CONTROLLING DEVICE FOR CLOTHES WASHING MACHINE

Abstract: A controlling device for a clothes washing machine comprising a washing liquor collector (13), wherein a heating element (15) and two thermostats (16, 17) calibrated at fixed temperatures are housed, and also comprising an electric pump (19), for circulating washing liquor from the collector (13) to the tub (4), and three pressostats (22, 23, 26), for allowing washing liquid to be filled at two different levels in the machine and for controlling the working condition of the filtering element (14). The controlling device allows both "intensive" washing programmes with only a low level of liquor in the collector (13), and "delicate" washing programmes with normal levels of liquor in the tub (4) to be set and carried out. Therefore, each kind of clothes can be washed under the best conditions with low consumption of water, detergents and electric power.

Description: The present invention relates to a controlling device for a clothes washing machine of a type in which clothes are washed through the wash liquor being sprayed on the same clothes. In the Italian patent application No. 45734 A/83, filed in the name of Industrie Zanussi SpA on December 6, 1983, a clothes washing machine of the above cited type is described, which essentially includes a washing tub, a clothes containing drum, as well as a collector for the wash liquor placed underneath and suitably connected with said tub, the collector being so shaped as to contain at least a filtering element, an electrical heating element and a thermostatic sensor for filtering, heating and sensing the temperature of the wash liquor, respectively. Said wash liquor collector is connected both with the outlet piping of the washing machine through a usual drain pump, and with the wash tub through a further piping system and an electric circulating pump, which can be either separate or on the same axis with the drain pump, said electric circulating pump being provided with a suction opening connected with said wash liquor collector as well as a delivery opening connected with said further piping system. Such a machine allows therefore for performing both "intensive" and "delicate" washing programmes of a traditional type for washing heavily soiled clothes at normal levels of the wash liquor in the tub, while keeping the circulating pump switched off for the whole duration of the same washing programmes, as well as "intensive" washing programmes for laundering not so heavily soiled clothes at lower levels of the wash liquor in the tub and switching on said circulating pump on certain periods during the same washing programmes in such a way that the wash liquor is repeatedly circulated from the collector into the tub through said piping system and directly sprayed onto the clothes. In particular, these special "intensive" washing programmes are used to wash not so heavily soiled cottons and/or heat-resistant synthetics by filling the wash liquor into said collector at different reduced levels according to the actual wash load in the drum. Such special programmes do not include pre-soak or pre-wash cycles of the type usually available in traditional "intensive" or "delicate" washing programmes, but only a suitable sequence of washing steps in which said circulating pump is constantly kept under switched-on condition and the wash liquor is heated up to maximum temperatures of approximately 90°C, while the drum is rotated both at wash speed with a reversing action, and at spin-extraction speed for shorter time spans than the ones at regular wash speed. At the end of the actual washing process, the wash liquor is discharged under switched-off condition of the recirculating pump. Thereafter, a sequence of regular rinse cycles is performed in a traditional way. As a result, these "intensive" washing programmes, owing to the reduced levels of wash liquor used in the tub, can be performed under substantial savings of water, detergents and energy as compared with traditional programmes. However, while operating satisfactorily and reliably, such a washing machine has some drawbacks. A first drawback is represented by limitations in the applicability of washing programmes involving reduced levels of the wash liquor in the tub. In particular, such programmes are not applicable to the washing of clothes with special kinds of soils, such as some proteinic or organic soils (blood, cocoa, milk, etc.), mud and similar soils, which require that the wash liquor be heated up to low temperatures (approximately 40°C) and duly kept to such temperature values for fixed periods of time in order to prevent soil from fixing onto the clothes. As a matter of fact, in such a case - owing to the reduced amount of water that is being filled into the tub - the wash liquor would be heated up very quickly, thus preventing said lower temperature values from being reached and kept for a suitable period of time as required for best washing results. In other words, clothes with such particular soils would be washed at higher temperatures than the suitable ones and this would inevitably lead to unsatisfactory washing results. Furthermore, the above mentioned washing programmes would only give satisfactory washing results when laundering cottons and/or it-resistant synthetics which are not so heavily soiled and do not, therefore, require a pre-soak or pre-wash cycle in order to completely remove soil. On the contrary, said washing programmes would not lead to satisfactory results even when laundering clothes of the same kind mentioned above if they are heavily soiled and therefore require a preliminary soak or pre-wash cycle for adequate soil removal, since said programmes are not designed to include such a pre-soak or pre-wash cycle. Further drawbacks in the use of this washing machine derive from the absence of suitable safety devices to check both the filtering element for efficiency and the heating element for safe operation, i.e. to make sure that the latter only operates when actually flooded with wash liquor. As a matter of fact, in the first case, since said filtering element is designed to retain soil particles from the wash liquor being circulated