Toyota Jidosha Kabushiki Kaisha

Takanori Sasaki

Keiichiro Aoki

Go Hayashita

Tetsushi Suzuki

Atsunori Kumagai

Shoichi Tateyama

Yuji Miyoshi

Hideo Yahagi

Isamu Nakada

A correction device for an air/fuel ratio sensor in the present invention, the sensor issuing an output according to an air/fuel ratio and installed on the downstream from catalyst of the exhaust passage, has air/fuel ratio control means for controlling an air/fuel ratio of an exhaust gas on the upstream side from a catalyst to switch between a rich air/fuel ratio which is richer and a lean air/fuel ratio which is leaner than a stoichiometric air/fuel ratio. Moreover, correction means for correcting an output of the sensor in accordance with a difference between the output of the sensor during a predetermined period during air/fuel ratio control by the air/fuel ratio control means, and a reference output corresponding to a stoichiometric air/fuel ratio, is provided.

Correction device for air/fuel ratio sensor

A control device for an internal combustion engine, equipped with: an exhaust purification catalyst provided in the exhaust passage of the internal combustion engine and capable of absorbing oxygen; a downstream air-fuel ratio sensor provided downstream from the exhaust purification catalyst in the direction of the exhaust flow; and an engine control device that controls the internal combustion engine in response to the output from the downstream air-fuel ratio sensor. The downstream air-fuel ratio sensor is configured such that the applied voltage for which the output current is zero changes in response to the exhaust air-fuel ratio, and such that when the exhaust air-fuel ratio equals the theoretical air-fuel ratio and the applied voltage in the downstream air-fuel ratio sensor is increased, the output current increases in conjunction therewith. When the air-fuel ratio of the exhaust gas is detected by the downstream air-fuel ratio sensor, the applied voltage in the downstream air-fuel ratio sensor is fixed at a constant voltage, with this constant voltage being a voltage for which the output current is zero when the exhaust air-fuel ratio is a predetermined air-fuel ratio that is leaner than the theoretical air-fuel ratio.

Control device for internal combustion engine

In this invention, an EMF oxygen sensor is subjected to an activation process applying unidirectional voltage between an atmosphere electrode and an exhaust electrode thereof. A control device controlling the oxygen sensor in which a voltage was applied with the atmosphere electrode being positive, additionally applies unidirectional voltage between the electrodes to make the atmosphere electrode positive, for example, when the oxygen sensor was used under an environment in which the air-fuel ratio of the internal combustion engine was rich relative to the theoretical air-fuel ratio. Conversely, a control device controlling the oxygen sensor in which a voltage was applied to make the atmosphere electrode negative, additionally applies unidirectional voltage between the electrodes to make the atmosphere electrode negative, for example, when the oxygen sensor was used under an environment in which the air-fuel ratio was lean relative to the theoretical air-fuel ratio.

Oxygen sensor and oxygen sensor control device

In an exhaust path of an internal combustion engine, a catalyst, a first air-fuel ratio sensor installed upstream thereof, and a second air-fuel ratio sensor installed downstream thereof are disposed. An air-fuel ratio of the engine is controlled to a rich air-fuel ratio or a lean air-fuel ratio. In a state that is determined as a state where the catalyst stores oxygen to an upper limit after the air-fuel ratio is switched to the lean air-fuel ratio from the rich air-fuel ratio, or a state where the catalyst releases oxygen to a lower limit after the air-fuel ratio is switched to the rich air-fuel ratio from the lean air-fuel ratio, a first output from the first air-fuel ratio sensor, and a second output from the second air-fuel ratio sensor are detected and based on a difference therebetween the output of the first air-fuel ratio sensor is corrected.

An oxygen amount (an oxygen storage amount OSA) stored by metal cerium during a storage cycle is obtained based on an output value of an A/F sensor in a time period immediately before an exhaust air-fuel ratio (a downstream side A/F) detected by the A/F sensor shifts to a lean region, and degradation relating to OSC of the three-way catalyst is detected. In the storage cycle, a target air-fuel ratio is set so that an air-fuel ratio of exhaust emission flowing into an S/C changes from rich to lean. Therefore, the downstream side A/F shifts from stoichiometry to the lean region at a time after reaching stoichiometry. When the three-way catalyst degrades, the downstream side A/F shifts to the lean region from stoichiometry at a time. Therefore, the calculated oxygen storage amount OSA becomes extremely smaller as compared with that at a normal time.

Catalyst-degradation detection device

A sensor characteristic correction device is configured to detect a characteristic of a first sensor arranged upstream of a catalystin an exhaust passageof an internal combustion engine, and a characteristic of a second sensor that is an air-fuel sensorarranged downstream of the catalyst, to calculate a first air-fuel ratio based on the characteristic of the first sensor, and calculates a second air-fuel ratio based on the characteristic of the second sensor, to detect, when the catalystis in an inactive state after start-up of the internal combustion engine, a difference between the first characteristic and the second characteristic or a difference between the first air-fuel ratio and the second air-fuel ratio, and to correct the responsiveness of the first or the second sensor in accordance with the difference.

