EP3702510B1

EP3702510B1 - Laundry washing machine

Info

Publication number: EP3702510B1
Application number: EP19159501.6A
Authority: EP
Inventors: Igor Colin; Marcin Lorenc; Diana Moruzzi; Ashish Gupta; Narayanan K R RUKESH
Original assignee: Electrolux Appliances AB
Current assignee: Electrolux Appliances AB
Priority date: 2019-02-26
Filing date: 2019-02-26
Publication date: 2023-08-09
Anticipated expiration: 2039-02-26
Also published as: PL3702510T3; EP3702510A1

Description

The present invention relates to a laundry washing machine.
More in detail, the present invention relates to a front-loading home laundry washing machine, to which the following description specifically refers purely by way of example without this implying any loss of generality.
As is known, a front-loading home laundry washing machine generally comprises: a substantially parallelepiped-shaped, self-supporting boxlike outer casing structured for resting on the floor; a substantially horizontally-oriented and nearly cylindrical, cup-shaped washing tub which, in use, contains the washing liquid and is suspended in floating manner inside the casing, with the front mouth directly facing a laundry loading-unloading through opening formed in the front wall of the casing; a substantially cylindrical, cup-shaped rotatable drum which is structured for accommodating the laundry to be washed, and is fitted in axially rotatable manner inside the washing tub with the concavity facing the laundry loading-unloading opening, so as to be able to freely rotate inside the washing tub about its substantially horizontally-oriented, central axis locally coinciding with the longitudinal axis of the washing tub; an elastically-deformable bellows which watertight connects the front mouth of the washing tub to the laundry loading-unloading opening formed in the front wall of the casing; a porthole door which is hinged to the front wall of the casing to rotate to and from a closing position in which the door closes the laundry loading-unloading opening in the front wall of the casing for watertight sealing the washing tub; and an electrically-powered motor assembly which is structured for driving into rotation the rotatable drum about its longitudinal axis inside the washing tub.
To reduce vibrations of the drum during spin phases with unbalance loads, today's high end laundry washing machines are additionally provided with at least one and usually two ball balancing rings which are rigidly secured to the drum body perfectly coaxial to the drum rotation axis.
More specifically, each ball balancing ring is substantially circular in shape and is usually secured to the drum body, outside of the drum and adjacent to the front or rear rim of the drum cylindrical wall, coaxial to the drum rotation axis.
Each ball balancing ring moreover basically comprises: a rigid, toroidal housing having inside a perfectly circular, closed annular inner cavity; and a number of heavy spherical masses accommodated in free movable manner inside the inner cavity of the toroidal housing together with a viscous liquid that damps out the movement of the spherical masses inside the inner cavity. The toroidal housing is secured to the drum body perfectly coaxial to the drum rotation axis, so that the annular inner cavity lies/extends on a plane perfectly perpendicular to the drum rotation axis.
During spin phases, the spherical masses tend to group together and to move altogether inside the inner cavity so as to balance the unbalanced load (laundry) momentarily placed inside the drum.
EP1862577 A2 and EP1862577 A2 disclose a front-loading laundry washing machine wherein the hollow toroidal housing of the ball balancing ring is divided into two discrete and complementary annular members that are made of plastic material and are fused together.
The first annular member has a nearly U-shaped cross section with the two opposite lateral walls extending nearly perpendicular to the midplane or equatorial plane of the toroidal housing (i.e. the plane perpendicular to the central axis of the torus and containing the geometric barycentres of all the transversal cross-sections of the torus), whereas the second annular member has a nearly plate-like annular structure and is arranged to close the upper annular opening of the circular groove delimited by the first annular member so as to form/delimit an annular inner cavity having a nearly rectangular cross-section.
More in detail the second annular member extends spaced from and parallel to the midplane of the toroidal housing, is arranged in abutment against the inner and outer annular rims/edges of the first annular member, and is stably welded to the first annular member without interruptions along the same inner and outer annular rims/ edges of the first annular member.
The main drawback of this structure is that, during spin phases, the hollow toroidal housing is subjected to high mechanical stresses that, at high drum rotation speeds, may slightly deform the toroidal housing, with all problems that this entails.
