A cam follower for operable attachment to a valve lifter assembly for use with a variable cam lobe camshaft in a variable valve timing system includes a housing with a central cavity and a mushroom head with a stem pivotably connected to the housing in the central cavity, the mushroom head having a radiused surface for contacting a cam lobe surface. The cam follower is used in combination with a variable cam surface of an axially displaceable camshaft to obtain improvements in idling speed and volumetric efficiency.

An adjustable camshaft of an internal combustion engine may include an outer shaft and an inner shaft arranged coaxially to the outer shaft and rotatable over a predefined angle. At least one first cam may be connected rotationally fixedly to the inner shaft. A second cam may be arranged beside the first cam and may be connected rotationally fixedly to the outer shaft. The first cam and the second cam may each be operatively associated with a common valve. Rotation of the first cam relative to the second cam may impart an extension of a valve opening time of the valve. The first cam and the second cam may each include an identical circular segment section in an elevated region of valve lift. The circular segment section of the first cam and the second cam may merge without interruptions during rotation about the predefined angle range.

A variable valve duration apparatus may include a first cam rotating with a camshaft; a second cam rotating with the camshaft; a first operation device that is operated by the first cam to generate a valve lift; a second operation device that is operated by the second cam to generate the valve lift; and a controller controlling the first operation device or the second operation device to generate the valve lift according to an operation state of an engine.

A continuously variable valve timing apparatus may include a camshaft, a first and a second cam portions of which two cams are formed thereto, of which the camshaft is inserted thereinto and of which relative phase angles with respect to the camshaft are variable, a first and a second inner brackets transmitting rotation of the camshaft to the first and second cam portions respectively, a first and a second slider housings of which the first and second inner brackets are rotatably inserted thereinto respectively and of which relative positions with respect to the camshaft are variable, a control shaft connected with the slider housings and a control portion connected with the control shaft and selectively changing the positions of the inner brackets.

Methods and systems are provided for a valve lift control device. In one example, a method may include rotating an adjusting camshaft of the valve lift control device in order to adjust a valve lift of one or more cylinders.

A continuous variable valve duration apparatus may include camshaft, first and second cam portions of cam is formed thereto respectively, of which the camshaft is inserted thereto and of which relative phase angles with respect to the camshaft are variable, first and second inner brackets transmitting rotation of the camshaft to the first and second cam portions respectively, first and second slider housings of which the first and second inner brackets are rotatably inserted thereto and of which relative position with respect to the camshaft are variable, cam cap rotatably supporting the first and second cam portions respectively and of which each slider housing is slidably mounted thereto, control shaft disposed parallel to the camshaft and engaged with the first and second slider housings for selectively moving the first and second slider housings and a control portion selectively rotating the control shaft for changing positions of the inner brackets.

A continuous variable valve duration apparatus may include camshaft, first and second cam portions of cam is formed thereto respectively, of which the camshaft is inserted thereto and of which relative phase angles with respect to the camshaft are variable, first and second inner brackets transmitting rotation of the camshaft to the first and second cam portions respectively, first and second slider housings of which the first and second inner brackets are rotatably inserted thereto and of which relative position with respect to the camshaft are variable, cam cap rotatably supporting the first and second cam portions respectively and of which each slider housing is slidably mounted thereto, control shaft disposed parallel to the camshaft and engaged with the first and second slider housings for selectively moving the first and second slider housings and a control portion selectively rotating the control shaft for changing positions of the inner brackets.

A variable valve lift apparatus may include: an outer body selectively making a lever motion according to rotation of a cam, a first inner body disposed in the any one inside space of the outer body and adapted, a second inner body disposed in the other one inside space of the outer body, a connecting shaft disposed to penetrate the one end of the outer body, the one end of the first inner body, and the one end of the second inner body and connect the outer body with the first and second inner bodies, a first lost motion spring to return the first inner body relatively rotated with the outer body around the connecting shaft, and a second lost motion spring to return the second inner body relatively rotated with the outer body around the connecting shaft.

A variable valve actuating mechanism comprising a camshaft having two concentric cam lobes that may be rotated relative to one another a summation lever engaging with both cam lobes, a valve actuating rocker pivotally connected to the summation lever and engaging with a hydraulic lash adjuster at a first end and with a valve at a second end, and a shim surface movable with the pivot axis connecting the summation lever to the valve actuating rocker for limiting the expansion of the hydraulic lash adjuster to control clearance in the rocker system, wherein, in order to reduce friction, the shim surface abuts with a stationary stop surface that forms part of a camshaft support bearing.

A continuously variable valve timing apparatus may include a camshaft, a first and a second cam portions of which two cams are formed thereto, of which the camshaft is inserted thereinto and of which relative phase angles with respect to the camshaft are variable, a first and a second inner brackets transmitting rotation of the camshaft to the first and second cam portions respectively, a first and a second slider housings of which the first and second inner brackets are rotatably inserted thereinto respectively and of which relative positions with respect to the camshaft are variable, a control shaft connected with the slider housings and a control portion connected with the control shaft and selectively changing the positions of the inner brackets.