Variable valve actuation apparatus of internal combustion engine

A variable valve actuation apparatus of an internal combustion engine comprising:

• a drive shaft having a drive support shaft and a drive eccentric cam whose geometric center is displaced from a shaft axis of the drive support shaft, and adapted to rotate about the shaft axis of the drive support shaft in synchronism with rotation of an engine crankshaft;
• a control shaft having a control support shaft and a control eccentric cam whose geometric center is displaced from a shaft axis of the control support shaft, and adapted to rotate about the shaft axis of the control support shaft;
• a rockable cam pivotably supported by a pivot, and having a cam nose portion and a connecting portion such that the cam nose portion and the connecting portion are arranged on opposite sides of the pivot, and adapted to actuate an engine valve by a cam contour surface portion defined between the cam nose portion and the connecting portion;
• a rocker arm configured to pivot about a fifth fulcrum Q corresponding to the geometric center of the control eccentric cam;
• a link arm linked at a first end to the drive eccentric cam in such a manner as to pivot about a first fulcrum X corresponding to the geometric center of the drive eccentric cam, and further linked at a second end to the rocker arm in such a manner as to pivot about a second fulcrum R provided on the rocker arm;
• a link rod linked at a first end to the rocker arm in such a manner as to pivot about a third fulcrum S provided on the rocker arm at a position different from the second fulcrum R, and further linked at a second end to the connecting portion of the rockable cam in such a manner as to pivot about a fourth fulcrum T provided on the connecting portion of the rockable cam;
• and
• an actuator adapted to drive the control shaft,
• wherein at least a working angle of the engine valve varies by rotating the control shaft;
• and
• wherein a position of rotation of the control shaft is set, so that, at a peak lift during a valve opening period of the engine valve, an angle β2 between a line segment X-R between and including the first and second fulcrums X and R and a line segment R-Q between and including the second and fifth fulcrums R and Q midway between minimum and maximum working-angle control modes is less than both an angle β1 between the line segment X-R and the line segment R-Q at the minimum working-angle control mode and an angle β3 between the line segment X-R and the line segment R-Q at the maximum working-angle control mode.

A variable valve actuation apparatus of an internal combustion engine comprising:

• a drive shaft having a drive eccentric cam, and adapted to be driven by a torque transmitted from an engine crankshaft to the drive shaft;
• a control shaft having a control eccentric cam and configured to rotate about its rotation axis;
• a rockable cam pivotably supported by a pivot, and having a cam nose portion and a connecting portion such that the cam nose portion and the connecting portion are arranged on opposite sides of the pivot, and adapted to actuate an engine valve by a cam contour surface portion defined between the cam nose portion and the connecting portion;
• a rocker arm pivotably supported by an outer periphery of the control eccentric cam;
• a link arm linked at a first end to the drive eccentric cam in such a manner as to pivot about a first fulcrum X corresponding to a geometric center of the drive eccentric cam, and further linked at a second end to the rocker arm in such a manner as to pivot about a second fulcrum R provided on the rocker arm;
• and
• a link rod linked at a first end to the rocker arm in such a manner as to pivot about a third fulcrum S provided on the rocker arm at a position different from the second fulcrum R, and further pivotably linked at a second end to the connecting portion of the rockable cam;
• and
• an actuator adapted to drive the control shaft by an electric motor,
• wherein at least a working angle of the engine valve varies by rotating the control shaft;
• and
• wherein, during a transition from minimum working-angle control to maximum working-angle control by rotating the control shaft, the third fulcrum S revolves about the second fulcrum R with a displacement relative to a straight line, which connects the first and second fulcrums X and R, in one direction, and thereafter revolves about the second fulcrum R in the opposite direction.

A variable valve actuation apparatus of an internal combustion engine comprising:

• a drive shaft having a drive support shaft and a substantially oval drive cam fixed to the drive support shaft and protruded radially outward from the drive support shaft, and adapted to be driven by a torque transmitted from an engine crankshaft to the drive shaft;
• a control shaft having a control support shaft and a substantially cylindrical control eccentric cam, which cam is fixed to the control support shaft and whose geometric center is displaced from a shaft axis of the control support shaft, and configured to rotate about its rotation axis;
• a rockable cam pivotably supported by a pivot, and having a cam nose portion and a connecting portion such that the cam nose portion and the connecting portion are arranged on opposite sides of the pivot, and adapted to actuate an engine valve by a cam contour surface portion defined between the cam nose portion and the connecting portion;
• a rocker arm, which is pivotably supported by an outer periphery of the control eccentric cam and to which an oscillating force is transmitted by rotary motion of the drive cam;
• a link rod linked at a first end to the rocker arm in such a manner as to pivot about a fulcrum provided on the rocker arm, and further pivotably linked at a second end to the connecting portion of the rockable cam;
• and
• an actuator adapted to drive the control shaft by an electric motor,
• wherein at least a working angle of the engine valve varies by rotating the control shaft;
• and
• wherein, during a transition from a minimum working-angle control state to a maximum working-angle control state by rotating the control shaft, at a peak lift during a valve opening period of the engine valve, a multinodular-link motion converter, including at least the rocker arm and the link rod, has both an operating range that the fulcrum of the rocker arm moves toward an extension line of a straight line, which connects a rotation center of the drive cam and a maximum protruded point of a cam lobe portion of the drive cam, and an operating range that the fulcrum of the rocker arm moves apart from the extension line of the straight line.

A variable valve actuation apparatus of an internal combustion engine comprising:

• a drive shaft having a drive eccentric cam, and adapted to be driven by a torque transmitted from an engine crankshaft to the drive shaft;
• a control shaft having a control eccentric cam and configured to rotate about its rotation axis;
• a rocker arm configured to pivot about the control eccentric cam;
• a rockable cam pivotably supported by a pivot, and having a connecting portion and a cam contour surface portion formed on an outer periphery of the rockable cam, and adapted to actuate an engine valve by the cam contour surface portion;
• a link arm linked at a first end to the drive eccentric cam in such a manner as to pivot about a first fulcrum X corresponding to a geometric center of the drive eccentric cam, and further linked at a second end to the rocker arm in such a manner as to pivot about a second fulcrum R provided on the rocker arm;
• a link rod linked at a first end to the rocker arm in such a manner as to pivot about a third fulcrum S provided on the rocker arm at a position different from the second fulcrum R, and further pivotably linked at a second end to the connecting portion of the rockable cam;
• and
• an actuator adapted to drive the control shaft by an electric motor,
• wherein at least a working angle of the engine valve varies by rotating the control shaft;
• wherein pushing up the link arm by the drive eccentric cam causes a valve-lifting motion of the rockable cam, thereby opening the engine valve;
• and
• wherein, during a transition from a minimum working-angle control state to a maximum working-angle control state by rotating the control shaft, the third fulcrum S revolves about the second fulcrum R with a displacement relative to a straight line, which connects the first and second fulcrums X and R, in one direction, and thereafter revolves about the second fulcrum R in the opposite direction.