Abstract:
Variable valve timing apparatus includes eccentric valve actuator sleeves which surrounds each of the valve actuators. In a preferred embodiment, the pivoting sleeves act to change the position of the valve actuator axis related to the camshaft axis. In combination with roller style cam follower, a movement of the actuator axis in camshaft rotation direction it causes a delayed valve operation, meantime a movement of the actuator axis towards the camshaft rotation direction it causes a advanced valve operation mode.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a valve actuator arrangement in internal combustion engines. In particular, the invention pertains to pivoting, eccentric valve actuator sleeves with lever arms. By its use, the valve timing in internal combustion engines can be varied. 
         [0002]    The aforementioned system has the fundamental concept of making it possible to regulate the valve timing in an internal combustion engine with camshaft-in-block valvetrain layout, such as the traditional American style V6, V8 and V10 engines. Engines with variable valve drive have major advantages over “normal” engines. They have excellent running properties over the entire rpm range. Both pollutant emissions and fuel consumption can be reduced considerably. Because the valve control times are designed to be regulatable, higher outputs can be attained even with smaller engine displacement. 
         [0003]    US Patent 2008/223321 discloses a valve system which allow a secondary valve event to be enabled or disabled. U.S. Pat. No. 5,937,809 discloses a system in which the valve timing are variable by the rotation of the rocker arm about the camshaft. US Patent 2007/000459 show a roller actuator with integrated deactivating device. U.S. Pat. No. 5,664,463 discloses a assembled style camshaft, in which shaft elements are positioned one inside the other. DE102009037976 discloses a camshaft hub for variable adjustment of valve timing. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    Compared to the prior art, the eccentric valve actuator sleeves during the rotatory switchover process from a initial leaver arm position to a changed leaver arm position it causes a circular motion of the valve actuator and corresponding a change of its position related to the camshaft axis. Dependent of the specific geometry and eccentricity of said sleeves, a movement of the valve actuator axis towards to the camshaft rotation direction can be achieved, or alternatively a movement of the valve actuator axis in camshaft rotation direction can be achieved. In combination with valve actuators with roller style cam follower a change of the valve actuator position towards camshaft rotation direction it causes a advanced valve operation, while a change of the valve actuator position in camshaft rotation direction it causes a retarded valve operation. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0005]    The invention is described below in terms of an exemplary embodiment in conjunction with the schematic drawings. The variant described is based for instance on a V-8 engine with a single camshaft which is located central into the engine block. The drawings show the following: 
           [0006]      FIG. 1 , a partial engine block with installed camshaft, equipped with eccentric valve actuator sleeves with lever arms according to the invention, further a exemplary hydraulic actuator device with linkage which act in conjunction with the actuator sleeves lever arms for changeover the rotatory position of the sleeves. 
           [0007]      FIG. 2 , bottom view, frontal view and trimetric view of a single eccentric valve actuator sleeve exemplary for incoroprate a valve actuator which act in conjunction with the intake valve. 
           [0008]      FIG. 3 , an mirrored version corresponding to  FIG. 2 , exemplary for incoroprate a valve actuator which act in conjunction with the exhaust valve. 
           [0009]      FIG. 4 , top view of a eccentric valve actuator sleeve pair, encluding the surrounded valve actuator pair which provide the valve operation for a single cylinder. The displayed position of the sleeves lever arms and the corresponding position of the eccentricity show the initial position which provide a specific valve operation timing. 
           [0010]      FIG. 5 , top view according  FIG. 4 , however the position of the lever arms and the according position of the valve actuators is displayed in changed position. 
           [0011]      FIG. 6 , Sectional view according  FIG. 4 . These view show the initial situation according  FIG. 4 . The displayed actuators  28  and  30  show optionally switchable hydraulic valve actuators which allows a decommissioning of the according cylinder by deactivation of valve operation. 
           [0012]      FIG. 7 , Sectional view according  FIG. 5 . These view show the changed situation, also in combination with switchable hydraulic valve actuators. 
           [0013]      FIG. 8 , Show a exemplary valve actuator guide which act in conjunction with the exhaust valve actuators. These guide is in order to keep the valve actuators from rotating during pivoting of the valve actuator sleeves. 
           [0014]      FIG. 9 , Show the according valve actuator guide for the intake valve actuators. It is mounted on the top of the intake valve actuator guide shown in  FIG. 8   
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    Referring to  FIG. 1 , there is shown a partial cylinder block  10  including a plurality of cylinders. The engine is illustrated without the cylinder heads in which the engine intake and exhaust valves and a substantial portion of the valve actuating mechanism or valve train are mounted. The valve mechanism may be of any known type for actuating engine valves depending upon the particular type of engine. The camshaft  12  is installed, the notional rotation direction is illustrated by an arrow  14 , and the camshaft rotation axis  16  is visible. 
         [0016]    In the illustrated embodiment the engine has two cylinder banks  18 , and  20 . Between said cylinder banks a lifter valley area  22  is located. In said area bores are located in which eccentric valve actuator sleeves  24 ,  26  are implemented to incorporate conventional hydraulic valve actuators  28   30 , or optionally switchable hydraulic valve actuators  32 . Both type of valve actuators are roller style cam followers and commonly used for camshaft in block engines. 
