Internal-combustion engines – Spark ignition timing control – Electronic control
Reexamination Certificate
2001-05-11
2001-12-04
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Spark ignition timing control
Electronic control
C123S406120
Reexamination Certificate
active
06325047
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control apparatus for an internal combustion engine, provided with a variable valve timing mechanism (VVT) for variably controlling an opening/closing timing (valve timing) of an intake valve and an exhaust valve of the internal combustion engine in response to an operating condition of the engine, and more particularly to a control apparatus for an internal combustion engine for controlling a fuel injection amount or an ignition timing in response to a change in the valve timing.
2. Description of the Related Art
Conventionally, in a D-jetro type control apparatus for an internal combustion engine, a fuel injection amount or an ignition timing has been controlled by using a volumetric efficiency or ignition timing which has been obtained from the number of revolutions per minute (rpm) of the engine or an intake pressure. Thus, in the D-jetro system, the volumetric efficiency or the ignition timing is obtained by using the rpm of the engine and the intake pressure as parameters. The volumetric efficiency and the ignition timing are obtained at a plurality of points from a plurality of the rpms of the engines and intake pressures to thereby prepare a map, and values other than the values obtained in advance with respect to the volumetric efficiency and the ignition timing are obtained from the map by way of interpolation.
Such a method for obtaining the volumetric efficiency is effective in the case where the opening/closing timing of the exhaust/intake valve is kept constant. However, in the internal combustion engine provided with the VVT for variably and continuously controlling the valve timing, even if the rpm of the engine or the intake pressure is kept constant, a change in the opening/closing timing of the exhaust/intake valves causes a change in the volumetric efficiency or the optimum ignition timing. Then, the change in the volumetric efficiency and/or the ignition timing relative to the change of such valve timing is not constant depending upon the rpm of the engine or the intake pressure.
Accordingly, in the internal combustion engine provided with the VVT, in the case where the opening/closing timing of the exhaust/intake valve is changed, there arises a problem in that the fuel injection amount or the target ignition timing may be shifted from the optimum value.
SUMMARY OF THE INVENTION
Accordingly, the present invention is intended to overcome the above-noted problem inherent in the prior art, and has for its object to provide a control apparatus for a D-jetro type internal combustion engine having a VVT mechanism, which is capable of preparing a plurality of maps of control quantities such as a volumetric efficiency, an ignition timing and the like in accordance with a shift amount of opening/closing timing of an intake valve and/or an exhaust valve, interpolating the values between the maps on the basis of an actual shift amount of the actual valve timing and exactly obtaining the volumetric efficiency or the ignition timing corresponding to the shift amount even if the opening/closing timing of the intake valve and/or the exhaust valve is changed, whereby the fuel injection amount and the ignition timing may be optimally controlled.
Another object of the present invention is to provide a control apparatus for an internal combustion engine in which the amount of data to be stored in a memory may be reduced as much as possible when the volumetric efficiency or the ignition timing is to be obtained in response to the shift amount of the opening/closing timing of the intake valve and/or the exhaust valve.
Bearing the above objects in mind, according to a first aspect of the present invention, there is provided a control apparatus for an internal combustion engine for variably controlling an opening/closing timing of an intake valve and an exhaust valve of the internal combustion engine in response to an engine operating condition. The apparatus comprises: a memory for storing a fuel control parameter as a plurality of data preset on the basis of an intake pressure and an rpm of the internal combustion engine; a valve opening/closing element provided on a camshaft which is operably connected with a crank shaft of the internal combustion engine for drivingly opening/closing the intake valve and the exhaust valve in synchronism with a rotation of the crank shaft; a rotational phase controller for shifting a rotational phase of the camshaft relative to the crank shaft; a shift amount detector for detecting a shift amount of the rotational phase of the camshaft relative to the crank shaft caused by the rotation shift controller; a compensator for calculating control data on the basis of the intake pressure and the rpm of the engine and the plurality of data of the fuel control parameter stored in the memory and for compensating the calculated data on the basis of the detection value of the shift amount detector; and a fuel injection amount controller for controlling a fuel injection amount to each cylinder of the internal combustion engine in accordance with data in which the fuel control parameter has been compensated for. The fuel control parameter has a change-rate change maximum point at which a change in a change rate of the fuel control parameter relative to the shift amount he cam shaft is at maximum, and the data of the fuel control parameter is determined in advance for each shift amount substantially corresponding to the change-rate change maximum point.
In a preferred form of the first aspect of the invention, values of the fuel control parameter other than the stored data are obtained through an interpolation calculation in response to a detection value of the shift amount detector from the stored fuel control parameter corresponding to the shift amount close to the detection value.
In another preferred form of the first aspect of the invention, the control apparatus further comprises an overlap amount calculator for calculating an overlap amount of the intake valve and the exhaust valve on the basis of the detection value of the shift amount detector. The fuel control parameter is a value that is smaller at least in a region where the overlap amount is greater than a predetermined value than that in the other regions thereof.
According to a second aspect of the present invention, there is provided a control apparatus for an internal combustion engine for variably controlling an opening/closing timing of an intake valve and an exhaust valve of the internal combustion engine in response to an engine operating condition. The apparatus comprises: a memory for storing an ignition timing control parameter as a plurality of data preset on the basis of an intake pressure and an rpm of the internal combustion engine; a valve opening/closing element provided on a camshaft which is operably connected with a crank shaft of the internal combustion engine for drivingly opening/closing the intake valve and the exhaust valve in synchronism with a rotation of the crank shaft; a rotational phase controller for shifting a rotational phase of the camshaft relative to the crank shaft; a shift amount detector for detecting a shift amount of the rotational phase of the camshaft relative to the crank shaft caused by the rotation shift controller; a compensator for calculating control data on the basis of the intake pressure, the rpm of the engine and the plurality of data of the ignition timing control parameter stored in the memory and for compensating the calculated data on the basis of the detection value of the shift amount detector; and an ignition timing controller for controlling an ignition timing for each cylinder of the internal combustion engine in accordance with data in which the ignition timing control parameter has been compensated for. The ignition timing control parameter has a change-rate change maximum point at which a change in a change rate of the ignition control parameter relative to the shift amount of the camshaft is at maximum, and the data of the ignition timing c
Argenbright Tony M.
Mitsubishi Denki & Kabushiki Kaisha
Sughrue Mion Zinn Macpeak & Seas, PLLC
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