Abstract: 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.

Abstract: An engine includes a rotatable crankshaft and an expansion piston slidably received within an expansion cylinder and operatively connected to the crankshaft. A crossover passage including walls connects a source of high pressure gas to the expansion cylinder. A crossover expansion (XovrE) valve is operable to control fluid communication between the crossover passage and the expansion cylinder. The XovrE valve includes a valve head and a valve stem extending from the valve head. A fuel injector operable to inject fuel into the crossover passage includes a plurality of spray holes disposed in a nozzle end and aimed at an at least one target at which fuel emitting from the spray holes is directed to form at least one spray pattern. The at least one target is located above a seated position of the XovrE valve head and between the walls of the crossover passage and the XovrE valve stem.