The present invention provides systems, methods and apparatus to overcome limitations of liquid fuel engine combustion. Liquid fuel is mixed with superheated water which vaporizes, mixes with air and ignites within the injector nozzle. The injector nozzles then accelerate the mixture into the engine combustion chamber where unburned fuel vapor mixes and burns. Combustion begins the instant of injection and increases uniformly. Combustion pressure builds progressively. Combustion of fuel vapor is more ideal, and better controlled. As part of the system and apparatus, the present disclosure also includes a low-cost high-speed solenoid valve which produces shorter injection pulses. It also includes a high-speed, high-air-volume solenoid fuel valve. In addition, the present invention and its disclosure create tools to develop and optimize this new method of fuel vapor injection.

A control system of an engine including a cylinder and a fuel injector, the fuel mixing with air to form a mixture gas and combusting inside the cylinder is provided, which includes a water injector for injecting supercritical water or subcritical water into the cylinder, and a controller. Within a high engine speed operating range, the controller controls the water injector to inject the one of supercritical water and subcritical water into the cylinder for a given period including a top dead center of the cylinder on compression stroke, such that when an injection amount of the one of supercritical water and subcritical water reaches half of a given injection amount, a crank angle of the engine corresponds to a retarding side of the top dead center, the given injection amount being a total amount of the supercritical water or subcritical water injected for the given period.

A control system of an engine including a cylinder and a fuel injector, the fuel mixing with air to form a mixture gas and combusting inside the cylinder is provided, which includes a water injector for injecting supercritical water or subcritical water into the cylinder, and a controller. Within a high engine speed operating range, the controller controls the water injector to inject the one of supercritical water and subcritical water into the cylinder for a given period including a top dead center of the cylinder on compression stroke, such that when an injection amount of the one of supercritical water and subcritical water reaches half of a given injection amount, a crank angle of the engine corresponds to a retarding side of the top dead center, the given injection amount being a total amount of the supercritical water or subcritical water injected for the given period.

An engine system is provided that includes a cylinder, an exhaust flow part, a purifying system, a water injector for injecting supercritical/subcritical water into the cylinder, a water supply passage connected with the water injector and for supplying the water, a first temperature increasing device disposed at a position of the exhaust flow part and for increasing a water temperature, and a second temperature increasing device including a part of the exhaust flow part and a part of the water supply passage, and for increasing a water temperature. The first device increases the water temperature when an exhaust gas temperature passing through the position of the exhaust flow part exceeds a reference temperature. The second device increases the water temperature when an exhaust gas temperature passing through the part of the exhaust flow part is above a water temperature passing the part of the water supply passage.

An engine system is provided that includes a cylinder, an exhaust flow part, a purifying system, a water injector for injecting supercritical/subcritical water into the cylinder, a water supply passage connected with the water injector and for supplying the water, a first temperature increasing device disposed at a position of the exhaust flow part and for increasing a water temperature, and a second temperature increasing device including a part of the exhaust flow part and a part of the water supply passage, and for increasing a water temperature. The first device increases the water temperature when an exhaust gas temperature passing through the position of the exhaust flow part exceeds a reference temperature. The second device increases the water temperature when an exhaust gas temperature passing through the part of the exhaust flow part is above a water temperature passing the part of the water supply passage.