Patent Publication Number: US-8985717-B2

Title: Hinge assembly for household appliances having an horizontally-pivoted front door

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a national stage application, filed under 35 U.S.C. §371, of International Application No. PCT/EP2011/066370, filed Sep. 21, 2011, which claims priority to European Patent Application No. 10014483.1, filed Nov. 11, 2010, both of which are hereby incorporated by reference in their entirety. 
     BACKGROUND 
     The present invention relates to a hinge assembly for household appliances having an horizontally-pivoted front door. 
     More specifically, the present invention relates to a hinge assembly for a home dishwasher having an horizontally-pivoted front door, and to a front-loading dishwasher provided with such hinge assembly, implementation to which the following description refers purely by way of example without implying any loss of generality. 
     As is known, today&#39;s front-loading dishwashers generally comprise a substantially parallelepiped-shaped, outer casing which is structured for resting on the floor, and is provided with an inner washing chamber which communicates with the outside through a substantially rectangular crockery loading/unloading opening formed in the vertically-oriented front wall of the casing; a substantially rectangular-shaped front door which is pivotally-jointed to the front wall of the casing via two lateral hinge assemblies structured to allow free rotation of the door about a horizontally-oriented rotation axis which is located immediately beneath the access opening to the washing chamber; and usually two dish-racks which are housed inside the washing chamber one above the over, and are fixed to the inner surface of the washing chamber in drawer-like manner so to be manually extractable from the washing chamber through the crockery loading/unloading opening on front wall of the casing. 
     More specifically, the two hinge assemblies are located on opposite sides of the front door, close to the lower horizontal edge of the door, and are aligned one another so as to allow manual rotation of the door about the door rotation axis, between a raised position in which the front door is oriented substantially vertically and rests completely against the front wall of the casing to close the crockery loading/unloading opening and watertight seal the washing chamber, and a lowered position in which the front door is oriented substantially horizontally, beneath the crockery loading/unloading opening, so as to give the user free access to the washing chamber via the crockery loading/unloading opening. 
     Each hinge assembly of currently marketed front-loading dishwashers usually comprises: a first coupling plate which is substantially perpendicular to the front-door rotation axis and is structured for being firmly fixed to a corresponding vertical lateral wall of the casing, immediately adjacent the crockery loading/unloading opening of the front wall; a second coupling plate which is structured for being firmly fixed to the door side body, and is pivotally jointed to the first coupling plate so as to be able to rotate about the door rotation axis, between a first working position wherein the front door of the dishwasher is arranged in the raised position, and a second working position wherein the front door of the dishwasher is arranged in the completely lowered position; and finally a door-weight balancing device which is interposed between the first and the second coupling plate and it is structured for elastically hampering rotation of the second coupling plate with respect to the first coupling plate from the first to the second working position, so as to get a very slow lowering of the front door. 
     Additionally, several models of hinge assembly currently on the market are also structured so as to allow an on-site adjustment of the hampering effect of the door-weight balancing device, according to the actual weight of the front door. This solution avoids an on-site replacement of the standard hinge assemblies when a particularly heavy covering panel is firmly fixed to the front door of the dishwasher to hide the household appliance. This problem is typical of built-in front-loading dishwashers and similar household appliances. 
     Hinge assemblies having an on-site adjustable door-weight balancing device are disclosed in DE3140039 and EP1602883. 
     The main drawback of the hinge assembly disclosed in DE3140039 is that the on-site adjustable door-weight balancing device is too complicated to tune up because the user is requested to act on two distinct adjusting mechanisms, namely the front screw and the internal sleeve, and only one of these adjusting mechanisms is directly accessible from the front wall of the casing. 
     The main drawback of the hinge assembly disclosed in EP1602883 is that the on-site adjustable door-weight balancing device is structured to allow only a few step-by-step discrete adjustments of the hampering effect of the door-weight balancing device. Moreover the elastic member of the on-site adjustable door-weight balancing device is a tensile-stressed helical spring which traditionally has a non linear response to loads, with all problems concerned. 
