Abstract:
A drive device for a movable furniture part includes an ejection device which can be locked in a locked position, the ejection device being used to move the movable furniture part from a closed position into an open position. The ejection device can be unlocked by pushing the movable furniture part so that the movable furniture part moves into a pushed-in position which is beyond the closed position in a closing direction, this enables the ejection device to move the movable furniture part in an opening direction; and the movable furniture part can also be moved from the closed position into the open position by pulling the movable furniture part, the ejection device remaining in the locked position when opened by pulling. The drive device also includes a coupling device for coupling the drive device to the movable furniture part or to a furniture body.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention concerns a drive device for a furniture part movable in a furniture carcass, comprising an ejection device lockable in a locked position for moving the movable furniture part from a closed position into an open position, wherein the ejection device is unlockable by over-pressing the movable furniture part into an over-pressing position which is behind the closed position in a closing direction, whereby the movable furniture part is movable by the ejection device in an opening direction, wherein the movable furniture part is also movable from the closed position into the open position by pulling on the movable furniture part, wherein the ejection device remains in the locked position upon opening by pulling, and a coupling device for coupling the drive device to the movable furniture part or to the furniture carcass. The invention further concerns an article of furniture having such a drive device. 
     2. Description of Related Art 
     So-called touch latch mechanisms have already been known for many years in the furniture fitting industry, in which an ejection device is unlocked by pressing against the movable furniture part which is in the closed position, whereupon the movable furniture part (for example, a drawer or a furniture flap) is ejected in the opening direction. 
     In simple touch latch mechanisms of a different general kind, the ejection device is disposed anywhere on the furniture carcass and ejects the movable furniture part at least during the first opening travel. There is no coupling device for coupling the drive device to the movable furniture part. Rather, there is only an abutment surface against which the movable furniture part directly or indirectly bears. If, in the case of such a drive device, instead of over-pressing the movable furniture part, the movable furniture part is simply pulled starting from the closed position, then the movable furniture part is lifted away from the abutment surface without triggering a movement in the drive device. 
     Conversely, in WO 2012/149587 A1, which is also of a different general kind, a coupling device remains in a coupling position upon ejection of the movable furniture part whereas, however, the locking device with the cardioid-shaped guide path is no longer in the locking position when opening the movable furniture part by pulling. Rather, there is provided an evasion passage by which the locking pin can evasively pass through the “heart” of the cardioid when opening by pulling. The locking position is therefore preserved upon opening by pulling. 
     In WO 2011/015663 A1, which relates to a different general kind of device, the coupling position between the drive device and the movable furniture part or furniture carcass is also maintained in the same fashion upon opening by pulling, but unlocking of the lockable ejection device is implemented both upon unlocking by over-pressing and also upon unlocking by pulling. 
     In comparison, WO 2009/114886 A1, disclosing a device of the general kind set forth herein, discloses a kind of overload protection device in which the ejection device remains in a locking position upon opening by pulling (see FIG. 30 c ). The catch fork, however, is pivoted against the force of a spring by a pin associated with the furniture carcass whereby the drive device is no longer coupled to the furniture carcass upon opening by pulling. A disadvantage with that structure is that, upon such opening by pulling, the drive device has to be unlocked upon reclosing the furniture part so that it is only after that that the pin can be coupled to the catch element again. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of the present invention is to provide a drive device which is an alternative or which is improved over the state of the art. In particular, the invention seeks to avoid the disadvantages of the state of the art defining the general kind of drive device involved here. 
     That is achieved by a drive device having features described herein. In accordance therewith, it is provided that the coupling device is in a coupling position upon ejection of the movable furniture part by the ejection device, wherein the coupling device is movable loosely with respect to the ejection device upon opening by pulling. Accordingly, the coupling device remains in a coupling position at least portion-wise upon opening by pulling and the coupling device can be movable free of a spring loading of an overload spring. In addition, no unlocking has to be effected upon reclosing as, when the furniture part is pushed in, the components of the coupling device can be simply coupled together again. 