Experimental tests, in fact, revealed that, when drum rotation speed exceeds about 1000 rpm, the ball balancing rings become much more noisy than expected. The noise seems to be caused by the spherical masses not rolling any more on a perfectly cylindrical surface due to the unexpected random deformation of the hollow toroidal housing.
Aim of the present invention is to realize a ball balancing ring capable of operating at high drum rotation speeds without the drawbacks referred above.
In compliance with the above aims, according to the present invention there is provided a laundry washing machine having an outer casing and comprising, inside said outer casing: a washing tub adapted to contain the washing liquid; a rotatable drum which is fitted in axially rotatable manner inside the washing tub and is adapted to contain the laundry to be washed; and at least one balancing ring which is discrete from rotatable drum and is rigidly secured to the rotatable drum for reducing the vibrations of the drum;

said at least one balancing ring comprises: a substantially toroidal, annular housing which is rigidly secured to the drum and is internally provided with a closed annular cavity; and a number of balancing masses accommodated in free movable manner inside said annular cavity;
the annular housing including two discrete and complementary first and second annular hemishells which are concentric to one another and are joined to one another so as to form/delimit the annular cavity of said annular housing;
wherein the second annular hemishell surrounds the first annular hemishell; wherein the cross-section of both said first and said second annular hemishell has a substantially C-shaped, curved polygonal-chain profile ; characterized in that the concavity of the second annular hemishell faces the central axis of the annular housing, whereas the concavity of the first annular hemishell is opposite to/faces away from the same central axis.

Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the axis around which the drum rotates is horizontal, or slightly inclined, with respect to the plane where the machine rests in its working position.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the cross-sections of said first and said second annular hemishells are shaped/dimensioned so as to form/delimit an annular cavity having a substantially polygonal-shaped transversal cross-section with at least five sides.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the cross-section of said first and/or said second annular hemishell has a substantially C-shaped, curved polygonal-chain profile with three or more straight line segments connected and inclined to one another.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the straight line segments of said substantially C-shaped, curved polygonal-chain profile have lengths different to one another.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the annular cavity of said hollow annular housing has a nearly hexagonal cross-section.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that said first and said second annular hemishells are substantially coplanar to one another.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the second annular hemishell is adapted to firmly abut on the drum.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the second annular hemishell is provided with a number of fixing protrusions which are angularly spaced about the central axis of the second annular hemishell and extend outwards in a nearly radial direction so as to stably abut against the drum.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the said first annular hemishell and said second annular hemishell are stably joined/coupled to one another along corresponding first and second mating annular rims/edges.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that said first and second mating annular rims/edges are arranged on opposite sides of a reference plane of the annular housing.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that said reference plane substantially coincides with the midplane of said annular housing.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that said first and said second annular hemishells are made of plastic material and are reciprocally welded along said first and second mating annular rims/edges.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the first annular hemishell has a first wall segment and a second wall segment nearly faced and non-parallel to one another, and a third wall segment connecting the first wall segment to the second wall segment; the first annular rim/edge of the first annular hemishell edging the first wall segment of said first annular hemishell; the second annular rim/edge of the first annular hemishell edging the second wall segment of said first annular hemishell.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the second annular hemishell has a first wall segment and a second wall segment nearly faced and non-parallel to one another, and a third wall segment connecting the first wall segment to the second wall segment; the first annular rim/edge of the second annular hemishell edging the first wall segment of said second annular hemishell; the second annular rim/edge of the second annular hemishell edging the second wall segment of said second annular hemishell.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the balancing ring is rigidly secured directly to the cylindrical wall of the drum.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the balancing ring is located inside the drum.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the balancing ring includes, inside the annular cavity, a dumping liquid that damps out the movement of the balancing masses inside the same annular cavity.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that the balancing masses are spherical in shape.
Preferably, though not necessarily, the laundry washing machine is furthermore characterized in that both said first and second annular hemishells extend astride of the midplane of said annular housing.
A non-limiting layout of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a side view of a laundry washing machine realized in accordance with the teachings of the present invention, sectioned along the midplane of the washing machine and with parts removed for clarity;
Figures 2 is an enlarged view of part of the laundry washing machine shown in Figure 1, with parts removed for clarity;
Figures 3 is a front view of one of the balancing rings of the laundry washing machine shown in Figures 1 and 2;
Figures 4 is an enlarged side view of the balancing ring shown in Figure 3, sectioned along the midplane of the washing machine;
Figure 5 is an enlarged perspective view of a segment of the balancing ring shown in Figures 3 and 4, with parts removed for clarity;
Figure 6 is an exploded view of the toroidal annular housing of the balancing ring shown in the preceding figures, sectioned along the midplane of the washing machine; whereas
Figure 7 is an enlarged view of a portion of the toroidal annular housing shown in Figure 6.