     BRIEF SUMMARY 
     Aim of the present invention is to realize a hinge assembly for front-loading dishwashers which allows a continuous adjustment of hampering effect of the door-weight balancing device via a single adjusting mechanism directly accessible from the front wall of the casing. 
     In compliance with the above aims, according to the present invention there is provided a hinge assembly as specified in Claim  1  and preferably, though not necessarily, in any one of the dependant claims. 
     Moreover, according to the present invention, there is also provided a household appliances as specified in Claim  11  and preferably, though not necessarily, in any one of the dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       A non-limiting embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  shows a lateral view, with parts removed for clarity, of a front-loading dishwasher provided with a couple of hinge assemblies realized in accordance with the teachings of the present invention; 
         FIG. 2  shows a front view, with parts in section and parts removed for clarity, of one of the two hinge assemblies of the  FIG. 1  dishwasher; 
         FIG. 3  shows a front view of the  FIG. 2  hinge assembly in a different operative configuration; 
         FIG. 4  show an isometric view of a component part of the  FIG. 2  hinge assembly; whereas 
         FIG. 5  shows a front view of an alternative embodiment of the  FIG. 2  hinge assembly with parts in section and parts removed for clarity. 
     
    
    
     DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS 
     With reference to  FIG. 1 , number  1  indicates as a whole a hinge assembly specifically structured for being used in a household appliance  2  having an horizontally-pivoted front door, such as a stand-alone or built-in, front-loading dishwasher or a stand-alone or built-in, gas or electric oven. 
     In the example shown, in particular, reference is made to a built-in front-loading dishwasher  2  which preferably, though not necessarily, comprises:
         a substantially parallelepiped-shaped, rigid outer casing  3  which is structured for being stably fitted into a piece of kitchen furniture (not shown) and/or for resting on the floor, and is provided with a preferably, though not necessarily, substantially parallelepiped-shaped, inner washing chamber which communicates with the outside through a preferably, though not necessarily, substantially rectangular-shaped, crockery loading/unloading opening realized in the substantially vertically-oriented, front wall  3   a  of outer casing  3 ; and   a preferably, though not necessarily, substantially flat and rectangular-shaped, front door  4  which is pivotally-jointed to front wall  3   a  of outer casing  3  via two reciprocally aligned hinge assemblies  1  (only one is shown in  FIG. 1 ) which are located on opposite sides of front door  4 , so to allow free rotation of front door  4  about a substantially horizontally-oriented rotation axis A which lays on or extends locally substantially parallel to the front wall  3   a  of casing  3 , immediately beneath the crockery loading/unloading opening.       

     More specifically, the two hinge assemblies  1  are preferably located on opposite sides of front door  4 , close to the lower horizontal edge of the door, and are aligned one another so as to allow manual rotation of front door  4  about axis A, between a raised position in which front door  4  is oriented substantially vertically and rests completely against the front wall  3   a  of casing  3  to close the crockery loading/unloading opening and watertight seal the washing chamber; and a completely lowered position in which front door  4  is oriented substantially horizontally, beneath the crockery loading/unloading opening, so as to give the user free access to the washing chamber via the crockery loading/unloading opening on front wall  3   a.    
     With reference to  FIG. 1 , alike today&#39;s front-loading dishwashers, dishwasher  2  preferably, though not necessarily, also comprises one or more dish-racks  5  (only one is shown in  FIG. 1 ) which are housed inside the washing chamber preferably, though not necessarily, one above the other, and each of which is structured for housing the crockery to be washed and is preferably, though not necessarily, fixed to the inner surface of the washing chamber in drawer-like manner so to be manually extractable from the washing chamber through the crockery loading/unloading opening on front wall  3   a.    
