Control arrangement for the spin extraction phase in clothes washing machines

Abstract: Control arrangement for the spin-extraction phase in clothes washing machines, adapted to cause said phase to be terminated when the water contained in the washload has been fully removed therefrom and pumped out of the tub, thereby optimizing the washing cycle in its duration. Control arrangement comprising an electronic counter means (4) and an electronic comparator means (5), both connected with the microcontroller means (1), which is provided to control the washing cycle selected by the user, along with the drain pump (3) and a pressure switch (2) adapted to detect a pre-determined filling level of the water in the washing tub. The counter (4) measures the time elapsing from the moment at which the drain pump (3) is switched off during the final spin-extraction phase, to the moment at which the water in the washing tub reaches said pre-determined filling level as detected by said pressure switch (2). If the so measured time is shorter than a pre-set reference time (T rif ), said drain pump (3) is switched on again; otherwise said drain pump (3) is kept in its de-energized state and the spin-extraction phase is terminated.

Description: The present invention relates to a control arrangement for the spin-extraction phase of a washing process in a clothes washing machine, in particular a clothes washing or a combined clothes washing and drying machine, adapted to provide an effective, optimized final spin-extraction action on the washload according to the quantity and the type of clothes in the washload. Washing machines of the above cited type are known (see for exemple document US-A-4 662 193), which comprise a washing tub accomodating a rotating drum provided to hold the washload and capable of being rotatably driven by driving means of a traditional type in order to accomplish the assigned task of washing clothes through a sequence of subsequently performed washing and rinsing phases, as controlled by a cycle or sequence control device consisting of a programme control-timer switch of the electromechanical type, which may possibly be associated with an electronic microcontroller means. Said rinsing phases are performed so as to be carried out within periods of time having a pre-determined duration, as controlled by the action of said programme control-timer switch and/or electronic microcontroller means, while pre-determined amounts of fresh water from the mains are each time delivered into the washing tub of the machine, under the control of such level control devices as a pressure switch of a more or less traditional type or, possibly, level sensors of a per sè known type that are built into the machine, for any amount and type whatsoever of clothes loaded in the drum, said drum being driven to first rotate alternately at the washing speed in either one of its directions of rotation and then, in the final phases of the rinsing process, at the spin-extraction speed in a single direction of rotation, whereas the drain pump of the machine is switched on, so that the washload is spin-dried and the extracted water collecting in the tub is at the same time discharged outside the machine. This method of performing the rinsing process in its various phases, while actually enabling the clothes to be washed and rinsed in an essentially effective way within periods of time of a pre-determined duration regardless of the amount and the properties (especially the type of fabrics, which may absorb moisture to a more or less marked extent) of the clothes making up the washload, does not on the other hand enable the washing cycles to be optimized in terms of duration, as a consequence of said properties and amount of the washload being duly taken into account, so as it would on the contrary be desirable in view of adapting each time the duration of said process phases to the actual conditions of the washload. It therefore is the purpose of the present invention to eliminate the afore cited drawbacks in a clothes washing machine through the implementation of a control arrangement for the spin-extraction phase of said machine, said control arrangement being adapted to optimize the duration of said phases according to the actual amount and the actual properties of the clothes that have each time to be laundered. This control arrangement is embodied with such construction characteristics as essentially described with particular reference to the appended claims. Such a control arrangement according to the present invention will anyway be further described by way of non-limiting example with reference to the single accompanying drawing, in which the Figure shows the electrical wiring schematics of said control arrangement. The afore cited Figure is a schematical view of the control arrangement according to the present invention, which is built in a clothes washing machine, in particular a clothes washing or a combined clothes washing and drying machine, comprising a washing tub accomodating a rotating drum provided to hold the washload and capable of being rotatably driven by an electric motor (all these items not being shown in the Figure) in order to accomplish the assigned task of washing clothes through a sequence of subsequently performed washing and rinsing phases, as well as comprising a cycle control device consisting in an electronic microcontroller means 1 of a traditional type, which is adapted to be set in a per sè known way so as to control, in accordance with the type and the amount of the clothes that are each time introduced in the drum for being washed, the progress of the basically pre-set washing cycles. The afore cited clothes washing machine further comprises at least a level control arrangement to control the filling level of the wash liquor or the rinse water in the tub. This control arrangement may for instance consist of a pressure switch 2 or a similar type of level sensing device, which may be constituted by either an electromechanical pressure switch or an analog-output electronic pressure sensor of a traditional type. Said machine also comprises a drain pump 3, which is connected to the lower portion of the washing tub and electrically linked to the microcontroller means 1, along with said pressure switch 2, said pump being adapted to discharge the wash liquor or the rinsing water outside said tub at the end of the corresponding phases of the laundering process. Finally, said clothes washing machine also comprises at least an electronic counter means 4 and an electronic comparator means 5, or a similar element for comparing electric quantities, which are connected, along with the other electric components, in the electrical circuit of the machine in the way and to the purposes as described hereinafter. In