Toyota Jidosha Kabushiki Kaisha

Kenji Tashiro

Kazutaka Hattori

Hiroshi Sawada

Yasushi Iwazaki

Masanobu Kanamaru

Akito Adachi

Kimitoshi Murata

Takashi Matsui

Masaya Kawaji

An oxygen sensor is employed for determining whether the exhaust air-fuel ratio is rich or lean. A voltage is applied to the oxygen sensor at device impedance calculation intervals to calculate device impedance. After device impedance calculation, a reverse voltage is applied to the oxygen sensor with a view toward promptly negating the influence of voltage application on the sensor output. Subsequently, the sensor output of the oxygen sensor is sampled at sampling time intervals until it is concluded that the device impedance calculation period is over.

Controller for gas concentration sensor

An air-fuel ratio sensor that outputs a sensor signal used for the feedback control of an air-fuel ratio is provided. It is determined whether an element crack is present by applying a reverse voltage to the air-fuel ratio sensor. The value of the sensor signal output from the air-fuel ratio sensor is corrected during a time period 'A'. The time period 'A' consists of a reverse-voltage application time period in which the reverse voltage is applied, and a return time period &#x201c;T&#x201d; after application of the reverse voltage ends. The return time period &#x201c;T&#x201d; is set based on sensor impedance correlated with the internal resistance of the air-fuel ratio sensor. The return time period &#x201c;T&#x201d; decreases as the sensor impedance decreases.

Method and apparatus for detecting exhaust gas sensor defect

An air-fuel ratio sensor has an exhaust-side electrode and an atmosphere-side electrode. The atmosphere-side electrode is disposed in an atmosphere layer that communicates with the atmosphere. Since the air-fuel ratio sensor is disposed in an exhaust passage, exhaust gas enters the atmosphere layer if a sensor crack occurs. Ordinarily, forward voltage is applied to the air-fuel ratio sensor to obtain an output thereof in accordance with the air-fuel ratio. Immediately after the applied voltage is switched to reverse voltage, sensor current iin accordance with the impedance flows, regardless of the presence/absence of a sensor crack. After that, the sensor current converges to a value ithat is in accordance with the oxygen concentration in the atmosphere layer. The presence/absence of a sensor crack is determined by comparing the value obtained by correcting iby i, with a criterion value.

Failure detection apparatus and failure detection method for exhaust gas sensor

An engine control apparatus includes a first intake valve and a second intake valve provided along an intake passage. First and second actuators drive the respective throttle valves. A setting unit sets a vehicle target speed in the constant cruising speed control mode. A first control unit controls the first actuator so as to maintain the actual vehicle speed at the target speed during the constant cruising speed control mode. An angle sensor detects the angle of the first throttle valve. A mode memory stores information about a plurality of control modes to be used in controlling the second throttle valve. A mode selector selects one of the control modes. Each control mode stored in the mode memory defines the target angle of the second throttle valve that depends on the angle of the first throttle valve. In accordance with the control mode selected by the mode selector, a second control unit controls the second actuator in such a way that the angle of the second throttle valve becomes the target angle determined in accordance with the first throttle valve angle. The control apparatus includes a regulator unit for regulating the first and/or the second control units, so as to control the first throttle valve in accordance with the control mode specified for the constant cruising speed control mode, while the constant speed control mode is in progress.

Growing community of inventors

Susuno, Japan

Kenji Tashiro