Abstract:
A device for damping vibrations, in particular a torsion vibration damper with a primary component and a secondary component, coupled together through a torque transfer device and a damping coupling device. The torque coupling device includes a ramp mechanism for converting a rotation of one of the two elements, primary component or secondary component, into an axial force proportional to the input moment, which acts upon the other element. A device for compensating the resulting axial forces for generating an opposing force, opposing the resulting axial force, wherein the input moment is designed for a mean input torque. A conversion device is also provided, which directly converts an occurring force difference between the resulting axial force and the opposite force into a control variable for operating an actuation device in the device for damping vibrations, whereby an adaptation of the opposite force is performed.

Description:
This claims benefit of German Patent Application 10 2006 048 809.1, filed Oct. 16, 2006. 
     The invention relates to a device for damping vibrations, in particular to a torsion vibration damper. 
     BACKGROUND 
     Devices for damping vibrations for application in motor vehicles are known in a plurality of embodiments. In this context, a differentiation made between active and passive damping systems. Passive damping systems are most widely used. These are substantially comprised of a primary section and a secondary section in the form of flywheels, which are coupled amongst each other through a spring- and damping coupling. The spring- and damping coupling is thus created through spring units, wherein at least one circumferentially acting coil spring is provided. Among this group are also the so-called dual mass flywheels, wherein the two flywheel masses are supported on each other through a bearing. The application of this passive vibration insulation, however, is subject to certain restrictions. On the one hand, it is required that the damping element has as little stiffness as possible for achieving good vibration insulation, on the other hand, such a device operates like an elastic clutch, since it also has to transfer torque, wherein the transfer of large moments with a simultaneously restricted rotation angle between input and output requires a relatively stiff system. This contradicts the desired damping properties. It would therefore be advantageous to create a damping system with low stiffness for uneven rotations, and simultaneously with high stiffness, in order to be able to transfer the mean torque of the drive motor. For solving this problem, therefore, so-called active damping systems are proposed. These are being used in the area of suspensions for mechanisms and machinery. In an exemplary manner, the Patent document DE 69 724 691 is referred to in this context, wherein the drive motor is stabilized through a special control system in this embodiment. This, however, causes a direct function change at the drive motor, which is not desired for reasons of system modularity, and in order to avoid unpredictable dependencies with respect to the basic conditions, predetermined by components supplied by third party vendors. 
     Furthermore, mechanical solutions are known, which do not apply circumferentially acting coil springs, but an axial thrust is imparted through a respective ramp function from the one flywheel of the torsion vibration damper to the other flywheel, this means typically from the primary component to the secondary component. When an axially acting spring is used, the vibration energy can thus be stored in a preliminary manner. The generation of the axial thrust is performed through providing at least one lens shaped depression, extending in circumferential direction at least on one face side of one of the discs, which are also called ramps or double ramps, when they are symmetrically formed in both directions in circumferential direction. In such a double ramp, a roller element is disposed, which touches the front face of the respective adjacent disc, even at the deepest point of the double ramp. The roller element is typically provided as a ball. With this respect, reference is made to patent document DE 100 17 688 A1, among others. Thus, an axial thrust is generated through the relative rotation of the one disc relative to the other disc, which is converted into a torque again, after the imparted torque peak has subsided. Since the rotation is generally converted into an axial motion in ramp mechanisms, and a hydraulic pressure cavity is used for compensating the axial reaction and for transferring the torque, the compression pressure generally has to be controlled proportional to the mean input torque. Therefore it is required, however, to detect the input torque at the primary element and to filter it. From this variable, then the control variable for the pressure control or regulation, in particular of the compressing pressure towards at the secondary side, and thereby, the control variable for controlling or providing the pressure is formed. This control system requires a relatively complicated sensor system and electronic processing of the detected variable. Therefore the entire system is very complex. 
     SUMMARY OF THE INVENTION 
     An object of the invention provides refining a device for damping vibrations with an integrated ramp mechanism of the kine described above, so that the disadvantages are avoided, in particular, to implement an active damper with minor engineering and control efforts. A control system would be ideal, which does not require additional detection of certain actual values, and the required computation of target and control variables resulting from them. 
     The device for damping vibrations includes a primary component and a secondary component, which may be coupled amongst each other through torque transfer devices and through damping coupling means. The coupling for torque transfer may be performed through a ramp mechanism for converting a rotation caused by the induction of an input torque M in  at one of the two elements, the primary element or the secondary element, into an axial force F axial , proportional to the input moment, wherein the axial force that may be effective relative to the other element, the secondary element or the primary element, is converted into a torque to be transferred, wherein the torque is supported through a device generating an opposite force F axial-opposing  at the other element, primary element or secondary element, which opposes the resulting axial force F axial . The means are adjusted to a predefined mean input torque M in-mean  to be transferred, so that there may be force equilibrium at the ramp mechanism, when this moment occurs. According to the invention a conversion device may be provided, converting an occurring force difference between the resulting axial force F axial  and the opposing force F axial-opposing  into a control variable Y for operating an adjustment device in the device for damping vibrations for changing the opposing force F axial-opposing . 
