Honda Giken Kogyo Kabushiki Kaisha

Satoshi Kiso

Takashi Isobe

Takashi Yamaguchi

Sachito Fujimoto

Hideo Moriwaki

Akira Hashimoto

Yoshiaki Matsuzono

Takashi Iwamoto

Kojiro Tsutsumi

Hiroyuki Ando

Manabu Niki

An abnormality detecting device for an evaporative fuel processing system is disclosed. The evaporative fuel processing system includes a fuel tank, a canister for trapping evaporative fuel generated in the fuel tank, a charging passage for connecting the fuel tank and the canister, a tank pressure regulating valve provided in the charging passage, a bypass passage bypassing the tank pressure regulating valve, a bypass valve provided in the bypass passage, and a pressure sensor provided in the fuel tank or in the charging passage at a position between the tank pressure regulating valve and the fuel tank. The pressure in the canister is reduced to a pressure which is lower than the atmospheric pressure in the condition where a valve closing command signal for the bypass valve is output. It is determined that the tank pressure regulating valve or the bypass valve is abnormal, when the pressure detected by the pressure sensor becomes equal to or less than a predetermined threshold during execution of the pressure reduction in the canister.

Abnormality detecting device for evaporative fuel processing system

An abnormality detecting device for an evaporative fuel processing system is disclosed. The evaporative fuel processing system includes a fuel tank, a canister for trapping evaporative fuel generated in the fuel tank, a charging passage for connecting the fuel tank and the canister, an on-off valve provided in the charging passage for opening and closing the charging passage, and a pressure sensor provided in the charging passage at a position between the on-off valve and the fuel tank. A pressure in the canister is reduced to a pressure which is lower than the atmospheric pressure in the condition where the on-off valve is open. The on-off valve is closed at the time of completion of the pressure reduction, and it is determined that the charging passage is clogged between the pressure sensor and the fuel tank, when an amount of change in pressure detected by the pressure sensor is less than a predetermined change amount after closing the on-off valve.

An abnormality diagnosis apparatus for performing a leak check of an evaporative fuel processing system which includes a fuel tank, a canister for storing evaporative fuel generated in the fuel tank, a purging passage for connecting the canister to an intake system of an internal combustion engine, and a purge control valve provided in the purging passage. A process of reducing the pressure in the evaporative fuel processing system is executed with a limited flow rate of gases passing through the purge control valve when performing the leak check in an idling condition of the engine. The limited flow rate is set to a value equal to or smaller than a predetermined flow rate which is smaller than the maximum flow rate applied to the leak check performed in operating conditions other than the idling condition. The leak check is performed on the basis of a change in the pressure in the evaporative fuel processing system after the pressure reduction process.

Abnormality diagnosis apparatus for evaporative fuel processing system

An evaporated fuel treatment apparatus having a correction checking means for detecting the state of change in the internal pressure of the fuel tank when the fuel tank is closed after being placed under atmospheric pressure, a leakage checking means for detecting the state of change in the internal pressure of the fuel tank when the fuel tank is closed after being placed under a negative pressure, and a judgement means for judging the presence or absence of leakage in the fuel tank on the basis of the detection results obtained by the leakage checking means and the correction checking means. The apparatus includes calculating means for calculating the amount of fuel consumption at the time of correction checking and the amount of fuel consumption at the time of leakage checking, and judgement prohibiting means for prohibiting a judgement of the presence or absence of leakage from being made by the judgement means in cases where the amounts of fuel consumption calculated at the time of correction checking and at the time of leakage checking are substantially different. As a result, a judgement of the presence or absence of leakage in the tank system is prevented from being performed in cases where such a judgement might be inaccurate.

Evaporated fuel treatment apparatus for internal combustion engine

An evaporated fuel treatment apparatus that has a leakage checking means that detects the conditions of change in the internal pressure of the fuel tank when said fuel tank is closed after being placed under a negative pressure, and a judgement means that judges the presence or absence of leakage in the fuel tank on the basis of the detection results obtained by the leakage checking means and correction checking means. The apparatus further includes a pressure variation checking means which detects the degree of pressure variation in the fuel tank, and then opens the fuel tank to the atmosphere and judges whether or not the pressure inside the fuel tank has dropped. Judgement prohibition means is provided that prohibits a judgement of the presence or absence of leakage from being made by the judgment means in response to a judgement by the pressure variation checking means that the pressure has dropped. Accordingly, a judgement of the presence or absence of leakage in the tank system is prevented from being performed in cases where such a judgement might be inaccurate.

