The variable compression ratio piston system for an engine adjusts the compression ratio of the engine piston by way of hydraulic fluid distributed between a pair of chambers formed in a pair of bores receiving control pistons mechanically coupled to the engine piston. A control valve selectively permits flow of hydraulic fluid between the high compression ratio line and the low compression ratio line. A variable force solenoid controlled by an engine control unit preferably controls the position of the control valve. The position of the spool controls whether hydraulic fluid can flow toward the first chamber, toward the second chamber, or not at all. Flow of hydraulic fluid is actuated by alternating forces from inertial and combustion forces on a crankshaft from operation of the engine.

An internal combustion engine comprises a variable compression ratio mechanism that changes the relative position of a cylinder block with respect to a crankcase and a controlling device that controls the variable compression ratio mechanism. The variable compression ratio mechanism contains a driving device that rotates a shaft that includes an eccentric axis, and the drive device includes a clutch that blocks reverse input and is disposed in a drive power transmission route that transmits the rotational power of a motor to the shaft. The control device fixes the mechanical compression ratio to a predetermined low mechanical compression ratio when the amplitude of the rotational power vibration applied to an output shaft of the clutch is less than a predetermined determination value.

A method for starting an internal combustion engine has the steps of: oscillating a crankshaft of the engine using the electrical actuator; then injecting fuel in a combustion chamber and igniting the fuel in this combustion chamber to cause the crankshaft to turn in a reverse direction; then injecting fuel in another combustion chamber and igniting the fuel in the other combustion chamber to cause the crankshaft to turn in a forward direction; and then injecting fuel in the other combustion chamber and igniting fuel in the other combustion chamber to cause the crankshaft to turn in the forward direction.

A method for starting an internal combustion engine has the steps of: oscillating a crankshaft of the engine using the electrical actuator; then injecting fuel in a combustion chamber and igniting the fuel in this combustion chamber to cause the crankshaft to turn in a reverse direction; then injecting fuel in another combustion chamber and igniting the fuel in the other combustion chamber to cause the crankshaft to turn in a forward direction; and then injecting fuel in the other combustion chamber and igniting fuel in the other combustion chamber to cause the crankshaft to turn in the forward direction.

A variable length connecting rod includes a connecting rod body, an eccentric member, a first piston mechanism, a second piston mechanism and a flow-direction switching mechanism. The eccentric member, the first piston member, the second piston member and the flow-direction switching mechanism are provided in the connecting rod body. The first piston mechanism and the second piston mechanism are configured to pivot the eccentric member. The connecting rod body has a control oil passage that communicates with a first opening of the connecting rod and the flow-direction switching mechanism. The flow-direction switching mechanism is switched between the first state and the second state by switching pins. The switching pins are disposed in the connecting rod body such that directions in which the switching pins are operated are angled with respect to a plane perpendicular to an axis of the first opening.

transmission device, particularly for an engine with variable compression rate and/or variable displacement, includes, in a cylinder housing: a combustion piston, capable of moving in a combustion cylinder of the engine and secured to a transmission member; a gear engaging with a first rack of the transmission member and providing transmission of the movement between the combustion piston and a crankshaft of the engine; a connecting rod engaging, at a first end, with the gear and, at a second end, with the crankshaft; and a control member engaging with the gear and secured to a control piston. The combustion piston and the transmission member are slidably linked with the cylinder housing in a main direction.

transmission device, particularly for an engine with variable compression rate and/or variable displacement, includes, in a cylinder housing: a combustion piston, capable of moving in a combustion cylinder of the engine and secured to a transmission member; a gear engaging with a first rack of the transmission member and providing transmission of the movement between the combustion piston and a crankshaft of the engine; a connecting rod engaging, at a first end, with the gear and, at a second end, with the crankshaft; and a control member engaging with the gear and secured to a control piston. The combustion piston and the transmission member are slidably linked with the cylinder housing in a main direction.

A control device for an internal combustion engine has a controller configured to control a fuel injection valve arranged to directly inject a fuel into a combustion chamber, and a variable compression ratio mechanism arranged to vary an upper dead center position of a piston, and thereby to vary a compression ratio of the internal combustion engine. The controller is configured to control a fuel cut by which the fuel injection from the fuel injection valve is stopped, when a predetermined fuel cut condition is satisfied during a traveling of a vehicle. The fuel injection from the fuel injection valve is restarted when a predetermined fuel cut recovery condition is satisfied during the fuel cut.

A variable length connecting rod includes: a connecting rod body; an eccentric member which can swivel with respect to the connecting rod body and in which the effective length of the variable length connecting rod is changed when swiveled; a first piston mechanism making the eccentric member swivel in one direction when hydraulic fluid is fed; a second piston mechanism making the eccentric member swivel in the opposite direction when hydraulic fluid is fed; and a flow direction changing mechanism switching flow directions of hydraulic fluid between the first and second piston mechanisms. The first piston mechanism and second piston mechanism are formed so that a first cylinder volume defined by a stroke length of the first piston and a cross-sectional area of the first cylinder is equal to a second cylinder volume defined by a stroke length of the second piston and a cross-sectional area of the second cylinder.

A variable length connecting rod includes a connecting rod body, an eccentric member, a switching mechanism and a stopping mechanism. The eccentric member is provided at a small diameter end of the connecting rod body. The eccentric member rotates such that an effective length of the variable length connecting rod is varied. The switching mechanism includes a hydraulic piston connected to the eccentric member. The eccentric member reaches a first position when the switching mechanism is in a first state. The eccentric member reaches a second position when the switching mechanism is in a second state. The stopping mechanism includes a stopping member that abuts against or engages with the eccentric member or the hydraulic piston such that the eccentric member is maintained at an intermediate position between the first position and the second position.