Patent Publication Number: US-2009229317-A1

Title: Domestic Appliance Having A Detergent Solution Container

Description:
The invention relates to a domestic appliance having a detergent solution container and with at least one ballast weight which is mechanically connected via at least one of its own contact surfaces to at least one contact surface of the detergent solution container. 
     A wide variety of methods are known for attaching ballast weights using friction fits and force fits. Thus ballast weights are notoriously normally fastened by means of screws to the outer walls of detergent solution holders. Since these point-type fastenings have frequently not been satisfactory, the number of connections per ballast weight has increased steadily and yet these connections still take the form of points which, in conjunction with ballast weights made from the brittle material concrete, frequently leads to the formation of cracks between the connection points. In addition this increases the demands to strict tolerances by the plurality of fastening points to be matched in their dimensions to one another. 
     In a similar way connections between plastic detergent solution containers and ballast weights have been created by means of molded-on dowels in which by an injection process (for example through a additional screw screwed in along the extent of the dowel) additional support surfaces have been obtained. However even this form of fastening was unable to satisfy requirements, because the area between the fastening points are still at risk from bending stresses, which the brittle concrete material can often not withstand. 
     Furthermore clamp connections are also employed in which very powerful steel belt clamps take care of holding the ballast weights on the support surfaces of the detergent solution container of a washing machine. Here friction movements between the ballast weight and the support surfaces and wear to said surfaces are deliberately accepted, because the spring force of the clamps always adjusts the connection. A problem however—as with the dowel connection—is the tendency of the plastic of the detergent solution container to become viscous, so that the contact surfaces change their shape over and above the wear, which eventually however can lead to the connection coming apart. 
     Fastenings of ballast weights using a band clamp (DE 196 33 705 A1) have the disadvantage that the band clamp must fully enclose the ballast body. This requires a circular or ring-shaped ballast weight which greatly reduces the freedom of constructional design of detergent solution containers. Since the tensioning band must also enclose lug-type extensions on the detergent solution container, the design of a tool for detergent solution container is very expensive and the lug-type extensions must be shaped in a particular way in order to correspond to the appropriate indentations on the ballast weight. 
     Furthermore the fastening of ballast weights using a plastic welding method is known. DE 693 07 668 T2 thus discloses a washing machine or a combined washer/dryer in which at least one ballast weight is fastened to a detergent solution container made of plastic. The ballast weight features a hollow plastic container, which can be filled with water as ballast material. The plastic container of the ballast weight also has an outer contour which precisely matches and thus makes a form fit with a corresponding structure on the detergent solution container. The plastic container is arranged on the detergent solution container such that the two structures fit tightly into one another and the pairs of the matching structures are permanently connected to each other by welding once joined together. Over and above this, prior art is also known in 693 07 668 T2, in which concrete blocks which are completely enclosed in a plastic envelope are known as ballast weights. Such a plastic envelope is also connected to the detergent solution container by a plastic welding process. Plastic welding processes require complex machines in the production line which make it more expensive to manufacture the detergent solution containers connected to the ballast weights. Also this form of attachment is linked to the use of thermoplastic plastics on both parts—detergent solution container and ballast weight. 
     The object of the present invention is thus to create a domestic appliance of the type stated at the outset, in which a connection between a ballast weight and a detergent solution container can be embodied at low cost and safely. 
     This object is achieved in accordance with the identifier of claim  1  by the contact surface of the ballast weight and of the detergent solution container being glued to each other. 
     An inventive domestic appliance has a detergent solution container with at least one ballast weight that is mechanically connected via at least one of its own contact surfaces to at least one contact surface of the detergent solution container. Inventively the ballast weight is fastened to the detergent solution container by gluing the contact surface of the ballast weight to the contact surface of the detergent solution container, with the mechanical connection being embodied by a glued joint. 
     A major advantage of this connection method is the large-surface or full-surface adhesion between the contact surfaces, in which the stresses for the ballast weight can be widely distributed. This is especially of advantage when used in washing machines, because in such systems in the course of an agitation process, in which the oscillating system consisting of laundry drum and detergent solution container with a number of built-in components (motor, heating, bellows-type collar etc.) is excited into many thousands of vibrations which impose a strain on the attachment elements of the ballast weight. 
