Abstract:
The present invention relates to a damping apparatus for moving furniture parts, for example doors, flaps or drawers. Such a damping apparatus of a compact construction which avoids a possible springing back movement of the furniture parts is provided in accordance with the invention in that the damping apparatus has at least two damping stages each having a cylinder having a piston longitudinally displaceable therein which exert a damping action of different strengths.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a damping apparatus for moving furniture parts, for example for doors, flaps or drawers. 
     Such damping apparatuses are known in numerous different embodiments. DE 44 09 716 A1 shows an air damper which consists of a piston and a cylinder and whose piston is braked on its plunging into the cylinder by the compressed air in the cylinder, with the escape of the air being largely prevented by a seal through which the piston is moved on plunging into the cylinder. DE 37 29 597 A1 likewise shows a damping apparatus comprising a cylinder and a piston longitudinally displaceably received therein. A spigot is received in the cylinder which has a diameter changing in the longitudinal direction and which is guided in the piston designed as a hollow piston. The air compressed in the cylinder on the insertion of the piston is expanded depending on the position of the piston by the annular gap between the spigot and the bore of the piston. 
     Damping apparatuses of the kind first mentioned are furthermore known from DE 201 20 112.7. Air dampers are disclosed which have a bore in the jacket wall of the cylinder close to the closed end region, whereby a very good damping effect can be achieved. 
     If furniture parts are closed with great force or at great speed, the kinetic energy cannot be completely absorbed immediately by the aforesaid dampers on contact with them so that it can occur that the furniture parts jump back before they are pulled into their final closed position by closing apparatuses. A door damping element is known from JP 0020279886 AA which consists of a resilient damping part and an oil damper. The resilient damping part should have the effect that the impact of the door is damped. The remaining kinetic energy should be absorbed by the oil damper. 
     SUMMARY OF THE INVENTION  
     It is the object of the present invention to provide a damping apparatus of the kind first mentioned which avoids a possible jumping back movement of the furniture parts with a compact construction. 
     The object is solved by a damping apparatus having the features herein. In accordance with the invention, the damping apparatus has at least two damping stages which have in each case a cylinder having a piston longitudinally displaceable therein and which exert a damping effect of different strength. The braking effect is thus divided into two stages which are designed differently in that they exert braking effects of different strengths on their actuation. Provision can, for example, be made that the braking effect is achieved by two damping stages of which the first damping stage has a comparatively weak spring and the second damping stage has a customary air damper. In such an embodiment, the movement of the furniture part is initially mainly reduced by the force of the spring, while the following damping stage is only partly made use of. The remaining kinetic energy already reduced by the first stage is then completely absorbed by the second damping stage. A progressive braking effect thus results between the two stages, whereby jumping back of the furniture parts is avoided. 
     The damping apparatus can consist of two damping stages. More than two damping stages can naturally also be realized. The design of the damping apparatus with telescopic cylinders results in a particularly compact aspect of the damping apparatus. 
     In a preferred aspect of the present invention, the damping apparatus has a multistage, preferably two-stage, telescopic cylinder whose first damping stage has a piston loaded by a spring and received in a telescopic cylinder and whose second damping stage is formed by an air damper. The design of a damping apparatus with multi-stage telescopic cylinders is known, for example, from the already named DE 201 20 112.7 and also from DE 201 17 031.0. Damping apparatuses of this kind are characterized by a very small length or installation depth such that a particularly compact construction can be realized. 
     An air gap can exist between the piston and the cylinder of the first damping stage such that the braking effect of the first damping stage is essentially brought about by the force of the spring acting on the piston. 
     In a further aspect of the present invention, provision is made that the cylinder of the first damping stage has a piston fixedly connected to it which has a peripheral seal received in a groove which contacts the wall of the cylinder of the following damping stage in the insertion direction in a sealing manner and which contacts the groove wall in the moving out direction. 
     Whereas a compression of the air in the cylinder space thus takes place on the insertion movement, and thus the desired damping effect of the air damper is achieved, air can pass between the piston and the cylinder wall on the moving out so that the piston can be moved outward freely and easily. 
