Abstract: The electronic control unit sets an initial value of an inertia torque equivalent flow rate Qmg as an air flow equivalent to an inertia torque that acts on rotational elements related to a crankshaft 26, and a diminishing rate thereof, based on a shift position SP and coolant temperature Tw after the engine is cranked by a motor generator and the engine speed reaches an idle speed. The electronic control unit controls an the engine speed using an idle speed maintaining flow rate Qisc which is obtained by subtracting the inertia torque equivalent flow rate Qmg from a target idle speed maintaining flow rate Qisc*.

Abstract: Gas containing fuel vapor is purged as purge gas from a canister to an intake passage through a purge line. An ECU computes purge flow rate, which is the flow rate of the purge gas, and computes vapor concentration, which is the concentration of the fuel vapor contained in the purge gas. The ECU obtains a concentration correction value in accordance with the rate of change of the computed purge flow rate. The ECU correct the computed vapor concentration by using the concentration correction value and by taking into consideration of the time at which the purge flow rate is computed and the time at which purge gas having the computed flow rate is drawn into the combustion chamber. The ECU sets the fuel supply amount in accordance with the computed purge flow rate and the corrected vapor concentration. As a result, the accuracy of the air-fuel ratio control during purging is improved.

Abstract: An engine is automatically stopped when a predetermined amount of time has passed with a predetermined stopping condition being fulfilled, even if learning is not yet complete, when an automatic stopping condition of the engine and a learning execution condition of a control amount of the engine during idling have been fulfilled. However, the engine is prohibited from automatically stopping until the learning is complete when the learning history of the control amount has been cleared by battery disconnection or the like and is not stored. Accordingly, it is possible to both simultaneously control an idling stop when the engine is idling and learn the control amount, as well as minimize a strange sensation felt by the driver that arises from an idling stop not being performed.

Abstract: A canister includes an adsorbent, an air layer and an air hole. An ECU obtains a physical status quantity Mgair representing the vapor stored state of the air layer, a physical status quantity Mgcan representing the fuel vapor stored state of the adsorbent, and a physical status quantity Fvptnk representing the vapor generating state in the fuel tank. The ECU then estimates a total vapor flow rate Fvpall purged to an intake system of the engine by using a physical model related to the vapor behaviors. The physical model is based on the obtained physical status quantities. The ECU corrects the fuel supply amount to the engine according to the estimated flow rate Fvpall. As a result, the air-fuel ratio feedback control is readily prevented from being influenced by the fuel vapor purging.

Abstract: A controller for purging an optimal amount of vaporized fuel in accordance with the operating conditions of an engine. The controller presumes the flow rate of the purged gas to be that when a purge valve is fully opened and uses the presumed value to calculate a target flow rate ratio. The controller than uses the target flow rate ratio and the actual intake pressure to calculate a duty ratio. This achieves a purged gas flow rate which compensates for a deviation that results from a characteristic of the purge valve.

Abstract: Gas containing fuel vapor is purged as purge gas from a canister to an intake passage through a purge line. An ECU computes purge flow rate, which is the flow rate of the purge gas, and computes vapor concentration, which is the concentration of the fuel vapor contained in the purge gas. The ECU obtains a concentration correction value in accordance with the rate of change of the computed purge flow rate. The ECU correct the computed vapor concentration by using the concentration correction value and by taking into consideration of the time at which the purge flow rate is computed and the time at which purge gas having the computed flow rate is drawn into the combustion chamber. The ECU sets the fuel supply amount in accordance with the computed purge flow rate and the corrected vapor concentration. As a result, the accuracy of the air-fuel ratio control during purging is improved.

Abstract: A canister includes an adsorbent, an air layer and an air hole. An ECU obtains a physical status quantity Mgair representing the vapor stored state of the air layer, a physical status quantity Mgcan representing the fuel vapor stored state of the adsorbent, and a physical status quantity Fvptnk representing the vapor generating state in the fuel tank. The ECU then estimates a total vapor flow rate Fvpall purged to an intake system of the engine by using a physical model related to the vapor behaviors. The physical model is based on the obtained physical status quantities. The ECU corrects the fuel supply amount to the engine according to the estimated flow rate Fvpall. As a result, the air-fuel ratio feedback control is readily prevented from being influenced by the fuel vapor purging.

