EP2138624B1

EP2138624B1 - Method for washing and/or rinsing in a laundry washing machine with increased energy saving.

Info

Publication number: EP2138624B1
Application number: EP09158273A
Authority: EP
Inventors: Silvano Fumagalli
Original assignee: Candy SpA
Current assignee: Candy SpA
Priority date: 2008-06-24
Filing date: 2009-04-20
Publication date: 2011-11-30
Anticipated expiration: 2029-04-20
Also published as: ATE535639T1; EP2138624A1; ES2376614T3

Abstract

Method for washing and/or rinsing in a laundry washing machine with a plurality of nozzles (6,8) for releasing the liquids into a tank (1) and an opening (4) for the discharge of said liquids, a reservoir (3) arranged below the bottom portion of the tank and able to hold a predetermined amount of washing or rinsing liquid, said reservoir (3) being hydraulically connected to said nozzles (6,8), to said opening (4) in the bottom portion the tank, to an outlet (13) outside the machine, to a water source (14), to a pump (11) for discharging liquids from the machine and to a pump (10) for recirculating liquids, said method comprising a phase of wetting the laundry placed inside the drum (2) by recirculating a predetermined amount of washing and/or rinsing liquid, such that, during the recirculation, a dynamic level of the liquid results which does not exceed the horizontal plane (A) tangential to the edge (2a) of the drum (2) when considered in its lowest position having regard to the axis of rotation (X-X).

