Mitsubishi Jidosha Kogyo Kabushiki Kaisha

Shiro Kumagai

Tateo Kume

Reijiro Komagome

Katsuo Akishino

Michiyasu Yoshida

Yoshiaki Kodama

Takehisa Fujita

Masaki Nishizawa

Seiji Ishida

Kazuo Koga

Katsuyuki Maeda

Nobuyuki Yasuda

An exhaust gas purifying apparatus is provided which includes a three way catalyst provided in an exhaust pipe of an internal combustion engine; and a NOx adsorption/reduction catalyst provided in the exhaust pipe to be located downstream of the three way catalyst. Nickel serving as a catalyst source is loaded on an alumina support layer of the NOx adsorption/reduction catalyst. When the engine operates with a fuel-rich air/fuel mixture at a relatively small air-fuel ratio, a reducing atmosphere is formed around the NOx catalyst, and the reaction to convert NiO into NiS occurs, thereby to consume H S. As a result, consumption of SO proceeds, and the reaction to convert BaSO as an oxidized product of sulfur deposited on the NOx catalyst into BaCO as an NOx adsorbent is accelerated in an oxidizing atmosphere, thereby resuming the purifying capability of the NOx catalyst.

Exhaust gas purifying apparatus

An air/fuel ratio control system is provided for use with an internal combustion engine. The system includes a first air/fuel ratio detector arranged on an upstream side of a catalytic converter so as to detect the air/fuel ratio of the engine from components of exhaust gas, a second air/fuel ratio detector arranged in the exhaust system and having a detection response speed slower than the first air/fuel ratio detector, a device for controlling the air/fuel ratio of the engine on the basis of results of a comparison between a detection value from the first air/fuel ratio detector and a predetermined first reference value, a device for effecting a correction to the control of the air/fuel ratio by the air/fuel ratio control device on the basis of results of a comparison between a detection value from the second air/fuel ratio detector and a predetermined second reference value, and a device for shifting the second reference value to a lean air/fuel ratio side in a specific operation state of the engine.

Air/fuel ratio control system for internal combustion engine

An air/fuel ratio control system is provided for use with an internal combustion engine. The system includes an air/fuel ratio detector arranged on an upstream side of a catalytic converter so as to detect the air/fuel ratio of the internal combustion engine from components of exhaust gas, a device for controlling the air/fuel ratio of the internal combustion engine on the basis of results of a comparison between a detection value from the air/fuel ratio detector and a predetermined reference value; and a device for shifting the reference value to a lean air/fuel ratio side in a specific operation state of the internal combustion engine.

Air/fuel ratio control system for an internal combustion engine

An apparatus is provided for controlling the air/fuel ratio of an internal combustion engine. The apparatus includes a sensor disposed in an exhaust system for detecting components of exhaust gas, a device for compulsorily changing the air/fuel ratio, another device for setting a first target value which gives a target air/fuel ratio to be compared with each output from the sensor, and a further device for controlling the air/fuel ratio, which has been compulsorily changed by the air/fuel ratio changing device, on the basis of the result of a comparison between the output and the first target value, whereby the average air/fuel ratio may be controlled to the first target air/fuel ratio. The first target value setting device includes an element for modifying the first target value to a second target value, which gives a leaner air/fuel ratio, in a specific operation state of the engine.

Apparatus for controlling air/fuel ratio of internal combustion engine

An air/fuel ratio control system is provided for an internal combustion engine. The system includes first and second oxygen density sensors, an air/fuel ratio control device and a standard-value changing device. The first oxygen density sensor is arranged on an upstream side of a catalytic converter, while the second oxygen density sensor is provided either inside or on a downstream side of the catalytic converter. The air/fuel control device controls the air/fuel ratio of the internal combustion engine on the basis of results of comparison between a detection value from one of the first and second oxygen density sensors and a predetermined standard value. The standard-value changing device changes the standard value on the basis of outputs from the first and second oxygen density sensors.

A temperature control apparatus for at least two catalytic converters which are connected in series in an exhaust passage of an internal combustion engine mounted on a vehicle. A by-pass is disposed in parallel with a first catalytic converter which is connected in the vicinity of the engine. Valve drive means serves to drive a control valve for controlling the ratio between the amounts of exhaust gas introduced into the first catalytic converter and the by-pass. Control means serves to calculate the deviation between a reference value and a temperature value, which is associated with the catalyst-bed temperature of the first catalytic converter, and is detected by temperature detecting means, and to deliver a drive signal to the valve drive means in accordance with the deviation, thereby controlling the opening of the control valve. Immediately after the start of the engine, therefore, the catalyst-bed temperature of the first catalytic converter rises to the reference temperature value for an optimum purifying efficiency. Thereafter, the bed temperature is kept constantly in the vicinity of the reference value.

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Kyoto, Japan

Shiro Kumagai