particular, the pressure switch 2 is selected with such ratings as to be able to measure very low pressures of the liquors in the tub (ie. in the range of 20 to 30 mm WC), while the pressure detection intake (not shown) of the same pressure switch is arranged in a position located outside the tub, in as low a location as possible. Furthermore, said pressure switch can be noticed as being connected with the electronic counter means 4 through the electronic microcontroller means 1, the latter being set in such a way as to be able to generate an electric signal 9 capable of suppressing counting by the counter means 4 upon water reaching the highest filling level in the tub, as pre-determined by the setting of the same pressure switch ("full" level). The drain pump 3 can in turn be noticed as being connected with said electronic counter means 4 through said electronic microcontroller means 1, while the latter is arranged so as to be able to generate a further electric signal 10 capable of enabling said counter means 4 to start counting upon said drain pump 3 being switched off by said electronic microcontroller means during the final washload spin-extraction phase, in which all of the rinsing water filled into the tub is discharged outside the same tub. The purpose of the electronic counter means 4 is to measure the time elapsing from the moment in which said drain pump 3 is de-energized by said electronic microcontroller means 1, up to the moment in which said highest water filling level, as pre-determined by the setting of the pressure switch 2, is reached, ie. a condition in which the liquor absorbed by the clothes is gradually extracted therefrom after spinning, thereby returning inside the tub. This time measurement is applied to a first input 6 of said electronic comparator means 5 and is continuously compared with a pre-set, experimentally determined reference time T rif generated by said microcontroller means 1, and corresponding to the ultimate condition in which water has actually been extracted to an adequate extent from the various kinds or types of fabrics in the washload so that they are now returning just negligible amounts of liquor to the tub of the machine, so that the final washload spin-extraction phase can reasonably be considered as being practically completed, said reference reference time information being applied to the other input 7 of said comparator means. In such a manner, therefore, in the condition in which the time being measured by the counter means 4 is shorter than said reference time T rif , the liquor contained in the washload undergoing spin-extraction is still given off in the tub in an appreciable amount, ie. there is still an appreciable amount of water to be extracted from the washload, so that it will be adequate to let the rotating drum of the machine go on to perform further spin-extraction phases in order to extract said remaining liquor from the washload, whereas in the condition in which the time measured by said counter means 4 is equal to or longer than said reference time T rif , this means that the washload now contains just an unappreciable amount of residual liquor and, as a consequence, the same washload does no longer need undergoing spin-extraction, ie. no further spin-extraction is practically needed. Furthermore, said electronic comparator means 5 is connected through its output 8 with the microcontroller means 1, whereas two different levels of signal can occur at said output 8 of the comparator means 5, such as for instance a zero level and a pre-set level in accordance with the comparison of the time applied to the input 6 with the time applied to the input 7 of said comparator means. These two different operational conditions of the output 8 of the comparator means 5 are detected by the microcontroller means 1, which then reacts by generating a corresponding electrical signal, as described hereinafter. In particular, in the case where the time measured by the counter means 4 is shorter than the reference time T rif when the washing machine is operating in the afore described conditions, the level of the signal occurring at the output 8 of said comparator means 5 is such as to cause the microcontroller means 1 to generate an electrical signal 11 that is arranged to switch on again the drain pump 3 of the washing machine through the control of the same microcontroller means, whereas in the case where said time measured by the counter means 4 is equal to or longer than the reference time T rif , under the corresponding operational conditions of the washing machine as previously illustrated, the other level of the signal occurring at the output 8 of said comparator means 5 is such as to cause said microcontroller means 1 to generate a further electrical signal 12 that is arranged to keep said drain pump 3 in its de-energized state and switch off the electric motor of the washing machine, thereby putting an end to the final washload spin-extraction phase of the washing process, under the control of said microcontroller means 1. The way in which the control arrangement according to the present invention operates for controlling a spin-extraction phase is therefore fully apparent. First of all, the microcontroller means 1 starts by being set to perform a pre-determined washing cycle according to the type and the quantity of the clothes to be laundered, whereas the progress of said washing cycle will be controlled automatically by said microcontroller means and is terminated in the usual way by a sequence of final spin-extraction phases aimed at extracting the rinsing water from the clothes. During the last one of these final spin-extraction phases, wherein the drum is driven to correspondingly rotate at its highest spin-extraction speed under simultaneous energization of the drain pump 3 to discharge said rinsing water outside the tub, said microcontroller means 1, in the usual way, causes said drain pump 3 to be switched off after a pre-determined period of time, which is considered to be adequate to allow the largest possible amount of the water contained in the tub to be pumped outside. As soon as the drain pump 3 is de-energized and switches off, the microcontroller means 1 is arranged to detect this operational condition of the same pump and, at the same time, to generate the afore cited electrical signal 10 enabling the function of said electronic counter means 4 which therefore starts counting the time elapsing from the moment at which the same drain pump is switched off. Said counter means then stops counting said time as soon as the microcontroller means 1 detects, through the corresponding signal 13, the state in which the "full" level of the pressure switch 2 is reached. The value of the time having in this way been counted is then applied to the