Abstract:
A valve device for controlling a bypass of an exhaust-gas turbocharger may include a valve disc for opening and closing a bypass opening of a turbine, and the bypass opening may be surrounded by a valve seat. A mandrel may protrude on a rear side of the valve disc. An adjusting lever for pivoting the valve disc may be connected with the mandrel. The adjusting lever may have a through opening that may be pierced by the mandrel. The through opening may be radially limited by an interior surface of the adjusting lever. At least one spring element may be arranged in the through opening, and the at least one spring element may subject the mandrel to a radial force.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to German Patent Application No. 10 2015 209 042.6, filed May 18, 2015, the contents of which are hereby incorporated by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The invention relates to a valve device for controlling a bypass, for example a turbine of an exhaust-gas turbocharger, with a valve disc for opening and closing a bypass opening of the turbines surrounded by a valve seat and with a mandrel, which projects on a rear side of the valve disc, and with an adjusting lever for pivoting the valve disc, which is connected with the mandrel of the valve disc. The invention further relates to a charging device with such a valve device and a method for assembling such a valve device. 
       BACKGROUND 
       [0003]    In charging devices, for example exhaust-gas turbochargers, for internal combustion engines, so-called wastegate valves are used for regulating power, said wastegate valves controlling a bypass that circumvents the turbine wheel of the exhaust-gas turbocharger, in order to prevent any possible damage occurring to the exhaust-gas turbocharger if the exhaust-gas stream contains too much power. Poppet valves are usually used, the valve disc of which is pivoted by an adjusting lever, in order to open or close a bypass opening. In order to cope the changing temperatures and temperature gradients during implementation in an automobile, the connection between the valve disc and the adjusting lever has some play, thus allowing the valve disc to be properly adjoined to a valve seat. However, this leads to, for example, that the valve disc can move and thus rattle in the adjusting lever when the bypass valve is open. It is known from prior art that pre-stressing the valve disc in an axial direction retains the valve disc in an end position. 
         [0004]    A disadvantage of such an embodiment is that if a warping due to thermal expan-sions needs to be balanced out by the play between adjusting lever and valve disc, the force has to be overcome by the spring. Consequently, the actuating forces needed to close the bypass valve are relatively high. 
         [0005]    Such a valve device is known for example from DE 10 2010 043 147 A1. The valve disc is pre-tensioned in an axial direction relative to the adjusting lever by a spring-elastic tensioning element, whereby the valve disc is fixed in a predetermined position on the adjusting lever. 
         [0006]    A turbocharger with a wastegate valve, in which the valve disc is pre-tensioned in an axial direction against the adjusting lever by a disc spring, is known from WO 2010/135104 A2. 
         [0007]    WO 2014/011468 also discloses an exhaust-gas turbocharger with a wastegate valve, in which the valve disc is pre-tensioned against the adjusting lever by means of an annular spring element. 
         [0008]    A valve device for an exhaust-gas turbocharger, which has a centring element, which centres a mandrel of the valve disc in a through opening of the adjusting lever, is known from DE 10 2011 076 361 A1. 
         [0009]    Finally DE 10 2012 101 322 also discloses an exhaust-gas turbocharger with a wastegate valve in which a disc spring is provided, in order to axially pre-stress the valve disc relative to the adjusting lever. 
       SUMMARY 
       [0010]    It is the object of the invention to provide an improved or at least a different embodiment of a valve device, which is particularly distinguished by a cost-effective and simple production. 
         [0011]    The invention is based on the general concept of increasing the friction between the valve disc and the adjusting lever by means of a spring element, instead of pre-stressing the valve disc in an axial direction, and therefore being able to prevent a rattling of the valve disc within a through opening of the adjusting lever. Therefore, at least one spring element, which subjects the mandrel to a radial force, is arranged in the through opening. Said radial force to which the mandrel is subjected creates a frictional engagement between the mandrel of the valve disc and the through opening of the adjusting lever. This frictional engagement prevents the valve disc being able to move freely in the adjusting lever, thus preventing annoying noises, such as rattling or pattering. The service life of the valve device also increases. At the same time, the spring element enables the position of the valve disc, in particular of the mandrel of the valve disc, to adapt in the through opening of the adjusting lever, in order to balance out the temperature-related expansions of the individual components, thus allowing a sealed closure of the bypass opening at any time. 
