Hitachi, Ltd.

Takashi Mukaihira

Toshio Ishii

Kazuya Kawano

Kiyoshi Miura

Yutaka Takaku

Noboru Sugiura

Ryoichi Kobayashi

Akihito Numata

Nobuo Kurihara

Seiji Asano

Masayoshi Kaneyasu

A diagnostic system in which the accuracy of the diagnosis of the deterioration state of a catalyst in a catalytic converter for cleaning the exhaust gas of an internal combustion engine is enhanced without incurring a rise in cost. The temperature of the catalyst is estimated using the operating-state signal (for example, the flow rate of intake air or the width of a fuel injection pulse) of the engine by a diagnostic device. The conversion efficiency of the catalyst calculated from the outputs of oxygen sensors is corrected using the estimated temperature by the diagnostic device. The deterioration state of the catalyst is diagnosed on the basis of the corrected temperature by the diagnostic device.

System for diagnosing deterioration of catalyst

A diagnostic and control system first checks the current operation status of the vehicle engine, when a malfunction or abnormal condition is detected by diagnostic sensors. A selection of optimum corrective measures is then made and carried out taking into account the safety of the vehicle, based on current operational status of the engine. For this purpose, a set of prioritized corrective measures is determined beforehand for each of the individual monitored items, according to detected changes in the engine operating status. The individual control measures are selected considering the safety of the vehicle, possible measures to correct the malfunction, assuring vehicle operability, and maintaining appropriate engine operating parameters such as exhaust gas mixture, fuel consumption and the like.

Control method and apparatus for diagnosing vehicles

A conversion efficiency of a catalyst is determined by a cross correlation function of a cross-correlation between an output of an oxygen sensor at the upstream of the catalyst and an output of an oxygen sensor at the downstream of the catalyst, to thereby monitor deterioration index of the catalyst. Then, an air and fuel ratio is obtained from at least one of the outputs of the two oxygen sensors, to thereby adjust a fuel supply quantity, so that the fuel supply quantity can be controlled even during a period when the catalyst is being analyzed, without deviating the air and fuel ratio from a target air and fuel ratio.

Internal combustion engine controller with exhaust gas purification

Provided is an internal combustion engine malfunction diagnosis apparatus capable of diagnosing the deterioration of an internal combustion engine with a high accuracy and capable of diagnosing deterioration of a fluctuation factor detection section of the engine with a high accuracy in irrespective of the engine speed. According to one embodiment of the present invention, there is provided a malfunction diagnosis apparatus for an internal combustion engine comprises: a crank angle detection sensor for detecting a crank angle of the internal combustion engine; a fluctuation factor measurement means for measuring a state of a fluctuation factor of the internal combustion engine; an angular-based data sampling section for sampling data of an output signal from the fluctuation factor measurement means at a predetermined rotation angle of a crank shaft in accordance with a crank angle signal from the crank angle detection sensor; a malfunction judgement section for judging a malfunction of the internal combustion engine on the basis of data sampled by the angular-based data sampling section; a time-based data sampling section for sampling an output signal from the fluctuation factor measurement means at every lapse of a predetermined constant time; and a fluctuation factor measurement means deterioration judgement section for judging deterioration of the fluctuation factor measurement means on the basis of data sampled by the time-based data sampling section.

Malfunction diagnosis apparatus for internal combustion engine

A catalytic diagnostic apparatus for determining whether a catalyst of an internal combustion engine has deteriorated as disclosed. Air-fuel ratio sensors are placed at the upstream and downstream sides of the catalytic converter, and the output signal from the upstream air-fuel sensor is used to control the air-fuel mixture provided to the engine via the fuel injectors, in a conventional closed loop operation. Diagnosis of the condition of the catalytic converter is performed only when selected engine operating parameters fall within a predetermined diagnostic range. When the engine is operated in the diagnostic range, the condition of the catalytic converter is analyzed by calculating a deterioration index based on a comparison of the variation of the output signals from the upstream and downstream air-fuel ratio sensors. In a preferred embodiment, a look-up table is provided to correct the deterioration index, based on the intake air flow rate to the engine, and on the cyclic frequency of the variation of the downstream air-fuel ratio sensor.

Diagnostic apparatus for catalytic converter of an internal combustion

An apparatus for combustion condition diagnosis has an ionic current detecting circuit for measuring a voltage at the secondary side of the ignition coil of an engine during a plurality of time periods during one operation cycle including a period in which an internal pressure of a cylinder of the engine becomes maximum, under a normal combustion condition. A window generation circuit is provided for establishing the time periods, an integration circuit is provided for integration processing of the measured voltage during each time period, a ROM stores a list indicating combustion condition corresponding to the integrated value for the each time period, and a CPU diagnoses the combustion condition based on the integrated value for the each time period and the list of combustion conditions, in order to decrease erroneous judgement and perform more adequate combustion condition diagnosis.

Combustion condition diagnosis utilizing multiple sampling of ionic

A system which is capable of diagnosing the deterioration condition of an engine exhaust gas purifying device has front and rear air/fuel ratio sensors for detecting the air/fuel ratio of the exhaust gas upstream and downstream of the catalyst, an autocorrelation function calculation for calculating the autocorrelation function .phi.xx of an output signal from the front air/fuel ratio sensor to output the maximum values (.phi.xx)max of the autocorrelation function .phi.xx at predetermined intervals, each maximum value (.phi.xx)max being in each of the predetermined intervals. A cross-correlation function calculator calculates the cross-correlation function .phi.xy between the output signals from the front and rear air/fuel ratio sensors to output the maximum values (.phi.xy)max of the mutual correlation function .phi.xy at predetermined intervals, each maximum value (.phi.xy)max being in each of the predetermined intervals therefore. The ratios between the maximum values (.phi.xy)max and (.phi.xx)max (successive deterioration index .PHI..sub.i) are calculated to determine the deterioration condition of the catalyst by comparing the ratio with a predetermined reference value.

System for diagnosing engine exhaust gas purifying device and system for

An ignition current conduction time control apparatus, comprising power transistors for producing a spark for ignition at the ignition plugs, and a controller for applying ignition signals to the power transistors, wherein the saturated state of the power transistors is eliminated by controlling the start time of current conduction time of said ignition signals applied to the power transistors according to the internal resistance values of the ignition coils, thereby eliminating the heat generation of the ignition coils.

Ignition current conduction time control apparatus for internal

During an abnormal stop condition of an internal combustion engine, the semiconductor devices which control the supply of current to the ignition coils during a dwell time are subject to damage by a high transient current. To prevent this, at least one predetermined time interval is selected on the basis of detected engine temperatures and/or battery supply voltage level and this selected time interval is compared to a time period between reference pulses from a crank angle sensor. When the time period between reference pulses exceeds the selected time interval, a stop condition of the engine is indicated and the semiconductor devices which supply ignition current are controlled to shorten the dwell time or entirely stop the supply of current to the ignition coils.

Growing community of inventors

Katsuta, Japan

Takashi Mukaihira