Field of the invention
[0001] The present invention relates to a laundry-drier machine.
State of the art
[0002] Laundry-drier machines are typically provided with a cabinet, rotatably housed within
which is a drum, designed to contain the laundry to be dried. In some solutions, the
drum has a perforated cylindrical wall and is rotatably mounted within a tank: this
is typically the case of the so-called washer-drier machines, i.e., machines that
enable washing and subsequent drying of a load of laundry. Drier machines in a strict
sense, instead, are not normally provided with a tank. In some solutions, the drum
is constituted by a non-perforated cylindrical wall, associated to which are a front
flange and a rear flange, provided with openings for passage of a flow of drying air.
In other solutions, the drum basically consists of just the cylindrical wall, the
open ends of which are rotatably constrained to respective front and rear containment
elements, with interposition of suitable sliding seal means.
[0003] The machine has a ventilation system, for generating and conveying a forced flow
of air, and heating means, for heating the air of the forced flow. The ventilation
system typically comprises a ducting, associated to which are a fan and the means
for heating the air.
[0004] In the majority of known solutions, the heating means comprise at least one electrical
resistance, but in recent times - mainly for reasons of energy efficiency - there
has been a widespread use of heat pumps.
[0005] Heat-pump machines envisage two substantially closed circuits: the first circuit
is the circuit for the forced air, which is passed over the garments, whilst the second
circuit is the circuit for the coolant, which passes into a compressor set between
an evaporator and a condenser. In said applications, the temperature of the coolant
increases following upon the compression undergone by means of the compressor. The
coolant is then made to pass into a condenser, where it transfers heat to the flow
of forced air, which is thus heated. From the condenser, the coolant passes first
into an expansion valve, which expands and cools the fluid, and then into the evaporator,
to return again to the compressor. The condenser performs the same function of heating
of the flow of air as the one performed by the electrical resistance in the other
known solutions.
[0006] Irrespective of the type of heating means, the fan forces the air into the drum,
via a delivery branch of the ventilation circuit after the air itself has been heated
via heating means. The hot air traverses the inside of the drum and collects the moisture
yielded by the laundry items contained therein, said items being thus progressively
dried. The moist air exits from the drum through its front wall, which is provided
with a central opening, used - in the case of front-loading machines - also for loading
and unloading the laundry.
[0007] In traditional "condensation" machines, the front opening of the drum is in fluid
communication with the intake branch of the ventilation system, upstream of the fan,
along which there is a condenser device designed to extract the moisture from the
air taken in from the drum, said dehumidified air being then re-heated and re-introduced
into the drum via the delivery branch of the system. In heat-pump machines, the corresponding
evaporator is directly exploited to bring about condensation of the moisture of the
air of the forced flow. The water resulting from condensation is collected in a suitable
container, from which, via a pump, it is brought into a container accessible by the
user, for corresponding manual emptying.
[0008] Traditional electrical-resistance machines usually envisage also an open ventilation
circuit, via which fresh air is taken from outside the cabinet of the machine, by
means of a front fan. A duct inside the base of the machine deviates the flow of this
air towards the condenser device. The air thus cools the condenser device and at the
same time exits therefrom slightly heated. This slightly heated air - which can possibly
be exploited to reduce the temperature of the motor of the machine - then exits from
the cabinet from the bottom part of the motor compartment.
[0009] The operating programs that can be executed on the machine according to the known
art are used for drying the items of laundry and, possibly, for reducing bad smells
or creasing of the laundry. These programs generally have a relatively long duration,
of roughly between 30 and 210 minutes. The temperature of the air is in general comprised
between 55°C and 65°C.
[0010] It should be recalled that an operating program is aimed at execution of a cycle
of treatment of laundry items and is made up of a predetermined automatic sequence
of operating steps, which, executed by a control logic, cause passage from a start-of-cycle
state to an end-of-cycle state. To each operating step there corresponds, on the part
of the control logic, activation of determined electrical loads and monitoring of
physical quantities, such as for example the time and/or the humidity and/or the temperature,
representing the current state of execution of the program and designed to determine
the actions of control during execution of the cycle. Start of a program generally
occurs following upon a command imparted by a user, for example by means of a start
button. Starting from the start-of-cycle state the aforesaid predetermined automatic
sequence of operating steps is carried out.