     Casing  3 , front door  4 , and dish-racks  5  are commonly known parts in the dishwashers technical field and therefore won&#39;t be described in further details. 
     With reference to  FIGS. 1 ,  2  and  3 , each hinge assembly  1  comprises:
         a first coupling plate  6  which is structured for being firmly fixed to a corresponding lateral wall  3   b  of outer casing  3 , immediately adjacent to lower horizontal edge of the crockery loading/unloading opening on front wall  3   a , so as to lay on a reference plane locally substantially perpendicular to the door rotation axis A;   a second coupling plate  7  which is substantially parallel to coupling plate  6 , is pivotally jointed to coupling plate  6  via a transversal pin  8  extending coaxial to a reference axis R locally substantially perpendicular to both coupling plates  6  and  7 , and it is finally structured for being firmly fixed to the body of front door  4  so that reference axis R of transversal pin  8  is locally substantially coincident to door rotation axis A, thus to be able to rotate about axis R, i.e. about the door rotation axis A, between a first working position (shown in solid line in  FIG. 3 ) wherein front door  4  is arranged in the raised position, and a second working position (shown in dotted line in  FIG. 3 ) wherein front door  4  is arranged in the completely lowered position; and   a door-weight balancing device  9  which is interposed between coupling plates  6  and  7  and is structured for elastically hampering rotation of coupling plate  7  with respect to coupling plate  6  at least from the first to the second working position, so to almost completely balance the overall weight of front door  4  for significantly slowing down or event stop the gravity movement of front door  4  from the raised position to the completely lowered position.       

     The door-weight balancing device  9 , in turn, comprises: a straight supporting rod  10  which is coaxial to a longitudinal axis L substantially parallel to coupling plate  6  (i.e. supporting rod  10  lays on a plane substantially perpendicular to the door rotation axis A), and extends in axially sliding manner through a transversally protruding tailpiece  11  which juts out from coupling plates  6 ; a compression-preloaded helical spring or similar elastically-deformable tubular member which is fitted to supporting rod  10  so as to have a first end  12   a  rigidly fixed to the distal end  10   a  of supporting rod  10 , and a second end  12   b  in abutment against the protruding tailpiece  11  of coupling plate  6 , so that axial movement of supporting rod  10  varies the length of helical spring  12 ; and a linking mechanism  13  which connects the proximal end  10   b  of supporting rod  10  to coupling plate  7 , at a given distance from reference axis R of transversal pin  8  (i.e. from door rotation axis A), so that supporting rod  10  is axially moved with respect to protruding tailpiece  11  to further compress helical spring  12  when coupling plate  7  rotates from the first to the second working position, and returns to its maximum length when coupling plate  7  rotates back to the first working position. 
     With reference to  FIGS. 2 and 3 , differently from currently marketed hinge assemblies, the door-weight balancing device  9  additionally comprises an adjustable spacer element  14  which is interposed between the protruding tailpiece  11  and the second end  12   b  of helical spring  12 , and which is structured so as to allow a manually-operated continuous adjustment, between a lower value and a higher value, of the distance h between the protruding tailpiece  11  and the second end  12   b  of helical spring  12 . 
     In other words, being the first end  12   a  of helical spring  12  rigidly fixed to the distal end  10   a  of supporting rod  10 , the adjustable spacer element  14  directly increases or reduces the actual maximum length of helical spring  12  on supporting rod  10  and, therefore, it allows a manually-operated continuous adjustment of the compression preload of helical spring  12  between a lower value and a higher value. 
     In the example shown, in particular, the linking mechanism  13  preferably comprises a movable guide member  15  which is fixed in sliding manner onto coupling plate  6 , approximately between protruding tailpiece  11  and transversal pin  8 , so as to be substantially aligned to supporting rod  10  on opposite side of tailpiece  11  with respect to spacer element  14 , and so as to be freely movable onto coupling plate  6  towards and backwards the protruding tailpiece  11  in a direction locally substantially parallel to the rod longitudinal axis L. The movable guide member  15  is moreover directly faced to, and rigidly connected to, the proximal end  10   b  of supporting rod  10  so as to move axially the supporting rod  10  with respect to protruding tailpiece  11 . 
