Patent Abstract:
A movable furniture part, such as a furniture drawer, includes an ejector device having an ejector lever and an electric motor for driving the ejector lever. A retracting device has a pulling member that can be wound onto a roll. The roll can be driven by an electric motor, and the ejector device and retracting device are mechanically connected to one another such that they can be mounted as a unit in or on a furniture body.

Full Description:
This application is a Continuation of International application No. PCT/AT2008/000056, filed Feb. 22, 2008. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention concerns a drive for a movable furniture part, in particular a furniture drawer, comprising an ejection device having an ejection lever and an electric motor for driving the ejection lever. 
     By virtue of such a drive, it is possible to eject the movable furniture part from its closed end position in or on a furniture body or carcass, into an at least partially open position. It is however not possible to move the movable furniture part in an opposite relationship to the opening direction in order, for example, to transfer it into the closed end position. 
     The object of the invention is to develop a drive of the general kind set forth, in such a way that its functionality is enhanced but the drive is not more complicated and expensive to fit. 
     SUMMARY OF THE INVENTION 
     The provision of a retraction device allows the application of forces to the movable furniture part in the retraction direction. A cable line, for example, presents itself as a pulling means. It is however also possible to provide pulling means having a certain stiffness (such as for example metal bands). 
     The mechanical connection of the ejection device and the retraction device to afford a structural unit ensures that the drive with the combined functionalities is equally simple to fit as a drive in accordance with the state of the art, which has only an ejection device. 
     For example, the ejection device and the retraction device are arranged on a common mounting plate. A particularly preferred embodiment of the invention, however, is one in which the ejection device and the retraction device are arranged in a common housing. 
     It is particularly advantageous if the housing has a stirrup arrestable by a lever for fastening the drive to a profile bar without a tool. That permits particularly simple mounting of the drive. 
     In principle, a drive according to the invention can have an electric motor assembly with respective dedicated electric motors for the ejection device and the retraction device. 
     In that case, it is desirable if the ejection device and the retraction device have respective dedicated transmissions for the transmission of force from the respective electric motor to the ejection lever and the roller respectively so that the drive train of the ejection device and that of the retraction device remain mechanically separated from each other. 
     In such a case, coupling of the ejection device and the retraction device can be effected electronically by a common control or regulating unit. 
     Alternatively, it can be provided that the ejection lever of the ejection device and the roller of the retraction device are drivable by an electric motor assembly with one common electric motor for driving both the ejection device and the retraction device. This embodiment has the advantage that only a single electric motor is required per drive. 
     The operation of switching over the transmission of force from the electric motor to the ejection lever of the ejection device or to the roller of the retraction device respectively can be effected by a wide range of different couplings. A particularly preferred embodiment, however, is one in which the transmission of force from the electric motor is effected selectively to the ejection lever or the roller by way of a planetary transmission. A planetary transmission of that kind is distinguished by a particularly compact structure, which is of significance in particular when the ejection device and the retraction device are arranged in a common housing. 
     In this embodiment, the planetary transmission is of a two-stage nature, wherein the one stage serves for the transmission of force from the electric motor to the ejection lever, and the second stage serves for the transmission of force from the electric motor to the roller. Selection of the respective stage can be effected by way of a brake which is switchable by a control or regulating device and which, for example, can be in the form of a solenoid brake. 
     Each of the two stages of the planetary transmission can have its own hollow ring gear in which the respective planetary gears are accommodated. The brake of each stage co-operates with the respective ring gear. Fixing the respective ring gear by the respective brake causes a rotational movement of the planetary gears. 
     In an embodiment of the invention, in the stage associated with the ejection unit, the transmission of force is effected with the planetary gears rotating. In the stage associated with the roller, the transmission of force occurs with the planetary gears stationary. That arrangement provides that the mutually opposite directions of rotation of the ejection lever and the roller can be implemented with the same direction of rotation of the electric motor. 
     By way of example, three planetary gears can be provided for each stage. 
     The sun gear of the planetary transmission is formed in each stage by a common shaft drivable by the common electric motor. 
     As already stated a common control or regulating device for controlling or regulating the ejection device and the retraction device can be provided in each of the above-mentioned embodiments. 
     In each embodiment of the drive, the ejection device can have a touch-latch functionality. That means that the ejection device is triggerable in the closed and/or partially or completely opened end position of the movable furniture part, by an application of force to the furniture part. The configuration of the ejection device, that is necessary for that purpose, was already disclosed in Austrian patent AT 413 472 (see in particular page 4, paragraphs 3 through 7; page 7, paragraphs 4 and 5; page 8, paragraph 6 and the Figures referred to therein) so that there is no need for a more detailed description at this juncture. 
