A damping device for movable furniture part, includes a damper housing, a fluid chamber which is arranged in the damper housing and in which a piston is movably mounted, a tappet which is connected to the piston, at least one seal being arranged between the damper housing and the tappet in order to seal the fluid chamber, wherein the tappet passes through the seal, a compensating chamber which is fluidically connected to the fluid chamber, which runs laterally parallel to the fluid chamber. At least one deformable compensating body is arranged in the compensating chamber in order to compensate for a volume change due to the tappet being immersed into the fluid chamber. The deformable compensating body and the at least one seal are designed together as a single piece.

BACKGROUND OF THE INVENTION 
     The present invention concerns a damping device for moveable furniture parts, comprising:
         a damper housing,   a fluid chamber arranged in the damper housing and in which a piston is moveably supported, and   a ram connected to the piston. Arranged between the damper housing and the ram is at least one seal for sealing off the fluid chamber, and the ram passes through the seal.   In addition, a compensating chamber which is in fluid-conducting relationship with the fluid chamber extends laterally parallel to the fluid chamber and there there is arranged at least one deformable compensating body in the compensating chamber for compensation for a change in volume due to the ram immersing into the fluid chamber.       

     The damping action of fluid dampers is substantially based on the flow resistance of a damping fluid present in a fluid chamber. When the piston is subjected to pressure, it is displaced relative to the fluid chamber, in which case the fluid flows from one cylinder chamber into another cylinder chamber by way of through-flow openings of the piston or between the piston and fluid chamber. In order to prevent the liquid damping medium from escaping from the damper, the ram or the piston rod is sealed relative to the fluid chamber by a seal, wherein the ram or the piston rod is slidingly displaceable against that seal. The compensating chamber is provided to compensate for the volume of the piston rod or ram as it moves into or out of the fluid chamber so that failure of the damping device due to the increased pressure loading of the inwardly moving piston rod is prevented. 
     WO 2010/108203 A1 to the present applicant discloses a furniture hinge having a damping device which has two fluid chambers connected by way of a passage. Arranged in one fluid chamber is a device having a displaceable piston or a displaceable material portion provided to compensate for the volume of the piston rod. 
     DE 199 01 517 A1 describes a door closer having a hydraulic piston-cylinder unit, wherein a compensating body forming the pressure compensating space is arranged in one of the hydraulic spaces. The compensating body is connected to a piston component and is of a bag-form configuration, wherein the inwardly moving volume of the piston rod can be compensated by the compensating body present in the hydraulic space. 
     EP 1 241 374 A1 and JP 60-018631 respectively describe damping devices having a piston guided in a fluid chamber and a compensating chamber extending parallel to the fluid chamber, wherein the seal arranged between the damper housing and the ram and the compressible material disposed in the compensating chamber are formed separately from each other. 
     In the state of the art, a relatively large number of individual parts are necessary for the damping device, and those parts, due to the desired compact structure of furniture dampers, are additionally very small and delicate, in which respect assembly of the damper is also relatively complicated and laborious. 
     SUMMARY OF THE INVENTION 
     Therefore the object of the present invention is to provide a damping device of the general kind set forth in the opening part of this specification, while avoiding the above-mentioned disadvantages. 
     According to the invention, it is therefore provided that the deformable compensating body and the at least one seal are of a one-piece configuration. 
     In that way the number of required components for the damping device can be reduced, and also the one-piece design of the compensating body with the seal results in a more robust structure and is thus less susceptible to trouble. 
     The material of the compensating body with the seal formed thereon can be formed from plastic, for example a thermoplastic material or an elastomer or also a mixture of those materials, wherein it is preferably provided that this one-piece component is formed from rubber. 
     The compensating body can be in the form of a hollow body which is preferably filled with air and which is of a fluid-tight nature. That has the advantage over conventional compensating bodies of foam that the air contained in the foam can no longer be dissolved in the damping medium (for example in silicone oil), thereby ensuring linear volume compensation even after numerous damping stroke movements. In a possible embodiment the compensating body can be of a substantially bag-form configuration which in the rest position substantially completely fills the compensating chamber and is compressible in a damping stroke movement. 
