EP3256754A1

EP3256754A1 - Balancing device for a machine with rotatable drum, and machine including a rotatable drum provided with such a device

Info

Publication number: EP3256754A1
Application number: EP16707898.9A
Authority: EP
Inventors: Ali Messaoudi
Original assignee: Amnc Innovations
Current assignee: Amnc Innovations
Priority date: 2015-02-13
Filing date: 2016-02-11
Publication date: 2017-12-20
Also published as: US20180030639A1; JP6737795B2; CN107208743A; CA2976146A1; WO2016128681A1; US10260191B2; CN107208743B; FR3032766B1; FR3032766A1; KR20170117425A; JP2018514710A

Abstract

The invention relates to a balancing device for a machine with a rotatable drum. Said device includes at least one balancing ring (20) intended to be coaxially mounted onto the rotatable drum. Said ring has an inner space (51) divided into a plurality of separate channels (52). Said channels (52) extend around the axis of said balancing ring over the entire circumference thereof. According to the invention, at least some of the channels (52) each have, in at least one direction, a non-zero internal dimension (b) less than or equal to 3 millimeters.

Description

BALANCING DEVICE FOR A ROTARY DRUM MACHINE AND MACHINE COMPRISING A ROTARY DRUM EQUIPPED WITH SUCH A DEVICE

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The present invention relates generally to the field of balancing devices for rotary elements.

It relates more particularly to a balancing device for a rotary drum machine, comprising at least one balancing ring to be mounted coaxially on the rotary drum, which has an interior space divided into a plurality of distinct channels, said channels extending around the axis of said balancing ring over its entire circumference.

The invention is particularly advantageously applied to the balancing of a rotary drum of a washing machine having in particular a laundry spinning function.

BACKGROUND

The rotational movement of a rotating element of a machine, such as a drum of a washing machine, a centrifuge, or a turbine, is likely to generate strong and damaging vibrations if this element does not have a balanced mass distribution with respect to its axis of rotation.

Such vibrations are particularly pronounced for machines whose rotating drum at high speed contains a free mass. This is particularly the case for washing machines in the spinning phase.

In general, at the beginning of a spinning phase, the laundry contained in the drum of a washing machine is located against the internal face of the cylindrical side wall of the drum, on which it is unevenly distributed. . This cloth then represents a mass whose center of gravity is eccentric with respect to the axis of rotation of the drum.

Due to its eccentric positioning, the mass of laundry contained in the rotating drum exerts stresses on the latter which cause the rotation of the drum is accompanied by a substantially circular displacement of its axis. We then observe a drum that turns unbalanced.

This imbalance, combined with high rotation speeds (during spinning phase), generates significant vibrations and noise. In order to mitigate this harmful phenomenon of vibrations, it is known to equip the drum of a washing machine with a balancing device designed to prevent the axial imbalance of said drum rotating at high speed.

Document EP 1 634 986 discloses such a balancing device comprising a balancing ring whose channels which are distinct from one another are partially filled with a balancing liquid.

Under the effect of the substantially circular displacement of the axis of the drum, the balancing liquid of this device is positioned in the channels of the balancing ring diametrically opposite the mass of laundry that contains the drum.

The assembly comprising the drum, the laundry it contains, the balancing ring and the balancing liquid contained therein, is thus balanced with respect to the axis of rotation of the drum, which substantially reduces the vibrations generated by its rotation.

Such a balancing effect can thus be obtained, for a machine for washing the domestic laundry, up to rotational speeds of up to 200 rpm, for example.

For higher speeds of rotation, the centrifugal force exerted on the balancing liquid becomes preponderant compared to the inertial force associated with the substantially circular displacement of the axis of the drum. This movement is then no longer sufficient for the balancing liquid is positioned diametrically opposite to the mass of laundry. Under the effect in particular of the centrifugal force that it undergoes, the balancing liquid contained in each channel is distributed substantially over the entire length of the channel. The imbalance due to the mass of spinning laundry is no longer compensated by the balancing liquid, the rotation movement of the drum is again unbalanced and accompanied by strong vibrations.

Such a balancing device is thus very little effective in reducing the vibrations generated by the rotation of a washing machine drum in the spinning phase, which can reach a rotational speed typically between 400 and 1800 revolutions per minute. minute.

In general, a balancing device such as that described in document EP 1 634 986 is not very effective in balancing a rotary element containing a free mass, subjected to high speeds of rotation, such as example a centrifuge drum or washing machine.

Document WO 2010/0291 12 also discloses a balancing device for a rotating drum, comprising a balancing ring whose channels are partially filled with a balancing substance having thixotropic properties. This substance is essentially solid at rest. It liquefies under the effect of the vibrations of the machine, and is then distributed in the channel which contains it. The document WO 2013/087722 describes such a balancing device, in which the section of the channels is furthermore capable of deforming.

