Abstract: Actuators, and corresponding methods and systems for controlling such actuators, provide independent valve control with a large initial or opening force.

Abstract: A split-cycle engine includes an expander, the expander including an expansion piston received within an expansion cylinder. A compressor includes a compression piston received within a compression cylinder. A crossover passage interconnects the compression and expansion cylinders. An intake manifold is connected to the compression cylinder. A boosting device providing a 1.7 bar absolute or greater boost pressure level is connected to the intake manifold. An intake valve is disposed between the intake manifold and the compression cylinder. The intake valve closing is timed to provide a compressor volumetric efficiency of 0.75 or greater. A compressor displacement volume is sized relative to an expander displacement volume such that the combination of compressor displacement volume and boost pressure level provides an expander volumetric efficiency relative to ambient conditions that is 0.90 or greater.

Abstract: In split-cycle engines and air hybrid split-cycle engines, the sizing of the crossover passage is critical to engine efficiency. Efficiency can be improved by sizing the crossover passage volume to be small relative to the volume of the cylinders, and in particular relative to the volume of the compression cylinder. This allows for a higher pressure in the crossover passage, which extends the duration of sonic flow from the crossover passage into the expansion cylinder and increases combustion pressure. The methods, systems, and devices disclosed herein generally involve sizing the crossover passages, cylinders, or other components of a split-cycle engine or air hybrid split-cycle engine to improve efficiency.

Abstract: The engines, engine components, and related methods disclosed herein generally involve closing an exhaust valve through which exhaust gasses and other combustion products are evacuated from the expansion cylinder of a split-cycle engine before opening a crossover expansion valve through which a fresh charge of air and/or fuel is supplied to the expansion cylinder. The exhaust valve is preferably closed as late as possible after a combustion event, but with sufficient margin before opening of the crossover expansion valve and, in the case of an inwardly-opening exhaust valve, before valve-to-piston contact occurs. Preferably, the exhaust valve is closed about 0 CA degrees to about 15 CA degrees before the crossover expansion valve is opened.

Abstract: A split-cycle 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 such that the compression piston reciprocates through intake and compression strokes during a single rotation of the crankshaft. An expansion piston is slidably received within an expansion cylinder and operatively connected to the crankshaft such that the expansion piston reciprocates through expansion and exhaust strokes during a single rotation of the crankshaft. A crossover passage interconnects the expansion and compression cylinders. The crossover passage includes crossover compression (XovrC) and crossover expansion (XovrE) valves defining a pressure chamber therebetween. At least one of the XovrC and XovrE valves is a balanced valve.

Abstract: An engine has a rotatable crankshaft. A compression piston is received within a compression 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. An expansion piston is received within an expansion cylinder and operatively connected to the crankshaft such that the expansion piston reciprocates through an expansion stroke and an exhaust stroke during a single rotation of the crankshaft. A crossover passage interconnects the compression and expansion cylinders. The crossover passage includes a crossover compression valve and a crossover expansion valve defining a pressure chamber therebetween. A fuel injector is disposed in the pressure chamber of the crossover passage. Fuel injection from the fuel injector into the crossover passage is timed to occur entirely during the compression stroke of the compression piston.

Abstract: A split-cycle engine includes a crankshaft. A compression piston is received within a compression 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. An expansion piston is received within an expansion cylinder and operatively connected to the crankshaft such that the expansion piston reciprocates through an expansion stroke and an exhaust stroke during a single rotation of the crankshaft. A crossover passage interconnects the compression and expansion cylinders. The crossover passage includes a crossover compression (XovrC) valve and a crossover expansion (XovrE) valve defining a pressure chamber therebetween. The crossover compression valve is timed to open when the pressure in the compression cylinder is less than the upstream pressure in the crossover passage at the crossover compression valve.

Abstract: Methods, systems, and devices are disclosed that generally involve split-cycle engines in which a combustion event is initiated in a crossover passage that interconnects a compression cylinder and an expansion cylinder of the split-cycle engine. In one embodiment, the compression piston leads the expansion piston by a phase shift angle so that, for example, a substantial amount of the combustion event can occur in the crossover passage at a constant volume.

Abstract: An engine has a rotatable crankshaft. A compression piston is received within a compression 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. An expansion piston is received within an expansion cylinder and operatively connected to the crankshaft such that the expansion piston reciprocates through an expansion stroke and an exhaust stroke during a single rotation of the crankshaft. A crossover passage interconnects the compression and expansion cylinders. The crossover passage includes a crossover compression valve and a crossover expansion valve defining a pressure chamber therebetween. A fuel injector is disposed in the pressure chamber of the crossover passage. Fuel injection from the fuel injector into the crossover passage is timed to occur entirely during the compression stroke of the compression piston.

Abstract: Actuators, and corresponding methods and systems for controlling such actuators, provide independent valve control with a large initial or opening force.

