Patent Publication Number: US-8978844-B2

Title: Adjustable damping valve arrangement

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed to an adjustable damping valve arrangement for a vibration damper. 
     2. Background of the Invention 
     U.S. 2011/0168935 A1 relates to a generic adjustable damping valve arrangement in which its main stage valve body has two pressure-impinged surfaces acting in closing direction. Among the advantages offered by this type of construction of the main stage valve is that the construction of the opening surface in rebound direction is simplified as a result of the enlarged closing surface. As a result of this type of construction of the damping valve arrangement, the damping force that can be achieved in compression direction is increased. This increase in damping forces can certainly be desirable, e.g., when a larger damping force range must be covered at a given actuator force. 
     However, there is also a demand for damping force characteristics which are as soft as possible. Of course, in this case recourse could be had again to a constructional form with only one pressure-impinged surface in closing direction at the main stage valve body. However, this option is not expedient from a cost perspective. 
     It is thus an object of the present invention to make it possible to decrease the damping force level in a generic damping valve arrangement. 
     SUMMARY OF THE INVENTION 
     According to the invention, this object is met in that the flow connection is carried out so as to be functionally parallel to an incident flow of the main stage valve, wherein a flow-in opening of the flow connection is oriented at an angle of at least 60° to the flow direction into the main stage valve so that only a static pressure acts on the closing surface of the main stage valve. 
     A reduced pressure on the pressure-impinged closing surface can be achieved by a simple guiding of flow inside the damping valve arrangement. An angle of 90° is preferably used. 
     To improve the effect of the pressure reduction, a deflecting profile is arranged upstream of the flow-in opening in flow direction. 
     In a further advantageous embodiment, the deflecting profile is executed on an annular element of the damping valve arrangement. Optionally, the annular element can be executed in the damping valve arrangement, i.e., appreciably different damping force characteristic ranges can be covered by a damping valve arrangement which is identical per se. 
     According to an advantageous embodiment, the annular element has channel portions of the flow connection. This simplifies production efforts for the flow connection inside the damping valve arrangement. 
     A collecting channel running in circumferential direction is arranged downstream of the flow-in opening and is connected to individual channels of the flow connection so as to allow any installation position for the annular element. 
     When two pressure-impinged closing surfaces are provided at the main stage valve, for example, a closing surface can also be connected to the incident flow opening for an incident flow direction. However, there is also the advantageous option of connecting a plurality of pressure-impinged closing surfaces to the incident flow opening. The larger the pressure-impinged surface or surfaces, the greater the achievable effect for the reduction of damping force. 
     At least two pressure-impinged closing surfaces can also be arranged in series with respect to the flow path. This type of construction leads to the advantage that both pressure-impinged closing surfaces are influenced by one incident flow opening. 
     A particularly large difference in damping force between damping during a compression movement and damping for a rebound movement is achieved when a flow-in opening is formed for only one working space. 
     In an alternative embodiment, a throttle is arranged in the flow connection. For example, the throttle can be constructed in a sleeve which can be pressed into the flow connection. 
     Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described more fully below with reference to the drawings in which: 
         FIG. 1  shows an adjustable damping valve arrangement with an incident flow opening; 
         FIG. 2  shows adjustable damping valve arrangement with two pressure-impinged surfaces arranged in series; and 
         FIG. 3  shows an auxiliary valve body as individual part. 
     
    
    
     DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
       FIG. 1  shows a damping valve arrangement  1  which is fastened, e.g., to a piston rod  3  of a vibration damper, shown only partially. The damping valve arrangement  1  comprises a piston  5  which divides a cylinder  7  into a working chamber  9  on the piston rod side and a working chamber  11  remote of the piston rod, both of which working chambers  9 ;  11  are filled with damping medium. In this embodiment example, the damping valve arrangement is fastened to the piston rod  3 , but the invention is not limited to an arrangement of this kind. 
     An actuator  15  of optional design is arranged in an outer housing  13 . Serving as actuator in this example is a magnetic coil  17  which exerts a force on an axially movable armature  19 , this force being transmitted to a multiple-part auxiliary valve body  21  of an auxiliary valve  23 . The design of the auxiliary valve body is described in detail in connection with  FIG. 3 . At least one valve spring—in this variant, two opposing valve springs  25 ;  27  are used—preloads the auxiliary valve body  21  in the lift direction with respect to an auxiliary valve surface  29  of the auxiliary valve  23 . The actuator  15  acts in the closing direction of the auxiliary valve  23 . The force of the at least one valve spring  25 ;  27  and the force of the actuator  15  form a resultant force which acts on the auxiliary valve body  21  in the lift direction. 
