Patent Publication Number: US-6336246-B1

Title: Door mounting mechanism and assembly for door opening-closing with movements at right angles

Description:
DESCRIPTION 
     The invention applies to the field of furniture. 
     So-called coplanar door units are well known and widely used for closing openings on furniture or as doors used in various living environments. Coplanar doors, when in a closing position, generally have their main surfaces lying on a same vertical plane and opening of a passageway closed by the doors is carried out by pushing back one of the doors and therefore sliding it behind a second door which remains stationary, or vice versa by drawing or pulling one of the doors and sliding it over the other door which remains temporarily stationary. Movement may be applied to either of the coplanar doors. For aesthetic and practical reasons it is desired that each door is kept parallel to itself in its closing position, in its intermediate retracted or extracted position, and in its opening position n when it overlaps a second door. 
     A coplanar door movement mechanism of four-bar linkage type is already known. This mechanism includes a carriage movable for a horizontal traverse parallel to the door plane, and two parallel connecting rods or links assembled on the carriage and supporting a door. To open the door, the user pushes it from its steady closed position to its retracted (respectively extracted) intermediate position, then slides it behind or before, respectively, a second door held stationary. Since, during a first movement step, the carriage stays still, the first door, passing from its steady closed position to its retracted or respectively extracted position, moves along a circular are round the connecting rod fulcrums on the carriage. Such are motion, although of limited extent, is undesirable since it means that a relatively wide clearance is needed between a door&#39;s vertical edge and a fixed structure facing it, and because it means that a door must be bevelled so as not to interfere with an adjacent door. 
     An aim of the invention is to achieve an opening/closing coplanar door movement that produces a straight shifting of the door between its closing position and its intermediate retracted or extracted position and vice versa, i.e. in which each vertical door edge substantially moves in a plane. 
     An additional aim is to realize such a device that keeps the door parallel to itself in every position. 
     An additional aim of the invention is to realize a device of limited bulk, that may be hidden from view by the furnishing portions whereon it is assembled and that is easy to assemble as a single item. 
     Such aims have been reached with a mechanism as said in claim  1  and an assembly as said in claim  10 . Additional new and useful characteristics are said in the following claims. 
     The mechanism of the invention includes a pair of levers or connecting rods arranged as a four-bar linkage, each assembled by a pivot on a sliding carriage, and a compensator unit to make the carriage slide, each time the connecting rods are rotated to retract or extract the door, carried on them, by an extent that is equal and opposite to the extent of the projection, on a carriage track, of an arc travelled by the door. The compensator unit is generally of cam type. More particularly, the compensator unit includes at least a slider which is moved by a tab extending from a connecting rod of the four-bar linkage, each connecting rod forming a first class lever. The slider is longitudinally movable along the carriages for a length and at one end thereof has a movement control lever engaging a cam recess in a mechanism stationary structure with a cam roller. A spring between the slider and the carriages biases the mechanism to its stable condition with the connecting rods or links in a condition in which the door is in the closing position. The mechanism can be enclosed in a thin casing that internally forms a cam part and the sliding track for the carriages. 
     Each door is preferably assembled on a said mechanism at its upper edge and on another said mechanism at its lower edge, the carriage unit of the mechanism preferably occupying a lengthwise extension of no more than half the door width. Preferably the upper and lower mechanismns are interconnected with at least one bar which is rigidly secured to a connecting rod of the upper mechanism and a corresponding connecting rod of the lower mechanism to ensure a consistent shifting of both mechanisms and a door movement wherein the door is always parallel according to vertical planes. 
     The new device achieves the above mentioned aims, particularly allows each door of a set of coplanar doors to move parallel to itself along perpendicular axes. Moreover, it is of compact construction. It could be entirely factory built, with only simple mounting operations required for assembly to a door and the item of furniture or the structure of which the door is part. 
