Nissan Motor Company Limited

Ritsuo Sato

Kimiyoshi Nishizawa

Hiroshi Katoh

Masahiko Yuya

Takahisa Koseki

Kouichi Mori

Mikio Tsuzuki

Hideaki Takahashi

Masaaki Ashida

Fuminori Yamanashi

Yoshinao Ugomori

Hidetoshi Ito

Osamu Matsuno

Shigeaki Kakizaki

Masatomo Kakuyama

Katsuhiro Shibata

Hideharu Ehara

Hajime Oguma

Naoki Kachi

Kiyotaka Baba

Ken Ouchi

Keiji Yakushiji

Kaoru Ikeda

The Rh content by percentage in an HC absorbent catalytic converter provided in an exhaust pipe is greater than the Rh content by percentage in an upstream three-way catalyst. In this way, even when HC which has been temporarily absorbed is emitted in an atmosphere and the exhaust gas becomes rich, the HC absorbent catalytic converter displays improved oxidization and removal of HC due to the high content by percentage of Rh which has a high HC conversion ratio in rich atmospheres. There is no necessity to control the air-fuel ratio to a strongly lean ratio and so HC removal can be improved while maintaining suppression of NOemissions.

Exhaust emission control device

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

The invention comprises at least two independent intake ports connected to a combustion chamber , two intake valves , and two exhaust valves . Upper and lower channels which are defined by a partition wall, and an intake control valve for opening and closing the lower side channel are provided in the interior of the first intake port . An intake control valve for opening and closing the first intake port is also provided. The invention further comprises a controller for controlling the opening and closing of the intake control valves and , and the degree of opening of these intake control valves and is controlled in accordance with the operating conditions.

Engine control apparatus

The invention comprises at least two independent intake ports connected to a combustion chamber , two intake valves , and two exhaust valves . A first fuel injection valve is provided in the first intake port and a second intake control valve is provided for opening and closing the second intake port . When the engine is in the cold condition, the second intake control valve is slightly opened and fuel is injected from the first fuel injection valve . Air-fuel mixture from the first intake port and a smaller amount of fresh air from the second intake port are introduced &lsqb;into the combustion chamber&rsqb;, and the overall air-fuel ratio inside the combustion chamber is controlled to become slightly lean.

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.

A controller ( ) controls an air-fuel ratio of an engine ( ) so that an oxygen storage amount of a catalyst ( ) provided in an exhaust passage ( ) is maintained constant. At this time, the controller ( ) computes or estimates the oxygen storage amount separately for a first amount and a second amount, where the first amount is estimated based on a relationship between the first and second amount. The controller ( ) controls the air/fuel ratio based on the estimated first amount.

Engine exhaust purification device

A controller controls an air-fuel ratio of an engine to maintain the oxygen storage amount of a catalyst provided in an exhaust passage at a predetermined amount. At this time, the controller first estimates the initial value of the oxygen storage amount based on the catalyst temperature on engine startup, and then computes an oxygen storage characteristic using this estimated initial value. In this way, the oxygen storage amount can be precisely computed even immediately after engine startup, and the conversion efficiency of the catalyst is maintained at a high level.

A three-way catalytic converter and a combined catalytic-hydrocarbon adsorbent are arranged in an exhaust manifold of an engine . The three-way catalytic converter and the combined catalytic-hydrocarbon adsorbent are arranged adjacent to each other in series from an upstream. A pulsing stream of the exhaust gas is kept strong at the point where combined catalytic-hydrocarbon adsorbents are arranged. Thus, hydrocarbons desorbed from the combined catalytic-hydrocarbon adsorbents are strongly affected by an action of a pulsing stream of the exhaust gas, and hydrocarbons desorbed from the combined catalytic-hydrocarbon adsorbent flow backward in the direction of the three-way catalytic converter . Consequently, hydrocarbons desorbed from the combined catalytic-hydrocarbon adsorbent are given a chance to contact with the three-way catalytic converter again, and are oxidized with the three-way catalytic converter

Exhaust gas purification apparatus in combustion engine

The Rh content by percentage in an HC absorbent catalytic converter provided in an exhaust pipe is greater than the Rh content by percentage in an upstream three-way catalyst. In this way, even when HC which has been temporarily absorbed is emitted in an atmosphere and the exhaust gas becomes rich, the HC absorbent catalytic converter displays improved oxidization and removal of HC due to the high content by percentage of Rh which has a high HC conversion ratio in rich atmospheres. There is no necessity to control the air-fuel ratio to a strongly lean ratio and so HC removal can be improved while maintaining suppression of NO,emissions.

A plurality of catalysts (,), (,) are disposed in an engine exhaust passage (,). At least the catalyst disposed downstream of these catalysts comprises a multi-layered catalyst (,) which is covered in a catalyst layer (,) on the surface and an HC absorbent layer (,) on an inner layer with respect to a catalyst carrier (,). A ratio of the downstream multi-layered catalyst (,) (catalyst heat capacity/catalyst surface area) is set so that it is greater than the same ratio for the upstream catalyst (,). In this way, temperature increase in the upstream catalyst (,) is advanced, the temperature gradient in the downstream catalyst (,) is increased and temperature rises in the HC absorbent layer are reduced. As a result, the HC emission period approximates the activation period of the catalyst layer (,). In this way, during low temperature vehicle operation, it is possible to synchronize the timing of HC emission by the HC absorbent layer and catalyst activation and therefore to achieve extreme reductions in HC emitted to the outside atmosphere.

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Yokohama, Japan

Ritsuo Sato