Patent Publication Number: US-2016242542-A1

Title: Furniture drive

Description:
The present invention concerns a furniture drive for ejecting a moveable furniture part from a closed end position relative to a furniture carcass, including:
         a housing,   an electric drive unit arranged in or on the housing,   an ejection lever which can be driven by the electric drive unit for transmitting a movement to the moveable furniture part,   wherein the ejection lever on the one hand is mounted rotatably about an axis of rotation and on the other hand has a free lever end, wherein between the axis of rotation and the free lever end the ejection lever has an ejection surface.       

     In addition, the invention concerns an arrangement having a furniture drive of the kind to be described and a force transmission device for transmitting a force to the furniture part to be ejected. 
     AT 504 838 B1 discloses a furniture drive having a motor-driven ejection lever, wherein in the mounted position, the ejection surface of the ejection lever loosely bears against a pushrod in the closed end position of the moveable furniture part. The pushrod forms a part of a force transmission device, wherein the force exerted during the ejection process can be transmitted to the moveable furniture part by way of an intermediate space formed between the ejection lever and the moveable furniture part. In that way, even moveable furniture parts which project into the furniture carcass only to a very slight extent or even not at all (furniture doors, furniture flaps or drawers, the depth of which is substantially less than the depth of the furniture carcass) can be ejected from the closed end position. 
     In the known furniture drives having an ejection lever, the ejection surface of the ejection lever bears loosely against the furniture part to be ejected or against a force transmission portion. Transmission of the movement in the ejection process is thereby effected in a force-locking relationship by way of the ejection surface being slidingly supported against the moveable furniture part or the force transmission portion, wherein a relatively low level of efficiency can be achieved due to the occurring slippage. 
     The object of the present invention is to provide a furniture drive of the general kind set forth in the opening part of this specification, with an improved force transmission possibility. 
     According to the invention, that is achieved by the features of claim 1. Further configurations of the invention are recited in the appendant claims. 
     According to the invention, it is provided that the ejection surface of the ejection lever at least region-wise has a tooth arrangement. 
     The provision of a tooth arrangement at the ejection surface of the ejection lever makes it possible to provide for a positively locking transmission of force, whereby substantially higher forces can be transmitted in comparison to a force-locking transmission. The positively locking transmission permits slippage-free, angularly accurate transmission of the rotary movement of the ejection lever with a high level of efficiency. 
     In an embodiment, it can be provided that the tooth arrangement of the ejection lever has at least one curved portion. In that case, the tooth arrangement can be of such a configuration that, upon ejection of the moveable furniture part from the closed end position (that is to say when the electric drive unit only slowly starts), a high transmission of force with a low travel transmission is provided. In that way, a particularly high level of torque is available when starting from the closed end position so that even heavily loaded drawers can easily be ejected from the closed end position. The transmission ratio can then decrease, starting from the closed end position of the moveable furniture part, over a predetermined range of rotary angular movement of the ejection lever so that the force transmission decreases and the travel transmission increases. 
     The tooth arrangement of the ejection lever can at least portion-wise be in the form of an eccentric tooth arrangement. More specifically, when using such an eccentric tooth arrangement, variable torque configurations can be implemented with a constant drive output from the electric drive unit. While, when using gear transmissions with a constant transmission ratio, the entire tooth arrangement as well as the electric drive unit must always be designed in relation to the maximum torque occurring, in the case of an eccentric tooth arrangement with a variable transmission, the required drive torque pattern can be optimized in accordance with a constantly low drive moment. The eccentric transmission can be in the form of a rotatable gear transmission or also in the form of a tooth segment. 
     In accordance with an embodiment, the tooth arrangement is connected in a motionally coupled relationship to the ejection lever or, alternatively, the tooth arrangement is made in one piece together with the ejection lever. The tooth arrangement can be connected, for example, in the form of a fitment portion to the ejection lever, or alternatively, the tooth arrangement can be in the form of an inherent part of the ejection lever. Production of such an ejection lever is easily possible, for example by way of an injection molding process. 
     In a further embodiment, the ejection lever can be designed to be variable in length by the arrangement of the tooth arrangement, wherein the length of the ejection lever is adjustable by way of an adjusting device. Alternatively, to increase the length of the ejection lever, the tooth arrangement can be fitted in the form of a fitment portion onto the ejection lever, preferably onto the free end thereof. 
     For reducing the production of noise, the tooth arrangement and/or a counterpart tooth arrangement cooperating with the tooth arrangement can be at least region-wise provided with a sound-damping coating. 
     The arrangement according to the invention is characterized by a furniture drive of the kind described and by a force transmission device, the tooth arrangement of the ejection lever cooperating with a counterpart tooth arrangement of the force transmission device. In that case, the counterpart tooth arrangement can be provided on a gear, a gear portion, a toothed lever, a pulley or on a toothed belt of the force transmission device. 
    
