Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
1999-09-27
2001-08-07
Wolfe, Willis R. (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C701S105000, C701S115000, C123S295000
Reexamination Certificate
active
06272424
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an engine control apparatus including an interpolation control means, and especially to an engine control apparatus including an interpolation control means such that, when the required operational state is switched between one state to another state, a desired value of a controlled variable can be smoothly changed from a desired value of the controlled variable in the one state to that in another state.
In engine control, it is necessary to switch an operational state of an engine in response to an operational requirement corresponding to a change in a running state of a vehicle with the engine. In the switching of an operational state, since a desired value of a controlled variable in one operational state differs from that in another operational state, the switching of an operational state of an engine has been generally performed by searching a prepared map and so on in which the relationship between a desired value of a controlled variable and each operational state of the engine is described.
The above engine control is explained below by taking up a fuel burning (referred to simply as burning) control in an engine as an example. In a direct injection engine, a lean-burn operation is performed. In the lean-burn operation, a stoichiometric mixture burning in the vicinity of the stoichiometric air to fuel ratio (homogeneous charge burning) or a lean air to fuel ratio mixture burning (stratified charge burning) is selected corresponding to a change of an operational state such as a change in a required load for an engine.
In the above lean-burn operation, since fuel is burn at a superlean air to fuel ratio (hereafter, referred to as A/F), the fuel consumption cost can be greatly reduced, and the gas exhaust performance can be improved. However, in order to burn fuel at a superlean A/F in the engine, it is necessary to inject highly-pressurized fuel into each cylinder of the engine. Although the fuel pressure to inject fuel into cylinders of an engine is often set as constant, it is also required to change the fuel pressure corresponding to a fuel burning state from the point of view of sufficiently bring out the burning performance of the engine. In a conventional burning control, to satisfy the above requirement, a map search method has been generally used. This method uses a prepared map in which the relationship between a desired value of the fuel pressure and each burning state of the engine is described, and if the switching of a burning state is required, a desired value of fuel pressure is selected by searching the map, and the burning state is stepwise switched by changing the desired value of fuel pressure.
If the fuel pressure to inject fuel into cylinders of an engine is changed, when the required burning state is switched, the desired value of the fuel pressure should be smoothly changed from a desired value in the present burning state to that in another burning state, these desired values being described in a map. Such a burning control is especially required from the standpoint of the burning stability. As mentioned above, if the desired value of fuel pressure is stepwise changed, the actual fuel pressure also rapidly changes, which degrades the burning controllability, and may cause stopping of fuel burning or engine shock.
SUMMARY OF THE INVENTION
The present invention has been achieved in consideration of the above described subjects, and is aimed at providing an engine control apparatus including an interpolation control means wherein, when an operational state is required to be changed, a desired value of a controlled valuable is smoothly switched to that of the required operational state of an engine in various kinds of engine operations including a burning operation in the engine.
To attain the above object, the present invention provides an engine control apparatus including an interpolation control means basically applicable to control changing an operational state of an engine to a required one of various kinds of operational states, the engine control apparatus comprising:
an interpolation control unit including;
desired value calculation means for calculating a desired value of a controlled variable corresponding to each operational state based on related control parameters of an engine;
determination means for determining changes of the operational state of the engine;
interpolation coefficient calculation means for calculating an interpolation coefficient of the controlled variable for an interpolated desired value of the controlled variable between desired values in a first operational state and a second operational state to which the operational state of the engine is switched from the first operational state; and
interpolated desired value calculation means for calculating changes of the interpolated desired value of the controlled variable based on changes of the interpolation coefficient and two desired values of the controlled variable in the first and second operational states;
wherein the interpolation control unit controls the controlled variable in switching of the operational state from the first state to the second state in the engine with the interpolated desired value whose changes are obtained by the interpolated desired value calculation means corresponding to the operational state determined by the state determination means.
As mentioned above, in accordance with the above engine control apparatus, since an operation state of an engine can be smoothly switched to another operational state by obtaining changes of the interpolated desired value of the controlled variable based on the changes of the interpolation coefficient and two desired values of the controlled value in the first and second operational state, and smoothly changing the operational state of the engine with the interpolated target, it is possible to prevent the control instability which may occur in switching of a desired value of a controlled variable between two different operational states.
Further, the present invention provides an engine control apparatus including an interpolation control means, the engine control apparatus comprising:
an interpolation control unit including;
desired value calculation means for calculating a desired value of fuel pressure corresponding to each burning state based on a quantity equivalent to an engine load and an engine rotational speed;
determination means for determining changes of the operational state of the engine;
interpolation coefficient calculation means for calculating an interpolation coefficient for an interpolated desired value of fuel pressure between desired values in a first burning state and a second burning state to which the burning state of the engine is switched from the first burning state;
interpolated desired value calculation means for calculating changes of the interpolated desired value of the fuel pressure based on changes of the interpolation coefficient and two desired values of the fuel pressure in the first and second burning states;
wherein the interpolation control unit controls the fuel pressure in switching of the burning state from the first to the second state in the engine with the interpolated desired value of fuel pressure, whose changes are obtained by the interpolated desired value calculation means corresponding to the burning state determined by the state determination means.
As mentioned above, in accordance with the above engine control apparatus, since a desired value of fuel pressure can be smoothly transferred to another desired value when the fuel pressure is changed in selecting one of a stoichiometric mixture burning in the vicinity of the stoichiometric A/F (homogeneous charge burning) or a lean A/F mixture burning (stratified charge burning) in the lean-burn operation, it is possible to prevent stopping of fuel burning or engine shock which may be caused in the switching between the two desired values of the fuel pressure.
Moreover, in the above engine control apparatus, the interpolation coefficient is obtaine
Iriyama Masahiro
Iwaki Hidefumi
Yoshida Yoshiyuki
Crowell & Moring , L.L.P.
Hitachi , Ltd.
Wolfe Willis R.
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