     In addition to the above, the linking mechanism  13  also comprises a substantially flat, connecting arm or rod  16  which extends on a plane locally substantially perpendicular to reference axis R, and has a first end  16   a  directly hinged to coupling plate  7  at a given distance from pin  8 , and a second end  16   b  hinged to guide member  15 , so that the whole connecting arm  16  is able to both freely move above coupling plate  6  towards and backwards the protruding tailpiece  11  in a direction locally substantially parallel to the rod longitudinal axis L, and to freely rotate with respect to coupling plate  7  and guide member  15  while remaining on a plane locally substantially perpendicular to reference axis R of transversal pin  8 . 
     In other words, connecting arm or rod  16  connects coupling plate  7  to guide member  15  so to transform the rotating movement of coupling plate  7  about reference axis R, i.e. the rotating movement of front door  4  about door rotation axis A, into an axial reciprocating movement of supporting rod  10  through protruding tailpiece  11 . 
     In the example shown, in particular, guide member  15  preferably, though not necessarily, consists of a substantially flat, transversal rocket arm  17  which extends immediately above coupling plate  6 , approximately between protruding tailpiece  11  and transversal pin  8 , and which has its intermediate section both rigidly connected to the proximal end  10   b  of supporting rod  10 , and pivotally jointed to connecting arm or rod  16 . The two opposite ends of rocket arm  17  are finally hinged each to a respective sliding block  18  which, in turn, is fixed in sliding manner to coupling plate  6  so as to be able to freely slide on the body of supporting plate  6  in a direction locally substantially parallel to the longitudinal axis L of supporting rod  10  and helical spring  12 , towards and backwards protruding tailpiece  11 . 
     In turn, with reference to  FIGS. 2 ,  3  and  4 , the adjustable spacer element  14  comprises two substantially wedge-shaped blocks or bodies  20  and  21  which are piled up roughly aligned to the longitudinal axis L of supporting rod  10 , and are fitted to supporting rod  10  between the protruding tailpiece  11  and the second end  12   b  of helical spring  12 , so that the wedge-shaped block  20  abuts exclusively against the protruding tailpiece  11 , and the wedge-shaped block  21  abuts exclusively against the end  12   b  of helical spring  12 . 
     In the example shown, in particular, a washer or bushing is preferably, though not necessarily, interposed between the second end  12   b  of helical spring  12  and the wedge-shaped block  21 , i.e. the adjustable spacer element  14 . 
     Additionally the two wedge-shaped blocks  20  and  21  are structured so to be able to slide/move one onto the other along a preferably, though not necessarily, straight travelling direction d having a vectorial component parallel to the longitudinal axis L of supporting rod  10 , so that any reciprocal movement of the wedge-shaped blocks  20  and  21  causes a variation of the overall high of the adjustable spacer element  14  parallel to longitudinal axis L and, as a consequence, a variation of the distance h between the protruding tailpiece  11  and the second end  12   b  of helical spring  12 . 
     In the example shown, in particular, travelling direction d is preferably, though not necessarily, locally parallel to coupling plate  6 , and is tilted of an angle α preferably, though not necessarily, ranging between 5° and 85° with respect to the longitudinal axis L of supporting rod  10 . 
     More specifically, travelling direction d is preferably, though not necessarily, tilted of an angle α equal to 30° or 45° with respect to the longitudinal axis L of supporting rod  10 . 
     In addition to the above, adjustable spacer element  14  is provided with a manually-operated adjusting mechanism  22  which is structured so to both prevent any undesired reciprocal movement of the two wedge-shaped blocks  20  and  21 , and to selectively move the two wedge-shaped blocks  20  and  21  one with respect to the other along the direction d, so to permit a continuous manually-operated adjustment of the distance h between the protruding tailpiece  11  and the second end  12   b  of helical spring  12  and, as a consequence, of the actual compression preload of helical spring  12  fitted on supporting rod  10 . 