     The complete lack of raised areas, which would be used to connect the ballast weight such as by screws for example to the detergent solution container, also allows the manufacturer every possible freedom in the embodiment of the external form of the ballast weight. 
     Depending on the pairing of the two materials to be connected to one another, there are known measures to be taken in general adhesive technology for preparing the gluing. These can be washing the contact surface, treatments which increase adhesion, e.g. through a plasma treatment, of contact surfaces made of plastic, roughening or smoothing by brushing or sanding, application of primers or similar, that are easily able to be integrated into automated assembly processes. 
     Numerous variants described in the subclaims enable the invention to be advantageously further developed. These variants can be used in any possible combination individually or jointly with the gluing in accordance with claim  1 . 
     In such cases the contact surface of the detergent solution container can advantageously be embodied at least in some areas from plastic or metal. In such cases it is useful for the ballast weight to also be able to be fastened to detergent solution containers made of stainless steel or plastic. 
     The ballast weight can be embodied from metal, preferably cast metal, from plastic or from pure concrete. Ballast weights made of metal can be used in particular if the space in the interior of the domestic appliance requires a ballast weight of low volume. 
     An advantageous embodiment of the invention features at least one raised area on the contact surface of the ballast weight or of the detergent solution container which is in contact with an essentially flat area of the contact surface to be connected, with adhesive being deposited in the hollows between the raised parts which extends into the flat area when the parts are glued together in order to prepare the adhesive connection between the contact surfaces. In such cases the raised areas can serve to keep a defined distance between the contact surfaces until the glued connection is hardened. The connection between the ballast weight and the detergent solution container can be made with little effort and yet still safely by using this method. 
     A prior form-fit fitting of the of the ballast weight onto the detergent solution container is not necessary, but can be desirable in order to make it easier to fix the ballast weight into its intended position. Raised areas preferably extend in the direction of the contact surface. 
     The embodiment of the ballast weight as a body made entirely of concrete will be preferred. However armoring within the concrete body can be provided to increase the stability. 
     In an advantageous manner however the ballast weight can be embodied from at least two solid materials, with one material being a plastic. At least one further section of the ballast weight consists of another solid material and is connected to the plastic part. 
     In a preferred manner the second solid material is concrete or a compound containing concrete. This allows a sufficiently heavy ballast weight to be created. Such a ballast weight fastened to the detergent solution container serves to make it heavier and increase the mass inertia and consequently to restrict the vibrations of the detergent solution container during an agitation phase. This is especially advantageous if a washing machine drum rotating in the detergent solution container is filled with an unbalanced load of washing and driven at a relatively high speed. 
     In an advantageous manner the plastic element of the ballast weight is a discrete plastic part which extends partly into the second solid material. In particular there can be provision for the second material to be completely penetrated by the plastic part of the ballast weight. A two-component ballast weight created in this way allows a diversity of embodiments. In particular in such cases these two components can be created in a variety of shapes which can be optimized in respect of the arrangement of the ballast weight on the detergent solution container and available space within the domestic appliance. 
     In an advantageous manner the raised areas are embodied in the form of ribs. However the connecting elements can be designed to assume any other shape which leads to a raised structure of the connection elements by comparison with the remaining part of the contact surface. Thus for example a pin-shaped of point-shaped or cone-shaped embodiment of the raised areas is advantageous. Here too in respect of the requirements of the ballast weight (space requirement, strength, etc.) a shape optimized for the situation concerned can be selected. 
     The plastic part of the ballast weight can feature an undercut. On the one hand this allows the connection of the plastic part to the second solid material of the ballast weight to be improved and on the other hand allows a best possible mechanically-rigid connection with the contact surface of the detergent solution container to be obtained. 
     The raised areas can advantageously be embodied on the detergent solution container and can be glued to the contact surface of the plastic part of the ballast weight. In another variant the raised areas can be embodied on the ballast weight and have adhesive contact with an essentially flat area of the plastic area of the detergent solution container. 
     In an advantageous manner a plurality of raised areas is embodied in the plastic area of the detergent solution container or on the plastic part of the ballast weight, extending essentially in the same direction. This plurality of connecting elements enables a number of contact areas with the plastic area to be connected to be created, enabling the strength of the mechanical connection to be improved. In addition the parts of the adhesive deposited between the raised areas guarantee the distribution of adhesive to all contact areas. 
