Abstract:
A damping device with variable damping force, including a cylinder, in which a piston rod is arranged axially movably, and an adjustable damping valve which is activated as a function of the compression travel of an axle part. The adjustable damping valve is activated by a generator device. The generator device includes an equidirectional device which causes an equidirectional regulating variable to take effect on the adjustable damping valve independently of the compression direction.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to a damping force device with adjustable damping force.  
           [0003]    2. Discussion of the Prior Art  
           [0004]    German reference DE 196 37 095 C2 discloses a vibration damper with variable damping force, in which the damping force is adjustable as a function of the compression travel. As soon as an axle part expands, for example on a bend, there is no damping force adjustment carried out. In the embodiment of the vibration damper according to DE 196 37 095 C2, there is a tendency toward a softer setting of the damping force, since the adjustable damping valve is not additionally pressurized. It was found that it is expedient, on a bend, also to set the vibration damper on the bend-inside wheel with a greater damping force, in order to prevent the wheel from jumping. In vibration dampers, the damping force of which can be adjusted via an electric actuator, the problem of how to set the bend-inside vibration damper with a greater damping force does not arise. Suitable sensor technology allows a controlled setting of the damping force on the basis of many different parameters which characterize the movement of the vehicle and/or of the wheel. By contrast, sensor technology cannot be used in a vibration damper, such as is known, for example, from DE 196 37 095 C2.  
         SUMMARY OF THE INVENTION  
         [0005]    The object of the present invention is to provide a damping device, in which it is possible to adjust the damping force, in particular during a rolling movement of a motor vehicle, and the problems known from the prior art are avoided.  
           [0006]    The object is achieved, according to the invention, in that the generator device comprises an equidirectional device which causes an equidirectional regulating variable to take effect on the adjustable damping valve independently of the compression direction.  
           [0007]    It is thereby possible that the generator device can be designed in a very simple way. Whether a compression movement or an expansion movement of the wheel is taking place is less important for the damping device.  
           [0008]    So that as few regulating or transmission elements as possible need to be used, the generator device is connected to a stabilizer. The stabilizer, by virtue of its principle, has one movement behavior in the case of a suspension movement of the wheels in the same direction or in the case of a suspension movement in a different direction, for example in the case of unilateral compression or on a bend. This movement behavior allows a controlled variation of the damping force in specific compression situations.  
           [0009]    In a first embodiment, the generator device is designed as a gear with coupling rods, an output coupling rod exerting a unilaterally directed regulating force independently of an input coupling rod.  
           [0010]    With a view to as few gear parts as possible, the stabilizer forms the input coupling rod.  
           [0011]    Furthermore, there is provision for the gear to have a coupling rod which is designed as a rocker and on which further coupling rods engage.  
           [0012]    In addition, a coupling rod has free motion for one force transmission direction in each case, so that the coupling rods within the gear can transmit a regulating force in only one direction.  
           [0013]    In an alternative embodiment, the equidirectional device has for each compression direction at least one working space filled with pressure medium, the pressure medium being conveyed into a control space of the adjustable damping valve through at least one pressure medium line by a displacer.  
           [0014]    In order to minimize the use of nonreturn valves and at the same time achieve the safeguarded functioning of the equidirectional device, there is provision for each working space to have a separate displacer, so that the movement of one displacer can be executed independently of a second displacer.  
           [0015]    In this case, the displacers assume their maximum stroke position when the vibration damper is in a defined compression position. Strict functional separation of the displacers is achieved by means of this measure. In a different compression position, only one displacer is moved and ensures that pressure medium is conveyed to the control space of the adjustable damping valve.  
           [0016]    In addition, the two working spaces have a separate pressure medium line to the control space, the pressure medium lines containing a throttle device. Different throttle settings can be carried out for each suspension direction by means of separate pressure medium lines. In principle, if this possibility is to be dispensed with, the pressure medium lines of the working spaces could be connected to one another and only one common pressure medium line to the control space of the adjustable damping valve be provided.  
           [0017]    In order to simplify the outlay for the construction of the equidirectional device, the working spaces are arranged in a common housing.  
