Abstract:
Valve element for an exhaust-gas turbocharger, having a spindle which has a longitudinal extent, a lever which extends from the spindle laterally in relation to the longitudinal extent of said spindle and which has a through opening, a valve flap plate, a substantially disc-shaped fastening element, and a shank which extends through the through opening and which connects the valve flap plate to the fastening element, wherein the valve flap plate and the fastening element are connected to one another by way of a shank extending through the through opening of the lever, and wherein a spring element is provided for generating a preload between shank and lever.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a valve element and in particular to a valve element for use for charge-pressure regulation in an exhaust-gas turbocharger. 
       DESCRIPTION OF THE PRIOR ART 
       [0002]    Valve elements for exhaust-gas turbochargers are known and are described for example in DE 10 2015 008 426 A1. 
         [0003]    Valve elements of said type are commonly referred to as wastegate valves. The general and known mode of operation of an exhaust-gas turbocharger with a wastegate valve device will be described below with reference to  FIGS. 1 and 20 . 
         [0004]    During operation of the engine under load, the wastegate valve element  1 —comprising a rotatably mounted spindle  2 , a lever  3  which is attached to one end of the spindle and which projects laterally and which has a through opening, a (valve) flap plate  4  with a shank which is attached to or integrated with the flap plate centrally on one side and which is provided for being led through the lever opening, and a disc  5  as a fastening element on a led-through shank end of the flap plate  4 —is closed by way of an actuating drive  22  and an actuating arrangement  24 . Here, the flap plate  4  is pressed against a valve seat  23  by pivoting of the valve element  1 . In this way, the entire exhaust-gas flow is conducted via an exhaust-gas-side turbine wheel  19  which is fixedly connected to a connecting shaft  20  and to an intake-side compressor wheel  21 . The exhaust-gas flow accelerates the turbine wheel  19  together with the connecting shaft  20  and the intake-side compressor wheel  21 . The required combustion air is thereby compressed by the compressor wheel  21  and supplied, at positive pressure, via the charge-air cooler to a combustion chamber, which leads to significantly improved and more effective combustion of the fuel and to a greater power output of the engine. 
         [0005]    During partial-load or overrun operation of the engine, the air compression is required to a lesser extent, or is not required. Therefore, during this type of driving, the actuating drive  22  opens the valve  1  by way of the actuating arrangement  24 , and allows the major part of the exhaust-gas flow to escape directly, and without being diverted by the turbine wheel  19 , through the “wastegate” into the exhaust tail pipe, and the air compression is reduced or eliminated. Here, the engine backpressure is also reduced. The lower backpressure reduces the pumping work and improves fuel economy. 
         [0006]    During operation, the problem arises that the temperature of the exhaust gas can reach temperatures of over 1,000° C. The heat that is generated here is released non-uniformly to the mechanical components involved. This can give rise to stresses and distortion in the mechanical components (housing, flap plate  4 , valve seat  23 , lever  3  etc.—cf.  FIG. 20 ). In the case of a rigid arrangement of the components of flap plate  4  and lever  3 , this can lead to leaks between the valve seat  23  and the sealing surface of the valve plate  4 , because the flap plate may set down on the valve seat in a skewed manner. 
         [0007]    In order to realize a compensation here, it is known for the connection between flap plate  4  and lever  3  to be realized with a certain radial clearance between flap plate shank and lever bore and with a certain axial clearance between lever  3  and fastening disc  5 , that is to say the flap plate shank with the flap plate wobbles in the lever bore. If the wastegate valve element  1  is opened by way of the actuating drive  22  and the actuating arrangement  24 , a major part of the exhaust gas flows at high speed in turbulent fashion over the flap plate  4  fastened with a clearance to the lever  3 , and causes said flap plate to flutter. Here, the flap plate  4  may strike the lever  3  and/or the valve seat  23  in uncontrolled fashion, and the disc  5  may strike the lever  3 . This gives rise to an undesired rattling noise, and can lead to increased wear on the individual elements. 
       SUMMARY OF THE INVENTION 
       [0008]    In contrast thereto, the invention proposes a valve element having the features of claim  1 . 