Sensor characteristic correction device

In a control device for an internal combustion engine including an air-fuel ratio sensor that includes a catalyst layer that covers an exhaust gas-side electrode, an oxygen storage capacity of the catalyst layer is acquired based on a sensor output of the air-fuel ratio sensor. The sensor output is corrected if the oxygen storage capacity is higher than a predetermined value and the sensor output is in a predetermined range in the vicinity of the theoretical air-fuel ratio. Preferably, the oxygen storage capacity is calculated by integrating the product of a deviation amount &#x394;A/F of the sensor output with respect to the theoretical air-fuel ratio and a dwell time thereof. A correction period in which a correction operation is performed is set based on the oxygen storage capacity.

The present invention relates to a gas concentration detection apparatus for detecting the concentration of a specific gas component in an exhaust gas emitted from an engine, and forms a deterioration judgment about the gas concentration detection apparatus accurately and immediately. After excess oxygen is discharged by an oxygen pump cell, a NOx concentration detection apparatus, judges whether a NOx sensoris activated. If the NOx sensoris not activated yet, an output increase rate Vu(t) of the NOx sensor cell output N during an increase process of the NOx sensor cell output N is acquired. The present invention judges whether the output increase rate Vu(t) is lower than a predetermined reference value Vth. If the obtained judgment result indicates that Vu(t)&#x3c;Vth, the NOx sensor cellis deteriorated.

Gas concentration detection apparatus

Fuel reforming catalystsgenerate a hydrogen-containing reformed gas when they come into contact with exhaust gas that contains a reforming fuel. Upstream and downstream air-fuel ratio sensorsare respectively installed upstream and downstream of the fuel reforming catalysts. The upstream air-fuel ratio sensoroutputs a upstream sensor signal in accordance with oxygen concentration. The downstream air-fuel ratio sensoroutputs a downstream sensor signal in accordance with oxygen concentration and hydrogen concentration by using zirconia's oxygen detection capability and a change of a diffusion layer's hydrogen-concentration-dependent oxygen detection capability. An ECUdetects the hydrogen concentration without being affected by the oxygen concentration through the use of the upstream sensor signal in which only the oxygen concentration is reflected and the downstream sensor signal in which the oxygen concentration and hydrogen concentration are reflected. This makes it possible to establish a hydrogen concentration detection system with the common air-fuel ratio sensors

Fuel reforming apparatus

It is an object of the present invention to provide a gas concentration detection apparatus that is capable of forming an accurate activity judgment when a gas concentration detection cell begins to detect gas concentration with high accuracy. When warm-up begins at time tin a NOx concentration detection apparatus that achieves NOx concentration detection with a NOx sensor cell after excess oxygen is discharged by an oxygen pump cell, a NOx sensor cell output begins to rise at time t. Subsequently, at time t, an oxygen pump cell output begins to rise. An inflection point appearing in the NOx sensor cell output is then located. At time tat which the inflection point appears, an activity judgment about the NOx sensor cell is formed.

A cylinder head of an internal combustion engine is fitted with rocker arms. Camshafts are disposed so that the rocker arms and cams will be brought into contact with each other. The camshafts are rotatably supported by lower bearings, which supports the camshafts from below, and by upper bearings integrated with a head cover. The head cover is provided with visual observation windows that make it possible to see valve system parts through the head cover. A visual observation window covers for covering the visual observation windows are fixed to the head cover.

Camshaft support structure for internal combustion engine

A camshaft support structure of an internal combustion engine () includes a camshaft () that drives an intake valve () or an exhaust valve (); a head cover () that houses the camshaft (); an upper bearing portion () which is provided on the head cover () and supports the camshaft (); a lower bearing portion () which is attached to the head cover () and makes a pair with the upper bearing portion () to retain the camshaft (); a rocker arm () that transmits driving force from the camshaft () to the intake valve () or the exhaust valve (); and a rocker arm support portion () that inhibits the rocker arm () from falling out of position by being provided near and directly above the rocker arm ().

Camshaft support structure of an internal combustion engine

A lower cam carrier is disposed over a cylinder head and a head cover is disposed thereover. The lower cam carrier has, formed as one therewith, an outer frame superposed with the edge peripheral edge of the cylinder head, and a bridging part provided between opposing sides of the outer frame part. The bridging part has a lower bearing for supporting an intake camshaft and an exhaust camshaft. The head cover has, formed as one therewith, a flange part superposed with the outer frame part and a bearing part opposing the bridging part inside the flange part. The bearing part has an upper bearing that, together with the lower bearing, supports the intake camshaft and the exhaust camshaft.

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Susono, Japan

Takanori Sasaki