     There can be provision for the plastic part of the ballast weight to have at least two separate contact surfaces, which are connected by a connection pin. Preferably the connection pin is embodied from plastic. A special form of strengthening is provided however by an armoring wire between the two contact surfaces. 
     There can be provision for the connecting pin and/or the armoring wire to be surrounded in at least some areas by the second material of the ballast weight. For example they can be encapsulated in the second material. This allows a firm connection to be created between the materials and a positionally-stable arrangement of the plastic part to be guaranteed. 
     The ballast weight can advantageously be embodied as a cube or as a part ring. However this does not exclude other shapes of ballast weight. 
     The raised areas are preferably an integral component of the assigned plastic part. This enables the plastic part to be manufactured in one piece with the raised areas. For example the plastic part for the ballast weight can be manufactured by a single injection molding process. 
     In an advantageous manner the domestic appliance is a washing machine or a combined washer/dryer. 
    
    
     
       The invention is explained in greater detail below with reference to a number of exemplary embodiments for the fastening of a ballast weight to a detergent solution container a washing machine. The figures show 
         FIG. 1  a schematic side view of a detergent solution container with a view of the oscillation system provided with a ballast weight, 
         FIG. 2 to 7  a plurality of possible embodiment variants of a ballast weight with plastic parts, the contact surfaces of which are suitable for fastening by means of an adhesive, 
         FIGS. 8 and 9  further exemplary embodiments of ballast weights showing a measure for fastening them to a detergent solution container, 
         FIG. 10  a view onto the contact surface of a ballast weigh with differently-shaped adhesive surfaces, 
         FIG. 11 to 13  arrangements of bead-type adhesive surfaces for adhesives able to handle different loads and 
         FIG. 14 to 21  different variants of the embodiment of bead-type adhesive surfaces. 
     
    
    
     In housing  1  of the washing machine shown in FIG. I a detergent solution holder  2  is supported to allow oscillation of spring-loaded legs  3 . An electric motor  5  drives the laundry drum  6  supported horizontally within the detergent solution container  2  via a belt drive  4 . The laundry drum  6  and the detergent solution container  2  have a common loading opening  9 , through which washing  15  can be introduced into the drum  6  or removed from it and which is sealed by a bellows-type collar  7  from the inner chamber of the housing  1 . The loading can be closed at the front by a door  8 . 
     Since the motor  5  is accommodated at the bottom to the rear on the vibration detergent solution holder system, its large weight must be compensated for on the side lying opposite the center of gravity of the detergent solution holder system. The ballast weight  10  which is fastened to the front side of the detergent solution container  2  above the loading opening  9  is used for this purpose. The ballast weight  10  and the detergent solution container  2  are connected by gluing  133  between the touching contact surface  11  of the ballast weight  10  and  12  of the detergent solution container  2 . 
     The ballast weight  10  is embodied in all exemplary embodiments from two different solid materials. The main component of the ballast weight  10  consists of concrete. The plastic part  13  is used to fasten the ballast weight  10  to the detergent solution container  2  and in the different examples depicted in  FIG. 2 to 9  is connected by form fit or force fit to the concrete part as required. The ballast weight  10  can be embodied as a cube or as depicted in  FIG. 10  in a shaped adapted to the area of application, with the plastic part  13  extending partly into the concrete body or partly surrounding it. Ballast weights in accordance with the invention can also be accommodated at other locations of the detergent solution container or additionally in order to achieve specific weight distributions. 
     In the exemplary embodiment depicted in  FIG. 1  the plastic part  13  is provided with two extensions  131  which project into the concrete body. At the end of the extensions  131  are accommodated limbs  132  pointing outwards, by which undercuts acting in the pulling direction of the ballast body  10  away from the detergent solution container  2  are produced, which make a form fir between concrete body and plastic part. 
     A ballast weight  16  in accordance with  FIG. 1  can however be embodied as in  FIG. 2 . In this case the concrete body can have a shape adapted to the respective area of application, regardless of the form of the plastic part  161 . The plastic part  161  projects with two extensions  162  into the concrete body  163 , which are angled inwards at their ends by limbs  164 , in order once again—in a similar fashion to FIG.  1 —to make form-fit undercuts. 