     The retraction device can also be provided with such a touch-latch functionality so that overall this provides a drive having a touch-latch functionality. For that purpose, it is necessary for the roller to be biased in the winding-on direction by a force storage means so that the pulling means is constantly held under a mechanical tension in the retraction direction. By virtue of that arrangement, an application of force to the movable furniture part by a user can be transmitted to the roller by way of the pulling means and can be detected by way of suitable means (for example rotary potentiometers). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages and details of the invention will be apparent with reference to the drawings and the related specific description. In the drawings: 
         FIG. 1  shows a perspective view of an embodiment of a drive according to the invention with a common housing, 
         FIGS. 2   a  and  2   b  show the drive train of a first embodiment of a drive according to the invention as a perspective view and a block-wise exploded view, 
         FIGS. 3   a  and  3   b  show a detail view of  FIGS. 2   a  and  2   b  as a perspective view and an exploded view, 
         FIGS. 4   a  through  4   e  show the drive train of a second embodiment of a drive according to the invention in various perspective views and sectional views, and 
         FIGS. 5   a  through  5   c  show the drive train illustrated in  FIGS. 4   a  through  4   c  in further views and as a detail view. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a perspective view of a drive  1  according to the invention in which all components are arranged in a common housing  2  or mounted therein. It is possible to see in particular the ejection lever  3  of an ejection device and the pulling member  4  of a retraction device. The drive  1  can be fastened without a tool to a profile bar (not shown) in a furniture body or carcass by way of the lever mechanism denoted by reference  5 . 
       FIG. 2   a  shows a perspective view of the first drive train  6 ,  9 ,  3  of the ejection device and the second drive train  7 ,  10 ,  8  of the retraction device for a first embodiment of a drive  1  according to the invention, in which the ejection lever  3  of the ejection device and the roller  8  of the retraction device are drivable by an electric motor assembly with separate electric motors  6  and  7  respectively, and there are respective dedicated transmissions  9  and  10  for the transmission of force. 
     The first drive train  6 ,  9 ,  3  of the ejection device has a first transmission  9  by which the rotary speed of the electric motor  6  (for example about 6000 rpm) can be reduced by way of a series of gears. It can further be seen that the ejection lever  3  is provided in a known manner (see for example FIG. 17 of AT 413 472 B) with a tooth configuration  12  with which a rotary potentiometer (not shown) meshes to ensure a touch-latch functionality. 
     The second drive train  7 ,  10 ,  8  of the retraction device has a second transmission  10  for reducing (about 40:1) the rotary speed of the second electric motor  7  (for example, about 12,000 rpm) and is shown in detail in  FIGS. 3   a  and  3   b.    
       FIG. 2   b  shows that the first and second drive trains  6 ,  9 ,  3  and  7 ,  10 ,  8  in the mounted position shown in  FIG. 2   a  are mechanically separated from each other and are pushed as close together as possible only for reasons of space. 
       FIG. 3   a  shows the second transmission  10  together with the roller  8  which is driven by the second transmission  10  and on which the pulling member  4  is wound. The pulling member  4  is passed out of the housing  2  (not shown here) by rollers  13  and is provided at its free end with a coupling portion  48  to be connected to a corresponding coupling portion (not shown) on the movable furniture part. 
     The second electric motor  7  drives the gear  14  by way of its worm. The gear  14  is non-rotatably connected by the shaft  15  to the gear  16 . The gear  16  meshes with the gear  17  which in turn meshes with the gear  18 . The gear  18  is non-rotatably connected to a square region  19  serving for the transmission of force to the roller  8 . In this arrangement, connected between the square region  19  and the roller  8  is a slipping clutch  20  through  23  which is described in detail in Austrian patent application A 1769/2006. This involves a wrap spring clutch, the outer casing  22  of which is slightly braked by the spring  23 , leading to immediate shifting of the clutch. 
     The roller  8  is biased in the winding-on direction by a force storage means  24 . 
     Non-rotatably connected to the roller  8  is a worm attachment  25  meshing with the drive gear  26  of a rotary potentiometer. In that case, the rotary potentiometer serves to determine the position of the roller  8  to implement a touch-latch functionality and the position as a movable furniture part. 
       FIGS. 4   a  through  4   e  show the drive train of a second embodiment of a drive  1  according to the invention, including an electric motor assembly with a common (single) electric motor  6  for driving both the ejection lever  3  and the roller  8  (see  FIG. 5 ). 
