ITPN940005A1 - WASHING MACHINE WITH PERFECT DYNAMIC BALANCING DEVICE - Google Patents

Abstract

Laundry washing machine equipped with an external cabinet, a washing tub, a perforated drum of cylindrical shape and contained in said tub and adapted to rotate inside said drum being equipped with a plurality of annular hollow bodies closed and solidly arranged in correspondence of the lateral walls of said cylindrical basket, and of a plurality of movable masses sliding freely within said hollow bodies, where said annular hollow bodies are formed and prominent lobes and regularly arranged on the perimeter of said hollow bodies. At least one of the lateral walls of said basket it is adjacent to a plurality of said hollow bodies, which are centered coaxially with the axis of the basket and have different rays so as not to interfere with each other.

Description

Description of the Patent for Industrial Invention entitled: "WASHING MACHINE WITH PERFECTED DYNAMIC BALANCING DEVICE"

The invention relates to a particularly domestic washing machine equipped with an improved device for dynamic balancing of the drum.

Even if the present invention refers especially to a front loading washing machine, and for greater convenience of example this description refers to this type of machine, it can advantageously also be applied to other types of washing machines, such as e.g. top loading washing machines or machines equipped with a basket rotating around a vertical axis.

It is known that in particularly domestic washing machines one of the major problems faced by designers concerns the balancing of the drum containing the laundry load during the spinning phases for the rapid extraction of the rinsing water; this problem is particularly felt when the load is unbalanced, which causes an undesirable and sometimes unacceptable oscillation of the basket, which affects the tub and from this to the entire cabinet.

The problem is well known and therefore will not be described further. Among the various solutions to overcome this problem, some have proposed a dynamic solution, which consists in opposing the centrifugal force of the unbalanced load an imbalance of equal magnitude 'but of opposite vector. Such solutions are described e.g. in the French patents n. 1.213.067, Swiss priority 11.8.1957, and in the Italian patent no. 1108367, Japanese priority 12.1.1978.-These documents describe dynamic balancing devices to be applied to washing machine baskets, especially for domestic use, consisting of annular hollow bodies attached to the basket and containing balancing masses that slide inside said hollow bodies, called masses arranging themselves in a position such as to oppose the unbalancing motion of the drum caused by the unbalanced load. This solution, although valid, has nevertheless not found a practical solution due to some reasons, including in particular the following:

a) with originally fairly well balanced loads, the balancing masses are distributed along the development of the annular hollow bodies in substantially indifferent but opposite positions to each other, to maintain the balance of the entire complex; precisely because this position is substantially indifferent, it has been observed that due to irregularities in the movement, the tolerances in the assembly of the ring with the masses and the deformation of this, the vibrations that occur due to the even small imbalance cause a immediate balancing reaction of the masses that begin to rotate until a new position of equilibrium is found.

During this search for balance, said masses also violently collide with each other, causing a consequent significant noise '.

Once the new equilibrium is found, this is not maintained for a long time, since a new small load imbalance restarts the imbalance / rebalancing cycle just described.

An unstable situation therefore arises in which the machine automatically unbalances and re-balances itself, and so on continuously.

This leads to an extremely annoying situation because 'on the one hand the vibrations are definitely not suppressed at all, and on the other hand the machine periodically emits a significant noise'.

b) It is necessary to modify the baskets to strengthen them and make them suitable for housing said hollow bodies, which press against the walls of the basket with a considerable centrifugal force due to the weight of said balancing masses, c) The annular hollow bodies used up to now are made of fairly light material and therefore deformable to a certain extent under the centrifugal force exerted by the balancing masses; this deformation in the hollow bodies has the consequence that the balancing masses do not arrange themselves in the optimal position to balance the unbalance of the load, with the final result that this balancing effect is imperfect and partial.