With reference to Figures 1 and 2, reference number 1 denotes as a whole a laundry washing machine 1 preferably suitable for domestic use.
The laundry washing machine 1 basically comprises: a preferably substantially parallelepiped-shaped, self-supporting boxlike outer casing 2 structured for stably resting on the floor; a preferably substantially cylindrical, washing tub 3 which, in use, contains the washing liquid and is arranged inside the casing 2 with its mouth directly facing a laundry loading-unloading opening formed on outer casing 2; a substantially cylindrical, hollow rotatable drum 4 which is structured for accommodating the laundry to be washed, and is fitted in axially rotatable manner inside the washing tub 3 so as to be able to freely rotate about its longitudinal/central axis A inside the washing tub 3; a door 5 which is hinged to the outer casing 2 so as to be manually movable to and from a closing position (see Figure 1) in which the door 5 closes the laundry loading-unloading opening on the boxlike casing 2 for watertight sealing the washing tub 3; and an electrically-powered motor assembly 6 which is structured for driving into rotation the rotatable drum 4 about its longitudinal axis A inside the washing tub 3.
Moreover the laundry washing machine 1 comprises, inside the outer casing 2, a detergent dispenser 7 and a fresh-water supply circuit 8.
The detergent dispenser 7 is preferably located inside the outer casing 2 above the washing tub 3 and preferably, though not necessarily, immediately underneath an upper worktop or top wall of casing 2, and is structured for selectively feeding into the washing tub 3, preferably according to a washing cycle manually-selected by the user, a given amount of detergent, softener and/or other washing agent suitably mixed with water.
The fresh-water supply circuit 8, in turn, is directly connected/connectable to the water mains, and is structured for selectively channelling, preferably according to the washing cycle manually-selected by the user, a flow of water from the water mains to the detergent dispenser 7 and/or directly to the washing tub 3.
In the example shown, in particular, the washing tub 3 is preferably substantially cup-shaped, is preferably arranged substantially horizontally inside the outer casing 2, and is preferably provided with a nearly circular front mouth that directly faces a complementary-shaped, laundry loading-unloading opening formed on a front wall 9 of casing 2.
With reference to Figure 1, the door 5, in turn, is preferably hinged to the front wall 9 so as to be manually movable, preferably about a nearly vertically-oriented rotation axis, to and from a closing position in which the door 5 closes the laundry loading-unloading opening on front wall 9 for watertight sealing the washing tub 3.
Furthermore, the washing tub 3 is preferably suspended in floating manner inside the boxlike casing 2 via a suspension system that preferably comprises at least one, and preferably a couple of coil springs 10 connecting the upper portion of washing tub 3 to the top of casing 2, and preferably at least one and more conveniently a couple of vibration dampers 11 connecting the bottom portion of washing tub 3 to the bottom of casing 2.
Preferably the laundry washing machine 1 moreover comprises an elastically-deformable tubular bellows 12 that watertight connects the front mouth of washing tub 3 to the laundry loading-unloading opening formed on the front wall 9 of boxlike casing 2.
The rotatable drum 4, on the other hand, is preferably substantially cup-shaped and is fitted in axially rotatable manner inside the washing tub 3 with its concavity facing the front mouth of washing tub 3. Preferably the rotatable drum 4 is furthermore arranged inside washing tub 3 with the drum rotation axis A locally substantially coaxial to the longitudinal axis of washing tub 3, and with its nearly circular front mouth directly aligned and faced to the front mouth of washing tub 3, so as to receive the laundry to be washed through the laundry loading-unloading opening present on front wall 9. In other words, the drum rotation axis A is preferably substantially horizontal.
With reference to Figures 1, 2 and 3, laundry washing machine 1 additionally comprises at least one balancing ring 13 which is discrete from rotatable drum 4, is rigidly secured to the rotatable drum 4 substantially coaxial to the drum rotation axis A, and is adapted to minimize/reduce the vibrations produced by drum 4 when rotating at high speed about the rotation axis A while accommodating an unbalance load of laundry.