from the appropriate collector to the machines tub through the proper recirculation pipe, there is the actual need of constantly having said element checked in order to immediately sense an irregular condition, e.g. clogging, and let the user clean or possibly replace the filtering element for ensuring a constantly effective circulation of the wash liquor. In the second case, the heating element shall always be flooded, i.e. submerged in the wash liquor, for its correct and safe operation, or else it will over heat to excessive temperature values, thereby reating the risk of damages to the element itself and the washing machine. This invention, therefore, pursues the aim of overcoming all the above mentioned drawbacks and limitations in a washing machine of the type described above, but provided with a special controlling device designed to allow programmes at low levels of wash liquor in the tub to be performed for washing any kind of more or less soiled clothes, except for particularly delicate fabrics and knitware (woollens, silkens, acrylics) requiring washing at regular levels of the wash liquor in the tub in all cases. This controlling device is further provided with safety devices for checking the efficiency and the operating conditions of both the filtering element and the heating element of the washing machine, in order to prevent disturbances of the afore mentioned kind from occurring. These and other aims are reached, according to the present invention, in a controlling device for a clothes washing machine including a tub, a rotatable drum within said tub and a wash liquor collector communicating with the lower side of the tub through a flexible conduit and with the lower side of the tub through a pipe and a circulating pump, said collector housing at least a filtering element, an electric heating element and thermostatic control means, the washing machine further including an inlet solenoid valve and level control means for the wash liquor. Said thermostatic control means comprise at least a first and a second thermostat, or the like, which are calibrated at a fixed tripping temperature and at adjustable tripping temperatures, respectively. Furthermore, said level control means comprise a first and a second pressure switch, or the like, which are selectively connectable with said solenoid valve and so calibrated as to determine that the wash liquor is fed up to a predetermined level in said tub and to a lower level in said collector, said level control means further including a third pressure switch, or the like, which is connectable with both said first and second pressure switches and calibrated so as to detect the pressure of the wash liquor circulating upstream of said filtering element, said first and second pressure switches being also selectively connectable to said heating element, in parallel with said circulating pump, through said first and second thermostats and at least a control relay the energization or de-energization of which causes the cams associated with the various electrical contacts of the controlling device to stop or to progress, respectively. The features and the advantages of this invention will more clearly emerge from following description, serving merely as a non-limiting example with reference to the enclosed drawings, where: - Fig. 1 schematically shows a side view of the cross-section of a clothes washing machine provided with a controlling device according to the invention; - Fig. 2 shows the electrical schematics relating to the controlling device according to the invention. With reference to Fig. 1, the clothes washing machine provided with a controlling device according to the invention is shown, which machine essentially includes a cabinet 3, a wash tub 4 supported inside said cabinet in a per se know way, as well as a drum 5 designed to contain the washload and rotated by an electric driving motor 6 of a traditional type, which is attached to the lower part of the tub 4. Furthermore, on the upper part of the machine there is a detergent dispenser 7 for washing and rinsing agents, which is connected to the water supply through a suitable pipe 8 and a solenoid valve 9 and is provided with a hose 10 connecting it with the tub 4, through which water and detergents flow into said tub. The lower part of the tub 4 is provided with a drain opening 11, which is connected through a hose 12 with a collector 13 designed to collect the wash liquor from said tub, said collector being so shaped as to contain a fine-mesh filtering element 14 of a traditional type, which is placed in a removable way inside said collector so as to be in the stream of the wash liquor flowing off the tub 4 and retain all soil particles from the same liquor during pre-wash and main wash, as described in the following. Furthermore, at least an electric heating element 15 and two thermostats 16 and 17, or similar temperature sensors, of a traditional type are located inside said collector 13, which are designed to heat up and control the temperature of the in-flowing wash liquor, respectively. In particular, the heating element 15 is sized so as to ensure an adequate power output for a rather rapid heating up of the wash liquor; it can further be energized for different lenghts of time - as described in the following - through proper control by the thermostat 16 or the thermostat 17. The thermostat 16 itself is of a fixed-adjustment type and is set to a relatively low tripping temperature, i.e. preferably approximately 40°C, in order to allow the wash liquor to be heated up to this temperature value during pre-wash and main wash cycles at low temperature. The thermostat 17 is on the contrary of an adjustable type, and is calibrated for a variable temperature range, i.e. preferably from approximately 30°C and 90°C, in order to allow the wash liquor to be heated up to different temperature values - according to the type or requirements of the washload - during the wash cycle. Furthermore, the wash liquor collector 13 is connected with the upper part of the tub 4 through a pipe 18, which is attached to the upper part of the collector itself, and an electric circulating pump 19, so as to bring about a