Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-09-03
2001-07-10
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S480000, C123S481000, C701S113000
Reexamination Certificate
active
06257207
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to apparatus and method for controlling startup of an internal combustion engine including a plurality of cylinders.
BACKGROUND OF THE INVENTION
In internal combustion engines including a plurality of cylinders and a fuel injector valve for each of the cylinders, for example, a multi-point fuel injection (MPI) engine with a fuel injector valve provided at an intake port of each cylinder, and an in-cylinder injection type internal combustion engine with a fuel injector valve for injecting fuel directly into a combustion chamber of each cylinder, an electronic control unit (ECU) operates to detect the start of cranking of the engine upon receipt of an ON signal from a cranking switch, and then to carry out cylinder identification based on signals received from a crank angle sensor and others. Once the cylinder identification is completed, the ECU drives the fuel injector valve of each cylinder with suitable timing so as to start the engine. In this operation, the ECU sets the driving period or duration of the fuel injector valve so that the amount of fuel ejected from the fuel injector valve during engine startup is larger than that ejected while the engine is idling after warm-up thereof. The amount of fuel ejected from the fuel injector valve during engine startup is relatively large for the reason as follows: where the engine is started in the cold state, and vaporization of the fuel injected into the cylinder is delayed due to a low temperature within the cylinder, for example, a sufficient amount of fuel required for combustion needs to be present around the spark plug so as to fire an air-fuel mixture without fail.
However, if the amount of the fuel is relatively large during startup of the engine as described above, the fuel injection amount per cylinder is increased, thus causing excessive racing of the engine upon combustion, or overshoot of the engine speed. Also, since the total amount of the fuel injected into the internal combustion engine as a whole is increased during startup of the engine, the fuel efficiency may be lowered, and exhaust gas characteristics may deteriorate due to increased unburned fuel components that were not used for combustion and that were eventually dispelled in exhaust gas.
As disclosed in laid-open Japanese Patent Publication No. 10-54272, for example where the water temperature is equal to or lower than a predetermined level after completion of cylinder identification, the fuel injection is halted for a period of time corresponding to two strokes, so that the temperature within the combustion chamber is increased due to a compression effect of the internal combustion engine, and the fuel injector valves are subsequently actuated.
The technique disclosed in the above publication, wherein the fuel injection is stopped for a period of two strokes after cylinder identification is completed, is advantageous in terms of the fuel efficiency and exhaust gas characteristics, as compared with the known technique of increasing the fuel amount. It is, however, difficult to achieve the desired temperature in the combustion chamber by utilizing the compression effect of the internal combustion engine, and the amount of the fuel injected after stopping the fuel injection for a period of two strokes must be determined taking account of the case where the temperature in the combustion chamber was not sufficiently increased, as in the known method of increasing the fuel amount. Also, since the fuel is injected into all of the cylinders in a specific sequence after a halt of the fuel injection, the total amount of fuel injection in the internal combustion chamber as a whole tends to be large during engine startup. Thus, there is a plenty of room for improvements in the above-described known methods, which are to be made for suppressing overshoot of the engine speed, and deterioration of exhaust gas characteristics and fuel efficiency.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a startup control apparatus of an internal combustion engine which can overcome the above and other shortcomings of conventional apparatuses and that can suppress overshoot of the engine speed, and avoid deterioration of exhaust gas characteristics and fuel efficiency.
To accomplish the above and other objects, the present invention provides a startup control apparatus of an internal combustion engine, which comprises a plurality of cylinders, a plurality of fuel injector valves respectively provided for the plurality of cylinders, and a control unit comprising a fuel injected cylinder limiting device that stops driving of at least one of the fuel injector valves that are timed to inject fuel into the cylinders, during startup of the internal combustion engine.
With the above arrangement, the total amount of the fuel injected into all of the cylinders during startup of the internal combustion engine can be reduced, thereby suppressing overshoot of engine rotation or engine speed, while assuring improved exhaust gas characteristics and fuel efficiency.
In one preferred form of the startup control apparatus as described above, the control unit further comprises an engine starting capability determining device that determines whether the engine can be successfully started even if driving of at least one of the fuel injector valves in fuel injection timing is stopped during startup of the engine, and the control unit permits the fuel injected cylinder limiting device to be activated when the engine starting capability determining device determines that the engine can be successfully started. With this arrangement, the internal combustion engine can be smoothly started with high reliability.
The startup control apparatus as described just above may further include a temperature detecting device that detects a temperature of the engine. In this case, the engine starting capability determining device determines that the engine cannot be successfully started if driving of at least one of the fuel injector valves in fuel injection timing is stopped during startup of the engine, when the temperature detected by the temperature detecting device is lower than a first predetermined temperature. With this arrangement, the fuel injected cylinder limiting device is actuated based on the result of a determination by the engine starting capability determining device, and therefore the internal combustion engine can be smoothly started with high stability and reliability.
In the above case, the temperature detecting device preferably takes the form of a water temperature sensor provided on a main body of the engine and adapted to detect a coolant temperature of the engine, or an ambient temperature sensor that detects an ambient temperature, and the engine starting capability determining device determines whether the engine can be successfully started, based on the outputs of these sensors.
In the startup control apparatus including the temperature detecting device as described above, the control unit may preferably stop operating the fuel injected cylinder limiting device when the temperature detected by the temperature detecting device is higher than a second predetermine temperature that is set to be higher than the first predetermined temperature. Thus, the engine can be started with high stability.
In the above preferred form of the invention, the startup control apparatus may preferably include an engine speed determining device that determines whether the rotating speed of the internal combustion engine reaches a predetermined speed, and the control unit may include a startup control device that causes the fuel injector valves to sequentially inject the fuel into the respective cylinders during engine startup. In this case, the control unit activates the startup control device when the engine speed determining device determines that the rotating speed of the engine does not reach the predetermined speed after the fuel injected cylinder limiting device is activated. Thus, the engine can be started wit
Hoshiba Yoshiyuki
Inui Toshio
Miyamoto Katsuhiko
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
Vo Hieu T.
Yuen Henry C.
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