More in detail, the/each balancing ring 13 is substantially circular in shaped, and is preferably accommodated inside of drum 4 coaxial to drum rotation axis A. Preferably the/each balancing ring 13 is furthermore rigidly secured directly to the cylindrical wall 14 of drum 4.
In the example shown, in particular, laundry washing machine 1 is preferably provided with two balancing rings 13 which are rigidly secured to the body of rotatable drum 4, preferably inside the drum 4 and preferably adjacent to the front and rear rims of the cylindrical wall 14 of drum 4.
With reference to Figures 2-7, the/each balancing ring 13 basically comprises: a substantially toroidal, rigid annular housing 15 which is adapted to be rigidly secured to the body of drum 4, or rather to the cylindrical wall 14 of drum 4, so that its central axis B substantially coincides with the drum rotation axis A, and has a tubular structure so as to delimit, inside itself, a closed annular cavity 16 which is circular in shape, is coaxial to central axis B and preferably has a substantially uniform cross-section; a number of heavy balancing masses 17 which are accommodated in free movable manner inside the inner cavity 16 of annular housing 15; and a dumping liquid (not shown in the figures) that fills up, preferably completely, the inner cavity 16 of annular housing 15 for damping out the movement of the balancing masses 17 inside the inner cavity 16.
More in detail, the balancing masses 17 are preferably spherical in shape so as to roll on the inner surface of the hollow annular housing 15, and are preferably made of metal material. Preferably, the balancing masses 17 are moreover dimensioned so as to take up more than 50% of the cross-section of the annular inner cavity 16.
The dumbing liquid, in turn, is preferably a silicon-based liquid and/or preferably has a viscosity higher than 200 cSt.
It is to be understood that, in toroidal geometry, a transversal cross-section of the torus is a section of the torus according to a cutting plane which extends radially from the central axis of the torus and is, at same time, perpendicular to any plane perpendicular to the central axis of the torus, whereas the midplane or equatorial plane of the torus is the plane perpendicular to the central axis of the torus and containing the geometric barycentres of all the transversal cross-sections of the torus.
With reference to Figures 2-7, the annular housing 15, on the other hand, is divided into, or at least includes two discrete and complementary annular hemishells 18 and 19 that are preferably substantially coplanar and concentric to one another, and are watertight joined/coupled to one another so as to form/delimit the annular inner cavity 16.
More specifically, both annular hemishells 18 and 19 preferably extend astride of a reference plane M of annular housing 15, which is locally perpendicular to the central axis B and preferably also substantially coincides with the midplane of the annular housing 15, i.e. the plane perpendicular to central axis B and containing the geometric barycentres of almost all the transversal cross-sections of annular housing 15.
In other words, both annular hemishells 18 and 19 preferably extend astride of the midplane of annular housing 15. Moreover the annular hemishell 19 preferably surrounds the annular hemishell 18.
In addition to the above, with reference to Figures 2, 4, 5, 6 and 7, the transversal cross-section of both annular hemishells 18 and 19 has a substantially C-shaped, curved polygonal-chain profile, so as to form/delimit an annular inner cavity 16 having a substantially polygonal-shaped cross-section. Preferably the concavity of one of said two discrete and complementary annular hemishells 18 and 19 furthermore faces the central axis B of annular housing 15.
In other words, the transversal cross-section of both annular hemishells 18 and 19 basically consists of a series of straight line segments connected and inclined to one another so as to resemble a C.
Preferably the concavity of the outer annular hemishell 19 faces the central axis B, whereas the concavity of the inner annular hemishell 18 is opposite to/faces away from the central axis B.
Preferably the straight line segments of said substantially C-shaped, curved polygonal-chain profile have lengths different to one another. The cross-section of the inner cavity 16 therefore has the shape of an irregular polygon.
Moreover, the cross-sections of the annular hemishells 18 and 19 are preferably shaped/dimensioned so as to form/delimit together an annular inner cavity 16 having a substantially polygonal-shaped cross-section with at least five sides.
In the example shown, in particular, the curved polygonal-chain profile of the transversal cross-section of annular hemishell 18 preferably includes three or more straight line segments connected and inclined to one another.