continuous circulation of the wash liquor from the collector 13 to the tub 4 during the different washing programmes performed by the clothes washing machine considered. Finally, said wash liquor collector is also connected - through the drain pump 20 - with the drain hose 21 to discharge the wash liquor from the collector into the drain at the end of a washing programme. The washing machine designed in this way is substantially similar to the one described in the patent application no. 45734 A/83, filed by the same Applicant on December 6, 1983, where the operation features and the further possible embodiments of the machine itself are also described. In order to achieve a suitable control of the level of the liquor flowing into the washing machine, the latter is provided with two pressure switches 22 and 23, or similar level control devices, which are connected to the air traps 24 and 25 respectively, as provided for in the hose 12 and in the upper part of the collector 13. In particular, the pressure switch 22 is set to bring about a fixed, normal level of the wash liquor filled into the tub 4 for carrying out "delicate" laundering programmes to wash woollens, silkens or delicate, synthetics, or even single soak or pre-wash cycles associated with "intensive" laundering programmes for washing more or less heavily soiled cottons, linens and/or heat-resistant synthetics, in the way described later on. The pressure switch 23 is in its turn set to bring about a minimum level of the wash liquor flowing into the collector 13, which minimum level is lower than the one brought about by the afore mentioned pressure switch 22, remains unaltered for any quantity and type of clothes loaded in the drum 5, and is also high enough to ensure complete submersion of the heating element 15 in the wash liquor. Purpose of said pressure switch 23 is to allow "intensive" laundering programmes to be performed for washing more or less heavily soiled cottons, linens and/or heat-resistant synthetics in the way described later on. Furthermore, the clothes washing machine herein considered is provided with another pressure switch or similar level control device 26, which is also connected to the air trap 24 and set so as to sensitively react to pressure variations occurring in the hose 12 when the wash liquor is being circulated through the conduits 12 and 18 and the filtering element 14 by the action of the proper recirculation pump 19. Purpose of said pressure switch 26 is to constantly sense the pressure of the wash liquor flowing through the flexible conduit 12 - before the filtering element 14 according to the flow direction of the wash liquor itself - so as to indirectly check the efficiency conditions of said filtering element, in that it will sense - and immediately indicate - any irregular condition resulting from the filtering element becoming clogged with dirt or soil particles retained from the wash liquor. In this way, the pressure switch 26 changes between two operating settings, according to the efficiency condition of the filtering element. In particular, said pressure switch will stay in its first operating setting as long as it senses a certain flow pressure in the flexible conduit 12 corresponding to a condition in which said filtering element is completely free or is clogged to such a minimum extent that an efficient circulation of the wash liquor is not being impaired. The pressure switch 26 will then change over to its second operating setting as soon as it senses a different pressure in the same flexible conduit 12 - higher than the previous one - owing to the filtering element 14 becoming clogged to such an extent as to preclude any further efficient circulation of the wash liquor. This second operating setting of the pressure switch 26 is indicated by an optical display or an acoustic signal - as it will be described later on - to alert the user that the filtering element 14 needs cleaning or possibly replacing. This invention also considers the possibility of combining the afore mentioned pressure switches, so as to obtain - for example - a single level control unit comprising a combination of the three pressure switches 22, 23 and 26, or even a level control pair comprising a combination of the two pressure switches 22 and 26 and a separate assembly of the remaining pressure switch 23. With reference to Figure 2, the electrical schematics of the main controlling device for the washing machine according to the invention is shown, where it can be seen that said device is connected to the power supply source through a main on/off-switch 27 and essentially comprises - in addition to the pressure switches 22, 23 and 26 and all other components mentioned above - also the electrical windings 28 e 29 of the motor 6, which are designed to bring about the low wash speed and the high spin speed of the motor itself, respectively, said windings being connected with the corresponding start capacitors 30 and 31. This controlling device for the washing machine also comprises an indicator light 32 designed to alert the user of a possible clogged condition of the filtering element 14, a motor 33 intended for rotating the cam cylinder, said cams being associated with a set of electrical contacts 34 - 46 which are provided for selectively switching on and off the various electrical components of the washing machine, and it comprises a control relay 47 or similar device as well, which is designed to cause said cams to stop or to further rotate according to the relay itself being energized or de-energized. The pressure switch 22 is also provided with a moving electrical contact 48 which can switch over to two different operating settings, i.e. to either of the two fixed contacts 49 or 50, as a function of the level of the wash liquor filled into the tub 4. In particular, said moving contact switches over to the fixed contact 49 ("empty" tub) whenever the tub 4 is empty or filled with wash liquor to a level which is lower than the regular one. On the contrary, said moving contact switches over to the fixed contact 50 ("full" tub) whenever the regular level of the wash liquor is reached in the tub 4. Similarly, also the pressure switch 