An engine includes a combustion chamber including a cylinder wall defining a cylinder, a fuel injector disposed in a first opening in the cylinder wall and a piston head disposed in the cylinder. A piston bowl at least partially defined by a wall having a generally spiral shape is provided in a top of the piston head.

A combustion chamber for an opposed-piston engine has a rotationally skewed shape in a longitudinal section that is orthogonal to a chamber centerline, between diametrically-opposed openings of the combustion chamber through which fuel is injected. The rotationally skewed shape interacts with swirl to generate a tumble bulk charge air motion structure that increases turbulence.

A method for operating an internal combustion engine includes using a 3-front combustion method. When the fuel is injected into the combustion chamber the fuel flows through an injection element with a hydraulic flow of more than 1000 cubic centimeters per 60 seconds and under an injection pressure of 100 bar and 1 liter capacity per cylinder if the internal combustion engine is used in a truck application. The fuel flows through the injection element with a hydraulic flow of more than 1900 cubic centimeters per 60 seconds and under an injection pressure of 100 bar and 1 liter capacity per cylinder if the internal combustion engine is used in a car application.

A piston with an improved bowl geometry includes a piston body having a generally planar crown and a skirt extending from the crown. An oval or multi-lobed bowl rim of a combustion bowl that is recessed in the crown so that the sides of the bowl rim are provided with increased material to resist fatigue along the pin plane, optionally along the thrust/antithrust plane and generally optionally along other planes between the pin plane and the thrust/antithrust plane.

The internal combustion engine comprises a swirl control valve able to change a strength of a swirl generated in a combustion chamber; a load sensor for detecting an engine load; and a control device for controlling the swirl control valve. The control device controls the swirl control valve, when the engine load detected by the load sensor is lower than a predetermined load, so that the swirl ratio is higher when a suction intake gas amount is increasing, compared to when it is decreasing.

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.

A control device for an engine is provided, which includes a fuel injector attached to the engine, a spark plug disposed to be oriented into a combustion chamber, a swirl control valve provided in an intake passage, and a controller connected to the fuel injector, the spark plug, and the swirl control valve and configured to control the fuel injector, the spark plug, and the swirl control valve. The swirl control valve closes in a given operating state of the engine. The fuel injector injects fuel after the swirl control valve is closed, between intake stroke and an intermediate stage of compression stroke. The fuel injector injects the fuel after the first fuel injection. The spark plug performs the ignition after the second fuel injection so that the mixture gas starts combustion by flame propagation and then unburned mixture gas self-ignites.

A control system for a compression-ignition engine is provided, which includes an engine configured to combust a mixture gas inside a combustion chamber by compression ignition, a fuel injector attached to the engine, a state function adjusting part attached to the engine and configured to adjust at least introduction of fresh air into the combustion chamber, a three-way catalyst provided in an exhaust passage of the engine, a wall temperature acquiring part configured to acquire a parameter related to a temperature of a wall of the combustion chamber, and a controller. A swirl flow is generated inside the combustion chamber to circle along the wall. When the wall temperature of the combustion chamber is below a given wall temperature, the controller sets an air-fuel ratio of the mixture gas substantially to a stoichiometric air-fuel ratio so as to remain within a purification window of the three-way catalyst.

A control system for a pre-mixture compression-ignition engine is provided, configured such that in a first combustion mode, the control unit controls the fuel injection valve to have a fuel amount within a mixture gas in an outer circumferential portion of the combustion chamber larger than in the center portion, the swirl generating part to generate a swirl flow in the outer circumferential portion, and the spark plug to ignite the mixture gas in the center portion. In a second combustion mode, the control unit controls the fuel injection valve to start a fuel injection on intake stroke so that the mixture gas is formed in the entire combustion chamber, the swirl generating part so that a swirl flow becomes weaker than in the first combustion mode, and the spark plug to ignite the mixture gas before CTDC.

A piston with an improved bowl geometry includes a piston body having a generally planar crown and a skirt extending from the crown. An oval or multi-lobed bowl rim of a combustion bowl that is recessed in the crown so that the sides of the bowl rim are provided with increased material to resist fatigue along the pin plane, optionally along the thrust/antithrust plane and generally optionally along other planes between the pin plane and the thrust/antithrust plane.