Similarly the curved polygonal-chain profile of the transversal cross-section of annular hemishell 19 preferably includes three or more straight line segments connected and inclined to one another.
In other words, the substantially C-shaped, curved polygonal-chain profile of the transversal cross-section of annular hemishell 18 and/or 19 includes three or more straight line segments connected and inclined to one another.
Furthermore the inner and outer annular hemishells 18 and 19 are preferably shaped so as to form/delimit in between themselves an annular inner cavity 16 having a nearly hexagonal transversal cross-section.
More specifically in the example shown the transversal cross-section of the inner cavity 16 preferably has roughly the shape of an irregular hexagon.
In addition to the above, with reference to Figures 2, 4, 6 and 7, the annular hemishells 18 and 19 are stably joined/coupled to one another along corresponding mating annular rims/ edges 18a, 19a and 18b, 19b that are preferably located on opposite sides of the reference plane M of annular housing 15.
In other words, the inner annular hemishell 18 has an approximately C-shaped transversal cross-section with the concavity facing the annular hemishell 19, i.e. opposite to central axis B, and the two annular rims/ edges 18a and 18b delimiting the annular groove of hemishell 18 are located on opposite sides of the reference plane M.
The outer annular hemishell 19, in turn, has an approximately C-shaped transversal cross-section with the concavity facing the central axis B and the annular hemishell 18, and the two annular rims/ edges 19a and 19b delimiting the annular groove of hemishell 19 are located on opposite sides of the reference plane M. The outer annular hemishell 19, furthermore, encircles the inner annular hemishell 18 so that its two annular rims/ edges 19a and 19b area aligned and stably coupled/joined each to a respective facing annular rim/ edge 18a, 18b of annular hemishell 18.
Preferably the annular hemishells 18 and 19 are furthermore shaped so that the two annular rims/ edges 18a and 18b of annular hemishell 18 and the two annular rims/ edges 19a and 19b of annular hemishell 19 are located/extend/lie on a same/ common frustoconical surface which is coaxial to the central axis B of annular housing 15 and has an opening angle lower than 150°.
More in detail, the opening angle of said frustoconical surface preferably ranges between 20° and 70°. In other words, the generatrix f of the frustoconical surface makes an angle α with respect to central axis B preferably ranging between 10° and 35°.
In the example shown, in particular, the annular rims/ edges 18a, 18b, 19a and 19b of the annular hemishells 18 and 19 are located/extend/lie on a frustoconical surface whose generatrix f is preferably inclined with respect to central axis B by an angle α roughly equal to 15°.
In other words, the opening angle of the frustoconical surface on which the annular rims/ edges 18a, 18b, 19a and 19b of annular hemishells 18 and 19 lie is preferably equal to roughly 30°.
In addition to the above, the annular hemishells 18 and 19 are preferably made of plastic material and are stably fused/joined to one another preferably via vibration welding.
Therefore, the two annular rims/ edges 18a and 18b of annular hemishell 18 are stably joined/fused to the corresponding mating annular rims/ edges 19a and 19b of annular hemishell 19 preferably by vibration welding.
According to an alternative embodiment, however, the two annular rims/ edges 18a and 18b of annular hemishell 18 may be stably joined to the mating annular rims/ edges 19a and 19b of annular hemishell 19 by gluing.
With reference to Figures 4, 6 and 7, in the example shown, in particular, the inner annular hemishell 18 is preferably provided with a first wall segment 21 and a second wall segment 22 nearly faced and non-parallel to one another, and a third wall segment 23 connecting the first wall segment 21 to the second wall segment 22.
The first annular rim/edge 18a of annular hemishell 18 edges the first wall segment 21 of annular hemishell 18, whereas the second annular rim/edge 18b of annular hemishell 18 edges the second wall segment 22 of annular hemishell 18.
Similarly, the outer annular hemishell 19 is preferably provided with a first wall segment 24 and a second wall segment 25 nearly faced and non-parallel to one another, and a third wall segment 26 connecting the first wall segment 24 to the second wall segment 25.
The first annular rim/edge 19a of annular hemishell 19 edges the first wall segment 24 of annular hemishell 19, whereas the second annular rim/edge 19b of annular hemishell 19 edges the second wall segment 25 of annular hemishell 19.