23 is provided with an electrical moving contact 51 which can switch over to two different control settings, i.e. to either of the two fixed contact 52 or 53, as a function of the level reached by the wash liquor filled into the collector 13. In particular, said moving contact switches over to the fixed contact 52 ("empty" collector) when the collector 13 is empty or filled with wash liquor to a level which is lower than the minimum regular one. On the contrary, said moving contact switches over to the fixed contact 53 ("full" collector) when the collector 13 is filled with wash liquor to the minimum regular level. Finally, also the remaining pressure switch 26 is provided with a moving electrical contact 54, which can be connected to the power supply through a main conductor 55 and the on/off switch 27, said moving contact switching over to either of two fixed contacts 56 or 57 according to the pressure switch 26 being on its first or second operating setting, respectively, as described above. In the first case, said moving contact 54 causes the energization of a common conductor 58, which is connected with both the corresponding moving contacts 48 and 51 of the pressure switches 22 and 23 and the electrical contact 38 of the considered controlling device, said electrical contact being also capable of switching over to a further fixed contact 59 connected with a further common conductor 60. In the second case, said moving contact 54 causes the energization of the indicator light 32, which is connected with the fixed contact 57 of the pressure switch 26 and the other main conductor 61 of the considered controlling device. In their turn, the fixed contacts 49 and 50 of the pressure switch 22 can be connected - through the making of a corresponding electrical contact 34 and 39 of the controlling device - both with the solenoid valve 9 and the above mentioned main conductor 61, and the common conductor 60. Similarly, the fixed contacts 52 and 53 of the pressure switch 23 can be connected - through the making of a corresponding electrical contact 35 and 37 of the controlling device - both with the solenoid valve 9 and the main conductor 61, and with the common conductor 60. Functional connections that can be brought about with the remaining contacts of the considered controlling device will be described hereinafter. In particular, the contact 40 can close to make a circuit comprising an inverter switch 62, which is actuated by the continuous rotation of the cams of the controlling device and which can be connected in series with the electrical windings 29 for the high spin speed of the motor 6, said windings being connected with the main conductor 61. As an alternative, said electrical windings 29 can also be energized through the contact 36, which is directly connected with the fixed contact 52 of the pressure switch 23, rather than through the above mentioned inverter switch 62. In their turn, the contacts 41 and 42 can close on the drain pump 20 and the circulation pump 19, respectively, both said pumps being connected with the main conductor 61. Similarly, the contact 43 can close on a circuit comprising the adjustable thermostat 17, which can be connected - in series with the heating element 15 - to the main conductor 61. In its turn, said heating element can be parallel-connected with a further circuit comprising the fixed thermostat 16 in series with the control relay 47, said fixed thermostat further being short-circuitable through the closure of the contact 44, which is parallel-connected with the same thermostat. In the considered case, the above cited thermostats 16 and 17 are provided with corresponding contacts 63 and 64 of the normally closed type, which therefore open when the rated tripping temperature for the corresponding thermostat is reached. Of course, according to the invention it is also possible to use thermostats having contacts of the normally open type, by connecting them in a different way with the heating element 15 and the relay 47, provided that the heating up of the wash liquor can in both cases be controlled according to the form and procedure described hereinafter. Finally, the remaining electrical contacts 45 and 46 of the considered controlling device can energize both electrical windings 28 for the low wash speed of the motor 6, said windings being connected with the main conductor 61. In particular, the contact 45 can be connected with said electrical windings through two further inverter switches 65 and 66, both associated with a corresponding cam of the controlling device, of which the inverter switch 66 can be switched over to close on either of the fixed contacts 67 and 68 connected with the above cited electrical windings 28, in order to cause the driving motor 6 to rotate according to a reversing motion sequence. The contact 46, on the other hand, can be only connected with said electrical windings through the inverter switch 66. Purpose of said contacts 45 and 46 is to enable the drum 5 to be driven and to rotate according to a reversing sequence and two different rhythms of said reversing motion, i.e. a "delicate" alternating rotation (i.e. with short motions) through the closure of the contact 45 and the energization of the inverter switches 65 and 66, and an "intensive" alternating rotation (i.e. with long motions) through the closure of the contact 46 and the energization of the inverter switch 66, in order to carry out the various washing programmes as described hereinafter. Finally, the drive motor 33 of the considered controlling device is directly connected with the common conductor 60 and the main conductor 61. The various washing programmes that the controlling device according to this invention is able to control will now be described in detail. In particular, a pre-soak or pre-wash cycle before the main wash can be added or not to the programme in the case of heavily soiled clothes. If a pre-wash is to be added, the thermostat 17 shall be set by hand to an appropriate control setting according to the nature or type of soil to be removed, at which setting the wash liquor is heated to a higher temperature than 40°C. Furthermore, also the considered controlling