     A similarity shape is provided for the plastic part  171  in  FIG. 3 , if it is guided around the side facing the detergent solution container with its extensions  172  up to the side walls of the concrete body  173 . Then the arms  174  can penetrate from the side into the concrete body and in this way make a form fit. 
     The contact surfaces  165  or  175  of the ballast weight  16  or  17  in accordance with  FIG. 2 . or  FIG. 3  are provided for receiving adhesive for the connection with the detergent solution container  2  with recesses in Form of channels  166  or  176 . Before the ballast weight is joined to the intended contact surface  12  ( FIG. 1 ) of the detergent solution container  2  the channels  166  or  176  are filled so much with adhesive mass so that when the contact surfaces are pressed together adhesive mass is pressed onto the raised part of the contact surface  12 . The pressing is ended one the raised areas located between the recesses rest against the opposing contact surface. The volume of the channels is naturally kept as small as possible so that no more adhesive mass is used than is absolutely necessary. It is also possible to provide indentations to accept adhesive in the contact surface  12  of the detergent solution container  2 . In such a case the contact surfaces  165  or  175  of the ballast weight  16  or  17  are preferably embodied as smooth surfaces. 
     It is also possible, instead of the channels, to provide indentations with a large volume, with the adhesive mass not completely filling such recesses. Even after the ballast weight is completely pressed onto the detergent solution container complete filling of the recesses with the pressed adhesive mass is not absolutely necessary. 
     With suitable peripheral conditions (application technique, adhesive preparation, material selection and nature of the adhesive) it is also possible to dispense entirely with such channels and to provide a completely level surface  185  on ballast weight  18  ( FIG. 4 ), which in the exemplary embodiment shown here is applied to a plastic part  181  fully enclosing the concrete body  183 . Instead this type of level contact surface can also be applied to a plastic part which is constructed in another way, e.g. as shown. Spacing raised areas can however also be made outside the contact surface intended for gluing. Such raised areas can have large support surfaces. 
       FIG. 5  shows a further exemplary embodiment in which the undercuts difficult to make in casting technology can be entirely dispensed with. To this end the inner friction-fit connections are relied on which are made between the surface of the concrete body  193  and the plastic part  191  by the inlay injection molding process. The plastic part  191  of the ballast weight  19  has a plurality of extensions  192  for this purpose which penetrate into the concrete body  193 , so that the total friction forces produce a sufficiently large retaining force for the concrete body  193  on the glued plastic part  191 . The plastic part  191  has a completely level contact surface  195 . 
     The plastic part  201  of the ballast weight  20  in  FIG. 6  can also provide on the side facing the detergent solution container  2  a greater deposit area for the adhesive mass and for example be convex or concave on its contact surface  205 . Only two arms or larger dimension extending into the concrete body  203  then hold the ballast weight  20  on the plastic part  201 . The parts of the arms  204  protruding from the concrete body  203  once again serve to retain the spacing against the contact surface  12  on the detergent solution container  2 . This form will be selected above all if the inclusion of a larger mass of adhesive is of advantage for adhesion. 
     A completely different construction, which still comes within the framework of the invention, is provided for the ballast weight  21  in  FIG. 7 . A tubular plastic part  211  with two retaining flanges  212  is then used, the tubular part of which is fully encapsulated by the concrete body  213 . The tubular part can have any possible regular or irregular cross-section, e.g. a cross shape or a multi-sided column shape. 
     In  FIGS. 8 and 9  two further variants for the embodiment of the ballast weight  80  or  90  are used to show two methods for applying a glued connection. The concrete body  803  of the ballast weight  80  in  FIG. 8  has a recess into which the plastic part  801  also penetrates with a hollow cone  808 . This recess together with a cone  128  on the contact surface  12  of the detergent solution container  2  adapted in its shape for the purpose, ensures that no transversal movements are possible between the ballast weight  80  and the contact surface  12  on the detergent solution container  2 . Shear forces can thus not have any effect in the adhesive connection. The adhesive connection between the contact surface  805  of the plastic part  801  and the contact surface  12  of the detergent solution container  2  is also reinforced by the fact that the cone  128  is additionally glued to the hollow cone  808 . In this way the forces acting on the glued connection in different directions are captured and distributed. 
