Patent Publication Number: US-2023160128-A1

Title: Sealing device for sleeves of washing machines

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority to Italian Patent Application No. 102021000029618 filed on Nov. 24, 2021, under 35 U.S.C. § 119, the disclosure of which is incorporated by reference herein. 
     FIELD 
     The present disclosure relates to a sealing device for sleeves of washing machines, which seals off the portion of the machine including the bearing units for supporting the rotary shaft from the portion of the machine dedicated to washing and including the washing tub of the washing machine. 
     BACKGROUND 
     The sleeves of washing machines may be interposed between the tub of the washing machine and a motor shaft for driving the drum of the washing machine. 
     The sleeves typically include a hub and a pair of rolling bearings, which are housed inside the hub and are engaged by the motor shaft, which projects out from the sleeve so as to support the drum. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will now be described with reference to the attached drawings, which show exemplary embodiments thereof, in which: 
         FIG.  1    is a cross-sectional view of the portion of the washing machine, which houses the sealing device according to exemplary embodiments of this disclosure, and 
         FIG.  2    is a radial cross-sectional view of a sealing device according to exemplary embodiments of this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The sleeves of washing machines may be interposed between the tub, which may be made of plastic, of the washing machine and a motor shaft for driving the drum of the washing machine 
     The sleeves are typically co-molded in the plastic material of the tub, and include a hub which may be made of metal and a pair of rolling bearings, which are housed inside the hub axially spaced apart from one another and are engaged by the motor shaft which projects out from the sleeve so as to support the drum. 
     On the side where the motor shaft projects axially from the sleeve, in order to protect the rolling bearings from water, detergents and other solid contaminants, such as sand, fibers and pebbles, a sealing device may be provided, which may have two support screens and two or three sealing lips mounted on a first screen of the two support screens and in sliding contact with the second screen of the two support screens. To increase the sealing action, one of these lips may be also equipped with a spring, which presses the relative lip radially against the sealing surface of the second screen. 
     Such sealing devices, although providing optimum sealing capacity, have rather large axial dimensions, which limit, in some cases, the usable space for the tub, in other words its volume, especially in cases where the related washing machines have to have small axial dimensions. 
     The sealing devices described above have optimum sealing capacity but may also give rise to relatively high friction forces to the detriment of the energy consumption of the washing machines. 
     One object of the present disclosure is to provide a sealing device for sleeves of washing machines, which makes it possible to optimize the space available for the tub even in washing machines with small axial dimensions. 
     Another object of the present disclosure is to provide a sealing device for sleeves of washing machines which, as well as having good sealing capacity, has low friction and offers savings in terms of consumption. 
     According to the present disclosure, the sealing device has an optimized shape for reducing axial size, which benefits tub capacity and internal friction. 
     By way of non-limiting example and with reference to  FIGS.  1 - 2   , the sealing device for sleeves of washing machines is designated by the reference sign  1 . In such machines, use may be made of two radial “deep groove” ball bearing units, and the sealing device may be mounted axially externally to the latter. 
       FIG.  1    shows the portion of the washing machine, which houses the sealing device  1 . One bearing unit  2  of the pair of bearing units may include a radially outer ring  3 , a radially inner ring  4  and a row of rolling bodies  5 . A sleeve  6  may be provided which is stationary and integral with a washing tub of the washing machine. A motor shaft  7  may project out from the sleeve so as to support the drum of the washing machine. All of the above components are axisymmetric with respect to a central axis A. 
     Throughout the present description and in the claims, terms and expressions indicating positions and directions such as “radial”, “axial” or “transverse” are intended with reference to the axis of symmetry A. 
     With reference to  FIG.  2   , the sealing device  1  may include a first annular stationary screen  8  configured to be connected in use to the sleeve  6 , and a second annular rotating screen  9  facing the first annular stationary screen  8 , and configured to be connected in use to the motor shaft  7 . In various embodiments, first annular stationary screen  8  and second annular rotating screen  9  are made of sheet metal. First annular stationary screen  8  may have a first cylindrical mounting portion  8   a  and a first flange portion  8   b . Second annular rotating screen  9  may have a second cylindrical mounting portion  9   a  and a second flange portion  9   b.    
     The two cylindrical annular screens  8 ,  9  facing each other define a first annular meatus M of predetermined axial dimensions. 
     The sealing device  1  may further include a first elastomeric element  10  carried integrally by the first annular stationary screen  8  facing the second annular rotating screen  9 . The first elastomeric element  10  may be provided with at least one annular sliding sealing lip  11  configured to cooperate in contact, in use, with the second cylindrical portion  9   a  of the second annular rotating screen  9 . 
     Sealing device  1  may further include a second elastomeric element  12 , carried integrally by the second annular rotating screen  9 , facing the first annular stationary screen  8  and facing the first elastomeric element  10 . The first annular meatus M may be defined between the first elastomeric element  10  and the second elastomeric element  12 . The second elastomeric element  12  may further include a non-contacting distal radial portion  13 , configured to cooperate in use with the sleeve  6  to form a second annular meatus M 1  that is configured as a first barrier to the entry of washing liquids or other impurities. This second annular meatus M 1 , taking advantage of the geometrical boundary conditions of the washing machine, makes it possible to minimize the ingress of solid contaminants. 
