Abstract:
In an actuating device for a turbine of an exhaust gas turbocharger for controlling the charging pressure of the exhaust gas turbocharger, wherein a valve of the exhaust gas turbocharger has an actuating shaft onto which a connecting arm is firmly mounted and is pivotally coupled to an actuating link via a connecting bolt by which the actuating shaft can be pivoted about an axis of rotation by a translatory motion of the actuating link, the actuating shaft and the connecting bolt are engaged via a single integral locking element for retaining the actuating link in engagement with the connecting bolt and the actuating shaft.

Description:
This is a Continuation-In-Part application of pending international patent application PCT/EP2012/005084 filed Dec. 8, 2012 and claiming the priority of German patent application 10 2011 121 391.4 filed Dec. 17, 2011. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to an actuating device for a turbine of an exhaust gas turbocharger particularly for controlling the charging pressure of the exhaust gas turbocharger. 
     Such an actuating device is disclosed for example in US 2003/0196435 A1. The actuating device which serves to control the charging pressure of the exhaust gas turbocharger comprises a first bolt element which is rotatable about an axis of rotation. A valve element, a so-called waste gate, of the turbine is movable between a closed position and at least one open position via the first bolt element. 
     In the open position, the valve element opens a bypass duct, a so-called waste gate duct. The exhaust gas may bypass a turbine wheel of the turbine via the bypass duct so that the turbine wheel is not driven by the exhaust gas. The output of the turbine and thus the charging pressure of the exhaust gas turbocharger may be controlled by opening and closing of the bypass duct. 
     The first bolt element is non-rotatably joined to a connecting element, in this case to a connecting plate. The connecting element is articulatedly joined to an actuating element via a second bolt element. Here, the actuating element and the connecting element are joined rotatably about another axis of rotation relative to each other, with the axis of rotation and the other axis of rotation extending at least essentially parallel to each other. The actuating element is movable at least essentially vertically and translatorily to the axis of rotation of the first bolt element. 
     By moving the actuating element translatorily, the first bolt element is rotated about its axis of rotation due to the connection of the actuating element with the connecting element as well as due to the connection of the connecting element with the first bolt element. This is accompanied by the movement of the valve element of the turbine. 
     It was found that in particular due to wear as well as due to manufacturing-related tolerances some play between the connecting element and the bolt elements may develop which results in the generation of noises. 
     It is therefore the object of the present invention to develop an actuating apparatus for a turbine of an exhaust gas turbocharger of the above mentioned type in such a manner that the turbine noises are at least reduced. 
     SUMMARY OF THE INVENTION 
     In an actuating device for a turbine of an exhaust gas turbocharger, for controlling the charging pressure of the exhaust gas turbocharger, wherein a valve of the exhaust gas turbocharger has an actuating shaft onto which a connecting arm is firmly mounted and is pivotally coupled to an actuating link by a connecting bolt via which the actuating shaft can be pivoted about an axis of rotation by a translatory motion of the actuating link, a single integral intermediate locking element is provided for retaining the actuating link in engagement with the connecting bolt and the connecting bolt in engagement with the connecting arm. 
     With this arrangement, the above mentioned generation of noise can be kept particularly low or be prevented. The intermediate element which is common to the bolt elements provides for a compensation of in particular manufacturing-related and wear-related tolerances and clearances between the bolt elements and the connecting element, so that in particular rattling of the inventive actuating device is reliably prevented even over a long life. 
     In addition, the integral intermediate locking element which is common to the bolt and actuating shaft may be easily and thus quickly and cost efficiently installed and arranged between the actuating arm shaft and the connecting bolt. 
     In another advantageous embodiment, at least one of the connecting bolt and the actuating shaft, in particular the connecting bolt, element is locked in place via the integral intermediate locking element. This provides for a fixed and defined support so that any relative movement between the connecting bolt and the connecting arm and also the link is eliminated, and also noise resulting from such relative movement may be avoided even over a long life. 
     When the integral intermediate element is attached at one of the connecting bolt and the actuating shaft, in particular the actuating shaft, the number of parts and thus the costs of the inventive actuating apparatus will be kept low. Additional and separate fastening means are not necessary. In particular in combination with the two-sided support of the connecting bolt and the actuating shaft the intermediate locking element may be firmly and reliably secured. 
     In another embodiment of the invention, the at least one of the connecting bolt and the actuating shaft is held in engagement with the connecting arm by means of the intermediate locking element. Therefore, the intermediate locking element does not only fulfill the support function and thus the compensation of tolerances and clearances, respectively, but also the function of fastening the connecting bolt element at the actuating link. By this integration of functions the number of parts, the costs and the weight of the inventive actuating device may be kept within a particularly narrow range. 
