GB2339705A

GB2339705A - Washing machine with self-cleaning recirculation filter

Info

Publication number: GB2339705A
Application number: GB9916547A
Authority: GB
Inventors: Luca Bertolin
Original assignee: Electrolux Zanussi Elettrodomestici SpA; Electrolux Zanussi SpA
Current assignee: Electrolux Zanussi Elettrodomestici SpA; Electrolux Zanussi SpA
Priority date: 1998-07-17
Filing date: 1999-07-14
Publication date: 2000-02-09
Anticipated expiration: 2019-07-14
Also published as: GB2339705B; IT245320Y1; DE29911677U1; FR2781237A1; ITPN980039U1; FR2781237B3; GB9916547D0

Description

2339705 FILTER FOR CLOTHES WASHING MACHINES OR THE LIKE OF THE SPRAY TYPE

The present invention relates to a filter for washing machines of the spray 5 type.

In that type of machine, the washing liquid is sprayed directly on to the items of laundry, the washing liquid being continuously drawn up from the bottom of the tub by way of a recirculation line which is separate from the discharge line, each line being provided with a pump which operates alternately with the other.

EP-A-024091 I discloses a clothes washing machine with a recirculation pump, a discharge pump and a collector for collecting the washing liquid, which is disposed below the washing tub. Accommodated in the collector are both the waterheating element and a filter which is formed in one piece from a close-mesh section and a coarse-mesh section.

A filter of that kind suffers from the disadvantage of being effective only in machines provided with a catchment collector, that is. to say a type of machine which is obsolete by virtue of the excessive level of water consumption. In addition the frequency with which the end user has to attend to the filter for periodic cleaning operations is very high, precisely because the filter is a single unit, with the danger of damaging the close- mesh section which is obviously delicate.

US-A-3727435 discloses a clothes washing machine with a special filtering unit which comprises a discoidal filter with close meshes, accommodated in an intermediate position between an upper outlet for the washing liquid connected to the recirculation pump and a lower outlet connected to the discharge pump. Below the filter the filtering unit also comprises an intake directly connected to the bottom of the washing tub disposed there above. When the recirculation pump is actuated for spraying the laundry, the washing liquid moves in the filtering unit from the bottom upwardly and the filter which experiences a certain degree of elastic deformation retains the foreign objects in the lower part of the filtering unit. When the discharge pump is actuated the movement of the washing liquid is reversed whereby the filter experiences a certain degree of elastic deformation downwardly while the fluff and any other foreign object would have to be detached and expelled from the machine. Indeed, by virtue of the fact that the intake for the washing liquid into the filtering unit is below the filter, the asserted self- cleaning effect thereof is problematical; in particular fluff can easily remain caught up within the filtering unit, insofar as just the suction effect on the part of the discharge pump is indeed insufficient to separate the fluff from the fine meshes of the filter and discharge it from the machine.

Finally, US-A-4485645 shows a clothes washing machine in which a pump, in dependence on the position of an electrically operated three-way valve disposed on its outlet, provides either for recirculation of the washing liquid for spraying the laundry which has been loaded into the tub or discharge of the washing liquid. The machine is provided with a so-called trap which comprises two half-shell portions which are separably connected together, the upper half-shell portion being connected to the intake of the pump and having passing there through a vertical connecting pipe which starts from the bottom of the tub and which, at a position corresponding to the outlet opening, has a horizontal flange which divides the body of the trap into two parts and is provided with a plurality of vertical tubes of irregular shape. The larger foreign objects cannot pass through the above mentioned vertical tubes and remain in the lower half-shell portion of the trap while the fluff flows freely through the tubes to the intake of the pump.

The main shortcoming of that know structure lies in the fact that in the phases of the operating cycle in which the washing liquid is discharged from the machine, the larger foreign objects remain in the trap and the user is thus forced to implement periodic and labourious maintenance operations to keep the machine efficient.

It would be desirable, and this constitutes an aim of the present invention, to provide a filter for a clothes washing machine of the spray type, which is truly self cleaning, of simple and reliable construction, and which requires practically no maintenance.