Abstract: An evaporation fuel processing mechanism supplies fuel vapor in a fuel tank to a canister via a vapor passage and purges fuel in the canister to an air-intake passage of an internal combustion engine via a purge passage when the internal combustion engine is operated. This mechanism supplies fuel vapor in the fuel tank when refueling to the canister via a breather passage. The breather passage has a pressure sensitive valve that opens in response to a variation in pressure in the fuel tank during refueling. An air-fuel ratio variation limiting apparatus determines whether the pressure sensitive valve is open and limits a variation in the air-fuel ratio when the pressure sensitive valve is open.

Abstract: A controller controls a purge amount adjusting valve provided in a purge passage, thereby purging an amount of vapor in accordance with an operating state from a canister into an intake passage. The controller detects an internal pressure of a fuel tank with a pressure sensor provided therein, and determines the fact that a tank internal pressure control valve provided in a vapor passage is open based on the detection result. When the controller determines that the tank internal pressure control valve is open, the controller can, e.g., fully close the purge amount adjusting valve and then gradually open the opening amount of the purge amount adjusting valve such that an amount of vapor in accordance with the operating state is purged.

Abstract: An air-fuel ratio control apparatus adapted for an internal combustion engine equipped with a purge system. The air-fuel ratio control apparatus estimates the amount of fuel vapor present in a fuel tank from a balance between an estimated produced vapor amount and an estimated purged amount of fuel vapor. When the estimated amount of fuel vapor present is small, the concentration of fuel vapor to be purged is low, so that a base air-fuel ratio feedback coefficient is learned in a period where the estimated value is small. As a result, the base air-fuel ratio feedback coefficient is appropriate learned. Even if the base air-fuel ratio feedback coefficient is learned incorrectly, the air-fuel ratio control apparatus can correct the feedback coefficient. Accordingly, the concentration of the fuel vapor to be purged into the intake air can be detected accurately, thus permitting the base air-fuel ratio feedback coefficient to be maintained at a more appropriate value.

Abstract: An abnormality detector apparatus for an engine water-cooling apparatus has an electronic control unit (ECU) for precisely and quickly determining and detecting an operation abnormality of a thermostat or a water temperature sensor. After the engine is started, the ECU calculates, over time, an engine heat generation quantity, an estimated cooling water temperature or the like on the basis of various engine operating condition parameters, such as cooling water temperature, intake temperature, engine revolution speed, amount of intake air, and the like. After the elapse of a predetermined time, the ECU compares the estimated cooling water temperature and the cooling water temperature actually detected by the water temperature sensor. If the relationship therebetween meets a predetermined condition, the ECU determines whether there is an abnormality in the operating condition of the thermostat and/or the cooling water temperature sensor.

Abstract: The engine of the present invention has a plurality of cylinders that are divided into a first group and a second group. An air flow meter for detecting an amount of air supplied to the engine is provided downstream of an air cleaner in an intake system. A crank angle sensor for detecting a rotational speed of the engine is provided adjacent to a crank shaft. The amount of air distributed to the first group and the amount of air distributed to the second group are calculated based on the detected amount of air and the detected rotational speed of the engine. The amount of fuel injected into the first group and the amount of fuel injected into the second group are corrected according to the calculated amounts of air distributed to the first and second groups.

Abstract: The device for determining deterioration of a catalytic converter includes a catalytic converter disposed in the exhaust gas passage of the engine and an air-fuel ratio sensor disposed on the exhaust gas passage downstream of the catalytic converter. The device performs two types of determining operations based on the length of the output response curve of the downstream air-fuel ratio sensor, one is a deterioration determining operation which determines whether the catalytic converter has deteriorated and the other is a normal determining operation which determines whether the catalytic converter is normal. The device also estimates the temperature of the catalytic converter based on the operating condition of the engine, and sets a deterioration diagnosis intake air flow range and a normal diagnosis intake air flow range in accordance with the estimated temperature of the catalytic converter.