     A solution according to the invention allows a direct adaptation of the required opposing force, depending on the size of the deviation from a mean input torque, for transferring the higher or lower input torque without the complex determination of the particular variables and processing in a control system. 
     Preferably, a force difference is directly converted into a distance s, or an angle at the conversion device. Thus the force difference may already causes a translatoric displacement of the particular ramp elements, so that in a particularly simple embodiment, this distance can be used directly as a control variable for controlling the adjustment device. 
     Preferably the control is performed in a purely hydraulic manner, this means without electronic data transfer. The hydraulic control device therefore includes a device for generating the opposing force F axial-opposing  and an adjustment device for changing the opposing force, including an actuating element, coupled with the conversion device. The device for generating the opposing force F axial-opposing  typically includes at least one piston element, and a pressure cavity, which can be filled with a pressure medium for loading the piston element, wherein the pressure cavity can be alternatively coupled through a switching device with a pressure medium source, or with a relief device, or alternatively only with a storage, not coupled with the relief device or the pressure medium source. Thus the storage may simultaneously functions as a device for damping coupling. 
     The actuation device in its simplest form may include a valve device, including at least three operating positions, the first operating position for coupling the pressure cavity with the storage, the second operating position for coupling the pressure cavity with a pressure medium source, and a third operating position for coupling the pressure cavity with a relief device. The valve device can thus be provided as a 3/3 way valve. For fine adjustment of the opposing force, this can preferably be operated continuously. Depending on the form of the piston surfaces and the strokes, the smoothness of the adjustment can be determined. 
     The system is thus in equilibrium in the mean area of the relative rotation angle, this means when the compressing force and the force resulting from the input moment, typically at the primary component, are equal in size. In this relative rotation angle range, the system is passive and torque may be transferred. Then there is neither a connection between the pressure chamber or the hydraulic storage and the tank, nor between the hydraulic storage and the pressure medium source. Thus, the pressure chamber operates as an elastic element together with the storage, in order to assure an insulation of the vibrations. In this case, the vibrations may be quasi extinguished through the storage. 
     When the input torque increases, an axial force is generated, which may be higher than the pressure force acting upon the secondary component in the pressure chamber. Consequently, the ramp and the piston move, so that the connection between the pressure chamber and the pressure medium source may be established. The compression pressure increases through the coupling with the pressure medium source, until the pressure equilibrium is reestablished. The system is passive again now. Analogously, the same processes occur, when the mean input torque decreases. In this case, the equilibrium may be reestablished through the connection between the pressure chamber and the tank as a relief device. 
     A solution according to the invention thus allows an adaptation of the pressure in the pressure- or compression chamber to the changed input torque, depending on the magnitude of the deviation from a mean input torque. Thus, the change directly functions as a control variable for the operation of a valve device. 
     There are numerous possibilities for a respective engineering design. Preferably, however, also here a high degree of component integration is selected. It is advantageous in particular, to integrate parts of the pressure chamber into the ramp element or into the secondary element. The same is true for the actuation device, in particular the valve device. In this case, a very compact design can be realized, and the particular required channels can be provided directly in the system in direct dependency, wherein a relative motion allows blocking or opening of these channel cross sections. 
     The valve device can be implemented in various manners. In the simplest case, these include at least three operating positions, and they are provided as a 3/3 way valve. This can be operable only in increments, this means between the particular operating positions, or also continuously between the particular operating conditions. 
     The conversion device is preferably formed by an element involved in the torque transfer, in particular a ramp element. Thus, preferably the second ramp element is selected, since here the axial force, and the opposing force directly become effective. The conversion device can thus also be formed by the secondary component, coupled torque proof with the ramp element, or by the ramp element, when it is provided as a secondary component. 
     According to a particularly advantageous embodiment, the valve device, the piston element, and the ramp element are integrated in the secondary component. In this embodiment, the system includes a so-called fixed ramp, this means it is fixed in place in axial direction, and forms the input and is typically formed by the primary element, as well as, a so-called distance ramp, forming the output, which is connected with the secondary component, preferably, torque proof, or forms it directly. Furthermore, the valve device and a storage are provided. Thus, for simplification, the piston of the valve device is provided as a travel ramp. The travel ramp is thus formed by a wall of the compression chamber, which can be moved in axial direction. In order to be able to transfer the torque, it is thus required that the secondary component is connected with the travel ramp in circumferential direction, in axial direction, however, it is provided movable relative to the secondary component. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is subsequently described with reference to figures. Therein the following is illustrated. 
         FIG. 1  illustrates the basic layout of a system according to the invention for active vibration damping in a simplified schematic depiction; 