     It is in particular possible to advantageously compensate for even relatively large tolerances and clearances if the intermediate locking element comprises at least one protrusion which is raised relative to at least a partial area adjoining the protrusion of the intermediate locking element and via which the intermediate locking element supports resiliently the connecting arm at least at the connecting bolt elements and/or at the actuating shaft, in particular. The protrusion facilitates in particular to clamp or to bias, respectively, the intermediate locking element at least with the connecting bolt or the actuating shaft. Thereby, any relative movement and the resulting noise may be reliably prevented even for a long service life and operating periods with extreme temperature variations. 
     The protrusion is advantageously formed by means of a coating, in particular a protective coating, on the intermediate locking element. Therefore, the intermediate locking element can be manufactured cost efficiently. It may further be provided to form the protrusion by at least a fiber and/or similar material build-up. 
     In order to reliably compensate for clearances and tolerances, even with large temperature variations, the intermediate locking element is advantageously disposed resiliently at the connecting bolt and actuating shaft locations. 
     In another advantageous embodiment of the invention, the intermediate locking element comprises through-holes which are assigned to the respective connecting bolt and actuating shaft elements and which are penetrated by the associated connecting bolt and operating shaft in a respective passage direction. Thus, the intermediate locking element may easily be mounted by inserting the connecting bolt and the actuating shaft e. g. in the passage direction through the respective through-holes. 
     In another embodiment, at least one of the through-holes is provided with an opening in the circumferential area, via which the associated bolt element may be inserted under an angle, in particular vertically, to the passage direction into the through-hole. This is beneficial for a particularly easy, quick and cost efficient installation, which keeps the costs of the actuating apparatus and thus of the entire turbine particularly low. 
     The intermediate locking element may be formed from a metallic material. There-fore, it has advantageous, in particular resilient, properties and can also at least essentially withstand large temperature variations without being damaged. The intermediate locking element is e. g. formed as a sheet metal strip. 
     The intermediate element may also be formed from a synthetic material. This results in a particularly low weight of the intermediate element and thus of the actuating apparatus. 
     Further advantages, features and details of the invention will become apparent from the following description of a preferred exemplary embodiment with reference to the accompanying drawings. The features and feature combinations as previously mentioned in the description as well as the features and feature combinations which will be mentioned in the following description of the figures and/or which are solely illustrated in the figures are not only applicable in the respective indicated combination but also in other combinations or isolated, without deviating from the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic perspective view of an actuating apparatus for a turbine of an exhaust gas turbocharger, via which a bypass valve for a bypass duct of the turbine is adjustable and which exhibits a particularly advantageous noise behavior; 
         FIG. 2  shows a schematic plan view of the actuating apparatus according to  FIG. 1 ; 
         FIG. 3  shows a schematic side view of the actuating apparatus according to  FIGS. 1 and 2 ; 
         FIG. 4  shows a schematic perspective view of an intermediate element of the actuating apparatus according to  FIGS. 1 to 3 ; 
         FIG. 5  shows a schematic perspective view of another embodiment of the intermediate element according  FIG. 4 ; and 
         FIG. 6  shows a schematic perspective view of another embodiment of the intermediate element according to  FIGS. 4 and 5 . 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       FIGS. 1 to 3  show an actuating apparatus  10  for a turbine of an exhaust gas turbocharger. The exhaust gas turbocharger serves, for example, to charge a combustion engine of an automobile. The exhaust gas turbocharger comprises a compressor with a compressor wheel by means of which air to be supplied to the combustion engine is to be compressed. The compressor may be driven via the turbine of the exhaust gas turbocharger. 
     For this purpose, the turbine comprises a turbine casing with a housing space in which a turbine wheel of the turbine is at least partially accommodated rotatably about an axis of rotation of the turbine wheel relative to the turbine casing. 
     The turbine casing further comprises at least one supply duct via which exhaust gas of the combustion engine may be supplied to the turbine wheel. The exhaust gas can flow into the turbine wheel and drive it. The turbine wheel is connected non-rotatably with a shaft of the exhaust gas turbocharger, with which the compressor wheel, too, is non-rotatably connected. Thereby, the compressor wheel is driven by the turbine wheel. 
     For controlling or regulating, respectively, of the charging pressure of the exhaust gas turbocharger which may be provided by the compressor, the turbine comprises at least one bypass duct. By means of the bypass duct, exhaust gas may be branched off upstream of the turbine wheel and be guided past the turbine wheel. In other words, the exhaust gas flowing through the bypass duct may bypass the turbine wheel without flowing into the turbine wheel and driving it. 
