Patent Publication Number: US-2023160472-A1

Title: Sealing device for washing machine sleeves

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority to Italian Patent Application No. 102021000029621 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 washing machine sleeves. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will now be described with reference to the attached FIGURE: 
         FIG.  1    shows a cross-sectional, radial elevation view of a sealing device according to exemplary embodiments of this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Known washing machines include a washing tub, which may be made of plastic, a drum housed inside the tub and angularly connected to a drive shaft that is rotatably supported by the tub by a sleeve. The sleeve may include a tubular hub made of a metallic material and co-molded in the plastic material of the washing tub and a pair of rolling bearings housed inside the tubular hub. The pair of rolling bearings may be axially spaced from each other in order to be engaged by the drive shaft that projects outside the sleeve itself on a side of the washing tub in order to support the drum. On a side opposite the washing tub, there may be a joint for connection to a washing machine motor. 
     Known sealing devices for washing machine sleeves may be mounted in a position axially in front of the corresponding sleeves on the same side as the washing tub, namely the side where the drive shaft axially projects from the sleeve to engage the inside of the drum. These sleeves are completely exposed to washing water, detergents, and solid contaminants (e.g., sand, fibers, and gravel) present in the washing tub. These sleeves serve to protect the rolling bearings inside the tubular hub from these contaminants. 
     Known sealing devices may have a first, shaped, metallic screen engaged onto the drive shaft and a second metallic support screen integrally mounted on the washing tub and provided with sealing lips in sliding contact with the first screen. Usually, in order to provide a good sealing action, at least two sealing lips diverge axially from each other, thereby increasing the dimensions and the axial volumes of the sealing device. At least one of these sealing lips may also be provided with an annular spring for increasing the radial pressure of the sealing lip on the first screen, with a resulting increase in sliding friction, decreasing an operating efficiency of the entire washing machine. 
     Therefore, known sealing devices having optimum sealing capacities may also have relatively large axial dimensions, limiting the useful space for the washing tub. In cases in which the washing machine require reduced axial volumes, relatively high frictional forces can be produced to the detriment of energy consumption of the washing machines. 
     It is therefore an object of the present disclosure to provide a sealing device for a washing machines sleeve that achieves a high sealing capacity and low friction levels, while having dimensions optimized for a washing tub in a washing machine with reduced axial dimensions. A further object of the present disclosure is to reduce energy consumption levels and ensure an easy assembly, even by manufacturers who produce the washing machines. 
     According to an exemplary embodiment,  FIG.  1    illustrates a washing machine  100 . Washing machine  100  may include a washing tub  110 , a drum (not shown for simplicity of illustration) rotatably arranged inside washing tub  110 , and a drive shaft  7  for rotation of the drum inside washing tub  110 . A sleeve  6  may be integrally joined together with washing tub  110 . In various embodiments, sleeve  6  may be co-molded with washing tub  110 . 
     Drive shaft  7  may include a mounting shoulder  7   a  that projects outside of sleeve  6  for supporting the drum, and is in turn rotatably supported inside sleeve  6  by a pair of bearing units  2  (only one of which is shown for simplicity of illustration). Each bearing unit  2  may include a radially outer ring  3 , a radially inner ring  4 , and a row of rolling bodies  5  arranged between radially outer ring  3  and radially inner ring  4 . 
     In the whole of the present description and in the claims, terms and expressions which indicate positions and directions, such as “radial”, “axial” or “transverse”, are to be understood as being in relation to a central axis of symmetry A, which coincides with an axis of rotation of the drum. 
     A sealing device  1  may be arranged axially alongside bearing unit  2  on a same side as washing tub  110 . Sealing device  1  may include an axially extending stationary screen  8  fixed to screen  6  during use and having a cylindrical mounting portion  8   a  and a flange portion  8   b , and an axially extending rotating screen  9  fixed to drive shaft  7  during use and having a cylindrical mounting portion  9   a  and a flange portion  9   b . The axially extending rotating screen  9  faces first screen  8  in the radial direction. In various embodiments, stationary screen  8  and rotating screen  9  are made of sheet metal. 
     Sealing device  1  may further include an elastomeric element  10  integrally mounted on stationary screen  8  and an elastomeric element  12  integrally mounted on screen  9 . Elastomeric element  10  may be provided with one or more axially extending annular sealing lips L 1 , and elastomeric element  12  may be provided with one or more axially extending annular sealing lips L 2 . Annular sealing lips L 1  and L 2  may be non-contacting sealing lips that are similar to each other in composition and design, and are axially contained between flange portions  8   b  and  9   b . Lips L 1  and L 2  may alternate radially with one another to define a sealing labyrinth L. In various embodiments, annular sealing lips L 1  and L 2  may be equal in number N. 