         [0012]    The terms “radial” and “axial” in the description and the enclosed claims refer to the axis of the through opening of the adjusting lever, which is in particular designed in a circular manner. 
         [0013]    A favourable option provides that the at least one spring element extends at least partially radially between the interior surface of the adjusting lever and the mandrel. As the spring element extends radially between the interior surface of the adjusting lever and the mandrel, it allows the spring element to be supported on the interior surface and on the mandrel and thus to exert a radial force on the mandrel. 
         [0014]    A further favourable option provides that the spring element has a spring section, which extends within an annular gap formed between the mandrel and the adjusting lever and is designed in such a curved manner that it is tensioned when the mandrel is located in the through opening, and that the at least one spring element has at least one gripping section, which extends at an angle with relation to the spring section. This allows a tensioning of the mandrel within the through opening to be achieved very easily. Furthermore, the gripping section allows the spring element to be fixed to the adjusting lever and not slip. 
         [0015]    A particularly favourable option provides that the spring section extends in a substantially axial direction. This allows the spring section of the spring element to extend in the annular gap between the mandrel and the interior of the adjusting lever and thus exert a radial force on the mandrel. In the description and the enclosed claims “substantially extend in a axial direction” means that a main extension of the relevant element is in the axial direction. In particular, the extension in an axial direction is greater than in the radial direction. 
         [0016]    An advantageous solution provides that the spring section is designed in a convexly or concavely bent manner. This allows the spring section within the annular gap to change its radial expansion by curvature of the spring section, and therefore the spring section acts as a spring and can thus subject the mandrel to a radial force. 
         [0017]    A further advantageous solution provides that the spring section abuts against the mandrel if said mandrel is located in the through opening. Thereby is eliminated the radial play of the mandrel in the through opening and as well generated a frictional engagement between the mandrel and the through opening. 
         [0018]    A particularly advantageous solution provides that the spring section abuts against the interior of the adjusting lever. Thereby the spring section can be supported on the interior of the adjusting lever, in order to subject the mandrel to a radial force. 
         [0019]    A favourable variant provides that the gripping portion extends in a substantially radial direction. This allows the gripping section to engage behind an edge of the through opening, for example, and thus limit the axial mobility of the spring element, such that the spring element remains positioned in the through opening. In the descriptions and the enclosed claims “substantially extend in a radial direction” means that a main extension of the relevant element is in the radial direction. The extension in a radial direction is in particular greater than in the axial direction. 
         [0020]    A further favourable variant provides that the gripping portion abuts against the adjusting lever on a front side of the adjusting lever surrounding the through opening. The gripping section thus prevents the spring element from being able to slip completely into the through opening or even slip through the through opening and thus fall out of the annular gap. 
         [0021]    A particularly favourable variant provides that the at least one spring element has two gripping portions, which merge into the spring section at ends of said spring section that are remotely positioned with relation to each other. As the spring element has two gripping portions, said gripping portions are able to retain the spring element even better in the through opening. It can in particular be provided that the two gripping portions of a spring element abut against opposing front sides of the adjusting lever. Thereby the possibility of the spring element being removed from the through opening by a purely axial movement is prevented. If the mandrel is arranged in the through opening, the spring element can no longer be moved radially either, thus preventing the spring element from falling out of the through opening. 
         [0022]    A further particularly favourable variant provides that the at least one spring element is designed as a sheet metal shaped part. Such sheet metal shaped parts can be easily produced, thus resulting in a cost-effective solution. 
