A method of controlling a reciprocating internal combustion engine comprising: a cylinder defining a cavity having a first end and a second end; and a piston moveable within the cavity of the cylinder between the first end and the second end, the method comprising: receiving at least a first signal; determining a quantity of liquid air to be injected using at least the received first signal; controlling injection of the determined quantity of liquid air into the first end of the cavity at a first time when the piston is closer to the first end than the second end.

A method of controlling a reciprocating internal combustion engine comprising: a cylinder defining a cavity having a first end and a second end; and a piston moveable within the cavity of the cylinder between the first end and the second end, the method comprising: controlling injection of a quantity of liquid air, without fuel, into the first end of the cavity at a first time when the piston is closer to the first end than the second end to cause the piston to perform a first power stroke; and controlling injection of fuel into the first end of the cavity at a second time when the piston is closer to the first end than the second end to cause the piston to perform a second power stroke.

A method of controlling a reciprocating internal combustion engine comprising: a cylinder defining a cavity having a first end and a second end; and a piston moveable within the cavity of the cylinder between the first end and the second end, the method comprising: controlling injection of a quantity of liquid air, without fuel, into the first end of the cavity at a first time when the piston is closer to the first end than the second end to cause the piston to perform a first power stroke; and controlling injection of fuel into the first end of the cavity at a second time when the piston is closer to the first end than the second end to cause the piston to perform a second power stroke.

A two-stroke internal combustion engine achieves high performance levels by using an innovatively timed sequence of injecting and igniting fuel and oxidant. The operating cycle of the engine does not utilize a compression process. This permits the injection of fuel and oxidant to be coordinated with the initiation of the combustion process in such a way that the engine achieves high efficiency and provides high torque, while at the same time producing low thermal loading of engine components and low levels of engine noise and vibration.

A control system for a compression-ignition engine is provided, which includes the engine, a spark plug, a fuel injection valve, an air-fuel ratio control valve, and a control unit. A geometric compression ratio of the engine is 14:1 or above. The control unit includes a processor configured to execute an air-fuel ratio controlling module for, when the engine being in a given operating state is detected, controlling the air-fuel ratio control valve to bring the air-fuel ratio of the entire mixture gas to a given lean air-fuel ratio that is larger than a stoichiometric air-fuel ratio, and an spark plug controlling module for, after this control, outputting the control signal to the spark plug to perform the ignition at a given ignition timing so that the mixture gas starts combustion by flame propagation and then unburned mixture gas self-ignites. The given ignition timing is stored in a memory.

A two-stroke uniflow engine is provided with: a cylinder; a piston; an exhaust valve that is opened and closed in order to discharge exhaust gas that is generated inside the cylinder; a scavenging port that takes active gas into the interior of the cylinder in accordance with a sliding movement of the piston; a fuel injection port that is provided in the internal circumferential surface of the cylinder; a fuel injection valve that injects fuel gas into the fuel injection port; and a fuel injection control unit that executes control of the injection of the fuel gas in the fuel injection valve, wherein the fuel injection control unit decides at least one of an injection pressure and an injection time of the fuel injection valve based on a change in pressure inside the cylinder that is caused by a reciprocating movement of the piston.

A two-stroke uniflow engine is provided with: a cylinder; a piston; an exhaust valve that is opened and closed in order to discharge exhaust gas that is generated inside the cylinder; a scavenging port that takes active gas into the interior of the cylinder in accordance with a sliding movement of the piston; a fuel injection port that is provided in the internal circumferential surface of the cylinder; a fuel injection valve that injects fuel gas into the fuel injection port; and a fuel injection control unit that executes control of the injection of the fuel gas in the fuel injection valve, wherein the fuel injection control unit decides at least one of an injection pressure and an injection time of the fuel injection valve based on a change in pressure inside the cylinder that is caused by a reciprocating movement of the piston.

A control device of a compression-ignition engine is provided. The control device includes the engine having a cylinder, an exhaust gas recirculation system for introducing exhaust gas into the cylinder, and a controller for operating the engine by compression-ignition combustion of mixture gas inside the cylinder within a predetermined compression-ignitable range on a low engine load side. Within the compression-ignitable range, the controller sets an EGR ratio higher as the engine load becomes lower, and the controller sets the EGR ratio to a predetermined highest EGR ratio when the engine load is at a specific load that is on the low engine load side within the compression-ignitable range. When the engine load is lower than the specific load, the controller sets the EGR ratio to be lower than the highest EGR ratio.

A control device of a compression-ignition engine is provided. The control device includes the engine having a cylinder, an exhaust gas recirculation system for introducing exhaust gas into the cylinder, and a controller for operating the engine by compression-ignition combustion of mixture gas inside the cylinder within a predetermined compression-ignitable range on a low engine load side. Within the compression-ignitable range, the controller sets an EGR ratio higher as the engine load becomes lower, and the controller sets the EGR ratio to a predetermined highest EGR ratio when the engine load is at a specific load that is on the low engine load side within the compression-ignitable range. When the engine load is lower than the specific load, the controller sets the EGR ratio to be lower than the highest EGR ratio.