     In a possible embodiment it can be provided that a sealing body is arranged in the compensating chamber to seal off the compensating chamber, wherein the compensating body, the seal and the sealing body are provided jointly in one piece. In that way the number of components required for the damper can be reduced even more. 
     The furniture hinge according to the invention is characterised by at least one damping device of the kind in question. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further details and advantages of the invention will be described by means of the embodiment by way of example illustrated in the drawings, in which: 
         FIG. 1  shows a perspective view of an article of furniture in cabinet form with a pivotably mounted door, 
         FIG. 2  shows a perspective view of a furniture hinge with a damping device, 
         FIGS. 3   a  and  3   b  show two different sectional views of the damping device, the piston being in a readiness position, 
         FIGS. 4   a  and  4   b  show two different sectional views of the damping device, the piston being in a pressed-in position, 
         FIGS. 5   a - 5   c  show various views of the compensating body which is in one piece with the seal of the fluid chamber and with the seal of the compensating chamber, 
         FIG. 6  shows an exploded view of the damping device and parts of the furniture hinge, 
         FIGS. 7   a  and  7   b  show a cross-section of the damping device of a further embodiment, and 
         FIGS. 8   a  and  8   b  show a cross-section of the damping device in a further embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a perspective view of an article of furniture  1 , wherein a door  3  is mounted pivotably by way of furniture hinges  4  relative to a furniture carcass  2 . In a known manner, the furniture hinges  4  have a hinge cup  5  hingedly connected to a carcass-side fitment portion in the form of a hinge arm  6 . The furniture hinges  4  each have a damping device  7  (not visible here) for damping a hinge movement, and it is preferably provided that the damping device  7  is mounted in or on the hinge cup  5 . In particular it can be provided that at least one damping device  7  is mounted to the outside of the hinge cup  5 , wherein the hinge cup  5  together with at least one damping device  7  arranged thereon can jointly be fitted within a provided furniture standard bore in the door  3  and are arranged within a notional diameter of the bore. 
       FIG. 2  shows a perspective view of a furniture hinge  4 , wherein the hinge cup  5  is pivotably connected to the hinge arm  6  by way of at least one hinge lever  8 . The hinge cup  5  is provided with a fixing flange  9 , wherein at least one damping device  7  is mounted with a damper housing  10  beneath the fixing flange  9  and at the outside of the hinge cup  5 . The damping device  7  has a switch  11  which is to be adjusted by a person and by which the damping action of the damping device  7  can be completely deactivated, if desired. Provided within the hinge cup  5  is a pivotably mounted actuating element  12  which towards the end of the closing movement of the hinge  4  can be acted upon by the hinge lever  8  and can be pressed in thereby in the direction of the bottom of the hinge cup. That last closing movement can be damped by the provided damping device  7 . The actuating element  12  is preferably mounted pivotably about an axis parallel to the axis of rotation  13 . 
       FIGS. 3   a  and  3   b  show two different perspective sectional views of the damping device  7 . It is possible to see the actuating element  12  which is mounted rotatably about a pivot axis  14  relative to the hinge cup  5  and which towards the end of the closing movement can be acted upon by the hinge lever  8  which engages into the hinge cup  5  ( FIG. 2 ). A lever  16  mounted pivotably about the axis of rotation  15  is motionally coupled to the actuating element  12  so that therefore the lever  16  always moves with a movement of the actuating element  12 . The lever  16  has a lever arm  17  which bears against a ram  18  (or a piston rod, respectively). The ram  18  is connected to a piston  19  mounted displaceably in a fluid chamber  20  of the damper housing  10 . After a damping stroke movement has occurred, the ram  18  (and therewith the piston  19 ) can be returned again into a ready position for the next damping stroke movement, by way of a return spring  21  arranged in the fluid chamber  20 . In  FIGS. 3   a  and  3   b  the piston  19  is in such a ready position. The fluid chamber  20  is filled with a hydraulic damping fluid which, upon a displacement of the piston  19  in the direction of the end  22  of the fluid chamber  20 , can flow laterally past the piston  19  between the piston  19  and the inside wall  23  ( FIG. 3   b ) of the fluid chamber  20  and can flow through a passage  24  ( FIG. 3   b ) into a compensating chamber  25  in which a deformable compensating body  26  is arranged. That compensating body  26  serves to compensate for the volume of the ram  18  as it