Toyota Jidosha Kabushiki Kaisha

Fujitsu Ten Limited

Fijitsu Ten Limited

Hirofumi Yamasaki

Takao Fukuma

Keisuke Tsukamoto

Toshio Takaoka

Kiyoshi Yagi

Tatsuo Teratani

Minoru Takahashi

Junji Takahashi

Jiro Masuda

Masumi Nagasaka

Masaki Hitotsuya

Takeshi Tachibana

Akira Miyazaki

A lean burn internal combustion engine has a basic fuel injection amount calculated and multiplied by a lean correction factor, the resulting amount controls the air fuel ratio of the engine. The lean correction multiplied by factor is calculated from a first map based on intake pressure and engine speed. However, when the degree of opening of the throttle valve is larger than a predetermined value, a second correction map based on the degree of opening of the throttle valve and engine speed is used to obtain the lean correction factor. When the second correction map is employed, an ignition timing map based on the degree of opening of the throttle valve and engine speed is used to obtain an ignition timing; instead of the usual ignition timing, based on intake pressure and engine speed.

Lean burn internal combustion engine

An air-fuel ratio control device for an engine, by which the air-fuel ratio of the air-fuel mixture supplied to the engine is changed. The device set the air-fuel ratio to a lean mixture when the engine load is lower than a set load value and predetermined set speed, and when the engine load become higher than the set load value, or the engine speed exceeds the set speed, the device switches the air-fuel ratio from a lean mixture to a rich mixture to obtain higher engine output. The set load value is varied in accordance with the engine speed such that it is reduced as the engine speed is increased.

Air-fuel ratio control device for an engine

An air-fuel ratio control device for an vehicle engine, by which the air-fuel ratio of the air-fuel mixture supplied to a vehicle engine is changed. The device sets the air-fuel ratio to a lean mixture when the engine coolant temperature is higher than a predetermined value and the vehicle speed is higher than a value determined by a time elapsed after engine startup.

Air-fuel ratio control device for a vehicle engine

An air-fuel ratio control device comprising a memory which stores the relationship between the degree of opening of the throttle valve and the absolute pressure in the intake passage, which pressure is produced when the engine is in a cruising state. When a difference between the blunt value of the actual absolute pressure in the intake passage and the absolute pressure stored in the memory exceeds a fixed value, the air-fuel mixture is changed from the mixture for the stoichiometric air-fuel ratio to a lean mixture.

Air-fuel ratio control device of an internal combustion engine

A lean burn internal combustion engine wherein a basic fuel amount is calculated from a map based on the intake pressure and the engine speed, and a lean correction factor, which is multiplied by the basic fuel amount, is calculated from a lean map based on the intake pressure and engine speed. A second lean map based on the throttle opening and engine speed is provided for obtaining a lean correction factor when the degree of opening of the throttle valve is larger than a predetermined value. A lean sensor is provided for obtaining a signal indicating the air fuel ratio for carrying out a feedback control. The lean sensor is provided with a heater for controlling the temperature of the sensing element of the heater. A basic map for the heater power, which is based on the intake pressure and engine speed, is provided, and a correction map for the heater power is provided for reducing the heater power from the value obtained from the basic map when the lean map based on the intake pressure and engine speed is employed for obtaining the lean air-fuel mixture, to prevent thermal damage to the sensor element.

In an internal combustion engine, a vibration period and a vibration amplitude are measured and the detected vibration period is compared with a natural vibration period prestored in accordance with a driving condition of the vehicle. If the detected vibration period is equal to the natural vibration period under the driving condition at which the vibration period is detected, it is determined that surging due to a torque variation of the engine is occurring. In this condition, the torque variation is controlled to be a predetermined value by increasing an air-fuel ratio or decreasing an amount of EGR when the detected vibration amplitude is smaller than a predetermined value, and the torque variation is controlled to a predetermined value by decreasing an air-fuel ratio or increasing an amount of EGR when the detected vibration amplitude is larger than a predetermined value, and accordingly, the driveability and emission rate are improved.

Method and apparatus for controlling torque variations in an internal

A device for determining an activated condition of the oxygen sensor of a lean sensor for an electric-controlled fuel injection internal combustion engine. When the engine is under a fuel cut operation, the output level from the oxygen sensor is compared with a first predetermined threshold level or with a second predetermined threshold level which is lower than the first threshold level. A determination of the activated condition of the oxygen sensor is obtained when the output level from the oxygen once exceeds the higher first level, or when the output level from the oxygen sensor consecutively exceeds the higher first level twice, whereby a positive and quick determination of the activated condition of the oxygen sensor can be obtained.

Device for determining activated condition of an oxygen sensor

A constant speed cruise control system of duty ratio control type for approximating an actual car speed to a stored target car speed, by on/off control of a control valve of an actuator to adjust the throttle valve opening degree by an output duty ratio D obtained from a control line having a gradient showing a conversion characteristic of car speed and duty ratio. The system has a controller in which

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Toyota, Japan

Hirofumi Yamasaki