DESCRIPTION

Technical Field

This invention relates to a washing appliance and to a method for making it.

Prior Art

Known in the prior art are laundry washing machines comprising a drum and a drive motor connected to the drum by a tripod joint. A tripod joint is a structure with three arms extending from a central body which is connected to the rotational drive shaft. The three arms are connected by threaded connections to the rear flank of the drum in order to transmit drive from the shaft to the drum.

Disclosure of the Invention

In this context, the aim of this invention is to provide a washing appliance that is simpler in construction.

Another aim of the invention is to simplify washing appliance assembly.

A further aim of this invention is to propose a washing appliance which allows the functions of the individual components to be optimized.

The technical purpose and aims specified are substantially achieved by a washing appliance comprising the technical features set out in one or more of the accompanying claims.

Brief Description of the Drawings

Further features and advantages of the invention are more apparent in the non-limiting description which follows of a preferred non-exclusive embodiment of a washing appliance illustrated in the accompanying drawings, in which:

- Figure 1 is a front view of a drum for a washing appliance according to this invention;

- Figures 2 and 3 are, respectively, a front and a rear perspective view of a drum for a washing appliance according to this invention;

- Figure 4 shows a cross section through the plane A- A of Figure 1; - Figure 5 shows the detail "C" from Figure 4;

- Figure 6 shows a washing appliance according to this invention.

Detailed Description of the Preferred Embodiments of the Invention

With reference to the accompanying drawings, the numeral 1 denotes a washing appliance comprising a drum 2 which forms a washing compartment 20.

The washing appliance 1 is a laundry washing machine.

The drum 2 can rotate about an axis of rotation 21. Rotation improves washing efficiency by moving the articles to be washed and also allows them to be spin dried. The drum 2 comprises an opening 22 for loading and extracting the articles to be washed. In front- loading laundry washing machines, the opening 22 faces an external door 23, while in top- loading laundry washing machines the opening 22 can normally be closed by a door built into the drum 2.

The washing appliance 1 comprises a shaft 3 for rotationally driving the drum 2 and extending along the axis 21 of rotation. The rotational drive shaft 3 allows transfer to the drum 2 of the rotational motion imparted by an electric motor (not illustrated) forming part of the washing appliance 1.

The drum 2 also comprises a flank 4 which extends transversally to the rotational drive shaft

3 and which partly delimits the washing compartment 20 of the drum 2.

The flank 4 comprises a hole 5 coaxial with the axis 21 of rotation in which the rotational drive shaft 3 of the drum 2 is inserted. Advantageously, the rotational drive shaft 3 is irremovably embedded in the coaxial hole 5 (in which case, the rotational drive shaft 3 can be considered as being integrated into the drum 2). Conveniently, at the interface between the shaft 3 and the flank 4, every point on the flank 4 adheres stably and irremovably to the shaft 3. That means there is no need for a tripod joint to connect the rotational drive shaft to the drum.

Advantageously, the flank 4 and the rotational drive shaft 3 are obtained by overmoulding the flank 4 over the shaft 3.

As illustrated by way of an example in Figure 4, the flank 4 comprises a first wall 41 and a second wall 42 alongside each other. The first and the second walls 41 , 42 are irremovably connected.

In the preferred embodiment, the first and second walls 41 , 42 are made at least partly of a material having a plastic matrix. More specifically, the first wall 41 is at least partly (or substantially) made of a plastic material charged with calcium. In particular, the material must be such as not to damage the laundry by friction. The second wall 42 is at least partly (or substantially) made of a plastic material charged with fibre glass. The mechanical and stress resistance properties of this material are greater than those of the material used to make the first wall 41. The use of plastic materials makes it possible to limit the rotating mass, with advantages in terms of reduced vibrations. Further, as explained better below, the use of plastic material facilitates assembly to the rest of the drum 2. The use of plastic material is also important because it allows costs to be reduced.

Conveniently, the first and second walls 41 , 42 are joined to each other by die-casting.

The first wall 41 contributes to delimiting the washing compartment 20. It is thus intended to come into contact with the articles to be washed located inside the washing compartment 20. Advantageously, the rear end 40 comprises means 409 for pushing the articles to be washed. In this regard, the pushing means 409 comprise ribs 410 made as one with the first wall 41. The ribs 410 project towards the inside of the drum 2. More specifically, the ribs 410 project towards the opening 22. Further, the ribs 410 comprise passages 411 which place the washing compartment 20 in fluid communication with a gap 412 which is interposed between the first and second walls 41, 42 along the direction of the axis 21 of rotation.