     In various embodiments, lips L 1  and L 2  may have respective opposite conicities, where a conicity of lips L 1  increases towards tub  110 , while the conicity of lips L 2  decreases towards tub  110 . In other words, lips L 1  that are further from axis A of bearing unit  10  have progressively greater conicities than lips L 1  that are closer to axis A, and lips L 2  that are further from axis A have progressively smaller conicities than lips L 2  that are closer to axis A. 
     Sealing lips L 1  extend from flange portion  8   a  of screen  8  towards flange portion  9   a  of screen  9  and towards lips L 2 . Lip L 2  extend from flange portion  9   a  of screen  9  towards flange portion  8   a  of screen  8  and towards lips L 1 . Lips L 1  and L 2  may have a similar projecting length so as to be able to be inserted substantially inside one another (i.e. alternating in the radial direction), almost intersecting, but without coming into contact with one another, and thus forming a sealing labyrinth L with a winding form. 
     Each lip L 1  and L 2  is radially defined by a respective conical surface L 1   s  and L 2   s , respectively, facing away from axis A, and a respective conical surface L 1   i , or L 2   i  facing axis A. In various embodiments, L 1   s  and L 1   i  are substantially parallel and L 2   s  and L 2   i  are substantially parallel. Therefore, each lip L 1  and L 2  may have a substantially constant thickness and terminates at a free end L 1   e  and L 2   e , respectively, which, as a result of limited axial dimensions of sealing device  1 , may be arranged a distance from surface L 2   i  or L 1   i , respectively, of each respective opposite lip L 2  or L 1 . In various embodiments, a distance between opposing free ends L 1   e  and L 2   i , and free ends L 2   e  and L 1   i , is a very small distance on the order to tenths of a millimeter. 
     In various embodiments, sealing labyrinth L, as well as the sealing device  1 , extends along radial length such that an overall axial volume of sealing device  1  may be limited and extremely compact without, however, losing capacity of its sealing action. 
     In various embodiments, sealing device  1  may further include a chamber C 1  and a chamber C 2  defined by flange portions  8   b  and  9   b  and arranged along a labyrinth L. Chamber C 1  and Chamber C 2  may be located at opposite radial ends of sealing labyrinth L. 
     Chamber C 1  is a storage chamber, sometimes referred to as a discharge chamber, arranged at an outer radial end of labyrinth L. Chamber C 2  may be an obstruction chamber arranged at an intermediate radial portion of labyrinth L. Alternatively, chamber C 2  may be arranged at an inner radial end of labyrinth L. 
     In various embodiments, chamber C 1  may have a greater axial length than chamber C 2  due to the fact that a centrifugal speed of annular screen  9  gradually increases in the radial direction away from axis A. The axial lengths of chamber C 1  and chamber C 2  may be proportional to the centrifugal speed of screen  9  at each respective chamber. This difference in the axial length that is proportional to the centrifugal speed of annular screen  9  is advantageous during operating conditions of sealing device  1 . In particular, during use, high tangential speeds caused by rotation of screen  9  creates a centrifugal swirling flow inside of a greater axial length of chamber C 1  that helps prevent entry of contaminants inside labyrinth L. At the same time, the reduced tangential speeds caused by rotation of screen  9  at C 2 , due to its vicinity to axis A, and the reduced axial length of chamber C 2  creates a centrifugal swirling flows with more moderate tangential speeds. This has the effect of slowing down and substantially compacting any contaminants along the labyrinth L, preventing them from advancing further inside labyrinth L. Contaminants are further prevented from traveling along the labyrinth L and into bearing unit  10  by lips L 1  and L 2  extending in the radial direction away from axis A. This results in a plurality of “ramps,” which any contaminants must travel up during their movement along the labyrinth L towards axis A, making it even more difficult for contaminants to reach bearing unit  10 . 
     Chamber C 1  allows a substantial expansion of any contaminants present inside sealing device  1 , favoring an outflow thereof from chamber C 2  and facilitating subsequent expulsion thereof to an external environment. Also the orientation of lips L 1  and L 2  as described herein will favor the outflow of contaminants from chamber C 2  towards chamber C 1 , and in particular along portion of the sealing device  1  arranged at “6 o&#39;clock” zone, namely arranged underneath axis A of a full 360° bearing unit. In this zone, surfaces L 1   s  and L 2   s  of the lips L 1  and L 2 , respectively, act as basic slides for any contaminants during their movement along labyrinth L. 
