Internal combustion engine and working cycle

Abstract

An internal combustion engine provides cooler working cycle and, selectively, mean effective cylinder pressure higher than conventional Otto and Miller cycle engine arrangements. According to one embodiment, during each cycle, intake valve is held closed during the initial portion of the intake stroke and then opened and closed. In another embodiment, during each cycle, intake valve opens twice, once opening and closing during the intake stroke and, then opening and closing again. In all embodiments, the last intake valve closing of the cycle is during the compression stroke at a point which captures a charge weight needed to power the engine and at such time that the effective compression ratio of the engine will be less than the expansion ratio. The combustion chambers, engine stroke and/or cylinder bore are selectively sized. An expansion valve is alternately provided to cool entry air, and may have a controllable, variable orifice.

1 . Method of operating an internal combustion engine, which engine includes a piston cycling in a cylinder through at least an intake stroke and a compression stroke, said method comprising the steps of preventing entry of air into the cylinder during an initial part of the intake stroke and then opening an intake port to the chamber and closing the intake port at point of piston travel in the compression stroke.  
   
   
       2 . Method of  claim 1 , including the step of cooling pressurized air and inducting the cooled, pressurized air into the cylinder through the open intake port.  
   
   
       3 . Method of  claim 2 , wherein the cooling step includes the step of expanding air through an orifice prior to entry of the air through the intake port.  
   
   
       4 . Method of  claim 3 , further including the step of selectively controlling the size of the orifice.  
   
   
       5 . Method of  claim 1 , wherein the step of closing the intake valve includes closing the intake port at a predetermined point of piston travel in the compression stroke.  
   
   
       6 . Method of  claim 1 , wherein the step of closing the intake valve includes varying from one cycle to another the point of closing of the intake valve.  
   
   
       7 . Method of  claim 1 , wherein the step of closing the intake port includes closing the intake port at a point of piston travel as late as possible in the compression stroke while still providing enough time for ignition to take place no later than at piston top dead center.  
   
   
       8 . Method of  claim 1 , wherein the step of closing the intake port includes closing the intake port at a point of piston travel which point falls within the range of greater than or equal to 25% of the compression stroke and 15° of piston travel before top dead center of the compression stroke, inclusive.  
   
   
       9 . Method of operating an internal combustion engine, which engine includes a piston cycling in a cylinder through at least an intake stroke and a compression stroke, said method comprising the steps of opening and closing an intake port to the cylinder twice during each cycle of the piston, wherein the first opening occurs prior to or during the intake stroke and the second closing occurs at a point of piston travel in the compression stroke.  
   
   
       10 . Method of  claim 7 , including the step of cooling pressurized air and inducting the cooled, pressurized air into the cylinder through the open intake port.  
   
   
       11 . Method of  claim 10 , wherein the cooling step includes the step of expanding air through an orifice prior to entry of the air through the intake port.  
   
   
       12 . Method of  claim 11 , further including the step of selectively controlling the size of the orifice.  
   
   
       13 . Method of  claim 9 , wherein the step of closing the intake valve includes closing the intake port at a predetermined point of piston travel in the compression stroke.  
   
   
       14 . Method of  claim 9 , wherein the step of closing the intake valve includes varying from one cycle to another the point of closing of the intake valve.  
   
   
       15 . Method of  claim 9 , wherein the second closing occurs at a point of piston travel as late as possible in the compression stroke while still providing enough time for ignition to take place no later than at piston top dead center.  
   
   
       16 . Method of  claim 9 , wherein the second closing occurs at a point within the range of 25% of the compression stroke and 15° before top dead center, inclusive.