device is in this case set by hand to an initial setting in which the moving contact 54 of the pressure switch 26 closes on the fixed contact 56, while the moving contact 48 of the pressure switch 22 closes on the fixed contact 49. In their turn, the contacts 34 and 39 are connected with the solenoid valve 9 and the fixed contact 50 of the pressure switch 22, respectively, while the contact 43 closes on the circuit comprising the heating element 15, both thermostats 16 and 17, as well as the relay 47, and - finally - the contact 46 is connected with the inverter switch 66. In this way, the wash liquor is filled into the tub 4 to a normal level as fixed by the pressure switch 22, and said liquor is then gradually heated up while the rotating drum of the washing machine is driven at low wash speed according to an "intensive" reversing sequence. Subsequently, the contact 42 is closed on the circulation pump 19 for the whole duration of the period in which the wash liquor is heated up. As a result, such a wash liquor is being circulated through the recirculation conduit 18, thereby ensuring its uniform heating up inside the machine. In this way, since the heating is done in the presence of a considerable quantity of wash liquor in the tub 4, the temperature of the same liquor can only rise slowly. Furthermore, during such heating of the wash liquor the thermostat 16 is connected in series with the control relay 47, the resulting energization of which causes the cams of the controlling device to stop. In this way, an extended soak cycle at low temperatures is obtained for the clothes, which allows part of the soil to be removed from the clothes. It also prevents this soil from re-depositing onto the same clothes as it is subsequently discharged with the wash liquor. As soon as a temperature of 40°C of the wash liquor is reached, which is the value at which the thermostat 16 is rated to trip, the contact 64 of said thermostat then opens causing the de-energization of the relay 47. As a result, the cams of the controlling device start again to rotate and their progress causes the contacts 38, 41 and 45 to close and the contacts 34, 43 and 46 to open. In this way, the contacts 41 and 45 become energized through the common conductor 58, 60 and the contact 38, and this switches on the drain pump 20 and the low speed windings 28 of the motor 6, the latter ones through the inverter switches 65 and 66, causing the wash liquor to be let off the tub 4 and the rotating drum 5 to be driven according to a "delicate" reversing sequence. Furthermore, the heating element 15 is de-energized by the opening of the contact 43. The contact 36 is then closed on the high speed windings 29 of the motor 6, while the contact 41 is kept closed on the drain pump 20. As a result, the drum 5 is driven to rotate at spin-extraction speed, while the wash liquor continues at the same time to be let off the tub 4. In particular, the drum is made to rotate at this spin-extraction speed for a relatively long period of time, until all of the wash liquor is discharged from the tub. In this way the pre-wash cycle is terminated. Subsequently, at the beginning of the main wash cycle for said heavily soiled cottons and/or linens featuring such special soils as already described, the moving contact 54 of the pressure switch 26 is still set on the fixed contact 56, while the moving contact 51 of the pressure switch 23 switches over to the fixed contact 52. In their turn, the contacts 35 and 37 are connected with the solenoid valve 9 and the fixed contact 53 of the pressure switch 23, respectively, while the contact 40 is closed on the circuit comprising the high speed windings 29 of the motor 6 through the inverter switch 62. Finally, with the controlling device set in this way, the contact 42 turns out to be closed on the circulation pump 19, while the contact 45 turns out to be closed on the low speed windings 28 of the motor 6 through the inverter switches 65 and 66. In this way, the wash liquor is filled into the collector 13 of the washing machine to a reduced level as determined by the pressure switch 23, while the drum 5 stands still. Subsequently, while said circulation pump 19 continues to be switched on, said drum 5 is driven for long periods of time at the wash speed by the inverter switches 65 and 66 being energized, and for short periods at the spin-extraction speed owing to the energization of the inverter switch 62. While the contacts 37, 40, 42 and 45 are kept closed, the contract 43 is then closed on the circuit comprising the thermostats 16 and 17, as well as the heating element 15 and the relay 47. The energization of said relay then causes the cams of the controlling device to stop. As a result, the drum 5 and the circulation pump 19 are driven in the same way as described above, while the wash liquor is being heated up to the tripping temperature of the thermostat 16, i.e. 40°C. Then, as soon as said tripping temperature of the thermostat 16 is reached, the contact 64 of the same thermostat opens and the resulting de-energization of the relay 47 causes the cams of the controller device to start rotating again in the same way as described before. At this point, a wash period is carried out with the wash liquor maintained at a low temperature in order to ensure the effective removal of said particular soils and to prevent them from fixing onto the clothes. This wash period to remove such special soils can be also performed in a way differing from the above described one, in that a period can be provided for at the beginning of the main wash cycle during which the drum 5 and the circulation pump 19 are driven as in the previous cycle, but with no initial heating of the wash liquor, in order to have the same wash liquor sprayed unheated onto the clothes. Then, after such a fixed period of time as to equally ensure the effective removal of said special type of soil from the clothes, this first wash period is terminated, while the next one is started. While the contacts 35, 37, 40, 42 and 45 are still switched on their corresponding closed settings as described above, also the contacts 43 and 44 are now closed in order to bring about the