     In this case, a planetary transmission  11  is provided for the selective transmission of force to the ejection lever  3  of the ejection device and the roller  8  of the retraction device respectively (see the perspective view in  FIG. 4   a ). The structure of the planetary transmission  11  will be described with reference to  FIG. 4   b  in conjunction with  FIGS. 5   a  through  5   c . The flow of force through the planetary transmission  11  is diagrammatically shown in  FIGS. 4   c  through  4   e.    
     The planetary transmission  11  has a first drive gear  27  drivable by way of the gears  28  and  29  by the worm  30  of an electric motor  6  (see  FIG. 5   a ). 
     The drive gear  27  is arranged non-rotatably on the shaft  31  which functions as the sun gear of the planetary transmission  11 . Arranged on the same shaft  31  is a gear carrier  32  which by way of pins  35  carries three planetary gears  34  (only two planetary gears  34  can be seen in  FIG. 4   b ). Arranged integrally with the gear carrier  32  between the gear carrier  32  and the first drive gear  27  is a square region  33 , on to which the ejection lever  3  of the ejection device can be fitted for drive purposes. Jointly with a ring gear  36  which is toothed at the inside (i.e., has internal teeth), the first stage of the planetary transmission  11  is formed by the components  32 ,  33 ,  34 ,  35  and  36  and the shaft  31  as the sun gear. 
     Arranged beneath the first ring gear  36  is a second ring gear  38  carrying three planetary gears  39  (only two can be seen). The planetary gears  39  mesh with the internal teeth of a roller gear  40  which is formed integrally with the roller  8  and with the intermediate gear  37  non-rotatably connected to the shaft  31 . The roller gear  40  further has external teeth  41  which mesh by way of a gear  42  and a gear  43  with a rotary potentiometer (not shown) (see  FIG. 5   a ). 
     The second stage of the planetary transmission  11  is formed by the components  37 ,  38 ,  39  and  40  and the shaft  31  as the sun gear. 
     The functionality of the planetary transmission  11  will also be described in particular with reference to  FIGS. 4   c  through  4   e . In this respect, for the sake of enhanced clarity, only the respective relevant components are denoted by reference numerals in  FIGS. 4   d  and  4   e.    
       FIG. 4   d  shows the transmission of force from the electric motor  6  to the ejection lever  3  of the ejection device. The application of force is effected by way of the drive gear  27  to the shaft  31 . The brake  44  associated with the first stage of the planetary transmission  11  (this cannot be seen in  FIG. 4   d  as it is on the rear side which cannot be viewed) brakes the first ring gear  36  of the first stage by way of a first wrap spring  45 . That causes a rotational movement of the planetary gears  34  in the first ring gear  36 , in meshing engagement with the internal teeth of first ring gear  36 . That arrangement provides that, by way of the pins  35 , the gear carrier  32  and the square region  33  arranged thereon are rotated. That rotation drives the ejection lever  3  of the ejection device. 
     In the meantime, the brake  44  of the second stage remains inactive. The second ring gear  38  of the second stage can freely rotate jointly with the planetary gears  39  fixed thereto. By virtue of that situation, no force is transmitted to the roller gear  40  and the roller  8 . 
     The situation is different in  FIG. 4   e . Here the brake  44  (see  FIG. 5   a ) of the second stage is active and presses the second wrap spring  46  against the second ring gear  38 . Due to second the ring gear  38  being fixed, the planetary gears  39  remain stationary and mesh on the one hand with the intermediate gear  37  driven by the shaft  31  and on the other hand with the internal teeth of the roller gear  40 . As a result, the drive force is transmitted from the intermediate gear  37  (sun gear) by way of the planetary gears  39  to the roller gear  40  and thus to the roller  8 . 
     The first stage (transmission of force to the ejection lever  3 ) therefore has a first set of planetary gears  34  which rotate during the transmission of force whereby the gear carrier  32  carrying the planetary gears  34  by way of the pins  35  is set in motion. 
     In contrast thereto, the second stage (for the roller  8 ) has a second set of planetary gears  39  which are stationary during the transmission of force as in fact the second ring gear  38  on which the planetary gears  39  are mounted is fixed by the wrap spring  46 . That situation involves the transmission of force from the shaft  31  and the gear  37  by way of the planetary gears  39  to the gear  40 . The direction of rotation, however, is reversed in comparison with the first stage. That is also to be required as in fact the drive direction for ejection or retraction respectively of a movable furniture part must be in mutually opposite relationship, while the direction of rotation of the shaft  31  is unchanged. 
     The structure of the brake  44  is also of interest, as can be seen from  FIGS. 5   b  and  5   c . It can be seen that the brake  44  has a pushrod  47  which, when the brake  44  is activated, presses against the associated wrap spring  45  or  46 , respectively. In this embodiment, the brakes  44  are in the form of solenoid brakes.

Technology Classification (CPC): 0