         [0009]    The invention is based on the concept of further developing a generic valve element such that a spring element is provided for generating a preload between shank and lever. 
         [0010]    According to the invention, the spring element may be designed to impart a radial spring force action relative to the valve plate shank. 
         [0011]    With the solution according to the invention, a disturbing fluttering of the valve flap plate that has hitherto occurred when the wastegate is open is prevented, and thus the rattling noise is eliminated. Furthermore, the wear on the individual components of a wastegate valve device is reduced by way of a valve element according to the invention. 
         [0012]    Further refinements of the invention are described in the further subclaims. 
         [0013]    Further advantages and refinements of the invention will emerge from the description and from the appended drawings. 
         [0014]    It is self-evident that the features mentioned above and the features yet to be discussed below may be used not only in the respectively specified combination but also in other combinations or individually without departing from the scope of the present invention. 
         [0015]    The invention is illustrated in the drawing in highly schematic form, and not to scale, on the basis of exemplary embodiments, and will be described in detail below with reference to the drawing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0016]      FIG. 1  shows an assembled wastegate valve element with pivotable spindle, lever projecting laterally therefrom, flap plate and disc, in a plan view. 
           [0017]      FIG. 2  shows a wastegate valve element according to the invention in a lateral sectional illustration as per the section line A-A in  FIG. 1 . 
           [0018]      FIG. 3  shows an alternative embodiment of the wastegate valve element from  FIG. 2 , in a lateral sectional illustration. 
           [0019]      FIG. 4  shows a ring-shaped spring element according to the invention with a cutout for a disc-mounted arrangement, in a plan view. 
           [0020]      FIG. 5  shows a sectional illustration through an embodiment of the spring element according to the invention as per the section line B-B in  FIG. 4 , with a first profile shape. 
           [0021]      FIG. 6  shows a sectional illustration through a further embodiment of the spring element according to the invention as per the section line B-B in  FIG. 4 , with a second profile shape. 
           [0022]      FIG. 7  shows a sectional illustration through a further embodiment of the spring element according to the invention as per the section line B-B in  FIG. 4 , with a third profile shape. 
           [0023]      FIG. 8  shows a further embodiment of the valve element according to the invention in a lateral sectional illustration as per the section line A-A in  FIG. 1 . 
           [0024]      FIG. 9  shows a variant of the valve element according to the invention from  FIG. 8 . 
           [0025]      FIG. 10  shows a ring-shaped spring element according to the invention with a cutout for plate-mounted arrangement, in a plan view. 
           [0026]      FIG. 11  shows a sectional illustration through an embodiment of the spring element according to the invention as per the section line C-C in  FIG. 10 , with a first profile shape. 
           [0027]      FIG. 12  shows a sectional illustration through a further embodiment of the spring element according to the invention as per the section line C-C in  FIG. 10 , with a second profile shape. 
           [0028]      FIG. 13  shows a sectional illustration through a further embodiment of the spring element according to the invention as per the section line C-C in  FIG. 10 , with a third profile shape. 
           [0029]      FIG. 14  shows an enlarged detail illustration of  FIG. 3 . 
           [0030]      FIG. 15  shows an enlarged detail illustration of  FIG. 2 . 
           [0031]      FIGS. 16 and 16   a  illustrate the mode of operation according to the invention in the case of a flap plate that has set down in skewed fashion, in the case of a disc-mounted configuration. 
           [0032]      FIG. 17  shows an enlarged detail illustration of  FIG. 9 . 
           [0033]      FIG. 18  shows an enlarged detail illustration of  FIG. 8 . 
           [0034]      FIG. 19  illustrates the mode of operation according to the invention in the case of a flap plate that has set down in skewed fashion, in the case of a plate-mounted configuration. 
           [0035]      FIG. 20  shows, in a schematic illustration, the mode of operation of an exhaust-gas turbocharger with wastegate valve arrangement. 
           [0036]      FIGS. 21 and 22  show enlarged detail illustrations of the embodiment of  FIG. 8 , with a bevel arranged in the lever bore. 
           [0037]      FIGS. 23 and 23   a  show enlarged detail illustrations of the embodiment of  FIG. 28  as a welded version. 