     For controlling the quantity or mass, respectively, of the exhaust gas flowing through the bypass duct a valve element, a so-called waste gate valve, is provided which may be adjusted between a closed position and at least one open position. In the closed position, the bypass duct is fluidly blocked so that no exhaust gas may flow into the bypass duct and bypass the turbine wheel. 
     In the at least one open position, the bypass duct is at least partially fluidly open so that exhaust gas may flow into the bypass duct and bypass the turbine wheel. 
     Here, the valve element is adjustable via the actuating apparatus  10 . The actuating apparatus  10  comprises an arm shaft  12  which penetrates the turbine casing and is non-rotatably connected with the valve element. The lever arm shaft  12  is rotatable about a lever arm shaft axis of rotation  14  relative to the turbine casing. For providing high functional reliability, a bearing sleeve  16  is provided via which the arm  12  is rotatably supported at the turbine casing. Moreover, a housing  18  is provided in which the lever arm shaft  12  is supported and which e. g. prevents a leakage of media such as exhaust gas, oil or the like from the turbine casing. 
     The actuating apparatus  10  further comprises a connecting arm  20  with a first through-hole which is penetrated by the lever arm shaft  12 . In other words, the lever arm shaft  12  is installed in the first through-hole of the connecting arm  20 . Here, the connecting plate  20  is non-rotatably connected with the lever arm haft  12 . 
     The actuating apparatus  10  also comprises a connecting bolt  22  which penetrates a second through-hole of the connecting arm  20 . In other words, the connecting bolt  22  is installed in the second through-hole of the connecting arm  20 . The connecting bolt  22  is articulatedly connected with the connecting arm  20 . This means that the connecting bolt  22  is connected with the connecting arm  20  rotatably about a connecting bolt axis of rotation  24  relative to the connecting arm  20 . 
     As can be seen in particular from  FIG. 3 , the lever arm shaft axis of rotation  14  and the connecting bolt axis of rotation  24  extend at least essentially parallel to each other. 
     The connecting bolt  22  is non-rotatably connected with an actuating link  26 . The actuating link  26  is provided with a third through-hole in which the connecting bolt  22  is installed. 
     Alternatively it may be provided that the connecting bolt  22  is non-rotatably connected with the connecting arm  20  and connected with the actuating link  26  rotatably about the connecting bolt axis of rotation  24  relative to the actuating link  26 . 
     The actuating link  26  is at least essentially normally and translatorily movable relative to the lever arm shaft axis of rotation  14  and the connecting bolt axis of rotation  24  and is articulatedly connected with the connecting  20  via the connecting bolt  22 . For a translatory movement or shifting, respectively, of the actuating link  26 , it is at least indirectly connected with a pressure sensor of the exhaust gas turbocharger. 
     When the valve element is e. g. in its closed position in which at least essentially the entirety of the exhaust gas flows to the turbine wheel driving it, and when the charging pressure of the exhaust gas turbocharger exceeds a predetermined threshold value, a diaphragm of the pressure sensor is caused to move. The movement of the diaphragm is transferred to the actuating link  26  so that the actuating link  26  is translatorily moved. Due to the described coupling of the actuating link  26  with the lever arm shaft  12  as well as due to the coupling of the lever arm belt shaft  12  with the valve element, the translatory movement of the actuating link  26  is transformed to a rotational movement of the lever arm shaft  12  about the lever arm bolt axis of rotation  14  and further to a swiveling motion of the valve element from its closed position to its open position. 
     In order to avoid undesired relative movements of the connecting arm  20  relative to the lever arm shaft  12  and relative to the connecting bolt  22 , an intermediate locking element  28  illustrated in  FIG. 4  is provided. The intermediate element is integrally formed and arranged in the direction of the lever arm shaft axis of rotation  14  or of the connecting bolt axis of rotation  24 , respectively, between the connecting arm  20  and the lever arm shaft  12  and between the connecting arm  20  and the connecting bolt  22 . In other words, both the lever arm shaft  12  and the connecting bolt  22  are secured on the connecting arm  20  via the integral intermediate locking element  28 . This provides for the compensation of manufacturing-related and/or wear-related tolerances or clearances, respectively, or clearances between the connecting arm  20  and the lever arm shaft  12 , or the connecting bolt  22 , respectively, so that relative motion between the connecting arm  20  and the lever arm shaft  12  and the connecting bolt  22 , respectively, and the noise resulting therefrom may be avoided or minimized. 
