Nippondenso Co., Ltd.

Ubukata Industries Co., Ltd.

Akihiro Nakashima

Hisashi Iida

Shigenori Isomura

Toshiaki Mizuno

Hideki Koseki

Hidehiko Inoue

Kazuhiro Nakai

Takao Tsuji

Satoru Namizaki

A catalyst deterioration detection apparatus having oxygen sensors disposed in the upper stream and the lower stream from a ternary catalyst disposed in the exhaust system of an internal combustion engine, controlling so as to make the air/fuel ratio of the internal combustion engine to be in the neighborhood of a theoretical air/fuel ratio in response to an output signal from at least either of the oxygen sensors, detecting a response delay time from a moment an output signal from the upper stream oxygen sensor has been changed to a moment an output signal from the lower stream oxygen sensor has been changed when the air/fuel ratio of the internal combustion engine is changed from the rich side to the lean side or from the lean side to the rich side, and discrimination that the catalyst has deteriorated if the response delay time is shorter than a predetermined value, the catalyst deterioration detection apparatus including a device for permitting the catalyst deterioration detection apparatus to perform the detection operation if a fact that the internal combustion engine is in a predetermined operation state has been detected and a fact that the air/fuel ration has been converged to the neighborhood of the theoretical air/fuel ratio has been detected.

Apparatus for detecting deterioration of catalyst

A detecting system for condition of a fuel evaporative emission generated in a fuel tank, includes a pressure sensor and a three-way valve for selectively connecting the pressure sensor to atmosphere and the fuel tank. The pressure sensor is initially communicated with the atmosphere to detect an atmospheric pressure P.sub.a (step 110), and subsequently communicated with the fuel tank to detect an internal pressure P.sub.f of the fuel tank (step 130). Based on the atmospheric pressure P.sub.a and the internal pressure P.sub.f of the fuel tank, an amount EVP of the fuel evaporative emission generated in the fuel tank is derived through a map look-up against a preset map (step 150).

Fuel evaporative emission amount detection system

A fuel evaporative emission flow rate detecting system is capable of detecting a small flow rate of the fuel evaporative emission. The system includes an electromagnetic valve (22) in a communication passage (21). The pressure of the fuel evaporative emission in the fuel tank is detected by means of a magnetic flux detector or so forth. A control circuit is responsive to the pressure of the fuel evaporative emission reaching 15 mmHg, for example, while the communication passage (21) is held closed, to open the communication passage (21). On the other hand, the control circuit closes the communication passage when the pressure of the fuel evaporative emission becomes lower than or equal to 8 mmHg. Depending on a period, in which the communication passage (21) is held open, the flow rate of the fuel evaporative emission is calculated.

Gaseous fuel flow rate detecting system

Disclosed is a self-diagnosis apparatus in a fuel evaporation gas scattering preventing system in an internal combustion engine. The apparatus comprises: a canister communicating with a fuel tank and containing therein an absorption material adapted to absorb a fuel evaporation gas in the fuel tank; a discharge path for making the canister communicate with a suction path of an internal combustion engine; an opening/closing device provided in the discharge path for opening/closing the discharge path; an air-fuel ratio detector for detecting an air-fuel ratio of an air-fuel mixture fed to the internal combustion engine; a gas generation quantity detector for detecting a quantity of generation of fuel evaporation gas within the fuel tank; judgment device for controlling the opening/closing device to close/open the discharge path to thereby judge whether abnormality exists or not on the basis of a change in the air-fuel ratio detected by the air-fuel ratio detector upon closing/opening discharge path, when the gas generation quantity detector detects that gas is being generated within the fuel tank; and a warning device for generating a warning when the judgment device proves existence of abnormality.

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Chiryu, Japan

Akihiro Nakashima