Control apparatus for internal-combustion engine with variable valve mechanism

Abstract

An intake variable valve mechanism 34 is provided that allows closing timing of an air intake valve 30 to be varied. The intake variable valve mechanism 34 has a first control mode that controls IVC timing of the intake valve 30 at an angle-advancing side relative to a certain range including an air intake bottom dead center BDC, and a second control mode that controls the IVC timing of the intake valve 30 at an angle-retarding side relative to the certain range. IVC variable control (first control mode) for making the IVC timing of the intake valve 30 variable according to load is selected for operation in a region of relative low loads, and intake valve closing retardation control (second control mode) for controlling the intake valve 30 in fully retarded IVC timing is selected for operation in a region of relatively high loads.

Description

TECHNICAL FIELD[0001]The present invention relates to a control apparatus for an internal-combustion engine having a variable valve mechanism.BACKGROUND ART[0002]Patent Document 1, for example, discloses a control apparatus for an internal-combustion engine having a variable valve mechanism to make variable the opening and closing timing of an air intake valve and the lift amount thereof. The conventional control apparatus as described in Patent Document 1 is constructed so that when knock is detected, the apparatus executes control to suppress knock and suppress changes in torque. More specifically, as an example of the control performed when knock is detected, the conventional control apparatus operates to increase the opening area of the intake valve as well as to advance the closing timing thereof.[0003]Including the above-mentioned document, the applicant is aware of the following document as a related art of the present invention.[0004][Patent Document 1] Japanese Patent Laid-...

AI Technical Summary

Benefits of technology

[0007]In an internal-combustion engine with a variable valve mechanism for making variable the opening and closing timing of an intake valve and the lift amount thereof, as in the foregoing conventional internal-combustion engine, such intake air amount control as outlined below may take place to reduce pumping loss for improved fuel efficiency. That is to say, the intake air amount may be controlled such that: the closing timing of the intake valve is advanced by reducing the operating angle of the intake valve to limit the amount of air passed through the intake valve, and a throttle angle is correspondingly increased at the same time.

[0008]According to the above control of the intake air amount, when an operating region of the internal-combustion engine changes from a low-load region to a high-load region, pumping loss is reduced by gradually increasing the operating angle in accordance with the load required of the internal-combustion engine. As a result, an operating angle equivalent to the very timing in which the intake valve is closed near a bottom dead center will be used in a medium-load region. When the intake valve is closed near the bottom dead center, an actual in-cylinder compression ratio will increase and knock will be more likely to occur.

[0009]The present invention has been made for solving the above problem, and an object of the invention is to provide a control apparatus which can control an operating state of an internal-combustion engine while properly avoiding knock in the internal-combustion engine having a variable valve mechanism to make at least closing timing of an intake valve variable

Problems solved by technology

When the intake valve is closed near the bottom dead center, an actual in-cylinder compression ratio will increase and knock will be more likely to occur.

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