METHOD FOR WASHING LAUNDRY, WASHING MACHINE AND PROGRAM FOR CARRYING OUT SUCH A METHOD

Description

Scope of the invention

[0001] The present invention relates to the field of machine washing processes, implementing several phases of laundry treatment.

[0002] The invention relates more particularly to the wetting phase of the laundry, at the beginning of a washing process.

[0003] It also concerns a washing machine implementing such a process, and more specifically a rotating drum washing machine.

[0004] It also relates to a program suitable for implementation by a control module of a washing machine to implement such a process. Previous art

[0005] Many washing machines consist of a perforated drum containing the laundry, which rotates inside a tub that can be filled with wash water. These washing machines typically employ a laundry washing process, or wash cycle, comprising a series of several laundry treatment phases. At the beginning of a wash cycle, one of the first phases is usually a pre-soaking phase.

[0006] During this pre-wetting phase, wash water is introduced into the drum, and the drum is rotated. The laundry inside the drum comes into contact with the water until it is wet. The wash cycle can then continue with this wet laundry.

[0007] Several solutions are known for implementing the laundry wetting phase.

[0008] For example, document WO 2008 / 003577 A1 discloses a laundry processing method in a washing machine comprising a tub, a drum, and a sensor for determining the liquid level in the tub. During a wetting phase, water is added to a predetermined quantity while the drum rotates. When the predetermined quantity of water is reached, the drum rotation and water filling cease, and the hydrostatic pressure due to the released water is evaluated to determine the amount of laundry in the drum.

[0009] These solutions generally aim to effectively wet laundry by saturating it with water, while minimizing the amount of water used. It is indeed important to limit this amount of water in order to reduce both water and energy consumption during the laundry wash cycle. Such a limitation of the amount of water used during the wetting phase helps washing machines meet the increasing demands for energy and resource conservation.

[0010] According to a known solution, the laundry wetting phase can include several successive stages of filling the tub and rotating the drum, in order to minimize the amount of water used for washing.

[0011] Thus, during the initial filling stage, the tub is filled with wash water up to a predetermined fill level. This fill level is normally relatively low and insufficient to wet a large amount of laundry.

[0012] This initial filling stage is followed by the first drum rotation stage, during which the drum rotates to bring the laundry into contact with the wash water. During this stage, the laundry absorbs wash water, lowering the water level in the tub.

[0013] After this rotation of the drum, water is then added up to the same predetermined fill level, during a second filling stage, to replace the water absorbed by the laundry.

[0014] This second filling stage is followed by a second drum rotation stage, during which the machine drum is rotated to bring the laundry into contact with the water.

[0015] Finally, during a third filling stage, called final filling, water is once again added to the drum until the same predetermined filling level is reached.

[0016] This solution for implementing the laundry wetting phase has several advantages.

[0017] Indeed, during the drum's rotation, the amount of wash water absorbed by the laundry varies, depending on the quantity of laundry and its absorbency. Thus, a large load, or particularly absorbent laundry, absorbs more water during the drum's rotation. Consequently, the amount of wash water added during the second and third filling stages naturally adjusts to the characteristics of the laundry being washed.

[0018] Furthermore, such a solution is particularly simple and robust. It does not implement complex computer programs, which can be a source of failure, and requires only basic information about the water level. Indeed, it is only necessary to know if a predetermined water level has been reached, not the precise height of the water in the tank. This information can be provided by a simple, inexpensive, robust, and reliable sensor.

[0019] Implementing such a solution optimizes the amount of water in the drum, adapting it to the amount of laundry and its absorbency. It also has the advantage of being simple to install and program, and therefore inexpensive to manufacture washing machines.

[0020] With energy-saving requirements imposing increasingly strict standards on washing machine manufacturers, it is nevertheless necessary to evolve washing cycles to make them more economical in terms of resources, particularly water and energy. Objectives of the invention

[0021] The present invention aims to improve upon prior art solutions by overcoming their drawbacks.

[0022] In particular, one objective of the invention is to provide a washing process, or washing cycle, in a washing machine, which optimizes the amount of washing water consumed.

[0023] A particular objective is to optimize the amount of water consumed during the laundry wetting phase of a laundry wash cycle.