     An auxiliary valve closing spring  30  impinges on an auxiliary valve seat body  32  in closing direction regardless of the actuator setting. 
     A stepped opening  33  in which a main stage valve body  35  of a main stage valve  37  can execute an axial movement is formed in an inner housing  31  of the damping valve arrangement  1 . The main stage valve body  35  has a guide sleeve  39  whose back side  41  forms a surface A CloseD  that is pressure-impinged by damping medium. Further, the main stage valve body  35  has a radial shoulder  43  which has an additional pressure-impinged surface A CloseD2  in the direction of the back side  41 . 
     In a neutral position of the piston rod  3 , i.e., without opening force, the main stage valve body  35  contacts a valve seat surface  45  of an axially movable valve ring  47  which contacts a housing-side valve seat surface  49  at the side of the axially movable valve ring  47  facing in direction of the working chamber  11  remote of the piston rod. 
     The main stage valve body  35  is formed of a plurality of parts. An outer cup  51  forms the guide sleeve  39  and the radial shoulder  43 . In a separation plane, an inner disk  53  defines with the cup  51  a radial damping medium flow path  55  between the additional pressure-impinged surface A CloseD2 , as part of the main stage valve, and a control space  57 , as part of the auxiliary valve, whose outlet cross section is determined in direction of a rear space  59  by the valve body  21 . 
     The additional surface A CloseD2  of the main stage valve body  35  can be acted upon with damping medium via at least two flow paths. A first feed flow channel  61  is formed directly in the main stage valve body  35  as an axial passage. An out-flow channel  63  extends inside the main stage valve body  35  between the rear space  59  of the main stage valve  37  and the damping medium flow path  55 . 
     A flow connection  65  of the rear space  59  to the working chamber  11  remote of the piston rod inside a connection sleeve  66  between the outer housing  13  and the piston  5  is controlled by an emergency operation valve  67 . The emergency operation valve  67  is formed by a valve ring  69  which is lifted from an emergency operation valve seat surface  73  by the actuator  15  against the force of at least one closing spring  71 . Even a slight application of energy is sufficient for the actuator  15  to achieve the lift movement of the valve ring  69 . The auxiliary valve closing spring  30  is also supported axially at the valve ring  69  so that there is a slight closing force of the auxiliary valve closing spring  30  when the emergency operation valve  67  is open. In this example, the magnetic force of the magnetic coil  17  acts on the valve ring  69 . As a result of apt dimensioning of the spring forces and magnetic forces, a strict separation can be achieved between an emergency operating state and a normal operating state. In this way, the flow path between the rear space  59  and the working chamber  11  remote of the piston rod can be influenced by means of the emergency operation valve  67 . 
     At least one connection orifice  75  leading from the working chamber  9  on the piston rod side to the pressure-impinged surface A ÖZ  at the underside of the radial shoulder and to the control space  57  is formed in the connection sleeve  66  of the damping valve arrangement  1 . For this purpose, the main stage valve body  35  has at least one axial opening  77  in the region of the radial shoulder  43 . 
     With the damping medium flow path  55  and the feed flow channel  61  for two separate incident flow paths A ÖZ  and A ÖD , the auxiliary valve also has separate flow connection portions to the control space  57 . A check valve  79  and a damping valve  81  functioning as a check valve are arranged in the feed flow channel  61  and in the flow-off channel  63  so that damping medium does not escape through the feed flow channel  61  and flow-off channel  63  in the main stage valve body  35  in direction of the working space  11  remote of the piston rod when there is an incident flow via the connection orifice  75 . In so doing, the damping valve  81  is connected to the rear space  59  by the flow-off channel  63 . During a lift movement of the main stage valve body when the rear space is closed, the damping valve  81  releases the flow path for a flow of damping medium out of the rear space  59  in direction of the additional surface A CloseD2  in connection with a damping force. 
       FIG. 3  is limited to a section from  FIG. 1 . The auxiliary valve body  21  comprises a shaft portion  83  which forms an interference fit with the armature  19 . The shaft portion  83  is constructed as a hollow body in order to supply a back side of the armature  19  with damping medium for hydraulic pressure compensation. 