    
     
       Further details and advantages of the present invention will be apparent from the exemplary embodiments illustrated in the Figures in which: 
         FIG. 1  shows a perspective view of an article of furniture including a furniture carcass and a furniture part mounted moveably relative thereto, 
         FIGS. 2 a , 2 b    show the furniture drive and a force transmission device in the mounted position to the furniture carcass and as a perspective view, 
         FIG. 3  shows an exploded view of the furniture drive and the force transmission device, 
         FIGS. 4 a -4 d    show perspective views showing the time sequences of the ejection process of the moveable furniture part starting from the closed end position, 
         FIGS. 5 a -5 d    show a plan view, showing the time sequences of the ejection process of the moveable furniture part starting from the closed end position, and 
         FIG. 6  shows a further embodiment of a furniture drive, wherein the ejection lever is made in one piece together with a tooth arrangement. 
     
    
    
       FIG. 1  shows a perspective view of an article of furniture  1  having a furniture carcass  2  and a furniture part  3  moveable relative thereto. In the illustrated embodiment, the moveable furniture part  3  is in the form of a door which is pivotally mounted about a vertical axis relative to the furniture carcass  2 . A furniture drive  4  and a force transmission device  5  for transmitting a force to the moveable furniture part  3  are mounted on the cabinet top  7  of the furniture carcass  2 , wherein the moveable furniture part  3  can be ejected from the closed end position by way of a moveably mounted pushrod  6 . For that purpose, the moveable furniture part  3  projects above the cabinet top  7  of the furniture carcass  2  so that the rear side of the moveable furniture part  3  forms an abutment surface for the extendable pushrod  6 . 
       FIG. 2 a    shows an enlarged view of the furniture drive  4  arranged on the furniture carcass  2 , and the force transmission  5 , as shown in  FIG. 1 . The furniture drive  4  is mounted to a base plate  8  to be fixed to the furniture carcass  2  and includes a housing  9  in which an electric drive unit  10  having a transmission for driving an ejection lever  12  is arranged. The ejection lever  12  is pivotally mounted relative to the housing  9  about an axis of rotation which preferably extends vertically in the mounted position. Triggering of the electric drive unit  10  can be effected by means of sensors which detect a (closing) movement of the moveable furniture part  3 , produced manually by a user. Simple triggering capability for the furniture drive  4  is afforded by a Touch-Latch functionality. For that purpose, it can be provided that a sensor, preferably a rotary potentiometer, is provided for detecting the angular position of the ejection lever  12 , wherein the signals of the sensor can be fed to an open-loop or closed-loop control unit of the furniture drive  4  and the electric drive unit  10  can be controlled or regulated by of the open-loop or closed-loop control unit. The ejection lever  12  has an ejection surface  14  which is arranged between the axis of rotation  11  and the free end  13  of the ejection lever  12  and which is provided with a tooth arrangement  15  for a positive transmission of force. In the illustrated embodiment, the tooth arrangement  15  is pivotally and coaxially mounted with respect to the axis of rotation  11  of the ejection lever  12  and is connected thereto in a motionally coupled relationship so that, upon a pivotal movement of the ejection lever  12 , the tooth arrangement  15  also moves therewith. The tooth arrangement  15  of the ejection lever  12  is at least portion-wise in the form of an eccentric tooth arrangement so that a variable torque can be transmitted to the moveable furniture part  3 . The force transmission device  5  includes a counterpart tooth arrangement  16  which is connected to the pushrod  6  and which cooperates with the tooth arrangement  15  of the ejection lever  12 . The pushrod  6  is mounted linearly displaceably—preferably along a guide  17 —relative to the base plate  8 , wherein in the illustrated Figure, a slider  27 , which is connected to the pushrod  6 , having a guide element  18  in the form of a rib is mounted displaceably along the guide  17 . 
       FIG. 2 b    shows a perspective view of the furniture drive  4  with the cooperating force transmission device  5 . Abutments  19  and  20  which are preferably resilient are provided to delimit the inner end position of the ejection lever  12  and to delimit the inner end position of the slider  27 . The moveable furniture part  3  can be held in the fully closed position and/or can be moved into the fully closed position towards the end of the closing movement by a closing retaining device  21 . The closing retaining device  21  includes at least two parts, a first part  22  being arranged or provided on the pushrod  6  and a second part (not shown) being arranged or provided on the moveable furniture part  3 , wherein the part  22  in the closed position of the moveable furniture part  3  exerts a magnetic attraction force on the part corresponding on the moveable furniture part  3 . The part  22  in the form of a magnet is mounted moveably relative to the pushrod  6  in a transverse direction relative to the longitudinal direction of the pushrod  6 , in particular in a horizontal and/or vertical direction. In addition, a spring device  25  ( FIG. 3 ) can be provided by which the pushrod  6  and/or the ejection lever  12  can again be returned into a ready position after an ejection process. 
