Control system and method for controlling an internal combustion engine

Abstract

An engine includes two or more banks, VVTL mechanisms provided for the respective banks for changing the operating characteristics of intake valves, and a control device that controls the VVTL mechanisms. The control device controls the VVTL mechanisms by integrating a plurality of pieces of control information corresponding to the respective VVTL mechanisms. When one of the pieces of control information becomes unknown, the control device performs a process of learning the control information with respect to the VVTL mechanism for the bank involving the unknown control information, and continues to control the VVTL mechanism for the other bank or banks, using the corresponding control information.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and/or further objects, features and advantages of the invention will become more apparent from the following description of an exemplary embodiment with reference to the accompanying drawings, in which like numerals are used to represent like elements and wherein:

FIG. 1 is a view showing the construction of an engine according to one embodiment of the invention;

FIG. 2 is a graph indicating some examples of the relationship between the lift amount of valves and the crank angle, which are established by a variable valve actuating mechanism;

FIG. 3 is a front view of a VVL mechanism that controls the lift and duration of an intake valve;

FIG. 4 is a perspective view showing a part of the VVL mechanism;

FIG. 5 is a cross-sectional view showing an actuator that linearly moves a drive shaft of the VVL mechanism in the axial direction thereof;

FIG. 6 is a first operation waveform diagram used for explaining re-learning performed after a learned value or values of the variable valve actuating mechanism is/are cleared;

FIGS. 7A and 7B are a set of flowcharts illustrating a re-learning process executed by a control device for re-learning the position of the maximum lift end of a drive element driven by an actuator;

FIG. 8 is a second operation waveform diagram used for explaining a process of learning the mechanical LOW end of the drive element; and

FIGS. 9A and 9B are a set of flowcharts illustrating a process of learning the position of the minimum lift end of the drive element driven by the actuator.

Claims

1. A control system for an internal combustion engine including a plurality of banks and a plurality of variable valve actuating mechanisms, provided for the respective banks, for changing operating characteristics of variable valves, the control system comprising: a control device that controls the plurality of variable valve actuating mechanisms, by integrating a plurality of pieces of control information corresponding to the respective variable valve actuating mechanisms;wherein, when at least one of the plurality of pieces of control information becomes unknown, the control device learns the control information with respect to the variable valve actuating mechanism for the bank involving the unknown control information, and continues to control the variable valve actuating mechanism for the remaining banks of the plurality of banks, using the known control information of the plurality of pieces of control information.

2. The control system according to claim 1, wherein: the variable valve actuating mechanisms changes the operating characteristics of intake valves.

3. The control system according to claim 2, wherein: each of the variable valve actuating mechanisms includes an actuator that moves a drive element to adjust a lift of each of the intake valves of the corresponding bank, and a sensor that detects a change in a relative position of the drive element of the actuator;

4. The control system according to claim 3, wherein: each of the variable valve actuating mechanisms further includes a variable valve timing mechanism that advances or retards the opening timing of each of the intake valves; andthe control device causes the variable valve timing mechanisms for the first and second banks to hold the opening timing at a specified middle position during an operation for learning the first reference position.

5. The control system according to claim 2, wherein each of the variable valve actuating mechanisms moves the drive element so as to increase the lift and duration of each of the intake valves

6. The control system according to claim 1, wherein the variable valve actuating mechanisms changes the operating characteristics of exhaust valves.

7. A method of controlling an internal combustion engine including a plurality of banks, and a plurality of variable valve actuating mechanisms provided for the respective banks for changing operating characteristics of variable valves, the method comprising: integrating a plurality of pieces of control information corresponding to the respective variable valve actuating mechanisms;controlling the variable valve actuating mechanisms in accordance with the integration of the plurality of pieces of control information; andlearning the control information with respect to the variable valve actuating mechanism when at least one of the plurality of pieces of control information becomes unknown for one of the plurality of banks, and continuing to control the variable valve actuating mechanism for the remaining banks of the plurality of banks, using the known control information of the plurality of pieces of control information.

8. The method according to claim 7, wherein: the variable valve is an intake valve.

9. The method according to claim 8, wherein: each of the variable valve actuating mechanisms includes an actuator that moves a drive element to adjust a lift of each of the intake valves of the corresponding bank, and a sensor that detects a change in a relative position of the drive element of the actuator;the control information includes an absolute position of the drive element which is calculated by adding the change in the relative position to a reference position in accordance with an output of the sensor;when the absolute position calculated with respect to a first bank of the plurality of banks becomes unknown, the absolute position is provisionally set to a value of a first operational limit of the drive element which provides the lowest lift of the intake valve, and the actuator is operated to gradually increase the lift until the drive element reaches a second operational limit, which provides the highest lift of the intake valve, so that a first reference position is learned as the absolute position when the drive element reaches the second operational limit; andduring the learning process for the first bank, the actuator for another bank of the plurality of banks, in which the absolute position is known, is operated to move the drive element within a specified range between the first and second operational limits, in accordance with the movement of the drive element for the first bank.

10. The method according to claim 9, wherein: each of the variable valve actuating mechanisms further includes a variable valve timing mechanism that advances or retards the opening timing of each of the intake valves; andthe variable valve timing mechanisms for the first and second banks hold the opening timing at a specified middle position during an operation for learning the first reference position.

11. The method according to claim 8, wherein each of the variable valve actuating mechanisms moves the drive element so as to increase the lift and duration of each of the intake valves.

12. The method according to claim 7, wherein the variable valve is an exhaust valve.