     The shaft portion  83  is adjoined by a spring holder  85  which carries a spring element  87 . The spring holder  85  has a guide pin  89  in the direction of the shaft portion  83 , which guide pin  89  engages in a radial positive-engagement connection with a guide surface  91  of the shaft portion  83 . 
     The guide pin  89  has a fastening flange  93  for the spring element  87 . The spring element  87 , which is constructed as a disk spring, is centered together with the auxiliary valve seat body  32  by a radial wall  95  as part of the fastening flange  93 . The spring element  87  acts upon two portions of the auxiliary valve body  21  at a distance, namely the auxiliary valve seat body  32  and the shaft portion  83 . The spring holder  85  contacts the shaft portion  83  axially without clearance after the final assembly of the damping valve arrangement  1 . 
     The spring holder  85  has a free space  97  for receiving a spring path of the spring element  87 . For this purpose, the fastening flange  93  is constructed with a cone. The disk spring  87  is supported by its outer diameter at the cone. The cone forms a supporting surface  99  for limiting the deformation of the spring element  87 . 
     The wall  95  of the fastening flange  93  is constructed so as to be somewhat longer axially than the structural height of the disk spring  87  and of the auxiliary valve seat body  32 . A protruding portion serves for a positive-engagement connection so that the spring holder  85 , the spring element  87  and the auxiliary valve seat body  32  form a constructional unit. 
     The auxiliary valve seat body  32  is constructed as a solid component and has a closure region  101  projecting into the control space  57  ( FIG. 1 ). It adjoins a disk body  103  which extends radially up to the wall  95  of the spring holder  85 . A central contact face is formed for the spring element  87  on the top side of the auxiliary valve seat body  32  facing in direction of the spring holder  85 . Adjoining radially outwardly is a conical transition  105  which likewise receives the deformation path of the disk spring  87 . 
       FIG. 1  further shows that a clamping pin  107  of the main stage valve body  35  preloads at least one valve disk  109  of the damping valve  81  at least indirectly in closing direction. Formed at the clamping pin  107  is a circumferential collar  111  which preloads at least one flexible valve disk  109  of the damping valve  81  on a valve seat surface. The preloading of a check valve spring  113  does not depend on the preloading of the flexible valve disk  109 . The clamping pin  107  can be secured by an interference fit in the main stage valve body  35 . The loading capacity of the interference fit is appreciably greater than the preloading force on the damping valve  81 . Alternatively, a preloading spring  115  can be arranged axially between the clamping pin  107  and the inner disk  53  of the main stage valve body  35 . The preloading force of the preloading spring  115  is likewise greater than the required preloading force on the damping valve  81 . 
     There are four basic operating states to be considered which will be described with reference to  FIG. 1 . A first operating state of the damping valve arrangement  1  is characterized by an incident flow proceeding from the working chamber  11  remote of the piston rod via a passage  117  to the valve ring  47  and main stage valve body  35  in order to lift the valve ring  47  and the main stage valve body  35  jointly in opening direction. Via passage  117 , the damping medium flows mostly to the main stage valve body  35 . A volume flow controlling the function of the main stage valve  37  flows in the direction of at least one flow-in opening  119  of the flow connection  65 . The flow-in opening  119  is oriented at an angle of at least 60° to the flow direction to the main stage valve  37  and is arranged at an appreciable distance upstream thereof with respect to the flow path to the main stage valve  37 . In this concrete embodiment, the angle is virtually 90°. Consequently, only a static pressure acts upon the closing surfaces A CloseD ; A CloseD2  of the main stage valve  37 . A deflecting profile  121  is arranged in front of the flow-in opening  119  in the flow direction. The deflecting profile  121  and the flow-in opening  119  are constructed on an annular element  123 . Use of this annular element  123  is optional. This affords the possibility of covering two distinctly different damping force characteristic ranges with an otherwise identical damping valve arrangement  1 . The pressure level on the closing surfaces of the main stage valve body is reduced by the annular element  123  with the result that the damping force characteristic tends to be softer. Alternatively, by dispensing with the annular element  123 , both the static and dynamic pressure inside the damping valve arrangement can be made use of so that the pressure which is increased in comparison also has a greater hydraulic closing force and, therefore, there is also a harder damping force characteristic of the damping valve arrangement  1 . 
     Downstream of the flow-in opening  119 , the annular element  123  has a radial channel portion  125  which forms part of the flow connection  65 . Further, a collecting channel  127  which extends in circumferential direction and is connected to individual channels of the flow connection  65  is arranged downstream of the at least one flow-in opening  119 . 