     The gluing of the plastic part  901  anchored in the concrete body  903  is to be seen accordingly, in that two or more adhesive beads  127  are provided on the contact surface  12  of the detergent solution holder  2  and the ballast weight  90  is subsequently pressed with its contact surface  905  against the contact surface  12  of the detergent solution container  2 . 
     To manufacture the adhesive connection—as merely indicated in FIGS.  8  and  9 —a number of adhesive beads are laid onto one of the contact surfaces, e.g. the (12) of the detergent solution holder  2 , and thereafter the ballast weight  89  or  90  is pressed onto the detergent solution holder until the adhesive has hardened sufficiently. The best positioning of the adhesive bead can be determined by trial and error and be executed automatically by machine in the series manufacturing process. In the example shown in  FIG. 8  it is also recommended that the cone  128  be glued to the hollow cone  808 . To accelerate hardening a hardening accelerator can be added to the adhesive. The adhesive surfaces are to be cleaned or pre treated before the gluing process so that inner contact between the adhesive and the respective surface to be glued is produced. 
     The size of the overall adhesive surface between the plastic part  161 ,  171 ,  181 ,  191 ,  201 ,  211 ,  801  or  901 , especially the recesses  166  or  176  or  206  and the contact surface  12  of the detergent solution holder  2  can vary and be embodied as a function of the forces created by the loading, e.g. the forces created during agitation. 
     In the view of the surfaces to be glued shown in  FIG. 10  the ballast weight  10  is embodied in an arc shape. The surfaces to be glued  101 ,  102 ,  103  or  104  can be circular, rectangular, annular and cover a part of the width of the ballast weight  10  or cover the entire width of the ballast weight. These surfaces can only represent the surfaces to be glued on the plastic part  13  of the ballast weight  10  or can directly form the surfaces of the plastic part. Individual surfaces can also be connected by bars  105  or armorings not shown, with bars also able to be implemented with or without armoring. 
     The different embodiments of the ballast weight  10  thus allow a very wide diversity of shapes to be designed which are embodied from two solid materials. As well as cost-effective concrete only relatively simple plastic parts are needed which are to be inserted into the mold during the manufacturing of the concrete parts. This enables a simple embodiment of the overall ballast weight to be implemented, even if the shapes of the contact surfaces  11  on the ballast weight  10  or  12  on the detergent solution container  2  are complex in their embodiment. A cost-effective implementation of the ballast weight can also be guaranteed by the choice of material. 
       FIG. 11 to 13  show how simple variation of the size of the surfaces to be glued allows the gluing to be adapted to later mechanical loading. The figures show views on the front side of a detergent solution container  2  for a front-loading washing machine. The almost closed annular contact surface  12  of the detergent solution container  2  encircles the loading opening  9 . The ballast weight  10  applied to this front side is shown by the dashed lines. 
       FIG. 11  shows a two-sided arrangement of adhesive beads  117  in the upper area of the ballast weight  10 . The adhesive bead  117  applied relative shortly before the pressing together of the contact surface of the ballast weight  10  and of the detergent solution container  2  is for example dimensioned for gluing intended to withstand forces between the detergent solution container  2  and the ballast weight  10 , as occur for agitation speeds of the laundry drum  6  supported in the detergent solution container  2  of 900 rpm. 
     The gluing will resist correspondingly greater forces if the adhesive beads  127  are dimensioned longer, as shown in  FIG. 12 . In this case forces as would occur at 1200 rpm might be resisted. Very long adhesive beads  137  in accordance with  FIG. 13  are configured for forces, as occur at 1500 rpm. 