         [0023]    An advantageous option provides that the at least one spring element is designed in a C-shaped curved manner, thus allowing the two gripping sections as well as a convex spring section to be easily formed. 
         [0024]    A further advantageous option provides that the valve device has a plurality, three for example, of spring elements, which are arranged in the through opening in an evenly distributed manner, thus allowing a better centring of mandrel within the through opening to be achieved, which enables the stress and wear of the mandrel to be reduced. 
         [0025]    A particularly advantageous option provides that the adjusting lever has at least one groove in which the at least one spring element is arranged. The provision of the groove within the through opening of the adjusting lever allows the spring element to be positioned even better, thus in particular preventing the spring element from slipping in the circumferential direction. 
         [0026]    A favourable solution provides that the groove extends on the interior surface of the adjusting lever in an axial direction and that said groove transfers from the interior surface to the front surfaces at the front surfaces surrounding the through opening. This allows both the spring sections and the gripping portions of the spring elements to run within the groove, thus ensuring that the spring elements can be particularly well-positioned. 
         [0027]    A further favourable solution provides that the gripping portion in part of the groove, which extends in the front side of the adjusting lever, abuts against the adjusting lever. The gripping section thus allows the spring element to be positioned in an axial direction within the through opening. 
         [0028]    A particularly favourable solution provides that the at least one spring element is designed in an annular manner, wherein the spring section and the at least one gripping portion are each designed in an annual manner, thus allowing a particularly even distribution of the radial force on the mandrel to be achieved. 
         [0029]    An advantageous variant provides that the at least one spring element is a separate component with regard to the valve disc and the adjusting lever. This, for example, allows functionally and cost-optimised materials to be used for the mandrel, the adjusting lever and the spring element. 
         [0030]    A particularly advantageous variant provides that the mandrel has a flattened area on an exterior, against which the at least one spring element abuts, when the mandrel is arranged in the through opening. This way, an anti-rotation safeguard of the valve disc with relation to the adjusting lever can be achieved. 
         [0031]    The above-stated object is also solved by a charging device, in particular by an exhaust-gas turbocharger with a valve device pursuant to the above description. The advantages of the valve device are thus transferred to the charging device, to the preceding description of which reference is made in this respect. 
         [0032]    Furthermore, the above-stated object is achieved by a method for mounting a valve device pursuant to the preceding description, wherein the at least one spring element is initially inserted in the through opening and the mandrel is then guided into the through opening. This allows the adjusting lever to be pre-mounted together with the spring elements in a simple manner and the mandrel of the valve disc need only be inserted in the through opening. Thus, no retroactive tensioning of a disc spring intended to exert an axial force, for example, is required. The mounting of the valve device is thus simplified. 
         [0033]    Further important features and advantages of the invention result from the sub-claims, from the drawings and from the associated illustrative description of the figures by means of the drawings. 
         [0034]    It is understood that the previously stated and the still to be explained features below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the framework of the present invention. 
         [0035]    Preferred exemplary embodiments of the invention are illustrated in the drawings and will be explained in more detail in the following description, wherein like reference numerals relate to identical or similar or functionally identical components. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]    The figures schematically in each case show: 
           [0037]      FIG. 1  a greatly simplified schematic illustration of a charging device with a wastegate valve, 
           [0038]      FIG. 2  a sectional illustration of a valve device for a charging device according to  FIG. 1 , 
           [0039]      FIG. 3  a perspective illustration of an adjusting lever of a valve device according to  FIG. 2 , 
           [0040]      FIG. 4  a top view of a valve disc of a valve device according to  FIG. 2 , 
           [0041]      FIG. 5  a perspective illustration of an adjusting lever of a valve device according to a second embodiment, 
           [0042]      FIG. 6  a sectional illustration through the valve device according to  FIG. 5  in the area of a mandrel of a valve disc, 
           [0043]      FIG. 7  a perspective illustration of an adjusting lever of a valve device according to a third embodiment, and 
           [0044]      FIG. 8  a sectional illustration of the valve device in  FIG. 7  in the area of the mandrel of a valve disc. 