           [0038]      FIGS. 24 and 24   a  show enlarged detail illustrations of the embodiment of  FIG. 3 , with a bevel arranged in the disc bore. 
           [0039]      FIGS. 25 and 25   a  show enlarged detail illustrations of the embodiment of  FIG. 27  as a riveted version. 
           [0040]      FIG. 26  shows a radially acting, meander-ring-shaped spring element according to the invention. 
           [0041]      FIG. 27  shows the section A-A through the valve element according to the invention with ring-shaped spring element in a plate-mounted configuration, in a riveted variant. 
           [0042]      FIG. 28  shows the section A-A through the valve element according to the invention with ring-shaped spring element in a disc-mounted configuration, in a welded variant. 
           [0043]      FIG. 29  shows, in a plan view, a ring-shaped spring element with cutout with trapezoidal profile for plate-side and disc-side arrangements as per  FIGS. 27 and 28 . 
           [0044]      FIG. 30  shows a sectional illustration through the spring elements according to the invention of  FIGS. 26 and 29  with a trapezoidal profile as per the section line D-D of  FIG. 29 . 
       
    
    
     DETAILED DESCRIPTION 
       [0045]      FIG. 2  shows the section A-A through the valve element  1  in the case of a riveted version  6  with a ring-shaped spring element  10  or  25  with elliptical (circular) profile  8  in a disc-mounted configuration. The shank of the flap plate for riveted fastening  4   a  is led through the opening in the lever  3   a . At the plate side, the lateral surface of the lever  3   a  rests or abuts flat against the elevated surface of the flap plate  4   a . It is possible to see the radial clearance between the lever bore and the flap plate shank. On the disc, at the lever bore, it is possible to see the bevel  16  in which the spring element  10  or  25  is arranged with a clearance with respect to the flap plate shank. The disc  5  is riveted so as to abut against the shoulder on the flap plate shank, wherein the spring element  10  or  25  is pushed into the bevel  16  slightly and, in the process, is preloaded. The spacing between the disc-side lever surface and lever-side disc surface is the axial clearance (gap dimension) by which the flap plate with shank and fixedly riveted-on disc  5  can move in an axial direction in the lever bore. The cross section of the spring element  10  or  25  must be larger than the axial clearance. Thus, the spring element  10  or  25  cannot emerge from its introduction region. If the flap plate  4   a  is pressed onto a valve seat  23  which is skewed owing to distortion, this also gives rise to a skewed position of the flap plate with shank and disc. As a result, the spring element is pushed deeper into the bevel  16  and, in the process, is radially compressed by the oblique bevel  16 , and is placed under even greater load. The restoring force of the spring element  10  or  25  increases until the disc  5  sets down on the lever surface. The mechanical end stop is thus reached, and the spring element  10  or  25  can expand no further. Overloading of the spring element  10  or  25  is thus prevented (in this regard, see also  FIG. 16  and  FIG. 16 a   ). If the wastegate valve device is opened, the restoring force of the spring element  10  or  25  has the effect, via the bevel  16 , that the flap plate  4   a  immediately returns in an axial direction into its initial position and is held there by the preload, even if it is impinged on by a flow of the exhaust gas. Rattling is thus prevented. 
