Valve operating control system for internal combustion engine

Details Valve operating control system for internal combustion engine Valve operating control system for internal combustion engine

2000-02-04

2001-04-17

Lo, Weilun (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

C123S090170

Reexamination Certificate

active

06216655

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valve operating control system for an internal combustion engine, including a cam change-type valve operating characteristic changing mechanism, and a control unit for controlling the valve operating characteristic changing mechanism in a feedback manner and in a feed-forward manner.
2. Description of the Prior Art
Internal combustion engines, which include a cam phase changing-type valve operating characteristic changing mechanism constructed to continuously control the timing of the opening and closing of an intake valve or an exhaust valve, are known from Japanese Patent Application Laid-open No. 59-93964 and Japanese Patent Publication No. 5-43847.
In carrying out the control for converging a deviation between an actual cam phase and a target cam phase to zero in such valve operating characteristic changing mechanism, if the feedback control is carried out when the deviation is large, a responsiveness can be ensured, but there is a possibility that the actual cam phase overshoots the target cam phase, whereby the convergence cannot be ensured. In such a case, it is conceived that while the deviation is large, a feed-forward control is carried out to ensure the convergence, and after the deviation becomes small, feedback control is carried out, thereby enabling the responsiveness and the convergence to be reconciled.
When the feedback control and the feed-forward control are used in combination with each other, the effect can be exhibited in a particular operational state of the internal combustion engine, however, there is a possibility that a sufficient effect cannot be obtained depending on the operational state of the internal combustion engine over a wide range of an operational condition, e.g., the level of the engine temperature.
SUMMARY OF THE INVENTION
The present invention has been accomplished with the above circumstance in view, and it is an object of the present invention to ensure that when the valve operating characteristic changing control for converging the deviation between the actual cam phase and the target cam phase of the internal combustion engine to zero, is carried out, the responsiveness and the convergence can be reconciled independent of the operational state of the internal combustion engine.
To achieve the above object, there is provided a valve operating system for an internal combustion engine, comprising a cam phase changing-type valve operating characteristic changing mechanism capable of continuously changing a cam phase in the internal combustion engine. A control means controls the valve operating characteristic changing mechanism in a feedback manner and in a feed-forward manner, based on the deviation between a target cam phase set in accordance with the operational state of the internal combustion engine and an actual detected cam phase to converge the deviation to zero. The control means controls the valve operating characteristic changing mechanism in the feedback manner, when the deviation is equal to or smaller than a feed-forward determining threshold value, and controls the valve operating characteristic changing mechanism in the feed-forward manner with a basic operational amount, when the deviation exceeds the feed-forward determining threshold value. The control means is arranged so that as the engine temperature is higher, or as the deviation is larger, the basic operational amount is increased more.
With the above arrangement, by controlling the valve operating characteristic changing mechanism in the feed-forward manner with the basic operational amount, when the deviation between the target cam phase and the actual cam phase exceeds the feed-forward determining threshold value, it is possible to prevent a reduction in convergence due to the occurrence of overshooting feared when the feedback control is carried out. In addition, by controlling the valve operating characteristic changing mechanism in the feedback manner, when the deviation becomes equal to or smaller than the feed-forward determining threshold value to eliminate the occurrence of the overshooting, the actual cam phase can be converged into the target cam phase with a high responsiveness and a high convergence. Moreover, in carrying out the feed-forward control, as the engine temperature becomes higher, or as the deviation becomes larger, the basic operational amount is increased more. Therefore, it is possible to further enhance the convergence in the feed-forward control.
The feed-forward determining threshold value in the present invention corresponds to a second feed-forward control determining value #DCAINFFR in the disclosed embodiment; the basic operational amount in the present invention corresponds to a highest limit value #DVLMTH2 in the disclosed embodiment, and the engine temperature in the present invention corresponds to a cooling-water temperature TW in the disclosed embodiment.


REFERENCES:
patent: 5184578 (1993-02-01), Quinn, Jr. et al.
patent: 5289805 (1994-03-01), Quinn, Jr. et al.
patent: 5562071 (1996-10-01), Urushihata et al.
patent: 5937808 (1999-08-01), Kako et al.
patent: 6079381 (2000-06-01), Morikawa
patent: 59-93964 (1984-05-01), None
patent: 5-43847 (1993-07-01), None

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