     With reference to  FIGS. 2 and 3 , in the example shown, in particular, the wedge-shaped block  20  is rigidly fixed to the protruding tailpiece  11 ; and the wedge-shaped block  21  abuts against helical spring  12 , or rather the washer or bushing on the second end  12   b  of helical spring  12 , with a substantially flat upper surface locally perpendicular to the longitudinal axis L of supporting rod  10 , so as to allow the second end  12   b  of helical spring  12  to freely slide on wedge-shaped block  21 . 
     The manually-operated adjusting mechanism  22 , in turn, rigidly connects the wedge-shaped block  21  to the coupling plate  6 , and it is structured so to selectively move the wedge-shaped block  21  with respect to coupling plate  6 , onto the wedge-shaped block  20  along direction d, for alternatively increasing or reducing the overall high of the adjustable spacer element  14  and, as a consequence, continuously adjusting the distance h between the protruding tailpiece  11  and the second end  12   b  of helical spring  12 . 
     More specifically, with reference to  FIGS. 2 ,  3  and  4 , in the example shown wedge-shaped block  20  is preferably provided with a central through cavity dimensioned to allow exclusively axial displacements of supporting rod  10 ; whereas wedge-shaped block  21  is provided with a central through cavity dimensioned to allow both axial and transversal displacements of supporting rod  10  parallel to coupling plate  6 , and rests onto wedge-shaped block  20  on a flat contact surface which lays on a reference plane P locally perpendicular to coupling plate  6  and locally tilted of an angle α preferably, though not necessarily, ranging between 5° and 85° with respect to the longitudinal axis L of supporting rod  10 , so that any transversal movement of wedge-shaped block  21  with respect to supporting rod  10  and wedge-shaped block  20  causes an increase or reduction of the distance h between the protruding tailpiece  11  and the flat upper surface of wedge-shaped block  21  against which the second end  12   b  of helical spring  12  abuts. 
     The adjusting mechanism  22 , in turn, preferably consists of a connecting screw  22  which is fixed in axially rotating manner to coupling plate  6 , beside wedge-shaped block  21 , and extends towards wedge-shaped block  21  while remaining locally parallel to travelling direction d up to reach and screw into the body of the wedge-shaped block  21 , so that any rotation of the connecting screw  22  causes a sliding of the wedge-shaped block  21  onto the wedge-shaped block  20  along direction d and, as a consequence, causes an increase or reduction of the distance h between the protruding tailpiece  11  and the flat upper surface of the wedge-shaped block  21  against which the second end  12   b  of helical spring  12  abuts. 
     General operation of front-loading dishwasher  2  is clearly inferable from the above description, with no further explanation required. 
     As regards hinge assembly  1 , coupling plate  6  is structured for being fixed to the lateral wall  3   b  of outer casing  3  immediately beside the crockery loading/unloading opening on front wall  3   a , so that the head  22   a  of connecting screw  22 , i.e. the manually-operated adjusting mechanism  22 , crops out of front wall  3   a  beside the crockery loading/unloading opening, and it is easily accessible to the user when front door  4  is not in the raised position. The door-weight balancing device  9  therefore allows an on-site, manually-operated adjustment of the compression preload of the helical spring  12  fitted on supporting rod  10 . 
     The particular structure of door-weight balancing device  9  offers several advantages. First of all, the door-weight balancing device  9  allows the user to manually adjust the compression preload of helical spring  12  in a continuous and extremely precise manner, simply acting exclusively on the manually-operated adjusting mechanism  22 , i.e. on the head  22   a  of connecting screw  22 . 
