The present invention relates to a domestic washer-drier machine which provides for washing and drying the laundry.
Domestic washer-drier machines are known to comprise a support and housing structure, a washing tank being housed therein, which is provided with a front opening that can be closed by means of a porthole door that is hinged in front of the housing. Within the washing tank, a basket is pivotally housed about a horizontal or inclined axis for the laundry to be accommodated therein to be washed and/or dried. The basket also defines a front opening that is located such as to match the opening of the washing tank, in order to load/unload the laundry.
The washing tank is suitable to contain the washing liquid during the laundry washing steps, and to be a portion of the drying circuit during the laundry drying step.
In order to allow loading the tank with mains water and detergent and additive substances, a washing water delivery system is provided to be connected to the water system. This washing water delivery system comprises a plurality of electrovalves which are suitable to selectively adjust the supply to a plurality of flow paths extending downstream of these electrovalves through respective compartments of a detergent tray to the washing tank. On the bottom of the washing tank there is provided a drain duct with a discharge pump being associated thereto, which provides for the removal of the washing liquid from the tank and controls, together with the supply electrovalves, the liquid level within the tank. To heat the washing liquid contained within the tank, an electric resistance is provided, which is arranged within the tank in the gap between the tank wall and the laundry basket.
The drying circuit of prior art washer-drier machines typically comprises a suction unit, a heat exchanger and a heating unit with electric resistances intercommunicating by means of a drying circuit.
In such a closed-loop circuit, the air flow generated by the suction unit is heated by the electric resistances and sent to the basket, where it flows through the wet laundry thereby causing the water contained in the fabric to evaporate. In the heat exchanger, which is generally a container separate from the washing tank and provided with a spray nozzle, the wet air is cooled by a jet of cold water. Due to this cooling, the vapour condensates and is collected and discharged together with the cooling water. The de-humidified air is then sucked again by the suction unit and ricirculated.
The cooling water is usually supplied to the heat exchanger by means of a cooling duct with a dedicated electrovalve which controls the loading of the mains water in the heat exchanger (condenser).
Prior art drying devices, while being satisfactory under many aspects, however, have a much complicated structure which is due to the presence of the condensation chamber and three different circuits:
The structural complexity of known washer-drier machines and the high consumption of cooling water during the drying step are some of the causes of the high production and running costs that are related to this type of appliance.
The object of the present invention is thus to provide a washer-drier machine having such characteristics as to reduce the consumption of mains water during the drying step.
Within the above general object, a further object of the present invention is to simplify the structure of the washer-drier machine and reduce the number of hydraulic components thereof.
This and other objects are achieved by means of a washer-drier machine according to claim 1. Advantageous embodiments are the object of the dependent claims.
According to the invention, the washer-drier machine comprises a laundry basket that is supported within a washing tank suitable to contain the washing liquid, in which the washing tank internally defines a condensation space suitable to contain a cooling water volume forming a free water surface spaced away from the basket such as to be capable of cooling the drying air flow downstream of the basket within the washing tank.
Thereby, the whole supply circuit of the condenser can be eliminated, as the latter can be easily supplied with mains water loaded by the washing water loading circuit, since it consists of a free surface of a water volume within the washing tank.
In addition, since a cooling water volume is maintained within the washing tank, a continuous use of a same water volume will be allowed until the latter reaches an upper threshold temperature for condensation purposes. This results in a considerable saving of cooling water during the drying step.
In accordance with a further important aspect of the invention, the operation of the washer-drier machine is controlled by a program which carries out, during the drying step, the following actions:
In order to better understand the present invention and appreciate the advantages thereof, several embodiments thereof will be described below by way of non-limiting example, with reference to the annexed drawings, in which:
With reference to the figures, a washer-drier machine 1 comprises a support and housing structure 2, a washing tank 3 being housed therein, which is provided with a front opening that can be closed by means of a porthole door 4 being hinged in the front of the housing 2. Within the washing tank 3, a basket 5 is pivotally housed about a horizontal or inclined axis, for the laundry to be accommodated therein to be washed and/or dried. The basket 5 also defines a front opening that is located such as to match the opening of the washing tank 3, in order to load/unload the laundry.
The washing tank 3 is suitable to contain the washing liquid during the laundry washing steps, and to be a portion of the drying circuit during the laundry drying step.
In order to allow loading the tank 3 with mains water and detergent and additive substances, a washing water delivery system is provided to be connected to the water system. This washing water delivery system comprises a plurality of washing flow paths extending from, for example, two supply electrovalves 6, 7, through corresponding compartments 8, 9, 10 of a detergent tray 12, to the washing tank 3.
On the bottom 13 of the washing tank 3, there is provided a drain duct 14 with a discharge pump 15 being associated thereto, which provides for the removal of the washing liquid from the tank 3 and controls, together with the supply electrovalves 6, 7 the level of liquid within the tank 3.