[0024] One objective of the invention is to save the energy needed to heat the water used for washing clothes.

[0025] Another objective of the invention is to provide such a method which can be implemented by robust, reliable and inexpensive equipment, and which does not affect the reliability and robustness of the washing machine.

[0026] A particular objective of the invention is to provide such a process which can be easily implemented on existing washing machines, without modification of their hardware components.

[0027] The invention also aims to provide a washing machine that implements such a washing process. Description of the invention

[0028] These objectives, as well as others which will become clearer later, are achieved using a laundry washing process with a washing machine comprising a tub in which a drum, containing the laundry to be washed, is driven in rotation by a drive device, this process comprising a laundry wetting phase, comprising at least: a first step of filling the tub with wash water, up to a first predetermined filling level, a first step of rotating the drum, a second step of filling the tub with wash water, up to a second predetermined filling level. According to the invention, the laundry wetting phase also includes, after the first drum rotation stage, and before the second filling stage, a waiting stage during which the drum is stationary for a period of at least 20 seconds.

[0029] This waiting period between drum rotation and the subsequent drum filling allows the free water retained in the laundry to drain into the tub. During the subsequent filling stage, less water is needed to reach the predetermined level, thus reducing the amount of water consumed during the filling phase. The energy required to heat this water in later phases of the wash cycle is also lower. Implementing this solution therefore saves resources and energy.

[0030] Advantageously, the first predetermined filling level and the second predetermined filling level are identical.

[0031] The same level sensor can therefore be used, which facilitates the implementation of the process.

[0032] According to an advantageous embodiment, during the waiting stage, said drum is stationary for a period of at least 30 seconds.

[0033] Such a waiting period allows, in view of the experiments carried out by the inventors, for substantial water savings to be achieved.

[0034] Preferably, during the said waiting period, the said drum is stationary for a period of at least one minute.

[0035] Such a waiting period allows, in view of the experiments carried out by the inventors, for even greater water savings to be achieved.

[0036] According to an advantageous embodiment, the laundry wetting phase comprises at least: A first stage of filling the tub with wash water, up to a predetermined first fill level; a first stage of drum rotation; a second stage of filling the tub with wash water, up to a second predetermined fill level; a second stage of drum rotation; a third stage of filling the tub with wash water, up to a third predetermined fill level and at least one waiting step, between the first rotation step and the second filling step and / or between the second rotation step and the third filling step.

[0037] Advantageously, in this case, the second predetermined filling level and the third predetermined filling level are identical.

[0038] The invention also relates to a washing machine comprising: a tank in which a drum, containing the laundry to be washed, is driven in rotation by a drive device, and means for filling this tank with wash water. this washing machine also comprising a control module capable of controlling at least said filling means and said drive device, characterized in that said control module implements a washing process according to any one of the preceding claims.

[0039] Advantageously, this washing machine includes a water level detection device, capable of communicating information about the washing water level in the tub to the control module.

[0040] According to a preferred embodiment, this water level detection device includes a pressure switch.

[0041] The invention further relates to a program product, suitable for implementation by a control module of a washing machine comprising a tub in which a drum, containing the laundry to be washed, is driven in rotation by a drive device, and means for filling this tub with wash water, this program implementing, when executed by the control module, a laundry washing process as described above. List of figures

[0042] The invention will be better understood upon reading the following description of preferred embodiments, given by way of simple figurative and non-limiting example, and accompanied by the figures, among which: [ Fig. 1 ] there figure 1 is a schematic representation of a washing machine according to an embodiment of the invention. Fig. 2 ] there figure 2is a schematic representation of the steps in a laundry wetting phase of a washing process according to an embodiment of the invention. Fig. 3 ] there figure 3 is a graph representing the evolution of the quantity of water in the tank and the rotation speed of the drum during a phase of wetting laundry in a process according to an embodiment of the invention. Detailed description of embodiments of the invention

[0043] There figure 1 The diagram schematically represents a washing machine 1 according to an embodiment of the invention. This washing machine 1 comprises a tub 2, suitable for holding the wash water. A pipe 21, closed by a solenoid valve 22, supplies the tub 2 with wash water. The tub 2 is also equipped with a drain system, not shown in the diagram. figure 1allowing the liquid it contains to be emptied. Finally, it contains a heating element 23 capable of heating the wash water it contains.