OBJECT OF THE INVENTION

Compared to the prior art, the present invention proposes a new balancing device as defined in the introduction, wherein at least a portion of the channels each have in at least one direction a non-zero internal dimension less than or equal to at 3 millimeters.

Drum means both a rotary hollow cylinder such as a washing machine drum, a rotary full cylinder as a turbine engine shaft.

By internal dimension of a channel, denotes a distance that it presents internally, representative of its extent in said direction, and therefore not zero.

Such an internal dimension more precisely designates a distance representative of the extent of a cross section of this channel.

A straight section of this channel, hereinafter referred to simply as the section of this channel, may have any shape.

An internal dimension of this channel may then correspond for example to the diameter of a circle inscribed internally in this section, or to an average internal width of this section in a given direction. It is recalled that the circle inscribed internally in such a section corresponds to the circle of greatest possible radius contained within this section.

An internal dimension of this channel can thus designate:

the internal diameter of the section of the channel when it is circular,

the small internal diameter of this section when it is elliptical,

the internal width of this section when it is rectangular, in particular square,

- a height of the internal contour of this section when this contour forms a trapezoid or a parallelogram,

a height or a side of the internal contour of this section when this contour forms a triangle, or the diameter of the circle inscribed in this triangle.

Each of the channels of the balancing ring of the balancing device according to the invention is preferably filled with a balancing liquid occupying a volume of between a quarter and three quarters of the internal volume of said channel.

When this balancing ring rotates about its axis, the centrifugal force exerted on the balancing liquid tends to spread it over the entire circumferential length of the corresponding channel, at maximum distance from the axis of the ring. balancing.

The surface tension, which is exerted on the level of the free surface of the counterbalancing liquid, on the contrary, tends, to reduce the area of this free surface, to maintain the equilibrating liquid in the form of a column of liquid occupying only one section of said channel over its entire section. The free surface of this liquid column forms two meniscuses each resting on the internal face of the wall of each corresponding channel, in particular on the part of the inner face of this wall closest to the axis of the ring of 'balancing.

When the speed of rotation of the balancing device according to the invention rises and reaches for example 800 revolutions per minute, each channel of the balancing ring is advantageously sufficiently narrow for the surface tension effect described above. above dominates the effect of the centrifugal force experienced by the counterbalancing liquid, and thus prevents the spreading of the counterbalancing liquid over the entire length of the corresponding channel.

The balancing fluid of the balancing device according to the invention then remains located only part of the length of said balancing ring channels, whereby it can advantageously provide a balancing function of a rotary drum on which is mounted coaxially said balancing ring, including for high rotational speeds, typical for example of a spin phase of a washing machine.

According to an advantageous characteristic of the balancing device according to the invention, said internal dimension of each of said channels is between 0.5 and 2 millimeters.

Such channels are then sufficiently narrow so that the balancing liquid they contain (an aqueous solution) remains localized on a only part of the length of said channels by surface tension effect, as explained above, up to rotational speeds of about 1500 revolutions per minute of a rotary drum about 0.5 m in diameter on which is mounted the balancing ring.

Other nonlimiting and advantageous features of a balancing device according to the invention are the following:

each channel of said portion of said channels has:

- a section of between 2 and 4 square millimeters,

- a section smaller than 2 square millimeters, and

a wall that delimits a closed interior volume.

The invention provides, in a preferred embodiment, that said channels together form a one-piece strip of flexible plastic material, wound to form a flexible ring, two ends of said strip being sealingly joined by an element of junction that ensures the continuity of the interior volume of each channel.

The fact that all the channels form a flexible band in one piece facilitates the handling and assembly of such a balancing ring.

Such a flexible band may advantageously be made by extrusion of a plastic material through a profile.

This arrangement is therefore particularly interesting in terms of production and assembly costs.

The invention also proposes a machine comprising a rotary drum equipped with a balancing device according to the invention.

Preferably, it can be provided according to the invention that the rotary drum of this machine is equipped with another balancing device according to the invention, the two balancing devices being respectively mounted near the two opposite ends of the cylindrical wall. said rotary drum.

Having at least two balancing rings, located at different positions along the axis of the rotary drum, to correct not only the static unbalance, but also the torque unbalance of the drum.