       
    
    
     DETAILED DESCRIPTION 
       [0045]    A charging device  10  illustrated in  FIG. 1 , in particular an exhaust-gas turbocharger, is used for charging internal combustion engines. The charging device  10  comprises a turbine  12  with a turbine wheel  14  and a compressor  16  with a compressor wheel  18 , which is non-rotatably connected with the turbine wheel  14  via a drive shaft  20 . The turbine wheel  14  is driven via an exhaust-gas stream  22 . The connection via the drive shaft  20  also drives the compressor wheel  18 , and therefore the power in the exhaust-gas stream  22  can be used to compress fresh air and supply it to the internal combustion engine. The charging device also comprises a bypass  24 , which circumvents the turbine  12 . This allows the exhaust-gas stream  22  to bypass the turbine  12 , and therefore the latter is not driven by the exhaust-gas stream. This can, for example, be necessary if the power of the exhaust-gas stream  22  is too great and could thus damage the turbine wheel  14  and/or the charging device  1 . 
         [0046]    A wastegate valve  26  is provided, in order to control the through-flow of the bypass  24 . To this end the wastegate valve  26  opens and closes a bypass opening  28 , such that the exhaust-gas stream  22  can either flow through the bypass  24  or cannot flow through if the bypass opening  28  is closed. 
         [0047]    The wastegate valve  26  comprises a valve device  30  with a valve disc and a valve seat  34 , which surrounds the bypass opening  28 . In a closed position the valve disc  32  rests on the valve seat  34 , thus closing the bypass opening  28  and meaning that no exhaust-gas stream  22  can flow through the bypass  24 . In an opened position the valve disc  32  is raised from the valve seat  34 , thus opening the bypass opening  28  and allowing part of the exhaust-gas stream  22  to flow through the bypass  24  and circumventing the turbine  12 . The valve disc  32  can be pivoted between the opened and closed positions. To this end, the valve disc  32  is retained on an adjusting lever  36 . 
         [0048]    The adjusting lever  36  is in turn driven by an actuating device  38 . Said actuating device  38  comprises a spindle  40 , on which the adjusting lever  36  is retained, a lever arm  42 , which is also retained on the spindle  40  and via which said spindle  40  can be rotated around a spindle axis  48 , and an actuating rod  44 , which is coupled with the lever arm  42  and a positioning drive  46 , and therefore the spindle  40  can be rotated via the servo drive  46 . The rotation of the spindle  40  allows the adjusting lever to be pivoted around the spindle axis  48 . This causes the valve disc  32  to also be pivoted around the spindle axis  48 , in particular between the opening and closing positions. 
         [0049]    As shown in  FIGS. 2 and 4 , for example, the valve disc  32  has a front side  50 , on which a sealing surface  52  is arranged, and which abuts against the valve seat  34  in the closed position, thus closing the bypass opening  28 . The sealing surface is, for example, round, in particular annularly designed, and the valve seat  34  is correspondingly designed in a complementary manner. Accordingly, the front side  50  of the valve disc  32  is preferably designed in an annular manner. 
         [0050]    The valve disc  32  has a rear side  54  facing away from the front side  50 , said rear side  54  running conically, for example, in an external area  56 . Located further inwards in the radial direction is a section  58 , which separates the conical externally- located area  56  from an abutment surface  60  for the adjusting lever  36 . Said abutment area  60  is a substantially plane annular surface via which the adjusting lever  36  can exert an axial force on the valve disc  32 , in order to press said valve disc  32  in the valve seat  34 . 
         [0051]    The abutment surface  60  surrounds a mandrel  62 , which axially extends outwards from the abutment surface  60 . In particular, the mandrel  62  is arranged in concentric relation to the front side  50  and/or the sealing surface and the abutment surface  60 . 
