Desmodromic valve system including single cam surface for closing and opening the valve

Abstract

A desmodromic valve and cam system is provided. The system may comprise a cam lobe mounted to a cam shaft and defining an effective cam surface. The system may also comprise a rocker mounted to a valve wherein the rocker pivots up and down in response to an input of the cam lobe to close and open the valve. More particularly, the effective cam surface of the cam lobe pushes up on the rocker follower surface to close the valve and pushes down on the rocker follower surface to open the valve.

1 . A desmodromic valve and cam system for an internal combustion engine comprising an engine block and at least one head which utilizes at least one intake and one exhaust valve per cylinder, the system comprising:
 a main camshaft assembly adapted to be received within a plurality of journals disposed internally within the engine block, the camshaft assembly including one cam lobe for each intake valve and exhaust valve, each cam lobe having an effective cam surface facing radially outward;   a rocker pivotable about a rocker pivot axis, the rocker having a valve movement end adapted to be mechanically linked to a valve head such that the rocker can either push down or pull up the valve head as the rocker is respectively pivoted down or up about the rocker pivot axis to respectively open or close the valve, the rocker having closing and opening follower surfaces which are arranged and configured to radially face inward to a central portion of the rocker, the closing and opening follower surfaces being representative of desired valve performance characteristics, wherein the rocker is pivoted upward when the effective cam surface of the cam contacts the closing follower surface and pivoted downward when the effective cam surface of the cam contacts the opening follower surface;   wherein the cam lobes rotate such that the effective cam surface reciprocally contacts the closing follower surface and the opening follower surface to respectively close and open the valve without the need to use valve springs to close the valves.   
   
   
       2 . The desmodromic valve and cam system of  claim 1  wherein the closing and opening follower surfaces have an oblong circular configuration. 
   
   
       3 . The desmodromic valve and cam system of  claim 1  wherein the cam lobe has a circular configuration. 
   
   
       4 . The desmodromic valve and cam system of  claim 1  wherein the cam lobe defines an effective cam surface which is about one half of the outer periphery of the cam lobe. 
   
   
       5 . The desmodromic valve and cam system of  claim 1  wherein a rotating axis of the cam lobe is offset with a center of the cam lobe. 
   
   
       6 . The desmodromic valve and cam system of  claim 1  wherein the rocker comprises a first part and a second part which is removeably securable to each other to form the rocker. 
   
   
       7 . The desmodromic valve and cam system of  claim 1  wherein the closing and opening follower surfaces define a box shaped configuration. 
   
   
       8 . The desmodromic valve and cam system of  claim 1  wherein the rocker has a groove and the cam lobe has a mating protrusion for aligning the cam lobe to the rocker as the cam lobe rotates. 
   
   
       9 . The desmodromic valve and cam system of  claim 8  wherein a groove depth varies about a periphery of the rocker to control an amount of time that the valve stays closed, stays opened or both. 
   
   
       10 . The desmodromic valve and cam system of  claim 9  wherein a height of the protrusion varies about a periphery of the cam lobe to control the amount of time that the valve stays closed, stays opened, or both. 
   
   
       11 . A desmodromic valve and cam system for an internal combustion engine comprising an engine block and at least one head which utilizes at least one intake and one exhaust valve per cylinder, the system comprising:
 a main camshaft assembly adapted to be received within a plurality of journals disposed internally within the engine block, the camshaft assembly including one cam lobe for each intake valve and exhaust valve, each cam lobe having an effective cam surface facing radially outward;   a rocker pivotable about a rocker pivot axis, the rocker having a valve movement end adapted to be mechanically linked to a valve head such that the rocker can either push down or pull up the valve head as the rocker is respectively pivoted down or up about the rocker pivot axis to respectively open or close the valve, the rocker having a central aperture, the central aperture defining a travel path;   a slider sized and configured to slid up and down along the travel path within the central aperture of the rocker, the slider having opening and closing follower surfaces mateable with the effective cam surface of the cam lob, the opening and closing follower surfaces being arranged to face radially inward;   wherein the cam lobes rotate such that the effective cam surface reciprocally contacts the closing follower surface and the opening follower surface to respectively close and open the valve without the need to use valve springs to close the valves, and an angle of the travel path is representative of desired valve performance characteristics.   
   
   
       12 . The desmodromic valve and cam system of  claim 11  wherein a position of the rocker pivot axis in a horizontal direction and vertical direction is representative of desired valve performance characteristics. 
   
   
       13 . The desmodromic valve and cam system of  claim 11  further comprising a spring disposed between the rocker and slider to bias the slider to one side of the rocker. 
   
   
       14 . The desmodromic valve and cam system of  claim 13  wherein a spring force exerted on the slider by the spring is representative of desired valve performance characteristics. 
   
   
       15 . The desmodromic valve and cam system of  claim 11  wherein the opening and closing follower surfaces form a circular configuration. 
   
   
       16 . A desmodromic valve and cam system retrofit kit for an engine, the kit comprising:
 at least one cam lobe attachable to a stock cam shaft of the engine, the cam lobe defining an effective cam surface facing radially outward;   a corresponding rocker defining opening and closing follower surfaces facing radially inward, the opening and closing follower surfaces being representative of desired valve performance characteristics, the effective cam surface being mateable with the opening and closing follower surfaces in a reciprocal manner as the cam lobe rotates to pivot the rocker down and up about a rocker pivot axis to respectively open and close a valve of the engine, the rocker defining a valve moveable end and a lifter end;   a valve joint pivotally connected to the valve moveable end of the rocker and connectable to a stem of the valve;   a lifter joint pivotally connected to the lifter moveable end of the rocker and connectable to the lifter which is sized and configured to fit within a lifter aperture of the engine.