Description

The present invention relates to a method for washing and/or rinsing in a laundry washing machine of the type comprising a tank, said tank being provided with a bottom portion, a drum with perforated walls for the laundry to be washed arranged inside the tank and mounted for rotating around a substantially horizontal axis, a hydraulic system comprising a plurality of nozzles for releasing the liquids into the tank and an opening in the lowest part of the tank bottom portion for the discharge of said liquids, a reservoir arranged below the bottom portion of the tank and able to hold a predetermined amount of washing and/or rinsing liquid, said reservoir being hydraulically connected to said nozzles, to said opening in the lowest part of the tank bottom portion, to an outlet outside the machine, to a water source, to a pump for discharging liquids from the machine and to a pump for recirculating liquids from and to the tank passing through said reservoir, said method comprising a phase of wetting the laundry placed in the drum by loading a predetermined amount of washing and/or rinsing liquid into the tank, a plurality of phases of recirculating the washing and/or rinsing liquid in order to wash and rinse the laundry respectively and, finally, at least one phase of discharging the used washing and/or rinsing liquid.
Laundry washing machines operating in accordance with the washing and/or rinsing method described above are known in the art of this field.
An example is illustrated and described in US-A-5,345,637 .
As is evident from said document of the known art, the liquid for wetting the laundry placed in the drum in order to be washed is initially loaded via the release into the tank of a specific amount of liquid, depending substantially on the weight of the laundry to be washed, drawn from an appropriate source of hot or cold water.
The liquid passes through the laundry and accumulates in the bottom of the tank until reaching a particular level through which the drum with the laundry passes, resulting in the liquid permeating the laundry during rotation thereof.
It appears obvious that, in accordance with such known technology, a considerable amount of liquid is required to wet the laundry, which itself constitutes a cost and which, moreover, results in a significant resistance to the movement of the drum containing laundry when said drum passes through the liquid in the lower path of its rotation inside the tank.
This occurrence reflects the need to include an electric motor in the machine provided with suitable torque and therefore suitable power, with relative absorption of energy, in order to rotate the drum even during the initial phase of wetting the laundry.
It has already been suggested in the known art to limit the amount of washing and/or rinsing liquid in such a way that, during the operative washing and/or rinsing phases in which the drum is rotating and the recirculating pump withdraws liquid from the tank and returns it thereto, the dynamic level of liquid does not exceed the plane tangential to the tank at the lowest point of its profile so as to eliminate or reduce the resistance which the liquid poses against the movement of the drum when it passes through the liquid.
Examples of other known technology of this type aimed at reducing the energy used by the laundry washing machine are described in EP-A-0,726,349 and also in EP-A-0,597,509 .
However, in accordance with this latest known technology, it is noted that the amount of liquid, when released into the hydraulic system of the machine and in particular into the tank of said machine in order to wet the laundry, reaches a pressure head in static conditions which necessarily exceeds the plane tangential to the edge of the drum since, only in dynamic conditions due to the recirculation during the operative washing and/or rinsing phases, the level of liquid is made to decrease to the level of the aforementioned plane tangential to the edge of the drum.
This means that during the phase of wetting the laundry, when the drum rotates in order to distribute the liquid in the laundry, the drum containing the laundry moves but is still struck by liquid which poses resistance against the motion of said drum.
Therefore, in accordance with the known art mentioned above, it is still necessary to use an electric motor, the power of which is suitable and greater than that which would be strictly necessary during the operative phases of washing and rinsing, during which, thanks to recirculation, the dynamic level of liquid decreases to below the plane tangential to the edge of the drum, no longer obstructing the movement thereof.
The object of the present invention is to be able to further reduce the absorption of energy by the laundry washing machine, thus reducing the torque and power necessary for the electric motor rotating the drum as well as that necessary for heating the washing liquid.
This and other objects which will be become clearer from the following description are achieved with the method according to the invention in accordance with claim 1.
The invention will now be described in more detail with reference to the illustrated drawing of Fig. 1, in which a cross-section of a tank for a laundry washing machine with an associated drum is shown.
With reference to the aforementioned schematic drawing, the tank of a laundry washing machine is indicated by the reference numeral 1. The tank 1 is provided with a bottom portion la having a circular shape.
Inside the tank 1 a drum 2 is arranged, which, in a conventional manner, is set in rotation by an appropriate electric motor and relative mechanical transmission, not shown, around a substantially horizontal axis X-X.
A reservoir 3 is provided below the bottom portion of the tank 1 and it is connected to the lowest part of the bottom portion of the tank, where an opening 4 is provided, via a conduit 5 and to a plurality of nozzles 6 via the recirculation conduit illustrated by the line 7. Although the reservoir 3 is shown in the drawing as being vertically below the tank 1, is should be understood in the description and in the relevant claims that it can be located below the tank but at a side of the vertical line passing through the opening 4 of the tank bottom portion. The nozzles 6 are arranged in the upper part of the tank 1 and allow washing and/or rinsing liquid to be released through the perforated peripheral wall of the drum 2.
Another nozzle 8, fed via the conduit illustrated by line 9, is in turn connected to the conduit 7, and may be provided for releasing washing and/or rinsing liquid at the access door to the drum 2.
The conduits 7 and 9 feeding the nozzles 6 and 8 are connected to a recirculation pump 10 provided on the reservoir 3, upon which a discharge pump 11 is also mounted.
Said discharge pump 11 is connected via a conduit 12 to an outlet 13 outside the laundry washing machine.
An external water source, identified with the reference numeral 14 loads the hydraulic system with the necessary and predetermined amount of liquid for operation of the machine via a valve 15 and a conduit 16.
A detergent cassette drawer 17 may be inserted into the path of the conduit 16 if the machine programme provides for this.
A pressure gauge 18 is arranged on the reservoir 3 for measuring and thus regulating the height of the liquid column which is introduced into the hydraulic system of the machine when the valve 15 is opened.
In order to heat the washing liquid, the reservoir 3 comprises a resistance element 19 powered electrically via external terminals 20.
A conventional filter, not shown, is also inserted into the hydraulic system of the machine, for example in the discharge conduit 12 or, alternatively, in the recirculation conduit 7.
In accordance with the invention, the phase of wetting the laundry placed in the drum 2 is carried out by activating the recirculation pump 10 and loading a predetermined amount of liquid into the hydraulic system of the machine.
Therefore, the recirculation pump 10 sends the liquid to the nozzles 6 and 8 resulting in the laundry being wetted, even with a small amount of liquid.
Preferably, this amount of liquid is such that a dynamic level is able to be established in the system which does not exceed the horizontal plane A tangential to the edge 2a of the drum 2, when considered at its lowest point having regard to the axis of rotation X-X.
Consequently, in accordance with a preferred feature of the invention, if the drum 2 is simultaneously set in rotation in order to wet the laundry and to diffuse liquid thereinto, it rotates without there being a level of liquid in the tank which may resist the movement.
It follows that the torque and power required for the motor driving the drum may be reduced since, both during the wetting phase and during the other operating phases of the machine, the recirculation function keeps the dynamic level of liquid below the plane A tangential to the edge 2a of the drum.
This results in a significant energy saving and also makes it possible to reduce the size of the motor, thus reducing the torque with consequent savings in cost.
Recirculation during the phase of wetting the laundry, in accordance with the invention, allows the hydraulic system of the laundry washing machine to be loaded and thus used even with a reduced amount of liquid relative to the amount strictly necessary, so the dynamic level does not exceed or remains at the level of the horizontal plane A tangential to the edge 2a of the drum 2, having regard to the axis of rotation X-X.
Experimental tests have shown that even loading a reduced amount of liquid, for example an amount between 400 and 600 millilitres, likely to result, in a machine having a washing capacity of 9 kg of laundry, in a static level not exceeding or substantially coincidental with the horizontal plane B tangential to the bottom portion of the tank at the lowest part of its profile, is sufficient to satisfactorily wet the laundry in the drum due to the fact that said wetting is achieved by recirculation of the liquid via the pump 10.
It has also been proven that, in the phase of wetting the laundry, substantially ¾, of the total amount of liquid loaded into the hydraulic system of the machine is recirculated.
The reduced amount of water also results in a significant saving of electrical energy used for heating the water during the successive washing phases.
It has been calculated that, overall, a reduction of approximately 25 % of consumed energy can be achieved with the present invention.

