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.

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.

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.

It is an object of the present invention to provide a control device for an internal combustion engine capable of appropriately controlling compression ratio and ignition timing before the target compression ratio that is set according to humidity is attained. A control device for an internal combustion engine controls the internal combustion engine including a cylinder, humidity detection means for detecting humidity of outside air supplied to the cylinder, a variable compression ratio mechanism for changing a compression ratio of the cylinder, and an ignition device igniting air-fuel mixture in the cylinder, and the control device includes: a compression ratio control unit controlling the variable compression ratio mechanism; and an ignition control unit controlling ignition timing of the ignition device, wherein corresponding characteristics between compression ratio and ignition timing are determined for each humidity according to a predetermined condition of an operation state of the internal combustion engine, the compression ratio control unit determines a target compression ratio of the variable compression ratio mechanism according to the detected humidity, and while the variable compression ratio mechanism changes a compression ratio to the target compression ratio, the ignition control unit controls the ignition device on the basis of corresponding characteristics determined according to the detected humidity.

A display device for an internal combustion engine includes a variable compression ratio mechanism structured to vary an engine compression ratio of the internal combustion engine. The display device includes an indicator structured to vary its indication depending on the engine compression ratio. The indicator is configured to maintain the indication constant or within a slight change with respect to a change in the engine compression ratio within each of at least one of first and second dead zones of the engine compression ratio. The first dead zone includes a vicinity of an upper limit of the engine compression ratio including the upper limit. The second dead zone includes a vicinity of a lower limit of the engine compression ratio including the lower limit.

A control device for a variable compression ratio mechanism for changing a compression ratio of an internal combustion engine by rotating a control shaft connected to an output shaft of an actuator, wherein with respect to a reference position, the control device determines the rotation angle of the control shaft by sequentially integrating the output values of an angle sensor that detects the rotation angle of the output shaft of the actuator in a range of 0? to 360? such that the rotation angle approaches a target angle. When the internal combustion engine is stopped, the control device rotates the control shaft to a high-compression-ratio side and a low-compression-ratio side, respectively, toward a stopper mechanism that defines the rotatable range and compares the determined rotation angle and a reference operation angle to diagnose whether a failure has occurred in the variable compression ratio mechanism.

Methods and systems are provided for indicating degradation of a VCR mechanism that mechanically alters a cylinder compression ratio. Degradation is detected based on an elevated knock incidence and increased spark retard usage. If the VCR mechanism is stuck, knock and pre-ignition that could be induced by continued operation in a higher than intended compression ratio is mitigated by limiting the engine load.

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.

An apparatus for diagnosing an engine including a variable compression ratio apparatus according to an exemplary embodiment of the present invention, may include a piston configured to reciprocally move in a cylinder of the engine, a detector configured to determine a position of the piston, a variable compression ratio apparatus configured to adjust a moving range of the piston, and a controller configured to determine whether the variable compression ratio apparatus is defective based on a position signal of the piston determined by the detector.

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.