摘要 |
An engine includes a crankshaft rotatable about a crankshaft axis. A compression piston is slidably received within a compression cylinder and operatively connected to the crankshaft. An expansion piston is slidably received within an expansion cylinder and operatively connected to the crankshaft. A crossover passage interconnects the compression and expansion cylinders. The crossover passage includes a crossover expansion (XovrE) valve disposed therein. In at least one of an Engine Firing (EF) mode, an Firing and Charging (FC) mode, and an Air Expander and Firing (AEF) mode of the engine, the timing of the XovrE valve closing is variable to control engine load, and the engine has a residual expansion ratio at XovrE valve closing of 14 to 1 or greater. |