     The “loose” movement of the coupling device with respect to the ejection device can be defined in other words by stating that, upon opening by pulling, the coupling device is movable independently of the ejection device. To put it another away, the coupling device is not connected to the ejection device upon opening by pulling. In that case, the coupling device can be movable with a translatory component with respect to the drive device, wherein, for example, the coupling device is movable without a spring loading in a linear portion of a guide path. 
     Basically it can be provided that the coupling device is in a coupling position during the entire opening travel of the movable furniture part. It is, however, preferably provided that, upon opening by pulling, the coupling device remains in the coupling position only in a first opening travel portion which is in front of the closed position in the opening direction. In that case, the first opening travel portion can be between 10 mm and 100 mm, preferably between 20 mm and 70 mm, in length. 
     It is particularly preferably provided for the loose movement that the coupling device has a transmission abutment, by way of which the coupling device bears against a triggering abutment of the ejection device in the closed position and in an over-pressing region between the closed position and the over-pressing position, whereas upon opening by pulling the transmission abutment lifts away from the triggering abutment or moves away therefrom so that there is no longer any contact between the transmission abutment and the triggering abutment. 
     In an embodiment of the invention, it can be provided that the drive device has a base plate. It is particularly preferably provided in that respect that the ejection device has a preferably cardioid-shaped guide path in the base plate, an ejection slider which is movable preferably linearly along the base plate, a locking lever mounted pivotably to the ejection slider, a locking pin mounted to the locking lever and displaceable in the guide path and an ejection force storage means fixed on the one hand to the base plate and on the other hand to the ejection slider. With such a structure, basically, the triggering abutment can be provided on any component, for example, on the ejection slider of the ejection device. It is preferably provided, however, that the triggering abutment of the ejection device is on the locking lever. 
     In addition, in a preferred embodiment of the invention, it can be provided that the coupling device has a coupling slider displaceable at least portion-wise linearly in the base plate and a catch element mounted movably, preferably pivotably, on the coupling slider, for a coupling entrainment portion arranged on the furniture carcass or on the movable furniture part, wherein the coupling slider and the catch element are displaceable along a portion-wise linear guide path in the base plate, having an angled end portion. It is preferably provided in that case that the transmission abutment of the coupling device is provided on the coupling slider. 
     In order to integrate not just the function of active ejection by over-pressing into the drive device, the drive device can preferably also have a retraction device for retraction of the movable furniture part from an open position into the closed position. For coupling the retraction device to the furniture carcass or to the movable furniture part, it can be provided in that case that the retraction device can be brought into engagement by way of a retraction catch element with a retraction entrainment portion which is separate from the coupling entrainment portion. 
     If the ejection device and the retraction device of the drive device form a common structural unit, it is preferably provided that the retraction device can be at least portion-wise coupled to the coupling device by way of the retraction catch element and upon opening by pulling a retraction force storage means of the retraction device can be stressed along the first opening travel portion. Thus, the coupling device is in the coupling position, upon retraction by the retraction device. 
     Basically, however, the retraction device and the ejection device do not have to be in the form of a structural unit. Rather, it can also often happen that a drive device according to the invention is to be retrofitted in already existing movable furniture parts or in extension guide assemblies. In that case, for example, retraction devices which each have a retraction entrainment portion are already provided in the extension guide assemblies. Accordingly, in that case, only the ejection device has to be retrofitted, in which case then two separate entrainment portions (retraction entrainment portion and coupling entrainment portion) are provided for making the connection or coupling between the drive device and the furniture carcass or the movable furniture part. 
