Methods and systems are provided for maintaining a compression ratio of an engine via a brake and while disabling an electric current applied to an actuator of the associated variable compression ratio mechanism. A braking force applied via the brake on a compression ratio control shaft is varied before and during a compression ratio transition to move the control shaft at a desired velocity. Brake torque application is coordinated with motor torque from a VCR actuator and engine torque applied on the control shaft to enable a smooth CR transition.

Systems and methods for operating an engine that includes a compression ratio linkage for adjusting engine compression ratio are described. The systems and methods provide different ways of changing a compression ratio of an engine based on forecast or anticipated engine operating conditions. In one example, the forecast or anticipated engine operating conditions may include a forecast or anticipated transmission gear shift.

Systems and methods for operating an engine that includes a compression ratio linkage for adjusting engine compression ratio are described. The systems and methods provide different ways of diagnosing the presence or absence of engine misfire in response to engine operating regions that may be more or less prone to torsional engine crankshaft vibration. In one example, engine misfire may be determined responsive to force applied to an engine compression ratio changing linkage.

The present invention relates to a control device and to a control method for a vehicle drive mechanism including a moving body having a movability range regulated by two stoppers, and a sensor which senses a position of the moving body. The control device of the present invention learns an output of the sensor corresponding to a contact state of a high-rigidity stopper, and limits, to a lower level, an operation variable of the actuator for moving the moving body toward a low-rigidity stopper along with an increase in an amount of change in the output of the sensor from the contact state of the high-rigidity stopper. Then, the control device learns the output of the sensor corresponding to the contact state of the low-rigidity stopper, and controls the actuator based on the output of the sensor learned at both the stopper positions.

A failure diagnosis apparatus according to the present disclosure is applied to a variable compression ratio mechanism that can switch the compression ratio of an internal combustion engine between at least a first compression ratio and a second compression ratio lower than the first compression ratio. When the variable compression ratio mechanism is controlled so as to set the compression ratio of the internal combustion engine to the second compression ratio, the failure diagnosis apparatus advances the ignition timing of one cylinder to a knock inducing ignition timing more advanced than the MBT that does not lead to the occurrence of knock if the actual compression ratio of that cylinder is the second compression ratio but leads to the occurrence of knock if the actual compression ratio of that cylinder is the first compression ratio and diagnoses failure of the variable compression ratio mechanism on the basis of whether knock occurs or not.

A variable compression ratio engine includes a piston reciprocally moving in a cylinder of an engine; a variable compression ratio apparatus controlling a movable range of the piston; and a controller controlling the variable compression ratio apparatus if a driving condition of a vehicle and a stability condition of the engine are satisfied to change a compression ratio and controlling a motor torque and an engine torque to control a requirement torque to be satisfied.

A control method for an internal combustion engine is arranged to vary an engine compression ratio, and includes a control mechanism arranged to control the engine compression ratio, and a driving source arranged to drive the control mechanism. The control method includes converting an operation amount of the driving source in accordance with an attenuation rate according to the engine compression ratio, transmitting the converted operation amount to the control mechanism, and controlling the cylinder pressure based on a basic ignition timing when the attenuation rate is relatively large, and controlling the cylinder pressure based on an allowable ignition timing retarded from the basic ignition timing when the attenuation rate is relatively small.

The invention relates to a method for operating a reciprocating piston machine, particularly an internal combustion engine, having at least one piston rod that is hydraulically adjustable in length for setting a compression ratio, wherein the piston rod comprises a piston and a hydraulic cylinder for adjusting its length, wherein the piston with the hydraulic cylinder delimits at least one working chamber, through the fill level of which at least two switching positions of the piston rod are possible, wherein independently from the setting of the compression ratio the working chamber is at least partially filled and emptied as a function of at least one first predetermined requirement to effect an at least partial exchange of a hydraulic medium in the at least one working chamber.

Systems and methods for operating an engine that includes a compression ratio linkage for adjusting engine compression ratio are described. The systems and methods provide different ways of changing a compression ratio of an engine based on forecast or anticipated engine operating conditions. In one example, the forecast or anticipated engine operating conditions may include a forecast or anticipated transmission gear shift.

An internal combustion engine includes a turbocharger, a variable valve timing mechanism, a variable compression ratio mechanism, and an electronic control unit that controls the variable compression ratio mechanism such that the mechanical compression ratio becomes a target mechanical compression ratio and controls the variable valve timing mechanism such that the valve closing timing of the intake valve becomes a target valve closing timing. The electronic control unit brings the target valve closing timing close to an intake bottom dead center and make the target mechanical compression ratio low, compared to a steady state after the intake pressure reaches a target pressure, in a transient state before the intake pressure reaches the target pressure in a case where the intake pressure is increased to the target pressure higher than an atmospheric pressure by the turbocharger.