     As can be seen in particular from  FIG. 3 , the intermediate locking element  28  is arranged at a first side  30  of the connecting arm  20  between the lever arm bolt  12  and the connecting arm  20  and between the connecting bolt  22  and the connecting arm  20 . In addition, the intermediate locking element  28  is also arranged at a second side  32  of the connecting arm  20  facing away from the first side  30  between the connecting arm  20  and the connecting bolt  22 . Thereby, a particularly strong and advantageous connection of the connecting bolt  22  with the connecting arm  20  is implemented. In other words, the connecting arm  20  is secured at the connecting bolt  22  by means of the intermediate locking element  28  and vice versa, respectively. 
     The integral nature of the intermediate locking element  28  enables a quick and cost efficient assembly. Further, clearance and tolerance compensation is effected at all connecting points of the actuating apparatus  10  which may be prone to clearances by means of the only one integral intermediate locking element  28 . This also contributes to low wear of the actuating apparatus  10 . The intermediate locking element  28  also enables advantageously to avoid or minimize the generation of noise upon an excitation of the actuating apparatus  10 . 
     As can be seen in particular from  FIG. 4 , the intermediate locking element  28  comprises a first through-hole  34  in which the connecting bolt  22  is received at the second side  32 . Starting from the first through-hole  34 , the intermediate locking element  28 , which in the present case, is formed as a sheet metal strip extends around the connecting arm  20  to the first side  30 , where the intermediate locking element  28  comprises a second through-hole  36  for receiving the connecting shaft  22  at the first side  30 . 
     The intermediate locking element  28  further comprises a third through-hole  38  in which the lever arm shaft  12  is installed at the first side  30 . 
     The through-holes  34 ,  36 ,  38  each have a passage direction, in which they are penetrated by the connecting bolt  22  or the lever arm shaft  12 , respectively. While the second through-hole  36  is completely closed in the circumferential direction the through-holes  34 ,  38  comprise respective openings in the circumferential direction. It is e. g. possible to insert the lever arm shaft  12  into the third through-hole  38  vertically to its passage direction via the opening of the third through-hole  38 . In other words, the intermediate locking element  28  may be mounted vertically to the passage direction of the third through-hole  38  onto the lever arm shaft  12 . 
     This may apply analogously for the first through-hole  34  into which the connecting bolt  22  may be inserted vertically to the passage direction of the first through-hole  34 . On the other hand, this means that the intermediate element  28  may be mounted vertically to the passage direction of the first through-hole  34  onto the connecting bolt  22 . 
     The through-holes  34 ,  38  which are open in the circumferential direction are defined by respective straps  40  of the intermediate locking element  28 , which may encompass the connecting bolt  22  or the lever arm shaft  12 , respectively, in particular resiliently. Thereby, the intermediate element  28  is reliably secured both at the connecting bolt  22  and the lever arm shaft  12 . 
     The first through-hole  34  of the intermediate locking element  28  according to  FIGS. 5 and 6  is also completely closed in the circumferential direction so that the connecting bolt  22  may be inserted into the through-holes  34 ,  36  in the passage direction. 
     The intermediate locking element  28  also comprises first protrusions  42  and second protrusions  44 . The protrusions  42 ,  44  are raised relative to the partial areas adjoining the protrusions  42 ,  44  of the relatively thin-walled intermediate locking element  28 . The first protrusions  42  are assigned to the connecting bolt  22 , while the second protrusions  44  are assigned to the lever arm shaft  12 . The intermediate locking element  28  is supported on the first side  30  at the connecting arm  20  via the first protrusions  42 . Correspondingly, the intermediate locking element  28  is supported on the first side  30  at the connecting arm  20  via the second protrusions  44 . Because the intermediate locking element  28  is also supported at the connecting bolt  22  and at the lever arm shaft  12  the intermediate locking element  28  may be particularly firmly clamped between the connecting arm  20  and the lever arm shaft  12 , and the connecting bolt  22 , respectively, by means of the protrusions  42 ,  44  so that the connecting arm  20  is positively and advantageously engaged with the lever arm bolt  12  and the connecting bolt  22 . This provides for an efficient and effective compensation for clearances and/or tolerances. 
     Alternatively or additionally the intermediate locking element  28  may also be supported via at least one corresponding protrusion at the connecting bolt  22  and/or via at least one corresponding protrusion at the lever arm shaft  12 . 
     The protrusions  42 ,  44  are formed e. g. by stamping or the like of the sheet metal strip. The protrusions  42 ,  44  may, however, be also formed by a material build-up, e. g. by means of a coating, at least a fiber or a similar material build-up of the intermediate locking element  28 . 
       FIGS. 5 and 6  show further embodiments of the intermediate locking element  28 , which are adapted to specified installation conditions or installation conditions which may be predetermined, respectively.