INTERNAL COMBUSTION ENGINE CONTROL APPARATUS

Abstract

An internal combustion engine control apparatus is provided with a hydraulically operated variable valve operating mechanism for varying the valve timing of air intake valves, and a water temperature sensor for sensing engine coolant temperature to estimate the degree of engine warm-up. The valve operating mechanism is controlled to switch the valve timing from the warm-up idle valve timing with a high idling speed to the post-warm-up idle valve timing with a slower idling speed as the engine temperature approaches the warm-up temperature threshold. The switch in valve timings starts before an engine rotational speed falls below a rotational speed threshold lying between the high idling speed during the warm-up idling and the post-warm-up idling speed during the post-warm-up idling such that a sufficient hydraulic pressure switch the valve timing with a specific degree of responsiveness is attained when the engine rotational speed is at or above the rotational speed threshold.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of this original disclosure:

FIG. 1 is a diagrammatic perspective view illustrating key components of a variable valve operating mechanism of an intake control apparatus for the internal combustion engine in accordance with a preferred present invention;

FIG. 2(A) is a diagrammatic operation diagram illustrating a zero lift operation of a lift/operating angle varying mechanism of the variable valve operating mechanism in accordance with the preferred embodiment of the present invention;

FIG. 2(B) is a diagrammatic view operation diagram illustrating a full lift operation of the lift/operating angle varying mechanism of the variable valve operating mechanism in accordance with the preferred embodiment of the present invention;

FIG. 3 is a characteristic diagram showing the characteristic changes of the lift/operating angle (i.e., lift and duration of air intake valves) made by the lift/operating angle varying mechanism in accordance with the preferred embodiment of the present invention;

FIG. 4 is a timing characteristic diagram showing the phase changes in the valve lift characteristics made by the phase varying mechanism in accordance with the preferred embodiment of the present invention;

FIG. 5 is a map for calculating the phase of the lift center angle of the air intake valves determined according to load and engine rotational speed in accordance with the preferred embodiment of the present invention;

FIG. 6 is a diagram schematically showing the valve timing of the air intake valves during the fast idling state in accordance with the preferred embodiment of the present invention;

FIG. 7 is a diagram schematically showing the valve timing of the air intake valves during the post-warm-up idling state in accordance with the preferred embodiment of the present invention;

FIG. 8 is a characteristic diagram showing the correlating relationship between engine rotational speed and hydraulic pressure in accordance with the preferred embodiment of the present invention;

FIG. 9 is a timing chart depicting a case in which the valve timings of the air intake valves are switched from the fast idling state to valve timings for the post-warm-up idling state in accordance with the preferred embodiment of the present invention;

FIG. 10 is a flowchart showing the setting of the engine rotational speed during idling based on the coolant temperature of the engine in accordance with the preferred embodiment of the present invention; and

FIG. 11 is a flowchart describing the switching of the valve timing of the air intake valves at the end of the fast idling phase ahead of the timing at which a switch is made from the fast idling state to the post-warm-up idling state in accordance with the preferred embodiment of the present invention.

Claims

1. An internal combustion engine control apparatus comprising: a hydraulically operated variable valve operating mechanism configured to vary a valve timing of air intake valves; anda valve timing control section configured to control the hydraulically operated variable valve operating mechanism to set the valve timing to a warm-up idle valve timing with a high idling speed when engine temperature is determined to be cold and to set the valve timing to a post-warm-up idle valve timing with a post-warm-up idling speed when the engine temperature is determined to be equal to or above a warm-up temperature threshold, the high idling speed being higher than the post-warm-up idling speed,the valve timing control section being further configured to switch the valve timing from the warm-up idle valve timing to the post-warm-up idle valve timing as the engine temperature approaches the warm-up temperature threshold such that the switch starts before an engine rotational speed falls below a rotational speed threshold lying between the high idling speed during the warm-up idle valve timing and the post-warm-up idling speed during the post-warm-up idle valve timing such that a sufficient hydraulic pressure switch the valve timing with a specific degree of responsiveness is attained when the engine rotational speed is at or above the rotational speed threshold.

