Intake air control apparatus for vehicular internal combustion engine

A method for controlling an intake valve which regulates intake air to a vehicular internal combustion engine, the engine having a variable valve operating mechanism configured to vary a valve lift of the intake valve and to vary a phase angle of the intake valve by independently and separately operating a variable valve lift mechanism and a variable valve phase angle mechanism, the variable valve phase angle mechanism having a response speed that is slower than a response speed of the variable valve lift mechanism, the method comprising:

• calculating a first target value corresponding to a valve lift and a valve phase angle which are desired in a current engine operating condition;
• when an accelerator is in a fully closed position, calculating an estimated reacceleration value corresponding to a hypothetical valve lift and a hypothetical valve phase angle at which the intake valve does not contact a piston, wherein the hypothetical valve lift and the hypothetical valve phase angle are based on an estimated load upon reacceleration and a current engine rotational speed different from the valve lift and the valve phase angle which are desired at the current engine operating condition;
• determining whether or not a minimum clearance between the intake valve and the piston would become less than a permissible value during variation of the valve lift and the valve phase angle from the first target value toward the reacceleration estimated value;
• calculating a second target value corresponding to a combination of the valve lift and the valve phase angle at which the engine torque is equivalent to the engine torque produced at the first target value, the minimum clearance remains greater than or equal to the permissible value, and the valve phase angle is more retarded than that of the first target value;
• and
• setting the first target value as a control target value, and then switching the control target value from the first target value to the second target value when it is determined that the minimum clearance would become less than the permissible value during variation of the valve lift and the valve phase angle from the first target value toward the reacceleration estimated value, wherein the variable valve operating mechanism starts to vary the actual valve lift of the intake valve and the actual phase angle of the intake valve according to the control target value prior to the reacceleration.

An intake air control apparatus for controlling an intake valve which regulates intake air to a vehicular internal combustion engine, the intake air control apparatus comprising:

• variable valve operating means for varying a valve lift and a valve phase angle of the intake valve by independently and separately operating a variable valve lift means and a variable valve phase angle means, the variable valve phase angle means having a response speed that is slower than a response speed of the variable valve lift means;
• first target value calculating means for calculating a first target value corresponding to a combination of the valve lift and the valve phase angle which is desired at a current engine operating condition;
• reacceleration estimated value calculating means for calculating, when an accelerator is in a fully closed position, a reacceleration estimated value corresponding to a combination of a hypothetical valve lift and a hypothetical valve phase angle at which the intake valve does not contact a piston, wherein the combination of the hypothetical valve lift and the hypothetical valve phase angle is based on a current engine rotational speed and an engine operating load estimated to occur upon reacceleration different from the combination of the valve lift and the valve phase angle which is desired at the current engine operating condition;
• determining means for determining whether or not a minimum clearance between the intake valve and the piston would become less than a permissible value during variation of the valve lift and the valve phase angle from the first target value toward the reacceleration estimated value;
• second target value calculating means for calculating a second target value corresponding to a combination of the valve lift and the valve phase angle at which the engine torque produced is equivalent to the torque produced at the first target value, the minimum clearance remains greater than or equal to the permissible value, and the valve phase angle is more retarded than that of the first target value;
• and
• setting means for setting the first target value as a control target value, and for then switching the control target value from the first target value to the second target value when the determining means determines that the minimum clearance would become less than the permissible value during variation of the valve lift and the valve phase angle from the first target value toward the reacceleration estimated value, wherein the variable valve operating means starts to the actual valve lift and the actual valve phase angle of the intake valve to follow the control target value prior to the reacceleration.