Conveniently, the second wall 42 comprises the coaxial hole 5 for receiving the rotational drive shaft 3. Conveniently, the rotational drive shaft 3 is made of a metallic material (typically steel). In the preferred embodiment illustrated in the accompanying drawings, the flank 4 is a rear end 40 of the drum 2 at least partly facing the opening 22 for introducing and extracting the articles to be washed (this solution applies to front-loading laundry washing machines). The flank 4 comprises first means 43 for balancing the mass of the articles to be washed in the drum 2. The first balancing means 43 comprise a first annular chamber 430 which encircles the axis 21 of rotation and which is suitable for containing first rolling members 431. Conveniently, the first balancing means 43 comprise: the first annular chamber 430 filled with a viscous liquid (for example, silicone oil) and first rolling members 431 which roll along the first annular chamber 430.

In effect, during spin drying, centrifugal force causes the laundry articles to move against the inside wall of the drum 2. This may lead to vibrations and noise due to eccentricity.

At least for drum rotation speeds higher than a predetermined threshold, the first balancing means 43 move to positions which are diametrically opposite (relative to the axis of rotation 21) to those where an imaginary eccentric mass determined by the presence of the laundry articles can be located. This allows vibrations and noise to be reduced.

The first rolling members 431 comprise steel balls. Typically, the first rolling members 431 comprise 10 to 15 balls. Preferably, the balls are between 13 and 17 millimetres in diameter. In the first annular chamber 430 there is a quantity of viscous liquid of between 0.25 and 0.65kg.

The first annular chamber 430 is formed by coupling the first and second walls 41, 42. The first annular chamber 430 is fluid-dynamically sealed. In the non-limiting example embodiment of Figure 5, the first annular chamber 430 is made by combining together a groove 433 defined by the second wall 42 and a flat surface 444 defined by the first wall 41. Conveniently, the first rolling members 431 are completely inside the groove 433.

Conveniently, the first annular chamber 430 comprises an opening which can be blocked by a fluid-tight plug and which is used for pouring in the viscous liquid (once the first rolling members 431 have been stably inserted into the groove 433). The first rolling members 431 are of a size such that they cannot be extracted from the first chamber 430 through the opening.

The drum 2 comprises a lateral annular band 7 which encircles the axis 21 of rotation of the drum 2. The band 7 comprises at least one bent edge 71 which forms a first seat 710 for receiving and retaining a perimeter portion of the flank 4, thus making the band 7 and the flank 4 integral with each other. Conveniently, the band 7 is made from metal sheet, typically stainless steel. It is obtained by calendering. Normally, the band 7 is between 0.35 and 0.65 millimetres thick.

Advantageously, the first seat 710 receives and retains a perimeter portion of the first and second walls 41, 42, the perimeter portion of the first wall 41 being adjacent to the perimeter portion of the second wall 42. More specifically, the first seat 710 at least partly encircles two transversal surfaces of the perimeter portion of the first wall 41 and three transversal surfaces of the perimeter portion of the second wall 42.

More specifically, the first seat 710 comprises:

-a first annular stretch 711 which extends in a direction which is substantially radial to the axis 21 of rotation and which is in contact with the first wall 41 ;

-a second annular stretch 712 which is transversal (preferably at right angles) to the first annular stretch 711 and which is in contact with the first and second walls 41, 42;

-a third annular stretch 713 which extends in a direction which is substantially radial to the axis 21 of rotation and which is in contact with the second wall 42; the first stretch 71 1, the second stretch 712 and the third stretch 713 forming a concavity that faces towards the axis 21 of rotation;

-a fourth annular stretch 714 which is transversal (preferably at right angles) to the third annular stretch 713 and which is in contact with the second wall 42. The fourth stretch 714 comprises an edge of the annular band 7. Thus, the fourth stretch 714 is not in contact with other portions of the annular band 7 apart from the third stretch 713.

Advantageously, the first and second walls 41 , 42 are at least partly interposed between the first and second stretches 711, 713. Advantageously, the second wall 42 is at least partly interposed between the second and fourth stretches 712, 714.

Conveniently the washing appliance 1 comprises a flange 6 which encircles the opening 22 for introducing and extracting the laundry articles.

The lateral band 7 comprises a second bent edge 72 forming a second seat 720 for receiving and retaining the flange 6, thus making the lateral band 7 and the flange 6 integral with each other. Conveniently, the flange 6 comprises a third and a fourth wall 45, 46 which are irremovably connected to each other (for example by die casting). The third wall 45 is interposed between the first and fourth walls 41, 46.