         FIG. 2  illustrates a possible design implementation of an embodiment according to  FIG. 1  in a simplified schematic depiction. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates the basic layout of a device  1  for damping vibrations with an integrated ramp mechanism  2  in a schematic simplified depiction. The device  1  comprises a primary component  3  and a secondary component  4 , which are coupled through means  5  for torque transfer and furthermore through means  6  for damping coupling. Thus the ramp mechanism  2  comprises an input section and an output section, wherein these are either formed by the primary section  3 , or the secondary section  4 , depending on the force transmission device, or at least form a physical unit, this means they are coupled torque proof, with these elements as ramp elements. Typically, the primary part  3  and the secondary part  4  are provided as flywheels. At least one of the two flywheels, preferably both, or the ramp elements connected torque proof with them, have lens shaped indentations symmetrically extending in circumferential direction at the face sides  7  and  8 , pointing toward each other, in which indentations at least one roller element  11  is disposed, preferably in the form of a ball, which is in contact, also at the deepest point of the lens shaped indentation, with the respective adjacent face surface  8  or  7  at the other component, the primary component  3  or the first ramp element, or the secondary component  4 , or the second ramp element, or vice versa, and thus serves for torque transmission. The ramp elements are either the primary component  3 , or the secondary component  4 , or elements connected torque proof with them, on which the ramp surfaces  9 ,  10  are provided. The indentations are not shown here in detail. Only the ramp surfaces  9  and  10 , which are created by them, and which are disposed in parallel with each other, and movable relative to each other in circumferential direction, are visible, which operate like slanted surfaces movable relative to each other. Since the primary component  3  is typically connected torque proof with the input side, and it is provided in axial direction without a possibility for axial translatoric movement, this means it is fixated in axial direction with respect to its position, a rotation of the primary component  3  in circumferential direction causes an axial thrust upon the secondary component  4 , which is transferred through the roller elements  11 . This axial thrust, which is caused by an axial force, F axial , generated due to the imparted input torques M in , is supported by an opposite force F axial-opposing , so that a torque is transferred, depending on the magnitude of the opposing force. Ideally, an opposing force F axial-opposing  is created, which corresponds to the axial force F axial , which results from the mean input torque M in , wherein, due to the force equilibrium, this mean input torque M in  is then transferred through the roller elements  11 . The generation of the opposing force F axial-opposing  is performed by a hydraulic control device  15 . It comprises a piston element  14 , which is associated with the secondary component  4 , or directly formed by it, and a pressure cavity  12 . The piston element  14  is actuated through the pressure in the pressure cavity  12 . The pressure cavity  12  can thus be loaded by a pressure medium. The secondary component  4 , or the ramp element connected therewith, is loaded with a pressure p at its front face  13 , facing away from the primary component  3  as a piston surface, generating the corresponding opposing force F axial-opposing  with respect to the force F axial , thus holding the system in equilibrium by supporting the secondary component  4  in axial direction. The opposing force F axial-opposing , caused by the pressure p onto the piston surface, is thus provided, so that at least the mean input torque M in-mean  is reliably transmitted through the device  1 . In case of deviations from the mean input torque M in-mean , compensation can be performed through pressure control in the pressure cavity  12 . To avoid complex detections of the actual value of the mean input torque, M in-mean , and to perform a respective control of the pressure p in the pressure cavity  12 , there is a possibility to solve this from a design point of view by performing the control hydraulically. The hydraulic control device  15  comprises next to the pressure cavity  12 , associated at least indirectly with the secondary component  4 , or the second ramp element, a storage  16 , coupled with the pressure cavity  12 , and means  17  for selective coupling of the pressure medium storage with a pressure medium source  19 , in particular a pressure ramp or a relief device  20 , in particular, a pressure sink, e.g. provided as a tank, or in general for decoupling both. The means  17  thus comprise in the simplest case a valve assembly  18 , comprising at least three operating positions, a first operating position I, in which the storage  16 , or the pressure cavity  12  is decoupled from the pressure medium source  19  and the relief device  20 , a second operating position II, in which the storage  16 , or the pressure cavity  12  is connected with a pressure medium source  19 , and a third operating position III, in which the storage  16  or the pressure cavity  12  is connected with a relief device  20 . The means  12  thus function as actuation device  35  for adjusting the compression pressure in the pressure chamber  12  for creating the required opposing force F axial-opposing . 
     The system is provided, so that for transferring a mean input torque M in-mean  at the device  1  for damping vibrations, in particular, in the primary component  3 , an opposite force F axial-opposing  is provided, which opposes the resulting axial force F axial , generated in the pressure cavity  12 , relative to the piston element  14 . In this case, the actuation device  35  is in the first operating position I. There is equilibrium and torque peaks can be compensated through the storage  16 . When the mean input torque M in-mean  to be transferred increases a higher opposing force is required for torque transfer. The pressure in the pressure chamber  12  has to be adapted. According to the invention this is not realized through complex control systems, but the force difference directly impacts the control variable Y for controlling the control device  35  through a conversion device  38 . Preferably a conversion is performed into a variable, characterizing the change in position, as e.g. a travel distance or an angle. As a conversion device, an element, e.g. the second ramp element can function, which is subject to a translatoric motion due to the force difference. 
     In the simpliest case, the force difference between the axial force F axial , generated by the input torque M in-mean , to be transferred, and the preset opposing force F axial-opposing  is converted into a translatoric motion of an element, in particular, into a translatoric motion of the second ramp element, by a travel distance s, which is proportional or equal to the required stroke of the actuating element  35  of the valve device  18 . Thus, the valve device  18  is actuated in the direction of the second operating position II, and the pressure source  19  is connected with the pressure cavity  12 , when the mean torque M in-mean  to be transferred increases. Analogously, a connection with the relief device  20  is performed, when the input torque M in-mean  to be transferred is reduced. Depending on the embodiment, the change between the particular operating positions, I, II, III, is preferably performed continuously, so that through changing the free cross sections, a fine adjustment of the pressure in the pressure chamber  12  is possible. 
