[0001] The present invention relates to a rotary-drum laundry-drying machine for domestic
use, of the type including:
a support casing,
a cylindrical drum mounted for rotation about its axis within the support casing and
having a loading opening for the laundry situated in correspondence with a door with
which the support casing is provided,
means for rotatably driving the rotary drum,
means for supplying a flow of hot air to the interior of the rotary drum at one end
thereof,
means for discharging the air from the rotary drum at the end thereof opposite the
end to which the air is supplied,
filtering means for filtering the air leaving the rotary drum, including a perforated
filtering wall facing the interior of the rotary drum, whereby, in operation, the
laundry contacts this wall removing therefrom the filtered out material.
[0002] A laundry-drying machine of the type specified above is described and illustrated
in German Utility Model No. 71 17 075. The perforated filtering wall with which this
machine is provided is able to retain the fluff which forms within the rotary drum
during the drying cycle, preventing its discharge to the external environment. At
the same time, the rubbing of the laundry on this perforated filtering wall during
the drying cycle prevents this filtering part from becoming covered with fluff and
the air flow therethrough being reduced. This would in fact cause an increase in the
time needed for the drying cycle, an increase in the working temperature of the machine
and, in conclusion, a reduction in the drying efficiency and an increase in the energy
consumption.
[0003] However, in the laundry drying machine described and illustrated in the German Utility
Model cited above, the fluff removed from the perforated filtering wall as a result
of the contact of the laundry with this wall returns into circulation in the rotary
drum whereby, during the drying cycle, it continues to be deposited on this wall reducing
the efficiency of the cleaning action of the laundry. Moreover, when the dried laundry
is removed from the machine at the end of the cycle it is covered with fluff.
[0004] The object of the present invention is to provide a laundry drying machine of the
type specified above which allows the said disadvantages to be avoided.
[0005] In order to achieve this object, the invention provides a laundry drying machine
of the type specified above, which is characterised in that the said filtering means
further include an auxiliary perforated filtering wall disposed so as to be traversed
in parallel with the main perforated filtering wall by the air leaving the rotary
drum, and in that this auxiliary perforated filtering wall is situated in a position
which cannot be reached by the laundry, so as to collect the material which has been
filtered out by the main filtering wall and subsequently removed therefrom by the
laundry.
[0006] In operation, the fluff which forms during the drying cycle is deposited partly on
the main perforated filtering wall and partly on the auxiliary perforated filtering
wall.
[0007] The fluff which is deposited on the main perforated filtering wall is removed by
the laundry within the rotary drum and is conveyed by the drying air flow towards
the auxiliary perforated filtering wall, which is traversed by this flow in parallel
with the main perforated filtering wall. Thus the main perforated filtering wall always
remains clean, guaranteeing an air flow which is sufficient for efficient drying.
At the same time, the auxiliary perforated filtering wall, which is situated in such
a position that the laundry cannot come into contact with it, collects the fluff removed
from the main perforated filtering wall preventing this fluff from re-entering into
circulation in the rotary drum. As a result of this characteristic, therefore, during
the drying cycle, the main perforated filtering. wall remains constantly clean, and
at the end of the cycle, the dried laundry removed from the machine is not covered
with fluff. Preferably the auxiliary perforated filtering wall is releasably mounted
in the machine to facilitate its cleaning at the end of the cycle.
[0008] Further characteristics and advantages of the present invention will emerge from
the description which follows with reference to the appended drawings, provided purely
by way of non-limiting example, in which:
Figure 1 illustrates a schematic section, in side elevation, of a laundry-drying machine
according to the present invention,
Figure 2 illustrates schematically a frontal section of the machine of Figure 1,
Figure 3 is a diagram which illustrates the operational characteristics of the machine
of Figure 1, and
Figures 4 to 6 illustrate variants of Figure 1.
[0009] In the drawings, the parts common to the various embodiments of the machine according
to the present invention have been indicated by the same reference numerals.
[0010] In Figure 1, a rotary drum laundry-drying machine for domestic use is generally indicated
1, the machine comprising a support casing 2 within which is rotatably mounted a cylindrical
drum 3. The drum 3 has a laundry loading opening 4 situated in correspondence with
a door 5, in the form of a porthole, with which the support casing 2 is provided.
[0011] The laundry-drying machine 1 is provided with means of a type known per se, not illustrated,
for r'otat- ably driving the rotary drum 3 about its axis (which is indicated by the
line X-X of Figure 1).