[0011] The end of the program is determined by reaching of a certain predetermined condition
associated to the program itself, detected by the control system of the machine. Said
predetermined condition is typically represented by reaching of a predetermined program
time, or of a temperature of the drying air or of a certain rate of humidity of the
air or moisture of the load of laundry. Passage of the predetermined program time
can be measured by the control unit of the machine, typically provided with an internal
clock of its own, whilst the temperature and/or humidity can be detected via suitable
sensor means belonging to the control system. Once said predetermined condition is
reached, the treatment cycle is completed, and consequently the program goes into
the end-of-cycle state and terminates.
[0012] Laundry-drier machines are also usually provided with a sensor for opening/closing
the door of the machine. In the case where, after starting a drying program, the user
opens the door of the machine - for example, for adding garments to be dried - the
program is interrupted or paused. When the door is reclosed, the program restarts
from the current state at the moment when it was paused, typically by pressing the
start button. It should be noted that the drying process entails rotation of the drum
of the machine at a relatively low speed (roughly comprised between 45 and 55 r.p.m.),
and this causes during running of the program the drum not to have to be blocked in
the closed condition, unlike what occurs in the course of a washing program, where
the speed of rotation of the drum can reach high values, even higher than 1000 r.p.m.
Summary of the invention
[0013] The object of the present invention is basically to provide, in a simple and inexpensive
way, a laundry-drier machine having functions additional to the traditional ones,
for the benefit of the user.
[0014] Said purpose is achieved, according to the present invention, by a laundry-drier
machine and by a method of control of operation of a laundry-drier machine having
the characteristics specified in the annexed claims. The claims form an integral part
of the technical teaching provided in relation to the invention.
Brief description of the drawings
[0015] Further purposes, characteristics and advantages of the invention will emerge clearly
from the ensuing detailed description, with reference to the annexed drawings, which
are provided purely by way of explanatory and non-limiting example and in which:
- Figure 1 is a partial and schematic cross section of a laundry-drier machine according
to the invention;
- Figure 2 is a schematic representation of a control panel of the machine of Figure
1;
- Figure 3 is a simplified diagram of a system for conditioning the air of the machine
of Figure 1, which uses a reversible heat pump;
- Figures 4 and 5 are simplified diagrams representing operation of the reversible heat
pump of the system of Figure 3, in two different operating modes.
Description of preferred embodiments of the invention
[0016] Reference to "an embodiment" or "one embodiment" in the context of the present description
is intended to indicate that a particular configuration, structure, or characteristic
described in relation to the embodiment is comprised in at least one embodiment. Hence,
phrases such as "in an embodiment" or "in one embodiment" and the like, that may be
present in various points of the present description, do not necessarily all refer
to one and the same embodiment. Moreover, the particular configurations, structures,
or characteristics can be combined in any adequate way in one or more embodiments.
The references used in what follows are merely provided for convenience and do not
define the sphere of protection or the scope of the embodiments.
[0017] It is pointed out that in the sequel of the present description, the word "
end", when referred to an operating program or cycle of the machine, indicates a condition
in which all the operating steps envisaged by the program for the purposes of achieving
the specific objective of the program itself have been executed, this corresponding
to a predetermined condition being reached by a monitored quantity, such as time elapsed
and/or moisture content of the garments or humidity of the air and/or temperature
of the air.
[0018] It is moreover pointed out that in the sequel of the present description only the
elements useful for an understanding of the invention will be described in particular
detail, taking for granted that the machine forming the subject of the invention comprises
all the other elements in themselves known for normal operation of a laundry-drier
machine.
[0019] With particular reference to Figure 1, designated as a whole by 1 is a laundry-drier
machine according to the present invention. In the case illustrated, the machine 1
is a drier machine, namely, a machine designed to perform only drying functions, of
the condensation type.
[0020] The machine 1 has a load-bearing structure or cabinet 2, rotatably mounted within
which is a drum 3, designed for containing the laundry. The drum 3 has a generally
cylindrical shape and is mounted for rotating about a substantially horizontal axis
of rotation. Provided within the cabinet 2 are means, of a type in itself known, for
rotatably supporting the drum 3, which can, for example, be of a rolling type, such
as wheels or rollers, or of a sliding type, such as runners.