moves into the fluid chamber  20 . As can be clearly seen from  FIG. 3   a , the compensating body  26  in the rest position is of a substantially bag-form configuration and substantially completely fills the compensating chamber  25 . The compensating body  26  is filled with air and in the damping stroke movement—that is to say when the ram  18  is moved in the direction towards the end  22  of the fluid chamber  20 —can be elastically deformed by the volume of fluid streaming into the compensating chamber  26 , wherein air can escape through an opening  27  of the damper housing  10 . When the ram  18  is moved back into the ready position again by the force of the return spring  21 , then the damping fluid in the compensating chamber  25  can flow back into the fluid chamber  20  again due to the reduced pressure caused thereby and the compensating body  26  can again assume the bag-form shape shown in  FIG. 3   a , due to the incoming air flowing through the opening  27 . There is also provided an overload prevention means  28  by which at least one overload opening  29  between the fluid chamber  20  and the compensating chamber  25  can be opened above a threshold value of a pressure acting on the ram  18 . The overload prevention means  28  includes a ball  31  which is pre-stressed by a spring  30  and which when a predetermined fluid pressure is exceeded opens the overload opening  29  so that in an overload situation the damping fluid can flow across from the fluid chamber  20  into the compensating chamber  25 . When the fluid pressure falls below the predetermined pressure, the overload opening  29  is closed again by the spring-loaded ball  31 . 
     A seal  33  which seals off the ram  18  relative to the damper housing  10  and which is provided jointly in one piece with the compensating body  26  is essential. In the illustrated embodiment, it is also provided that the sealing body  34  which seals off the compensating chamber  25  relative to the damper housing  10  is formed jointly in one piece with the seal  33  and the compensating body  26 . 
       FIG. 3   b  shows another sectional view of the damping device  7  of  FIG. 3   a , wherein it is possible to see the gap which remains between the piston  19  and the inside wall  23  of the fluid chamber  20  and through which the damping fluid can flow from one side of the piston to the other. To influence the damping action, the inside wall  23  of the fluid chamber  20  can have grooves which are of a narrowing flow cross-section in the direction of the end  22 , whereby adaptive damping can be implemented. It is possible to see the switch  11  for deactivating the damping function and at least one resilient latching element  32  for—preferably releasably—fixing the damping device  7  to the hinge cup  5 . To provide a particularly compact damping device  7 , it can be provided that the fluid chamber  20  has a first longitudinal axis and the compensating chamber  25  has a second longitudinal axis, the first longitudinal axis of the fluid chamber  20  and the second longitudinal axis of the compensating chamber  25  extending in substantially parallel mutually spaced relationship. 
       FIGS. 4   a  and  4   b  show two different sectional views of the damping device  7 , the piston  19  being disposed near the rearward end position. A pivotal movement of the actuating element  12  also causes rotation of the lever  16 , the lever end  17  of which presses the ram  18  (and therewith the piston  19 ) into the fluid chamber  20 . Then—corresponding to the arrow shown in  FIG. 4   b —the displaced damping fluid can flow starting from the high-pressure side (H) laterally past the piston  19  to the low-pressure side (L) and through the passage  24  into the compensating chamber  25 , whereby the compensating body  26  is deformed and thus the volume of the inwardly moving ram  18  is compensated. The air displaced in the compensating body  26  can flow out of the opening  27  ( FIG. 4   a ). After the damping stroke movement has occurred, the return spring  21  can return the piston  19  again, in which case due to the reduced pressure caused thereby, the damping fluid can flow from the compensating chamber  25  back again into the fluid chamber  20  and the compensating body  26  can again assume the original form ( FIG. 3   a ) due to air flowing in through the opening  27 . The passage  24  can lead from that end region of the fluid chamber  20 , that is away from the end  22  of the fluid chamber  20 , to the compensating chamber  25 . The passage  24  then opens into that end region of the compensating chamber  25 , that is away from the end  36  of the compensating chamber  25 . The advantage of the passage  24  extending from the low-pressure side (L) is its short length leading to the compensating chamber  25 , whereby the risk of leakage is substantially eliminated. In addition, the compensating body  26  is deformable in a defined fashion by virtue of being acted upon from the low-pressure side (L) and can thus be adapted to the respectively prevailing fluid pressure in an improved fashion. 