     In order to further improve the sealing characteristics of sealing device  1  and its capacity for expelling contaminants, while maintaining the reduced axial dimensions of sealing device  1 , screen  8  may include a discharge outlet or discharge surface  50 , which may be arranged in a vicinity of cylindrical mounting portion  8   a  inside sealing device  1 . Discharge surface  50  may radially delimit chamber C 1  and define, together with a free annular edge  51  of screen  9  an annular passage “M,” which has an extremely small axial dimension to prevent entry of contaminants, such as sand and the like while also allowing for discharging of any contaminants that have entered labyrinth L. 
     Discharge surface  50  may form an integral part of elastomeric element  10  and line cylindrical mounting portion  8   a  inside sealing device  1 . Discharge surface  50  may further lie on a conical surface that tapers towards sleeve  6  and is open towards tub  110 . Because discharge outlet  50  is a stationary surface, it facilitates the sliding of contaminants towards passage M. 
     In various embodiments, elastomeric element  12  that is integral with screen  9  may further include a sealing lip L 3  arranged inside discharge chamber C 1  and upstream of sealing lips L 2  along sealing labyrinth L. Sealing lip L 3  may extend towards discharge surface  50  and may be inclined at an inclination opposite an inclination of discharge surface  50 , defining a “collector.” This collector may accumulate contaminants that may penetrate inside sealing device  1  through passage M, including by means of adhesion to surfaces of the components of sealing device  1 , and seep into chamber C 1  inside which they will tend to accumulate. The lip L 3  may therefore accumulate and/or collect contaminants, preventing the further advancing movement thereof along the labyrinth L. By increasing the number of barriers at the entrance into sealing device  1 , sealing device  1  may more effectively prevent introduction of contaminants into sealing device  1  and also make labyrinth L more winding. 
     Sealing lip L 3  extends from portion  9   b  in a vicinity of end  51  and has a projecting length greater than a projecting length of sealing lips L 1  and L 2 . Sealing lip L 3  may extend as far as possible towards discharge outlet  50  such that a free end L 3   e  is in a vicinity of end  51  and such that sealing lip L 3  passes along a majority of chamber C 1 . Sealing lip L 3  may extend such that a distance between free end L 3   e  and discharge surface  50  is on the order of tenths of millimeters. This avoids potential sliding contact and subsequent friction while at the same time improving the sealing capacity of sealing device  1 . 
     Lip L 3  may be radially defined by two conical surfaces L 3   s  and L 3   i , where surface L 3   s  faces axis A and surface L 3   s  faces away from axis A. Surface L 3   s  thus acts as a slide for any contaminants moving along labyrinth L towards passage M. 
     The effects of lip L 3 , of lips L 1  and L 2 , of the winding form of labyrinth L, of discharge outlet  50 , and of the interrelationship resulting from the positions of these components may be considered in combination with each other and also in their successive mutually superimposed arrangement, for purposes of both achieving an effective sealing action and an effective discharge capacity of sealing device  1 . 
     In various embodiments, each free end L 2   e  of each lip L 2  may be arranged as close as possible to each respective surfaces L 1   i  of lips L 1  defining a very small free space between them on the order of tenths of a millimeter. Similarly, each free ends L 1   e  of each lip L 1  may be arranged as close as possible to each respective surface L 2   s  of each lip L 2  and to surface L 3   s  of lip L 3  defining a very small free space on the order of tenths of a millimeter. 
     Because lips L 1  and L 2  may be arranged inside chamber C 2 , namely inside a radially intermediate part communicating with the chamber C 1 , the spaces between L 1  and L 2  may be even smaller than the space between lip L 3  and discharge outlet  50 . 
     For purposes of increasing the barriers preventing any contamination of the bearing  2 , the screen  8  or the elastomeric element  10  integral therewith may be provided with a sliding annular sealing lip  11 . The annular sealing lip  11  is arranged inside the chamber C 2  and in sliding contact with the cylindrical portion  9   a  of the screen  9 . The sliding sealing lip  11  extends from an inner radial end  60  of the flange portion  8   b  of the screen  8  and has a thickness with dimensions greater than the dimensions of a thickness of the lips L 1  and L 2  since it must exert a radial pressure on the cylindrical portion  9   a  with a controlled value precisely because of its form. 