According to the present invention there is provided [1] Features and advantages of the invention will be clearly apparent from the following description of a preferred but not exclusive embodiment of the invention with reference to the accompanying drawings in which:

Figure I shows a three-dimensional view of a filter according to the invention; Figure 2 shows a front view of the filter of Figure 1; Figure 3 is a view of the filter in section taken along line IH-III in Figure 2; and Figure 4 shows a partial view of a domestic spray-type clothes washing machine to which is fitted a filter as shown in the preceding Figures, the machine being illustrated in a vertical sectional plane perpendicular to the axis of rotation of the drum.

As can be seen from Figures I to 3 a filter according to the invention comprises a body I in one piece of metal (for example aluminium. alloy) or plastics material (for example polypropylene) of an approximately duckbill-shaped configuration with an outwardly curved end portion 2 and with the mouth opening 4 provided with a flange 3. The body 1 of the filter has a lateral surface 6 which is not exactly circular but polygonal - see in particular Figure I - with a lower flattened portion 7 and an upper groove 8, which have a certain inclination towards the interior, that is to say towards the flange see in particular Figure 3. The end portion 2 has a moderate number of holes 5 which are disposed on a plurality of concentric circles which when viewed from the front are of a circular shape - see Figure 2 - while when viewed in section they comprise, in the direction from the end portion 2 towards the mouth opening 4, a first convergent portion followed by a second divergent portion - see Figure 3. That shape is made possible by virtue of the relatively great thickness of the end portion 2.

Figure 4 clearly shows the use of the filter of the preceding Figures insofar as it illustrates (with the omission of the parts which are not relevant for understanding the invention) the lower region of a domestic clothes washing machine which comprises an oscillating washing tub 10 which encloses a drum 11 with a plurality of holes on the lateral surface thereof and, immediately above its flat bottom 12, an electrical heating element 13. Beside the heating element 13 the tub 10 has a circular hole 14 which is provided with an external lip to be joined (with the interposition of a sealing element and by means of a clip, which are not shown) to the mouth 19 of a connection 16 which constitutes the intake line of a pump 17 for recirculation of the washing liquid. The recirculation pump 17 is preferably supported by the stationary structure (diagrammatically indicated in Figure 4 by reference numeral 24) by means of an elastic pad 25 for the purposes of reducing the noise level of the clothes washing machine. The delivery line 18 of the recirculation pump 17 terminates at an upper point (not shown) of the tub 10 to provide for direct spraying of the laundry.

In this preferred embodiment of the invention the axis X of the hole 14 and thus also of its external lip is parallel to a radius of the drum I I while the axis Y of the connection 16 and the axis of rotation Z of the impeller (not shown) of the recirculation pump 17 are substantially on the same plane as the flat bottom 12 of the tub 10, that is to say virtually horizontal, see Figure 4. In that way the water consumption and thus also the power consumption of the clothes washing machine are minimised.

The filter is capable of being fitted into the clothes washing machine in such a way that the lower flattened portion 7 and the upper groove 8 of its body 1 remain held in position by interference by corresponding male portions (not shown) of the external lip of the hole 14 of the tub 10 in such a way that the flange 3 of the body I is fixed to the mouth opening 19 of the connection 16.

In accordance with a basic feature of the invention the end portion 2 of the body 1 of the filter with the holes 5 is substantially tangential to the internal surface 15 which at that point is inclined and connected to the adjacent flat bottom 12 of the tub - see Figure 4.

The geometrical and dimensional characteristics of the filter such as the duckbill shape of its body 1, the number, sections and arrangement of the holes 5 on the end portion 2 are experimentally defined in such a way as to ensure that fluff and other foreign objects of small dimensions which are entrained by the washing liquid during the periods of operation of the recirculation pump 17 do not remain caught up there. At the same time the holes 4 must be capable of retaining foreign objects of larger dimensions (buttons, clips and the like) which could cause malfunctions of the recirculation pump 17.

Preferably the transverse dimensions of the holes 5 are greater than or equal to the diameter of the holes on the lateral surface of the drum 11.