    
    
     An exemplary unrestrictive embodiment of the invention will be described in the following with reference to the enclosed figures in which: 
     FIG. 1 is a front elevational view of a coplanar door item of furniture, drawn in a reduced scale; 
     FIG. 2 is a broken-away, top plan view of the item of furniture in FIG. 1, with a covering plate partially removed, and shown enlarged with respect to FIG. 1; the doors thereof are drawn with a continuous line in their coplanar closing position, a door is drawn in dash lines in an intermediate retracted position, ready to be moved sideways for opening; 
     FIG. 3 is a vertical sectional view along  3 — 3  in FIG. 2; the doors are shown in an opening position, in which one of the doors is moved behind the other; 
     FIG. 4 is a top plan view of the invention mechanism; the mechanism is shown in an embodiment thereof suitable for assembly of a lefthand door of a coplanar door pair and is shown in its stable closing position; an upper plate of a mechanism casing has been removed to expose the underlying parts; 
     FIG. 5 is a similar illustration to FIG. 4, but the mechanism is shown in a retracted door position ready for sliding open; a door closed position is shown by the dash lines; 
     FIG. 6 is an exploded top plan view of the mechanism. 
    
    
     With reference to first FIG. 1, a pair of coplanar doors is shown fitted to an item of furniture or wardrobe. The item of furniture is referenced  1  as a whole and the doors have the references  2  and  4 . The exposed faces of doors  2  and  4  lie on a same vertical plane when the doors are in a position in which they cooperate to close a front opening of the piece of furniture or wardrobe. 
     Although the explanation given here, as an example, refers to wardrobe doors, the use of coplanar door pairs to close openings or passageways of different kinds is known. 
     Wardrobe  1  basically includes lateral uprights  5 ,  6 , a base panel  7 , a covering or upper panel  8 . The coplanar doors  2  and  4  are assembled to close a front opening defined by panels  5 ,  6 ,  7  and  8 . A movement mechanism or device for the doors, according to the invention, is referenced  10  in the figures. As shown in FIG. 3, a mechanism  10  is assembled on top of, and a mechanism  10  at the bottom of panel  8  and panel  7 , respectively. 
     The device or mechanism  10  will be explained in detail with reference to FIGS. 4,  5 , and  6 . With reference first to FIG. 4, a door  2  is shown interrupted in its closing position. Said door includes a peripheral frame  2 , and, on an exposed part thereof, a panel  22 . However, the invention is also applicable to solid wooden doors. The mechanism  10  includes a fixed box-like structure or casing  12 , that has a C-shape in sectional view as seen in FIG. 3, and internally forms a first and second sliding track,  14  and  17 , horizontally extended and parallel along the width of the opening to be closed by the doors. Track  14  is defined by walls  15 ,  16 , of which  16  is of reduced height. A second track  17  is defined between walls  18  and  19  of reduced height. The tracks can be defined in the internal lower surface of the box-like structure  12  or in the upper surface thereof, or both. 
     The box-like structure  12  further has coupling means  12 ′ for coupling to the panel, in any form. 
     The mechanism  10  includes a carriage unit  20 , comprising a pair of carriages  22 ,  22   a , made integral with each other by a rod  23 . The carriage unit length preferably does not exceed half the door width. Since the two carriages  22 ,  22   a  are preferably identical, a description of only one of them will follow, since such a description is also applicable to the other (the parts of which are denoted by reference numbers corresponding to those of the corresponding parts of the first carriage with the letter a, and they will not be described). Carriage  22  has a pair of vertical axis movement guide wheels  24 ,  24  and horizontal axis movement guide wheels  25 ,  25  on one side and  26  on the other side. Wheel  26  is preferably arranged between the two wheels  24 . This arrangement provides for travel of carriage  22  alone the longitudinal direction (the direction of the opening width), with wheels  24 ,  26  engaging track  14 , wheels  25  engaging track  17 . The carriage has a seat  28 , defining an axis  29  whereon a connecting rod or lever element  30  is rotatably assembled with an eyelet or bearing  31  thereof. Lever  30  and lever  30   a  are pivoted with their other respective distal pivots  32 ,  32   a  of arms  34 ,  34   a  on door frame  2   1 . Each carriage can be completed with a covering plate  34 ,  34   a  that is assembled to cover the respective carriage seat  28 ,  28   a.    