Moreover, the first wall segment 24 of outer annular hemishell 19 is preferably faced to the second wall segment 22 of inner annular hemishell 18. The second wall segment 25 of outer annular hemishell 19 is preferably faced to the first wall segment 21 of inner annular hemishell 18. The first wall segment 24 of outer annular hemishell 19 is furthermore faced to the second wall segment 22 of inner annular hemishell 18
With reference to Figures 2-7, preferably the outer annular hemishell 19 of annular housing 15 is finally structured to firmly rest/prop on the body of drum 4, or rather against the cylindrical wall 14 of drum 4, coaxial to drum rotation axis A.
More in detail, the outer annular hemishell 19 is preferably provided with a number of fixing protrusions 28 which are angularly spaced about the central axis B and extend outwards in a nearly radial direction so as to stably abut against the body of drum 4, or rather against the cylindrical wall 14 of drum 4
Preferably, these fixing protrusions 28 are additionally coplanar to one another and substantially regularly spaced about the central axis B.
In the example shown, in particular, the fixing protrusions 28 are preferably regularly spaced about the central axis B and extend on a same/common reference laying plane which is substantially parallel to and offset from the reference plane M of annular housing 15 and/or from the midplane of annular housing 15.
With particular reference to Figures 2, 4 and 7, preferably each fixing protrusion 28 is finally adapted to be engaged by a preferably radially-extending, fixing screw 29 that extend in pass-through manner through the body of drum 4, or rather through the cylindrical wall 14 of drum 4.
More in detail, each fixing protrusion 28 is preferably provided with a radially-oriented, bling central hole adapted to be engaged by the threaded stem of the fixing screw.
Operation of laundry washing machine 1 is almost identical to that of any other laundry washing machine and therefore does not require further explanations.
As regards the balancing rings 13, during spin phases, the balancing masses 17 tend to group together and to move inside the annular inner cavity 16 of annular housing 15 so as to balance the unbalanced load, i.e. the laundry, momentarily placed inside the drum 4.
The advantages resulting from the particular structure of balancing ring 13 are large in number.
First of all, the particular shape of the cross-section of annular hemishells 18 and 19 allows to significantly increase the overall stiffness of the annular housing, thus bringing almost close to zero the in-use deformations of annular housing 15, even when drum rotation speed rises far beyond 1000 rpm.
As a consequence, the laundry washing machine 1 is less noisy that today's laundry washing machines with traditional balancing rings.
Moreover in balancing ring 13, each balancing mass 17 has now two spaced points of contact with the surface of annular hemishell 19, thus further reducing the noise of the balancing masses 17 rolling inside the inner annular cavity 16.
Furthermore, the balancing masses 17 roll nearly astride the centreline of the annular hemishell 19 thus minimizing the mechanical stresses to the welding lines/ areas of annular housing 15, i.e. the annular rims/ edges 18a, 18b, 19a and 19b of annular hemishells 18 and 19.
Finally, placing the first 18a, 19a and the second 18b, 19b mating annular rims/ edges of annular hemishells 18 and 19 on opposite sides of the reference plane M of annular housing 15, or rather of the midplane of annular housing 15, allows to greatly simplify the assembly process of the balancing ring 13 with the cost savings that this entails.
Clearly changes and modifications may be made to laundry washing machine 1 and to balancing ring 13 without, however, departing from the scope of the present invention.
For example, in a less sophisticated embodiment the balancing ring 13 may lack the dumbing liquid.
Moreover the balancing ring or rings 13 may be firmly secured to the body of drum 4, outside of drum 4.
Furthermore the front balancing ring 13 may be located/recessed into a specific annular seat formed in the front wall 30 of drum 4, obviously coaxial to drum longitudinal/rotation axis A.
Lastly, the fixing protrusions 28 may be replaced by a single outwards-protruding annular rib or ridge extending all around the annular hemishell 19.

