A reentrant combustion chamber is disclosed. The reentrant combustion chamber includes a profile forming the inlet of the combustion chamber that is a projective surface formed inward in the combustion chamber and the bottom of the combustion chamber that is a recessed space that is recessed outward under the inlet in the combustion chamber, a cone formed in a truncated cone shape continuing from the profile and protruding to the central space in the combustion chamber, and a top end for expanding the space of the combustion chamber by expanding the top of the combustion chamber at the inlet of the combustion chamber.

The present disclosure improves serviceability of an automotive powertrain unit without deteriorating NVH characteristics. A powertrain includes an engine having a cylinder head; and a transmission coupled to the engine. The engine includes an EGR connected between an intake passage and an exhaust passage. The transmission is provided below the cylinder head in a vehicle height direction. The EGR is provided along a side of the cylinder head toward the transmission, and supported by the transmission.

A set of apparatus to inject distilled-water in solution acting as an engine coolant into the combustion chamber of a high-compression air-cooled piston aircraft engine to mix with aviation gasoline, operating on a minimum 91 motor octane aviation gasoline (leaded or unleaded), thereby improving engine performance, and suppressing early detonation in prescribed operating situations. The apparatus incorporates 1) an ultra-light weight corrosion-resistant engine coolant storage compartment mounted inside the aircraft, 2) stainless steel pipe fittings, 3) controller activated fluid injectors with wide spray nozzles, 4) aircraft-approved wiring and stainless steel plumbing tied to the pump and combustion chamber, 5) a primary and back-up electric pump approved for aviation use, 6) a special formulation of water-based cooling fluid in solution with a non-toxic anti-freezing agent designed for high altitude aircraft use, 7) electric sensors for temperature, pressure and early detonation programmed to a sensory control unit that automatically activates the electric pump to inject coolant only on pre-configured conditions during periods of peak engine performance when early detonation is most likely to occur, 8) a is digital metering display for the pilot instrument panel capable to report cylinder-head temperature, manifold pressure, oxygen (air/fuel ratio) and an aviation approved knock-sensor, and 8) a test switch and automatic operation on-off switch.

A neat-fuel direct-injected compression ignition engine having a thermal barrier coated combustion chamber, an injection port injects fuel that satisfies a stoichiometric condition with respect to the intake air, a mechanical exhaust regenerator transfers energy from exhaust gas to intake compression stages, an exhaust O.sub.2 sensor inputs to a feedback control to deliver quantified fuel, a variable valve actuation (VVA) controls valve positions, an exhaust gas temperature sensor controls exhaust feedback by closing the exhaust valve early according to the VVA, or recirculated to the chamber with an exhaust-gas-recirculation (EGR), heat exchanger, and flow path connecting an air intake, a load command input, and a computer operates the EGR from sensors to input exhaust gas according exhaust temperature signals and changes VVA timing, the load control is by chamber exhaust gas, the computer operates a fuel injector to deliver fuel independent of exhaust gas by the O.sub.2 signals.

A neat-fuel direct-injected compression ignition engine having a thermal barrier coated combustion chamber, an injection port injects fuel that satisfies a stoichiometric condition with respect to the intake air, a mechanical exhaust regenerator transfers energy from exhaust gas to intake compression stages, an exhaust O.sub.2 sensor inputs to a feedback control to deliver quantified fuel, a variable valve actuation (VVA) controls valve positions, an exhaust gas temperature sensor controls exhaust feedback by closing the exhaust valve early according to the VVA, or recirculated to the chamber with an exhaust-gas-recirculation (EGR), heat exchanger, and flow path connecting an air intake, a load command input, and a computer operates the EGR from sensors to input exhaust gas according exhaust temperature signals and changes VVA timing, the load control is by chamber exhaust gas, the computer operates a fuel injector to deliver fuel independent of exhaust gas by the O.sub.2 signals.

A gasoline compression ignition engine, a vehicle and a method of operating a gasoline compression ignition engine. An inlet air management system includes a membrane-based separator and an exhaust gas recirculation flowpath that cooperate to deliver a nitrogen enriched air stream to the engine to help reduce exhaust gas emissions. The separator segregates the incoming air into the nitrogen enriched air stream as well as an oxygen enriched air stream such that the latter can be used for various engine load conditions, as well as for supplemental air for a cabin or related passenger compartment within a vehicle that is powered by the engine. Significantly, during an increase in engine load not associated with the cold start and warm-up conditions, the nitrogen enriched air supply that is used for the exhaust gas emissions reduction is provided at least partially by the nitrogen enriched air stream from the separator, as well as increasingly by the nitrogen enriched combustion product stream from the exhaust gas recirculation flowpath.

Various methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system comprises a first fuel system to deliver liquid fuel to at least one cylinder of an engine, a second fuel system to deliver gaseous fuel to the at least one cylinder, and a controller. The controller is configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder thereby to ignite the liquid fuel and the gaseous fuel in the at least one cylinder via compression-ignition, and adjust an amount of the gaseous fuel relative to an amount 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.

Various methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system comprises a first fuel system to deliver liquid fuel to at least one cylinder of an engine, a second fuel system to deliver gaseous fuel to the at least one cylinder, and a controller. The controller is configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder thereby to ignite the liquid fuel and the gaseous fuel in the at least one cylinder via compression-ignition, and adjust an amount of the gaseous fuel relative to an amount 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.

The engines include compression cylinders, combustion cylinders, an air rail, and a heat exchanger. The methods of operating a compression ignition engine include taking air into a compression cylinder of the engine, compressing the air in the compression cylinder to raise the pressure and temperature of the air, passing the compressed air through a heat exchanger, and from the heat exchanger into a combustion cylinder, further compressing the compressed air during a compression stroke of the combustion cylinder, igniting fuel in the combustion cylinder at or near the end of the compression stroke by compression ignition, followed by a power stroke, and opening an exhaust valve at the end of the power stroke and passing at least some of the exhaust in the combustion cylinder through the heat exchanger to heat air that has been compressed in the compression cylinder and is then passing through the heat exchanger.

The engines include compression cylinders, combustion cylinders, an air rail, and a heat exchanger. The methods of operating a compression ignition engine include taking air into a compression cylinder of the engine, compressing the air in the compression cylinder to raise the pressure and temperature of the air, passing the compressed air through a heat exchanger, and from the heat exchanger into a combustion cylinder, further compressing the compressed air during a compression stroke of the combustion cylinder, igniting fuel in the combustion cylinder at or near the end of the compression stroke by compression ignition, followed by a power stroke, and opening an exhaust valve at the end of the power stroke and passing at least some of the exhaust in the combustion cylinder through the heat exchanger to heat air that has been compressed in the compression cylinder and is then passing through the heat exchanger.