A pressure compensated solenoid valve with fluid flow force balancing is provided. The solenoid valve includes an armature and a valve plunger arranged to transport hydraulic fluid from a supply end of a valve plunger to an upper end of the armature facilitating a resultant upper fluid force that acts upon the upper end of the armature to balance a resultant lower fluid force that acts on the supply end of the valve plunger. The solenoid valve includes a poppet that is configured as a pressure-relief valve for maintaining a minimum fluid pressure within an actuation fluid gallery. An inlet fluid force of the poppet is balanced by an outlet fluid force of the poppet.

A hydraulically-actuated variable camshaft timing (VCT) system comprises a spool valve including a sleeve and a spool, having a plurality of radially-outwardly extending lands, received within a sleeve; a sleeve fluid pathway, extending axially along the sleeve and formed within the sleeve, configured to receive fluid from a fluid supply; an advancing port in the sleeve in fluid communication with an advancing chamber of a hydraulically-actuated camshaft phaser; a retarding port in the sleeve in fluid communication with a retarding chamber of the hydraulically-actuated camshaft phaser; a first fluid supply port formed in the sleeve; a second fluid supply port formed in the sleeve; and an exhaust port axially positioned in the sleeve in between the first fluid supply port and the second fluid supply port or in between the advancing port and the retarding port, wherein the exhaust port is configured to selectively receive fluid from either the advancing chamber or the retarding chamber depending on an axial position of the spool relative to the sleeve.

A variable camshaft timing (VCT) assembly for controlling the angular position of concentric camshafts includes an independent VCT device that is configured to couple with a first concentric camshaft and change an angular position of the first concentric camshaft relative to an angular position of a crankshaft; and one or more dependent VCT devices mechanically linking an output of the independent VCT device with a second concentric camshaft, wherein the dependent VCT device(s) change(s) an angular position of the second concentric camshaft relative to the angular position of the first concentric camshaft based on angular movement of the output of the independent VCT device.

An actuation apparatus for actuating a component of a switchable valve train device of an internal combustion engine includes: a support body for mounting on a cylinder head cover of the internal combustion engine; an actuation lever mounted to the support body for pivotal movement of the actuation lever between a first position for actuation of the component and a second position for allowing de-actuation of the component; and a biasing means for urging the actuation lever from the second position towards the first position. In use, the biasing means becomes biased when an actuation source causes the actuation lever to pivot to the second position. When the actuation source attempts to actuate the component when the component is non-actuatable, the biasing means causes the actuation lever to pivot from the second position to the first position, thereby to actuate the component when the component becomes actuatable again.

In order to ensure a simple, reliable and recuperative operation in a hydraulic drive (10) for accelerating and braking a gas exchange valve (20) of internal combustion engines or other reciprocating engines, it is proposed that a first pressure reservoir (41) for providing a first pressure p.sub.1 comprises a restoring energy accumulator, preferably configured as a spring (25), and at least one hydraulic base pressure reservoir (40), which has a lower pressure p.sub.0 than the first pressure reservoir (41). In a connecting line (48) between the first hydraulic pressure reservoir (41) and the working cylinder (22), a controllable opening (49) of a first valve (46) comprising at least one check valve (47) is arranged upstream or downstream in the flow path, which allows the pressure medium (30) to flow in the direction of working cylinder (22), but prevents a backflow towards the pressure reservoir (41). In order to also initiate the closing movement or to enable the breaking of the gas exchange valve in a hydraulically simple and reliable manner, in a second connecting line (58) between the first pressure reservoir (41) and the working cylinder (22) there is arranged a controllable opening (59) of a second valve (56) comprising a check valve (57), which prevents a flow in the direction of the working cylinder (22), but allows a return flow in the direction of the pressure reservoir (41).

Presented are variable compression ratio and independent compression and expansion engines, methods for making/operating such engines, and vehicles equipped with such engines. An engine assembly includes an engine block with a cylinder bore defining a combustion chamber, and a piston movable within the cylinder bore. A valve assembly, which is fluidly coupled to the combustion chamber, selectively introduces/evacuates fluid from the combustion chamber. A crankshaft is supported by the engine block and rotatable on a first axis. A multipoint linkage, which drivingly engages the piston to the crankshaft, rotates on a second axis offset from the first axis. A control shaft is supported by the engine block and rotates on a third axis offset from the first and second axes. The control shaft operable to selectively rotate the multipoint linkage on the second axis, and is operable to selectively unseat the valve assembly.

A variable camshaft timing system including a first camshaft phaser having an input that is configured to receive rotational force from a crankshaft and an output that is configured to link with a first camshaft of a concentric camshaft assembly to change the angular position of the first camshaft relative to a crankshaft; and a second camshaft phaser having an output that is configured to link with a second camshaft of the concentric camshaft assembly to change the angular position of the second camshaft relative to the crankshaft, wherein the first camshaft is concentrically positioned to the first camshaft and the first camshaft phaser is mechanically linked to the second camshaft phaser to communicate rotational force from the crankshaft to the second camshaft phaser through the first camshaft phaser and the mechanical link.

A hydraulic type scissors gear removes factors that generate a backlash due to reduction of tension of existing springs by generating a relative motion between gears using oil pressure. The hydraulic type scissors gear includes: a first gear having an operation chamber and supplied with oil in the operation chamber; a second gear coaxially disposed on a side of the first gear to be rotate relative to the first gear; and a piston configured to rotate the second gear by applying force that pushes the second gear in a rotational direction opposite to a rotational direction of the first gear by being moved in the operation chamber by oil pressure supplied to the operation chamber.

A rocker arm assembly having a rocker arm with a first end defining a first cavity, a second end opposite the first end, a bore positioned between the first end and the second end for pivotally mounting the rocker arm within an engine, and an oil passage extending from the bore to the cavity. A hydraulic lash adjuster is positioned within the cavity and has an oil inlet in fluid communication with the oil passage. The rocker arm has a vent passage configured to place the oil inlet in fluid communication with an area exterior to the rocker arm.

An engine oil passage structure for an engine contributing to downsizing the engine and achieving protection of an oil passage against external forces is provided. Provided is an oil passage structure for an engine installed in a small vehicle, the engine including an engine body formed of a crankcase and a cylinder block and a cylinder head stacked inclined vehicle frontward on the crankcase, the crankcase, the cylinder block, and the cylinder head being integrally fastened. The oil passage structure includes, near a bent part formed by a case front wall of the crankcase and a cylinder front wall of the cylinder block forming a valley part by an obtuse angle, a right-left direction oil passage extending in a right-left direction along the valley part.