Nissan Motor Company Limited

Victor Company of Japan, Limited

Other

Hiroshi Katoh

Ritsuo Sato

Masahiko Yuya

Takahisa Koseki

Shigeaki Kakizaki

Rie Takatsuto

Hajime Hosoya

Mikio Matsumoto

Satoshi Nakazawa

Mitsuo Fujita

Takane Hayashi

Hiromi Taguchi

Shoji Kikunaga

Hiroyuki Osaki

An air-fuel ratio feedback control range is enlarged to improve exhaust purification performance and output stability. In one aspect, an air-fuel ratio control apparatus of an internal combustion engine comprises an air-fuel ratio sensor capable of detecting an air-fuel ratio across both lean and rich ranges with a theoretical air-fuel ratio interposed therebetween. Feedback control is performed so as to bring an actual air-fuel into a target air-fuel ratio at least in a predetermined operational range on the basis of a detected value of the air-fuel ratio sensor. Even in a range where the air-fuel ratio is made richer than the theoretical air-fuel ratio, the target air-fuel ratio is set to be richer, and the air-fuel ratio feedback control may still be executed.

Air-fuel ratio control apparatus and method of internal combustion engine

A diagnostic apparatus for an internal combustion engine. An exhaust purification section includes an exhaust purifier disposed in an exhaust passage of the internal combustion engine, for purifying an exhaust emission, and a purifier activation section configured to control engine operating parameters of the internal combustion engine to promote activation of the exhaust purifier during the internal combustion engine being cold. The diagnostic apparatus is configured to determine a state of the exhaust purifier, to determine a total purifier out emission quantity as a quantity of the exhaust emission exiting the exhaust purifier during the internal combustion engine being cold, in accordance with the state of the exhaust purifier, and to determine normality of the exhaust purification section in accordance with the total purifier out emission quantity.

Diagnostic apparatus for internal combustion engine

A diagnostic apparatus for an internal combustion engine is disclosed herein. In one embodiment, the diagnostic apparatus comprises a catalytic converter and a controller. The catalytic converter is disposed in an exhaust passage of an engine and treats an exhaust gas component in the exhaust gas. The controller is adapted to perform a number of functions. More specifically, the controller is adapted to operate the engine with an engine control parameter to increase catalyst temperature of the catalytic converter during a cold engine condition. The controller is further adapted to calculate a temperature factor indicative to temperature increase of the catalyst based on the engine control parameter. The controller is further adapted to estimate the amount of the exhaust gas component flowing out of the catalytic converter based on the temperature factor. Finally, in one embodiment, the controller is adapted to determine malfunction of the engine operation to increase catalyst temperature of the catalytic converter based on the amount of exhaust gas component flowing out of the catalytic converter. A diagnostic method is also disclosed.

Diagnostic apparatus and diagnostic method for an internal combustion engine

An engine air-fuel ratio control system is configured to use a rich air-fuel ratio immediately after starting an engine such that the air-fuel ratio converge rapidly toward a stoichiometric value and then afterwards start an air-fuel ratio feedback control. Upon determining an air-fuel ratio sensor is active, a stabilization fuel quantity increasing factor that is a component of a target air-fuel ratio revising coefficient is decreased at a higher rate than the rate used before the air-fuel ratio sensor was determined to be active. Air-fuel ratio feedback control is started when the air-fuel ratio corresponds to a stoichiometric air-fuel ratio. After starting air-fuel ratio feedback control, an unburned fuel quantity compensating value is set based on the stabilization fuel quantity increasing factor in effect at that point in time and added to the target air-fuel ratio revising coefficient while, simultaneously, the stabilization fuel quantity increasing factor is set to zero.

Engine air-fuel ratio control system

An engine air-fuel ratio control system is configured to use a rich air-fuel ratio immediately after starting an engine such that the air-fuel ratio converge rapidly toward a stoichiometric value and then afterwards start an air-fuel ratio feedback control. Upon determining an air-fuel ratio sensor is active based on the output of the air-fuel ratio sensor and the amount of time elapsed since an engine was started, a stabilization fuel quantity increasing value that is a component of a target air-fuel ratio revising coefficient is decreased at a higher rate than the rate used before the air-fuel ratio sensor was determined to be active. During the same period, an air-fuel ratio feedback revising coefficient is held at a reference value. After the output of the air-fuel ratio sensor reaches a value corresponding to a stoichiometric air-fuel ratio, an air-fuel ratio feedback control is started.

An engine air-fuel ratio control system uses a rich air-fuel ratio immediately after starting an engine to converge rapidly the air-fuel ratio toward a stoichiometric value. Upon determining an air-fuel ratio sensor is active, a stabilization fuel quantity increasing factor of a target air-fuel ratio revising coefficient decreases at a higher rate than before the air-fuel ratio sensor was active. Air-fuel ratio feedback control starts when the air-fuel ratio corresponds to a stoichiometric air-fuel ratio. Afterwards, when either air-fuel ratio feedback control starts or the engine enters a high rotational speed/high load region that operates using a rich air-fuel ratio, whichever occurs first, an unburned fuel quantity compensating value is set based on the stabilization fuel quantity increasing factor in effect at that point in time and added to the target air-fuel ratio revising coefficient while, simultaneously, the stabilization fuel quantity increasing factor is set to zero.