           [0018]    Thus, there may be provision for the stabilizer to have a split design, one stabilizer portion being connected fixedly in terms of rotation to a pivoting generator shaft and a second stabilizer portion being connected fixedly in terms of rotation to the housing, and a displacer conveying pressure medium to the vibration damper within the housing as a result of the relative movement between the housing and the pivoting generator shaft.  
           [0019]    So as not to give rise to damping force adjustment on the adjustable damping valve whenever there is a slight suspension movement, the working movement of the displacer for the reduction of the working space is counteracted by a threshold-force.  
           [0020]    With a view to as favorable a utilization of the construction space as possible, the threshold-force is arranged within the working space.  
           [0021]    So that a softer damping force setting on the adjustable damping valve does not occur too quickly in the event of a reversal of the suspension movement, the pressure medium flows out of the control space of the adjustable damper through the throttle device back into the working space.  
           [0022]    For a rapid response to the adjustable damping valve, a nonreturn valve is connected in parallel to the throttle device.  
           [0023]    So that the overall outlay for adjusting the damping force for vibration damping can be kept low, a plurality of vibration dampers of one vehicle axle are connected to the equidirectional device.  
           [0024]    In a further development stage, a plurality of vibration dampers of a plurality of vehicle axles may also be connected to the equidirectional device.  
           [0025]    The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]    [0026]FIG. 1 shows a vibration damper with a laterally arranged adjustable damping valve;  
         [0027]    [0027]FIG. 2 shows a sectional illustration of the adjustable damping valve of FIG. 1;  
         [0028]    [0028]FIG. 3 shows an adjustable damping valve arranged in the vibration damper;  
         [0029]    [0029]FIG. 4 shows a hydraulic equidirectional device;  
         [0030]    [0030]FIG. 5 shows a compact solution of a hydraulic equidirectional device on the principle of FIG. 4;  
         [0031]    [0031]FIG. 6 shows the equidirectional device designed as a pivoting generator;  
         [0032]    [0032]FIG. 7 shows the pivoting generator in section;  
         [0033]    [0033]FIG. 8 shows a mechanical equidirectional device; and  
         [0034]    [0034]FIG. 9 shows a vibration damper with an adjustable damping valve for a mechanical equidirectional device.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    [0035]FIG. 1 illustrates a vibration damper  1  with a cylinder  3 , in which a piston rod  5  is arranged axially movably. The cylinder  3  is closed off downwardly by a bottom  7 . The piston rod  5  is led through a piston rod guide  9  out of the upper end of the cylinder  3 . Within the cylinder  3 , a piston unit  11  having a piston valve arrangement  13  is fastened to the piston rod  5 . The bottom  7  of the cylinder  3  is provided with a bottom-valve arrangement  15 . The cylinder  3  is encased by a container tube  17 . Between the container tube  17  and the cylinder  1  is formed an annular space  19  which constitutes a compensating space. The space within the cylinder  1  is subdivided by the piston unit  11  into a first working chamber  21   a  and a second working chamber  21   b . The working chambers  21   a ,  21   b  are filled with pressure liquid. The compensating space  19  is filled with liquid up to the level  19   a  and with gas above this. Within the compensating space  19 , an intermediate tube  23  forms a first line section, to be precise a high-pressure subsection  23   a , which is connected to the second working chamber  21   b  via a bore  25  of the cylinder  1 . Connected to this high-pressure subsection is a valve  27  which is mounted laterally on the container tube  17  and reacts as a function of pressure. A second line section, to be precise a low-pressure subsection, leads (not illustrated) from this valve to the compensating space  19 .  
         [0036]    When the piston rod  5  is extended upwardly out of the cylinder  3 , the upper working chamber  21   b  is reduced. Overpressure is formed in the upper working chamber  21   b  and can be decreased into the lower working chamber  21   a  by means of the piston valve arrangement  13 , as long as the valve  27  reacting as a function of pressure is closed. When the valve  27  reacting as a function of pressure is opened, liquid simultaneously flows from the upper working chamber  21   b  through the high-pressure subsection  23   a  and the valve  27  reacting as a function of pressure into the compensating space  19 . The damping characteristic of the vibration damper during the extension of the piston rod  5  therefore depends on whether the valve  27  reacting as a function of pressure is open or closed.  