     An article of furniture may have a furniture carcass, a furniture part movable relative to the furniture carcass and a drive device according to the invention for the movable furniture part. In that respect it can, in principle, be provided that the drive device is disposed on the furniture carcass and a coupling entrainment portion is associated with the movable furniture part. In a preferred embodiment, however, it is provided that the drive device is disposed on the movable furniture part, wherein the coupling device has a coupling entrainment portion which is associated with the furniture carcass and which can be brought into engagement with the catch element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further details and advantages of the present invention are described more fully hereinafter by means of the specific description with reference to the embodiments by way of example illustrated in the drawings in which: 
         FIG. 1  diagrammatically shows an article of furniture with movable furniture parts in various positions, 
         FIG. 2  shows a movable furniture part from below with a drive device, 
         FIG. 3  shows an exploded view of a drive device, 
         FIG. 4  shows the drive device in the closed position, 
         FIG. 5  shows the drive device in the over-pressing position, 
         FIG. 6  shows the drive device upon ejection, 
         FIG. 7  shows the drive device after termination of the ejection process, 
         FIGS. 8( a ) and 8( b )  show the drive device with ejection device and retraction device in the closed position, 
         FIGS. 9( a ) and 9( b )  show the drive device upon opening by pulling, and 
         FIGS. 10( a ) and 10( b )  show the drive device after termination of opening by pulling. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows an article of furniture  14  comprising a furniture carcass  2  and a plurality of movable furniture parts  3  in the form of drawers. Viewed from above downwardly, the drawers are in an open position OS, then in an open position OS which is further moved in the closing direction SR, then in the closed position SS and right at the bottom in the over-pressing position ÜS. In general, it is to be stated that the movable furniture part  3  comprises a drawer container  24  and a front panel  25 . Each movable furniture part  3  is supported movably on the furniture carcass  2  by way of an extension guide assembly  28 . In that respect, the extension guide assembly  28  has a drawer rail  26 , a carcass rail  27 , and optionally, a central rail (not shown). In addition, a diagrammatically indicated retraction device  19  can be provided, for example, between the drawer rail  26  and the carcass rail  27 . The drive device  1  has an ejection device  4  which, in this case, is associated with the movable furniture part  3 . As essential components, the ejection device  4  has the base plate  8  fixed to the movable furniture part  3  or to the drawer rail  26 , the cardioid-shaped guide path  9  in the base plate  8 , the ejection slider  10  mounted movably on the base plate  8 , the locking lever  11  mounted pivotably to the ejection slider  10 , the locking pin  12  which is mounted to the locking lever  11  and which is displaceable in the cardioid-shaped guide path  9  and the ejection force storage means  13  which is braced between the ejection slider  10  and the base plate  8 . In addition, the ejection device  4  is coupled to the furniture carcass  2  by way of a coupling device  5  and the coupling entrainment portion  16 . 
     The coupling entrainment portion  16  is also visible in  FIG. 2 , being mounted to the carcass rail  27  by way of the entrainment plate  30 . The drive device  1  itself is mounted to the drawer bottom  29  of the movable furniture part  3  by way of the base plate  8  or a cover  31 . 
     It will be seen from the exploded view in  FIG. 3  that the cardioid-shaped guide path  9  is provided in the base plate  8 . In that case, the guide path  9  as an important component has the latching region  33 . A depth adjusting wheel  32  is also rotatably mounted on the base plate  8 . The ejection slider  10  of the ejection device  4  is mounted linearly displaceably along the guide path  43  on the base plate  8 . The ejection force storage means  13 , which is in the form of a tension spring, is braced between the ejection slider  10  and the base plate  8  by way of the spring base  37  and the spring base  38 . The locking lever  11  is mounted pivotably to the ejection slider  10  by way of the rotary mounting  35 , the rotary pin  34  and the rotary mounting  36 . 