The present invention enables a large leak to be accurately detected by providing an evaporated fuel treatment apparatus for an internal combustion engine. The apparatus comprises the evaporated fuel discharge prevention system including a fuel tank, a canister having an opening to the atmosphere, a passage allowing the fuel tank to communicate with the canister, a purging passage allowing the canister to communicate with the intake manifold of the engine. The apparatus also comprises a pressure sensor for detecting the pressure of the evaporated fuel discharge prevention system, and a controller coupled to the pressure sensor for judging the presence of a first leak in the evaporated fuel discharge prevention system if a change in the pressure from the pressure sensor is small. The controller further checks a change in the pressure from said pressure sensor when closing said system after placing said system under negative pressure. The controller judges the presence of a large leak if the first leak is judged and the pressure increases instantaneously upon closing said system.

An evaporated fuel leak detection apparatus for an internal combustion engine that has a fuel tank, a canister with an opening to the atmosphere, a charging passage that causes the fuel tank to communicate with the canister, a pressure adjustment valve installed in the charging passage, an internal pressure sensor installed on the upstream side of the pressure adjustment valve to detect the internal pressure of the fuel tank, and a controller that detects leakage in the fuel tank system on the upstream side of the pressure adjustment valve in accordance with the output of the internal pressure sensor. The controller judges that there is no leakage in cases where the internal pressure sensor indicates a negative pressure, and the vehicle is not in a high-load operating state or when variation in atmospheric pressure is less than a predetermined amount.

Evaporated fuel leak detection apparatus

An evaporated fuel treatment apparatus that includes a fuel tank, a canister with an opening to the atmosphere, a charging passage that causes the fuel tank to communicate with the canister, a purging passage that causes the canister to communicate with the intake manifold of the internal combustion engine, a pressure adjustment valve installed in the charging passage, a bypass valve installed in a passage that bypasses the pressure adjustment valve, a purge control valve installed in the purging passage, a vent shut valve capable of opening and closing the opening port, an internal pressure sensor for detecting the internal pressure of the fuel tank, and a controller that opens the fuel tank to atmospheric pressure or opens the fuel tank to a negative pressure by controlling the bypass valve, purge control valve, and vent shut valve. The apparatus of the invention detects the presence or absence of leakage on the basis of the change in negative pressure that occurs after the fuel tank has been placed under a negative pressure.

In an evaporated fuel treatment device for an internal combustion engine which has a fuel tank, a canister having an interior and an opening that opens the interior to the atmosphere, and which adsorbs evaporated fuel generated inside the fuel tank, a charging passage that communicates with the fuel tank and with the canister, a pressure adjustment valve provided in the charging passage, an internal pressure sensor provided upstream from the pressure adjustment valve to detect and output the vapor pressure inside the fuel tank, and a fuel tank system leakage detector that detects leakage in the fuel tank system on the upstream side of the pressure adjustment valve according to the output of the sensor, the device having at least a first stored reference value for a first leak diameter constituting an object of detection and a second stored reference value for a second leak diameter constituting an object of detection, and the leakage detector configured to detect the presence or absence of leakage by comparing the output of the internal pressure sensor with the first and second reference values.

Evaporated fuel treatment device

An evaporative fuel-processing system for an internal combustion engine has an evaporative emission control system. An ECU carries out negative pressurization of the interior of the evaporative emission control system, by opening a purge control valve and closing a vent shut valve, and determines presence/absence of leakage from the evaporative emission control system, based on a rate of decrease in negative pressure within the system, by closing a purge control valve. Before the negative pressurization, the interior of the evaporative emission control system is opened to the atmosphere, and during the open-to-atmosphere, a pressure state within the fuel tank is estimated based on a rate of change in an output from a pressure sensor which senses pressure within the evaporative emission control system. The ECU determines whether the evaporative emission control system is normal, based on the estimated pressure state.

Evaporative fuel-processing system for internal combustion engines

An evaporative fuel-processing system for an internal combustion engine has an evaporative emission control system and a pressure sensor. An ECU carries out negative pressurization of the interior of the evaporative emission control system, by opening a purge control valve and closing a vent shut valve. The purge control valve is closed over a predetermined time period after the interior of the evaporative emission control system is brought into the predetermined negatively pressurized state, and a rate of decrease in negative pressure within the evaporative emission control system is detected. Then, it is determined whether or not there is leakage from the evaporative emission control system, based on the detected rate of decrease in the negative pressure, and at least one detected pressure value at at least one predetermined time point within the predetermined time period over which the purge control valve is closed.

Growing community of inventors

Tochigi, Japan

Satoshi Kiso