[0044] The liquid used for wetting laundry is generically referred to in this application as "wash water". This liquid may, however, be water combined with a washing product, such as laundry detergent, or with any other product, without this affecting the invention described.

[0045] A cylindrical drum 3 is mounted inside the tub 2 and pivots around an axis 31. This drum 3 can be driven in rotation by a drive device (not shown). This drum 3 is designed to hold laundry 5 intended for washing. Typically, this drum is perforated, meaning that water present in the tub 2, outside of the drum 3, can enter the drum 3 without restriction.

[0046] Tank 2 is also equipped with a water level detection device, which can be any level sensor known to those skilled in the art. In the embodiment shown, this water level detection device consists of a pressure switch 4 connected to a compression chamber 41 communicating with tank 2. The pressure switch is connected to the compression chamber via a small-diameter hose forming a pressure switch pipe 42.

[0047] The pressure switch 4 is an electrical contactor that changes state under the effect of pressure exerted on a flexible diaphragm. When the wash water level rises in the tank 2, the air pressure increases in the compression chamber 41 and in the pressure switch tube 42. This trapped air exerts pressure on the flexible diaphragm of the pressure switch 4.

[0048] When the water level in tank 2 reaches a predetermined level represented by the dotted line 40, which corresponds to the top of the wash cycle, the flexible diaphragm of the pressure switch 4 is subjected to sufficient pressure to press a pin in the pressure switch and flip the contactor. In the embodiment shown, this flip of the contactor causes the solenoid valve 22 to close.

[0049] The use of a pressure switch in a washing machine is very common and particularly advantageous. Indeed, such sensors are particularly simple, inexpensive, and robust. They do not allow for very precise monitoring of the water level, but they generate a signal when the water level reaches the high mark. In this case, this pressure switch 4 is configured to emit a signal when the water level in the drum 2 reaches the level represented by the dotted line 40 on the diagram. figure 1 .

[0050] In other possible embodiments of the invention, the level detection device may be a sensor of a different type. For example, this level detection device may consist of an analog pressure switch that delivers an electrical signal proportional to the water level in the tank. A predefined water level in the tank then corresponds to a predefined value of the electrical signal provided by the pressure switch. It is thus possible, with such an analog pressure switch, to detect when several distinct predefined levels are exceeded, or even to monitor the evolution of the wash water level in the tank in real time.

[0051] The washing machine 1 is designed to carry out a washing process, or wash cycle. It includes for this purpose a control module (not shown), capable in particular of controlling the solenoid valve 22 and the drum drive device 3, and of receiving signals from the pressure switch 4. This control module implements a control program, which can be likened to a computer program, enabling the washing machine 1 to carry out the washing process, or wash cycle.

[0052] The washing process, or wash cycle, comprises several phases, including a laundry wetting phase during which the following steps are carried out successively: a first step of filling the tank 2, by opening the solenoid valve 22, until the signal emitted by the pressure switch 4 indicates that the wash water in the tank reaches the predetermined level 40, a first step of rotating the drum 3, in order to wet the laundry 5 in the wash water contained in the tank 2, a second step of filling the tank 2, by opening the solenoid valve 22, until the signal emitted by the pressure switch 4 indicates that the wash water in the tank reaches the predetermined level 40, a second step of rotating the drum 3, and a third step of filling the tank 2, by opening the solenoid valve 22, until the signal emitted by the pressure switch 4 indicates that the wash water in the tank reaches the predetermined level 40.

[0053] According to the invention, the laundry washing process is modified, compared to prior art processes, to introduce one or more waiting stages during the laundry wetting phase. figure 2 schematically represents the sequence of steps implemented during such a laundry wetting phase, in a washing process according to an embodiment of the invention.

[0054] There figure 3 represents two curves: a first curve 81 is representative of the quantity of water contained at the bottom of the tank 2 during the implementation of the laundry wetting phase, and the curve 82 is representative of the rotation speed of the drum 3 during the implementation of the laundry wetting phase.