     Arranged on the locking lever  11  is the locking pin  12  which is displaceable in the guide path  9  in the base plate  8 . The triggering abutment  7  is also provided on the locking lever  11 . In matching relationship therewith, the transmission abutment  6  is provided on the coupling slider  14 . The catch element  15  is mounted pivotably to the coupling slider  14  by way of the axis of rotation X. The coupling slider  14  and the catch element  15  are mounted displaceably by way of the guide pins  39  and  40  in the guide path  17  in the base plate  8 . The guide path  17  has an angled end portion  18  for the guide pin  39 . The coupling slider  14  and the catch element  15 , jointly with a coupling entrainment portion  16  which is not shown in  FIG. 3 , form the coupling device  5 . The drive device  1  is closed with a cover  31  which can be fixed to the base plate  8 . 
       FIG. 4  shows the drive device  1  in a position when the movable furniture part is in the closed position SS. At the same time in the closed position SS, the lockable ejection device  4  is disposed in a locked position V as the locking pin  12  mounted to the locking lever  11  is in the latching region  33  of the guide path  9 . The ejection force storage means  13  is stressed in the locked position V. In addition, the coupling device  5  is in a coupling position K in which the coupling entrainment portion  16  associated with the furniture carcass  2  is held or caught between the coupling slider  14  and the catch element  15 . In the closed position SS, there is contact between the transmission abutment  6  on the coupling slider  4  and the triggering abutment  7  on the locking lever  11 . 
     If now, starting from that position shown in  FIG. 4 , a pressing force is applied to the movable furniture part  3  in the closing direction SR, then the movable furniture part  3  moves into an over-pressing region Ü between the closed position SS and the over-pressing position ÜS, as shown in  FIG. 5 . As the coupling entrainment portion  16  is fixed with respect to the carcass, when the furniture part  3  is over-pressed, the base plate  8  of the drive device  1  is moved in the closing direction SR relative to the coupling entrainment portion  16 . As, however, the coupling entrainment portion  16  is coupled to the coupling device  5 , the coupling slider  14  and by way of the transmission abutment  6  and the triggering abutment  7  also the locking lever  11  are moved relative to the base plate  8  whereby the locking pin  12  on the locking lever  11  is moved out of the latching region  33  of the cardioid-shaped guide path  9 . 
     As soon as that position is reached, the ejection force storage means  13  is no longer locked and the ejection slider can move relative to the base plate  8  into the position of  FIG. 6 . With that movement of the ejection slider  10 , the locking lever  11  and by way of the triggering abutment  7  and the transmission abutment  6  also the coupling slider  14  are also moved. As a result, the drive device  1  bears by way of the coupling device  5  against the coupling entrainment portion  16  and is in an open position OS in which the coupling device  5  is always still in the coupling position K. 
     At the end of the ejection movement, the drive device  1  is in the position shown in  FIG. 7  in which the movable furniture part  3  is still in an open position OS and the coupling device  5  also still remains in the coupling position K. To provide for uncoupling of the coupling device  5 , the movable furniture part  3  is further moved in the opening direction OR either by momentum or by pulling until the catch element  15  passes by way of the guide pin  39  into the angled end portion  19  of the guide path  17  so that the coupling entrainment portion  16  is no longer caught between the coupling slider  14  and the catch element  15 . The ejection force storage means  13  is relieved of stress in the position shown in  FIG. 7 . 
     Such a drive device  1  as shown in  FIGS. 1 through 7  can be easily retrofitted in an existing movable furniture part  3 . In that case, a retraction device  19  can already be disposed, for example, in the region of the extension guide assembly  28 . 
     In order, however, to provide a drive device  1  in the form of a structural unit having an ejection device  4  and a retraction device  19 , attention is directed to the embodiment shown in  FIGS. 8 through 10 .  FIGS. 8 through 10 , in contrast to  FIGS. 4 through 7 , describe and illustrate opening by pulling, wherein naturally such opening by pulling also correspondingly applies for  FIGS. 4 through 7 . Conversely, unlocking by over-pressing as shown in  FIGS. 4 through 7  correspondingly also applies for  FIGS. 8 through 10 . 
