention are achieved by the 
provision of a laundry washing machine including a wash tub, a basket for 
receiving laundry and mounted for rotation within the wash tub, a 
recirculating duct extending from the bottom of the wash tub to an upper 
portion thereof, pump means for recirculating washing liquid through the 
duct from the bottom of the wash tub to the upper portion thereof, and 
electrical resistor heating means located externally of the wash tub for 
heating washing liquid prior to passage thereof to the upper portion of 
the wash tub. In particular accordance with the present invention, a 
housing is attached to the top of the wash tub to define a chamber. The 
recirculating duct extends into the housing such that washing liquid 
pumped by the pump means through the duct is discharged into the chamber. 
The electrical resistor heating means is located within the chamber. 
Means, positioned within the chamber and connected to the interior of the 
wash tub, defines a weir for the overflow of washing liquid collected into 
the chamber into the interior of the wash tub. In other words, in 
accordance with the present invention, the washing liquid is heated just 
prior to its recirculation back into the wash tub, thereby avoiding any 
substantial heat loss or dissipation. 
In further accordance with the present invention the washing machine may be 
supplemented with an arrangement for drying of the laundry. Thus, there is 
provided a fan for recirculating air from the bottom of the wash tub back 
to the upper portion thereof through the chamber. Specifically, an air 
duct extends from the bottom of the wash tub to the chamber, and the fan 
is located within the duct to recirculate air back to the chamber and then 
into the upper portion of the wash tub. The recirculated drying air is 
heated in the chamber by the electrical resistor heating means.

DETAILED DESCRIPTION OF THE INVENTION 
One embodiment of a laundry washing machine according to the present 
invention is illustrated in FIG. 1. The machine includes a cabinet 10 
within which is mounted a wash tub 11. A basket 12 for receiving laundry 
is mounted for rotation within wash tub 11. Cabinet 10 requires no 
modification from commercially available and conventional cabinets and may 
correspond to standardized dimensions. Basket 12 is mounted within wash 
tub 11 to spin or rotate therein by means of conventional support and 
drive arrangements. On the other hand, wash tub 11 is modified in 
accordance with the present invention. Thus, to the exterior top of wash 
tub 11 is fastened a housing 15 which defines therein a chamber 13. The 
housing may be made from the same material as wash tub 11, for example 
stainless steel, and preferably is welded thereto. In the central zone of 
chamber 13, at the peak or apex of wash tub 11, is provided at least one 
vertical pipe 16 which causes chamber 13 to communicate freely with the 
interior of wash tub 11. Conduit or pipe 16 forms a weir for the overflow 
of washing liquid collected within chamber 13 into wash tube 11. This 
washing liquid penetrates through perforations in the jacket of basket 12 
to thereby wet laundry positioned therein. 
The bottom of wash tub 11 is provided with a port 17 connected via a pipe 
18 to a drain pump 19 which is operable during a discharge cycle of the 
machine to discharge washing liquid from the bottom of wash tub 11 through 
a drain pipe 20, for example at the end of each washing cycle. Drain pump 
19 or pipe 18 also is connected via a conduit 21 to a recirculation pump 
22 which passes washing liquid from the bottom of wash tub 11 to chamber 
13 via recirculation pipe 23. Thus, pipes 18, 21, 23 define a 
recirculation duct through which washing liquid is recirculated from the 
bottom of wash tub 11 to chamber 13 by means of pump 22. 
Recirculation pipe 23 includes a discharge end length portion 24 which 
extends to a position in close proximity to the bottom of chamber 13. As a 
result, end portion 24 thereby forms a siphon which may be used to remove 
washing liquid collected in chamber 13. Thus, at particular times during 
the washing cycle it is desirable to withdraw washing liquid from chamber 
13, for example when pump 22 stops pumping. This makes it possible to 
ensure that chamber 13 is kept clean, thereby preventing water stoppages 
and deposits of lint and deposits within chamber 13. This is particularly 
important in view of the fact that electrical resistor heaters 14 for 
heating the recirculating washing liquid are located within the interior 
of chamber 13. As a result, the washing liquid is heated shortly before 
discharge into the washing tub, thereby avoiding heat loss or dissipation. 
FIG. 1 shows the conventional arrangement for initial supply of water to 
the wash tub. Thus, the water supply is from a water main connected to a 
detergent distributor 25 which is connected to the interior of wash tub 11 
by a conduit or flexible sleeve 26. Distributor 25 preferably is housed in 
the upper part of cabinet 10. 