     From lever  30 , respectively  30   a  in opposite position to arm  33 , respectively  33   a  with respect to the fulcrum of  31  ( 31   a ) i.e. axis  29 ,  29   a , extends a tab  36 ,  36   a  which will be discussed later. 
     A compensator unit referenced  40  as a whole includes a pair of sliders,  42  and  42   a , respectively. The sliders  42 ,  42   a  are preferably identical, are made of cut metal sheet, and are symmetrically arranged with respect to a vertical plane (FIG.  6 ). Only slider  42  will be described, and the description there of also o applies to slider  42   a , whose elements carry corresponding references to those of slider  42 , but with the letter a. The slider  42  ( 42   a ) is bar-shaped and has two end lugs  45  ( 45   a ) and  46  ( 46   a ), respectively. Lug,  45 , (respectively  45   a ) has an elongated slot  47 , respectively  47   a , lug  46 ,  46   a  has through hole  48 , respectively  48   a . A left end (in the figures) of slider  42  ( 42   a ) has an elongated slot  50  ( 50   a ). In it s intermediate position the slider has a through hole  51  ( 51   a ) and an additional elongated slot  52  ( 52   a ) and further through holes  53  ( 53   a ). The two sliders  42 ,  42   a  are made integral to each other by a rod  55 , fixed to the holes  53 ,  53   a.    
     Slider  42  is applied to carriage  22  with the possibility of longitudinal sliding along it by means of slots  50 ,  52  engaging pegs  27 ′,  27 . “Longitudinal” means the lengthwise direction of tracks  14 ,  17 , which is the direction of the door width. Slider  42  is bound to the tab  36  of connecting rod or lever  30 , at hole  51 , and slider  42   a  is bound to the tab  36   a  of connecting rod-lever  30   a . The tabs  36 ,  36   a  cause the compensator unit to move rightwards, as shown in the figures, for a clockwise rotation of levers  30 ,  30   a.    
     A spring  60  between a tab  21  of the carriage  22  and lug  46  of the slider urges the carriage unit  20  and the compensator unit  40  to a retracted condition. 
     The compensator unit  40  further includes a control/movement lever or cam means  70 , that includes a triangular plate  71  with an idle roller  72 . Plate  71  rotatably engages a peg  27 ′, of the carriage  22  and has its peg  73  received in slot  47  of slider  42 . The axes of roller  72 , peg  27 ′ and peg  73  are arranged at the vertices of a triangle. 
     When the mechanism is assembled, roller  72  engages a cam recess or groove  74  of the structure  12  for a sliding movement. The cam recess  74  is in communication with track  14  and, for a retracting door, has its axis inclined, from said track  14 , towards the front and side of the mechanism. If it is desired to have door  2  assembled for an extraction opening movement so that it can slide open before adjoining door  4 , the cam recess  74  inclination will be 90° with respect to the position shown in the drawings, i.e. extended from the track  14  in a sidewards direction and towards the wardrobe&#39;s rear portion. The shape of cam groove  74  is designed to offset exactly, if possible, the projection of the travel of pivot  32  of lever  30  in the door plane, upon rotation of the levers  30 ,  30   a , and, if possible, during each moment of the travel. 
     That is to say: assume that l 33  is the distance between axes a 31 , a 32  of bearing  31  and pivot  32  of the connecting rod-lever  30 , and a straight line joining the two axes in the plane of FIGS. 4 and 5, forms and angle α in the extended door condition and an angle β in the retracted door condition with a vertical plane through axis of  31 ; should the carriages be held stationary, door  2 , passing from its coplanar condition to its retracted condition, would undergo a leftwards shift of: l 33  COS β−l 33  cos α, and, at each intermediate moment, a shift equal to l 33  cosγ−l 33  cos α with β&lt;γ&lt;α. The collaboration of the cam system of roller  72  and recess  74  is such as to ensure, at all times, a rightwards shift or travel x=1 33  COS γ−l 33  COS α, with γ varying between α and β. 
