A fuel system for an engine has a cylinder with an inlet air port, an air box surrounding the inlet air port, and a gaseous fuel injector positioned in the air box and having a nozzle located at the inlet air port. The fuel system also has a gaseous fuel control valve, a fuel supply line fluidly extending from the gaseous fuel control valve to the gaseous fuel injector, a purge valve, and a purge fluid supply line fluidly extending from the purge valve to at least one of the fuel supply line and the gaseous fuel injector. The fuel system also has a return valve and a return line fluidly extending from at least one of the fuel supply line and the gaseous fuel injector.

In a dual-fuel fuel injector comprising a first injector unit for a first injector operating mode using a first main fuel and a second injector unit for a second injector operating mode using a second main fuel and an injector-reservoir, the reservoir is connected at one end to a first main fuel supply and at the opposite end to a second main fuel supply with a separating element disposed in the injector reservoir so as to be movable between the opposite ends so that, in each operating mode, the full volume of the reservoir can be used for accommodating the respective main fuel.

An objective of the present invention is to stabilize the fuel injection amount for each cylinder and to execute fuel injection control accurately in a single-pressure-feed dual-injection type alcohol fuel injection system. An engine includes two injection valves and and a single-pressure-feed dual-injection type fuel supply system. The fuel supply system is configured such that fuel is injected sequentially in two cylinders during the pressure-feed-interval period from the execution of one fuel pressure-feed operation to the execution of the next fuel pressure-feed operation. If the alcohol concentration in the fuel is higher than a predetermined determination value γ at a startup operation time, an ECU executes only a cylinder injection for the first of the two cylinders described above, and executes both an intake passage injection and a cylinder injection for the second cylinder. Thus, even if the fuel pressure decreases due to the fuel injection for the first cylinder, the required fuel injection amount can be reserved for the second cylinder.

A dual-fuel internal combustion engine includes: cylinders for combusting a first liquid fuel having a first ignitability in a first operating mode, and a second liquid fuel having a second lesser ignitability, in a second operating mode; a main injection system including a main injector for each cylinder, for feeding the first liquid fuel to the respective cylinders in the first operating mode and for feeding the second liquid fuel to the respective cylinders in the second operating mode; and a pilot injection system including a pilot injector for each cylinder, via which the first liquid fuel can is feedable to the respective cylinders in the second operating mode for igniting the second liquid fuel. The main and pilot injection systems are coupled such that in the second operating mode the first liquid fuel, is feedable to the respective main injector as a working fluid and/or a barrier fluid.

Methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system may include first and second fuel systems to deliver liquid and gaseous fuels, respectively, to at least one cylinder of the engine, and a controller. The controller may be configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder to compression ignite the liquid fuel and combust the gaseous fuel in the at least one cylinder, and retard an injection timing of the injection of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel. In some examples, the controller may further be configured to adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on the measured parameter.

Methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system may include first and second fuel systems to deliver liquid and gaseous fuels, respectively, to at least one cylinder of the engine, and a controller. The controller may be configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder to compression ignite the liquid fuel and combust the gaseous fuel in the at least one cylinder, and retard an injection timing of the injection of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel. In some examples, the controller may further be configured to adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on the measured parameter.

The invention relates to a fuel injector (1) for operating with combustible gas. The fuel injector has a plurality of combustible-gas nozzle valve elements (9), and the stroke of each of the combustible-gas nozzle valve elements can be controlled by means of a paired hydraulic piston control assembly (55) of the fuel injector, wherein each piston control assembly is formed by two control chambers (59, 61) and a piston section (63) on the combustible-gas nozzle valve element paired with the piston control assembly, said piston section separating the control chambers in such a way that their volumes can be varied, and the fuel injector is designed to control the stroke of the combustible-gas nozzle valve elements in tandem using a 3/2-way valve (67), by means of which the hydraulic pressure in one of the two control chambers of the piston control assemblies is controlled.

An engine system includes: an ammonia engine; a reforming device that has a reforming catalyst for cracking ammonia gas into hydrogen and configured to reform ammonia gas to generate reformed gas containing hydrogen; and a control unit. The control unit includes: a purge controller configured to control a reforming injector so as to be closed and control a reforming throttle valve so as to be opened, after an ignition switch gives an instruction of a stop of the ammonia engine; and an engine stop controller configured to control main injectors so as to be closed, after the ignition switch gives the instruction of the stop of the ammonia engine.

Fuel management system for enhanced operation of a spark ignition gasoline engine. Injectors inject an anti-knock agent such as ethanol directly into a cylinder. It is preferred that the direct injection occur after the inlet valve is closed. It is also preferred that stoichiometric operation with a three way catalyst be used to minimize emissions. In addition, it is also preferred that the anti-knock agents have a heat of vaporization per unit of combustion energy that is at least three times that of gasoline.

An engine system includes an engine having a combustion chamber, an intake gas passage through which air to be supplied to the combustion chamber flows, an exhaust gas passage through which exhaust gas generated from the combustion chamber flows, a reformer configured to reform the fuel to generate a reformed gas containing hydrogen, a gas supply passage through which air to be supplied to the reformer flows, a bypass passage connected to the gas supply passage and the exhaust gas passage so as to bypass the reformer and through which the fuel having passed through the reformer is circulated to an upstream of the reformer, and a switching valve switched between a normal position that does not allow the fuel having passed through the reformer to flow to the bypass passage and a circulating position that allows the fuel having passed through the reformer to flow to the bypass passage.