Mitsubishi Jidosha Kogyo Kabushiki Kaisha

Hidetsugu Kanao

Kenji Saito

Takuya Matsumoto

Toru Hashimoto

Mitsuhiro Miyake

Tateo Kume

Toshiro Nomura

Satoshi Nagashima

Tomonobu Sakagami

Yoichiro Ando

Yoshiaki Higuchi

Hitoshi Kamura

Yoshiaki Danno

Katsuo Akishino

Osamu Hirako

Takashi Dogahara

Yasuhisa Yoshida

Daisuke Sanbayashi

Takehiko Katsumoto

Takashi Takatsuka

Masahiko Matsuda

Hiroshi Kamada

Taizou Kitada

Nobuaki Shimizu

Yoshinari Fukami

Haruki Fukuda

Takaaki Hirano

Masaji Asada

A failure diagnostic apparatus for an air-fuel ratio detecting device has an exhaust emission purifying device provided in an exhaust passage; an air-fuel ratio detecting unit for detecting the air-fuel ratio of an exhaust gas from the purifying device; a first determination unit for determining that the air-fuel ratio is estimated to be rich for longer than a first predetermined period of time; a second determination unit for determining that the air-fuel ratio is estimated to be lean for longer than a second predetermined period of time; and a failure diagnosis device for determining that the air-fuel ratio detecting device has failed if a variation in the air-fuel ratio, calculated based on the detected air-fuel ratios until both the first and second determination units make the determinations, is equal to or less than a predetermined value.

Failure diagnostic apparatus and method for air-fuel ratio detecting device

When a first restoring pressure amount, measured after a fault diagnosis object region is in a reduced pressure state, exceeds a first or second judgment value, a second restoring pressure amount is measured by releasing the fault diagnosis object region to the atmosphere and then sealing it. When the first restoring pressure amount is between the first and second judgment values, the second restoring pressure amount is compared with a third judgment value. When the first restoring pressure amount exceeds the second judgment value, the second restoring pressure amount is compared with a fourth judgment value. Leak is determined to exist when the first restoring pressure amount exceeds the first judgment value and the second restoring pressure amount does not exceed the third judgment value, or when the first restoring pressure amount exceeds the second judgment value and the second restoring pressure amount does not exceed the fourth judgment value.

Fault diagnosis apparatus of fuel evaporation/dissipation prevention system

In a thermostat failure diagnosis apparatus for an internal combustion engine in which a failure diagnosis of a thermostat can be effectively made, in the case where, after starting of the engine, an intake air quantity of the engine or a parameter related to the intake air quantity is equal to or higher than a predetermined value, and a cooling water temperature is equal to or higher than an intake air temperature (outside air temperature), on the basis of a time in which a rising quantity in the cooling water temperature at an upstream side of the thermostat reaches a predetermined value, or a time in which the cooling water temperature rises to a predetermined temperature, the failure of the thermostat is judged. By this, the failure diagnosis of the thermostat can be rationally made only when the engine generating heat quantity is large to some degree to prevent erroneous diagnosis.

Thermostat failure diagnosis apparatus for internal combustion engine

A failure diagnostic system reduces the internal pressure of a fuel tank to a predetermined negative pressure, seals off the fuel tank from the air, and then determines whether an evaporated fuel processing system has failed or not by monitoring an increase in pressure in the fuel tank. In determination, the failure diagnostic system compares a detected pressure in the fuel tank with a reference value that is increased by a predetermined rate. The failure diagnostic system stops update of the detected pressure if the detected pressure becomes higher than the reference value, and resumes update of the detected pressure if the detected pressure becomes lower than the reference value. It is therefore possible to accurately determine whether the evaporated fuel processing system has failed or not even if the pressure in the fuel tank is rapidly increased.

Failure diagnostic system of evaporated fuel processing system

There is provided a failure diagnostic system of an evaporated fuel processing system, which comprises a first failure diagnostic device that shuts off an evaporated fuel purge passage connecting a fuel tank and an engine intake passage from the air and determines whether there is any leakage from a large hole by monitoring the degree of increase in pressure in the fuel tank in which engine intake negative pressure is introduced; and a second failure diagnostic device that reduces a pressure the fuel tank to a predetermined negative pressure and seals off the fuel tank from the air to carry out failure diagnosis as to whether there is any leakage from a small hole by monitoring the degree of increase in pressure in the fuel tank. An operating range of the second failure diagnostic device is set to substantially include an operating range of the first failure diagnostic device and to be extended from the operating range of the first failure diagnostic device to include a lower intake negative pressure range.

