Split four stroke engine

Abstract

An engine includes a crankshaft, rotating about a crankshaft axis of the engine. A power piston is received within a first cylinder and operatively connected to the crankshaft such that the power piston reciprocates through a power stroke and an exhaust stroke during a single rotation of the crankshaft. A compression piston is received within a second cylinder and operatively connected to the crankshaft such that the compression piston reciprocates through an intake stroke and a compression stroke during a single rotation of the crankshaft. A gas passage interconnects the first and second cylinders. The gas passage includes an inlet valve and an outlet valve defining a pressure chamber therebetween. The outlet valve permits substantially one-way flow of compressed gas from the pressure chamber to the first cylinder. The power piston descends to a firing position from its top dead center position.

1 . An engine comprising:
 a crankshaft, rotating about a crankshaft axis of the engine;   a power piston slidably received within a first cylinder and operatively connected to the crankshaft such that the power piston reciprocates through a power stroke and an exhaust stroke during a single rotation of the crankshaft;   a compression piston slidably received within a second cylinder and operatively connected to the crankshaft such that the compression piston reciprocates through an intake stroke and a compression stroke during a single rotation of the crankshaft; and   a gas passage interconnecting the first and second cylinders, the gas passage including an inlet valve and an outlet valve defining a pressure chamber therebetween, the outlet valve permitting substantially one way flow of compressed gas from the pressure chamber to the first cylinder;   wherein the power piston descends to a firing position from its top dead center position.   
   
   
       2 . The engine of  claim 1  wherein the inlet valve and the outlet valve of the gas passage substantially maintain at least a predetermined firing condition gas pressure in the pressure chamber during the entire intake, compression, power and exhaust strokes. 
   
   
       3 . The engine of  claim 1  wherein the crankshaft rotates at least 10 degrees past the power piston's top dead center position before the power piston descends to its firing position. 
   
   
       4 . The engine of  claim 1  wherein the power piston leads the compression piston by a phase shift angle that is substantially greater than zero. 
   
   
       5 . The engine of  claim 4  wherein the phase shift angle is equal to or greater than 20 degrees. 
   
   
       6 . The engine of  claim 1  comprising a first piston-cylinder axis along which the power piston reciprocates within the first cylinder, wherein the first piston cylinder axis has an offset from the crankshaft axis such that the first piston-cylinder axis does not intersect the crankshaft axis. 
   
   
       7 . The engine of  claim 1  comprising a second piston-cylinder axis along which the compression piston reciprocates within the second cylinder, wherein the second piston cylinder axis has an offset from the crankshaft axis such that the second piston-cylinder axis does not intersect the crankshaft axis. 
   
   
       8 . The engine of  claim 1  wherein the intake, power, compression and exhaust strokes comprise a four stroke cycle. 
   
   
       9 . The engine of  claim 1  comprising:
 a first mechanical linkage system operatively connecting the power piston to the crankshaft; and   a second mechanical linkage system operatively connecting the compression piston to the crankshaft;   wherein the first and second linkage systems share no common mechanical link.   
   
   
       10 . The engine of  claim 1  wherein the inlet valve permits substantially one way flow of compressed gas from the second cylinder to the pressure chamber. 
   
   
       11 . An engine comprising:
 a crankshaft, rotating about a crankshaft axis of the engine;   a power piston slidably received within a first cylinder and operatively connected to the crankshaft such that the power piston reciprocates through a power stroke and an exhaust stroke during a single rotation of the crankshaft;   a compression piston slidably received within a second cylinder and operatively connected to the crankshaft such that the compression piston reciprocates through an intake stroke and a compression stroke during a single rotation of the crankshaft; and   a gas passage interconnecting the first and second cylinders, the gas passage including an inlet valve and an outlet valve defining a pressure chamber therebetween, the outlet valve permitting substantially one way flow of compressed gas from the pressure chamber to the first cylinder;   wherein the crankshaft rotates at least 10 degrees past the power piston's top dead center position before the power piston descends to its firing position.   
   
   
       12 . The engine of  claim 11  wherein the inlet valve and the outlet valve of the gas passage substantially maintain at least a predetermined firing condition gas pressure in the pressure chamber during the entire intake, compression, power and exhaust strokes. 
   
   
       13 . The engine of  claim 11  comprising a first piston-cylinder axis along which the power piston reciprocates within the first cylinder, wherein the first piston cylinder axis has an offset from the crankshaft axis such that the first piston-cylinder axis does not intersect the crankshaft axis. 
   
   
       14 . The engine of  claim 11  comprising a second piston-cylinder axis along which the compression piston reciprocates within the second cylinder, wherein the second piston cylinder axis has an offset from the crankshaft axis such that the second piston-cylinder axis does not intersect the crankshaft axis. 
   
   
       15 . The engine of  claim 11  comprising:
 a first mechanical linkage system operatively connecting the power piston to the crankshaft; and   a second mechanical linkage system operatively connecting the compression piston to the crankshaft;   wherein the first and second linkage systems share no common mechanical link and the power piston leads the compression piston by a phase shift angle that is substantially greater than zero.   
   
   
       16 . The engine of  claim 11  wherein the intake, power, compression and exhaust strokes comprise a four stroke cycle. 
   
   
       17 . The engine of  claim 11  wherein the inlet valve permits substantially one way flow of compressed gas from the second cylinder to the pressure chamber.