       FIG. 3  shows an exploded view of the arrangement with the furniture drive  4  and the force transmission device  5 . The base plate has a guide  17  extending in the ejection direction  29  of the pushrod  6  and along which a guide element  18  of the slider  27  is displaceably guided. In this case, the ejection direction  29  of the pushrod  6  extends transversely relative to the (main) ejection direction of the ejection lever  12 . In the illustrated embodiment, the pushrod  6  is formed in one piece together with the slider  27 , the guide element  18  and the counterpart tooth arrangement  16 . The furniture drive  4  with the housing  9  can be releasably fixed by way of a snap-connection to a mounting profile member  23  which is to be screwed to a plate  24  extending vertically when mounted. The furniture drive  4  includes an ejection lever  12  which is pivotally mounted about an axis of rotation  11  and which has an ejection surface  14  provided with a tooth arrangement  15 . The tooth arrangement  15  is mounted about a pivot axis  28  and is motionally coupled to the ejection lever  12 . Besides the resilient abutments  19 ,  20  for delimiting the inner end position of the ejection lever  12  and the pushrod  6 , there is provided a spring device  25  including at least one tension spring in the form of a coil spring. The spring device  25  is anchored with a first end region to the pushrod  6  and with a second end region to a, preferably displaceable, spring base  26 . The pushrod  6  and/or the ejection lever  12  can again be returned into a ready position by the spring device  25 . A first part  22  of the closing retaining device  21  is arranged at the free end of the pushrod  6 , wherein the part  22  magnetically cooperates with a corresponding part arranged or provided on the moveable furniture part  3 . The magnetic holding force of the closing retaining device  21  can be of such a magnitude that the moveable furniture part  3  will not be detached from the part  22  of the pushrod  6  after an ejection process has taken place, so that it is only a user who detaches the moveable furniture part  3  from the pushrod  6  after overcoming the magnetic holding force. That represents a safety aspect, because the moveable furniture part  3 , after incorrect triggering (for example by virtue of the moveable furniture part  3  being pressed in by small children or domestic animals), will not be released on its own from the pushrod  6 , whereupon after a predetermined period of time, a return movement of the ejection lever  12  is possible by way of an open-loop or closed-loop control unit of the furniture drive  4 , and thus also retraction of the moveable furniture part  3  (which is magnetically coupled to the pushrod  6 ) by the force of the spring device  25  into the closed end position is attained. 
       FIGS. 4 a -4 d    show a time sequence of the ejection process of the moveable furniture part  3 . Starting from the closed position shown in  FIG. 4 a   , after activation of the electric drive unit  10 , the ejection lever  12  is pivoted out in the direction of the illustrated arrow  30 , in which case the tooth arrangement  15  of the ejection lever  12  cooperates with the counterpart tooth arrangement  16  of the force transmission device  5 . 
       FIG. 4 b    shows the pushrod  6  after a slight extension movement, with the moveable furniture part  3  also being slightly opened.  FIG. 4 c    shows a further open position of the pushrod  6 , wherein the tooth arrangement  15  and the counterpart tooth arrangement  16  move against each other and a positively locking transmission of force is provided.  FIG. 4 d    shows a further open position of the pushrod  6 , with the part  22  of the retaining device  21  being magnetically coupled to the moveable furniture part  3 . When the fully open position of the pushrod  6  is reached, a user can release the moveable furniture part  3  from the magnetic coupling by gripping behind same and can move it further towards the open position. If, in contrast, the magnetic coupling between the part  22  and the moveable furniture part  3  is not released by the action of the user, then, after a predetermined period of time and with the magnetic coupling being maintained, the moveable furniture part  3  is again pulled into the completely closed position. It will be appreciated that a corresponding part of the retaining device  21  is to be arranged or provided on the moveable furniture part  3  so that a magnetic attraction force can be produced between the part  22  and the moveable furniture part  3 . Alternatively, it is for example also possible for the moveable furniture part  3  to be at least region-wise of a metallic nature, in which case the magnetic part  22 —possibly by the interposition of a plastic lining for noise reduction—is operative directly on a metallic region of the moveable furniture part  3 . Thus, it is also possible to open and close doors of tool cupboards, refrigerators, dishwashers or ovens by the provided structure. 