     In this embodiment form, the flow-in opening  119  is effective only for the pressure-impinged closing surface A CloseD . The additional pressure-impinged surface A CloseD2  is supplied directly via the feed flow channel  61  with damping medium under static and dynamic pressure. 
     Further, the use of the flow-in opening  119  oriented according to the invention is realized only for the incident flow from the working space  11  remote of the piston rod. 
     The emergency operation valve  67  is switched on, i.e., lifted from its emergency operation valve seat surface  73  as in the illustrated position, and the actuator  15  acts against the force of the valve springs  25 ;  27 . The preloading of the auxiliary valve closing spring takes on the minimum magnitude so that the valve closing spring has practically no effect on the normal operating function of the damping valve arrangement. The damping medium flows along the first feed flow channel  61  in the valve body  35  and the opened check valve  79 , then further along the damping medium flow path  55  to the additional valve closing surface A CloseD2 . A first closing force component exerts the pressure on this valve closing surface A CloseD2 . Further, damping medium flows through the flow connection  65  in the connection sleeve  66  and through the opened emergency operation valve  67  into the rear space  59 . The damping valve  81  for the additional pressure-impinged surface A CloseD2  is closed owing to the incident flow through the feed flow channel  61 . As was already described, the back side  41  of the main stage valve body  35  forms the pressure-impinged surface A CloseD  that is acted upon by the static pressure in the working space  11 . The closing force acting on the main stage valve body  35  is composed of the resulting closing force, which acts directly on the back side  41  of the main stage valve body  35  via the auxiliary valve body, and the pressure forces on surfaces A CloseD  and A CloseD2 . A surface A ÖD  at the valve ring  47  is slightly larger than the sum of surfaces A CloseD  and A CloseD2  so as to exclude blocking of the lift movement of the main stage valve body  35  due to the pressure ratios. The pressure in the control space  57  of the main stage valve body plays no part in this incident flow direction of the damping valve arrangement because the auxiliary valve is bypassed by the flow connection  65  to the rear space  59 . 
     Particular with minimal energizing of the actuator  15  and with an incident flow of the main stage valve body  35 , the auxiliary valve seat body  32  can quickly move slightly to the shaft portion  82  against the small closing force of the spring element  87 . The main stage valve body  35  can follow this movement and take up a passage. The inertia of the armature  19  in this case does not affect this initial movement of the main stage valve body  35  because the spring element  87  functions in a series connection with the armature  19 . When the relative movement of the auxiliary valve seat body  32  toward the shaft portion  83  is concluded as intended by operation, the spring element  87  contacts the spring holder  85 . 
     A second operating state concerns the emergency operating state of the damping valve arrangement  1  and an incident flow of the damping valve arrangement  1  proceeding from passage  117 . The emergency operation valve  67  is closed due to the absence of energy supply via the actuator  15 . The auxiliary valve seat body  32 , as part of the auxiliary valve body  21 , is guided so as to be slightly displaceable axially inside the auxiliary valve body  21 . In the deenergized state of the magnetic coil  17 , the valve springs  25 ;  27  hold the shaft portion  83  of the auxiliary valve body  21 , considered statically, i.e., without incident hydraulic flow, at a maximum distance from the auxiliary valve seat surface  29 . Therefore, the auxiliary valve seat body  32  could occupy a maximum lift position when loaded even by the slightest pressure proceeding from the control space  57 . When the emergency operation valve is closed, however, the preloading of the auxiliary valve closing spring  30  is maximized. Regardless of the dimensioning of the valve springs  25 ;  27 , the auxiliary valve closing spring  30  moves the auxiliary valve seat body  32  into a closed position on the auxiliary valve surface  29 . The rear space  59  is accordingly closed off from any incident flow via the control space  57  and flow connection  65 . As in the normal operating state, the damping medium reaches the additional pressure-impinged surface A CloseD2  via the feed flow channel  61  in the main stage valve body  35  and the open check valve  79 . In order that the main stage valve body  35  together with the valve ring  47  can lift from the housing-side valve seat surface  49 , the damping valve  81  in the main stage valve body  35  opens so that damping medium which is displaced from the rear space  59  can flow off via the flow-off channel  63  in main stage valve body  35  in direction of the additional pressure-impinged surface A CloseD2 . Accordingly, the main stage valve cannot open quickly in an uncontrolled manner, but only after overcoming the damping force of the damping valve  81 . When the motion of the piston rod is reversed, the opening pressure on the main stage valve body  35  decreases and a closing spring  129  moves the main stage valve body quickly back into the closed position with open check valve  79 . 
