EP0542137B1

EP0542137B1 - Method for the treatment of laundry in a laundry washer/drier combination

Info

Publication number: EP0542137B1
Application number: EP92118987A
Authority: EP
Inventors: Emanuele Sacconato; Silvano Cimetta
Original assignee: Zanussi Elettrodomestici SpA
Current assignee: Electrolux Zanussi Elettrodomestici SpA
Priority date: 1991-11-11
Filing date: 1992-11-05
Publication date: 1995-08-02
Anticipated expiration: 2012-11-05
Also published as: DE69203829T2; IT1256274B; ITPN910073A1; DE69203829D1; ITPN910073A0; EP0542137A1

Description

The invention relates to a method for the treatment of laundry in a laundry washer/drier combination, as defined in the preamble part of claim 1.
Known laundry washer/drier combinations are designed for the sequential execution of laundering and drying operations. During the laundering operation, the drum containing the laundry is rotated at a low laundering speed in alternating directions, and during the final rinsing operation, it is rotated at an increased spin-drying speed for effectively squeezing the laundry partly dry prior to its being dried in the conventional manner.
From FR-A-2546540, a laundry and dryer machine which is able to operate at speeds between 500 and 780 rpm is known. After the final rinsing operation, a plurality of operational steps is executed to prepare the laundry for the drying operation. During the first step, the drum is rotated at a comparatively low speed of 50 to 120 rpm, the second step is characterized by several bursts in which the drum is rotated for a short time with a rotational speed of up to 480 rpm. Then, a third step follows in which after a slowly increasing rotational speed from 50 to 150 rpm, the drum is rotated at a constant speed of about 780 rpm. Finally, during the last step the drum is rotated in alternating directions at a low speed of about 50 rpm.
The rotation of the drum at the spin-drying speed may, particularly in the case of machines operating at very high spin-drying speeds of the order of 1200 to 1500 rpm, lead to the undesirable result of the laundry adhering to the inner walls of the drum, giving rise to difficulties with regard to detaching the laundry from the drum walls at the end of the spin-drying operation.
As a result thereof, the laundry may exhibit the tendency to accumulate in separate areas of the drum's inner wall, rather than being evenly distributed over the entire area of the inner wall surface of the drum as would be desirable for permitting it to be rapidly and substantially uniformly dried. The uneven distribution of the laundry may again result in its being yellowed and/or partially scorched in the course of the subsequent drying operation.
It is an object of the present invention to guard against the occurrence of undesirable effects of the type explained above in a laundry washer/drier combination by the employ of a method for the treatment of the laundry effective to permit the latter to be detached from the inner walls of the drum prior to the drying operation.
This object is attained by a laundry treatment method having the features of claim 1. Preferred embodiments are subject to various dependent claims.
The invention will be more fully understood from the following description, given by way of non-restrictive example with reference to the attached drawing, the only figure of which diagrammatically illustrates a time-chart of the variations of the rotary speed of the drum in a laundry washer/drier combination functioning in accordance with the present laundry treatment method.
This laundry treatment method is particularly applicable to laundry washer/drier combinations operating at elevated spin-drying speeds of the drum and includes the execution at the end of the various laundering operations of any selected laundering cycle of the operative steps to be described as follows:
In particular, the operative steps of the present laundry treatment method are initiated subsequent to the charge of water for the final rinsing operation having been admitted to the tub enclosing the drum containing the laundry, by rotating the drum at a low speed in alternating directions.
In the diagram of the drawing figure, this final rinsing operation is indicated at A and has a duration of for example three minutes, during which the drum is rotated at a speed of 55 rpm. with its direction of rotation being reversed at 8 sec. intervals. At the end of this operation, the rinsing water is completely discharged from the tub during a first step indicated as phase B and having a maximum duration of for example 20 to 40 sec.. During this phase, the drum continues to be alternatingly rotated at low speed, in the present example for a period of 4 sec. in one direction and for 12 sec. in the opposite direction, at a speed of 55 rpm..
Subsequently, in the second step of the present laundry treatment method, the drum is rotated in a series of short bursts of progressively increasing spin-drying speeds separated from one another by intervals during which the drum is rotated at low speed in alternating directions. In the present example, the present method provides the execution of four such spin-drying bursts at rotary speeds of 400, 600, 800 and 1000 rpm.. In particular, during the first phase of this step of the present method, indicated at C and having a duration of 15 sec., the drum is initially rotated at a low speed of in the present example 55 rpm, with only a single rotation in each direction for a duration of 3 sec., followed by a short burst, in the present example of a duration of 4 sec., of rotation at the spin-drying speed rapidly attaining a maximum of 400 rpm., whereupon the electric motor of the machine acting to rotate the drum is deenergized to permit the rotary speed of the drum to drop to the previous value. During the subsequent second, third and fourth phases of this step of the method, indicated respectively at D, E and F and having a duration each of 27 sec., the drum is initially rotated at the same low speed of in the present example 55 rpm, the direction of rotation being reversed five times at 3 sec. intervals, followed by a short burst, with a uniform duration of 4 sec., of spin-drying rotation at maximum speeds of 600, 800 and 1000 rpm, respectively, whereupon the rotary speed is again reduced to the previous value.
In the first part of the third step of the present treatment method, generally indicated as phase G and having a duration of 45 sec. in the present example, the drum is initially rotated at the low laundering speed of in the present example 55 rpm, with the direction of rotation being reversed at intervals of 12 and 4 sec. respectively, followed by its rotary speed being gradually and linearly increased to a value of in the present example 85 rpm, which is then maintained for the remainder of this phase for permitting a uniform distribution of the laundry over the inner walls of the drum to be established.
Subsequently initiated are further phases of the present treatment method, in which the drum is exclusively rotated at the spin-drying speed which is progressively increased from an initial value to a final value, in the present example from 650 rpm to 1500 rpm.
To this purpose the second part of the third step is in the present case further sub-divided into seven consecutive phases designated by reference letters H, I, L, M, N, O, P, the first of these phases having a duration of 10 sec, while the duration of the remaining phases is 50 sec each.
In particular, during the first phase H of this second part of the third step of the method, the rotary speed of the drum is rapidly increased from the previously attained value of 85 rpm to a spin-drying speed of 650 rpm, which is held for a short instance, to be subsequently again rapidly increased to the higher spin-drying speed of 85o rpm, which is then again held for a short instance.
In the subsequent second phase I of this second part of the third step of the present method, the rotary speed of the drum is rapidly increased from the previously attained value to a faster spin-drying speed of in the present example 900 rpm, which is then held constant for the remainder of this phase of the third step. In all of the remaining phases of this second part of the third step, the rotary speed of the drum is rapidly increased from the previously attained value to a somewhat faster spin-drying speed of successively 1000, 1100, 1200, 1400 and 1500 rpm, the respective rotary speeds thus attained being maintained constant throughout the respective phases of this step.
This sequence of spin-drying operations is conducive to obtain an efficient squeeze-drainage of the laundry and a uniform distribution of the laundry on the inner walls of the drum rather than localized accumulations thereof.For permitting the thus treated laundry to become readily detached from the inner walls of the drum to thereby ensure uniform and effective drying of the laundry in the subsequent drying operation of the laundry washer/drier combination without the danger of scorching and/or yellowing, the present treatment method finally provides the execution of a fourth and a fifth step indicated respectively with phases Q and R and having a duration each of 10 min in the present example.
In particular, for the full duration of the fourth step the drum is rotated at a low speed of about 30 to 35 rpm in alternating directions, in the present example for 4 sec in one direction and for 12 sec in the opposite direction, while during the fifth step, the drum is still rotated at a low, albeit somewhat higher speed of 55 rpm, the direction of rotation being reversed at regular 10 sec intervals.
By suitably adapting the program timer of machines of the type under consideration, it is thus possible to automatically control the execution of a particular cycle of relatively short duration in accordance with the present method and subsequent to the laundering cycle, to thereby establish the conditions for the efficient drying of the laundry and for safely avoiding the occurrence of the above described undesirable effects.

