Split-cycle aircraft engine

Abstract

A split-cycle aircraft engine includes a crankshaft rotatable about a crankshaft axis. A power piston is slidably received within a power cylinder and is operatively connected to the crankshaft such that the power piston reciprocates through an expansion stroke and an exhaust stroke during a single rotation of the crankshaft. A compression piston is slidably received within a compression cylinder and is 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 crossover passage operatively interconnects the compression cylinder and the power cylinder. An air reservoir is operatively connected to the gas crossover passage by a reservoir passage. The air reservoir is selectively operable to receive and deliver compressed air. The engine is mounted to an aircraft and the air reservoir is disposed within the aircraft.

1 . A split-cycle radial engine comprising:
 a crankshaft rotatable about a crankshaft axis;   a power bank including a plurality of power cylinders radially disposed around the crankshaft;   a power piston slidably received within each power cylinder and operatively connected to the crankshaft such that each power piston reciprocates through an expansion stroke and an exhaust stroke during a single rotation of the crankshaft;   a compression bank axially adjacent the power bank, the compression bank including a plurality of compression cylinders radially disposed around the crankshaft and equal in quantity to the number of power cylinders;   a compression piston slidably received within each compression cylinder and operatively connected to the crankshaft such that each compression piston reciprocates through an intake stroke and a compression stroke during a single rotation of the crankshaft;   each compression cylinder being paired with an associated power cylinder;   each compression and power cylinder pair including a gas crossover passage interconnecting the compression cylinder and the power cylinder of the pair, the gas crossover passage including an inlet valve and an outlet valve defining a pressure chamber therebetween; and   valves controlling gas flow into the compression cylinders and out of the power cylinders.   
   
   
       2 . The split-cycle radial engine of  claim 1 , wherein the compression cylinders of the compression bank are angled relative to the power cylinders of the power bank. 
   
   
       3 . The split-cycle radial engine of  claim 1 , wherein a longitudinal axis of each compression cylinder is offset from a rotational axis of the crankshaft. 
   
   
       4 . The split-cycle radial engine of  claim 1 , wherein a longitudinal axis of each power cylinder is offset from a rotational axis of the crankshaft. 
   
   
       5 . The split-cycle radial engine of  claim 1 , wherein the compression pistons have a shorter stroke than the power pistons. 
   
   
       6 . The split-cycle radial engine of  claim 1 , wherein the compression cylinders have a larger diameter than the power cylinders. 
   
   
       7 . The split-cycle radial engine of  claim 1 , wherein the power cylinders are arranged to fire in sequential order as the crankshaft rotates. 
   
   
       8 . The split-cycle radial engine of  claim 1 , wherein fuel is ignited in each power cylinder within a range of 5 to 40 degrees crank angle after the power piston associated with the power cylinder has reached its top dead center position. 
   
   
       9 . The split-cycle radial engine of  claim 1 , including an air reservoir operatively connected to the pressure chambers by a reservoir passage at locations between the inlet valve and the outlet valve of each pressure chamber, the air reservoir being selectively operable to receive and deliver compressed air.