Claims

Method for washing and/or rinsing in a laundry washing machine of the type comprising a tank (1), said tank being provided with a bottom portion (1a), a drum (2) for the laundry to be washed arranged inside the tank and mounted for rotating around a substantially horizontal axis (X-X), a hydraulic system comprising a plurality of nozzles (6, 8) for releasing the liquids into the tank (1) and an opening (4) in the lowest part of the tank bottom portion (1a) for the discharge of said liquids, a reservoir (3) arranged below the bottom portion of the tank and able to hold a predetermined amount of washing or rinsing liquid, said reservoir (3) being hydraulically connected to said nozzles (6, 8), to said opening (4) in the lowest part of the tank bottom portion, to an outlet (13) outside the machine, to a water source (14), to a pump (11) for discharging liquids from the machine and to a pump (10) for recirculating liquids from and to the tank (1) passing through said reservoir (3), said method comprising a phase of wetting the laundry arranged in the drum (2) by loading a predetermined amount of washing and/or rinsing liquid into said hydraulic system of the machine, a plurality of phases of recirculating the washing and/or rinsing liquid in order to wash and rinse the laundry respectively and, finally, at least one phase of discharging the used washing and/or rinsing liquid, characterised in that said phase of wetting the laundry in the drum is achieved by loading into said hydraulic system of the machine, an amount of liquid so that, during recirculation, a dynamic level of liquid results which does not exceed the horizontal plane (A) tangential to the edge (2a) of the drum (2) when considered in its lowest position having regard to the axis of rotation (X-X).
Method according to claim 1, wherein the amount of liquid loaded into said hydraulic system of the machine is such that its level, in static conditions, does not exceed the horizontal plane (B) tangential to the lowest part of the bottom portion (1a) of tank (1).
Method according to claim 1, wherein the portion of liquid used in the stage of wetting the laundry inside the drum via recirculation is substantially equal to ¾ of the total amount of liquid present in said hydraulic system, when considered in static conditions.
Method according to anyone of claims from 1 to 3, wherein the amount of liquid originating from the water source and loaded into said hydraulic system is between 400 and 600 millilitres.