[0021] The cabinet 2 has a front face, comprising a front wall 2a, having an opening - not
indicated - on which a door 4 is mounted for enabling access to the inside of the
drum 3. In the front face of the cabinet 2, in particular in its upper region, a control
panel or user interface of the machine is provided, designated as a whole by 5. The
panel 5 forms part of a control system of the machine, which includes a control unit
6, preferably of an electronic microcontroller type, prearranged for controlling execution
of a plurality of operating programs of the machine.
[0022] A possible simplified embodiment of the control panel 5 is represented in Figure
2. The panel 5 comprises at least one ON/OFF button, designated by ON, means for selection
and start of one from a plurality of operating programs and, preferably, display means.
In the example, the aforesaid selection and starting means comprise a rotary selector
S with a number of positions and a program-start button R, but other means can obviously
be used for the purpose, such as a series of pushbuttons or a selector with linear
slider with a number of positions. In the example, the display means comprise a display
D, which in possible variant embodiments can be replaced by warning lights. In the
embodiment exemplified, moreover, also provided on the panel 5 are signaling means,
for example, represented by a buzzer, designated by B. It should be noted that a warning
means of an acoustic type can be installed in another position, also inside the cabinet
2, and hence not necessarily on the control panel 5.
[0023] The machine 1 comprises ventilation means, designed for generating a forced flow
of air, and heating means, designed for heating the air of the forced flow.
[0024] In the example of embodiment illustrated, the ventilation means include a substantially
closed path for the air (not indicated), defined in a known way within the cabinet
2, and possibly comprising a hollow part of the door 4. The aforesaid path substantially
extends between an opening of the front wall of the drum 3 and at least one opening
of the rear wall of the drum 3. In Figure 1, the white arrows designated by F indicate
the forced flow along the aforesaid path and through the drum 3. The ventilation means
further comprise a fan 7 that is operative along the aforesaid path and that is preferably
- but not necessarily - driven by the same motor 8 that is to bring about rotation
of the drum 3. Along the path for the air a filter 9, of a conception in itself known,
is preferably provided, which can be inspected by the user of the machine 1.
[0025] In the embodiment exemplified, the means for heating the air include a heat pump
10, which operates along the path for the air and comprises a first heat exchanger
11, a second heat exchanger 12, and a compressor 13, which is operatively set between
the two heat exchangers 11 and 12. The heat pump 10 can possibly include a respective
filter for the air. The heat exchangers can be of any type known in the sector, for
example ones comprising a coil for a working fluid of the heat pump, in particular
a coolant, where the compressor and the heat exchangers are connected in a closed
circuit for said fluid. The path of the air is such that the flow F will be forced
to traverse, or in any case lap, the heat exchangers 11 and 12, for providing a heat
exchange with the coolant of the heat pump 10.
[0026] Once again with reference to the non-limiting example of Figure 1, designated by
14 is a tray for collecting the water produced by condensation of the moisture present
in the air of the forced flow F at output from the drum 3. In the example, associated
to the tray 14 is a pump 14a, which, via a duct 15, takes the condensation water from
the tray 14 to a removable container 16, positioned in the top part of the machine
1. To the container 16 there can be associated an overflow duct, not represented,
in communication with the tray 14 itself.
[0027] According to a characteristic of the invention, the machine 1 comprises change-over
means, designated as a whole by 20 in Figures 1 and 3, which can be controlled by
the control unit 6 for assuming a first operating condition and a second operating
condition, in which the heat pump 10 causes heating and cooling, respectively, of
the air of the forced flow F. The control unit 6 is provided for controlling the change-over
means 20 in order to assume the aforesaid second operating condition following upon
selection of at least one of the operating programs, which can be selected via the
selection means S.
[0028] In the preferred embodiment of the invention, the heat pump 10 is a reversible heat
pump, configured in such a way that:
- when the air of the flow F is to be heated, for example in the course of a typical
drying program, the change-over means 20 are in the respective first operating condition,
with the heat exchanger 11 that operates as evaporator and the second heat exchanger
12 operates as condenser, whilst
- when the air of the flow F is to be cooled, for example in the course of a program
for refreshing the laundry, described hereinafter, the change-over means 20 are in
the respective second operating condition, with the heat exchanger 12 that now operates
as evaporator and the heat exchanger 11 that operates as condenser.
