A method for operating an internal combustion engine for a motor vehicle including receiving measurement signals of a cylinder pressure sensor and determining cylinder pressure fluctuations as a function of the received measurement signals of the cylinder pressure sensor. The method also includes increasing an exhaust gas recirculation rate of the internal combustion engine as a function of the determined cylinder pressure fluctuations until a predefined limiting value of the cylinder pressure fluctuations is reached. In addition, the method includes determining an actual value of the exhaust gas recirculation rate if the predefined limiting value of the cylinder pressure fluctuations is reached, and storing the determined actual value as a setpoint value for the exhaust gas recirculation rate of the internal combustion engine.

In an internal combustion engine, fluctuations in combustion torque are suppressed to reduce vibration and prevent deterioration of ride comfort of a driver. Therefore, a control device of an internal combustion engine 100 having a plurality of cylinders 150 (a first cylinder 151, a second cylinder 152, a third cylinder 153, and a fourth cylinder 154) includes a combustion state detection unit for detecting whether the plurality of cylinders 150 are in a normal combustion state or a flame-out state, and a control device 1 which controls driving of a fuel pump 131 that is a load of a combustion torque generated by the cylinder 150. The control device 1 suppresses the driving of the fuel pump 131 at a predetermined combustion timing of the cylinders 151 to 154 of the flame-out state in a case where it is determined that any one of the cylinders 151 to 154 among the plurality of cylinders 150 is in the flame-out state.

Operating a dual fuel engine system includes igniting a main charge of gaseous fuel in response to combustion of an early pilot shot of liquid fuel and production of a spark. Operating the system also includes covarying a spark timing parameter and a pilot shot delivery parameter, and reducing an error in a phasing of combustion of another main charge based on the covarying of the spark timing parameter and the pilot shot delivery parameter.

A lubricity estimation device is applied to a fuel supply system that supplies a fuel to an internal combustion engine, and includes a mixing ratio estimation unit and a lubrication index calculation unit. The mixing ratio estimation unit estimates the mixing ratio of each of plural types of molecular structures included in the fuel. The lubrication index calculation unit calculates a lubrication index, representing the lubricity of an outer peripheral portion S1 of the piston of a fuel pump and an outer peripheral portion of the valve body of a fuel injection valve by the fuel, based on the mixing ratio estimated by the mixing ratio estimation unit.

A method of implementing control logic of a compression-ignition engine is provided. A control part of the engine performs a calculation according to the control logic corresponding to an engine operating state in response to a measurement of a measurement part, controls a fuel injection part, a variable valve operating mechanism, an ignition part and a supercharger so that a G/F becomes leaner than a stoichiometric air fuel ratio and a A/F becomes equal to or richer than the stoichiometric air fuel ratio, while causing the supercharger to boost, and controls the ignition part so that unburnt mixture gas combusts by self-ignition after the ignition. The method includes determining a supercharging pressure P, and determining control logic defining a close timing IVC of an intake valve. When determining the control logic, the close timing IVC (deg.aBDC) is determined so that the supercharging pressure P (kPa) satisfies the following expression: P8.010.sup.11IVC.sup.61.010.sup.8IVC.sup.5+3.010.sup.7IVC.sup.44.010.sup.6IVC.sup.3+0.0068IVC.sup.20.3209IVC+116.63.

A combustion control system for a dual fuel engine includes a combustion control unit structured to receive phasing data for combustion of a main charge of gaseous fuel ignited by way of pilot shots of a liquid fuel, output a pilot fueling command based on the phasing data, and output a valve timing command. The combustion control unit is further structured to vary a phasing of combustion of a main charge of a gaseous fuel ignited by pilot shots of a liquid fuel based on an adjustment to at least one of a pilot shot delivery parameter or a valve timing parameter such as intake valve closing timing from a first engine cycle to a second engine cycle. Control of the intake valve timing can be based on a main pilot shot timing error.

A controller includes a valve control unit and a target calculation unit. The valve control unit is configured to control a fuel injection valve such that divergence decreases between an ignition delay of fuel injected into a cylinder through main injection and an ignition delay target value. The target calculation unit is configured to calculate the ignition delay target value such that the ignition delay target value decreases as estimated ignitability of the fuel in the cylinder increases during an engine operation in a region where diffusion combustion and premix combustion are both performed, the ignitability of the fuel in the cylinder being estimated based on a parameter that varies the ignitability.

Variable compression ratio engines and methods for homogeneous charge, compression ignition operation. The engines effectively premix the fuel and air well before compression ignition. Various embodiments are disclosed including embodiments that include two stages of compression to obtain compression ratios well above the mechanical compression ratio of the engine cylinders for compression ignition of difficult to ignite fuels, and a controllable combustion chamber volume for limiting the maximum temperature during combustion. Energy storage with energy management are also disclosed.

A method of estimating the MFB50 combustion index of the cylinders of an internal combustion engine provided with a drive shaft coupled to at least a pair of position sensors, each of which is arranged at a respective end of the drive shaft; the estimation method comprising the steps of: acquiring the signals coming from two position sensors; determining the angular torsion of the drive shaft based on the signals from the two position sensors; and estimating the MFB50 combustion index of the single cylinders of the internal combustion engine based on the angular torsion of the drive shaft.

A combustion control part of a control device for an internal combustion engine configured to calculate a first vibration level of an engine body at a first judgment frequency band of a second overtone of a specific frequency band based on vibration acceleration detected by a vibration sensor and, when the first vibration level is less than a predetermined first reference vibration level set in advance according to the engine operating state, to correct one or both of a target injection amount and target injection timing so that the first vibration level becomes the first reference vibration level or more.