A variable-length connecting rod comprises: a connecting rod head, designed to establish a pivot connection with a crankpin of a crankshaft, a hydraulic circuit for controlling the length of the connecting rod, and a system for controlling the hydraulic circuit. The control system comprises: at least one linear hydraulic slide arranged within a housing of the connecting rod head, at least a first shoe arranged on a sidewall of the connecting rod head, suitable for undergoing a bearing force exerted by a controlling member, the bearing force allowing the slide to be moved, a return means for bringing the slide back to its resting position in the absence of the bearing force, At and at least a second shoe arranged on the sidewall of the connecting rod head and suitable for undergoing the bearing force.

A variable-length connecting rod comprises: a connecting rod head, designed to establish a pivot connection with a crankpin of a crankshaft, a hydraulic circuit for controlling the length of the connecting rod, and a system for controlling the hydraulic circuit. The control system comprises: at least one linear hydraulic slide arranged within a housing of the connecting rod head, at least a first shoe arranged on a sidewall of the connecting rod head, suitable for undergoing a bearing force exerted by a controlling member, the bearing force allowing the slide to be moved, a return means for bringing the slide back to its resting position in the absence of the bearing force, At and at least a second shoe arranged on the sidewall of the connecting rod head and suitable for undergoing the bearing force.

An internal combustion engine (1) for a vehicle is equipped with a variable compression ratio mechanism (2) capable of changing the mechanical compression ratio. An idle stop, which is for automatically stopping the internal combustion engine (1) when the vehicle stops, and a sailing stop, which is for stopping the internal combustion engine (1) in conjunction with the release of a forward clutch (8) during inertial travel, are carried out. A target compression ratio during normal travel is set on the basis of the load and rotation speed of the internal combustion engine (1). During an idle stop the target compression ratio is set to an idle stop restart compression ratio (εis). During a sailing stop the target compression ratio is set to a sailing stop restart compression ratio (εss). The sailing stop restart compression ratio (εss) is lower than the idle stop restart compression ratio (εis).

An internal combustion engine (1) for a vehicle is equipped with a variable compression ratio mechanism (2) capable of changing the mechanical compression ratio. An idle stop, which is for automatically stopping the internal combustion engine (1) when the vehicle stops, and a sailing stop, which is for stopping the internal combustion engine (1) in conjunction with the release of a forward clutch (8) during inertial travel, are carried out. A target compression ratio during normal travel is set on the basis of the load and rotation speed of the internal combustion engine (1). During an idle stop the target compression ratio is set to an idle stop restart compression ratio (εis). During a sailing stop the target compression ratio is set to a sailing stop restart compression ratio (εss). The sailing stop restart compression ratio (εss) is lower than the idle stop restart compression ratio (εis).

Combustion engine with a variable compression ratio which, according to the invention, includes the following items: engine body, crankshaft with crank pins mounted rotatably in the body, cylinders, pistons connected to the crankshaft via pin connecting rod sand control arms as well as the control arm rod located inside the engine body, with eccentrics mounted on it, on which eccentrics for each piston there are separately mounted control arms, it is characterized by the fact that on the control arm rod (19) aside from the rigidly mounted eccentrics (18), on which single control arms (14) are rotatably mounted, there are also rotatably mounted eccentrics (23), on which single control arms (14) are rotatably mounted, where preferably on the eccentrics (18) are mounted the control arms (14) for one row of cylinders (5), while for the eccentrics (23) are mounted the control arms (14) for the other row of cylinders (5), additionally the engine contains a mechanism for changing the compression ratio consisting of the control arm rod (19) with eccentrics (18, 23) mounted on the control arm rod (19) as well as coupling elements that connect the elements of the mechanism which ensure that neighboring eccentrics (18, 23) rotate in opposite directions.

Combustion engine with a variable compression ratio which, according to the invention, includes the following items: engine body, crankshaft with crank pins mounted rotatably in the body, cylinders, pistons connected to the crankshaft via pin connecting rod sand control arms as well as the control arm rod located inside the engine body, with eccentrics mounted on it, on which eccentrics for each piston there are separately mounted control arms, it is characterized by the fact that on the control arm rod (19) aside from the rigidly mounted eccentrics (18), on which single control arms (14) are rotatably mounted, there are also rotatably mounted eccentrics (23), on which single control arms (14) are rotatably mounted, where preferably on the eccentrics (18) are mounted the control arms (14) for one row of cylinders (5), while for the eccentrics (23) are mounted the control arms (14) for the other row of cylinders (5), additionally the engine contains a mechanism for changing the compression ratio consisting of the control arm rod (19) with eccentrics (18, 23) mounted on the control arm rod (19) as well as coupling elements that connect the elements of the mechanism which ensure that neighboring eccentrics (18, 23) rotate in opposite directions.

A hydraulic control system for a variable compression ratio engine, comprises: a control cylinder comprising a piston, a body in which two hydraulic chambers with equivalent sections are defined on either side of the piston and a return device arranged in one of the chambers, a hydraulic control circuit comprising: at least one duct connecting the two chambers to each other, and a controlled fluid discharging device for establishing or blocking a fluid communication between the chambers, at least one duct connecting one of the chambers to a low-pressure oil supply, and a refill valve, at least one duct connecting an oil outlet to at least one of the chambers, and a relief valve.

A hydraulic control system for a variable compression ratio engine, comprises: a control cylinder comprising a piston, a body in which two hydraulic chambers with equivalent sections are defined on either side of the piston and a return device arranged in one of the chambers, a hydraulic control circuit comprising: at least one duct connecting the two chambers to each other, and a controlled fluid discharging device for establishing or blocking a fluid communication between the chambers, at least one duct connecting one of the chambers to a low-pressure oil supply, and a refill valve, at least one duct connecting an oil outlet to at least one of the chambers, and a relief valve.

Methods and systems are provided for controlling a vehicle engine to reduce engine knock and increase fuel efficiency by reducing hydrocarbon breakthrough. In one example, a method may include adjusting a compression ratio of a variable compression engine in response to hydrocarbon breakthrough above a threshold from a fuel vapor canister of an evaporative emissions system.

A longitudinally adjustable connecting rod with a hydraulic control device for effecting a change in the effective length of the connecting rod is provided. The hydraulic control device comprises a hydraulic control valve which comprises a hydraulically actuatable control slide that is preloaded by way of a control slide spring, and two outlet valves which can be actuated by the control slide by way of two control contours arranged at a distance from one another. The control slide comprises a low-pressure section with a low-pressure piston for hydraulically actuating the control slide. For optimizing the control slide for such a longitudinally adjustable connecting rod, the two control contours are arranged together in a high-pressure section of the control slide which is arranged on one side of the low-pressure section and separated therefrom by way of a sealing section disposed therebetween. The control contours each comprise a closure region with control cams and an opening region adjoining the control cams. The closure region has a smaller cross-section than the opening region. The mass of the section of the control slide disposed between the two closure regions corresponds at most to 0.95 times the envelope volume of this section multiplied by the density of steel (7.85 g/mm.sup.3) due to the selection of material and/or the contouring narrowing in comparison with the opening regions. A respective control slide and a reciprocating piston engine are also provided.