[0012] In its wall opposite that provided with the door 5, the support casing 2 has a series
of apertures 6 for" drawing air into the interior of a passage 7. The passage 7 communicates
with the interior cavity 8 of the rotary drum 3 through a series of perforations 9
formed in the back wall of the drum 3, that is, the wall opposite the loading opening
4.
[0013] An electrical heating resistance 10 is positioned in the passage 7.
[0014] The interior cavity 8 of the rotary drum 3 communicates through the loading opening
4 with a passage 11 connected to a duct 12 for discharging air from the machine. A
suction fan 13 for causing forced circulation of air through the interior of the machine
is disposed in the duct 12.
[0015] In correspondence with the loading opening 4 of the rotary drum 3, the machine is
provided with filtering means operable to separate from the air leaving the rotary
drum the particles of fluff which form during the drying cycle.
[0016] The said filtering means are constituted by a main perforated filtering wall 14 and
an auxiliary filtering wall 15.
[0017] The main filtering wall is constituted (see Figure 2) by a curved wall in the form
of a C with its opening facing downwardly, coaxially surrounding the loading opening
4 of the rotary drum 3.
[0018] The door 5 with which the support casing 2 is provided has an internal, frusto-conical
bell shape 16 such as to permit the laundry contained in the rotary drum 3 to come
into contact with the wall 14 during the drying cycle.
[0019] The auxiliary filtering wall is constituted by a trap element located below the wall
14 and having an inlet mouth of rectangular form the two smaller sides of which are
adjacent the ends of the curved wall 14. The trap element 15 is located within the
duct 11 and is releasably fixed to the wall 14.
[0020] Preferably moreover the mouth of the trap element 15 is provided with transverse
elements 15b arranged to prevent the penetration of the smaller items of laundry into
the trap element 15 and usable for grasping the trap element 15 in order to extract
it from the machine. In operation, the fluff which forms during the drying cycle is
deposited partly on the perforated filtering wall 14 and partly in the trap element
15. The fluff deposited on the wall 15 is removed from this latter by the action of
the laundry itself,
'contained in the rotary drum 3, which, during the drying cycle, comes into contact
with the wall 14. The fluff removed from the wall 14 is carried away into the trap
element 15 by the flow of air which traverses the rotary drum 3. In this way the filtering
wall 14 always remains clean and, since its effective area is much greater than that
of the trap element 15, the filling of this latter with fluff does not significantly
alter the rate of flow of drying air.
[0021] After each drying cycle the trap element 15 can be removed from the machine to be
cleaned of fluff.
[0022] Figure 3 is a diagram in which the values of the air flow rate are plotted as a function
of time for one drying cycle of the laundry-drying machine.
[0023] The line indicated A relates to a laundry-drying machine according to the invention,
whilst the line indicated B relates to a laundry-drying machine of known type provided
with a single filtering wall of cylindrical form positioned coaxially adjacent the
load ing aperture of the rotary drum of the machine. The time t
0 corresponds to the beginning of the drying cycle. The points in time when the drying
cycles of the two laundry-drying machines used for the test are completed have been
indicated t
A and t
B respectively.
[0024] Figure 3 shows that by using a machine of the known type the rate of flow of air
progressively reduces during the course of the drying cycle. By using instead the
machine according to the present invention the air flow remains substantially constant
for the whole cycle. Thanks to this characteristic the time necessary to effect the
drying cycle is reduced.
[0025] The single difference between the machine of Figure 1 and the machine illustrated
in Figure 4 is that in this latter the main filtering wall is constituted by a disc
140 extending perpendicularly to the axis X-X of the rotary drum in correspondence
with the door 5, the air which traverses the wall 140 being carried away in the duct
11a arranged in parallel with the duct 11.
[0026] In operation, the laundry contained in the rotary drum 3 comes into contact with
the filtering wall 140 removing the fluff deposited on this latter and avoiding, in
this way, a reduction in the rate of flow of air during the drying cycle. In this
case also the trap element 15 collects the fluff removed from the wall 140 and can
be taken out to be cleaned at the end of the cycle.
[0027] The machine illustrated in Figure 5 differs from the machine illustrated in Figure
4 by the fact that the main filtering wall, is constituted by a cylindrical wall 18
disposed coaxially adjacent the loading aperture 4 of the rotary drum 3, and by the
fact that the auxiliary filtering wall is constituted by a perforated disc 19 arranged
perpendicularly with respect to the axis X-X of the rotary drum 3 in correspondence
with the door 5. A perforated spacer wall 20 is arranged over the door 5 to prevent
the laundry contained in the rotary drum 3 from coming into contact with the perforated
disc 19 during the course of the drying cycle. The perforations in the wall 20 are
sufficiently wide to allow the fluff to pass through this wall.