Claims

A laundry washing machine (1) having an outer casing (2) and comprising, inside said outer casing (2): a washing tub (3) adapted to contain the washing liquid; a rotatable drum (4) which is fitted in axially rotatable manner inside the washing tub (3) and is adapted to contain the laundry to be washed; and at least one balancing ring (13) which is discrete from rotatable drum (4) and is rigidly secured to the rotatable drum (4) for reducing the vibrations of the drum (4);
said at least one balancing ring (13) comprises: a toroidal annular housing (15) which is rigidly secured to the drum (4) and is internally provided with a closed annular cavity (16); and a number of balancing masses (17) accommodated in free movable manner inside said annular cavity (16);

the annular housing (15) including two discrete and complementary first (18) and second (19) annular hemishells which are concentric to one another and are joined to one another so as to form/delimit the annular cavity (16) of said annular housing (15);

wherein the second annular hemishell (19) surrounds the first annular hemishell (18); wherein the cross-section of both said first (18) and said second annular hemishell (19) has a C-shaped, curved polygonal-chain profile; and characterized in that the concavity of the second annular hemishell (19) faces a central axis (B) of the annular housing (15), whereas the concavity of the first annular hemishell (18) is opposite to/faces away from the same central axis (B).
Laundry washing machine according to Claim 1, wherein the cross-sections of said first (18) and said second (19) annular hemishells are shaped/dimensioned so as to form/delimit an annular cavity (16) having a polygonal-shaped transversal cross-section with at least five sides.
Laundry washing machine according to Claim 1 or 2, wherein the cross-section of said first (18) and/or said second annular hemishell (19) has a C-shaped, curved polygonal-chain profile with three or more straight line segments connected and inclined to one another.
Laundry washing machine according to Claim 1, 2 or 3, wherein the straight line segments of said C-shaped, curved polygonal-chain profile have lengths different to one another.
Laundry washing machine according to any one of the preceding claims, wherein the annular cavity (16) of said hollow annular housing (15) has an hexagonal cross-section.
Laundry washing machine according to any one of the preceding claims, wherein said first (18) and said second (19) annular hemishells are substantially coplanar to one another.
Laundry washing machine according to any one of the preceding claims, wherein both said first (18) and second (19) annular hemishells extend astride of a midplane of said annular housing (15) that is perpendicular to the central axis (B) of the annular housing (15) and contains the geometric barycentres of almost all the transversal cross-sections of said annular housing (15).
Laundry washing machine according to any one of the preceding claims, wherein said first annular hemishell (18) and said second annular hemishell (19) are stably joined/coupled to one another along corresponding first (18a, 19a) and second (18b, 19b) mating annular rims/edges.
Laundry washing machine according to Claim 8, wherein said first (18a, 19a) and second (18b, 19b) mating annular rims/edges are arranged on opposite sides of a reference plane (M) of the annular housing (15) which is locally perpendicular to the central axis (B) of the annular housing (15).
Laundry washing machine according to Claim 9, wherein said reference plane (M) coincides with a midplane of said annular housing (15) that is perpendicular to the central axis (B) of the annular housing (15) and contains the geometric barycentres of almost all the transversal cross-sections of said annular housing (15).
Laundry washing machine according to Claim 8 or 9, wherein said first (18) and said second (19) annular hemishells are made of plastic material and are reciprocally welded along said first (18a, 19a) and second (18b, 19b) mating annular rims/edges.
Laundry washing machine according to any one of the preceding claims, wherein the first annular hemishell (18) has a first wall segment (21) and a second wall segment (22) faced and non-parallel to one another, and a third wall segment (23) connecting the first wall segment (21) to the second wall segment (22); the first annular rim/edge (18a) of the first annular hemishell (18) edging the first wall segment (21) of said first annular hemishell (18); the second annular rim/edge (18b) of the first annular hemishell (18) edging the second wall segment (22) of said first annular hemishell (18, 19).
Laundry washing machine according to any one of the preceding claims, wherein the second annular hemishell (19) has a first wall segment (24) and a second wall segment (25) faced and non-parallel to one another, and a third wall segment (26) connecting the first wall segment (21) to the second wall segment (22); the first annular rim/edge (19a) of the second annular hemishell (19) edging the first wall segment (24) of said second annular hemishell (19); the second annular rim/edge (19b) of the second annular hemishell (18) edging the second wall segment (22) of said second annular hemishell (18, 19).
Laundry washing machine according to any one of the preceding claims, wherein the balancing ring (13) includes, inside the annular cavity (16), a dumping liquid that damps out the movement of the balancing masses (17) inside the same annular cavity (16).
Laundry washing machine according to any one of the preceding claims, wherein the balancing masses (17) are spherical in shape.