Claims

A method for the treatment of laundry in a laundry washer and drying combination comprising a laundering tub enclosing a laundry containing drum adapted to be rotated at different high speeds i.e. above 800 rpm by an electric motor of the appliance for the execution of the laundering and rinsing operation and a subsequent laundry drying operation, said method being executed subsequent to the end of the last rinsing operation and prior to the initiation of the laundry drying operation for completely discharging the water from the laundering tub, comprising the execution of several operation steps (1 to 5), wherein in said first step (B), the drum is rotated at a low speed, in the second step (C, D, E, F), the drum is rotated alternately at a low speed and at short bursts with a spin drying speed, in the third step, the drum is rotated initially at an increasing low speed and then at spin drying speed and in the fourth step, the drum is rotated at a low speed in alternating directions, said method being
characterized in that
during the first step (B), the drum is rotated during several periods in alternating directions, at a speed of preferably 55 rpm,
during the second step (C, D, E, F), the drum is rotated during several phases (C to F), each phase having several periods of rotations in alternating directions at low speed followed by a short burst whereby the speed value of the burst in different phases increase sequentially preferably from 400 rpm to 1,000 rpm,
during the third step, the initial slow rotation (G) is carried out in alternating directions at preferably 55 rpm and then at another low speed preferably 85 rpm, and then the drum is rotated for several phases (H to P) having increasing spin drying speeds from an initial value to a final value preferably from 650 rpm to 1,500 rpm, whereby the actual spin drying rotary speed of the drum being maintained constant for the duration of each phase and rapidly increasing between successive phases and,
during the fourth and a fifth step, the drum is rotated preferably at 30 to 35 rpm and 55 rpm respectively.
A method according to claim 1, characterized in that the spin-drying rotation bursts of the drum in the second step are executed at speeds of 400, 600, 800 and 1000 upm, respectively, and for a durction of 4 sec.
A method according to claim 1 or 2, characterized in that during the high-speed rotation periods of the third step, the drum is rotated at speeds of 650, 850, 900, 1000, 1100, 1200, 1400 and 1500 upm, respectively.
A method according to one of claims 1-3, characterized in that during the fourth step, the drum is rotated for a period of 12 sec in one direction, and for a period of 4 sec in the opposite direction.
A method according to one of claims 1-4, characterized in that in the fifth step the drum is rotated for periods of 10 sec in each of its directions of rotation.