     According to various embodiments, the first annular stationary screen  8  may be mounted externally with interference in the sleeve  6 , by the interposition of a third cylindrical portion  10   a  of the first elastomeric element  10  between sleeve  6  and first annular stationary screen  8 , and axially, by the first cylindrical portion  8   a  of the screen  8 , against the radially outer ring  3 . This arrangement does not require, for the attachment of the sealing device, any working either of the radially outer ring  3 , for example, the production of an attachment groove, or of the sleeve  6 . 
     Alternatively, according to various embodiments, the first cylindrical mounting portion  8   a  may be mounted with a free annular edge thereof facing the outside of the bearing unit  2  and directly defining the second annular meatus M 1  with the non-contacting distal radial portion  13  of the second elastomeric element  12 . 
     In various embodiments, the second annular rotating screen  9  may be mounted internally with interference on the motor shaft  7  and axially, by means of the second cylindrical portion  9   a  of the second annular rotating screen  9 , against the radially inner ring  4 . 
     In various embodiments, the first elastomeric element  10  and the second elastomeric element  12  may be provided with a plurality of pairs of annular sealing lips L 1 , L 2  arranged inside the first annular meatus M. The first sealing lip L 1  and the second sealing lip L 2  of the plurality of pairs of annular sealing lips L 1 , L 2  may be substantially radially and axially superimposed and have predetermined axial dimensions to define, inside the first annular meatus M and with the first and the second sealing lips of the other pairs of annular sealing lips L 1 , L 2 , a tortuous labyrinth L, configured to make it difficult for any washing liquids or other impurities to enter the sleeve  6 , in other words the portion of the washing machine in which the bearing units  2  are housed. 
     The first and the second sealing lip of each pair of annular sealing lips L 1 , L 2  may be radially and axially superimposed, but also radially and axially separate, in other words free of one another without any point of contact. 
     In various embodiments shown in  FIG.  2   , the first elastomeric element  10  and the second elastomeric element  12  may be respectively provided with an equal number N of annular sealing lips L 1 , L 2 , where the value of N, in order to obtain the required sealing efficiency, may be greater than three. Advantageously, as shown in  FIG.  2   , both the first elastomeric element  10  and the second elastomeric element  12  may each be provided with five annular sealing lips L 1 , L 2 , which are non-contacting. 
     Both the number and the axial dimensions of the annular sealing lips L 1 , L 2  may be optimized in such a way as to make the tortuous labyrinth L as long as possible, compatibly with the dimensions of the meatus M, and as narrow as possible, at the same time avoiding the annular sealing lips L 1 , L 2  coming into contact with one another and giving rise to friction losses. 
     In various embodiments, the second annular screen  9  may be designed such that the second cylindrical portion  9   a , used for attachment, faces the radially inner ring  4 . This also means that the annular sliding sealing lip  11  slides on the radially external surface  9   a ′ of the second cylindrical portion  9   a . There are primarily two advantages: 
     improved fitting of the sealing device, since the second cylindrical portion  9   a  comes into abutment against the lateral surface of the radially inner ring  4 . Furthermore, the second cylindrical portion  9   a  has a radially external lateral surface  9   a ′ of slightly truncated cone shape, thus preventing the annular sliding sealing lip  11  from being deformed during fitting. 
     axial size of the entire sealing device  1  reduced to a minimum. 
     In short, this sealing device makes it possible to obtain a number of advantages and achieve the aims set out by the present disclosure. 
     First of all, the reduction in friction losses and hence a significant saving on energy. Sealing performance is provided by the tortuous labyrinth and, therefore, is not correlated with the force of contact of the sliding lip with the benefit of the reduction in friction losses. 
     Second, this sealing device, which takes advantage of the concept of “guttering”, in other words two facing screens very close to one another, enables a significant reduction in axial size, equal to less than half with respect to other known solutions. This maximizes the axial space available for the washing tub and therefore increases the load capacity of the drum of the washing machine. 
     Third, the optimization of the tortuous labyrinth, which may be made very long and very narrow by the number and dimensions of the pairs of sealing lips, makes it possible to take maximum advantage of the sealing offered by the “guttering” system and ensure excellent sealing performance. All of this is further provided by the geometry of the second elastomeric element comprising the non-contacting distal radial portion that forms with the sleeve the second annular meatus, and this meatus works as a first barrier to the entry of water and contaminants. 
     Lastly, the fitting of the sealing device is simplified, since it does not require further working of the other components, and may be made as abutment surfaces of the surfaces of the rings of the bearing unit. 
     Note that, in addition to the embodiments of the disclosure described above, many other variants exist. It must also be understood that these embodiments are simply examples and do not limit the scope of the disclosure or its applications or its possible configurations. On the contrary, although the description above makes it possible for a person skilled in the art to implement the present disclosure at least according to one exemplary embodiment thereof, it must be understood that many variations of the components described are possible without thereby exceeding the scope of the disclosure as defined in the attached claims, interpreted literally and/or according to their legal equivalents.