It would therefore be desirable, and it is the purpose of the present patent, to improve the construction of said baskets, equipping them with devices that force the masses into precise positions when there is an imbalance lower than a predetermined limit, and which instead allow the masses to position oneself freely with a higher imbalance. These devices are made with the characteristics defined in the attached claims, which eliminate the drawbacks described without the need for major constructive modifications and interventions on the machines themselves.

The invention will be better understood from the following description by way of non-limiting example only and with reference to the attached drawings, in which:

fig. 1 schematically shows the cross section of an annular hollow body according to the invention,

Figures 2a and 2b show two distinct shapes of perimeter of the hollow bodies according to the invention.

- fig. 3 shows the operating conditions of a variant of the invention,

- fig. 4 shows a particular operating condition, - fig. 5 shows an improvement of the invention,

- figs. 6, 7 and 7a show different application possibilities of a plurality of hollow bodies according to the invention,

- fig. 8 shows a variant of the shape of the movable bodies - fig. 9 shows an improvement of the shape of the lobed hollow bodies according to the invention,

- Figures 10 and 10a show a particular case in the shape and arrangement of the hollow bodies.

- fig. 11 shows an improved constructive solution alternative to the solution of fig. 10.

Since the problem consists in finding a means to prevent the movement of the balancing masses. In the presence of limited unbalancing of the basket, various configurations of the hollow bodies containing mobile balancing masses have been realized and tested; it has resulted that the described problems of instability 'and noise' are effectively eliminated if said hollow bodies are shaped with the following constraints:

1) Each hollow body must have a closed and convex development 1n each of its sections, so that the segment that joins any two points placed on the perimeter of the hollow body is entirely contained in the surface delimited by this perimeter;

2) Each hollow body must have a plurality of "lobes", ie 1 of perimeter portions regularly distributed along it, which are arranged outside the circle inscribed in said perimeter.

Finally, it is highly preferable for constructive reasons and symmetry of operation, even if not strictly necessary, that these lobes are regularly distributed on a single circumference having the center coinciding with the center of gravity of the relative hollow body, even if of course the perimeter of the hollow body does not coincide with this circumference, and that the center of gravity of the hollow body is on the rotation and symmetry axis of the basket.

Fig. 1 represents a preferred embodiment of this hollow body, which has three lobes placed at regular intervals along the perimeter.

Observing Figure 1, it should be noted that the perimeter p of the hollow body associated with the basket (not drawn) and with the center placed on its rotation axis shows the three lobes 1 arranged at regular intervals on the circumference 2 with center 0.

The perimeter of the hollow body is formed by three curved sections 3, which in the figure are represented as three arcs of respective three circles having a radius R greater than the radius r of the circumference 2.

The positioning of these circumferences and the total regularity of their distribution and positioning is clearly visible in Figure 1 itself.

Observe that the bisector g that cuts the angle given by two rays r between the center 0 and two lobes intersects the perimeter of the hollow body at point 4 and subsequently the circumference 2 at point 5.

Called f the distance between the center and said point 4, the distance (r-f) between point 4 and point 5 represents the d1sl1-fleece that should overcome a mobile mass that is positioned on a lobe to reach said point 5 , counteracting the centrifugal force for the rotation of the basket. To reach intermediate points 6 located on said perimeter, the mass must exceed a lower level (r-f), however always positive.

These differences in height are both geometric definitions but above all real physical situations because if the basket, and with it the hollow body, are made to rotate at a certain rotation speed, the centrifugal force acting on the mobile masses forces them to position themselves in correspondence with the lobes and not the intermediate points of the hollow body between a lobe and the adjacent lobe, precisely because of the difference in height that they should overcome by overcoming the centrifugal force.

Therefore in a situation in which the basket is little or no unbalanced, it substantially rotates around its center 0, and the mobile masses are positioned stably in correspondence with the lobes, from which they do not move in the absence of stresses that push them to overcome the centrifugal force due to the rotation of the basket only.

With ref. to fig. 10, one can observe a perimeter of a hollow body according to the invention, 1n which the three lobes 1 are connected by the three circular arcs A, B and C, which are centered respectively in the points OA, 0B and OC.