The clothes washing machine also includes a second pump 20 which serves for discharge of the washing liquid during the spin phases (in which the drum I I rotates at high speed) and at the end of the cycle. The intake line 21 of the pump 20 is sealingly connected to a hole 22 disposed beneath the heating element 13 in the bottom 12 of the tub while the delivery line 23 is connected to the final discharge pipe (this is also not shown).

The filter of the present invention thus has the advantage that, whenever the discharge pump 20 of the clothes washing machine is in operation and at the same time the recirculation pump 17 is stopped (that is to say one or more times during each cycle of operation) the suction intake of the discharge pump 20 causes a flow of washing liquid in the direction of the arrow F5, that is to say towards the pump 20. That flow produces a washing-away action on the end portion 2 of the body I of the filter since it entrains towards the discharge hole 22 the objects of larger dimensions which are retained by the filter in such a way as to permit discharge thereof from the tub 10. That washing-action is all the more effective during the spin phases when the drum 11 rotates at high speed in the direction of the arrow F4 and the washing liquid is expelled from the drum I I through the 5 holes in its lateral surface substantially radially in the direction of the arrows F I, F2, F3 (and thus approximately along the axis X of the hole 14 of the tub 10 in which the filter is fitted) - see Figure 4. That effect is particularly significant when the filter is designed as described hereinbefore.

Experiments carried out on a prototype have also demonstrated that in itself a filter according to the invention does not require any maintenance action on the part of the user during the useful life, of the order of many years, of a domestic clothes washing machine. However, if necessary, it is always possible for the technical assistance service department to remove the filter by undoing the connection of the body I obtained by the lower flattened portion 7 and the upper groove 8 with the associated parts of the external lip of the hole 14 and the mouth opening 19 of the connection 16, and removing the filter downwardly by gripping it by means of the flange 3.

Finally a further advantage of the present invention lies not only in a low cost of production of the filter, but also the fact that it can be adopted without at the same time compelling a designer to make substantial structural modifications to the existing clothes washing machine.

Claims

A washing machine for clothes or like items having a washing tub which encloses an aperture rotary drum, a recirculation pump and a discharge pump for the washing liquid which operate alternately, a filter disposed along the intake line of said recirculation pump and having a body provided with meshes which are capable of retaining foreign bodies of larger dimensions during the periods of operation of the recirculation pump, wherein said meshes are provided on a surface of the body which is substantially tangential to the internal surface of the tub at a position corresponding to a hole adjacent to the bottom of the tub and joined to a connection which constitutes the intake line of the recirculation pump whereby said surface of the body is subjected to a washing-out action during the period of operation of the discharge pump and/or the spin phases.
2. A machine according to claim 1, wherein the body of the filter is in the shape of a duckbill, the end portion of which constitutes the surface provided with said meshes.
3. A machine according to claim 2, wherein said meshes are formed by a number of holes in the end portion of the body.
4. A machine according to claim 3, wherein the holes are of a circular cross section and comprise in the direction of the washing liquid during the periods of operation of said recirculation pump an initial convergent portion followed by a divergent portion.
5. A machine according to claim 3 or 4, wherein the minimum cross-section of the holes is of dimensions which are no larger than the holes provided on the lateral surface of the drum.
6. A machine according to any one of claims I to 5 wherein the filter body is provided with means which pen-nit fixing thereof by interference respectively to a hole in the tub and the associated mouth opening of a connection which constitutes the intake line of said recirculation pump.
7. A machine according to claim 6 wherein the means for fixing the filter comprises a flange which extends along the mouth opening, a flattened portion and an oppositely disposed groove of its body and in associated parts of an external lip of said hole and the mouth opening of said connection to the recirculation pump.
8. A machine according to claim 5, 6 or 7 wherein the axis of said connection and the axis of the recirculation pump are substantially on the same plane as the flat bottom of the tub, that is to say practically horizontal.
9. A machine according to any one of the preceding claims characterised by 10 being produced in one piece from metal or plastics material.
10. A clothes washing machine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.