Abstract: An engine assembly includes an engine structure, a camshaft supported on the engine structure, a first cam phaser coupled to a first axial end of the camshaft, and a locating pin. The camshaft includes a first shaft, a second shaft, a first cam lobe and a second cam lobe. The first shaft defines a first opening. The second shaft is supported within the first shaft and defines a second opening. The first cam lobe is located on and fixed for rotation with the first shaft. The second cam lobe may be located on the first shaft and fixed for rotation with the second shaft. During assembly, the first cam phaser is located on the camshaft and the locating pin may be inserted through the first and second openings to rotationally fix the first and second shafts. The first cam phaser is then secured to the camshaft.

Abstract: An engine assembly may include an engine structure, a camshaft supported for rotation on the engine structure, a drive member and a camshaft actuation assembly. The camshaft may include a first shaft, a second shaft located within the first shaft and rotatable relative to the first shaft, a first cam lobe located on the first shaft and fixed for rotation with the first shaft and a second cam lobe supported for rotation on the first shaft and fixed for rotation with the second shaft. The drive member may be fixed to a first axial end of the camshaft and rotationally driven to drive rotation of the camshaft. The camshaft actuation assembly may include an actuator coupled to a second axial end of the camshaft and rotationally fixed to the engine structure and relative to the camshaft.

Abstract: An engine assembly may include a camshaft rotationally supported on an engine structure. The camshaft may include a first shaft, a second shaft located in and rotatable relative to the first shaft and a partial cam lobe located on the first shaft. The partial cam lobe may include a peak region and may define a partial bore. A radial distance defined by the partial bore between first and second circumferential ends of the partial bore may be greater than or equal to a radial width of the first shaft. The partial cam lobe may define a recess extending in a radial direction through the partial bore and into the partial cam lobe. The camshaft may include a sleeve located within a radial passage defined by the second shaft and the recess in the partial cam lobe and radially locating the partial cam lobe relative to the second shaft.

Abstract: An engine assembly may include an engine structure, a camshaft supported for rotation on the engine structure, a drive member and a camshaft actuation assembly. The camshaft may include a first shaft, a second shaft located within the first shaft and rotatable relative to the first shaft, a first cam lobe located on the first shaft and fixed for rotation with the first shaft and a second cam lobe supported for rotation on the first shaft and fixed for rotation with the second shaft. The drive member may be fixed to a first axial end of the camshaft and rotationally driven to drive rotation of the camshaft. The camshaft actuation assembly may include an actuator coupled to a second axial end of the camshaft and rotationally fixed to the engine structure and relative to the camshaft.

Abstract: An engine assembly includes an engine structure, a camshaft supported on the engine structure, a first cam phaser coupled to a first axial end of the camshaft, and a locating pin. The camshaft includes a first shaft, a second shaft, a first cam lobe and a second cam lobe. The first shaft defines a first opening. The second shaft is supported within the first shaft and defines a second opening. The first cam lobe is located on and fixed for rotation with the first shaft. The second cam lobe may be located on the first shaft and fixed for rotation with the second shaft. During assembly, the first cam phaser is located on the camshaft and the locating pin may be inserted through the first and second openings to rotationally fix the first and second shafts. The first cam phaser is then secured to the camshaft.

Abstract: An engine assembly may include a camshaft rotationally supported on an engine structure. The camshaft may include a first shaft, a second shaft located in and rotatable relative to the first shaft and a partial cam lobe located on the first shaft. The partial cam lobe may include a peak region and may define a partial bore. A radial distance defined by the partial bore between first and second circumferential ends of the partial bore may be greater than or equal to a radial width of the first shaft. The partial cam lobe may define a recess extending in a radial direction through the partial bore and into the partial cam lobe. The camshaft may include a sleeve located within a radial passage defined by the second shaft and the recess in the partial cam lobe and radially locating the partial cam lobe relative to the second shaft.

Abstract: A camshaft assembly may include a first shaft adapted to be rotationally driven, a first lobe member fixed for rotation with the first shaft, and a torsional damper fixed to the first shaft. The torsional damper may include a mass structure fixed to the first shaft and an elastic member disposed between and coupling the mass structure and the first shaft. The elastic member may have a spring constant providing a first sideband natural frequency and a second sideband natural frequency for the camshaft assembly.

Abstract: A diagnostic system and method for operating the same includes a pressure monitoring module generating a diagnostic pressure signal and a camshaft driven engine component correction module generating an engine component oil pressure correction signal and generating a corrected diagnostic pressure signal based on the diagnostic pressure signal and the engine component oil pressure signal. The system further includes a diagnostic module generating a failed variable valve lift mechanism signal based on the corrected diagnostic pressure signal.

Abstract: An engine assembly may include an engine structure, a rocker arm assembly supported by the engine structure, and a camshaft. The rocker arm assembly may include a lever body, a support member coupled to the lever body, and a first roller member supported for rotation on the support member. The first roller member may include an annular body having first and second axial ends and an inner bore. The inner bore may receive the support member and include a groove extending from the first axial end to the second axial end. The groove may include a first portion at the first axial end rotationally offset relative to a second portion at the second axial end of the annular body. The first roller member may be rotated by rotation of the camshaft and the groove may be adapted to pump oil along the bore when the first roller member is rotated.

Abstract: An engine assembly may include a first exhaust valve lift assembly, a first exhaust valve, and a first camshaft. The first exhaust valve lift assembly may be operable in first and second operating modes. The first exhaust valve may be engaged with the first exhaust valve lift assembly and may be in communication with an engine combustion chamber. The first camshaft may include a first exhaust lobe engaged with the first exhaust valve lift assembly and defining a profile including a first exhaust region and a first exhaust gas recirculation (EGR) region. The first exhaust valve may remain closed when the first EGR region engages the first exhaust valve lift assembly during the first operating mode and may be opened when the first EGR region engages the first exhaust valve lift assembly during the second operating mode to provide exhaust gas flow into the combustion chamber during an intake stroke.