[0055] Thus, according to one possible embodiment of the invention, the laundry wetting phase implemented by the washing machine 1 comprises the steps described below.

[0056] The wetting phase begins with a first filling step 91 of the tank, during which the solenoid valve 22 is open until the signal emitted by the pressure switch 4 indicates that the wash water in the tank reaches the predetermined level 40. As shown in curve 81, the quantity of water at the bottom of the tank increases rapidly during this step, until it reaches the predetermined level 40.

[0057] This filling stage is followed by a first stage of drum rotation 92. During this first phase of drum rotation 92, the amount of water at the bottom of the tub decreases due to the absorption of the wash water by the agitated laundry.

[0058] In the embodiment shown, the duration of this rotation step is predetermined. However, in other embodiments, this step may end when the water level in the tub reaches a predetermined low level. Furthermore, in the embodiment shown, this first drum rotation step 92 begins after the end of the first filling step 91. This prevents the drum rotation from disturbing the water level and thus the reading of the wash water level in the tub. However, in other embodiments, this first drum rotation step 92 may begin before the end of the first filling step 91, and these two steps may at least partially overlap.Finally, if curve 82 shows a constant drum rotation speed during this first stage of drum rotation 92, it is also possible that the drum rotation is variable, or that the rotation is intermittent, for example by alternating rotations in different directions.

[0059] Following this initial rotation, the wetting phase continues with a first waiting phase 93, lasting 30 seconds, during which the drum 3 remains stationary. During this first waiting phase 93, the amount of wash water at the bottom of the tub 2 increases slightly again, due to the free water retained by the laundry 5 flowing into the tub 2. For noticeable effectiveness, this waiting phase must last at least 20 seconds. A longer duration, for example one minute, can further improve its effectiveness.

[0060] Following this first waiting stage, the wetting phase continues with a second filling stage 94 of the tank, during which the solenoid valve 22 is open until the signal emitted by the pressure switch 4 indicates that the wash water in the tank reaches the predetermined level 40. As shown in curve 81, the quantity of water at the bottom of the tank increases rapidly again during this stage, until it reaches the predetermined level 40.

[0061] This second filling stage is followed by a second drum rotation stage 95, during which the amount of water at the bottom of the tub decreases slightly again due to the absorption of wash water by the laundry.

[0062] Following this initial rotation stage, the wetting phase continues with a second waiting stage 96, lasting 30 seconds, during which the drum 3 remains stationary. During this second waiting stage 96, the water level rises slightly due to the free water contained in the laundry flowing into the tub.

[0063] Finally, at the end of this first waiting stage, the wetting phase ends with a third filling stage 94 of the tank, during which the solenoid valve 22 is opened until the signal emitted by the pressure switch 4 indicates that the wash water in the tank reaches the predetermined level 40.

[0064] Introducing such waiting periods between a drum rotation stage and the subsequent drum filling stage to a predetermined level is particularly advantageous. This allows free water, which may be retained in the laundry 5 without being absorbed by it, to drain into the tub 2.

[0065] During the filling stage following this waiting stage, the amount of water that must be added to bring the wash water level up to the predetermined level 40 is then lower than if the filling stage had immediately followed the drum rotation stage, without the free water retained by the laundry having time to flow into tub 2.

[0066] The amount of water consumed during the filling phase is therefore lower. Furthermore, since this amount of water is lower, the energy required to heat this water in subsequent phases of the wash cycle is also reduced. Implementing the solution of the invention thus results in resource and energy savings.

[0067] Introducing these waiting stages during the filling phase might raise concerns about increasing the overall wash cycle time, which seems detrimental. However, the inventors found that this overall time was not necessarily increased and could even be slightly shortened by introducing these waiting stages. This is because, since less water is used for washing, the heating time for this water is reduced.

[0068] As an example, the inventors compared two wash cycles performed by the same machine, loaded with the same laundry, under identical conditions. The first wash cycle included a wetting phase comprising three successive filling stages, separated by drum rotation stages, with no waiting periods. The second wash cycle included a wetting phase comprising three successive filling stages, separated by drum rotation stages, followed by waiting periods.

