EP2752519B1

EP2752519B1 - Washing machine with self-cleaning drying circuit and relevant operating cycle

Info

Publication number: EP2752519B1
Application number: EP13425003.4A
Authority: EP
Inventors: Luca Bicego; Lucio Gastaldelli; Mauro Tosi
Original assignee: Bonferraro SpA
Current assignee: Bonferraro SpA
Priority date: 2013-01-08
Filing date: 2013-01-08
Publication date: 2015-10-07
Anticipated expiration: 2033-01-08
Also published as: EP2752519A1; PL2752519T3

Description

The present invention relates to washing machines provided with a drying circuit, and in particular to a machine provided with an automatic device for cleaning said circuit and to a relevant operating cycle.
It is known that in washing machines which also carry out the drying function there is provided a drying circuit in which, at the end of the wash cycle, the air coming from the drum is passed. This circuit includes a substantially vertical condensation channel where water is fed which is kept in suspension by the suction generated by a drying fan, such that the water vapour contained in the air drawn in from the drum encounters the suspended water and condensates towards the drain pump. The thus dehumidified air is then heated and returned to the drum repeating this path for a preset time or until detection of the drying of the laundry.
A typical drawback of these combined washing-drying machines is that due to accessibility problems they are not provided with filters in the drying circuit, whereas these are provided in drying machines. Said filters are required to stop the cloth fibers and the detergent particles which enter the circuit together with the air during the drying step. In fact it is well known that a worn item releases fibers during the wash and these become lighter due to the drying and they may follow the air flow in the drying circuit. These fibers, together with the detergent particles, tend to deposit in the condensation channel and on the impeller of the fan which generates the air flow in the circuit.
The continuous accumulation of these residues causes over time a progressive decrease in the performance of the drying system due to the reduction of the air flow rate delivered by the fan. The problem may increase until it reaches a clogging of the circuit with consequent blocking of the drying system upon intervention of the safety devices which prevent overheating (e.g. thermostat). Obviously at this moment a maintenance intervention is required to restore the drying function of the machine.
In order to prevent these problems it is already known to provide the washing-drying machine with nozzles for cleaning the condensation channel and/or the fan impeller, as described for example in EP 1353004 in the name of the same applicant. These nozzles are fed through an electrovalve that is activated at the beginning or at the end of the drying cycle whereby the dispensed water, together with the removed residues, is then drained by the drain pump and the system is ready for the following drying cycle in a perfectly clean state. This cleaning step will in general be carried out in an automatic way at every drying cycle, but it is possible to provide so that it is carried out every given number of cycles or only upon specific command by the user.
In this way the drying performance of the machine remains constant over time, the maintenance interventions are reduced and there is no alteration of the laundry smell. However, this cleaning step implies also a consumption of water to wash the circuit and of power to activate the drain pump, in addition to a greater length of the operating cycle of the machine.
FR 2711153 proposes a machine and an operating cycle aimed at decreasing the water consumption by providing to use for the cleaning step a portion of the wash or rinse water that is recycled by diverting it from the drain duct through a branch duct connected to the condensation channel and the fan. Such an arrangement, however, still has various drawbacks in that it makes the machine structure more complicated and therefore expensive, it does not avoid the power consumption caused by the extended operation of the drain pump which must drain the recycled water and always implies a distinct cleaning step which extends the duration of the operating cycle of the machine.
Moreover, the use of recycled water does not allow for an optimal cleaning since the drying circuit is washed with water containing dirt and/or detergent particles or even containing the same fibers coming from the laundry which on the contrary should be removed in such a cleaning step.
Therefore the object of the present invention is to provide a washing-drying machine which is free from said drawbacks. This object is achieved by means of a machine provided with a device for cleaning the drying circuit which is sized to operate also as a device for loading the wash or rinse water, whereby the cleaning step can be carried out in parallel to the water loading for one of said steps. Other advantageous features of the present device are disclosed in the subsequent claims.
The main advantage of the present machine resides in the fact that the water used for the cleaning step is then used also for the wash or rinse, whereby there is no increase in water consumption nor in the operating time of the drain pump. This recycled water is suitable for wash or rinse in that the cleaning of the drying circuit is preferably carried out at every operating cycle such that there is no accumulation of dirt in the circuit.
Also, as a consequence, the cleaning step does not extend the duration of the operating cycle of the machine but rather shortens the duration since it is carried out in parallel with a water loading step to which it contributes with its flow rate. Furthermore, said cleaning is fully effective too because it is carried out with a high flow rate of clean water coming directly from the water network.
Another advantage of this type of machine is that it is made with a very simple structure, which therefore results cheap to manufacture and reliable in use.
Further advantages and characteristics of the machine according to the present invention will be clear to those skilled in the art from the following detailed description of an embodiment thereof, with reference to the annexed drawings wherein:

Fig.1 is a perspective front view of the drying circuit of a machine according to the invention;
Fig.2 is a perspective partial rear view of said drying circuit in which the cleaning device is arranged;
Fig.3 is a perspective partial side view similar to Fig.2;
Fig.4 is a top plan view schematically illustrating the arrangement and orientation of the impeller cleaning nozzle; and
Figs.5 and 6 are views of the condensation channel respectively in a longitudinal and transverse cross-section schematically illustrating the arrangement and orientation of the condensation channel cleaning nozzle.