         [0037]    When the piston rod  3  is retracted into the cylinder  3 , overpressure is formed in the lower working chamber  21   a . Liquid can pass from the lower working chamber  21   a  through the piston valve arrangement  13  upwardly into the upper working chamber  21   b . The liquid displaced within the cylinder  1  by the increasing piston rod volume is expelled into the compensating space  19  by the bottom-valve arrangement  15 . A rising pressure likewise occurs in the upper working chamber  21   b  since the throughflow resistance of the piston valve arrangement  13  is lower than the throughflow resistance of the bottom-valve arrangement  15 . With the valve  27  reacting as a function of pressure being open, this rising pressure can, in turn, flow through the high-pressure subsection  23   a  over into the compensating space  19 . This means that, with the valve  27  reacting as a function of pressure being open, even during retraction the shock damper has a softer characteristic when the valve  27  reacting as a function of pressure is open and a harder characteristic when the valve  27  reacting as a function of pressure is closed, in exactly the same way as when the piston rod  5  is extended. It should be noted that the direction of flow through the high-pressure subsection  23   a  of the bypass is always the same, irrespective of whether the piston rod  5  is retracted or extended.  
         [0038]    [0038]FIG. 2 shows an exemplary embodiment of the pressure-dependent valve  27  as an individual component. Within a tubular connection piece  29  arranged on the outside of the container tube  17  is mounted a bowl-shaped insert  31  which has a connection  33  to the high-pressure subsection  23   a  of the vibration damper. A valve surface  35  and at least one outflow orifice  37  to the compensating space  19  are machined on the bottom of the connection  33 .  
         [0039]    In this operating position, a valve body  39  is prestressed on the valve surface  35 . The valve body  39  is guided radially in a central passage orifice  41  of a pressure intensifier  43 , a valve body seal  39   a  separating the valve body front side from the valve body rear side. The valve body  39  has adjoining it a prolongation  45  which passes completely through the pressure intensifier  43  and which terminates in a pressure connection orifice  47  in a cover  49 . The pressure connection orifice  47  is connected to an equidirectional device not illustrated (see FIG. 4).  
         [0040]    The pressure in the pressure connection orifice  47 , referred to further as control pressure, acts on the pressure intensifier  43  which is guided in an axially floating manner in the bowl-shaped insert  31 . The pressure intensifier  43  is formed by a disk which carries a seal  51  on its outside diameter. For this purpose, the inside diameter of the tubular insert is machined as a guide surface  55  from the cover  49  as far as a first supporting surface  53 .  
         [0041]    A first spring element  59 , which preferably consists of layered flat disks, is arranged radially on the outside on the first supporting surface  53  and on a step  57  on the underside of the pressure intensifier  43 . A second spring element  61  is braced between a further step  63  of the pressure intensifier  43  and a second supporting surface  65 . The second supporting surface  65  is provided by a clamping ring  67 , the outside diameter of which is dimensioned with respect to the guide surface  55  so that there is a press fit between these surfaces.  
         [0042]    Starting from the seal  51 , the guide surface  55  forms, with the top side of the pressure intensifier  43  and with the cover  49 , a control space  69  in which the control pressure prevails. The control medium does not pass from the pressure connection orifice  47  directly into the pressure space, since the prolongation  45  is sealed off on the outside relative to the pressure connection orifice  47  by means of a seal  45   a . The prolongation  45  has a central throttle inflow duct  71  which reaches approximately as far as the valve body  39 . The pressure medium can flow from there through the slight gap between the pressure intensifier  43  and the prolongation  45  as far as a threaded connection which forms a setting device  73 . The threaded connection constitutes a continuation of the throttle inflow duct  71 . A further seal  45   b  prevents leakages of compressed air from the control space to a low-pressure space  89 .  
         [0043]    So that the setting device or the threaded connection operates without play, a prestressing spring  75  is arranged between the prolongation  45  and the top side of the pressure intensifier  43  and prestresses said two components of the threaded connection in such a way that the same threaded flanks are always in engagement. A supporting disk  77  serves as an abutment for the prestressing spring  75 .  