When the machine according to the invention is a washing machine, the distribution of the balancing liquid within the balancing ring of each balancing device makes it possible to adjust the overall position of the center of gravity of the machine. set of equalizing liquid, so that it coincides, along the axis of the drum, with the position of the linen contained in it. The rotating drum is thus balanced at best, according to the distribution of the laundry against the inner face of its cylindrical side wall.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT The following description with reference to the accompanying drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

In the accompanying drawings:

FIG. 1 is a schematic view according to section B-B of a washing machine according to the invention, represented in FIG. 2,

FIG. 2 is a schematic view according to section A-A of the washing machine of FIG. 1,

FIG. 3 is a diagrammatic perspective view of a balancing ring of a first balancing device of the washing machine of FIG. 1,

FIG. 4 is a sectional view along plane C-C of the balancing ring of FIG. 3;

FIG. 5 is a detailed view of the zone V of FIG. 4;

FIG. 6 is a diagrammatic perspective view of a balancing ring of a second balancing device of the washing machine of FIG. 1,

FIG. 7 is a sectional view along plane D-D of the balancing ring of FIG. 6,

FIG. 8 is a detailed view of zone VIII of FIG. 7; FIG. 9 schematically represents a connecting element of the balancing ring of FIG. 3;

FIG. 10 schematically represents a connecting element of the balancing ring of FIG. 6, and

FIG. 11 shows diagrammatically, at a given moment, the rotating drum of the washing machine of FIG. 1 and the balancing ring of FIG. 3 partly filled with a balancing liquid, when the rotating drum rotates at high speed.

The term "washing machine" here means any machine providing a laundry treatment, comprising a rotating laundry drum contained in a tank. This term thus refers in particular washing machines and / or spinning laundry, and washing machines, spin and dry laundry.

A machine 10 to wash the laundry according to the invention, shown schematically in section, and at rest in Figure 1, comprises in particular a body 1 1 and a tank 12, of generally cylindrical general shape, suspended from the body 1 1 by springs 13 and 14.

The tank 12 contains a rotary drum 17, of horizontal axis, for receiving the laundry to be treated. The rotary drum 17 is rotatably mounted in the tank 12 and can thus rotate about its axis A1 with respect to the tank 12.

The tank 12 is intended to receive a liquid for washing laundry contained in the rotating drum 17, rinsing it, or a liquid extracted from the laundry contained in the rotating drum 17 during a spinning phase.

The rotation of the rotary drum 17 generates, particularly when it contains laundry to be treated, an oscillatory movement of the scrubber unit, that is to say of the assembly comprising the tank 12 and the rotary drum 17.

The tank 12 is provided in its lower part with two damping devices 15 and 16, for example hydraulic dampers, connecting the tank 12 to the body 1 1 of the washing machine 10, which contribute to damping the oscillatory movement of the scrubber mentioned above.

As best shown in Figure 2, the rotary drum 17 comprises in particular a cylindrical wall 18, which constitutes its side wall, bounded by a first end 22, here forming a circular edge, and a second end 23, opposite the first end. 22, and also forming here a circular edge. The rotating drum 17 is closed at the bottom by a rear wall 24 extending from the second end 23 of the cylindrical wall 18 to the axis A1 of the drum, and having substantially the shape of a disc.

In a conventional manner, the rotary drum 17 is rotated relative to the tank 12 by means of an electric motor 25, integral with the tank 12 and situated on the side of the rear wall 24 of the rotary drum 17.

The tank 12 comprises, on the side opposite the motor 25, a wall 26 which extends from one end of the substantially cylindrical side wall of the tank 12 in the direction of the axis of the tank. The wall 26 is connected by a seal 27 to a circular port 28 positioned substantially on the axis of the tank. In the closed position, the circular port 28 closes the tank 12 in a sealed manner. In position open, it allows to introduce or remove laundry in the rotary drum 17.

The rotary drum 17 is installed inside the tank 12 by depositing the wall 26, which is removable. Once this installation has been completed, the wall 26 is fastened to the substantially cylindrical side wall of the tank 12 by means of fastening elements 29. An annular seal 30, participating in the sealing of the tank 12, is interposed between the wall 26 and the substantially cylindrical side wall of the tank 12.

The arrangement of the rotary drum 17 and the tank 12 suspended in the body 1 1 of the washing machine 10 not actually forming part of the invention, it will not be described in more detail here.

According to a remarkable characteristic of the machine 10, the rotary drum 17 is equipped with at least one balancing device comprising a balancing ring 20; 21 detailed below.

Here, preferably, the rotary drum 17 is equipped with two balancing devices each comprising a balancing ring 20 and 21.

The balancing ring 20 of the first balancing device is mounted coaxially on the rotary drum 17, near the first end 22 of the cylindrical wall 18. Here, the balancing ring 20 of the first balancing device is engaged externally on the rotary drum 17. It is based on an area of the outer face of the cylindrical wall 18 of the rotary drum which extends from the first end 22 of this wall. The balancing ring 20 of the first balancing device is fixed to the rotary drum 17, for example because it is engaged in force on the latter.