To heat the washing liquid contained within the tank 3, a coiled electric resistance 11 is provided, which is arranged within the tank 3, particularly on the bottom 13 of the latter, in the gap between the tank wall 3 and the laundry basket 5.
The washer-drier machine 1 further comprises a closed-loop drying circuit with a suction unit, for example an fan impeller 17 driven by an electric motor 18, a heat exchanger as well as a heating unit with electric resistance 21, which communicate with each other by means of a drying circuit 16.
In such a closed-loop circuit, the air flow 22 generated by the suction unit 17, 18 is heated by the electric resistance 21 and sent to the basket 5, where it flows through the wet laundry thereby causing the water contained in the fabric to evaporate. The heat exchanger is arranged downstream of the laundry basket 5 (with reference to the direction of the drying air flow 22) and cools the wet air flowing from the basket 5.
Due to this cooling, the vapour condensates and is collected and discharged, for example together with a cooling water volume. The de-humidified air is then sucked again by the suction unit 17, 18 and ricirculated.
According to an aspect of the invention, the washing tank 3 defines therein a condensation space 19 suitable to contain a cooling water volume 20 that forms a free water surface spaced away from the basket 5 such as to be capable of cooling the drying air flow 22 downstream of the basket 5 within the washing tank 3.
According to a preferred embodiment, this condensation space 19 is formed at the tank bottom 13, approximatively below the basket 5.
Thereby, the whole supply circuit of the condenser can be eliminated, as the latter can be easily supplied with mains water loaded by the washing water loading circuit, since it consists of a free surface of a water volume 20 (condensation surface) within the washing tank 3.
Furthermore, as the cooling water volume 20 on the washing tank 3 is maintained, a continuous use of a same water volume is allowed until the latter is heated past a threshold temperature allowed for condensation purposes. This results in a considerable saving of cooling water during the drying step.
The washer-drier machine 1 comprises a control unit (not shown in the drawings) which allows setting a drying program that carries out the following steps:
The step of controlling the level of cooling water 20 may comprise the step of detecting a value indicative of the level of cooling water 20 and at least partially draining the cooling water 20 through the drain duct 14, when the level of cooling water 20 exceeds said upper level.
The operation of detecting a value indicative of the level of cooling water 20 may be carried out by means of a pressure sensor 24 that is arranged at the tank bottom 13. This pressure sensor 24 (e.g., a so-called pressure switch) generates a pressure signal and sends it to the control unit that, in turn, controls the discharge pump 15 and causes the latter to at least partially drain the cooling water 20 and condensate from the washing tank 3. Alternatively, the pressure sensor 24 directly interacts with the power supply of the discharge pump 15 and causes the partial or total drainage of the tank 3 in response to the attainment of a determined water level, for example the above-cited upper level.
In accordance with a further embodiment, the control of the cooling water level 20 can be carried out with one or more level sensors (such as a sensor using the electrical conductivity of the cooling water 20) that are connected to the control unit and/or directly to the discharge pump 15.
The washer-drier machine and the washing and drying programs thereof may be configured such that the control of the level of cooling water 20 during the drying step and the control of the washing liquid level during the washing and rinse step are carried out by means of a same pressure sensor 24 or group of level sensors.
According to the invention, the control of the level of cooling water 20 is carried out by at least partially draining this water, at preset time intervals, wherein the duration of these intervals is determined, for example, on the basis of a series of tests or numerical simulations and takes into account the condensate accumulation on the tank bottom.
According to an embodiment, the process step of controlling the temperature of cooling water 20 comprises the step of detecting the temperature or a magnitude indicative of the temperature of the cooling water 20 and at least partially discharging the cooling water 20 through the drain duct 14 and feeding a corresponding amount of fresh mains water in the washing tank 3, when the temperature detected exceeds said upper value.
Advantageously, the operation of detecting the temperature of the cooling water 20 is carried out by means of a temperature sensor 25 arranged in the vicinity of the tank bottom 13. This temperature sensor 25 generates a temperature signal and sends it to the control unit, which, in turn controls the drain pump 15 and the supply electrovalves 6, 7.
When the upper temperature is reached or exceeded, the control unit causes the drain pump 15 to at least partially remove the cooling water 20 and condensate from the washing tank 3 and, subsequently, it opens the supply electrovalve 6 and/or 7 to feed a corresponding amount of cold mains water, preferably through the same water supply duct used during the washing step. Alternatively, the temperature sensor 25 directly interacts with the power supply of the discharge pump 15 and supply electrovalves 6, 7 and causes the partial or total replacement of the cooling water 3 in response to the fact that the upper temperature has been attained or exceeded.