       FIGS. 5   a - 5   c  show various views of the compensating body  26 .  FIG. 5   a  shows the compensating body  26  in the rest position, which in this operative condition is of a bag-shape configuration. The compensating body  26  together with the seal  33  (which seals off the ram  18  relative to the damper housing  10 ) and the sealing body  34  (which seals off the compensating chamber  25  relative to the damper housing  10 ) is of a common structural unit in the form of a one-piece configuration.  FIG. 5   b  shows the compensating body  26  in the compressed condition, while  FIG. 5   c  shows the compensating body  26  which is of a hollow configuration, the sealing body  34  and the seal  33  in a sectional view. 
       FIG. 6  shows an exploded view of the damping device  7 , wherein the fluid chamber  20  and the compensating chamber  25  which extends in laterally parallel relationship therewith are provided within the damper housing  10 . It is possible to see the actuating element  12  which in the mounted position is non-rotatably connected to the lever  16 . The ram  18  is connected to the piston  19 , the ram  18  being sealed off relative to the damper housing  10  by means of the seal  33  which is formed in one piece together with the sealing body  34  of the compensating chamber  25  and the elastically compressible compensating body  26 . The end of the piston rod or ram  18 , that is remote from the piston, is led out of the fluid chamber  20  in the assembled condition and projects into a closure portion  35 . 
       FIGS. 7   a  and  7   b  show cross-sectional views of a further embodiment of the damping device  7 .  FIG. 7   a  shows the damping device  7  with a ram  18  in the ready position, whereas  FIG. 7   b  shows the ram  18  or piston  19  in the position of being pressed into the fluid chamber  20 . A fluid chamber  20  and a compensating chamber  25  extending in laterally parallel relationship therewith are provided within the damper housing  10 . The seal  33  which is provided for sealing off the fluid chamber  20  and through which the ram  18  passes, is formed in one piece together with the deformable compensating body  26 . In the illustrated embodiment, the bag-form compensating body  26  is so arranged that—relative to the end  22  of the fluid chamber  20 —it faces in a direction in opposite relationship thereto and projects out of the damper housing  10 . When now the ram  18  is pressed into the fluid chamber  20 , the displaced damping fluid passes into the interior of the compensating body  26  and—as shown in  FIG. 7   b —causes it to bulge out in a direction transversely relative to the damping stroke movement of the piston  19 . After the damping stroke movement has occurred, the piston  19  can be moved back again into the ready position of  FIG. 7   a  by the force of a return spring  21 . 
       FIGS. 8   a  and  8   b  show a cross-section of the damping device  7  in a further embodiment. Provided in the damper housing  10  is a fluid chamber  20  with a piston  19  mounted displaceably therein, the piston  19  being connected to the ram  18 . Arranged concentrically relative to the fluid chamber  20  is a compensating chamber  25  surrounding the fluid chamber  20 —preferably in an annular configuration. The seal  33  for sealing off the fluid chamber  20 , through which the ram  18  passes, is provided in one piece with the deformable compensating body  26 .  FIG. 8   a  shows the damping device  7  with the ram  18  in a ready position. When now the ram  18  is pressed into the fluid chamber  20 , the displaced damping fluid passes into the compensating chamber  25  and causes the compensating body  26  which is of a sleeve-like configuration to bulge out in the radial direction. The direction of the maximum expansion of the compensating body  26  extends in that case substantially in a direction at a right angle to the damping stroke movement of the piston  19 . 
     The present invention is not just limited to the illustrated embodiments but includes or extends to all variants and technical equivalents which can fall within the scope of the appended claims. The positional references adopted in the description such as for example up, down, lateral and so forth are also related to the directly described and illustrated Figure and are to be appropriately transferred to the new position upon a change in position. The compensating chamber  25  is preferably separated from the fluid chamber  20  but it can also be integrated into same. The piston  19  can also be provided with at least one opening, through which the damping fluid can flow through the piston  19  between the high-pressure side (H) and the low-pressure side (L).