The balancing ring 21 of the second balancing device is mounted, also coaxially, on the rotary drum 17, near the second end 23 of the cylindrical wall 18. Here, the balancing ring of the second device of balancing is mounted on the bottom 24 of the rotary drum 17, externally to the drum. It occupies, at the rear of the drum, a circular corolla which abuts the second end 23 of the cylindrical wall 18. The balancing ring 21 of the second balancing device is fixed to the rotary drum 17, for example by means fasteners such as screws.

In another embodiment, not shown, in which a single balancing device equips the rotary drum, the balancing ring of this balancing device is preferably positioned substantially to equal distance between the first end and the second end of the cylindrical wall of said rotary drum.

As shown in detail in FIGS. 5 and 8, each balancing ring 20; 21 of each of the two balancing devices has an interior space 51; 81 divided into a plurality of distinct channels 52; 82, said channels 52; 82 extending around the axis A2; A3 (see Figures 3, 4, 6 and 7) of said balance ring 20; 21 over its entire circumference, at least a portion of the channels 52; 82 each having in at least one direction an internal dimension b non-zero less than or equal to 3 millimeters.

Each channel 52; 82 of each balancing ring 20; 21 delimits an interior volume, here a closed volume, having a ring shape, symmetrical of revolution about the axis A2; A3 of each balancing ring 20; 21. Here, the cross section of this channel, which corresponds to a section of this channel 52; 82 by a plane containing the axis A2; A3 of the balance ring 20; 21, is square. The cross section of this channel 52; 82 is simply referred to hereinafter as the section of the channel.

The internal volume of each channel may receive a counterbalancing liquid, for example water, or water added with an adjuvant such as salt or a surfactant. This balancing liquid occupies between a quarter and three quarters, here about half, of the internal volume of each channel. This balancing liquid can circulate in each channel all around the axis A2; A3. The manner in which it is distributed in each channel during the operation of the washing machine 10 will be explained later with reference to FIG.

Each channel here has an internal width b equal to about 1 millimeter (see Figures 5 and 8). The value of the internal width b can be adapted according to the speeds of rotation provided for the rotary drum 17 and as a function of the average diameter of the balancing ring 20; 21 correspondent. For a balancing ring 20; 21, the average diameter of which is approximately 0.5 meters, the following values are chosen preferentially:

when the maximum rotation speed provided for the rotary drum 17 is less than 600 revolutions per minute, b = 2 millimeters,

when the maximum rotational speed provided for the rotary drum 17 is less than 900 rpm, b_ = 1.8 mm, when the maximum rotation speed provided for the rotary drum 17 is less than 1200 revolutions per minute, b = 1.5 millimeters,

when the maximum rotation speed provided for the rotary drum 17 is less than 1500 revolutions per minute, b = 1 millimeter, and

- when the maximum rotational speed expected for the rotating drum

17 is less than 1800 rpm, b = 0.7 millimeter.

As a variant, for a balancing ring whose average diameter is approximately 0.5 meters, the value of the internal width b may for example be chosen as follows:

- when the maximum rotational speed for the rotating drum is less than 600 rpm, b = 3 millimeters,

- when the maximum rotational speed for the rotating drum is less than 900 rpm, b = 2.5 millimeters,

- when the maximum rotational speed for the rotating drum is less than 1200 rpm, b_ = 2 millimeters,

when the maximum rotational speed for the rotating drum is less than 1500 rpm, b = 1.8 mm, and

when the maximum rotational speed provided for the rotary drum is less than 1800 revolutions per minute, b = 1.5 millimeters.

In general, the internal width b of the channels 52; 82 is chosen even smaller than the rotational speed of the rotary drum 17 is high.

Moreover, the internal width b of the channels 52; 82 is chosen all the smaller than the average radius of the balancing ring 20; 21 correspondent is tall. For example, when the maximum rotation speed provided for the rotary drum 17 is less than 1200 revolutions per minute, the following values are preferably chosen:

when the average diameter is approximately 0.25 meters, b = 1, 6 millimeters,

when the average diameter is approximately 0.5 meters, b = 1.5 millimeters, and

when the average diameter is about 1 meter, b = 0.8 millimeter.

In a variant, when the maximum rotation speed provided for the rotary drum is less than 1200 revolutions per minute, the value of the internal width b may for example be chosen as follows:

when the average diameter is about 0.25 meters, b = 2.5 millimeters,

when the average diameter is about 0.5 meters, b = 2 millimeters, and when the average diameter is about 1 meter, b = 1.5 millimeter.

In the embodiment described here, the channels 52; 82 of each balancing ring 20; 21 have a square section, as indicated above. In other embodiments, not shown, they may have a section of circular, rectangular, hexagonal or any other shape.