Advantageously, the second seat 720 receives and retains a perimeter portion of the third and fourth walls 45, 46, the perimeter portion of the third wall 45 being adjacent to the perimeter portion of the fourth wall 46.

The flange 6 comprises second means 44 for balancing the mass of the laundry articles to be washed in the drum 2. The second balancing means 44 comprise: a second annular chamber 440 filled with a viscous liquid, encircling the axis 21 of rotation, and second rolling members 432 which roll along the second annular chamber 440, the second annular chamber 440 being formed by the combination of the third and fourth walls 45, 46.

The technical features described above in connection with the first balancing means 43 also apply to the second balancing means 44. More specifically, the adjectives "first" and "second" referring to the expressions "balancing means", "annular chamber" and "rolling members" are used only to distinguish the components from each other. For example, the washing appliance 1 according to this invention might have the second balancing means 44 or a second annular chamber 440 or second rolling members 432 irrespective of whether or not it has first balancing means 43, a first annular chamber 430 or first rolling members 431. Similarly, the presence of a third and a fourth wall 45, 46 might be independent of the first and second walls 41, 42.

Conveniently, the drum 2 is substantially cylindrical. The annular band 7 corresponds to the lateral surface of the cylinder. The flank 4 is located at one of the two bases of the cylinder. The flange 6 is located at the other base of the cylinder. Advantageously, the drum 2 (more specifically, one base of the cylindrical drum 2) has a variable or constant diameter of between 400 and 420 millimetres. The annular band 7 is at least partly interposed between the flange 6 and the flank 4.

The annular band 7 contributes to delimiting the gap 412. More specifically, at the gap 412, the annular band 7 comprises a plurality of holes 413. The holes 413, in combination with the passages 411, allow the washing compartment 20 to be placed in fluid communication with the outside of the drum 2 (for example, to facilitate draining off of the water from the laundry articles during spin drying).

This invention also has for an object a method for making a drum for a washing appliance having one or more of the technical features described above.

The method comprises the steps of:

-overmoulding the second wall 42 and the rotational drive shaft 3;

-joining (more specifically, welding) the first and second walls 41 , 42 to each other by die- casting thereby obtaining the flank 4;

-clamping the lateral band 7 to the flank 4 and to the flange 6.

Advantageously, the step of joining the first and second walls 41 , 42 to each other by die- casting is preceded by the step of resting the first rolling members 431 on the portion of the first annular chamber 430 formed by the second wall 42. Preferably, the portion of the first annular chamber 430 formed by the second wall 42 is an extended portion, the groove 433 being made entirely on the second wall 42, so as to obtain a more secure housing for the first rolling members 431 during the subsequent welding operation. The step of die-casting the first and second walls 41, 42 determines the formation of the first annular chamber 430 delimited by the first and second walls 41, 42.

Advantageously, the step of clamping the lateral band 7 to the flange 6 is preceded by the step of irremovably connecting the third and fourth walls 45, 46 of the flange 6 by die- casting. Advantageously, the step of joining the first and second walls 41, 42 to each other by die-casting is followed by the step of filling into the first chamber 430 the viscous liquid that surrounds the first rolling members 431. The step of filling the viscous liquid into the first chamber 430 comprises the step of pouring the liquid in through the opening which can be closed by a plug.

The invention achieves important advantages and provides a device which is functional and feasible, that is to say, a laundry washing machine where the eccentric loads inside the drum can be well balanced, while at the same time limiting the cost of the machine as a whole. More specifically, it allows the components of the drum 2 to be optimized. More specifically, the flank 4 (which, in the preferred embodiment, coincides with the rear end 40 of the drum 2) has important structural functions, making it possible to eliminate the need for a tripod joint. Moreover, it can be easily connected to the lateral band 7, plays an important role in balancing the drum 2 and also integrates the means 409 for pushing the laundry articles to be washed (known as "lifters" in the jargon of the trade).

Lastly, the invention provides a laundry washing machine whose drum is considerably increased in strength thanks to the fact that the rear end of the drum is made like a box- shaped structure as a result of welding the first wall 41 and the second wall 42 to each other. It shall be understood that the invention described above may be modified and adapted in several ways without departing from the scope of the inventive concept. Moreover, all the details of the invention may be substituted by other technically equivalent elements. Further, the embodiments of the invention may be made in any size, depending on requirements.