         [0044]    During assembly, a number of flat disks for the first spring element  59  are first laid onto the first supporting surface  53  in the bowl-shaped insert  31 . The pressure intensifier,  43  together with the seal  51 , is then introduced into the bowl-shaped insert  31 . The prolongation  45  of the valve body  39  is thereafter screwed through the insert into the pressure intensifier  43 . The connection  33  is subsequently pressed on the end face onto the tubular insert  31 . In a further work step, the second spring element  61  is laid onto the step  63 . The subassembly prepared in this way is clamped in a fixture which applies a periodically swelling force from below onto the valve body. The force may be introduced mechanically by means of a ram or hydraulically or pneumatically by means of a pressure medium.  
         [0045]    For a specific valve setting, a defined opening force is to be applied to the valve body. At the same time, the pressure intensifier  43  is pressed down via the introduced clamping ring  67  and the second spring element  61 . When the intended force gradient on the pressure intensifier  43  is reached, the means for introducing force to the valve body  39  and to the pressure intensifier  43  can be put out of operation. The spring elements are consequently set at an intended spring constant. The clamping ring  67 , by virtue of its press fit relative to the guide surface  55 , maintains the set position of the spring elements. Tolerances on the spring elements, the steps on the pressure intensifier  43  or the like, are compensated by means of this type of setting.  
         [0046]    The prestressing spring  75 , together with the supporting disk  77 , then has to be mounted. In a further work step, the position of the valve body  39  relative to the pressure intensifier  43  is fixed by means of the setting device  73 , in order to set a valve passage cross section between the valve body  39  and the valve surface  35 . There may already be provision for determining a valve passage cross section. Alternatively, the valve body  39  may rest, without force, on the valve surface  35  in the opening direction or a prestress may act on the valve body  39  by means of an adjusting movement during which the valve body  39  is unscrewed from the pressure intensifier  43 . For the setting movement, the prolongation  45  has at least one tool surface  79  at its end. An operating point on the force characteristic curve of the pressure intensifier  43  can be set by means of the setting device  73 .  
         [0047]    When the force settings on the structural unit described hitherto are concluded, the bowl-shaped insert  31  is introduced into the tubular connection piece  29 . The cover  49 , together with its outer cover seal  81 , is then pushed into the tubular connection piece  29 , until the cover  49  comes to bear on the bowl-shaped insert  31 . The cover seal  81  is intended to seal off the control space  69  relative to the surroundings in the region of the valve  27 . A cover retaining ring  83  holds the cover  49  in the closed position, the cover  49  itself being rotatable, so that a supply line, not illustrated, can be oriented into a desired position relative to the valve  27 .  
         [0048]    While the damper is in operation, damping liquid is displaced into the connection  33  of the valve  27  via the high-pressure subsection  23   a . The damping medium impinges onto an onflow surface  87  of the valve body  39  as a function of the desired damping force characteristic curve. The pressure on the onflow surface  87 , multiplied by the area of the latter, constitutes an opening force which takes effect on the valve body  39  and which acts counter to the resultant closing force arising from the control pressure in the control space  69  on the pressure intensifier  43  and the resultant spring force of the two spring elements  59 ;  61 . When the opening force is greater than the closing force, the valve body  39  is lifted off or an already opened valve body  39 , which in the pressureless state already permits a valve passage cross section, is lifted off further. The damping medium can flow into the compensating space  19  via the outflow orifices  37 .  
         [0049]    A static pressure due to gas being pressurized in the vibration damper, although also acting on the onflow surface  87  of the valve body  39 , nevertheless at the same time also acts on a valve body rear side  95 , so that only the differential surface composed of the onflow surface  87  minus the valve body rear side  95  remains as an active surface for the static pressure. In the case of an appropriate size difference between the pressure-loaded surface in the control space for the pressure intensifier  43  and the pressure-loaded surfaces on the valve body  39 , the influence of the static pressure can be ignored.  