The section of such a channel is then dimensioned preferentially so that the circle inscribed internally in this section has a diameter equal to said internal width b defined above. The section of such a channel may also be dimensioned so as to have an average internal width equal to said internal width b.

In particular, the section of such a channel is preferably dimensioned such that one of its internal dimensions is equal to said internal width b defined above, this internal dimension corresponding in particular:

- in the case of a circular section, to the internal diameter of this section,

- in the case of a rectangular section, to the internal width of that section,

- in the case of an elliptical section, at the small internal diameter of this section,

in the case of a trapezoidal section, at the height of this trapezium, and

- in the case of a section in the form of a parallelogram, at the smallest of the two heights of this parallelogram.

When a channel of the balancing ring has a longer than wide section, for example a rectangular or elliptical section, the direction in which the section of this channel has said internal width b preferably corresponds to a radial direction with respect to the balancing ring. Thus, when the section of this channel is for example rectangular, this section is preferably narrow in a radial direction with respect to the balancing ring, while it may possibly be more elongated in the direction of the axis of this channel. ring.

Such channels can also be sized to have a section s less than 2 square millimeters.

The value of this section s can be adapted as follows, depending on the rotation speeds provided for the rotary drum and as a function of the average diameter of the corresponding balancing ring.

For a balancing ring whose average diameter is approximately 0.5 meters, the following values are chosen preferentially:

- when the maximum rotational speed for the rotating drum is less than 600 rpm, s = 4 square millimeters,

- when the maximum rotational speed for the rotating drum is less than 900 rpm, s = 3.3 square millimeters,

- when the maximum rotational speed expected for the rotating drum is less than 1200 rpm, s = 2.25 square millimeters,

when the maximum rotational speed expected for the rotary drum is less than 1500 rpm, s = 1 square millimeter, and

when the maximum rotational speed for the rotating drum is less than 1800 rpm, s = 0.5 square millimeter.

Alternatively, for a balancing ring whose average diameter is about 0.5 meters, the value of the section s can for example be chosen as follows:

- when the maximum rotational speed for the rotating drum is less than 600 rpm, s = 9 square millimeters,

- when the maximum rotational speed for the rotating drum is less than 900 rpm, s = 6 square millimeters,

- when the maximum rotational speed for the rotating drum is less than 1200 rpm, s = 4 square millimeters,

when the maximum rotational speed expected for the rotating drum is less than 1500 rpm, s = 3 square millimeters, and

when the maximum rotational speed expected for the rotating drum is less than 1800 rpm, s = 2 square millimeters.

In general, the section s of the channels is chosen smaller as the speed of rotation of the rotary drum is high.

Moreover, the section s of the channels is chosen smaller as the average radius of the corresponding balancing ring is large. For example, when the maximum rotational speed expected for the rotating drum is less than 1200 rpm, the following values are preferably chosen:

- when the average diameter is approximately 0.25 meters, s = 2.5 square millimeters,

when the average diameter is about 0.5 meters, s = 2.25 millimeters squared, and

and when the average diameter is about 1 meter, s = 0.7 millimeter squared.

Alternatively, when the maximum rotational speed provided for the rotating drum is less than 1200 rpm, the value of the section s may for example be chosen as follows:

when the average diameter is about 0.25 meters, s = 6 square millimeters,

when the average diameter is about 0.5 meters, s = 4 square millimeters, and

and when the average diameter is about 1 meter, s = 2 square millimeters.

According to another embodiment of the balancing device according to the invention, adapted to rotational speeds lower than 1200 rpm, the balancing ring of this device may comprise channels each having a section between 2 and 4 square millimeters.

According to yet another embodiment not shown of the balancing device according to the invention, the balancing ring of this device may comprise channels having sections of different values. For example, a portion of the channels of said balancing ring may each have a section equal to 3 square millimeters, and another portion of the channels of the same balancing ring may each have a section equal to or less than 2 square millimeters.

According to a preferred embodiment, the set of channels 52; 82 of each balancing ring 20; 21 is in the form of a flexible band wound end to end to form a flexible ring 53; 83 provided with said channels 52; 82 (see Figures 5 and 8). For each of said flexible strips, two of its ends are sealingly joined by a connecting member 90; 100 (see figure 9 and 10), after having introduced the balancing liquid which, as previously explained, partially fills the interior volume of each of said channels 52; 82.

Each junction element 90; 100 comprises a plurality of conduits 91; 101 disposed adjacent to each other. These conduits 91; 101 are for example secured to each other by a wall 92; 102. They are arranged within each junction element 90; 100 in a manner comparable to the way the channels 52; 82 are arranged within the corresponding flexible band. For each joining element 90; 100, a conduit 91; 101 thus takes place in front of each of the channels 52; 82 of the corresponding flexible band, during the establishment of the junction element 90; 100.

