Tubular bushing co-moldable with tubs of washing machines

A tubular bushing co-moldable with tubs of washing machines is provided. The tubular bushing is suitable to be engaged by a drive shaft of the washing machine extending along a central axis (A) and being provided with two rolling bearings (20), arranged at a given distance from each other along the axis (A) to allow rotation of the drive shaft with respect to the tub, and a containing sleeve, made of plastic and by means of co-molding around the two bearings; a current dispersion means being incorporated in the containing sleeve and suitable to be electrically connected both to the drive shaft and to earth so as to prevent an accumulation of static electricity in the washing machine and prevent electrostatic discharges.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Italian Patent Application No. TO2013A000743 filed Sep. 13, 2014, the contents of which are herein fully incorporated by reference.

FIELD OF THE INVENTION

The present invention is related to a tubular bushing co-moldable with tubs of washing machines.

BACKGROUND OF THE INVENTION

Known tubular bushings, co-moldable with tubs of washing machines, are suitable to be engaged by a drive shaft of the washing machine, in order to support, by means of the drive shaft, the rotatable drum inside the tub. Known tubular bushings comprise two rolling bearings, to allow a rotation of the drive shaft, and a containing sleeve, which is made of plastic and by means of co-molding around the two bearings.

Such known tubular bushings are suitable to be co-molded with the tubs of the washing machines, to simplify the production process of said washing machines. In particular, the bushing containing sleeve is co-molded together with tubs of washing machines, so as to realize one piece with the said tubs, allowing remarkable savings in process time, handling time and components number.

Before this simplification, tubular bushings were made of metal materials, so as drums and tubs of washing machines, and any accumulation of static electricity, due to drum rotation or to fabrics friction inside the drum, was almost prevented. The arrival of new co-molded tubular bushings, having the majority of their components made of plastic material and being electrically insulated, if on one hand has simplified a lot the production of current washing machines, on the other hand has caused the insurgence of electrostatic problems for the same washing machines.

SUMMARY OF THE INVENTION

Aim of the present invention is to realize a tubular bushing co-moldable with tubs of washing machines, the tubular bushing does not showing the above mentioned inconveniences.

According to the present invention, a tubular bushing co-moldable with tubs of washing machines is realized, the tubular bushing having the characteristics as in the enclosed independent claim.

Further embodiments of the invention, preferred and/or particularly advantageous, are described according to the characteristics as in the enclosed dependent claims

DETAILED DESCRIPTION OF THE INVENTION

With reference toFIGS. 1 and 3, in such drawings is shown as a whole a tubular bushing10co-moldable with a tub of a washing machine (known and not shown), to support, in a rotatable way around a central axis X of rotation, a drive shaft15of a drum (known and not shown) of said washing machine. The tubular bushing10extends along the axis X between a side13, so called “humid”, being close to the mentioned tub and a side14, so called “dry”, being close to the washing machine outside, and comprises:two rolling bearings20(only one of them is shown) located along the axis X and engaged by the drive shaft15to allow the rotation of the drive shaft15with respect to the mentioned tub; anda spacer40axially interposed between the two bearings20.

The bearing20, of the two rolling bearings20, which is shown inFIG. 3, is the one located along the tubular bushing10, on the dry side14. The bearing20comprises a rotatable inner ring21, engaged by the drive shaft15, a stationary outer ring22and a plurality of rolling bodies23, interposed between the rings21and22. Both the rings21and22, the rolling bodies23and the drive shaft15are made of metal material, anyhow of electrically conductive material. Moreover, the tubular bushing10comprises a containing sleeve50, which is made of plastic material and is co-molded around the two bearings20and the spacer40. The spacer40has the function to define a structural stiff element of the tubular bushing10and to retain the two bearings20at a determined axial distance from each other, during the co-molding process.

Finally, the tubular bushing10comprises dispersion means70, for example, a current dispersion device70, which is incorporated in the containing sleeve50and is electrically connected both to the drive shaft15and to earth, to prevent an accumulation of static electricity in the washing machine and prevent electrostatic discharges.

According to what is also shown inFIG. 2, dispersion means70comprise a socket71, which is defined as a hollow cylindrical body71, made of electrically conductive material and partially embedded in the containing sleeve50, and an intermediate transfer body81, which is also made of electrically conductive material. The body81is almost completely embedded in the containing sleeve50and is located close to both the body71and the bearing20, on the dry side14. The bodies71and81are located along the outer edge of the containing sleeve50and axially aligned to the bearing20, and present correspondent outer surfaces71aand81aarranged so as to make contact each other. The body71is located radially outwards the body81, which is located in an intermediate position between the body71and the bearing20, and whose surface81ais arranged so as to be also in direct contact with the outer ring22of the bearing20.

The body71presents a central axis Y, parallel to the axis X, and is axially confined by an axial face72, which is transversal to the axis Y, and is completely exposed outside the containing sleeve50, on the dry side14. Preferably, the body71is provided with an inner thread73, while the body81is defined by a roll, which is a normally available element for rolling bearing producers.

Moreover, dispersion means70comprises a pin91, made of electrically conductive material and releasable engaged inside the body71, and an earth electrical connection92, electrically connected to the pin. The pin91, which is shown inFIG. 3in its disengaged position, can be a plug or, if the body71were provided with the thread73, as in the preferred embodiment of the present invention, is an earthing screw and is screwed in an unscrewable manner inside the said body71.

While the tubular bushing10is mainly made of plastic material, so as to prevent any electrical connection between the drum of the washing machine and the external environment, thus electrically insulating the drum of the washing machine from the remaining parts of said washing machine, dispersion means70, as above disclosed, comprise elements—the body71, the body81, the pin91, the electrical connection92—all electrically conductive. Such elements are arranged so as to make contact each other and realize an electrical circuit, which starts from the drive shaft15, goes through the bearing20, and ends at earth, through the connection92. Therefore, since the drive shaft15is connected to the drum of the washing machine, to let the drum rotating, dispersion means70allow to discharge at earth any accumulation of static electricity in the washing machine, thus preventing possible electrostatic discharges.

To allow a correct co-molding of the tubular bushing10with the tub of the washing machine, in other words, to allow the axis Y of dispersion means70being located in a suitable position for connecting the device towards the outside of the washing machine and towards earth, by means of the pin91and the electrical connection92, the tubular bushing10also comprises references means95, out of the containing sleeve50, axially on the opposite side with respect to dispersion means70, in other words, on the humid side13of the containing sleeve50, and is axially aligned with the device70.

Since the tubular bushing10has a substantially cylindrical outer shape, such reference means95make easier the handling of said tubular bushing10during the co-molding process with tubs of washing machines, simplifying said process and always ensuring the same positioning of dispersion means70.