Advantageously, the washer-drier machine and the washing and drying programs are configured such that the control of the temperature of the cooling water 20 during the drying step and the control of the temperature of the washing liquid during the washing and rinse steps are carried out by means of a same temperature sensor 25 or groups of temperature sensors.
Alternatively to what has been described above, the control of the temperature of the cooling water 20 can be carried out by at least partially draining this water, at preset time intervals, wherein the duration of these intervals is determined, for example, on the basis of a series of tests or numerical simulations and takes into account the temperature increase in the mixture of cooling water and condensate on the tank bottom 13.
According to an embodiment, the control unit is configured such as to allow selecting a drying program in which during the last drying step, also known as the cool-down step, the condensation space 19 results to be completely without cooling water 20, which has been previously drained and not replaced with fresh mains water. In fact, experimental tests have proved that, during the cool-down step, the residual humidity can be extracted from the laundry without an active cooling by the drying air flow 22.
In accordance with a further embodiment, the control unit is configured such as to allow selecting a drying program in which only or also during the early drying step, the condensation space 19 results to be completely without cooling water 20, which will be loaded only about 20 min - 40 min, preferably 30 min after the beginning of the drying step. In fact, experimental tests have proved that a part of the humidity can be also extracted from the laundry during the early drying step without an active cooling by the cooling air flow 22.
According to an embodiment, the washing tank 3 which is preferably moulded from plastics, defines therein a suction portion 26 of the drying duct 16, i.e. the duct portion arranged downstream of the heat exchanger (consisting of the free surface 23 of the cooling water 20 on the tank bottom 13) and upstream of the suction unit 17, 18.
In accordance with an embodiment, this suction duct 26 extends within the washing tank 3 from a lower area thereof to an opening 27 in the upper area thereof and is defined by a portion of the inner surface of the tank 3 and by a lid 28 that is separately manufactured and subsequently connected to the inner surface of the washing tank 3.
Thereby, the same washing tank 3 can be advantageously used both with washing machines without drying function (without the inner lid 28), and with drier-washer machines (with the inner lid 28).
In accordance with a further embodiment, (
In accordance with an embodiment, the additional heat exchanger 29 comprises a cooling coil 30 that can be supplied with mains water and is arranged in the supply path of the washing water, preferably between the supply electrovalve 6, 7 and the detergent tray 12.
Thereby, the additional heat exchanger 29 is also supplied by means of the same washing water supply circuit.
According to an embodiment, the cooling coil 30 of the additional heat exchanger 29 is formed, for example by means of blow moulding, at or in the lid 28 of the suction portion 26 of the drying duct 16.
Thereby, two further condensation surfaces are obtained, i.e. the inner surface 31 and the outer surface 32 of the lid 28, both arranged within the washing tank 3 and blown by the drying air 22.
Due to the direct hydraulic connection to one of the supply valves 6, 7, the cooling coil 30 cannot be emptied. By opening the supply valve 6, 7, the water contained within the cooling coil 30 can be only replaced with fresh mains water.
This allows, during the step of controlling the level of the condensation free surface 23, discharging part of the cooling water volume 20 and condensate accumulated on the tank bottom 3 independently of the additional heat exchanger 29 as well as simultaneously carrying out the replacement of the cooling water in both heat exchangers.
With reference to the embodiments providing also said further heat exchanger 30, in addition to the first heat exchanger consisting of the cooling water volume 20 on the bottom of the washing tank 3, the control unit is preferably configured such as to allow selecting a drying program, in which, during an early drying step, only the additional heat exchanger will be operated, whereas the condensation space 19 on the tank bottom 13 is not provided with cooling water 20.
Thereby, during the early drying step, a drier environment is obtained within the tank, which is thus even more favourable to the extraction and condensation of the initial high amount of humidity contained in the laundry.
The washer-drier machine according to the invention has a number of advantages.
Due to the free cooling water surface on the tank bottom and due to the fact that a major part of the drying circuit runs within the washing tank 3, a considerable space saving is obtained at the same laundry load relative to the traditional washer-drier machines.
In view of the particular conformation of the suction portion 26 of the drying circuit allows using the same tank structure both in washing machines and in the present washer-drier machine.
The supply of the cooling water 20 on the washing tank bottom 3 being carried out through the same ducts that are provided for carrying the washing water and detergent during the washing and rinse steps, a dedicated duct for supplying the heat exchanger is eliminated. This results in the elimination of at least one dedicated electrovalve for the heat exchanger and the spray nozzles and cooling ducts thereof.
In conclusion, the washer-drier machine according to the invention is a considerable simplification and unification, both in terms of structure and washing and drying programs.
Obviously, to the washer-drier machine according to the present invention, those skilled in the art, aiming at meeting contingent and specific requirements, may carry out further modifications and variations, all being however contemplated within the scope of protection of the invention, such as defined in the annexed claims.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.