[0069] During the first wash cycle, The first filling stage consumed 9.1 liters of wash water, the second filling stage consumed 3 liters of wash water, the third filling stage consumed 1.3 liters of wash water. The amount of wash water consumed during the filling phase was therefore 13.4 liters. The energy consumed during this wash cycle, including the energy for heating the wash water, was 0.673 kWh. This heating of the wash water lasted 11 minutes and 36 seconds, and the total wash cycle lasted 159 seconds.

[0070] During the second wash cycle, implementing the waiting steps according to the invention, The first filling stage consumed 9.2 liters of wash water, the second filling stage consumed 2.2 liters of wash water, the third filling stage consumed 1.1 liters of wash water. The amount of wash water consumed during the filling phase was therefore 12.5 liters. The energy consumed during this wash cycle, including the energy for heating the wash water, was 0.560 kWh. This heating of the wash water lasted 7 minutes and 28 seconds, and the total wash cycle lasted 157 minutes.

[0071] Thus, adding the waiting stages according to the invention during the laundry wetting phase allows for a saving of 0.9 liters in wash water consumption, a reduction in heating time, and a saving of 0.113 kWh. Furthermore, the inventors verified that this modification to the wash cycle did not result in any degradation of the laundry washing performance.

[0072] In the preferred embodiment of the invention described above, the wetting phase has three successive filling stages, separated from each other by drum rotation stages followed by waiting stages.

[0073] However, the invention can be advantageously implemented with a filling phase comprising only two successive filling steps, separated by a drum rotation step followed by a waiting step. It could also be implemented with a filling phase comprising more than three successive filling steps.

[0074] Furthermore, it would also be possible, during a laundry wetting phase comprising more than two successive filling phases, that one or more filling steps are followed by a drum rotation step followed by a waiting step, before the next filling phase, while one or more other filling steps are followed by a drum rotation step, without a waiting step before the next filling phase.

[0075] Such embodiments may, in certain cases, make it possible to obtain at least some of the advantages of the present invention.

Claims

1. Method for washing laundry in a washing machine (1) comprising a tub (2) in which a drum (3), containing the laundry to be washed, is rotated by a drive device, said method comprising a laundry wetting phase, comprising at least: - a first step (91) of filling said tank with washing water, up to a predetermined first filling level (90), - a first step (92) of rotating the drum, - a second step (93) of filling said tank with washing water, up to a second predetermined filling level, wherein said laundry wetting phase also comprises, after said first drum rotation step, and before said second filling step, a waiting step (93) during which said drum is stationary for a period of at least 20 seconds.

2. Washing method according to the preceding claim, wherein said first predetermined filling level and said second predetermined filling level are identical.

3. Washing method according to either of the preceding claims, wherein, during said waiting step, said drum is stationary for a period of at least 30 seconds.

4. Washing method according to the preceding claim, wherein, during said waiting step, said drum is stationary for a period of at least one minute.

5. Washing method according to any of the preceding claims, wherein said laundry wetting phase further comprises: - a second step (95) of rotating the drum, - a third step (96) of filling said tank with washing water, up to a predetermined third filling level, and at least one waiting step (96), between said second rotation step and said third filling step.

6. Washing method according to the preceding claim, wherein said first predetermined filling level, said second predetermined filling level and said third predetermined filling level are identical.

7. Laundry washing machine (1) comprising: - a tub (2) in which a drum (3) containing the laundry to be washed is rotated by a drive device, and - means for filling this tank with washing water, said laundry washing machine also comprising a control module suitable for controlling at least said filling means and said drive device, wherein said control module implements a washing method according to any of the preceding claims.

8. Laundry washing machine according to the preceding claim, comprising a water level detection device (4, 41, 42), suitable for communicating to said control module information relating to the level of washing water in said tub.

9. Laundry washing machine according to the preceding claim, wherein said water level detection device comprises a pressure switch (4).

10. Program product, suitable for being implemented by a control module of a laundry washing machine (1) comprising a tub (2) in which a drum (3), containing the laundry to be washed, is rotated by a drive device, and means for filling this tub with washing water, said program implementing, when executed by said control module, a laundry washing method according to any of claims 1 to 6.