     The sealing is advantageously received in a groove of the piston which is in communication with the inner space of the cylinder of the following damping stage via passages. On the moving out of the piston, air flows through the passages such that, as described above, the piston can be pulled freely outward. 
     Provision can further be made that the piston of the first damping stage and the piston of the second damping stage each have a cut-out in Which the end regions of the spring of the fist damping stage are received. 
     In a further aspect of the invention, provision is made that the cylinder of the first damping stage has an annular flange by means of which this is supported in the starting position at a collar of the cylinder of the second damping stage at the front face. 
     The cylinder of the first damping stage can have an annular flange at which the piston of the first damping stage is supported in the starting position. 
     In a preferred aspect of the present invention, the last, or in a two-stage design the second, damping stage is formed by an air damper whose cylinder has a bore close to the closed end region in the jacket wall, the diameter of said bore being substantially smaller than that of the cylinder. Reference is made here to DE 201 20 112.7, from which a damping apparatus having a correspondingly arranged bore can be seen. 
     In a further aspect of the present invention, provision is made that the piston of the first damping stage has a plunger in whose end region a magnet is arranged. This has the effect that the damping apparatus is again moved into its starting position on the opening of the moving furniture part and is then available for a new damping process. 
     Provision can further be made for a spring to be provided in the last damping stage which is supported on the base of the cylinder of the last damping stage and exerts a return force on the piston of this damping stage. This spring guides the piston of this damping stage back into its starting position. 
     Provision can be made in this case that the piston of the first damping stage has a plunger in whose end region a buffer is arranged. 
     It is particularly advantageous for the first damping stage to exert a lower damping action than the second damping stage. Provision can be made for the second damping stage to be designed such that its starting friction is overcome during the actuation of the first damping stage. A gentle transition of the braking effect of the damping stages can thereby be achieved, whereby a springing back of the furniture parts can largely be avoided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       Further details and advantages of the present invention will be explained in more detail with reference to an embodiment shown in the drawing, in which are shown: 
         FIG. 1 : a sectional representation through a first embodiment of the damping apparatus in accordance with the invention in its starting position; 
         FIGS. 2 ,  3 : a section through the damping apparatus in accordance with  FIG. 1  in a partially and fully inserted position; 
         FIG. 4 : a section through a further embodiment of the damping apparatus in accordance with the invention in its starting position; and 
         FIGS. 5-9 : individual parts of the damping apparatus in accordance with  FIGS. 1 to 4 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     A damping apparatus  1  in accordance with the invention can be seen from  FIG. 1 . This consists of two damping stages of which the first has the cylinder  30  having the piston  32  and the second has the cylinder  20  having the piston  22 . 
     The piston  32  is guided in a longitudinally displaceable manner in the cylinder  30  of the first damping stage. The piston  32  has a plunger  34  in one piece with it in whose end region the magnet  36  is arranged. 
     The cylinder  30  has in its end region the piston  22  of the second damping stage, said piston  22  being fixedly connected to said cylinder  30 . The connection can take place, for example, by ultrasonic welding. 
     The piston  22  is displaceably guided in the cylinder  20  of the second damping stage. 
     The piston  32  has the cut-out  320  an the piston  22  has the cut-out  220  in which the end regions of the spring  40  of the first damping stage are received. 
     The piston  32  is supported in its starting position shown in  FIG. 1  at the annular collar  302  of the cylinder  30 . Furthermore, the cylinder  30  is supported in the starting position by its annular flange  300  at the collar  200  of the cylinder  20  at the front face, as is shown in  FIG. 1 . 
     The piston  32  is guided in the cylinder  30  such that an air gap remains between the piston  32  and the inner cylinder wall through which the air can flow such that the movement of the piston  32  substantially only takes place against the force of the spring  40  such that the damping characteristic of this first damping stage is quite substantially determined by the spring  40 . 
     The piston  22  of the second damping stage has the annular groove  24  in which the seal  26  is received. The groove  24  is in communication with the inner space  21  of the cylinder  20  of the second damping stage by means of the passages  28  and  29 . 
     The end region of the cylinder  20  is closed by the cap  60  which is fixedly connected to the cylinder  20 , for example by ultrasonic welding or by other customary means. The bore  202 , through which air escapes in a controlled manner on the pressing of the piston  22  into the cylinder  20 , whereby the damping action of the second damping stage is effected, is located in the end region of the jacket surfaces of the cylinder  20 . 