energization of the heating element 15 which is parallel-connected with the circuit comprising the relay 47 in series with the contact 44, through the adjustable thermostat 17. The drum is still driven to alternately rotate at wash speed and spin-extraction speed, while the circulation pump 19 is constantly kept energized under the same conditions as described above. The thermostat 16 is short-circuited by the closure of the contact 44 and therefore, during this wash period, the heating of the wash liquor is controlled only through the adjustable thermostat 17. In this way, the relay 47 causes again the cams of the controlling device to stop and to further progress - as previously described - as a function of the set temperature of the wash liquor being reached or not. In particular, as soon as said wash liquor is heated to the temperature that has been set through the adjustable thermostat 17, the contact 63 of this thermostat opens, thereby causing the relay 47 to de-energize and to allow the cams of the controlling device to rotate to a further control position, where the contacts 37, 40, 42 and 45 are kept in their closed settings, while the contacts 43 and 44 open. As a result, a wash step is thereby performed for a fixed period of time, starting from the previously reached temperature of the wash liquor and under no further heating of the same wash liquor, while the drum and the circulation pump are driven in the same way as previously described. At the end of this wash step, during which the temperature of the wash liquor decreases very rapidly owing to a reduced volume of the same liquor, the contacts 43 and 44 close again, while the remaining contacts of the controlling device are kept in the same condition as before. In this way, the heating element 15 and the relay 47 are again energized, thereby creating the same operating conditions as previously described. Also in this case, therefore, the temperature of the wash liquor is controlled by the thermostat 17, the on/off cycling of which causes the heating element 15 to repeatedly switch on and off in such a way as to keep the temperature of the wash liquor within a close range of lower and upper limits. Subsequently, the contacts 37, 40, 42, 43, 44 and 45 open, while the contacts 34, 39 and 46 close. In this setting, the moving contact 54 of the pressure switch 26 furthermore switches over to the fixed contact 56, while the moving contact 48 of the pressure switch 22 changes over to the fixed contact 49. As a result, a further quantity of cold water is filled into the tub 4 - under no detergent addition - and this adds to the still warm liquor contained in the same tub until the normal filling level is reached as controlled by the pressure switch 22. In this setting, the drum is standing still. As soon as the normal filling level of the wash liquor is reached in the tub, the moving contact 48 of the pressure switch 22 changes over to the fixed contact 53, thereby causing the drum to be driven so as to rotate at low wash speed according to an "intensive" reversing sequence. The addition of further cold water to the hot wash liquor contained in the tub allows the same wash liquor and the clothes to be gradually cooled down, thereby preventing the clothes from unduly wrinkling and creasing during the subsequent rinses. Furthermore, owing to the fact that a rather large quantity of such further water is filled into the tub, there also occurs a substantial dilution of the detergent solution in the wash liquor, so that said detergent can partially be let off the clothes and the tub even before the actual rinsing sequence. Finally, the contacts 38, 41 and 45 close and the contacts 34, 39 and 46 open, so that the wash liquor is let off the tub, while the drum is rotated at low speed according to a "delicate" reversing rhythm. Rinse cycles are subsequently performed in a very traditional way. However, the number of rinse cycles performed in this case appears to be lower than the number of rinses usually required by washing machines of the current type, since the detergent contained in the wash liquor will have already been diluted and partially discharged at the end of the previous wash cycle. In this way, it is possible to obtain a satisfactory wash cycle, featuring a shorter duration and an optimized number of rinses as compared with the cycle described in the Patent Application No. 45734 A/83, filed by Industrie Zanussi SpA on December 6, 1983. The controlling device considered herein also allows "intensive" wash programmes to be performed for heavily soiled cottons and/or linens, featuring types of soil differing from the previously cited ones. In this case, however, since these type of soil do not require slow heating of the wash liquor as it was the case for the special soils previously described, these programmes can be performed without any pre-wash or preliminary soak cycle, so that the controlling device described herein can be directly set at the beginning of the main wash sequence, while having the adjustable thermostat 17 set by hand on the required wash temperature according to the type or degree of soil to be removed. This main wash sequence will then be carried out in the same way as previously described. "Intensive" wash programmes for not so heavily soiled cottons, linens and/or heat-resistant synthetics can be carried out by having the considered controlling device set at a wash step immediately following the one providing for a heating of the wash liquor to 40 °C, which is designed to remove soils of a special nature ad previously described, and the adjustable thermostat 17 set by hand on a wash temperature to be selected according to the soil to be removed. These programmes are performed in much the same way as the afore described "intensive" programmes for heavily soiled clothes. However, they turn out to be shorter than the latter ones in that they include neither a pre-wash or preliminary soak cycle nor the main wash steps calling for a heating to 40°C of the wash liquor. The controlling device herein considered also allows "intensive" wash programmes to be carried out for heat-resistant synthetics according to these clothes being heavily or