         [0050]    The preceding description relates to the ideal situation. However, the situation cannot be ruled out where the seals  51  in the pressure intensifier and the seal  45   b  in the prolongation  45  of the valve body  39  no longer fulfill their required sealing function. So that a leakage out of the control space  69  into the low-pressure space  89  does not exert any opening force on the pressure intensifier  43  or the valve body  39 , the low-pressure space has a venting connection  97  between the low-pressure space  89  and a lower pressure level, as a rule the atmosphere surrounding the valve. The venting connection consists of portions  97   a ;  97   b  in the insert  31  and in the tubular connection piece  29 . Even when the tubular connection piece  29  is being welded to the container  23 , an oriented installation of the tubular connection piece  29  is ensured by the welding appliance having a positioning pin engaging into the portion  97   b . What is to be achieved thereby is that, in the case of a vibration damper standing essentially vertically, the portion  97   b  emerges from the tubular connection piece on the underside and therefore at the lowest point.  
         [0051]    The bowl-shaped insert  31 , too, must be installed so as to be oriented in position in the circumferential direction. For this purpose, the insert  31  has an installation orientation marking in the form of an axially running groove  101 , into which an antitwist device in the form of a pin  103  engages. During assembly, an incorrect installation position of the tubular connection piece  29  is recognized immediately, since the insert  31  comes to bear with its holding surface  105  on the pin  103  and cannot be introduced far enough into the tubular connection piece  29 . The insert  31  is twisted until the pin  103  engages into the groove  101  and a further introduction movement is possible.  
         [0052]    The pin  103  assumes a second function of holding an inflow throttle element  107 . In this case, the inflow throttle element  107  consists of a cap which is bent and therefore only partially covers the venting connection  97 . A radial flow path  109  is still available. At all events, the direct penetration of splash water or dust into the lower-pressure space  89  is effectively prevented. The situation cannot be ruled out where water condenses out of the air or splash water penetrates which likewise collects in the low-pressure space  89 . The water likewise flows from the insert  31  through the funnel-shaped widening  31   a  of the wall of the bottom out of the valve  27  into the open via the venting connection. Insofar as the inflow throttle element  107  is formed by a notched stud or a clamping pin, this has at least one groove or slot partially running essentially axially. This slot is entirely sufficient for venting the low-pressure space. Furthermore, the groove or the slot can be oriented in such a way that there is little likelihood that moisture will penetrate into the valve. A separate cap may then be dispensed with.  
         [0053]    [0053]FIG. 3 shows the piston-rod-side end of a vibration damper  1  which has the axially movable piston rod  5  within the cylinder  3 . A piston rod guide  9  delimits on the end face the cylinder and consequently the working chamber  21   b . Arranged within the piston rod guide  9  is the adjustable damping valve  27  which consists of a valve plate  111  and of a damping valve spring  113 . A fluid connection  115  to the compensating space  19  is formed within the piston rod guide and is enabled when the valve plate is lifted off from its valve seat by the pressure in the working space filled with damping medium.  
         [0054]    A piston rod seal  119  closes the entire vibration damper  1 . The piston rod seal  119  has a reinforcement and is supported on the valve plate  111  via a transmission sleeve  121 .  
         [0055]    The cylinder is followed axially by a sleeve-shaped carrier  123  which has a bottom  125 . The bottom  125 , the sleeve part and an annular web  127  of the carrier form, together with a piston  129 , the control space  69  which is filled with a pressure medium, for example oil or air, and can be loaded with a control pressure via a pressure connection  131 . The piston  129  is prestressed in the direction of the adjustable damping valve by the control pressure within the control space  69  and is supported via the piston rod seal  119  and the transmission sleeve  121  on the valve plate and consequently exerts a closing force on the adjustable damping valve. A seal against the loss of pressure medium is arranged on the inside diameter and on the outside diameter of the piston. Damping medium can flow into the compensating space  19  via the fluid connection as a function of the ratio of the closing force in the control space to the operating pressure in the working chamber  21   b.    