Abstract: A camshaft assembly may include a first shaft adapted to be rotationally driven, a first lobe member fixed for rotation with the first shaft, and a torsional damper fixed to the first shaft. The torsional damper may include a mass structure fixed to the first shaft and an elastic member disposed between and coupling the mass structure and the first shaft. The elastic member may have a spring constant providing a first sideband natural frequency and a second sideband natural frequency for the camshaft assembly.

Abstract: A diagnostic system and method for operating the same includes a pressure monitoring module generating a diagnostic pressure signal and a camshaft driven engine component correction module generating an engine component oil pressure correction signal and generating a corrected diagnostic pressure signal based on the diagnostic pressure signal and the engine component oil pressure signal. The system further includes a diagnostic module generating a failed variable valve lift mechanism signal based on the corrected diagnostic pressure signal.

Abstract: A rocker arm assembly includes a lever body having a first end defining a pivot point, a second end for engagement with a valve train and a central opening extending therethrough. An eccentric bearing is received in the central opening, the eccentric bearing having an eccentric opening therein. The eccentric opening having at least one thrust absorbing key extending radially inward from a surface of the eccentric opening. An eccentric pivot shaft is supported by the eccentric bearing, the eccentric pivot shaft including at least one radially inwardly extending slot located and sized to receive the at least one thrust absorbing key in an assembled position. A first cam follower is disposed on the eccentric bearing and second and third cam followers are each disposed on opposite ends of the eccentric pivot shaft.

Abstract: A control system and method for a hydraulic system (HS) that controls a fluid supply in an engine includes a timer module determines the response time of the HS to perform at least one of: increasing the pressure of the fluid supply above a predetermined threshold following the state change command and decreasing said pressure of said fluid supply below said predetermined threshold following said state change command. An update module updates the desired time of the HS based on the response time of the HS.

Abstract: An engine assembly may include an engine structure, a rocker arm assembly supported by the engine structure, and a camshaft. The rocker arm assembly may include a lever body, a support member coupled to the lever body, and a first roller member supported for rotation on the support member. The first roller member may include an annular body having first and second axial ends and an inner bore. The inner bore may receive the support member and include a groove extending from the first axial end to the second axial end. The groove may include a first portion at the first axial end rotationally offset relative to a second portion at the second axial end of the annular body. The first roller member may be rotated by rotation of the camshaft and the groove may be adapted to pump oil along the bore when the first roller member is rotated.

Abstract: A rocker arm assembly includes a lever body having a first end defining a pivot point, a second end for engagement with a valve train and a central opening extending therethrough. An eccentric bearing is received in the central opening, the eccentric bearing having an eccentric opening therein. The eccentric opening having at least one thrust absorbing key extending radially inward from a surface of the eccentric opening. An eccentric pivot shaft is supported by the eccentric bearing, the eccentric pivot shaft including at least one radially inwardly extending slot located and sized to receive the at least one thrust absorbing key in an assembled position. A first cam follower is disposed on the eccentric bearing and second and third cam followers are each disposed on opposite ends of the eccentric pivot shaft.

Abstract: A control system and method for a hydraulic system (HS) that controls a fluid supply in an engine includes a timer module determines the response time of the HS to perform at least one of: increasing the pressure of the fluid supply above a predetermined threshold following the state change command and decreasing said pressure of said fluid supply below said predetermined threshold following said state change command. An update module updates the desired time of the HS based on the response time of the HS.

Abstract: A crank driven VVT mechanism includes single or dual cranks for actuating oscillating cam drive mechanisms. The crank drive positively actuates the mechanisms in both valve opening and valve closing directions and thus avoids the need to provide return springs as are generally required in cam driven mechanisms to bias the mechanisms toward a valve closed position. However, the crank driven mechanisms of the invention require the oscillating cams to pivot onto the base circle portion during a dwell period in order to provide periods of valve closed engine operation even when the valves are set for maximum opening stroke. Thus, increased motion of the actuating mechanism or a smaller angular extent of the valve lift portions of the oscillating cams is required as compared to a cam driven mechanism.

Abstract: A desmodromic cam driven variable valve timing (VVT) mechanism includes dual rotary opening and closing cams for actuating a rocker mechanism that drives valve actuating oscillating cams. The dual rotary cam drive positively actuates the rocker mechanism in both valve opening and valve closing directions and thus avoids the need to provide return springs as required in prior cam driven mechanisms to bias the mechanisms toward a valve closed position. A variable ratio slide and slot control lever drive as well as a back force limiting worm drive for the control shaft are combined with the desmodromic cam mechanism to provide additional system advantages.

Abstract: Variable valve timing (VVT) mechanisms are disclosed which are relatively compact and are applicable for operating individual or multiple valves. In an exemplary embodiment, dual engine valves are driven by an oscillatable rocker cam that is actuated by a linkage driven by a rotary cam. The linkage is pivoted on a control member that is in turn pivotable about the axis of the rotary cam and angularly adjustable to vary the orientation of the rocker cam and thereby vary the valve lift and timing. The rotary cam is carried on a camshaft and the oscillatable rocker cam is pivoted on the rotational axis of the rotary cam. A control shaft connects with the control member through an angled slider and slot connection that provides a variable angular ratio for improved charge control at low valve lifts. A worm gear actuator may be applied to drive the control shaft.