For the sake of simplicity, assume that said three arcs are identical, it follows that the respective radii and angles of curvature are also the same.

Now trace the rays a and a 'between the center OA and the two extremes of the corresponding arc A, and similarly the rays b and b' and finally the rays c and c '.

Said six rays will cut each other, and the points of intersection Together with the aforementioned centers OA, OB and OC define the vertices of a hexagon H which in the drawing is indicated in dashed manner.

Each internal point in this hexagon is less than the radii of equal length a, a ', b, b' c and c 'from a generic point P placed inside d1. for any position d1 said generic point P excluding the extreme points of the three lobes 1.

Therefore, if the center of rotation C of the corresponding hollow body is located within this hexagon, the mobile masses contained in said hollow body will be pushed by the centrifugal force to position themselves in the points furthest from the center of rotation and therefore to position themselves in the cusp points 1. In general this will not determine an imbalance that opposes the imbalance of the center of rotation C with respect to the center of gravity 0 but in this hypothesis in which the center of rotation C is relatively close to the center of gravity 0 also means that the imbalance is limited, and therefore a particular balancing force is not required.

If, on the other hand, the imbalance is high enough, such as to make the basket and relative hollow body rotate around a center of rotation C1 external to this hexagon, then points P 'are determined on the perimeter formed by the three circular arcs located at a distance d from said center of rotation C1 greater than said radii; in these conditions the mobile masses will naturally move towards these points P ', up to the condition of re-balancing the drum imbalance since' the new center of rotation will reposition itself 'within the aforementioned hexagon H.

In substance, a situation very similar to that described in the aforementioned priority patents occurs, whereby known solutions are applied which are not compromised by the particular conformation of the hollow bodies described above.

At this point it will be clear to the expert in the field that, by appropriately adjusting the shape of the hollow body, the number of lobes, their shape (cusp or without edges), the type of mobile mass (better explained below) it can also experimentally determine a combination of factors whereby the moving masses are distributed in correspondence with the lobes, providing the desired balancing characteristics also as a function of the rotation speed. This invention admits a numerous series of improvements: the first improvement, which is above all an optimization, concerns the possibility of making hollow bodies equipped with a more or less high number of lobes, whose tracts between continuous lobes are more or less less curved or tense. This allows a wide range of choices that optimize on the one hand the minimum intervention speed of the moving masses and on the other hand the balancing capacity of the unbalanced basket, (flg. 2a, 2b. naturally strive for the best compromise according to the priority scale of the defined objectives, and therefore the circumstance that the less the arches between said lobes are curved, the more the perimeter of the hollow body will resemble a circumference and therefore will have an unstable behavior as described above; however this configuration will be the best from the point of view of the balancing properties, since the difference in height that said masses will have to overcome in order to position themselves will be lower at the same rotation speed. in the optimal balancing position and therefore more ready will be the balancing reaction and this will become effective at a lower speed.

In the opposite case, that is, of lobes connected by very curved sections, the opposite effects will be obtained to those just described and which, for the sake of brevity, cannot be explained because they can be immediately understood by the expert in the sector.

A second improvement consists in the fact of introducing a considerable plurality of mobile masses, e.g. metal spheres, within said hollow body. This correspondingly increases the balancing mass and therefore the balancing capacity even with highly unbalanced loads, but has the drawback that in this case said spheres under the action of the centrifugal force tend to form a single section of non-superimposed spheres.

Obviously this solution generates a drawback, due to the fact that in this case the distribution of the masses over a too wide arc reduces the balancing capacity since the balancing components of the centrifugal force relative to the spheres farthest from the center of the lobe compensate each other in part, as shown in fig. 4 where F1 is opposed to F2.

To overcome this further drawback it becomes advantageous to make a plurality of distinct hollow bodies, having not necessarily identical characteristics, arranged side by side (see the two sections of fig. 5, 1 in which the left section is the section identified as A-A of the right) to increase the overall balancing mass without incurring the aforementioned drawbacks of a balancing mass which covers an excessively extended arc of the hollow body.