       FIGS. 5 a -5 d    show a plan view of time sequences of the ejection process of the moveable furniture part  3  starting from the closed end position.  FIG. 5 a    shows the closed end position of the moveable furniture part  3 , this Figure therefore corresponding to the view in  FIG. 4 a   . At the beginning of the ejection process, both the ejection lever  12  and also the pushrod  6  by way of the slider  27  bear against the abutments  19  and  20  associated therewith. The tooth arrangement  15  includes a first portion  15   a  and an adjoining second portion  15   b , wherein a movement of the pushrod  6 , in a first range of rotary angular movement of the ejection lever  12 , is effected by the cooperation of the first portion  15   a  with a corresponding portion of the counterpart tooth arrangement  16 , with a high transmission of force and with a low travel transmission. More specifically, at the beginning of the ejection process, there is effectively a shorter force arm (that is to say the spacing between the axis of rotation  11  and that location at which the tooth arrangement  15  and the counterpart tooth arrangement  16  are in contact with each other), whereby a predetermined torque M of the electric drive unit  10  is converted into a greater force F acting on the moveable furniture part  3 . 
       FIG. 5 b -5 d    shows the further sequence in the ejection process, wherein in  FIG. 5 b    the portion  15   a  is already out of engagement with the counterpart tooth arrangement  16 . In a second range of rotary angular movement which adjoins the first range, movement of the pushrod  6  takes place with a lower force transmission which is reduced upon a further ejection movement of the ejection lever  12 . The force transmitted to the pushrod  6  therefore decreases, but a faster extension movement of the pushrod  6  is implemented. Now therefore the portion  15   b  in the form of the eccentric tooth arrangement cooperates with the counterpart tooth arrangement  16 , in which case the slider  27  with the pushrod  6  connected thereto is moved in the direction of the open position with a higher travel transmission.  FIG. 5 c    shows a further open position of the pushrod  6 , from which it can be clearly seen that the ejection travel of the pushrod  6  can be increased by the eccentric configuration of the tooth arrangement  15  and the counterpart tooth arrangement  16 . In  FIG. 5 d   , the moveable furniture part  3  was moved by manually exerting a pulling force in the direction of the open position and after release of the magnetic coupling of the part  22  of the restraining device  21 , into a further open position, and can subsequently be moved freely. It can be seen from  FIGS. 5 a -5 d    that in the mounted condition of the furniture drive  4 , the location at which the tooth arrangement  15  and the counterpart tooth arrangement  16  are in contact with each other moves in the direction towards the free end  13  of the ejection lever  12  (see  FIG. 5 c   ) upon ejection of the moveable furniture part  3 , starting from the proximity of the axis of rotation  11  of the ejection lever  12  (see  FIG. 5 a   ), wherein there is a substantially uniform change in the force arm and violent changes in the exerted force are avoided. It is also possible to see a particular advantage of the invention, namely that the illustrated structure permits a deflection of force and thus also an angular ejection of the pushrod  6  in relation to the ejection direction of the ejection lever  12 . More specifically, it is possible in illustrated  FIG. 5 b    to see the direction  35  of the linear movement of the pushrod  6 , which extends substantially parallel to a longitudinal direction (L) of the housing  9  of the furniture drive  4 . 
       FIG. 6  shows a furniture drive  4  according to a further embodiment, the tooth arrangement  15  being made in one piece together with the ejection lever  12 . The tooth arrangement  15  includes a first portion  15   a  and a second portion  15   b , wherein those two portions  15   a ,  15   b  are respectively of a differently curved configuration. In order for the first portion  15   a  of the tooth arrangement  15  to be pivoted inwardly beneath the housing  9  of the furniture drive  4  upon ejection of the ejection lever  12 , it is possible to provide at the underside  31  of the housing  9  knobs (not visible here) which space the underside  31  of the housing  9  from the base plate  8  so that the first portion  15   a  can pivot inwardly under the housing  9 . 
     In a possible embodiment of the invention, the furniture drive  4  can be assembled together with the force transmission device  5  in a housing of a common constructional unit, in which case only the pushrod  6  is extended out of the housing of that common unit.