         [0052]    The mandrel  62  has a radially outer exterior surface  66 . Said exterior surface  66  has at least one flattened area  70  against which, for example, a spring element  72  can abut. The mandrel  62  engages through a through opening  64  of the adjusting lever  36 . Here, the exterior surface  66  of the mandrel  62  thereby abuts against the adjusting lever  36 , in particular with an interior surface  68 , which radially limits the through opening  64 . An annular gap  78  is formed between the exterior surface  66  of the mandrel  62  and of the interior surface  68  of the adjusting lever  36 . 
         [0053]    The mandrel  62  has a head  74 , on which a safety ring  76  is retained, which radially protrudes beyond the exterior surface  66  of the mandrel  62  and thus prevents the mandrel from being able to slide out of the through opening  64  of the adjusting lever  36 . The valve disc  32  is thus retained in the through opening  64  of the adjusting lever  36 . The valve disc  32  thus has both some radial and some axial play. This also allows the valve disc  32  to be raised from the valve seat  34  into the opened position by the adjusting lever  36 . 
         [0054]    The adjusting lever  36  is retained on the spindle  40  and can thus be pivoted around the spindle axis  48 . As shown as an example in  FIG. 3 , the through opening  64  of the adjusting lever  36  is eccentrically arranged with relation to the spindle axis  48 , thus allowing the valve disc  32  to be raised from the valve seat  34 , in particular by a rotation of the spindle  40  around the spindle axis  48 . 
         [0055]    The adjusting lever  36  has two front surfaces  80 , which surround the through opening  64  and substantially run parallel in relation to each other. The interior surfaces  68  radially limit the through opening  64 . Said through opening  64  is preferably designed in a circular manner. 
         [0056]    The adjusting lever further comprises a groove  82 , which axially extends on the interior surface  68  and continues to run at a transition to each of the front surfaces  80  and runs radially within the front surfaces  80 . The groove  82  thereby extends over the entire axial height of the interior surface  68 , whereas said groove  82  only partially extends within the front surfaces  80 , in particular in a radial direction preferably less than the length of the axial height of the interior surface  68 . 
         [0057]    The spring element  72  is arranged in such a way that it exerts a radial force on the mandrel  62 . This causes a frictional engagement between the mandrel  62  and the adjusting lever  36 , in particular between the exterior surface  66  of the mandrel  62  and the interior surface  68  of the adjusting lever  36 . This enables a relative movement in the axial and radial direction between the mandrel  62  and thus the valve disc  32  and the adjusting lever  36  within the framework of the axial and radial play, as long as the frictional force of the frictional engagement is overcome. Nevertheless, the frictional engagement prevents any uncontrolled rattling of the valve disc  32  in the adjusting lever  36 . The pre-stressing of the spring element allows the radial force and thus the frictional force of the frictional engagement to be specifically adapted, thus allowing the desired effect to be achieved. 
         [0058]    As shown for example in  FIG. 2 , the spring element  72  is arranged between the mandrel  62  and the adjusting lever  36 , in the annular gap  78  for example. If the spring element  72  is arranged in such a way, said spring element  72  can be favourably supported on the interior surface  68  of the adjusting lever  36 , in order to transfer a radial force to the mandrel  62  via the exterior surface  66  of said mandrel  62 . The mandrel is thus pressed against the opposite side of the interior surface  68  of the adjusting lever  36 , thus creating the frictional engagement there. 
         [0059]    The spring element  72  has a spring section  84  auf, which extends with the annular gap  78  and is curved. In particular, the spring section  84  is convexly curved, i.e. the spring section  84  in the axial centre of the spring section  84  juts further beyond the interior surface  68  than at the axial edges close to the front surfaces  80  of the adjusting lever  36 . 