         [0056]    The carrier  123  has latching means  133  which, together with an abutment  135  of the vibration damper, form a latching connection. During assembly, the carrier  123  is simply pushed onto the vibration damper, until the latching means  133  latch elastically behind the abutment  135 . The carrier  123  is fixed axially in the demounting direction. However, the carrier  123  can be pressed further onto the vibration damper in the direction of the adjustable damping valve. The control pressure within the control space  69  ensures that the latching means  133  always bear on the abutment  135 . There is therefore no need for the carrier  123  to be secured axially any further. So that the control pressure does not subject the adjustable damping valve to too high a load, the piston  31  has an abutment  137  which limits the piston travel.  
         [0057]    FIGS.  1  to  3  disclose a vibration damper  1  which is adjustable as a function of the control pressure. It is to be documented that the adjustable damping valve can be executed at various points of the vibration damper.  
         [0058]    [0058]FIG. 4 is intended to describe an equidirectional device  139  for controlling the vibration damper  1 . The two subassemblies form the damping device. The equidirectional device  139  is activated by a stabilizer  141  and has two working spaces  143 ;  145  filled with a pressure medium, in each of which an axially movable displacer  147 ,  149  is arranged. The stabilizer  141  constitutes the generator device for the equidirectional device  139 . The two displacers  147 ,  149  are connected to the stabilizer  141 . The connection between the displacer and the stabilizer consists of a simple open contact connection. Only pressure forces can be exerted on the displacers  147 ,  149  from the stabilizer  141 . FIG. 4 illustrates a defined compression position of the vibration damper, in which both displacers  147 ;  149  assume their maximum extension stroke position and both contact connections are closed. When the angled end  151  of the stabilizer  141  moves in the direction A, the displacer  147  is pressed into the working space  143 , with the result that pressure medium is conveyed through a pressure medium line  153  to the adjustable damping valve  27 . The other displacer  149  maintains its operating position and does not move, since there is no contact with the angled end  151  of the stabilizer  141 . The pressure medium in the pressure medium line  153  flows through an open nonreturn valve  155  in parallel with a throttle  157  which may be adjustable. In the adjustable damping valve  27 , the pressure medium acts in the control spaces  69  in the way described previously.  
         [0059]    When the angled end  151  of the stabilizer  141  moves back in the direction of the defined compression position again, the pressure medium is pressed out of the control space  69  by the operating pressure in the vibration damper back in the direction of the working space  143 . The backflowing pressure medium must necessarily flow through the throttle  157  since the nonreturn valve  155  is closed. The throttle brings about an intended inertia in the adjustment of the damping force from a greater damping force to a lower damping force.  
         [0060]    When the angled end  151  of the stabilizer  141  moves in the direction B, the displacer  147  maintains its maximum extension stroke position and the displacer  149  is moved into the working space  145 . Once again, pressure medium flows through the pressure medium line  159  to the adjustable damping valve  27 , a throttle  163  and a nonretum valve  161  likewise being interposed. The throttle  163  and the nonreturn valve  161  are advantageous developments of the equidirectional device, but are not absolutely necessary. It is essential that pressure medium is always conveyed to the adjustable damping valve  27 , irrespective of the direction of movement of the angled end of the stabilizer  141 .  
         [0061]    [0061]FIG. 5 shows an equidirectional device on the principle of FIG. 4, in which the two working spaces  143 ;  145  are combined in a housing  165 . A coupling rod  167 , which is connected to the angled end  151  of the stabilizer  141 , passes through the two working spaces and is mounted in covers  169 ;  171  of the housing  165  which are arranged in each case on the end faces. The covers, with the displacers  147 ;  149  sealed off on the inside diameter and on the outside diameter, form, together with a sleeve of the housing, the working spaces  143 ;  145 . The housing, in turn, is arranged on the vibration damper  1  in an articulated manner. The cover  169  having the joint  173  has a venting orifice  175  for the back space  177  of the bearing point.  
         [0062]    The housing  165  has a separating web which serves as an axial abutment  179  for the displacers. In the defined level compression position, the two displacers  147 ,  149  bear on the separating web and consequently assume a maximum retraction position. The separating web may be formed in one part with the housing wall, but also by a retaining ring. The coupling rod has a peripheral flange  181  which bears in each case on the undersides of the displacers  147 ,  149 . During a stabilizer movement, the coupling rod  167  and consequently the flange  181  are pressed upwardly or downwardly against the displacers  147 ;  149 .  