     Moreover, in the door-weight balancing device  9  the adjustment speed of the compression preload of helical spring  12  depends solely on the tilt angle α of the travelling direction d with respect to the longitudinal axis L of supporting rod  10 , thus even a few turns of the connecting screw  22  can cause relevant variation of the helical-spring compression preload. A tilt angle α approximately equal to 45° offers the best compromise between speed and adjustment accuracy of the helical-spring compression preload. 
     In addition to the above, the head  22   a  of the adjusting screw  22  of the on-site adjustable door-weight balancing device  9  is located on the front wall  3   a  of casing  3 , in a raised position which is easy reachable by the user without removing the household appliance from the niche in the kitchen furniture where it is recessed. 
     In other words, the adjusting mechanism of the on-site adjustable door-weight balancing device  9  is located in a raised position which is particularly user friendly. 
     Last but not least, in hinge assembly  1  the on-site adjustable door-weight balancing device  9  is wholly integrated in coupling plate  6 , thus the assembly of hinge assembly  1  on the appliance casing is greatly simplified and cost-effective. 
     Clearly, changes may be made to the household appliance  2  and to hinge assembly  1  as described herein without, however, departing from the scope of the present invention. 
     For example, in a non-shown structural variation of hinge assembly  1 , transversal pin  8  may be replaced by a multilink leverage mechanism which is preferably, though not necessarily, structured to allow a free rotation of coupling plate  7  with respect to coupling plate  6  about a rotation axis locally substantially perpendicular to both coupling plates  6  and  7 , and, at the same time, a transversal displacement of coupling plate  7  with respect to coupling plate  6  in a direction locally perpendicular to said rotation axis. In this case, the door rotation axis A is therefore allowed to space out from front wall  3   a  of outer casing  3  while front door  4  rotates about axis A. 
     Additionally, with reference to  FIG. 5 , in a different embodiment of the adjustable spacer element  14  the wedge-shaped block  20  abuts against the protruding tailpiece  11  with the possibility to slide above tailpiece  11  in a direction locally parallel to coupling plate  6  and preferably, though not necessarily, roughly perpendicular to the longitudinal axis L of supporting rod  10 . 
     The wedge-shaped block  21  instead is fitted to supporting rod  10  exclusively in axially sliding manner, and rests onto the wedge-shaped block  20  on a flat contact surface which lays on a reference plane P locally perpendicular to coupling plate  6  and locally tilted of an angle α preferably, though not necessarily, ranging between 5° and 85° with respect to the longitudinal axis L of supporting rod  10 , so that any transversal displacement of wedge-shaped block  20  with respect to supporting rod  10  obliges the wedge-shaped block  21  to slide onto the wedge-shaped block  20  along a travelling direction d having a vectorial component parallel to longitudinal axis L of supporting rod  10 , thus causing an increase or reduction of the distance h between the protruding tailpiece  11  and the second end  12   b  of helical spring and, as a consequence, an increase or reduction of the compression preload of helical spring  12  fitted on supporting rod  10 . 
     As regards the manually-operated adjusting mechanism  22 , in this embodiment it consists of a connecting screw  22  which is fixed in axially rotating manner to coupling plate  6 , beside the wedge-shaped block  20 , and extends towards wedge-shaped block  20  while remaining locally perpendicular to the longitudinal axis L of supporting rod  10 , i.e. locally parallel to the sliding direction of wedge-shaped block on protruding tailpiece  11 , up to reach and screw into the body of the wedge-shaped block  20 , so that any rotation of connecting screw  22  causes a sliding of the wedge-shaped block  21  onto the wedge-shaped block  20  along the travelling direction d, thus causing an increase or reduction of the distance h between the protruding tailpiece  11  and the second end  12   b  of helical spring  12 . 
     As regards instead the household appliance  2 , one of the two hinge assemblies  1  connecting the front door  4  to the front wall  3   a  of casing  3  may be replaced by a traditional hinge assembly which is either provided with or lacks a corresponding door-weight balancing device.