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 control method for an internal combustion engine which includes a variable compression ratio mechanism: controlling the compression ratio by using a control target compression ratio whose a variation amount per unit time is limited to be equal to or smaller than a predetermined variation amount threshold value; and setting a first variation amount threshold value which is the variation amount threshold value of the control target compression ratio per unit time toward a high compression ratio side, to be smaller than a second variation amount threshold value which is the variation amount threshold value of the control target compression ratio per unit time toward a low compression ratio side.

When a stopper portion is brought into abutment against body high-compression-ratio side stopper portion, when viewed in the control shaft axial direction, it is configured that the distance between body high-compression-ratio side stopper surface and control-shaft high-compression-ratio side stopper surface becomes relatively longer as being closer to the control shaft rotation center. Similarly, when a stopper portion is brought into abutment against body low-compression-ratio side stopper portion, when viewed in the control shaft axial direction, the distance between body low-compression-ratio side stopper surface and control-shaft, low-compression-ratio side stopper surface becomes relatively longer as being closer to the control shaft rotation center.

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 rod (1), the length of which is variable, is used for adjusting the compression ratio of an engine. The rod comprises a cylinder rigidly connected to a first end of the rod; a piston that is movable within the cylinder, and is rigidly connected to the second end of the rod, and defines, in the cylinder, a first hydraulic chamber referred to as the high-pressure hydraulic chamber, capable of transmitting compression forces, and a second hydraulic chamber referred to as the low-pressure hydraulic chamber, capable of transmitting tensile forces; at least one conduit calibrated to enable fluid to flow between the low-pressure chamber and the high-pressure chamber; and return means to bring the rod back to its nominal length, wherein the cross-sections of the low-pressure hydraulic chamber and the high-pressure hydraulic chamber are equal.

A method for varying a compression ratio of an operating applied-ignition internal combustion engine having at least two cylinders and having a crank mechanism (1) comprising a crankshaft (2) which is mounted in a crankcase and which rotates at a crankshaft rotational speed .sub.crankshaft, is described. The method includes increasing an expansion phase of a cylinder cycle via rotation of the eccentric bushing (4).

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.

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.

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.

An object of the present invention is to provide a novel compression ratio adjusting apparatus for an internal combustion engine that can improve a knocking resistance performance and also prevent or cut down an increase in a temperature of exhaust gas. The compression ratio adjusting apparatus is configured to relatively decrease a mechanical compression ratio in a high load area of the internal combustion engine and also adjust a mechanical expansion ratio at this time to a relatively high ratio. According to this configuration, the compression ratio adjusting apparatus performs control of decreasing the mechanical compression ratio in the high load area of the internal combustion engine and also increasing the mechanical expansion ratio at this time, thereby succeeding in improving the knocking resistance performance and also preventing or cutting down the increase in the temperature of the exhaust gas, thus succeeding in reducing thermal damage on a part in an exhaust system.