     The third operating state concerns an incident flow of the damping valve arrangement  1  proceeding from the working chamber  9  on the piston rod side and open emergency operation valve  67 . The damping medium flows through the connection orifice  75  in the connection sleeve  66  to the pressure-impinged surface A ÖZ  at the radial shoulder  43  and then to the pressure-impinged surface which now functionally forms a closing surface A CloseZ . The pressure-impinged surface at the radial shoulder of the main stage valve body is operative for both incident flow directions of the damping valve arrangement. Depending on the energy supply of the actuator  15 , there ensues an auxiliary valve position by which, in turn, a control pressure in the control space  57  and accordingly also at the pressure-impinged surface A CloseZ  can be controlled. The pressure acting on an annular surface A ÖZ  opposes the pressure acting in the closing direction on surface A CloseZ . Because of the outlet throttle  86  which now functions as an inlet throttle, there is a pressure gradient between the pressures at surfaces A ÖZ  and A CloseZ  when the auxiliary valve  23  is open, so that the hydraulic opening force at the main stage valve body  35  is always somewhat greater than the hydraulic closing force. The pressure in the connection orifice  75  also acts on the valve ring  47  which is accordingly pressed on the housing-side valve seat surface  49 . Therefore, the main stage valve body  35  lifts from the valve seat surface  45  of the valve ring  47 . With its check valve function, the damping valve  81  prevents a hydraulic short circuit of the auxiliary valve  23 . The function of the spring holder  85  is identical to that described in the first operating state. 
     The damping medium flowing out of the control space  57  through the auxiliary valve  23  arrives in the rear space  59  and through the open emergency operation valve  67  and flow connection  65  in the connection sleeve  66  into the working chamber  11  remote of the piston rod. Consequently, the rear space  59  has an inlet and an outlet with the working chamber  11  of the vibration damper. 
     In the fourth operating state, the feed flow again takes place via the connection orifice  75  in the connection sleeve  66 , but the emergency operation valve  67  is closed. The flow path to the auxiliary valve  23  corresponds to the description of the third operating state. In contrast, the auxiliary valve  23  is closed due to the auxiliary valve seat spring  30 . The closing spring  129  ensures that the main stage valve body  35 , together with the valve ring  47 , is seated on the housing-side valve seat surface  49 . This prevents a hydraulic short circuiting between the working chambers via the connection orifice  75 . The damping medium arrives in the rear space  59  whose outlet is blocked by the closed emergency operation valve  67 . The damping valve  81  also remains closed. A flow path  131  to a pressure limiting valve  133  by which a defined pressure level in the rear space  59  can be determined is formed in the valve ring  69  of the emergency operation valve  67 . The pressure level in the rear space  59  and, therefore, on the back side  41  of the main stage valve body  35  and on the pressure-impinged surface at the radial shoulder A CloseZ  determines the closing force in emergency operation of the damping valve arrangement  1 . It is clear from a comparison of the second operating state and fourth operating state that the emergency operation valve  67  is effective in only one incident flow direction of the damping valve arrangement  1  via the connection orifice  75 . Tests have shown that this design of the damping valve arrangement  1  is suitable for reliable operating behavior of a vibration damper. 
       FIG. 2  shows a modification, based on  FIG. 1 , in which the two pressure-impinged closing surfaces A CloseD ; A CloseD2  are arranged in series with respect to the flow path proceeding from the working space  11  remote of the piston rod via the flow connection  65 . There is no direct incident flow from the working space remote of the piston rod via the feed flow opening  61  as in  FIG. 1 . Accordingly, it is always only the static pressure that acts on both pressure-impinged closing surfaces during an incident flow from the working space remote of the piston rod. 
     Alternatively or in addition to the annular element  123 , the flow connection to the two pressure-impinged closing surfaces A CloseD ; A CloseD2  can have a throttle  135  which once again reduces the pressure level proceeding from the static pressure in the working space remote of the piston rod. The functional difference between the throttle  135  and the flow-in opening  119  consists in that the flow-in opening is also effective when there is no flow connection between the working space and the pressure-impinged surface, but rather a stationary connection as is the case, e.g., when the emergency operation valve  67  is closed. 
     Thus, while there have shown and described and pointed out fundamental novel features of the 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 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. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.