Systems and methods for determining fuel delay in a fuel injected engine with cylinders that may be deactivated are presented. In one example, the fuel injection delay is determined via a cylinder firing schedule array when the cylinder firing schedule array is available. The fuel injection delay is determined via weighted average of a fuel injection delay of a present engine cycle and a fuel injection delay of a past engine cycle when the cylinder firing schedule array is not available.

The present invention relates to a method for operating an internal combustion engine provided as a medium-speed gas engine or dual fuel engine in a gas fuel mode. The method comprises the step of directly injecting a gas fuel into a combustion chamber of the engine at a maximum injection pressure that is lower than a compression-end pressure of the engine.

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.

An engine according to an embodiment includes at least one cylinder, at least one piston disposed in the at least one cylinder, a plurality of fuel injection valves disposed on the at least one cylinder, the plurality of fuel injection valves including a first fuel injection valve having a predetermined total hole area and a second fuel injection valve having a total hole area smaller than the total hole area of the first fuel injection valve, and a control device for controlling the first fuel injection valve and the second fuel injection valve according to a load of the engine.

A method of controlling a skip-fire cylinder deactivation system of an engine system is provided. The method includes a controller deactivating a cylinder of the engine system to operate the engine system in a skip-fire mode. The method further includes determining a temperature of an injector tip nozzle associated with the cylinder and comparing the temperature of the injector tip nozzle to a threshold a temperature. In response to determining that the temperature of the injector tip nozzle is greater than the threshold temperature, the cylinder is activated by the controller.

Some embodiments described herein relate to a method of operating a compression ignition engine. The method of operating the compression ignition engine includes opening an intake valve to draw a volume of air into a combustion chamber, closing an intake valve, and moving a piston from a bottom-dead-center (BDC) position to a top-dead-center (TDC) position in the combustion chamber at a compression ratio of at least about 15:1. The method further includes injecting a volume of fuel into the combustion chamber at an engine crank angle between about 330 degrees and about 365 degrees during a first time period. The fuel has a cetane number less than about 40. The method further includes combusting substantially all of the volume of fuel. In some embodiments, a delay between injecting the volume of fuel into the combustion chamber and initiation of combustion is less than about 2 ms.

A normal control unit performs a normal control to cause an injection apparatus to perform predetermined normal injection and subsequently cause an ignition plug to perform ignition. In a delay region in a combustion chamber, propagation of flame is retarded further than in another region when the normal control is performed. In a knock state, self-ignition occurs in the delay region when the normal control is performed. When the knock state is established, an adjustment control unit performs, to suppress the self-ignition, an adjustment control to perform main injection and subsequently perform sub-injection in a second half of a compression stroke to adjust a fuel distribution in the combustion chamber to facilitate propagation of flame to the delay region further than in the normal control and subsequently cause the ignition plug to perform the ignition.

Disclosed is a method for optimizing the time gradient of the pressure increase in a fuel injection system of a hybrid motor vehicle. The method determines and uses the engine torque generated by the electric machine of the vehicle to reduce the engine torque generated by the internal combustion engine of the vehicle and allow the high-pressure pump of the internal combustion engine to generate, if applicable, a higher value of the time gradient of the pressure increase in the common supply chamber of its injection system.

An internal combustion engine with at least one combustion chamber, at least one fuel delivery line for the delivery of fuel to at least one combustion chamber, and at least one differential pressure control valve for controlling the pressure in the at least one fuel delivery line. The at least one differential pressure control valve is configured to perform a valve opening or valve closing movement based on a pressure difference between the at least one fuel delivery line and a reference volume having a reference pressure. The internal combustion engine further includes at least one pressure relief valve, separate from the at least one differential pressure control valve, and configured to open to cause a pressure relief in the reference volume and a decrease in the reference pressure if a drop occurs in the power to be performed by the internal combustion engine.

The subject matter of this specification can be embodied in, among other things, a method performed in connection with an internal combustion engine, and the method including receiving a pressure signal from a combustion chamber pressure sensor during a first range of volumes, the first range corresponding to a portion of a compression phase, the received pressure being a first pressure, providing, based on the received pressure signal, a first pulse of fuel at a first position of the body during the compression phase, and providing, based on the received pressure signal a second pulse of fuel at a second position of the body during the compression phase.