Each of these conduits 91; 101 presents:

a small length relative to the length of one of the channels 52; 82 of the balancing ring 20; 21 corresponding (for example equal to about 1/100 ^th of the length of such a channel), and

an external section complementary to the (internal) section of said channels 52; 82 (thus here a square section having externally a side of width b).

A first end 93; 103 of each of said conduits 91; 101 of each junction element 90; 100 is engaged, here engaged in force, through a first end of the channel 52; 82 of said corresponding flexible band. The second end 94; 104 of this conduit is also engaged, here engaged in force, in the second end of the same channel 52; 82, thus ensuring its tightness and the continuity of its interior volume. It can further be provided that the first and second ends of this channel 52; 82 are each glued or welded to the corresponding end 93, 94; 103, 104 of said duct 91; 101 to improve the tightness and durability of the junction thus produced.

Each junction element 90; 100 is preferably produced by molding a partially rigid plastic material, for example acrylonitrile butadiene styrene.

The flexible band, whose two ends are joined by this junction element 90; 100, is made here in one piece, by extrusion of a plastic material through a profile.

Alternatively, to be more easily wound end to end, said band flexible can be made in the form of several separate ribbons of plastic each provided with a portion of the channels, these ribbons being superimposed on each other to form this flexible band. Such a ribbon may for example be obtained by cutting a honeycombed polypropylene plate having channels of appropriate size.

In the context of this variant, the aforementioned junction element preferably comprises several separate junction pieces, each of these junction pieces being formed of a part of the ducts of the connecting element, secured to each other.

Each ribbon is then wound end to end and its two ends are joined in a sealed manner by one of these connecting pieces. These tapes, which can thus be handled independently of each other, are then superimposed on each other concentrically to form the flexible ring of the balancing device.

Each balancing ring 20; 21 of each balancing device here comprises a flexible ring 53; 83 provided with said channels 52; 82 and a crankcase

54; 84 closed by a cover 55; 85 (see Figures 5 and 8).

Each housing 54; 84 is an annular profile whose axis corresponds to the axis A2; A3 of the balance ring 20; 21 corresponding, and having a substantially U-shaped section, the base of this U being oriented radially relative to the axis A2; A3 of said balance ring 20; 21.

Each lid 55; 85 is a substantially flat annular profile of the same axis, the same average radius and the same radial width as the housing 54;

84 corresponding.

Each flexible ring 53; 83 of each balancing ring 20; 21 is inserted into the circular groove defined by the casing 54; 84 corresponding, said groove being then sealingly closed by the cover 55; 85 corresponding.

Each lid 55; 85 is fixed to the housing 54; 84 corresponding, for example by means of a weld or an adhesive, or because it is engaged in force in the circular groove defined by this housing 54; 84.

It will be recalled that the balancing ring 20 of the first balancing device is mounted here around the cylindrical wall 18 of the rotary drum 17. In the spinning phase, the liquid extracted from the laundry to be treated is removed from the drum. rotary 17 by holes provided for this purpose in this cylindrical wall 18.

Also, so as not to hinder the evacuation of this liquid, the housing 54 of the balancing ring 20 of the first balancing device has, on the side of the axis A2 of this ring, a frustoconical face 56, slightly inclined relative to the cylindrical wall 18 of the rotary drum 17, so that a space is provided between the two, through which can drain said liquid in the spin phase. This frustoconical face 56 is provided with ribs 57 (also visible in FIGS. 1 and 3) by means of which the casing 53 rests on the outside face of the cylindrical wall 18 of the rotary drum 17.

The material constituting each housing 54; 84 and each cover 55;

85 corresponding is chosen not to deteriorate under the effect of temperatures or in contact with liquids used for the treatment of laundry. This material may for example be a partially rigid plastic such as acrylonitrile butadiene styrene. Similarly, the plastic material constituting each flexible ring 53; 83, for example polypropylene, and the plastic forming each junction element 90; 100 corresponding, are chosen to withstand the temperatures used for the treatment of laundry (especially to have a good longevity when subjected to a temperature of 90 ° C).

Referring to Figure 1 1, we will now describe the operation of the washing machine 10 which comprises a rotating drum 17 on which is mounted coaxially the balancing ring 20; 21 of a balancing device according to the invention as described in detail above, containing a balancing liquid 1 1 1, and which rotates at high speed.

The rotary drum 17 on which is mounted the balancing ring 20; 21 contains a package of linen to be treated 1 16 pressed against the inner face of its side wall 18 and representing a mass whose center of gravity is eccentric with respect to the axis of rotation A1 of the drum.

