Honda Giken Kogyo Kabushiki Kaisha

Minoru Muroya

Masahiko Asakura

Tomohiko Kawanabe

Noritaka Kushida

Takanori Shiina

Katsuhiko Kimura

Yasunari Seki

Hiroshi Hasebe

Shinichi Kubota

Yukihiro Matsumoto

Shin'ichi Kubota

Masahiro Ueda

Kouji Matsuura

An air-fuel ratio control system for an internal combustion engine mounted on a vehicle with a transmission, including an oxygen concentration sensor producing an output signal whose level is substantially proportional to an oxygen concentration of the exhaust gas, effects a feedback control of the air-fuel ratio of mixture to be supplied to the engine toward a target value determined on the basis of various parameters of the engine operation and corrected in response to a magnitude of atmospheric pressure, so that the higher a shift position of the transmission gear is, the leaner the target air-fuel ratio becomes. Thus, the fuel consumption in a light load operating condition of the engine is decreased and the driveability of the vehicle is improved.

Air-fuel ratio control system for an internal combustion engine with an

An apparatus for sensing the concentration of oxygen in a gas such as engine exhaust gas includes an oxygen concentration sensor formed of an oxygen pump element and a sensor cell element, each based on a solid electrolytic member formed of a material such as ZrO.sub.2, and is provided with a limiter circuit which functions to reduce the level of current supplied to the oxygen pump element when a voltage produced by the sensor cell element indicates that this current level is such as to produce a 'blackening' phenomenon whereby deterioration of the oxygen pump element will occur and oxygen concentration sensing reliability will be lowered. The apparatus also includes a delay circuit which functions such that a reduction of the oxygen pump element current level is delayed by a predetermined time interval, after an increase of the sensor cell element voltage to the 'blanking' region is detected, thereby preventing fluctuations in the oxygen pump element current level due to transient increases in sensor cell element voltage and increasing the sensing reliability.

Oxygen concentration sensing apparatus

An oxygen concentration sensing apparatus includes an oxygen pump element and a sensor cell element to be placed in a gas under measurement, and a device for generating a voltage value command indicating a voltage to be generated across electrodes of the sensor cell element. A current limit device is provided so that the supply of the voltage value command is stopped to decrease a pump current to the oxygen pump element gradually when the voltage generated across the electrodes of the sensor cell element exceeds a first predetermined voltage, and the pump current to the oxygen pump element is reduced immediately when the voltage generated across the electrodes of the sensor cell element exceeds a second predetermined voltage which is higher than the first predetermined voltage.

An air intake side secondary air supply system for an internal combustion engine having an air intake side secondary air supply system includes an oxygen concentration sensor, and controls a duty ratio of opening and closing of an open/close valve disposed in the air intake side secondary air supply passage by determining a valve open period within each duty cycle of control operation in accordance with a result of comparison between the level of the output signal of the oxygen concentration sensor and a level corresponding to a target air-fuel ratio. The duty ratio of opening and closing of the open/close valve is maintained within a predetermined duty ratio range so as to improve effectiveness of the control of the secondary air supply as well as to avoid the generation of over lean or over rich mixture.

Air intake side secondary air supply system for an internal combustion

An air/fuel ratio control system for an internal combustion engine having an air supply system for controlling the air/fuel ratio of mixture to be supplied to the engine, and an oxygen concentration sensing device for sensing the oxygen concentration in the exhaust gas of the internal combustion engine. The oxygen concentration sensing device includes a pair of solid electrolyte members operating as an oxygen pump element to which a pump current is supplied, and a sensor cell element. An open/close valve is provided in the air supply system and controlled by a duty ratio control circuit which causes the open/close valve to be opened for a calculated valve open time period in each of successive predetermined cycles in response to a result of detection of air/fuel ratio. When the calculated valve open time period exceeds a predetermined upper limit, the supply of the pump current is stopped so that the blackening phenomenon of the solid electrolyte members is avoided.

Air/fuel ratio control system for an internal combustion engine with a

Method for controlling an oxygen concentration sensor for sensing an oxygen concentration in an exhaust gas of an internal combustion engine, which sensor includes an oxygen pump element and a heater element, comprises steps for controlling a pump current and a heat current control in response to a result of a detection of engine load. When the engine is operating in a predetermined high load range, the supply of the pump current to the oxygen pump element is stopped, and the heat current to the heater element is reduced when the engine operation in the high load range has continued for more than a predetermined time period. The heater current to the heater element is stopped when the engine load is in a first predetermined load range, and when the engine operation in a second load range which is lighter than the first load range has continued for a predetermined time period.

Method for controlling an oxygen concentration sensor for sensing an

An air intake side secondary air supply system for an internal combustion engine has an air intake system using a carburetor and an air intake side secondary air supply passage leading downstream of the carburetor. The passage includes an oxygen concentration sensor producing an output signal whose level is substantially proportional to an oxygen concentration of the exhaust gas. A control means for controlling a flow control valve is disposed in the air intake side secondary air supply passage and operates in accordance to the output signal of the oxygen concentration sensor. In a variation of the invention, the feedback control of air-fuel ratio using the output signal of the oxygen concentration sensor is effected only when the engine operational state is in a predetermined operational region.

An air intake side secondary air supply system for an internal combustion engine having an air intake side secondary air supply passage and an O.sub.2 sensor controls a duty ratio of opening and closing of an open/close valve disposed in the air intake side secondary air supply passage in accordance with a detected air-fuel ratio of mixture by means of an output signal of the O.sub.2 sensor. The system sets a base valve open period of the open/close valve every predetermined period and decreases the base valve open period by a first predetermined correction amount when the detected air-fuel ratio is leaner than a target air-fuel ratio, and increases the base valve open period by a second predetermined correction amount when the detected air-fuel ratio is richer than the target air-fuel ratio.

An oxygen concentration sensing device and an air/fuel ratio control system for an internal combustion engine which include a pair of solid electrolyte members having oxygen ion permeability which are arranged to face each other to form a restricted region between them. One of the solid electrolyte members is operative as an oxygen pump element when a pump current is supplied across the electrodes thereof. The sensing device is provided with a current supply part including a limit command circuit which generates a current stop command signal when the magnitude of the pump current exceeds a reference limit level. With the current stop command signal, the supply of the pump current is stopped so as to prevent an overcurrent to the oxygen pump element. The air/fuel ratio control system includes an air/fuel ratio detection part and an air/fuel ratio control part operated by an air/fuel ratio detection signal. The detection of the air/fuel ratio and the supply of the pump current are stopped under a predetermined operating condition of the engine.

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Wako, Japan

Minoru Muroya