A dual-fluid injection system for an internal combustion engine, and an unmanned aerial vehicle (UAV) powered by an engine having the dual-fluid injection system. The dual-fluid injection system comprises a liquid fuel metering device and a fluid delivery device operating in tandem. A gas supply system comprising an air compressor and an air delivery path extending between the air compressor and the fluid delivery device is provided to supply pressurised air to the fluid delivery device. The gas supply system comprises an air compressor and an air delivery path extending between the air compressor and the fluid delivery device. A fuel supply system is adapted to deliver liquid fuel to the liquid fuel metering device. A fuel-air regulator is provided for regulating fuel pressure with reference to air pressure to establish and maintain a requisite pressure differential between the fuel pressure and the air pressure. The fuel-air regulator is located remotely from the fluid delivery device and more particularly in close proximity to the air compressor. In a preferred arrangement, the fuel-air regulator is mounted on or integrated with the air compressor or a part thereof.

Methods and systems are provided for operating a pre-chamber to provide ignition to a cylinder during catalyst heating. In one example, a method may include injecting fuel and air into a pre-chamber of an engine cylinder during an expansion stroke of the engine cylinder responsive to a temperature of a catalyst being less than a threshold temperature, and injecting the fuel and the air into the pre-chamber during a compression stroke of the engine cylinder responsive to the temperature of the catalyst being greater than or equal to the threshold temperature. In this way, the pre-chamber may provide robust ignition to the cylinder during a variety of operating conditions.

Methods and systems are provided for a ducted fuel injector. In one example, the ducted fuel injector comprises a plurality of passages, with at least one of the passages configured to receive an oxygen poor gas from a reservoir or an adjacent cylinder to decrease a likelihood of pre-ignition in the duct.

Methods and systems are provided for a ducted fuel injector. In one example, the ducted fuel injector comprises a plurality of passages, with at least one of the passages configured to receive an oxygen poor gas from a reservoir or an adjacent cylinder to decrease a likelihood of pre-ignition in the duct.

A method of operating an internal combustion engine system having a fuel injection system including a fluid delivery means operable to deliver a fuel entrained in gas directly into a combustion chamber. The method comprises supplying pressurised gas to the fluid delivery means from a gas supply system, and regulating gas pressure in the gas supply system. The gas pressure in the gas supply system may be regulated during a lag period between commencement of engine cranking and the delivery of fuel at a requisite fuel pressure to the fuel injection system. Regulating gas pressure in the gas supply system comprises opening the fluid delivery means to selectively allow gas to pass into the combustion chamber to relieve pressure in the gas supply system. Optionally, regulating gas pressure in the gas supply system may also comprise opening the fluid delivery means to selectively allow pressurised gas to flow from the combustion chamber to the gas supply system so as to pressurise the gas supply system.

A controller for an internal combustion engine of a spark ignition type is provided. When stopping combustion in a cylinder in a situation in which a crankshaft of the internal combustion engine is rotating, one of a fuel cut process and a fuel feeding process is selectively executed. When combustion is resumed in the cylinder in which the combustion has been stopped, an enrichment process is executed to control a fuel injection valve so that an air-fuel ratio is set to be richer than a stoichiometric air-fuel ratio. When the enrichment process is executed, a decrease amount of an oxygen storage amount of the three-way catalyst corresponding to the enrichment process is set.

A method of operating an internal combustion engine system having a fuel injection system including a fluid delivery means operable to deliver a fuel entrained in gas directly into a combustion chamber. The method comprises supplying pressurised gas to the fluid delivery means from a gas supply system, and regulating gas pressure in the gas supply system. The gas pressure in the gas supply system may be regulated during a lag period between commencement of engine cranking and the delivery of fuel at a requisite fuel pressure to the fuel injection system. Regulating gas pressure in the gas supply system comprises opening the fluid delivery means to selectively allow gas to pass into the combustion chamber to relieve pressure in the gas supply system. Optionally, regulating gas pressure in the gas supply system may also comprise opening the fluid delivery means to selectively allow pressurised gas to flow from the combustion chamber to the gas supply system so as to pressurise the gas supply system.

A controller for an internal combustion engine of a spark ignition type is provided. When stopping combustion in a cylinder in a situation in which a crankshaft of the internal combustion engine is rotating, one of a fuel cut process and a fuel feeding process is selectively executed. When combustion is resumed in the cylinder in which the combustion has been stopped, an enrichment process is executed to control a fuel injection valve so that an air-fuel ratio is set to be richer than a stoichiometric air-fuel ratio. When the enrichment process is executed, a decrease amount of an oxygen storage amount of the three-way catalyst corresponding to the enrichment process is set.

A dual-fluid injection system for an internal combustion engine, and an unmanned aerial vehicle (UAV) powered by an engine having the dual-fluid injection system. The dual-fluid injection system comprises a liquid fuel metering device and a fluid delivery device operating in tandem. A gas supply system comprising an air compressor and an air delivery path extending between the air compressor and the fluid delivery device is provided to supply pressurised air to the fluid delivery device. The gas supply system comprises an air compressor and an air delivery path extending between the air compressor and the fluid delivery device. A fuel supply system is adapted to deliver liquid fuel to the liquid fuel metering device. A fuel-air regulator is provided for regulating fuel pressure with reference to air pressure to establish and maintain a requisite pressure differential between the fuel pressure and the air pressure. The fuel-air regulator is located remotely from the fluid delivery device and more particularly in close proximity to the air compressor. In a preferred arrangement, the fuel-air regulator is mounted on or integrated with the air compressor or a part thereof.