         [0046]      FIG. 3  is a variant of  FIG. 2 .  FIG. 3  shows the section A-A through the valve element  1  in the case of a welded version  7  with ring-shaped spring element  10  or  25 , which has a profile  9  in the shape of a rectangle with a truncated corner, in a disc-mounted configuration. The shank of the flap plate for welded fastening  4   b  is led through the opening in the lever  3   a . At the plate side, the lateral surface of the lever  3   a  rests flat against the elevated surface of the flap plate  4   b . It is possible to see the radial clearance between the lever bore and the flap plate shank. On the disc, at the lever bore, it is possible to see the bevel  16  in which the spring element  10  or  25  is arranged with a clearance to the flap plate shank. The disc  5  is welded so as to abut against the shoulder on the flap plate shank, wherein the spring element  10  or  25  is pushed into the bevel  16  slightly and, in the process, is preloaded. The spacing between the disc-side lever surface and lever-side disc surface is the axial clearance (gap dimension) by which the flap plate with shank and fixedly welded-on disc  5  can move in an axial direction in the lever bore. The cross section of the spring element  10  or  25  must be larger than the axial clearance. Thus, the spring element  10  or  25  cannot emerge from its introduction region. If the flap plate  4   b  is pressed onto a valve seat which is skewed owing to distortion, this also gives rise to a skewed position of the flap plate with shank and disc. As a result, the spring element is pushed deeper into the bevel  16  and, in the process, is radially compressed by the oblique bevel  16 , and is placed under even greater load. The restoring force of the spring element  10  or  25  increases until the disc  5  sets down on the lever surface. The mechanical end stop is thus reached, and the spring element  10  or  25  can expand no further. Overloading of the spring element  10  or  25  is thus prevented (in this regard, see also  FIG. 16  and  FIG. 16 a   ). If the wastegate valve is opened, the restoring force of the spring element  10  or  25  has the effect, via the bevel  16 , that the flap plate  4   b  immediately returns in an axial direction into its initial position and is held there by the preload, even if it is impinged on by a flow of the exhaust gas. Rattling is thus prevented. 
         [0047]      FIG. 4  shows the ring-shaped spring element with a cutout for disc-mounted arrangement  10 , in a plan view. The ring is not closed, such that a spring travel is possible. The spring force acts radially. 
         [0048]      FIG. 5  shows the section B-B through the spring element for disc-mounted arrangement  10  with a profile  9  which is rectangular with a truncated corner,  FIG. 6  shows the section B-B through the spring element for disc-mounted arrangement  10  with a triangular profile  11 , and  FIG. 7  shows the section B-B through the spring element for disc-mounted arrangement  10  with an elliptical (circular) profile  8 . 
         [0049]      FIG. 8  shows the section A-A through the wastegate valve element  1  in the case of a riveted version  6  with ring-shaped spring element  15  or  25 , which has a profile  12  in the shape of a rectangle with a truncated corner, in a plate-mounted configuration. The shank of the flap plate for riveted fastening  4   c  is led through the opening in the lever  3   b . At the disc side, the lateral surface of the lever  3   b  rests flat against the lever-side surface of the disc  5 . It is possible to see the radial clearance between the lever bore and the flap plate shank. In the elevated region of the flap plate  4   c , a ring-shaped groove is formed in coaxially with respect to the shank, which ring-shaped groove transitions into a bevel  17  on the flap plate shank. The ring-shaped groove is the introduction region for receiving the ring-shaped spring element  15  or  25  when the latter is pushed downward by the plate-side surface of the lever  3   b . The spring element  15  or  25  is arranged on the flap plate shank without a clearance. The disc  5  is riveted so as to abut against the shoulder on the flap plate shank. Here, the spring element  15  or  25  is pushed into the bevel  17  slightly and, in the process, is preloaded. The spacing between the plate-side lever surface and the elevated ring on the flap plate  4   c  is the axial clearance (gap dimension) by which the flap plate with shank  4   c  and fixedly riveted-on disc  5  can move in an axial direction in the lever bore. The cross section of the spring element  15  or  25  must be larger than the axial clearance. Thus, the spring element  15  or  25  cannot emerge from its introduction region. If the flap plate  4   c  is pressed onto a valve seat  23  which is skewed owing to distortion, this also gives rise to a skewed position of the flap plate with shank  4   c  and disc  5 . As a result, the spring element is pushed deeper into the bevel  17  and, in the process, is radially expanded by the oblique bevel  17 , and is placed under even greater load. The restoring force of the spring element  15  or  25  increases until the lever surface sets down on the flap plate ring. The mechanical end stop is thus reached, and the spring element  15  or  25  can expand no further. Overloading of the spring element  15  or  25  is thus prevented (in this regard, see also  FIG. 17  and  FIG. 18  and  FIG. 19 ). If the wastegate valve is opened, the restoring force of the spring element  15  or  25  has the effect, via the bevel  17 , that the flap plate  4   c  immediately returns in an axial direction into its initial position and is held there by the preload, even if it is impinged on by a flow of the exhaust gas. Rattling is thus prevented. 
