Internal-combustion engines – Engine speed regulator – Idle speed control
Patent
1994-03-14
1995-01-17
Wolfe, Willis R.
Internal-combustion engines
Engine speed regulator
Idle speed control
123585, F02D 4116, F02M 2306
Patent
active
053817680
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an air-fuel ratio control apparatus of an internal combustion engine, which causes the engine selectively to effect the so-called lean or rich combustion as required, to thereby improve the exhaust gas characteristics and Fuel cost performance and increase the engine output as required, and more particularly, to an air-fuel ratio control apparatus capable of preventing a sudden change of the engine output which is liable to be caused when the air-fuel ratio is changed for switching between the lean combustion and rich combustion.
BACKGROUND ART
In order to improve the exhaust gas characteristics and fuel cost performance of a motor vehicle, it is known to control the air-fuel ratio of an air-fuel mixture to be supplied to an internal combustion engine, to have a value on the fuel-lean side of a theoretical air-fuel ratio, thereby allowing the engine to be operated in a lean-combustion mode. If the engine is continually operated in the lean-combustion mode, however, the engine output will be insufficient in some specific operating states (e.g., sudden-departure operating state and sudden-acceleration operating state). Conventionally, therefore, the air-fuel ratio is adjusted to the theoretical air-fuel ratio or its near value (hereinafter referred to as near theoretical air-fuel ratio) to effect rich-combustion operation in the specific operating states of the engine.
According to the conventional air-fuel ratio control, however, the amount of fuel supply to the engine sometimes may undergo a sudden change when the air-fuel ratio is changed between the near theoretical air-fuel ratio and an air-fuel ratio on the fuel-lean side thereof, in order to switch the combustion mode between rich combustion and lean combustion. In such a case, the engine output, which depends on the fuel supply amount, thermal efficiency of the engine, etc., changes suddenly. For example, when the accelerator pedal is released from a driver's stepping operation so that an acceleration operating state (one of the specific operating states) is finished, conventional air-fuel ratio control apparatuses operate to reduce the fuel supply amount rapidly, in order to restore the air-fuel ratio to a value on the fuel-lean side. As a result, the engine output lowers suddenly. If the engine output undergoes such a sudden change, a torque shock is caused in the engine, thus retarding the drivability.
Disclosed in Published Unexamined Japanese Patent Application No. 2-267340 is an air-fuel ratio control apparatus which, belonging to the aforementioned conventional apparatuses in a broader sense, is so designed that the fuel supply amount is reduced during the transition to the lean operating state.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide an air-fuel ratio control apparatus of an internal combustion engine, capable of preventing a disagreeable torque shock which is liable to be caused when the air-fuel ratio is changed between a near theoretical air-fuel ratio value and a value on the fuel-lean side thereof, in order to cause the engine selectively to undergo either rich combustion or lean combustion.
In order to achieve the above object, according to the present invention, there is provided an air-fuel ratio control apparatus of an internal combustion engine, which controls the air-fuel ratio of an air-fuel mixture to be supplied to an engine so that the air-fuel ratio is adjusted to a first air-fuel ratio approximate to a theoretical air-fuel ratio when the engine is in a specific operating state, and that the air-fuel ratio is adjusted to a second air-fuel ratio on the fuel-lean side of the first air-fuel ratio when the engine is in any other operating state than the specific operating state. This air-fuel ratio control apparatus comprises: a main bypass line bypassing a throttle valve in the middle of a suction passage of the engine and having both ends thereof communicated with the suction passage; a sub-bypass line bypassing the throttle valve and h
REFERENCES:
patent: 4617890 (1986-10-01), Kobayashi et al.
patent: 4700676 (1987-10-01), Harashima et al.
patent: 4700679 (1987-10-01), Otobe et al.
patent: 4721082 (1988-01-01), Hibino et al.
patent: 4873955 (1989-10-01), McAuliffe, Jr.
patent: 4986236 (1991-01-01), Kobayashi
patent: 5035217 (1991-07-01), Kako
patent: 5170761 (1992-12-01), Kato et al.
patent: 5172674 (1992-12-01), Horie et al.
Togai Kazuhide
Ueda Katsunori
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
Wolfe Willis R.
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