         [0063]    The coupling rod  167  does not necessarily have to pass through both displacers. A bearing point in the lower cover  171  would be sufficient. In the design illustrated, in which both displacers are of annular design, two identical displacers may be used.  
         [0064]    A threshold-force spring  183  may be arranged within the working spaces  143 ;  145 . This spring generates a counterforce to the introduction of force of the stabilizer  141  or of the coupling rod  167 . What is to be achieved is that a particular force threshold first has to be overcome by the stabilizer  141  in order to achieve an adjustment of damping force. The spring used may be a helical spring or else a cup spring which are known per se.  
         [0065]    [0065]FIG. 6 shows a top view of a stabilizer  141 , the stabilizer consisting of two stabilizer portions, the torsion bars  141   a ;  141   b  of which terminate in the housing  165  of a pivoting generator. Starting from the housing, the pressure medium lines  153 ;  159  run to the vibration dampers  1 .  
         [0066]    [0066]FIG. 7 illustrates the housing  165  in section. With reference to FIGS. 4 and 5, the housing delimits at least two working spaces  143 ;  145 , in which the displacers  147 ;  149  are arranged slidably in the circumferential direction. The housing has, between the working spaces, a rib which serves as an abutment  179 . Furthermore, partitions  185  are provided, in which, together with the inner wall of the housing  165 , the displacers and the cylindrical surface of a pivoting generator shaft  187 , define the working spaces  143 ;  145 . A hub  189  for the connection of one of the stabilizer portions  141   a ;  141   b  is illustrated symbolically in the pivoting generator shaft  187 . FIG. 7 shows the position of the displacers  147 ;  149  in the defined compression position. When the vehicle body executes a rolling movement, a twisting movement between the pivoting generator shaft  187  and the housing  165 , which is fastened to the other stabilizer portion, occurs as a result of the connection of the stabilizer portions to the vehicle body and via the angled ends  151  on the wheel carrier. A wing  191  on the pivoting generator shaft  187  moves the displacers  147 ;  149  from the rib  179  in the direction of the partitions  185 , with the result that pressure medium is conveyed into the pressure medium lines  153 ;  159 .  
         [0067]    [0067]FIG. 8 illustrates in greatly simplified form a vibration damper  1  designed as an axle damper. A wheel carrier is connected to the cylinder  3  of the vibration damper, the vehicle body, not illustrated, being supported on the piston rod  5 . Connected to a vehicle axle is the stabilizer  141  which varies the damping force of the damping valve  27  (FIG. 9).  
         [0068]    The stabilizer  141  is fastened to a stabilizer holder  193  in an articulated manner and together with the stabilizer holder forms a rocker. Two coupling rods  195 ;  197  engage on the rocker. The stabilizer constitutes in functional terms an input coupling rod of a gear. An output coupling rod  199  acts on the damping valve  27  within the piston rod guide (FIG. 9). The two coupling rods  195 ;  197  have free motion ( 201 ;  203 ) in the form of a long hole. This ensures that, depending on the movement of the angled end  151  of the stabilizer  141 , in each case only one coupling rod exerts on the output coupling rod  199  tensile forces which then bring about an adjustment on the damping valve  27 .  
         [0069]    [0069]FIG. 9 shows by way of example the design of a vibration damper  1  in the arrangement according to FIG. 8. In principle, the output coupling rod  199  activates the valve plate  111  within the piston rod guide  9  via the transmission sleeve  121 . The piston rod guide allows the damping medium to flow out of the upper working chamber  21   b  into the compensating space  19 . A gas bubble  205  is introduced within the compensating space in order to prevent foaming.  
         [0070]    Thus, while there have been shown and described and pointed out fundamental novel features of the present invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the present invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Substitutions of elements from one described embodiment to another are also fully intended and contemplated. It is also to be understood that the drawings are not necessarily drawn to scale but that they are merely conceptual in nature. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.