Internal-combustion engines – Charge forming device – Fuel injection system
Patent
1993-05-26
1994-08-16
Argenbright, Tony M.
Internal-combustion engines
Charge forming device
Fuel injection system
F02D 4300, F02D 4110, F02D 1702
Patent
active
053377206
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an engine control method, and more particularly, to an engine control method applied to a variable-cylinder engine whose operating state is changeable between a cylinder-off state, in which the operation of the engine for some cylinders is stopped, and a cylinder-on state, and in which fluctuations of the engine output caused by the change of the engine operating state can be reduced.
BACKGROUND ART
While a motor vehicle is running very normally on an ordinary road, it does not require a very high engine output, and is expected only to produce half the engine output that the motor vehicle can produce. Thus, a motor vehicle furnished with a multi-cylinder engine may be designed so that the engine operation for some of its cylinders can be stopped to reduce the output in this running state, whereby the fuel-cost performance can be improved.
Conventionally proposed, therefore, is a variable-cylinder engine which can be operated in either a cylinder-off state, in which the engine operation is stopped for some specific ones of its cylinders, or a cylinder-on state, in which the engine operation is performed for all of the cylinders. When operating the conventional variable-cylinder engine in the cylinder-off state, rocker arms of the specific cylinders are rocked idle to stop the operation of suction and exhaust valves, whereby the operation of valve drive mechanisms associated with these cylinders is stopped. Thus, in the case of a 6-cylinder engine, for example, the engine operation is stopped with respect to, e.g., three cylinders. In changing the operating state between the cylinder-off state and the cylinder-on state, moreover, the valve drive mechanisms for each cylinder and a fuel supply system (e.g., fuel injection system) are controlled so that they are operated in associated with each other, thereby ensuring normal combustion in the cylinders.
However, the conventional variable-cylinder engine control method is subject to a drawback such that the engine output greatly fluctuates, thereby producing a shock, during the change between the cylinder-off state and the cylinder-on state, or a spark plug smolders.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide an engine control method in which fluctuations of the engine output caused by change between a cylinder-off state and a cylinder-on state can be reduced.
Another object of the present invention is to provide an engine control method in which fluctuations of the engine output caused during transition from tile cylinder-off state to the cylinder-on state can be reduced, in particular.
Still another object of the present invention is to provide an engine control method in which fluctuations of the engine output caused during transition from the cylinder-on state to the cylinder-off state, in particular, and smoldering of a sparking plug can be eliminated.
In order to achieve the above objects, according to the present invention, there is provided an engine control method in which a valve operation in valve drive mechanism associated with at least one specific cylinder is limited to permit a reduction in the number of cylinders, and fuel injection is controlled depending on the operating conditions of the valve drive mechanism, while an engine is being operated in a specific operation region.
According to one aspect of the present invention, the engine control method comprises: previously injecting fuel into the specific cylinder, then restoring the valve operation in the valve drive mechanism associated with the specific cylinder, and effecting normal combustion in the specific cylinder on restoring the valve operation, during the change of the operating state of the engine from a cylinder-off state to a cylinder-on state and in the case where the engine is in a rapid-acceleration operation region; and restoring the valve operation in the valve drive mechanism associated with the specific cylinder and then starting fuel injection into the specific cylinder, during the cha
Kawabe Takashi
Murakami Nobuaki
Argenbright Tony M.
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
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