     The function of the damping apparatus shown in  FIG. 1  is designed as follows: on the pressing in of the plunger  34 , the spring  40  is first compressed which sets a lower resistance against the impressing force than the second damping stage formed by the air damper. This has the consequence that the piston  32  is moved in the direction of the piston  22  until the end faces of the pistons contact one another, as is shown in  FIG. 2 . Part of the movement of the furniture part is absorbed by the pushing in of the piston  32  and the movement energy is reduced accordingly. This is now subsequently taken up by the second damping stage whose function is designed as follows: 
     Starting from the position shown in  FIG. 2 , the cylinder  30  with the piston  22  is now inserted into the cylinder  20 . The air is then compressed in the inner space  21 , whereby the pressure also increases in the passages  28  and  29  as well as in the groove  24  such that the seal  26  is pressed onto the inner wall of the cylinder  20 . This has the consequence that the air can substantially only escape through the bore  202 . The counter force applied by the air results in a further damping of the movement of the furniture part until the cylinder  30  is completely received in the cylinder  20 , as is shown in  FIG. 3 . 
     The damping action of the second damping stage is advantageously designed such that the partial load also acting on the second damping stage during the compression of the spring  40  results in an overcoming of the starting friction. This has the advantage that the second damping stage is set in motion directly after the state shown in  FIG. 2  so that a progressive effect of the damping apparatus is achieved and any springing back of the furniture parts can be avoided. 
       FIG. 4  shows a further embodiment of the damping apparatus in accordance with the invention. The elements shown here substantially correspond to those shown in  FIG. 1 . An exception to this is formed by the spring  50  which is supported between the base  60  of the cylinder  20  and the area of the piston  22  of the second damping stage at the front face which faces this. The spring  50  is fixed on the neck  62  of the base  60 . The spring  50  has the effect that a return force is exerted on the piston  22  such that this is pushed back into the position shown in  FIG. 4  when no strain is present. The same applies accordingly to the action of the spring  40  on the piston  32 . 
     In the embodiment shown in  FIG. 4 , the end region of the plunger  34  is not fitted with a magnet, but with the buffer  38 . 
       FIGS. 5 to 9  show individual parts of the aforesaid damping apparatuses in accordance with the present invention.  FIG. 5  shows the base  60  of the cylinder  20  which is preferably fixedly connected to this in an air tight manner by ultrasonic welding or also by other connection techniques in order to ensure that the air only escapes through the bore  202 . 
       FIG. 6  shows the cylinder  20  of the second damping stage with a bore  202  and the collar  200  at the front face which, in the starting position shown in  FIG. 1  and in  FIG. 4 , holds the annular flange  300  of the cylinder  30 . 
       FIG. 7  shows the piston  22  with the annular groove  24  and the passages  28 ,  29 , with the passages  28  extending radially and the passage  29  extending axially with respect to the cylinder  20  or piston  22 . Furthermore the cut-out  220  can be seen in  FIG. 7  which serves the purpose of taking up an end region of the spring  40  whose other end region is received in the cut-out  320  of the piston  32 . 
       FIG. 8  shows the telescopic cylinder  30  which is received in the cylinder  20  in the inserted state of the damping apparatus, as can be seen from  FIG. 3 . The cylinder  30  has the annular flange  300  which contacts the collar  200  of the cylinder  20  at the front face in the starting position. Furthermore, the cylinder  30  has the annular collar  302  which serves the purpose of holding the piston  32  in the starting position in accordance with  FIGS. 1 and 4 . 
     Finally,  FIG. 9  shows the piston  32  with the plunger  34  adjoining it in one piece. The cut-out  320  serves the reception of an end region of the spring  40 ; the cut-out of the plunger  34  shown on the right hand side serves the reception of a magnet  36  (see  FIG. 1 ) or of the buffer  38  (see  FIG. 4 ). 
     The present embodiments show the second damping stage as an air damper and the first damping stage as a spring-loaded damper. Generally, other embodiments are also conceivable here. For example, the air damper could also be formed by another customary damping device.