Because of its eccentric positioning, the mass of linen 1 16 contained in the rotary drum 17 exerts stresses on the latter which cause the rotation of the drum is accompanied by a substantially circular displacement of its axis A1, as this has been mentioned above. In Figure 1 1, for example, the axis A1 of the drum is located at a position O 'different from the position O it occupies at rest; the distance OO 'shown in Figure 1 1 is a schematic distance simply to illustrate the purpose. In Figure 1 1 can be seen in particular one of the channels 52; 82 of the balancing ring 20; 21 and the balancing liquid 1 1 1 it contains.

Under the effect of the displacement of the axis A1 of the rotary drum 17, the balancing liquid January 1 contained in the channel 52; 82, and located on only a part of the length of this channel by surface tension effect, is positioned in the channel 52; 82 diametrically opposite the mass of laundry 1 16, relative to the axis A1 of the drum.

More particularly, the centrifugal force exerted on the balancing liquid 1 1 1 due to the rotation of the rotary drum 17 which is fixed the balancing ring 20; 21, tends to spread the balancing liquid 1 1 1 over the entire circumferential length of the channel 52; 82, at maximum distance from the axis A2; A3 of the balance ring 20; 21, against the part 1 14 of the inner face of the wall of the channel 52; 82 furthest from axis A2; A3 of the balance ring 20;

21, which is recalled that it coincides with the axis A1 of the rotary drum 17.

On the contrary, the surface tension exerted on the free surface 1 17 of the balancing liquid 1 1 1, tends, to reduce the area of this free surface 1 17, to maintain the balancing liquid 1 1 1 in the form of a column of liquid occupying only a section of the channel 52; 82 on all its section, delimited by two meniscuses 1 12 and 1 13, each meniscus 1 12; 1 13 resting on the inner face of the wall of the channel 52; 82, in particular on the part 1 15 of the inner face of the wall of the channel 52; 82 closest to the A2 axis; A3 of the balancing ring.

The internal width b of the channel 52; 82, chosen in accordance with the indications given above, is advantageously small enough for the surface tension effect described above to dominate the effect of the centrifugal force experienced by the balancing fluid 1 1 1, and thus prevent the spreading of the balancing liquid 1 1 1 along the entire length of the channel 52; 82.

Also, in this position, the mass of the balancing liquid January 1 counterbalances the mass of laundry January 16, and effectively reduces the imbalance of the whole.

The greater the mass of linen 1 16 to be balanced, and the greater the displacement OO 'of the axis A1 that it induces is large. The driving force exerted on the balancing liquid January 1 is also greater than the displacement OO 'of the axis A1 is large. Consequently, the amount of the balancing liquid January 1 which is ultimately maintained in opposition to the mass of linen January 16 is even greater than this mass of linen January 16 to balance is large. The mass of the balancing liquid 1 1 1 effectively having a balancing function and best suits, continuously, the mass of linen 1 16 to balance.

This property is particularly advantageous in the case of a washing machine 10, for example, because:

the mass of linen initially introduced into the drum may vary from one use to another of the washing machine 10,

the mass to be balanced changes strongly furthermore between the beginning and the end of a spinning phase: at the beginning of a spinning phase, this mass of linen to be balanced is important because it is still largely soaked with liquid, whereas at the end of a spinning phase, the mass of laundry to be balanced is lower, since a significant portion of the liquid initially soaking this laundry has already been evacuated.

The use of a balancing device as described above thus makes it possible finally to balance particularly effectively a rotary drum 17 of a machine 10, rotating at high speed and containing a free mass, for example a mass of laundry , said mass being able to vary during the operation of the machine 10.

In the case where the machine 10 is a washing machine, this advantageous effect of adjusting the weight of the balancing liquid actually having a balancing function, to the mass to be balanced, for example here a mass of laundry varying during a spin phase, can be reinforced by the use of a balancing ring comprising channels having sections of different values.

A portion of the channels of said balancing ring may for example each have a section equal to 3 square millimeters, and another part of the channels of the same balancing ring may each have a section equal to or less than 2 square millimeters, as has been mentioned above.

In such an embodiment, all the channels of the corresponding balancing ring participate in the balancing of the rotating drum and the free mass that it contains as the rotational speed of the drum is not too much. high; here for example, as long as it is less than about 900 rpm. For high speeds of rotation, here for example for rotation greater than 900 rpm, only the narrowest channels participate in the balancing of the rotating drum, the surface tension effect described above is not necessarily sufficient to maintain the balancing fluid contained in the channels the widest on only part of their length.