     In accordance with the different requirements which are produced by various peripheral conditions such as material pairing between ballast weight and adhesive as well as adhesive and detergent solution container for example or also the type and the size of the forces acting on the gluing, different forms can be employed when the adhesive bead(s) is/are applied.  FIG. 14  shows the simplest form as a single-row adhesive bead  147 ,  FIGS. 15 and 18  on the other hand shown two parallel adhesive beads  157  or  187 . By contrast these adhesive beads can deliberately not run in parallel, if for example part of the adhesive surfaces demand a thicker adhesive in relation to other adhesive surfaces. Thicker or thinner application of adhesive can also be controlled by the adhesive bead(s)  167  or  197  in accordance with  FIGS. 16 and 19  being interrupted and/or the adhesive bead(s)  177 ,  207  or  217  in accordance with  FIG. 17 ,  20  being laid in waves or zig-zag lines. 
     The variants shown in  FIG. 18 to 21  also show that any square ballast weights can be fastened to correspondingly shaped contact surfaces in entirely the same manner as by annular ribs by adhesive beads  187 ,  197 ,  207  and  217  with a straight main direction. 
     The adhesive mass, depending on the above-mentioned different requirements can also be applied in another form, for example adhesive can be applied in U-shaped beads. In addition a point-form or surface application of the adhesive mass is also conceivable. 
     The gluing process enables a fast and safe connection to be made with the glue connections easily able to be established by a simple automated system. The glued connection are able to be realized both for a ballast weight attachment to surfaces of a face or sleeve or a floor of the detergent solution container. In addition the glued connections are suitable for oscillating systems with a high agitation speed since the load can be introduced over a large surface into the respective component, so that the tension per surface element in the mechanical connection is very small. In this case the proposed measures can be applied in the same way to detergent solution containers made from stainless steel and for ballast weights made from pure concrete or from cast metal. In an advantageous manner the adhesive masses, preferably consisting of a polyurethane or of a silicon and the volumes of the adhesive masses dictated by the geometrical requirements compensate for the uneven thermal expansions of the different materials and also from frequent changes of load, during the agitation in a washing machine for example. 
     LIST OF REFERENCE SYMBOLS 
       1  Domestic appliance
   2  Detergent solution container
 
       3  Damper 
       4  Belt drive
   5  Electric motor
 
       6  Drum 
       7  Bellows-type collar 
       8  Door 
       9  Loading opening
   10  Ballast weight
   11  Contact surface of ballast weight  10     12  Contact surface of detergent solution container
   13  Plastic part
 
       14  Washing 
       15  Ballast weight
   16  Ballast weight
   17  Ballast weight
   18  Ballast weight
   19  Ballast weight
   20  Ballast weight
   21  Ballast weight
   80  Ballast weight
   90  Gluing surface
   102  Gluing surface
   103  Gluing surface
   104  Gluing surface
 
       105  Bars 
       117  Adhesive bead
   127  Adhesive bead
   128  Cone on contact surface  12   
       131  Extensions 
       132  Limb 
       133  Gluing 
       147  Adhesive bead
   157  Adhesive bead
   161  Plastic part of ballast weight  16     162  Extensions of plastic part  161     163  Concrete body of ballast weight  16     164  Limb of the plastic part  161     165  Contact surface of ballast weight  16     166  Channels (recesses) of plastic part  161     167  Adhesive bead
   171  Plastic part of ballast weight  17     173  Concrete body of ballast weight  17     174  Limb of the plastic part  171     175  Contact surface of ballast weight  17     176  Channels (recesses) of plastic part  171     177  Adhesive bead
   181  Plastic part of ballast weight  18     183  Concrete body of ballast weight  18     185  Contact surface of ballast weight  18     198  Adhesive bead
   191  Plastic part of ballast weight  19     192  Extensions of plastic part  191     193  Concrete body of ballast weight  19     195  Contact surface of ballast weight  19     197  Adhesive bead
   201  Plastic part of ballast weight  20     202  Rails of plastic part  201     203  Concrete body of ballast weight  20     204  Side rails of plastic part  201     205  Contact surface of ballast weight  20     206  Recess of plastic part  201     207  Adhesive bead
   211  Plastic part of ballast weight  21     212  Retaining flanges of plastic part  211     213  Concrete body of ballast weight  21     215  Contact surface of ballast weight  21     217  Adhesive bead
   801  Plastic part of ballast weight  80     803  Concrete body of ballast weight  80     805  Contact surface of ballast weight  80     808  Hollow cone of plastic part  801     901  Plastic part of ballast weight  90     903  Concrete body of ballast weight  90     905  Contact surface of ballast weight  90