first input 6 of the electronic comparator means 5 and compared with the reference time T rif that is applied to the second input 7 of the same comparator means. Therefore, under these conditions, since the drain pump 3 is switched off, water is no longer discharged outside the tub and, as a consequence, the tub itself is gradually filled with the water being extracted from the washload, and still contained in the clothes, the filling level of the water in said tub being constantly monitored by the pressure switch 2 and detected through said signal 13. In the case where the time measured by said counter means, and used by the water extracted from the clothes to fill the tub up to said "full" level of the pressure switch 2, is shorter than said pre-determined reference time T rif , in the condition in which the clothes still contain a considerable amount of water, the signal occurring at the output 8 of the comparator means 5 emphasizes a determined level, such as for instance a zero level, so that said microcontroller means 1 is caused to generate the electrical signal 11 enabling the drain pump 3 to switch on again. As a consequence, said drain pump 3 starts again discharging the water extracted from the clothes and collecting in the tub. In the opposite case, ie. in the case where the afore cited time measured by said counter means is equal to or longer than said pre-determined reference time T rif , in the condition in which the clothes contain just a negligible amount of residual water and the tub is therefore no longer collecting any appreciable amount of water extracted from the clothes, ie. in the condition in which the clothes do not need any further spin-extraction for moisture removal, the signal occurring at the output 8 of said comparator means emphasizes another pre-determined level causing the microcontroller means 1 to generate the electrical signal 12 that is arranged to keep the drain pump 3 in its de-energized condition, ie. switched off, and to switch off the power supply to the electric motor of the washing machine, thereby causing the final spin-extraction phase concluding the clothes washing process to terminate. In a quite advantageous way, said electronic counter means 4 and said electronic comparator means 5 can be directly included in the structure of said microcontroller means 1. The control arrangement for the spin-extraction phase of the washing process of a clothes washing machine provided according to the present invention does in this way enable the duration of the final spin-extraction phase to be each time adapted automatically to both the actual characteristics of the different types of clothes and the actual amount of clothes in the washload, and therefore to the actual water adsorbing capacity of the same washload, while ensuring effective water extraction from the clothes and optimizing the way in which the whole washing process is ultimately performed.

Claims: Control arrangement for the spin-extraction phase in clothes washing machines, in particular clothes washing or combined clothes washing and drying machines, comprising a washing tub accomodating a clothes-holding rotating drum capable of being rotatably driven by per sè known motor drive means, an electronic microcontroller means for setting and controlling the progress of each washing cycle selected by the user, at least a pressure switch or similar level-control means for detecting a pre-determined filling level of the liquor inside said washing tub, and a drain pump connected with said tub for discharging the liquor extracted from the clothes and collecting in said tub during the final spin-extraction phase, characterized by counting means (4) and comparing means (5) functionally connected with said electronic microcontroller means (1), along with said pressure switch (2) and said drain pump (3), said counting means (4) being arranged to count the time elapsing from the moment at which said drain pump (3) is de-energized by said microcontroller means (1), up to the moment at which said pre-determined filling level of the liquor in the tub is reached, as controlled by said pressure switch (2), and said comparing means (5) being arranged to compare the time counted by said counting means (4) with a pre-determined reference time (T rif ) corresponding to the condition in which the clothes in the drum no longer contain any appreciable amount of residual water following adequate spin-extraction, and said comparing means being further arranged to cause said drain pump (3) to either be switched on again or be kept in its de-energized state, while cutting off the power supply to said motor drive means and causing the spin-extraction phase to terminate, under the control of said electronic microcontroller means (1), when said time counted by said counting means (4) is shorter than or is equal to or longer than said pre-determined reference time (T rif ), respectively. Control arrangement according to claim 1, characterized in that said counting means comprise an electronic counter (4) connected with said comparing means (5) and with said pressure switch (2), as well as with said drain pump (3), through said microcontroller means (1) , said electronic counter (4) being capable of receiving from said microcontroller means (1) an enable signal (10) and a disenable signal (9) to respectively start and stop said time counting function, when said microcontroller means (1) causes the drain pump (3) to be switched off and, respectively, when said pressure switch (2) detects the attainment of the pre-determined filling level by the liquor in the tub. Control arrangement according to claim 2, characterized in that said comparing means comprise an electronic comparator (5) provided with a first and a second input (6, 7) that are respectively connected with said time-counting electronic counter (4) and said microcontroller means (1) providing said reference time (T rif ) information, as well as provided with an output (8) connected with said microcontroller means (1) and arranged to provide two different levels of signal to either energize said drain pump (3) or keep it in its de-energized state, respectively, according to the result of the comparison of the time counted by said electronic counter (4) with said pre-determined reference time (T rif ), as respectively applied to said first and said second input (6, 7). Control arrangement according to claim 3, characterized in that said electronic counter (4) and said electronic comparator (5) are capable of being integrated into said microcontroller means (1).

Inventors: CIMETTA SILVANO, FRUCCO GIUSEPPE, CIMETTA, SILVANO, FRUCCO, GIUSEPPE
Applicants: ZANUSSI ELETTRODOMESTICI, ZANUSSI ELETTRODOMESTICI S.P.A.
Application year: 1993
Main classification: D06F33
IPC codes: D06F33, D06F35