     Finally, as described above, it is clear that, because lips L 1  and L 2  are arranged in positions so close to each other, almost intersecting each other, and lip L 3  is also arranged in a position very close to discharge outlet  50 , namely elastomeric element  10  and elastomeric element  12  are arranged very close to each other because of the small axial dimensions of sealing device  1 , the absolutely precise mounting of screens  8  and  9  is required. Therefore, annular screen  9  may include a shaped stop edge  70  formed at a free end of flange portion  9   b  so as to define a precise position of sealing device  1  along drive shaft  7  and with respect to the sleeve  6 . Elastomeric element  10  further include a cylindrical mounting portion  80  connected to cylindrical portion  8   a  and may be internally keyed with interference inside sleeve  6 , axially against bearing  2  of sleeve  6  so as to define a precise position of annular screen  8  with respect to annular screen  9 . This ensures the correct positioning of lips L 1  and L 2  with respect to each other. 
     In particular, assembly of sealing device  1  may be performed by keying with interference of screen  8 , or rather cylindrical mounting portion  80  inside sleeve  6 , and arranging screen  8  with its flange portion  8   b  in axial abutment against bearing  2 . Whereas screen  9  is slid axially along drive shaft  7  until shaped stop edge  70  engages against shoulder  7   a  of drive shaft  7 , which determines the mounting by means of interference of cylindrical mounting portion  9   a  onto drive shaft  7 . Once screen  9  is positioned, drive shaft  7  is inserted inside bearing  2 , causing the gradual axial movement of screens  8  and  9  towards a mounting position where lips L 1  and L 2  are arranged spaced from each other in accordance with the description provided herein. 
     It is worth mentioning that annular screen  9  may be designed so that cylindrical portion  9   a , which is intended to perform an anchoring action, is directed towards radially inner ring  4  of bearing  2  and that shaped stop edge  70 , which has a substantially frustoconical shape, opens outwards towards axis A so that annular sliding sealing lip  11  may slide over it and, likewise, may also slide on a radially outer surface  9   a   1  of cylindrical portion  9   a  without any possibility of bending back onto itself. 
     In various embodiment of sealing device  1  shown in  FIG.  1   , elastomeric element  10  and elastomeric element  12  are provided with three lips L 1 , L 2 , each for obtaining the required sealing efficiency. Advantageously, the three lips L 1  and the three lips L 2 , as well as the lip L 3 , are non-contacting annular sealing lips, the axial dimensions of which are optimized so as to make the labyrinth L as long and as winding as possible and as axially narrow as possible. At the same time, annular sealing lips L 1 , L 2  are sized such that they do not contact each other, which could result in leakages due to friction. 
     With sealing device  1  disclosed herein, a series of advantages may be obtained and the objects predefined by the present disclosure may be achieved. 
     Firstly, the leakages due to friction are reduced and therefore significant savings in energy are achieved. Compared to the known solutions, which use two and in some cases three contacting lips, the number of contacting lips for sealing device  1  disclosed herein is reduced to one contacting lip. The sealing performance is essentially ensured by the winding labyrinth and therefore is not related to the contact force of the sliding lip, thereby helping reduce the leakages due to friction. 
     Secondly, by taking advantage of a substantially intersecting arrangement of lips L 1  and L 2  and the “gutter” effect of lip L 3 , sealing device  1  is able to achieve a significant reduction in the axial volume, of about less than half compared to other known solutions. This results in maximization of the axial space available for washing tub  110 , and therefore an increase in the loading capacity of the drum of washing machine  100 . 
     Thirdly, the optimized form of the labyrinth L, which is very long and very narrow due to the number and dimensions of sealing lips L 1  and L 2 , is able to fully exploit the sealing action offered by sealing device  1 , and guarantee an excellent sealing performance. 
     Finally, mounting of the sealing device is simplified because it is very precise, as the bearing unit and the shoulder of the drive shaft serve as locating points, and because it does not require further machining of other components. 
     In addition to the exemplary embodiments of the disclosure described herein, it will be understood by a person of ordinary skill in the art that there exist numerous other variants. It will also be understood that these embodiments are only examples and do not limit either the scope of the disclosure, its applications, or its possible configurations. On the contrary, although the description above allows a person skilled in the art to implement the present disclosure at least according to one exemplary embodiment, it will be understood that many variants of the components described are possible, without thereby departing from the scope of the disclosure, as defined in the accompanying claims, interpreted literally and/or in accordance with their legal equivalents.