Control device for engine valve and control system for engine

Abstract

A rotational phase difference of a camshaft relative to a crankshaft in a variable valve timing mechanism is controlled by an operation of an oil control valve. That is, in the oil control valve, there is outputted an operational signal which is defined by adding a feedback correction amount corresponding to a difference between an actual value and a target value of the rotational phase difference, to a holding learning value as the operational signal for holding the rotational phase difference. The holding learning value is altered only by a specified value on condition that the operational signal for holding the rotational phase difference is assumed to change.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features, and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which like parts are designated by like reference numbers and in which:

FIG. 1 is a diagram showing a structure of a control system of an engine valve in a first embodiment of the present invention;

FIG. 2 is a graph showing a relation between an operational signal of an oil control valve and a cam angular displacement velocity in the first embodiment;

FIG. 3 is a flow chart showing a routine for control of a rotational phase difference in the first embodiment;

FIGS. 4A and 4B are time charts each showing a state of the control of the rotational phase difference;

FIGS. 5A, 5B, 5C and 5D are time charts each showing a problem of the conventional control;

FIG. 6 is a flow chart showing a routine for control of a rotational phase difference in a second embodiment of the present invention;

FIG. 7 is a flow chart showing a routine for fixation control of a rotational phase difference in a third embodiment of the present invention;

FIG. 8 is a flow chart showing a routine for control of a rotational phase difference in the third embodiment; and

FIG. 9 is a flow chart showing a routine for control of a rotational phase difference in a fourth embodiment of the present invention.

Claims

1. A control device of an engine valve comprising: a rotational phase difference-adjusting means which varies a rotational phase difference of a camshaft relative to a crankshaft to adjust operating timing of an engine valve;a crank angle detector for detecting a rotational angle of the crankshaft;a cam angle detector for detecting a rotational angle of the camshaft;a phase difference-calculating means which calculates the rotational phase difference based upon a detection value of the crank angle detector and a detection value of the cam angle detector;a learning means which learns a holding learning value as an operational signal of the rotational phase difference-adjusting means for holding the rotational phase difference;a calculating means which calculates a feedback correction amount in accordance with a difference between an actual value and a target value of the rotational phase difference;a control means which feedback-controls the actual value to the target value by operating the rotational phase difference-adjusting means with the feedback correction amount by setting the holding learning value as a reference; andan alteration means which alters the holding learning value as the reference only by a specified value on condition that the operational signal for holding the rotational phase difference is assumed to change.

2. A control device of an engine valve according to claim 1, wherein: when a difference between the actual value and the target value is more than a predetermined value, the alteration means alters the holding learning value to reduce the difference.

3. A control device of an engine valve according to claim 2, wherein: the alteration means alters the holding learning value when the difference between the actual value and the target value is more than the predetermined value and a changing amount of the target value is more than a predetermined amount.

4. A control device of an engine valve according to claim 3, wherein: the alteration means variably sets the specified value in accordance with the changing amount.

5. A control device of an engine valve according to claim 1, wherein: the rotational phase difference is fixed near the maximum retard position under a predetermined condition; andthe alteration means alters the holding learning value to an advance side only by the specified value when a fixation period of the rotational phase difference is more than a prescribed period.

6. A control device of an engine valve according to claim 5, wherein: the alteration means variably sets the specified value in accordance with the fixation period.

7. A control device of an engine valve according to claim 5, wherein: the predetermined condition is operation stop time of an internal combustion engine;the phase difference-adjusting means includes a holding mechanism for mechanically holding the rotational phase difference at a value in the vicinity of the maximum retard value;the alteration means alters the holding learning value to the advance side only by the specified value when the operation stop time is more than a predetermined time.

8. A control device of an engine valve according to claim 5, wherein: the predetermined condition includes idling operating time.

9. A control device of an engine valve according to claim 1, wherein: the specified value is set within a changing amount assumed as a value of the operational signal for holding the rotational phase difference.

10. A control device of an engine valve comprising: a phase difference-adjusting means which varies a rotational phase difference of a cam shaft relative to a crank shaft to adjust operating timing of an engine valve;a crank angle detector for detecting a rotational angle of the crankshaft;a cam angle detector for detecting a rotational angle of the camshaft;a phase difference-calculating means which calculates the rotational phase difference based upon a detection value of the crank angle detector and a detection value of the cam angle detector;a learning means which learns a holding learning value as an operational signal of the rotational phase difference-adjusting means for holding the rotational phase difference;a calculating means which calculates a feedback correction amount in accordance with a difference between an actual value and a target value of the rotational phase difference; anda control means which feedback-controls the actual value to the target value by operating the rotational phase difference-adjusting means with the feedback correction amount by setting the holding learning value as a reference; andan alteration means which alters the holding learning value only by a specified value to reduce a difference between the actual value and the target value when the difference is more than a predetermined value.

11. A control device of an engine valve according to claim 10, wherein: when the difference between the actual value and the target value is more than the predetermined value and a changing amount of the target value is more than a predetermined amount, the alteration means alters the holding learning value only by the specified value to a side for following the change of the target value.

12. A control device of an engine valve according to claim 11, wherein: the alteration means variably sets the specified value in accordance with the changing amount.

13. A control system of an engine valve comprising: a phase difference-adjusting means for varying a rotational phase difference of a camshaft relative to a crankshaft to adjust operational timing of the engine valve;a crank angle detecting means for detecting a rotational angle of the crankshaft;a cam angle detecting means for detecting a rotational angle of the camshaft;a phase difference-calculating means for calculating the rotational phase difference based upon a detection value of the crank angle detecting means and a detection value of the cam angle detecting means;a learning means for learning a holding learning value as an operational signal of the rotational phase difference-adjusting means for holding the rotational phase difference;a calculating means for calculating a feedback correction amount in accordance with a difference between a target value and an actual value of the rotational phase difference;a control means for feedback-controlling the actual value to the target value by operating the rotational phase difference-adjusting means with the feedback correction amount by setting the holding learning value as a reference; andan alteration means for altering the holding learning value as the reference only by a specified value on condition that the operational signal for holding the rotational phase difference is assumed to change.