         [0050]      FIG. 9  is a variant of  FIG. 8 .  FIG. 9  shows the section A-A through the wastegate valve element  1  in the case of a welded version  7  with ring-shaped spring element  15  or  25 , which has an elliptical or circular profile  14 , in a plate-mounted configuration. The shank of the flap plate for welded fastening  4   d  is led through the opening in the lever  3   b . At the disc side, the lateral surface of the lever  3   b  rests flat against the lever-side surface of the disc  5 . It is possible to see the radial clearance between the lever bore and the flap plate shank. In the elevated region of the flap plate  4   d , a ring-shaped groove is formed in coaxially with respect to the shank, which ring-shaped groove transitions into a bevel  17  on the flap plate shank. The ring-shaped groove is the introduction region for receiving the ring-shaped spring element  15  or  25  when the latter is pushed downward by the plate-side surface of the lever  3   b . The spring element  15  or  25  is arranged on the flap plate shank without a clearance. The disc  5  is welded so as to abut against the shoulder on the flap plate shank. Here, the spring element  15  or  25  is pushed onto the bevel  17  slightly and, in the process, is preloaded. The spacing between the plate-side lever surface and elevated ring on the flap plate  4   d  is the axial clearance (gap dimension) by which the flap plate with shank  4   d  and fixedly riveted-on disc  5  can move in an axial direction in the lever bore. The cross section of the spring element  15  or  25  must be larger than the axial clearance. Thus, the spring element  15  or  25  cannot emerge from its introduction region. If the flap plate  4   d  is pressed onto a valve seat  23  which is skewed owing to distortion, this also gives rise to a skewed position of the flap plate with shank  4   d  and disc  5 . As a result, the spring element is pushed deeper onto the bevel  17  and, in the process, is radially expanded by the oblique bevel  17 , and is placed under even greater load. The restoring force of the spring element  15  or  25  increases until the lever surface sets down on the flap plate ring. The mechanical end stop is thus reached, and the spring element  15  or  25  can expand no further. Overloading of the spring element  15  or  25  is thus prevented (in this regard, see also  FIG. 17  and  FIG. 18  and  FIG. 19 ). If the wastegate valve device is opened, the restoring force of the spring element  15  or  25  has the effect, via the bevel  17 , that the flap plate  4   d  immediately returns in an axial direction into its initial position and is held there by the preload, even if it is impinged on by a flow of the exhaust gas. Rattling is thus prevented. 
         [0051]      FIG. 10  shows the ring-shaped spring element with a cutout for plate-mounted arrangement  15 , in a plan view. The ring is not closed, such that a spring travel is possible. The spring force acts radially. 
         [0052]      FIG. 11  shows the section C-C through the spring element for disc-mounted arrangement  15  with a profile  12  which is rectangular with a truncated corner,  FIG. 12  shows the section C-C through the spring element for disc-mounted arrangement  15  with a triangular profile  13 , and  FIG. 13  shows the section C-C through the spring element for disc-mounted arrangement  15  with an elliptical (circular) profile  14 . 
         [0053]      FIG. 14  shows details of  FIG. 3 , and  FIG. 15  shows details of  FIG. 2 . 
         [0054]      FIG. 16  and  FIG. 16 a    show the mode of operation of the spring element  10  or  25  in the case of a flap plate  4   b  that has set down in skewed fashion, in the case of a disc-mounted configuration. 
         [0055]      FIG. 17  shows details of  FIG. 9 , and  FIG. 18  shows details of  FIG. 8 . 
         [0056]      FIG. 19  shows the mode of operation of the spring element  15  or  25  in the case of a flap plate  4   c  that has set down in skewed fashion, in the case of a plate-mounted configuration. Here, it can also be seen, as per Patent claim  17 , that the setting-down of the flap plate  4   c  and the orientation take place before the actual exertion of load, and thus more smoothly and in a more material-preserving manner. 
         [0057]      FIG. 20  schematically shows an exhaust-gas turbocharger  18  with wastegate valve seat  23  and wastegate valve element  1 , actuating drive  22  and actuating arrangement  24  for the wastegate valve element  1 , the exhaust-gas-side turbine wheel  19  with connecting shaft  20 , and the inlet-air-side compressor wheel  21 . 