The realization and installation of a plurality of hollow bodies opens up a new interesting possibility '(fig. 6).

In fact these hollow bodies, which for descriptive simplicity are considered identical, can be oriented in such a way as to have non-zero angles between contiguous lobes and therefore in the hypothesis illustrated in fig. 6 of a certain number of identical hollow bodies angled to each other by the same angle equal to the round angle divided by the product of the number of hollow bodies by the number of lobes of each hollow body, (in which two hollow bodies are exemplified each equipped with three lobes, with a total therefore of 6 lobes that are arranged at regular intervals of 360 ° / 6) we obtain the advantageous configuration of a device having good balancing capabilities both for the quantity of mass to balance them and for the centering of said mass,

where said balancing capacity is further increased due to the fact that said balancing mass can be divided into several hollow bodies arranged so that their action taken as a whole expresses an optimal balancing action whatever the position of the unbalanced load in the basket.

Another improvement due to the plurality of hollow bodies consists in arranging said bodies in contact with the side walls of the basket, (fig 7) and not arranged on the cylindrical area, where they would cause the inconvenience of occupying a large part of the space dedicated to the holes. d1 lye in / out. In this case, so that more hollow bodies are all in contact with the side walls, they must be sized so that they can be inserted into each other.

The f1g. 7 shows the example of only two hollow bodies, but it is natural that this architecture can be extended to more hollow bodies arranged on the same side wall; this improvement extends both to the case of hollow bodies whose lobes are arranged on common radii, shown in fig. 7, both in the case of hollow bodies 1 whose lobes are arranged on different radii, as shown in fig. 7a.

It has also been experimented that an equivalent solution to the solutions proposed so far consists in making the hollow bodies not lobed but circular in shape and with the same diameter, and arranging said hollow bodies so that the respective centers D1, D2, D3 are arranged slightly offset with respect to the axis of the basket, as shown schematically in fig. 10.

It has been verified that this configuration provides a balance markedly similar to the balance of a lobed hollow body having the same perimeter as the external portions (seen in front projection) of the circular hollow bodies, shown with an enlarged line in fig. 10a, where the internal portions of the individual circular hollow bodies are indicated with a dashed line.

Therefore, as will be easily understood by the skilled in the art, all the variations and improvements illustrated above and referring to lobed hollow bodies are also valid if one or more lobed hollow bodies are replaced for each of said hollow bodies, a corresponding plurality of circular hollow bodies, both coplanar and lost or mutually inserted and having a different radius, are arranged laterally and side by side, with respective centers D1, D2, D3 offset with respect to the basket axis.

In particular, the solution of a lobed hollow body consisting of a plurality of offset circular hollow bodies, coplanar and therefore inserted one into the other, is illustrated in fig. 11, which shows a plurality of circular hollow bodies 11, 12, 13 having different radii S1, S2, S3 respectively; said circular hollow bodies have the same depth 'H and said radii are chosen so that, and the respective centers D1, D2, D3 are offset with respect to the axis 0 of the basket and are rotated between them with respect to said axis by an equal angle a "(in the case d1 fig. 11, a" = 120 °) 1 so that said hollow bodies can be perfectly inserted one into the other, in a combination of the "Chinese box" type.

Advantageously, from the constructive point of view, said combination of hollow bodies is made of one piece, and therefore constitutes a cylinder, as exemplified in fig. 11, where the external cylindrical surface T of said piece including said hollow bodies are also shown, and the projection on the base in view of said cylinder of the three thicknesses d that delimit said hollow bodies one from the other. An advantageous improvement of the invention also consists in the adoption of movable masses formed as a thick disc and rotatable within said hollow bodies having a section substantially similar to the section of said disc D, (Fig. 8). It is in fact known and easily demonstrable that for the same total volume occupied by the portion of the hollow body filled with mobile masses, the injured of the mobile masses is greater when these are precisely formed in discs than when they are spherical, using the most appropriate in both cases in relation to the section of the respective hollow bodies.