[0029] In the illustrated preferred embodiment, and as will emerge more clearly hereinafter,
the ventilation means of the machine are provided for obtaining a unidirectional forced
flow in such a way that, in both of the operating conditions of the change-over means
20, the forced flow F of air to be heated or cooled, after leaving the drum 3, passes
first through the heat exchanger 11, irrespective of whether the latter at the moment
operates as condenser or as evaporator, and subsequently through the heat exchanger
12.
[0030] In one embodiment, and as may be seen in particular in Figures 4 and 5, the change-over
means 20 include valve means of the heat pump 10, which preferably comprise a four-way
switchable valve 21.
[0031] In its first switching condition (visible in Figure 4), the valve 21 is operative
for directing the frigorific fluid of the heat pump 10 from the heat exchanger 11
to the compressor 13, and from the compressor 13 to the heat exchanger 12.
[0032] In this condition, as already explained above, the heat exchanger 11 operates as
evaporator, and is cold, whilst the heat exchanger 12 operates as condenser, and is
hot. The flow of air F leaving the drum 3 reaches the heat exchanger 11, where condensation
of the corresponding moisture is produced, and then reaches the heat exchanger 12,
for being heated. The condensation water is collected in the tray 14.
[0033] In its second switching condition (visible in Figure 5), the valve 21 is instead
operative for directing the frigorific fluid of the heat pump 10 from the heat exchanger
12 to the compressor 13, and from the compressor 13 to the heat exchanger 11.
[0034] In this condition, there is in practice a reversal of the frigorific cycle, as compared
to the previous case, with the heat exchanger 11 that operates as condenser, and is
hot, whilst the heat exchanger 12 operates as evaporator, and is cold. The flow of
air F leaving the drum 3 reaches the heat exchanger 11, where it heats up, and then
reaches the heat exchanger 12, for being cooled. In this condition, the air leaving
the drum 3 is in any case already relatively cooled air substantially without humidity
(as will emerge hereinafter, the program with cold flow F is used for the treatment
of dry garments).
[0035] Obviously, the heat pump 10 envisages a line of return of the frigorific fluid between
the two exchangers 11 and 12, along which a reduction of pressure of the frigorific
fluid must take place. In the example of embodiment, and as illustrated in Figures
3-5, said line comprises a capillary duct, represented schematically by the block
22, within which the reduction of pressure occurs by lamination of the flow. When
the valve 21 is in the respective first switching condition, the capillary duct 22
enables flow of the frigorific fluid from the heat exchanger 12 to the heat exchanger
11, as may be seen in Figure 4. Instead, when the valve 21 is in the respective second
switching condition, the capillary duct 22 enables flow of the frigorific fluid from
the heat exchanger 11 to the heat exchanger 12.
[0036] As mentioned previously, operation of the heat pump 10 to bring about cooling of
the air of the forced flow F is exploited for the purposes of execution of a program
for refreshing dry laundry, which can be selected via the means S and can be started
via the pushbutton R of the user interface. In the course of said refreshing program,
the valve 21 is in the condition of Figure 5, and the control system of the machine
controls the heat pump 10 for sending and maintaining the air of the forced flow F
at a substantially predetermined temperature, preferably between 5°C and 12°C, for
example approximately 10°C. In this way, it is possible to cool items of laundry contained
in the drum 3 that are already dry.
[0037] The program in question can thus be used to refresh dry garments, for example in
order to render them pleasant to wear, for example in the summer, once they have been
taken out of the drum 3. The same program, or a similar refreshing program, can be
provided for abating the concentration of acari in certain garments or smells of a
load of laundry.
[0038] The operating programs, which can be selected via the selection means S, comprise
treatment programs that terminate when at least one condition arises, which can be
detected by the control system of the machine. As per the known art, the condition
or conditions that determine the end of one of said programs may comprise program
time and/or temperature of the air of the forced flow and/or rate of humidity of the
air of the forced flow or of moisture of the items of laundry. Expiry of the program
time can be conveniently measured by the control unit 6, the microcontroller of which
is equipped with an internal clock of its own, whilst the temperature of the air and
the moisture of the garments can be detected by the unit 6 via purposely provided
sensor means of a type in itself known, represented by the blocks 25a and 25b of Figure
1, which form part of the control system. In the example, the moisture of the items
of laundry is measured by means of a sensor 25b, for example a conductivity sensor,
which operates directly inside the drum so as to come into contact with the garments
themselves.