         [0058]      FIG. 21  and  FIG. 22  correspond, in terms of mode of operation, to  FIG. 8 , but here, the bevel is arranged not in a ring-shaped groove in the flap plate but rather in the lever bore. 
         [0059]      FIG. 23  and  FIG. 23 a    show details of  FIG. 28  as a welded version. 
         [0060]      FIG. 24  and  FIG. 24 a    correspond, in terms of mode of operation, to  FIG. 3 , but here, the bevel is arranged not in the lever bore but rather in the disc bore. 
         [0061]      FIG. 25  and  FIG. 25 a    show details of  FIG. 27  as a riveted version.  FIG. 26  shows the plan view of the meander-ring-shaped, radially acting spring element  25 . 
         [0062]      FIG. 27  shows the section A-A through the wastegate valve element  1  in the case of a riveted version  6  with a ring-shaped spring element  26  or  25  with trapezoidal profile  27  in a plate-mounted configuration. The shank of the flap plate  4   e ,  4   f  is led through the opening in the lever  3   c . At the disc side, the lateral surface of the lever  3   c  rests flat against the lever-side surface of the disc  5 . It is possible to see the radial clearance between the lever bore and the flap plate shank. A ring-shaped groove is formed into the elevated region of the flap plate  4   e ,  4   f  coaxially with respect to the shank, which ring-shaped groove transitions into a bevel  28 . Opposite this, a bevel  29  is likewise formed into the plate in the lever bore. The space that exists between said two bevels  28  and  29  is the introduction region for receiving the ring-shaped spring element  26  or  25  with trapezoidal profile  27 . The spring element  26  or  25  is supported by way of its two oblique surfaces both against the bevel  28  in the flap plate  4   e ,  4   f  and against the bevel  29  in the lever  3   c . The disc  5  is riveted so as to abut against the shoulder on the flap plate shank. Here, the spring element  26  or  25  is pushed into the bevels  28  and  29  slightly and, in the process, is preloaded. Here, centring of the flap plate with shank  4   e ,  4   f  in the bore of the lever  3   c  is realized. The spacing between the plate-side lever surface and the elevated ring on the flap plate  4   e ,  4   f  is the axial clearance (gap dimension) by which the flap plate with shank  4   e ,  4   f  and fixedly riveted-on disc  5  can move in an axial direction in the lever bore. The cross section of the spring element  26  or  25  must be larger than the axial clearance. Thus, the spring element  26  or  25  cannot emerge from its introduction region. If the flap plate  4   e ,  4   f  is pressed onto a valve seat  23  which is skewed owing to distortion, this also gives rise to a skewed position of the flap plate with shank  4   e ,  4   f  and disc  5 . As a result, the spring element is pushed deeper onto the bevels  28  and  29  and, in the process, is radially expanded by the oblique bevels  28  and  29 , and is placed under even greater load. The restoring force of the spring element  26  or  25  increases until the lever surface sets down on the flap plate ring. The mechanical end stop is thus reached, and the spring element  26  or  25  can expand no further. Overloading of the spring element  26  or  25  is thus prevented (in this regard, see also  FIG. 25 a   ). If the wastegate valve is opened, the restoring force of the spring element  26  or  25  has the effect, via the bevels  28  and  29 , that the flap plate  4   e ,  4   f  immediately returns in an axial direction and in a radial direction into its centred initial position and is held there by the preload, even if it is impinged on by a flow of the exhaust gas. Rattling is thus prevented. 