Said improvement is further improved if the substantially rectangular section of said hollow body has an increased width, e.g. with sloping walls p (fig. 9a) or with rounded edges (fig. 9b) with respect to the width of the thick discs, with the outer edge of the hollow body that narrows to a width similar to the width of the thick disc.

This allows a freer and more regular rotation of the thick discs within the hollow bodies since it minimizes the possibility of contact and therefore of friction between said elements E to favor the sliding of said movable masses within the respective hollow bodies, and to reduce the noise arising from their movement it is advantageous to introduce lubricating fluid into said hollow bodies, preferably oil with a limited viscosity within the operating temperature range of the drum.

Finally, a further improvement consists in the use of movable masses constituted not by a plurality of distinct solids, but by a dense fluid mass, preferably a liquid having the function of facilitating the movement and in which a quantity of very small particles with high specific gravity, such as sand, shavings or metal dust etc. -

This composition would have the advantage of simplifying the construction of the moving masses, of having an even better balancing capacity since the mass thus constituted would not suffer from the discontinuities of distinct moving masses and also because the ratio between the mass produced and the volume occupied under certain conditions might be even better than in the above illustrated case of thick disk-shaped movable masses.

Although the invention has been described on the example of the preferred embodiments and with a known terminology, it is not considered limited by these poles since the skilled in the art can make numerous variations. It is therefore intended that the appended claims include such obvious modifications which are apparent to those skilled in the art, and which are within the true spirit and scope of the present invention.

Claims (2)

CLAIMS 1) - Particularly domestic washing machine, equipped with an external cabinet, a washing tank, a perforated cylindrical basket contained in said tank and able to rotate inside it around the axis of the cylinder during washing and centrifugation, said basket being equipped with a dynamic balancing device consisting of a plurality of annular hollow bodies closed and arranged integrally with said cylindrical basket, and of a plurality of mobile masses sliding freely within said hollow bodies, characterized in that at least one of said annular hollow bodies is formed with a plurality of lobes protruding towards the outside of the perimeter of said hollow body. 2) Washing machine according to claim 1, characterized in that said annular hollow bodies are arranged in the same plane and centered coaxially with the axis of the drum and have maximum and minimum dimensions of the respective annular shapes so as not to interfere 3) - Machine washing machine according to claim 1, characterized in that said annular hollow bodies are arranged so that at least two of them are side by side. 4) Washing machine according to any one of the preceding claims, characterized in that said hollow bodies are rotated between them, with respect to the axis of the drum, by the same angle d1360 ° / (m. N), where m is the number of bodies hollow and n is the number of lobes for each hollow body. 5) Washing machine according to any one of the preceding claims, characterized in that at least one of said annular hollow bodies having s lobes is constituted by a plurality of circular hollow bodies (11, 12, 13) each of which has its respective center (DI, D2, D3) rotated from the center of another of said hollow bodies, with respect to the axis of the drum, by the same angle of 360 ° / s 6) Washing machine according to claim 5, characterized in that said hollow bodies circular annular rings offset from each other (11, 12, 13) have different radii (S1, S2, S3) and are inserted one into the other in a coplanar manner. 7) Washing machine according to claim 6, characterized by the fact that said circular hollow bodies mutually offset have the same thickness (H) and are formed in one piece. 8) Washing machine according to any one of the preceding claims, characterized in that said movable masses are shaped like a thick disk and that the cross section of said hollow bodies is rectangular and of dimensions suitable to allow the sliding by rotation of said movable masses to thick disk. 9) Washing machine according to any one of the preceding claims, characterized in that the cross section of said hollow bodies is rectangular and slightly flared towards the outer edge, and that a play is provided between the internal wall of said hollow bodies and the surface lateral of said movable disc masses. 10) Washing machine according to any one of the preceding claims, characterized in that said movable masses consist of heavy fluid substances.