       FIG. 2  illustrates a particularly advantageous engineering design of the integration of the hydraulic control device  15  according to the invention into a device  1  for damping vibrations in a simplified schematic depiction. This also comprises a primary part  3  and a secondary part  4 , which are connected amongst each other through the ramp mechanism  2 . The ramp mechanism  2  thus comprises at least two ramp elements, designated here with  21  and  22 , wherein they are either connected torque proof with the primary component  3  and the secondary component  4 , or they form the respective primary component  3 , or the secondary component  4 . Both possibilities are feasible. The primary component  3  and the secondary component  4  are typically provided as flywheels. They are provided as disc shaped elements. In the illustrated embodiment, only torque proof couplings are illustrated between the particular elements. Thus, the ramp element  21  forms a so-called fixed ramp  23  with the primary component  3 . The secondary component  4  forms the so-called travel ramp  24  with the second ramp element  22 . The fixed ramp  23  forms the input E, and the travel ramp  24  forms the output A of the ramp mechanism  2 . Also here, a physical unit of the secondary component  4  and the ramp element  22 , or an integral design is feasible. The coupling for torque transfer is performed through the roller elements  11 , which are provided in indentations at the respective ramp elements  21  and  22 . 
       FIG. 2  illustrates a particularly advantageous embodiment, in which the hydraulic control device  15  is integrated in the secondary component  4 , in particular in the travel ramp  24 . The hydraulic control device  15  comprises a pressure chamber provided as the compression chamber  25 , impacting a piston element, coupled with the second ramp element  22 , and movable relative to it, or forming the second ramp element  22  according to a particularly advantageous embodiment. In this case the piston element  26  is used for forming the compression chamber  25 . The piston element  26  is therefore guided at the secondary component  4  in a sealing and axially translatoric manner. The piston element  26  comprises a piston surface  27  which operates together with the roller element  11 , wherein a support at the secondary component  4  is performed through it. The positioning device  35  in the form of a valve assembly  18  is integrated in the secondary component  4 , or in the travel ramp  24 , through which the compression chamber  25  can be selectively coupled with a pressure medium souce  19 , or a relief device  20 , or it is decoupled from both. The piston element  26  thus has a pass-through opening  29 , which can be selectively coupled with the particular connections at the secondary component  4  or the fixed ramp  24 , forming the valve assembly  18 . The coupling is thus performed depending on the position of the piston element  26  in axial direction, relative to the secondary component  4 . The piston element  26  is thus provided axially movable at the secondary component  4  for this purpose. At the secondary component  4  radially facing connections  30  through  32  are provided, which are used for coupling with the compression chamber  25 . The secondary component  4  is thus provided as a cylindrical element  28 , through whose walls the channels for the connections  30  to  32  extend up to the outer circumference  33 . Through the pass-through opening  29 , which is also preferably provided in radial direction in the wall of the piston element  26 , defining the compression chamber  25 , the connection with the compression chamber  25  can be generated. The compression chamber  25  and the actuating device  35  are preferably provided coaxial with each other. The particular connections with the pressure source  19 , or the relief device  20  are created through establishing flush positioning or overlapping positioning between the particular connections  30  through  32  and the pass-through opening  29 . In the shown embodiment the connection  31  can be coupled with the pressure medium source  19  and the connection  32  can be coupled with the relief device  20 . The connector  30  can be connected with a hydraulic storage  16 , wherein the storage  16  comprises a piston element  37 , supported at a spring unit  34 , wherein the piston element  37  is loaded by the pressure in the compression chamber  25 . According to  FIG. 2 , the coupling of the pressure chamber  12  with the other connections is always performed through the storage  16 . 
     The system is designed, so that for the transfer of a mean input torque M in-mean  at the device  1  for damping vibrations, in particular in the primary component  3 , relative to the resulting axial force F axial , an opposing force F axial-opposing  is provided, which is generated relative to the piston element  26  in the compression chamber  25 , wherein the particular connections  31  and  32  are not connected to the compression chamber  25  in this position. Only a coupling between the compression chamber  25  and the storage  16  exists. This is realized through the first connection  30 . The second connection  31  can be coupled with the source of the pressure means  19 , while the third connection  32  can be connected with the relief device  20 . Depending on the position of the piston element  26 , the particular connections are more or less covered, which generates the particular functions of the valve device. The function of the valve piston of the valve device  18  is taken over by the piston  26  in this case, which simultaneously also generates the compression force relative to the second ramp element. 
     The solution according to the invention is not limited to the embodiment shown in  FIG. 2 . Any possibility of a direct conversion of a position change, caused by the difference between the axial force resulting from the input moment and the predefined opposing force is conceivable. In the simplest case the force difference is used, which is directly converted into a travel distance. 
     The integration of the travel ramp  24  into the secondary component  4  provides a particularly compact embodiment, which is characterized by a minimal design and control complexity. Furthermore, it is conceivable to connect the compression chamber with the compression volume of another unit, e.g. a continuously variable transmission, provided in the form of a CVT, which is disposed subsequent to the device for damping vibrations, and thus to integrate the function of a moment sensor into the damper right away. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 Designations 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 device for damping vibrations 
               