[0039] According to an important feature of the invention, the operating programs of the
machine comprise at least one program, the end of which is determined by a condition
of the door 4. Consequently, for said purpose, the control unit 6 is programmed to
bring about the end of said further program following upon the detection of the condition
of the door 4 made via sensor means, designated in Figure 1 with 26. The sensor means
26 can, for example comprise, a microswitch, which can switch between a state of closing
and a state of opening, which are obtained when the door is closed or open, respectively.
[0040] The operating program, the end of which depends upon the condition of the door 4,
can, for example, be the refreshing program referred to above. In this perspective,
then, the user can set the dry garment or garments to be refreshed in the drum 3,
close the door 4 and, after turning the machine 1 on and selecting the program via
the selector S, start the program itself by pressing the pushbutton R. The control
unit 6 thus governs the motor 8 in order to bring about rotation of the drum 3 and
start of the fan 7, as well as of the heat pump 10, with switching of the valve 21
into the position of Figure 5. The load of the drum 3 is then progressively cooled,
until a predetermined temperature is reached, for example approximately 10°C, which
can be detected via the sensor means 25a. When said predetermined temperature is reached,
the unit 6 controls the heat pump 10 so as to cause, once again with the aid of the
sensor 25a, a substantial maintenance of the predetermined temperature. According
to a further feature of the invention, the predetermined temperature is then maintained
up to end of the program.
[0041] Preferably, after the aforesaid temperature has been reached the control system (possibly
with pre-set delay time) supplies a warning to the user, for example an indication
of an acoustic or visual type. For this purpose, as has been seen previously, the
machine 1 can be provided with suitable signaling means, represented in the example
of Figure 2 by a buzzer B. Alternatively, or in addition, a signalling of a visual
type is possible, exploiting the display D or other suitable warning means, for example,
of a luminous type. The user, thus informed that the program temperature has reached,
and consequently that the load has been refreshed, can open the door 4 of the machine
when desired, thus determining the end of the program itself, and take out the load.
The warning may, for example, be of a continuous or intermittent type.
[0042] In one embodiment, verification of the state of the door 4 that causes the end of
the program is activated by the control unit 6 only after the predetermined temperature
has been reached. In this way, after start of the program and before the aforesaid
temperature is reached, the user has the possibility of suspending the program temporarily
by opening the door 4 (for example, for adding one or more garments to be refreshed).
Upon reclosing of the door 4, and following upon a restart command by the user, for
example by pressing the button R, the program resumes execution, proceeding from the
current state at the moment of opening of the door. In this embodiment, then, only
opening of the door 4 after a predetermined temperature has been reached causes ending
of the program.
[0043] In general terms, the program proceeds, after start of warning for the user, if the
door 4 is not opened, with the control unit 6 that governs the heat pump 10 so as
to maintain the predetermined temperature of the flow F. In a possible embodiment,
the control logic can be configured for terminating the program when a predetermined
maximum period of time elapses (for example, measured to starting from start of the
program, or from reaching of the predetermined temperature, or from start of the warning
for the user). Until expiry of the aforesaid period, in any case, the heat pump 10
and the fan 7 remain operative for maintaining the predetermined temperature of the
flow F.
[0044] The operating program the end of which depends upon the condition of the door 4 may
also be a program different from the aforesaid refreshing program, such as for example
a program for warming dry laundry, which can also be selected via the means S and
can be started by pressing the pushbutton R of the user interface 5. In the course
of said warming program, the valve 21 is in the condition of Figure 4, and the control
system of the machine governs the heat pump 10 in order to bring and maintain the
air of the forced flow F to a temperature substantially of between 34°C and 38°C,
for example approximately 36°C. The this way, it is possible to warm the items of
laundry that are already dry introduced into the drum 3 or render them tepid. The
program in question can hence be used, for example, for bringing certain garments
up to body temperature, in order to render them pleasant to wear, such as, for example,
in the case of a bathrobe to wear after a bath or a shower. The same program, or a
similar warming program, can be envisaged for warming particular garments are worn
during fitness session for slimming purposes because they increase perspiration (for
example, neoprene garments that, if heated before being worn, accentuate their function).