         [0017]    A exemplary actuator device with exemplary two hydraulic actuators  34 ,  36  acts in conjunction with the linkage  38  to the lever arms  40  of the sleeves. 
         [0018]      FIG. 2  show a eccentric valve actuator sleeve  24  for incorporate a intake valve actuator,  FIG. 3  show a corresponding mirrored version  26  for incorporate a exhaust valve actuator. The sleeves are equipped with oil passage bores  42  for supply the valve lash adjusting mechanism of the surrounded valve actuators, and optionally with additional oil passage bores  44  for supply the switching mechanism of optional switchable valve actuators. 
         [0019]      FIG. 4  show a top view of a embodiment with two eccentric valve actuator sleeves which act in conjunction with a single cylinder. The valve actuator  28  is surrounded by the sleeve  24  and act in conjunction with the intake valve, the valve actuator  30  is surrounded by the sleeve  26  and act in conjunction with the exhaust valve. The displayed configuration show the lever arms  40  of the valve actuator sleeves, the piston  46  of the hydraulic actuator  34  and the linkage  38  in initial position. Because the eccentrically position of the valve actuator  28 , the actuator axis  48  is located on the right—hand side of the camshaft rotation axis  16 , analogous it is moved in rotation direction  14  of the camshaft. This configuration provide a delayed operation mode for the actuator  28  and the corresponding intake valve. On the other hand the actuator axis  50  is located on the left—hand side of the camshaft rotation axis  16 . It is moved towards the rotation direction  14  of the camshaft, and provide an advanced operation mode for the actuator  30  and the corresponding exhaust valve. 
         [0020]      FIG. 5  show the arrangement of  FIG. 4  in changed position. During the rotatory switching operation the actuator axis  48  change his position from the right—hand side of the camshaft rotation axis  16  towards the camshaft rotation direction  14  to the left—hand side of the camshaft rotation axis. The valve actuator  28  and the corresponding intake valve change from the delayed operation mode to a advanced operation mode. Simultaneously the actuator axis  50  change his position from the left—hand side to the right—hand side of the camshaft rotation axis  16 , and change from the advanced operation mode to a delayed operation mode for the corresponding valve actuator  30  and the corresponding exhaust valve. 
         [0021]      FIG. 6  show a sectional view corresponding  FIG. 4 . which display the initial situation before the changeover. It present the insides of an arrangement in conjunction with the invention. These arrangement is exemplary equipped with optional switchable hydraulic valve actuators  28  and  30  with integrated switching mechanism  56 . Said valve actuators allows a deactivation of valve function on demand. A commonly integrated hydraulic lash adjusting device are provided by the oilline  52  which commonly is pressurized continuously, in the meantime an additional oilline  54  is provided to supply the switching mechanism of the switchable valve actuators with pressurized oil on demand. In combination with switchable valve actuators additional bores  44  are located on the circumference of the eccentric valve actuator sleeves to build a connection between the oilline  54  an the switching mechanism  56 . The arrangement in  FIG. 6  show the valve actuator axis  50  located on the left—hand side of the camshaft rotation axis  16 . By keep in mind a clockwise rotation direction of the camshaft, the corresponding valve actuator  30  show a advanced operation mode, in the meantime the valve actuator  28  on the background show a right—hand offset and is working in a delayed operation mode. 
         [0022]    The arrangement in  FIG. 7  show the arrangement in changed position according  FIG. 5 . During the switching operation the valve actuator axis  50  change from the left—hand side to the right—hand side of the camshaft rotation axis  16 . The corresponding valve actuator  30  change from a advanced operation mode to a delayed operation mode. In the meantime the valve actuator  28  on the background make a opposite movement and change from a delayed operation mode to a advanced operation mode. 
         [0023]    In order to keep the valve actuators from rotating with the rotary sleeves, the upper portions of the actuator bodies are provided with flats, which are engaged by valve actuator guides. Both, intake valve actuators and exhaust valve actuators require a separate and independent guide device.  FIG. 8  illustrate exemplary a actuator guide device  58  which act in conjunction with the intake valve actuators only. Elongated recesses  60  and increased clearance  62  around each exhaust valve actuator allow a limited linear movement of the guide device parallel to the camshaft axis without to act against the exhaust valve actuators. This ensure a proper alignment of the intake valve actuators without to limit the required freedom of movement during the synchronous and circular movement of the valve actuators during the switching operation. 
         [0024]      FIG. 9  show the corresponding guide device  64  for the exhaust valve actuators which is mounted on the top of the guide device  58 . Both, intake and exhaust actuator guides are guided and hold down in position by stepped bushings  66 , which are fixed with screws  68 . 
         [0025]    While the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. For example, the variability of the described embodiment could be increased by the use of separate actuation devices for both, intake valve actuator sleeves and exhaust valve actuator sleeves. Also a detection of the pivoting position of the sleeves with sensors for determine a specific lever arm position and the corresponding resulting valve operation condition could be implemented. Accordingly, it is intended that the invention not be limited to the disclosed embodiments, but that it have the full scope permitted by the language of the following claims.