At the beginning of a spinning phase, the rotational speeds are moderate, and the free mass to be balanced. Advantageously, in such an embodiment, the mass of the balancing liquid actually having a balancing function is then important (because of the moderate rotational speed of the rotating drum), the balancing liquid contained in each of the channels. said ring then contributing to this balancing.

However, at the end of a spin phase, the rotation speeds are high, and the free mass to be balanced lower. Advantageously, the mass of the balancing liquid actually having a balancing function is then lower (because of the high speed of rotation of the rotary drum, as explained above).

Furthermore, the mounting of a balancing device outside the rotary drum 17 allows:

to preserve the entire internal volume of the drum for an object or a substance to be treated, for example here linen, and

- Increase the performance of this balancing device due to a larger radius of its balancing ring 20; 21 (relative to an installation of said balancing device inside the rotary drum 17), which gives a greater lever arm to the mass of the balancing liquid contained said ring 20; 21.

Finally, having two balancing devices located at different positions along the axis A1 of the rotary drum 17 of the machine 10, as shown in FIG. 2, makes it possible to correct not only the static unbalance, but also the unbalance of the machine. torque of this drum, which ensures an optimal reduction of the vibrations that would otherwise generate the rotation of the drum.

Positioning each of these two balancing devices at one end of the rotary drum 17 also makes it possible to correct the static imbalance and the torque unbalance of this drum with optimum efficiency. This arrangement ensures that the mass of laundry to be balanced is positioned, the along the axis A1 of the rotary drum, between the two masses of balancing liquid each contained in the ring 20; 21 corresponding to one of the two balancing devices. This configuration is particularly mechanically stable and advantageously reduces the weight of the balancing liquid 1 1 1 necessary to balance a given free mass.

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant within his mind.

In particular, it may be provided that a balancing device as described above advantageously equips a washing machine with vertical axis.

Such a balancing device can also advantageously equip the drum with a centrifuge, with appropriate adaptation, according to the indications given above, internal dimensions of the channels of its balancing ring rotation speeds used in this centrifuge.

More generally, a balancing device as described above is well suited to balance a rotary drum rotating at high speed and intended to receive a free mass, or a mass whose value and positioning in the rotary drum are not determined.

Such a balancing device can also advantageously equip a rotary drum (for example a motor shaft) of a turbine rotating at a high speed, again by means of a suitable adaptation, according to the indications given above, of the internal dimensions of the channels of its ring. balancing at the rotational speeds used in this turbine. For such a rotating drum (for example a motor shaft) of a turbine, an imbalance with respect to its axis of rotation may appear during the life cycle of the turbine, for example following wear of the rotating parts that it comprises. Such an imbalance is then corrected by means of this balancing device, without the need for an expensive maintenance operation of this turbine.

Claims

1. Balancing device for a rotary drum machine (17), comprising at least one balancing ring (20; 21) to be mounted coaxially on the rotating drum (17), which has an internal space (51; 81 ) divided into a plurality of distinct channels (52; 82), said channels (52; 82) extending about the axis (A2; A3) of said balancing ring (20; 21) over its entire circumference, characterized in that at least a portion of the channels (52; 82) each have in at least one direction a non-zero internal dimension (b) of less than or equal to 3 millimeters.

2. balancing device according to claim 1, wherein said internal dimension (b) is between 0.5 and 2 millimeters.

3. Balancing device according to one of claims 1 and 2, wherein each channel (52; 82) of said portion of said channels (52; 82) has a section between 2 and 4 square millimeters.

4. Balancing device according to one of claims 1 and 2, wherein each channel (52; 82) of said portion of said channels (52; 82) has a section less than 2 square millimeters.

5. Balancing device according to one of claims 1 to 4, wherein each channel (52; 82) of said portion of said channels (52; 82) has a wall which delimits a closed interior volume.

6. Balancing device according to one of claims 1 to 5, wherein each channel (52; 82) of said portion of said channels (52; 82) is filled with a balancing liquid (1 1 1) occupying a volume of between one quarter and three quarters of the internal volume of said channel (52; 82).

7. Balancing device according to one of claims 1 to 6, wherein said channels (52; 82) together form a flexible plastic strip, wound to form a flexible ring (53; 83), two ends of said flexible strip being sealingly joined by a connecting member (90; 100) which provides continuity of the interior volume of each channel (52; 82).

8. Machine (10) comprising a rotary drum (17) equipped with a balancing device according to one of claims 6 and 7.

9. Machine (10) according to claim 8, wherein the rotary drum (17) is equipped with another balancing device according to one of claims 6 and 7, the two balancing devices being respectively mounted near the two opposite ends (22, 23) of the cylindrical wall (18) of said rotary drum (17).

10. Machine (10) according to one of claims 8 and 9 constituting a washing machine.