With reference to said figures there is seen that the drying system of the present machine conventionally includes a fan made up of an impeller 1 enclosed by a case 2 and driven by a motor 3 to generate an air flow through the drum (not illustrated) and the circuit. More specifically, the air coming from the drum enters the circuit through inlet 4, flows up along the condensation channel 5 up to case 2, then passes through the heating chamber 6 where it is heated by resistor 7, and is finally returned to the drum through joint 8.
The operation of the drying system is based on the condensation of the vapour coming from the drum by means of the water fed through a pipe 9 and kept suspended in the substantially vertical channel 5 due to the suction effect generated by the fan. Once it has been condensed, the vapour is conveyed to the drain pump through an outlet (not shown), so that the fan receives cool and dry air which is heated in chamber 6. Here resistor 7 is monitored by a safety thermostat 10 and in the last minutes of the drying cycle it is turned off while the fan continues to operate to cool down the laundry which otherwise would be too hot to allow the user to extract it from the drum.
To achieve the cleaning of impeller 1 and of channel 5 a specific electrovalve 11 feeds through a pipe 12 a first nozzle 13, which emits a measured water jet towards impeller 1, and a second nozzle 14 which emits a measured water jet at the top of channel 5. In particular, the jet emitted by the first nozzle 13 is preferably oriented in the direction opposite with respect to the direction of rotation of impeller 1 and is emitted for some seconds so as to achieve the cleaning of all blades of impeller 1 that is mounted idle on motor 3. In this way it is the jet itself which causes the counter-rotation of the impeller during the cleaning step, but a short activation of motor 3 could be provided as well.
A first novel aspect of the present invention resides in the choice of using an electrovalve 11 of the cleaning device having a flow rate of at least 6 l/min, preferably 7 l/min, which is thus sized in order to be able to guarantee a proper simultaneous washing of impeller 1 and of the condensation channel 5.
A second novel aspect of this machine stems from the fact that the cleaning step is carried out in parallel with the wash cycle whereby electrovalve 11 in the meantime contributes to the water loading in a loading step of the operating cycle, preferably at the first rinse that is carried out immediately after the wash.
Furthermore, as previously mentioned, the choice of washing the drying circuit with water coming directly from the water network allows to achieve a higher washing effectiveness without circulating additional elements, such as fibers and detergent particles, which might cause cloggings. All of this is achieved, with respect to the prior art, without increasing the use of the drain pump and thus decreasing the operating time and the power consumption.
Finally, the inclination angles of the wash nozzles 13, 14 with respect to the axes of impeller 1 and channel 5 are important. More specifically, nozzle 13 emits a water jet that is inclined in the horizontal plane (see Fig.4) at an angle between 30° and 35°, preferably 33°, with respect to the rotation axis of impeller 1, while nozzle 14 is oriented downwards in the vertical plane (see Fig.5) at an angle between 16° and 20°, preferably 18°, and in the horizontal plane (see Fig.6) it forms an angle between 0° and 4°, preferably 2°, with respect to the midplane of channel 5.
It is clear that the above-described and illustrated embodiment of the machine according to the invention is just an example susceptible of various modifications. In particular, the shape and arrangement of the elements making up the drying circuit may be somewhat changed, same as the type of impeller 1 and/or the position of the wash nozzles 13, 14 as long as electrovalve 11 is activated at the proper time and suitably sized.

Claims

Washing machine provided with a drying circuit including a substantially vertical condensation channel (5) connected at the top to a fan made up of an impeller (1) enclosed by a case (2) and driven by a motor (3) to generate an air flow through the machine drum and said condensation channel (5), as well as a cleaning device for said drying circuit including an electrovalve (11) that feeds through a pipe (12) both a first nozzle (13), arranged in said case (2) to emit a water jet suitable to clean said impeller (1), and a second nozzle (14) arranged at the top of the condensation channel (5) to emit a water jet suitable to clean the latter, characterized in that said electrovalve (11) has a flow rate of at least 6 l/min, preferably 7 l/min, and is operatively connected to a control unit of the washing machine so as to be activated during the wash cycle at a water loading step.
Washing machine according to claim 1, characterized in that the first nozzle (13) is arranged so as to emit a water jet oriented in the direction opposite with respect to the direction of rotation of the impeller (1), which is preferably mounted idle on the motor (3).
Washing machine according to claim 2, characterized in that the nozzle (13) emits a water jet that is inclined in the horizontal plane at an angle between 30° and 35°, preferably 33°, with respect to the rotation axis of the impeller (1).
Washing machine according to any of claims 1 to 3, characterized in that the second nozzle (14) is oriented downwards in the vertical plane at an angle between 16° and 20°, preferably 18°, and in the horizontal plane it forms an angle between 0° and 4°, preferably 2°, with respect to the midplane of the condensation channel (5).
Operating cycle for a washing machine according to one or more of the preceding claims, characterized in that a cleaning step of the drying circuit including the activation of the electrovalve (11) for at least some seconds is carried out simultaneously with a water loading step during the wash cycle.
Operating cycle for a washing machine according to claim 5, characterized in that the cleaning step is carried out at the first rinse.
Operating cycle for a washing machine according to claim 5 or 6, characterized in that the cleaning step is carried out at every operating cycle which includes the drying step.