               
                 2 
                 ramp mechanism 
               
               
                 3 
                 primary component 
               
               
                 4 
                 secondary component 
               
               
                 5 
                 torque transfer device 
               
               
                 6 
                 damping coupling device 
               
               
                 7 
                 front face 
               
               
                 8 
                 front face 
               
               
                 9 
                 ramp surface 
               
               
                 10 
                 ramp surface 
               
               
                 11 
                 roller element 
               
               
                 12 
                 pressure cavity 
               
               
                 13 
                 front face 
               
               
                 14 
                 piston surface 
               
               
                 15 
                 hydraulic control system 
               
               
                 16 
                 storage 
               
               
                 17 
                 selective coupling or decoupling to/from a pressure medium 
               
               
                   
                 source, or a relief device 
               
               
                 18 
                 valve assembly 
               
               
                 19 
                 pressure medium source 
               
               
                 20 
                 relief device 
               
               
                 21 
                 fixed ramp 
               
               
                 22 
                 ravel ramp 
               
               
                 23 
                 compression chamber 
               
               
                 24 
                 piston element 
               
               
                 25 
                 piston surface 
               
               
                 26 
                 cylindrical element 
               
               
                 27 
                 pass-through opening 
               
               
                 28 
                 connection 
               
               
                 29 
                 connection 
               
               
                 30 
                 connection 
               
               
                 31 
                 outer circumference 
               
               
                 32 
                 spring unit 
               
               
                 33 
                 actuation device 
               
               
                 34 
                 actuator 
               
               
                 35 
                 piston 
               
               
                 38 
                 conversion device