2. The internal combustion engine control apparatus according to claim 1, wherein the valve timing control section is further configured to set a lift center angle phase of the air intake valves such that a the warm-up lift center angle phase for the warm-up idle valve timing is more retarded than a post-warm-up lift center angle phase for the post-warm-up idle valve timing; andthe valve timing control section is further configured to advance the lift center angle phase of the air intake valves such that the post-warm-up lift center angle phase is reached before the post-warm-up idling speed is reached, when switching from the warm-up idle valve timing to the post-warm-up idle valve timing.

3. The internal combustion engine control apparatus according to claim 2, wherein the valve timing control section is further configured to advance the lift center angle phase of the air intake valves such that the post-warm-up lift center angle phase is reached before the rotational speed threshold is reached, when switching from the warm-up idle valve timing to the post-warm-up idle valve timing.

4. The internal combustion engine control apparatus according to claim 2, wherein the variable valve operating mechanism comprises a hydraulically operated lift/operating angle varying mechanism configured to continuous control a valve lift and a valve operating angle of the air intake valves to selectively increase or decrease the valve lift and the valve operating angle of the air intake valves.

5. The internal combustion engine control apparatus according to claim 4, wherein the valve timing control section is further configured to switch the valve lift and the valve operating angle of the air intake valves such that the valve lift and the valve operating angle used for the post-warm-up idle valve timing phase is reached before the post-warm-up idling speed is reached, when switching from the warm-up idle valve timing to the post-warm-up idle valve timing.

6. The internal combustion engine control apparatus according to claim 4, wherein the valve timing control section is further configured to switch the valve lift and the valve operating angle of the air intake valves such that the valve lift and the valve operating angle used for the post-warm-up idle valve timing phase is reached before the rotational speed threshold is reached, when switching from the warm-up idle valve timing to the post-warm-up idle valve timing.

7. The internal combustion engine control apparatus according to claim 1, wherein the valve timing control section is further configured to control the switch from the warm-up idle valve timing to the post-warm-up idle valve timing such that the switching to the post-warm-up idle valve timing finishes at or before the rotational speed threshold.

8. An engine comprising the internal combustion engine control apparatus according to claim 1.

9. An internal combustion engine control apparatus comprising: hydraulically operated variable valve operating means for varying a valve timing of air intake valves; andvalve timing control means for controlling the hydraulically operated variable valve operating means to set the valve timing to a warm-up idle valve timing with a high idling speed when engine temperature is determined to be cold and to set the valve timing to a post-warn-up idle valve timing with a post-warm-up idling speed when the engine temperature is determined to be equal to or above a warm-up temperature threshold, the high idling speed being higher than the post-warm-up idling speed,the valve timing control means further performing switching of the valve timing from the warm-up idle valve timing to the post-warm-up idle valve timing as the engine temperature approaches the warm-up temperature threshold such that the switch starts before an engine rotational speed falls below a rotational speed threshold lying between the high idling speed during the warm-up idle valve timing and the post-warm-up idling speed during the post-warm-up idle valve timing such that a sufficient hydraulic pressure switch the valve timing with a specific degree of responsiveness is attained when the engine rotational speed is at or above the rotational speed threshold.

10. A method for controlling an intake air for an internal combustion engine comprising: varying a valve timing of air intake valves;setting the valve timing to a warm-up idle valve timing with a high idling speed when engine temperature is determined to be cold;setting the valve timing to a post-warm-up idle valve timing with a post-warm-up idling speed when the engine temperature is determined to be equal to or above a warm-up temperature threshold, the high idling speed being higher than the post-warm-up idling speed andswitching of the valve timing from the warm-up idle valve timing to the post-warm-up idle valve timing as the engine temperature approaches the warm-up temperature threshold such that the switch starts before an engine rotational speed falls below a rotational speed threshold lying between the high idling speed during the warm-up idle valve timing and the post-warm-up idling speed during the post-warm-up idle valve timing such that a sufficient hydraulic pressure switch the valve timing with a specific degree of responsiveness is attained when the engine rotational speed is at or above the rotational speed threshold.