FIG. 2 illustrates a modified embodiment of the present invention which 
however is based on the same basic operating principle as the embodiment 
shown in FIG. 1. Thus, in FIG. 2 the structure of the machine and 
operation thereof is somewhat simplified, since there is employed a single 
pump 35 in place of the two pumps 19, 22 employed in the embodiment of 
FIG. 1. Single pump 35 operates to achieve both the functions of draining 
and recirculation of washing liquid. In this arrangement, a valve, such as 
a two-way deflector valve 36, is located in pipe 23 to selectively control 
the discharge of washing liquid pumped by pump 35 to chamber 13 or to 
drain pipe 20. 
All other components of the embodiment of FIG. 2 are similar to those of 
the embodiment of FIG. 1, and therefore further description and 
explanation thereof are not necessary. In both of the embodiments of FIGS. 
1 and 2, the machine will be provided with additional conventional 
components, for example filters, pressure switches, programmer, etc., 
which are not shown or described herein, since they are of per se known 
and conventional structure and do not form any portion of the present 
invention. 
FIGS. 3 and 4 illustrate the machines of FIGS. 1 and 2, respectively, but 
modified to enable, in addition to laundry washing, drying of the laundry. 
Thus, FIG. 3 illustrates a combined washing and drying machine in which the 
washing and drying functions are integrated due to the provision of the 
particular recirculation type washing system of the present invention 
which provides the chamber 13 in which are located the electrical 
resistance heating elements. Thus, the hydraulic portion of the machine of 
FIG. 3 corresponds to that of FIG. 1. However, in addition there is 
provided a drying circuit. Thus, to the lower port 17 at the bottom of 
wash tub 11 is connected an air pipe 27 within which is located an air 
recirculating fan 28 at a position in the upper portion of cabinet 10 and 
connected to chamber 13 via a conduit 29. Accordingly, fan 28 recirculates 
air from the bottom of wash tub 11 to chamber 13 and from there back into 
the upper portion of wash tub 11. Preferably, chamber 13 is provided with 
an additional air circulation conduit or duct 30 leading from the top of 
chamber 13 into the interior of wash tub 11. 
In accordance with this embodiment of the present invention, washing and 
drying of laundry is achieved by washing and drying circuits which are 
integrated into a single machine. The washing circuit includes tub 11, 
drain pump 19, recirculation pump 22 and chamber 13. On the other hand, 
the drying air circuit includes tub 11, fan 28 and chamber 13. Electrical 
resistor heating elements 14 are located in chamber 13 and are employed 
for heating both the washing liquid and the drying air prior to the 
introduction thereof into the upper portion of the wash tub 11. 
The embodiment of FIG. 3 includes an additional feature. Thus, a nozzle 31 
extends into air duct 27 at a position upstream of fan 28 to supply water 
into air duct 27 to condense any water vapor from the air which is 
withdrawn from wash tub 11 by fan 28. Nozzle 31 may be connected to the 
hydraulic supply network, i.e. to the source of water. Water injected by 
nozzle 31 into duct 27 condenses water vapor from the air being circulated 
therethrough. This condensate falls down along duct 27 and is discharged 
by means of drain pump 19. Thus, this embodiment of the present invention 
enables the provision of a combined laundry washing and drying machine 
which is simplified and much more practical than known machines, thus 
making it particularly suitable for domestic use, while making possible 
savings of water, detergent and energy, both during the drying and washing 
cycles. 
FIG. 4 illustrates a modification of the arrangement of FIG. 3, but adapted 
to the machine of FIG. 2. It is believed that the operation of the 
embodiment of FIG. 4 will be apparent from the above discussion of the 
operation of the embodiments of FIGS. 2 and 3. 
In accordance with the present invention, it is possible to provide a 
washing machine which achieves effective and efficient integration of the 
circulation and heating of the washing liquid to maximize wetting of the 
laundry. The container defining chamber 13 is secured to the exterior top 
or ceiling of wash tub 11 and contains electrical resistor heating 
elements 14, and this achieves improved heating of the washing liquid 
which is substantially immediately supplied to the laundry without heat 
loss or dissipation. As a result, the solution of the present invention 
further reduces the consumption of energy and ensures better cleaning and 
protection of the heating elements. Furthermore, in accordance with the 
present invention, it is possible to supplement the washing machine with 
drying capability without requiring any substantial modification of the 
basic washing machine. The machine of the present invention can be of the 
front loading or of the top loading type without modifying the basic 
structure and dimensions of the respective types of machines. 
Although the present invention has been described and illustrated with 
respect to preferred embodiments thereof, it is to be understood that 
various changes and modifications may be made to the specifically 
described and illustrated features without departing from the scope of the 
present invention.