[0028] In operation, the laundry comes into contact with the cylindrical wall 18 removing
the fluff deposited on it. In this way the wall 18 constantly remains clean and the
rate of flow of air is maintained substantially constant throughout the course of
the drying cycle. The fluff removed by the action of the laundry from the cylindrical
wall 18 is carried by the flow of air which traverses the rotary drum 3 onto the apertured
disc 19 which, at the end of the cycle, can be removed to be cleaned.
[0029] The main difference between the laundry-drying machine illustrated in Figure 6 and
the machine illustrated in the'preceding Figures lies in the fact that in the case
of Figure 6 the main filtering wall is constituted by a perforated disc 140 positioned,
in correspondence with the door 5, perpendicularly with respect to the axis X-X of
the machine. The auxiliary filtering wall is constituted, on the other hand, by a
cylindrical wall
18 disposed coaxially to the rotary drum 3 adjacent the loading aperture 4 of the rotary
drum. The door 5 has a cylindrical wall adjacent the wall 18 so as to prevent, during
operation, the laundry contained in the rotary drum 3 from coming into contact with
the wall 18.
[0030] In operation the laundry comes into contact with the apertured disc 140 removing
from this latter the fluff deposited on it. In this way the rate of flow of air remains
substantially constant, whilst the fluff is carried by the flow of air which traverses
the rotary drum, onto the auxiliary filtering wall 18 which can be cleaned at the
end of the cycle after the door has been opened.
[0031] Naturally, the principle of the invention remaining the same, the details of construction
and the embodiments may be varied widely with respect to those described and illustrated
purely by way of example without thereby departing from the scope of the present invention.
1. A rotary drum laundry-drying machine, comprising:
a support casing (2),
a cylindrical drum (3) mounted for rotation about its axis (X-X) within the support
casing (2) and having a loading aperture (4) for the laundry situated in correspondence
with a door (5) with which the support casing (2) is provided,
means for rotatably driving the rotary drum,
means (13, 10) for supplying a flow of hot air to the interior of the rotary drum
(3) at one end thereof,
means for discharging air out from the rotary drum (3) at the end thereof which is
opposite the end to which air is supplied,
filtering means for filtering the air leaving the rotary drum (3), including
a main perforated filtering wall (14, 140, 18) facing into the interior (8) of the
rotary drum (3) so that, in operation, the laundry comes into contact with this wall
removing from it the filtered out material,
characterised in that the said filtering means further include an auxiliary perforated
filtering wall (15, 19, 18) disposed so as to be traversed in parallel with the main
perforated filtering wall ( 14, 140, 18) by the air leaving the rotary drum (3) and
in that the auxiliary perforated filtering wall (15, 18, 19) is situated in a position
which cannot be reached by the laundry, so as to collect material which has been filtered
out by the main filtering wall and subsequently removed therefrom by the laundry.
2. Laundry drying machine according to Claim 1, characterised in that the said main
filtering wall is constituted by a curved perforated wall (14) of substantially C-shape
conformation with the opening facing downwardly, arranged coaxially adjacent the loading
aperture (4) of the rotary drum (3) of the machine, and in that the said auxiliary
filtering wall is constituted by a trap element (15) positioned below the said C-shaped
wall (14) and having an inlet opening (15a) situated in correspondence with the opening
of the C.
3. Laundry drying machine according to Claim 1, characterised in that the said main
filtering wall is constituted by a perforated disc (140) arranged in correspondence
with the loading aperture (4) of the rotary drum (3), perpendicularly with respect
to the axis (X-X) of this latter, and in that the said auxiliary filtering wall is
constituted by a trap element (15) arranged below the said perforated filtering disc
( 140 ) .
4. Laundry drying machine according to Claim 1, characterised in that the said main
filtering wall is constituted by a perforated cylindrical wall (18) coaxially surrounding
the loading aperture (4) of the rotary drum (3) of the machine, and in that the said
auxiliary filtering wall is constituted by a perforated disc (19) extending perpendicularly
with respect to the axis (X-X) of the rotary drum (3), the aid machine further comprising
a perforated spacer wall (20) interposed between the said perforated filtering disc
(19) and the interior cavity (8) of the rotary drum (3).
5. Laundry drying machine according to Claim 1, characterised in that the said main
filtering wall is constituted by a perforated filtering disc (140) arranged adjacent
the loading aperture (4) of the rotary drum (3), perpendicularly with respect to the
axis (X-X) of this latter, and in that the said auxiliary filtering wall is constituted by
a perforated cylindrical wall (18) coaxially surrounding the loading aperture (4)
of the rotary drum (3).