not so heavily soiled. These "intensive" programmes are set and carried out in much the same way as the "intensive" programmes previously described. Therefore, also in this case pre-wash or pre-soak cycles can appropriately be added if heavily soiled heat-resistant sunthetics are to be washed through the removal of special soils of the same kind as previously cited. However, as opposed to the previously described programmes, these pre-wash or pre-soak cycles are carried out with the drum driven so as to rotate at low wash speed according to a "delicate" reversing sequence (rather than an "intensive" one as in the previous case). The subsequent main wash and rinse cycles of these "intensive" programmes are then carried out in the same way and to the same purposes as in the previously described programmes, except for the fact that - throughout these cycles - the drum is never made to rotate at spin-extraction speed, said drum instead driven to rotate at low speed according to alternate "intensive" and "delicate" reversing sequences during the wash step involving heating of the wash liquor to 40°C. Similarly, the controlling device herein described also allows "delicate" programmes of a traditional type to be carried out for washing woollens, silkens and delicate synthetics, said programmes being performed at normal levels of the wash liquor in the machine through the energization of the pressure switch 22 and the circulation pump 19, the latter during the heating stages of the wash liquor. Finally, the controlling device herein considered also includes safety devices for sensing the operating conditions of both the filtering element 14 and the heating element 15. In particular, as far as the filtering element 14 is concerned, it is necessary that the condition be immediately sensed and indicated in which said element appears to be excessively clogged by the soil particles and lint contained in the circulated wash liquor, in order to allow the user to clean or - if required - replace said filtering element, thereby ensuring a continued efficient circulation of the liquor itself. According to the invention, the operating conditions of the filtering element 14 are sensed by the pressure switch 26, which can be switched over to either of the two operating settings previously described, in the first one of these settings the moving contact 54 of said pressure switch being closed on the fixed contact 56 and in the second one said moving contact 54 being closed on the fixed contact 57 (Fig. 2). As a result, in the first case, i.e. when the filtering element 14 is sensed to be unclogged or not appreciably clogged, all of the electrical contacts of the controlling device herein considered can be appropriately energized through the common conductors 58 and 60. The same applies to the various operating parts and components of the washing machine. However, in the second case, i.e. when said filtering element is sensed to be unduly clogged, the power supply to the electrical contacts of the controlling device - and, therefore, to the various operating parts and components of the washing machine - is cut off, while the indicator light 32, or other appropriate optical, acoustic or similar signalling device, is on the contrary energized in order to call the attention of the user on this irregular condition of the filtering element 14. As soon as this element is cleaned or replaced, as the case may be, the pressure switch 26 will then sense a lower flow pressure of the wash liquor circulating through the flexible conduit 12, so that the moving contact 54 of said pressure switch closes again on the fixed contact 56, thereby de-energizing the indicator lamp 32. Finally, the safety device designed to sense the operating condition of the heating element 15 during the heating periods of the wash liquor when said element is energized, is formed by both thermostats 16 and 17 previously described. In particular, said heating element is able to operate in a correct way when it is entirely submerged in the wash liquor contained in the collector 13. In such a case, the heating element 15 will then be controlled by the thermostats 16 and 17 in the same way as previously indicated. However, if said heating element - due to failures occurring in the machine - happens to be only partially submerged in the wash liquor or to operate under dry conditions owing to the abscence of wash liquor in the collector 13, the same element would overheat very rapidly and this would be likely to damage it, as well as the clothes and the machine. According to the invention, the heating element 15 can in this case be immediately be de-energized by the tripping of the thermostat 17, as soon as the element heats up to the rated tripping temperature of said thermostat. As a result, this will safety prevent said heating element from overheating to any undesired extent. The controlling device according to this disclosure therefore allows clothes to be washed both with "delicate" laundering programmes of the traditional type, i.e. at normal levels of the wash liquor in the tub, and "intensive" laundering programmes carried out at reduced levels of the wash liquor in the tub. These latter programmes, in particular, allow clothes to be washed featuring any kind of soil, i.e. even the special soils previously indicated, under reduced water, detergent and power consumption values as compared with "intensive" programmes performed by washing machines of the traditional type. Such a controlling device can further be set so as to carry out very short "intensive" programmes for washing not so heavy soiled clothes, thus bringing about further water, detergent and power savings. A further advantage of this controlling device derives from the fact that it allows for a lower number of rinse cycles to be carried out owing to the above indicated reasons, thus cutting the duration of the wash programmes involved as well as the overall water consumption. Finally, owing to the presence of the pressure switch 26 and the thermostats 16 and 17, such a controlling device also provides for a total safety in the correct operation of both the filtering element 14 and the heating element 15.