         [0060]    As an alternative, the spring section  84  can also be designed in a concave manner, i.e. the spring section  84  in the axial center of the spring section  84  juts less beyond the interior surface  68  of the adjusting lever  36  than in the axial edge areas close to the front surfaces  80 . 
         [0061]    The curvature of the spring section  84  allows the latter to reduce its radial extension within the annular gap in that the curvature is straightened out, thus causing the spring-like conduct of the spring section  84 . 
         [0062]    Furthermore, the spring element  72  has two gripping portions  86 , which run at an angle in relation to the spring section  84 . At the axial ends of the spring section  84  said spring section  84  transfers into the two gripping portions  86 , which extend radially outwards from there and thus encompass the adjusting lever  36  in such a way that the gripping portions  86  abut against the two front surfaces  80 , thus causing the axial position of the spring element  72  to be determined by the gripping portions  86 . The spring element  72  cannot readily fall out of the through opening  64 . 
         [0063]    The spring element  72  is also arranged in the groove  82 , and therefore the spring element  72  is positioned in the circumferential direction of the through opening  64 . In interaction with the flattened area  70  of the mandrel  62  of the valve disc against which the spring element  72  abuts, this thus results in an anti-rotation safeguard of the valve disc in relation to the adjusting lever  36 . 
         [0064]    The spring element  72  is preferably configured as sheet metal shaped part and can thus be produced cost-effectively and of a qualitative high-class. 
         [0065]    When mounting the valve device, in particular when mounting the valve disc on the adjusting lever  36 , the at least one spring element  72  is initially inserted in the through opening  64  of the adjusting lever  36 . It is in particular inserted in the groove  82  in such a way that the gripping sections  86  abut against the front surfaces  80  of the adjusting lever  36  from axial directions and thus clamp the spring element  72  to the adjusting lever  36 . 
         [0066]    This allows the spring element  72  to be positioned very easily, with no fear of said spring element  72  falling out. 
         [0067]    Once the spring element  72  has been fitted to the adjusting lever  36 , the mandrel  62  of the valve disc  32  is inserted in the through opening  64  of the adjusting lever  36 . The safety ring  76  is subsequently fitted to the head  74  of the mandrel  62 , and therefore said mandrel  62  cannot slide out of the through opening  64  again. 
         [0068]    A second embodiment of the valve device  30  according to the invention shown in  FIGS. 5 and 6  differs from the first embodiment of the valve device  30  shown in  FIGS. 1 to 4  in that said valve device  30  comprises three spring elements  72 , which are arranged at substantially regular intervals in the circumferential direction. 
         [0069]    The radial force of the spring element  72  is thus distributed more evenly on the mandrel  62 , and therefore the valve disc  32  is better centred in the through opening  64 . The emerging frictional engagement is thus created between the mandrel  62  and the spring elements  72 . 
         [0070]      FIG. 7  shows an example of a spring element  72 , running in a concavely curved manner within the annular gap  78 . 
         [0071]    Moreover, the second embodiment of the valve device shown in  FIGS. 6 and 7  complies with regard to construction and function with the first embodiment of valve device  30  shown in  FIGS. 1 to 4 , to the preceding description of which reference is made in this respect. 
         [0072]    A third embodiment of the valve device  30  shown in  FIGS. 7 and 8  differs from the first embodiment of the valve device shown in  FIGS. 1 to 4  in that the spring element  72  is not limitedly configured in the circumferential direction, but is instead annularly designed. The spring element  72  thus has only one gripping portion  86 , which abuts against the front surface  80  of the adjusting lever  36  facing away from the front side  50  of the valve disc  32 . 
         [0073]    Alternatively, the spring element  72  can also be inserted between the support surface  60  and the front surface  80  of the adjusting lever  36   
         [0074]    Moreover, the third embodiment of the valve device shown in  FIGS. 7 and 8  complies with regard to construction and function with the first embodiment of valve device  30  shown in  FIGS. 1 to 4 , to the preceding description of which reference is made in this respect.