Abstract: A control system for an engine including intake and exhaust valve phase variable devices and a control device is provided. At an engine temperature below a first determination temperature, the control is performed so that an exhaust valve close timing is at or retarded from the exhaust top dead center, an intake valve open timing is retarded from the exhaust valve close timing, and the fuel supply to the combustion chamber starts in an intake stroke on a retarding side of the exhaust valve close timing. At the engine temperature above the first determination temperature and below a second determination temperature, the control is performed so that a negative overlap with both the exhaust and intake valves closed during a period including the exhaust top dead center, or a positive overlap with both the exhaust and intake valves opened during a period including the exhaust top dead center, occurs.

Abstract: A control system for an engine including intake and exhaust valve phase variable devices and a control device is provided. At an engine temperature below a first determination temperature, the control is performed so that an exhaust valve close timing is at or retarded from the exhaust top dead center, an intake valve open timing is retarded from the exhaust valve close timing, and the fuel supply to the combustion chamber starts in an intake stroke on a retarding side of the exhaust valve close timing. At the engine temperature above the first determination temperature and below a second determination temperature, the control is performed so that a negative overlap with both the exhaust and intake valves closed during a period including the exhaust top dead center, or a positive overlap with both the exhaust and intake valves opened during a period including the exhaust top dead center, occurs.

Abstract: An engine system is provided, including a controller which controls devices of an engine at a given engine speed so that, when a demanded engine load is a first load, a mass ratio (G/F) of intake air inside a cylinder (containing fresh air and burnt gas) to fuel is a first G/F and mixture gas inside the cylinder combusts by flame-propagation, when the demanded load is a second load (<the first load), the G/F is a second G/F (>the first G/F) and an injection center-of-gravity is at a timing such that the entire mixture gas combusts by CI combustion, and when the demanded load is between the first and second loads, the G/F is at a third G/F (between the first and second G/Fs) and the injection center-of-gravity is at a later timing such that at least part of the mixture gas combusts by the CI combustion.

Abstract: An engine system is provided, including a controller which estimates an intake-valve-closing temperature inside a cylinder. When an engine operates at a given speed and a demanded engine load is a first load or a second load (>the first load), the controller controls so that a mixture gas inside the cylinder combusts by compression ignition, and controls so that, at the first load, the entire mixture gas combusts by compression ignition when the intake-valve-closing temperature is above a first temperature, and at least part of the mixture gas combusts by flame propagation when the intake-valve-closing temperature is below the first temperature, whereas at the second load, the entire mixture gas combusts by compression ignition when the intake-valve-closing temperature is above a second temperature (<the first temperature), and at least part of the mixture gas combusts by flame propagation when the intake-valve-closing temperature is below the second temperature.

Abstract: An engine system is provided, including a controller which estimates a mass ratio (G/F) of intake air inside a cylinder (containing fresh air and burnt gas) to fuel, and controls devices of an engine at a given engine speed so that, while a demanded engine load is a first load, at least part of a mixture gas inside the cylinder combusts by flame-propagation when the estimated G/F is below a first G/F, and the entire mixture gas combusts by compression ignition when the estimated G/F is above the first G/F, whereas while the demanded load is a second load (>the first load), at least part of the mixture gas combusts by flame-propagation when the estimated G/F is below a second G/F (<the first G/F), and the entire mixture gas combusts by compression ignition when the estimated G/F is above the second G/F.

Abstract: An engine system is provided, including a controller which estimates an intake-valve-closing temperature inside a cylinder. When an engine operates at a given speed and a demanded engine load is a first load or a second load (>the first load), the controller controls so that a mixture gas inside the cylinder combusts by compression ignition, and controls so that, at the first load, the entire mixture gas combusts by compression ignition when the intake-valve-closing temperature is above a first temperature, and at least part of the mixture gas combusts by flame propagation when the intake-valve-closing temperature is below the first temperature, whereas at the second load, the entire mixture gas combusts by compression ignition when the intake-valve-closing temperature is above a second temperature (<the first temperature), and at least part of the mixture gas combusts by flame propagation when the intake-valve-closing temperature is below the second temperature.

Abstract: An engine system is provided, including a controller which controls devices of an engine at a given engine speed so that, when a demanded engine load is a first load, a mass ratio (G/F) of intake air inside a cylinder (containing fresh air and burnt gas) to fuel is a first G/F and mixture gas inside the cylinder combusts by flame-propagation, when the demanded load is a second load (<the first load), the G/F is a second G/F (>the first G/F) and an injection center-of-gravity is at a timing such that the entire mixture gas combusts by CI combustion, and when the demanded load is between the first and second loads, the G/F is at a third G/F (between the first and second G/Fs) and the injection center-of-gravity is at a later timing such that at least part of the mixture gas combusts by the CI combustion.

Abstract: An engine system is provided, including a controller which estimates a mass ratio (G/F) of intake air inside a cylinder (containing fresh air and burnt gas) to fuel, and controls devices of an engine at a given engine speed so that, while a demanded engine load is a first load, at least part of a mixture gas inside the cylinder combusts by flame-propagation when the estimated G/F is below a first G/F, and the entire mixture gas combusts by compression ignition when the estimated G/F is above the first G/F, whereas while the demanded load is a second load (>the first load), at least part of the mixture gas combusts by flame-propagation when the estimated G/F is below a second G/F (<the first G/F), and the entire mixture gas combusts by compression ignition when the estimated G/F is above the second G/F.

Abstract: An engine is provided, which includes a combustion chamber defined by a cylinder head and a piston inside a cylinder of a cylinder block, a fuel injection nozzle provided to the cylinder head and formed in a tip-end part with a plurality of injection holes from which fuel is injected into the combustion chamber, the tip-end part being exposed to the combustion chamber, and a passage-forming member formed with a passage through which the injected fuel passes. The injection holes include first and second injection holes, and the passage-forming member is disposed around the tip-end part of the nozzle so as to cause a difference between a speed at which fuel injected from the first injection hole flows toward a circumferential part of the combustion chamber, and a speed at which fuel injected from the second injection hole flows toward the circumferential part.

Abstract: An engine is provided, which includes a combustion chamber defined by a cylinder head and a piston inside a cylinder of a cylinder block, a fuel injection nozzle provided to the cylinder head and formed in a tip-end part with an injection hole from which fuel is injected into the combustion chamber, the tip-end part being exposed to the combustion chamber, and a passage-forming member formed with a passage through which the fuel injected from the injection hole passes. An outer circumferential surface of the passage-forming member contacts a combustion-chamber ceiling surface of the cylinder head, and the passage of the passage-forming member includes an enlarged part gradually increasing in a cross-sectional area thereof from an upstream side to a downstream side of the passage.

Abstract: A structure of a combustion chamber applied to an engine provided with a piston that reciprocates inside a cylinder, and a fuel supply system that supplies fuel to the combustion chamber defined by the cylinder and the piston, mixture gas of fuel from the fuel supply system and air combusting inside the combustion chamber, is provided. The structure includes a first heat insulating layer covering at least a part of a combustion chamber wall surface defining the combustion chamber and made of a material with a lower thermal conductivity than the combustion chamber wall surface, and a second heat insulating layer covering the first heat insulating layer and facing toward the combustion chamber, a thermal diffusivity of the second heat insulating layer being larger than the thermal diffusivity of the first heat insulating layer. The second heat insulating layer has a thickness less than the first heat insulating layer.