[0045] Execution of such a warming program is basically performed in a way similar to what
has been described above with reference to the refreshing program, obviously taking
into account that the air of the flow F is in this case heated. Hence, in the course
of the program, the control unit 6 governs the heat pump 10, with switching of the
valve 21 into the position of Figure 4, so as to warm the load of the drum 3 progressively,
in a substantially monotonic/linear way, until a predetermined temperature is reached,
for example approximately 36°C, which can be detected via the sensor means 25a. When
said predetermined temperature is reached, the unit 6 controls the heat pump 10 and
the fan 7 so as to cause a substantial maintenance of the temperature thus reached.
Also in this case, preferably, the control system issues the warning that the predetermined
temperature has been reached, for example via the buzzer B. The user, thus warned
that the load has been warmed, can open the door 4, so bringing about end of the program,
and take out the load. Also in relation to the warming program, the control logic
is configured in such a way that the end of the program occurs upon opening of the
door 4, after the predetermined temperature is reached or else - if the door is not
opened - upon expiry of a predetermined maximum period of time, measured starting
from start of the program, or from reaching of the predetermined temperature, or from
start of the warning for the user.
[0046] It should be emphasized that, in the course of the refreshing program or of the warming
program referred to above, the control system of the machine monitors, via the sensor
means 25a, just the temperature of the air of the forced flow F, without monitoring
humidity: what is important, in fact, for the purposes of warming or refreshing of
the garments to be warn, is the fact that the pre-defined temperature is reached,
which must preferably be maintained util the user brings about end of cycle by opening
the door 4.
[0047] It should moreover be recalled that the typical operating programs envisaged for
drying laundry, here including the drying programs that can be executed by the machine
1, envisage one or more steps in which the air is heated and forced through the drum
3 in order to dry the laundry, and at least one final step, substantially a cooling
step, in the course of which the means for heating the air are inactive and the ventilation
means are, instead, active. This final cooling step of a drying cycle is carried out
mainly because, below a threshold of absolute humidity, it becomes more advantageous
to work by reducing the temperature, in order to have a higher relative humidity and
favour condensation. In practice, in a typical drying cycle, the temperature of the
air is brought up to a value of stability or else to a predetermined value, which
is then maintained via thermostatting for a certain time, considering that when the
garments are almost dry the temperature starts to rise. The program, before terminating,
carries out the aforesaid final cooling step.
[0048] According to a preferential characteristic, instead, in the course of the program
for warming dry laundry described above, the aforesaid final cooling step is absent:
this precisely owing to the fact that the ultimate purpose is to take out the garments
warmed to a substantially predetermined temperature.
[0049] From the description provided, the characteristics of the present invention emerge
clearly, as likewise its advantages.
[0050] The fact that, according to the invention, the end of one or more programs can be
determined by mere opening of the door of the machine, enables reaching and maintenance
of predetermined treatment conditions up to any desired instant, not pre-determined
by the machine, but rather determined by an action of the user.
[0051] In other words, a substantial advantage is that the desired final condition for the
garments (heating or cooling to a certain temperature) is maintained until the user
intervenes directly on the machine by opening its door: instead, in the case where
the program were to terminate at a predetermined time, or when a certain temperature
is reached, the effectiveness of the treatment would be markedly reduced if the user
were to take out the garments from the machine after some delay). A correlated advantage
is the optimization of the duration of the program, and consequently of its energy
consumption, which is adapted to the effective needs of the user: this is obtained
with the minimum of interactions required from the user, limiting said interactions
to opening of the door (which is an action in any case necessary to take out the load
of laundry).
[0052] The fact that, in a preferred embodiment of the invention, the frigorific cycle of
the heat pump can be reversed enables enhancement of the functions of the machine,
to the evident benefit of the users, who can take advantage of new useful programs,
such as the refreshing program described previously.