Abstract: A split-cycle air-hybrid engine includes a rotatable crankshaft. A compression piston is slidably received within a compression cylinder and operatively connected to the crankshaft. An intake valve selectively controls air flow into the compression cylinder. 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 compression (XovrC) valve and a crossover expansion (XovrE) valve therein. An air reservoir is operatively connected to the crossover passage. In an Air Expander (AE) mode and an Air Expander and Firing (AEF) mode of the engine, the XovrC valve is kept closed during an entire rotation of the crankshaft, and the intake valve is kept open for at least 240 CA degrees of the same rotation of the crankshaft.

Abstract: A split-cycle air-hybrid engine includes a rotatable crankshaft. A compression piston is slidably received within a compression cylinder and operatively connected to the crankshaft. An intake valve selectively controls air flow into the compression cylinder. 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 compression (XovrC) valve and crossover expansion (XovrE) valve therein. An air reservoir is operatively connected to the crossover passage. An air reservoir valve selectively controls air flow into and out of the air reservoir. In a Firing and Charging (FC) mode of the engine, the air reservoir valve is kept closed until the XovrE valve is substantially closed during a single rotation of the crankshaft such that the expansion cylinder is charged with compressed air before the air reservoir is charged with compressed air.

Abstract: A split-cycle air hybrid engine includes a rotatable crankshaft. 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 compression (XovrC) valve and a crossover expansion (XovrE) valve defining a pressure chamber therebetween. An air reservoir is operatively connected to the crossover passage. An air reservoir valve selectively controls air flow into and out of the air reservoir. In an Air Expander and Firing (AEF) mode of the engine, the engine has a residual expansion ratio at XovrE valve closing of 15.7 to 1 or greater, and more preferably in the range of 15.7 to 1 and 40.8 to 1.

Abstract: An engine includes a rotatable crankshaft. 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 an Engine Firing (EF) mode of the engine, the engine has a residual expansion ratio at XovrE valve closing of 10.0 to 1 or greater, and more preferably 15.7 to 1 or greater.

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: A split-cycle air-hybrid engine includes a rotatable crankshaft. A compression piston is slidably received within a compression cylinder. An expansion piston is slidably received within an expansion cylinder. A crossover passage interconnects the compression and expansion cylinders. The crossover passage includes a crossover compression (XovrC) valve and a crossover expansion (XovrE) valve. An air reservoir is operatively connected to the crossover passage. An air reservoir valve selectively controls air flow into and out of the air reservoir. In an Engine Firing (EF) mode, the air reservoir valve is kept closed. In an Air Expander (AE) and an Air Expander and Firing (AEF) mode, the air reservoir valve is kept open for a duration that is at least as long as a duration of the XovrE valve opening event. In an Air Compressor (AC) mode and a Firing and Charging (FC) mode, the air reservoir valve is selectively opened and closed.

Abstract: A split-cycle air-hybrid engine includes a rotatable crankshaft. 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 compression (XovrC) valve and a crossover expansion (XovrE) valve defining a pressure chamber therebetween. An air reservoir is operatively connected to the crossover passage. An air reservoir valve selectively controls air flow into and out of the air reservoir. The engine is operable in an Air Expander and Firing (AEF) mode. In the AEF mode, the pressure in the air reservoir is greater than or equal to approximately 5 bar absolute, preferably greater than or equal to approximately 7 bar absolute, and more preferably greater than or equal to approximately 10 bar absolute.

Abstract: A split-cycle air-hybrid engine includes a rotatable crankshaft. 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 compression (XovrC) valve and a crossover expansion (XovrE) valve defining a pressure chamber therebetween. An air reservoir is operatively connected to the crossover passage. An air reservoir port connects the crossover passage to the air reservoir. An air reservoir valve is disposed in the air reservoir port. The air reservoir port includes a first air reservoir port section between the crossover passage and the air reservoir valve. The first air reservoir port section has a volume that is less than or equal to a volume of the crossover passage.

Abstract: A split-cycle air-hybrid engine includes a rotatable crankshaft. 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. An exhaust valve selectively controls gas flow out of the expansion cylinder. A crossover passage interconnects the compression and expansion cylinders. The crossover passage includes a crossover compression (XovrC) valve and a crossover expansion (XovrE) valve therein. An air reservoir is operatively connected to the crossover passage. An air reservoir valve selectively controls air flow into and out of the air reservoir. In an Air Compressor (AC) mode of the engine, the XovrE valve is kept closed during an entire rotation of the crankshaft, and the exhaust valve is kept open for at least 240 CA degrees of the same rotation of the crankshaft.

Abstract: An engine has a crankshaft, rotating about a crankshaft axis of the engine. An expansion piston is slidably received within an expansion cylinder and operatively connected to the crankshaft such that the expansion piston reciprocates through an expansion stroke and an exhaust stroke of a four stroke cycle during a single rotation of the crankshaft. A compression piston is slidably received within a compression cylinder and operatively connected to the crankshaft such that the compression piston reciprocates through an intake stroke and a compression stroke of the same four stroke cycle during the same rotation of the crankshaft. A ratio of cylinder volumes from BDC to TDC for either one of the expansion cylinder and compression cylinder is fixed at substantially 26 to 1 or greater.