Abstract: The object of the present invention is to provide an apparatus for detecting the deterioration of a three-way catalytic converter which can accurately detect the deterioration degree. The present apparatus is furnished with an upstream A/F sensor installed at the upstream side of the converter and a downstream A/F sensor installed at the downstream side of the converter. The output of the upstream sensor is converted into the converted output for calculating the trajectory length. The trajectory length of the converted output and that of the output of the downstream sensor are respectively calculated, and the deterioration degree of the converter is detected based on these two trajectory lengths to avoid the misjudgment. The detecting accuracy can be better improved by compensating for the aberration of the balance between the oxygen absorbing power and the oxygen releasing power of the converter.

Abstract: In an internal combustion engine in which air-fuel ratio feedback control is performed using an A/F sensor mounted upstream of an exhaust gas purifying catalyst, a deviation in the characteristic of the A/F sensor is estimated and the air-fuel ratio feedback control and catalyst deterioration judging processes are performed accounting for the estimated deviation. If the characteristic of the A/F sensor deviates in an output increasing direction, the amount of fuel correction will become excessively large, and the period from the time an output voltage VAF crosses a target voltage VAFT to the time it returns to the target voltage will become short compared with a normally functioning A/F sensor. On the other hand, if the characteristic of the A/F sensor deviates in an output decreasing direction, the amount of fuel correction will become excessively small, and that period will become long compared with a normally functioning A/F sensor.

Abstract: The object of the present invention is to provide an apparatus for detecting the deterioration of a converter enabled to avoid a misjudgement even though the balance between the oxygen absorbing power and the oxygen releasing power disappears. The present apparatus is furnished with an upstream air-fuel ratio sensor installed at the upstream side of the converter and a downstream air-fuel ratio sensor installed at the downstream side of the converter. The deterioration of the converter is detected in accordance with the trajectory lengths of these sensors, and a parameter which denotes the oxygen balance of the converter is calculated in accordance with the outputs of these sensors. When the value of the parameter is outside a fixed lower limit or a fixed upper limit, the detection for deterioration is inhibited in order to prevent a misjudgement occuring.

Abstract: The device according to the present invention controls air-fuel ratio of the exhaust gas flowing into the catalytic converter in such a manner that the exhaust gas flowing into the catalytic converter fluctuates around a center value on the lean air-fuel ratio side compared to the stoichiometric air-fuel ratio when it performs the determination of deterioration of the catalytic converter. In this condition, the device calculates the rich gas inflow amount which is the amount of HC and CO in the exhaust gas flowing into the catalytic converter and the rich gas outflow amount which is the amount of HC and CO in the exhaust gas flowing out from the catalytic converter. The device, then, determines the degree of deterioration of the catalytic converter based on the calculated values of the rich gas inflow amount and the rich gas outflow amount.

Abstract: A catalyst deterioration detection device for an internal combustion engine, according to the present invention, includes a three-way catalyst mounted in an exhaust passage of the internal combustion engine and having an O.sub.2 storage capability and an air-fuel ratio sensor, mounted upstream of the three-way catalyst, for linearly detecting an air-fuel ratio. An air-fuel ratio feedback control unit, based on the output of the air-fuel ratio sensor, calculates a feedback correction amount consisting of a proportional term for bringing the air-fuel ratio to stoichiometry and an integral term for bringing an integrated value of an error between the air-fuel ratio and stoichiometry to zero. An O.sub.2 sensor, mounted downstream of the three-way catalyst, detects whether the air-fuel ratio is rich or lean. A catalyst deterioration determining unit determines deterioration of the three-way catalyst on the basis of the length of a response curve that the output of the O.sub.

Abstract: The device according to the present invention controls air-fuel ratio of the exhaust gas flowing into the catalytic converter when performing the determination of deterioration of the catalytic converter in such a manner that the amount of oxygen released from a three-way catalytic converter is maintained at a suitable value for determining the deterioration of the converter. When the air-fuel ratio of the exhaust gas flowing into the catalytic converter fluctuates between a rich air-fuel ratio and a lean air-fuel ratio, the catalytic converter absorbs oxygen from the exhaust gas when the air-fuel ratio of the exhaust gas is rich, and releases the absorbed oxygen when the air-fuel ratio of the exhaust gas is lean. According to the present invention, the amount of oxygen released from the catalytic converter during the rich air-fuel ratio period of exhaust gas is controlled to a predetermined amount.

Abstract: 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.