Claims: 1. A controlling device for a clothes washing machine including a tub, a rotatable drum within said tub and a wash liquor collector communicating with the lower side of the tub though of the tub though a flexible conduit and with the lower side of the tub through a pipe and a circulating pump, said collector housing at least a filtering element, an electric heating element and thermostatic control means, the washing machine further including an inlet solenoid valve and level control means for the wash liquor, characterized in that said thermostatic control means comprise at least a first (16) and a second (17) thermostat, or the like, which are calibrated at a fixed tripping temperature and at adjustable tripping temperatures, respectively, and further characterized in that said level control means comprise a first (22) and a second (23) pressure switch, or the like, which are selectively connectable with said solenoid valve (9) and so calibrated as to determine that the wash liquor is fed up to a predetermined level in said tub (4) and to a lower level in said collector (13), said level control means further invluding a third pressure switch (26), or the like, which is connectable with both said first and second pressure switches (22, 23) and calibrated so as to detect the pressure of the wash liquor cirulating upstream of said filtering element (14), said first and second pressure switches (22, 23) being also selectively connectable to said heating element (15), in parallel with said circulating pump (19), through said first and second thermostats (16, 17) and at least a control relay (47) the energization or de-energization of which causes the cams associated with the various electrical contacts (34 to 46) of the controlling device to stop or to progress, respectively. 2. A controlling device according to claim 1, characterized in that said first thermostat (16) is connected in series with said control relay (47) and in parallel with said heating element (15), this latter in turn being connected in series with said second thermostat (17). 3. A controlling device according to claim 1, characterized in that said first thermostat (16) is capable of being short-circuited by a contact (44) which is connected in parallel therewith. 4. A controlling device according to claim 1, characterized in that said first and second thermostats (16, 17) are provided with corresponding normally closed contacts (64, 63). 5. A controlling device according to claim 1, characterized in that said first and secons pressostats (22, 23) are mechanically connected with said flexible conduit (12) and with the top of said collector (13), respectively, and are provided with relevant moving electrical contacts (48, 51) which are each one able to be positioned in two different operating positions, the first position corrsponding to the selectable connection of said moving contacts (48, 51) with said solenoid valve (9), whereas the second position corresponds to the selectable connection of said moving contacts (48, 51) with said circulating pump (19), said heating element (15), said thermostats (16, 17) and said control relay (47). 6. A controlling device according to claims 1 and 5, characterized in that said third pressostat (26) is mechanically connected with said flexible conduit (12) and is provided with a moving electric contact (54) which is connected to the supply mains and is able to be positioned in two positions, the first position corresponding to its connection with both moving contacts (48, 51) of said first and second pressostats (22, 23), when said filtering element (14) is free from dirt particles, the second position corresponding to the connection of said moving electric contact (54) with at least a signal lamp (32), or the like, when said filtering element (14) is completely clogged by dirt particles. 7. A controlling device according to the foregoing claims, in a clothes washing machine which also comprises at least an electric motor for driving said drum, provided with windings for the high spinning speed and the low washing speed, respectively, the low speed winding being energized intermittently and for alternating rotation by an inverter switch, characterized in that the high speed winding (29) is energized by the moving contact (51) of said second pressostat (23), selectively via a further inverter switch (62) of the timer, for short intervals, when said moving contact (51) is positioned in its second working position, or via a further contact (36) of the timer, for intervals longer than the foregoing ones, when said moving contact (51) is positioned in its first working position.

Inventors: BABUIN, PIERO, CARGNEL, GIUSEPPE, MORI, MAURIZIO
Applicants: INDUSTRIE ZANUSSI S.P.A.
Application year: 1986
Main classification: D06F33
IPC codes: D06F33