[0053] The use of a heat pump of a reversible type is particularly advantageous in view
of the fact that it enables implementation in a simple and economic way of both the
aforesaid refreshing program and the aforesaid warming program (as well as the traditional
drying programs). However, it will be appreciated that obtainment of an operating
program with heating of the forced air, whose end is caused by the door opening, can
be implemented also by using air heating means differing from a reversible heat pump,
such as for example a non-reversible heat pump or one or more traditional electric
resistances.
[0054] It is clear that numerous variations may be made by the person skilled in the sector
to the laundry-drier machine described by way example, without thereby departing from
the scope of the invention as defined in the annexed claims.
[0055] In the examples of embodiment described previously, the treatment temperatures for
the refreshing program and for the warming program are temperatures pre-defined by
the program. In possible variant embodiments, it is possible to equip the user interface
of the machine with a purposely provided selector, of a type in itself known, for
enabling the user to set a desired temperature within the range of possible temperatures.
[0056] The invention may, of course, be applied also to machines for washing and drying
laundry, by introducing arrangements that are evident for the person skilled in the
art, taking into account that in this case the laundry drum turns inside a tank.
1. A machine for drying laundry, having a cabinet (2) within which a rotatable laundry
drum (3) is housed, the drum (3) being accessible by a user through a door (4) of
the machine (1), the machine comprising:
- ventilation means (7), adapted for generating a forced flow of air (F), the ventilation
means including one fan,
- heating means (10), adapted for heating air of the forced flow (F),
- a control system (5, 6, 25a, 25b, 26) including a control unit (6), prearranged
for controlling execution of a plurality of operating programs of the machine; and
a user interface (5), having selection means (S) for selecting a desired operating
program among the said plurality of operating programs, wherein the plurality of operating
programs comprises operating programs which end upon achievement of a condition detectable
by the control system (5, 6, 25a, 25b, 26), characterized in that
- the plurality of operating programs comprises at least one first operating program
for which said condition is a condition of the door (4) of the machine (1), the at
least one first operating program being selectable through the selection means (S),
- the control system (5, 6, 25a, 25b, 26) is prearranged for controlling, during the
at least one first operating program, the ventilation means (7) and the heating means
(10) for bringing air of the forced flow (F) to a substantially predetermined temperature,
and then maintaining the air of the forced flow (F) at such a temperature until ending
of the at least one first operating program, and
- the control system (5, 6, 25a, 25b, 26) is prearranged for causing ending of the
at least one first operating program as a result of the detection of the said condition
of the door (4), carried out through corresponding sensor means (26).
2. The machine according to claim 1, wherein the at least one first operating program
comprises at least one of
- a program for warming dry laundry, the control system (5, 6, 25a, 25b, 26) being
in particular configured for bringing the air of the forced flow (F) to, and then
maintaining it at, a temperature substantially comprised between 34 and 38 °C during
the program for heating dry laundry, and
- a program for refreshing dry laundry, the control system (5, 6, 25a, 25b, 26) being
in particular configured for bringing the air of the forced flow (F) to, and then
maintaining it at, a temperature substantially comprised between 5 and 12 °C during
the program for refreshing dry laundry.
3. The machine according to claim 2, wherein the control system (5, 6, 25a, 25b, 26)
is configured for monitoring, during execution of the at least one first operating
program, only the temperature of the air of the forced flow (F), without any monitoring
of the humidity of the air or of the laundry, for the achievement of a determined
temperature of the forced flow (F) and the subsequent maintenance thereof.
4. The machine according to claim 2 or 3, wherein the control system (5, 6, 25a, 25b,
26) comprises signaling means (B, D), for signalling achievement of a determined temperature
of air of the forced flow (F), the signaling means (B, D) comprising in particular
at least one of acoustic signaling means (B) and visual signaling means (D).
5. The machine according to claim 2 or 3, wherein
- the plurality of operating programs comprises laundry treatment programs during
which the ventilation means (7) are active for forcing the forced flow (F) through
the drum (3), with the heating means (10) being active, said treatment programs including
a final step during which the heating means (10) are inactive and the ventilation
means (7) are active, and
- during the said program for warming dry laundry the said final step is absent.
