Early closing miller cycle internal combustion engine

Abstract

The present invention mitigates restriction due to the fact that the opening period (angular working range) of the intake valve becomes smaller in the early closing Miller cycle operation, in which the intake valve closing timing occurs before the bottom dead center. The crankshaft center O 1 is offset on one side from the cylinder central axis X. The top dead center and the bottom dead center of the piston occur when the three points, namely the crankshaft center O 1 , the crankpin center O 2 , and the piston pin center O 3 are aligned in one line. At this time, the connecting rod and the crank arm are inclined relative to the axis X. The inclination angle θ bdc at the bottom dead center is greater than the inclination angle θ tdc at the top dead center. Therefore, as the crankshaft rotates in the direction of arrow ω, the intake process and the expansion process become greater than 180° CA, while the compression process and the exhaust process become smaller than 180° crank angle. Accordingly, the angular working range of the intake valve is enlarged. Therefore, the restriction to the valve lift curve is mitigated.

What is claimed is:  
     
         1 . An early closing Miller cycle internal combustion engine, comprising; 
 a piston slidably disposed in a cylinder to reciprocate along a cylinder central axis;    an intake valve disposed in an intake opening of said cylinder to open and close said intake opening;    an exhaust valve disposed in an exhaust opening of said cylinder to open and close said exhaust opening;    a valve driving device arranged to close said intake valve before bottom dead center to achieve the Miller cycle operation;    a crankshaft operatively coupled to said piston to move said piston in said cylinder, said crankshaft having a crankshaft center axis of rotation offset from said cylinder central axis in such a direction that an intake process and an expansion process have greater than 180° crank angle.    
     
     
         2 . The early closing Miller cycle internal combustion engine as set forth in  claim 1 , wherein 
 said valve driving device mechanically drives said intake valve by moving along with a movement of said crankshaft.    
     
     
         3 . The early closing Miller cycle internal combustion engine as set forth in  claim 1 , wherein 
 said valve driving device includes a hydraulic actuator which hydraulically drives said intake valve.    
     
     
         4 . The early closing Miller cycle internal combustion engine as set forth in  claim 1 , wherein 
 said valve driving device includes an electromagnetic actuator which drives said intake valve.    
     
     
         5 . The early closing Miller cycle internal combustion engine as set forth in  claim 1 , wherein 
 said valve driving device closes said intake valve at a predetermined closure timing that corresponds to a detected engine operating condition, and said predetermined timing is set before said bottom dead center at least under said detected engine operating condition.    
     
     
         6 . The early closing Miller cycle internal combustion engine as set forth in  claim 1 , wherein 
 said valve driving device is controllably arranged to vary a closure timing of said intake valve, said valve driving device controls said closure timing of said intake valve to a target closure timing of said intake valve that is determined based on a detected engine operating condition, and said target closure timing of said intake valve includes a timing set before said bottom dead center.    
     
     
         7 . The early closing Miller cycle internal combustion engine as set forth in  claim 4 , wherein 
 said valve driving device closes said intake valve at a predetermined closure timing that corresponds to a detected engine operating condition, and said predetermined timing is set before said bottom dead center at least under said detected engine operating condition.    
     
     
         8 . The early closing Miller cycle internal combustion engine as set forth in  claim 4 , wherein 
 said valve driving device is controllably arranged to vary a closure timing of said intake valve, and controls said closure timing of said intake valve to a target closure timing of said intake valve that is determined in accordance with a detected engine operating condition and said target closure timing of said intake valve includes a timing set before said bottom dead center.    
     
     
         9 . An early closing Miller cycle internal combustion engine, comprising; 
 a piston slidably disposed in a cylinder to reciprocate along a cylinder central axis;    intake valve means for opening and closing an intake opening of said cylinder;    an exhaust valve means for opening and closing an exhaust opening of said cylinder;    valve control means for closing said intake valve before a bottom dead center to achieve the Miller cycle operation;    crank means for moving said piston in said cylinder, said crank means having a center crank axis offset from said cylinder central axis in such a direction that an intake process and an expansion process have greater than 180° crank angle.