A spark ignition engine () has a fuel injector () in an intake port (). An engine rotation speed sensor () detects the rotation speed of the engine (). The controller () determines the target fuel injection amount of the fuel injector () during startup of the engine () by correcting the basic injection amount in response to the trend in the variation in the engine rotation speed. When the rotation speed of the engine () decreases, the controller () sets the target fuel injection amount to be smaller than when the rotation speed of the engine () is increasing at an identical rotation speed. As a result, effects on the air-fuel ratio related to wall flow relative to fluctuations in the rotation speed of the engine () are eliminated and the control accuracy of the air-fuel ratio of the engine () is improved.

Engine fuel injection control device

A spark ignition internal combustion engine () performs ignition within a fixed ignition crank angle range. The operation control device comprises a programmable controller () and a unit crank angle sensor () outputting a unit crank angle signal on each unit crank angle. The controller () calculates the engine rotation speed based on the unit crank angle signals (S). By preventing the calculation of the engine rotation speed based on the unit crank angle signals detected in the ignition crank angle range, errors in the calculation of the engine rotation speed resulting from engine ignition noise are eliminated and a precise engine rotation speed is obtained.

Detection of engine rotation speed in spark ignition internal combustion engine

A fuel injector ( ) injects fuel to generate an air-fuel mixture that is burnt in the engine ( ), and a sensor ( ) detects an air-fuel ratio of the air-fuel mixture from an exhaust gas composition of the engine ( ). A controller ( ) calculates a dead time representing a lag between the air-fuel ratio variation of the air-fuel mixture and the air-fuel ratio variation detected by the sensor ( ), and calculates an estimated state quantity by applying a dead time compensation according to Smith method and a disturbance compensation to the air-fuel ratio detected by the sensor ( ). By determining an air-fuel ratio feedback correction amount based on the estimated state quantity applying a sliding mode control process, the response and stability of air-fuel ratio control is improved.

Engine air-fuel ratio control

A state quantity &sgr;(n) of a switching function is calculated based on a predetermined target air-fuel ratio TGABF, a detected air-fuel ratio AFSAF detected by a sensor ( ), and a state equation derived from a transfer function Geng(q) of a secondary discrete system, representing the correlation between an air-fuel ratio of an air fuel mixture in a combustion chamber ( A) and the detected air-fuel ratio (S ). The air-fuel ratio is feedback corrected by applying a sliding mode control process based on the difference between the target air-fuel ratio TGABF and the detected air-fuel ratio AFSAF, and the state quantity &sgr;(n) (S -S ). The response and robustness of the air-fuel ratio control are enhanced by using a physical model of the secondary discrete system.

The startup time of an engine is shortened by performing initial fuel injection after the start of cranking on a cylinder undergoing an intake stroke and a cylinder undergoing an exhaust stroke. After the initial fuel injection, HC emissions are suppressed by performing fuel injection in cylinders undergoing an exhaust stroke. Furthermore when it is determined that initial combustion has not occurred after the initial fuel injection, an additional injection is performed on the cylinder undergoing an intake stroke. In this manner, it is possible to minimize increases in the startup time and adverse effects on exhaust emissions.

Fuel injection control for internal combustion engine

In order to improve the control characteristics for ignition timing during transient operating conditions including engine startup, during engine transient operating conditions, a controller ( ) sets an advance limit ADVLMT restricting the maximum value of the ignition timing advance to a limit ADMLMTS which is a large value when compared to the value for steady-state operating conditions. Furthermore during transient operating conditions, the dwell angle TDWLLB is also increased and the correlation of the ignition timing control with respect to a suitable ignition timing is improved.

Ignition timing control device for internal combustion engine

In a four-stroke cycle multi-cylinder internal combustion engine ( ), a controller ( ) controls fuel injectors ( ) to inject fuel for the cylinder (&num; ) in the intake stroke immediately after the first cylinder-stroke identification is performed. Due to this fuel injection control, the fuel is necessarily injected before the first combustion occasion at any cylinder ( ), cylinder dependent fluctuation of air-fuel ratio when the first combustion takes place in the respective cylinders ( ) is prevented. Further, in a predetermined low temperature range, the controller ( ) controls fuel injectors ( ) to perform a preliminary fuel injection for all the cylinders ( ) before the first cylinder-stroke identification, so the fuel amount required for the first combustion is ensured for all the cylinders ( ).

Fuel injection control for start-up of internal combustion engine

A fuel injection control device for an internal combustion engine is provided with a controller functions to command the fuel injectors for a cylinder in the exhaust stroke and for a cylinder in the intake stroke to simultaneously perform a primary fuel injection, when the first cylinder-stroke identification is performed, if the engine temperature is higher than a predetermined temperature. The controller further functions to command the fuel injector only for a cylinder in the intake stroke to perform a primary fuel injection, when the first cylinder-stroke identification is performed, if the engine temperature is less than the predetermined temperature. Thus the startup time of the engine is shortened and the stability of startup is ensured at normal, low, or extremely low temperatures.

An internal combustion engine ( ) provided with a starter motor sequentially performs combustion of fuel in a plurality of cylinders (&num;1-&num;4). Each cylinder is provided with an intake port ( ) and a fuel injector ( ) to inject fuel in the intake port ( ) and repeatedly performs an intake stroke, compression stroke, expansion stroke and an exhaust stroke. A sensor ( ) generates a signal identifying a cylinder in a specific position in a specific stroke and the controller ( ) executes a cylinder-stroke identification in response to the signal. Upon the first execution of the cylinder-stroke identification when the engine is cranked, a fuel injection is performed for a cylinder in the intake stroke and for a cylinder in the exhaust stroke simultaneously so as to ensure the fuel supply amount required for the first combustion in each cylinder.

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Yokohama, Japan

Hiroshi Katoh