6. The machine according to one of the preceding claims, wherein the control system (5,
6, 25a, 25b, 26) is prearranged for
- counting time, and
- upon expiry of a predetermined time period, causing ending of the said at least
one first operating program,
the control system (5, 6, 25a, 25b, 26) being in particular prearranged for maintaining
air of the forced flow (F) at a substantially predetermined temperature until expiry
of the above said predetermined time period.
7. The machine according to claim 1, wherein the heating means include one heat pump
(10) having one first heat exchanger (11), one second heat exchanger (12) and one
compressor (13) operatively arranged between the first and the second heat exchanger
(11, 12).
8. The machine according to claims 2 and 7, also comprising change-over means (20), controllable
by the control unit (6) to take on one first operating condition and one second operating
condition, for obtaining from the heat pump (10) heating or cooling of air of the
forced flow (F), respectively, and wherein the control unit (6) is prearranged for
controlling the change-over means (20) to take on the second operating condition as
a result of the selection of the program for refreshing dry laundry.
9. The machine according to claim 8, wherein the heat pump is a reversible heat pump
(10), and wherein
- in the first operating condition of the change-over means (20), the first heat exchanger
(11) operates as an evaporator and the second heat exchanger (12) operates as a condenser,
and
- in the second operating condition of the change-over means (20), the first heat
exchanger (11) operates as a condenser and the second heat exchanger (12) operates
as an evaporator.
10. The machine according to claim 9, wherein the ventilation means (7) are prearranged
for generating a unidirectional forced flow, in such a way that, in both the operating
conditions of the change-over means (20) the forced flow (F) of air to be heated or
cooled, respectively, after exiting the drum (3) passes first through the first heat
exchanger (11) and then through the second heat exchanger (12) of the heat pump (10).
11. The machine according to claim 9 or 10, wherein the change-over means (20) include
valve means (21) of the heat pump (10), switchable between one first and one second
switching condition, and wherein:
- in the first switching condition the valve means (21) are operative for addressing
a work fluid, or refrigerant, of the heat pump (10) from the first heat exchanger
(11) to the compressor (13) and from the compressor (13) to the second heat exchanger
(12), and
- in the second switching condition the valve means (21) are operative for addressing
the work fluid of the heat pump (10) from the second heat exchanger (12) to the compressor
(13) and from the compressor (13) to the first heat exchanger (11),
where in particular the valve means comprises a four-way valve (21).
12. The machine according to claim 11, wherein the heat pump (10) also comprises a return
line (22) of the flow of the work fluid of the heat pump (10), arranged for allowing:
- a flow of the work fluid from the second heat exchanger (12) to the first heat exchanger
(11), when the valve means (21) are in the respective first switching condition, and
- a flow of the work fluid from the first heat exchanger (11) to the second heat exchanger
(12), when the valve means (21) are in the respective second switching condition,
where in particular the return line (22) comprises at least one capillary duct adapted
to cause lamination of the work fluid of the heat pump (10).
13. A method for controlling operation of a machine for drying laundry (1) of the type
in which air of a forced flow (F) is made to pass through a laundry drum (3), the
method comprising selection, through selection means (S), of one of a plurality of
operating programs whose execution is controlled by a control system (5, 6, 25a, 25b,
26), each operating program ending upon achievement of a condition detectable by the
control system (5, 6, 25a, 25b, 26), wherein, for at least one first operating program,
the said condition is a condition of a door (4) of the machine (1), detectable through
corresponding sensor means (26) belonging to the control system (5, 6, 25a, 25b, 26),
during the at least one first operating program air of the forced flow (F) being brought
to a substantially predetermined temperature, which temperature is then maintained
until ending of the at least one first operating program.
14. The method according to claim 13, wherein the at least one first operating program
comprises at least one of
- a program for warming dry laundry, particularly during which air of the forced flow
(F) is brought to, and then maintained at, a temperature substantially comprised between
34 and 38 °C,
- a program for refreshing dry laundry, particularly during which air of the forced
flow (F) is brought to, and then maintained at, a temperature substantially comprised
between 5 and 12 °C.
15. The method according to claim 13 or 14, wherein, during execution of the at least
one first operating program, only the temperature of the air of the forced flow (F)
is monitored, without any monitoring of the humidity of the air or of the laundry,
for the achievement of a determined temperature of the forced flow (F) and the subsequent
maintenance thereof.