In a thermostat failure diagnosis apparatus for an internal combustion engine in which a failure diagnosis of a thermostat can be effectively made, in the case where, after starting of the engine, an intake air quantity of the engine or a parameter related to the intake air quantity is equal to or higher than a predetermined value, and a cooling water temperature is equal to or higher than an intake air temperature (outside air temperature), on the basis of a time in which a rising quantity in the cooling water temperature at an upstream side of the thermostat reaches a predetermined value, or a time in which the cooling water temperature rises to a predetermined temperature, the failure of the thermostat is judged. By this, the failure diagnosis is not made in the state where an engine generating heat quantity is small so that there is a fear that an erroneous diagnosis occurs, and the failure diagnosis of the thermostat can be rationally made only in the state where the engine generating heat quantity is large to some degree so that there is no fear of erroneous diagnosis.

A fault diagnosing apparatus for evapopurge systems, including a device adapted to detect a pressure in the interior of an evapopassage including a fuel tank, a depressurization device adapted to close a first valve provided in an atmosphere-opened port of a canister and depressurize the interior of the evapopassage by a negative pressure occurring in a suction passage of an internal combustion engine, a repressurization device adapted to close a second valve after the operation of the depressurization device finishes, to repressurize the interior of the evapopassage, and a fault judgement device adapted to allow a judgement, which is based on an output from the pressure detecting device, that an evapopurge system is abnormal to be given on condition that the depressurization and repressurization devices are operated plural times.

Fault diagnosing apparatus for evapopurge systems

A fault diagnosis apparatus for a fuel evaporative emission suppressing system has an electronic control unit which inputs an average value of integral terms for air-fuel ratio feedback control, engine speed, etc. when diagnosis executing conditions are satisfied, and then starts opening operation of a purge control valve. Subsequently, the average value of integral terms, engine speed, etc. are input again. If no substantial change occurs in the average value, etc. with driving of the purge control valve, it is concluded that purge air for fault diagnosis has not been introduced, and that the suppressing system is faulty. In driving the purge control valve, its driving duty ratio is increased by a relatively small increment till the driving duty ratio reaches a predetermined duty ratio. If the system is normal, therefore, a purge-air introduction amount for fault diagnosis is increased by a relatively small increasing degree, to thereby prevent fluctuation of the air-fuel ratio or engine output torque attributable to the purge air introduction. After the driving duty ratio has reached the predetermined duty ratio, the driving duty ratio is increased by a relatively large increment, to thereby rapidly execute the purge-air introduction and fault diagnosis.

Fault diagnosis apparatus for a fuel evaporative emission suppressing

A deterioration diagnostic apparatus for a three-way catalyst includes an electronic control unit, which obtains a frequency of reversals of the changing direction in which the output of an upstream-side O.sub.2 sensor changes, based on the number of times the output voltage of the O.sub.2 sensor crosses a threshold. Also, the control unit obtains a frequency of reversals of the changing direction in which the output of a downstream-side O.sub.2 sensor changes, based on the number of times the output voltage of the downstream-side O.sub.2 sensor crosses upper and lower reversal reference values which are obtained by adding and subtracting a hysteresis constant to and from an average value of input values of the downstream-side O.sub.2 sensor output voltage. The control unit further obtains the ratio of the reversal frequency of the downstream-side sensor output to the reversal frequency of the upstream-side sensor output, and diagnoses deterioration of the three-way catalyst when the reversal frequency ratio has become greater than a predetermined value.

Apparatus for deterioration diagnosis of an exhaust purifying catalyst

A fault diagnosis apparatus for detecting a fault in a fuel evaporative emission suppressing system comprises an electronic control unit. When fault diagnosis execution conditions are fulfilled, the electronic control unit stores an average of integral term values for air-fuel ratio feedback control, operating position of an idling speed control valve, and engine speed, and then actuates a purge control valve of the suppressing system so that the valve opens. In a predetermined time period after the actuation of the purge control valve, the integral term average and the like are stored again. If any changes of the integral term average and other values caused by the actuation of the purge control valve are detected, the suppressing system is concluded to be normal. If no changes are detected, on the other hand, the suppressing system is concluded to be faulty.

An engine cooling device comprises an oil jacket surrounding a cylinder portion of an engine, an oil gallery supplying high-pressure oil to various parts of the engine, and an oil pressure regulator disposed between the oil jacket and the oil gallery to reduce the pressure of the high-pressure oil supplied from the oil gallery and to supply the oil at a reduced pressure to the oil jacket. Thus, the required mechanical strength of the oil jacket can be decreased to decrease the weight of the engine cylinder block.

Growing community of inventors

Aichi, Japan

Hidetsugu Kanao