Toyota Jidosha Kabushiki Kaisha

Shin Adachi

Hideo Miyagi

Shuichi Hanai

Noriyuki Iden

Yuichi Kohara

Fumiaki Ohya

Koji Fukushima

Noritake Mitsutani

Tokiji Ito

Hidetoshi Amano

Tokiji Itoh

Takayuki Sugiyama

A failure test apparatus for a fuel-vapor purging system for adsorbing fuel vapor in a fuel tank into a canister and for purging fuel to an intake system of an internal combustion engine as needed. The purging system has at least one valve. A first test unit provides a differential pressure between the inside and the outside of the fuel-vapor purging system, measures the internal pressure with the fuel-vapor purging system in an airtight condition, and determines whether a leak exists in the fuel-vapor purging system from the behavior of the internal pressure. The test by the first test unit involves a differential-pressure forming process of creating a differential pressure between the inside and the outside of the fuel-vapor purging system, a sealing process of making the fuel-vapor purging system airtight when the differential pressure exists, and a differential-pressure releasing process for releasing the differential pressure. In association with one or more of the processes, a second test unit measures the internal pressure of the fuel-vapor purging system to detect a failure in any valve actuated in one of the processes based on the behavior of the internal pressure.

Failure test apparatus for fuel-vapor purging system

An improved diagnosis apparatus for detecting leakage of a fuel vapor purge system that purges fuel vapor from a fuel tank to an intake passage of an engine. The apparatus includes a pressure sensor and a purge valve. The pressure sensor detects the pressure in the purge system. The purge valve connects the purge system with the intake passage for lowering the purge system pressure to a predetermined pressure level. After the purge system pressure is lowered to the predetermined level, the purge system is sealed. The apparatus measures the rate of pressure change immediately after the purge system is sealed. The apparatus subsequently measures the rate of pressure change when the purge system pressure reaches a second reference pressure value and computes the ratio of the rates. The apparatus diagnoses whether there is a leak in the purge system based on the ratio and the rate of pressure change at the second reference pressure value.

Diagnosis apparatus for fuel vapor purge system

An air-fuel ratio control apparatus for an internal combustion engine has an oxygen sensor, a first operational means, a second operational means, a maximum and minimum setting means, an air-fuel ratio correcting means, a maximum and minimum magnifying means, and a maximum and a minimum returning means. When an air-fuel ratio learning value calculated by the second operational means reaches a maximum or minimum limit set by the maximum and minimum setting means, an air-fuel ratio feedback correction value is measured for a predetermined time. The maximum and minimum magnifying means increases the maximum or decreases the minimum limit of the air-fuel learning value in response to a deviation of fuel injection amount from a fuel injection amount requested for maintaining a target air-fuel ratio. The maximum and minimum returning means returns the maximum or minimum limit of the air-fuel ratio learning value to a predetermined basic maximum or minimum limit, when a predetermined condition continues for a predetermined time. An emission condition, or an emission amount exhausted from the internal combustion engine, is improved by the above-mentioned control.

Air-fuel ratio control apparatus for an internal combustion engine and a control method of the air-fuel ratio control apparatus

In a diagnostic apparatus for an internal combustion engine, an electronic control unit recognizes occurrence of a misfire in the engine based on fluctuations of the rotational speed of a crankshaft detected by a rotation speed sensor. Based on the detected incidences of misfire, the electronic control unit performs diagnostics. The electronic control unit turns on a warning light when, after the first diagnosis of the presence of an abnormality, a second diagnosis of the presence of an abnormality is made without the return of the engine to the normal state being recognized after a restart of the engine.

Internal combustion engine diagnostic apparatus

The device according to the present invention determines whether the catalytic converter has deteriorated based on the outputs of an upstream air-fuel ratio sensor and a downstream air-fuel ratio sensor only when the flow rate of the intake air is within an allowable flow range. Further, the allowable range is determined in accordance with operating conditions of the engine, for example, the temperature of the catalytic converter. Since the O.sub.2 storage capability of the catalytic converter changes in accordance with the temperature of the catalytic converter, different determination results may be obtained for the same catalytic converter if the determination is carried out at different temperature. In this invention, for example, the flow range is selected in accordance with the temperature of the catalytic converter in such a manner that a normal catalytic converter is always determined as being normal and a deteriorated catalytic converter is always determined as being deteriorated. Therefore, in the present invention, the deterioration of the catalytic converter is correctly determined regardless of a change in the operating conditions of the engine.

Device for determining deterioration of a catalytic converter for an

An internal combustion engine is provided with a mechanically operated supercharger in kinematic connection with a crankshaft the engine. The engine is provided with a system for controlling the effect of supercharger, such as a by-pass control valve. A timer is provided for detecting a predetermined short period after the engine is switched to an acceleration condition from the preceding deceleration condition with a fuel-cut, or after a moderate acceleration has begun. The system for controlling the effect of the supercharging is so controlled that the effect of supercharging is weakened during that period.

System for controlling intake pressure in a supercharged internal

An internal combustion engine provided with a mechanically operated supercharger in kinematic connection with a crankshaft the engine. The engine is provided with a system for controlling the effect of supercharging, such as a by-pass control valve. A timer is provided for detecting a predetermined short period after the engine is switched to an acceleration condition from the preceding deceleration condition with a fuel-cut, or after a moderate acceleration has begun. The system for controlling the effect of the supercharging is so controlled that the effect of supercharging is weakened during that period.

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Toyota, Japan

Shin Adachi