         [0063]      FIG. 28  shows the section A-A through the wastegate valve element  1  in the case of a welded version  7  with ring-shaped spring element  26  or  25 , which has a trapezoidal profile  27 , in a disc-mounted configuration. The shank of the flap plate  4   a ,  4   b  is led through the opening in the lever  3   a . At the plate side, the lateral surface of the lever  3   a  rests flat against the lever-side elevated surface of the flap plate  4   a ,  4   b . It is possible to see the radial clearance between the lever bore and the flap plate shank. A bevel  30  is formed into the lever-side surface of the disc  5   a . Opposite this, a bevel  16  is likewise formed into the disc in the lever bore. The space that exists between said two bevels  30  and  16  is the introduction region for receiving the ring-shaped spring element  26  or  25  with trapezoidal profile  27 . The spring element  26  or  25  is supported by way of its two oblique surfaces both against the bevel  30  in the disc  5   a  and against the bevel  16  in the lever  3   a . The disc  5   a  is welded so as to abut against the shoulder on the flap plate shank. Here, the spring element  26  or  25  is pushed into the bevels  30  and  16  slightly and, in the process, is preloaded. Here, centring of the flap plate with shank  4   a ,  4   b  in the bore of the lever  3   a  is realized. The spacing between the disc-side lever surface and the lever-side planar outer ring-shaped surface on the disc  5   a  is the axial clearance (gap dimension) by which the flap plate with shank  4   a ,  4   b  and fixedly welded-on disc  5   a  can move in an axial direction in the lever bore. The cross section of the spring element  26  or  25  must be larger than the axial clearance. Thus, the spring element  26  or  25  cannot emerge from its introduction region. If the flap plate  4   a ,  4   b  is pressed onto a valve seat  23  which is skewed owing to distortion, this also gives rise to a skewed position of the flap plate with shank  4   a ,  4   b  and disc  5   a . As a result, the spring element is pushed deeper onto the bevels  30  and  16  and, in the process, is radially expanded by the oblique bevels  30  and  16 , and is placed under even greater load. The restoring force of the spring element  26  or  25  increases until the lever surface sets down on the disc ring. The mechanical end stop is thus reached, and the spring element  26  or  25  can expand no further. Overloading of the spring element  26  or  25  is thus prevented (in this regard, see also  FIG. 23 a   ). If the wastegate valve is opened, the restoring force of the spring element  26  or  25  has the effect, via the bevels  30  and  16 , that the flap plate  4   a ,  4   b  immediately returns in an axial direction and in a radial direction into its centred initial position and is held there by the preload, even if it is impinged on by a flow of the exhaust gas. Rattling is thus prevented. 
         [0064]      FIG. 29  shows the ring-shaped spring element with a cutout  26  with trapezoidal profile  27  for plate-mounted and disc-mounted arrangement as per  FIG. 27  and  FIG. 28 , in a plan view. The ring is not closed, such that a spring travel is possible. The spring force acts radially. 
         [0065]      FIG. 30  shows the trapezoidal profile  27  of the spring elements  26  and  25 . 
         [0066]    The use of a radially acting ring-shaped spring element between the fastening disc and the lever (disc-side variant) or between the lever and the flap plate (plate-side variant) on one or two bevels eliminates the fluttering of the flap plate by way of a certain permanent preload. For this purpose, the embodiment of the bevels and of the ring-shaped spring element is selected such that the spring element is already pushed slightly onto the bevel(s) in the axial direction towards the flap plate shank during the assembly process. Here, the spring element is placed under load in a radial direction. Owing to the support on the oblique bevel(s), it is also the case here that a restoring force acts in an axial direction, with a centring action being realized in the case of support on two oppositely situated bevels. 
         [0067]    The spring element imparts a vibration-damping action when the wastegate valve is open, and stabilizes the flap plate in its initial position. In the closed state, the spring element permits a skewed position of the flap plate within the range of the axial and radial clearance. During the opening process, the initial position is immediately re-established by way of the restoring force of the spring element. 
         [0068]    The restoring or holding force of the spring element required in the respective usage situation may be set through variation of the bevel angle, the spring characteristic curve, the spring geometry and the axial and radial clearance. Experts at the spring manufacturer can select the optimum material for the respective usage situation. 
         [0069]    The design of the introduction region or installation space for the spring element and the geometry of the spring element should be selected such that the spring element can be completely received in its introduction region when the lever is pushed into a block state both at the disc side and at the plate side (mechanical end stop). In this way, the spring element cannot be over-expanded or overloaded. 
         [0070]    The use of the application according to the invention is independent of the method used for the fastening of the disc to the flap plate bolt. The disc may be welded on, riveted on, shrink-fitted on etc. 
         [0071]    The valve device according to the invention may be arranged at the turbine side and/or compressor side in a bypass of an exhaust-gas turbocharger.