     In  FIGS. 8( a ) and 8( b ) , the movable furniture part  3 —like also in  FIG. 4 —is in the closed position SS. In that case, the ejection device  4  is in the locked position V in which the locking pin  12  is locked in the latching region  33  of the guide path  9 . As can be seen from  FIG. 8( b ) , the rear view of the drive device  1  is shown, with the base plate  8  being connected to a base plate member  42  of the retraction device  19 . As essential components, the retraction device  19  has the base plate member  42 , the retraction catch element  20 , the retraction guide path  41  in the base plate member  42  for the retraction guide element  20  and the retraction force storage means  21  which is fixed on the one hand to the base plate member  42  and on the other hand to the retraction catch element  20 . The retraction force storage means  21  is in the form of a tension spring. As a further important component for the retraction device  19 , disposed on the catch element  15  of the coupling device  5  is the retraction entrainment portion  22  which is held in the catch region of the retraction catch element  20 . The coupling entrainment portion  16 , which is separate from the retraction entrainment portion  22 , is held between the catch element  15  and the coupling slider  14 . If—as shown in  FIG. 5 —a pressing force is applied to the movable furniture part  3  in the closing direction SR, the elastic arm  44  of the retraction catch element  20  yields and allows movement of the catch element  15  together with the retraction entrainment portion  22  relative to the retraction catch element  20  in opposite relationship to the closing direction SR as the retraction catch element  20  is already in an end abutment condition in the retraction guide path  41 . The end abutment condition is necessary to also stop the movable furniture part  3  in the closed position upon being retracted by the retraction device  19 , and to not move it further into an over-pressing position US. Nonetheless, movement into the over-pressing position US is to be possible, the elastic arm  44  being provided precisely for that purpose. 
     If now the movable furniture part  3  is not unlocked and ejected by over-pressing, as shown in  FIG. 5 , but opening is effected by pulling on the movable furniture part  3 , the drive device  1  moves into an open position OS as shown in  FIGS. 9( a ) and 9( b ) . It will be seen, in that position, that the ejection device  4  is still in a locking position V. Upon opening by pulling, the base plate  8  is moved in the opening direction OR relative to the coupling entrainment portion  16  which is fixed with respect to the carcass. As the coupling device  5  is coupled to the coupling entrainment portion  16  by way of the catch element  15  and the coupling entrainment portion  14  and is thus in a coupling position K, the triggering abutment  7  is lifted away from the transmission abutment  6 , whereby upon opening by pulling, the coupling device  5  moves loosely with respect to the ejection device  4 . The retraction force storage means  21  is also stressed with that opening movement along the first opening travel portion W, as on the one hand the spring base  45  moves by way of the base plate member  42  with the base plate  8  in the opening direction OR, but on the other hand the retraction force storage means  21  is coupled by way of the spring base  46  and the retraction catch element  20  to the retraction entrainment portion  22  provided on the catch element  15 . As soon as the angled end portion  47  of the retraction guide path  41  is reached, the retraction catch element  20  pivots so that the retraction catch element  20  is uncoupled from the retraction entrainment portion  22 , as shown in  FIGS. 9( a )  and ( 9   b ). At the same time, however, the coupling device  5  is still in the coupling position K with the coupling entrainment portion  16 . In that position, as shown in  FIGS. 9( a ) and 9( b ) , the retraction force storage means  21  is stressed again. 
     With a further movement of the movable furniture part  3  in the opening direction OR, the drive device  1  passes into the position shown in  FIGS. 10( a ) and 10( b ) , in which the coupling slider  14  and, in particular, the catch element  15  have also reached the angled end portion  18 , in which the coupling position K is cancelled, whereby the coupling entrainment portion  16  is no longer held. The ejection device  4  is still in the locked position V. 
     The present invention thus provides a drive device  1  in which the coupling device  5  is freely movable upon opening by pulling in relation to the ejection device  4 . In that way, the ejection device  4  can remain in the locked position V upon opening by pulling. At the same time, however, upon closing, the appropriate coupling position K of the drive device  1  is immediately restored.