Methods and systems are provided for a vehicle engine having a pre-chamber ignition system. In one example, a method may include adjusting one or more of an air injection amount and a fuel injection amount to a pre-chamber of an engine based on an air injection offset and a fuel injection offset learned while discontinuing fueling to cylinders of the engine and reducing air flow through the engine. In this way, air and fuel may be more accurately provided to the pre-chamber, thereby decreasing an occurrence of pre-chamber misfire.

Methods and systems are provided for controlling engine knock. In one example, a method may include decreasing intake valve lift at a first set of cylinders where knock is indicated and increasing intake valve lift at a second set of cylinders where knock is not indicated. A stoichiometric air-to-fuel ratio is thereby maintained.

Methods, devices, controllers, and algorithms are described for operating an internal combustion engine wherein at least some firing opportunities utilize low temperature gasoline combustion (LTGC). Other firing opportunities may be skipped or utilize some other type of combustion, such as spark ignition. The nature of any particular firing opportunity is dynamically determined during engine operation, often on a firing opportunity by firing opportunity basis. Firings that utilize LTGC produce little, if any, nitrous oxides in the exhaust stream and thus, in some implementations, may require no aftertreatment system to remove them from the exhaust stream.

Various methods of control of combustion knock are disclosed in relation to a spark ignition, internal combustion engine having active tappets, whereby an inlet poppet valve can be moved independently of the usual operating cam. In one embodiment the invention provides for combustion knock to be controlled solely by variation of inlet air charge.

The present invention relates to a method for controlling lubrication of a connecting rod bearing of an internal combustion engine arrangement. The method comprises the steps of controlling an inlet valve to be maintained in the closed position during a movement of the reciprocating piston from the top dead center during an intake stroke for a predetermined number of crank angle degrees; and positioning the inlet valve in the open position when the reciprocating piston has traveled the predetermined number of crank angle degrees from the top dead center, wherein lubricating medium is provided to the connecting rod bearing within a predetermined time period before the inlet valve is arranged in the open position.

An engine system comprising an internal combustion engine and a turbocharger, where a diameter of the at least one intake valve is greater than a diameter of the at least one exhaust valve, the salient angle of the piston bowl is at least 10 degrees, the ratio between the piston bowl opening diameter and the piston bowl depth is approximately 0.5 to 2.0, the intake valve opens before top dead center on an exhaust stroke of the internal combustion engine and closes before bottom dead center of an intake stroke of the internal combustion engine, and the turbocharger has a combined efficiency of more than 50%.

Torque fluctuations caused by misfire and abnormal combustion are prevented appropriately at the time of switching from SI to HCCI, and exhaust of NOx is restricted at the time of switching. Provided is a control apparatus for an internal combustion engine performing a plurality of combustion modes each having a different air-fuel ratio and compression end temperature in a cylinder 7 from each other. In the middle of switching from a first combustion mode to a second combustion mode, an intermediate combustion mode in which the compression end temperature is increased while keeping a different air-fuel ratio from the air-fuel ratio of the first combustion mode and the air-fuel ratio of the second combustion mode is performed. Accordingly, at the time of switching between an operation mode performing SI and an operation mode performing HCCI, a temperature in the cylinder 7 and an air-fuel ratio are controlled appropriately, torque fluctuations caused by misfire and abnormal combustion can be prevented appropriately, and exhaust of NOx can be restricted.

A method for operating an internal combustion engine, involving the following steps: determining a target lambda value and measuring an actual lambda value for combustion in a combustion chamber of an internal combustion engine; establishing, in accordance with the target lambda value and the actual lambda value, a point in time for an intake valve associated with the combustion chamber to open; and opening the intake valve at the established point in time.

An internal combustion engine may have an intake valve device. A sudden load variation may be carried out in which a torque provided by the internal combustion engine is increased from a first value to a second value which is higher than the first value. While the sudden load variation is being carried out, the intake valve device may be operated according to an operating method different from the second operating method and is thereby closed later than in the second operating method. After the sudden load variation has been carried out, and while the internal combustion engine provides the torque having the second value after the sudden load variation has been carried out, the internal combustion engine may be switched over from the first operating method different from the second operating method to the second operating method.

The present invention relates to a method for controlling lubrication of a connecting rod bearing of an internal combustion engine arrangement. The method comprises the steps of controlling an inlet valve to be maintained in the closed position during a movement of the reciprocating piston from the top dead center during an intake stroke for a predetermined number of crank angle degrees; and positioning the inlet valve in the open position when the reciprocating piston has traveled the predetermined number of crank angle degrees from the top dead center, wherein lubricating medium is provided to the connecting rod bearing within a predetermined time period before the inlet valve is arranged in the open position.