Internal-combustion engines – Combustion chamber means having fuel injection only – Combustible mixture stratification means
Reexamination Certificate
2000-09-08
2002-06-25
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Combustion chamber means having fuel injection only
Combustible mixture stratification means
C060S285000, C123S300000
Reexamination Certificate
active
06408816
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to control apparatus and method for a direct-injection spark-ignition internal combustion engine.
b) Description of the Related Art
In recent years, internal combustion engines have been known in each of which fuel is injected directly into a combustion chamber of a corresponding engine cylinder, for example, a fuel combustion (so-called, a homogeneous combustion) is performed in a state wherein fuel is, under a normal driving condition, injected during a suction stroke (so that the injected fuel is diffused homogeneously over the whole combustion chamber) and another fuel combustion (so-called, a stratified lean combustion) at an extremely thin air-fuel ratio placed in a vicinity to a lean limit is performed in a state wherein fuel is injected directly into the combustion chamber during a compression stroke, under a predetermined driving condition, (a low-engine-speed-and-low-engine-load condition) so that a stratified air-mixture fuel is formed which is constituted by an air-mixture fuel of a combustible mixture ratio ignitable about its spark plug of the corresponding combustion chamber. This type of internal combustion engine is called a direct-injection spark-ignition internal combustion engine (refer to a Japanese Patent Application First Publication No. Showa 62-191622 published on Aug. 22, 1987 and a Japanese Patent Application First Publication No. Heisei 2-169834 published on Jun. 29, 1990).
SUMMARY OF THE INVENTION
A Japanese Patent Application First Publication No. Heisei 10-169488 published on Jun. 23, 1998 exemplifies a first previously proposed direct-injection spark-ignition internal combustion engine in which, during an engine operation from a cold start of the engine to a warm-up state, a local air-fuel ratio of a stratified air-mixture fuel in an inner space of the combustion chamber surrounding the spark plug is enriched so that a local insufficiency in air quantity is created, imperfectly combusted matter (CO) and part of fuel which remains unburned are reacted with an extra oxygen after a main combustion to raise exhaust temperature, thus an activation of an exhaust purification catalytic converter being promoted.
An assignee to which the present invention is to be assigned filed as an applicant Japanese Patent Application No. Heisei 11-46612 in Japan on Feb. 24, 1999. This Japanese Patent Application does not form prior art under 35 U.S.C. 102 and 35 U.S.C 103, and it does not form the state of the art under Article 54(2) EPC.
This Japanese Patent Application discloses a second previously proposed direct-injection spark-ignition internal combustion engine in which, to solve a problem of an increased exhaust quantity of an un-combusted fuel (HC) due to an unstable ignition of fuel in the above-described direct-injection spark-ignition internal combustion engine, the stratified air-mixture fuel is formed with the air-fuel ratio enriched locally around the spark plug and a sprayed fuel is sufficiently atomized through a retardation of an ignition timing at a later time than the normal stratified lean combustion so that a stable ignition-and-combustion is advanced, thus an activation of the exhaust purification catalytic converter being promoted and an exhaust of the un-combusted fuel (HC) being suppressed.
Furthermore, the above-described Japanese Patent Application discloses a stratified air-mixture fuel formed in an inner space of the combustion chamber surrounding the spark plug locally with the air-fuel ratio enriched and with the fuel injected during the compression stroke, the air-mixture fuel being formed over the whole combustion chamber with the fuel injected also during the suction stroke so that the air-mixture fuel is formed in which the air-mixture fuel over the whole combustion chamber is lean and a stratified stoichiometric combustion in which an average air-fuel ratio in this combustion chamber is set to indicate an approximately stoichiometric air-fuel ratio, this CO being developed due to a main combustion of the stratified air-mixture fuel and its fire flame being propagated over the whole corner of the combustion chamber by means of the enriched air-mixture fuel after the main combustion. Consequently, a more speedy re-combustion of CO can be achieved.
It is an object of the present invention is to provide control apparatus and method for a direct-injection spark-ignition internal combustion engine in which the above-described stratified stoichiometric combustion can normally and more favorably be carried out.
According to a first aspect of the present invention, there is provided a control apparatus for a direct injection spark-ignition internal combustion engine, comprising: a first controlling section that performs a stratified combustion to raise an exhaust temperature under a condition prior to a completion of an engine warm-up, the stratified combustion being provided with a lean air-fuel mixture formed over a whole combustion chamber through a fuel injection at a suction stroke and a rich air-fuel mixture formed in an inner space surrounding a spark plug of the combustion chamber through a fuel injection at a compression stroke; and a second controlling section that corrects a fuel injection quantity of the fuel injection at the suction stroke and a fuel injection quantity of the fuel injection at the compression stroke by means of a feedback correction coefficient so that an average air-fuel ratio over the whole combustion chamber is controlled to be a predetermined target air-fuel ratio, wherein one of the fuel injections whose fuel injection quantity is larger than the other fuel injection is corrected in both increase and decrease directions by means of the feedback correction coefficient, and wherein the other fuel injection is corrected only in an increase direction by means of the feedback correction coefficient.
According to a second aspect of the present invention, there is provided a control apparatus for a direct-injection spark-ignition internal combustion engine, comprising: a fuel injector that injects fuel directly into a combustion chamber; an air-fuel ratio sensor provided in an exhaust passage of the engine; and a controller that is programmed to: set a feedback correction coefficient on the basis of an air-fuel ratio detected by the air-fuel ratio sensor in such a manner that the air-fuel ratio indicates a predetermined target air-fuel ratio; perform a stratified combustion to raise an exhaust temperature under a predetermined condition, the stratified combustion being provided with a lean air-fuel mixture formed over the whole combustion chamber through a fuel injection at a suction stroke and a rich air-fuel mixture formed in an inner space surrounding the spark plug through a fuel injection at a compression stroke; and correct a fuel injection quantity of the fuel injection whose fuel injection quantity is larger than the other fuel injection by means of the feedback correction coefficient in both increase and decrease directions, and correct a fuel injection quantity of the other fuel injection by means of the feedback correction coefficient only in an increase direction.
According to a third aspect of the present invention, there is provided a control apparatus for a direct-injection spark-ignition internal combustion engine, comprising: a first controlling section that performs a stratified combustion to raise an exhaust temperature under a condition prior to a completion of an engine warm-up, the stratified combustion being provided with a lean air-fuel mixture formed over a whole combustion chamber through a fuel injection at a suction stroke and a rich air-fuel mixture formed in an inner space surrounding a spark plug of the combustion chamber through a fuel injection at a compression stroke; and a second controlling section that corrects a fuel injection quantity of the fuel injection whose fuel injection quantity is larger than the other fuel injection quantity by means of a feedback correction coefficient so that an
Nishizawa Kimiyoshi
Tomita Masayuki
Argenbright Tony M.
Nissan Motor Co,. Ltd.
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