摘要:
A variable valve actuation (VVA) apparatus is disclosed. The VVA apparatus can keep an engine cylinder valve closed. Rotating a camshaft in timed relation with a crankshaft of the engine causes an eccentric crank cam to move a link or crank arm, thereby causing one end of a rocker arm to reciprocate. This causes the other end of the rocker arm to reciprocate. The reciprocating motion of the other end of the rocker arm is transmitted via a link to a valve operating (VO) cam, thereby causing the VO cam to pivot to push a valve lifter for opening the associated cylinder valve. An eccentric circular cam, fixed to a control rod, supports the rocker arm for rotation relative thereto in such a manner that rotation of the control rod causes a pivot center of the rocker arm to move, thereby changing position of the VO cam relative to the valve lifter. The change in the position of the VO cam causes its valve lift diagram to change. The VO cam has a base circle portion that extends over a predetermined angle with respect to the center of pivot of the VO cam and the contiguous ramp portion. A predetermined valve clearance exists between the VO cam and the valve lifter when the base circle portion faces the valve lifter. When it is desired to keep the associated cylinder valve closed, the control rod is rotated to establish a state wherein the VO cam pivots to bring not only base circle but also the ramp portions into facing relation with the valve lifter. In this state, the maximum cam lift of a cam lift diagram is greater than zero and less than the valve clearance.
摘要:
A variable valve actuation (VVA) apparatus comprises an eccentric rotary (ER) cam fixed to a driving shaft for rotation therewith, a pivotal valve operating (VO) cam, a rocker arm having a first arm and a second arm, a control rod having an eccentric control cam, and a crank arm. The eccentric control cam supports the rocker arm for pivotal motion. The crank arm interconnects the ER cam and the first arm of the rocker arm. A link interconnects the second arm of the rocker arm and the VO cam.
摘要:
In a VVA apparatus, when an actual lift amount detected by a lift-amount detecting sensor exceeds a basic lift-amount target value by a predetermined value or more, ECU corrects a lift phase through a lift-phase varying mechanism to separate from a piston TDC with respect to a basic lift-phase target value.
摘要:
A variable valve actuation (VVA) apparatus for an internal combustion engine comprises a drive cam fixed to a drive shaft, a valve operating (VO) cam supported by the drive shaft for pivotal motion, and a motion transmitting mechanism interconnecting the drive cam and the VO cam. The VO cam having a cam surface that extends at least from a cam lift start point to a maximum cam lift point. The cam surface includes a first section providing a ramp section, a second section providing a positive acceleration section, and a third section providing a zero acceleration section that includes a situation where acceleration continuously vary within a predetermined infinitesimal window about zero.
摘要:
A variable valve actuation (VVA) apparatus comprises a supporting arm to support a pivot center of a rocker arm. The rocker arm operates a valve operating (VO) cam in response to operation of a drive cam on an engine driven drive shaft. The supporting arm is mounted for angular motion about an axis of rotation of the drive shaft to move the pivot center of the rocker arm along a circle about the drive shaft axis. The VO cam is mounted for pivot motion about the drive shaft axis. A supporting arm (SA) actuator is provided to position the pivot center of the rocker arm to any angular position to shift mode of operation of the VVA apparatus.
摘要:
An internal combustion engine is provided with a valve lift varying mechanism for intake valves and a valve phase varying mechanism for exhaust valves. A controller performs a control operation in response to a request to pause at least one cylinder while the engine is in operation. The control operation includes: a first operation of setting an intake valve lift to a zero-lift setpoint by the valve lift varying mechanism; and a second operation of setting an exhaust valve phase by the valve phase varying mechanism so as to set an exhaust valve opening timing to a first timing setpoint on an advance side of bottom dead center and set an exhaust valve closing timing to a second timing setpoint on a retard side of bottom dead center. The first and second timing setpoints are closer to top dead center than to bottom dead center.
摘要:
A variable valve actuation apparatus of an internal combustion engine has a multinodular-link motion converter, to vary at least a working angle. A position of rotation of a control shaft, variably adjusting the attitude of the motion converter, is set, so that, at a peak lift during a valve opening period, an angle γ2 between an extension line of a line segment connecting a first fulcrum corresponding to a drive-eccentric-cam center and a second fulcrum provided on a rocker arm and a line segment connecting the second fulcrum and a third fulcrum provided on the rocker arm at a position different from the second fulcrum at a middle working-angle control mode is less than both an angle γ1 between the two line segments at a minimum working-angle control mode and an angle γ3 between the two line segments at a maximum working-angle control mode.
摘要:
A valve operating mechanism of an internal combustion engine, comprises a drive cam rotatable with and eccentric to a drive shaft; a link arm having a circular opening in which the drive cam is rotatably received, so that rotation of drive cam about an axis of the drive shaft produces a swing movement of the link arm; a pair of swing cams swingably disposed on the drive shaft at both sides of the drive cam, the swing cams being connected through a movement transmission mechanism to the link arm to be swung when the link arm is subjected to the swing movement; a pair of swing arms respectively actuated by the swing cams for carrying out an open/close operation of a pair of engine valves; a pair of spring retainers respectively provided by the pair of engine valves; and a pair of valve springs respectively held by the spring retainers and biasing the engine valves in a close direction. A lubricating oil passage is formed in the drive cam. The oil passage has one end exposed to an oil feeding passage formed in the drive shaft and the other end exposed to a minute clearance defined between a cylindrical outer surface of the drive cam and a cylindrical inner surface of the circular opening of the link arm.
摘要:
In a valve operating apparatus of an engine capable of varying a valve lift characteristic, rotary motion of a drive cam is converted through a motion-conversion linkage including a rocker arm into oscillating motion of a valve actuation member for operating an engine valve. Also provided is a control shaft whose angular position is adjusted depending on an engine operating condition for changing a linkage attitude. The valve actuation member has an arcuate portion curved to bypass the drive shaft. The control shaft has a coaxial shaft portion and an eccentric control cam. The control cam is a fulcrum of oscillating motion of the rocker arm and the coaxial shaft portion of the control shaft is a fulcrum of oscillating motion of the valve actuation member. The fulcrums are laid out in close proximity to each other.
摘要:
A valve operating mechanism of an internal combustion engine, comprises a drive cam rotatable with and eccentric to a drive shaft; a link arm having a circular opening in which the drive cam is rotatably received, so that rotation of drive cam about an axis of the drive shaft produces a swing movement of the link arm; a pair of swing cams swingably disposed on the drive shaft at both sides of the drive cam, the swing cams being connected through a movement transmission mechanism to the link arm to be swung when the link arm is subjected to the swing movement; a pair of swing arms respectively actuated by the swing cams for carrying out an open/close operation of a pair of engine valves; a pair of spring retainers respectively provided by the pair of engine valves; and a pair of valve springs respectively held by the spring retainers and biasing the engine valves in a close direction. A lubricating oil passage is formed in the drive cam. The oil passage has one end exposed to an oil feeding passage formed in the drive shaft and the other end exposed to a minute clearance defined between a cylindrical outer surface of the drive cam and a cylindrical inner surface of the circular opening of the link arm.