     The operation of the mechanism will now be described in more detail. Door  2  with its frame  2   1  is assembled on pivots  32 ,  32   a  of an upper mechanism  10  and on similar pivots of a similar lower mechanism. A rigid bar (not shown) connects corresponding pivots, for instance,  32 , of the two mechanisms. The bar is rigidly secured to the corresponding connecting rods  30 ,  30   a  next to the fulcrum or pivots  32 , so that the connecting rods turn of a same angle. A rigid connection of bar and connecting rod is well within the reach of a person skilled in the art and therefore is not explained further. In its rest condition, shown in FIG. 4, spring  60  keeps the compensator unit in a retracted condition on the carriage unit; lever  30  and lever  30   a  of the four-bar linkage are in an extended condition in which door  2  is in its closing position, coplanar to adjacent door  4 ; roller  72  is at an end of recess  74 . To open the door  2 , the user pushes it, causing it to slide backwards parallel to itself until the condition shown in FIG. 5, and thus causes the levers  30 ,  30   a  to turn around their respective pivots, hence forcing the tabs  36 ,  36   a  to slide the compensator unit rightwards, as in the figures, against the action of spring  60 . The sliding of the compensator unit rightwards drags the triangular plate  71  of the movement control lever  70  forcing the same to turn around the pivot  27 ′. The wheel  72  travels along cam recess  74  following a path defined by the recess walls, and forces the slider units bound thereto to shift rightwards. The shift is transferred to the carriage unit  20 , through the tabs  36 ,  36   a . Door  2  in the retracted condition in FIG. 5 can slide behind door  4 . The retracted condition of door  2 , for its entire longitudinal travel, is maintained by means of roller  72  engaging Track  14 . 
     The operation of the mechanism will now be described in more detail. Door  2  with its frame  2   1  is assembled on pivots  32 ,  32   a  of an upper mechanism  10  and on similar pivots of a similar lower mechanism. A rigid bar (not shown) connects corresponding pivots, for instance,  32 , of the two mechanisms. The bar is rigidly secured to the corresponding connecting rods  30 ,  30   a  next to the fulcrum points  32 , so that the connecting rods turn of a same angle. A rigid connection of bar and connecting rod is well within the reach of a person skilled in the art and therefore is not explained further. In its rest condition, shown in FIG. 4, spring  60  keeps the compensator unit in a retracted condition on the carriage unit; lever  30  and lever  30   a  of the four-bar linkage are in an extended condition in which door  2  is in its closing position, coplanar to adjacent door  4 ; roller  72  is at an end of recess  74 . To open the door  2 , the user pushes it, causing it to slide backwards parallel to itself until the condition shown in FIG. 5, and thus causes the levers  30 ,  30   a  to turn around their respective pivots, hence forcing the tabs  36 ,  36   a  to slide the compensator unit rightwards, as in the figures, against the action of spring  60 . The sliding of the compensator unit rightwards drags the triangular plate  71  of the movement control lever  70  forcing the same to turn around the pivot  27 ′. The wheel  72  travels along cam recess  74  following a path defined by the recess walls, and forces the slider units bound thereto to shift rightwards. The shift is transferred to the carriage unit  20 , through the tabs  36 ,  36   a . Door  2  in the retracted condition in FIG. 5 can slide behind door  4 . The retracted condition of door  2 , for its entire longitudinal travel, is maintained by means of roller  72  engaging track  14 . 
     For closing movement, door  2  is slid leftwards until roller  72  enters the recess or groove  74 , which allows rotation again, this time anti-clockwise, of levers  30  around the respective pivots under the action of spring  60 . 
     It will be noticed that the device could easily be adapted for doors of various width simply by choosing rods  23  and  55  of suitable size. 
     Although the device has been described with particular reference to a lefthand door of retracting coplanar doors, with the same parts arranged in an identical way, it could easily be adapted for a righthand door. Besides, with appropriate modifications of groove  74 , the device could be adapted to extraction opening coplanar doors.